Comparative Analysis of αB-Crystallin Expression in Heat-Stressed Myocardial Cells In Vivo and In Vitro

Relationships between alpha B-crystallin expression patterns and pathological changes of myocardial cells after heat stress were examined in vitro and in vivo in this study using the H9C2 cell line and Sprague-Dawley rats, respectively. Histopathological lesions, characterized by acute degeneration, karyopyknosis and loss of a defined nucleus, became more severe in rat hearts over the course of heat stress treatment from 20 min to 100 min. The expression of alpha B-crystallin in rat hearts showed a significant decrease (P<0.05) throughout the heat stress treatment period, except at the 40 min time point. Likewise, decreased alpha B-crystallin expression was also observed in the H9C2 cell line exposed to a high temperature in vitro, although its expression recovered to normal levels at later time points (80 and 100 min) and the cellular damage was less severe. The results suggest that alpha B-crystallin is mobilized early after exposure to a high temperature to interact with damaged proteins but that the myocardial cells cannot produce sufficient alpha B-crystallin for protection against heat stress. Lower alpha B-crystallin expression levels were accompanied by obvious cell/tissue damage, suggesting that the abundance of this protein is associated with protective effects in myocardial cells in vitro and in vivo. Thus, alpha B-crystallin is a potential biomarker of heat stress.