Immune Fitness and Biomarkers of Immune Function: Relationships with the Oral and Gut Microbiome Composition

Background:Immune fitness refers to the body's capacity to respond to health challenges, such as infections, by activating an appropriate immune response. The aim of the current study was to investigate the relationship between oral and gut microbiota community structure and immune fitness scores. Methods:Stool and saliva samples were collected to assess compositions of both oral and gut microbiota. Immune fitness was assessed with a single-item scale ranging from 0 (very poor) to 10 (excellent). Additionally, saliva samples were analyzed to measure the concentrations (pg/ml) of pro-inflammatory biomarkers interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-alpha (TNF-α). Spearman's correlations were computed between microbiota abundance, immune fitness, and salivary biomarker levels. Bootstrapping was used to adjust for the relatively small sample size in the correlation analysis. Results:A total of 29 healthy participants (15 males; 14 females) enrolled in the study, with a mean age of 21.1 years old. Analysis of the salivary microbiota revealed significant negative correlations between self-reported immune fitness scores and the relative abundances of putative oral proinflammatory genera Selenomonas (r = -0.610), and Lachnospiraceae uncultured (r = -0.501). In the fecal microbiota, immune fitness scores showed a significant positive correlation with the relative abundance of putative beneficial butyrate-producing genus Lachnoclostridium (r = 0.513), and significant negative correlations with commensal gut bacterial genera Colidextribacter (r = -0.582) and Lachnospiraceae FCS020 group (r = -0.504). Conclusion:Self-reported immune fitness is associated with the oral and gut microbiota community. The findings demonstrate the importance of microbiota in immune function and support the use of self-assessment scales to evaluate immune fitness.