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Neutrophil:lymphocyte ratio and cell-free DNA dynamics during excessive heat stress in occupational and experimental settings

Hansson, Erik LU ; Gilworth, Rachel E. ; Glaser, Jason R. ; Chavarría, Denis ; Skinner, Bethany D. ; Weiss, Ilana ; Johnson, Richard J. ; Madero, Magdalena ; Segelmark, Mårten LU orcid and Wegman, David H. , et al. (2026) In Journal of Thermal Biology 136.
Abstract

Introduction Systemic inflammation is postulated to mediate heat stroke and heat-related organ injury, yet acute inflammatory responses among heat-stressed workers remains poorly understood. We aimed to describe neutrophil mobilisation and potential release of DNA during heat stress in multiple hot occupational settings and a controlled experimental setting. Methods Neutrophil:lymphocyte ratio (NLR) was investigated in six sugarcane worker groups: Nicaraguan cohorts consisting of 1a) workers undergoing pre-employment screening (N = 5257), 1b) workers with acute kidney injury (AKI, N = 470); 2) Salvadoran cane cutters (N = 45) sampled pre/post-shift before and during a rest-shade-hydration intervention; 3) Mexican cane workers performing... (More)

Introduction Systemic inflammation is postulated to mediate heat stroke and heat-related organ injury, yet acute inflammatory responses among heat-stressed workers remains poorly understood. We aimed to describe neutrophil mobilisation and potential release of DNA during heat stress in multiple hot occupational settings and a controlled experimental setting. Methods Neutrophil:lymphocyte ratio (NLR) was investigated in six sugarcane worker groups: Nicaraguan cohorts consisting of 1a) workers undergoing pre-employment screening (N = 5257), 1b) workers with acute kidney injury (AKI, N = 470); 2) Salvadoran cane cutters (N = 45) sampled pre/post-shift before and during a rest-shade-hydration intervention; 3) Mexican cane workers performing 3a) heavy (N = 148) and 3b) light-moderate (N = 24) work, sampled pre/post shift; and 4) Honduran cane cutters sampled pre/post-shift (N = 72). Cell-free DNA (cf-DNA) was measured in two cross-shift sugarcane worker groups (N = 26, El Salvador and N = 20, Nicaragua). NLR and cf-DNA was also measured in research participants (N = 10) exercising in temperate and hot conditions. Results NLR was elevated in sugarcane workers with AKI and increased during work shifts. Large positive NLR changes were associated with not having rest-shade-hydration, heavy workload, high environmental heat and high core body temperatures. cf-DNA increased across work-shifts in both cane cutter groups and after exercise in heat. Conclusion Neutrophil mobilisation was common among workers with AKI, and NLR and cf-DNA increased during and after field-based occupational and experimental heat stress. The findings indicate that acute systemic inflammation with neutrophil activation and destruction is common during excessive exertional heat stress.

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organization
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type
Contribution to journal
publication status
published
subject
in
Journal of Thermal Biology
volume
136
article number
104424
publisher
Elsevier
external identifiers
  • scopus:105030943223
  • pmid:41734407
ISSN
0306-4565
DOI
10.1016/j.jtherbio.2026.104424
language
English
LU publication?
yes
additional info
Publisher Copyright: Copyright © 2026. Published by Elsevier Ltd.
id
7eff07a1-5174-454b-b1f6-a6c831f1e6ad
date added to LUP
2026-04-20 13:57:34
date last changed
2026-06-01 18:13:33
@article{7eff07a1-5174-454b-b1f6-a6c831f1e6ad,
  abstract     = {{<p>Introduction Systemic inflammation is postulated to mediate heat stroke and heat-related organ injury, yet acute inflammatory responses among heat-stressed workers remains poorly understood. We aimed to describe neutrophil mobilisation and potential release of DNA during heat stress in multiple hot occupational settings and a controlled experimental setting. Methods Neutrophil:lymphocyte ratio (NLR) was investigated in six sugarcane worker groups: Nicaraguan cohorts consisting of 1a) workers undergoing pre-employment screening (N = 5257), 1b) workers with acute kidney injury (AKI, N = 470); 2) Salvadoran cane cutters (N = 45) sampled pre/post-shift before and during a rest-shade-hydration intervention; 3) Mexican cane workers performing 3a) heavy (N = 148) and 3b) light-moderate (N = 24) work, sampled pre/post shift; and 4) Honduran cane cutters sampled pre/post-shift (N = 72). Cell-free DNA (cf-DNA) was measured in two cross-shift sugarcane worker groups (N = 26, El Salvador and N = 20, Nicaragua). NLR and cf-DNA was also measured in research participants (N = 10) exercising in temperate and hot conditions. Results NLR was elevated in sugarcane workers with AKI and increased during work shifts. Large positive NLR changes were associated with not having rest-shade-hydration, heavy workload, high environmental heat and high core body temperatures. cf-DNA increased across work-shifts in both cane cutter groups and after exercise in heat. Conclusion Neutrophil mobilisation was common among workers with AKI, and NLR and cf-DNA increased during and after field-based occupational and experimental heat stress. The findings indicate that acute systemic inflammation with neutrophil activation and destruction is common during excessive exertional heat stress.</p>}},
  author       = {{Hansson, Erik and Gilworth, Rachel E. and Glaser, Jason R. and Chavarría, Denis and Skinner, Bethany D. and Weiss, Ilana and Johnson, Richard J. and Madero, Magdalena and Segelmark, Mårten and Wegman, David H. and Wesseling, Catharina and Jakobsson, Kristina and Lucas, Rebekah A.I.}},
  issn         = {{0306-4565}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Thermal Biology}},
  title        = {{Neutrophil:lymphocyte ratio and cell-free DNA dynamics during excessive heat stress in occupational and experimental settings}},
  url          = {{http://dx.doi.org/10.1016/j.jtherbio.2026.104424}},
  doi          = {{10.1016/j.jtherbio.2026.104424}},
  volume       = {{136}},
  year         = {{2026}},
}