Role of the gut-lung axis in sepsis and the effect of probiotics on pulmonary complications.

INTRODUCTION

Sepsis is a major cause of mortality and organ failure, particularly associated with pulmonary complications. This study investigates the role of the gut-lung axis in sepsis-induced lung injury and explores the therapeutic potential of the probiotic Lactobacillus rhamnosus GG in improving these effects.

METHODS

Using a cecal ligation and puncture (CLP) model in male Wistar rats, we assessed pulmonary function, histopathology, and inflammation. Twenty-four animals were randomly assigned into four groups (n = 8/group): Control, Sepsis, Probiotic, and Sepsis + Probiotic. Lactobacillus rhamnosus GG (2 × 10⁸ CFU/day) was administered orally for seven days. Pulmonary function was assessed using whole-body plethysmography and flexiVent, while lung histopathology and fibrosis were evaluated using hematoxylin and eosin and Masson's trichrome staining. Inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-10) were quantified by ELISA, gut microbiota composition was analyzed by 16S rRNA sequencing, and arterial blood gas and hemodynamic parameters were recorded.

RESULTS

Sepsis significantly impaired pulmonary function, characterized by reduced tidal volume and lung compliance, increased respiratory rate, hypoxemia, hypercapnia, metabolic acidosis, hypotension, and tachycardia (p < 0.01). Peripheral neutrophil and macrophage counts were elevated, and severe gut dysbiosis was observed, marked by reduced microbial diversity and increased Proteobacteria abundance. Probiotic treatment significantly improved pulmonary mechanics and lung histology compared to untreated septic animals. Probiotic supplementation also restored gut microbiota diversity, reduced pro-inflammatory cytokines, and enhanced anti-inflammatory responses.

DISCUSSION: These results suggest that Lactobacillus rhamnosus GG acts via the gut-lung axis to alleviate sepsis-induced pulmonary dysfunction, supporting its potential as an adjunctive therapy for sepsis.