Ultra-rare complement factor 8 coding variants in families with age-related macular degeneration

Genome-wide association studies have uncovered 52 independent common and rare variants across 34 genetic loci, which influence susceptibility to age related macular degeneration (AMD). Of the 5 AMD-associated complement genes, complement factor H (CFH) and CFI exhibit a significant rare variant burden implicating a major contribution of the complement pathway to disease pathology. However, the efforts for developing AMD therapy have been challenging as of yet. Here, we report the identification of ultra-rare variants in complement factors 8A and 8B, two components of the terminal complement membrane attack complex (MAC), by whole exome sequencing of a cohort of AMD families. The identified C8 variants impact local interactions among proteins of C8 triplex in vitro, indicating their effect on MAC stability. Our results suggest that MAC, and not the early steps of the complement pathway, might be a more effective target for designing treatments for AMD.

Axial spondyloarthritis patients have altered mucosal IgA response to oral and fecal microbiota

Axial spondyloarthritis (axSpA) is an inflammatory arthritis involving the spine and the sacroiliac joint with extra-articular manifestations in the eye, gut, and skin. The intestinal microbiota has been implicated as a central environmental component in the pathogenesis of various types of spondyloarthritis including axSpA. Additionally, alterations in the oral microbiota have been shown in various rheumatological conditions, such as rheumatoid arthritis (RA). Therefore, the aim of this study was to investigate whether axSpA patients have an altered immunoglobulin A (IgA) response in the gut and oral microbial communities. We performed 16S rRNA gene (16S) sequencing on IgA positive (IgA⁺) and IgA negative (IgA^-) fractions (IgA-SEQ) from feces (n=17 axSpA; n=14 healthy) and saliva (n=14 axSpA; n=12 healthy), as well as on IgA-unsorted fecal and salivary samples. PICRUSt2 was used to predict microbial metabolic potential in axSpA patients and healthy controls (HCs). IgA-SEQ analyses revealed enrichment of several microbes in the fecal (Akkermansia, Ruminococcaceae, Lachnospira) and salivary (Prevotellaceae, Actinobacillus) microbiome in axSpA patients as compared with HCs. Fecal microbiome from axSpA patients showed a tendency towards increased alpha diversity in IgA⁺ fraction and decreased diversity in IgA^- fraction in comparison with HCs, while the salivary microbiome exhibits a significant decrease in alpha diversity in both IgA⁺ and IgA^- fractions. Increased IgA coating of Clostridiales Family XIII in feces correlated with disease severity. Inferred metagenomic analysis suggests perturbation of metabolites and metabolic pathways for inflammation (oxidative stress, amino acid degradation) and metabolism (propanoate and butanoate) in axSpA patients. Analyses of fecal and salivary microbes from axSpA patients reveal distinct populations of immunoreactive microbes compared to HCs using the IgA-SEQ approach. These bacteria were not identified by comparing their relative abundance alone. Predictive metagenomic analysis revealed perturbation of metabolites/metabolic pathways in axSpA patients. Future studies on these immunoreactive microbes may lead to better understanding of the functional role of IgA in maintaining microbial structure and human health.

Identifying RNA Biomarkers and Molecular Pathways Involved in Multiple Subtypes of Uveitis

PURPOSE

Uveitis is a heterogeneous collection of diseases. We tested the hypothesis that despite the diversity of uveitides, there could be common mechanisms shared by multiple subtypes, and that evidence of these common mechanisms may be detected as gene expression profiles in whole blood.

DESIGN

Cohort study.

METHODS

Ninety subjects with uveitis including axial spondyloarthritis (n = 17), sarcoidosis (n = 13), inflammatory bowel disease (n = 12), tubulointerstitial nephritis with uveitis (n = 10), or idiopathic uveitis (n = 38) as well as 18 healthy controls were enrolled, predominantly at Oregon Health & Science University. RNA-Seq data generated from peripheral, whole blood identified 19,859 unique transcripts. We analyzed gene expression pathways via Kyoto Encyclopedia of Genes and Genomes and Gene Ontology (GO). We validated our list of upregulated genes by comparison to a previously published study on peripheral blood gene expression among 50 subjects with diverse forms of uveitis.

RESULTS

Both the Kyoto Encyclopedia of Genes and Genomes and GO analysis identified multiple shared pathways or GO terms with a P value of <.0001. Almost all pathways related to the immune response and/or response to an infection. A total of 119 individual transcripts were upregulated by at least 1.5-fold and false discovery rate <.05, and 61 were downregulated by similar criteria. Comparing mRNA from our study with a false discovery rate <.05 and the prior report, we identified 10 common gene transcripts: ICAM1, IL15RA, IL15, IRF1, IL10RB, GSK3A, TYK2, MEF2A, MEF2B, and MEF2D.

CONCLUSIONS

Many forms of uveitis share overlapping mechanisms. These data support the concept that a single therapeutic approach could benefit diverse forms of this disease.

The impact of genetic background and sex on the phenotype of IL-23 induced murine spondyloarthritis

BACKGROUND

Overexpression of IL-23 in adult mice by means of hydrodynamic tail vein injection of IL-23 minicircles has been reported to result in spondyloarthritis-like disease. The impact of genetic background and sex on the disease phenotype in this model has not been investigated.

METHODS

We compared male B10.RIII mice with male C57BL/6 mice, and male with female B10.RIII mice after hydrodynamic injection of IL-23 enhanced episomal vector (EEV) at 8-12 weeks of age. We monitored clinical arthritis scores, paw swelling, and body weight. Animals were euthanized after two weeks and tissues were harvested for histology, flow cytometry and gene expression analysis. Serum cytokine levels were determined by ELISA.

FINDINGS

Male B10.RIII mice developed arthritis in the forepaws and feet within 6 days after IL-23 EEV injection; they also exhibited psoriasis-like skin disease, colitis, weight loss, and osteopenia. In contrast to previous reports, we did not observe spondylitis or uveitis. Male C57BL/6 mice injected with IL-23 EEV had serum IL-23 levels comparable with B10.RIII mice and developed skin inflammation, colitis, weight loss, and osteopenia but failed to develop arthritis. Female B10.RIII mice had more severe arthritis than male B10.RIII mice but did not lose weight.

CONCLUSIONS

The phenotype of IL-23 induced disease in mice is controlled by genetic background and sex of the animals. The development of extra-articular manifestations but absence of arthritis in C57BL/6 mice suggests that organ-specificity of IL-23 driven inflammation is genetically determined. The mechanisms behind the strain-specific differences and the sexual dimorphism observed in this study may be relevant for human spondyloarthritis and warrant further exploration.

Revising the Diagnosis of Idiopathic Uveitis by Peripheral Blood Transcriptomics

PURPOSE

To test the hypothesis that idiopathic uveitis can be categorized into subtypes based on gene expression from blood.

DESIGN

Case control study.

METHODS

We applied RNA-Seq to peripheral blood from patients with uveitis associated with 1 of 4 systemic diseases, including axial spondyloarthritis (n = 17), sarcoidosis (n = 13), inflammatory bowel disease (n = 12), tubulo-interstitial nephritis with uveitis (n = 10), or idiopathic uveitis (n = 38) as well as 18 healthy control subjects evaluated predominantly at Oregon Health and Science University. A high-dimensional negative binomial regression model implemented in the edgeR R package compared each disease group with the control subjects. The 20 most distinctive genes for each diagnosis were extracted. Of 80 genes, there were 75 unique genes. A classification algorithm was developed by fitting a gradient boosting tree with 5-fold cross-validation. Messenger RNA from subjects with idiopathic uveitis were analyzed to see if any fit clinically and by gene expression pattern with one of the diagnosable entities.

RESULTS

For uveitis associated with a diagnosable systemic disease, gene expression profiling achieved an overall accuracy of 85% (balanced average of sensitivity plus specificity, P < .001). Although most patients with idiopathic uveitis presumably have none of these 4 associated systemic diseases, gene expression profiles helped to reclassify 11 of 38 subjects.

CONCLUSIONS

Peripheral blood gene expression profiling is a potential adjunct in accurate differential diagnosis of the cause of uveitis. Validation of these results and characterization of the gene expression profile from additional discrete diagnoses could enhance the value of these observations.

Genomewide Association Study of Acute Anterior Uveitis Identifies New Susceptibility Loci

Purpose

Acute anterior uveitis (AAU) is a common intraocular inflammatory disease. AAU occurs in 30% to 50% of patients with ankylosing spondylitis (AS), and both conditions are strongly associated with human leukocyte antigen (HLA)-B27, implying a shared etiology. This study aims to apply genomewide association study (GWAS) to characterize the genetic associations of AAU and their relationship to the genetics of AS.

Methods

We undertook the GWAS analyses in 2752 patients with AS with AAU (cases) and 3836 patients with AS without AAU (controls). There were 7,436,415 single-nucleotide polymorphisms (SNPs) available after SNP microarray genotyping, imputation, and quality-control filtering.

Results

We identified one locus associated with AAU at genomewide significance: rs9378248 (P = 2.69 × 10⁻⁸, odds ratio [OR] = 0.78), lying close to HLA-B. Suggestive association was observed at 11 additional loci, including previously reported AS loci ERAP1 (rs27529, P = 2.19 × 10⁻⁷, OR = 1.22) and NOS2 (rs2274894, P = 8.22 × 10⁻⁷, OR = 0.83). Multiple novel suggestive associations were also identified, including MERTK (rs10171979, P = 2.56 × 10⁻⁶, OR = 1.20), KIFAP3 (rs508063, P = 5.64 × 10⁻⁷, OR = 1.20), CLCN7 (rs67412457, P = 1.33 × 10⁻⁶, OR = 1.25), ACAA2 (rs9947182, P = 9.70 × 10⁻⁷, OR = 1.37), and 5 intergenic loci. The SNP-based heritability is approximately 0.5 for AS alone, and is much higher (approximately 0.7) for AS with AAU. Consistent with the high heritability, a genomewide polygenic risk score shows strong power in identifying individuals at high risk of either AS with AAU or AS alone.

Conclusions

We report here the first GWAS for AAU and identify new susceptibility loci. Our findings confirm the strong overlap in etiopathogenesis of AAU with AS, and also provide new insights into the genetic basis of AAU.

Radiologic imaging shows variable accuracy in diagnosing orbital inflammatory disease and assessing its activity

Radiologic orbital imaging provides important information in the diagnosis and management of orbital inflammation. However, the diagnostic value of orbital imaging is not well elucidated. This study aimed to investigate the diagnostic accuracy of orbital imaging to diagnose orbital inflammatory diseases and its ability to detect active inflammation. We collected 75 scans of 52 patients (49 computed tomography (CT) scans; 26 magnetic resonance (MR) imaging scans). Clinical diagnoses included thyroid eye disease (TED) (41 scans, 31 patients), non-specific orbital inflammation (NSOI) (22 scans, 14 patients), sarcoidosis (4 scans, 3 patients), IgG4-related ophthalmic disease (IgG4-ROD) (5 scans, 3 patients), and granulomatosis with polyangiitis (GPA) (3 scans, 1 patient). Two experienced neuroradiologists interpreted the scans, offered a most likely diagnosis, and assessed the activity of inflammation, blinded to clinical findings. The accuracy rate of radiological diagnosis compared to each clinical diagnosis was evaluated. Sensitivity and specificity in detecting active inflammation were analyzed for TED and NSOI. The accuracy rate of radiologic diagnosis was 80.0% for IgG4-ROD, 77.3% for NSOI, and 73.2% for TED. Orbital imaging could not diagnose sarcoidosis. Orbital CT had a sensitivity of 50.0% and a specificity of 75.0% to predict active TED using clinical assessment as the gold standard. The sensitivity/specificity of orbital MR was 83.3/16.7% for the detection of active NSOI. In conclusion, orbital imaging is accurate for the diagnosis of IgG4, NSOI, and TED. Further studies with a large number of cases are needed to confirm this finding, especially with regard to uncommon diseases. Orbital CT showed moderate sensitivity and good specificity for identifying active TED.

Expression of Cytokines in Porcine Iris, Retina and Choroidal Tissues Stimulated by Microbe-associated Molecular Patterns

PURPOSE

The innate immune system is strongly implicated in the pathogenesis of uveitis. This study was designed to clarify the responses of the innate immune system in uveal tissues.

MATERIALS AND METHODS

We utilized quantitative, real-time RT-PCR to measure mRNA of innate immune system receptors from porcine iris, choroid, and retina tissues. We used RT-PCR for cytokines to evaluate the responses of these tissues to specific ligands or extracts of whole bacteria that activate the innate immune system. We used ELISA for IL-6 on selected choroidal supernatants to confirm that the mRNA measurement correlated with protein levels.

RESULTS

In each of the studied tissues, we detected the expression of important receptors belonging to the innate immune system including dectin-1, TLR4, TLR8, and NOD2. Relative mRNA expression was generally lower in the retina compared to iris or choroid. All three tissues demonstrated upregulation of cytokine mRNA in response to a range of ligands that activate the innate immune system. The measurement of IL-6 protein was consistent with results based on mRNA. Notably, the expression of mRNA for IL-23 was more pronounced than IL-12 in all three tissues after stimulation with various innate immune system ligands.

CONCLUSIONS

These data provide evidence of a potent innate immune response intrinsic to uveal tissues. Specific innate immune system ligands as well as bacterial extracts enhanced the production of several inflammatory cytokines. Furthermore, the observation of higher upregulation of IL-23 mRNA, compared to IL-12 in response to innate immune stimuli, suggested that a local TH17 response might be more robust than a local TH1 response in uveal tissues. Our results expand the understanding as to how the innate immune system may contribute to uveitis.

HLA Alleles Associated With Risk of Ankylosing Spondylitis and Rheumatoid Arthritis Influence the Gut Microbiome

OBJECTIVE

HLA alleles affect susceptibility to more than 100 diseases, but the mechanisms that account for these genotype-disease associations are largely unknown. HLA alleles strongly influence predisposition to ankylosing spondylitis (AS) and rheumatoid arthritis (RA). Both AS and RA patients have discrete intestinal and fecal microbiome signatures. Whether these changes are the cause or consequence of the diseases themselves is unclear. To distinguish these possibilities, we examined the effect of HLA-B27 and HLA-DRB1 RA risk alleles on the composition of the intestinal microbiome in healthy individuals.

METHODS

Five hundred sixty-eight stool and biopsy samples from 6 intestinal sites were collected from 107 healthy unrelated subjects, and stool samples were collected from 696 twin pairs from the TwinsUK cohort. Microbiome profiling was performed using sequencing of the 16S ribosomal RNA bacterial marker gene. All subjects were genotyped using the Illumina CoreExome SNP microarray, and HLA genotypes were imputed from these data.

RESULTS

Associations were observed between the overall microbial composition and both the HLA-B27 genotype and the HLA-DRB1 RA risk allele (P = 0.0002 and P = 0.00001, respectively). These associations were replicated using the stool samples from the TwinsUK cohort (P = 0.023 and P = 0.033, respectively).

CONCLUSION

This study shows that the changes in intestinal microbiome composition seen in AS and RA are at least partially due to effects of HLA-B27 and HLA-DRB1 on the gut microbiome. These findings support the hypothesis that HLA alleles operate to cause or increase the risk of these diseases through interaction with the intestinal microbiome and suggest that therapies targeting the microbiome may be effective in preventing or treating these diseases.

Prediction of in vitro and in vivo oestrogen receptor activity using hierarchical clustering

In this study, hierarchical clustering classification models were developed to predict in vitro and in vivo oestrogen receptor (ER) activity. Classification models were developed for binding, agonist, and antagonist in vitro ER activity and for mouse in vivo uterotrophic ER binding. In vitro classification models yielded balanced accuracies ranging from 0.65 to 0.85 for the external prediction set. In vivo ER classification models yielded balanced accuracies ranging from 0.72 to 0.83. If used as additional biological descriptors for in vivo models, in vitro scores were found to increase the prediction accuracy of in vivo ER models. If in vitro activity was used directly as a surrogate for in vivo activity, the results were poor (balanced accuracy ranged from 0.49 to 0.72). Under-sampling negative compounds in the training set was found to increase the coverage (fraction of chemicals which can be predicted) and increase prediction sensitivity.

MOAtox: A comprehensive mode of action and acute aquatic toxicity database for predictive model development

The mode of toxic action (MOA) has been recognized as a key determinant of chemical toxicity and as an alternative to chemical class-based predictive toxicity modeling. However, the development of quantitative structure activity relationship (QSAR) and other models has been limited by the availability of comprehensive high quality MOA and toxicity databases. The current study developed a dataset of MOA assignments for 1213 chemicals that included a diversity of metals, pesticides, and other organic compounds that encompassed six broad and 31 specific MOAs. MOA assignments were made using a combination of high confidence approaches that included international consensus classifications, QSAR predictions, and weight of evidence professional judgment based on an assessment of structure and literature information. A toxicity database of 674 acute values linked to chemical MOA was developed for fish and invertebrates. Additionally, species-specific measured or high confidence estimated acute values were developed for the four aquatic species with the most reported toxicity values: rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas), bluegill (Lepomis macrochirus), and the cladoceran (Daphnia magna). Measured acute toxicity values met strict standardization and quality assurance requirements. Toxicity values for chemicals with missing species-specific data were estimated using established interspecies correlation models and procedures (Web-ICE; http://epa.gov/ceampubl/fchain/webice/), with the highest confidence values selected. The resulting dataset of MOA assignments and paired toxicity values are provided in spreadsheet format as a comprehensive standardized dataset available for predictive aquatic toxicology model development.

Genetic dissection of acute anterior uveitis reveals similarities and differences in associations observed with ankylosing spondylitis

OBJECTIVE

To use high-density genotyping to investigate the genetic associations of acute anterior uveitis (AAU) in patients with and those without ankylosing spondylitis (AS).

METHODS

We genotyped samples from 1,711 patients with AAU (either primary or combined with AS), 2,339 AS patients without AAU, and 10,000 control subjects on an Illumina Immunochip Infinium microarray. We also used data for AS patients from previous genome-wide association studies to investigate the AS risk locus ANTXR2 for its putative effect in AAU. ANTXR2 expression in mouse eyes was investigated by real-time quantitative reverse transcription-polymerase chain reaction.

RESULTS

A comparison between all patients with AAU and healthy control subjects showed strong association over HLA-B, corresponding to the HLA-B27 tag single-nucleotide polymorphism rs116488202. The association of 3 non-major histocompatibility complex loci, IL23R, the intergenic region 2p15, and ERAP1, reached genome-wide significance (P < 5 × 10(-8)). Five loci harboring the immune-related genes IL10-IL19, IL18R1-IL1R1, IL6R, the chromosome 1q32 locus harboring KIF21B, as well as the eye-related gene EYS, were also associated, reaching a suggestive level of significance (P < 5 × 10(-6)). Several previously confirmed AS associations demonstrated significant differences in effect size between AS patients with AAU and AS patients without AAU. ANTXR2 expression varied across eye compartments.

CONCLUSION

These findings of both novel AAU-specific associations and associations shared with AS demonstrate overlapping but also distinct genetic susceptibility loci for AAU and AS. The associations in IL10 and IL18R1 are shared with inflammatory bowel disease, suggesting common etiologic pathways.

Comparison of global and mode of action-based models for aquatic toxicity

The ability to estimate aquatic toxicity is a critical need for ecological risk assessment and chemical regulation. The consensus in the literature is that mode of action (MOA) based toxicity models yield the most toxicologically meaningful and, theoretically, the most accurate results. In this study, a two-step prediction methodology was developed to estimate acute aquatic toxicity from molecular structure. In the first step, one-against-the-rest linear discriminant analysis (LDA) models were used to predict the MOA. The LDA models were able to predict the MOA with 85.8-88.8% accuracy for broad and specific MOAs, respectively. In the second step, a multiple linear regression (MLR) model corresponding to the predicted MOA was used to predict the acute aquatic toxicity value. The MOA-based approach was found to yield similar external prediction accuracy (r(2) = 0.529-0.632) to a single global MLR model (r(2) = 0.551-0.562) fit to the entire training set. Overall, the global hierarchical clustering approach yielded a higher combination of accuracy and prediction coverage (r(2) = 0.572, coverage = 99.3%) than the other approaches. Utilizing multiple two-dimensional chemical descriptors in MLR models yielded comparable results to using only the octanol-water partition coefficient (log K(ow)).

Rare and common variants in extracellular matrix gene Fibrillin 2 (FBN2) are associated with macular degeneration

Neurodegenerative diseases affecting the macula constitute a major cause of incurable vision loss and exhibit considerable clinical and genetic heterogeneity, from early-onset monogenic disease to multifactorial late-onset age-related macular degeneration (AMD). As part of our continued efforts to define genetic causes of macular degeneration, we performed whole exome sequencing in four individuals of a two-generation family with autosomal dominant maculopathy and identified a rare variant p.Glu1144Lys in Fibrillin 2 (FBN2), a glycoprotein of the elastin-rich extracellular matrix (ECM). Sanger sequencing validated the segregation of this variant in the complete pedigree, including two additional affected and one unaffected individual. Sequencing of 192 maculopathy patients revealed additional rare variants, predicted to disrupt FBN2 function. We then undertook additional studies to explore the relationship of FBN2 to macular disease. We show that FBN2 localizes to Bruch's membrane and its expression appears to be reduced in aging and AMD eyes, prompting us to examine its relationship with AMD. We detect suggestive association of a common FBN2 non-synonymous variant, rs154001 (p.Val965Ile) with AMD in 10 337 cases and 11 174 controls (OR = 1.10; P-value = 3.79 × 10(-5)). Thus, it appears that rare and common variants in a single gene--FBN2--can contribute to Mendelian and complex forms of macular degeneration. Our studies provide genetic evidence for a key role of elastin microfibers and Bruch's membrane in maintaining blood-retina homeostasis and establish the importance of studying orphan diseases for understanding more common clinical phenotypes.

Immunologic and genetic markers in patients with idiopathic ocular inflammation and a family history of inflammatory bowel disease

PURPOSE

To evaluate the prevalence of immunologic and genetic markers in patients with idiopathic ocular inflammation and a family history of inflammatory bowel disease.

DESIGN

Matched case-control study.

METHODS

Patients with a diagnosis of idiopathic ocular inflammation and family history of inflammatory bowel disease who did not have inflammatory bowel disease themselves were identified and matched to control patients with idiopathic ocular inflammation. Serum was evaluated for immunologic markers using Prometheus IBD Serology 7. Genomic DNA was analyzed for single nucleotide polymorphisms (SNP) of the NOD2 gene associated with Crohn disease.

RESULTS

Fifteen patients with idiopathic ocular inflammation and family history of inflammatory bowel disease were matched to 15 control patients based on age, sex, and race. Eight of 15 patients (53%) with a family history of inflammatory bowel disease had elevated p-ANCA antibody levels compared to 3 of 15 controls (20%) (1-sided P = .04) with a matched analysis odds ratio of 6.0 (1-sided P = .06). Four of 15 patients (27%) with family history of inflammatory bowel disease tested positive for immunologic markers predicting ulcerative colitis, while no control patients tested positive (1-sided P = .06). Carrier rates of NOD2 SNPs did not differ significantly between the test and control groups.

CONCLUSIONS

One-quarter of patients with idiopathic ocular inflammation and a family history of inflammatory bowel disease had immunologic markers predicting bowel disease, and one-half had elevated p-ANCA levels. Prometheus IBD Serology 7 may be useful in the evaluation of selected patients with unexplained uveitis.

Association of interleukin 23 receptor gene with sarcoidosis

Interleukin 23 receptor (IL23R) gene has been reported as a genetic factor strongly associated with inflammatory bowel disease, psoriasis, and ankylosing spondylitis. We investigated the association between IL23R gene single nucleotide polymorphisms (SNPs) and susceptibility to sarcoidosis, including the clinical manifestation of uveitis. Ninety-one sarcoidosis subjects (58 with and 33 without uveitis) and 104 healthy controls were genotyped for eleven IL23R SNPs. DNA was amplified using specific PCR primers and genotyped by denaturing HPLC and/or direct DNA sequencing. Case-control frequency comparisons were analyzed using Chi square test. Three IL23R SNPs, rs7517847 (intron 6), rs11465804 (intron 8), and rs11209026 (exon 9, c.1142G>A, p.Arg381Gln) were associated with sarcoidosis in our population (p<0.05): rs7517847 showed increased frequencies in sarcoidosis compared to controls, but rs11465804 and rs11209026 were decreased. Two of these SNPs were associated with the uveitis subgroup compared to controls: rs11465804 (0.9% vs. 7.2%, OR=0.11, P=0.013) and rs11209026 (1.8% vs. 7.3%, OR=0.23, P=0.038). This finding indicates the association of IL23R polymorphism with sarcoidosis, especially with sarcoid uveitis. IL23R may be a common susceptibility gene shared by several autoimmune disorders including inflammatory bowel disease, psoriasis, and ankylosing spondylitis and sarcoid uveitis.

An update on the genetics of HLA B27-associated acute anterior uveitis

The discovery of the association of HLA B27 with spondyloarthropathy led to more questions than answers about the role of this gene in disease susceptibility. The realization that HLA B27 was not responsible for all of the genetic effects helped to lay a foundation for further investigation into the genetics of uveitis. Over several decades, genetic findings have provided clues to advance the understanding of mechanisms of uveitis and to catalyze new research on diagnostics, animal models, and therapies. From the early candidate gene studies on immune mediators to the recent genome-wide investigations, much has been discovered. However, these discoveries have come with the caveat that a genetic finding does not automatically reveal the disease-relevant functional effect of the associated variant.

Gender and laterality affect recurrences of acute anterior uveitis

AIM

Acute anterior uveitis (AAU) associated with HLA-B27 or axial spondyloarthritis (axial SpA) is primarily unilateral and recurrent. We tested the hypotheses that disease laterality and gender affected recurrences of AAU.

METHODS

We studied 207 AAU subjects who were either HLA-B27 positive or had a verified history of axial SpA with documentation of the first uveitis episode. We recorded gender, laterality, duration, and time between episodes.

RESULTS

Of 207 subjects, 126 (60.9%) had axial spondyloarthritis. Of the 179 with known HLA-B27 status, 174 (97.2%) were HLA-B27 positive. The initial episode of AAU occurred slightly more often in the right eye, 109 (52.6%), than in the left, 91 (44.0%) or bilaterally, 7 (3.4%), but the difference between right and left was not significant (p=0.23). Interestingly, 69.4% of subsequent episodes occurred in the same eye affected previously (95% CI 59.3%, 78.3%, p=0.0001). In subjects with recurrent AAU, the probability of being disease-free for one year was 38.9% (95% CI 29.1%, 52.0%) using Kaplan-Meier estimates. Univariate analyses showed that male gender (p=0.03) and AAU which recurred in the same eye (p=0.04) was associated with a shorter time interval between episodes. Multivariate analysis by the Cox proportional hazards model showed similar results.

CONCLUSIONS

The initial episode of unilateral AAU associated with HLA-B27 or axial SpA randomly affects either eye. Subsequent episodes occur more often in the same eye previously affected. Male gender and history of unilateral AAU in the same eye are associated with a shortened time interval between relapses.

Sporadic Blau syndrome with onset of widespread granulomatous dermatitis in the newborn period

Blau syndrome is a dominantly inherited, chronic autoinflammatory disorder characterized by the clinical triad of granulomatous dermatitis, symmetric arthritis, and recurrent uveitis with onset below 4 years of age. It is caused by activating mutations in the nucleotide-binding oligomerization domain 2 (NOD2) gene, previously referred to as CARD15 gene. Noncaseating granulomas in affected tissues are the pathologic hallmark of the condition. We report the lifelong severe disease course in a 14-year-old Caucasian boy with sporadic Blau syndrome. Unusually, granulomatous dermatitis started in the first week of life. Whereas skin involvement faded away spontaneously in subsequent years, polyarthritis and anterior uveitis appeared in the second and third year of life respectively. Mutational analysis of the NOD2 gene revealed a missense mutation (R334W) previously detected in other Blau syndrome pedigrees. With this report, we would like to stress the rare possibility of Blau syndrome in generalized papular rashes of infancy and the importance of histopathologic study for clarification. The finding of early-onset widespread granulomatous dermatitis should prompt eye and joint examination in regular intervals and entail mutational analysis of the NOD2 gene.

Insights in to the pathogenesis of axial spondyloarthropathy based on gene expression profiles

Introduction

Axial spondyloarthropathy (SpA) is a group of inflammatory diseases, with ankylosing spondylitis as the prototype. SpA affects the axial skeleton, entheses, joints and, at times, the eyes. This study tested the hypothesis that SpA is characterized by a distinct pattern of gene expression in peripheral blood of affected individuals compared with healthy controls.

Methods

High-density, human GeneChip^® probe arrays were used to profile mRNA of peripheral blood cells from 18 subjects with SpA and 25 normal individuals. Samples were processed as two separate sets at different times (11 SpA + 12 control subjects in primary set (Set 1); 7 SpA+ 13 control subjects in the validation set (Set 2)). Blood samples were taken at a time when patients were not receiving systemic immunomodulatory therapy. Differential expression was defined as a 1.5-fold change with a q value < 5%. Gene ontology and pathway information were also studied.

Results

Signals from 134 probe sets (representing 95 known and 12 unknown gene transcripts) were consistently different from controls in both Sets 1 and 2. Included among these were transcripts for a group of 20 genes, such as interleukin-1 (IL-1) receptors 1 and 2, Nod-like receptor family, pyrin domain containing 2 (NLRP2), secretory leukocyte peptidase inhibitor (SLPI), secreted protein acidic and rich in cysteine (SPARC), and triggering receptor expressed on myeloid cells 1 (TREM-1) that are clearly related to the immune or inflammatory response and a group of 4 transcripts that have a strong role in bone remodeling.

Conclusions

Our observations are the first to implicate SPARC, SLPI, and NLRP2, a component of the innate immune system, in the pathogenesis of SpA. Our results also indicate a possible role for IL-1 and its receptors in SpA. In accord with the bone pathology component of SpA, we also found that expression levels of transcripts reflecting bone remodeling factors are also distinguishable in peripheral blood from patients with SpA versus controls. These results confirm some previously identified biomarkers implicated in the pathogenesis of SpA and also point to novel mediators in this disease.

Nucleotide oligomerization domain-2 interacts with 2'-5'-oligoadenylate synthetase type 2 and enhances RNase-L function in THP-1 cells

Nucleotide-binding and oligomerization domain-2 (NOD2) is an intracellular protein involved in innate immunity and linked to chronic inflammatory diseases in humans. Further characterization of the full spectrum of proteins capable of binding to NOD2 may provide new insights into its normal functioning as well as the mechanisms by which mutated forms cause disease. Using a proteomics approach to study human THP-1 cells, we have identified 2'-5'-oligoadenylate synthetase type 2 (OAS2), a dsRNA binding protein involved in the pathway that activates RNase-L, as a new binding partner for NOD2. The interaction was confirmed using over-expression of OAS2 and NOD2 in HEK cells. Further confirmation was obtained by detecting NOD2 in immunoprecipitates of endogenous OAS2 in THP-1 cells. Finally, over-expression of NOD2 in THP-1 cells led to enhanced RNase-L activity in cells treated with poly(I:C), a mimic of double-stranded RNA virus infection. These data indicate connectivity in pathways involved in innate immunity to bacteria and viruses and suggest a regulatory role whereby NOD2 enhances the function of RNase-L.

Killer cell immunoglobulin-like receptors in HLA-B27-associated acute anterior uveitis, with and without axial spondyloarthropathy

PURPOSE

To determine associations between polymorphic genes that encode KIRs and their HLA class I ligands in patients with HLA-B27-associated acute anterior uveitis (AAU), with and without axial spondyloarthropathy (axial SpA).

METHODS

Molecular DNA typing methods were used to define the frequencies of variable KIR genes and their relevant HLA class I ligands in HLA-B27(+) (B27(+)) Caucasian subjects with AAU and 429 healthy Caucasian control subjects. The patients were evaluated for axial SpA based on their histories using published criteria.

RESULTS

Of 143 Caucasian subjects with AAU, 71 (49.6%) had features of axial SpA. The only difference between cases and controls in KIR gene frequencies was a trend toward fewer activating KIRs in subjects with AAU with axial SpA, which reached statistical significance for 2DS5 (P = 0.025, corrected P [P(c)] = 0.05; odds ratio [OR], 0.48; 95% CI, 0.25-0.90). The 3DL1+Bw4(T80) combination implicated in weak inhibition was more frequent in subjects with AAU than in control subjects (P = 2.73 x 10(-28), P(c) = 8.2 x 10(-27); OR, 13.5; 95% CI, 7.73-23.68). The 2DL1+HLA-C2 combination was decreased in subjects with axial SpA compared with subjects with AAU without axial SpA (P = 0.022; P(c) = NS; OR, 0.43; 95% CI, 0.21-0.88).

CONCLUSIONS

Evidence was found of a role for KIR-HLA combinations that trigger weaker inhibition in subjects with AAU. Furthermore, there was a trend toward fewer KIR3DS1, -2DS1, and -2DS5 in AAU patients with axial SpA, which have been implicated in NK cell activation. HLA-B27(+) without KIR2DS3 (and -2DS1 and -3DS1) may fail to trigger an early NK cell response to clear antigenic stimuli, which may in part contribute to disease pathogenesis.

NOD2-associated pediatric granulomatous arthritis, an expanding phenotype: study of an international registry and a national cohort in Spain

OBJECTIVE

To study the phenotype characteristics of the largest to date cohort of patients with pediatric granulomatous arthritis (PGA) and documented mutations in the NOD2 gene.

METHODS

We analyzed merged data from 2 prospective cohorts of PGA patients, the International PGA Registry and a Spanish cohort. A systematic review of the medical records of interest was performed to identify phenotype characteristics.

RESULTS

Forty-five patients with PGA (23 sporadic cases and 22 from familial pedigrees) and documented NOD2 mutations were identified and formed the basis of the study. Of these 45 patients, 18 had the R334W-encoding mutation, 18 had R334Q, 4 had E383K, 3 had R587C, 1 had C495Y, and 1 had W490L. The majority of patients manifested the typical triad of dermatitis, uveitis, and arthritis. In contrast, in 13 patients, the following "atypical" manifestations were noted: fever, sialadenitis, lymphadenopathy, erythema nodosum, leukocytoclastic vasculitis, transient neuropathy, granulomatous glomerular and interstitial nephritis, interstitial lung disease, arterial hypertension, hypertrophic cardiomyopathy, pericarditis, pulmonary embolism, hepatic granulomatous infiltration, splenic involvement, and chronic renal failure. In addition, 4 individuals who were asymptomatic carriers of a disease-causing mutation were documented.

CONCLUSION

NOD2-associated PGA can be a multisystem disorder with significant visceral involvement. Treating physicians should be aware of the systemic nature of this condition, since some of these manifestations may entail long-term morbidity.

Predictive models for carcinogenicity and mutagenicity: frameworks, state-of-the-art, and perspectives

Mutagenicity and carcinogenicity are endpoints of major environmental and regulatory concern. These endpoints are also important targets for development of alternative methods for screening and prediction due to the large number of chemicals of potential concern and the tremendous cost (in time, money, animals) of rodent carcinogenicity bioassays. Both mutagenicity and carcinogenicity involve complex, cellular processes that are only partially understood. Advances in technologies and generation of new data will permit a much deeper understanding. In silico methods for predicting mutagenicity and rodent carcinogenicity based on chemical structural features, along with current mutagenicity and carcinogenicity data sets, have performed well for local prediction (i.e., within specific chemical classes), but are less successful for global prediction (i.e., for a broad range of chemicals). The predictivity of in silico methods can be improved by improving the quality of the data base and endpoints used for modelling. In particular, in vitro assays for clastogenicity need to be improved to reduce false positives (relative to rodent carcinogenicity) and to detect compounds that do not interact directly with DNA or have epigenetic activities. New assays emerging to complement or replace some of the standard assays include Vitotox, GreenScreenGC, and RadarScreen. The needs of industry and regulators to assess thousands of compounds necessitate the development of high-throughput assays combined with innovative data-mining and in silico methods. Various initiatives in this regard have begun, including CAESAR, OSIRIS, CHEMOMENTUM, CHEMPREDICT, OpenTox, EPAA, and ToxCast. In silico methods can be used for priority setting, mechanistic studies, and to estimate potency. Ultimately, such efforts should lead to improvements in application of in silico methods for predicting carcinogenicity to assist industry and regulators and to enhance protection of public health.

The NOD2 defect in Blau syndrome does not result in excess interleukin-1 activity

OBJECTIVE

Blau syndrome is a rare, autosomal-dominant, autoinflammatory disorder characterized by granulomatous arthritis, uveitis, and dermatitis. Genetics studies have shown that the disease is caused by single nonsynonymous substitutions in NOD-2, a member of the NOD-like receptor or NACHT-leucine-rich repeat (NLR) family of intracellular proteins. Several NLRs function in the innate immune system as sensors of pathogen components and participate in immune-mediated cellular responses via the caspase 1 inflammasome. Mutations in a gene related to NOD-2, NLRP3, are responsible for excess caspase 1-dependent interleukin-1beta (IL-1beta) in cryopyrinopathies such as Muckle-Wells syndrome. Furthermore, functional studies demonstrate that caspase 1-mediated release of IL-1beta also involves NOD-2. The aim of this study was to test the hypothesis that IL-1beta may mediate the inflammation seen in patients with Blau syndrome.

METHODS

IL-1beta release was measured in peripheral blood mononuclear cells cultured in vitro, obtained from 5 Blau syndrome individuals with a NOD2 (CARD15) mutation.

RESULTS

We observed no evidence for increased IL-1beta production in cells obtained from subjects with Blau syndrome compared with healthy control subjects. Furthermore, we presented 2 cases of Blau syndrome in which recombinant human IL-1 receptor antagonist (anakinra) was ineffective treatment.

CONCLUSION

Taken together, these data suggest that in contrast to related IL-1beta-dependent autoinflammatory cryopyrinopathies, Blau syndrome is not mediated by excess IL-1beta or other IL-1 activity.

Genotype analysis of polymorphisms in autoimmune susceptibility genes, CTLA-4 and PTPN22, in an acute anterior uveitis cohort

PURPOSE

Acute anterior uveitis (AAU) is the most common form of uveitis and is thought to be autoimmune in nature. Recent studies have described genes that act as master controllers of autoimmunity. Protein tyrosine phosphatase type 22 (PTPN22) and Cytotoxic T lymphocyte antigen-4 (CTLA-4) are two of these genes, and single nucleotide polymorphisms (SNPs) in the genes encoding these molecules have been associated with several autoimmune diseases. In this study we have analyzed SNPs in PTPN22 and CTLA-4 in patients with AAU.

METHODS

The functional protein tyrosine phosphatase type 22 (PTPN22) SNP (R620W rs2476601, 1858C/T), and two CTLA-4 SNPs (rs5742909, -318C/T and rs231775, 49A/G) were analyzed in 140 patients with AAU and 92 healthy controls by sequence-specific primer -polymerase chain reaction (SSP-PCR). Data was analyzed by chi(2) analysis and Fisher's exact test.

RESULTS

There was no significant association between PTPN22 620W, CTLA-4 -318C/T, or CTLA-4 49A/G and AAU. Similarly, there was no association with the three SNPs when patients were classified by race or gender. Finally, there was no association with the presence of ankylosing spondylitis in the patient cohort.

CONCLUSIONS

The data do not support an association between SNPs in PTPN22 and CTLA-4, genes regarded as genetic master switches of autoimmunity. This raises the issue of the etiology of AAU and the possibility that it should be regarded as an autoinflammatory rather than an autoimmune condition.

Activation of nucleotide oligomerization domain 2 exacerbates a murine model of proteoglycan-induced arthritis

In addition to its role in innate immunity, nucleotide oligomerization domain 2 (NOD2) has been shown to play a suppressive role in models of colitis. Notably, mutations in NOD2 cause the inherited granulomatous disease of the joints called Blau syndrome, thereby linking NOD2 with joint disease as well. However, the role of NOD2 in joint inflammation has not been clarified. We demonstrate here that NOD2 is functional within the mouse joint and promotes inflammation, as locally or systemically administered muramyl dipeptide (MDP; the NOD2 agonist) resulted in significant joint inflammation that was abolished in NOD2-deficient mice. We then sought to investigate the role of NOD2 in a mouse model of inflammatory arthritis dependent on adaptive immunity using TCR-transgenic mice whose T cells recognized the dominant epitope of proteoglycan (PG). Mice immunized with PG in the presence of MDP developed a more severe inflammatory arthritis and histopathology within the joints. Antigen-specific activation of splenocytes was enhanced by MDP with respect to IFN-gamma production, which would be consistent with the Th1-mediated disease in vivo. Intriguingly, NOD2 deficiency did not alter the PG-induced arthritis, indicating that NOD2 does not play an essential role in this model of joint disease when it is not activated by MDP. In conclusion, we demonstrate that in a model of inflammatory arthritis dependent on T and B cell priming, NOD2 activation potentiates disease. However, the absence of NOD2 does not alter the course of inflammatory arthritis, in contrast to models of intestinal inflammation.

Nucleotide oligomerization domain-2 (NOD2)-induced uveitis: dependence on IFN-gamma

PURPOSE

Nucleotide oligomerization domain-2 (NOD2) plays an important role in innate immunity to sense muramyl dipeptide (MDP), a component of bacterial cell walls. Notably, NOD2 is linked to eye inflammation because mutations in NOD2 cause a granulomatous type of uveitis called Blau syndrome. A mouse model of NOD2-dependent ocular inflammation was employed to test the role of a cytokine strongly implicated in granuloma formation, IFN-gamma, in order to gain insight into downstream functional consequences of NOD2 activation within the eye triggering uveitis.

METHODS

Mice deficient in IFN-gamma, NOD2, or CD11b and their wild-type controls were treated with intravitreal injection of MDP in the presence or absence of IFN-gamma. IFN-gamma production in the eye was measured by ELISA. The intravascular inflammatory response within the iris was quantified by intravital microscopy.

RESULTS

NOD2 activation resulted in the production of IFN-gamma within the eye. Deficiency in IFN-gamma diminished the development of MDP-induced uveitis, indicating its crucial role in downstream inflammatory events triggered by NOD2. Moreover, exogenous IFN-gamma markedly exacerbated MDP-induced ocular inflammation in a NOD2-dependent mechanism. The potential of IFN-gamma to enhance inflammation required the adhesion molecule CD11b because CD11b-deficient mice failed to show the synergistic effects of IFN-gamma and MDP cotreatment on adhering and infiltrating cells.

CONCLUSIONS

IFN-gamma was identified as a downstream mediator of NOD2-driven inflammation and the capacity of IFN-gamma in vivo to enhance the inflammatory potential of NOD2 was demonstrated. Extrapolation of these findings in mice suggests that the dysregulation of IFN-gamma may occur in patients with Blau syndrome, thereby contributing to the granulomatous nature of the disease.

NOD2, the gene responsible for familial granulomatous uveitis, in a mouse model of uveitis

PURPOSE

NOD2 plays an important role in the recognition of intracellular bacteria through its ability to sense the components of bacterial peptidoglycan (PGN), namely muramyl dipeptide (MDP) and muramyl tripeptide (MTP). Specific mutations in the human NOD2 gene cause Blau syndrome, an autosomal dominant form of uveitis, arthritis, and dermatitis. As a first step toward understanding the role of NOD2 in the pathogenesis of uveitis, the authors developed a mouse model of MDP-dependent uveitis.

METHODS

BALB/c mice and mice deficient in L-selectin or NOD2 received intravitreal injection of MDP, MTP, or PGN. The intravascular response within the iris and cellular infiltration was quantified by intravital microscopy and histologic assessment.

RESULTS

MDP induced an acute, ocular inflammatory response, wherein rolling and adhering leukocytes within the vasculature were significantly increased within 6 hours after MDP treatment. A minor increase in cellular infiltration occurred at 12 hours after MDP treatment. The adhesion molecule L-selectin participated in MDP-induced vascular inflammation because L-selectin knockout mice showed a significant decrease in the number of rolling cells. Importantly, NOD2 plays an essential role in ocular inflammation induced by MDP, as indicated by the fact that uveitis did not develop in Nod2 knockout mice in response to MDP. Nod2 knockout mice also showed abolished ocular inflammation in response to MTP but not to PGN treatment.

CONCLUSIONS

These findings demonstrate a novel mouse model of uveitis, wherein NOD2 plays an essential role in inflammation induced by the minimal components of PGN. Thus, innate immune responses mediated by NOD2 may participate in the development of uveitis in response to bacterial products.

Activation of NOD2 in vivo induces IL-1beta production in the eye via caspase-1 but results in ocular inflammation independently of IL-1 signaling

Nucleotide-binding and oligomerization domain 2 (NOD2) belongs to the emerging Nod-like receptor (NLR) family considered important in innate immunity. Mutations in NOD2 cause Blau syndrome, an inherited inflammation of eye, joints, and skin. Mutations in a homologous region of another NLR member, NALP3, cause autoinflammation, wherein IL-1beta plays a critical role. Here, we tested the hypothesis that IL-1beta is a downstream mediator of NOD2-dependent ocular inflammation. We used a mouse model of NOD2-dependent ocular inflammation induced by muramyl dipeptide (MDP), the minimal bacterial motif sensed by NOD2. We report that MDP-induced ocular inflammation generates IL-1beta and IL-18 within the eye in a NOD2- and caspase-1-dependent manner. Surprisingly, two critical measures of ocular inflammation, leukocyte rolling and leukocyte intravascular adherence, appear to be completely independent of IL-1 signaling effects, as caspase-1 and IL-1R1-deficient mice still developed ocular inflammation in response to MDP. In contrast to the eye, a diminished neutrophil response was observed in an in vivo model of MDP-induced peritonitis in caspase-1-deficient mice, suggesting that IL-1beta is not essential in NOD2-dependent ocular inflammation, but it is involved, in part, in systemic inflammation triggered by NOD2 activation. This disparity may be influenced by IL-1R antagonist (IL-1Ra), as we observed differential IL-1Ra levels in the eye versus plasma at baseline levels and in response to MDP treatment. This report reveals a new in vivo function of NOD2 within the eye yet importantly, distinguishes NOD2-dependent from NALP3-dependent inflammation, as ocular inflammation in mice occurred independently of IL-1beta.

Anterior uveitis accompanies joint disease in a murine model resembling ankylosing spondylitis

BACKGROUND

Uveitis is often associated with a systemic inflammatory disease such as ankylosing spondylitis. Our understanding of the eye's susceptibility to immune-mediated uveitis as in the apparent absence of infection has been limited by a relative lack of experimental models. Here we sought to assess whether ocular inflammation occurs in a previously described murine model of proteoglycan-induced spondylitis, wherein mice develop progressive spondylitis, sacroiliitis and peripheral arthritis--features common to the clinical presentations of ankylosing spondylitis.

METHODS

Using intravital microscopy we examined the ocular inflammatory response after the onset of arthritis in mice that overexpressed the T cell receptor (TCR) specific for a dominant arthritogenic epitope of cartilage proteoglycan [TCR-Tg (transgenic) mice] or BALB/c controls.

RESULTS

Immunized TCR-Tg mice showed a significant increase in the number of rolling and adhering cells within the iris vasculature compared to adjuvant control mice. Cellular infiltration within the iris tissue, as assessed by intravital microscopy and histology, was also increased. Our initial temporal analysis has revealed that immunized TCR-Tg mice show a significant increase in intravascular inflammation by 2 weeks after immunization, but it diminishes at 4 weeks after immunization.

CONCLUSIONS

Although these data are preliminary, this model has the potential to clarify the mechanisms accounting for the coexistence of eye and sacroiliac inflammation as occurs in patients with ankylosing spondylitis.

Infantile onset panniculitis with uveitis and systemic granulomatosis: a new clinicopathologic entity

We report on 4 children with infantile-onset lobular panniculitis, high fever, uveitis, and systemic granulomatous inflammation, recruited through the International Registry of Pediatric Granulomatous Arthritis. Neither CARD15 nor CIAS1 mutations were found. Despite immunosuppressive therapy, disease course was progressive. Response to anti-tumor necrosis factor monoclonal antibody in 3 patients is of note.

Can medical schools teach high school students to be scientists?

The preeminence of science in the United States is endangered for multiple reasons, including mediocre achievement in science education by secondary school students. A group of scientists at Oregon Health and Science University has established a class to teach the process of scientific inquiry to local high school students. Prominent aspects of the class include pairing of the student with a mentor; use of a journal club format; preparation of a referenced, hypothesis driven research proposal; and a "hands-on" laboratory experience. A survey of our graduates found that 73% were planning careers in health or science. In comparison to conventional science classes, including chemistry, biology, and algebra, our students were 7 times more likely to rank the scientific inquiry class as influencing career or life choices. Medical schools should make research opportunities widely available to teenagers because this experience dramatically affects one's attitude toward science and the likelihood that a student will pursue a career in science or medicine. A federal initiative could facilitate student opportunities to pursue research.

Interstitial pneumonitis in Blau syndrome with documented mutation inCARD15

This is the first report of a CARD15 mutation-positive patient with Blau syndrome who exhibited interstitial lung disease, a feature historically considered absent from Blau syndrome, while typical of the adult form of sarcoidosis. This case illustrates the continued evolution of the phenotype of a disease initially conceived as a familial inflammatory granulomatous disease limited to the triad of synovitis, dermatitis, and uveitis.

Pediatric granulomatous arthritis: An international registry

OBJECTIVE

Blau syndrome and its sporadic counterpart, early-onset sarcoidosis, share an identical phenotype featuring the classic triad of arthritis, dermatitis, and uveitis and are associated with mutations of CARD15 in 50-90% of cases. We chose the term "pediatric granulomatous arthritis" to refer to both. An international registry was established in the spring of 2005 to define the phenotype spectrum and establish the mutation frequency and variants.

METHODS

Histologically confirmed granuloma and arthritis were required for inclusion. Probands and relatives were genotyped for CARD15. Deidentified clinical information was collected.

RESULTS

One year after the inception of the registry, 61 individuals from 22 pedigrees had been entered. Seven pedigrees with 19 individuals (8 affected, 11 unaffected) had clinical disease that was atypical, and none of the individuals in those pedigrees showed mutations. There were 9 classic simplex pediatric granulomatous arthritis pedigrees including 19 individuals (9 affected, 10 unaffected) and 6 classic multiplex pedigrees with 22 individuals (17 affected, 5 unaffected). Cutaneous presentation was the most common. Arthritis was polyarticular in 96% of patients. Isolated eye disease was never the presenting symptom, but significant/severe visual impairment was observed in 41% of patients. Eye disease was bilateral in 21 of 22 patients and was complicated by glaucoma in 6 of 22 patients and by cataracts in 50% of patients. Skin biopsy was the best diagnostic approach (because of accuracy and low invasiveness).

CONCLUSION

In this series, the first combining familial and sporadic pedigrees and, to our knowledge, the largest, we further defined the phenotype and showed that all affected classic (and no nonclassic) pedigrees carry a mutation and that there is no asymptomatic carriage. If these data are confirmed, mutation analysis rather than tissue sampling may prove to be the most efficient diagnostic procedure.

Human endothelial cells express NOD2/CARD15 and increase IL-6 secretion in response to muramyl dipeptide

Mutations in the human NOD2/CARD15 gene cause Blau syndrome, an autoinflammatory disorder involving the joints, skin and eyes. Insights into the mechanism of this association may be gained by a further understanding of where NOD2 is expressed. The objective of this study was to analyze ocular endothelial cells for NOD2 expression. Human ocular tissue was analyzed by immunohistology using anti-NOD2 antisera. RNA isolated from iris, choroid and endothelial cell lines was analyzed by reverse transcription-PCR and real-time quantitative PCR. Gene regulation was studied by treating endothelial cells with TNF-alpha and IFN-gamma. Functional responses were assessed by measuring IL-6 release from endothelial cells treated with muramyl dipeptide (MDP), synthetic lipopeptide (Pam3CSK4) and lipopolysaccharide (LPS). Immunohistological analysis revealed staining of endothelial cells in the uveal tract. NOD2 expression was detected in primary ocular endothelial cell cultures, and levels increased in response to inflammatory cytokines. Endothelial cells from choroid demonstrated enhanced release of IL-6 in response to MDP, and synergy was observed following treatment with MDP and either Pam3CSK4 or LPS. The observations that endothelial cells express NOD2, upregulate NOD2 in response to stimuli known to promote NOD2 expression and show synergistic cytokine responses to MDP and TLR ligands previously shown to be mediated by NOD2 are informative since they may be relevant to pathogenic mechanisms leading to the spectrum of inflammation seen in Blau syndrome.

Caspase recruitment domain 15 mutations and rheumatic diseases

PURPOSE OF REVIEW

The purpose of this article is to review the foundational work and current developments on a group of rheumatic disorders associated with mutations in the caspase recruitment domain 15/nucleotide oligomerization domain 2 gene.

RECENT FINDINGS

To date, there are at least 10 arthritic conditions for which specific genetic mutations have been demonstrated. They include familial Mediterranean fever; tumor necrosis factor receptor associated periodic syndrome; hyper immunoglobulin D syndrome; neonatal onset multisystemic inflammatory disease; pyogenic arthritis pyoderma gangrenosum and acne; Muckle-Wells syndrome; familial cold autoinflammatory syndrome; immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome; Crohn's disease; and familial and sporadic sarcoid granulomatous arthritis. This review focuses on recent progress in the last two diseases and the caspase recruitment domain 15 genetic defects with which they are associated. Up to 50% of patients with familial granulomatous arthritis (Blau's syndrome), 90% of those with sporadic granulomatous arthritis (early-onset sarcoidosis), and 40% of individuals with Crohn's disease have documented mutations in the caspase recruitment domain 15 gene.

SUMMARY

Although histologically, Crohn's disease and familial and sporadic sarcoid granulomatous arthritis are distinct from rheumatoid arthritis because of the defining presence (albeit in not all cases) of non-caseating granulomata in the synovial and intestinal tissues, respectively, they still represent a promising model of both chronic synovitis and uveitis. In addition, once the actual mechanism is discovered by which defects of the caspase recruitment domain 15 gene product lead to chronic arthritis, it may uncover unsuspected biologic targets for therapeutics.

A locus on chromosome 9p predisposes to a specific disease manifestation, acute anterior uveitis, in ankylosing spondylitis, a genetically complex, multisystem, inflammatory disease

OBJECTIVE

Uveitis or intraocular inflammation is a major cause of visual loss. Acute anterior uveitis (AAU) affects approximately 40% of patients with ankylosing spondylitis (AS) but also affects patients with no evidence of spondylarthritis. We sought to determine whether a unique genetic region could be implicated in a specific manifestation-AAU-of a multisystem, inflammatory, genetically complex disease, AS.

METHODS

Individuals from families multiplex for AAU were genotyped at 400 markers representing the ABI PRISM linkage map MD-10, and at the HLA-B, DRB1, DQA1, DQB1, and DPB1 alleles. Among the family members with AAU, 76 affected sibpairs were analyzed (6 without concomitant AS, 12 discordant for AS, and 58 concordant for AS). Two-point and multipoint nonparametric linkage analyses were performed, and 1-parameter allele-sharing model logarithm of odds (LOD) scores were determined.

RESULTS

As previously reported for AS, linkage at the major histocompatibility complex region (chromosome 6p21) was evident, exhibiting the highest multipoint LOD score (4.96 at marker HLA-B). Strong linkage was seen at a region on chromosome 9p21-9p24, with a LOD score of 3.72 at marker D9S157. When compared with a companion cohort of AS families, the linkage at this region was found in association with AAU but not with AS. A third region on chromosome 1q23-1q31 was observed to have suggestive linkage (LOD 2.05 at marker D1S238), which overlaps with a region associated with AS.

CONCLUSION

This is the first study in which a genetic region for AAU has been identified by genome-wide scan. Even though AS was highly prevalent in this cohort of families, a locus at chromosome 9p21-9p24 was identified that uniquely associates with AAU. Identifying the genetic perturbation at this region may advance our understanding of the mechanisms involved in tissue-specific pathology of complex inflammatory diseases.

Blau syndrome mutation of CARD15/NOD2 in sporadic early onset granulomatous arthritis

Patients with sporadic early-onset granulomatous arthritis are clinically identical to Blau syndrome, but without the family history. Blau syndrome is an autosomal dominant inherited disease and is known to be caused by mutations in the CARD15 gene (also called NOD2). We investigated the hypothesis that an individual with sporadic early onset granulomatous arthritis may have a Blau syndrome mutation in CARD15/NOD2. Our patient's genomic DNA isolated from a buccal swab sample was subjected to amplification to include the region of exon 4 from the CARD15/NOD2 gene that contains known mutations that cause Blau syndrome. This region was screened for mutations by direct DNA sequencing in both directions. One of the mutations in CARD15/NOD2 attributed to Blau syndrome was found in the DNA sample. The nucleotide change encodes an amino acid substitution from arginine to tryptophan at position 334 of the protein. This mutation has been found in some Blau syndrome pedigrees reported in the literature. These data suggest that sporadic granulomatous arthritis may in fact be the sporadic form of Blau syndrome, but arising from a spontaneous neomutation. This would explain the profound clinical identity and the lack of disease history in the parents.