Heat stress-induced heat shock protein 70 (HSP70) expressions among vulnerable populations in urban and rural areas Klang Valley, Malaysia

Background: As climate change raises global temperatures, there remains a notable gap in understanding the body's mechanisms of heat stress defense exhibited by Heat Shock Protein (HSP) within the populations. Objective: This study aims to investigate the expression level of HSP70 in response to indoor heat exposure among vulnerable populations in both urban and rural settings. Methods: A comparative cross-sectional was conducted among 108 participants from urban and rural areas in Klang Valley, Malaysia. The study included face-to-face interviews, indoor heat exposure monitoring, and thermal stress classification using the Universal Thermal Climate Index (UTCI). HSP70 gene and protein expressions were analyzed using reverse-transcription quantitative polymerase chain reaction (RT-qPCR) and HSP70 High Sensitivity Enzyme-linked Immunosorbent Assay (ELISA), respectively. Results: Urban areas experienced signficantly higher UTCI heat exposure levels than rural areas (p < 0.001). In response to heat stress, vulnerable populations in urban areas exhibited higher HSP70 gene relative expression and HSP70 protein expression. A significant mean difference in the plasma HSP70 protein expression was observed between the two groups (p < 0.001). The linear mixed model (LMM) revealed a significant association between UTCI heat exposure levels and HSP70 gene and protein expression in both groups (p < 0.001). Impact: center dot While previous studies have examined cellular responses to heat stress in healthy individuals within controlled experimental settings, our study uniquely focuses on vulnerable individuals in actual environmental conditions. This is crucial for establishing baseline information on the ability of these populations to adapt to climate change and surrounding temperatures. Such information is essential for building resilient communities and preventing fatal incidents such as heat stroke during extreme heat events. By highlighting the differences between urban and rural populations, this study provides critical information for policymakers and health practitioners to design location-specific and population-specific heat stress mitigation strategies.