Gut microbial signatures and their functions in Behcet's uveitis and Vogt-Koyanagi-Harada disease.

BACKGROUND: A number of public metagenomic studies reveal an association between the gut microbiome and various immune-mediated diseases including Behcet's uveitis (BU) and Vogt-Koyanagi-Harada disease (VKH). Integrated-analysis and subsequent validation of these results could be a potentially powerful way to understand the microbial signatures and their functions in these two uveitis entities. METHODS: We integrated the sequencing data of our previous metagenomic studies on two major uveitis entities, BU and VKH as well as four other publicly available immune-mediated diseases datasets, including Ankylosing Spondylitis (AS), Rheumatoid Arthritis (RA), Crohn's disease (CD) and Ulcerative Colitis (UC). Alpha-diversity and beta-diversity analysis were used to compare the gut microbiome signatures between both uveitis entities and other immune-mediated diseases and healthy controls. Amino acid homology between microbial proteins and a uveitogenic peptide of the interphotoreceptor retinoid-binding protein (IRBP)161-180 was investigated using a similarity search in the NCBI protein BLAST program (BLASTP). Enzyme-linked Immunosorbent Assay (ELISA) was performed to evaluate the cross-reactive responses of experimental autoimmune uveitis (EAU)-derived lymphocytes and BU patients-derived peripheral blood mononuclear cells (PBMCs) against homologous peptides. The area under the curve (AUC) analysis was used to test the sensitivity and specificity of gut microbial biomarkers. RESULTS: Depleted Dorea, Blautia, Coprococcus, Erysipelotrichaceae and Lachnospiraceae as well as enriched Bilophila and Stenotrophomonas were identified in BU patients. An enriched Alistipes along with a lower level of Dorea were observed in VKH patients. A peptide antigen (SteTDR) encoded by BU specifically enriched Stenotrophomonas was identified to share homology with IRBP161-180. In vitro experiments showed that lymphocytes from EAU or PBMCs from BU patients reacted to this peptide antigen as shown by the production of IFN-γ and IL-17. Addition of the SteTDR peptide to the classical IRBP immunization protocol exacerbated EAU severity. Gut microbial marker profiles consisted of 24 species and 32 species respectively differentiated BU and VKH from each other as well as from the other four immune-mediated diseases and healthy controls. Protein annotation identified 148 and 119 specific microbial proteins associated with BU and VKH, respectively. For metabolic function analysis, 108 and 178 metabolic pathways were shown to be associated with BU and VKH, respectively. CONCLUSIONS: Our study revealed specific gut microbial signatures and their potentially functional roles in BU and VKH pathogenesis that differ significantly from other immune-mediated diseases as well as healthy controls.

NLRP3 Attenuates Intraocular Inflammation by Inhibiting AIM2-Mediated Pyroptosis Through the Phosphorylated Salt-Inducible Kinase 1/Sterol Regulatory Element Binding Transcription Factor 1 Pathway.

OBJECTIVE: The NLRP3 inflammasome has been shown to be involved in the development of uveitis, but the exact mechanism remains elusive. This study was undertaken to explore the role of NLRP3 in the development of uveitis. METHODS: First, Nlrp3-deficient mice were used to study the role of NLRP3 in experimental autoimmune diseases, such as experimental autoimmune uveitis (EAU) and experimental autoimmune encephalomyelitis (EAE). Next, the gathering of ASC, activation of caspase 1 and gasdermin D, and secretion of lactate dehydrogenase and interleukin-1ß were detected to confirm macrophage pyroptosis and AIM2 activation in the Nlrp3-/- mice. Additionally, RNA sequencing and chromatin immunoprecipitation-polymerase chain reaction were used to investigate the phosphorylated salt-inducible kinase 1 (p-SIK1)/sterol regulatory element binding transcription factor 1 (SREBF1) pathway, which regulates the transcription of Aim2. Finally, overexpression of Nlrp3 was applied to treat EAU. RESULTS: Surprisingly, our findings show that NLRP3 plays an antiinflammatory role in 2 models of EAU and EAE. Additionally, macrophages show an increased M1 activation and pyroptosis in Nlrp3-/- mice. Further experiments indicate that this pyroptosis of macrophages was mediated by the up-regulated transcription of Aim2 as a result of Nlrp3 deficiency. In mechanistic studies, Nlrp3 deficiency was implicated in the down-regulation of p-SIK1 and subsequently the up-regulation of SREBF1, which binds to Aim2 and then promotes the latter's transcription. Finally, Aim2 deficiency, RNA silencing of Aim2 or Srebf1, and overexpression of Nlrp3 resulted in attenuated inflammation of EAU. CONCLUSION: Our data demonstrate that NLRP3 inhibits AIM2 inflammasome-mediated EAU by regulating the p-SIK1/SREBF1 pathway, highlighting the therapeutic potential of targeting Nlrp3.

Identification of differently expressed mRNAs by peripheral blood mononuclear cells in Vogt-Koyanagi-Harada disease.

Vogt-Koyanagi-Harada disease (VKH) is a rare autoimmune disease characterized by diffuse and bilateral uveitis, alopecia, tinnitus, hearing loss, vitiligo and headache. The transcriptional expression pattern of peripheral blood mononuclear cells (PBMC) in VKH remains largely unknown. In this study, mRNA sequencing was conducted in PBMC from VKH patients with active uveitis before treatment (n = 7), the same patients after prednisone combined with cyclosporine treatment (n = 7) and healthy control subjects strictly matched with gender and age (n = 7). We found 118 differentially expressed genes (DEGs) between VKH patients and healthy control subjects, and 21 DEGs between VKH patients before and after treatment. TRIB1 was selected as a potential biomarker to monitor the development of VKH according to the mRNA sequencing. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to predict the possible biological functions and signaling pathways of DEGs. Neutrophil degranulation, peptidase regulator activity, secretory granule membrane, cellular response to peptide, growth factor binding and cell projection membrane were enriched as GO annotations of DEGs. Arachidonic acid metabolism and mitogen-activated protein kinase (MAPK) signaling pathway were potential signaling pathways involved in pathogenesis and drug response of VKH. A protein-protein interaction (PPI) network was constructed by STRING, and colony stimulating factor 1 receptor (CSF1R) was identified as the hubgene of all DEGs by Cytoscape. The cell type presumed to contribute to the aberrant expression of DEGs was analyzed with the use of publicly available single-cell sequencing data of PBMC from a healthy donor and single-cell sequencing dataset of monocytes from VKH patients. Our findings may help to decipher the underlying cellular and molecular pathogenesis of VKH and may lead novel therapeutic applications.

Genetically predicted fasting blood glucose level plays a causal role in intraocular pressure: A Mendelian randomisation study.

BACKGROUND: This study aimed to examine possible causal associations between various components of metabolic syndrome and glaucoma-related phenotypes. METHODS: A two-sample Mendelian randomisation study was conducted with the models of inverse-variance weighted (IVW), maximum likelihood, weighted median and MR-Egger regression. We accessed data from publicly available genome-wide association studies for individual parameters of metabolic syndrome as the exposures and the data for glaucoma and its endophenotypes as the outcomes. RESULTS: Among 11 exposures and 6 outcomes examined in this Mendelian randomisation study, only fasting blood glucose level showed evidence of a causal influence on intraocular pressure. Results analysed by the IVW model suggested that each one-SD increase in genetically predicted fasting blood glucose level was significantly associated with 0.80 SD elevation in intraocular pressure (ß: 0.80, 95% CI: 0.38-1.22, p: 2.12e-4). The maximum likelihood model (ß: 0.82, 95% CI: 0.39-1.25, p: 1.616e-4) also supported a significant causal effect. The weighted median model (ß: 0.78, 95% CI: 0.17-1.39, p: 0.012) showed a nominally significant effect whereas the MR-Egger model (ß: 0.63, 95% CI: -0.32-1.59, p: 0.212) showed a consistent direction of effect but was not statistically significant. Several sensitivity analyses indicated no evidence of directional horizontal pleiotropy that would bias the result. CONCLUSIONS: This Mendelian randomisation study provides evidence for a causal role for genetically determined higher fasting blood glucose level in the development of increased intraocular pressure. This finding could be considered in the monitoring and control of intraocular pressure and may be instrumental in prevention strategies for ocular hypertension.

Association between temperature changes and uveitis onset in mainland China.

BACKGROUND: Some uveitis subtypes show seasonal patterns. Whether these patterns are caused by seasonally varying temperatures or by other climatic factors remains unknown. This ecological research aimed to quantify the association between climate variability and uveitis onset. METHODS: We combined data from the largest database of uveitis cases with surface climate data to construct panel data. We used choropleth maps to visually assess spatial uveitis variations. RESULTS: Among 12 721 reports of uveitis originating from 31 provinces of mainland China from 2006 to 2017, we found that a 1°C increase in monthly temperature was associated with a rise in approximately 2 uveitis reports per 1000 individuals (95% CI 0.00059 to 0.0029). This association was present across all provinces, ranging in effect size from 0.0011 to 0.072 (95% CI 0.00037 to 0.10). A clear 0-3 months of cumulative lagging effect was noted across all types of uveitis, with the strongest effect for non-infectious uveitis (0.0067, 95% CI 0.0041 to 0.013). Stratified by age and sex, we found that men and people aged 20-50 years were more affected by temperature variations. Our model predicts that China might experience an increase in uveitis cases due to future global warming. CONCLUSION: Our study is the largest-ever investigation of the association between uveitis and climate and, for the first time, provides evidence that rising temperature can affect large-scale uveitis onset. These results may help promote and implement policies to mitigate future temperature increases and the burden of disease caused by global warming.

Identification of Novel Risk Loci for Behçet's Disease-Related Uveitis in a Chinese Population in a Genome-Wide Association Study.

OBJECTIVE: To explore susceptibility loci associated with uveitis in Behçet's disease (BD). METHODS: We conducted a 2-stage study, consisting of a genome-wide association study (GWAS) stage and a replication stage, in a Chinese population. The GWAS stage included 978 cases with BD-related uveitis and 4,388 controls, and the replication stage included 953 cases with BD-related uveitis and 2,129 controls. Luciferase reporter analysis and chromatin immunoprecipitation assay were performed to explore the functional role of susceptibility genetic variants near ZMIZ1. RESULTS: Three independent HLA alleles (HLA-B51 [3.75 × 10-190 ], HLA-A26 [1.50 × 10-18 ], and HLA-C0704 [3.44 × 10-16 ]) were identified as having a genome-wide association with BD-related uveitis. In the non-HLA region, in addition to confirming 7 previously reported loci, we identified 22 novel susceptibility variants located in 16 loci. Meta-analysis of the Chinese cohort consisting of 1,931 cases and 6,517 controls and a published Japanese cohort of 611 cases and 737 controls showed genome-wide significant associations with ZMIZ1, RPS6KA4, IL10RA, SIPA1-FIBP-FOSL1, and VAMP1. Functional experiments demonstrated that genetic variants of ZMIZ1 were associated with enhanced transcription activity and increased expression of ZMIZ1. CONCLUSION: This GWAS study identified a novel set of genetic variants that are associated with susceptibility to uveitis in BD. These findings enrich our understanding of the contribution of genetic factors to the disease.

Development of revised diagnostic criteria for Fuchs' uveitis syndrome in a Chinese population.

BACKGROUND/AIMS: Fuchs' uveitis syndrome (FUS) is one of the frequently misdiagnosed uveitis entities, which is partly due to the absence of internationally recognised diagnostic criteria. This study was performed to develop and evaluate a set of revised diagnostic criteria for FUS. METHODS: The clinical data of Chinese patients with FUS and patients with non-FUS were collected and analysed from a tertiary referral centre between April 2008 and December 2020. A total of 593 patients with FUS and 625 patients with non-FUS from northern China were enrolled for the development of diagnostic criteria for FUS. Three hundred and seventy-seven patients with FUS and 503 patients with non-FUS from southern China were used to validate the criteria. Clinical symptoms and ocular signs were collected from all patients with FUS and patients with non-FUS. Multivariate two-step cluster analysis, logistic regression and decision tree algorithms in combination with the clinical judgement of uveitis experts were used to revise diagnostic criteria for FUS. RESULTS: Three essential findings including diffuse iris depigmentation, absence of posterior synechiae, mild inflammation in the anterior chamber at presentation and five associated findings including mostly unilateral involvement, cataract, vitreous opacities, absence of acute symptoms and characteristic iris nodules were used in the development of FUS diagnostic criteria. All essential findings were required for the diagnosis of FUS, and the diagnosis was further strengthened by the presence of associated findings. CONCLUSION: Revised diagnostic criteria for FUS were developed and validated by analysing data from Chinese patients and showed a high sensitivity (96.55%) and specificity (97.42%).

Association between Fine Particulate Air Pollution and the Onset of Uveitis in Mainland China.

PURPOSE: Although it has long been recognized that air pollution can affect the immune system and human ocular symptoms, it is uncertain whether air pollutants may also contribute to the development of uveitis. This study aimed to quantify the association of particulate matters less than 2.5 µm (PM2.5) with uveitis onset. METHODS: We combined monthly averages of PM2.5 concentrations, with data from the largest database of uveitis cases to assess the association between PM2.5 and uveitis onset. We further estimated the uveitis burden that was attributed to PM2.5 exposure and used choropleth maps to precisely characterize geographical variations. RESULTS: We found that a 10 µg/m3 increase in PM2.5 concentration was associated with a one-case per 10 individuals increase in uveitis onset across the dataset. Our results further suggest that PM2.5 concentrations above the level of the minimum exposure are responsible for 13% of novel uveitis cases in our cohort. Conclusion: These findings provide evidence supporting the association between fine particulate air pollution and uveitis onset.

Surveillance of Liver Function in Uveitis with or without Chronic HBV Infection.

INTRODUCTION: Immunosuppressive therapy for uveitis may cause liver damage. METHODS: To investigate incidence of liver damage during uveitis treatment, we compared serological Hepatitis B core antibody (HBcAb) status with risk of liver dysfunction in all participants (n = 992), in anterior uveitis (AU) (n = 489), and combined of intermediate, posterior, or panuveitis (IPPU) patients (n = 503). The primary endpoint was incidence of elevated serum alanine aminotransferase level above 2-fold upper limits of normal within 6 months. RESULTS: The incidence rate of primary endpoint for HBcAb-negative and HBcAb-positive patients was 65 and 212 per 1,000 person years, respectively. The absolute rate difference was 147 (95% confidence interval [CI], 80-213) per 1,000 person years. HBcAb positivity was associated with a higher risk for primary endpoint in all participants (adjusted hazard ratio [aHR], 3.53; 95% CI, 1.79-6.99; p value = 2.8 × 10-4) and in IPPU (aHR, 3.80; 95% CI, 1.61-9.01; p value = 0.002). No significant association with primary endpoint was observed for HBcAb positivity in AU (aHR, 3.21; 95% CI, 0.94-10.95; p value = 0.063). AU was mainly treated with topical eye drops (74.0%), whereas IPPU cases received systemic therapy including prednisone (94.0%), cyclosporine (80.9%), or other additionally combined immunomodulatory agents (14.9%). CONCLUSION: Noninfectious uveitis cases with HBcAb positivity have an increased risk of liver damage. This association was predominantly driven by IPPU but was not significant in AU, suggesting that the association is mediated by systemic therapy.

Trends in Corneal Transplantation and Characteristics of Donors in the Chongqing Eye Bank, China: A Retrospective Study, 1999-2018.

Aim: This study aimed to analyze corneal transplantation trends and voluntary donor characteristics at the Chongqing Eye Bank in China. Methods: We retrospectively reviewed and analyzed data from January 1, 1999, to December 31, 2018, covering 5,397 preregistered voluntary donors, 1,955 actual donors, 3,910 donated tissues, and 2,374 corneal transplantations. Results: The 5,397 preregistered donors included 13 ethnic groups, with an overall mean age of 39.6 years (SD 21.5) and 3,010 were women (55.8%). The most prevalent education level was college and above (2,546, 47.2%), and the most common ethnic group was Han (5,335, 98.85%). Of the 1,955 actual donors, the male-to-female ratio was 3.3, and the mean age was 57.1 (SD 23.0 years). Based on population size in 2018, Jiangbei county was the most active in donation willingness, with ~60 × 10-6 per capita, and the Yuzhong county was the most active in cornea donations, with ~451 × 0-6 per capita. Of the 3,910 donated corneas, 2,540 (65.0%) were clinically used. Of those not used, 978 (71.4%) were rejected for poor corneal quality. The 2,374 (93.5%) corneal transplantation procedures were done at the Department of Ophthalmology of the First Affiliated Hospital of Chongqing Medical University and the rest (n = 166, 6.5%) were performed in other centers. Of those 2,374 corneal transplantations, there were 1,671 penetrating keratoplasty (70.39%), 700 anterior lamellar keratoplasty (29.49%), and three corneal endothelial transplantations in our center (0.13%). The number of annual corneal transplantations increased by nearly 10 times, from 35 cases in 1999 to 327 cases in 2018. Among them, cases of penetrating keratoplasty and anterior lamellar keratoplasty increased from 27, and eight cases in 1999 to 230 and 94 cases in 2018, respectively. Infectious keratitis (37.0%) was the leading indication for keratoplasty, followed by corneal scar (19.8%). Over the study period, corneal scars dropped from the first (41.1% in 1999-2003) to the second indication (20.5% in 2014-2018), while infectious keratitis advanced to take the lead, ranging from 12.2% in 1999-2003 to 26.3% in 2014-2018. Conclusion: Our study reports corneal donation and transplantation trends in Chongqing over 20 years, showing that infectious keratitis is a leading indication for keratoplasty and that penetrating keratoplasty and anterior lamellar keratoplasty show upward trends. The analysis further suggests that a potential preregistered cornea donor is a female Han, with a higher education level.

SNP-mediated binding of TBX1 to the enhancer element of IL-10 reduces the risk of Behçet's disease.

Aims: The genetic association between Behçet's disease susceptibility and IL-10 has been confirmed in multiple cohorts, but the underlying mechanism of this association remains unclear. Materials & methods: We combined public resources and laboratory experiments (electrophoretic mobility shift assays, chromatin immunoprecipitation, luciferase reporter gene and CRISPR/Cas9 genome editing) to analyze transcription factor binding and enhancer activity controlling IL-10 expression. Results & conclusion: The T allele of noncoding rs3024490 within super-enhancer elements is able to specifically bind TBX1 and, in turn, promotes the enhancer activity and increased expression of IL-10. However, a relative deficiency in TBX1 in Behçet's disease patients leads to the low expression of IL-10 and increased risk of developing Behçet's disease.

Lay abstract Behçet's disease is a prominant cause of blindness. Previous reports show that genetic factors are linked with this disease, although the exact genetic mechanism is unclear. Many of these genetic factors are involved in the control of the immune response, including a large family of proteins known as cytokines. Some of the cytokines are proinflammatory while others can dampen the inflammatory response. An example of the latter is the IL-10 cytokine. We found that individuals carrying a specific site in the noncoding region of the IL-10 gene had a higher risk of Behçet's disease than other noncarriers. This study was designed to further investigate the biological mechanisms explaining the role of the specific site in the development of Behçet's disease. The results show that this specific site affects the binding of an important transcription factor, TBX1, which reduces IL-10 production. The dysregulated control of IL-10 explains why individuals with this genetic trait are more susceptible to developing Behçet's disease.

Changes in the Gut Microbiome Contribute to the Development of Behcet's Disease via Adjuvant Effects.

Behcet's disease (BD) is associated with considerable gut microbiome changes. However, it still remains unknown how the composition of the gut microbiome exactly affects the development of this disease. In this study, transplantation of stool samples from patients with active ocular BD to mice via oral gavage was performed. This resulted in decreases of three short chain fatty acids (SCFAs) including butyric acid, propionic acid and valeric acid in the feces of the BD-recipient group. Intestinal barrier integrity of mice receiving BD feces was damaged as shown by a decreased expression of tight junction proteins and was associated with the release of Lipopolysaccharides (LPS) in the circulation. The mice also showed a higher frequency of splenic neutrophils as well as an enrichment of genes associated with innate immune responses in the neutrophils and CD4 + T cells as identified by single cell RNA sequencing. Analysis of neutrophils and T cells functions in these mice showed an enhanced mesenteric lymph node and splenic Th1 and Th17 cell differentiation in association with activation of neutrophils. Transplantation of BD feces to mice and subsequent induction of experimental uveitis (EAU) or encephalomyelitis (EAE) led to an exacerbation of disease in both models, suggesting a microbial adjuvant effect. These findings suggest that the gut microbiome may regulate an autoimmune response via adjuvant effects including increased gut permeability and enhancement of innate immunity.

Specific sweat metabolite profile in ocular Behcet's disease.

BACKGROUND: Behcet's disease (BD) is an autoimmune disorder with the serious possibility of blindness, calling for further research on its pathogenesis. Our aim was to study the metabolite composition of sweat in BD and to identify possible biomarkers. METHODS: Metabolomics analysis was performed on sweat samples from 20 BD patients and 18 normal controls by liquid chromatography tandem mass spectrometry. RESULTS: A significantly different metabolic profile of sweat was observed when BD patients were compared with healthy controls. The result of the orthogonal partial least squared-discrimination analysis (OPLS-DA) showed that these two comparison groups could be separated with a relatively satisfactory fitting degree (R2Y = 0.995 and Q2 = 0.817 in positive ion mode; R2Y = 0.991 and Q2 = 0.721 in negative ion mode). Based on OPLS-DA, a panel of metabolites was selected as candidate biomarkers, including l-citrulline, l-pyroglutamic acid, urocanic acid, 2-oxoadipic acid, cholesterol 3-sulfate, and pentadecanoic acid. CONCLUSION: This is the first report on the metabolite profile of sweat in BD. Our results demonstrated a significantly different metabolite composition of sweat in BD compared to that of healthy controls.

High Ambient Temperature Aggravates Experimental Autoimmune Uveitis Symptoms.

Whether ambient temperature influences immune responses leading to uveitis is unknown. We thus tested whether ambient temperature affects the symptoms of experimental autoimmune uveitis (EAU) in mice and investigated possible mechanisms. C57BL/6 mice were kept at a normal (22°C) or high temperature (30°C) housing conditions for 2 weeks and were then immunized with human interphotoreceptor retinoid-binding protein (IRBP651-670) peptide to induce EAU. Histological changes were monitored to evaluate the severity of uveitis. Frequency of Th1 cells and Th17 cells was measured by flow cytometry (FCM). The expression of IFN-γ and IL-17A mRNA was measured by real-time qPCR. The generation of neutrophil extracellular traps (NETs) was quantified by enzyme-linked immunosorbent assay (ELISA). Differential metabolites in the plasma of the mice kept in the aforementioned two ambient temperatures were measured via ultra-high-performance liquid chromatography triple quadrupole mass spectrometry quadrupole time of flight mass spectrometry (UHPLC-QQQ/MS). The differential metabolites identified were used to evaluate their effects on differentiation of Th1 and Th17 cells and generation of NETs in vitro. The results showed that EAU mice kept at high temperature experienced a more severe histopathological manifestation of uveitis than mice kept at a normal temperature. A significantly increased frequency of Th1 and Th17 cells in association with an upregulated expression of IFN-γ and IL-17A mRNA was observed in the splenic lymphocytes and retinas of EAU mice in high temperature. The expression of NETs as evidenced by myeloperoxidase (MPO) and neutrophil elastase (NE), was significantly elevated in serum and supernatants of neutrophils from EAU mice kept at high temperature compared to the normal temperature group. The metabolites in the plasma from EAU mice, fumaric acid and succinic acid, were markedly increased in the high temperature group and could induce the generation of NETs via the NADPH oxidase-dependent pathway, but did not influence the frequency of Th1 and Th17 cells. Our findings suggest that an increased ambient temperature is a risk factor for the development of uveitis. This is associated with the induction of Th1 and Th17 cells as well as the generation of NETs which could be mediated by the NADPH oxidase-dependent pathway.

Metabolomic Analysis of Aqueous Humor Identifies Aberrant Amino Acid and Fatty Acid Metabolism in Vogt-Koyanagi-Harada and Behcet's Disease.

To investigate aqueous metabolic profiles in Vogt-Koyanagi-Harada (VKH) and Behcet's disease (BD), we applied ultra-high-performance liquid chromatography equipped with quadrupole time-of flight mass spectrometry in aqueous humor samples collected from these patients and controls. Metabolite levels in these three groups were analyzed by univariate logistic regression. The differential metabolites were subjected to subsequent pathway analysis by MetaboAnalyst. The results showed that both partial-least squares discrimination analysis and hierarchical clustering analysis showed specific aqueous metabolite profiles when comparing VKH, BD, and controls. There were 28 differential metabolites in VKH compared to controls and 29 differential metabolites in BD compared to controls. Amino acids and fatty acids were the two most abundant categories of differential metabolites. Furthermore, pathway enrichment analysis identified several perturbed pathways, including pantothenate and CoA biosynthesis when comparing VKH with the control group, and D-arginine and D-ornithine metabolism and phenylalanine metabolism when comparing BD with the control group. Aminoacyl-tRNA biosynthesis was altered in both VKH and BD when compared to controls. Our findings suggest that amino acids metabolism as well as two fatty acids, palmitic acid and oleic acid, may be involved in the pathogenesis of BD and VKH.

Identification of Urine Metabolic Biomarkers for Vogt-Koyanagi-Harada Disease.

The diagnosis of Vogt-Koyanagi-Harada (VKH) disease is mainly based on a complex clinical manifestation while it lacks objective laboratory biomarkers. To explore the potential molecular biomarkers for diagnosis and disease activity in VKH, we performed an untargeted urine metabolomics analysis by ultra-high-performance liquid chromatography equipped with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS). Through univariate and multivariate statistical analysis, we found 9 differential metabolites when comparing VKH patients with healthy controls, and 26 differential metabolites were identified when comparing active VKH patients with inactive VKH patients. Pathway enrichment analysis showed that glycine, serine and threonine metabolism, and arginine and proline metabolism were significantly altered in VKH versus healthy controls. Lysine degradation and biotin metabolism pathways were significantly altered in active VKH versus inactive VKH. Furthermore, the receiver operating characteristic (ROC) curve analysis revealed that the combination of acetylglycine and gamma-glutamylalanine could differentiate VKH from healthy controls with an area under the curve (AUC) of 0.808. A combination of ureidopropionic acid and 5'-phosphoribosyl-5-amino-4-imidazolecarboxamide (AICAR) had an excellent AUC of 0.958 for distinguishing active VKH from inactive VKH. In summary, this study identified abnormal metabolites in urine of patients with VKH disease. Further studies are needed to confirm whether these metabolites are specific for this disease.

Activation of the interleukin-23/interleukin-17 signalling pathway in autoinflammatory and autoimmune uveitis.

Uveitis is a group of diseases characterized by intraocular inflammation, of which some are driven by autoinflammatory or autoimmune responses, such as Vogt-Koyanagi-Harada disease, Behçet's disease, uveitis associated with spondyloarthritis, ocular sarcoidosis, sympathetic ophthalmia and birdshot chorioretinopathy. These entities have various clinical forms, but genetic and biomarker data suggest that they share a common molecular basis, activation of the Interleukin (IL)-23/IL-17 pathway. Multiple factors including genetic predisposition, various cytokine imbalances, infectious agents and gut alterations are found to trigger an aberrant response of this pathway. The enhanced activity of the IL-23/IL-17 pathway is committed to the expansion and pathogenicity of Th17 cells. Evidence from animal models demonstrates that the development of pathogenic Th17 cells is responsible for the induction of experimental autoimmune uveitis. Further findings indicate that retinal pigment epithelium (RPE) cells may be a target of IL-17. IL-17 triggers downstream inflammatory cascades and causes dysfunction of RPE cells, which may affect retinal barrier function and thereby promote intraocular inflammation. Currently, several emerging drugs blocking the IL-23/IL-17 pathway have been assessed for the treatment of uveitis in pilot studies. The purpose of this is to summarize updated biological knowledge and preliminary clinical data, providing the rationale for further development and evaluation of novel drugs targeting the IL-23/IL-17 pathway in autoinflammatory and autoimmune uveitis. Future studies may focus on translational medicine targeting the IL-23/IL-17 pathway for the improvement of diagnosis and treatment of uveitis. In conclusion, activation of the IL-23/IL-17 pathway is a critical biological event and can be an important target for the treatment of autoinflammatory and autoimmune uveitis.

The Rs12569232 SNP Association with Vogt-Koyanagi-Harada Disease and Behcet's Disease is Probably Mediated by Regulation of Linc00467 Expression.

Purpose: To investigate whether the rs12569232 SNP association with Vogt-Koyanagi-Harada disease and Behcet's disease is mediated by regulation of Linc00467 expression.Methods: The expression of linc00467 was detected by real-time PCR. Adenovirus carrying the linc00467 was transduced into CD4+T cells and the effect on cell viability was measured by the CCK-8 test. Human proteome microarray and starBase 2.0 were used to identify the binding proteins of linc00467 and RNA Immunoprecipitation (RIP) was used to confirm the identity of bound proteins.Results: The rs12569232 was associated with the expression of linc00467. The expression of linc00467 was up-regulated in PBMCs and CD4+T cells from VKH disease and BD patients. Over-expression of linc00467 increased cell viability of CD4+T cells. HUR was the common binding protein identified by the two methods and confirmed by RIP.Conclusions: The rs12569232 association with VKH disease and BD may be mediated via regulating the expression of linc00467.

Prevalence and clinical features of systemic diseases in Chinese patients with uveitis.

PURPOSE: Systemic diseases are frequently associated with uveitis but are often not recognised by clinicians. An estimate of the prevalence in a large-scale uveitis population is essential for understanding the epidemiological profile and may be helpful for clinical practice. DESIGN: A nationwide survey. METHODS: Data were obtained from a national database which included the registration of uveitis cases from 23 provinces, 5 autonomous regions and 4 municipalities across mainland China. The primary outcome was identification of a systemic disease associated with uveitis. RESULTS: From April 2008 through August 2018, 15 373 uveitis patients were included in the study. Males accounted for 52.9%, and the mean (SD) age of uveitis onset was 35.4 (15.9) years. After standardisation for age, the prevalence of systemic disease among patients with uveitis was 30.8% (95% CI, 30.1% to 31.6%). Vogt-Koyanagi-Harada disease (VKH; age-standardised prevalence, 12.7%; 95% CI, 12.1% to 13.2%), Behçet's disease (BD; 8.7%; 95% CI, 8.3% to 9.2%), ankylosing spondylitis (AS; 5.0%; 95% CI, 4.6% to 5.3%) and juvenile idiopathic arthritis (JIA; 1.2%; 95% CI, 1.0% to 1.3%) were the most common entities among 36 different forms of systemic diseases identified. The prevalence was significantly higher in males (37.0%; 95% CI, 36.0% to 38.1%) than in females (23.6%; 95% CI, 22.6% to 24.6%), and also higher in bilateral uveitis patients (41.2%; 95% CI, 40.2% to 42.2%) compared with unilateral cases (14.3%; 95% CI, 13.4% to 15.2%), and was highest in panuveitis (59.5%; 95% CI, 58.2% to 60.8%). CONCLUSION: Approximately one third of uveitis patients in this nationwide survey have an associated systemic disease, whereby VKH, BD, AS and JIA are the most frequent entities seen in China.

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.