title: Dual roles of tumor necrosis factor-alpha receptor-1 in a mouse model of hindlimb ischemia.
abstract: Signals in the tumor necrosis factor alpha (TNF-alpha) pathway are upregulated after ischemia, yet its role in peripheral ischemia remains unclear. We investigated the effect of TNF-alpha receptor 1 (TNFR-1) in acute limb ischemia of TNFR-1 knockout (TNFR-1-/-) and wild type (WT, TNFR-1+/+) mice. Laser Doppler scanning showed that although pre-ischemia blood flow levels were similar in these mice, the limb reperfusion after ischemia was significantly higher in TNFR-1-/- mice 1-7 days after injury. Consistently, fewer TUNEL-positive cells, less DNA fragmentation, and a lower ischemic score were detected in the TNFR-1-/- group when compared to WT controls. Western blot analysis revealed less expression of pro-apoptotic markers Bax and cleaved caspase-3 in TNFR-1-/- mice 1 day after ischemia, supporting the hypothesis that the absence of TNFR-1 results in a reduction of apoptosis. The rate of post-ischemia amputation was 50% in WT mice versus 0% in TNFR-1-/- mice. However, immunohistochemical co-staining of microvessel marker CD31 and cellular proliferation marker BrdU 21 days after ischemia showed an impaired angiogenic activity in the TNFR-1-/- mice. These data were supported by Western blot analysis, which indicated a decreased expression of angiopoietin-1 (Ang-1) and its receptor Tie-2 in TNFR-1-/- mice. Our results suggest that a deficiency in TNFR-1 prevents the activation of death-related proteins downstream to TNF-alpha and attenuates apoptosis in acute limb ischemia, but the lack of TNFR-1 signaling hinders the belated angiogenesis mediated by the Ang-1/Tie-2 pathway.
authors.affiliation: Department of Cardiology, Second Affiliated Hospital, Zhejiang University College of Medicine, Hangzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Jiang
authors.forename: Jianan
authors.initials: J
authors.lastname: Wang
authors.forename: Changling
authors.initials: C
authors.lastname: Li
authors.forename: Shan Ping
authors.initials: SP
authors.lastname: Yu
authors.forename: Ling
authors.initials: L
authors.lastname: Wei
mesh_terms: D000671:Amputation, Surgical; D042683:Angiopoietin-1 / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D007511:Ischemia / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D017078:Laser-Doppler Flowmetry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology; D018919:Neovascularization, Physiologic; D042787:Receptor, TIE-2 / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D012039:Regional Blood Flow; D015398:Signal Transduction; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D042683:Angiopoietin-1; C494827:Bax protein, mouse; D047888:Receptors, Tumor Necrosis Factor, Type I; C506236:Tnfrsf1a protein, mouse; D014409:Tumor Necrosis Factor-alpha; D051028:bcl-2-Associated X Protein; D042787:Receptor, TIE-2; C505409:Casp3 protein, mouse; D053148:Caspase 3