<scp><i>Mycobacterium avium</i></scp> Subsp. <scp><i>paratuberculosis</i></scp> and Human Endogenous Retrovirus in Italian Patients With Inflammatory Bowel Disease (<scp>IBD</scp>) and Irritable Bowel Syndrome (<scp>IBS</scp>)

Inflammatory bowel disease (IBD), comprising ulcerative colitis (UC) and Crohn's disease (CD) and irritable bowel syndrome (IBS) are distinct gastrointestinal disorders. Mycobacterium avium subspecies paratuberculosis (MAP) is implicated in IBD pathogenesis, while the roles of human endogenous retroviruses (HERVs) are under investigation. We aimed (a) to investigate whether the levels of humoral response to MAP-3865c, HERV-K envelope and HERV-W envelope against the epitopes in IBD/IBS patients; (b) to determine the frequency of micronuclei in IBD patients and (c) to evaluate the possible correlation between genomic damage and humoral response. This study investigates antibody titres against MAP 3865c, HERV-K env and HERV-W env in plasma from 102 IBD, 20 IBS patients and 92 healthy controls (HCs). Micronuclei (MNi) frequency in IBD patients is assessed, correlating with humoral responses and patient genotype profiles. IBD patients exhibited elevated antibody responses to MAP 3865c, with those carrying the GA genotype for TNF-α showing higher anti-MAP 3865c IgG levels. A significant positive correlation was observed between MNi frequency and the humoral response against MAP 3865c in IBD patients. Higher antibody responses to HERV-K env were detected in both IBD and IBS patients compared to HCs, with significant positive correlations found between MAP 3865c and HERV-K env peptide responses in IBD patients. HERV-W env antibody levels were higher in IBS patients than in HCs. Our findings highlight the association between UC and CD and immune responses targeting MAP and HERV-Kenv. Specific genetic profiles may exacerbate inflammation, potentially amplifying genetic damage observed in IBD patients, as indicated by MNi frequencies.