摘要：AIM: To study the apoptotic effect of TNFα on rat pulmonary microvascular endothelial cells (PMVEC) and the influences of Fas, NF-κB in its mechanism. METHODS: Apoptosis of PMVEC was analyzed and quantitated with TUNEL, flow cytometer. The distribution of NF-κB was detected via histoimmunochemical staining in TNF-treated cells and the control. Northern blot was applied to assess the influence of TNF on PMVEC Fas expression. Fas antibody was used to investigate the apoptotic effect of Fas on PMVEC. Activation of caspase-8 was detected with Western blot. Expression of caspase-3 was analyzed with histoimmunochemical staining. RESULTS: After treatment with 5×108 U/L TNF for 24 hours, viable PMVEC significantly diminished. Apoptosis rate was 14.0%±3.1% detected with TUNEL, and 13.1% with flow cytometer. Histoimmunochemical staining showed that NF-κB relocated from cytoplasm to the nuclear. When the cells were co-cultured with TNF and APDC, an NF-κB inhibitor, less cells were viable and more cells were positively stained with TUNEL. Fas expression in PMVEC was elevated treated with TNF. Apoptosis in PMVEC was found aggravated, when the cells were co-cultured with TNF and anti-Fas antibody. The positive rate was 24.1%±1.5% with TUNEL. Increase of caspase-8 activation was manifested by Western blot following TNF stimulation. Caspase-3 expression was found elevated using histoimmunochemical staining. Cell permeable caspase-3 inhibitor significantly ameliorated PMVEC apoptosis induced by TNF. CONCLUSION: 1. Large dose of TNF(5×108 U/L) can induce apoptosis in rat PMVEC. 2. NF-κB has a protective effect on PMVEC apoptosis. 3. TNF up-regulates Fas expression in PMVEC. And the latter takes a part in apoptosis. 4. TNF induced caspase-8 activation in PMVEC, and more caspase-3 was expressed. These may be involved in PMVEC apoptosis induced by TNF.