TKT inhibition attenuates cardiac fibrosis in myocardial infarction through deactivating AKT signaling pathway

Transketolase (TKT) is expressed extensively in various tissues, modulating functions of metabolism and cell apoptosis. However, the effect of TKT on cardiac fibrosis after acute myocardial infarction (AMI) has not yet been explored. Firstly, we explored the expression of TKT in patients with AMI and acute coronary syndrome (ACS) by ELISA, and investigated the predictive value of TKT on prognosis of patients with ACS by Cox regression analysis. To elucidate the role of TKT in cardiac fibrosis following AMI, we established AMI animal model by ligating the left anterior descending coronary artery (LAD) in mice. Following intervention with TKT inhibitor-Oxythiamine (OT), we further assessed the impact of TKT inhibition on myocardial fibrosis in mice using Masson, Sirius red, and immunohistochemical staining assays. Subsequently, we isolated neonatal rat cardiac fibroblasts (NRCFs), then stimulated NRCFs with TGF-β1 and TKT inhibitor to explore the mechanism of cardiac fibroblasts activation in AMI. Meanwhile, western blotting was used to analyze the expression levels of cardiac fibrotic proteins. In addition, EDU, wound healing and Transwell assays were applied to detect cell proliferation and migration function, and to explore the relationship between TKT and AKT pathway. We have found for the first time that TKT was significantly elevated in AMI and ACS patients. Further confirmed that TKT not only holds significant clinical value in distinguishing AMI from unstable angina (UA) patients but also serves as a risk factor for major adverse cardiovascular events (MACE) in ACS patients. At the animal model level, we found that cardiac function was significantly improved and cardiac fibrosis alleviated in AMI mice under TKT inhibition. To further investigate the underlying mechanism, we established a cellular model of cardiac fibrosis by stimulating NRCFs with TGF-β1. Following treatment with TKT inhibitor, we observed significant suppression of both phenotypic transformation and proliferation or migration functions of NRCFs. This effect was attributable to inhibition of AKT phosphorylation. To validate TKT acts through AKT pathway, we demonstrated that TKT overexpression (OE) of NRCFs promoted phenotypic transformation, proliferation and migration functions of NRCFs in response to stimulation of TGF-β1, which could be reversed by inhibition of AKT phosphorylation. TKT was significantly elevated in AMI patients and AMI mice, and has preliminarily indicated the potential to be a biomarker for AMI and ACS patients. TKT inhibition reduced cardiac fibrosis in AMI mice, indicating that TKT regulated cardiac fibrosis post-AMI. TKT inhibitor suppressed phenotypic transformation, proliferation and migration functions of NRCFs, which mainly due to inhibition of AKT phosphorylation.