Microbiome sequence analyses have suggested that changes in gut bacterial composition are associated with autoimmune disease in humans and animal models. The mechanisms through which the gut microbiota influences autoimmune responses are still barely known. In a recent study, Jayne S. Danska and colleagues evaluated systemic antibody responses against cultured human gut bacterial strains to determine whether observed patterns of anticommensal antibody (ACAb) responses are associated with type 1 diabetes (T1D) in two cohorts of pediatric study participants. In the first cohort, ACAb responses in sera collected from participants within 6 months of T1D diagnosis were equal to the age-matched healthy controls and also to patients with recent onset Crohn’s disease. In the second cohort, the investigators evaluated whether ACAb responses present before diagnosis were associated with later T1D development and with an HLA genotype (Human Leukocyte Antigen). Serum IgG2 antibodies against Roseburia faecis and against a bacterial consortium were associated with future T1D diagnosis in an HLA DR3/DR4 haplotype–dependent manner.  This approach provides an “immune system’s view” of the microbiome and complements efforts to identify associations between the genomic composition of fecal microbes and autoimmune diseases.¹

1. Paun A et al., 2019, Sci Immunol, 4: eeau8125