Current Evidence on the Potential Role of Endothelial SHP-1 in Pulmonary Vascular Remodeling Associated With Pulmonary Hypertension

Abstract

Pulmonary hypertension (PH) is characterized by an abnormally high pressure within the pulmonary arteries, which can be attributed to various factors. Severe diseases affecting pulmonary vessels may result in heart failure and potentially lead to death; these conditions are linked to significant mortality and unfavorable outcomes. Approximately 1% of adults worldwide have PH, and this condition may affect up to 10% of people older than 65 years. Currently, the mechanisms involved in the development of PH are not fully known and are thought to result from multiple coordinated factors. This lack of understanding remains a bottleneck in clinical practice. Numerous studies have confirmed that pulmonary artery endothelial cell (PAEC) dysfunction plays an important role in occlusive pulmonary vascular remodeling and the pathogenesis of PH. Src homology region 2 domain-containing phosphatase-1 (SHP-1) is a regulatory molecule that negatively modulates various cellular mediators and growth factors, primarily playing a negative regulatory role in signal transduction pathways. This review mainly presents an in-depth exploration of the key signaling pathways through which SHP-1 regulates the expression of endothelial cells (ECs), thereby influencing various physiological functions, including proliferation, migration, oxidative stress, angiogenesis, apoptosis, autophagy, the inflammatory response, and vascular permeability. Furthermore, the potential mechanisms through which endothelial SHP-1 plays a role in pulmonary vascular remodeling in PH are discussed. These findings underscore SHP-1 as an encouraging therapeutic target for preventing and managing PH.

Graphical abstract

Keywords

pulmonary hypertension / SHP-1 / endothelial cells / vascular remodelling

1. Introduction

Pulmonary hypertension refers to a disease that involves increased pulmonary vascular resistance. The pathological process of PH is characterized by pulmonary vascular remodelling, which involves excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells (PAECs), distal pulmonary artery muscularization, vascular occlusion, plexiform lesions, and abnormal accumulation of inflammatory cells [1, 2, 3, 4]. Alterations in pulmonary vascular tone and remodelling contribute to a progressive increase in pulmonary vascular resistance, ultimately culminating in a spectrum of clinical syndromes associated with right heart failure and, in severe cases, death [5]. The diagnostic criteria for haemodynamics are outlined as follows: A mean pulmonary artery pressure (mPAP) of \ge20 mmHg, as assessed through right heart catheterization, indicates the presence of pulmonary hypertension (PH) under resting conditions at sea level [6]. One percent of adults across the globe are afflicted with PH, whereas its prevalence can reach 10% among individuals older than 65 years [7]. Currently, several drugs with vasodilatory effects, such as endothelin, nitric oxide, and prostacyclin, have been successfully developed to treat PH [6, 8].

Recent research has shown that among individuals undergoing standard treatment for PH, the use of sotatercept results in decreased pulmonary vascular resistance and increased haemodynamic metrics and exercise ability, as evaluated using the 6-minute walk test [9, 10]. These findings provide a new potential treatment strategy for PH [11]. Although current treatment methods can improve the quality of life of patients, none are curative, which presents a significant challenge in clinical practice [12]. In the early stages of PH development, EC injury and apoptosis are predominant [13, 14, 15]. Conversely, in the later stages of PH, EC overproliferation and antiapoptotic mechanisms prevail, resulting in significant vascular remodelling [16]. Recent studies have shown that endothelial cell dysfunction, injury, and immune‒inflammatory responses, along with metabolic abnormalities, epigenetic changes, endothelial‒mesenchymal transition (EndMT), and the release of growth factors and chemokines from endothelial cells (ECs), induce the proliferation of SMCs and play a role in the structural changes associated with pulmonary vascular remodelling. This process increases pulmonary artery pressure and pulmonary vascular resistance [17].

Src homology region 2 protein tyrosine phosphatase-1 (SHP-1), which is encoded by the gene protein tyrosine phosphatase non-receptor type 6 (PTPN6), is an essential component of the protein tyrosine phosphatase (PTP) family [18, 19]. SHP-1 functions as a negative regulator in various cellular signalling pathways [19, 20], primarily by dephosphorylating tyrosine residues on various signalling proteins (such as signal transducer and activator of transcription (STAT), protein kinase B (Akt) and Src). This dephosphorylation modulates tumour, inflammatory, and metabolic pathways [21], inhibiting signal transduction by targeting tyrosines in proteins. These factors significantly influence various critical biological activities of related cells and are essential for maintaining normal cellular functions and the integrity of the immune system [18]. Although SHP-1 is predominantly expressed in haematopoietic cells, it has also been identified in nonhaematopoietic cells, such as ECs [22]. Research indicates that bovine aortic ECs contain endogenous SHP-1 [23]. Additionally, this molecule functions as a negative modulator, blocking superoxide generation in these cells [24]. In ECs under hypoxia, SHP-1 inhibits reactive oxygen species (ROS) generation, reduces the stability of hypoxia-inducible factor 1-alpha (HIF-1\alpha), and promotes the secretion of vascular endothelial growth factor (VEGF) to inhibit cell growth [25].

We analysed the cell-type specific expression of SHP-1 based on single-cell RNA-seq data derived from the lung tissue samples of PH mice and retrieved from the GSE154959 dataset in the Gene Expression Omnibus (GEO) database. Specifically, SHP-1 is highly expressed in several immune cell populations, including macrophages, B cells, monocytes, granulocytes and dendritic cells. In contrast, SHP-1 expression is significantly inhibited in ECs, whereas SHP-1 expression is almost absent in nonimmune cells, such as adipocytes, epithelial cells, and hepatocytes (Fig. 1, Ref. [26]). This unique expression profile suggests that SHP-1 is involved primarily in the regulation of immune cell functions. However, its low-level expression in ECs may indicate a specific role in vascular homeostasis or pulmonary vascular remodelling.

Therefore, the aim of this review is to explore the role and mechanisms of PAECs in the pathogenesis of PH. The possible mechanisms of endothelial SHP-1 in PH-related pulmonary vascular remodelling are discussed in detail, which may provide novel therapeutic targets and insights for the prevention and treatment of PH.

2. Role and Mechanisms of PAECs in the Pathogenesis of PH

2.1 Roles of Genetic and Epigenetic Inheritance in PH

The genetic roles and mechanisms of PAECs in PH encompass multiple aspects, including abnormalities in transcription factors [27, 28, 29], mitochondrial dysfunction [30, 31], cell death pathways [30, 32], EndMT [33, 34], genetic variations, and metabolic abnormalities [34, 35]. Together, these mechanisms lead to PAEC dysfunction, which results in changes in the pulmonary vasculature and advances the progression of PH. Importantly, the most frequently identified genetic factor associated with familial PH is bone morphogenetic protein receptor type II (BMPR2) [35]. Some individuals with PH have a genetic predisposition, such as patients carrying a heterozygous abnormality in the gene encoding BMPR2 and a mutation in the activin-like kinase (Alk)-1 receptor [5, 36, 37]. Mutant mice have increased susceptibility to hypoxia-induced PH, along with impaired endothelium-dependent vasodilation within the pulmonary vasculature [38]. Heterozygous Bmpr2 knockout leads to EC injury and persistent PH in mice.

Epigenetic inheritance describes how gene expression can be altered without any modification to the DNA sequence itself. This mechanism is influenced by factors such as DNA methylation, histone modifications, and noncoding RNA [39]. A recent epigenome-wide association study (EWAS) revealed a total of 865,848 differentially methylated cytosine-phosphate-guanine (CpG) sites in the peripheral blood samples of patients suffering from PH [40], underscoring the widespread occurrence of epigenetic dysregulation. Within vascular ECs, modifications to histones are crucial for disease progression. The targeted inhibition of important elements within the histone H3 lysine 4 (H3K4) methyltransferase complex, specifically absent, small, or homeotic 2 (ASH2) and WD repeat-containing protein 5 (WDR5), significantly ameliorates hypoxia-induced PH in mice, confirming the critical role of histone methylation regulation [41].

Furthermore, studies utilizing the pulmonary thromboembolism (PTE) rat model have demonstrated that the miR-124/polypyrimidine tract binding protein 1 (PTBP1)/pyruvate kinase M (PKM) signalling axis facilitates pulmonary artery intimal remodelling through the mediation of metabolic reprogramming [42]. Collectively, these findings indicate that (1) epigenetic mechanisms, including DNA methylation and histone modifications, drive abnormal endothelial cell proliferation and vascular remodelling by regulating the expression of key genes and that (2) energy metabolism disorders resulting from metabolic reprogramming further exacerbate the pathological thickening of the pulmonary artery intima. These two mechanisms may be interrelated and jointly contribute to the progression of pulmonary hypertension.

2.2 Role of PAEC Dysfunction in PH

The primary trigger for PH is the dysfunction of PAECs, which is predominantly characterized by the generation of associated active factors and alterations in coagulation within the pulmonary endothelium. This dysfunction leads to abnormal contractions of the pulmonary vasculature, in situ thrombosis, and the remodelling of vascular structures, ultimately contributing to the onset and progression of PH. This condition represents an endothelial pathological state resulting from an imbalance between substances that induce contraction and those that promote vasodilation [43].

Studies have confirmed that PAEC dysfunction disrupts the pathological proliferation and migration of adjacent PASMCs, ultimately leading to thickening of the vascular wall’s medial layer and a progressive increase in pulmonary vascular resistance [44, 45].

Mice with defects in ECs and haematopoietic cells that encode prolyl-4 hydroxylase 2 (PHD2) exhibit severe occlusive vascular remodelling and right heart failure. In particular, the pulmonary vascular lesions of these mice significantly increased EC proliferation. Reactivation of hypoxia-inducible factor 2\alpha (HIF-2\alpha) signalling in ECs is a crucial factor in the development of PH. Endothelial HIF-2\alpha activation is the primary mechanistic link for the development of PH after PHD2 deficiency [46, 47]. Additionally, a reduction in pulmonary endothelial HIF-2\alpha causes a significant loss of hypoxia-induced PH in these mice [48]. Studies have shown that P-selectin and von Willebrand factor (vWF) are procoagulant factors located on pulmonary ECs. Increases in these factors reflect damage and dysfunction [49, 50].

The above studies elucidate the central role of EC dysfunction in the pathogenesis of PH. This dysfunction leads to pulmonary vasoconstriction, thrombus formation, and medial thickening through an imbalance of active factors, coagulation abnormalities, and HIF-2\alpha-driven vascular remodelling, ultimately resulting in increased pulmonary vascular resistance and right heart failure.

2.3 Role of the Immune Inflammatory Response in PH

In PH, inflammation is characterized by (1) elevated levels of cytokines, chemokines, and adipokines and (2) varying degrees of inflammatory and immune cell infiltration surrounding and within the walls of small pulmonary arteries [51]. Furthermore, one study revealed the presence of tertiary lymphoid tissues (tLTs) in the lungs of patients with idiopathic pulmonary arterial hypertension (IPAH), which may be associated with aberrant immune system activation and autoantibody production [52]. Another study demonstrated that anti-endothelial cell antibodies (AECAs) are detectable in patients with systemic sclerosis (SSc) and are correlated with a greater incidence of vascular lesions and related symptoms. AECAs can activate ECs and lead to apoptosis in patients. Additionally, PH can also occur in patients, contributing to increased mortality [53]. A study conducted by Sasaki N’s team [54] suggested that the induction of PAEC apoptosis by a combination of anti-endothelial cell antibodies and activated natural killer cells may play a crucial role in the vascular damage associated with PH in patients with mixed connective tissue disease. These findings underscore the significant role of the immune system in PH.

2.4 Role of Oxidative Stress in PH

Oxidative stress is recognized as a critical factor leading to EC injury and functional impairment [55]. Increases in ROS production lead to an imbalance in the signalling between reactive nitrogen species (RNS) and nitric oxide (NO) [56], as well as to DNA damage [57]. This imbalance results in abnormal proliferation, injury, and apoptosis of ECs. Oxidative stress can also promote the development of PH by disrupting the NO signalling pathway. As a crucial vasodilatory mediator, the synthesis of NO is regulated primarily by endothelial nitric oxide synthase (eNOS). Under pathological conditions associated with PH, dysfunction of eNOS leads to its uncoupling, subsequently disrupting NO signalling and significantly impairing the capacity for vasodilation. This pathological alteration not only exacerbates vasoconstrictive responses but also further accelerates the progression of pulmonary arterial hypertension [56].

2.5 Role of Autophagy in PH

Research has demonstrated that oestradiol directly inhibits the proliferation of ECs and improves haemodynamics. By enhancing mitochondrial autophagy, oestradiol also inhibits PH [58]. Conversely, it enhances EC angiogenesis in foetal lambs with persistent PH, which reduces the expression of the autophagy protein beclin-1, leading to autophagy defects [59]. Moreover, autophagy accelerates the transition from an apoptotic phenotype to a hyperproliferative phenotype in pulmonary vascular ECs associated with HIV-related PH [60].

Singh et al. [61] reported increased expression and activity of fatty acid synthase (FAS) in hypoxic human pulmonary artery smooth muscle cells (HPASMCs). The inhibition of FAS promotes HPASMC apoptosis and reduces autophagy, which reduces pulmonary vascular remodelling and endothelial dysfunction [61].

2.6 Role of EndMT in PH

EndMT induced by dysfunctional PAECs is considered the initial step and a key pathological factor in the occurrence of PH [62]. In PH, EndMT directly promotes structural changes in the vascular wall by causing PAECs to lose their endothelial characteristics and acquire the migratory and proliferative abilities of mesenchymal cells [33, 62, 63]. In PH associated with congenital heart disease, high shear stress (HSS) can directly induce EndMT, thereby initiating vascular remodelling [64]. Numerous studies have demonstrated that apoptosis, inflammation, and metabolic abnormalities, such as oxidative stress in PAECs, can induce EndMT. These findings suggest that EndMT may serve as a compensatory response following endothelial injury [65]. This dual regulatory role positions SHP-1 as a pivotal therapeutic target for modulating vascular remodelling processes [66].

3. The Expression and Regulation of SHP-1 in eECs

3.1 Expression Characteristics of SHP-1 in ECs

Studies have demonstrated that SHP-1 is expressed in various epithelial tissues, including haematopoietic cells and ECs [24, 67]; however, its expression level in ECs remains relatively low. In human microvascular endothelial cells (HMECs), SHP-1 is predominantly localized in the nucleus, with only moderate expression observed in the cytoplasm [25].

3.2 Core Role of SHP-1 in Vascular Homeostasis and Disease

SHP-1 plays a critical role in ECs by protecting them from the upregulation of adhesion molecules and the harmful effects of thrombosis under inflammatory conditions. Under hypoxic or ischaemic conditions, SHP-1 promotes the development of blood vessels by suppressing oxidative stress. In ischaemic illnesses, SHP-1 suppresses the production of ROS, which in turn inhibits the proliferation and survival of ECs [25].

For example, in a diabetic mouse model, hyperglycaemia impairs the vascular regenerative capacity of ischaemic muscles by upregulating SHP-1 expression in ECs, which inhibits the activity of angiogenic factors [68]. In an in vitro model of chronic obstructive pulmonary disease (COPD), the expression level of SHP-1 was significantly decreased. SHP-1 overexpression reversed the effects of cigarette smoke extract (CSE) on endothelial cell migration, epithelial‒mesenchymal transition (EMT), and the production of proinflammatory factors. Moreover, it mitigated the inflammatory response by inhibiting the P65 and PI3K/AKT signalling pathways [69]. In the diabetic state, SHP-1 promotes endothelial cell senescence and contributes to abnormal collateral vessel formation by diminishing the proangiogenic effects of nuclear factor erythroid 2-related factor 2 (Nrf2) and VEGF, ultimately impeding blood flow reperfusion. However, the overexpression of dominant-negative SHP-1 (dnSHP-1) effectively reverses these pathological effects [62]. In diabetic peripheral arterial disease, SHP-1 reduces endothelial cell migration and capillary formation by negatively regulating the vascular endothelial growth factor receptor 2 (VEGFR2) and platelet derived growth factor receptor beta (PDGFR-\beta) signalling pathways [70].

Comprehensive evidence indicates that maintaining moderately high SHP-1 expression is crucial for controlling inflammation and ensuring endothelial homeostasis. The lack of expression of this molecule has emerged as a common pathological feature in various vascular diseases. These findings underscore the importance of SHP-1 as a vital target for research in the context of vascular diseases and inflammatory responses.

4. The Key Signalling Pathway That Regulates the Expression of SHP-1

4.1 SHP-1 Regulates the Phosphorylation Level of VEGFR2

4.1.1 Target Action

SHP-1 can indirectly affect the phosphorylation of VEGFR2 by dephosphorylating Src family kinases (such as Lyn and Fyn) [71]. This dephosphorylation depends on the interaction between SHP-1 and the SH2 domain of Src family receptors [72]. Upon VEGF stimulation, the phosphatase activity of SHP-1 is activated, leading to the dephosphorylation of specific tyrosine residues (such as Y996, Y1059, and Y1175) on VEGFR2, thereby inhibiting VEGFR2 signalling. This dephosphorylation attenuates VEGFR2-mediated downstream signalling pathways, such as the activation of extracellular signal-regulated kinase (ERK) and Akt, consequently suppressing the proliferation and DNA synthesis of vascular ECs [71]. Cellular communication network factor 1 (CCN1), also known as cysteine-rich protein sixty-one, is a stromal cell protein that interacts with integrins and is secreted by the cell. Cardiovascular system development is highly important in human life. CCN1 enhances SHP-1 activity by binding to VEGFR2, leading to VEGFR2 dephosphorylation and the inhibition of endothelial cell proliferation [73].

4.1.2 Evidence of Inhibiting Angiogenesis Through the Regulation of SHP-1

Furthermore, this study revealed that acetyl-11-keto-boswellic acid (AKBA) can upregulate the expression and activity of SHP-1. The upregulation of SHP-1 by AKBA leads to reduced VEGF expression and downregulated phosphorylation of VEGFR2 and STAT3, thus inhibiting angiogenesis. Overall, these findings underscore the critical role of SHP-1 in regulating endothelial cell angiogenesis [74].

4.1.3 Evidence to Support That Regulating SHP-1 Inhibits Vascular Permeability

Clearly distinguishing the mechanisms underlying changes in vascular permeability between PH and acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is crucial. Both ALI and ARDS are marked by a breakdown of the alveolar-capillary barrier, which is evident through a strong inflammatory reaction that causes damage to both endothelial and alveolar epithelial cells injury, ultimately culminating in the accumulation of protein-rich pulmonary edema [75]. ARDS signifies the critical phase of ALI, marked by significant formation of hyaline membranes, collapse of alveoli, and persistent hypoxemia [76, 77]. Conversely, the changes in vascular permeability seen in PH mainly stem from endothelial dysfunction that occurs throughout the chronic remodeling of the pulmonary vasculature. This condition presents as perivascular edema rather than as exudation into the alveolar spaces, and the underlying mechanisms differ fundamentally from the acute inflammatory damage seen in ALI/ARDS [78].

Cytokine TNF superfamily member 15 (TNFSF15) is produced primarily by vascular ECs, and receptor activation leads to trimerization with VEGFR2 and death receptor 3 (DR3). This process affects the activity of SHP-1 phosphatase, which further inhibits the phosphorylation of VEGFR2 [79]. In addition, Chu et al. [80] reported that thrombospondin-1 (TSP-1) binds to VEGFR2 via its interaction with STAT3 while recruiting SHP-1 to inhibit the phosphorylation of VEGFR2; thus, TSP-1 reduces the phosphorylation level of VEGFR2 and VEGF-induced endothelial cell migration. The thrombospondin type 1 repeat (TSR) domain inhibits tube formation [80].

Additionally, SHP-1 phosphatase activity is enhanced by a novel aliphatic isohydroxamic acid ester derivative (WMJ-S-001), resulting in the inhibition of VEGFR2 phosphorylation within the VEGF-A-VEGFR2 signalling pathway, which ultimately decreases the cytogenic activity of vascular ECs [81].

4.1.4 Role of SHP-1 in the Pathological Environment

Studies have shown that hyperglycaemic and hypoxic environments upregulate the phosphatase activity of SHP-1, which inhibits VEGF signalling. This process impairs the functional ability of ECs and inhibits angiogenesis [25, 82, 83]. In addition, N(\epsilon)-carboxymethyl lysine (CML) activates ROS signalling via NADPH oxidase, which in turn enhances SHP-1 activity. Consequently, SHP-1 damages ECs by dephosphorylating VEGFR-2, which results in EC dysfunction [84].

4.1.5 Gene Intervention and Animal Model Validation

In an in vitro study, SHP-1 inhibition promoted the ability of TNF-\alpha to impede the VEGF-driven phosphorylation of VEGFR-2, which promoted the growth of ECs. In a rat model of hind limb ischaemia, the expression levels of SHP-1 and VEGF were elevated in vivo. Treatment with siRNA that suppressed SHP-1 gene expression significantly increased both VEGFR-2 phosphorylation and capillary density, indicating that SHP-1 is a negative regulator of angiogenesis [85]. Treatment with VEGF resulted in the c-Src kinase-dependent activation of SHP-1 phosphatase activity. Inhibition of SHP-1 with siRNA or c-Src results in elevated tyrosine phosphorylation levels of VEGFR-2 and phosphorylation extracellular signal-regulated kinase (pERK), which enhances DNA synthesis and promotes EC proliferation. These results show that SHP-1 is essential for the regulation of ECs [80].

4.2 SHP-1 Regulates the JAK2/STAT3 Signalling Pathway

4.2.1 Target Action

As a tyrosine phosphatase with an SH2 domain, SHP-1 can directly bind to JAK2 and dephosphorylate its substrate STAT3. As a result, it negatively regulates the activation of the JAK/STAT3 signalling pathway, which helps maintain ECs under normal conditions [86, 87].

4.2.2 Abnormal Regulation of SHP-1 Under Pathological Conditions

The levels and activity of SHP-1 control critical functions of ECs, such as proliferation, migration, and angiogenesis. For example, in a high-glucose environment, the inhibition of SHP-1 activity can result in hyperactivation of the JAK/STAT3 signalling pathway, leading to abnormal endothelial cell injury and angiogenesis [88]. Additionally, the expression and activity of SHP-1 are modulated by various factors. Under certain pathological conditions, SHP-1 expression may be downregulated, or its activity may be suppressed, resulting in the aberrant activation of the JAK/STAT3 signalling pathway [89, 90, 91].

4.2.3 Pharmacological Intervention and Therapeutic Potential

This study revealed that naringenin can inhibit JAK2/STAT3 signalling pathway activation while increasing the expression of SHP-1, which improved hypertension during pregnancy. Sufficient evidence indicates that SHP-1 must be expressed and activated to suppress oxidative stress, inflammatory responses, and JAK2/STAT3 signalling pathway activity. This alleviation of damage to vascular endothelial cell damage and vasoconstriction further regulates the development and differentiation of ECs [92]. Angiopoietin 1 (Ang1) inhibits cell proliferation; in this context, the induction of SHP-1 dampens Ang1-mediated interleukin 6 (IL-6)-induced stimulation of the JAK/STAT3 signalling pathway, thus reducing IL-6-induced endothelial cell permeability and suppressing the vascular immune‒inflammatory response [93]. Moreover, some studies have shown that inhibiting Phloretin activates SHP-1 to phosphorylate STAT3. This process can ultimately induce apoptosis and autophagy in vascular ECs [94, 95].

4.3 SHP-1 Regulates ERK Phosphorylation

4.3.1 Target Action

SHP-1 can bind to epidermal growth factor receptor (EGFR) and dephosphorylate its downstream substrates, thereby suppressing EGFR-mediated ERK activation [96]. SHP-1 suppresses angiogenesis and inflammatory responses through the dephosphorylation of key signalling molecules, such as ERK and c-Jun N-terminal kinase (JNK) [97, 98].

4.3.2 Functional Verification

Stimulation of bovine aortic ECs with VEGF and epidermal growth factor (EGF) significantly increased the phosphorylation of ERK. However, treatment with TNF-\alpha for 10 minutes attenuated the phosphorylation of ERK. Importantly, the overexpression of SHP-1 effectively prevented the inhibition of ERK phosphorylation induced by TNF-\alpha. TNF-\alpha blocks the growth factor-induced phosphorylation of ERK-induced EC proliferation by activating SHP-1. The activation of SHP-1 suppresses the phosphorylation of E23RK induced by growth factors, including VEGF, EGF, and platelet-derived growth factor (PDGF). Endothelial cell proliferation, differentiation, and transformation are downregulated [23, 70].

4.3.3 Animal Model Validation

Knockout of the connexin 37 (Cx37) gene in mice might increase SHP-1 activity, which in turn could lead to the dephosphorylation of proteins such as myosin light chain 2 (MLC2), ERK, and protein kinase B through various mechanisms. The angiotensin II (Ang II) signalling cascade involves the phosphorylation of proteins generated after the activation of Ang II at the AT1 receptor (AT1R) in ECs. Protein dephosphorylation may interfere with important cellular physiological processes, such as contraction, proliferation, and survival [99].

4.4 SHP-1 is Involved in Regulating the Levels of ROS and HIF-1

4.4.1 The Oxygen-dependent Regulatory Mechanism of HIF-1\alpha

HIF-1 consists of an oxygen-regulated \alpha subunit and a constitutively expressed \beta subunit [100, 101]. Under normoxia, prolyl hydroxylase facilitates the degradation of HIF-1\alpha, whereas hypoxia blocks this process, leading to the stabilization and accumulation of HIF-1\alpha [102, 103]. HIF-1\alpha is an important transcription factor under low-oxygen conditions. It can regulate the production of VEGF [104, 105].

4.4.2 Regulation of the ROS/HIF-1\alpha/VEGF Axis by SHP-1

Under hypoxic conditions, SHP-1 knockdown increases ROS in ECs and further induces ROS to upregulate the expression of the HIF-1\alpha protein [25]. The synthesis and production of VEGF are increased when SHP-1 is knocked down. Moreover, SHP-1 also negatively regulates the production of ROS. ROS increase the stability of HIF-1\alphaby inhibiting the enzyme activity of prolyl hydroxylase, leading to its degradation [106]. Thus, SHP-1 knockdown leads to an increase in ROS, which stabilizes HIF-1\alpha. In summary, SHP-1 regulates cell proliferation and VEGF synthesis by altering the HIF-1\alpha and ROS levels [25].

4.5 Other Avenues

Under hyperglycaemic conditions, SHP-1 is activated and binds to DR3, the receptor for tumour necrosis factor ligand-related molecule 1A (TL1A). This activation inhibits the dephosphorylation of Src by SHP-1. Consequently, when glucose levels are elevated, SHP-1 binds to the receptor of TL1A, also called death receptor 3 (DR3). This action of SHP-1 prevents the dephosphorylation of Src, which then activates vascular endothelial-cadherin (VE-cadherin). As a result, EC integrity is impaired, leading to vascular leakage [107].

SHP-1 plays a crucial role in maintaining vascular haemostasis within the body. During the inflammation of ECs caused by TNF-\alpha, SHP-1 inhibition enhances interactions between platelets and ECs, ultimately leading to arterial thrombosis. This autoinhibitory feedback mechanism of phosphatases is believed to prevent excessive inflammation and thrombosis [108]. TNF-\alpha inhibits VEGF- and EGF-stimulated EC proliferation via SHP-1 activation. Under hypoxia, blocking tumor necrosis factor receptor 1 (TNFR-1) or SHP-1 in human umbilical vein endothelial cells (HUVECs) upregulated the expression of proangiogenic genes (VEGFR2 and eNOS) and a prosurvival gene (Bcl-xL) while downregulating the expression of a proapoptotic gene (Bax). Inhibiting TNFR-1 or SHP-1 with siRNA leads to increased HUVEC growth and differentiation [109].

Many findings present strong evidence that SHP-1 negatively regulates endothelial cell function via tyrosine phosphatase activity. The activation of SHP-1 inhibits the coagulant activity of ECs; however, loss of function or expression is able to attenuate this effect (Table 1, Ref. [23, 24, 25, 70, 73, 74, 79, 80, 81, 82, 83, 84, 85, 88, 92, 93, 94, 95, 97, 98, 99, 107, 108, 109, 110]).

5. Potential Mechanism of Endothelial SHP-1 in PH-Related Pulmonary Vascular Remodelling

5.1 Suppression of the Proliferation, Migration and Angiogenesis of ECs

SHP-1 plays a crucial role in regulating EC function and angiogenesis by modulating the phosphorylation of VEGFR2 and its downstream signalling pathways. Molecules such as CCN1, limonin, AKBA, and WMJ-S-001 activate SHP-1 and inhibit VEGFR2 phosphorylation, thereby suppressing endothelial cell proliferation, migration, and angiogenesis [73, 74, 81]. Under conditions such as hyperglycaemia and hypoxia, the activity of SHP-1 is increased. By suppressing the overactivation of the VEGF and JAK/STAT3 signalling pathways, SHP-1 contributes to endothelial cell dysfunction and impaired angiogenesis [25, 82, 83]. Furthermore, the inhibition of SHP-1 in HUVECs promotes VEGFR2 expression and drives endothelial cell proliferation [109]. The activation of SHP-1 induces dephosphorylation of the ERK protein, thereby modulating endothelial cell proliferation [23, 70, 99]. Under hypoxic conditions, SHP-1 regulates endothelial cell proliferation by controlling HIF-1\alpha and ROS levels [25, 102, 103]. Collectively, these studies demonstrate that the deletion or reduction of SHP-1 leads to excessive endothelial cell proliferation and migration as well as abnormal vascular formation.

5.2 Regulating Endothelial Apoptosis and Autophagy

Phloretin inhibits the phosphorylation of STAT3 by activating SHP-1, which induces apoptosis and autophagy in ECs [94, 95]. Under hypoxic conditions, the inhibition of TNFR-1 or SHP-1 in HUVECs significantly increases the expression of the antiapoptotic factor Bcl-xL while decreasing the expression of the proapoptotic factor Bax, thereby effectively suppressing apoptosis in these cells [109].

5.3 Regulating the Inflammatory Response

SHP-1 suppresses angiogenesis and inflammatory responses by dephosphorylating key signalling molecules, including ERK and JNK [97, 98]. Studies have shown that Ang1 activates SHP-1 to inhibit IL-6-induced endothelial cell permeability and inflammatory responses [108]. Furthermore, the inhibition of SHP-1 exacerbates TNF-\alpha-induced endothelial inflammation, while its self-inhibitory feedback mechanism serves to prevent excessive inflammatory activation [108].

5.4 Regulation of Vascular Permeability

Under hyperglycaemic conditions, SHP-1 is activated and binds to DR3, impairing its ability to dephosphorylate Src. This process induces the activation of VE-cadherin, which destabilizes endothelial cell integrity and contributes to vascular leakage [107].

5.5 Regulation of the Oxidative Stress Response

In HUVECs, SHP-1 negatively regulates Rac1 activation by suppressing PI3K activity, thereby modulating NAD(P)H oxidase-dependent superoxide production and significantly reducing oxidative stress levels in ECs [24].

5.6 Summary

In summary, endothelial SHP-1 may suppress the development and progression of PH through multiple mechanisms. Specifically, SHP-1 inhibits EC migration and proliferation, reducing key drivers of vascular remodelling; SHP-1 modulates immune-inflammatory responses and oxidative stress to mitigate endothelial cell damage; SHP-1 suppresses pathological angiogenesis by inhibiting signalling pathways such as VEGF; and SHP-1 regulates vascular permeability while inhibiting apoptosis and autophagy to maintain endothelial cell function and stability. These combined effects inhibit pulmonary vascular remodelling and prevent the progression of PH, highlighting SHP-1 as a potential therapeutic target for PH treatment (Fig. 2).

6. Therapeutic Prospects of SHP-1 Activators/Inhibitors in Vascular Diseases

6.1 Therapeutic Potential of SHP-1 Activators

The SHP-1 activators exert antiproliferative and pro-apoptotic effects by inhibiting B cell receptor (BCR) signalling pathway, as evidenced by the downregulation of p-Lyn. This inhibition may also indirectly influence tumour angiogenesis [111, 112]. The overexpression of SHP-1 counteracts the migration of endothelial cells and the release of inflammatory factors triggered by CSE, indicating that SHP-1 has a protective function in chronic inflammatory vascular conditions, including vascular lesions associated with COPD [69]. Angiogenesis is influenced by SHP-1 through the regulation of TGF-\beta1 signalling, potentially facilitating the development of collateral circulation in models of ischaemia [113].

6.2 Potential Risks of SHP-1 Inhibitors

In certain types of cancer, the activation of SHP-1 may foster a microenvironment that is favourable for tumours, indicating that caution is warranted when using SHP-1 inhibitors to treat vascular-related tumours [87]. SHP-1 suppresses overly active immune responses within Treg cells; nonetheless, a lack of this protein might result in T-cell impairment, which can influence the development of vascular autoimmune disorders [114].

6.3 Summary

Modulators of SHP-1 have the potential to play dual roles in vascular disease treatment: they may enhance the healing of atherosclerotic or diabetic vascular lesions by providing anti-inflammatory benefits and protecting endothelial cells as an activator, whereas they may facilitate the regeneration of blood vessels in ischaemic tissues under certain circumstances as an inhibitor. Additional research is essential to clarify the mechanisms specific to different tissues and explore avenues for clinical application.

7. Conclusion and Clinical Implications

On the basis of current knowledge, SHP-1 is suspected to play a significant role in the development and maintenance of pulmonary endothelial dysfunction associated with PH, potentially offering new therapeutic innovations for this condition. Several experiments could be conducted to test this hypothesis, including in situ studies on tissues from patients with and without PH to verify the expression and localization of the SHP-1 protein in various cell types within remodelled pulmonary artery walls. Because PH is typically diagnosed at advanced stages and patients are often treated with multiple therapeutic agents, tracking SHP-1 expression and its targets in preclinical models of PH at different stages of its development is crucial. Such analyses include using the chronic Sugen-hypoxia model, models severe PH induced by monocrotaline, and the combination model in rats. Furthermore, in vitro experiments could be designed to investigate the molecular mechanisms regulated by SHP-1 in dysfunctional PAECs from PH patients by manipulating SHP-1 expression levels in PAECs from patients without PH. Using haemodynamic data from adult knockout or conditionally overexpressing SHP-1 mice or rats and evaluating the efficacy of SHP-1 agonist treatments in preclinical models are both essential to strengthening these observations. In these in vivo studies, it will be important to thoroughly assess cardiac function to ensure that these approaches do not negatively impact ventricular performance, including adaptive hypertrophy of the right ventricle. Taken together, these data could be used to determine whether restoring SHP-1 expression is a promising novel intervention in the treatment of PH.

References

[1] Ruopp NF, Cockrill BA. Diagnosis and Treatment of Pulmonary Arterial Hypertension: A Review. JAMA. 2022; 327: 1379–1391. https://doi.org/10.1001/jama.2022.4402.

[2] Rabinovitch M. Molecular pathogenesis of pulmonary arterial hypertension. The Journal of Clinical Investigation. 2012; 122: 4306–4313. https://doi.org/10.1172/JCI60658.

[3] Stacher E, Graham BB, Hunt JM, Gandjeva A, Groshong SD, McLaughlin VV, et al. Modern age pathology of pulmonary arterial hypertension. American Journal of Respiratory and Critical Care Medicine. 2012; 186: 261–272. https://doi.org/10.1164/rccm.201201-0164OC.

[4] Rabinovitch M. Pathobiology of pulmonary hypertension. Annual Review of Pathology. 2007; 2: 369–399. https://doi.org/10.1146/annurev.pathol.2.010506.092033.

[5] Evans CE, Cober ND, Dai Z, Stewart DJ, Zhao YY. Endothelial cells in the pathogenesis of pulmonary arterial hypertension. The European Respiratory Journal. 2021; 58: 2003957. https://doi.org/10.1183/13993003.03957-2020.

[6] Humbert M, Kovacs G, Hoeper MM, Badagliacca R, Berger RMF, Brida M, et al. 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension. The European Respiratory Journal. 2023; 61: 2200879. https://doi.org/10.1183/13993003.00879-2022.

[7] Hoeper MM, Humbert M, Souza R, Idrees M, Kawut SM, Sliwa-Hahnle K, et al. A global view of pulmonary hypertension. The Lancet. Respiratory Medicine. 2016; 4: 306–322. https://doi.org/10.1016/S2213-2600(15)00543-3.

[8] Humbert M, Kovacs G, Hoeper MM, Badagliacca R, Berger RMF, Brida M, et al. 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension. European Heart Journal. 2022; 43: 3618–3731. https://doi.org/10.1093/eurheartj/ehac237.

[9] Humbert M, McLaughlin V, Gibbs JSR, Gomberg-Maitland M, Hoeper MM, Preston IR, et al. Sotatercept for the Treatment of Pulmonary Arterial Hypertension. The New England Journal of Medicine. 2021; 384: 1204–1215. https://doi.org/10.1056/NEJMoa2024277.

[10] Hoeper MM, Badesch DB, Ghofrani HA, Gibbs JSR, Gomberg-Maitland M, McLaughlin VV, et al. Phase 3 Trial of Sotatercept for Treatment of Pulmonary Arterial Hypertension. The New England Journal of Medicine. 2023; 388: 1478–1490. https://doi.org/10.1056/NEJMoa2213558.

[11] Madonna R, Biondi F. Perspectives on Sotatercept in Pulmonary Arterial Hypertension. Journal of Clinical Medicine. 2024; 13: 6463. https://doi.org/10.3390/jcm13216463.

[12] Zhang MQ, Wang CC, Pang XB, Shi JZ, Li HR, Xie XM, et al. Role of macrophages in pulmonary arterial hypertension. Frontiers in Immunology. 2023; 14: 1152881. https://doi.org/10.3389/fimmu.2023.1152881.

[13] Lévy M, Maurey C, Celermajer DS, Vouhé PR, Danel C, Bonnet D, et al. Impaired apoptosis of pulmonary endothelial cells is associated with intimal proliferation and irreversibility of pulmonary hypertension in congenital heart disease. Journal of the American College of Cardiology. 2007; 49: 803–810. https://doi.org/10.1016/j.jacc.2006.09.049.

[14] Masri FA, Xu W, Comhair SAA, Asosingh K, Koo M, Vasanji A, et al. Hyperproliferative apoptosis-resistant endothelial cells in idiopathic pulmonary arterial hypertension. American Journal of Physiology. Lung Cellular and Molecular Physiology. 2007; 293: L548–L554. https://doi.org/10.1152/ajplung.00428.2006.

[15] Sakao S, Tatsumi K, Voelkel NF. Endothelial cells and pulmonary arterial hypertension: apoptosis, proliferation, interaction and transdifferentiation. Respiratory Research. 2009; 10: 95. https://doi.org/10.1186/1465-9921-10-95.

[16] Ranchoux B, Harvey LD, Ayon RJ, Babicheva A, Bonnet S, Chan SY, et al. Endothelial dysfunction in pulmonary arterial hypertension: an evolving landscape (2017 Grover Conference Series). Pulmonary Circulation. 2018; 8: 2045893217752912. https://doi.org/10.1177/2045893217752912.

[17] Humbert M, Guignabert C, Bonnet S, Dorfmüller P, Klinger JR, Nicolls MR, et al. Pathology and pathobiology of pulmonary hypertension: state of the art and research perspectives. The European Respiratory Journal. 2019; 53: 1801887. https://doi.org/10.1183/13993003.01887-2018.

[18] Tonks NK. Protein tyrosine phosphatases: from genes, to function, to disease. Nature Reviews. Molecular Cell Biology. 2006; 7: 833–846. https://doi.org/10.1038/nrm2039.

[19] Poole AW, Jones ML. A SHPing tale: perspectives on the regulation of SHP-1 and SHP-2 tyrosine phosphatases by the C-terminal tail. Cellular Signalling. 2005; 17: 1323–1332. https://doi.org/10.1016/j.cellsig.2005.05.016.

[20] Wang N, Tan S, Liu H, Nie Y, Wang M, Liu H, et al. SHP-1 negatively regulates LPS-induced M1 polarization, phagocytic activity, inflammation and oxidative stress in primary macrophages of Chinese tongue sole (Cynoglossussemilaevis). Fish & Shellfish Immunology. 2025; 163: 110375. https://doi.org/10.1016/j.fsi.2025.110375.

[21] Zhao Y, Jiang L. Targeting SHP1 and SHP2 to suppress tumors and enhance immunosurveillance. Trends in Cell Biology. 2025; 35: 667–677. https://doi.org/10.1016/j.tcb.2024.10.008.

[22] Yu Z, Su L, Hoglinger O, Jaramillo ML, Banville D, Shen SH. SHP-1 associates with both platelet-derived growth factor receptor and the p85 subunit of phosphatidylinositol 3-kinase. The Journal of Biological Chemistry. 1998; 273: 3687–3694. https://doi.org/10.1074/jbc.273.6.3687.

[23] Nakagami H, Cui TX, Iwai M, Shiuchi T, Takeda-Matsubara Y, Wu L, et al. Tumor necrosis factor-alpha inhibits growth factor-mediated cell proliferation through SHP-1 activation in endothelial cells. Arteriosclerosis, Thrombosis, and Vascular Biology. 2002; 22: 238–242. https://doi.org/10.1161/hq0202.104001.

[24] Krötz F, Engelbrecht B, Buerkle MA, Bassermann F, Bridell H, Gloe T, et al. The tyrosine phosphatase, SHP-1, is a negative regulator of endothelial superoxide formation. Journal of the American College of Cardiology. 2005; 45: 1700–1706. https://doi.org/10.1016/j.jacc.2005.02.039.

[25] Alig SK, Stampnik Y, Pircher J, Rotter R, Gaitzsch E, Ribeiro A, et al. The tyrosine phosphatase SHP-1 regulates hypoxia inducible factor-1α (HIF-1α) protein levels in endothelial cells under hypoxia. PloS One. 2015; 10: e0121113. https://doi.org/10.1371/journal.pone.0121113.

[26] The datasets generated during the current study are available in the GEO repository. 2021. Available at: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE154959 (Accessed: 26 January 2025).

[27] Lee DH, Kim M, Chang SS, Lee R, Jang AJ, Kim J, et al. PPARγ/ETV2 axis regulates endothelial-to-mesenchymal transition in pulmonary hypertension. Pulmonary Circulation. 2024; 14: e12448. https://doi.org/10.1002/pul2.12448.

[28] Toyama T, Kudryashova TV, Ichihara A, Lenna S, Looney A, Shen Y, et al. GATA6 coordinates cross-talk between BMP10 and oxidative stress axis in pulmonary arterial hypertension. Scientific Reports. 2023; 13: 6593. https://doi.org/10.1038/s41598-023-33779-8.

[29] Park CS, Kim SH, Yang HY, Kim JH, Schermuly RT, Cho YS, et al. Sox17 Deficiency Promotes Pulmonary Arterial Hypertension via HGF/c-Met Signaling. Circulation Research. 2022; 131: 792–806. https://doi.org/10.1161/CIRCRESAHA.122.320845.

[30] Zhang H, Chen L, Li J, Sun J, Zhao Q, Wang S, et al. STAT3 phosphorylation at Tyr705 affects DRP1 (dynamin-related protein 1) controlled-mitochondrial fission during the development of apoptotic-resistance in pulmonary arterial endothelial cells. Genes & Genomics. 2024; 46: 751–762. https://doi.org/10.1007/s13258-024-01522-w.

[31] Xia H, Duan J, Li M, Chen N, Zhong W, Zhou Y, et al. CD137 Signaling Mediates Pulmonary Artery Endothelial Cell Proliferation Under Hypoxia By Regulating Mitochondrial Dynamics. Journal of Cardiovascular Translational Research. 2024; 17: 859–869. https://doi.org/10.1007/s12265-024-10493-y.

[32] Jiang Y, Huang J, Xia Y, Sun Z, Hu P, Wang D, et al. Hypoxia activates GPR146 which participates in pulmonary vascular remodeling by promoting pyroptosis of pulmonary artery endothelial cells. European Journal of Pharmacology. 2023; 941: 175502. https://doi.org/10.1016/j.ejphar.2023.175502.

[33] Kang K, Xiang J, Zhang X, Xie Y, Zhou M, Zeng L, et al. N6-methyladenosine modification of KLF2 may contribute to endothelial-to-mesenchymal transition in pulmonary hypertension. Cellular & Molecular Biology Letters. 2024; 29: 69. https://doi.org/10.1186/s11658-024-00590-w.

[34] Austin ED, Aldred MA, Alotaibi M, Gräf S, Nichols WC, Trembath RC, et al. Genetics and precision genomics approaches to pulmonary hypertension. The European Respiratory Journal. 2024; 64: 2401370. https://doi.org/10.1183/13993003.01370-2024.

[35] Deliu N, Das R, May A, Newman J, Steele J, Duckworth M, et al. StratosPHere 2: study protocol for a response-adaptive randomised placebo-controlled phase II trial to evaluate hydroxychloroquine and phenylbutyrate in pulmonary arterial hypertension caused by mutations in BMPR2. Trials. 2024; 25: 680. https://doi.org/10.1186/s13063-024-08485-z.

[36] Girerd B, Montani D, Coulet F, Sztrymf B, Yaici A, Jaïs X, et al. Clinical outcomes of pulmonary arterial hypertension in patients carrying an ACVRL1 (ALK1) mutation. American Journal of Respiratory and Critical Care Medicine. 2010; 181: 851–861. https://doi.org/10.1164/rccm.200908-1284OC.

[37] Thenappan T, Ormiston ML, Ryan JJ, Archer SL. Pulmonary arterial hypertension: pathogenesis and clinical management. BMJ (Clinical Research Ed.). 2018; 360: j5492. https://doi.org/10.1136/bmj.j5492.

[38] Frank DB, Lowery J, Anderson L, Brink M, Reese J, de Caestecker M. Increased susceptibility to hypoxic pulmonary hypertension in Bmpr2 mutant mice is associated with endothelial dysfunction in the pulmonary vasculature. American Journal of Physiology. Lung Cellular and Molecular Physiology. 2008; 294: L98–L109. https://doi.org/10.1152/ajplung.00034.2007.

[39] Dave J, Jagana V, Janostiak R, Bisserier M. Unraveling the epigenetic landscape of pulmonary arterial hypertension: implications for personalized medicine development. Journal of Translational Medicine. 2023; 21: 477. https://doi.org/10.1186/s12967-023-04339-5.

[40] Ulrich A, Wu Y, Draisma H, Wharton J, Swietlik EM, Cebola I, et al. Blood DNA methylation profiling identifies cathepsin Z dysregulation in pulmonary arterial hypertension. Nature Communications. 2024; 15: 330. https://doi.org/10.1038/s41467-023-44683-0.

[41] Chen D, Yang Y, Cheng X, Fang F, Xu G, Yuan Z, et al. Megakaryocytic leukemia 1 directs a histone H3 lysine 4 methyltransferase complex to regulate hypoxic pulmonary hypertension. Hypertension (Dallas, Tex.: 1979). 2015; 65: 821–833. https://doi.org/10.1161/HYPERTENSIONAHA.114.04585.

[42] Yang MX, Wu ZZ, Wu DW, Liao XY, Wu QX, Shao N, et al. miR-124/PTBP1/PKM axis modulates pulmonary artery endothelial metabolism in a pulmonary thromboembolism rat model. Journal of Thoracic Disease. 2025; 17: 2217–2226. https://doi.org/10.21037/jtd-24-1806.

[43] Haworth SG. Role of the endothelium in pulmonary arterial hypertension. Vascular Pharmacology. 2006; 45: 317–325. https://doi.org/10.1016/j.vph.2006.08.006.

[44] Ye L, Wang B, Xu H, Zhang X. The Emerging Therapeutic Role of Prostaglandin E2 Signaling in Pulmonary Hypertension. Metabolites. 2023; 13: 1152. https://doi.org/10.3390/metabo13111152.

[45] Tuder RM. Pulmonary vascular remodeling in pulmonary hypertension. Cell and Tissue Research. 2017; 367: 643–649. https://doi.org/10.1007/s00441-016-2539-y.

[46] Dai Z, Li M, Wharton J, Zhu MM, Zhao YY. Prolyl-4 Hydroxylase 2 (PHD2) Deficiency in Endothelial Cells and Hematopoietic Cells Induces Obliterative Vascular Remodeling and Severe Pulmonary Arterial Hypertension in Mice and Humans Through Hypoxia-Inducible Factor-2α. Circulation. 2016; 133: 2447–2458. https://doi.org/10.1161/CIRCULATIONAHA.116.021494.

[47] Kapitsinou PP, Rajendran G, Astleford L, Michael M, Schonfeld MP, Fields T, et al. The Endothelial Prolyl-4-Hydroxylase Domain 2/Hypoxia-Inducible Factor 2 Axis Regulates Pulmonary Artery Pressure in Mice. Molecular and Cellular Biology. 2016; 36: 1584–1594. https://doi.org/10.1128/MCB.01055-15.

[48] Hu CJ, Poth JM, Zhang H, Flockton A, Laux A, Kumar S, et al. Suppression of HIF2 signalling attenuates the initiation of hypoxia-induced pulmonary hypertension. The European Respiratory Journal. 2019; 54: 1900378. https://doi.org/10.1183/13993003.00378-2019.

[49] Collados MT, Sandoval J, López S, Massó FA, Páez A, Borbolla JR, et al. Characterization of von Willebrand factor in primary pulmonary hypertension. Heart and Vessels. 1999; 14: 246–252. https://doi.org/10.1007/BF01747854.

[50] Müller AM, Skrzynski C, Skipka G, Müller KM. Expression of von Willebrand factor by human pulmonary endothelial cells in vivo. Respiration; International Review of Thoracic Diseases. 2002; 69: 526–533. https://doi.org/10.1159/000066471.

[51] Huertas A, Tu L, Humbert M, Guignabert C. Chronic inflammation within the vascular wall in pulmonary arterial hypertension: more than a spectator. Cardiovascular Research. 2020; 116: 885–893. https://doi.org/10.1093/cvr/cvz308.

[52] Perros F, Dorfmüller P, Montani D, Hammad H, Waelput W, Girerd B, et al. Pulmonary lymphoid neogenesis in idiopathic pulmonary arterial hypertension. American Journal of Respiratory and Critical Care Medicine. 2012; 185: 311–321. https://doi.org/10.1164/rccm.201105-0927OC.

[53] Dib H, Tamby MC, Bussone G, Regent A, Berezné A, Lafine C, et al. Targets of anti-endothelial cell antibodies in pulmonary hypertension and scleroderma. The European Respiratory Journal. 2012; 39: 1405–1414. https://doi.org/10.1183/09031936.00181410.

[54] Sasaki N, Kurose A, Inoue H, Sawai T. A possible role of anti-endothelial cell antibody in the sera of MCTD patients on pulmonary vascular damage relating to pulmonary hypertension. Ryumachi. 2002; 42: 885–894. (In Japanese)

[55] Peng J, Liu B, Ma QL, Luo XJ. Dysfunctional endothelial progenitor cells in cardiovascular diseases: role of NADPH oxidase. Journal of Cardiovascular Pharmacology. 2015; 65: 80–87. https://doi.org/10.1097/FJC.0000000000000166.

[56] Tabima DM, Frizzell S, Gladwin MT. Reactive oxygen and nitrogen species in pulmonary hypertension. Free Radical Biology & Medicine. 2012; 52: 1970–1986. https://doi.org/10.1016/j.freeradbiomed.2012.02.041.

[57] Ranchoux B, Meloche J, Paulin R, Boucherat O, Provencher S, Bonnet S. DNA Damage and Pulmonary Hypertension. International Journal of Molecular Sciences. 2016; 17: 990. https://doi.org/10.3390/ijms17060990.

[58] Lahm T, Frump AL, Albrecht ME, Fisher AJ, Cook TG, Jones TJ, et al. 17β-Estradiol mediates superior adaptation of right ventricular function to acute strenuous exercise in female rats with severe pulmonary hypertension. American Journal of Physiology. Lung Cellular and Molecular Physiology. 2016; 311: L375–L388. https://doi.org/10.1152/ajplung.00132.2016.

[59] Teng RJ, Du J, Welak S, Guan T, Eis A, Shi Y, et al. Cross talk between NADPH oxidase and autophagy in pulmonary artery endothelial cells with intrauterine persistent pulmonary hypertension. American Journal of Physiology. Lung Cellular and Molecular Physiology. 2012; 302: L651–L663. https://doi.org/10.1152/ajplung.00177.2011.

[60] Dalvi P, Sharma H, Chinnappan M, Sanderson M, Allen J, Zeng R, et al. Enhanced autophagy in pulmonary endothelial cells on exposure to HIV-Tat and morphine: Role in HIV-related pulmonary arterial hypertension. Autophagy. 2016; 12: 2420–2438. https://doi.org/10.1080/15548627.2016.1238551.

[61] Singh N, Manhas A, Kaur G, Jagavelu K, Hanif K. Inhibition of fatty acid synthase is protective in pulmonary hypertension. British Journal of Pharmacology. 2016; 173: 2030–2045. https://doi.org/10.1111/bph.13495.

[62] Yao M, Zhong K, Zheng X, Yang Z, Li C, Gu Y, et al. Identification of LDHA as a Potential Therapeutic Target for Pulmonary Hypertension Through Modulation of Endothelial-To-Mesenchymal Transition. Journal of Cellular and Molecular Medicine. 2025; 29: e70692. https://doi.org/10.1111/jcmm.70692.

[63] Zou X, Yuan M, Zhou W, Cai A, Cheng Y, Zhan Z, et al. SOX17 Prevents Endothelial-Mesenchymal Transition of Pulmonary Arterial Endothelial Cells in Pulmonary Hypertension through Mediating TGF-β/Smad2/3 Signaling. American Journal of Respiratory Cell and Molecular Biology. 2025; 72: 364–379. https://doi.org/10.1165/rcmb.2023-0355OC.

[64] Shinohara T, Moonen JR, Chun YH, Lee-Yow YC, Okamura K, Szafron JM, et al. High Shear Stress Reduces ERG Causing Endothelial-Mesenchymal Transition and Pulmonary Arterial Hypertension. Arteriosclerosis, Thrombosis, and Vascular Biology. 2025; 45: 218–237. https://doi.org/10.1161/ATVBAHA.124.321092.

[65] Shen YH, Ding D, Lian TY, Qiu BC, Yan Y, Wang PW, et al. Panorama of artery endothelial cell dysfunction in pulmonary arterial hypertension. Journal of Molecular and Cellular Cardiology. 2024; 197: 61–77. https://doi.org/10.1016/j.yjmcc.2024.10.004.

[66] Gaikwad AV, Eapen MS, Dey S, Bhattarai P, Shahzad AM, Chia C, et al. TGF-β1, pSmad-2/3, Smad-7, and β-Catenin Are Augmented in the Pulmonary Arteries from Patients with Idiopathic Pulmonary Fibrosis (IPF): Role in Driving Endothelial-to-Mesenchymal Transition (EndMT). Journal of Clinical Medicine. 2024; 13: 1160. https://doi.org/10.3390/jcm13041160.

[67] López-Ruiz P, Rodriguez-Ubreva J, Cariaga AE, Cortes MA, Colás B. SHP-1 in cell-cycle regulation. Anti-cancer Agents in Medicinal Chemistry. 2011; 11: 89–98. https://doi.org/10.2174/187152011794941154.

[68] Nadeau A, Ouellet M, Béland R, Mercier C, Robillard S, Lizotte F, et al. Endothelial SHP-1 regulates diabetes-induced abnormal collateral vessel formation and endothelial cell senescence. Journal of Molecular and Cellular Cardiology. 2025; 202: 50–63. https://doi.org/10.1016/j.yjmcc.2025.03.005.

[69] He Q, Xu S, Ma X, Qian Y, Lu X, Feng W, et al. SHP-1 mediates cigarette smoke extract-induced epithelial-mesenchymal transformation and inflammation in 16HBE cells. Open Medicine (Warsaw, Poland). 2024; 19: 20240991. https://doi.org/10.1515/med-2024-0991.

[70] Mercier C, Rousseau M, Geraldes P. Growth Factor Deregulation and Emerging Role of Phosphatases in Diabetic Peripheral Artery Disease. Frontiers in Cardiovascular Medicine. 2021; 7: 619612. https://doi.org/10.3389/fcvm.2020.619612.

[71] Sim KH, Lee E, Shrestha P, Choi BH, Hong J, Lee YJ. Isobavachin attenuates FcεRI-mediated inflammatory allergic responses by regulating SHP-1-dependent Fyn/Lyn/Syk/Lck signaling. Biochemical Pharmacology. 2025; 232: 116698. https://doi.org/10.1016/j.bcp.2024.116698.

[72] Frank C, Burkhardt C, Imhof D, Ringel J, Zschörnig O, Wieligmann K, et al. Effective dephosphorylation of Src substrates by SHP-1. The Journal of Biological Chemistry. 2004; 279: 11375–11383. https://doi.org/10.1074/jbc.M309096200.

[73] Chintala H, Krupska I, Yan L, Lau L, Grant M, Chaqour B. The matricellular protein CCN1 controls retinal angiogenesis by targeting VEGF, Src homology 2 domain phosphatase-1 and Notch signaling. Development (Cambridge, England). 2015; 142: 2364–2374. https://doi.org/10.1242/dev.121913.

[74] Lulli M, Cammalleri M, Fornaciari I, Casini G, Dal Monte M. Acetyl-11-keto-β-boswellic acid reduces retinal angiogenesis in a mouse model of oxygen-induced retinopathy. Experimental Eye Research. 2015; 135: 67–80. https://doi.org/10.1016/j.exer.2015.04.011.

[75] Quan M, Guo Q, Yan X, Yu C, Yang L, Zhang Y, et al. Parkin deficiency aggravates inflammation-induced acute lung injury by promoting necroptosis in alveolar type II cells. Chinese Medical Journal Pulmonary and Critical Care Medicine. 2024; 2: 265–278. https://doi.org/10.1016/j.pccm.2024.11.004.

[76] Pelosi P, D’Onofrio D, Chiumello D, Paolo S, Chiara G, Capelozzi VL, et al. Pulmonary and extrapulmonary acute respiratory distress syndrome are different. The European Respiratory Journal. Supplement. 2003; 42: 48s–56s. https://doi.org/10.1183/09031936.03.00420803.

[77] Su Y, Lucas R, Fulton DJR, Verin AD. Mechanisms of pulmonary endothelial barrier dysfunction in acute lung injury and acute respiratory distress syndrome. Chinese Medical Journal Pulmonary and Critical Care Medicine. 2024; 2: 80–87. https://doi.org/10.1016/j.pccm.2024.04.002.

[78] Li L, Cook C, Liu Y, Li J, Jiang J, Li S. Endothelial glycocalyx in hepatopulmonary syndrome: An indispensable player mediating vascular changes. Frontiers in Immunology. 2022; 13: 1039618. https://doi.org/10.3389/fimmu.2022.1039618.

[79] Yang GL, Zhao Z, Qin TT, Wang D, Chen L, Xiang R, et al. TNFSF15 inhibits VEGF-stimulated vascular hyperpermeability by inducing VEGFR2 dephosphorylation. FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology. 2017; 31: 2001–2012. https://doi.org/10.1096/fj.201600800R.

[80] Chu LY, Ramakrishnan DP, Silverstein RL. Thrombospondin-1 modulates VEGF signaling via CD36 by recruiting SHP-1 to VEGFR2 complex in microvascular endothelial cells. Blood. 2013; 122: 1822–1832. https://doi.org/10.1182/blood-2013-01-482315.

[81] Chang YF, Hsu YF, Chiu PT, Huang WJ, Huang SW, Ou G, et al. WMJ-S-001, a novel aliphatic hydroxamate derivative, exhibits anti-angiogenic activities via Src-homology-2-domain-containing protein tyrosine phosphatase 1. Oncotarget. 2015; 6: 85–100. https://doi.org/10.18632/oncotarget.2765.

[82] Croteau L, Mercier C, Fafard-Couture É Nadeau A, Robillard S, Breton V, et al. Endothelial deletion of PKCδ prevents VEGF inhibition and restores blood flow reperfusion in diabetic ischemic limb. Diabetes & Vascular Disease Research. 2021; 18: 1479164121999033. https://doi.org/10.1177/1479164121999033.

[83] Paquin-Veillette J, Lizotte F, Robillard S, Béland R, Breton MA, Guay A, et al. Deletion of AT2 Receptor Prevents SHP-1-Induced VEGF Inhibition and Improves Blood Flow Reperfusion in Diabetic Ischemic Hindlimb. Arteriosclerosis, Thrombosis, and Vascular Biology. 2017; 37: 2291–2300. https://doi.org/10.1161/ATVBAHA.117.309977.

[84] Liu SH, Sheu WHH, Lee MR, Lee WJ, Yi YC, Yang TJ, et al. Advanced glycation end product Nε-carboxymethyllysine induces endothelial cell injury: the involvement of SHP-1-regulated VEGFR-2 dephosphorylation. The Journal of Pathology. 2013; 230: 215–227. https://doi.org/10.1002/path.4045.

[85] Sugano M, Tsuchida K, Maeda T, Makino N. SiRNA targeting SHP-1 accelerates angiogenesis in a rat model of hindlimb ischemia. Atherosclerosis. 2007; 191: 33–39. https://doi.org/10.1016/j.atherosclerosis.2006.04.021.

[86] Jiao H, Berrada K, Yang W, Tabrizi M, Platanias LC, Yi T. Direct association with and dephosphorylation of Jak2 kinase by the SH2-domain-containing protein tyrosine phosphatase SHP-1. Molecular and Cellular Biology. 1996; 16: 6985–6992. https://doi.org/10.1128/MCB.16.12.6985.

[87] Lim S, Lee KW, Kim JY, Kim KD. Consideration of SHP-1 as a Molecular Target for Tumor Therapy. International Journal of Molecular Sciences. 2023; 25: 331. https://doi.org/10.3390/ijms25010331.

[88] Amiri F, Venema VJ, Wang X, Ju H, Venema RC, Marrero MB. Hyperglycemia enhances angiotensin II-induced janus-activated kinase/STAT signaling in vascular smooth muscle cells. The Journal of Biological Chemistry. 1999; 274: 32382–32386. https://doi.org/10.1074/jbc.274.45.32382.

[89] Beldi-Ferchiou A, Skouri N, Ben Ali C, Safra I, Abdelkefi A, Ladeb S, et al. Abnormal repression of SHP-1, SHP-2 and SOCS-1 transcription sustains the activation of the JAK/STAT3 pathway and the progression of the disease in multiple myeloma. PloS One. 2017; 12: e0174835. https://doi.org/10.1371/journal.pone.0174835.

[90] Chim CS, Fung TK, Cheung WC, Liang R, Kwong YL. SOCS1 and SHP1 hypermethylation in multiple myeloma: implications for epigenetic activation of the Jak/STAT pathway. Blood. 2004; 103: 4630–4635. https://doi.org/10.1182/blood-2003-06-2007.

[91] Bian Y, Yuan L, Yang X, Weng L, Zhang Y, Bai H, et al. SMURF1-mediated ubiquitylation of SHP-1 promotes cell proliferation and invasion of endometrial stromal cells in endometriosis. Annals of Translational Medicine. 2021; 9: 362. https://doi.org/10.21037/atm-20-2897.

[92] Duan B, Li Y, Geng H, Ma A, Yang X. Naringenin prevents pregnancy-induced hypertension via suppression of JAK/STAT3 signalling pathway in mice. International Journal of Clinical Practice. 2021; 75: e14509. https://doi.org/10.1111/ijcp.14509.

[93] Yun JH, Han MH, Jeong HS, Lee DH, Cho CH. Angiopoietin 1 attenuates interleukin-6-induced endothelial cell permeability through SHP-1. Biochemical and Biophysical Research Communications. 2019; 518: 286–293. https://doi.org/10.1016/j.bbrc.2019.08.048.

[94] Kumar S, Nanduri R, Bhagyaraj E, Kalra R, Ahuja N, Chacko AP, et al. Vitamin D3-VDR-PTPN6 axis mediated autophagy contributes to the inhibition of macrophage foam cell formation. Autophagy. 2021; 17: 2273–2289. https://doi.org/10.1080/15548627.2020.1822088.

[95] Saraswati S, Alhaider A, Abdelgadir AM, Tanwer P, Korashy HM. Phloretin attenuates STAT-3 activity and overcomes sorafenib resistance targeting SHP-1-mediated inhibition of STAT3 and Akt/VEGFR2 pathway in hepatocellular carcinoma. Cell Communication and Signaling: CCS. 2019; 17: 127. https://doi.org/10.1186/s12964-019-0430-7.

[96] Keilhack H, Tenev T, Nyakatura E, Godovac-Zimmermann J, Nielsen L, Seedorf K, et al. Phosphotyrosine 1173 mediates binding of the protein-tyrosine phosphatase SHP-1 to the epidermal growth factor receptor and attenuation of receptor signaling. The Journal of Biological Chemistry. 1998; 273: 24839–24846. https://doi.org/10.1074/jbc.273.38.24839.

[97] Zhuang X, Ma J, Xu S, Sun Z, Zhang R, Zhang M, et al. SHP-1 suppresses endotoxin-induced uveitis by inhibiting the TAK1/JNK pathway. Journal of Cellular and Molecular Medicine. 2021; 25: 147–160. https://doi.org/10.1111/jcmm.15888.

[98] Geng Q, Xian R, Yu Y, Chen F, Li R. SHP-1 acts as a tumor suppressor by interacting with EGFR and predicts the prognosis of human breast cancer. Cancer Biology & Medicine. 2021; 19: 468–485. https://doi.org/10.20892/j.issn.2095-3941.2020.0501.

[99] Le Gal L, Pellegrin M, Santoro T, Mazzolai L, Kurtz A, Meda P, et al. Connexin37-Dependent Mechanisms Selectively Contribute to Modulate Angiotensin II -Mediated Hypertension. Journal of the American Heart Association. 2019; 8: e010823. https://doi.org/10.1161/JAHA.118.010823.

[100] Semenza GL. Hypoxia-inducible factors in physiology and medicine. Cell. 2012; 148: 399–408. https://doi.org/10.1016/j.cell.2012.01.021.

[101] Semenza GL. HIF-1: mediator of physiological and pathophysiological responses to hypoxia. Journal of Applied Physiology (Bethesda, Md.: 1985). 2000; 88: 1474–1480. https://doi.org/10.1152/jappl.2000.88.4.1474.

[102] Brahimi-Horn MC, Pouysségur J. HIF at a glance. Journal of Cell Science. 2009; 122: 1055–1057. https://doi.org/10.1242/jcs.035022.

[103] Semenza G. Signal transduction to hypoxia-inducible factor 1. Biochemical Pharmacology. 2002; 64: 993–998. https://doi.org/10.1016/s0006-2952(02)01168-1.

[104] Tang N, Wang L, Esko J, Giordano FJ, Huang Y, Gerber HP, et al. Loss of HIF-1alpha in endothelial cells disrupts a hypoxia-driven VEGF autocrine loop necessary for tumorigenesis. Cancer Cell. 2004; 6: 485–495. https://doi.org/10.1016/j.ccr.2004.09.026.

[105] Lee S, Chen TT, Barber CL, Jordan MC, Murdock J, Desai S, et al. Autocrine VEGF signaling is required for vascular homeostasis. Cell. 2007; 130: 691–703. https://doi.org/10.1016/j.cell.2007.06.054.

[106] Klimova T, Chandel NS. Mitochondrial complex III regulates hypoxic activation of HIF. Cell Death and Differentiation. 2008; 15: 660–666. https://doi.org/10.1038/sj.cdd.4402307.

[107] Li J, Xie R, Jiang F, Li Y, Zhu Y, Liu Z, et al. Tumor necrosis factor ligand-related molecule 1A maintains blood-retinal barrier via modulating SHP-1-Src-VE-cadherin signaling in diabetic retinopathy. FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology. 2021; 35: e22008. https://doi.org/10.1096/fj.202100807RR.

[108] Koch E, Pircher J, Czermak T, Gaitzsch E, Alig S, Mannell H, et al. The endothelial tyrosine phosphatase SHP-1 plays an important role for vascular haemostasis in TNF-α -induced inflammation in vivo. Mediators of Inflammation. 2013; 2013: 279781. https://doi.org/10.1155/2013/279781.

[109] Cho SW, Hartle L, Son SM, Yang F, Goldberg M, Xu Q, et al. Delivery of small interfering RNA for inhibition of endothelial cell apoptosis by hypoxia and serum deprivation. Biochemical and Biophysical Research Communications. 2008; 376: 158–163. https://doi.org/10.1016/j.bbrc.2008.08.123.

[110] Bhattacharya R, Kwon J, Wang E, Mukherjee P, Mukhopadhyay D. Src homology 2 (SH2) domain containing protein tyrosine phosphatase-1 (SHP-1) dephosphorylates VEGF Receptor-2 and attenuates endothelial DNA synthesis, but not migration*. Journal of Molecular Signaling. 2008; 3: 8. https://doi.org/10.1186/1750-2187-3-8.

[111] Chen JL, Chu PY, Huang CT, Huang TT, Wang WL, Lee YH, et al. Interfering B cell receptor signaling via SHP-1/p-Lyn axis shows therapeutic potential in diffuse large B-cell lymphoma. Molecular Medicine (Cambridge, Mass.). 2022; 28: 93. https://doi.org/10.1186/s10020-022-00518-0.

[112] Liu X, He Q, Sun S, Lu X, Chen Y, Lu S, et al. Research progress of SHP-1 agonists as a strategy for tumor therapy. Molecular Diversity. 2024. https://doi.org/10.1007/s11030-024-11059-5. (online ahead of print)

[113] Wang C, Nistala R, Cao M, Li DP, Pan Y, Golzy M, et al. Repair of Limb Ischemia Is Dependent on Hematopoietic Stem Cell Specific-SHP-1 Regulation of TGF-β1. Arteriosclerosis, Thrombosis, and Vascular Biology. 2023; 43: 92–108. https://doi.org/10.1161/ATVBAHA.122.318205.

[114] Gu Q, Tung KS, Lorenz UM. Treg-specific deletion of the phosphatase SHP-1 impairs control of inflammation in vivo. Frontiers in Immunology. 2023; 14: 1139326. https://doi.org/10.3389/fimmu.2023.1139326.

Funding

National Natural Science Foundation of China(82160016)

National Natural Science Foundation of China(82560078)

Famous Doctors of High-level Talent Training Support Program of Yunnan Province(YNWR-MY-2020-013)

Special and Joint Program of the Yunnan Provincial Science and Technology Department and Kunming Medical University(202201AY070001-265)

Special and Joint Program of the Yunnan Provincial Science and Technology Department and Kunming Medical University(202301AY070001-189)

Science Research Foundation of Yunnan Provincial Education Department(2024J0016)

Science Research Foundation of Yunnan Provincial Education Department(2024Y918)

Yunnan Provincial Innovation Team for Respiratory and Pulmonary Circulation Diseases(202405AS350018)

Yunnan Fundamental Research Projects(202501CF070056)

Yunnan University Medical Research Foundation(YDYXJJ2024-0026)