Selective M1 macrophage polarization in granuloma-positive and granuloma-negative Crohn's disease, in comparison to intestinal tuberculosis

BACKGROUND/AIMS: Classical M1 macrophage activation exhibits an inflammatory phenotype while alternative M2 macrophage activation exhibits an anti-inflammatory phenotype. We aimed to determine whether there are discriminant patterns of macrophage polarization in Crohn's disease (CD) and intestinal tuberculosis (iTB). METHODS: Colonic mucosal biopsies from 29 patients with iTB, 50 with CD, and 19 controls were examined. Dual colored immunohistochemistry was performed for iNOS/CD68 (an M1φ marker) and CD163/CD68 (an M2φ marker), and the ratio of M1φ to M2φ was assessed. To establish the innate nature of macrophage polarization, we analyzed the extent of mitochondrial depolarization, a key marker of inflammatory responses, in monocyte-derived macrophages obtained from CD and iTB patients, following interferon-γ treatment. RESULTS: M1φ polarization was more prominent in CD biopsies (P=0.002) than in iTB (P=0.2) and control biopsies. In granuloma-positive biopsies, including those in CD, M1φ predominance was significant (P=0.001). In iTB, the densities of M1φ did not differ between granuloma-positive and granuloma-negative biopsies (P=0.1). Interestingly, higher M1φ polarization in CD biopsies correlated with high inflammatory response exhibited by peripheral blood-derived monocytes from these patients. CONCLUSIONS: Proinflammatory M1φ polarization was more common in colonic mucosa of CD patients, especially in the presence of mucosal granulomas. Further characterization of the innate immune system could help in clarifying the pathology of iTB and CD.

Prevalence of hepatitis B, hepatitis C and human immunodeficiency viral infections in patients with inflammatory bowel disease in north India

BACKGROUND/AIMS: Patients with inflammatory bowel disease (IBD) often require immunosuppressive therapy and blood transfusions and therefore are at a high risk of contracting infections due to hepatitis B (HBV) and hepatitis C (HCV) and human immunodeficiency virus (HIV). In the present study, we assessed the prevalence of these infections in patients with IBD. METHODS: This retrospective study included 908 consecutive patients with IBD (ulcerative colitis [UC], n=581; Crohn's disease [CD], n=327) who were receiving care at a tertiary care center. Ninety-five patients with intestinal tuberculosis (ITB) were recruited as disease controls. Prospectively maintained patient databases were reviewed for the prevalence of HBV surface antigen, anti-HCV antibodies, and HIV (enzyme-linked immunosorbent assay method). HCV RNA was examined in patients who tested positive for anti-HCV antibodies. Prevalence data of the study were compared with that of the general Indian population (HBV, 3.7%; HCV, 1%; HIV, 0.3%). RESULTS: The prevalence of HBV, HCV, and HIV was 2.4%, 1.4%, and 0.1%, respectively, in the 908 patients with IBD. Among the 581 patients with UC, 2.2% (12/541) had HBV, 1.7% (9/517) had HCV, and 0.2% (1/499) had HIV. Among the 327 patients with CD, 2.8% (8/288) had HBV, 0.7% (2/273) had HCV, and 0% (0/277) had HIV. One patient with CD had HBV and HCV coinfection. The prevalence of HBV, HCV, and HIV in patients with ITB was 5.9% (4/67), 1.8% (1/57), and 1.2% (1/84), respectively. CONCLUSIONS: The prevalence of HBV, HCV, and HIV in north Indian patients with IBD is similar to the prevalence of these viruses in the general community. Nonetheless, the high risk of flare after immunosuppressive therapy mandates routine screening of patients with IBD for viral markers.