Investigation Of The Effect And Mechanism Of Compound Exposure To Polystyrene Microplastics And DEHP On Allergic Asthma In Mice

Microplastic pollution is regarded as one of the major problems facing humanity in this century.To date,in vivo and in vitro toxicological investigations have shown that exposure to microplastics(MPs)can elicit adverse effects on various biological systems leading to multiple organ injuries and body dysfunction such as nerve,reproduction,and respiration.Allergic asthma is among the most prevalent chronic non-communicable ailments affecting both children and adults,with environmental factors predominantly deemed as the primary causative agents responsible for its development,progression,and escalating incidence rates.Nonetheless,the influence of MPs on this disease,particularly allergic asthma,remains inadequately and indistinctly investigated.In reality,MPs in the environment are not a single pollutant.They often coexist with phthalates in natural environments,particularly in food and freshwater.The co-occurrence of MPs and phthalates presents a significant challenge to the survival of humans and other organisms within nature.Regrettably,research on the combined exposure to MPs and phthalates is still in its nascent stages,and the effects,as well as potential mechanisms,of exposure to polystyrene microplastics(PS-MPs)in conjunction with di-(2-ethylhexyl)phthalate(DEHP)on allergic asthma remain unknown.In this study,a mouse model of allergic asthma was established by using classic ovalbumin(OVA)and 5-week-old male BALB/c mice.Additionally,the mice were separately exposed to PS-MPs or a combination of PS-MPs and different doses of DEHP for 28 days to observe the effects of PS-MPs alone or in combination with DEHP on the occurrence and development of allergic asthma.To further investigate whether the TRPA1-p38 MAPK pathway is involved in the mechanism of influence,we used HC-030031 to block TRPA1 activation and SB203580 to inhibit p38 MAPK phosphorylation.In the experiment,H&E staining and PAS staining were performed,and a semiquantitative scoring method was employed to evaluate the pathological changes in lung tissue;the effect of PS-MPs or compound DEHP on lung function was assessed by detecting changes in inspiratory resistance(Ri),expiratory resistance(Re)and dynamic lung compliance(Cldyn);altered immune homeostasis was assessed by detecting and analyzing the levels of Th1/Th2 representative cytokines using ELISA;oxidative stress biomarkers in lung tissue,such as reactive oxygen species(ROS)levels and malondialdehyde(MDA)content,were detected to evaluate the oxidative damage of lung tissue caused by to lung tissue by PS-MPs or combined DEHP;ELISA and immunohistochemistry were utilized to detect and analyze the content of calcium ions,release of related peptides,TRPA1 protein expression,as well as the phosphorylation levels of interleukin-1β(IL-1β),interleukin-17(IL-17),and p38 MAPK,to assess the effects of PS-MPs or a combination of PS-MPs and DEHP on the TRPA1-p38 MAPK pathway.The experimental results indicated that:(1)PS-MPs alone or in combination DEHP exposure did not directly cause asthma-like lesions in mice.(2)PS-MPs could promote the development of allergic asthma,including promoting the recruitment of airway inflammatory cells,airway hyperresponsiveness,and mucus protein hypersecretion,while simultaneous exposure to PS-MPs and DEHP can cause more severe pathological damage and decreased lung function.(3)Exposure to PS-MPs or compound DEHP could disrupt immune homeostasis in asthmatic mice with elevated levels of Th2 cytokine expression;(4)After exposure to PS-MPs or combined DEHP,the level of ROS and MDA content in the lung tissue of asthmatic mice increased,while GSH content decreased.Additionally,these exposures induce increased expression of TRPA1 protein,elevated calcium ion levels,augmented calcitonin gene-related peptide(CGRP)content,elevated levels of substance P(SP)and IL-1β,as well as enhanced phosphorylation levels of p38 MAPK and higher levels of IL-17.(5)After treating with HC-030031 and SB203580,the protein expression of TRPA1 and phosphorylation of p38 MAPK decreased.The expression levels of Th2 cytokines were also decreased,and pathological damage in the lungs is alleviated.Conclusion: The co-exposure of PS-MPs and DEHP can exacerbate allergic asthma,and the toxicity of co-exposure is higher than that of PS-MPs exposure alone.The underlying mechanism may be that PS-MPs and DEHP activate the TRPA1-p38 MAPK pathway by exacerbating oxidative stress and inflammatory responses in lung tissue,ultimately exacerbating the Th2 immune response leading to allergic asthma exacerbations.The results of this research results reveal the toxicity of PS-MPs and DEHP compound exposure and provide new insights into the health risks of MPs and phthalates.