Genetic deletion of TNFR2 augments inflammatory response and blunts satellite‐cell‐mediated recovery response in a hind limb ischemia model. Issue 4 (2nd December 2014) - Sasi, Sharath P.
Abstract : We have previously shown that TNF‐tumor necrosis factor receptor‐2/p75 (TNFR2/p75) signaling plays a critical role in ischemia‐induced neovascularization in skeletal muscle and heart tissues. To determine the role of TNF‐TNFR2/p75 signaling in ischemia‐induced inflammation and muscle regeneration, we subjected wild‐type (WT) and TNFR2/p75 knockout (p75KO) mice to hind limb ischemia (HLI) surgery. Ischemia induced significant and long‐lasting inflammation associated with considerable decrease in satellite‐cell activation in p75KO muscle tissue up to 10 d after HLI surgery. To determine the possible additive negative roles of tissue aging and the absence of TNFR2/p75, either in the tissue or in the bone marrow (BM), we generated 2 chimeric BM transplantation (BMT) models where both young green fluorescent protein (GFP)‐positive p75KO and WT BM‐derived cells were transplanted into adult p75KO mice. HLI surgery was performed 1 mo after BMT, after confirming complete engraftment of the recipient BM with GFP donor cells. In adult p75KO with the WT‐BMT, proliferative (Ki67 + ) cells were detected only by d 28 and were exclusively GFP +, suggesting significantly delayed contribution of young WT‐BM cell to adult p75KO ischemic tissue recovery. No GFP + young p75KO BM cells survived in adult p75KO tissue, signifying the additive negative roles of tissue aging combined with decreased/absent TNFR2/p75 signaling in postischemic recovery.—Sasi, S. P., Rahimi, L., Yan, X., Silver, M., Qin, G., Losordo, D. W., Kishore, R., Goukassian, D. A. Genetic deletion of TNFR2 augments inflammatory response and blunts satellite‐cell‐mediated recovery response in a hind limb ischemia model. FASEB J. 29, 1208‐1219 (2015). www.fasebj.org