Increased viability but decreased culturability of Mycobacterium avium subsp. paratuberculosis in macrophages from inflammatory bowel disease patients under Infliximab treatment

• Published in: Medical microbiology and immunology Vol. 204; no. 6; pp. 647 - 656
• Main Authors: Nazareth, Nair, Magro, Fernando, Appelberg, Rui, Silva, Jani, Gracio, Daniela, Coelho, Rosa, Cabral, José Miguel, Abreu, Candida, Macedo, Guilherme, Bull, Tim J., Sarmento, Amélia
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2015; Springer Nature B.V
• Subjects: Adult; Aged; Bacterial Load; Biomedical and Life Sciences; Biomedicine; Case-Control Studies; Female; Humans; Immunology; Inflammatory bowel disease; Inflammatory Bowel Diseases - complications; Inflammatory Bowel Diseases - drug therapy; Infliximab - adverse effects; Infliximab - therapeutic use; Lysosomal-Associated Membrane Protein 1 - metabolism; Macrophages - microbiology; Male; Medical Microbiology; Microbial Viability - immunology; Middle Aged; Mycobacterium avium; Mycobacterium avium subsp. paratuberculosis - genetics; Mycobacterium avium subsp. paratuberculosis - immunology; Original Investigation; Paratuberculosis - etiology; Paratuberculosis - microbiology; Pathogens; Phagocytosis; Phagosomes - immunology; Phagosomes - microbiology; RNA, Ribosomal, 16S - genetics; Virology; Young Adult; Inflammatory bowel disease; Phagosomal maturation; Macrophages; subsp; Mycobacterium avium subsp. paratuberculosis
• ISSN: 0300-8584; 1432-1831
• DOI: 10.1007/s00430-015-0393-2

Mycobacterium avium subsp. paratuberculosis (MAP) has long been implicated as a triggering agent in Crohn’s disease (CD). In this study, we investigated the growth/persistence of both M. avium subsp. hominissuis (MAH) and MAP, in macrophages from healthy controls (HC), CD and ulcerative colitis patients. For viability assessment, both CFU counts and a pre16SrRNA RNA/DNA ratio assay (for MAP) were used. Phagolysosome fusion was evaluated by immunofluorescence, through analysis of LAMP-1 colocalization with MAP. IBD macrophages were more permissive to MAP survival than HC macrophages (a finding not evident with MAH), but did not support MAP active growth. The lower MAP CFU counts in macrophage cultures associated with Infliximab treatment were not due to increased killing, but possibly to elevation in the proportion of intracellular dormant non-culturable MAP forms, as MAP showed higher viability in those macrophages. Increased MAP viability was not related to lack of phagolysosome maturation. The predominant induction of MAP dormant forms by Infliximab treatment may explain the lack of MAP reactivation during anti-TNF therapy of CD but does not exclude the possibility of MAP recrudescence after termination of therapy.