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* = Presenting author

P103 Selective M1 macrophage polarisation in Crohn’s disease in comparison to intestinal tuberculosis: a novel observation

P. Das1, S. Pilli2, T. Kumar1, R. Rampal2, I. A. Khan2, A.K. Singh2, D. Kumar3, V. Ahuja*2

1All India Institute of Medical Sciences, Pathology, New Delhi, India, 2All India Institute of Medical Sciences, Gastroenterology, New Delhi, India, 3International Centre for Genetic Engineering and Biotechnology, Mammalian Biology, New Delhi, India

Background

Crohn’s disease (CD) is consequent to a dysregulated immune response to commensal intestinal microflora. In this study, we aimed at determining the M1 and M2 macrophage (�) polarisation pattern in CD and intestinal tuberculosis (iTB), which possibly involve different pathogenesis.

Methods

Intestinal biopsies from 29 patients with iTB (19 with granulomas [Gr] and 10 without), 50 CD (Gr in 8, without Gr in 42), and 19 controls were included. Dual immunohistochemistry was performed for iNOS/ CD68 (a marker of M1 �) and CD163/CD68 (a marker of M2 �). The ratio of iNOS and CD163 positive � 
was assessed in comparison to the CD68 positive � and was compared amongstst the biopsies of iTB, CD and controls.

Results

M1 � polarisation was more prominent in biopsies of CD (p = 0.002), than in iTB (p = 0.2) and controls. M2 � density was not significantly different in CD, iTB, and control biopsies. In all biopsies with granulomas, including those in CD, M1 � infiltrate was significantly dense (p = 0.001). In iTB, the densities of M1 � did not differ between biopsies showing the presence or absence of granulomas (p = 0.1).

Conclusion

M1 � polarisation is quite significant in intestinal biopsies from CD patients, in comparison to iTB, which is further pronounced in the presence of granulomas. In CD, macrophages are mostly activated via a classical macrophage activation pathway, which is different from � activation in iTB.