Date of Award

2026-08-01

Degree Name

Doctor of Philosophy

Department

Interdisciplinary Health Sciences

Advisor(s)

Gabriel Ibarra-Mejia

Abstract

Heat shock proteins (HSP) are intracellular molecular proteins that are upregulated in response to cellular stress, including heat exposure. Through their protective functions, HSP help maintain protein structure, prevent protein denaturation, and preserve cellular homeostasis during states of physiological stress. Because of their cytoprotective properties, HSP have emerged as potential biomarkers for detecting early signs of tissue injury and predicting clinical outcomes associated with heat related illnesses (HRI), including acute kidney injuries (AKI). AKI is a leading cause of hospitalizations due to heat stress exposure and heat stroke. In the absence of early detection and effective therapeutic interventions, AKI may progress to chronic kidney disease (CKD). Workers in outdoor occupations, particularly those employed in construction, agriculture, and related industries, are at increased risk because of prolonged exposure to high environmental temperatures combined with strenuous physical labor. As global temperatures continue to rise due to climate change, occupational heat exposure has become a public health concern. Early identification of physiological responses to heat stress may improve the prevention, diagnosis, and management of heat-related kidney injury in vulnerable worker populations. The purpose of this study was to quantify the expression of heat shock protein 72 (HSP72) among Hispanic construction workers in El Paso, Texas following a series of work shifts under ambient heat exposure, and to assess correlations with environmental conditions, physiological responses, and biomarkers of kidney function. In this study, HSP72 protein expression levels were found to increase following occupational heat exposure. Among the variables examined, environmental conditions demonstrated stronger associations (humidity and maximum ambient temperature) with HSP72 expression than physical exertion (metabolic equivalent of task). Age was also found to influence HSP72 expression among construction workers experiencing heat stress. Although several biomarkers of kidney function revealed physiological stress following work shifts under ambient heat, HSP72 expression showed limited association with AKI in this cohort. However, significant correlations between HSP72 and variables of heat stress such as serum potassium, creatinine, albumin, phosphate, eGFR, weight and diastolic blood pressure were obtained. The findings suggest that occupational heat exposure may induce an integrated physiological response to chronic heat exposure targeting the proximal convoluted tubule of the nephron where signs of electrolyte imbalance, cardiovascular adaptation, changes of osmolarity and of filtration may reveal early signs of renal stress before the development of AKI or CKD. This pilot study contributes to the growing body of evidence examining biological mechanisms underlying occupational heat stress and kidney dysfunction and supports the potential role of HSP72 as a biomarker for identifying workers at experiencing early signs of a heat-related kidney stress before the standard clinical biomarkers (creatinine, albumin and urine albumin-to-creatinine ratio) can be detected on irreversible kidney injuries. The findings provided on this study have important implications for occupational health surveillance, early public health intervention strategies, and the development of preventive measures based on an interdisciplinary approach to protect vulnerable population working to the heavy physical work demands under increasingly hot environments. Key words: Heat shock protein 72, occupational heat stress, acute kidney injury, chronic kidney disease, construction workers, climate change, heat related kidney injury, heat stress, heat related illnesses, occupational health.

Language

en

Provenance

Received from ProQuest

File Size

231 p.

File Format

application/pdf

Rights Holder

Maria Fuentes

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