Asquith M, Sternes PR, Costello ME, et al. - Five hundred sixty-eight stool and biopsy samples from 6 intestinal sites were collected from 107 healthy unrelated individuals, and stool samples were gathered from 696 twin pairs from the TwinsUK cohort so that researchers could investigate the impact of HLA–B27 and HLA–DRB1 RA risk alleles on the composition of the intestinal microbiome in healthy individuals. Between the overall microbial composition and both the HLA–B27 genotype and the HLA–DRB1 RA risk allele, relationships were discovered. These correlations were replicated via the stool samples from the TwinsUK cohort. Hence, the variations in intestinal microbiome composition observed in AS and RA were at least partly because of the impacts of HLA-B27 and HLA–DRB1 on the gut microbiome. These conclusions sustained the hypothesis that HLA alleles operated to cause or raised the risk of these diseases through interaction with the intestinal microbiome and recommended that therapies targeting the microbiome may be efficient in inhibiting or treating these diseases.