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McCormick JJ, Meade RD, King KE, Akerman AP, Notley SR, Kirby NV, Sigal RJ, Kenny GP. Effect of daylong exposure to indoor overheating on autophagy and the cellular stress response in older adults. Appl Physiol Nutr Metab 2024; 49:855-867. [PMID: 38394645 DOI: 10.1139/apnm-2023-0361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
To protect vulnerable populations during heat waves, public health agencies recommend maintaining indoor air temperature below ∼24-28 °C. While we recently demonstrated that maintaining indoor temperatures ≤26 °C mitigates the development of hyperthermia and cardiovascular strain in older adults, the cellular consequences of prolonged indoor heat stress are poorly understood. We therefore evaluated the cellular stress response in 16 adults (six females) aged 66-78 years during 8 h rest in ambient conditions simulating homes maintained at 22 °C (control) and 26 °C (indoor temperature upper limit proposed by health agencies), as well as non-air-conditioned domiciles during hot weather and heat waves (31 and 36 °C, respectively; all 45% relative humidity). Western blot analysis was used to assess changes in proteins associated with the cellular stress response (autophagy, apoptosis, acute inflammation, and heat shock proteins) in peripheral blood mononuclear cells harvested prior to and following exposure. Following 8 h exposure, no cellular stress response-related proteins differed significantly between the 26 and 22 °C conditions (all, P ≥ 0.056). By contrast, autophagy-related proteins were elevated following exposure to 31 °C (p62: 1.5-fold; P = 0.003) and 36 °C (LC3-II, LC3-II/I, p62; all ≥2.0-fold; P ≤ 0.002) compared to 22 °C. These responses were accompanied by elevations in apoptotic signaling in the 31 and 36 °C conditions (cleaved-caspase-3: 1.8-fold and 3.7-fold, respectively; P ≤ 0.002). Furthermore, HSP90 was significantly reduced in the 36 °C compared to 22 °C condition (0.7-fold; P = 0.014). Our findings show that older adults experience considerable cellular stress during prolonged exposure to elevated ambient temperatures and support recommendations to maintain indoor temperatures ≤26 °C to prevent physiological strain in heat-vulnerable persons.
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Affiliation(s)
- James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
| | - Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Ashley P Akerman
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Nathalie V Kirby
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, AB, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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Scovronick N, Pillarisetti A. Invited Perspective: Beating the Heat. ENVIRONMENTAL HEALTH PERSPECTIVES 2024; 132:21302. [PMID: 38329751 PMCID: PMC10852038 DOI: 10.1289/ehp14343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 12/22/2023] [Accepted: 01/03/2024] [Indexed: 02/09/2024]
Affiliation(s)
- Noah Scovronick
- Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
| | - Ajay Pillarisetti
- Division of Environmental Health Sciences, University of California, Berkeley, Berkeley, California, USA
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