Combined exposure to shrimp tropomyosin and microbial components triggers enhanced allergic and inflammatory responses in vitro

Introduction: Workers in the shellfish industry face increased risks of allergy and asthma due to complex bioaerosol exposures in the workplace. This study aimed to assess whether combined exposure to the main components of these aerosols, specifically allergens and microbial agents, can potentiate inflammatory and allergic responses. Methods: THP-1 monocytes and advanced human alveolar co-cultures model ALIsens® were exposed to shrimp tropomyosin (0.0049, 1.3 and 2.6 µg/mL), and components from Gram-positive bacteria; lipoteichoic acid (0.25–4 µg/mL), and fungi; zymosan (6.25–100 µg/mL), either alone or in combination. The effects on the gene expression and protein secretion of chemokines and cytokines were assessed by RT-qPCR and ELISA or Luminex. Results: Combined exposure to tropomyosin and lipoteichoic acid resulted in increased CCL20, CCL2, TNF and IL8 expression and CCL20 and TNF protein secretion in THP-1 cells, when compared to individual exposure. Similarly, tropomyosin combined with zymosan elicited a response pattern, characterised by increased expression and secretion of chemokines and cytokines in most of the tested combinations. Furthermore, the increased secretion of CCL20 and expression of CCL2 following combined exposure to tropomyosin and lipoteichoic acid were confirmed in the alveolar co-culture model, while no effects in combination with zymosan were observed. Conclusion: These findings suggest that microbial components in shellfish industry bioaerosols may enhance the immunological responses caused by inhaled allergens in an additive manner, highlighting the need to minimise microbial contamination in workplaces where allergen exposure is prevalent.