title: Role of IL-6 in Mycobacterium avium--associated immune reconstitution inflammatory syndrome.
abstract: Immune reconstitution inflammatory syndrome (IRIS) is a major adverse event of antiretroviral therapy in HIV infection, and paradoxically occurs as HIV viremia is suppressed and CD4 T cell numbers recover. IRIS reflects pathogenic immune responses against opportunistic infections acquired during the period of immunodeficiency, but little is understood about the mechanisms of inflammatory pathology. In this study, we show that IL-6 and C-reactive protein levels transiently rise at the time of the IRIS event in HIV-infected patients, unmasking Mycobacterium avium complex infection after starting antiretroviral therapy. To directly test the role of IL-6 in IRIS pathology, we used a model of experimentally inducible IRIS in which M. avium-infected T cell-deficient mice undergo a fatal inflammatory disease after reconstitution with CD4 T cells. We find that IL-6 neutralization reduces C-reactive protein levels, alleviates wasting disease, and extends host survival during experimental IRIS. Moreover, we show that combined blockade of IL-6 and IFN-γ further reduces IRIS pathology, even after the onset of wasting disease. The combination of these clinical and experimental-model data show that the IL-6 pathway is not only a biomarker of mycobacterial IRIS but also a major mediator of pathology distinct from IFN-γ and may be a useful target for therapeutic intervention.
authors: T Lymphocyte Biology Unit, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892;
authors: Daniel L
authors: DL
authors: Barber
authors: Bruno B
authors: BB
authors: Andrade
authors: Cortez
authors: C
authors: McBerry
authors: Irini
authors: I
authors: Sereti
authors: Alan
authors: A
authors: Sher
mesh_terms: D000328:Adult; D000818:Animals; D023241:Antiretroviral Therapy, Highly Active / Q000009:adverse effects; D002097:C-Reactive Protein / Q000276:immunology / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D005260:Female; D015658:HIV Infections / Q000276:immunology / Q000378:metabolism; D006801:Humans; D054019:Immune Reconstitution Inflammatory Syndrome / Q000276:immunology* / Q000378:metabolism; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D015850:Interleukin-6 / Q000276:immunology* / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D008875:Middle Aged; D009162:Mycobacterium avium / Q000276:immunology*; D015270:Mycobacterium avium-intracellulare Infection / Q000276:immunology* / Q000378:metabolism
chemical_list: D015850:Interleukin-6; D007371:Interferon-gamma; D002097:C-Reactive Protein