Microplastics exposed by respiratory tract and exacerbation of community-acquired pneumonia: The potential influences of respiratory microbiota and inflammatory factors

The relationships between microplastics (MP) exposure through respiratory and exacerbation of community-acquired pneumonia (CAP), as well as the potential influences of respiratory microbiota and inflammatory factors remain unknown in adults. Therefore, we conducted a cross-sectional study involving 50 non-severe CAP (NSCAP) and severe CAP (SCAP) patients to examine the associations of MP exposure in sputum (SP) and bronchoalveolar lavage fluid (BALF) samples with SCAP risk, and the underlying influences of respiratory microbiota and inflammatory factors. The average concentration of total MP was 23.24 μg/g dw and 4.49 μg/g dw in SP and BALF samples, with the detection rates of 98 % and 94 %. Participants who performing housework often or sedentary time ≤ 5h exhibited a higher proportion of high exposure to MP. Multivariable logistic regression and weighted quantile sum regression models showed the significantly positive relationships of single type or overall MP exposure with SCAP risk. Correlation analysis revealed that MP concentrations in BALF samples were significantly associated with multiple respiratory microbiota and inflammatory factors, particularly with the reduction in α-diversity indices of the respiratory microbiota. Our findings demonstrated that respiratory exposure to MP may cause the risk increase of SCAP, along with the alterations of respiratory microbiota and inflammatory factors. It is recommended that patients with CAP should reduce the respiratory exposure to MP for preventing the exacerbation of CAP in clinical practice.