Molecular Genetic Advances in Uveitis

Autoimmune Liver Disease Associated Uveitis: An Extrahepatic Manifestation or a Polyautoimmunity Phenomenon? Case Reports

PURPOSE

To report two cases of non-granulomatous unilateral anterior uveitis in two female patients associated with autoimmune liver diseases (ALD), emphasizing the possibility of this rare coexistence as a polyautoimmunity phenomenon.

CASE DESCRIPTIONS

Case 1: An 18-year-old female with a history of congenital renal hypoplasia and metabolic syndrome presented with anterior uveitis in OS and a history of jaundice, blood elevated hepatic enzymes, and cholangioresonance compatible with primary sclerosing cholangitis (PSC). Laboratory work-up for additional autoimmune and infective causes were within normal limits. Case 2: An 58-year-old female presented an episode of anterior uveitis in OD and a history of Sjögren syndrome diagnosed at the age of 53, primary biliary cholangitis (PBC), systemic sclerosis, Raynaud's phenomenon, bilateral sacroiliitis, and vitiligo, consistent with polyautoimmunity and multiple autoimmune syndrome.

CONCLUSIONS

Uveitis rarely coexists with ALD. However, it is essential to recognize the possibility of polyautoimmunity in patients presenting with ophthalmic manifestations and a previous diagnosis of ALD, such as PSC or PBC.

Causal inference between serum bilirubin levels and juvenile idiopathic arthritis-associated uveitis: A bidirectional Mendelian randomization study

Background

Several observational studies have suggested an association between low serum bilirubin levels and Behçet's disease uveitis. However, the causal inference between bilirubin level and juvenile idiopathic arthritis-associated uveitis (JIAU) remains ambiguous. We investigated the potential causal relationship between serum bilirubin levels and JIAU using a bidirectional two-sample Mendelian randomization (MR) framework.

Methods

We systemically integrated summary-level data from published large-scale genome-wide association studies on bilirubin level and JIAU in a Caucasian British population. To determine the causal effect of bilirubin level on JIAU, we constructed strong instrumental variables using 47 and 80 single-nucleotide polymorphisms (SNPs) specific to direct bilirubin and total bilirubin levels, respectively. For reverse causal inference, seven SNPs associated with JIAU were included in our study. Multiple complementary methods were further performed to evaluate the robustness of MR estimates.

Results

The inverse-variance weighted estimate did not show any significant causal associations of genetically predicted serum direct or total bilirubin level with the risk of JIAU (odds ratio [OR]: 1.010, 95% confidence interval [CI]: 0.750-1.359, p = 0.947; OR: 0.867, 95% CI: 0.688-1.093; p = 0.227, respectively). MR-Egger and weighted median methods also obtained similar associations. Additionally, the results of reverse MR analyses using JIAU as exposure showed no associations of genetically predicted risk of JIAU with serum bilirubin levels (p > 0.05). In sensitivity analysis, the causal estimate between serum bilirubin levels and JIAU did not differ when SNPs associated with possible confounders were omitted.

Conclusion

Genetic evidence from our bidirectional analysis did not support a causal association between serum bilirubin levels and JIAU risk in the Caucasian British population. Future large-scale studies should be conducted to validate these findings and explore any causal effects on the disease process.

Cytokines in Immune-mediated "Non-infectious" Uveitis

Uveitis is a significant cause of ocular morbidity and accounts for approximately 5 - 10% of visual impairments worldwide, particularly among the working-age population. Infections are the cause of ~ 50% cases of uveitis, but it has been suggested that infection might also be implicated in the pathogenesis of immune-mediated "non-infectious" uveitis. There is growing evidence that cytokines (i.e., interleukins, interferons, etc.) are key mediators of immune-mediated "non-infectious" uveitis. For example, activation of the interleukin-23/interleukin-17 signalling pathway is involved in immune-mediated "non-infectious" uveitis. Studies in animal models have been important in investigating the role of cytokines in uveitis. Recent studies of clinical samples from patients with uveitis have allowed the measurement of a considerable array of cytokines even from very small sample volumes (e.g., aqueous and vitreous humour). The identification of complex patterns of cytokines may contribute to a better understanding of their potential pathogenetic role in uveitis as well as to an improved diagnostic and therapeutic approach to treat these potentially blinding pathologies. This review provides further insights into the putative pathobiological role of cytokines in immune-mediated "non-infectious" uveitis.

A de novo missense mutation in MPP2 confers an increased risk of Vogt-Koyanagi-Harada disease as shown by trio-based whole-exome sequencing

Vogt-Koyanagi-Harada (VKH) disease is a leading cause of blindness in young and middle-aged people. However, the etiology of VKH disease remains unclear. Here, we performed the first trio-based whole-exome sequencing study, which enrolled 25 VKH patients and 50 controls, followed by a study of 2081 VKH patients from a Han Chinese population to uncover detrimental mutations. A total of 15 de novo mutations in VKH patients were identified, with one of the most important being the membrane palmitoylated protein 2 (MPP2) p.K315N (MPP2-N315) mutation. The MPP2-N315 mutation was highly deleterious according to bioinformatic predictions. Additionally, this mutation appears rare, being absent from the 1000 Genome Project and Genome Aggregation Database, and it is highly conserved in 10 species, including humans and mice. Subsequent studies showed that pathological phenotypes and retinal vascular leakage were aggravated in MPP2-N315 mutation knock-in or MPP2-N315 adeno-associated virus-treated mice with experimental autoimmune uveitis (EAU). In vitro, we used clustered regularly interspaced short palindromic repeats (CRISPR‒Cas9) gene editing technology to delete intrinsic MPP2 before overexpressing wild-type MPP2 or MPP2-N315. Levels of cytokines, such as IL-1β, IL-17E, and vascular endothelial growth factor A, were increased, and barrier function was destroyed in the MPP2-N315 mutant ARPE19 cells. Mechanistically, the MPP2-N315 mutation had a stronger ability to directly bind to ANXA2 than MPP2-K315, as shown by LC‒MS/MS and Co-IP, and resulted in activation of the ERK3/IL-17E pathway. Overall, our results demonstrated that the MPP2-K315N mutation may increase susceptibility to VKH disease.

Association of ZC3HAV1 single nucleotide polymorphisms with the susceptibility of Vogt-Koyanagi-Harada Disease

BACKGROUND

Polymorphisms of genes related to the immune response have been reported to confer susceptibility to Vogt-Koyanagi-Harada (VKH) disease. This study was carried out to determine whether zinc finger CCCH-type containing antiviral 1 (ZC3HAV1) and tripartite motif-containing protein 25 (TRIM25) genetic polymorphisms are associated with this disease.

METHODS

A total of 766 VKH patients and 909 healthy individuals were enrolled in this two-stage case-control study. Thirty-one tag single nucleotide polymorphisms (SNPs) of ZC3HAV1 and TRIM25 were genotyped by MassARRAY System and iPLEX Gold Genotyping Assay. Allele and genotype frequencies were analyzed by the χ² test or Fisher's exact test. Cochran-Mantel-Haenszel test was used to assess the pooled odds ratio (OR) in the combined study. A stratified analysis was performed in terms of the major clinical features of VKH disease.

RESULTS

We found a statistically significant increased frequency of the minor A allele of ZC3HAV1 rs7779972 (P = 1.50 × 10^- 4, pooled OR = 1.332, 95%CI = 1.149-1.545) in VKH disease as compared with controls by using the Cochran-Mantel-Haenszel test. The GG genotype of rs7779972 showed a protective association with VKH disease (P = 1.88 × 10^- 3, OR = 0.733, 95%CI = 0.602-0.892). There was no difference regarding the frequency of the remaining SNPs between VKH cases and controls (all P > 2.08 × 10^- 3). The stratified analysis showed no significant association of rs7779972 with the major clinical characteristics of VKH disease.

CONCLUSION

Our study indicated that the ZC3HAV1 variant rs7779972 might confer susceptibility to VKH disease in Han Chinese.

Integrated Transcriptome Analysis of Iris Tissues in Experimental Autoimmune Uveitis

Uveitis is a severe ocular inflammatory disease that affects the uvea and frequently results in visual impairment, even irreversible blindness. The current treatments for uveitis have exhibited adverse side effects. To find novel targets of this disease, we perform comparative transcriptome analysis using normal (n = 4) and experimental autoimmune uveitis (EAU) (n = 4) rat iris samples. We mainly focus on the expression profiles of mRNAs and long non-coding RNAs, and identify NOD-like receptor signaling pathway as the one that plays a key role in the pathological changes of the EAU irises. Our work demonstrates that the EAU iris transcriptome can be mined to uncover novel targetable pathways for uveitis. The molecules in NOD-like receptor signaling pathway could be novel therapeutic targets for autoimmune uveitis.

Meta-analysis of the genetic association between PTPN22, CTLA-4 variants and risk of uveitis

BACKGROUND

Though the risk of PTPN22, CTLA-4 genetic variants with uveitis have been developed, the combined results still remain uncertain and controversial.

OBJECTIVES

To perform a meta-analysis to estimate the precise association of PTPN22 (rs2488457, rs2476601) and CTLA-4 (rs231775, rs5742909, rs4553808, and rs3087243) polymorphisms with uveitis susceptibility.

METHOD

Five electronic databases (PubMed, Embase, Web of Science, CBM, CNKI) were systematically searched for relevant literature up to July 20, 2021. All statistical analysis were evaluated by STATA 12.0 software and R programming language.

RESULTS

Our meta-results indicated that PTPN22 rs2488457 conferred positive susceptibility to uveitis (OR=1.18, 95%CI=1.02-1.38, p=0.029). In stratified analysis by ethnicity, rs2488457 C allele had a growing tendency towards uveitis in Asian region (OR=1.21, 95%CI=1.00-1.45, p=0.046). For CTLA-4 rs231775, subgroup analysis based on ethnicity manifested a negative association among uveitis individuals in Africa region (OR=0.25, 95%CI=0.19-0.33, p<0.001). For CTLA-4 rs4553808, subgroup analysis by disease type revealed that GG genotype was associated with an elevated risk of Behcet's disease (OR=3.22, 95%CI=1.05-9.90, p=0.042).

CONCLUSIONS

Our research revealed that PTPN22 rs2488457 conferred strong susceptibility to uveitis in general, especially in Asian region. CTLA-4 rs231775 conveyed protection against uveitis in African populations and CTLA-4 rs4553808 displayed an increased risk of Behcet's disease.

Low Expression of YTH Domain-Containing 1 Promotes Microglial M1 Polarization by Reducing the Stability of Sirtuin 1 mRNA

The N6-methyladenosine (m6A) modification is the most abundant posttranscriptional mRNA modification in mammalian cells and is dynamically modulated by a series of "writers," "erasers," and "readers." Studies have shown that m6A affects RNA metabolism in terms of RNA processing, nuclear export, translation, and decay. However, the role of the m6A modification in retinal microglial activation remains unclear. Here, we analyzed the single-cell RNA sequencing data of retinal cells from mice with uveitis and found that the m6A-binding protein YTH domain-containing 1 (YTHDC1) was significantly downregulated in retinal microglia in the context of uveitis. Further studies showed that YTHDC1 deficiency resulted in M1 microglial polarization, an increased inflammatory response and the promotion of microglial migration. Mechanistically, YTHDC1 maintained sirtuin 1 (SIRT1) mRNA stability, which reduced signal transducer and activator of transcription 3 (STAT3) phosphorylation, thus inhibiting microglial M1 polarization. Collectively, our data show that YTHDC1 is critical for microglial inflammatory response regulation and can serve as a target for the development of therapeutics for autogenic immune diseases.

Immune Privilege: The Microbiome and Uveitis

Immune privilege (IP), a term introduced to explain the unpredicted acceptance of allogeneic grafts by the eye and the brain, is considered a unique property of these tissues. However, immune responses are modified by the tissue in which they occur, most of which possess IP to some degree. The eye therefore displays a spectrum of IP because it comprises several tissues. IP as originally conceived can only apply to the retina as it contains few tissue-resident bone-marrow derived myeloid cells and is immunologically shielded by a sophisticated barrier – an inner vascular and an outer epithelial barrier at the retinal pigment epithelium. The vascular barrier comprises the vascular endothelium and the glia limitans. Immune cells do not cross the blood-retinal barrier (BRB) despite two-way transport of interstitial fluid, governed by tissue oncotic pressure. The BRB, and the blood-brain barrier (BBB) mature in the neonatal period under signals from the expanding microbiome and by 18 months are fully established. However, the adult eye is susceptible to intraocular inflammation (uveitis; frequency ~200/100,000 population). Uveitis involving the retinal parenchyma (posterior uveitis, PU) breaches IP, while IP is essentially irrelevant in inflammation involving the ocular chambers, uveal tract and ocular coats (anterior/intermediate uveitis/sclerouveitis, AU). Infections cause ~50% cases of AU and PU but infection may also underlie the pathogenesis of immune-mediated “non-infectious” uveitis. Dysbiosis accompanies the commonest form, HLA-B27–associated AU, while latent infections underlie BRB breakdown in PU. This review considers the pathogenesis of uveitis in the context of IP, infection, environment, and the microbiome.

Epigenome-wide association study identifies Behçet's disease-associated methylation loci in Han Chinese

OBJECTIVE

The aetiology of Behçet's disease (BD), known as a systemic vasculitis, is not completely understood. Increasing evidence suggests that aberrant DNA methylation may contribute to the pathogenesis of BD. The aim of this epigenome-wide association study was to identify BD-associated methylation loci in Han Chinese.

METHODS

Genome-wide DNA methylation profiles were compared between 60 BD patients and 60 healthy controls using the Infinium Human Methylation 450 K Beadchip. BD-associated methylation loci were validated in 100 BD patients and 100 healthy controls by pyrosequencing. Gene expression and cytokine production was quantified by real-time PCR and ELISA.

RESULTS

A total of 4332 differentially methylated CpG sites were associated with BD. Five differentially methylated CpG sites (cg03546163, cg25114611, cg20228731, cg23261343 and cg14290576) revealed a significant hypomethylation status across four different genes (FKBP5, FLJ43663, RUNX2 and NFIL3) and were validated by pyrosequencing. Validation results showed that the most significant locus was located in the 5'UTR of FKBP5 (cg03546163, P = 3.81E-13). Four CpG sites with an aberrant methylation status, including cg03546163, cg25114611, cg23261343 and cg14290576, may serve as a diagnostic marker for BD (area under the receiver operating curve curve = 83.95%, 95% CI 78.20, 89.70%). A significantly inverse correlation was found between the degree of methylation at cg03546163 as well as cg25114611 and FKBP5 mRNA expression. Treatment with a demethylation agent, 5-Aza-2'-deoxycytidine resulted in an increase of FKBP5 mRNA expression and a stimulated IL-1β production.

CONCLUSION

Our findings suggest that aberrant DNA methylation, independently of previously known genetic variants, plays a vital role in the pathogenesis of BD.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, chictr.org.cn, ChiCTR-CCC-12002184.

Association of a CARD9 Gene Haplotype with Behcet's Disease in a Chinese Han Population

Purpose: To investigate the association of CARD9 gene polymorphisms with Behcet's disease (BD) and acute anterior uveitis (AAU) in a Chinese Han population.Methods: We performed a case-control association study in 480 patients with BD, 1151 patients with AAU and 1440 healthy controls. Six single nucleotide polymorphisms (SNPs) of CARD9 were genotyped, including rs4077515, rs11145769, rs59902911, rs9411205, rs4073153 and rs1135314.Results: None of the individual SNPs in the CARD9 gene showed an association with either BD or AAU. Haplotype analysis revealed a significant decrease of the frequency of a CARD9 gene haplotype CGCCA (rs4077515, rs11145769, rs59902911, rs9411205, rs4073153) in BD when compared to healthy controls (Pc = 0.012, OR = 0.585, 95%CI = 0.409 ~ 0.837). Haplotype analysis did not show an association between CARD9 and AAU.Conclusions: This study shows that a five-SNP haplotype of the CARD9 gene (CGCCA) may be a protective factor for BD with ocular involvement, but not for AAU.

Different Methylation of CpG-SNPs in Behcet's Disease

Purpose

We recently performed an Epigenome-Wide Association Studies (EWAS) study in Behcet's disease (BD) and identified various cytosine–phosphate–guanine (CpG) loci that were aberrantly methylated. In the current study, we wanted to investigate whether these sites contained genetic polymorphisms and whether the frequency of these polymorphisms was altered in BD.

Methods

A two-stage study was performed. The first stage involved 358 BD patients and 704 healthy controls to investigate genetic variants of 10 CpG-SNPs (rs10454134, rs176249, rs3808620, rs10176517, rs11247118, rs78016579, rs9461624, rs10492166, rs34929465, and rs6507921) using an iPLEX Gold genotyping assay and a Sequenom MassARRAY. In the second stage, an additional 172 independent BD patients and 330 healthy individuals are to confirm trends found in the first stage.

Results

A higher frequency of both the rs10454134 AG genotypes (p = 0.008, OR = 1.413, 95% CI = 1.094-1.826) and a lower GG genotype frequency (p = 0.003, OR = 0.630, 95% CI = 0.465-0.854) were found in BD patients compared to the controls in the first stage. However, after correcting for multiple comparisons, all associations identified in the first stage lost statistical significance. The frequencies of the other CpG-SNPs investigated were not different between BD patients and controls. The second stage was designed using an additional cohort to confirm the association with CpG-SNP, rs10454134. The data failed to confirm the association between this CpG-SNP and BD.

Conclusions

This study did not show an association between BD and CpG-SNPs in gene sites that were earlier shown to be aberrantly methylated.

Uveitis and Multiple Sclerosis: Potential Common Causal Mutations

Uveitis, defined as inflammation of the uveal tract of the eye, is a leading cause of blindness and visual impairment throughout the world. The etiology of uveitis is complex, and autoimmunity plays a major role in its pathogenesis. Intermediate uveitis (IU), a subtype of ocular inflammation, has been associated with systemic autoimmune disorders, specifically with multiple sclerosis (MS). This article reports a rare three-generation family with several members affected by IU (four siblings) and comorbid MS (two siblings fulfilling MS diagnostic criteria and a third sibling presenting some neurological symptoms). Based on the clinical findings, we captured and sequenced whole exomes of seven pedigree members (affected and unaffected). Using a recessive model of transmission with full penetrance, we applied genetic linkage analysis to define minimal critical regions (MCRs) in suggestive or nominal regions of linkage. In these MCRs, we defined functional (some pathogenic), novel, and rare mutations that segregated as homozygous in affected and heterozygous in unaffected family members. The genes harboring these mutations, including DGKI, TNFRSF10A, GNGT1, CPAMD8, and BAFF, which are expressed in both eye and brain tissues and/or are related to autoimmune diseases, provide new avenues to evaluate the inherited causes of these devastating autoimmune conditions.

Cytokines in uveitis

PURPOSE OF REVIEW

Increasing evidence supports Th17 cells as key mediators of ocular inflammatory disease. Cytokines that are important for the development and pathologic function of these cells are potential therapeutic targets in patients with immune mediated uveitis. This review provides an overview of these cytokines including recent insights about their roles in ocular inflammation from laboratory and clinical studies.

RECENT FINDINGS

Interleukin (IL)-6, IL-10, IL-17, IL-22, IL-23 and tumour necrosis factor-alpha (TNFα) are cytokines that have been examined for their functional role in uveitis and their relationship to pathologic Th17 cells. Studies in animal models, particularly in experimental autoimmune uveitis (EAU), have been instrumental in studying the role of these cytokines in disease pathogenesis. More recently, studies on aqueous, vitreous and serum from patients with uveitis using flow cytometry and multiplex ELISA bead-based methodologies have provided insights into the contribution of Th17 cells and the related cytokines in ocular inflammatory diseases. The central role of IL-23 in determining the pathologic Th17 fate has made it an effective therapeutic target in systemic diseases such as psoriasis and thereby an attractive potential target for patients with immune-mediated uveitis.

SUMMARY

Th17 cells, and their related cytokines, are important inflammatory mediators in autoimmune uveitis. Animal and human studies continue to provide new information to direct development of new cytokine-targeted therapies for patients with uveitis.

Association of human leukocyte antigen (HLA)-DQ and HLA-DQA1/DQB1 alleles with Vogt-Koyanagi-Harada disease: A systematic review and meta-analysis

OBJECTIVE

The aim of this study was to evaluate the association of human leukocyte antigen (HLA)-DQ and HLA-DQA1/DQB1 alleles with Vogt-Koyanagi-Harada (VKH), providing further evidences on the genetic background of this disease.

METHODS

A comprehensive literature search was conducted on the relationship of HLA-DQ and/or HLA-DQA1/DQB1 alleles with VKH through PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, VIP, and databases for grey literature. The last search was in October 2017. Pooled odds ratio (OR) with 95% confidence interval (95% CI) was calculated from extracted data to access the strength of the association between a genotype and VKH.

RESULTS

HLA-DQ4 was confirmed to increase the risk of VKH significantly (OR = 4.63, 95% CI: 1.74-12.31, P = .002), while HLA-DQ1 seemed to reduce VKH occurrence with OR = 0.32 (95% CI: 0.22-0.47, P < .00001). HLA-DQA1*0301-(OR = 4.52, 95% CI: 1.42-14.35, P = .01) and HLA-DQB1*0401-(OR = 23.12, 95% CI: 11.54-46.31, P < .00001) positive patients probably had a rising tendency to suffer from VKH. Alleles including HLA-DQA1*0103, 0401, 0501 and HLA-DQB1*0301, 0402, 0601, 0603 were significant protective genetic factors.

CONCLUSION

We concluded that HLA-DQ4 carriers had a higher risk of VKH and HLA-DQ1 seemed to be protective. People with positive HLA-DQA1*0301 and HLA-DQB1*0401 demonstrated to be more susceptible to VKH. HLA-DQA1*0103, 0401, 0501 and HLA-DQB1*0301, 0402, 0601, 0603 could be potential protectors.

Long-Term Efficacy and Safety of Interferon Alpha-2a in the Treatment of Chinese Patients with Behçet's Uveitis Not Responding to Conventional Therapy

PURPOSE

To investigate the long-term efficacy and safety of interferon alpha-2a (IFNα-2a) in Chinese patients with Behçet's uveitis (BU) refractory to conventional therapy.

METHODS

In a prospective observational cohort study, 127 patients were treated with an initial dosage of 3 million units per day in the first three months, followed by gradual tapering of the dose.

RESULTS

After 3 months of treatment, IFNα-2a was shown to be effective in 115 cases (91%). At the end of the 1-year follow-up, the frequency of ocular relapses decreased to 1.59 ± 1.68 per year (ranging 0-6) (p < 0.001), as compared to 5.09 ± 2.51 per year (ranging 3-15). Moreover, the frequency of oral ulcer relapses also decreased to 2.49 ± 1.84 per year (ranging 0-6) (p < 0.001), as compared to 8.20 ± 3.72 per year (ranging 2-10). Visual improvement or stability was observed in 32 patients (59%) in these 54 patients. During a mean follow-up of 11 months (range 3-33), the mean final VA (logMAR) had progressed from 1.0 logMAR to 0.8 logMAR in all treated patients.

CONCLUSIONS

Long-term low dose of IFNα-2a is useful in treating Chinese BU patients who do not respond adequately to conventional therapy.

The Association of Chemokine Gene Polymorphisms with VKH and Behcet's Disease in a Chinese Han Population

To investigate the association of chemokine gene polymorphisms and Behcet's disease (BD) and Vogt Koyanagi Harada (VKH) disease in a Chinese Han population. A case-control study was performed. Three hundred and seventy-one BD patients, 371 VKH disease patients, and 605 healthy controls were recruited to determine genetic variants of 26 SNPs in 12 chemokine genes with iPLEX Gold genotyping assay and Sequenom MassARRAY or TaqMan SNP assays. In this study, P_uncorr values showed a weak association of five SNPs of five genes in BD and three SNPs of three genes in VKH disease. However, after Bonferroni correction, the 26 investigated SNPs showed no significant differences in genetic variants, including genotype and allele frequencies, between BD or VKH disease patients and healthy individuals. Haplotype analysis for the chemokine genes showed a significant association with the TC haplotype of CXCL12 in VKH. Stratified gender analysis and genotype-phenotype analysis were conducted to analyze the association of the 26 SNPs of 12 chemokine genes with BD and VKH disease. However, no significant association was observed after Bonferroni correction. This study showed no association of 26 SNPs in 12 chemokine genes with both BD and VKH disease in a Chinese Han population.

Major review: Molecular genetics of primary open-angle glaucoma

Glaucoma is a leading cause of irreversible blindness worldwide. Primary open-angle glaucoma (POAG), the most common type, is a complex inherited disorder that is characterized by progressive retinal ganglion cell death, optic nerve head excavation, and visual field loss. The discovery of a large, and growing, number of genetic and chromosomal loci has been shown to contribute to POAG risk, which carry implications for disease pathogenesis. Differential gene expression analyses in glaucoma-affected tissues as well as animal models of POAG are enhancing our mechanistic understanding in this common, blinding disorder. In this review we summarize recent developments in POAG genetics and molecular genetics research.

Lack of association of C3 gene with uveitis: additional insights into the genetic profile of uveitis regarding complement pathway genes

Uveitis is a devastating ocular disease that causes blindness. Our previous studies have achieved great advancements in depicting the genetic profiles of uveitis regarding complement pathway genes. This study aimed to provide additional insights into this interest by testing the "central" factor of the complement system, C3 gene variants, in two uveitis entities. Eight haplotype-tagging SNPs of C3 gene were genotyped in 141 anterior uveitis (AU), 158 non-infectious intermediate and posterior uveitis (NIPU) and 293 controls. The results showed that none of the tagging SNPs had a significant association with uveitis (P > 0.05), either in the global uveitis or subtypes. Although rs428453 showed a nominal association with NIPU subtype in the recessive model (P = 0.042), the P value could not withstand the Bonferroni correction (P _corr > 0.05). Stratification analyses according to HLA-B27 status and correlation analysis still did not find any significant interactions or genetic markers regarding AU. Logistic regression analysis also revealed no gender-related epistatic effects of C3 on uveitis. Two haplotype blocks were defined across the C3 locus but neither of them was significantly associated with uveitis or subtypes. This study shows no significant association of the C3 gene with uveitis, suggesting C3 confers either no or limited risk for uveitis susceptibility.

Genetic analysis of innate immunity in Behcet's disease identifies an association with IL-37 and IL-18RAP

Interleukin-1 (IL-1) and the IL-1 receptor (IL-1R) family play an important role in the pathogenesis of inflammatory diseases. This study aimed to investigate the association between single nucleotide polymorphisms (SNP) of IL-1 and IL-1R family genes with Vogt-Koyanagi-Harada (VKH) and Behcet’s disease (BD) in Han Chinese. The case-control study was divided into two stages and included 419 VKH cases, 1063 BD cases and 1872 healthy controls. The MassARRAY platform (Sequenom), iPLEX Gold Assay and TaqMan SNP assays were used to score genotypes of 24 SNPs. The expression of IL-37 and IL-18Rap was measured by ELISA and real-time PCR in genotyped healthy individuals. A significantly lower frequency of the AG genotype, and a higher frequency of the GG genotype and G allele of IL-37/rs3811047 were observed in BD as compared to controls. AA genotype and A allele frequency of IL-18RAP/rs2058660 was significantly decreased in BD as compared to controls. Functional studies performed in healthy controls showed that rs3811047 AG genotype carriers had a higher IL-37 gene expression in peripheral blood mononuclear cells (PBMCs) than GG carriers. GG carriers showed a higher cytokine expression as compared to AG carriers. No association was detected between the tested SNPs and VKH.

Therapeutic effects of mesenchymal stem cells administered at later phase of recurrent experimental autoimmune uveitis

AIM

To test the therapeutic effects of delayed treatment of mesenchymal stem cells (MSCs) in recurrent experimental autoimmune uveitis (rEAU).

METHODS

The efficacy of different regimens of MSC administration in rEAU were tested by evaluation of clinical and pathological intraocular inflammation, as well as retinal structural and functional integrity using optical coherence tomography (OCT) and electroretinogram (ERG). The retinal sections were also immunostained with antibodies to glial fibrillary acidic protein (GFAP) and rhodopsin (RHO).

RESULTS

Delayed treatment of MSCs effectively alleviated the severity of intraocular inflammation with relative intact of outer retinal structure and function. Moreover, double therapies with longer interval led to an even better clinical evaluation, as well as a trend of decrease in relapse and amelioration of retinal function. MSC therapies also effectively reduced GFAP expression and increased RHO expression in the retina.

CONCLUSION

MSC administration can effectively treat developed diseases of rEAU, and multiple therapies can provide additional therapeutic benefits.

HLA-B27 Anterior Uveitis: Immunology and Immunopathology

Acute anterior uveitis (AAU) is the commonest type of uveitis and HLA-B27 AAU is the most frequently recognized type of acute anterior uveitis and anterior uveitis overall. Recent evidence indicates that acute anterior uveitis is a heterogenous disease, is polygenic and is frequently associated with the spondyloarthropathies (SpA). Studies of patients with AAU and animal models of disease indicate a role for innate immunity, the IL-23 cytokine pathway and exogenous factors, in the pathogenesis of both SpA and acute anterior uveitis. Recently described genetic associations cluster around immunologic pathways, including the IL-17 and IL-23 pathways, antigen processing and presentation, and lymphocyte development and activation. Patients with ankylosing spondylitis (AS) and AAU share other genetic markers, such as ERAP-1, which show strong evidence of gene-gene interaction and point to new mechanisms of disease pathogenesis. These observations have major implications for understanding the pathogenesis of HLA-B27 diseases, such as AAU, and may lead to the development of more specific therapy for AAU. Received 6 January 2016; revised 6 February 2016; accepted 18 February 2016; published online 31 May 2016.

Genetic Variations of NLR family genes in Behcet's Disease

This study aimed to investigate whether single nucleotide polymorphisms (SNPs) of five NLR family genes (NOD1, NOD2, NLRP1, NLRP3 and CIITA) are associated with Behcet’s disease (BD) in a Chinese Han population. The study was carried out in 950 BD patients and 1440 controls for 19 SNPs in the selected NLR genes. In the first-stage study, significantly decreased frequencies of the CIITA//rs12932187 C allele (Pc = 1.668E-02) and NOD1//rs2075818 G allele (Pc = 4.694E-02) were found in BD patients as compared to controls . After performing a second stage validation study and combination of data we confirmed the association of CIITA//rs12932187 and NOD1//rs2075818 with BD. In CIITA//rs12932187, the frequencies of the CC genotype and C allele were significantly lower in BD than in controls (Pc = 3.331E-06; Pc = 6.004E-07, respectively). In NOD1//rs2075818, the GG genotype and G allele showed significantly decreased frequencies in BD patients when compared to controls (Pc = 1.022E-02; Pc = 6.811E-05, respectively). Functional experiments showed that carriers with the CC genotype in CIITA//rs12932187 had a lower CIITA mRNA expression level and an enhanced IL-10 secretion as compared to GG and CG carriers. This study provides evidence that the CIITA and NOD1 gene are involved in the susceptibility to Behcet’s disease.