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

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.

IRT5 Probiotics Changes Immune Modulatory Protein Expression in the Extraorbital Lacrimal Glands of an Autoimmune Dry Eye Mouse Model

Purpose

While the association between the gut microbiome and the immune system has been studied in autoimmune disorders, little is known about ocular disease. Previously we reported that IRT5, a mixture of five probiotic strains, could suppress autoimmune dry eye. In this study, we investigated the mechanism by which IRT5 performs its immunomodulatory function in a mouse model of autoimmune dry eye.

Methods

NOD.B10.H2b mice were used as an autoimmune dry eye model. Either IRT5 or PBS was gavaged orally for 3 weeks, with or without 5 days of antibiotic pretreatment. The effects on clinical features, extraorbital lacrimal gland and spleen proteins, and fecal microbiota were analyzed.

Results

The ocular staining score was lower, and tear secretion was higher, in the IRT5-treated groups than in the PBS-treated groups. After IRT5 treatment, the downregulated lacrimal gland proteins were enriched in the biological processes of defense response and immune system process. The relative abundances of 33 operational taxonomic units were higher, and 53 were lower, in the feces of the IRT5-treated groups than in those of the PBS-treated groups. IRT5 administration without antibiotic pretreatment also showed immunomodulatory functions with increases in the Lactobacillus helveticus group and Lactobacillus hamsteri. Additional proteomic assays revealed a decrease of proteins related to antigen-presenting processes in the CD11b⁺ and CD11c⁺ cells of spleen in the IRT5-treated groups.

Conclusions

Changes in the gut microbiome after IRT5 treatment improved clinical manifestations in the autoimmune dry eye model via the downregulation of antigen-presenting processes in immune networks.

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.

Network-assisted analysis of primary Sjögren's syndrome GWAS data in Han Chinese

Primary Sjögren's syndrome (pSS) is a complex autoimmune disorder. So far, genetic research in pSS has lagged far behind and the underlying biological mechanism is unclear. Further exploring existing genome-wide association study (GWAS) data is urgently expected to uncover disease-related gene combination patterns. Herein, we conducted a network-based analysis by integrating pSS GWAS in Han Chinese with a protein-protein interactions network to identify pSS candidate genes. After module detection and evaluation, 8 dense modules covering 40 genes were obtained for further functional annotation. Additional 31 MHC genes with significant gene-level P-values (sigMHC-gene) were also remained. The combined module genes and sigMHC-genes, a total of 71 genes, were denoted as pSS candidate genes. Of these pSS candidates, 14 genes had been reported to be associated with any of pSS, RA, and SLE, including STAT4, GTF2I, HLA-DPB1, HLA-DRB1, PTTG1, HLA-DQB1, MBL2, TAP2, CFLAR, NFKBIE, HLA-DRA, APOM, HLA-DQA2 and NOTCH4. This is the first report of the network-assisted analysis for pSS GWAS data to explore combined gene patterns associated with pSS. Our study suggests that network-assisted analysis is a useful approach to gaining further insights into the biology of associated genes and providing important clues for future research into pSS etiology.

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.

Advances in understanding the pathogenesis of primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is a prototypic autoimmune disorder, management of which has long suffered from a lack of knowledge of the underlying pathophysiological mechanisms; however, over the past decade major advances have been made in understanding the pathogenesis of pSS. The innate immune system has been demonstrated to have an important role at the early stage of the disease, notably through activation of the type I interferon (IFN) system. In addition, mechanisms of B-cell activation in pSS have become clearer, particularly owing to recognition of the involvement of the TNF family cytokine B-cell-activating factor, production of which is highly dependent on expression of type I and type II IFNs. Moreover, key inroads have been made in understanding lymphomagenesis, the most severe complication of pSS. IL-12 production and subsequent T-cell activation, mainly IFN-γ-secreting type 1 T-helper cells, have also been implicated in disease pathogenesis. Furthermore, evidence implicates neuroendocrine system dysfunction in pSS pathogenesis. These pathophysiological advances open new avenues of investigation. Indeed, the increased understanding of pSS pathogenesis has already led to the development of promising novel therapeutic strategies. This article summarizes recent findings regarding the pathogenic mechanisms involved in pSS and their implications.

GWAS reveals new recessive loci associated with non-syndromic facial clefting

We have applied a GWAS to 40 consanguineous families segregating cases of non-syndromic cleft lip with or without cleft palate (NS CL/P) (a total of 160 affected and unaffected individuals) in order to trace potential recessive loci that confer susceptibility to this common facial malformation. Pedigree-based association test (PBAT) analyses reported nominal evidence of association and linkage over SNP markers located at 11q25 (rs4937877, P = 2.7 × 10(-6)), 19p12 (rs4324267, P = 1.6 × 10(-5)), 5q14.1 (rs4588572, P-value = 3.36 × 10(-5)), and 15q21.1 (rs4774497, P = 1.08 × 10(-4)). Using the Versatile Gene-Based Association Study to complement the PBAT results, we found clusters of markers located at chromosomes 19p12, 11q25, and 8p23.2 overcome the threshold for GWAS significance (P < 1 × 10(-7)). From this study, new recessive loci implicated in NS CL/P include: B3GAT1, GLB1L2, ZNF431, ZNF714, and CSMD1, even though the functional association with the genesis of NS CL/P remains to be elucidated. These results emphasize the importance of using homogeneous populations, phenotypes, and family structures for GWAS combined with gene-based association analyses, and should encourage. other researchers to evaluate these genes on independent patient samples affected by NS CL/P.

Shared HLA Class II in Six Autoimmune Diseases in Latin America: A Meta-Analysis

The prevalence and genetic susceptibility of autoimmune diseases (ADs) may vary depending on latitudinal gradient and ethnicity. The aims of this study were to identify common human leukocyte antigen (HLA) class II alleles that contribute to susceptibility to six ADs in Latin Americans through a meta-analysis and to review additional clinical, immunological, and genetic characteristics of those ADs sharing HLA alleles. DRB1(∗)03:01 (OR: 4.04; 95%CI: 1.41-11.53) was found to be a risk factor for systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), and type 1 diabetes mellitus (T1D). DRB1(∗)04:05 (OR: 4.64; 95%CI: 2.14-10.05) influences autoimmune hepatitis (AIH), rheumatoid arthritis (RA), and T1D; DRB1(∗)04:01 (OR: 3.86; 95%CI: 2.32-6.42) is a susceptibility factor for RA and T1D. Opposite associations were found between multiple sclerosis (MS) and T1D. DQB1(∗)06:02 and DRB1(∗)15 alleles were risk factors for MS but protective factors for T1D. Likewise, DQB1(∗)06:03 allele was a risk factor for AIH but a protective one for T1D. Several common autoantibodies and clinical associations as well as additional shared genes have been reported in these ADs, which are reviewed herein. These results indicate that in Latin Americans ADs share major loci and immune characteristics.

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.

The IkappaBL gene polymorphism influences risk of acquiring systemic lupus erythematosus and Sjögren's syndrome

The human inhibitory kappaB-like gene (IkappaBL) maps to a chromosomal region approximately 25 kb telomeric of the TNF gene at 6p21.3. IkappaBL encodes a protein related to IkappaBalpha that may interact with members of the NF-kappaB/Rel family. We evaluated the role of IkappaBL gene polymorphism in systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS). Genomic DNA isolated from individuals with SLE (n = 134), pSS (n = 67) and from individuals matched for age, sex, and ethnicity (n = 423) was genotyped for Delta-473, -62T/A and +738T/C polymorphisms. The -62A allele was associated with a decrease in the risk of acquiring SLE in a recessive manner; whereas the +738C allele was associated with a more than twofold and threefold increase in the risk of SLE and pSS respectively, relative to the +738T allele. Four haplotypes were observed for the IkappaBL polymorphisms. Haplotype -62A+738T (AT) was associated with a 37% decrease in the risk of SLE, whereas AC tended to increase the risk of developing pSS. Using previously reported TNF data, an almost twofold increased in the risk of SLE was observed between haplotypes IKBL-62T+738T/TNF-308G-238G (TTGG) and TTAG because of linkage disequilibrium between IKBL-62T and TNF-308A. Our findings indicate that the IkappaBL gene influences the risk of developing SLE and pSS.

Chronic hepatitis C infection and sicca syndrome: a clear association with HLA DQB1*02

BACKGROUND

Hepatitis C virus infection is a major cause of nonA, nonB hepatitis worldwide. A high prevalence of immunological abnormalities has been shown to occur in patients with chronic hepatitis C virus infection.

AIM

The aim of this study was to assess the development of sicca syndrome in a cohort of patients infected with a single strain of hepatitis C virus, namely genotype 1b, and correlate this with viral persistence and human leukocyte antigen type of the patients.

METHODS

Ninety-five patients infected with the single strain hepatitis C virus were used in this study, 32 of whom were polymerase chain reaction-negative and 63 polymerase chain reaction-positive. Patient details were reviewed for symptoms consistent with sicca syndrome. Human leukocyte antigen class I (A, B and C) and class II (DRB and DQB1) typing was performed on all patients. Auto-antibodies were also measured.

RESULTS

DQB1*02 was highly significantly associated with viral persistence (P<0.0001). Nineteen of 21 patients with sicca syndrome were hepatitis C virus-polymerase chain reaction-positive demonstrating a strong association with viral persistence and the development of the syndrome. Human leukocyte antigen DQB1*02 was significantly associated with the development of sicca syndrome, P=0.02.

CONCLUSION

The development of autoimmune disease in patients with chronic hepatitis C virus infection depends on the interaction of multiple factors. This study suggests that important factors in this process are viral persistence and human leukocyte antigen type of the patients.

Genetic basis of Sjögren's syndrome. How strong is the evidence?

Sjögren's syndrome (SS) is a late-onset chronic autoimmune disease (AID) affecting the exocrine glands, mainly the salivary and lachrymal. Genetic studies on twins with primary SS have not been performed, and only a few case reports describing twins have been published. The prevalence of primary SS in siblings has been estimated to be 0.09% while the reported general prevalence of the disease is approximately 0.1%. The observed aggregation of AIDs in families of patients with primary SS is nevertheless supportive for a genetic component in its etiology. In the absence of chromosomal regions identified by linkage studies, research has focused on candidate gene approaches (by biological plausibility) rather than on positional approaches. Ancestral haplotype 8.1 as well as TNF, IL10 and SSA1 loci have been consistently associated with the disease although they are not specific for SS. In this review, the genetic component of SS is discussed on the basis of three known observations: (a) age at onset and sex-dependent presentation, (b) familial clustering of the disease, and (c) dissection of the genetic component. Since there is no strong evidence for a specific genetic component in SS, a large international and collaborative study would be suitable to assess the genetics of this disorder.

Is there a common genetic basis for autoimmune diseases?

Autoimmune diseases (ADs) represent a diverse collection of diseases in terms of their demographic profile and primary clinical manifestations. The commonality between them however, is the damage to tissues and organs that arises from the response to self-antigens. The presence of shared pathophysiological mechanisms within ADs has stimulated searches for common genetic roots to these diseases. Two approaches have been undertaken to sustain the “common genetic origin” theory of ADs. Firstly, a clinical genetic analysis showed that autoimmunity aggregates within families of probands diagnosed with primary Sjögren's (pSS) syndrome or type 1 diabetes mellitus (T1D). A literature review supported the establishment of a familiar cluster of ADs depending upon the proband's disease phenotype. Secondly, in a same and well-defined population, a large genetic association study indicated that a number of polymorphic genes (i.e. HLA-DRB1, TNF and PTPN22) influence the susceptibility for acquiring different ADs. Likewise, association and linkage studies in different populations have revealed that several susceptibility loci overlap in ADs, and clinical studies have shown that frequent clustering of several ADs occurs. Thus, the genetic factors for ADs consist of two types: those which are common to many ADs (acting in epistatic pleitropy) and those that are specific to a given disorder. Their identification and functional characterization will allow us to predict their effect as well as to indicate potential new therapeutic interventions. Both autoimmunity family history and the co-occurrence of ADs in affected probands should be considered when performing genetic association and linkage studies.

Pathophysiology of Sjögren's syndrome

The term Sjögren's syndrome refers to keratoconjunctivitis sicca and xerostomia due to lymphocytic infiltrates of lachrymal and salivary glands. The current used criteria for diagnosis of primary Sjögren's syndrome is the American-European consensus. Primary Sjögren's syndrome is an autoimmune disorder characterized by lymphocytic infiltrates and destruction of the salivary and lachrymal glands and systemic production of autoantibodies to the ribonucleoprotein particles SS-A/Ro and SS-B/La. The infiltrating cells (T- and B-cells, dendritic cells) interfere with glandular function at several points: destruction of glandular elements by cell-mediated mechanisms; secretion of cytokines that activate pathways bearing the signature of type 1 and 2 interferons; production of autoantibodies that interfere with muscarinic receptors; and secretion of metalloproteinases (MMPs) that interfere with the interaction of the glandular cell with its extracellular matrix, which is necessary for efficient glandular function. As the process progresses, the mucosal surfaces become sites of chronic inflammation and the start of a vicious circle. Despite extensive study of the underlying cause of Sjögren's syndrome, the pathogenesis remains obscure. In broad terms, pathogenesis is multifactorial; environmental factors are thought to trigger inflammation in individuals with a genetic predisposition to the disorder.

Analysis of IL1B, TAP1, TAP2 and IKBL polymorphisms on susceptibility to tuberculosis

Genetic determinants of human susceptibility to tuberculosis (TB) have not been completely elucidated. Interleukin-1 beta (IL-1beta) and the inhibitor of kB-like (IkBL) are important molecules that participate in the inflammatory response required for the immunological control of a broad spectrum of infectious agents. The transporter associated with antigen processing (TAP) is involved in the antigen processing via major histocompatibility complex class I molecules and in turn might regulate the T-cell response against Mycobacterium tuberculosis. To better characterize the host genetic factors determining the susceptibility to TB, we evaluated the influence of functional polymorphisms in IL1B, TAP and IKBL genes on the risk of developing pulmonary TB in a Northwestern Colombian population, an endemic area of M. tuberculosis infection. A total of 122 TB patients and 166 healthy controls (N = 166) negative for human immunodeficiency virus infection were examined for IL1B-511 and +3,953, TAP1 and TAP2 and IKBL+738 polymorphisms. Univariate analysis disclosed significant differences between patients and controls for IL1B+3,953 polymorphism. After unconditional logistic regression analysis, a strong protection conferred by IL1B+3,953 T-allele-carrying genotypes was observed. A trend between TAP2*0201 allele and disease was observed. Association between IL1B-511, TAP1 or IKBL polymorphisms and TB disease was not found. These results indicate that a functional polymorphism in the IL1B gene influences the susceptibility to TB and suggest a role for IL-1beta in the pathogenesis of mycobacterial infection.

Interleukin-1beta polymorphisms in Colombian patients with autoimmune rheumatic diseases

Interleukin-1 beta (IL-1beta) exerts a range of inflammatory and immunomodulatory activities that are important in host defense and autoimmune response. The IL-1beta gene, located on chromosome 2 (2q13), is polymorphic. The influence of its polymorphism on 355 patients with autoimmune rheumatic diseases was examined. To this effect, 172 patients with rheumatoid arthritis (RA), 114 with systemic lupus erythematosus (SLE), and 69 with primary Sjogren's syndrome (pSS) were studied. The control group consisted of 392 matched healthy individuals. Genotyping of IL-1beta single-nucleotide polymorphisms (SNPs) at positions -511 (C/T) and + 3953 (C/T) was performed by the polymerase chain reaction-restriction fragment length polymorphism technique. In addition, levels of IL-1beta were measured by immunoassay in supernatants of lipopolysaccharide (LPS)-stimulated and nonstimulated peripheral blood monocytes (PBM) obtained from 19 homozygous individuals for the three most common IL-1beta likely haplotypes, all belonging to the control group. Allele + 3953T was protective for SLE (odds ratio (OR) = 0.57, 95% confidence intervals (CI) = 0.34-0.88, P = 0.01) as was the haplotype -511C + 3953T (OR = 0.43, 95%CI = 0.25-0.74, pc = 0.006). The latter was associated with a lower LPS-stimulated-PBM IL-1beta secretion. Results suggest that IL-1beta polymorphism influences the susceptibility to acquire SLE in our population. The protective association might be explained by the observed inhibitory effect of IL-1beta + 3953T allele on the secretion of IL-1beta under inflammatory circumstances.

Lamivudine is not effective in primary Sjögren's syndrome

BACKGROUND

Retroviral infection has been implicated in the pathogenesis of primary Sjögren's syndrome.

OBJECTIVE

To examine the efficacy of the reverse transcriptase inhibitor lamivudine in patients with this syndrome.

METHODS

16 patients with primary Sjögren's syndrome were randomised to receive either lamivudine 150 mg twice daily or placebo for three months. Measures of lacrimal and salivary function, including minor salivary gland biopsies, were obtained before and after treatment.

RESULTS

Treatment with lamivudine did not result in significant improvement in the primary outcome measure of unstimulated whole salivary flow or other secondary measures, including minor salivary gland biopsy focus scores.

CONCLUSION

Lamivudine is not effective in patients with primary Sjögren's syndrome, suggesting either that a retroviral aetiology is not present or that it may be important only in early disease.

Transcription of major histocompatibility complex class I (Kb) and transporter associated with antigen processing 1 and 2 genes is up-regulated with age

The transporter associated with antigen processing 1 and 2 (TAP1 and TAP2) genes belong to the ATP-binding cassette family of transporter genes. They provide peptides necessary for the assembly of major histocompatibility complex (MHC) class I molecules by transporting these peptides into the endoplasmic reticulum. As MHC class I protein expression increases with age, we have explored the effect of age on the transcription of MHC class I genes (Kb) and TAP1 and TAP2 genes in C57BL/6 mice. Blood and spleen lymphocytes were isolated from mice aged from 3 months to over 24 months. RNA was extracted and mRNA for Kb, TAP1, TAP2 was quantified using slot-blot hybridization followed by densitometry. There was a parallel age-related increase (1.5-fold) in blood lymphocyte mRNA of these genes from 3 months to 21 months. In mice over 24 months old there was a decrease in Kb and TAP1 mRNA, but an increase in TAP2 mRNA. In spleen lymphocytes an age-related increase in all three mRNA species occurred throughout life. While MHC class I and Tap genes underwent very similar age-related changes, MHC class I mRNA was about 50 times more abundant than either TAP1 or TAP2 mRNA.

New concepts in the pathogenesis of Sjögren syndrome: many questions, fewer answers

Although a modified European-American consensus classification of Sjögren syndrome has been introduced during the last year, the etiopathogenesis of this disease characterized by chronic lymphocytic inflammation, impaired function, and, finally, destruction of the salivary and lacrimal glands as well as systemic manifestations remains to be elucidated. Recent insights into the pathogenesis of Sjögren syndrome resulting from immunogenetic, hormonal, and epidemiologic evaluations as well as animal and in vitro studies are highlighted by this review. Evidence confirms that lymphocytic disturbances, including ectopic germinal center formation and aberrations of cellular signaling play a significant role in Sjögren syndrome. Although some of these features are unique to Sjögren syndrome, others are also found in a number of systemic autoimmune diseases, such as systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. The underlying cause of Sjögren syndrome remains largely enigmatic. However, distinct characteristics may provide the basis for the classification of the disease entities. Finally, an enhanced risk of lymphomagenesis is a well-known hallmark of primary Sjögren syndrome, indicating the central role of derangement of lymphocyte regulation. As demonstrated by the introduction of the new targeted therapeutic approaches in rheumatoid arthritis, solid insights into the pathogenesis of Sjögren syndrome may pave the way toward new therapeutic approaches.

Central Nervous System Compromise in Primary Sjögren’s Syndrome

Central nervous system (CNS) involvement in primary Sjögren's syndrome (SS) is poorly understood, and its frequency as well as its manifestations are subjects of controversy. The current study was undertaken to determine the prevalence and the clinical and immunogenetic characteristics of CNS compromise in a well defined group of patients with primary SS. In this retrospective study, patients fulfilled the European classification criteria. Among 120 patients with primary SS, 3 (2.5%) had CNS compromise (multiple sclerosis-like illness, complicated migraine, and optic neuritis with epilepsy). The CNS involvement coincided with the onset of sicca symptoms in 1 case. All 3 patients carried the human leukocyte antigen (HLA) DQB1*0303 allele and tested positive for anti-Ro antibodies, but not for anti-cardiolipin antibodies. Although rare, CNS compromise in primary SS can be the presenting manifestation of the disease in a few cases, and may be severe and varied.