Abstract
This review explores the 'gut-lung axis' in asthma with a focus on commensal fungal organisms. We explore how changes to the intestinal commensal fungal community composition alter lung immune function. We comprehensively review available studies that have profiled the composition of the gut mycobiome in adults and children with asthma, and discuss mechanisms of gut-lung interactions that have been described in animal models of asthma. Studies indicate that intestinal fungal dysbiosis, such as an increased abundance of certain fungi like Candida, can elevate the risk of asthma in children and exacerbate it in adults. This effect is mediated through various pathways: the host immune system's sensing of dysbiosis via C-type lectin receptors (e.g., Dectin-2), the impact of pro-inflammatory fungal metabolites (e.g., 12,13-diHOME, prostaglandin E2), and the role of lung immune cells (e.g., group 2 innate lymphoid cells [ILC2], M2 macrophages). We also describe strategies for modulating the gut mycobiome as potential therapies for severe asthma. The review concludes by emphasizing the necessity for further research into the role of the gut mycobiome in asthma to deepen our understanding of these complex interactions.