Involvement of B cells in non-infectious uveitis

Microglial-mediated immune mechanisms in autoimmune uveitis: Elucidating pathogenic pathways and targeted therapeutics

This review offers a comprehensive examination of the role of microglia in the pathogenesis of autoimmune uveitis, an inflammatory eye disease with significant potential for vision impairment. Central to our discussion is the dual nature of microglial cells, which act as both protectors and potential perpetrators in the immune surveillance of the retina. We explore the mechanisms of microglial activation, highlighting the key signaling pathways involved, such as NF-κB, JAK/STAT, MAPK, and PI3K/Akt. The review also delves into the genetic and environmental factors influencing microglial behavior, underscoring their complex interaction in disease manifestation. Advanced imaging techniques and emerging biomarkers for microglial activation, pivotal in diagnosing and monitoring the disease, are critically assessed. Additionally, we discuss current and novel therapeutic strategies targeting microglial activity, emphasizing the shift towards more precise and personalized interventions. This article aims to provide a nuanced understanding of microglial dynamics in autoimmune uveitis, offering insights into potential avenues for effective treatment and management.

Repurposing of rituximab biosimilars to treat B cell mediated autoimmune diseases

Rituximab, the first monoclonal antibody approved for the treatment of lymphoma, eventually became one of the most popular and versatile drugs ever in terms of clinical application and revenue. Since its patent expiration, and consequently, the loss of exclusivity of the original biologic, its repurposing as an off-label drug has increased dramatically, propelled by the development and commercialization of its many biosimilars. Currently, rituximab is prescribed worldwide to treat a vast range of autoimmune diseases mediated by B cells. Here, we present a comprehensive overview of rituximab repurposing in 115 autoimmune diseases across 17 medical specialties, sourced from over 1530 publications. Our work highlights the extent of its off-label use and clinical benefits, underlining the success of rituximab repurposing for both common and orphan immune-related diseases. We discuss the scientific mechanism associated with its clinical efficacy and provide additional indications for which rituximab could be investigated. Our study presents rituximab as a flagship example of drug repurposing owing to its central role in targeting cluster of differentiate 20 positive (CD20) B cells in 115 autoimmune diseases.

Pathogenesis and current therapies for non-infectious uveitis

Non-infectious uveitis (NIU) is a disorder with various etiologies and is characterized by eye inflammation, mainly affecting people of working age. An accurate diagnosis of NIU is crucial for appropriate therapy. The aim of therapy is to improve vision, relieve ocular inflammation, prevent relapse, and avoid treatment side effects. At present, corticosteroids are the mainstay of topical or systemic therapy. However, repeated injections are required for the treatment of chronic NIU. Recently, new drug delivery systems that may ensure intraocular delivery of therapeutic drug levels have been highlighted. Furthermore, with the development of immunosuppressants and biologics, specific therapies can be selected based on the needs of each patient. Immunosuppressants used in the treatment of NIU include calcineurin inhibitors and antimetabolites. However, systemic immunosuppressive therapy itself is associated with adverse effects due to the inhibition of immune function. In patients with refractory NIU or those who cannot tolerate corticosteroids and immunosuppressors, biologics have emerged as alternative treatments. Thus, to improve the prognosis of patients with NIU, NIU should be managed with different drugs according to the response to treatment and possible side effects.

Phasic regulation of the ATP/P2X7 receptor signaling pathway affects the function of antigen-presenting cells in experimental autoimmune uveitis

Purinergic ligand-gated ion channel 7 receptor (P2X7R) is a purine type P2 receptor that is expressed on a variety of immune cells. Recent studies have shown that P2X7R signaling is required to trigger an immune response, and P2X7R antagonist-oxidized ATP (oxATP) effectively blocks P2X7R activation. In this study, we investigated the effect of phasic regulation of the ATP/P2X7R signaling pathway on antigen-presenting cells (APCs) by constructing an experimental autoimmune uveitis (EAU) disease model. Our results demonstrated that APCs isolated from the 1st, 4th, 7th and 11th days of EAU presented antigen function and could stimulate the differentiation of naive T cells. Moreover, after stimulation by ATP and BzATP (a P2X7R agonist), antigen presentation, promoting differentiation and inflammation were enhanced. The regulation of the Th17 cell response was significantly stronger than that of the Th1 cell response. In addition, we verified that oxATP blocked the P2X7R signaling pathway on APCs, attenuated the effect of BzATP, and significantly improved the adoptive transfer EAU induced by antigen-specific T cells cocultured with APCs. Our results demonstrated that at an early stage of EAU, the ATP/P2X7R signaling pathway regulation of APCs was time dependent, and the treatment of EAU could be achieved by intervening in P2X7R function on APCs.

A new small molecule DHODH-inhibitor [KIO-100 (PP-001)] targeting activated T cells for intraocular treatment of uveitis — A phase I clinical trial

Uveitis is a T cell-mediated, intraocular inflammatory disease and one of the main causes of blindness in industrialized countries. There is a high unmet need for new immunomodulatory, steroid-sparing therapies, since only ciclosporin A and a single TNF-α-blocker are approved for non-infectious uveitis. A new small molecule inhibitor of dihydroorotate dehydrogenase (DHODH), an enzyme pivotal for de novo synthesis of pyrimidines, has a high potency for suppressing T and B cells and has already proven highly effective for treating uveitis in experimental rat models. Systemic and intraocular application of KIO-100 (PP-001) (previously called PP-001, now KIO-100) could efficiently suppress rat uveitis in a preventive as well as therapeutic mode. Here we describe the outcome of the first clinical phase 1 trial comparing three different doses of a single intraocular injection of KIO-100 (PP-001) in patients with non-infectious posterior segment uveitis. No toxic side effects on intraocular tissues or other adverse events were observed, while intraocular inflammation decreased, and visual acuity significantly improved. Macular edema, a sight-threatening complication in uveitis, showed regression 2 weeks after intraocular KIO-100 (PP-001) injection in some patients, indicating that this novel small molecule has a high potential as a new intraocular therapy for uveitis.

JAK-STAT Signaling Pathway in Non-Infectious Uveitis

Non-infectious uveitis (NIU) refers to various intraocular inflammatory disorders responsible for severe visual loss. Cytokines participate in the regulation of ocular homeostasis and NIU pathological processes. Cytokine receptors transmit signals by activating Janus kinase (JAK) and signal transducer and activator of transcription (STAT) proteins. Increasing evidence from human NIU and experimental models reveals the involvement of the JAK-STAT signaling pathway in NIU pathogenesis. Several small-molecule drugs that potentially inhibit multiple cytokine-dependent pathways are under investigation for treating autoimmune diseases, implicating possible applications for NIU treatment. This review summarizes the current understanding of the diverse roles of the JAK-STAT signaling pathway in ocular homeostasis and NIU pathology, providing a rationale for targeting JAKs and STATs for NIU treatment. Moreover, available evidence for the safety and efficacy of JAK inhibitors for refractory uveitis and potential approaches for treatment optimization are discussed.

Anti-CD20 therapy for multiple sclerosis associated uveitis: a case series

BACKGROUND

About 1% of patients with multiple sclerosis (MS) suffer from uveitis, but data on the effects of immunotherapies for MS on MS-associated uveitis are scarce.

OBJECTIVE

To investigate the ophthalmological outcomes in patients with MS-associated uveitis treated with anti-CD20 therapy.

METHODS

Retrospective study of 12 eyes of 6 patients with MS-associated uveitis, refractory to previous immunotherapies. Uveitis activity was assessed before initiation of anti-CD20 therapy and at regular follow-up visits. Primary outcome measures were vitreous haze score, retinal vasculitis score determined on fluorescein angiography images, macular edema as quantified by central retinal thickness (CRT) on optical coherence tomography, and visual acuity. Secondary outcomes included the number of annualized uveitis or MS relapses, disease activity on cerebral magnetic resonance imaging (cMRI) and the expanded disability status scale (EDSS).

RESULTS

After a median (IQR) treatment time of 28.5 (8-43) months, anti-CD20 therapy was associated with an improvement of vitreous haze score (p=0.002), retinal vasculitis score (p=0.001), CRT (p=0.002), and visual acuity (p=0.007). The median (IQR) annualized uveitis relapse rate declined from 0.59 (0.56-0.94) before to 0 (0-0.49) after the start of anti-CD20 therapy. The median (IQR) annualized MS relapse rate declined from 0.62 (0.26-2.84) before to 0 (0-0) after the start of anti-CD20 therapy. After initiation of anti-CD20 therapy, there was no disease activity on cMRI and the EDSS improved (n=2) or remained stable (n=4). No severe adverse events were observed.

CONCLUSION

These findings suggest that anti-CD20 therapy may be a valuable treatment option for MS-associated uveitis.

Mixed B- and T-lymphocyte Vitreous Infiltrate in Multiple Sclerosis Associated Uveitis

A 23-year-old man, under treatment for relapsing remitting multiple sclerosis, presented with sudden drop in vision in the left eye for the past 1 week. We noted optic atrophy with sclerosed vessels in multiple quadrants in both eyes, moderate vitreous haze, and active retinal vasculitis in left eye. The patient received therapeutic pars plana vitrectomy in the left eye, and the vitreous sample was analyzed for immunophenotypes by flow cytometry (T-cells) and immunohistochemistry (B-cells). 65.1% of total vitreous cells were CD3⁺ T-cells. These included 42.4% CD4⁺, and 20.6% CD8⁺ T-cells. Immunohistochemistry detected CD20⁺ B-cells (not quantifiable). Our analysis demonstrated a mixed B- and T-lymphocyte vitreous infiltrate in multiple sclerosis-associated uveitis.

Immune Cells in Subretinal Wound Healing and Fibrosis

The subretinal space is devoid of any immune cells under normal conditions and is an immune privileged site. When photoreceptors and/or retinal pigment epithelial cells suffer from an injury, a wound healing process will be initiated. Retinal microglia and the complement system, as the first line of retinal defense, are activated to participate in the wound healing process. If the injury is severe or persists for a prolonged period, they may fail to heal the damage and circulating immune cells will be summoned leading to chronic inflammation and abnormal wound healing, i.e., subretinal or intraretinal fibrosis, a sight-threatening condition frequently observed in rhematogenous retinal detachment, age-related macular degeneration and recurrent uveoretinitis. Here, we discussed the principles of subretinal wound healing with a strong focus on the conditions whereby the damage is beyond the healing capacity of the retinal defense system and highlighted the roles of circulating immune cells in subretinal wound healing and fibrosis.

Single subcutaneous injection of the minocycline nanocomposite-loaded thermosensitive hydrogel for the effective attenuation of experimental autoimmune uveitis

Autoimmune uveitis induces a serious pathological and inflammatory response in the retina/choroid and results in vision impairment and blindness. Here, we report a minocycline (Mino) nanocomposite-loaded hydrogel offering a high drug payload and sustained drug release for the effective control of ocular inflammation via a single subcutaneous injection. In the presence of divalent cations (i.e., Ca²⁺), Mino was found to co-assemble with a phosphorylated peptide (i.e., NapGFFpY) via electrostatic interaction and consequently generating Mino nanocomposite. The drug entrapment efficiency (EE) of the Mino nanocomposite varied from 29.93±0.76% to 67.90±6.57%, depending on different component concentrations. After incorporation into 30 wt% poly (D,L-lactide)-b-poly (ethylene glycol)-b-poly (D,L-lactide) (PDLLA-PEG-PDLLA) thermosensitive hydrogel, the resulting Mino nanocomposite-loaded hydrogel provided a sustained drug release over 21 days. In the experimental autoimmune uveitis (EAU) rat model, a single subcutaneous injection of the Mino nanocomposite-loaded hydrogel effectively alleviated ocular inflammation in a dose-dependent manner. As indicated by optical coherence tomography (OCT) and electroretinogram (ERG) measurements, the Mino nanocomposite-loaded hydrogel treatment not only remarkably reduced destruction of the retina by EAU, but also greatly rescued retinal functions. Moreover, the proposed Mino nanocomposite-loaded hydrogel exerted its therapeutic effect on EAU primarily through a significant reduction of the influx of leukocytes and Th17 cells as well as suppression of microglia activation and apoptosis in the retina. Overall, the proposed Mino nanocomposite-loaded hydrogel might be a promising strategy for the clinical management of EAU.

Increased vitreous levels of B cell activation factor (BAFF) and soluble interleukin-6 receptor in patients with macular edema due to uveitis related to Behçet's disease and sarcoidosis

PURPOSE

Uveitis accounts for 10-15% of all cases of blindness in the developed world. Uveitic macular edema (UME) is a primary cause of permanent visual impairment in patients with uveitis. Because proinflammatory mediators elicit inflammation and lead to UME, we determined the profiles of proinflammatory mediators associated with complications, such as ME, in the vitreous humor of patients with panuveitis related to Behçet's disease (BD) and sarcoidosis.

METHODS

In this retrospective study, we enrolled 21 patients with uveitis, including 6 with BD and 15 with sarcoidosis, and 15 patients with idiopathic epiretinal membrane (iERM) at the Department of Ophthalmology, Kyushu University Hospital, between January 2008 and April 2016. Vitreous concentrations of 32 proinflammatory mediators, including cytokines and soluble receptors of tumor necrosis factor (TNF) and interleukin (IL)-6 families, were assessed using a bead-based multiplex assay and their association with clinical data was examined.

RESULTS

The levels of proinflammatory mediators, including a proliferation-inducing ligand (APRIL), B cell activating factor belonging to the TNF family (BAFF), soluble cluster of differentiation 30 (sCD30), soluble TNF receptor-1 (sTNFR1), sTNFR2, TNF-α, IL-6, and soluble IL-6 receptor-α (sIL-6Rα), were significantly higher in patients with uveitis. With regard to clinical parameters in patients with uveitis, vitreous levels of BAFF and sIL-6Rα were prominently elevated in patients with UME compared to in those without UME (P < 0.01, respectively).

CONCLUSIONS

Our results suggest that elevated vitreous levels of BAFF and sIL-6Rα are associated with the pathogenesis of UME in patients with panuveitis related to BD and sarcoidosis.

Aging weakens Th17 cell pathogenicity and ameliorates experimental autoimmune uveitis in mice

Aging-induced changes in the immune system are associated with a higher incidence of infection and vaccination failure. Lymph nodes, which filter the lymph to identify and fight infections, play a central role in this process. However, careful characterization of the impact of aging on lymph nodes and associated autoimmune diseases is lacking. We combined single-cell RNA sequencing (scRNA-seq) with flow cytometry to delineate the immune cell atlas of cervical draining lymph nodes (CDLNs) of both young and old mice with or without experimental autoimmune uveitis (EAU). We found extensive and complicated changes in the cellular constituents of CDLNs during aging. When confronted with autoimmune challenges, old mice developed milder EAU compared to young mice. Within this EAU process, we highlighted that the pathogenicity of T helper 17 cells (Th17) was dampened, as shown by reduced GM-CSF secretion in old mice. The mitigated secretion of GM-CSF contributed to alleviation of IL-23 secretion by antigen-presenting cells (APCs) and may, in turn, weaken APCs’ effects on facilitating the pathogenicity of Th17 cells. Meanwhile, our study further unveiled that aging downregulated GM-CSF secretion through reducing both the transcript and protein levels of IL-23R in Th17 cells from CDLNs. Overall, aging altered immune cell responses, especially through toning down Th17 cells, counteracting EAU challenge in old mice.

Insights into multiple sclerosis-associated uveitis: a scoping review

PURPOSE

This paper is a scoping review of research on multiple sclerosis (MS)-associated uveitis to determine its epidemiology, pathophysiology, clinical features and treatment.

METHODS

A comprehensive search of the medical databases MEDLINE (PubMed), EMBASE, Web of Science and Cochrane was carried out on 25 November 2019, to identify papers published between 1980 and 2019 that focus on patients with MS-associated uveitis.

RESULTS

Based on large cohort studies (n ≥ 1000), the prevalence of uveitis in patients with MS is estimated to be 0.53-1.34% (mean = 0.83%), and MS is diagnosed in 0.52-3.20% (mean = 1.30%) of patients with uveitis. The condition is most frequent among middle-aged women. Patients usually complain of floaters and/or blurred vision, with bilateral intermediate uveitis (with retinal vasculitis) as the most frequent ophthalmological finding. Both MS and intermediate uveitis are associated with HLA-DRB1*15:01 and IL-2RA gene polymorphism rs2104286 A > G, suggesting a common genetic background. T cells, and possibly B cells, play an important role in both autoimmune disorders. Multiple sclerosis (MS)-related uveitis is classically treated as non-infectious uveitis, with corticosteroids as the first treatment step. Other treatments include immunosuppressants, cryotherapy, laser photocoagulation and vitrectomy. These treatment options have a limited, if any, effect on the course of MS and can be complicated by side-effects. As treatment strategies for MS have increased in the last decade, it would be interesting to evaluate the efficacy of these new treatments during the course of uveitis. Moreover, the correlation between retinal periphlebitis and MS could be established more accurately with the recently developed techniques of wide-field fluorescein angiography in a large cohort of MS patients.

CONCLUSION

MS-associated uveitis is a rare, highly discussed pathology about which much is still unknown. Large epidemiological studies and extrapolation of new MS treatments to this condition are warranted.

Blocking the inflammasome: A novel approach to treat uveitis

Uveitis is a complex ocular inflammatory disease often accompanied by bacterial or viral infections (infectious uveitis) or underlying autoimmune diseases (non-infectious uveitis). Treatment of the underlying infection along with corticosteroid-mediated suppression of acute inflammation usually resolves infectious uveitis. However, to develop more effective therapies for non-infectious uveitis and to better address acute inflammation in infectious disease, an improved understanding of the underlying inflammatory pathways is needed. In this review, we discuss the disease aetiology, preclinical in vitro and in vivo uveitis models, the role of inflammatory pathways, as well as current and future therapies. In particular, we highlight the involvement of the inflammasome in the development of non-infectious uveitis and how it could be a future target for effective treatment of the disease.

A Review of the Various Roles and Participation Levels of B-Cells in Non-Infectious Uveitis

Non-infectious uveitis is an inflammatory disorder of the eye that accounts for severe visual loss without evident infectious agents. While T cells are supposed to dominate the induction of inflammation in non-infectious uveitis, the role of B cells in the pathogenesis of this disease is obscure. Therefore, this review aimed to discuss diverse B-cell participation in different non-infectious uveitides and their roles in the pathogenesis of this disease as well as the mechanism of action of rituximab. Increasing evidence from experimental models and human non-infectious uveitis has suggested the participation of B cells in non-infectious uveitis. The participation levels vary in different uveitides. Furthermore, B cells play multiple roles in the pathogenic mechanisms. B cells produce autoantibodies, regulate T cell responses via antibody-independent functions, and constitute ectopic lymphoid structures. Regulatory B cells perform pivotal anti-inflammatory functions in non-infectious uveitis. Rituximab may work by depleting pro-inflammatory B cells and restoring the quantity and function of regulatory B cells in this disease. Identifying the levels of B-cell participation and the associated roles is beneficial for optimizing therapy. Diversified experimental model choices and emerging tools and/or methods are conducive for future studies on this topic.

Intermediate uveitis associated with MS: Diagnosis, clinical features, pathogenic mechanisms, and recommendations for management

Uveitis is a major cause of visual impairment and blindness among working-age adults, accounting for 10% of legal blindness in the United States. Among people with MS, the prevalence of uveitis is 10 times higher than among the general population, and because MS and uveitis share similar genetic risk factors and immunologic effector pathways, it is not clear whether uveitis is one of the manifestations of MS or a coincident disorder. This uncertainty raises several diagnostic and management issues for clinicians who look after these patients, particularly with regard to recognizing visual symptoms resulting from demyelination, intraocular inflammation, or the visual complications of disease modifying drugs for MS, e.g., fingolimod. Likewise, management decisions regarding patients with uveitis are influenced by the risk of precipitating or exacerbating episodes of demyelination, e.g., following anti-tumor necrosis factor biologic therapy, and other neurologic complications of immunosuppressive treatments for uveitis. In this review, we explore the similarities in the pathophysiology, clinical features, and treatment of patients with uveitis and MS. Based on the latest evidence, we make a set of recommendations to help guide neurologists and ophthalmologists to best manage patients affected by both conditions.

Whole Transcriptome Analysis Reveals Heterogeneity in B Cell Memory Populations in Patients With Juvenile Idiopathic Arthritis-Associated Uveitis

Purpose

Patients with juvenile idiopathic arthritis (JIA) are prone to developing chronic anterior uveitis (JIA-U+). Although several risk factors for JIA-U+ have been identified, the underlying etiology is poorly understood. Histopathological studies demonstrate B cell infiltrates in eye tissues of patients with JIA-U+.

Methods

We performed transcriptome profiling of peripheral blood CD19-positive B cells taken from 14 cases with JIA-U+, 13 JIA cases without uveitis (JIA-U-), and five healthy controls. Deconvolution-based estimation was used to determine the immune cell fractions for each sample.

Results

Deconvolution results revealed that naive B cells made up on average 71% of the CD19-positive cell fractions analyzed. Differential expression analysis identified 614 differentially expressed genes (DEGs) between the groups at nominal significance and six genes at a false discovery rate of 5% (FDR < 0.05). Head-to-head comparison of all JIA-U- versus JIA-U+ revealed no DEGs in the CD19+ B cell pool (FDR < 0.05). However, principal component analysis based on a panel of key genes for B cell subsets revealed that JIA-U+ cases bifurcate into distinct clusters, characterized by markedly disparate expression for genes associated with specific memory B cell populations. CIBERSORT analysis of the overall transcriptome of the new uveitis cluster identified an increased proportion of memory B cells.

Conclusion

These data show that JIA-U- and JIA-U+ have a globally similar transcriptome considering the global peripheral CD19-positive B cell pool. However, heterogeneity in B cell memory genes among cases with uveitis suggests a role for specific memory B cell subsets in the etiology of JIA-U+.

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.

Bioluminescence for in vivo detection of cell-type-specific inflammation in a mouse model of uveitis

This study reports the use of cell-type-specific in vivo bioluminescence to measure intraocular immune cell population dynamics during the course of inflammation in a mouse model of uveitis. Transgenic lines expressing luciferase in inflammatory cell subsets (myeloid cells, T cells, and B cells) were generated and ocular bioluminescence was measured serially for 35 days following uveitis induction. Ocular leukocyte populations were identified using flow cytometry and compared to the ocular bioluminescence profile. Acute inflammation is neutrophilic (75% of ocular CD45 + cells) which is reflected by a significant increase in ocular bioluminescence in one myeloid reporter line on day 2. By day 7, the ocular T cell population increases to 50% of CD45 + cells, leading to a significant increase in ocular bioluminescence in the T cell reporter line. While initially negligible (< 1% of CD45 + cells), the ocular B cell population increases to > 4% by day 35. This change is reflected by a significant increase in the ocular bioluminescence of the B cell reporter line starting on day 28. Our data demonstrates that cell-type-specific in vivo bioluminescence accurately detects changes in multiple intraocular immune cell populations over time in experimental uveitis. This assay could also be useful in other inflammatory disease models.

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.

Resolution of uveitis

Autoimmune uveitis is a sight-threatening, rare disease, potentially leading to blindness. Uveitis is a synonym for intraocular inflammation, presenting as various clinical phenotypes with different underlying immune responses in patients, whereas different animal models usually represent one certain clinical and immunological type of uveitis due to genetic uniformity and the method of disease induction. T cells recognizing intraocular antigens initiate the disease, recruiting inflammatory cells (granulocytes, monocytes/macrophages) to the eyes, which cause the damage of the tissue. The treatment of uveitis so far aims at downregulation of inflammation to protect the ocular tissues from damage, and at immunosuppression to stop fueling T cell reactivity. Uveitis is usually prevented by specific mechanisms of the ocular immune privilege and the blood-eye-barriers, but once the disease is induced, mechanisms of the immune privilege as well as a variety of novel regulatory features including new Treg cell populations and suppressive cytokines are induced to downregulate the ocular inflammation and T cell responses and to avoid relapses and chronicity. Here we describe mechanisms of regulation observed in experimental animal models as well as detected in studies with peripheral lymphocytes from patients.

Comparison of Aqueous and Vitreous Lymphocyte Populations From Two Rat Models of Experimental Uveitis

Purpose

To compare lymphocyte populations present within inflamed eyes in two rat models of autoimmune uveitis.

Methods

Experimental autoimmune uveitis (EAU) and primed mycobacterial uveitis (PMU) were initiated in Lewis rats. Aqueous and vitreous were collected at peak inflammation (PMU at day 2, EAU at day 14). The number of cells in the aqueous and vitreous was determined and compared for each eye and between the two models. Intraocular CD-19⁺ B cells, CD3⁺ T cells, and CD4⁺ or CD8⁺ T-cell subpopulations were identified by flow cytometry and compared between EAU and PMU.

Results

The median number of cells/mL collected from PMU aqueous (7.98 × 10⁷ cells/mL), was not significantly different from the number of cells collected from EAU aqueous (1.61 × 10⁷ cells/mL, P = 0.94). EAU aqueous contains a significantly larger mononuclear population (median 61%, interquartile range [IQR] 44%–67%) than PMU (median 9%, IQR 8%–10% [P < 0.0001]). Within the mononuclear population, EAU and PMU aqueous demonstrate similar proportions of CD3⁺, CD4⁺ T cells. However, EAU has a larger CD3⁺, CD8⁺, T-cell population than PMU, and this population also demonstrates co-expression of CD45R. B cells comprise a significantly larger median percentage of cells in EAU aqueous (median 18%, IQR 15%–20%) compared to PMU (median 13%, IQR 9%–15%, P = 0.006).

Conclusions

Flow cytometry analysis of intraocular lymphocytes from EAU and PMU identifies similarities and differences between the T-cell and B-cell populations present at peak inflammation. Complementary animal models that have well-defined mechanistic differences will improve our ability to test potential new therapies and bring meaningful advances into clinical practice for patients with uveitis.

Identification of unique proteins in vitreous fluid of patients with noninfectious uveitis

PURPOSE

Uveitis is a cause for concern in the developing countries like India. Its poor diagnosis and lack of proper therapeutics often cause blindness in children and young adults. Moreover, the exact mechanism of pathogenesis of different types of uveitis is still elusive. Modern proteomic techniques are found to be advantageous for an in-depth understanding of the ocular physiology using proteomic diversity. Our aim was to identify unique proteins involved in the pathogenesis of autoimmune or noninfectious uveitis.

METHODS

Vitreous fluid samples (n = 90) were obtained from infectious (N = 34) and noninfectious (N = 56) uveitis patients, and their protein profiles were compared by analysing sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and 2D electrophoresis. Unique proteins were identified through matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and further studied for pathway analysis.

RESULTS

Protein spots having different molecular weights were observed in noninfectious vitreous fluid samples. Enzymatic digestion of these spots after MALDI-TOF MS analysis revealed different proteins. We identified 25 different proteins through SDS-PAGE and 22 through 2D electrophoresis. 50% of the proteins from SDS-PAGE were associated with heterotrimeric G-protein signalling pathway-rod outer segment phototransduction. 50% proteins from SDS-PAGE and 20% from 2D electrophoresis revealed association with de novo purine biosynthesis. Carbonic anhydrase 1 and serpin B3 were found to be common in both analyses.

CONCLUSION

High-throughput proteomic and pathway analyses have exposed the potential association of these proteins with autoimmune pathogenesis in uveitis. The exact role of most of the proteins in autoimmune uveitis is yet to be unfurled.

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.

Innate and Adaptive Cell Populations Driving Inflammation in Dry Eye Disease

Dry eye disease (DED) is the most common ocular disease and affects millions of individuals worldwide. DED encompasses a heterogeneous group of diseases that can be generally divided into two forms including aqueous-deficient and evaporative DED. Evidence suggests that these conditions arise from either failure of lacrimal gland secretion or low tear film quality. In its secondary form, DED is often associated with autoimmune diseases such as Sjögren's syndrome and rheumatoid arthritis. Current treatment strategies for DED are limited to anti-inflammatory medications that target the immune system as the source of deleterious inflammation and tissue injury. However, there is a lack of understanding of the underlying pathogenesis of DED, and subsequently, there are very few effective treatment strategies. The gap in our knowledge of the etiology of primary DED is in part because the majority of research in DED focused on secondary autoimmune causes. This review focuses on what is currently understood about the contribution of innate and adaptive immune cell populations in the pathogenesis of DED and highlights the need to continue investigating the central role of immunity driving DED.

LONG-TERM OUTCOMES OF RITUXIMAB THERAPY IN PATIENTS WITH NONINFECTIOUS POSTERIOR UVEITIS REFRACTORY TO CONVENTIONAL IMMUNOSUPPRESSIVE THERAPY

PURPOSE

To assess long-term effectiveness of rituximab therapy for refractory noninfectious uveitis affecting the posterior segment.

METHODS

Retrospective case series. Patients diagnosed with recalcitrant noninfectious posterior uveitis who were treated with rituximab intravenous infusions between 2010 and 2015 were included. Patients underwent best-corrected visual acuity testing and fluorescein angiography evidence of disk or vascular staining at 6, 12, 18, and 24 months. Patients had at least 24 months of follow-up.

RESULTS

Eleven patients (21 eyes) with refractory posterior uveitis treated with intravenous rituximab were included. Nine (81.8%) patients were female. Mean follow-up was 29.3 ± 7.8 months. rituximab was administered as complementary therapy because of previous inefficacy of other therapies in 7 (63.7%) patients, and it was the only treatment in four (36.3%) patients who did not tolerate other drugs. Inflammation signs by fluorescein angiography were controlled in nine (81.8%) patients at the end of follow-up. Baseline best-corrected visual acuity was 20/80 (logarithm of the minimal angle of resolution 0.6 ± 0.4), and final best-corrected visual acuity was 20/40 (0.3 ± 0.5) (P = 0.005). No significant side effects were reported.

CONCLUSION

Rituximab therapy was associated with stability and remission of recalcitrant noninfectious posterior uveitis in patients who did not tolerate or did not respond to other therapies.

Re-programming immunosurveillance in persistent non-infectious ocular inflammation

Ocular function depends on a high level of anatomical integrity. This is threatened by inflammation, which alters the local tissue over short and long time-scales. Uveitis due to autoimmune disease, especially when it involves the retina, leads to persistent changes in how the eye interacts with the immune system. The normal pattern of immune surveillance, which for immune privileged tissues is limited, is re-programmed. Many cell types, that are not usually present in the eye, become detectable. There are changes in the tissue homeostasis and integrity. In both human disease and mouse models, in the most extreme cases, immunopathological findings consistent with development of ectopic lymphoid-like structures and disrupted angiogenesis accompany severely impaired eye function. Understanding how the ocular environment is shaped by persistent inflammation is crucial to developing novel approaches to treatment.

A model to study complement involvement in experimental retinal degeneration

BACKGROUND

The complement system (CS) plays a role in the pathogenesis of a number of ocular diseases, including diabetic retinopathy (DR), glaucoma, uveitis, and age-related macular degeneration (AMD). Given that many of the complex eye-related degenerative diseases have limited treatment opportunities, we aimed to mimic the in vivo retinal degenerative process by developing a relevant co-culture system.

METHOD AND MATERIALS

The adult porcine retina was co-cultured with the spontaneously arising human retinal pigment epithelial cells-19 (ARPE-19).

RESULTS

Inflammatory activity was found after culture and included migrating microglial cells, gliosis, cell death, and CS activation (demonstrated by a minor increase in the secreted anaphylotoxin C3a in co-culture). CS components, including C1q, C3, C4, soluble C5b-9, and the C5a receptor, were expressed in the retina and/or ARPE cells after culture. C1q, C3, and CS regulators such as C4 binding protein (C4BP), factor H (CFH), and factor I (CFI) were secreted after culture.

DISCUSSION

Thus, our research indicates that this co-culturing system may be useful for investigations of the CS and its involvement in experimental neurodegenerative diseases.

Modern Therapeutic Approaches for Noninfectious Ocular Diseases Involving Inflammation

Dry eye disease, age-related macular degeneration, and uveitis are ocular diseases that significantly affect the quality of life of millions of people each year. In these diseases, the action of chemokines, proinflammatory cytokines, and immune cells drives a local inflammatory response that results in ocular tissue damage. Multiple therapeutic strategies are developed to either address the symptoms or abate the underlying cause of these diseases. Herein, the challenges to deliver drugs to the relevant location in the eye for each of these diseases are reviewed along with current and innovative therapeutic approaches that attempt to restore homeostasis within the ocular microenvironment.

Tubulointerstitial nephritis and uveitis

PURPOSE OF REVIEW

Tubulointerstitial nephritis and uveitis (TINU) is an important yet underrecognized ocular inflammatory syndrome. This review summarizes key historical publications that identified and defined the syndrome, and more recent literature that reveal the importance of urinary β2-microglobulin testing and kidney biopsy in the diagnostic evaluation of patients with TINU. Additionally, research studies providing new insights into disease pathogenesis are highlighted.

RECENT FINDINGS

In contrast with initial reports of TINU manifesting exclusively as an anterior uveitis in pediatric patients, more recent reports have identified TINU in patients of all ages with a wide range of ocular manifestations. Urinary β2-microglobulin has emerged as a sensitive and specific laboratory screening test, and the role of kidney biopsy in differentiating TINU from sarcoidosis continues to evolve. Genetic studies have identified HLA-DQA101, HLA-DQB105, and HLA-DRB101 as high-risk alleles and the identification of antimonomeric C-reactive protein antibodies suggests a role for humoral immunity in disease pathogenesis. Management strategies have evolved to include systemic anti-inflammatory treatment as a result of important outcome studies in patients with significant renal and ocular disease.

SUMMARY

With greater recognition, understanding, and treatment of this syndrome, both ocular inflammation and renal disease can be better addressed.

Short chain fatty acids ameliorate immune-mediated uveitis partially by altering migration of lymphocytes from the intestine

Short chain fatty acids (SCFA) are metabolites of intestinal bacteria resulting from fermentation of dietary fiber. SCFA are protective in various animal models of inflammatory disease. We investigated the effects of exogenous administration of SFCAs, particularly propionate, on uveitis using an inducible model of experimental autoimmune uveitis (EAU). Oral SCFA administration attenuated uveitis severity in a mouse strain-dependent manner through regulatory T cell induction among lymphocytes in the intestinal lamina propria (LPL) and cervical lymph nodes (CLN). SCFA also suppressed effector T cell induction in the CLN and mesenteric lymph nodes (MLN). Alterations in intestinal morphology and gene expression demonstrated in the EAU model prior to the onset of uveitis were blunted by oral SCFA administration. Using a Kaede transgenic mouse, we demonstrated enhanced leukocyte trafficking between the intestine and the eye in EAU. Propionate suppressed T effector cell migration between the intestine and the spleen in EAU Kaede mice. In conclusion, our findings support exogenous administration of SCFAs as a potential treatment strategy for uveitis through the stabilization of subclinical intestinal alterations that occur in inflammatory diseases including uveitis, as well as prevention of trafficking of leukocytes between the gastrointestinal tract and extra-intestinal tissues.

The link between morphology and complement in ocular disease

The complement system is a vital component of the immune-priveliged human eye that is always active at a low-grade level, preventing harmful intraocular injuries caused by accumulation of turnover products and controlling pathogens to preserve eye homeostasis and vision. The complement system is a double-edged sword that is essential for protection but may also become harmful and contribute to eye pathology. Here, we review the evidence for the involvement of complement system dysregulation in age-related macular degeneration, glaucoma, uveitis, and neuromyelitis optica, highlighting the relationship between morphogical changes and complement system protein expression and regulation in these diseases. The potential benefits of complement inhibition in age-related macular degeneration, glaucoma, uveitis, and neuromyelitis optica are abundant, as are those of further research to improve our understanding of complement-mediated injury in these diseases.