Thymosin β4 and cardiac protection: implication in inflammation and fibrosis

摘要

Thymosin beta 4 (Tβ4) is a ubiquitous protein with diverse biological functions. The effecter molecules targeted by Tβ4 in cardiac protection remain unknown. We summarize previously published work showing that treatment with Tβ4 in the myocardial infarction setting improves cardiac function by activating Akt phosphorylation, promoting the ILK–Pinch–Parvin complex, and suppressing NF-κB and collagen synthesis. In the presence of Wortmannin, Tβ4 showed minimal cardiac protection. In vitro findings revealed that pretreatment with Tβ4 resulted in reduction of intracellular ROS in the cardiac fibroblasts and was associated with increased expression of antioxidant enzymes, reduction of Bax/Bcl_2 ratio, and attenuation of profibrotic genes. Silencing of Cu/Zn-SOD, catalase, and Bcl_2 genes abrogated the protective effect of Tβ4. Our findings suggest that Tβ4 improves cardiac function by enhancing Akt and ILK activation and suppressing NF-κB activity and collagen synthesis. Furthermore, Tβ4 selectively upregulates catalase, Cu/Zn-SOD, and Bcl_2, thereby protecting cardiac fibroblasts from H_2O_2-induced oxidative damage. Further studies are warranted to elucidate the signaling pathway(s) involved in the cardiac protection afforded by Tβ4.