A look at autoimmunity and inflammation in the eye

Genetic variations in autoimmune genes and VKH disease

PURPOSE

Vogt-Koyanagi-Harada (VKH) disease is a rare autoimmune disease. The autoimmune response in VKH disease is against the melanin-producing cells; therefore, in affected individuals melanocyte-containing organs manifest disease symptoms including eyes, ears, skin and nervous system. VKH is a multifactorial disease, and the precise cause of the VKH disease is unknown. Studies have suggested that both environmental and genetic factors are responsible for the VKH disease. In this review, the authors have collected all the available literature on the genetics of VKH to their knowledge and discussed the role of genetic variants in causing VKH disease.

METHODS

An extensive literature search was performed in order to review all the published studies regarding VKH clinical phenotyping and genetic variants in VKH disease. Medline, PubMed, Cochrane library, and Scopus was searched using combination of keywords.

RESULTS

It was found that variants in HLA genes, IL-12b, TNFSF4, and miR-20-5p genes are significantly associated with VKH; however, variants in genes ATG10, TNIP1 and CLEC16A did not achieve significant genome-wide association threshold. Moreover, polymorphisms in TNIP1 and CLEC16A play a protective role against VKH.

CONCLUSION

The authors conclude that increased sample size and a more homogeneous VKH patient population may reveal a significant association of variants in ATG10, TNIP1 and CLEC16A genes with VKH disease.

Tofacitinib inhibits the development of experimental autoimmune uveitis and reduces the proportions of Th1 but not of Th17 cells

Purpose

Tofacitinib is a pan-Janus kinase (JAK) inhibitor that suppresses cytokine signaling and in turn, the cells that participate in inflammatory immunopathogenic processes. We examined the capacity of tofacitinib to inhibit the induction of experimental autoimmune uveitis (EAU) and related immune responses.

Methods

EAU was induced in B10.A mice with immunization with bovine interphotoreceptor retinoid-binding protein (IRBP), emulsified in complete Freund's adjuvant (CFA), and a simultaneous injection of pertussis toxin. Tofacitinib, 25 mg/kg, was administered daily, and the vehicle was used for control. EAU development was assessed by histological analysis of the mouse eyes, and related immune responses were assessed by (i) the levels of interferon (IFN)-γ and interleukin (IL)-17, secreted by spleen cells cultured with IRBP; (ii) flow cytometric analysis of intracellular expression by spleen, or eye-infiltrating CD4 or CD8 cells of IFN-γ, IL-17, and their transcription factors, T-bet and RORγt. In addition, the inflammation-related cell markers CD44 and CD62L and Ki67, a proliferation marker, were tested. The proportions of T-regulatory cells expressing FoxP3 were determined by flow cytometric intracellular staining, while levels of antibody to IRBP were measured with enzyme-linked immunosorbent assay (ELISA).

Results

Treatment with tofacitinib significantly suppressed the development of EAU and reduced the levels of secreted IFN-γ, but not of IL-17. Further, treatment with tofacitinib reduced in the spleen and eye-infiltrating cells the intracellular expression of IFN-γ and its transcription factor T-bet. In contrast, treatment with tofacitinib had essentially no effect on the intracellular expression of IL-17 and its transcription factor, RORγt. The selective effect of tofacitinib treatment was particularly evident in the CD8 population. Treatment with tofacitinib also increased the population of CD44, but reduced the populations of cells producing CD62L and Ki67. Treatment with tofacitinib had no effect on the proportion of FoxP3 producing regulatory cells and on the antibody production to IRBP.

Conclusions

Treatment with tofacitinib inhibited the development of EAU, reduced the production of IFN-γ, but had essentially no effect on the production of IL-17.

CD8+ T cells: The past and future of immune regulation

Regulation of the adaptive immune response is critical for health. Regulatory activity can be found in multiple components of the immune system, however, the focus on particular components of the immune regulatory network has left many aspects of this critical immune component understudied. Here we review the evidence for activities of CD8+ T cells in immune homeostasis and regulation of autoimmune reactivity. The heterogeneous nature of identified CD8+ cell types are examined, and common phenotypes associated with functional activities are defined. The varying types of antigen signal crucial for CD8+ T cell regulatory activity are identified and the implications of these activation pathways for control of adaptive responses is considered. Finally, the promising capacity for transgenic antigen receptor directed cytotoxicity as a mechanism for modulation of autoimmunity is detailed.

Treatment With FoxP3+ Antigen-Experienced T Regulatory Cells Arrests Progressive Retinal Damage in a Spontaneous Model of Uveitis

We specify the clinical features of a spontaneous experimental autoimmune uveitis (EAU) model, in which foreign hen-egg lysozyme (HEL) is expressed in the retina, controlled by the promoter for interphotoreceptor retinol binding protein (IRBP). We previously reported 100% P21 (post-partum day) IRBP:HEL single transgenic (sTg) mice, when crossed to transgenic T cell receptor mice (3A9) generating the double transgenic (dTg) genotype, develop EAU despite profound lymphopenia (thymic HEL-specific T cell deletion). In this work, we characterized the immune component of this model and found conventional dTg CD4+ T cells were less anergic than those from 3A9 controls. Furthermore, prior in vitro HEL-activation of 3A9 anergic T cells (T_an) rendered them uveitogenic upon adoptive transfer (Tx) to sTg mice, while antigen-experienced (AgX, dTg), but not naïve (3A9) T cells halted disease in P21 dTg mice. Flow cytometric analysis of the AgX cells elucidated the underlying pathology: FoxP3+CD25^hiCD4+ T regulatory cells (T_reg) comprised ∼18%, while FR4+CD73+FoxP3-CD25^lo/–CD4+ T_an comprised ∼1.2% of total cells. Further T_reg-enrichment (∼80%) of the AgX population indicated FoxP3+CD25^hiCD4+ T_reg played a key role in EAU-suppression while FoxP3-CD25^lo/–CD4+ T cells did not. Here we present the novel concept of dual immunological tolerance where spontaneous EAU is due to escape from anergy with consequent failure of T_reg induction and subsequent imbalance in the [T_reg:T_effector] cell ratio. The reduced numbers of T_an, normally sustaining T_reg to prevent autoimmunity, are the trigger for disease, while immune homeostasis can be restored by supplementation with AgX, but not naïve, antigen-specific T_reg.

MicroRNAs and Autoimmune-Mediated Eye Diseases

MicroRNAs (miRNAs) are evolutionarily conserved short non-coding RNAs that act at post-transcriptional regulation of gene expression by destroying target messenger RNA or inhibiting its translation. Recently, miRNAs have been identified as important regulators in autoimmunity. Aberrant expression and function of miRNAs can lead to dysfunction of immune system and mediate autoimmune disorders. Here, we summarize the roles of miRNAs that have been implicated in three representative ocular autoimmune disorders, including autoimmune uveitis, Grave's ophthalmopathy, and Sjögren's syndrome dry eye, and discuss the potential of miRNAs as biomarkers and therapeutic targets for the diagnosis and treatment of these diseases.

A cell-permeable peptide inhibitor of p55PIK signaling alleviates ocular inflammation in mouse models of uveitis

PURPOSE

Previously we developed TAT-N24 as a synthetic cell-permeable peptide inhibitor of p55PIK signaling and demonstrated its anti-inflammatory effects. This study aimed to evaluate the potential of TAT-N24 as a new agent for the treatment of ocular inflammatory diseases.

METHODS

The endotoxin-induced uveitis (EIU) model was established by intravitreal injection of lipopolysaccharide (LPS) in BALB/c mice and experimental autoimmune uveitis (EAU) model was established by subcutaneous injection of a peptide spanning amino acid residues 161-180 of interphotoreceptor retinoid binding protein (IRBP161-180) with complete Freund's adjuvant (CFA) in B10.RIII mice. TAT-N24 was topically administered in EIU model and intraperitoneally administered in EAU model. The severity levels of uveitis were assessed by clinical and histopathological scores. The mRNA levels of inflammatory cytokines in iris-ciliary body (ICB) and retina were analyzed by reverse transcription quantitative polymerase chain reaction (RT-qPCR). The protein levels of inflammatory factors were determined by ELISA or Western blotting.

RESULTS

The results showed that TAT-N24 alleviated clinical signs, decreased inflammatory cell infiltration and the expression of inflammatory cytokines in both EIU and EAU models. Furthermore, protein levels of tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in aqueous humor and mRNA and protein levels of NF-κB p65 in the ICB significantly decreased in EIU model. In EAU model, TAT-N24 application induced a significant decrease of IFN-gamma (IFN-γ) and interleukin-17 (IL-17) in the retina, which were secreted by Th1 and Th17 cells, respectively.

CONCLUSION

In conclusion, TAT-N24 suppressed intraocular inflammation in both EIU and EAU models, and the anti-inflammatory effects were mediated by suppressing the expression of inflammatory cytokines by PI3K/NF-κB signaling pathway. TAT-N24 could be potential candidate for the treatment of ocular inflammatory diseases.

Use of Adrenocorticotropic Hormone in Ophthalmology

The ability of the adrenocorticotropic hormone (ACTH) to induce steroidogenesis and upregulate anti-inflammatory processes has long been known. More recently, however, extrasteroidal mechanisms, through which ACTH exerts anti-inflammatory processes, have been described. This has renewed hope that ACTH can combat inflammatory conditions even when resistant to steroids. This review article summarizes the literature on the use of ACTH in ocular disease. Unfortunately, much of the data regarding the clinical utility of ACTH are outdated, with many studies published in the 1950s and 1960s. Many of these older studies are inconsistent or incomplete with their reporting, making it difficult to ascertain the meaning of the outcomes. Despite the limitations, 2 important trends are evident. First, when used to treat an inflammatory disease, ACTH can be effective at decreasing or eliminating ocular inflammation, even in a refractory disease resistant to multiple treatment modalities. Second, adverse effects of ACTH are rare and are most likely to be reported with relatively high doses of ACTH therapy. Taken as a whole, these studies offer initial promising data that ACTH may be a safe and effective alternative in refractory ocular inflammatory disease. However, they highlight an important lack of prospective data to more rigorously understand the true safety and efficacy of this therapy.

Pathogenesis of ocular tuberculosis: New observations and future directions

Ocular tuberculosis (OTB) encompasses all forms of intra- and extra-ocular inflammation associated with Mycobacterium tuberculosis (Mtb) infection. However, the organism is rarely found in ocular fluid samples of diseased eyes, rendering the pathomechanisms of the disease unclear. This confounds clinical decision-making in diagnosis and treatment of OTB. Here, we critically review existing human and animal data related to ocular inflammation and TB pathogenesis to unravel likely pathomechanisms of OTB. Broadly there appear to be two fundamental mechanisms that may underlie the development of TB-associated ocular inflammation: a. inflammatory response to live/replicating Mtb in the eye, and b. immune mediated ocular inflammation induced by non-viable Mtb or its components in the eye. This distinction is significant as in direct Mtb-driven mechanisms, diagnosis and treatment would be aimed at detection of Mtb-infection and its elimination; while indirect mechanisms would primarily require anti-inflammatory therapy with adjunctive anti-TB therapy. Further, we discuss how that most clinical phenotypes of OTB likely represent a combination of both mechanisms, with one being predominant than the other.

The Role of Gut Microbiome in Autoimmune Uveitis

The gut microbiome has important physiological functions and plays an indispensable role in the human body. Currently, there are an increasing number of studies revealing the close correlation between dysbiosis of the gut microbiome and a variety of autoimmune diseases, including autoimmune uveitis. This brief review summarizes recent literature regarding the relationship between dysbiosis and the occurrence and development of autoimmune uveitis. Dysbiosis participates in the pathogenesis of autoimmune uveitis largely by 4 mechanisms: antigenic mimicry, disturbance of intestinal immune homeostasis, destruction of the intestinal barrier, and reduction of beneficial anti-inflammatory metabolites. Further elucidation of these mechanisms will facilitate the treatment of the gut-microbiome-relevant autoimmune diseases by potential therapeutic strategies, such as antibiotics, probiotics, diet modifications, and fecal microbial transplantation.

The Cytokine IL-17A Limits Th17 Pathogenicity via a Negative Feedback Loop Driven by Autocrine Induction of IL-24

Dysregulated Th17 cell responses underlie multiple inflammatory and autoimmune diseases, including autoimmune uveitis and its animal model, EAU. However, clinical trials targeting IL-17A in uveitis were not successful. Here, we report that Th17 cells were regulated by their own signature cytokine, IL-17A. Loss of IL-17A in autopathogenic Th17 cells did not reduce their pathogenicity and instead elevated their expression of the Th17 cytokines GM-CSF and IL-17F. Mechanistic in vitro studies revealed a Th17 cell-intrinsic autocrine loop triggered by binding of IL-17A to its receptor, leading to activation of the transcription factor NF-κB and induction of IL-24, which repressed the Th17 cytokine program. In vivo, IL-24 treatment ameliorated Th17-induced EAU, whereas silencing of IL-24 in Th17 cells enhanced disease. This regulatory pathway also operated in human Th17 cells. Thus, IL-17A limits pathogenicity of Th17 cells by inducing IL-24. These findings may explain the disappointing therapeutic effect of targeting IL-17A in uveitis.

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IL-17A deficiency does not reduce the pathogenicity of Th17 cells in uveitis

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IL-17A binds to its own receptor on Th17 cells, activating NF-κB

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NF-κB induces IL-24 production, repressing the Th17 cytokine program through SOCS1/3

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Silencing or depleting IL-24 in Th17 cells exacerbates neuroinflammation

Hypomethylation of Notch1 DNA is associated with the occurrence of uveitis

Uveitis is a serious intra-ocular inflammatory disease that can lead to visual impairment even blindness worldwide. Notch signaling can regulate the differentiation of naive CD4⁺ T cells, influencing the development of uveitis. DNA methylation is closely related to the autoimmune diseases. In this study, we measured the Notch1 DNA methylation level, determined the Notch1 and related DNA methylases mRNA expression and evaluated the ratio of T helper type 17 regulatory T cell (Th17/T_reg ) in peripheral blood mononuclear cells (PBMCs) from uveitis patients and normal control subjects; we also tested the levels of relevant inflammatory cytokines in serum from the participants. Results indicated that compared with those in normal control individuals, the expression of ten-eleven translocation 2 (TET2) and Notch1 mRNA is elevated in uveitis patients, whereas the methylation level in Notch1 DNA promotor region [-842 ~ -646 base pairs (bp)] is down-regulated, and is unrelated to anatomical location. Moreover, the Th17/T_reg ratio is up-regulated in PBMCs from uveitis patients, accompanied by the elevated levels of proinflammatory cytokines [e.g. interleukin (IL)-2, IL-6, IL-17 and interferon (IFN)-γ] in serum from uveitis patients. These findings suggest that the over-expression of TET2 DNA demethylase may lead to hypomethylation of Notch1, activate the Notch1 signaling, induce naive CD4⁺ T cells to differentiate theTh17 subset and thus disturb the balance of the Th17/T_reg ratio in uveitis patients. Overall, hypomethylation of Notch1 DNA is closely associated with the occurrence of uveitis. Our study preliminarily reveals the underlying mechanism for the occurrence of uveitis related to the hypomethylation of Notch1 DNA, providing a novel therapeutic strategy against uveitis in clinical practice.

Intravitreal enzyme replacement preserves retinal structure and function in canine CLN2 neuronal ceroid lipofuscinosis

CLN2 neuronal ceroid lipofuscinosis is a hereditary neurodegenerative disorder characterized by progressive vision loss, neurological decline, and seizures. CLN2 disease results from mutations in TPP1 that encodes the lysosomal enzyme tripeptidyl peptidase-1 (TPP1). Children with CLN2 neuronal ceroid lipofuscinosis experience ocular disease, characterized by progressive retinal degeneration associated with impaired retinal function and gradual vision loss culminating in total blindness. A similar progressive loss of retinal function is also observed in a dog CLN2 model with a TPP1 null mutation. A study was conducted to evaluate the efficacy of periodic intravitreal injections of recombinant human (rh) TPP1 in inhibiting retinal degeneration and preserving retinal function in the canine model. TPP1 null dogs received periodic intravitreal injections of rhTPP1 in one eye and vehicle in the other eye beginning at approximately 12 weeks of age. Ophthalmic exams, in vivo ocular imaging, and electroretinography (ERG) were repeated regularly to monitor retinal structure and function. Retinal histology was evaluated in eyes collected from these dogs when they were euthanized at end-stage neurological disease (43-46 weeks of age). Intravitreal rhTPP1 dosing prevented disease-related declines in ERG amplitudes in the TPP1-treated eyes. At end-stage neurologic disease, TPP1-treated eyes retained normal morphology while the contralateral vehicle-treated eyes exhibited loss of inner retinal neurons and photoreceptor disorganization typical of CLN2 disease. The treatment also prevented the development of disease-related focal retinal detachments observed in the control eyes. Uveitis occurred secondary to the administration of the rhTPP1 but did not hinder the therapeutic benefits. These findings demonstrate that periodic intravitreal injection of rhTPP1 preserves retinal structure and function in canine CLN2 disease.

Matairesinol ameliorates experimental autoimmune uveitis by suppression of IRBP-specific Th17 cells

We investigated the effects of matairesinol (MAT) in the experimental autoimmune uveitis (EAU), a classical animal model of uveitis. We found that treatment with MAT could alleviate intraocular inflammation of EAU. Notably, Th17 cells in eyes of EAU mice could be predominantly restrained by MAT. Furthermore, MAT could inhibit Th17 differentiation in vitro. In addition, MAT inhibited the signaling of MAPK and ROR-γt, a pivotal transcription factor for Th17 cell differentiation in vitro and in vivo. Taken together, these results suggested that MAT had immune-suppressive effects on autoimmune inflammation through Th17 cells.

The use of biologic agents in the management of uveitis

The uveitides are a heterogenous group of ocular inflammatory disorders that account for the third highest cause of blindness worldwide, responsible for 5-10% of visual impairment globally. Up to 35% of patients with uveitis can suffer significant vision loss. To prevent irreversible structural damage and blindness, it is important that the diagnosis and commencement of appropriate therapy occurs promptly. Management includes topical and systemic corticosteroid therapy and conventional immunomodulatory agents, including methotrexate, azathioprine, mycophenolate mofetil and cyclosporin. Significant progress has been made in the past decade in our understanding of the immunopathological pathways that drive intraocular inflammation, allowing the development of targeted therapy with biologic agents. These include TNF-α inhibitors, such as infliximab, adalimumab and etanercept; interleukin blockers, such as tocilizumab and daclizumab; and other targeted therapies, such as rituximab and abatacept. The efficacy of these agents has been studied in cases of severe uveitis that are refractory to conventional immunomodulatory agents and provide exciting results that have revolutionised uveitis management. Though the biologic era has provided a large armamentarium to treat uveitis, ongoing challenges and cases of recalcitrant uveitis remain, posing a challenge to internal medicine physicians. This comprehensive review aims to construct an updated summary on the existing evidence pertaining to the use of biologic agents in the treatment of uveitis. Methods include a systematic search for studies between 2000 and 2018 using PubMed, EMBASE, Ovid MEDLINE and Cochrane libraries.

Altered gut microbiome composition in patients with Vogt-Koyanagi-Harada disease

BACKGROUND

Vogt-Koyanagi-Harada (VKH) disease is a multisystemic autoimmune disorder characterized by granulomatous panuveitis. Gut microbiome has been considered to play a role in the pathogenesis of this disease but whether the alternation of gut microbiome was involved is unclear. This study was set up to identify abnormalities of gut microbiome composition in VKH disease.

RESULTS

Depleted butyrate-producing bacteria, lactate-producing bacteria and methanogens as well as enriched Gram-negative bacteria were identified in the active VKH patients, as well as in VKH patients of Mix enterotype and Bacteroides enterotype. Changes of gut microbiome in the VKH patients were partially restored after an immunosuppressive treatment. The disease susceptibility genotype HLA-DRA was associated with Bacteroides sp.2.1.33B, Paraprevotella clara, Alistipes finegoldii and Eubacterium eligens. A microbial marker profile including 40 disease-associated species was established to differentiate patients from controls. Another microbial marker profile including 37 species was found to be associated with the response to treatment. An animal experiment showed that transfer of gut microbiome from VKH patients could significantly exacerbate disease activity clinically and pathologically in the recipient mice.

CONCLUSION

Our results revealed a distinct gut microbiome signature in VKH patients and showed an exacerbating effect of this gut microbiome on experimental autoimmune uveitis (EAU). We also developed two microbial marker profiles in differentiating VKH patients from healthy controls as well as predicting the effectiveness of treatment.

Quantifying the Role of Stochasticity in the Development of Autoimmune Disease

In this paper, we propose and analyse a mathematical model for the onset and development of autoimmune disease, with particular attention to stochastic effects in the dynamics. Stability analysis yields parameter regions associated with normal cell homeostasis, or sustained periodic oscillations. Variance of these oscillations and the effects of stochastic amplification are also explored. Theoretical results are complemented by experiments, in which experimental autoimmune uveoretinitis (EAU) was induced in B10.RIII and C57BL/6 mice. For both cases, we discuss peculiarities of disease development, the levels of variation in T cell populations in a population of genetically identical organisms, as well as a comparison with model outputs.

Intravitreal thalidomide ameliorates inflammation in a model of experimental uveitis induced by BCG

Uveitis encompasses a heterogeneous and complex group of conditions characterized by intraocular inflammation, frequently affecting young individuals and representing an important cause of irreversible blindness worldwide. Animal models have been critical to understand etiology and pathogenesis of uveitis, being also employed to assess new therapeutic strategies, preceding human studies. However, there is still a need of developing and studying different models, due to the difficulties in recapitulating all forms of human uveitis effectively. Although corticosteroids are usually the first-line therapy for non-infectious uveitis, their long-term use is limited by potentially serious side effects in all possible delivery routes. Thus, thalidomide, a drug with anti-inflammatory and antiangiogenic properties, was investigated in a novel experimental model of uveitis, induced by Mycobacterium bovis Calmette-Guérin Bacillus (BCG), in rabbits. The experimental protocol consisted of two subcutaneous injections of BCG, followed by two intravitreal injections of the same antigen, inducing panuveitis. Animals were treated with a single intravitreal injection of thalidomide suspension or PBS. Clinical manifestations of uveitis improved after intravitreal thalidomide, involving both anterior and posterior segments. Protein content, N-acetyl-b-glucosaminidase (NAG) and myeloperoxidase (MPO) activities were elevated in ocular tissues after disease induction, further decreasing post-treatment with intravitreal thalidomide. This therapeutic response was also confirmed on ocular electrophysiology, as well as histopathology. This experimental model induced panuveitis in rabbits using a low-cost mycobacterial antigen, with intraocular inflammation subsequently improving after treatment. Intravitreal thalidomide may be a potential alternative to treat intraocular inflammation in corticosteroid-sparing therapies.

Signaling mechanisms of growth hormone-releasing hormone receptor in LPS-induced acute ocular inflammation

Ocular inflammation is a major cause of visual impairment attributed to dysregulation of the immune system. Previously, we have shown that the receptor for growth-hormone-releasing hormone (GHRH-R) affects multiple inflammatory processes. To clarify the pathological roles of GHRH-R in acute ocular inflammation, we investigated the inflammatory cascades mediated by this receptor. In human ciliary epithelial cells, the NF-κB subunit p65 was phosphorylated in response to stimulation with lipopolysaccharide (LPS), resulting in transcriptional up-regulation of GHRH-R. Bioinformatics analysis and coimmunoprecipitation showed that GHRH-R had a direct interaction with JAK2. JAK2, but not JAK1, JAK3, and TYK2, was elevated in ciliary body and iris after treatment with LPS in a rat model of endotoxin-induced uveitis. This elevation augmented the phosphorylation of STAT3 and production of proinflammatory factors, including IL-6, IL-17A, COX2, and iNOS. In explants of iris and ciliary body, the GHRH-R antagonist, MIA-602, suppressed phosphorylation of STAT3 and attenuated expression of downstream proinflammatory factors after LPS treatment. A similar suppression of STAT3 phosphorylation was observed in human ciliary epithelial cells. In vivo studies showed that blocking of the GHRH-R/JAK2/STAT3 axis with the JAK inhibitor Ruxolitinib alleviated partially the LPS-induced acute ocular inflammation by reducing inflammatory cells and protein leakage in the aqueous humor and by repressing expression of STAT3 target genes in rat ciliary body and iris and in human ciliary epithelial cells. Our findings indicate a functional role of the GHRH-R/JAK2/STAT3-signaling axis in acute anterior uveitis and suggest a therapeutic strategy based on treatment with antagonists targeting this signaling pathway.

A novel role for lipoxin A4 in driving a lymph node-eye axis that controls autoimmunity to the neuroretina

The eicosanoid lipoxin A4 (LXA4) has emerging roles in lymphocyte-driven diseases. We identified reduced LXA4 levels in posterior segment uveitis patients and investigated the role of LXA4 in the pathogenesis of experimental autoimmune uveitis (EAU). Immunization for EAU with a retinal self-antigen caused selective downregulation of LXA4 in lymph nodes draining the site of immunization, while at the same time amplifying LXA4 in the inflamed target tissue. T cell effector function, migration and glycolytic responses were amplified in LXA4-deficient mice, which correlated with more severe pathology, whereas LXA4 treatment attenuated disease. In vivo deletion or supplementation of LXA4 identified modulation of CC-chemokine receptor 7 (CCR7) and sphingosine 1- phosphate receptor-1 (S1PR1) expression and glucose metabolism in CD4+ T cells as potential mechanisms for LXA4 regulation of T cell effector function and trafficking. Our results demonstrate the intrinsic lymph node LXA4 pathway as a significant checkpoint in the development and severity of adaptive immunity.

Effect of berberine on spleen transcriptome and gut microbiota composition in experimental autoimmune uveitis

BACKGROUND

Berberine (BBR) was reported to have immunoregulatory and anti-inflammatory properties. In this study, we investigated whether BBR could exert its effects on the development of experimental autoimmune uveitis (EAU), and if so, what was the underlying mechanism?

METHODS

EAU was induced in B10R.III mice by immunization with IRBP 161-180, followed by 100 mg/kg/d BBR intragastric administration. Disease severity was assessed by evaluation of clinical and histopathological scores. Blood-retinal barrier (BRB) breakdown was tested by Evans blue. Effector and regulatory T (Treg) cell balance was evaluated by quantitative real-time PCR and flow cytometry. Spleen transcriptome was characterized by RNA sequencing (RNA-seq). Gut microbiota composition was investigated by 16S rRNA analysis.

RESULTS

BBR treatment significantly blocked EAU as shown by the decrease of the clinical and histological scores, as well as the inhibition of BRB breakdown. The frequency of splenic Th1 and Th17 cells was decreased, whereas Treg cells were increased in the BBR-treated group. RNA-seq of the spleen revealed 476 differentially expressed genes (DEGs) between the EAU and EAU-BBR group. GO functional classification, as well as KEGG analysis demonstrated that BBR treatment markedly influences genes belonging to chromatin remodeling and immune-related pathways. Intervention with BBR modified the gut microbiome in EAU mice, increasing the number of bacteria with immunomodulatory capacity. Depletion of gut microbiota affected the efficacy of BBR on EAU. Moreover, the altered bacterial strains showed a significant correlation with the expression of histones.

CONCLUSIONS

BBR inhibited IRBP induced EAU, which was associated with a significant change in the spleen transcriptome and intestinal microbial composition.

Features of ectopic lymphoid-like structures in human uveitis

Persistent non-infectious uveitis has a significant morbidity, but the extent to which this is accompanied by inflammation driven remodelling of the tissue is unclear. To address this question, we studied a series of samples selected from two ocular tissue repositories and identified 15 samples with focal infiltration. Eleven of fifteen contained lymphocytes, both B cells (CD20 positive) and T cells (CD3 positive). In 20% of the samples there was evidence of ectopic lymphoid like structures with focal aggregations of B cells and T cells, segregated into anatomically different adjacent zones. To investigate inflammation in the tissue, an analysis of 520 immune relevant transcripts was carried out and 24 genes were differentially upregulated, compared with control tissue. Two of these (CD14 and fibronectin) were increased in ocular inflammation compared to control immune tissue (tonsil). We demonstrate that in a significant minority of patients, chronic persistent uveitis leads to dysregulation of ocular immune surveillance, characterized by the development of areas of local ectopic lymphoid like structures, which may be a target for therapeutic intervention directed at antibody producing cells.

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Active inflammation continues in cases of persistent uveitis.

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Some patients develop ectopic lymphoid-like structure.

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In these cases targeting B cells may be beneficial.

Comprehensive analysis of a mouse model of spontaneous uveoretinitis using single-cell RNA sequencing

Autoimmune uveoretinitis is a significant cause of visual loss, and mouse models offer unique opportunities to study its disease mechanisms. Aire ^-/- mice fail to express self-antigens in the thymus, exhibit reduced central tolerance, and develop a spontaneous, chronic, and progressive uveoretinitis. Using single-cell RNA sequencing (scRNA-seq), we characterized wild-type and Aire ^-/- retinas to define, in a comprehensive and unbiased manner, the cell populations and gene expression patterns associated with disease. Based on scRNA-seq, immunostaining, and in situ hybridization, we infer that 1) the dominant effector response in Aire ^-/- retinas is Th1-driven, 2) a subset of monocytes convert to either a macrophage/microglia state or a dendritic cell state, 3) the development of tertiary lymphoid structures constitutes part of the Aire ^-/- retinal phenotype, 4) all major resident retinal cell types respond to interferon gamma (IFNG) by changing their patterns of gene expression, and 5) Muller glia up-regulate specific genes in response to IFN gamma and may act as antigen-presenting cells.

Juvenile idiopathic arthritis-associated uveitis

Juvenile idiopathic arthritis (JIA) is the commonest rheumatic disease in children and JIA-associated uveitis its most frequent extra-articular manifestation. The uveitis is potentially sight-threatening and so carries a considerable risk of morbidity. The commonest form of uveitis seen in JIA is chronic anterior uveitis which is almost always asymptomatic in the initial stages. Therefore, screening for JIA-associated uveitis in at-risk patients is essential. The aim of early detection and treatment is to minimise intra-ocular inflammation and avoid complications leading to visual loss, resulting from both disease activity and medications. There is increasing evidence for the early introduction of systemic immunosuppressive therapies in order to reduce topical and systemic glucocorticoid use. Two randomised controlled trials of adalimumab in JIA-associated uveitis provide convincing evidence for the use of this biologic in patients who fail to respond adequately to methotrexate. Tocilizumab and baricitinib are being investigated as alternatives to anti-tumour necrosis factor drugs.

Adverse effects of immune-checkpoint inhibitors: epidemiology, management and surveillance

Immune-checkpoint inhibitors (ICIs), including anti-cytotoxic T lymphocyte antigen 4 (CTLA-4), anti-programmed cell death 1 (PD-1) and anti-programmed cell death 1 ligand 1 (PD-L1) antibodies, are arguably the most important development in cancer therapy over the past decade. The indications for these agents continue to expand across malignancies and disease settings, thus reshaping many of the previous standard-of-care approaches and bringing new hope to patients. One of the costs of these advances is the emergence of a new spectrum of immune-related adverse events (irAEs), which are often distinctly different from the classical chemotherapy-related toxicities. Owing to the growing use of ICIs in oncology, clinicians will increasingly be confronted with common but also rare irAEs; hence, awareness needs to be raised regarding the clinical presentation, diagnosis and management of these toxicities. In this Review, we provide an overview of the various types of irAEs that have emerged to date. We discuss the epidemiology of these events and their kinetics, risk factors, subtypes and pathophysiology, as well as new insights regarding screening and surveillance strategies. We also highlight the most important aspects of the management of irAEs.

Therapeutic potential of aryl hydrocarbon receptor in autoimmunity

Aryl hydrocarbon receptor (AhR), a type of transcriptional factor, is widely expressed in immune cells. The activation of AhR signaling pathway depends on its ligands, which exist in environment and can also be produced by metabolism. Normal expressions of AhR and AhR-mediated signaling may be essential for immune responses, and effects of AhR signaling on the development and function of innate and adaptive immune cells have also been revealed in previous studies. Recent studies also indicate that aberrant AhR signaling may be related to autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), autoimmune uveitis (AU), autoimmune diabetes, Behcet's disease (BD) and myasthenia gravis (MG). Moreover, administration of AhR ligands or drugs has been proven effective for improving pathological outcomes in some autoimmune diseases or models. In this review, we summarize the effects of AhR on several innate and adaptive immune cells associated with autoimmunity, and the mechanism on how AhR participates in autoimmune diseases. In addition, we also discuss therapeutic potential and application prospect of AhR in autoimmune diseases, so as to provide valuable information for exploring novel and effective approaches to autoimmune disease treatments.

Emerging drugs for the treatment of noninfectious uveitis

Introduction: Uveitis is a leading cause of visual impairment and a significant burden of blindness. Although corticosteroids and conventional immunosuppressive agents have been successfully used, these are non-specific, and their long-term use may induce significant adverse effects. Areas covered: This article discusses existing local and systemic applied treatments for ocular inflammation including corticosteroids, non-biologic, and biologic disease-modifying anti-rheumatic drugs (DMARD). Potential drugs being studied in clinical trials are introduced for both local and systemic use. Expert opinion: Treatment options for uveitis continue to expand. Still, more efforts and research are needed to better understand the mechanisms potentially leading to clinical trials.

Recent advances of exosomes in immune-mediated eye diseases

Exosomes, nanosized extracellular vesicles of 30-150 nm, are shed by almost all cell types. Bearing proteins, lipids, RNAs, and DNAs, exosomes have emerged as vital biological mediators in cell-to-cell communication, affecting a plethora of physiological and pathological processes. Particularly, mounting evidence indicates that immunologically active exosomes can regulate both innate and adaptive immune responses. Herein, we review recent advances in the research of exosomes in several immune-mediated eye diseases, including Sjögren's syndrome (SS) dry eye, corneal allograft rejection, autoimmune uveitis, and age-related macular degeneration (AMD). Additionally, we discuss the potential of exosomes as novel biomarkers and drug delivery vesicles for the diagnosis and treatment of eye diseases.

Safety Assessment of Nanomaterials to Eyes: An Important but Neglected Issue

The production and application of nanomaterials have grown tremendously during last few decades. The widespread exposure of nanoparticles to the public is provoking great concerns regarding their toxicity to the human body. However, in comparison with the extensive studies carried out to examine nanoparticle toxicity to the human body/organs, one especially vulnerable organ, the eye, is always neglected. Although it is a small part of the body, 90% of outside information is obtained via the ocular system. In addition, eyes usually directly interact with the surrounding environment, which may get severer damage from toxic nanoparticles compared to inner organs. Therefore, the study of assessing the potential nanoparticle toxicity to the eyes is of great importance. Here, the recent advance of some representative manufactured nanomaterials on ocular toxicity is summarized. First, a brief introduction of ocular anatomy and disorders related to particulate matter exposure is presented. Following, the factors that may influence toxicity of nanoparticles to the eye are emphasized. Next, the studies of representative manufactured nanoparticles on eye toxicity are summarized and classified. Finally, the limitations that are associated with current nanoparticle-eye toxicity research are proposed.

Interleukin 22 ameliorates neuropathology and protects from central nervous system autoimmunity

IL-22 has opposing effects in different tissues, from pro-inflammatory (skin, joints) to protective (liver, intestine) but little is known about its effects on neuroinflammation. We examined the effect of IL-22 on retinal tissue by using the model of experimental autoimmune uveitis (EAU) in IL-22-/- mice, as well as by intraocular injections of recombinant IL-22 or anti-IL-22 antibodies in wild type animals. During EAU, IL-22 was produced in the eye by CD4+ eye-infiltrating T cells. EAU-challenged IL-22-/- mice, as well as WT mice treated systemically or intraocularly with anti-IL-22 antibodies during the expression phase of disease, developed exacerbated retinal damage. Furthermore, IL-22-/- mice were more susceptible than WT controls to glutamate-induced neurotoxicity, whereas local IL-22 supplementation was protective, suggesting direct or indirect neuroprotective effects. Mechanistic studies revealed that retinal glial Müller cells express IL-22rα1 in vivo, and in vitro IL-22 enhanced their ability to suppress proliferation of effector T cells. Finally, IL-22 injected into the eye concurrently with IL-1, inhibited the (IL-1-induced) expression of multiple proinflammatory and proapoptotic genes in retinal tissue. These findings suggest that IL-22 can function locally within the retina to reduce inflammatory damage and provide neuroprotection by affecting multiple molecular and cellular pathways.

Mechanisms of AIDS-related cytomegalovirus retinitis

Human cytomegalovirus (HCMV) generates a significant clinical burden worldwide, particularly among the immune compromised. In approximately 30% of untreated HIV/AIDS patients without access or sufficient response to antiretroviral therapies, for example, HCMV causes a sight-threatening retinitis. To study the mechanisms of AIDS-related HCMV retinitis, our lab has for many years used a mouse model in which a mixture of mouse retroviruses induces murine AIDS after approximately 10 weeks, rendering otherwise resistant mice susceptible to opportunistic pathogens. This immunodeficiency combined with subretinal inoculation of murine cytomegalovirus yields a reproducible model of the human disease, facilitating the discovery of many clinically relevant virologic and immunologic mechanisms of retinal destruction which we summarize in this review.

Case Series and Literature Review of Ophthalmologic Disorders Seen in a Specialist Rheumatology Clinic in Lagos, Nigeria

Purpose: To highlight the pattern and treatment outcomes of ophthalmologic disorders referred to a private specialist rheumatology clinic. Methods: Retrospective review (January 2015-December 2016) of referrals from Eye Foundation Hospital, Lagos to Arthrimed Specialist Clinic, Lagos. Case records were retrieved and relevant information extracted. Ethical standards were observed. Results: Twenty-two referrals (35 eyes) were received out of 643 patients (3.4%) seen during the study period. The majority were female (63.6%) with mean age 48.9 ± 19.3 years and bilateral disease (59%). Diagnoses included uveitis (45.5%), optic neuritis (36.4%), non-specific autoimmune eye disease (9.1%), keratoconjunctivitis sicca (4.5%), and giant cell arteritis (4.5%). Treatment was with steroids and immunosuppressive agents. Fourteen patients improved (63.6%), five remained unchanged (22.7%), while three worsened (13.6%). Conclusions: Our patients were mostly fourth-decade females with bilateral disease. Uveitis was the commonest presentation, and two-thirds of the treated patients improved after treatment. Early specialist referral and co-management of severe autoimmune eye diseases are desirable.

Type I Interferon Therapy Limits CNS Autoimmunity by Inhibiting CXCR3-Mediated Trafficking of Pathogenic Effector T Cells

Type I interferons (IFNs) have therapeutic potential in CNS autoimmune diseases, such as uveitis, but the molecular mechanisms remain unclear. Using a T cell-transfer model of experimental autoimmune uveitis (EAU), we found that IFN-α/β treatment inhibited the migration of IFN-γ-producing pathogenic CD4+ T cells to effector sites. IFN-α/β upregulated the expression of the cognate ligands CXCL9, CXCL10, and CXCL11, causing ligand-mediated downregulation of CXCR3 expression and effector T cell retention in the spleen. Accordingly, type I IFN did not alter EAU progression in CXCR3-/- mice. In uveitis patients, disease exacerbations correlated with reduced serum IFN-α concentrations. IFN-α/β reduced CXCR3 expression and migration by human effector T cells, and these parameters were associated with the therapeutic efficacy of IFN-α in uveitis patients. Our findings provide insight into the molecular basis of type I IFN therapy for CNS autoimmune diseases and identify CXCR3 as a biomarker for effective type I IFN immunotherapy.

The Purinergic System as a Pharmacological Target for the Treatment of Immune-Mediated Inflammatory Diseases

Immune-mediated inflammatory diseases (IMIDs) encompass a wide range of seemingly unrelated conditions, such as multiple sclerosis, rheumatoid arthritis, psoriasis, inflammatory bowel diseases, asthma, chronic obstructive pulmonary disease, and systemic lupus erythematosus. Despite differing etiologies, these diseases share common inflammatory pathways, which lead to damage in primary target organs and frequently to a plethora of systemic effects as well. The purinergic signaling complex comprising extracellular nucleotides and nucleosides and their receptors, the P2 and P1 purinergic receptors, respectively, as well as catabolic enzymes and nucleoside transporters is a major regulatory system in the body. The purinergic signaling complex can regulate the development and course of IMIDs. Here we provide a comprehensive review on the role of purinergic signaling in controlling immunity, inflammation, and organ function in IMIDs. In addition, we discuss the possible therapeutic applications of drugs acting on purinergic pathways, which have been entering clinical development, to manage patients suffering from IMIDs.

Tissue-specific production of MicroRNA-155 inhibits melanocortin 5 receptor-dependent suppressor macrophages to promote experimental autoimmune uveitis

Tissue-specific immune regulation is an important component of the immune response relevant to many areas of immunology. The focus of this study is on tissue-specific mechanisms that contribute to autoimmune uveitis. Precise gene regulation is necessary for the proper expression of an inflammatory or regulatory response. This precision gene regulation can be accomplished by microRNA at the level of the mRNA transcript. miR-155, in particular, has a complicated role in the immune response with positive and negative inflammatory effects. In this work, we identify a decrease in miR-155 in suppressor macrophages and further examine how tissue-specific production of miR-155 impacts experimental autoimmune uveitis. Importantly, we show that eliminating miR-155 expression by the target tissue before initiation reduces disease severity, but elimination of miR-155 after the onset of inflammation does not alter the course of disease. Additionally, expression of miR-155 by the target tissue before initiation is necessary for the induction of regulatory immunity that protects from further autoimmune disease, but not after the onset of inflammation. In summary, we find a MC5r-dependent decrease in miR-155 in postexperimental autoimmune uveitis APC, miR-155 production by the target tissue is necessary for the initiation of autoimmune uveitis, and may have a role in establishing protective regulatory immunity.

Anti-TNF Drugs for Chronic Uveitis in Adults-A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: We aimed to assess efficacy and safety of anti-tumor necrosis factor (TNF) drugs for adult chronic non-infectious uveitis (NIU).

Methods: CENTRAL, MEDLINE, and EMBASE, were searched from inception to January 2019. Double-masked randomized placebo-controlled trials, assessing any anti-TNF vs. best medical intervention/standard of care in adults with chronic NIU were considered. The PRISMA and SAMPL guidelines were followed. The risk of bias was assessed using the Cochrane risk of bias tool. Overall quality of the evidence was assessed according to GRADE. PROSPERO registration: #CRD42016039068. The primary efficacy and safety outcomes were preservation of visual acuity (VA) and withdrawals due to adverse events, respectively. Meta-analysis of efficacy analysis was not performed due to significant clinical heterogeneity between studies' population and interventions.

Results: A total of 1,157 references were considered and 3 studies were included. The overall risk of bias was moderate. In active NIU, adalimumab group showed an increased likelihood of VA preservation (risk ratio (RR) 1.75, 95%CI 1.32 to 2.32, n = 217), whereas the etanercept group did not (RR 0.81, 95%CI 0.57 to 1.14, n = 20). In inactive NIU, adalimumab was associated with increased likelihood of VA preservation (RR 1.31, 95%CI 1.12 to 1.53, n = 226). The rate of adverse events did not differ between anti-TNF and control arms (RR 1.03, 95%CI 0.94 to 1.13, n = 410).

Conclusions: There is high quality evidence that adalimumab decreases the risk of worsening VA in active and inactive NIU and very low quality evidence that the risk of etanercept worsening VA in inactive NIU is not different from placebo. Moderate quality evidence suggests that anti-TNF agents are not different from placebo on the risk of study withdrawal.

Type I ROP16 regulates retinal inflammatory responses during ocular toxoplasmosis

Ocular toxoplasmosis (OT), mostly retinochorioditis, is a major feature of infection with the protozoan parasite Toxoplasma gondii. The pathophysiology of this infection is still largely elusive; especially mouse models are not yet well developed. In contrast, numerous in vitro studies showed the highly Toxoplasma strain dependent nature of the host-parasite interactions. Some distinct polymorphic virulence factors were characterized, notably the rhoptry protein ROP16. Here, we studied the strain-dependent pathophysiology in our OT mouse model. Besides of two wild type strains of the canonical I (RH, virulent) and II (PRU, avirulent) types, we used genetically engineered parasites, RHΔROP16 and PRU ROP16-I, expressing the type I allele of this virulence factor. We analyzed retinal integrity, parasite proliferation and retinal expression of cytokines. PRU parasites behaved much more virulently in the presence of a type I ROP16. In contrast, knockout of ROP16 in the RH strain led to a decrease of intraocular proliferation, but no difference in retinal pathology. Cytokine quantification in aqueous humor showed strong production of Th1 and inflammatory markers following infection with the two strains containing the ROP16-I allele. In strong contrast, immunofluorescence images showed that actual expression of most cytokines in retinal cells is rapidly suppressed by type I strain infection, with or without the involvement of its homologous ROP16 allele. This demonstrates the particular immune privileged situation of the retina, which is also revealed by the fact that parasite proliferation is nearly exclusively observed outside the retina. In summary, we further developed a promising OT mouse model and demonstrated the specific pathology in retinal tissues.

AS101 ameliorates experimental autoimmune uveitis by regulating Th1 and Th17 responses and inducing Treg cells

AS101 is an organotellurium compound with multifaceted immunoregulatory properties that is remarkable for its lack of toxicity. We tested the therapeutic effect of AS101 in experimental autoimmune uveitis (EAU), a model for human autoimmune uveitis. Unexpectedly, treatment with AS101 elicited Treg generation in vivo in otherwise unmanipulated mice. Mice immunized for EAU with the retinal antigen IRBP and treated with AS101 developed attenuated disease, as did AS101-treated recipients of retina-specific T cells activated in vitro. In both settings, eye-infiltrating effector T cells were decreased, whereas regulatory T (Treg) cells in the spleen were increased. Mechanistic studies in vitro revealed that AS101 restricted polarization of retina-specific T cells towards Th1 or Th17 lineage by repressing activation of their respective lineage-specific transcription factors and downstream signals. Retina-specific T cells polarized in vitro towards Th1 or Th17 in the presence of AS101 had impaired ability to induce EAU in naïve recipients. Finally, AS101 promoted differentiation of retina-specific T cells to Tregs in vitro independently of TGF-β. We conclude that AS101 modulates autoimmune T cells by inhibiting acquisition and expression of effector function and by promoting Treg generation, and suggest that AS101 could be useful as a therapeutic approach for autoimmune uveitis.

Microbiome and Autoimmune Uveitis

Commensal microbes affect all aspects of immune development and homeostasis in health and disease. Increasing evidence points to the notion that the gut commensals impact not only intestinal diseases but also diseases in tissues distant from the gut. Autoimmune or non-infectious uveitis is a sight-threatening intraocular inflammation that affects the neuroretina. It is strongly T cell driven, but the precise causative mechanisms are not fully understood. We and others observed that depletion of gut microbiota in animal models of uveitis attenuated disease. Using a spontaneous model of the disease, we questioned how retina-specific uveitogenic T cells are primed when their cognate antigens are sequestered within the immune privileged eye. The data suggested that gut commensals provide a signal directly through the retina-specific T cell receptor and cause these autoreactive T cells to trigger uveitis. This activation of retina-specific T cells in the gut appears to be independent of the endogenous retinal antigen. Rather, the findings point to the notion that gut microbiota may mimic retinal antigen(s), however, the actual mimic has not yet been identified. Microbiota may also serve as an “adjuvant” providing innate signals that amplify and direct the host immune response for development of uveitis. In contrast, spontaneous uveitis that develops in AIRE^−/− mice appears to be independent of gut microbiota. To date, available data on human microbiota in association with uveitis are very limited and causative relationships are difficult to establish. This review will summarize the current knowledge on the role of microbiome in uveitis and its underlying mechanisms, and discuss unresolved questions and issues in an attempt to explore the concept of gut-retina axis.

Green tea catechins alleviate autoimmune symptoms and visual impairment in a murine model for human chronic intraocular inflammation by inhibiting Th17-associated pro-inflammatory gene expression

Autoimmune uveitis is a sight-threatening disease mainly caused by dysregulation of immunity. We investigated the therapeutic effects of green tea extract (GTE) and its major component, epigallocatechin-3-gallate (EGCG), on a murine model of experimental autoimmune uveoretinitis (EAU). Oral administration of GTE, EGCG, dexamethasone, or water, which started 5 days before the induction, was fed every two days to each group. On day 21 post induction, the eyes were examined by confocal scanning laser ophthalmoscopy, optical coherence tomography (OCT), fundus fluorescein angiography (FFA) and electroretinography (ERG) prior to sacrificing the animals for histological assessments and gene expression studies. Retinal-choroidal thicknesses (RCT) and major retinal vessel diameter were measured on OCT sections and FFA images, respectively. Comparing to water-treated EAU animals, GTE attenuated uveitis clinical manifestations, RCT increase (1.100 ± 0.013 times vs 1.005 ± 0.012 times, P < 0.001), retinal vessel dilation (308.9 ± 6.189 units vs 240.8 units, P < 0.001), ERG amplitudes attenuation, histopathological ocular damages, and splenomegaly in EAU mice. The therapeutic effects of GTE were dose dependent and were comparable to dexamethasone. EGCG, a major active constituent of GTE, partially alleviated uveitic phenotypes including recovering visual function. Th-17 associated pro-inflammatory gene [interleukin 1 beta (IL-1β), IL-6, IL-17A, and tumor necrosis factor alpha (TNF-α)] expressions were down regulated by GTE and EGCG treatments, which showed no detectable morphological defects in liver and kidney in non-induced and EAU mice. Our findings suggest that GTE consumption can serve as a potent therapeutic agent as well as a food supplement for developing alternative treatments against autoimmune uveitis.

hCMV-Mediated Immune Escape Mechanisms Favor Pathogen Growth and Disturb the Immune Privilege of the Eye

Human retinal pigment epithelial (hRPE) cells are important for the establishment and maintenance of the immune privilege of the eye. They function as target cells for human cytomegalovirus (hCMV), but are able to restrict viral replication. hCMV causes opportunistic posterior uveitis such as retinitis and chorioretinitis. Both mainly occur in severely immunocompromised patients and rarely manifest in immunocompetent individuals. In this study, hRPE cells were infected with hCMV in vitro and activated with proinflammatory cytokines. The enzymatic activities of indoleamine 2,3-dioxygenase-1 (IDO1) and inducible nitric oxide synthase (iNOS) were determined. The antimicrobial capacity of both molecules was analyzed in co-infection experiments using Staphylococcus aureus (S. aureus) and Toxoplasmagondii (T. gondii), causing uveitis in patients. We show that an hCMV infection of hRPE cells blocks IDO1 and iNOS mediated antimicrobial defense mechanisms necessary for the control of S. aureus and T. gondii. hCMV also inhibits immune suppressive effector mechanisms in hRPE. The interferon gamma-induced IDO1 dependent immune regulation was severely blocked, as detected by the loss of T cell inhibition. We conclude that an active hCMV infection in the eye might favor the replication of pathogens causing co-infections in immunosuppressed individuals. An hCMV caused blockade of IDO1 might weaken the eye’s immune privilege and favor the development of post-infectious autoimmune uveitis.

Role of Bioactive Sphingolipids in Inflammation and Eye Diseases

Inflammation is a common underlying factor in a diversity of ocular diseases, ranging from macular degeneration, autoimmune uveitis, glaucoma, diabetic retinopathy and microbial infection. In addition to the variety of known cellular mediators of inflammation, such as cytokines, chemokines and lipid mediators, there is now considerable evidence that sphingolipid metabolites also play a central role in the regulation of inflammatory pathways. Various sphingolipid metabolites, such as ceramide (Cer), ceramide-1-phosphate (C1P), sphingosine-1-phosphate (S1P), and lactosylceramide (LacCer) can contribute to ocular inflammatory diseases through multiple pathways. For example, inflammation generates Cer from sphingomyelins (SM) in the plasma membrane, which induces death receptor ligand formation and leads to apoptosis of retinal pigment epithelial (RPE) and photoreceptor cells. Inflammatory stress by reactive oxygen species leads to LacCer accumulation and S1P secretion and induces proliferation of retinal endothelial cells and eventual formation of new vessels. In sphingolipid/lysosomal storage disorders, sphingolipid metabolites accumulate in lysosomes and can cause ocular disorders that have an inflammatory etiology. Sphingolipid metabolites activate complement factors in the immune-response mediated pathogenesis of macular degeneration. These examples highlight the integral association between sphingolipids and inflammation in ocular diseases.

In Vivo Expression of Mutant Calpains in the Eye Using Lentivirus

Exome sequencing has identified many candidate genes and mutations for human diseases, but the functional validation of these candidates is a time-consuming and costly process. Here, we describe a method which uses lentiviruses to overexpress calpain mutations that may play a role in dominant diseases such as autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV). The use of lentivirus to deliver the mutant calpain allows for a cost-effective, rapid, and efficient approach to test whether or not a candidate gene mutation from exome sequencing acts as the disease-causing allele for a human disorder. This method also provides for a comparison of different candidate mutations from a single gene identified by exome sequencing, as well as elucidating the mechanisms underlying these complex human disorders. Furthermore, this chapter focuses on two different methods to deliver mutant calpain to the cells of the eye, using either a subretinal or an intravitreal injection of the lentivirus into the mouse eye.

Clinical and Functional Evaluation of Ocular Inflammatory Disease Using the Model of Experimental Autoimmune Uveitis

Non-infections uveitis in humans is an autoimmune disease of the retina and uvea that can be blinding if untreated. Its laboratory equivalent is experimental autoimmune uveitis (EAU) induced in susceptible rodents by immunization with retinal antigens and described elsewhere in this series (Agarwal et al., Methods Mol Biol, 900:443-469, 2012). Evaluation and quantitation of the disease is usually performed by fundus examination and/or histopathology, which provide limited information on structural and no information on functional changes as disease progresses. Here, we describe methods for systematic evaluation of disease using noninvasive clinical assessments by fundus examination and photography, optical coherence tomography, and functional evaluation by electroretinography, which are then compared to histopathology. Using these methodologies, we demonstrate that clinical variants of disease can be accurately evaluated both clinically and functionally, facilitating longitudinal follow-up and providing information that cannot be obtained by fundoscopy and histology alone. These methodologies can be useful to obtain additional information and to evaluate effects of therapeutic modalities under investigation.

A pediatric case with parvovirus B19-associated uveitis without autoantibody formation

Acute parvovirus B19 (B19) infection is often accompanied by autoantibody formation, including antinuclear antibodies and rheumatoid factor, and the symptoms of the infection are similar to those of several autoimmune diseases. Uveitis is a representative manifestation of autoimmune diseases and is rarely caused by B19. Autoantibody formation was confirmed in 2 previously reported cases with B19-associated uveitis. However, whether B19-associated uveitis is caused by the direct invasion of the virus or the induction of autoimmunity remains unclear. We herein report a pediatric case with B19-associated uveitis without autoantibody formation. We speculated that B19 might have directly invaded the eye in this patient because of the development of uveitis without antibody formation and the negative results for anti-B19-specific antibodies in the serum at the onset of the disease. Although the mechanism of invasion is unknown, B19 may have a high affinity for tissue in the eye.

IL-20 receptor cytokines in autoimmune diseases

IL-19, IL-20, and IL-24 are the members of IL-10 family. They are also known as IL-20 receptor (IL-20R) cytokines as they all signal through the IL-20RA/IL-20RB receptor complex; IL-20 and IL-24 (but not IL-19) also signal through the IL-20RB/IL22RA1 receptor complex. Despite their protein structure homology and shared use of receptor complexes, they display distinct biological functions in immune regulation, tissue homeostasis, host defense, and oncogenesis. IL-20R cytokines can be expressed by both immune cells and epithelial cells, and are important for their interaction. In general, these cytokines are considered to be associated with pathogenesis of chronic inflammation and autoimmune diseases, including psoriasis, rheumatoid arthritis, and inflammatory bowel disease. However, a number of studies also highlighted their suppressive functions in regulating both innate and adaptive T cell responses and other immune cells, suggesting that the role of IL-20R cytokines in autoimmunity may be complex. In this review, we will discuss the immunobiological functions of IL-20R cytokines and how they are involved in regulating autoimmune diseases.

High-Dimensional Profiling Reveals Heterogeneity of the Th17 Subset and Its Association With Systemic Immunomodulatory Treatment in Non-infectious Uveitis

Background: Non-infectious uveitis (NIU) is a severe intra ocular inflammation, which frequently requires prompt systemic immunosuppressive therapy (IMT) to halt the development of vision-threatening complications. IMT is considered when NIU cannot be treated with corticosteroids alone, which is unpredictable in advance. Previous studies have linked blood cell subsets to glucocorticoid sensitivity, which suggests that the composition of blood leukocytes may early identify patients that will require IMT. Objective: To map the blood leukocyte composition of NIU and identify cell subsets that stratify patients that required IMT during follow-up. Methods: We performed controlled flow cytometry experiments measuring a total of 37 protein markers in the blood of 30 IMT free patients with active non-infectious anterior, intermediate, and posterior uveitis, and compared these to 15 age and sex matched healthy controls. Results from manual gating were validated by automatic unsupervised gating using FlowSOM. Results: Patients with uveitis displayed lower relative frequencies of Natural Killer cells and higher relative frequencies of memory T cells, in particular the CCR6+ lineages. These results were confirmed by automatic gating by unsupervised clustering using FlowSOM. We observed considerable heterogeneity in memory T cell subsets and abundance of CXCR3-CCR6+ (Th17) cells between the uveitis subtypes. Importantly, regardless of the uveitis subtype, patients that eventually required IMT in the course of the study follow-up exhibited increased CCR6+ T cell abundance before commencing therapy. Conclusion: High-dimensional immunoprofiling in NIU patients shows that clinically distinct forms of human NIU exhibit shared as well as unique immune cell perturbations in the peripheral blood and link CCR6+ T cell abundance to systemic immunomodulatory treatment.

TMP778, a selective inhibitor of RORγt, suppresses experimental autoimmune uveitis development, but affects both Th17 and Th1 cell populations

Experimental autoimmune uveitis (EAU), an animal model for severe intraocular inflammatory eye diseases, is mediated by both Th1 and Th17 cells. Here, we examined the capacity of TMP778, a selective inhibitor of RORγt, to inhibit the development of EAU, as well as the related immune responses. EAU was induced in B10.A mice by immunization with interphotoreceptor retinoid-binding protein (IRBP). Treatment with TMP778 significantly inhibited the development of EAU, determined by histological examination. In addition, the treatment suppressed the cellular immune response to IRBP, determined by reduced production of IL-17 and IFN-γ, as well as lower percentages of lymphocytes expressing these cytokines, as compared to vehicle-treated controls. The inhibition of IFN-γ expression by TMP778 is unexpected in view of this compound being a selective inhibitor of RORγt. The observation was further confirmed by the finding of reduced expression of the T-bet (Tbx21) gene, the transcription factor for IFN-γ, by cells of TMP778-treated mice. Thus, these data demonstrate the capacity of TMP778 to inhibit pathogenic autoimmunity in the eye and shed new light on its mode of action in vivo.

Tolerance Induction in Relation to the Eye

Inflammatory intraocular eye diseases, grouped under the term uveitis are blinding conditions, believed to be mediated by pathogenic autoimmune processes that overcome the protective mechanisms of the immune privilege status of the eye. An animal model for these diseases, named experimental autoimmune uveitis (EAU), is induced by initiation of immunity against ocular-specific antigens, or it develops spontaneously in mice with T-cells that transgenically express TCR specific to the target eye antigen(s). T-Cells specific to ocular antigens are generated in the thymus and their majority are eliminated by exposure to their target antigen expressed in this organ. T-cells that escape this negative selection acquire pathogenicity by their activation with the target antigen. In spontaneous EAU, the microbiota play crucial roles in the acquisition of pathogenicity by providing both antigenic stimulation, by molecules that mimic the target ocular antigen, and an additional stimulation that allows invasion of tissues that harbor the target antigen. The pathogenic process is physiologically inhibited by the peripheral tolerance, composed of antigen-specific T-regulatory (Treg) lymphocytes. Deleting the Tregs enhances the ocular inflammation, whereas adoptively transferring them suppresses the pathogenic response. Potential usage of Treg cells for suppression of autoimmune diseases in humans is under intensive investigation.