Alteration of the gut microbiota in patients with lung cancer accompanied by chronic obstructive pulmonary diseases

Aim To explore the abundance and diversity of the gut microbiota in patients with lung cancer accompanied by chronic obstructive pulmonary disease (LC-COPD). Methods The study cohort comprised 15 patients with LC-COPD, 49 patients with lung cancer, and 18 healthy control individuals. ELISA was used to detect inflammatory factors in venous blood. 16S rDNA sequencing was performed to determine the abundance and diversity of the gut microbiota. Gas chromatography–mass spectrometry was used to determine the concentration of short-chain fatty acids (SCFAs) in feces samples. Results The α-diversity index indicated that the richness and diversity of the gut microbiota were lower in patients with LC-COPD compared with patients with lung cancer and controls. Principal component analysis revealed significant differences among the three groups (P < 0.05). The linear discriminant analysis effect size algorithm indicated that the o_Lactobacillales, g_Lactobaccillus, f_Lactobaccillaceae, s_Lactobaccillus_oris, c_Bacilli, g_Anaerofustis, s_uncultured organism, and s_bacterium_P1C10 species were prevalent in patients with LC-COPD, while the g_Clostridium_XIVa and g_Butyricicoccus species were prevalent in patients with lung cancer. Furthermore, the concentrations of the SCFAs butyric acid, isobutyric acid, isovaleric acid, and valeric acid tended to be lower in patients with LC-COPD compared with patients with lung cancer and healthy controls, although these intergroup differences were not significant (P > 0.05). Patients with lung cancer had the lowest serum concentration of tumor necrosis factor (TNF)-a. There were no intergroup differences in the concentrations of other inflammatory factors. Conclusions The present study indicated that the abundance and structure of the gut microbiota is altered, and the concentrations of SCFAs may be decreased in patients with LC-COPD. In addition, patients with lung cancer had the lowest serum concentration of TNF-a.