Adipocyte fatty acid-binding protein as a cerebrospinal fluid–accessible biomarker and druggable target in subarachnoid haemorrhage: Linking fatty acid dysregulation to microglial neuroinflammation

Abstract

Background: Subarachnoid haemorrhage (SAH), a devastating subtype of stroke, is predominantly caused by the rupture of intracranial aneurysms. Emerging evidence indicates that the risk of intracranial aneurysm rupture correlates with elevated serum levels of fatty acids and pro-inflammatory cytokines. Moreover, increased serum concentrations of adipocyte fatty acid-binding protein (A-FABP), an inflammation-related adipokine, have been associated with poorer prognosis in SAH. However, the precise roles of A-FABP in SAH pathogenesis and its biomarker potential in cerebrospinal fluid (CSF) remain unclear.

Methods: CSF from 40 SAH patients and 30 controls was analysed by targeted fatty acid metabolomics. Experimental SAH mice were induced by endovascular perforation in both genetic deletion and pharmacological inhibition of A-FABP. Brain injury was quantified by neurobehavioural test, inflammatory cytokine expression and TUNEL staining. In vitro, conditioned medium from fatty acid-stimulated microglia was applied to primary neurons to evaluate apoptosis. Microglial metabolic reprogramming was assayed with Seahorse XF assays.

Results: CSF revealed significant metabolic disruption in SAH, characterized by arachidonic acid (AA), linoleic acid and palmitic acid (PA). Enrichment analysis implicated A-FABP plays a crucial role in SAH pathogenesis. Notably, elevated A-FABP levels independently predicted increased SAH severity and poorer prognosis. In mice model of SAH, A-FABP was significantly upregulated in microglia. Genetic deletion and pharmacological inhibition of A-FABP significantly ameliorated brain injury, including neurological deficits, neuroinflammation and neuronal apoptosis. Mechanistically, PA and AA promoted BV2 microglial inflammation via an A-FABP-dependent manner, subsequently inducing apoptosis in co-cultured primary neurons. Moreover, A-FABP inhibition reprogrammed microglial metabolism, enhancing fatty acid β-oxidation and energy supply. Proteomics further identified the JAK2/STAT3 as a downstream pathway of A-FABP-mediated neuroinflammation.

Conclusions: A-FABP is a promising biomarker and translatable therapeutic target to improve SAH outcome. Targeting A-FABP disrupts fatty acids–driven neuroinflammation and microglial metabolic reprogramming to reduce brain injury after SAH.

Keywords

A-FABP / CSF biomarker / fatty acid metabolism / microglia / neuroinflammation / neuroprotection / subarachnoid haemorrhage

References

[1] Claassen J, Park S. Spontaneous subarachnoid haemorrhage. Lancet. 2022; 400: 846-862.

[2] Chen Y, Galea I, Macdonald RL, Wong GKC, Zhang JH. Rethinking the initial changes in subarachnoid haemorrhage: focusing on real-time metabolism during early brain injury. EBioMedicine. 2022; 83:104223.

[3] Tian Q, Guo Y, Feng S, et al. Inhibition of CCR2 attenuates neuroinflammation and neuronal apoptosis after subarachnoid hemorrhage through the PI3K/Akt pathway. J Neuroinflammation. 2022; 19: 312.

[4] Ohashi SN, DeLong JH, Kozberg MG, et al. Role of inflammatory processes in hemorrhagic stroke. Stroke. 2023; 54: 605-619.

[5] Mi Y, Qi G, Vitali F, et al. Loss of fatty acid degradation by astrocytic mitochondria triggers neuroinflammation and neurodegeneration. Nat Metab. 2023; 5: 445-465.

[6] Bazinet RP, Laye S. Polyunsaturated fatty acids and their metabolites in brain function and disease. Nat Rev Neurosci. 2014; 15: 771-785.

[7] Liu Q, Li K, He H, et al. The markers and risk stratification model of intracranial aneurysm instability in a large Chinese cohort. Sci Bull (Beijing). 2023; 68: 1162-1175.

[8] Li B, Hao J, Zeng J, Sauter ER. SnapShot: fABP functions. Cell. 2020; 182: 1066-1066.e1061.

[9] Guo D, Lin C, Lu Y, et al. FABP4 secreted by M1-polarized macrophages promotes synovitis and angiogenesis to exacerbate rheumatoid arthritis. Bone Res. 2022; 10: 45.

[10] Makowski L, Boord JB, Maeda K, et al. Lack of macrophage fatty-acid-binding protein aP2 protects mice deficient in apolipoprotein E against atherosclerosis. Nat Med. 2001; 7: 699-705.

[11] Liao B, Geng L, Zhang F, et al. Adipocyte fatty acid-binding protein exacerbates cerebral ischaemia injury by disrupting the blood–brain barrier. Eur Heart J. 2020; 41: 3169-3180.

[12] Luo YG, Han B, Sun TW, Liu X, Liu J, Zhang J. The association between serum adipocyte fatty acid-binding protein and 3-month disability outcome after aneurysmal subarachnoid hemorrhage. J Neuroinflammation. 2020; 17: 66.

[13] Zhou M, Bao Y, Li H, et al. Deficiency of adipocyte fatty-acid-binding protein alleviates myocardial ischaemia/reperfusion injury and diabetes-induced cardiac dysfunction. Clin Sci (Lond). 2015; 129: 547-559.

[14] Wei B, Liu W, Jin L, et al. Hepcidin depending on astrocytic NEO1 ameliorates blood–brain barrier dysfunction after subarachnoid hemorrhage. Cell Death Dis. 2024; 15: 569.

[15] Fan H, Tian H, Jin F, et al. CypD induced ROS output promotes intracranial aneurysm formation and rupture by 8-OHdG/NLRP3/MMP9 pathway. Redox Biol. 2023; 67:102887.

[16] Hu Y, Luo NJ, Gan L, et al. Heat stress upregulates arachidonic acid to trigger autophagy in sertoli cells via dysfunctional mitochondrial respiratory chain function. J Transl Med. 2024; 22(1): 501.

[17] Xiao ZP, Lv T, Hou PP, et al. Sirtuin 5-mediated lysine desuccinylation protects mitochondrial metabolism following subarachnoid hemorrhage in mice. Stroke. 2021; 52: 4043-4053.

[18] Wang B, Xu J, Ren Q, et al. Fatty acid-binding protein 4 is a therapeutic target for septic acute kidney injury by regulating inflammatory response and cell apoptosis. Cell Death Dis. 2022; 13: 333.

[19] Tso AW, Lam TK, Xu A, et al. Serum adipocyte fatty acid-binding protein associated with ischemic stroke and early death. Neurology. 2011; 76: 1968-1975.

[20] Peeters W, de Kleijn DP, Vink A, et al. Adipocyte fatty acid binding protein in atherosclerotic plaques is associated with local vulnerability and is predictive for the occurrence of adverse cardiovascular events. Eur Heart J. 2011; 32: 1758-1768.

[21] Li S, Bi P, Zhao W, et al. Prognostic utility of fatty acid-binding protein 4 in patients with type 2 diabetes and acute ischemic stroke. Neurotox Res. 2018; 33: 309-315.

[22] He J, Qin Z, Liu H, et al. Fatty acid-binding protein 4 drives microglia-mediated neuroinflammation through promoting S100A9 expression and lipid droplet accumulation after intracerebral hemorrhage. J. Neuroinflammation. 22;1: 263.

[23] Sandow N, Diesing D, Sarrafzadeh A, Vajkoczy P, Wolf S. Nimodipine dose reductions in the treatment of patients with aneurysmal subarachnoid hemorrhage. Neurocrit Care. 2016; 25: 29-39.

[24] Sulsky R, Magnin DR, Huang Y, et al. Potent and selective biphenyl azole inhibitors of adipocyte fatty acid binding protein (aFABP). Bioorg Med Chem Lett. 2007; 17: 3511-3515.

[25] Furuhashi M, Tuncman G, Gorgun CZ, et al. Treatment of diabetes and atherosclerosis by inhibiting fatty-acid-binding protein aP2. Nature. 2007; 447: 959-965.

[26] Burak MF, Inouye KE, White A, et al. Development of a therapeutic monoclonal antibody that targets secreted fatty acid-binding protein aP2 to treat type 2 diabetes. Sci Transl Med. 2015; 7:319ra205.

[27] Liao B, Yang S, Geng L, et al. Development of a therapeutic monoclonal antibody against circulating adipocyte fatty acid binding protein to treat ischaemic stroke. Br J Pharmacol. 2024; 181: 1238-1255.

[28] Signorelli F, Sela S, Gesualdo L, et al. Hemodynamic stress, inflammation, and intracranial aneurysm development and rupture: a systematic review. World Neurosurg. 2018; 115: 234-244.

[29] Etminan N, Rinkel GJ. Unruptured intracranial aneurysms: development, rupture and preventive management. Nat Rev Neurol. 2016; 12: 699-713.

[30] Wang Y, Xie Y, Wang H, et al. Development and clinical translation of a perioperative nomogram incorporating free fatty acids to predict poor outcome of aneurysmal subarachnoid hemorrhage following endovascular treatment. Front Neurol. 2021; 12:629997.

[31] Niu Z, Hu H, Tang F. High free fatty acid levels are associated with stroke recurrence and poor functional outcome in chinese patients with ischemic stroke. J Nutr Health Aging. 2017; 21: 1102-1106.

[32] Kim YJ, Kim OY, Cho Y, et al. Plasma phospholipid fatty acid composition in ischemic stroke: importance of docosahexaenoic acid in the risk for intracranial atherosclerotic stenosis. Atherosclerosis. 2012; 225: 418-424.

[33] Furuhashi M, Fuseya T, Murata M, et al. Local production of fatty acid-binding protein 4 in epicardial/perivascular fat and macrophages is linked to coronary atherosclerosis. Arterioscler Thromb Vasc Biol. 2016; 36: 825-834.

[34] Mi Y, Qi G, Vitali F, et al. Loss of fatty acid degradation by astrocytic mitochondria triggers neuroinflammation and neurodegeneration. Nat Metab. 2023; 5(3): 445-465.

RIGHTS & PERMISSIONS

2026 The Author(s). Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.