Lei Xu

Objective. Small heat shock protein-1 (HSPB1) is a small heat shock protein that participates in many cellular processes and alleviates stress-induced cell injury. Autophagy protects cells from many types of stress and plays a key role in preventing stress in arteriosclerosis obliterans (ASO). However, the roles of HSPB1 in autophagy and apoptosis in the context of ASO pathogenesis remain unclear. Methods. In vivo and in vitro studies were used to determine whether HSPB1 is associated with ASO progression. The expression of HSPB1 was measured in normal and sclerotic blood vessels. The role of HSPB1 and its potential downstream signaling pathway were determined in VSMCs by overexpressing and silencing HSPB1. Results. A total of 91 ASO patients admitted to and treated at our hospital from Sep. 2020 to Sep. 2021 were selected, and plasma HSPB1 expression was assessed. We divided the patients with ASO into the grade I ( ), II ( ), III ( ), and IV ( ) groups according to Fontaine’s classification. Plasma HSPB1 levels were markedly decreased in patients with grade III ( ) and IV ( ) ASO compared with patients with grade I ASO. Furthermore, HSPB1 expression was significantly decreased, and p62 and cleaved caspase-3 were increased in the sclerotic vasculature compared to the normal vasculature ( ). Overexpression of HSPB1 promoted apoptosis of VSMCs following ox-LDL treatment. Knockdown of HSPB1 led to a marked increase in the expression of LC3II and Beclin-1 in ox-LDL-stimulated VSMCs, whereas knockdown of HSPB1 attenuated these changes ( ). Importantly, overexpression of HSPB1 promoted the dephosphorylation of JNK in ox-LDL-stimulated VSMCs. Conversely, downregulation of HSPB1 induced the opposite change. Conclusion. Loss of HSPB1 promotes VSMC autophagy and inhibits VSMC apoptosis, which are associated with ASO. HSPB1 and its downstream signaling pathways could be potential therapeutic targets for ASO treatment.

Oxidative stress is the main cause of acute myocardial infarction (AMI), which is related to the disorder of the regulation of Bmal1 on the redox state. HSPB1 form homologous‐oxidized HSPB1 (homooxidized HSPB1) to resist oxidative damage via S‐thiolated modification. However, it is still unclarified whether there is an interaction between the circadian clock and HSPB1 in myocardial injury. A total of 118 AMI patients admitted and treated in our hospital from Sep. 2019 to Sep. 2020 were selected to detect the plasma HSPB1 expression and the redox state. We divided the AMI patients into three subgroups: morning‐onset AMI (5 : 00 am to 8 : 00 am; Am‐subgroup, n = 38), noon‐onset AMI (12 : 00 pm to 15 : 00; Pm‐subgroup, n = 45), and night‐onset AMI (20 : 00 pm to 23 : 00 pm; Eve‐subgroup, n = 35) according to the circadian rhythm of onset. The Am‐subgroup had remarkably higher cardiac troponin I (cTnI), creatine kinase MB (CK‐MB), and B‐type natriuretic peptide (BNP) but lower left ventricular ejection fraction (LVEF) than the Pm‐subgroup and Eve‐subgroup. Patients complicated with cardiogenic shock were significantly higher in the Am‐subgroup than in the other two groups. The homooxidized HSPB1 in plasma markedly decreased in the Am‐subgroup. The HSPB1C141S mutant accelerated H9c2 cell apoptosis, increased reactive oxygen species (ROS), and decreased reduced‐glutathione (GSH) and the ratio of reduced‐GSH and GSSG during oxidative stress. Importantly, we found that the redox state of HSPB1 was consistent with the oscillatory rhythm of Bmal1 expression in normal C57B/L mice. The circadian rhythm disorder contributed to decrease Bmal1 and homooxidized HSPB1 in cardiomyocytes of C57BL/6 mice. In addition, Bmal1 and homooxidized HSPB1 decreased in neonatal rat cardiomyocytes exposed to H₂O₂. Knockdown of Bmal1 led to significant attenuation in homooxidized HSPB1 expression, whereas overexpression of Bmal1 increased homooxidized HSPB1 expression in response to H₂O₂. Our findings indicated that the homooxidized HSPB1 reduced probably the AMI patients’ risk of shock and target organ damage, which was associated with Bmal1 regulating the redox state of HSPB1.