Epithelial remodeling and microbial dysbiosis in the lower respiratory tract of vitamin A-deficient mouse lungs.

The World Health Organization identified vitamin A deficiency (VAD) as a major public health issue in low-income communities and developing countries, while additional studies have shown dietary VAD leads to various lung pathologies. Once believed to be sterile, research now shows that transient microbial communities exist within healthy lungs and are often dysregulated in patients suffering from malnourishment, respiratory infections, and disease. The inability to parse vitamin A-mediated mechanisms from other metabolic mechanisms in humans with pathogenic endotypes, as well as the lack of data investigating how VAD affects the lung microbiome, remains a significant gap in the field. To address this unmet need, we compared molecular, metatranscriptomic, and morphometric data to identify how dietary VAD affects the lung as well as the lung microbiome. Our research shows structural and functional alterations in host-microbe-diet interactions in VAD lungs compared to vitamin A-sufficient (VAS) lungs; these changes are associated with epithelial remodeling, a breakdown in mucociliary clearance, microbial imbalance, and altered microbial colonization patterns after 8 weeks of vitamin A deficient diet. These findings confirm vitamin A is critical for lung homeostasis and provide mechanistic insights that could be valuable for the prevention of respiratory infections and disease.