Objective The mechanism of action of IL-22 in inflammatory arthritis remains unknown. IL-22 deficient mice have intact humoral and cellular immune response to collagen and yet have a reduced incidence of collagen induced arthritis. Further, administration of anti-IL-22 does not reduce severity of clinical arthritis but improves only certain aspects of joint inflammation as assessed by histology. In this report we studied the mechanism of action and the role of systemic IL-22 in modulating target organ inflammation. Methods CIA was induced in DBA mice following immunization with collagen and complete Freund's adjuvant. Expression of IL-22 and its receptor was elucidated in lymphoid organ and target tissues during various phases of arthritis. The effector functions of IL-22 on induction/regulation of various cytokines in in-vitro restimulation cultures were analyzed by ELISA. Recombinant IL-22 with or without anti-IL-10 antibodies was administered to mice following immunization with collagen and prior to the onset of arthritis. Severity of arthritis was evaluated by clinical scoring and histopathology. Anti-collagen antibodies in sera of mice were analyzed by ELISA. Results IL-22 and IL-22 receptor were upregulated in lymphoid organs and joints during the course of arthritis. In vitro IL-22 augmented IL-10, IL-17 and IL-6 in lymphoid tissues. Administration of recombinant IL-22 was associated with increase in IL-10 in-vivo and significant reduction in the progression of severity of arthritis. Anti-IL-10 antibody was associated with the abrogation of this protective effect of IL-22. Conclusion Our data shows, for the first time, that IL-22 plays a protective role in inflammatory arthritis.
ObjectiveIL-22 is elevated in patients with inflammatory arthritis and correlates with disease activity. IL-22 deficient mice have reduced incidence of arthritis. Recombinant IL-22 restrains progression of arthritis via increase in IL-10 responses when administered prior to onset of arthritis. These findings imply a possible dual role of IL-22 in inflammatory arthritis depending on the phase of arthritis. Experiments outlined here were designed to elucidate the contribution of endogenous IL-22 before and after the onset of arthritis.MethodsCollagen induced arthritis (CIA) was induced in DBA1 or IFN-γ deficient mice following immunization with collagen and complete Freund's adjuvant. Anti-IL-22 antibody or isotype control were administered prior to or after onset of arthritis and disease progression assessed by clinical scoring and histopathology. IL-22, IL-17 and IFN-γ responses were measured by ELISA and flowcytometry. Anti-collagen antibody responses were analyzed by ELISA. Expression of IL-22R1 in CD4+ cells was elucidated by flowcytometry and real time PCR.ResultsCollagen specific IL-22 responses were expanded during arthritis and IL-22 producing cells were discrete from IL-17 or IFN-γ producing cells. Neutralization of IL-22 after onset of arthritis resulted in significant increase in Th1 responses and significantly reduced severity of arthritis. CD4+ cells from arthritic mice showed increased surface expression of IL-22R1. In vitro, CD4+T cells cultured with antigen presenting cells in the presence or absence of IL-22 suppressed or induced IFN-γ, respectively. The protective effect of anti-IL-22 was reversed in IFN-γ deficient mice. Moreover, administration of anti-IL-22 prior to onset of arthritis augmented arthritis severity.ConclusionWe show for the first time that IL-22 plays a dual role: protective prior to the onset of arthritis and pathogenic after onset of arthritis. The pathogenic effect of IL-22 is dependent on suppression of IFN-γ responses. IL-17 responses remained unchanged with the administration of anti-IL22 antibody. IL-22R1 is upregulated on CD4+T cells during arthritis and regulates IFN-γ in T cells.
Interleukin (IL)-17 plays a critical role in inflammation. Most studies to date have elucidated the inflammatory role of IL-17A, often referred to as IL-17. IL-17F is a member of the IL-17 family bearing 50% homology to IL-17A and can also be present as heterodimer IL-17AF. This study elucidates the distribution and contribution of IL-17A, F and AF in inflammatory arthritis. Neutralizing antibody to IL-17A alone or IL-17F alone or in combination was utilized in the mouse collagen-induced arthritis (CIA) model to elucidate the contribution of each subtype in mediating inflammation. IL-17A, F and AF were all increased during inflammatory arthritis. Neutralization of IL-17A reduced the severity of arthritis, neutralization of IL-17A+IL-17F had the same effect as neutralizing IL-17A, while neutralization of IL-17F had no effect. Moreover, significantly higher levels of IL-17A and IL-17F were detected in peripheral blood mononuclear cells (PBMC) from patients with rheumatoid arthritis (RA) in comparison to patients with osteoarthritis (OA). IL-17A and AF were detected in synovial fluid mononuclear cells (SFMC) in RA and OA, with IL-17A being significantly higher in RA patients. Enriched CD3+ T cells from RA PBMCs produced singnificantly high levels of IL-17A and IL-17AF in comparison to OA peripheral blood CD3+ T cells. IL-17A, F and AF were undetectable in T cells from SFMCs from RA and OA. While IL-17A, F, and AF were all induced during CIA, IL-17A played a dominant role. Furthermore, production of IL-17A, and not IL-17F or IL-17AF, was elevated in PBMCs, SFMCs and enriched peripheral blood CD3+ T in RA.
After an initial increase in the viral load immediately posttransplantation, there is a reduction in viral load. A concomitant timed dissection of the immune response shows a complex interactive environment in which, despite immunosuppression, not only the antiviral immune response persists but the virus is also able to modulate the host immune response for its survival. Per se, HCV does not adversely affect the allograft or patient outcome in this case-control study.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.