Functions of mucosal associated invariant T cells in eye diseases.

Mucosal-associated invariant T (MAIT) cells are a unique subset of T cells that recognizes metabolites derived from the vitamin B2 biosynthetic pathway. Since the identification of cognate antigens for MAIT cells, knowledge of the functions of MAIT cells in cancer, autoimmunity, and infectious diseases has been rapidly expanding. Recently, MAIT cells have been found to contribute to visual protection against autoimmunity in the eye. The protective functions of MAIT cells are induced by T-cell receptor (TCR)-mediated activation. However, the underlying mechanisms remain unclear. Thus, this mini-review aims to discuss our findings and the complexity of MAIT cell-mediated immune regulation in the eye.

Clinical Features of Pediatric Uveitis at a Tertiary Referral Center in the Western Region of Japan.

PURPOSE: This study aimed to assess the clinical features of pediatric uveitis at a tertiary referral center in Western Japan. METHODS: One hundred forty eyes of 80 patients aged <20 years at the time of uveitis onset, who visited Kyushu University Hospital between January 2010 and December 2019 were included in this study. Clinical records were retrospectively reviewed. Demographics, clinical findings, treatments, and visual prognoses were compared between the disease groups. RESULTS: Of 80 patients, 32 were males and 48 were females. The average age of onset was 12.5 ± 4.8 (0-19) years. Tubulointerstitial nephritis and uveitis (TINU) and juvenile idiopathic arthritis (JIA) were the most frequent causes, accounting for 11.3% and 10% of cases, respectively, followed by sarcoidosis (5%), Behçet's disease, acute anterior uveitis, Vogt-Koyanagi-Harada disease, and juvenile chronic iridocyclitis (3.8% each). Infectious uveitis accounted for 7.6% of the cases: cytomegalovirus was the most frequent agent. Of these cases, 43.8% were unclassified. Systemic therapies were administered to 87.5% of the patients with JIA, 33.3% of those with TINU, and 28.6% of the other diagnostic groups. In the unclassified group, 80% of the patients were followed up with only topical corticosteroids. LogMAR visual acuity of 0 or less accounted for more than 80% in the final examination. CONCLUSION: TINU and JIA were the most common causes of pediatric uveitis. Although each required systemic therapy, most unclassified cases of pediatric uveitis were managed by topical corticosteroids alone with good visual prognosis. Accurate diagnosis is important for pediatric uveitis management.

Long-term outcomes of infliximab in patients with Behçet's disease-associated uveitis.

OBJECTIVES: To evaluate long-term outcomes of infliximab (IFX) treatment in patients with Behçet's disease (BD)-associated uveitis. PATIENTS AND METHODS: We retrospectively analyzed the cases of patients with BD-associated uveitis treated with IFX for > 5 years. We compared the numbers of ocular inflammatory attacks, ocular disease activities, and visual acuity before and after the initiation of IFX treatment. RESULTS: The 24 patients were 20 men and 4 women. Their mean age at the initiation of IFX treatment was 37.3 ± 9.2 years. The mean term from the initiation of IFX treatment was 10.3 ± 2.4 years. The average number of ocular inflammatory attacks was 5.4 ± 2.1 per 12 months before the IFX treatment and significantly lower at 0.83 ± 0.96 per 12 months after the initiation of IFX treatment (p < 0.05). We used a scoring system for BD-associated uveitis named the Behçet's disease ocular attack score 24 (BOS24) to estimate the changes in ocular disease activities between before and after initiation of IFX treatment. The average score decreased significantly from 7.58 ± 2.77 to 2.55 ± 2.74 after the initiation of IFX treatment (p < 0.05). Even after > 5 years of the treatment, both the number of ocular attacks and the BOS24 score kept decreasing. The visual acuity in 42 of 48 eyes (24 patients) was improved or maintained. CONCLUSIONS: IFX was effective for controlling ocular inflammatory attacks and diminishing ocular disease activities in patients with BD-associated uveitis, and it maintained the patients' visual acuity.

Intraocular human cytomegaloviruses of ocular diseases are distinct from those of viremia and are capable of escaping from innate and adaptive immunity by exploiting HLA-E-mediated peripheral and central tolerance.

Human cytomegalovirus (HCMV) infections develop into CMV diseases that result in various forms of manifestations in local organs. CMV-retinitis is a form of CMV disease that develops in immunocompromised hosts with CMV-viremia after viruses in the peripheral circulation have entered the eye. In the HCMV genome, extensive diversification of the UL40 gene has produced peptide sequences that modulate NK cell effector functions when loaded onto HLA-E and are subsequently recognized by the NKG2A and NKG2C receptors. Notably, some HCMV strains carry UL40 genes that encode peptide sequences identical to the signal peptide sequences of specific HLA-A and HLA-C allotypes, which enables these CMV strains to escape HLA-E-restricted CD8+T cell responses. Variations in UL40 sequences have been studied mainly in the peripheral blood of CMV-viremia cases. In this study, we sought to investigate how ocular CMV disease develops from CMV infections. CMV gene sequences were compared between the intraocular fluids and peripheral blood of 77 clinical cases. UL40 signal peptide sequences were more diverse, and multiple sequences were typically present in CMV-viremia blood compared to intraocular fluid. Significantly stronger NK cell suppression was induced by UL40-derived peptides from intraocular HCMV compared to those identified only in peripheral blood. HCMV present in intraocular fluids were limited to those carrying a UL40 peptide sequence corresponding to the leader peptide sequence of the host's HLA class I, while UL40-derived peptides from HCMV found only in the peripheral blood were disparate from any HLA class I allotype. Overall, our analyses of CMV-retinitis inferred that specific HCMV strains with UL40 signal sequences matching the host's HLA signal peptide sequences were those that crossed the blood-ocular barrier to enter the intraocular space. UL40 peptide repertoires were the same in the intraocular fluids of all ocular CMV diseases, regardless of host immune status, implying that virus type is likely to be a common determinant in ocular CMV disease development. We thus propose a mechanism for ocular CMV disease development, in which particular HCMV types in the blood exploit peripheral and central HLA-E-mediated tolerance mechanisms and, thus, escape the antivirus responses of both innate and adaptive immunity.

Corrigendum: Intraocular human cytomegaloviruses of ocular diseases are distinct from those of viremia and are capable of escaping from innate and adaptive immunity by exploiting HLA-E-mediated peripheral and central tolerance.

[This corrects the article DOI: 10.3389/fimmu.2022.1008220.].

Mucosal-associated invariant T cells have therapeutic potential against ocular autoimmunity.

Autoimmune uveitis is a sight-threatening disease induced by pathogenic T cells that recognize retinal antigens; it is observed in disorders including Vogt-Koyanagi-Harada disease (VKH). The roles of specific T cell subsets and their therapeutic potential against autoimmune uveitis are not fully understood. Here we conducted multi-parametric single-cell protein quantification which shows that the frequency of CD161highTRAV1-2+ mucosal-associated invariant T (MAIT) cells that recognize vitamin B2 metabolite-based antigens is decreased in relapsing VKH patients compared to individuals without active ocular inflammation. An experimental autoimmune uveitis (EAU) mouse model revealed that genetic depletion of MAIT cells reduced the expression of interleukin (Il) 22 and exacerbated retinal pathology. Reduced IL-22 levels were commonly observed in patients with relapsing VKH compared to individuals without active ocular inflammation. Both mouse and human MAIT cells produced IL-22 upon stimulation with their antigenic metabolite in vitro. An intravitreal administration of the antigenic metabolite into EAU mice induced retinal MAIT cell expansion and enhanced the expressions of Il22, as well as its downstream genes related to anti-inflammatory and neuroprotective effects, leading to an improvement in both retinal pathology and visual function. Taken together, we demonstrate that a metabolite-driven approach targeting MAIT cells has therapeutic potential against autoimmune uveitis.

Relationship among total tear IgE, specific serum IgE, and total serum IgE levels in patients with pollen-induced allergic conjunctivitis.

BACKGROUND: Recently, the number of patients with pollinosis, particularly Japanese cedar pollinosis, has markedly increased. We previously reported about local allergic conjunctivitis, which is a phenotype of allergic conjunctivitis (AC). AC cases are often sensitized by various antigens. This study aimed to investigate the relationship among total tear IgE (t-tIgE), specific serum IgE (s-sIgE), and total serum IgE (t-sIgE) levels in patients with pollen-induced AC. METHODS: In 2019, 1372 patients were clinically diagnosed with AC at the Yamana Eye Clinic using t-tIgE, t-sIgE, and s-sIgE tests against 39 allergens. Among the pollen-induced AC patients who underwent allergen testing, 99 tested positives for s-sIgE against pollen. The subjects comprised 33 (33.3%) male and 66 (66.7%) female individuals aged 9-86 years. RESULTS: The t-tIgE test was positive in 68 (68.7%) patients and negative in 31 (31.3%) patients. In the t-sIgE test, 45 (45.5%) patients had t-sIgE levels above the reference value of 170 IU/mL. The higher the total score of the positive class value of each pollen-specific IgE (pollen-sIgE) antibody, the higher the positive rate of t-tIgE (p < 0.001). Of 32 patients in whom food-specific IgE (food-sIgE) was detected, 81.3% of the pollen-sIgE-positive and food-sIgE-positive cases were also positive for t-sIgE and t-tIgE. However, significant difference was not found between the total score of food-sIgE of the t-tIgE positive group and negative group. CONCLUSIONS: Pollen-induced AC is caused by pollen sensitization of the conjunctiva. Food-induced AC might be induced by the different pathological mechanism involved in pollen-induced AC.

A Case of Diabetic Macular Edema with Improvement in Severity of Diabetic Retinopathy following Frequent Anti-Vascular Endothelial Growth Factor Treatment.

Background: Intravitreal anti-vascular endothelial growth factor (VEGF) drug injections are the gold standard for the treatment of diabetic macular edema (DME). We report a case of DME in which frequent anti-VEGF treatment resulted in improvement of diabetic retinopathy. Case: A 73-year old woman with DME who had previously undergone bilateral posterior subtenon injections of triamcinolone acetonide and vitrectomy OD presented at Kyushu University Hospital. Best corrected visual acuity was 0.1 OD and 0.15 OS. The central macular thickness was 1570 µm OD and 578 µm OS. We performed focal macular laser photocoagulation OU but the DME was not resolved. Subsequent intravitreal anti-VEGF drug injections(approximately 20 times/2 years)resulted in an improvement of the best corrected visual acuity (0.3 OD, 0.6 OS) and CMT (1570 µm OD, 578 µm OS). There was an improvement of 2 steps in the Diabetic Retinopathy Severity Scale (DRSS) score OU. Conclusion: Frequent anti-VEGF treatment can improve the severity of diabetic retinopathy.