Molecular analysis of HLA class II genes in primary Sjögren's syndrome. A study of Israeli Jewish and Greek non-Jewish patients

Association of endometriosis with Sjögren's syndrome: Genetic insights (Review)

Patients with a history of endometriosis have an increased risk of developing various autoimmune diseases such as rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, multiple sclerosis and celiac disease. There is a potential association between endometriosis and an increased susceptibility for Sjögren's syndrome (SS). SS is a common chronic, inflammatory, systemic, autoimmune, multifactorial disease of complex pathology, with genetic, epigenetic and environmental factors contributing to the development of this condition. It occurs in 0.5‑1% of the population, is characterized by the presence of ocular dryness, lymphocytic infiltrations and contributes to neurological, gastrointestinal, vascular and dermatological manifestations. Endometriosis is an inflammatory, estrogen‑dependent, multifactorial, heterogeneous gynecological disease, affecting ≤10% of reproductive‑age women. It is characterized by the occurrence of endometrial tissue outside the uterine cavity, mainly in the pelvic cavity, and is associated with pelvic pain, dysmenorrhea, deep dyspareunia and either subfertility or infertility. It is still unclear whether SS appears as a secondary response to endometriosis, or it is developed due to any potential shared mechanisms of these conditions. The aim of the present review was to explore further the biological basis only of the co‑occurrence of these disorders but not their association at clinical basis, focusing on the analysis of the partially shared genetic background between endometriosis and SS, and the clarification of the possible similarities in the underlying pathogenetic mechanisms and the relevant molecular pathways.

Combination of sporadic inclusion body myositis and primary Sjцgren’s syndrome: clinical case and review of literature

The article presents a review of the literature and a clinical observation of a patient with long-term anamnesis of primary Sjцgren's syndrome (SS) in combination with sporadic inclusion body myositis (sIBM). The diagnosis of SS was confirmed in accordance with the Russian diagnostic criteria for SS 2001, as well as with the ACR 2012 and ACR/EULAR 2016 criteria. The diagnosis of sIBM was established on the basis of a characteristic clinical picture: the development of the disease in a woman after 50 years of age with slowly progressive asymmetric muscle weakness and a typical distribution, a moderate increase in the level of creatine phosphokinase (<10 norms for the entire observation period), the presence of a generalized primary muscle process according to needle electromyography, a typical picture of muscle involvement according to magnetic resonance imaging, and the ineffectiveness of high doses of glucocorticoids. The absence of histological confirmation does not contradict the diagnosis, since morphological examination of muscles in patients with a typical course of the disease fails to detect characteristic signs of sIBM in 20% of cases.Currently, there is no effective pathogenetic therapy for sIBM. Understanding the mechanisms of sIBM development will allow to develop effective methods of its treatment.

Epitope Mapping of Pathogenic Autoantigens on Sjögren’s Syndrome-Susceptible Human Leukocyte Antigens Using In Silico Techniques

Sjögren’s syndrome (SjS) is characterized by lymphocytic infiltration and the dysfunction of the salivary and lacrimal glands. The autoimmune response is driven by the effector T cells and their cytokines. The activation of the effector helper T cells is mediated by autoantigen presentation by human leukocyte antigen (HLA) class II molecules of antigen-presenting cells. Studies using familial aggregation, animal models, and genome-wide association demonstrate a significant genetic correlation between specific risk HLAs and SjS. One of the key HLA alleles is HLA-DRB1*0301; it is one of the most influential associations with primary SjS, having the highest odds ratio and occurrence across different ethnic groups. The specific autoantigens attributed to SjS remain elusive, especially the specific antigenic epitopes presented by HLA-DRB1*0301. This study applied a high throughput in silico mapping technique to identify antigenic epitopes of known SjS autoantigens presented by high-risk HLAs. Furthermore, we identified specific binding HLA-DRB1*0301 epitopes using structural modeling tools such as Immune Epitope Database and Analysis Resource IEDB, AutoDock Vina, and COOT. By deciphering the critical epitopes of autoantigens presented by HLA-DRB1*0301, we gain a better understanding of the origin of the antigens, determine the T cell receptor function, learn the mechanism of disease progression, and develop therapeutic applications.

Myasthenia gravis, atypical polyneuropathy and multiple autoimmune phenomena in the same patient, with HLA-immunogenetic profile expectable for Greek chronic inflammatory demyelinating polyneuropathy: a case report

PURPOSE

The comorbidity of myasthenia gravis (MG), with other autoimmune disorders like systemic lupus erythematosus (SLE), is relatively frequent but the co-occurrence with chronic inflammatory demyelinating polyneuropathy (CIDP) along with various autoimmune manifestations in the absence of thymoma is of extreme rarity. Our aim is to report a case of a woman who presented the concomitant appearance of MG, axonal sensory-motor polyneuropathy and hepatitis that may indicate an underlying pathogenetic link among the different autoimmune disorders.

MATERIALS AND METHODS/RESULTS

We present a case of a 54-year-old woman, with a generalized MG and a chronic sensory-motor polyneuropathy, hypothyroidism, anaemia, hepatitis, livedo reticularis and facial flush, of assumed autoimmune background, like SLE, although with persistent negative ANA antibodies, from the beginning and through the whole following years. The Human Leukocyte Antigen (HLA)-DRB1 genotyping showed a profile of alleles (DRB1*11:01/11:04) compatible with CIDP of mainly female gender in Greece and frequencies close to those of Sjogren's syndrome and scleroderma's in the Greek population. The diagnostic problems, the atypical clinical, electrophysiological and immunological features are discussed, along with the rarity of the case, with this exceptional combination of autoimmune manifestations, which could be truly associated under the clinical umbrella of a systemic disease, like SLE. However, our patient did not ever fulfil the SLE criteria.

CONCLUSIONS

To raise awareness among clinicians about the exceptional combination of autoimmune manifestations driven by a specific HLA background.

Genetics of Sjögren's syndrome

The pathogenesis of Sjögren's syndrome has not been elucidated. There has been evidence that genetics play an important role in the development of this disease from earlier studies. However, till now only a number of genes have been identified to be associated with SS, and these have only a weak or moderate effect. In this review we summarize the findings of the genetics studies and emphasize the need of large multicenter projects that will increase the sample sizes to provide more meaningful associations, as is the case in other common autoimmune diseases.

Influence of geolocation and ethnicity on the phenotypic expression of primary Sjögren's syndrome at diagnosis in 8310 patients: a cross-sectional study from the Big Data Sjögren Project Consortium

Objectives

To analyse the influence of geolocation and ethnicity on the clinical presentation of primary Sjögren's syndrome (SjS) at diagnosis.

Methods

The Big Data Sjögren Project Consortium is an international, multicentre registry designed in 2014. By January 2016, 20 centres from five continents were participating. Multivariable logistic regression analyses were performed.

Results

We included 7748 women (93%) and 562 men (7%), with a mean age at diagnosis of primary SjS of 53 years. Ethnicity data were available for 7884 patients (95%): 6174 patients (78%) were white, 1066 patients (14%) were Asian, 393 patients (5%) were Hispanic, 104 patients (1%) were black/African-American and 147 patients (2%) were of other ethnicities. SjS was diagnosed a mean of 7 years earlier in black/African-American compared with white patients; the female-to-male ratio was highest in Asian patients (27:1) and lowest in black/African-American patients (7:1); the prevalence of sicca symptoms was lowest in Asian patients; a higher frequency of positive salivary biopsy was found in Hispanic and white patients. A north-south gradient was found with respect to a lower frequency of ocular involvement in northern countries for dry eyes and abnormal ocular tests in Europe (OR 0.46 and 0.44, respectively) and Asia (OR 0.18 and 0.49, respectively) compared with southern countries. Higher frequencies of antinuclear antibodies (ANAs) were reported in northern countries in America (OR=1.48) and Asia (OR=3.80) while, in Europe, northern countries had lowest frequencies of ANAs (OR=0.67) and Ro/La (OR=0.69).

Conclusions

This study provides the first evidence of a strong influence of geolocation and ethnicity on the phenotype of primary SjS at diagnosis.

Contribution of Genetic Factors to Sjögren's Syndrome and Sjögren's Syndrome Related Lymphomagenesis

We aimed to summarize the current evidence related to the contributory role of genetic factors in the pathogenesis of Sjögren's syndrome (SS) and SS-related lymphoma. Genes within the major histocompatibility complex (MHC) locus previously considered conferring increased susceptibility to SS development have been also revealed as important contributors in recent genome wide association studies. Moreover, genetic variations outside the MHC locus involving genes in type I interferon pathway, NF-κB signaling, B- and T-cell function and methylation processes have been shown to be associated with both SS and SS-related lymphoma development. Appreciating the functional implications of SS-related genetic variants could provide further insights into our understanding of SS heterogeneity, allowing the design of tailored therapeutic interventions.

The amino acid variation within the binding pocket 7 and 9 of HLA-DRB1 molecules are associated with primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is associated with HLA-DRB1 loci, but the association of amino acid variations in the hypervariable region of the HLA-DR β1 chain with pSS is largely unknown. In this study, we aimed to identify the amino acid variations within the hypervariable region of HLA-DRB1 molecule which are associated with the susceptibility to pSS. We sequenced the 2nd exon of the HLA-DRB1 locus in 52 pSS patients and 179 controls. The HLA-DRB1*0803 is the allele that shows the strongest association with pSS in Chinese population (OR = 3.0, P = 2.4 × 10(-4)). Furthermore, amino acid variations within the binding pocket P7 and P9 are associated with the susceptibility to pSS. An interaction between two residues within P7, β47 and β67, is associated with pSS. Structural modeling studies demonstrated that the electrostatics of peptide binding pocket 9 are opposite in pSS-susceptible and -protective HLA-DRB1 alleles. In conclusion, our results suggest that structural heterogeneity of the HLA-DRB1 peptide binding pocket P7 and P9 might play a role in the pathogenesis of pSS.

High-resolution HLA analysis of primary and secondary Sjögren's syndrome: a common immunogenetic background in Mexican patients

To compare the distribution of HLA-A, B, DRB1 and DQB1 alleles among Mexican patients with primary Sjögren Syndrome (pSS), secondary SS (sSS), connective tissue disease (CTD) without (w/o) SS and historical ethnically healthy controls. We included 28 pSS, 30 sSS, 96 CTD w/o SS patients and 234 controls. HLA-A, B, DRB1 and DQB1 were amplified and sequenced using the Allele SEQR Sequenced Based Typing Kits and analyzed on the ABI Prism*3130 DNA Analyzer using the Assign software. Gene frequencies were obtained by direct counting. Contingence tables of 2 × 2 were generated and analyzed by the Mantel-Haenzel χ (2) or Fisher's test (EPIINFO program). We reported odds ratios (OR) and corrected p values. SS patients showed increased frequencies of A*68:01 and DRB1*14:06 alleles when compared to CTD w/o SS (OR 4.43, 95 % CI 1.35-14.14, p = 0.007 and OR 14, 95 % CI 1.68-116, p = 0.001, respectively) and a higher prevalence of DRB1*01:01 (OR 5.9, 95 % CI 2.13-16.56, p = 0.003) and HLA-B*35:01 (OR 3.70, 95 % CI 1.92-7.12, p = 0.004) when compared with controls. pSS patients had a higher frequency of DRB1*14:06 allele than sSS (OR 16, 95 % CI 1.59-390, p = 0.001). Anti-Ro/SSA positivity was associated with B*51:01 (OR 10.11, 95 % CI 1.09-245, p = 0.02) and DRB1*03:01 alleles (OR 4.26, 95 % CI 1.01-18.89, p = 0.029), whereas the A*01:01 allele was associated with anti-La/SSB positivity (OR 4.75, 95 % CI 1.32-16.92, p = 0.003). In our population, the DRB1*14:06 allele was associated with primary and secondary SS implying that both varieties bear a similar immunogenetic background.

Sjögren's syndrome, the old and the new

Sjögren's syndrome is a chronic autoimmune disease characterised by progressive injury to exocrine glands accompanied by diverse extra-glandular manifestations. The spectrum of Sjögren's manifestations expanded in recent years to include new symptoms and signs such as small fibre neuropathy, and also well-defined activity and prognostic indexes. Similar to other non-organ-specific autoimmune diseases, a mosaic of factors have been linked with the development and appearances of Sjögren's syndrome. Progress has been made unravelling those factors, including susceptibility genes, immunological parameters and various environmental factors in the last decade, some of which may enable targeted therapies, biological and non-biological ones, for patients suffering from this disease. Thus, herein we review the postulated aetiologies, pathogenesis and new insights related to Sjögren's syndrome.

Novel aspects of Sjögren's syndrome in 2012

Sjögren's syndrome (SS) is a systemic progressive autoimmune disease characterized by a complex pathogenesis requiring a predisposing genetic background and involving immune cell activation and autoantibody production. The immune response is directed to the exocrine glands, causing the typical 'sicca syndrome', but major organ involvement is also often seen. The etiology of the disease is unknown. Infections could play a pivotal role: compared to normal subjects, patients with SS displayed higher titers of anti-Epstein-Barr virus (EBV) early antigens, but lower titers of other infectious agent antibodies such as rubella and cytomegalovirus (CMV) suggest that some infections may have a protective role against the development of autoimmune disease. Recent findings seem to show that low vitamin D levels in patients with SS could be associated with severe complications such as lymphoma and peripheral neuropathy. This could open new insights into the disease etiology. The current treatments for SS range from symptomatic therapies to systemic immunosuppressive drugs, especially B cell-targeted drugs in cases of organ involvement. Vitamin D supplementation may be an additional tool for optimization of SS treatment.

HLA and Sjögren's syndrome susceptibility. A meta-analysis of worldwide studies

The aim of this work was to identify common HLA Class II alleles contributing to primary Sjögren's syndrome (pSS) susceptibility worldwide and to analyze their biological implications through a binding prediction approach of peptides from major pSS auto-antigens. Case-control studies on HLA-DQ and HLA-DR in pSS were searched in various literature databases through April 2011 by a systematic review. The effect summary odds ratios and 95% confidence intervals were obtained by means of the random effect model. A total of 1166 cases and 6470 controls from 23 studies were analyzed. At the allelic level, DQA1*05:01, DQB1*02:01, and DRB1*03:01 alleles were found to be risk factors for disease. Conversely, the DQA1*02:01, DQA1*03:01 and DQB1*05:01 alleles were protective factors. The current study stresses the significant size effect HLA exhibits in the development of pSS. Analysis of susceptibility and protective alleles revealed physicochemical differences in critical amino acids located within the antigen-binding groove of DRβ, DQα and DQβ chains, allowing us to infer a mechanistic approach to understand the role of HLA in pSS and other autoimmune diseases.

Antineutrophil cytoplasmic antibodies testing in a large cohort of unselected greek patients

Objective. To retrospectively evaluate ANCA testing in a cohort of unselected Greek in- and outpatients. Methods. In 10803 consecutive serum samples, ANCA were tested by indirect immunofluorescence (IIF) and ELISA. ELISA in inpatients was performed only on IIF positive sera. Results. Low prevalence (6.0%) of IIF positive samples was observed. Among these samples, 63.5% presented perinuclear (p-ANCA), 9.3% cytoplasmic (c-ANCA) and 27.2% atypical (x-ANCA) pattern. 16.1% of p-ANCA were antimyeloperoxidase (anti-MPO) positive, whereas 68.3% of c-ANCA were antiproteinase-3 (anti-PR3) positive. Only 17 IIF negative outpatients' samples were ELISA positive. ANCA-associated vasculitides (AAV), connective tissue disorders and gastrointestinal disorders represented 20.5%, 23.9%, and 21.2% of positive results, respectively. AAV patients exhibited higher rates of MPO/PR3 specificity compared to non-AAV (93.8% versus 8%). Conclusions. This first paper on Greek patients supports that screening for ANCA by IIF and confirming positive results by ELISA minimize laboratory charges without sacrificing diagnostic accuracy.

Sjögren's syndrome associated with systemic lupus erythematosus: Clinical and laboratory profiles and comparison with primary Sjögren's syndrome

OBJECTIVE

To address the clinical, serologic, pathologic, and immunogenetic features of sicca syndrome that occurs in systemic lupus erythematosus (SLE), as well as its similarities to, and differences from, sicca syndrome that occurs in primary Sjögren's syndrome (SS).

METHODS

A cohort of 283 consecutive unselected SLE patients was evaluated for the presence of associated SS using the American-European classification criteria. Clinical and laboratory parameters in SLE patients with SS (SLE-SS) were compared with those in SLE patients without SS (SLE-no SS) and with a group of 86 unselected patients with primary SS.

RESULTS

SS was identified in 26 SLE patients (9.2%); the SS preceded the development of lupus in 18 of them (69.2%). Compared with the SLE-no SS group, patients with SLE-SS were significantly older, had a higher frequency of Raynaud's phenomenon, anti-Ro/SSA, anti-La/SSB, and rheumatoid factor, but had a significantly lower frequency of renal involvement, lymphadenopathy, and thrombocytopenia. Compared with the primary SS group, SLE-SS patients displayed a clinically similar sicca syndrome, but were significantly younger and had an increased frequency of perivascular infiltrates in the salivary glands associated with anticardiolipin antibodies in the serum. SLE-SS patients had a high frequency of the DRB1*0301 allele. This HLA profile distinguished the SLE-SS group from the SLE-no SS group, who had an increased frequency of DRB1*1501 and DQB1*0602 alleles, but was similar to the HLA profile of the primary SS group, who had an increased frequency of DRB1*0301.

CONCLUSION

SLE-SS appears to constitute a subgroup of patients with distinct clinical, serologic, pathologic, and immunogenetic features, in whom SS is expressed as an overlapping entity and is largely similar to primary SS.

Autoantibodies in primary Sjögren's syndrome: new insights into mechanisms of autoantibody diversification and disease pathogenesis

Characterisation of autoantibodies and their target autoantigens in primary Sjögren's syndrome (SS) is an important entry point for studying this common systemic autoimmune disease. Diversification of anti-Ro/La responses is believed to occur by a process of determinant spreading following initiation of an autoimmune response to one component, possibly 52-kD Ro (Ro52). Recent evidence supports the ER-resident chaperone Grp78 as a potential candidate in the initiation of an autoimmune response against Ro52, by binding to a Grp78 binding motif in the COOH-terminal region of Ro52. The subsequent diversification of the anti-Ro/La response is influenced by distinct HLA class II alleles. Anti-salivary duct autoantibodies have been revisited and shown to be mimicked by cross-reactive isoantibodies to AB blood group antigens. Identification of autoantibodies that act as antagonists at M3-muscarinic receptors represents an important advance. As well as contributing to the sicca symptoms, the functional effects of these autoantibodies may explain associated features of autonomic dysfunction in patients with SS. Anti-M3 receptor autoantibodies occur in both primary and secondary SS and allow Sjögren's syndrome to be viewed as a disorder of anti-receptor autoimmunity.

TAP, HLA-DQB1, and HLA-DRB1 polymorphism in Colombian patients with primary Sjögren's syndrome

OBJECTIVE

Although primary Sjögren's syndrome (pSS) has a worldwide distribution, little data is available on pSS immunogenetics in non-white populations. Thus, we investigated the influence of transporters associated with antigen processing (TAP), human leukocyte antigen (HLA)-DQB1, and HLA-DRB1 gene polymorphism in mestizo Colombian patients with pSS.

METHODS

In this cross-sectional and controlled study, all patients met the European criteria for classification of pSS. TAP and HLA typing was performed by polymerase chain reaction techniques. Genetic data analysis was performed to detect deviations from the expected Hardy-Weinberg (H-W) proportions and to determine the presence of population stratification or subdivision and the existence of linkage disequilibrium between pairs of loci.

RESULTS

Seventy-three Colombian patients with pSS (95% women) and 76 healthy controls were studied. Although significant associations were not observed between TAP or HLA polymorphism and disease, strong linkage disequilibrium among the loci TAP2 and DQB1 was found in patients. Deviations from the H-W expected value were found in the DQB1 locus of patients (P =.02). HLA-DRB1*0301-DQB1*0201 haplotype was associated with more severe histopathologic disease (odds ratio [OR], 15.5; 95% confidence interval [CI], 1.9-129; P =.001) and the presence of anti-Ro (OR, 3.8; 95% CI, 1-15; P =.04) and anti-La antibodies (OR, 4.3; 95% CI, 1.3-14; P =.01).

CONCLUSION

The data show genetic evidence suggesting that, in Colombians, a region immersed or in the vicinity in the HLA class II system is strongly associated with a predisposition to acquire pSS, which is probably located between the TAP2 and HLA-DQB1 locus. Our results confirm that the HLA-DRB1*0301-DQB1*0201 haplotype participates in the pathogenesis of pSS.

Clinical, immunological, and immunogenetic aspects of autoantibody production against Ro/SSA, La/SSB and their linear epitopes in primary Sjögren's syndrome (pSS): a European multicentre study

OBJECTIVES

To investigate the clinical and immunogenetic aspects of antibody formation against Ro/SSA and La/SSB as well as their linear B cell epitopes in patients with primary Sjögren's syndrome (pSS) from different European countries.

PATIENTS AND METHODS

Ninety patients with pSS from six European centres were studied. Serum samples from all patients were tested in a control laboratory for anti-Ro/SSA and anti-La/SSB autoantibodies by RNA precipitation assay and autoantibodies to the previously reported B cell linear epitopes of Ro 60 kDa (p169-190aa and p211-232aa) and La/SSB (p147-154aa, p291-302aa, p301-318aa, and p349-364aa). DNA from 88 patients was used for the determination of HLA-DRB1, -DQA1, and -DQB1 genotypes. Analysis of the results was performed in the 88 patients who were genotyped and tested also for antipeptide antibodies.

RESULTS

Antibodies to B cell epitopes of Ro 60 kDa were detected at a low frequency (range 10-37%). In contrast, B cell epitopes of La/SSB were detected frequently (range 58-86%) among the anti-La/SSB positive sera. Autoantibodies to the La/SSB epitope, p349-364aa, were significantly positively associated with longer disease duration (p<0.05), recurrent or permanent parotid gland enlargement (p<0.005), and a higher proportion of non-exocrine manifestations (p<0.005), compared with patients without autoantibodies. The presence of anti-Ro/SSA and anti-La/SSB autoantibodies was significantly associated with the presence of HLA-DRB1*03 and DQB1*02 (p=0.038 and p=0.034, respectively). This association was even more prominent and extended to HLA-DQA1*0501 when patients were stratified according the presence of autoantibodies to discrete La/SSB B cell epitopes in comparison with autoantibody negative patients (p<0.01). They were found also to be highly associated with the alleles HLA-DQB1*02 and HLA-DQA1*0501 as well as the presence of a shared amino acid motif in the region 59-69aa of DQB1 first domain (p<0.01, respectively).

CONCLUSIONS

Autoantibodies against La/SSB, binding to four synthetic peptides, derived from the sequence of the La protein were identified with increased frequency in sera of patients with pSS. The formation of autoantibodies against B cell epitope analogues of La/SSB in European patients with pSS may be dependent on the presence of a permissive HLA-DQ heterodimer, most prominently represented by the HLA-DQA1*0501/DQB1*0201 heterodimer, suggesting that a model of HLA restricted presentation of La/SSB peptide determinants is crucial for the autoimmune response against La/SSB.

HLA class I and class II are both associated with the genetic predisposition to primary Sjögren syndrome

Primary Sjögren syndrome (pSS) is an autoimmune disease characterized by progressive destruction of the exocrine glands leading to mucosal and conjunctival dryness. It is marked by lymphocytic infiltration of the glands and the accumulation of several types of autoantibodies such as rheumatoid factor (RF), antinuclear, anti-SS-A (anti-Ro) and anti-SS-B (anti-LA) autoantibodies. The susceptibility to pSS and/or the presence of SS-A/SS-B autoantibodies in pSS patients is associated with DRB1*03-DQB1*02 and DRB1*02-DQB1*06 haplotypes, whereas no associations have been described with any HLA class I allele. To define the impact of HLA class I alleles in predisposition to pSS, 46 patients responding to the European criteria and 222 healthy unrelated Caucasians were analyzed for their HLA class I and class II haplotypes. Our results confirm the association of the DRB1*03-DQB1*02 haplotype with SS-A/SS-B autoantibodies positive pSS and demonstrate a significant association of the HLA-A24 with the disease. Moreover, HLA-A24 is more often associated with DRB1*11-DQB1*0301 and/or DRB1*0301-DQB1*02 in pSS patients than in the controls. The novel association of HLA class I alleles with susceptibility to pSS provides new insights to the genetic predisposition to this disease and subsequently to its physiopathology.

Neuroendocrine manifestations in Sjögren's syndrome

Molecular biology has had a major impact on our concepts of the immune system and its relation to neuroendocrine axes, in particular, the adrenal, gonadal, and thyroid axes. It is now well established that not only are the biosynthetic and catabolic pathways of glucocorticoids and sex hormones (estrogen, progesterone, and testosterone) closely related but that the receptors for these hormones are part of a supergene family of receptors which include (in addition to these hormone receptors) the mineralocorticoid receptor, thyroid hormone receptor, retinoic acid receptors, and vitamin D receptors. This suggests a complex network of steroid hormones and receptors for the control and integration of a multitude of physiologic functions at a systemic level. The immune system seems to be tightly integrated into this homeostatic neuroendocrine regulatory network. The neurophysiologic and biochemical events that promote successful adaptation during stressful situations are now identified for illnesses that seem to occur as a result of or are associated with dysregulation of the stress response. One difficulty in interpreting the mechanisms of HPA axis dysfunction in autoimmune-inflammatory syndromes arises from the plasticity of the hormonal systems involved. Levels of hormones produced and receptors reset rapidly with changes in the hormonal milieu (deficiency or excess) and have likely changed during the course of the chronic immune disorder. This, in turn, is further confounded by the pleomorphic natural history of most autoimmune-inflammatory diseases such as SS. The levels of sex hormones and their receptors are tightly linked to HPA axis function. It may be that significant changes in the estrogen-to-androgen ratio or the ratio of their receptors alter the activity of steroid-sensitive cells such as the individual immune cells or epithelial cells, thus providing a means for endocrine regulation of the immune response in SS. Studies in the closely related disorder RA support this hypothesis. Taken together, adrenal and gonadal steroid hormone deficiency plus elevated PRL levels probably greatly facilitate cellular immunity in SS patients. This hypothesis in SS is supported by a growing body of data indicating that RA develops as a consequence of a deficiency in adrenal and gonadal steroid hormone production. It is noteworthy that the findings in female SS patients indicated a central deficiency in all three neuroendocrine axes: adrenal, gonadal, and thyroid. At present, it is not clear if any one system plays a primary role in the expression of the disease. Rather, it is likely that the net effect involves the synergistic and antagonistic effects of multiple hormones, making the specific effects of individual hormones difficult to discern.

Sjögren's syndrome: autoantibodies to cellular antigens. Clinical and molecular aspects

Autoantibodies to cellular autoantigens are usually found in sera of patients with systemic autoimmune rheumatic diseases. Patients with Sjögren's syndrome (SS) frequently present autoantibodies to both organ and non-organ-specific autoantigens. The most commonly detected autoantibodies are those directed against the ribonucleoproteins Ro/SSA and La/SSB. The presence of the antibodies in SS is associated with early disease onset, longer disease duration, parotid gland enlargement, higher frequency of extraglandular manifestations and more intense lymphocytic infiltration of the minor salivary glands. Over the past several years, the structure and function of these autoantigens have been extensively studied. Several centers, using different techniques, have investigated the B cell epitopes on the protein components Ro 60 kD, Ro 52kD, and La 48 kD. Finally, increased evidence of direct involvement of anti-Ro/SSA and anti-La/SSB autoantibodies in the pathogenesis of tissue injury has been contributed by several studies.

Sjögren's syndrome: autoimmune epithelitis

Sjögren's syndrome (SS) is a chronic autoimmune disorder of the exocrine glands of unknown aetiology, which is typically associated with focal lymphocytic infiltrates of glandular tissues and autoantibody responses against the Ro(SSA) and La(SSB) ribonucleoproteins. In almost one-third of patients disease involves various extraglandular sites, whereas approximately 5% of patients may also develop malignant B-cell lymphoma. In addition, features of SS are frequently encountered (5-20%) in patients with several other autoimmune rheumatic diseases, and in several respects these 'secondary' forms may be distinct from SS found alone (primary-SS), as well as from each other. The correct diagnosis and management of SS may require consideration from various specialists. Differential diagnosis includes adverse effects of drugs, sarcoidosis, lipoproteinaemias, age-related atrophy, chronic graft-versus-host disease, lymphomas, amyloidosis and infection by human immunodeficiency virus or hepatitis C virus. Based on the sequential application of the validated European classification criteria for SS, a practical algorithm for diagnosis is presented. Despite progress in the understanding of the broad clinicopathological spectrum of the entity, its treatment remains largely empirical and symptomatic. To date, the decision for systemic therapeutic intervention is primarily based on the severity of extraglandular manifestations.

Sjögren's syndrome

Sjögren's syndrome is a rather common autoimmune disease primarily characterized by the dysfunction and destruction of exocrine glands associated with lymphocytic infiltrations. The disorder has a quite broad clinical presentation, ranging from glandular disease to systemic involvement and to the development of lymphoid malignancy. This article reviews the current aspects in clinical diagnosis and management and the immunopathogenesis of the disorder.

HLA class II phenotype controls diversification of the autoantibody response in primary Sjögren's syndrome (pSS)

The coexistence of anti-La (SS-B) and anti-Ro (SS-A) autoantibodies in pSS is probably explained by intermolecular spreading of autoimmunity toward different components of the La/Ro ribonucleoprotein (RNP). In order to evaluate the role of the HLA class II phenotype in controlling diversification of this autoantibody response, 80 patients with pSS were typed by polymerase chain reaction sequence-specific oligonucleotide (PCR-SSO) at the HLA class II loci DRB1, DQA1 and DQB1. Serum samples were examined for anti-La and anti-Ro by counterimmunoelectrophoresis and by ELISA using purified recombinant La and 60-kD Ro proteins. Patient sera were classified according to the extent of diversification of the anti-La, anti-Ro response including the presence or absence of precipitating anti-La antibodies. Immunogenic characteristics of these stratified groups were then studied. All patients with pSS, with or without autoantibodies to Ro and La, were found to have at least one of the HLA-DRB1 types DR2, DR3 or DR5. The HLA DR3-DQA1*0501-DQB1*02 (DR3-DQ2) haplotype was primarily associated with a diversified La/Ro RNP response containing precipitating autoantibodies to La (P<0.001); whereas the haplotype HLA DR2-DQA1*0102-DQB1*0602 (DR2-DQ1) was associated with a less diversified La/Ro RNP response containing non-precipitating (restricted epitope) anti-La autoantibodies (P<0.001). Anti-La-positive patients lacking both HLA-DR2 and HLA-DR3 all expressed the HLA-DQA1*0501 allele, which was present at increasing frequency with greater diversification of the anti-La/Ro autoantibody response. The association of distinct HLA haplotypes with different degrees of autoantibody diversification in patients with pSS suggests a model of HLA-restricted presentation of La/Ro peptide determinants to autoreactive helper T cells. We propose that non-precipitating anti-La responses are driven by limited intermolecular help from DR2-DQ1-restricted T helper cells recognizing Ro determinants. On the other hand, we speculate that the more diversified, precipitating anti-La responses obtain more efficient cognate T help from DR3-DQ2-restricted T helper cells recognizing La determinants, where HLA-DQA1*0501 may be a critical determinant for antigen presentation.

HLA and graft-versus-host disease: a population-based study of HLA phenotypes of Jewish and Arabic bone marrow transplanted patients in Israel

The relationship between the incidence of graft-versus-host disease (GVHD) and human leukocyte antigens (HLA) was analyzed in HLA-identical sibling bone marrow transplantation donor/recipient pairs from the two major populations in Israel: Jewish and Arabic. HLA phenotypes were significantly different, in both groups, between patients and healthy controls. Among Jews, a higher incidence of GVHD was found with A28, CW3, CW6 of class I and DR7, DQ2 of class II; a lower incidence was found with A2, A26, B14. Among Arabs, a higher incidence of GVHD was found with B41, CW7 of class I, and DR2, DR13 of class II. The development of GVHD is apparently associated with HLA phenotypes specific to each population.

Comparative analysis of HLA polymorphism at the serologic and molecular level in Moroccan and Ashkenazi Jews

The Jewish people comprise two major groups, one encompassing the Jews of Ashkenazi (Central and Eastern European) origin and the other including those of Sephardic (Middle Eastern and North African) descent. To the latter belong the Jews of Moroccan stock, who form the largest Jewish subgroup among the non-Ashkenazi population living in Israel. As the members of each of these groups differ in physiognomy and life style, it was of interest to investigate whether these differences are also reflected in their respective HLA compositions. To this end, 132 subjects of Ashkenazi and 113 individuals of Moroccan origin residing in Israel were tested and the results compared with data for other populations made available by the 11th International Histocompatibility Workshop. Comparison between their HLA profiles and those of non-Jews revealed that the Jewish groups in some aspects resembled one another but in others showed disparities. The dissimilarities between the various groups are expressed in terms of gene and haplotype frequencies, as well as in HLA-disease associations (as for example rheumatoid arthritis, erosive lichen planus, primary Sjögren's syndrome, pemphigus vulgaris). However, both Jewish groups shared some unique features with respect to HLA class II allelic frequencies, pointing to a common ancestry.

HLA polymorphism in Moroccan Jewry

The Moroccan Jewish community living in Israel shows a relatively large genetic distance from other North African Jewish communities. In this work the polymorphism of HLA class I and class II determinants, as defined by serology and oligotyping, is analyzed in 113 healthy unrelated Jews of Moroccan stock. The class I antigens HLA-A1, -B44, and -Cw7 showed the highest frequency, while the most prevalent class II variants were DRB1*0701 and *1104, DQA1*0501, and DQB1*0201 and *0301. HLA A1-B13-DR7, A2-B51-DR10, and A1-B44-DR13 were the most typical three-locus haplotypes. Although the antigen frequency distribution of the Moroccan Jews falls within the Caucasian diversity range, this community has a unique pattern in terms of antigen, gene, and haplotype frequencies. Thus, in the Moroccan Jews DRB1*1305, an allele believed to be the result of a recombination event between DRB1*1301-1302 and DRB1*1101, is represented to a much larger extent than in all the other population groups studied at the 11th IHWS. This allele may therefore be a typical Jewish variant. A particular finding was the high frequencies of HLA-B13, B52, and DR10, alleles common among some Oriental populations. The answer to this enigmatic phenomenon probably must be sought in the tortuous history of this community.

Serologic and molecular analysis of the HLA system in Israeli Jewish patients with oral erosive lichen planus

Oral erosive lichen planus is a distinct subtype of the common dermatosis lichen planus. Although the etiology of lichen planus is still obscure, it is known that cell-mediated immune mechanisms and genetic factors underlie its pathogenesis. Previous studies have found an association between lichen planus and HLA-DR3 or DR9 in different population groups. The present work was designed to elucidate, at the serologic and molecular levels, whether and which HLA genes are associated with oral erosive lichen planus in Israeli Jewish patients. A significant association with HLA-DR2 (RR = 4.7; pc < 0.0013) and a decrease in DR4 (RR = 0.3; p < 0.03) among the patients were noted. Oligotyping of DR2 alleles showed the presence of all three common variants (DRB1*1501, DRB1*1502 and DRB1*1601) in the patients, although none of the variants was overrepresented significantly. Three possible explanations for the role of HLA genes in the predisposition to oral erosive lichen planus are discussed. The most attractive theory for the pathogenesis of the disease seems to include the involvement of non-classical HLA genes.