There is an association between periodontal disease and increased gut colonization of pathogenic H. parainfluenzae strains in Crohn's disease patients, as deciphered from a recent study. In order to understand the processes behind H. parainfluenzae-mediated intestinal inflammation, Jiho Sohn et al. looked at the mechanisms of periodontal disease as a modifier for H. parainfluenzae colonization in people with Crohn's disease.

The oral and fecal microbiomes of 50 subjects with and without Crohn's disease were examined for presence of periodontal disease. By using 16S rRNA sequencing, the oral and intestinal microbiomes of Crohn's disease-positive participants and control subjects with and without periodontal disease were described. Oligotyping was used to undertake a strain-level study of H. parainfluenzae, and a strain-specific quantitative polymerase chain reaction (qPCR) test was used to corroborate the results.

In individuals suffering from Crohn's disease, higher levels of H. parainfluenzae strains were linked to periodontal disease. Intestinal inflammation was caused by H. parainfluenzae in a strain-dependent manner. H. parainfluenzae gut colonization was linked to a rise in IFN-g+ CD4+ T cells.

H. parainfluenzae has a strain-specific pathogenic role in intestinal inflammation in Crohn's disease people, thus highlighting the possible influence of periodontal disease on the colonization of the intestinal tract by pathogenic H. parainfluenzae strains.