Article

Activation of OX40 Prolongs and Exacerbates Autoimmune Experimental Uveitis

Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA.
Investigative ophthalmology & visual science (Impact Factor: 3.66). 09/2011; 52(11):8520-6. DOI: 10.1167/iovs.11-7664
Source: PubMed

ABSTRACT T cells are essential for the development of autoimmune uveitis. Although the costimulatory molecule OX40 promotes T-cell function and expansion, it is unclear whether OX40 is implicated in ocular inflammation. The purpose of this study was to examine the role of OX40 in uveitis.
Experimental autoimmune uveitis (EAU) was induced in B10.RIII mice by subcutaneous injection of interphotoreceptor retinoid-binding protein peptide 161-180 (IRBP(161-180)). Some mice received an intravenous administration of OX40-activating antibody on days 0 and 4 after IRBP(161-180) sensitization or on days 10 and 14 of uveitis onset. The severity of EAU was evaluated by histology at different time points. In addition, ocular inflammatory cytokine expression was determined by real time-PCR, and peripheral activated CD4(+)CD44(+)CD62L(-) T cells and IL-7Rα expression were analyzed by flow cytometry. The activated CD4(+)CD44(+) lymphocytes were rechallenged with IRBP(161-180) in vitro to assess their antigen recall response.
The authors demonstrated a marked OX40 expression by infiltrating lymphocytes in enucleated human eyes with end-stage inflammation. In addition, the administration of OX40-activating antibody prolonged and exacerbated the disease course of EAU. Moreover, activation of OX40 not only increased CD4(+)CD44(+)CD62L(-) lymphocyte number, it upregulated IL-7Rα expression in the activated T-cell population. Lastly, these cells exhibited a stronger interferon-γ response to IRBP(161-180) restimulation in vitro.
The results reveal a pathogenic role of OX40 in uveitis. Furthermore, the upregulation of IL-7R in CD4(+)CD44(+) lymphocytes suggests that the activation of OX40 promotes the generation or expansion of uveitogenic memory T cells.

Download full-text

Full-text

Available from: Grazyna Adamus, Jul 30, 2015
0 Followers
 · 
118 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Rapamycin, a potent immune modulator, is used to treat transplant rejection and some autoimmune diseases. Uveitis is a potentially severe inflammatory eye disease, and 2 clinical trials of treating uveitis with rapamycin are under way. Unexpectedly, recent research has demonstrated that low dose rapamycin enhances the memory T cell population and function. However, it is unclear how low dose rapamycin influences the immune response in the setting of uveitis. B10.RIII mice were immunized to induce experimental autoimmune uveitis (EAU). Ocular inflammation of control and rapamycin-treated mice was compared based on histological change. ELISPOT and T cell proliferation assays were performed to assess splenocyte response to ocular antigen. In addition, we examined the effect of rapamycin on activation-induced cell death (AICD) using the MitoCapture assay and Annexin V staining. Administration of low dose rapamycin exacerbated EAU, whereas treating mice with high dose rapamycin attenuated ocular inflammation. The progression of EAU by low dose rapamycin coincided with the increased frequency of antigen-reactive lymphocytes. Lastly, fewer rapamycin-treated T cells underwent AICD, which might contribute to exaggerated ocular inflammation and the uveitogenic immune response. These data reveal a paradoxical role for rapamycin in uveitis in a dose-dependent manner. This study has a potentially important clinical implication as rapamycin might cause unwanted consequences dependent on dosing and pharmacokinetics. Thus, more research is needed to further define the mechanism by which low dose rapamycin augments the immune response.
    PLoS ONE 05/2012; 7(5):e36589. DOI:10.1371/journal.pone.0036589 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study aims to investigate the role of OX40 ligand (OX40L) in ocular inflammation via abrogation of retinal pigment epithelium (RPE)-mediated immunosuppression using an in vitro expression approach. OX40L cDNA was polymerase chain reaction-amplified and cloned into an eYFP fusion vector. Cultured retinal pigment epithelial cells (ARPE-19) were transfected with the vector. Total RNA from unstimulated or inflammatory cytokine-stimulated ARPE cells were isolated and analyzed for OX40L expression by reverse transcription-polymerase chain reaction. Peripheral blood mononuclear cells (PBMCs) were isolated from healthy human donors. Human ARPE cells (±OX40L ± GITR ligand (GITRL) expression) and PBMCs were co-cultured for in vitro proliferation studies. Polymerase chain reaction confirmed the insertion of the OX40L gene into the fusion vector. Flow cytometry and fluorescence microscopy further confirmed surface expression of OX40L on ARPE cells after transfection. OX40L expression was induced in the RPE cells stimulated with pro-inflammatory cytokines. In the co-culture studies, there was a significant reversal (20% to 30%) of the RPE-induced suppression of activated PBMCs when the ARPE cells were transfected with OX40L. When both OX40L and GITRL were concomitantly transfected into ARPE cells, there was an additive reversal of RPE-mediated T cell suppression, when compared to the reversal caused by RPE cells expressing either OX40L alone or GITRL alone. Using an in vitro approach, we found that OX40L causes an abrogation of the RPE-mediated immunosuppression. OX40L appears to be regulated in the ARPE-19 cell line and may play an important role in the pathogenesis of various ocular inflammatory conditions.
    01/2013; 3(1):12. DOI:10.1186/1869-5760-3-12
  • [Show abstract] [Hide abstract]
    ABSTRACT: Uveitis is a heterogeneous collection of diseases with polygenic and environmental influences. This heterogeneity presents challenges in trial design and selection of end points. Despite the multitude of causes, therapeutics targeting common inflammatory pathways are effective in treating diverse forms of uveitis. These treatments, including corticosteroids and immunomodulatory agents, although often effective, can have untoward side effects, limiting their utility. The search for drugs with equal or improved efficacy that are safe is therefore paramount. A mechanism-based approach is most likely to yield the future breakthroughs in the treatment of uveitis. We review the literature and provide examples of the nuances of immune regulation and dysregulation that can be targeted for therapeutic benefit. As our understanding of the causes of uveitis grows we will learn how to better apply antibodies designed to block interaction between inflammatory cytokines and their receptors. T-lymphocyte activation can be targeted by blocking co-stimulatory pathways or inhibiting major histocompatibility complex protein interactions. Furthermore, intracellular downstream molecules from cytokine or other pathways can be inhibited using small molecule inhibitors, which have the benefit of being orally bioavailable. An emerging field is the lipid-mediated inflammatory and regulatory pathways. Alternatively, anti-inflammatory cytokines can be provided by administering recombinant protein, and intracellular "brakes" of inflammatory pathways can be introduced potentially by gene therapy. Novel approaches of delivering a therapeutic substance include, but are not limited to, the use of small interfering RNA, viral and nonviral gene therapy, and microparticle or viscous gel sustained-release drug-delivery platforms. The author(s) have no proprietary or commercial interest in any materials discussed in this article.
    Ophthalmology 10/2013; 121(1). DOI:10.1016/j.ophtha.2013.08.029 · 6.17 Impact Factor
Show more