Effective-components combination alleviates PM2.5-induced inflammation by evoking macrophage autophagy in COPD

Bufei Yishen formula (BYF) is clinically used to treat chronic obstructive pulmonary disease (COPD). Effective-component compatibility (ECC) is a combination of five active components derived from BYF, which has an equal effect on COPD to BYF. Our previous study has also demonstrated that ECC can protect COPD rats against PM2.5 exposure. However, the precise mechanisms remain to be elucidated.

To explore the mechanism underlying the anti-inflammatory effects of ECC-BYF against PM2.5-accelerated COPD.

MH-S macrophages were stimulated by PM2.5 suspension to establish an in vitro model. Western blotting and immunofluorescent staining were used to measure the protein levels of autophagy markers. ELISA and quantitative PCR were used to detect the levels of inflammatory cytokines. In vivo, an established PM2.5-accelerated COPD rat model was used to determine the protective effect of ECC-BYF. Lung function, pathology, autophagy, and inflammatory mediators were detected.

Firstly, we observed a significantly increased number of macrophages in the lungs upon PM2.5 exposure. Then, decreased autophagy flux while elevated inflammation was detected in PM2.5-exposed rats and MH-S cells. In MH-S cells, ECC-BYF significantly suppressed the PM2.5-increased inflammatory cytokines production, which was accompanied by the enhancement of autophagy flux. An autophagy inhibitor counteracted the anti-inflammatory effect elicited by ECC-BYF. In addition, ECC-BYF stimulated Foxo3 nuclear translocation and upregulated Foxo3 expression, whereas Foxo3 knockdown abrogated the inhibitory effect of ECC-BYF on inflammation. In PM2.5-accelerated COPD rats, ECC-BYF also attenuated the autophagy disruption and increased Foxo3 in the lungs, finally resulting in a suppression of pulmonary inflammation and an enhancement of lung function.

ECC-BYF can ameliorate PM2.5-aggravated inflammation in COPD, which might be associated with the enhancement of autophagy flux in alveolar macrophages through the activation of Foxo3 signals.