Vitamin D and the microbiota connection: understanding its potential to improve COPD outcomes

The mucosa of the respiratory system is an essential site for local vitamin D synthesis, degradation, and signaling. It modulates the inflammatory and immune response by saving the integrity of the mucosal barrier and killing the invading pathogen through the induction of antimicrobial peptides. The proper functioning of the immune system within the respiratory system is influenced by the complex interactions of numerous immune pathways, including the gut-lung axis. Recent research has indicated that the gut microbiota is vital in developing and progressing chronic inflammatory chest conditions, such as asthma and chronic obstructive pulmonary disease (COPD). Furthermore, the immune-modulating function of vitamin D operates through the gut mucosa; hence, the vitamin D receptor is expressed to regulate the antimicrobial peptide. The potential protective role of vitamin D and its correlation with COPD has garnered significant interest. It is currently under exploration as a possible adjuvant therapy to aid in managing frequent exacerbation of COPD. In this review, we explored the connection between vitamin D and the immune system, as well as its relationship with microbiota. We also summarized some novel mechanisms of action of vitamin D supplementation that can impact disease exacerbation.