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. 2023 Sep;96(7):985-998.
doi: 10.1007/s00420-023-01984-7. Epub 2023 May 27.

Bioaerosol-induced in vitro activation of toll-like receptors and inflammatory biomarker expression in waste workers

Elke Eriksen  1 , Anani Komlavi Afanou  2 , Anne Straumfors  2 , Pål Graff  2
Affiliations

Bioaerosol-induced in vitro activation of toll-like receptors and inflammatory biomarker expression in waste workers

Elke Eriksen et al. Int Arch Occup Environ Health. 2023 Sep.

Abstract

Purpose: Occupational exposure to bioaerosols during waste handling remains a health concern for exposed workers. However, exposure-related health effects and underlying immunological mechanisms are still poorly described.

Methods: The present study assessed the inflammatory potential of work-air samples (n = 56) in vitro and investigated biomarker expression in exposed workers (n = 69) compared to unexposed controls (n = 25). These quantitative results were compared to self-reported health conditions.

Results: Personal air samples provoked an activation of TLR2 and TLR4 HEK reporter cells in one-third of all samples, indicating that the work environment contained ligands capable of inducing an immune response in vitro. Monocyte levels, as well as plasma biomarker levels, such as IL-1Ra, IL-18 and TNFα were significantly higher in exposed workers, compared to the control group when confounding factors such as BMI, sex, age and smoking habits were accounted for. Furthermore, a significant exposure-related increase in midweek IL-8 levels was measured among exposed workers. Tendencies of increased prevalence of health effects of the respiratory tract were identified in exposed workers.

Conclusion: Inhalable dust provoked TLR activation in vitro, indicating that an exposure-related immune response may be expected in susceptible workers. However, despite significant differences in inflammatory plasma biomarker levels between exposed and unexposed workers, prevalence of self-reported health effects did not differ between the groups. This may be due to the healthy worker effect, or other factors such as adequate use of personal protective respiratory devices or adaptation to the work environment with reduced activation of the immune system.

Keywords: Bioaerosols; Biomarkers; Health effects; Occupational exposure; Symptoms; TLR2; TLR4; Waste sorting.

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Conflict of interest statement

The authors have no competing interests to declare that are relevant to the content of this article.

Figures

Fig. 1
Fig. 1
Self-reported symptom frequencies in exposed workers and unexposed control group
Fig. 2
Fig. 2
TLR activation patterns by sample and waste sorting plant (plant A: F). Positive (LPS, LTA, Zymosan) and negative (PBS, PBS-BSA) controls in right panel. Absorbance levels in HEK null cells (grey), HEK TLR2 cells (orange), HEK TLR4 cells (blue). Significant differences between TLR transfected cells and the null cell line indicated with asterisk. Standard error included as error bars
Fig. 3
Fig. 3
Correlation matrix (Pearson correlation coefficients, upper half) and Benjamini–Hochberg corrected p-values (lower half) for background corrected TLR activation levels and exposure measurements in plant A: F
Fig. 4
Fig. 4
Correlation matrix (Pearson correlation coefficients, upper half) and Benjamini–Hochberg corrected p-values (lower half) of blood leukocytes and plasma biomarkers in exposed workers as well as dust-induced TLR activation in vitro from plant A: D
See this image and copyright information in PMC

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