# Gut-lung axis perturbation and Bifidobacterium potential after spinal cord injury in humans and mice

## TL;DR

Spinal cord injury disrupts the gut-lung connection, but adding Bifidobacterium can reduce lung inflammation and improve gut health in mice.

## Contribution

The study reveals that SCI causes gut-lung microbiota convergence and shows that Bifidobacterium supplementation can mitigate this effect.

## Key findings

- SCI increases similarity between gut and lung microbial communities in humans and mice.
- Oral Bifidobacterium reduces gut-lung similarity and lung inflammation after an E. coli challenge.
- Fecal microbiota transplantation from SCI donors induces gut-lung convergence in healthy recipients.

## Abstract

Spinal cord injury (SCI) predisposes patients to severe respiratory complications. Integrating clinical observations with a mouse model, we identified gut-lung axis perturbation as a key mechanism. SCI increased the similarity between gut and lung microbial communities, consistent with cross-compartment convergence driven by intestinal dysbiosis. Fecal microbiota transplantation from SCI donors reproduced this convergence in healthy recipients. Crucially, oral Bifidobacterium supplementation restored intestinal community structure, reduced gut-lung similarity, and attenuated pulmonary inflammation following an Escherichia coli challenge. These findings indicate that SCI disrupts gut-lung compartmentalization and that augmenting beneficial gut taxa mitigates downstream pulmonary consequences. Microbiota-targeted strategies therefore warrant evaluation as adjuncts to reduce post-SCI respiratory risk.

•SCI increases gut-lung microbiota similarity in humans and mice•Source tracking supports post-SCI cross-compartment convergence•Oral Bifidobacterium improves gut ecology and lowers gut-lung similarity•Probiotic treatment attenuates lung inflammation after E. coli challenge in mice

SCI increases gut-lung microbiota similarity in humans and mice

Source tracking supports post-SCI cross-compartment convergence

Oral Bifidobacterium improves gut ecology and lowers gut-lung similarity

Probiotic treatment attenuates lung inflammation after E. coli challenge in mice

Health sciences