Context: Cushing's Syndrome (CS) is a severe endocrine disease characterized by excessive secretion of cortisol with multiple metabolic disorders. While gut dysbiosis plays a vital role in metabolic disorders, the role of gut microbiota in CS remains unclear.
Objective: The objective of this work is to examine the alteration of gut microbiota in patients with CS.
Methods: We performed shotgun metagenomic sequencing of fecal samples from 78 patients with CS and 78 healthy controls matched for age and body mass index. Furthermore, we verify the cortisol-degradation capacity of Ruminococcus gnavus in vitro and identify the potential metabolite by LC-MC/MS.
Results: We observed significant differences in microbial composition between CS and controls in both sexes, with CS showing reduced Bacteroidetes (Bacteroides vulgatus) and elevated Firmicutes (Erysipelotrichaceae_bacterium_6_1_45) and Proteobacteria (Enterobacter cloacae). Despite distinct causes of hypercortisolism in ACTH-dependent and ACTH-independent CS, we found no significant differences in metabolic profiles or gut microbiota between the two subgroups. Furthermore, we identified a group of gut species, including R. gnavus, were positively correlated with cortisol levels in CS. These bacteria were found to harbor cortisol-degrading desAB genes and were consistently enriched in CS. Moreover, we demonstrated the efficient capacity of R. gnavus to degrade cortisol to 11-oxygenated androgens in vitro.
Conclusions: This study provides evidence of gut microbial dysbiosis in patients with CS and identifies a group of CS-enriched bacteria capable of degrading cortisol. These findings highlight the potential role of gut microbiota in regulating host steroid hormone levels, and consequently host health.
Keywords: Ruminococcus gnavus; Cortisol; Cushing’s Syndrome; Gut Microbiome.
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