Microglial mediators in autoimmune Uveitis: Bridging neuroprotection and neurotoxicity

Autoimmune uveitis, a severe inflammatory condition of the eye, poses significant challenges due to its complex pathophysiology and the critical balance between protective and detrimental immune responses. Central to this balance are microglia, the resident immune cells of the central nervous system, whose roles in autoimmune uveitis are multifaceted and dynamic. This review article delves into the dual nature of microglial functions, oscillating between neuroprotective and neurotoxic outcomes in the context of autoimmune uveitis. Initially, we explore the fundamental aspects of microglia, including their activation states and basic functions, setting the stage for a deeper understanding of their involvement in autoimmune uveitis. The review then navigates through the intricate mechanisms by which microglia contribute to disease onset and progression, highlighting both their protective actions in immune regulation and tissue repair, and their shift towards a pro-inflammatory, neurotoxic profile. Special emphasis is placed on the detailed pathways and cellular interactions underpinning these dual roles. Additionally, the review examines the potential of microglial markers as diagnostic and prognostic indicators, offering insights into their clinical relevance. The article culminates in discussing future research directions, and the ongoing challenges in translating these findings into effective clinical applications. By providing a comprehensive overview of microglial mechanisms in autoimmune uveitis, this review underscores the critical balance of microglial activities and its implications for disease management and therapy development.

Single-Cell transcriptomes of immune cells provide insights into the therapeutic effects of mycophenolate mofetil on autoimmune uveitis

Mycophenolate mofetil (MMF) is an immunosuppressive agent widely applied in various autoimmune diseases, including autoimmune uveitis, a sight-threatening autoimmune disease mainly affecting the eyes. However, the mechanisms of action are not comprehensively understood. To investigate the potential impact of MMF on uveitis, we generated single-cell RNA sequence data from normal, experimental autoimmune uveitis (EAU) and MMF-treated EAU mice. We observed that some EAU-induced transcriptional changes were reversed by MMF treatment. Transcriptional data indicated that MMF may have a general inhibitory effect on the activation of immune cells during EAU. Each immune cell type showed a different response to MMF treatment. Pseudotime analysis showed that MMF treatment partly reversed the increased differentiation tendency from naïve to effector phenotypes of T and B cells in EAU. The reduced proportion of T-helper (Th)1 and T-helper (Th)17 cells after MMF treatment was confirmed using flow cytometry. MMF treatment downregulated the EAU-associated upregulation of several molecules (such as Cebpd, Pim1, Furin, Bhlhe40, and Hif1a) that promote pathogenic cytokine production by T helper (Th)-1 and Th17 cells. Abnormally enhanced immunoglobulin production, antigen processing, and presentation ability of B cells may also be inhibited by MMF treatment. In addition to T and B cells, MMF treatment countered EAU-induced transcriptional changes in other immune cells to different degrees. Overall, our findings provide novel insights into the mechanisms underlying MMF treatment and indicate that the therapeutic effect of MMF is not driven by a single molecule.

Tregs in Autoimmune Uveitis

Uveitis is a chronic disease with relapsing and remitting ocular attack, which requires corticosteroids and systemic immunosuppression to prevent severe vision loss. Classically, uveitis is referred to an autoimmune disease, mediated by pro-inflammatory Th17 cells and immunosuppressive CD4+CD25+FoxP3+ T-regulatory cells (Tregs). More and more evidence indicates that Tregs are involved in development, resolution, and remission of uveitis. Clinically, many researchers have conducted quantitative and functional analyses of peripheral blood from patients with different subtypes of uveitis, in an attempt to find the changing rules of Tregs. Consistently, using the experimental autoimmune uveitis (EAU) model, researchers have explored the development and resolution mechanism of uveitis in many aspects. In addition, many drug and Tregs therapy investigations have yielded encouraging results. In this chapter, we introduced the current understanding of Tregs, summarized the clinical changes in the number and function of patients with uveitis and the immune mechanism of Tregs involved in EAU model, as well as discussed the progress and shortcomings of Tregs-related drug therapy and Tregs therapy. Although the exact mechanism of Tregs-mediated uveitis protection remains to be elucidated, the strategy of Tregs regulation may provide a specific and meaningful way for the prevention and treatment of uveitis.

Inhibitory role of transforming growth factor β2 in experimental autoimmune anterior uveitis

PURPOSE

Experimental autoimmune anterior uveitis (EAAU) is a clinically relevant animal model for human idiopathic anterior uveitis (IAU). The role of the immunomodulator transforming growth factor β2 (TGF-β2) in EAAU pathology is unknown. In this study, we investigated the regulatory role of TGF-β2 in EAAU.

METHODS

EAAU was induced in male Lewis rats by footpad injection of melanin-associated antigen (MAA). TGF-β2 was administered intravenously (iv) in MAA-sensitized rats during the induction of EAAU, or after the clinical onset of uveitis. MAA-sensitized rats injected similarly with an equal volume of PBS served as control. Animals were examined daily between days 7 and 30 post-injection for the clinical signs of uveitis using slit lamp biomicroscopy. Animals were sacrificed at various time points and eyes were harvested for histological analysis to assess the course and severity of inflammation. For histopathological analysis, paraffin sections of harvested eyes were stained with hematoxylin and eosin. Popliteal lymph nodes (LNs) were used for CD4⁺CD25⁺FoxP3⁺ T regulatory (Tregs) population analysis and for CD4⁺ T cell proliferation assay.

RESULTS

Administration of recombinant TGF-β2 during the early stages of EAAU prevented the induction of uveitis. Compared to PBS, the presence of TGF-β2 in the cell culture significantly (p < 0.05) inhibited the proliferation of CD4⁺ T cells in response to MAA. In MAA-sensitized Lewis rats, iv treatment with recombinant TGF-β2 resulted in significantly (p < 0.05) increased percentage of Tregs compared to animals treated similarly with PBS. Thus, TGF-β2 inhibited the induction of EAAU by inhibiting CD4⁺ T cell proliferation and increasing the number of Tregs. Injection of TGF-β2 in rats with active EAAU resulted in diminished disease activity. Unfortunately, this treatment did not lead to the early resolution of EAAU.

CONCLUSIONS

TGF-β2 plays a critical role in regulation of intraocular inflammation in EAAU. Findings reported in this study improve our understanding of immunopathology of IAU and suggest that recombinant TGF-β2 may be a promising therapeutic agent for human IAU.

T Helper 1 Cellular Immunity Toward Recoverin Is Enhanced in Patients With Active Autoimmune Retinopathy

Autoimmune retinopathy (AIR) causes rapidly progressive vision loss that is treatable but often is confused with other forms of retinal degeneration including retinitis pigmentosa (RP). Measurement of anti-retinal antibodies (ARA) by Western blot is a commonly used laboratory assay that supports the diagnosis yet does not reflect current disease activity. To search for better diagnostic indicators, this study was designed to compare immune biomarkers and responses toward the retinal protein, recoverin, between newly diagnosed AIR patients, slow progressing RP patients and healthy controls. All individuals had measurable anti-recoverin IgG and IgM antibodies by ELISA regardless of disease status or Western blot results. Many AIR patients had elevated anti-recoverin IgG1 levels and a strong cellular response toward recoverin dominated by IFNγ. RP patients and controls responded to recoverin with a lower IFNγ response that was balanced by IL-10 production. Both AIR and RP patients displayed lower levels of total peripheral blood mononuclear cells that were due to reductions of CD4⁺ T_H cells. A comparison of messenger RNA (mRNA) for immune-related genes in whole blood of AIR patients versus RP patients or controls indicated lower expression of ATG5 and PTPN22 and higher expression of several genes involved in T_H cell signaling/transcription and adhesion. These data indicate that an immune response toward recoverin is normal in humans, but that in AIR patients the balance shifts dramatically toward higher IFNγ production and cellular activation.

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.

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.

Complement Component C4 Regulates the Development of Experimental Autoimmune Uveitis through a T Cell-Intrinsic Mechanism

In addition to its conventional roles in the innate immune system, complement has been found to directly regulate T cells in the adaptive immune system. Complement components, including C3, C5, and factor D, are important in regulating T cell responses. However, whether complement component C4 is involved in regulating T cell responses remains unclear. In this study, we used a T cell-dependent model of autoimmunity, experimental autoimmune uveitis (EAU) to address this issue. We compared disease severity in wild-type (WT) and C4 knockout (KO) mice using indirect ophthalmoscopy, scanning laser ophthalmoscopy, spectral-domain optical coherence tomography, and histopathological analysis. We also explored the underlying mechanism by examining T cell responses in ex vivo antigen-specific recall assays and in in vitro T cell priming assays using bone marrow-derived dendritic cells, splenic dendritic cells, and T cells from WT or C4 KO mice. We found that C4 KO mice develop less severe retinal inflammation than WT mice in EAU and show reduced autoreactive T cell responses and decreased retinal T cell infiltration. We also found that T cells, but not dendritic cells, from C4 KO mice have impaired function. These results demonstrate a previously unknown role of C4 in regulating T cell responses, which affects the development of T cell-mediated autoimmunity, as exemplified by EAU. Our data could shed light on the pathogenesis of autoimmune uveitis in humans.

Imbalance of Th17/Treg cells in pathogenesis of patients with human leukocyte antigen B27 associated acute anterior uveitis

Th17 and regulatory T cells, involved in the pathogenesis of several autoimmune diseases, are new lineages of CD4+ T helper cells. However, the role of their imbalance in human leukocyte antigen B27-associated acute anterior uveitis has not been elucidated. In our study, the percentages of Th17 and Treg cells, their molecular markers and related factors in peripheral blood of patients and healthy controls were measured by flow cytometry, real-time RT-PCR and ELISA. We observed a remarkable increase of CD4+ and CD4+IL-17+ T cells in peripheral blood of patients compared to controls. The molecular markers and related factors of Th17 cell were also showed a distinct elevation. Interestingly, we observed an obvious decrease of CD4+CD25+Foxp3+ T cells and Foxp3 mRNA level in patients. The ratio of Th17/Treg in patients was dramatically higher than controls. Moreover, the ratio of Th17/Treg cells had a more significantly positive correlation with the disease activity score than Th17 cells whereas Treg cells had a negative correlation. Our findings demonstrated a distinct increase of Th17 cells and a significant decrease of Treg cells in patients compared to controls. The imbalance of Th17 and Treg cells may play a vital role in the pathogenesis of the disease.

The Equine CD4+ Lymphocyte Proteome

CD4+ T cells are key players in immunology and disease pathology, including relapsing autoimmune uveitis. Equine recurrent uveitis is the only spontaneous animal model for this disease in man. Knowledge about the CD4+ cell proteome is crucial for studies on possible changes in proteome expression of CD4+ effector cells in disease. For this purpose, we generated a reference dataset of the equine CD4+ cell proteome by sorting equine CD4+ lymphocytes followed by analysis of whole cell lysate as well as membrane protein fraction using mass spectrometry.

Treatment of refractory uveitis with adalimumab: a prospective multicenter study of 131 patients

OBJECTIVE

To evaluate adalimumab therapy in refractory uveitis.

DESIGN

Prospective case series.

PARTICIPANTS

A total of 131 patients with refractory uveitis and intolerance or failure to respond to prednisone and at least 1 other systemic immunosuppressive drug participated.

INTERVENTION

Patients received a 40 mg adalimumab subcutaneous injection every other week for 6 months. The associated immunosuppressants were tapered after administering 3 adalimumab injections (week 6).

MAIN OUTCOME MEASURES

Degree of anterior and posterior chamber inflammation (Standardization of Uveitis Nomenclature Working Group criteria), immunosuppression load (as defined by Nussenblatt et al), visual acuity (logarithm of the minimal angle of resolution [logMAR]), and macular thickness (optical coherence tomography).

RESULTS

There were 61 men and 70 women (mean age, 27.3 years). The most common causes were juvenile idiopathic arthritis in 39 patients, pars planitis in 16 patients, and Behçet's disease in 13 patients. Twenty-seven patients had uveitis of idiopathic origin. Inflammation in the anterior chamber was present in 82% of patients and in the vitreous cavity in 59% of patients. Anterior chamber inflammation and vitreous inflammation decreased significantly (P < 0.001) from a mean of 1.51 and 1.03 at baseline to 0.25 and 0.14, respectively, at 6 months. Macular thickness was 296 (102) μ at baseline versus 240 (36) μ at the 6-month visit (P < 0.001). Visual acuity improved by -0.3 logMAR in 32 of 150 eyes (21.3%) and worsened by +0.3 logMAR (-15 letters) in 5 eyes (3.3%). The dose of corticosteroids also decreased from 0.74 (3.50) to 0.20 (0.57) mg/kg/day (P < 0.001). Cystoid macular edema, which was present in 40 eyes at baseline, showed complete resolution in 28 eyes at 6 months. The mean suppression load decreased significantly (8.81 [5.05] vs 5.40 [4.43]; P < 0.001). Six months after the initiation of the study, 111 patients (85%) were able to reduce at least 50% of their baseline immunosuppression load. Only 9 patients (6.9%) had severe relapses during the 6 months of follow-up.

CONCLUSIONS

Adalimumab seems to be well tolerated and helpful in decreasing inflammatory activity in refractory uveitis and may reduce steroid requirement. Further controlled studies of adalimumab for uveitis are warranted.

Effects of AIN457, a fully human antibody to interleukin-17A, on psoriasis, rheumatoid arthritis, and uveitis

Interleukin-17A (IL-17A) is elaborated by the T helper 17 (T(H)17) subset of T(H) cells and exhibits potent proinflammatory properties in animal models of autoimmunity, including collagen-induced arthritis, experimental autoimmune encephalomyelitis, and experimental autoimmune uveitis. To determine whether IL-17A mediates human inflammatory diseases, we investigated the efficacy and safety of AIN457, a human antibody to IL-17A, in patients with psoriasis, rheumatoid arthritis, and chronic noninfectious uveitis. Patients with chronic plaque-type psoriasis (n = 36), rheumatoid arthritis (n = 52), or chronic noninfectious uveitis (n = 16) were enrolled in clinical trials to evaluate the effects of neutralizing IL-17A by AIN457 at doses of 3 to 10 mg/kg, given intravenously. We evaluated efficacy by measuring the psoriasis area and severity index (PASI), the American College of Rheumatology 20% response (ACR20) for rheumatoid arthritis, or the number of responders for uveitis, as defined by either vision improvement or reduction in ocular inflammation or corticosteroid dose. AIN457 treatment induced clinically relevant responses of variable magnitude in patients suffering from each of these diverse immune-mediated diseases. Variable response rates may be due to heterogeneity in small patient populations, differential pathogenic roles of IL-17A in these diseases, and the different involvement or activation of IL-17A-producing cells. The rates of adverse events, including infections, were similar in the AIN457 and placebo groups. These results support a role for IL-17A in the pathophysiology of diverse inflammatory diseases including psoriasis, rheumatoid arthritis, and noninfectious uveitis.

Activation of OX40 augments Th17 cytokine expression and antigen-specific uveitis

Uveitis is a major and common cause of visual disability. Recent studies have shown that Th17 cells are implicated in the pathogenesis of this serious intraocular disorder. Activated T cells express an inducible costimulatory molecule called OX40, and OX40 in turn promotes the activation and proliferation of these lymphocytes. Nevertheless, it is unclear whether OX40 plays a vital role in enhancing the effector function of Th17 cells as well as the severity of uveitis. In this study, we demonstrated an increase of OX40 transcription in ovalbumin-induced uveitis, whereas anti-OX40L antibody substantially inhibited the antigen-specific ocular inflammation. Next, results from flow cytometry showed that activated Th17 cells expressed OX40, and OX40-activating antibody significantly augmented the production of Th17 cytokines in vitro. To validate the impact of OX40 in vivo, we stimulated ovalbumin-specific T cells with the OX40-activating antibody. Compared to donor cells without OX40 activation, adoptive transfer of OX40-stimulated lymphocytes elicited more severe ocular inflammation. Furthermore, an interleukin-17-neutralizing antibody attenuated OX40-mediated uveitis. In conclusion, our findings suggest that activation of OX40 augments Th17 cell function and thereby contributes to ocular inflammation. This study thus enhances our knowledge of costimulatory molecule-mediated immunopathological mechanisms of uveitis and suggests a future therapeutic strategy to treat uveitis by the targeting of OX40.

Autoimmunity in retinal degeneration: autoimmune retinopathy and age-related macular degeneration

Autoantibody production is associated with a variety of ocular disorders, including autoimmune retinopathy (AIR) and age-related macular degeneration (AMD). A breakdown of immunologic tolerance (ocular immune privilege), including the blood-retinal barrier, anti-immune and anti-inflammatory proteins, and anterior chamber-associated immune deviation may play important roles in these disorders. Although the exact triggers for ocular autoimmunity are unknown, autoimmune targeting of retinal tissue is clearly associated with and may contribute to the pathogenesis of both AIR and AMD. Autoantibody production has long been associated with AIR, a collection of disorders that includes cancer-associated retinopathy, melanoma-associated retinopathy and non-paraneoplastic autoimmune retinopathy. A growing body of evidence indicates that AMD pathogenesis, too, involves ocular inflammation and autoimmunity. Identification and quantification of autoantibodies produced in patients with AIR and AMD may assist with diagnosis, prognosis, and choice of treatments. Animal models that allow investigation of ocular autoimmunity will also be needed to better understand the disease processes and to develop novel therapies. In this review we discuss ocular immune privilege and potential mechanisms of autoimmunity in the eye. We describe how autoimmunity relates to the pathogenesis of AIR and AMD. We explain how the antigen microarray technique is used to detect autoantibodies in patient serum samples, and discuss how current animal models for AMD can be used to investigate autoimmune pathogenesis. Finally, we outline unanswered questions and exciting areas of future study related to autoimmune retinal degeneration.

Cancer-Induced, Immune-Mediated Ocular Degenerations

The means whereby vision can be lost from a disease located distant from the eye include autoimmunity, with sensitization resulting from extraocular stimuli, a process illustrated here by the immunologic confusion caused by cancers. The uncontrolled proliferation of malignancies commonly involves the expression of components of the central nervous system, but a damaging loss of tolerance is rare. When autoimmunity does develop, organ-specific antigens are more often involved than the more generalized and widely disseminated common neuronal components. A focus upon a single antigen is typical of the immune-mediated paraneoplasia, a collection of syndromes identified by unusual antibody reactions. This review provides an outline of the immunologic trail that led to the recognition of autoimmunity in paraneoplastic ocular degenerations, how specific antibody reactions aid in diagnosis, and the possibility of including antibodies in modes for sight-saving intervention. 'Those who do not know history are destined to repeat it'.

CXCR4 but not CXCR7 is mainly implicated in ocular leukocyte trafficking during ovalbumin-induced acute uveitis

Uveitis is an inflammatory ocular disease characterized by the infiltration of T lymphocytes and other leukocytes into the eye. The recruitment of these inflammatory cells from systemic vasculature to ocular tissue is a well-coordinated multistep process including rolling, firm adhesion and transmigration. CXCL12 (SDF-1alpha) is an endothelial cell-derived cytokine interacting with CXCR4 and CXCR7, two chemokine receptors mainly expressed in T cells, neutrophils and monocytes. Recent studies have shown that CXCR4, CXCR7 and their ligand, CXCL12, are important for the regulation of leukocyte mobilization and trafficking. However, it is unclear whether these two chemokine receptors are implicated in the pathogenesis of uveitis. In this study, we used DO11.10 mice, whose CD4+ T cells are genetically engineered to react with ovalbumin (OVA), to investigate the role of CXCR4 and CXCR7 in an animal model of uveitis. Intravital microscopy revealed that intravitreal OVA challenge of DO11.10 mice caused the infiltration of both T cells and neutrophils. The invasion of these inflammatory cells coincided with the detection of transcriptional up-regulation of CXCR4 and CXCR7 in the eye. In addition, both real-time-PCR and immunohistochemistry revealed an enhanced expression of endothelial CXCL12. Furthermore, intraperitoneal injection of AMD3100 (a specific CXCR4 antagonist) significantly attenuated OVA-induced uveitis and CXCL12-mediated transwell migration. In contrast, intraperitoneal administration of CXCR7 neutralizing antibody did not significantly alter ocular infiltration of inflammatory cells caused by OVA challenge. Our data suggest that CXCR4 but not CXCR7 plays a critical role in antigen-induced ocular inflammation by facilitating leukocyte infiltration. This study not only enhances our knowledge of the immunopathological mechanism of uveitis but also provides a novel rationale to target CXCR4 as an anti-inflammatory strategy to treat uveitis.

Constitutive neuronal expression of the immune regulator, programmed death 1 (PD-1), identified during experimental autoimmune uveitis

PURPOSE

Programmed death-1 (PD-1) ligation downregulates active lymphocyte responses. The authors tested whether PD-1 or its ligands are expressed in the posterior segment during active intraocular inflammation.

METHODS

Experimental autoimmune uveitis (EAU) was induced using interphotoreceptor retinoid-binding protein (IRBP 161-180). Ocular inflammation was evaluated by histology and expression of PD-1 ligand tested by immunohistochemistry. PD-1 expression was evaluated by immunohistochemistry, RT-PCR, and Western immunoblotting.

RESULTS

Using immunohistochemistry, PD-1, but not its ligands, was constitutively expressed in retinal neurons of naive mouse retina. Both PD-1 and its ligands were observed, as expected, in sites of active inflammation.

CONCLUSIONS

PD-1 and its ligands were expressed in sites of active inflammation, in accordance with many other models of inflammatory disease. Surprisingly, PD-1, not previously described outside the immune system, was constitutively expressed in retinal neurons, raising the possibility that PD-1 signaling may be important for neuronal function in the absence of an inflammatory insult.

Interleukin-17 causes neutrophil mediated inflammation in ovalbumin-induced uveitis in DO11.10 mice

T cell-mediated uveitis is strongly associated with many systemic inflammatory disorders. Th17 cells are a novel T cell subset characterized by production of interleukin (IL)-17. In this study, we used DO11.10 mice to investigate the role of IL-17 in the pathogenesis of uveitis. CD4(+) T cells in DO11.10 mice are genetically engineered to react with ovalbumin (OVA). IL-17 expression was determined by real-time PCR and ELISPOT. Uveitis was induced by intravitreal injection of OVA, and ocular inflammation was evaluated by intravital microscopy. OVA challenge significantly induced IL-17 production by DO11.10 splenocytes in vitro. Next, we examined whether OVA challenge could elicit local inflammation and induce IL-17 in vivo. OVA elicited marked neutrophil-predominant inflammatory cell infiltration in the eyes. This leukocyte influx was mediated by CD4(+) lymphocytes as evidenced by significant inhibition of the ocular inflammation by CD4+ depleting antibody. Compared to control mice, OVA treatment induced IL-17 expression. Moreover, anti-IL-17 antibody markedly reduced OVA-mediated ocular inflammation. Finally, the neutralization of IL-17 attenuated ocular expression of CXCL2 and CXCL5, two cytokines which are chemotactic for neutrophils. Our study suggests that IL-17 is implicated in the pathogenesis of this T cell-mediated model of uveitis in part through neutrophil chemotaxis as a downstream effect of IL-17.

A DNA vaccine for multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a disease in which safety is of paramount importance when developing a potential therapeutic. Antigen-specific treatments provide a method for achieving efficacy while maintaining safety. DNA vaccines are one such form of treatment that have been tested in clinical trials

OBJECTIVE

To determine if a DNA vaccine is a viable method of antigen-specific treatment of MS.

RESULTS/CONCLUSION

Phase I and II trials of BHT-3009, a DNA vaccine encoding myelin basic protein, demonstrated that it was safe, well-tolerated, and caused antigen-specific immune tolerance. BHT-3009 showed efficacy in reducing brain lesion activity as well as clinical relapses in patients that were immunologically active at baseline. BHT-3009 is a promising therapy in development for MS, and may prove to be one of the first antigen-specific treatments for this disease.

Enolase autoantibodies and retinal function in multiple sclerosis patients

BACKGROUND

Electroretinographic (ERG) abnormalities have been reported in multiple sclerosis (MS), as well as the presence of circulating antiretinal antibodies. We and others have reported cases of impaired vision and diminished ERGs in MS patients with alpha-enolase autoantibodies. Anti-enolase antibodies have been implicated in autoimmune retinopathy. We performed this study to further explore the relationship between antiretinal antibodies and ERG changes in patients with MS.

METHODS

Patients with clinically definite MS and normal visual acuity were recruited for this study, along with healthy controls. All patients and controls had ERG testing done according to ISCEV standards. Patient and control sera were analyzed for the presence of antiretinal antibodies using Western blot and ELISA techniques, and HLA class II typing was performed using polymerase chain reaction.

RESULTS

We found a statistically significant difference between MS patients and controls in the rod-cone b-wave implicit time (p < 0.005). We found autoantibodies against alpha-enolase in 38% of MS patients and 11% of controls (p < 0.02). There was no statistically significant difference between ERG parameters of MS patients with alpha-enolase autoantibodies compared to those without alpha-enolase antibodies. Furthermore, the presence of alpha-enolase did not associate with a particular HLA haplotype.

CONCLUSIONS

Factors affecting the retina other than alpha-enolase antibodies may account for the delayed rod-cone b-wave implicit times observed in MS patients in this study. Anti-enolase antibodies are likely an epiphenomenon of autoimmune disease, and are not causing retinopathy in MS patients with normal visual acuity. However, the possibility of rare cases of patients with pathogenic alpha-enolase autoantibodies can not be excluded. The pathogenic contribution of these antibodies in MS patients with visual impairment deserves further investigation.

Increased CD40 ligand in patients with acute anterior uveitis

PURPOSE

The inflammatory response in acute anterior uveitis (AU) is believed to be primarily mediated by autoreactive T-cells. We wanted to evaluate whether the T-cell activation marker CD40 ligand is involved in the AU immunopathogenesis.

METHODS

We evaluated the expression of the CD40 ligand on CD4+ T-cells, CD8+ T-cells and CD19+ B-cells on peripheral blood mononuclear cells using flow cytometry in six patients with unilateral AU, six patients with monosymptomatic optic neuritis (ON) as inflammatory controls, and in six healthy controls. The ex vivo induction of the CD40 ligand on T-cells in patients and controls was also studied.

RESULTS

A significantly higher expression of the CD40 ligand on both CD4+ (p < 0.05) and CD8+ (p < 0.05) T-cells in patients with AU compared to ON patients and healthy controls was found. There was a significantly higher induction of the CD40 ligand on CD8+ T-cells in AU patients compared to ON patients and healthy controls (p < 0.01). No differences in the B-cell population were observed between the three groups.

CONCLUSION

Patients with AU had increased expression of the CD40 ligand on T-cells in the blood and expressed higher levels of the CD40 ligand when stimulated, compared to ophthalmological inflammatory controls and healthy controls. The data suggest that the CD40 ligand is involved in the development of AU.