A large meta-analysis identifies genes associated with anterior uveitis

Anterior Uveitis (AU) is the inflammation of the anterior part of the eye, the iris and ciliary body and is strongly associated with HLA-B*27. We report AU exome sequencing results from eight independent cohorts consisting of 3,850 cases and 916,549 controls. We identify common genome-wide significant loci in HLA-B (OR = 3.37, p = 1.03e-196) and ERAP1 (OR = 0.86, p = 1.1e-08), and find IPMK (OR = 9.4, p = 4.42e-09) and IDO2 (OR = 3.61, p = 6.16e-08) as genome-wide significant genes based on the burden of rare coding variants. Dividing the cohort into HLA-B*27 positive and negative individuals, we find ERAP1 haplotype is strongly protective only for B*27-positive AU (OR = 0.73, p = 5.2e-10). Investigation of B*27-negative AU identifies a common signal near HLA-DPB1 (rs3117230, OR = 1.26, p = 2.7e-08), risk genes IPMK and IDO2, and several additional candidate risk genes, including ADGFR5, STXBP2, and ACHE. Taken together, we decipher the genetics underlying B*27-positive and -negative AU and identify rare and common genetic signals for both subtypes of disease.

Molecular Signatures of Natural Killer Cells in CMV-Associated Anterior Uveitis, A New Type of CMV-Induced Disease in Immunocompetent Individuals

Cytomegalovirus (CMV) causes clinical issues primarily in immune-suppressed conditions. CMV-associated anterior uveitis (CMV-AU) is a notable new disease entity manifesting recurrent ocular inflammation in immunocompetent individuals. As patient demographics indicated contributions from genetic background and immunosenescence as possible underlying pathological mechanisms, we analyzed the immunogenetics of the cohort in conjunction with cell phenotypes to identify molecular signatures of CMV-AU. Among the immune cell types, natural killer (NK) cells are main responders against CMV. Therefore, we first characterized variants of polymorphic genes that encode differences in CMV-related human NK cell responses (Killer cell Immunoglobulin-like Receptors (KIR) and HLA class I) in 122 CMV-AU patients. The cases were then stratified according to their genetic features and NK cells were analyzed for human CMV-related markers (CD57, KLRG1, NKG2C) by flow cytometry. KIR3DL1 and HLA class I combinations encoding strong receptor–ligand interactions were present at substantially higher frequencies in CMV-AU. In these cases, NK cell profiling revealed expansion of the subset co-expressing CD57 and KLRG1, and together with KIR3DL1 and the CMV-recognizing NKG2C receptor. The findings imply that a mechanism of CMV-AU pathogenesis likely involves CMV-responding NK cells co-expressing CD57/KLRG1/NKG2C that develop on a genetic background of KIR3DL1/HLA-B allotypes encoding strong receptor–ligand interactions.

Recent Developments in HLA B27 Anterior Uveitis

There has been steady progress in understanding the pathogenesis, clinical features, and effective treatment of acute anterior uveitis (AU) over the past 5 years. Large gene wide association studies have confirmed that AU is a polygenic disease, with overlaps with the seronegative arthropathies and inflammatory bowel diseases, associations that have been repeatedly confirmed in clinical studies. The role of the microbiome in AU has received increased research attention, with recent evidence indicating that human leukocyte antigen B27 (HLA B27) may influence the composition of the gut microbiome in experimental animals. Extensive clinical investigations have confirmed the typical features of acute AU (AAU) and its response to topical, regional and systemic immunosuppressive treatment. Increased understanding of the role of cytokines has resulted in studies confirming the value of anti-cytokine therapy [anti-tumor necrosis factor (anti-TNF) and interleukin 6 (IL-6) therapy] in severe and recurrent cases of AAU, particularly in subjects with an associated spondyloarthopathy (SpA) and in juvenile idiopathic arthritis (JIA)-associated AAU.

The LMP2 CfoI polymorphism is associated with ankylosing spondylitis (AS) risk but not with acute anterior uveitis (AAU): A meta-analysis

BACKGROUND

Ankylosing spondylitis (AS) is one of the most common chronic inflammatory disorders affecting the sacroiliac joints, spine, and peripheral joints. Apart from HLA-B27, the LMP2 gene has been shown to play a role in the pathogenesis of AS as well as AAU in AS. However, genetic associations between LMP2 CfoI polymorphism and AS and AAU were inconclusive. We aimed to investigate the correlation of LMP2 CfoI polymorphism and AS and AAU using meta-analysis.

METHODS

An exhaustive search was conducted using the PubMed, Embase, Cochrane Library, and Chinese National Knowledge Infrastructure (CNKI) electronic databases. The strength association was assessed by crude ORs with 95% CI.

RESULTS

Eight eligible records with 449 AS patients and 317 healthy controls were included in the present study. The allelic model of the LMP2 CfoI polymorphism is associated with AS risk (OR = 0.60, 95%CI = [0.32, 1.11], P = .003). A stratified analysis based on ethnicity has shown that the allelic model of LMP2 CfoI was associated with AS in the Caucasian population (OR = 0.72, 95%CI = [0.55, 0.93], P = .01) but not in the Asian population (P > .05). Furthermore, no association was detected between LMP2 CfoI polymorphism and AS complication (AAU).

CONCLUSION

Our combined results revealed that the allelic model of LMP2 CfoI might be a protective factor for AS in the Caucasian population. Nevertheless, future studies on different ethnicities with larger sample sizes are needed to obtain a more convincing result.

Growth hormone-releasing hormone receptor mediates cytokine production in ciliary and iris epithelial cells during LPS-induced ocular inflammation

The receptor for growth hormone-releasing hormone (GHRH-R) has been shown to upregulate specifically in the ciliary and iris epithelial cells and infiltrating cells in the aqueous humor in a rat model of acute anterior uveitis. Treatment with GHRHR-R antagonist alleviates significantly these inflammatory responses. Herein we investigated whether the ciliary and iris epithelial cells can respond directly to lipopolysaccharide (LPS) without the influences of circulating leukocytes to produce inflammatory mediators through a GHRH-R mediated mechanism. In explant cultures of rat ciliary body and iris, LPS caused a substantial increase of GHRH-R in 24 h. Immunohistochemistry showed a localization of TLR4, the receptor for LPS, and an elevated expression of IL-6 and IL-1β in ciliary and iris epithelial cells after LPS treatment. LPS also elevated the level of IL-1β, IL-6, and iNOS and increased secretion of IL-1β and IL-6 from the explants. The GHRH-R antagonist, MIA-602, suppressed the elevated expression of IL-1β and IL-6, and reduced the release of IL-6. Such effects were not seen for the GHRHR agonist, MR-409. When co-cultured with leukocytes, expression of GHRH-R in the ocular explants was further enhanced during LPS treatment. Our results demonstrate a direct action of LPS on ciliary and iris epithelial cells to produce pro-inflammatory factors through a GHRH-R mediated mechanism, and suggest a role of these epithelial cells, in addition to the resident antigen presenting cells, in immune surveillance of the eye. Infiltrating leukocytes may enhance these inflammatory responses by regulating GHRH-R in ciliary and iris epithelial cells, in addition to their functions of synthesizing proinflammatory cytokines.

Associations of Independent IL2RA Gene Variants with Intermediate Uveitis

Purpose

The genetic background for the concomitance of uveitis and other autoimmune diseases remains elusive. Here the role of two IL2RA gene variants (rs11594656 and rs12722495) was investigated in intermediate uveitis and HLAB27 acute anterior uveitis.

Materials and Methods

One hundred fifty-nine patients with HLAB27 acute anterior uveitis, 85 patients with intermediate uveitis, 138 HLAB27 negative controls and 100 HLAB27 positive controls were recruited for this case-control study. Main outcome measures were genotype distribution and allelic frequencies determined by polymerase chain reaction.

Results

The frequencies of carriers of the minor allele at rs11594656 and rs12722495 were significantly different in patients with intermediate uveitis compared to HLAB27 positive and negative controls combined (p<0.05). For rs12722495 the minor G allele was protective (genotypic OR: 0.29 [0.12-0.69]), and for rs11594656 the minor A allele conferred risk (genotypic OR: 1.59 [1.09-2.32]). No significant differences in genotype distribution were found between patients with HLAB27 acute anterior uveitis and HLAB27 positive or negative control subjects.

Conclusions

We found rs11594656 and rs12722495 to be associated with intermediate uveitis but not with HLAB27 acute anterior uveitis. The genetic heterogeneity found at the IL2RA locus could help explain patterns of concomitance with other autoimmune diseases.

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.

Description of a new family with cryopyrin-associated periodic syndrome: risk of visual loss in patients bearing the R260W mutation

OBJECTIVE

The aim of this study was to describe a family with cryopyrin-associated periodic syndrome (CAPS) in which the disease was unveiled after the ophthalmologic evaluation.

METHODS

Family and personal histories from each of the patients were recorded. Each underwent a full ophthalmological examination along with the physical examination. The mutational analysis of the NLRP3 gene was performed by means of direct sequencing.

RESULTS

The proband was admitted during an episode of unilateral anterior uveitis. She had a history of recurrent red eye and had been suffering episodes of skin rash and arthralgia induced by cold since childhood. At examination, she showed a reticulated corneal mid-stroma. Her mother and her younger sister also suffered from relapsing episodes of skin rash and fever triggered by cold as well as flares of red eye. They had developed premature hearing loss. In both cases, opacities in the corneal mid-stroma were evidenced with a slit lamp. The genetic analysis detected the heterozygous germline p.R260W mutation in the NLRP3 gene in the three women, confirming the diagnosis of CAPS. Treatment with anakinra resulted in complete remission of flares.

CONCLUSION

In this family, a structural NLRP3 mutation was associated with classic MuckleWells features of different degrees of severity. Interstitial keratitis with corneal opacification, usually ascribed to neonatal-onset multisystem inflammatory disease, was found. We underscore that ocular involvement in MuckleWells syndrome should be carefully assessed, since it can lead to visual impairment.

[Screening of key genes and inflammatory signalling pathway involved in the pathogenesis of HLA-B27-associated acute anterior uveitis by gene expression microarray]

OBJECTIVE

To investigate the genes and signalling pathways located upstream of the inflammatory processes in human leukocyte antigen (HLA)-B27-associated acute anterior uveitis by gene expression microarray.

METHODS

Experimental study. HLA-B27-positive and-negative monocytes isolated from human peripheral blood were stimulated with Vibrio cholera lipopolysaccharide (LPS). Gene expression microarrays were used to identify the differentially expressed genes. Differentially expressed (DE) genes were testified by real-time PCR and analyzed by a series of bioinformatics-based techniques such as Gene Ontology, Kyoto Encyclopedia of Genes and Genomes.

RESULTS

Gene expression microarray analysis revealed marked differences between HLA-B27-positive acute anterior uveitis (AAU) and HLA-B27-negative healthy control peripheral monocytes in the genes that were upregulated in response to LPS stimulation with 1105 genes and 25 genes respectively. Gene Ontology enrichment and pathway analysis indicated that genes participating in protein transport and folding were essential to the inflammatory process. The LPS receptor-Toll-like receptor (TLR)4 induced TLR signalling pathway and pathway related to Vibrio cholerae infection were located upstream of the network and contribute to the overall response. Among the DE genes, PIK3CA, PIK3CB, AKT3, and MAPK1 might play critical roles in inflammation.

CONCLUSIONS

Equivalent LPS stimulation induces a different response in HLA-B27-positive peripheral monocytes compared to normal control, suggesting that the TLR pathway is involved in the pathogenesis of HLA-B27-associated AAU.

HLA-B27 association with uveitis in an Asian Indian population

BACKGROUND

Uveitis refers to diseases characterized by intraocular inflammation of the uveal tract. Anterior uveitis is a common ocular disease characterized by inflammation of the iris and the ciliary body.

OBJECTIVES

To establish the frequency of HLA-B27-positive uveitis in Asian Indian population, study their clinical profile and compare it with other reports in literature.

METHODS

We retrospectively reviewed medical data of 89 patients of uveitis referred for HLA B27 typing with predominantly ocular symptoms during the period from April 2006-October 2010. All patients were tested for complete blood count, erythrocyte sedimentation rate, infectious diseases serology, HLA-B27 typing, and prepared radiographs of the sacroiliac joints and lumbar spine if required.

RESULTS

The HLA-B27 positive rate was 56.2% among patients and 3% for control samples. Most of the patients were in the age group of 41-50 years with a male predominance.

CONCLUSIONS

HLA-B27 was seen to be associated with acute anterior uveitis in Asian Indian males and the test is important for confirmation of diagnosis, prognostication and also for planning the treatment.

Clinical characterisation and molecular analysis of Wagner syndrome

AIM

To detail the clinical findings in a British family with molecularly characterised Wagner syndrome.

BACKGROUND

Only in the last year has the specific genetic defect in Wagner syndrome been identified, and the background literature of the molecular genetics is outlined. Clinical and laboratory findings in a second case of Wagner syndrome are included to highlight difficulties that can be encountered when identifying pathogenic mutations for disorders arising in complex genes.

METHODS

Mutation screening was performed using PCR and RT-PCR.

RESULTS

A heterozygous mutation was found converting the donor splice site of exon 8 of the chondroitin sulphate proteoglycan 2 (CSPG2). This is the same mutation that has been reported in the original Wagner pedigree. The main clinical features of Wagner syndrome are vitreous syneresis, thickening and incomplete separation of the posterior hyaloid membrane, chorioretinal changes accompanied by subnormal electroretinographic responses, an ectopic fovea and early-onset cataract. A clinical feature present in this family, but previously undescribed, is anterior uveitis without formation of synechiae. Wagner syndrome has a progressive course, resulting in loss of vision even in the absence of retinal detachment.

CONCLUSION

On a background of considerable confusion regarding the distinction between Wagner syndrome and predominantly ocular Stickler syndrome, it is now apparent the that two conditions are both clinically and genetically distinct. This report summarises the clinical findings in Wagner syndrome and extends the phenotypic characteristics.

Risks of relapse in patients with acute anterior uveitis

AIM

To quantify the rate of recurrence of acute anterior uveitis (AAU), and evaluate the influence of associated risk factors.

METHODS

We retrospectively reviewed the case notes of 185 patients with acute anterior uveitis, from their time of presentation to August 2001. The time to the first three recurrences of AAU from the onset of the disease was recorded, as well as the site of recurrence. Information regarding risk factors (for example (HLA-B27) status, spondyloarthropathy (SpA), family history of AAU/SpA and history of non-specific joint pain) were also collected.

RESULTS

Patients were followed up until their third relapse, or up to the censoring date (August 2001) if less than three relapses had occurred. The median length of follow-up was 35 months. One hundred and twenty-two patients (66%) developed at least one relapse and 67 (36%) had three or more relapses. Kaplan-Meier estimate of median interval between disease onset and the first relapse was 24 months 95% CI (16 to 34) and between the first and second relapse was 14 months 95% CI (9 to 22), and was 15 months 95% CI (10 to 25) months between the second and third relapse. Using Cox regression only the number of previous relapses was significantly associated with the risk of AAU recurrence. There was no significant association between other reported risk factors and the risk of relapse, and neither did any risk factor significantly modify the association between previous relapses and AAU recurrence (p>0.066 for all interactions). There was a borderline significant difference in survival according to the laterality pattern of recurrences (ipsilateral, alternate, or bilateral) with a slightly greater than expected number of events in those with bilateral recurrence (p = 0.048).

CONCLUSION

Patients with previous relapse(s) of AAU have a greater risk of AAU recurrence compared to those at disease onset but the risk of recurrence appears not to increase in a dose-response manner with increasing number of previous relapses. Demographic and extraocular features do not appear to influence the rate, or risk of recurrence of AAU.

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.

Cytokine gene polymorphisms involved in chronicity and complications of anterior uveitis

The aim of this study was to identify key cytokine polymorphisms associated with disease susceptibility, clinical phenotype, and outcome in patients with chronic anterior uveitis (CAU) as compared to those with recurrent self-limiting anterior uveitis (RAU). One hundred fifty seven British Caucasian patients with anterior uveitis were identified and divided into those where the inflammatory process lasted less than 3 months (RAU=118) and those where the inflammation persisted longer than 3 months (CAU=39). Patients with CAU were further sub-divided into idiopathic CAU, CAU associated with systemic disease, CAU with and without complications (posterior synechiae, posterior subcapsular lens opacity, raised intraocular pressure, cystoid macular oedema, and poor response to treatment). Sixty-six healthy controls were ethnically matched. TaqMan PCR amplification was used to genotype five single nucleotide polymorphisms in cytokine genes; IL-1RN+2018, IL-6-174, IL-10-1082, TNF-238, TNF-308 and these were correlated with clinical phenotype.

Chemokine gene polymorphisms in idiopathic anterior uveitis

OBJECTIVES

The aim of this study was to determine whether there are any associations between single nucleotide polymorphisms of the chemokine genes IL-8, MCP-1, their corresponding receptors CXCR1 and CCR2 and disease outcome in patients with acute idiopathic anterior uveitis.

METHODS

60 Caucasian patients with idiopathic acute recurrent anterior uveitis together with 120 healthy Caucasian control subjects were tested for the presence of 16 bi-allelic polymorphisms and HLA-B27 using polymerase chain reaction in association with sequence-specific primers with mismatches at the 3' end. The genetic data was then compared between patients and controls, and within the patient group itself for association with clinical disease outcome.

RESULTS

As expected, the frequency of HLA-B27 was significantly higher in the patient group than the control group (63.33% versus 15.83%; Pearson's P<0.0001, Fisher's P<0.0001). In addition, the frequency of the T allele of MCP-1 63555 was found to be significantly higher in the control group when compared to the patient group (P=0.0160).

CONCLUSION

This study describes an association between acute anterior uveitis and MCP-1 63555 polymorphisms where the T allele may be a protective marker against the disease.

Polymorphisms within the tumor necrosis factor-alpha promoter region in patients with HLA-B27-associated uveitis: association with susceptibility and clinical manifestations

PURPOSE

The existence of genetic variations in a number of cytokines has been considered to influence susceptibility or relate to disease severity in various autoimmune diseases. Among these, single-nucleotide polymorphisms (SNPs) of the tumor necrosis factor alpha (TNF-alpha) promoter at nucleotides -308 and -238 are considered to be protective against inflammation in HLA-B27-positive individuals, whereas the SNP at position -857 has been associated with disease development in anterior uveitis. We investigate a hypothesized association between the TNF-alpha -857 C-to-T, -308 G-to-A, and the TNF-alpha -238 G-to-A SNPs and the presence of HLA-B27-associated uveitis.

DESIGN

Retrospective case-control study.

PARTICIPANTS

One hundred fourteen Caucasian patients with HLA-B27-associated uveitis were studied. Mean age of patients was 44.9+/-14 years (range, 16-81), and mean duration of HLA-B27-associated uveitis was 115.6+/-104 months (range, 6 months-51 years). Eighty-six patients (75.4%) suffered from an additional systemic manifestation of the disease. Sixty-three unrelated healthy HLA-B27-positive blood donors and 88 unrelated healthy HLA-B27-negative individuals served as controls.

METHODS

Genotypes were determined by polymerase chain reaction.

MAIN OUTCOME PARAMETERS

Association of genotypes at positions -857, -308, and -238 of the TNF-alpha gene with disease development.

RESULTS

Frequencies of the TNF-alpha -308GA and TNF-alpha -238GA genotypes were significantly lower in patients with HLA-B27-associated uveitis (6.1% and 0%, respectively) when compared with the HLA-B27-negative control group, 23% at -308 (P = 0.003), and 7.9% at -238 (P = 0.0003). When compared with healthy HLA-B27-positive controls, a significantly lower frequency of the TNF-alpha -238GA genotype was found among patients (6.3%, P = 0.015). The frequency of the TNF-alpha -308GA genotype was also found to be lower in patients than among HLA-B27-positive control subjects, without, however, reaching statistical significance (6.1%, P = 0.07). No difference in frequencies was seen among the different groups for the SNPs at position -857.

CONCLUSION

Our data suggest that HLA-B27-positive individuals show a higher susceptibility towards development of an intraocular inflammation in the presence of an A allele at nucleotide -238 and, to a lesser degree, at nucleotide -308 of the TNF-alpha gene promoter.

Role of the CCL2/MCP-1 -2518A>G gene polymorphism in HLA-B27 associated uveitis

PURPOSE

Acute anterior uveitis (AAU) is the most common form of uveitis. Up to 50% of patients with AAU are HLA-B27 positive. Since HLA B27 itself plays only a minor role in the overall genetic background, other genetic variants are likely to contribute to the susceptibility to AAU. The chemokine (C-C motif) ligand 2 (CCL2) gene, coding for monocyte chemoattractant protein-1 (MCP-1), a chemotactic cytokine, is involved in the induction of uveitis. A CCL2 gene polymorphism, which is characterized by an A>G substitution at nucleotide -2518 in the promoter region of CCL2 has been previously shown to affect MCP-1 synthesis. The purpose of the present study was to investigate a hypothesized association between this genetic variant and the presence of HLA-B27 associated AAU.

METHODS

The study group comprised 114 patients with HLA-B27 associated AAU. One hundred and eleven healthy HLA-B27 positive individuals served as the HLA-B27 positive control group, whereas 81 healthy HLA-B27 negative individuals served as a HLA-B27 negative control group. Genotyping for the CCL2 -2518A>G polymorphism was performed by polymerase chain reaction.

RESULTS

Carriers of a CCL2 -2518G allele were found significantly more often in patients with HLA-B27 associated AAU than among HLA-B27 positive controls (49.2% and 31.5%, respectively; odds ratio 2.1; 95% confidence interval 1.2-3.6; p=0.007).

CONCLUSIONS

Our data suggest that the CCL2 -2518A>G polymorphism may play a role in HLA-B27 associated acute anterior uveitis.

Acute anterior uveitis and HLA-B27

Acute anterior uveitis is the most common form of uveitis. HLA-B27-associated acute anterior uveitis is a distinct clinical entity that has wide-ranging medical significance due to its ocular, systemic, immunologic, and genetic features. The association between HLA-B27 and the spectrum of HLA-B27-associated inflammatory diseases remains one of the strongest HLA-disease associations known to date. This review examines acute anterior uveitis with particular focus on HLA-B27-associated acute anterior uveitis, including the epidemiology, immunopathology, association with HLA-B27 and its subtypes, clinical features, complications, prognosis, and potential new therapies such as anti-TNFalpha therapy and oral HLA-B27-peptide tolerance. There have been substantial recent advances in both clinical and basic scientific research in this field, including studies of the various animal models of acute anterior uveitis and the HLA-B27 transgenic animals, and these are summarized in this review. To the ophthalmologist, HLA-B27-associated acute anterior uveitis is an important clinical entity that is common, afflicts relatively young patients in their most productive years, and is associated with significant ocular morbidity due to its typically recurrent attacks of inflammation and its potentially vision-threatening ocular complications. Furthermore, to the ophthalmologist and the internist, HLA-B27-associated acute anterior uveitis is also of systemic importance due to its significant association with extraocular inflammatory diseases.

TNF-857T, a genetic risk marker for acute anterior uveitis

PURPOSE

To determine the association between 17 single nucleotide polymorphisms (SNPs) of tumor necrosis factor-alpha, lymphotoxin-alpha, and the TNF-receptors genes (TNF, LTA, and TNFRSF1A and -B) and idiopathic acute anterior uveitis (IAU) and to investigate their association with HLA-B27 and/or the development of visually significant complications.

METHODS

Ninety-eight white patients in the United Kingdom were identified (by SL) from the uveitis clinics of Moorfields Eye Hospital (London, UK). Sequence-specific primers with 3' end mismatches were used to identify the presence of specific allelic variants by PCR amplification.

RESULTS

There was a significant increase in the frequency of the TNF-857T allele in patients with IAU when compared with control subjects (15.3% vs. 7.3%, P = 0.0006). The frequency of haplotype 4, containing the T allele at nucleotide position -857, was also significantly increased in patients with IAU compared with control subjects (15.4% vs. 7.1%, P = 0.0003, OR 2.4, 95% confidence interval 1.4-4.0). In subgroup analysis, there were significant differences in the frequencies of the uncommon TNFRSF1A-201T and TNFRSF1A-1135T alleles between HLA-B27(+) patients with inflammation-related complications and those without complications (80.0% vs. 33.6%, P = 0.006; 80.0% vs. 36.6%, P = 0.01, respectively).

CONCLUSIONS

A significant difference in the frequency of TNF-857T allele was found in patients with IAU. There was a trend toward the development of inflammation-related complications in HLA-B27(+) patients with IAU who were carriers of TNFRSF1A-201T or TNFRSF1A-1135T alleles. Genetic variations in these proinflammatory mediators and their receptors appear to influence the susceptibility and severity of the inflammatory response within the eyes of patients during the development of IAU.

Alpha-1-antitrypsin phenotypes and HLA-B27 typing in uveitis patients in southeast Iran

OBJECTIVES

Uveitis is an eye disease that affects humans worldwide. Inflammation of the uveal tract is termed uveitis. Alpha-1-antitrypsin (AAT) deficiency is one of many factors that may be involved in abnormalities such as liver and lung disease, inflammatory joint diseases, and inflammatory eye diseases. In this study, the role of AAT in uveitis is analyzed.

DESIGN AND METHODS

AAT phenotyping and serum-trypsin inhibitory capacity (S-TIC) experiments were performed on 103 patients who were referred to the ALZAHRA eye center in Zahedan (southeast of Iran). The same experiments were performed on 167 people who did not suffer from any eye or systemic diseases and served as a control group.

RESULTS

The results revealed that the frequency of M1S, M2S, M1Z, and MV phenotypes were significantly higher in uveitis patients (P < 0.001). There was no difference in AAT phenotype frequencies between various types of uveitis (P = 0.1).

CONCLUSION

AAT deficiency appears to be a risk factor for uveitis in southeast Iran. More investigation is needed to establish potential benefits of AAT phenotyping tests and AAT therapy in the diagnosis and treatment of uveitis cases with unclear etiology.

HLA-B27-associated uveitis with a chorioretinitis manifestation

A 29-year-old man who had been treated for acute anterior uveitis in a local medical office and observed for 1 month presented complaining of distorted vision in his left eye for 1 week. On ophthalmic examination, the anterior segment was relatively quiet with few cells. A posterior segment examination revealed cystoid macular edema and multiple splinter retinal hemorrhages. Results of all laboratory and imaging studies were negative, except for a positive HLA-B27 haplotype. Fluorescein angiography revealed massive leakage in the mid and late phase, consistent with chorioretinitis. Periocular corticosteroid injections and oral prednisolone were administered. The patient responded to the treatment well with subsequent resolution of chorioretinitis 2 months later. Although rare, chorioretinitis can occur in the setting of uveitis associated with HLA-B27 and seems to respond well to corticosteroid treatment.

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.

Sporadic Blau syndrome with a double CARD15 mutation. Report of a case with lifelong follow-up

Blau syndrome (MIM 186580) is a rare granulomatous disorder inherited in an autosomal dominant manner characterized by the early appearance of granulomatous arthritis, skin rash and anterior uveitis. Missense mutations in CARD15, usually on codon 334, have been described in several families with Blau syndrome. The disorder has been described as familial; here we report the first evidence of a sporadic case of Blau syndrome in a 19 year-old man with two CARD15 mutations (R334Q and G908R). His healthy mother, father and brother did not carry the R334Q mutation, which was thus considered a neo-mutation, nor did they carry the other mutation, usually found in Crohn's disease. An extensive radiologic, histologic and laboratory evaluation and a life-long clinical follow-up is available for this patient who presented skin, joint, epididimal and eye involvement.

Susceptibility to endotoxin induced uveitis is not reduced in mice deficient in BLT1, the high affinity leukotriene B4 receptor

AIM

To investigate the role of arachidonic acid derived chemotactic factor, LTB(4), in the development of endotoxin induced uveitis (EIU), using mice deficient in the BLT1 gene which encodes the high affinity LTB(4) receptor.

METHODS

BLT1 gene deficient and wild type BALB/c mice were injected intravitreally with Escherichia coli 055:B5 lipopolysaccharide (250 ng/2 microl). Number of leukocytes invading the anterior chamber 24 hours later were counted on tissue cross sections.

RESULTS

In all mice, EIU was characterised by a polymorphonuclear and mononuclear cell infiltrate. Numbers of infiltrating cells did not differ significantly between control and BLT1 gene knockout mice.

CONCLUSION

Chemotactic factors other than LTB(4) are primarily responsible for leukocyte migration into the eye during murine EIU.

HLA-B27 subtypes determination in patients with ankylosing spondylitis from Zulia, Venezuela

To perform an investigation regarding the distribution of the human leukocyte antigen (HLA)-B27 subtypes in the Zulian population with ankylosing spondylitis (AS), 48 unrelated Mestizos, HLA-B27 positive by serology, were studied using the polymerase chain reaction-specific sequence oligonucleotides probe (PCR-SSOP) and specific sequence primers (SSP) to analyze the polymorphism in exons 2 and 3 of the HLA-B27 gene. Only two of eight HLA-B27 subtypes studied (B*2701-B*2708) were found. The distribution of these alleles in the population of patients was: B*2705, 68.8%, and B*2702, 31.2%. B*2705 subtype showed significant association with patients being male. In the healthy controls, the most common subtype was B*2708. These results were compared with frequencies reported in other Mestizo and Spanish populations and showed significant differences, such as a high frequency of B*2702. Such results show that HLA*B2705 and HLA*B2702 are the subtypes most frequently associated with AS in our Mestizo population and suggest a possible protector role for HLA*B2708, which was found only in the healthy population.

The monthly variation in acute anterior uveitis in a community-based ophthalmology practice

BACKGROUND

A significant increase in the number of episodes of acute anterior uveitis was found in December for two consecutive years at a community-based ophthalmology practice.

PURPOSE

To evaluate the monthly variation in episodes of acute anterior uveitis (AAU).

METHODS

The charts of all patients with AAU in a practice within a community-based multispecialty ophthalmology group in Albuquerque, New Mexico, were reviewed. Seventy-seven patients with acute, self limited, nontraumatic, unilateral, nongranulomatous anterior uveitis over a two-year period were identified.

RESULTS

Ninety-four episodes of AAU occurred in 77 patients (42 men, 35 women). The median number of episodes of AAU was three episodes per month (range: 0-14 episodes/month). An increased number of episodes was found in December of both years (11 in December 1996 [p < 0.01] and 14 in December 1997 [p < 0.003]). Smaller clusters of AAU were seen in other months, but did not reach statistical significance.

CONCLUSIONS

The presence of a seasonal variation in the number of episodes of AAU suggests that environmental factors are important. A search for such factors that increase the risk of AAU during selected periods may be useful for a better understanding of disease pathogenesis.

Crucial role of CCL3/MIP-1alpha in the recurrence of autoimmune anterior uveitis induced with myelin basic protein in Lewis rats

In this study, we examined the role of CCL2/MCP-1, CCL3/MIP-1alpha, CCL4/MIP-1beta, and CCL5/RANTES during recurrent anterior uveitis (RAU). LEW rats injected with myelin basic protein (MBP) developed experimental autoimmune encephalomyelitis (EAE) and associated anterior uveitis (AU), which was mediated by CD4(+) T cells. After recovery, rats become resistant to EAE but developed RAU. Rats reinjected with MBP developed RAU without EAE. The chemokines tested were detected in the eye at RAU accelerated onset, increased as the disease progressed, and fell as clinical signs improved. At the same time, in the spinal cords of rats, these chemokines were still detected but at reduced levels. Administration of anti-MIP-1alpha neutralizing antibodies resulted in almost complete suppression of clinical RAU and significant reduction of inflammatory cell recruitment into the iris. Anti-MIP-1beta and anti-MCP-1 antibodies were effective in suppression of RAU but to lesser degree. Treatment with anti-RANTES antibodies was not effective in protecting against the recurrent development of the disease. In the eyes, the message for CCR1 and CCR5 was considerably elevated prior to the onset of AU and decreased after treatment with anti-chemokine antibodies. Our results suggest a crucial role of CCL3/MIP-1alpha in the development of RAU in Lewis rats. In addition, CCL2/MCP-1 and CCL4/MIP-1beta may also play a role in immunopathogenesis of RAU.

Primary ankylosing spondylitis: patterns of disease in a Brazilian population of 147 patients

OBJECTIVE

To analyze patterns of disease in a population of Brazilian patients with primary ankylosing spondylitis (AS).

METHODS

Retrospective study (1988-98) analyzing 147 patients with a diagnosis of primary AS according to the modified New York criteria. Selected patients had complete clinical (initial symptom, axial and peripheral involvement, heel enthesitis, extraarticular manifestations) and radiological (sacroiliac, lumbar, thoracic, and cervical spine) investigations, and these data were compared with sex, race, age at onset, and HLA-B27.

RESULTS

There was a predominance of men (84.4%), Caucasian race (75.5%), adult onset (> 16 years, 85%), and positive HLA-B27 (78.2%). Family history of AS was noted in 14.3% of the patients. Pure axial AS was observed in 37 patients (25.2%). The predominant initial symptoms were inflammatory low back pain (61.9%) and peripheral arthritis (22.4%). Thoracic and cervical spine involvement was noted in 70.1% of the patients; radiological findings included syndesmophytes in 46.9% and "bamboo spine" in 20.4% of patients. The extraaxial joints most frequently involved were: ankles (39.5%), hips (36.1%), knees (29.3%), shoulders (19%), and sternoclaviculars (14.3%); heel enthesitis was present in 22.4%. Acute anterior uveitis was noted in 14.3% of patients. Male sex was associated with involvement of thoracic spine (p = 0.002), cervical spine (p = 0.002), and hips (p = 0.042), whereas female sex was associated with sternoclavicular (p = 0.024) involvement. Caucasian race presented higher frequency of positive family history (p = 0.023); there was no statistical significance of clinical and radiological variables compared with African-Brazilians. Juvenile onset AS presented higher frequency of ankle (p = 0.012) and knee (p = 0.001) involvement, heel enthesitis (p = 0.001), and total hip replacement (p = 0.038), whereas adult onset was associated with thoracic (p = 0.026) and cervical spine (p = 0.026) involvement and positive family history (p = 0.044). Positive HLA-B27 was associated with ankle involvement (p = 0.007) and heel enthesitis (p = 0.013).

CONCLUSION

In this population women showed a milder axial involvement, Caucasian race presented axial and peripheral involvement similar to African-Brazilians, juvenile onset AS was associated with articular involvement of the lower limbs, and positive HLA-B27 was associated with ankle involvement.

Epitope recognition and T cell receptors in recurrent autoimmune anterior uveitis in Lewis rats immunized with myelin basic protein

Lewis rats immunized with myelin basic protein (MBP) develop experimental autoimmune encephalomyelitis (EAE) and associated anterior uveitis (AU). Rats recover and become resistant to further reinduction of EAE. We investigated whether the resistance to reinduction of EAE was associated with the resistance to AU in LEW rats reinjected with MBP. We demonstrated that while rats remained resistant to EAE, they become susceptible to uveitis after recovery, and suffered a second episode of disease. The susceptibility to reinduced disease was associated with the recognition of new MBP epitopes. In contrast to the initial episode of AU, TCR Vbeta8.2 predominance was not observed in the iris/ciliary body. Our results suggest that T cells specific for MBP, which are rapidly reactivated when re-exposed to antigen, are sufficient to induce clinical uveitis in LEW rats. This process may involve a shifting of T cell specificity from the major encephalitogenic peptide utilizing the Vbeta8.2 receptor to a more diverse cell repertoire.

Nationwide collaborative study of HLA class II associations with distinct types of juvenile chronic arthritis (JCA) in Greece

The aim of this study was to investigate the association of different groups and subgroups of juvenile chronic arthritis (JCA) with HLA class II (DR, DP, DQ) alleles and/or haplotypes. Groups and subgroups were mainly distinguished on the basis of the type of onset, the course and complications of the disease, and some predefined disease markers according to the criteria proposed by the ILAR Standing Committee (Chile, 1994). On the basis of these criteria the following five JCA groups and their subgroups were included in the study: (1) define systemic onset (n = 25) and systemic progressing to persistent arthritis (n = 14); (2) JCA of oligoarthritis onset (O-JCA, n = 124) and of oligoarthritis onset and course (n = 98), O-JCA of early (< 6 years) or late (> 6 years) onset (EOO-JCA n = 71 and LOO-JCA n = 44), O-JCA with ANA positive (n = 69) or negative (n = 55) and O-JCA progressing to extended arthritis (n = 22); (3) JCA of polyarthritis onset (P-JCA) with rheumatic factor (RF) negative (n = 29), and P-JCA RF negative with antinuclear antibodies (ANA) positive (n = 13) or negative (n = 16); (4) JCA complicated with chronic anterior uveitis (CAU, n = 32); (5) juvenile psoriatic arthritis (n = 20). To assess the HLA allele frequencies in the above 223 Greek children with JCA, these frequencies were compared to those of 98 age-matched and 250 adult controls. The main findings were the following. A common HLA-DRB1* allele was not involved in the JCA groups and subgroups studied; on the other hand, the DQA1*0501 allele was found to be associated with different JCA groups/subgroups (O-JCA, P-JCA RF-negative ANA-positive, JCA with CAU), probably suggesting a closer relationship of this locus with the immunogenetic background of JCA. The DPB1*0201 allele was associated with the development of either EOO-JCA or CAU. Susceptibility to CAU was stronger when the DPB1*0201 was combined with the presence of DRB1*13. Another allele, DQB1*0301, was also associated with O-JCA and CAU. Finally, no specific HLA class II allele was found to be related to the presence of ANA or psoriatic lesions or to the severity of the arthritis. Our findings suggest that the wide clinical and laboratory spectrum of JCA is associated with an immunogenetic background that is linked with HLA alleles of more than one locus. Some of them, such as the DPB1*0201 allele, confer susceptibility to certain clinical onsets and courses or complications of the disease. The rapidly advancing techniques of typing of DNA profiles may lead to more definite conclusions.

HLA-B27 subtypes in patients with ankylosing spondylitis (As) in Colombia

OBJECTIVE

We investigated the distribution of HLA-B27 subtypes in patients with ankylosing spondylitis (AS) belonging to two ethnic groups of Colombia.

MATERIAL AND METHODS

PCR-SSOs was used to detect the polymorphism in exons 2 and 3 of HLA-B27 in two groups of patients: 39 Mulattos and 20 Mestizos. Fifty-nine of them suffered of ankylosing spondylitis (AS), including two patients with ankylosing spondylitis plus anterior uveitis (AU). Only two out of eight HLA-B27 subtypes studied (B*2701-B*2708) were found.

RESULTS

The distribution of these alleles in the whole population was: B*2705: 87.1% and B*2702: 12.8% in the Mulattos group; 80% were B*2705 and 20% B*2702 in Mestizos group. The distribution of HLA-B27 subtypes was: 84.74% of patients with AS were B*2705 and 15.26% B*2702.

CONCLUSIONS

There was no significant difference in the distribution of HLA-B27 subtypes among the patients ethnic groups studied. Other authors have shown that B*2705, B*2702 and B*2704, the more frequent subtypes, are equally associated to the disease. Although population studies need to be done to analyze the distribution of subtypes between patients and controls, the low frequency of HLA-B27 within the normal population does not permit to do a representative number of controls; our results suggest that HLA-B*2705 and HLA-B*2702 are the subtypes more frequently associated with AS in patients from the two more prevalent patients ethnic groups in Colombia.

HLA-B27 subtypes and HLA class II alleles in Japanese patients with anterior uveitis

PURPOSE

Some patients with anterior uveitis (AU) have ankylosing spondylitis (AS) and are HLA-B27 class I-positive. The purpose of this study was to investigate whether there are differences in HLA at the allele level among each group of patients with AU.

METHODS

Seventy-three patients with AU were studied. They were classified into three groups: 31 with AS-associated AU, 14 with HLA-B27-associated AU, and 28 with idiopathic AU. Three control groups without AU were used: 138 random subjects, 33 HLA-B27-positive healthy subjects, and 19 HLA-B27-positive patients with AS. DRB1 and DQB1 genotyping was performed using polymerase chain reaction (PCR)-single-strand conformation polymorphism (PCR-SSCP) and PCR-restriction fragment length polymorphism. HLA-B27 subtype was determined by PCR-SSCP.

RESULTS

There was no difference in the frequency of any class I antigen except HLA-B27 among the patients studied. The frequencies of HLA-DR12 in AS-associated AU and HLA-DR1 in HLA-B27-associated AU showed an increase. In HLA-B27-associated AU, DRB1*0101 and DQB1*0501 were increased compared with HLA-B27-positive control subjects. When HLA-B27 subtype distribution was compared among the groups, the proportion of B*2704 was significantly lower in HLA-B27-associated AU (P = 0.037), however, such a difference was not present in AS-associated groups.

CONCLUSIONS

These results indicated that B*2704 seemed to be less susceptible to AU compared with B*2705 in Japanese subjects. The increase of HLA-DR12 and HLA-DR1 in AU may be caused by linkage disequilibrium with B*2704 and B*2705, respectively.

Tumor necrosis factor-alpha is not essential in endotoxin induced eye inflammation: studies in cytokine receptor deficient mice

OBJECTIVE

Anterior uveitis frequently occurs in association with specific systemic inflammatory diseases. Interleukin 1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) have been implicated in the pathogenesis of these diseases. We evaluate the need for these cytokines in a model of anterior uveitis.

METHODS

Endotoxin was injected into the vitreous of mice deficient in IL-1 receptor type I, TNF receptors p55 and p75, both IL-1R1 and TNFR p55, or controls. Eyes were harvested after 24 h for histology and IL-6 bioassays or after 3 h for reverse transcriptase-polymerase chain reaction analysis of mRNA for specific cytokines or enzymes.

RESULTS

No significant difference in the number of infiltrating cells was found in TNFR p55/p75 deficient mice compared to controls in any of 4 separate experiments or in the combined data (p = 0.8). The number of infiltrating cells was significantly reduced in 2 of 4 experiments with IL-1R1 deficient mice (p < 0.001 based on combined data from 4 studies). IL-1R1/TNFR p55 deficient mice had a reduction in infiltrating cells in 2 of 3 experiments (p < 0.001 based on combined data from all studies). IL-6 levels were not significantly reduced in either of 2 experiments with TNFR p55/p75 deficient mice, but were reduced in one of 2 experiments with IL-1R1-/- mice (p = 0.02) and in one experiment with IL-1R1/TNFR p55 deficient mice (p = 0.01). In response to endotoxin, all 3 receptor deficient lines increased mRNA levels for IL-1-alpha, IL-10, TNF-alpha, IL-1 receptor antagonist, and inducible nitric oxide synthase.

CONCLUSIONS

IL-1 appears to have a more pivotal role in endotoxin induced uveitis than TNF-alpha, although neither cytokine is essential. Deletion of receptors for both cytokines has the most consistent effect, which is in accord with the hypothesis that these cytokines are, at least in part, functionally redundant.

TAP polymorphism is not associated with ankylosing spondylitis and complications with acute anterior uveitis in HLA-B27-positive Japanese

HLA-B27 is associated with the etiology of ankylosing spondylitis (AS) and acute anterior uveitis (AAU). Transporter associated with antigen processing (TAP) 1 and TAP2 polymorphism influences the range of peptide presented by HLA class I molecules. In this report, contribution of TAP polymorphism to the susceptibility to AS and AAU was studied in HLA-B27-positive Japanese individuals. Patients were classified into three groups: 16 AS patients, 14 AAU patients and 22 patients with both AS and AAU. Twelve HLA-B27-positive healthy individuals were included as a control. TAP polymorphism was detected by PCR-RFLP methods. Significant differences in frequencies of TAP1 alleles were not found between patient groups. None of the TAP2 frequencies showed increased or decreased frequencies compared with HLA-B27-positive healthy controls. In comparison with a random Japanese control, TAP2D allele frequency was significantly increased in the AAU group, but failed to reach a significant level in a group consisting of the AAU-only patients and the patients with both AS and AAU. All of the patient groups were noted to have a significantly increased prevalence of the TAP2H allele as compared to random controls; however, the higher frequency of this allele was detected in HLA-B27 healthy controls as well. These observations suggest a linkage disequilibrium between TAP2D, TAP2H and HLA-B27 in Japanese.

Association between MICA gene A4 allele and acute anterior uveitis in white patients with and without HLA-B27

PURPOSE

Acute anterior uveitis is strongly associated with the HLA-B27 antigen and triggered by the involvement of some external factors. However, it is uncertain whether HLA-B27 itself or other gene(s) near the HLA-B region in a linkage disequilibrium with HLA-B27 predispose to this uveitis. We therefore investigated microsatellite polymorphism in the transmembrane region of the major histocompatibility complex class I chain-related gene A (MICA), located 47 kilobases (kb) on the centromeric side of the HLA-B gene on the short arm of chromosome 6 within 6p21.3.

METHODS

We examined the following patients for MICA gene polymorphism by means of polymerase chain reaction and subsequent automated fragment detection by fluorescent-based technology: 64 (37 HLA-B27-positive and 27 HLA-B27-negative) whites with acute anterior uveitis, 74 (67 HLA-B27-negative and 7 HLA-B27-positive) ethnically matched random controls, and 36 HLA-B27-positive healthy controls.

RESULTS

The microsatellite allele consisting of four repetitions of GCT/AGC (designated A4 allele) was present at the significantly higher phenotype frequency (71.9%) in the patient group than in the ethnically matched random control group (13.5%) (P < .0000001, corrected P < .0000001). The A4 allele was strongly linked to HLA-B27 in a white population. However, the A4 allele was also found at the significantly higher phenotype frequency (37.0%) even in the HLA-B27-negative patient group than in the ethnically matched HLA-B27-negative control group (4.5%) (P = .0086, corrected P = .043).

CONCLUSIONS

These results suggest that the MICA gene itself or other nearby gene(s) linked to the MICA A4 allele may be involved in the development of acute anterior uveitis in a white population.

Outcomes in anterior uveitis associated with the HLA-B27 haplotype

OBJECTIVE

This study aimed to test the hypothesis that patients presenting with anterior uveitis who are HLA-B27 positive, either with or without associated systemic disease, have a less-favorable outcome than do patients with idiopathic anterior uveitis who are HLA-B27 negative.

DESIGN

Retrospective case-controlled series.

PARTICIPANTS

Ninety-seven patients who were HLA-B27 positive with no systemic disease, 94 patients who were HLA-B27 positive with systemic disease, and 72 patients who were HLA-B27 negative who presented with anterior uveitis were studied.

MAIN OUTCOME MEASURES

Ocular complications (e.g., secondary glaucoma, cataract formation, pupillary synechiae, vitritis, cystoid macular edema, and optic disc edema), medical and surgical treatment, number of recurrent attacks, and final visual acuity were recorded for all patients.

RESULTS

The patients who were HLA-B27 positive, either with or without systemic disease, experienced a greater number of complications than did the patients who were HLA-B27 negative. Periocular corticosteroids, systemic corticosteroids, and systemic immunosuppressive chemotherapy were required in a far greater number of HLA-B27-positive patients than in HLA-B27-negative patients (60% vs. 11%, 53% vs. 7%, and 18% vs. 1%, respectively; P < 0.001). The percentage of legally blind eyes was significantly greater in the HLA-B27-positive group, both with and without systemic disease, when compared with the HLA-B27-negative group (11% vs. 2%; P < 0.005).

CONCLUSIONS

The prognosis of anterior uveitis associated with the HLA-B27 haplotype, either with or without associated systemic disease, is less favorable when compared with that of HLA-B27-negative patients with idiopathic anterior uveitis.

MICA gene polymorphisms and HLA-B27 subtypes in Japanese patients with HLA-B27-associated acute anterior uveitis

PURPOSE

HLA-B27-associated acute anterior uveitis (HLA-B27 AAU) seems to be triggered by external factors in persons with a particular genetic background. It is still uncertain whether HLA-B27 or other gene(s) near the HLA-B region predisposes to uveitis in a linkage disequilibrium with B27. The authors investigated microsatellite polymorphism within the transmembrane region of the MICA gene, located 47 kb centromeric of the HLA-B gene, and HLA-B27 subtypes.

METHODS

Seventeen HLA-B27-positive Japanese patients with HLA-B27 AAU, 51 Japanese controls, and 20 B27-positive Japanese controls were examined for MICA gene polymorphism within the transmembrane region using polymerase chain reaction (PCR) and subsequent automated fragment detection by fluorescent-based technology. Furthermore, B27-positive patients with HLA-B27 AAU and B27-positive controls were examined for HLA-B27 subtypes by the PCR-sequence-specific primer method.

RESULTS

The microsatellite allele in the MICA gene, consisting of four repetitions of GCT/AGC (designated A4 allele), was present at a significantly higher phenotype frequency in the patient group (64.7%) than in the control group (25.5%) (chi 2 = 6.95, Pc = 0.042). Furthermore, the frequency of the A4 allele was significantly higher, even when compared with 20% in the B27-positive control group (chi 2 = 5.88, Pc = 0.042). The frequency of HLA-B27 subtypes was not significantly different between B27-positive patients with HLA-B27 AAU and B27-positive controls.

CONCLUSIONS

These results suggest that the MICA gene itself, or other nearby gene(s), linked to the MICA A4 allele may be involved in the development of HLA-B27 AAU and that HLA-B27 subtypes are not important in the development of HLA-B27 AAU in a Japanese population.

Interleukin-6 does not mediate endotoxin-induced uveitis in mice: studies in gene deletion animals

PURPOSE

Interleukin-6 (IL-6) has been strongly implicated in anterior uveitis based on its presence in aqueous humor from infected eyes and its inflammatory effects when injected intravitreally into rats. We used IL-6-deficient mice to test further the hypothesis that IL-6 contributes to the development of endotoxin-induced uveitis.

METHODS

Uveitis was scored by histologic analysis of C3H/HeN mice 24 hours after intravitreal injections of up to 200 ng of recombinant murine IL-6. Uveitis was similarly measured in IL-6-deficient mice and congenic controls 24 hours after intravitreal injection of 250 ng of Escherichia coli endotoxin. Reverse transcription-polymerase chain reaction was used to detect mRNAs for several cytokines at 3 hours postinjection. The IL-6 concentration in aqueous humor samples was determined with a bioassay using the murine B9 plasmacytoma cell line.

RESULTS

Direct injection of IL-6 did not induce uveitis. Mice genetically deficient in IL-6 developed endotoxin-induced uveitis that was comparable or more severe than congenic control mice. Compensatory changes in the expression of mRNA for other cytokines were not detected in irises from the IL-6-deficient mice. In IL-6-competent mice that received bilateral endotoxin injections, no correlation was found between the number of infiltrating cells in one eye and the IL-6 concentration in the aqueous humor of the contralateral eye.

CONCLUSIONS

In marked contrast to previous conclusions with rats, IL-6 was not sufficient for inducing uveitis in mice. Additionally, IL-6 was not necessary for the development of uveitis subsequent to intravitreal injection of endotoxin in mice.

The LMP2 polymorphism is associated with susceptibility to acute anterior uveitis in HLA-B27 positive juvenile and adult Mexican subjects with ankylosing spondylitis

INTRODUCTION

An association between polymorphism of the HLA linked LMP2 locus and the development of acute anterior uveitis (AAU) has previously been described in B27 positive white subjects with ankylosing spondylitis (AS). This study evaluated LMP2 alleles in two HLA-B27 positive Mexican populations of patients with spondyloarthropathy known to have a different clinical spectrum of disease from white people.

PATIENTS AND METHODS

The study populations consisted of 90 AS patients from Guadalajara with predominantly adult onset disease and 80 AS patients from Mexico City with predominantly juvenile onset disease. LMP2-CfoI amplified fragment length polymorphisms were determined after polymerase chain reaction amplification and digestion with CfoI restriction enzyme.

RESULTS

There was an increased LMP2A allelic frequency in patients who had had AAU in both Guadalajara (31.8%) and Mexico City (33.3%) when compared with non-AAU patients (15.2% and 17.7% of Guadalajara and Mexico City populations, respectively). The odds ratio relating LMP2A allelic frequency and AAU for the combined population, stratified by age at onset of disease, was 2.51 (p = 0.01). LMP2 alleles did not influence the age at onset of disease or the development of peripheral arthritis.

CONCLUSIONS

These data support the view that polymorphism at the LMP2 locus is associated with the development of AAU in B27 positive subjects with AS. The requirement for both the less common LMP2 allele and HLA-B27 is consistent with the low prevalence of AAU in Mexican patients with spondyloarthritis.

Keratouveitis--two families with a dominantly inherited disorder

Herein we describe a relapsing acute keratouveitis without known aetiology. The disorder has been found in two families and shows an autosomal dominant inheritance. Acute anterior uveitis can be traced for five generations in one of these families. In the same family there is also an association to an autosomal dominantly inherited vascular disorder (Osler-Rendu-Weber disease). The anterior uveitis has an acute onset, a recurrent pattern and a mild activity. The associated keratitis is seen as a midstromal thin flat disc in the central cornea, sometimes with folds in Descemet's membrane as a sign of oedema. This causes a change in refraction and a mild reduction of the corrected visual acuity. There is a prompt response to topical steroid treatment, but the corneal changes have in one case become permanent. Clinical documentation and the mode of inheritance is presented.

Non-HLA-B27 genetic factors in HLA-B27 associated diseases

Family and twin studies showed that besides HLA-B27 other genetic factors are of significance for the pathogenesis of ankylosing spondylitis, reactive arthritis or acute anterior uveitis. There are up to now no strong indications that any subtype of B27 is especially associated with these diseases. Also the indications that B2703 and B2706 are protective should be further substantiated. HLA-B27/HLA-B60 heterozygotes have a three times higher risk to develop ankylosing spondylitis as persons with another B type opposite B27. Haplotype studies made it unlikely that the other genetic factors are situated on chromosome 6p. Studies on 23 other genetic marker systems were all negative in this respect.

Experimental autoimmune anterior uveitis. Induction with melanin-associated antigen from the iris and ciliary body

PURPOSE

This study was designed to investigate an animal model of uveitis that resembles anterior uveitis in humans after immunization with iris-ciliary body antigen.

METHODS

Male Lewis rats 6 to 8 weeks of age were immunized with the buffer- and detergent-insoluble bovine iris-ciliary body antigen mixed with complete Freund's adjuvant and pertussis toxin. Antigen was digested with various proteolytic enzymes and tested in different rodent strains for a uveitogenic response.

RESULTS

Acute iridocyclitis developed in both eyes of the Lewis rat during the second week after immunization, and the pattern of inflammation was similar to acute anterior uveitis in humans, with sudden onset, localization to the anterior uvea, and spontaneous resolution. Among the strains tested, F344 rats were susceptible to experimental autoimmune anterior uveitis but Long-Evans rats were not. Experimental autoimmune anterior uveitis did not develop in any of the mice studied, nor was it induced by immunization with synthetic melanin, amelanotic bovine tissues, pigmented bovine skin, or pigmented rat and rabbit iris-ciliary body. A soluble fraction derived from bovine melanin-associated antigen (BMAA) after digestion with the proteolytic enzyme V8 protease resulted in a disease similar to that observed with intact BMAA.

CONCLUSIONS

A model of anterior uveitis has been induced in the Lewis rat after immunization with bovine uveal antigen, and it resembles the acute iridocyclitis observed in humans. These results suggest that the pathogenic antigen is a melanin-associated protein(s) present within the iris-ciliary body.