TREM-1 aggravates chronic obstructive pulmonary disease development via activation NLRP3 inflammasome-mediated pyroptosis.

Abstract

Chronic obstructive pulmonary disease (COPD) is a major cause of death globally. Inflammation plays a crucial role in COPD development. Pyroptosis, an inflammatory form of cell death, may involve in the pathogenesis of COPD. This study aims to explore the role and action mechanism of triggering receptor expressed on myeloid cells 1 (TREM-1) in COPD. Here, cigarette smoke stimulation was used to establish COPD model in mice. Cigarette smoke extract combined with lipopolysaccharide was used to stimulate RAW264.7 cells for COPD model in vitro. QRT-PCR and Western blot were performed to detect the expression of mRNA and proteins, respectively, in the lung tissues and cells. Concentration of cytokines was measured using ELISA. H&E staining was used to analyze the pathological changes in lung tissues. The number of infiltrated macrophage was examined using immunofluorescence. LP17 was used to silence the expression of TREM-1. The results showed that TREM-1 was highly expressed in COPD. In vivo, inhibition of TREM-1 effectively improved the injury in lung tissues of COPD mouse, and reduced the infiltration of macrophages. Moreover, inhibition of TREM-1 in vivo and in vitro notably suppressed the activation of NLRP3 inflammasome and pyroptosis. Rescue experiment demonstrated that TREM-1 activated pyroptosis via regulating NLRP3 inflammasome. Overall, our results proved that TREM-1 promoted the lung injury and inflammation in COPD mouse through activation of NLRP3 inflammasome-mediated pyroptosis. Our data indicated a novel mechanism of TREM-1 in COPD development, and maybe provide a novel therapeutic target for COPD treatment.