Immunity to soluble retinal antigen in patients with uveitis accompanying juvenile rheumatoid arthritis

Describing the Clinical and Laboratory Features and HLA-B Pattern of Adult-Onset Idiopathic Autoimmune Uveitis at a Tertiary Hospital in South India: A Cross-Sectional Study

Introduction

There is a scarcity of information available on clinical and laboratory features of adult-onset idiopathic autoimmune uveitis. Therefore, we conducted a single centre descriptive cross-sectional study. Patients and Methods. A chart review of all patients with idiopathic autoimmune uveitis with onset after 18 years of age who were referred to the rheumatology department between January 2017 and December 2018 was performed. Their clinical features, demographic features, and HLA-B genotypes were documented and described.

Results

Out of 210 patients referred to rheumatology, 66 were found to have uveitis, and 16 of these had an adult-onset idiopathic autoimmune uveitis. Apart from a slight female preponderance (62.5%), our patients were characterized by a high proportion of panuveitis (4 out of 16, i.e., 25%). There was an increased frequency of occurrence of synechiae (5 out of 16, i.e., 31.3%), retinal vasculitis (4 out of 16, i.e., 25%), optic disc edema (3 out of 16, i.e., 18.8%), and cystoid macular edema (seen in 2 patients, i.e., 12.5%). These features correlated with the anatomical subtypes. Retinal vasculitis and optic disc edema present in three fourth of all panuveitis cases were the most prominent features. The odds of finding HLA-B∗35 in retinal vasculitis were 33 times higher than odds of finding it in idiopathic autoimmune uveitis patients not having retinal vasculitis (OR 33; 95% CI 1.6–698).

Conclusion

Idiopathic autoimmune uveitis in our patients is characterized by a high frequency of panuveitis and retinal vasculitis, and complications with a probable association between HLA-B∗35 and retinal vasculitis.

Past and Present Behçet's Disease Animal Models

Behçet's disease (BD) is presumably an autoinflammatory disease of unknown etiology for which several animal models have been described over the years. Agents and methods used for the development of these models have ranged from the herpes simplex type one virus (hsv-1) pathogen to the use of transgenic mice. Other models have also been used to investigate a possible autoimmune component. Each model possesses its own unique set of benefits and shortcomings, with no one model fully being able to recapitulate the disease phenotype. Here, we review the proposed models and provide commentary on their effectiveness and usefulness in studying the disease.

Recent advances in uveitis of juvenile idiopathic arthritis

Chronic scarring-type uveitis is a frequent extra-articular manifestation of juvenile idiopathic arthritis. It occurs in about 20% of children with this disease, commencing typically within a few years from its onset. The risk of uveitis is greatest in antinuclear antibody-positive girls with early onset oligoarthritis. The classic clinical picture is chronic bilateral anterior uveitis, usually asymptomatic until substantial damage to intraocular structures occurs. In view of the asymptomatic nature of the condition, routine screening of juvenile idiopathic arthritis patients 2-4 times a year is crucial to prevent complications. The treatment consists of topical corticosteroids and mydriatics, in severe cases with immunosuppressive agents, and surgical management of complications. Although the prognosis of uveitis is improving, there are cases refractory to standard regimens. Patients in whom uveitis commences prior to the onset of arthritis present a special problem.

Inflammatory arthritic process, iridocyclitis and immune response to articular and ocular antigens in Wistar rats injected with T. gondii trophozoites

The present study deals with the potential role of T. gondii in inducing an arthritic inflammatory process. Wistar rats were injected subcutaneously (sc) into the right footpad with viable T. gondii trophozoites emulsified in incomplete Freund's adjuvant (IFA). The control group was injected with IFA. All parasite-injected animals developed a local inflammatory process characterized by hind limb swelling and marked restriction of ankle motility approximately 25 days after injection. Histopathogical studies of the joints, carried out 90 days after injection, revealed intense mononuclear infiltration, proliferation of granulation tissue, giant cells and necrosis in the synovia of 90% of T. gondii-injected rats. Strikingly, 40% (4/10) of the parasite-injected animals developed iridocyclitis, which was characterized by intense mononuclear infiltration around the iris-ciliary microvasculature in two animals and a slightly pronounced infiltrate of polymorphonuclear and mononuclear cells in two other animals. Antibodies to soluble T. gondii antigens (STAg) were detected in all parasite-injected rats. Antibodies against articular and ocular antigens such as proteoglycans, type II collagen, retinal S antigen and iris antigens were detected by ELISA in 40, 80, 70 and 70% of T. gondii -injected animals, respectively. Control animals injected with IFA failed to develop any articular or ocular process or humoral immune response. The present study demonstrated that footpad sc injection of Wistar rats with viable T. gondii trophozoites was able to induce a localized inflammatory arthritic process which, in some of the animals, was accompanied by iridocyclitis and immune response against articular and ocular components.

Juvenile rheumatoid arthritis in India--rarity of antinuclear antibody and uveitis

Juvenile chronic arthritis is a heterogeneous disease, having different subtypes. Among our 89 patients with juvenile chronic arthritis, we did not find even one patient with early onset pauciarticular disease with uveitis and antinuclear antibody positivity. Further, the prevalence of anti-nuclear antibodies and anti-histone antibodies was very low whereas the prevalence of rheumatoid factor was similar to that reported from Western countries. Thus, the spectrum of juvenile chronic arthritis in India differs from that seen in the west. Larger population based studies of the disease are thus needed.

Cellular immune responses of patients with juvenile chronic arthritis to retinal antigens and their synthetic peptides

The objective of this study was to determine the proliferative responses of peripheral blood lymphocytes of ocular antigens like retinal S-antigen, peptides M and G of S-antigen, yeast histone H3 peptide 106-121 homologous to peptide M and peptide R16 of interphotoreceptor retinoid binding protein (IRBP) in children with juvenile chronic arthritis (JCA). We have studied the in vitro proliferative response of peripheral blood lymphocytes from 41 patients with JCA (10 with and 31 without uveitis) and 23 healthy controls against the above antigens. The responders were retested after 1 or 6 months. Fifty (5/10) and 9.7% (3/31) of JCA patients with and without uveitis, respectively, responded (stimulation index > 3) to S-antigen or one of its peptide listed above or yeast histone H3 peptide or R16 of IRBP. None of the healthy controls responded to any of these antigens. The difference in the frequency of responders (SI > 3) between JCA associated with uveitis and healthy controls was statistically significant (p = 0.001). Similarly, the difference between JCA with and without uveitis was also significant (p = 0.013). Our findings suggest that these antigens may have a role in the pathogenesis of uveitis in a subset of patients with JCA.

The relative distribution of B35 alleles and their IEF isotypes in a HLA-B35-positive population

The HLA-B35 serotype represents a group of antigens detectable by IEF, cytotoxic T cells, and by sequencing analysis. Four isotypes and eight alleles have been thus far reported. We have determined the relative frequencies of these B35 subtypes in a group of 203 unrelated people. Dot blot hybridization of PCR amplified products was performed using 23 sequence-specific oligo probes designed based on the EMBL HLA class I sequence database. The amplification was achieved by a pair of group-specific primers, producing approximately 600 bp fragments. By hybridization pattern analysis, we found that four alleles represent over 95% of the B35+ population, with relative frequency of 48.2% for B*3501, 23.7% for B*3502, 15.2% for B*3503, and 8.0% for B*3508. We also identified 3 individuals with B*3504 and one with B*3505, and seven samples with new patterns. B*3501 and B*3503 exactly correlated with the most common isotype B35.3, B*3502 and B*3504 with B35.2, B*3508 may be the B35.1 IEF isotype. The B*3505 was identified from an individual with B35 IEF variant form. Our study shows that the B35 antigen has a wide distribution of alleles, and that many more B35-related alleles may yet to be uncovered.

Acute anterior uveitis: clinical and experimental aspects

Acute anterior uveitis (AAU) or iritis is an inflammatory disorder of the anterior structures of the eye that may be associated with a number of disease entities. A significant proportion of patients will have no evidence of an underlying disorder and are labeled as idiopathic. Within this group approximately 50% will possess the human leukocyte antigen, HLA-B27, and some will have an associated spondyloarthropathy such as ankylosing spondylitis or Reiter's syndrome. Nevertheless, a number of HLA-B27-positive patients have no apparent underlying rheumatic disorder. The potential interplay of HLA-B27 and certain infective agents in the pathogenesis of AAU is discussed with particular reference to Yersinia species. Presentation of a uveitogenic peptide, similar to the arthritogenic peptide model in spondyloarthropathies, may be a mechanism involved in the development of AAU. Experimental models in animals have increased our understanding of the roles of retinal proteins and bacterial peptides, as well as T cells and cytokines, in the pathogenesis of uveitis. As in animal models of arthritis, certain retinal peptides (in conjunction with adjuvant therapy) can induce uveitis in animals. The treatment of isolated AAU usually involves topical medication and the prognosis is good. Occasional cases, especially those associated with systemic disorders, may require the addition of systemic corticosteroids or other immunosuppressive medications.

Immunological aspects of juvenile rheumatoid arthritis

This article reviews the evidence from recent studies on immunological abnormalities associated with pathophysiologic mechanisms operating in three clinical subtypes of juvenile rheumatoid arthritis (JRA) (polyarticular, pauciarticular and systemic). The main discussion is focused on three hallmarks of immunopathological studies. First, abnormalities in phenotype and function of lymphocytes from peripheral blood and inflamed synovium are discussed. The aberrations of lymphocytes are elucidated by T and B cells expressing phenotypic cell-markers such as CD20, CD21, CD4, CD8 and DR in association with different subtypes and disease activity. The functional imbalance and impairment of T and B cells are mainly observed by abnormal proliferation and/or in vitro Ig production in response to mitogens and alloantigens. Second, because the appearance of rheumatoid factors (RF) in serum indicates that the pathogenesis of JRA may be based on the autoimmune mechanism, the prevalence of RF including IgM, IgA and IgG isotype, hidden IgM RF and cross-reactive idiotype RF, and their characteristic properties are discussed. Moreover, specific auto-antibodies (antinuclear antibodies and others) for JRA are illustrated in this paper. Third, the production of various pro-inflammatory cytokines resulting in the release of tissue-damaging chemical mediators is also discussed. This may play a central role in the generation of systemic inflammation and joint involvement in JRA.

Serum antiocular antibodies in patients with juvenile rheumatoid arthritis

Although the uveitis associated with juvenile rheumatoid arthritis (JRA) is presumed to have an autoimmune etiology, its pathogenesis is unknown. We utilized immunohistochemical techniques to detect the presence of serum antibodies directed against ocular tissues in these patients. The staining patterns of serum from patients with JRA, with and without uveitis, were compared with normal controls. Antibodies directed against epitopes in iris and ciliary body basement membranes, lens epithelium and fibers, Bruch's membrane, and iris and retinal blood vessels were observed in the sera of several individuals. These staining patterns were statistically more frequent among the pauciarticular and polyarticular JRA patients, with and without uveitis, than either the systemic JRA or normal populations. These results demonstrate the presence of antiocular antibodies in the sera of JRA patients, with and without uveitis. Whether those nonuveitic JRA patients with antiocular antibodies will develop uveitis is unknown at this time.

Autoantibody studies in juvenile rheumatoid arthritis

Early studies showed few immunologic abnormalities in juvenile rheumatoid arthritis (JRA) patients. There were no specific laboratory markers useful for diagnosis and assessment of the course of disease in JRA. Previous work showed an association of antinuclear antibodies (ANA) with early-onset pauciarticular disease and iridocyclitis. Similarly, the presence of 19S immunoglobulin (Ig) M rheumatoid factors (RF) was associated with late-onset polyarticular disease in girls. More recent studies have detected many unique autoantibodies. Newer assays show 19S IgM RF in up to 35% of JRA patients, although still mainly in girls with late-onset polyarticular disease. Hidden 19S IgM RF can be shown in up to 75% of JRA patients using different procedures, primarily in those with active polyarticular-or pauciarticular-onset disease. Immune complexes have been detected in JRA patients by means of different techniques; their presence usually correlates with active disease. Studies on a specific ANA in JRA have shown no common extractable nuclear antigen, but antihistone antibodies have been found in up to 75% of cases, again mainly in those with pauciarticular onset and iritis. Finally, a variety of unusual immunologic proteins have also been detected, including anti-ocular, anti-cellular, anti-cardiolipin, anti-perinuclear factor, and anti-collagen antibodies. This review evaluates the significance of these antibodies that can now be found in JRA.

Anterior uveitis in children. An analysis of 75 cases with special reference to retinal anti-S antibodies

In this prospective study of childhood uveitis, 75 children with anterior uveitis were analyzed to determine whether a relationship could be found between the occurrence of uveitis, its clinical features, and humoral immunity to retinal S-antigen. For the purposes of analysis, children were divided into acute (18 cases) and chronic (57 cases) categories, depending on the duration of ocular inflammation. Clinical features of both of these groups were compared and significant differences were found in the occurrence of unilateral vs bilateral involvement, the incidence of complications, and visual outcome. Serum samples from children with acute (7 cases) and chronic uveitis (28 cases) and from healthy children (132 cases) were tested for antibodies to S-antigen by enzyme-linked immunosorbent assay (ELISA). A statistically significant difference in the level of specific antibodies between patients with chronic uveitis and controls was found. However, there was no difference between children with acute uveitis and healthy patients, nor was there any correlation between the severity of uveitis and antibody titer. For further elucidation of the significance of circulating anti-S antibodies, 14 children with chronic anterior uveitis were followed for as long as 18 months after the initial visit. Multiple serum antibody titers to bovine retinal S-antigen were determined and compared with the clinical activity at the time of each sampling. In only 6 of 14 patients did the titers to S-antigen tend to decrease with clinical improvement and stabilize at titers somewhat higher than normal values.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies in patients with juvenile chronic arthritis and their immediate family relatives

Antibodies to nuclear antigens were assessed in 23 children with juvenile chronic arthritis (JCA) and 66 of their first degree relatives. Serum samples from 16 patients with JCA (70%) and nine relatives (14%) had antinuclear antibodies by indirect immunofluorescence. Antibodies against nuclear antigens in rabbit thymus extract or an erythroblastoid cell line (K562) were detected by countercurrent immunoelectrophoresis and immunoblotting in 16 patients (70%) and 39 family relatives (59%). Immunoblotting did not show any banding patterns common to all patients with JCA, though bands in the 43-45 kD range were detected in 5/23 patients. Anticardiolipin antibodies were found in 7/23 patients. In total, 18/20 families (90%) had members other than the probands with detectable autoantibodies. In five families immunoblotting showed common banding patterns between the probands and other members. This suggests that there might be an inherited trend towards autoimmune responses in some families of patients with JCA.

Serum antibody response to human and bovine IRBP in uveitis

Interphotoreceptor retinoid binding protein (IRBP) is a 136,000 molecular weight photoreceptor cell protein capable of inducing an experimental autoimmune uveitis (EAU) in susceptible animal strains. The occurrence of serum antibodies against human (Hu) or bovine (Bo) IRBP was investigated in patients with uveitis and healthy controls. A sensitive ELISA detected anti-IRBP in approximately 50% of patients and controls, without apparent differences in the mean level, titre or avidity and irrespective of the origin of the antigen. Although the correlation (p less than 0.001) between anti-HuIRBP and anti-BoIRBP levels in uveitis sera suggested the presence of crossreacting antibodies, these sera also contained antibodies specific for either the human or the bovine antigen. The only difference between patients and controls was the greater ability of antibodies in uveitis sera (p less than 0.05) to recognize a synthetic peptide of HuIRBP, which induces severe EAU in rats. We conclude that autoantibodies to IRBP occur naturally in man and are not increased in patients with uveitis.

Autoantibody profile in juvenile chronic arthritis

Patients with juvenile chronic arthritis (JCA) may be subdivided into a minority, who carry IgM rheumatoid factor and have erosive polyarthritis resembling adult rheumatoid arthritis, and the majority (90%), who are seronegative by conventional means. Between 30 and 60% of patients with JCA have positive antinuclear antibodies (ANAs) according to the choice of substrate for indirect immunofluorescence. The importance of ANAs is the frequent development of associated asymptomatic chronic iridocyclitis, which may impair vision causing worse handicap than the arthritis, which remains predominantly pauciarticular in two thirds of these young children. ANA positive patients rarely possess antibodies to deoxyribonucleic acid (DNA) or extractable nuclear antigens (ENA), and current studies suggest that several different nuclear antigens, including histones, may be involved.

Assignment of several epitopes to cyanogen bromide peptides of bovine retinal S-antigen by immunoblotting with peptide-specific antibodies

Peptide fragments of bovine S-antigen, an immunopathogenic retinal autoantigen which mediates experimental autoimmune uveoretinitis, were produced by cyanogen bromide cleavage and used to study antibody-defined epitopes, primarily those defined by antibodies from Lewis rats immunized with the intact antigen or various peptide fragments purified from the digests by HPLC. Antibodies from the sera have been affinity-purified on several of the peptides and examined by western blot analysis and enzyme-linked immunosorbent assay on S-antigen, digests and purified fragments. By immunoblotting it could be shown that five of the purified peptides, CB46, CB47, CB67, CB74 and CB123 were immunogenic, eliciting antibodies which recognized the peptides to which they were prepared; all, except for CB67, elicited antibodies which also bound intact S-antigen. Two more peptides, CB14 and CB27 were not immunogenic and did not contain epitopes. An epitope was also found in CB35, a previously uncharacterized peptide. Using these procedures together with amino acid sequence and composition data, we have been able to determine the origins of the peptides which contain antibody epitopes, including those which we have previously determined to possess epitopes recognized by class II MHC-restricted T cell lines raised to S-antigen and several of the peptides. A T cell line specific for the non-uveitogenic CB47 peptide was unable to transfer the disease.