ObjectiveTo explore the characteristics of induced sputum microbiome in the patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).MethodsInduced sputum samples from 55 patients with AECOPD and 45 patients with stable COPD were analyzed by sequencing of 16S rRNA gene. Microbiota was measured by alpha diversity, beta diversity and LDA effect size analysis (LefSe).ResultsThe microbiome diversity of induced sputum in the AECOPD group was lower than that in the stable COPD group. The microbiome richness in the AECOPD group was higher than that in the stable COPD group. The microbiome structure changed in the AECOPD group compared with the stable COPD group. The proportion of some common pathogens got enriched. The levels of hypersensitive C reactive protein (hs-CRP), interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-α) and Global Initative for Chronic Obstructive Lung Disease (GOLD) grade were negatively related to the diversity of microbiome in the AECOPD group.ConclusionsThe microbiome diversity of induced sputum in AECOPD patients is decreased, and is negatively correlated with the levels of hs-CRP, IL-8, TNF-α and GOLD grade. There are differences in the microbiome structure between AECOPD and stable COPD patients. Some enrichment of common pathogens are found in the induced sputum of patients with AECOPD. These results suggest that there is a significant bacterial dysbiosis in patients with AECOPD.
Objective To investigate the role of cysteinyl aspartate specific proteinase-3 (Caspase-3)/ gasdermin-E (GSDME)-mediated pyroptosis in skeletal muscle atrophy induced by cigarette smoke in mice.Methods To construct a mouse model of COPD, C57BL/6 mice were exposed to cigarette smoke (CS) for 24 weeks. HE staining was used to observe the changes in the morphology of the gastrocnemius muscle in mice. Immunohistochemistry was used to detect the expression of pyroptosis-related proteins in gastrocnemius muscle. To construct a model of skeletal muscle cell atrophy in vitro, C2C12 myoblasts were induced to differentiate into skeletal muscle cells with 2% horse serum, and then skeletal muscle cells were treated with cigarette smoke extract (CSE). Skeletal muscle cells were further treated with the caspase-3 inhibitor Z-DEVD-FMK and the GSDME inhibitor Dimethyl fumarate (DMF) to explore the effects of inhibition of caspase-3/GSDME on CSE-induced skeletal muscle cell atrophy. To observe the effects of TNF-α on the expression of caspase-3 and GSDME proteins as well as the impact on myotubes, skeletal muscle cells were stimulated with tumor necrosis factor-alpha (TNF-α). Western blotting was applied to detect protein expression levels of caspase-3 and GSDME in skeletal muscle cells. Hoechst 33342/ Hoechst33342/ Propidium Iodide (PI) staining was applied to detect the PI-positive rate of skeletal muscle cells. The lactate dehydrogenase (LDH) release of C2C12 myotubes was measured by LDH release test. Immunofluorescence was used to detect changes in myotube diameter. Results CS-induced skeletal muscle atrophy was observed in mice, accompanied by increased pyroptosis- associated proteins (c-caspase-3 and GSDME-N) (P<0.05). CSE also induced elevated c-caspase-3 and GSDME-N expression in C2C12 cells , resulting in increased LDH release, positive ratio of PI, along with reduced myotube diameter (P<0.05). In addition, TNF-α promotes myotube atrophy and the expression of cleaved-caspase-3 and GSDME-N proteins in skeletal muscle cells. ConclusionCS can induce skeletal muscle atrophy through activated TNF-α/Caspase-3/GSDME-mediated pyroptosis.