# Dysbiosis of the Gut–Lung Axis and Its Immune Correlates During Pulmonary Cryptococcus neoformans Infection

## TL;DR

This study shows that infection with Cryptococcus neoformans disrupts the gut and lung microbiomes, linking these changes to immune responses and suggesting microbiome-based treatments.

## Contribution

The study reveals the coordinated dysbiosis of the gut–lung axis and its immune correlates during cryptococcosis in a mouse model.

## Key findings

- Pulmonary infection caused dysbiosis in both lung and gut microbiota, with reduced beneficial microbes and increased pathogens.
- Lung dysbiosis correlated with IL-17-driven inflammation, while gut dysbiosis linked to systemic immune activation in the spleen.
- Microbial metabolic pathways were disrupted, and lung and gut dysbiosis were positively correlated during infection.

## Abstract

Cryptococcus neoformans is a major fungal pathogen responsible for life-threatening meningitis, especially in immunocompromised individuals. Although the gut–lung axis is known to regulate immune responses in respiratory infections, its role in cryptococcosis remains unclear. This study aimed to define the dynamic changes in the gut and lung microbiota and their relationship with host immunity during C. neoformans infection. Using a mouse model, we found that pulmonary infection induced significant dysbiosis in both the lung and gut microbiota, marked by decreased beneficial commensals and increased opportunistic pathogens. Integrated analysis showed these microbial shifts were closely associated with distinct immune responses: lung dysbiosis correlated with a strong IL-17-mediated pulmonary inflammatory response, while gut dysbiosis was linked to systemic immune activation in the spleen. Functional metagenomic prediction further revealed widespread disruption in microbial metabolic pathways, including energy metabolism and biosynthesis, in both sites. Importantly, a positive correlation was observed between lung and gut dysbiosis, indicating an interconnected gut–lung axis during cryptococcosis. These findings demonstrate that C. neoformans infection causes coordinated disruptions in microbiota and immunity across the gut–lung axis, underscoring the microbiome as a critical modulator of host response and suggesting potential avenues for microbiome-targeted therapies.