title: Mice genetically inactivated in interleukin-17A receptor are defective in long-term control of Mycobacterium tuberculosis infection.
abstract: Interleukin-17A (IL-17A), a pro-inflammatory cytokine acting on neutrophil recruitment, is known to play an important role during Mycobacterium tuberculosis infection, but the role of IL-17A receptor signalling in immune defence against this intracellular pathogen remains poorly documented. Here we have analysed this signalling using C57BL/6 mice genetically inactivated in the IL-17 receptor A subunit (IL-17RA(-/-) ). Although early after infection bacterial growth was controlled to the same extent as in wild-type mice, IL-17RA(-/-) mice were defective in exerting long-term control of M. tuberculosis infection, as demonstrated by a progressively increasing pulmonary bacterial burden and shortened survival time. Compared with infected wild-type mice, IL-17RA(-/-) mice showed impaired recruitment of neutrophils to the lungs at the early but not the late stage of infection. Pulmonary tumour necrosis factor-α, IL-6 and particularly IL-10 levels were decreased in the absence of IL-17RA signalling, whereas IL-1β was increased. CD4(+) -mediated and γδ-mediated IL-17A production was dramatically increased in IL-17RA(-/-) mice (confirming part of their phenotype), whereas production of interferon-γ and expression of the bactericidal enzyme inducible nitric oxide synthase were not affected. Collectively, our data suggest that early but not late neutrophil recruitment is essential for IL-17A-mediated long-term control of M. tuberculosis infection and that a functional interferon-γ response is not sufficient to control M. tuberculosis growth when the IL-17RA pathway is deficient. As treatment of auto-immune diseases with anti-IL-17A antibodies is actually being tested in clinical studies, our data suggest that caution should be taken with respect to possible reactivation of tuberculosis.
authors.affiliation: Service Immunology, Scientific Institute of Public Health WIV-ISP (Site Ukkel), Brussels, Belgium.
authors.forename: Danielle
authors.initials: D
authors.lastname: Freches
authors.forename: Hannelie
authors.initials: H
authors.lastname: Korf
authors.forename: Olivier
authors.initials: O
authors.lastname: Denis
authors.forename: Xavier
authors.initials: X
authors.lastname: Havaux
authors.forename: Kris
authors.initials: K
authors.lastname: Huygen
authors.forename: Marta
authors.initials: M
authors.lastname: Romano
mesh_terms: D000818:Animals; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009169:Mycobacterium tuberculosis; D053722:Receptors, Interleukin-17 / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D014376:Tuberculosis / Q000276:immunology*
chemical_list: D016207:Cytokines; C491673:Il17ra protein, mouse; D053722:Receptors, Interleukin-17
keywords: interleukin-17A; interleukin-17RA−/−; tuberculosis