The changes of CD4⁺CD25⁺ regulatory T cells (CD4⁺CD25⁺ Treg) and Foxp3 mRNA in peripheral blood mononuclear cells (PBMCs) from patients with asthma were investigated in order to elucidate the possible roles of CD4⁺CD25⁺ Treg in the development of asthma. The peripheral blood samples were collected from 29 healthy controls (normal control group) and 78 patients with asthma which included 30 patients in exacerbation group, 25 patients in persistent group, and 23 patients in remission group. By using flow cytometry and RT-PCR, the CD4⁺CD25⁺ Treg ratio and Foxp3 mRNA in PBMCs were detected. The CD4⁺CD25⁺ Treg ratio and Foxp3 mRNA in PBMCs of exacerbation and persistent groups were lower than that of remission and normal control group (P<0.05). Although the CD4⁺CD25⁺ Treg ratio and Foxp3 mRNA of remission group also lower than that of normal control group, there was no significant difference between them (P>0.05). As compared with persistent group, exacerbation group had lower CD4⁺CD25⁺ Treg ratio and Foxp3 mRNA (P<0.05). It was indicated that the decrease of CD4⁺CD25⁺ Treg ratio and its function in PBMCs may be responsible for pathogenesis of asthma.

This study was designed to investigate the expression of aminopeptidase N (APN)/CD13 on intraembryonic AGM stromal cells, and the change of its enzymatic activity after irradiation injury. The expression of APN/CD13 on AGM stromal cells was assayed by RT-PCR and immunihistochemistry. After the stromal cells in AGM region were irradiated with 8.0 Gy of ⁶⁰Co γ-rays, APN/CD13 enzymatic activity was measured by spectrophotometer at different time points. The result showed that AGM stromal cells strongly expressed APN/CD13. The enzymatic activity of APN/CD13 decreased temporarily after irradiation injury, then increased to higher level 4 h after irradiation, and it returned to the pre-irradiation level 24 to 48 h after the irradiation. The enzymatic activity of APN/CD13 was temporarily enhanced after irradiation injury, which might be one of the compensatory mechanisms that promote the hematopoietic recovery after irradiation.

The expression of paired immunoglobin-like receptors A (PIR-A) and B (PIR-B) and their relationship with tolerogenic dendritic cells (T-DC) in mice were investigated. The mouse DCs line, DC2.4 cells were cultured with the recombinant murine interleukin-10 (IL-10) and recombinant human transforming growth factor β1 (TGF-β1) respectively to develop the T-DC and stimulated with lipopolysaccharide (LPS) for 48 h to induce the mature dendritic cells (LPS-DC). Special small interfering RNAs (siRNA) molecule for PIR-B was chemically synthesized and transfected into DC2.4 cells (Si-DC) by lip2000. The expression of PIRs on DC2.4 cells were detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), flow cytometry (FCM) and Western blot. Realtime reverse transcriptase-polymerase chain reaction (Realtime-PCR) was applied for measurement of PIR-A and CD80, CD86, MHC-II mRNA expression. The allogeneic stimulating capacity of DCs was measured by mixed lymphocyte reaction (MLR) using ³H-thymidine incorporation test. The concentration of IFN-γ in supernatants of MLR from distinct groups was analyzed by ELISA. The results showed that PIR positive rate was (28.65±8.12)% examined by FCM on DC2.4 cells. PIR positive rate was increased dramatically to (54.21±6.34)%, (58.78±4.70)%, (48.24±6.75)% respectively for IL-10, TGF-β1 and LPS induction (P<0.01), but there was no significantly different among the three groups (P>0.01). The semi-quantitative RT-PCR and Western blot revealed that IL-10 and TGF-β1 induced the higher PIR-B level and lower PIR-A level. On the contrary, the LPS down-regulated the PIR-B expression and up-regulated the PIR-A expression. Realtime PCR examination demonstrated that PIR-A and co-stimulating molecules such as CD80, CD86 and MHC-II were increased significantly after stimulation with LPS. Compared with the DC2.4 cells and the LPS-DC, the T-DCs inhibited alloactived T cell proliferation and down-regulated the IFN-γ secretion in MLR supernatant. Si-DC promoted the T cell proliferation (P<0.01) and enhanced the IFN-γ secretion (P<0.01). It was concluded that up-regulating the PIR-B and down-regulating the PIR-A expression were the general feature of phenotype and constructed the new targets for dendritic cells to acquire immune tolerance in mice. Overexpression of PIR-B can inhibit the up-regulation of the PIR-A, CD80, CD86 and MHC-II expression, which might be the molecular mechanism for the T-DC.

To explore the role of mechanosensitive potassium channel TREK-1, Western blot analysis was used to investigate the expression changes of TREK-1 in left ventricle in acute mechanically stretched heart. Forty Wistar rats were randomly divided into 8 groups (n=5 in each group), subject to single Langendorff perfusion for 0, 30, 60, 120 min and acute mechanical stretch for 0, 30, 60, 120 min respectively. With Langendorff apparatus, an acute mechanically stretched heart model was established. There was no significant difference in the expression of TREK-1 among single Langendorff perfusion groups (P>0.05). As compared to non-stretched Langendorff-perfused heart, only the expression of TREK-1 in acute mechanically stretched heart (120 min) was greatly increased (P<0.05). This result suggested that some course of mechanical stretch could up-regulate the expression of TREK-1 in left ventricle. TREK-1 might play an important role in mechanoelectric feedback, so it could reduce the occurrence of arrhythmia that was induced by extra mechanical stretch.

In order to investigate the antitumor effect and molecular mechanism of interferon-α (IFN-α) on human acute myeloid leukemia cell line U937 cells in vitro, the proliferation of U937 cells was determined by MTT assay, the apoptosis rate was analyzed by flow cytometry (FCM), and the mRNA expression of cell cycle regulatory protein cyclin E was detected by RT-PCR. The results showed that IFN-α could inhibit the proliferation of U937 cells significantly in a dose-and time-dependent way (P<0.01), and induce the apoptosis of U937 cells also in a dose-and time-dependent manner at the concentration of 1000 4000 U/L (P<0.01). The apoptosis rate of U937 cells was even over 50% when cultured with IFN-for 36 48 h at the concentration of 2000 4000 U/L. Moreover, the expression of cyclin E mRNA was markedly inhibited by the addition of IFN-, and the inhibition was time-dependent (P<0.01). It was concluded that the anti-leukemia mechanism of IFN-α might be correlated with its antiproliferative and apoptotic inducing effects, and the down-regulation of the cyclin E expression might be one of its molecular mechanisms.

To investigate whether peroxisome proliferators-activated receptor-γ (PPARγ) ligand Troglitazone can reduce endothelial injury and activation during storage of harvested saphenous vein grafts. Segments of human saphenous vein graft were collected from 9 patients undergoing coronary bypass surgery and then divided into two equal parts of control and test specimens, were stored in either heparinized blood (control group) or heparinized blood containing 20 μmol/L troglitazone (test group) for 1 h at room temperature. Tissue distribution and protein expression of VCAM-1, ICAM-1, and endothelial nitric oxide synthase (eNOS) were compared using immunohistochemistry and Western blot analysis. Myeloperoxidase (MPO) activity, a marker of neutrophil sequestration in human saphenous vein grafts, was also measured in each group. The expression of ICAM-1 (753±132 versus 7201±934; P<0.01), VCAM-1 (3731±294 versus 8292±793; P<0.01), and MPO activity (1.52±0.42 U/g, 5.04±1.26 U/g P<0.01) were significantly lower in test group. In contract, eNOS expression (7983±834 versus 3989±1008; P<0.01) was significantly higher in test group. PPARγ ligand troglitazone might reduce endothelial injury during the storage period of human saphenous vein grafts.