Immunology and Uveitis

AIMS: To evaluate ocular disease characteristics and successful therapeutic regimens in patients with scleritis associated with relapsing polychondritis (RP). To compare these features with those seen in patients with scleritis associated with other systemic immune-mediated diseases (SIMD). METHODS: Electronic health records of 13 scleritis patients associated with RP were analysed and compared with those of 113 scleritis patients associated with other SIMD seen at two tertiary referral centres. RESULTS: Scleritis in patients with RP was often bilateral (92.3%), diffuse (76.9%), recurrent (84.6%), sometimes with decreased vision (46.2%), anterior uveitis (38.5%), peripheral keratitis (15.4%) and ocular hypertension (30.8%). Patients with scleritis associated with RP more often had bilateral scleritis (p=0.001), necrotising scleritis (23.1%; p=0.02), recurrences (p=0.001) and decreased vision (three of the six with legal blindness; p=0.012), as compared with patients who had scleritis associated with other SIMD. Nine patients (69.2%) had one or more SIMD other than RP, including systemic vasculitis (4) or other autoimmune disease (8); they antedated RP by 9 years (range 2-21 years). Successful therapy included cyclophosphamide (5), methotrexate (3), azathioprine (3), mycophenolate mofetil (2), infliximab (2) and adalimumab (1). CONCLUSIONS: Scleritis may be the first manifestation whose study leads to the diagnosis of RP. Scleritis associated with RP is more often bilateral, necrotising, recurrent and associated with decrease of vision than scleritis associated with other SIMD. About 69.2% of patients will have an additional SIMD disorder. Scleritis associated with RP most often will require immunomodulatory therapy. Occasionally, scleritis with RP may appear while using antitumor necrosis factor α agents.

Experimental autoimmune uveoretinitis (EAU) represents an experimental model for human endogenous uveitis, which is caused by Th1/Th17 cell-mediated inflammation. Natural killer T (NKT) cells recognize lipid antigens and produce large amounts of cytokines upon activation. To examine the role of NKT cells in the development of uveitis, EAU was elicited by immunization with a peptide from the human interphotoreceptor retinoid-binding protein (hIRBP1-20) in complete Freund's adjuvant and histopathology scores were evaluated in C57BL/6 (WT) and NKT cell-deficient mice. NKT cell-deficient mice developed more severe EAU pathology than WT mice. When WT mice were treated with ligands of the invariant subset of NKT cells (α-GalCer or RCAI-56), EAU was ameliorated in mice treated with RCAI-56 but not α-GalCer. IRBP-specific Th1/Th17 cytokines were reduced in RCAI-56-treated compared with vehicle-treated mice. Although the numbers of IRBP-specific T cells detected by hIRBP3-13/I-A(b) tetramers in the spleen and the draining lymph node were the same for vehicle and RCAI-56 treatment groups, RORγt expression by tetramer-positive cells in RCAI-56-treated mice was lower than in control mice. Moreover, the eyes of RCAI-56-treated mice contained fewer IRBP-specific T cells compared with control mice. These results suggest that invariant NKT (iNKT) cells suppress the induction of Th17 cells and infiltration of IRBP-specific T cells into the eyes, thereby reducing ocular inflammation. However, in sharp contrast to the ameliorating effects of iNKT cell activation during the initiation phase of EAU, iNKT cell activation during the effector phase exacerbated disease pathology. Thus, we conclude that iNKT cells exhibit dual roles in the development of EAU.

Omega (ω)-3 long-chain polyunsaturated fatty acids (LCPUFAs) inhibit the production of inflammatory mediators and thereby contribute to the regulation of inflammation. Experimental autoimmune uveitis (EAU) is a well-established animal model of autoimmune retinal inflammation. To investigate the potential effects of dietary intake of ω-3 LCPUFAs on uveitis, we examined the anti-inflammatory properties of these molecules in comparison with ω-6 LCPUFAs in a mouse EAU model. C57BL/6 mice were fed a diet containing ω-3 LCPUFAs or ω-6 LCPUFAs for 2 weeks before as well as after the induction of EAU by subcutaneous injection of a fragment of human interphotoreceptor retinoid-binding protein emulsified with complete Freund's adjuvant. Both clinical and histological scores for uveitis were smaller for mice fed ω-3 LCPUFAs than for those fed ω-6 LCPUFAs. The concentrations of the T helper 1 (Th1) cytokine interferon-γ and the Th17 cytokine interleukin-17 in intraocular fluid as well as the production of these cytokines by lymph node cells were reduced for mice fed ω-3 LCPUFAs. Furthermore, the amounts of mRNAs for the Th1- and Th17-related transcription factors T-bet and RORγt, respectively, were reduced both in the retina and in lymph node cells of mice fed ω-3 LCPUFAs. Our results thus show that a diet enriched in ω-3 LCPUFAs suppressed uveitis in mice in association with inhibition of Th1 and Th17 cell function.

PURPOSE: To report the outcomes of tocilizumab treatment for refractory ocular inflammatory diseases. METHODS: A retrospective case series of 17 patients (28 eyes) diagnosed with recalcitrant ocular inflammatory diseases including uveitis (10 cases), scleritis (six cases) and orbital pseudotumour (one case), who received tocilizumab between April 2010 and March 2015. All patients were initiated with treatment of 4 mg/kg or 8 mg/kg tocilizumab. The primary outcome was absence of inflammation and achievement of steroid sparing at 6 and 9 months. Secondary outcomes were change in visual acuity and major adverse effects of tocilizumab causing discontinuation of the treatment. RESULTS: Mean age at initiation of tocilizumab was 41 ± 16 years. Prior to tocilizumab treatment, all patients underwent unsuccessful conventional immunosuppressive therapy while 94% of patients (16/17) failed treatment with various biological agents. After tocilizumab administration, control of inflammation and steroid sparing were achieved in 63% and 71% of uveitis patients at 6 and 9 months, while 50% of scleritis patients achieved the primary outcome at 6 and 9 months. Mean duration of tocilizumab therapy was 12.6 ± 10.0 (range, 2-35) months. Three of four patients who had a follow-up of at least 18 (range, 18-35) months experienced quiescent inflammation for up to 32 months of tocilizumab use until last visit. Four patients (24%) discontinued tocilizumab due to serious side effects including neutropenia, unacceptable dizziness and nausea, severe angioedema and severe abdominal pain. CONCLUSION: Our series demonstrated moderate efficacy of tocilizumab in recalcitrant uveitis and scleritis. Serious adverse effects were not uncommon.

Vogt-Koyanagi-Harada syndrome (VKH) is a bilateral, diffuse granulomatous uveitis associated with neurological, audiovestibular, and dermatological systems. The primary pathogenesis is T-cell-mediated autoimmune response directed towards melanocyte or melanocyte-associated antigens causing inflammation of the choroidal layer. This phenomenon usually leads to diffuse inflammatory conditions throughout most parts of eye before ocular complications ensue. The diagnosis is achieved mainly by clinical features according to the revised diagnostic criteria of VKH published in 2001, without confirmatory serologic tests as a requirement. However, ancillary tests, especially multimodal imaging, can reliably provide supportive evidence for the diagnosis of early cases, atypical presentations, and evaluation of management. Prompt treatment with systemic corticosteroids and early non-steroidal immunosuppressive drug therapy can lessen visually threatening ocular complications and bring about good visual recovery. Close monitoring warrants visual stabilization from disease recurrence and ocular complications. This article review aims not only to update comprehensive knowledge regarding VKH but also to emphasize three major perspectives of VKH: immunogenetics as the major pathogenesis of the disease, multimodal imaging, and therapeutic options. The role of anti-vascular endothelial growth factor therapy and drug-induced VKH is also provided.