Lactobacillus rhamnosus ameliorates pulmonary dysfunction in a rat model of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory respiratory disorder characterized by persistent airflow limitation and systemic inflammation. Increasing evidence suggests that intestinal microbiota influence respiratory diseases through the gut-lung axis. Probiotics have emerged as potential therapeutic agents capable of modulating immune responses and restoring microbial balance. This study investigated the protective effects of Lactobacillus rhamnosus on pulmonary function, inflammatory responses, and gut microbiota composition in a cigarette smoke and lipopolysaccharide-induced rat model of COPD. Male Wistar rats were randomly assigned to Control, COPD model, Low-dose L. rhamnosus, High-dose L. rhamnosus, and Aminophylline groups. COPD was induced through chronic cigarette smoke exposure combined with intratracheal lipopolysaccharide administration. Pulmonary function parameters, including forced expiratory volume in 0.3 s (FEV₀.₃) and forced vital capacity (FVC), were measured. Lung and colon tissues were examined histopathologically, and serum concentrations of TNF-α, IL-6, IL-1β, and IL-10 were determined by enzyme-linked immunosorbent assay (ELISA). Gut microbiota composition was analyzed using 16 S rRNA gene sequencing. COPD model rats showed significant impairment of pulmonary function, marked increases in serum TNF-α, IL-6, and IL-1β, reduced IL-10 levels, and pronounced lung and colon tissue injury compared with Control animals. Treatment with L. rhamnosus significantly improved pulmonary function, reduced pro-inflammatory cytokine levels while restoring IL-10, and attenuated histopathological damage, with the High-dose group exhibiting greater protective effects than the Low-dose group. Microbiome analysis demonstrated modest alterations in bacterial community composition, although most diversity indices and bacterial taxa did not differ significantly among groups. These findings suggest that L. rhamnosus attenuates COPD-associated inflammation and tissue injury and may exert beneficial effects through modulation of host inflammatory responses and gut microbial composition. Further studies are required to clarify the underlying mechanisms linking probiotic supplementation and the gut-lung axis in COPD.