Controlling Our Immune System — 9

Across a multitude of studies, the gut microbiome composition in people with autoimmune conditions is different from those who are healthy. That doesn’t establish cause and effect, but it does suggest fruitful lines of inquiry. In lupus, for example, an Enterococcus species (E. gallinarum) has been implicated as disease causing, with specific autoantibodies, in susceptible individuals. A strain of Subdoligranulum has been implicated to be causal in some individuals with rheumatoid arthritis, likely via gastrointestinal barrier breakdown. The onset of type 1 diabetes has been correlated with an antibody response to certain gut bacteria. In multiple sclerosis, patterns of microbiome alterations have been noted in several studies. Interestingly, a systematic review of eighty-two studies of the gut microbiome in autoimmune disorders and cancer found inversion, in which certain Bifidobacterium species are increased in autoimmunity, decreased in cancer. In general, the imbalance of microorganisms in the gut microbiome likely plays a substantial role in autoimmune diseases.

The first rigorous trial to show efficacy against Long COVID tested a microbiome strategy. Long COVID is a condition that is characterized by a dysregulated immune system (gone haywire) with autoimmune features. In Hong Kong, 460 Long COVID patients were randomly assigned to a synbiotic preparation (three lyophilized Bifidobacteria strains and three probiotic compounds) or placebo. Significant improvement of symptoms in the microbiome intervention group was observed through the double-blind design.

From single-cell analytics, the discovery that activated dendritic cells produce lactate, alongside a probiotic that produces lactate, both markedly suppressed T cell–mediated autoimmunity, which may have important implications regarding manipulating our microbiome. A kidney autoimmune disease, IgA nephropathy, has been linked to a specific gut microbiome, Akkermansia muciniphila. In context, the outlook for fine-tuning the gut microbiome with prebiotics, stimulating the growth of specific bacteria, and probiotics, with microorganisms, is exceptionally promising. We also know that response to autoimmune treatment can be affected by the gut microbiome composition, such as seen with the effect of sulfasalazine therapy for inflammatory bowel disease or the response to teplizumab for type 1 diabetes. Caloric restriction has an impact on gut-mediated immunity, promoting large intestine Bifidobacteria, short-chain fatty acid production, and dendritic cell function. A randomized trial testing the addition of navy beans to the diet showed a pronounced shifting of the gut microbiome toward a more diverse, favorable composition with reduced immune and inflammation biomarkers.