Leptin is abnormally elevated in the plasma of patients with systemic lupus erythematosus (SLE), where it is thought to promote and/or sustain pro-inflammatory responses. Whether this association could reflect an increased genetic susceptibility to develop SLE is not known, and studies of genetic associations with leptin-related polymorphisms in SLE patients have been so far inconclusive. Here we genotyped DNA samples from 15,706 SLE patients and healthy matched controls from four different ancestral groups, to correlate polymorphisms of genes of the leptin pathway to risk for SLE. It was found that although several SNPs showed weak associations, those associations did not remain significant after correction for multiple testing. These data do not support associations between defined leptin-related polymorphisms and increased susceptibility to develop SLE.
systemic lupus erythematosus; leptin pathway; gene polymorphisms
The serologic hallmark of primary Sjögren’s syndrome (pSS) is IgG antibodies specific for Ro (SSA) and La (SSB). Molecular characteristics of glandular-derived B cells at the site of pSS inflammation have been described; however, parallels between glandular antibody-secreting cells (ASC) and serologic antibody specificities have not been evaluated. We utilized recombinant monoclonal antibody (hmAb) technology to study salivary gland-(SG) derived ASC specificities, evaluating their molecular characteristics and identified IgG antibody specificity.
hmAbs were generated from glandular IgG ASC. Heavy and light chain usage and immunoglobulin subclass were analyzed by sequencing. ELISA, indirect immunofluorescence, enzyme immunoassay and 35S immunoprecipitation analysis were used to determine antibody specificity.
Evaluation of single ASCs from SG biopsies of patients with primary SS or with SS and overlapping SLE revealed significant concordance between serum autoantibody and glandular ASC specificities. Glandular-derived ASC heavy and light chains were extensively somatically hypermutated, indicative of antigen-driven responses. Specifically, we produced the first fully human monoclonal autoantibodies derived from salivary glands in this study.
Salivary glands in SS patients are a site for antibody production, which extend beyond the canonical Ro and/or La SS specificities. Furthermore, we demonstrate that glandular antibody production strongly reflects the serological humoral response in the two patients studied herein.
Primary neuroendocrine tumors of the larynx are rare, with moderately differentiated neuroendocrine carcinoma (MDNC) being the most frequent histologic type. We report a MDNC in a 57-year-old gentleman with an enlarging right-sided neck mass. Flexible fiberoptic exam revealed a right arytenoid lesion. Histology from excisional biopsy was concerning for medullary thyroid carcinoma (MTC) versus NET of the larynx. Immunohistochemistry was diffusely positive for calcitonin and CEA and focally positive for TTF-1. Serum calcitonin was elevated. Thyroid ultrasound was unremarkable. The patient underwent laryngectomy, thyroidectomy, and neck dissection. Pathology showed neuroendocrine carcinoma of right arytenoid with positive cervical lymph nodes. A 4 mm deposit of NET was present in right thyroid with adjacent intravascular tumor consistent with thyroidal metastasis from a primary laryngeal NET (MDNC). MDNC and MTC can be microscopically indistinguishable. Both tumors can stain positively for calcitonin and CEA. TTF-1 staining has been useful to help distinguish these tumors as it is strongly and diffusely positive in MTC, but usually negative (or only focally positive) in MDNC. We report the fourth case of primary neuroendocrine carcinoma of the larynx associated with elevated serum calcitonin level and the first such case associated with metastasis to the thyroid.
Commercial curcumin (CU), derived from food spice turmeric (TU), has been widely studied as a potential therapeutic for a variety of oncological and inflammatory conditions. Lack of solubility/bioavailability has hindered curcumin's therapeutic efficacy in human diseases. We have solubilised curcumin in water applying heat/pressure, obtaining up to 35-fold increase in solubility (ultrasoluble curcumin (UsC)). We hypothesised that UsC or ultrasoluble turmeric (UsT) will ameliorate systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS)-like disease in MRL-lpr/lpr mice.
Eighteen female MRL-lpr/lpr (6 weeks old) and 18 female MRL-MpJ mice (6 weeks old) were used. Female MRL-lpr/lpr mice develop lupus-like disease at the 10th week and die at an average age of 17 weeks. MRL-MpJ mice develop lupus-like disease around 47 weeks and typically die at 73 weeks. Six mice of each strain received autoclaved water only (lpr-water or MpJ-water group), UsC (lpr-CU or MpJ-CU group) or UsT (lpr-TU or MpJ-TU group) in the water bottle.
UsC or UsT ameliorates SLE in the MRL-lpr/lpr mice by significantly reducing lymphoproliferation, proteinuria, lesions (tail) and autoantibodies. lpr-CU group had a 20% survival advantage over lpr-water group. However, lpr-TU group lived an average of 16 days shorter than lpr-water group due to complications unrelated to lupus-like illness. CU/TU treatment inhibited lymphadenopathy significantly compared with lpr-water group (p=0.03 and p=0.02, respectively) by induction of apoptosis. Average lymph node weights were 2606±1147, 742±331 and 385±68 mg, respectively, for lpr-water, lpr-CU and lpr-TU mice. Transferase dUTP nick end labelling assay showed that lymphocytes in lymph nodes of lpr-CU and lpr-TU mice underwent apoptosis. Significantly reduced cellular infiltration of the salivary glands in the lpr-TU group compared with the lpr-water group, and a trend towards reduced kidney damage was observed in the lpr-CU and lpr-TU groups.
These studies show that UsC/UsT could prove useful as a therapeutic intervention in SLE/SS.
Autoantibodies; Autoimmunity; Sjøgren's Syndrome; Systemic Lupus Erythematosus; Treatment
Objective. Systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS) share clinical and immunogenetic features and may occur together. We undertook this study to determine the risk of primary SS among SLE-unaffected relatives of SLE patients and whether or not primary and secondary SS tended to occur in the same families. Methods. We collected clinical and serological data on 2694 SLE patients, 7390 SLE-unaffected relatives of the SLE patients, and 1470 matched controls. Results. Of the 2694 subjects with SLE, 548 had secondary SS, while 71 of their 7390 SLE-unaffected relatives had primary SS. None of the 1470 controls had SS as defined herein (p = 5 × 10−5 compared to SLE-unaffected relatives). Of the 71 SLE-unaffected relatives with primary SS, 18 (25.3%) had an SLE-affected family member with secondary SS, while only 530 of the 7319 (7.2%) SLE-unaffected relatives without SS did so (p = 1 × 10−8). Conclusion. Among families identified for the presence of SLE, primary and secondary SS tend to occur within the same families. These results highlight the commonalities between these two forms of SS, which in fact correspond to the same disease.
CD4+ T cells predominate in salivary gland (SG) inflammatory lesions in Sjögren’s syndrome (SS). However, their antigen specificity, degree of clonal expansion, and relationship to clinical disease features remain unknown. We used multiplex reverse-transcriptase PCR to amplify paired T cell receptor α (TCRα) and β transcripts of single CD4+CD45RA− T cells from SG and peripheral blood (PB) of 10 individuals with primary SS, 9 of whom shared the HLA DR3/DQ2 risk haplotype. TCRα and β sequences were obtained from a median of 91 SG and 107 PB cells per subject. The degree of clonal expansion and frequency of cells expressing two productively rearranged α genes were increased in SG versus PB. Expanded clones from SG exhibited complementary-determining region 3 (CDR3) sequence similarity both within and among subjects, suggesting antigenic selection and shared antigen recognition. CDR3 similarities were shared among expanded clones from individuals discordant for canonical Ro and La autoantibodies, suggesting recognition of alternative SG antigen(s). The extent of SG clonal expansion correlated with reduced saliva production and increased SG fibrosis, linking expanded SG T cells with glandular dysfunction. Knowledge of paired TCRα and β sequences enables further work toward identification of target antigens and development of novel therapies.
Our purpose was to compile information on the haematological manifestations of systemic lupus erythematosus (SLE), namely leucopenia, lymphopenia, thrombocytopenia, autoimmune haemolytic anaemia (AIHA), thrombotic thrombocytopenic purpura (TTP) and myelofibrosis. During our search of the English-language MEDLINE sources, we did not place a date-of-publication constraint. Hence, we have reviewed previous as well as most recent studies with the subject heading SLE in combination with each manifestation. Neutropenia can lead to morbidity and mortality from increased susceptibility to infection. Severe neutropenia can be successfully treated with granulocyte colony-stimulating factor. While related to disease activity, there is no specific therapy for lymphopenia. Severe lymphopenia may require the use of prophylactic therapy to prevent select opportunistic infections. Isolated idiopathic thrombocytopenic purpura maybe the first manifestation of SLE by months or even years. Some manifestations of lupus occur more frequently in association with low platelet count in these patients, for example, neuropsychiatric manifestation, haemolytic anaemia, the antiphospholipid syndrome and renal disease. Thrombocytopenia can be regarded as an important prognostic indicator of survival in patients with SLE. Medical, surgical and biological treatment modalities are reviewed for this manifestation. First-line therapy remains glucocorticoids. Through our review, we conclude glucocorticoids do produce a response in majority of patients initially, but sustained response to therapy is unlikely. Glucocorticoids are used as first-line therapy in patients with SLE with AIHA, but there is no conclusive evidence to guide second-line therapy. Rituximab is promising in refractory and non-responding AIHA. TTP is not recognised as a criteria for classification of SLE, but there is a considerable overlap between the presenting features of TTP and SLE, and a few patients with SLE have concurrent TTP. Myelofibrosis is an uncommon yet well-documented manifestation of SLE. We have compiled the cases that were reported in MEDLINE sources.
Systemic Lupus Erythematosus; Biologics; Autoantibodies
CD4+ T cells predominate in salivary gland (SG) inflammatory lesions in Sjögren’s syndrome (SS). However, their antigen specificity, degree of clonal expansion, and relationship to clinical disease features remain unknown. We used multiplex reverse-transcriptase PCR to amplify paired T cell receptor α (TCRα) and β transcripts of single CD4+CD45RA– T cells from SG and peripheral blood (PB) of 10 individuals with primary SS, 9 of whom shared the HLA DR3/DQ2 risk haplotype. TCRα and β sequences were obtained from a median of 91 SG and 107 PB cells per subject. The degree of clonal expansion and frequency of cells expressing two productively rearranged α genes were increased in SG versus PB. Expanded clones from SG exhibited complementary-determining region 3 (CDR3) sequence similarity both within and among subjects, suggesting antigenic selection and shared antigen recognition. CDR3 similarities were shared among expanded clones from individuals discordant for canonical Ro and La autoantibodies, suggesting recognition of alternative SG antigen(s). The extent of SG clonal expansion correlated with reduced saliva production and increased SG fibrosis, linking expanded SG T cells with glandular dysfunction. Knowledge of paired TCRα and β sequences enables further work toward identification of target antigens and development of novel therapies.
CD4+ T cell clonal expansions in Sjögren’s syndrome salivary glands correlate with impaired glandular function and share TCR sequence similarity indicative of antigen-driven selection.
Prolidase deficiency is a rare autosomal recessive disease in which one of the last steps of collagen metabolism, cleavage of proline-containing dipeptides, is impaired. Only about 93 patients have been reported with about 10% also having systemic lupus erythematosus (SLE).
We studied a large extended Amish pedigree with four prolidase deficiency patients and three heterozygous individuals for lupus-associated autoimmunity. Eight unaffected Amish children served as normal controls. Prolidase genetics and enzyme activity were confirmed. Antinuclear antibodies (ANA) were determined using indirect immunofluorescence and antibodies against extractable nuclear antigens were determined by various methods, including double immunodiffusion, immunoprecipitation and multiplex bead assay. Serum C1q levels were determined by enzyme-linked immunosorbent assay.
Two of the four homozygous prolidase deficiency subjects had a positive ANA. One had anti-double-stranded DNA, while another had precipitating anti-Ro. By the simultaneous microbead assay, three of the four had anti-Sm and anti-chromatin. One of the three heterozygous subjects had a positive ANA and immunoprecipitation of a 75 000 molecular weight protein. The unaffected controls had normal prolidase activity and were negative for autoantibodies.
Prolidase deficiency may be associated with the loss of immune tolerance to lupus-associated autoantigens even without clinical SLE.
prolidase deficiency; systemic lupus erythematosus; autoantibodies
Systemic lupus erythematosus (SLE; OMIM 152700) is characterised by the production of antibodies to nuclear antigens. We previously identified variants in complement receptor 2 (CR2/CD21) that were associated with decreased risk of SLE. This study aimed to identify the causal variant for this association.
Genotyped and imputed genetic variants spanning CR2 were assessed for association with SLE in 15 750 case-control subjects from four ancestral groups. Allele-specific functional effects of associated variants were determined using quantitative real-time PCR, quantitative flow cytometry, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP)-PCR.
The strongest association signal was detected at rs1876453 in intron 1 of CR2 (pmeta=4.2×10−4, OR 0.85), specifically when subjects were stratified based on the presence of dsDNA autoantibodies (case-control pmeta=7.6×10−7, OR 0.71; case-only pmeta=1.9×10−4, OR 0.75). Although allele-specific effects on B cell CR2 mRNA or protein levels were not identified, levels of complement receptor 1 (CR1/CD35) mRNA and protein were significantly higher on B cells of subjects harbouring the minor allele (p=0.0248 and p=0.0006, respectively). The minor allele altered the formation of several DNA protein complexes by EMSA, including one containing CCCTC-binding factor (CTCF), an effect that was confirmed by ChIP-PCR.
These data suggest that rs1876453 in CR2 has long-range effects on gene regulation that decrease susceptibility to lupus. Since the minor allele at rs1876453 is preferentially associated with reduced risk of the highly specific dsDNA autoantibodies that are present in preclinical, active and severe lupus, understanding its mechanisms will have important therapeutic implications.
Systemic Lupus Erythematosus; Autoantibodies; Gene Polymorphism; B cells
Autoimmune thyroid disease is common in systemic lupus erythematosus (SLE). About 20% of patients with SLE have secondary Sjögren's syndrome.
Families with more than one patient with SLE were identified. All patients met the revised classification criteria, although SLE‐unaffected relatives were confirmed not to satisfy these criteria. Diagnosis of autoimmune thyroid disease and Sjögren's syndrome was made on the basis of a review of medical records, interview and questionnaire administered to patients with SLE, and by a questionnaire administered to SLE‐unaffected subjects.
Of a total of 1138 patients with SLE, 169 had a diagnosis of Sjögren's syndrome. Of these 50 (29.6%) patients also had autoimmune thyroid disease. Of the 939 patients with SLE with no diagnosis of Sjögren's syndrome, 119 (12.7%) had autoimmune thyroid disease (χ2 = 20.1, p = 0.000009). There was no association of a diagnosis of hypertension with secondary Sjögren's syndrome (42% vss 47%). Among 2291 SLE‐unaffected relatives, 44 had diagnosed primary Sjögren's syndrome and 16 (36.3%) of these also had autoimmune thyroid disease. 265 of 2247 (11.8%) subjects had autoimmune thyroid disease but no Sjögren's syndrome (χ2 = 24.2, p<0.001).
Autoimmune thyroid disease is found in excess among patients with SLE with a diagnosis of secondary Sjögren's syndrome, as well as among their SLE‐unaffected relatives with a diagnosis of primary Sjögren's syndrome.
Every human is intimately associated with a large and diverse population
of microorganisms living on the skin and mucous membranes. These commensal
organisms are known as the microbiome, or microbiota, and are acquired in young
childhood. The microbiome is critically important in establishing a fully
function immune system. For example, Th17 T helper cells are not present in a
germ-free environment. The relationship of the microbiome to autoimmune disease
is being explored actively. Mechanisms by which the microbiome may influence
these diseases include, but are not limited to, molecular mimicry as well as
induction and regulation of both Th17 and regulatory T cells. There are ample
data that a specific oral microbe, Porphyromonas gingivalis,
the only bacteria with the enzyme peptidylarginine deiminase, is involved in the
pathogenesis of rheumatoid arthritis. Connection between other rheumatic
autoimmune diseases and the microbiome remains to be made.
Sjögren’s syndrome (SS) is a complex polygenic autoimmune disorder. A few major genetic effects have been identified. Historically, HLA and non-HLA genetic associations have been reported. Recently, the HLA region continued to reveal association findings. A new susceptibility region has been suggested by a study of a D6S349 microsatellite marker. Among non-HLA studies, recent association of immunoglobulin κ chain allotype KM1 with anti-La autoantibodies in primary Sjögren’s syndrome confirms findings in a study from two decades ago. Meanwhile, mouse models have been employed to study the genetic contribution to salivary lymphadenitis or dry eyes and mouth. Gene transfer exploration in mouse models shows promise. The authors review the HLA and non-HLA association studies and the mouse model work that has been reported. Newly developed genomic capacity will provide, in the future, a much closer approximation of the true picture of the genetic architecture of Sjögren’s syndrome.
Sjögren’s syndrome; Genetics; HLA; Histocompatibility
It is widely proposed that microbial factors may incite autoimmune disease. While this hypothesis is proven in a few illnesses such as rheumatic fever, there is no definitive evidence of an infectious environmental trigger in Sjögren’s syndrome. However, there are circumstantial data with regard to viruses and several potential mechanisms of disease. These include antigen mimicry, polyclonal lymphocyte activation and infection mediated innate end-organ inflammation. In addition, hepatitis C virus infection clearly causes a Sjögren’s-like illness.
Sjögren’s Syndrome; virus; autoimmunity; infection
Primary Sjögren’s syndrome (pSS) is a systemic autoimmune disease with incompletely understood etiology. Very little is known about the role of epigenetic dysregulation in the pathogenesis of pSS.
We performed a genome-wide DNA methylation study in naïve CD4+ T cells in eleven pSS patients compared to age-, sex-, and ethnicity-matched healthy controls. Cytosine methylation was quantified using the Illumina Infinium HumanMethylation450 BeadChip array and validated using bisulfite sequencing.
We identified 553 hypomethylated and 200 hypermethylated CpG sites in naïve CD4+ T cells from pSS patients compared to healthy matched controls, representing 311 hypomethylated and 115 hypermethylated gene regions. Hypomethylated genes in pSS include LTA, coding for Lymphotoxin α. Other relevant genes such as CD247, TNFRSF25, PTPRC, GSTM1 and PDCD1 were also hypomethylated. The interferon signature pathway was represented by hypomethylation of STAT1, IFI44L, USP18 and IFITM1. A group of genes encoding for members of the solute carrier proteins were differentially methylated. In addition, the transcription factor RUNX1 was hypermethylated in patients, suggesting a possible connection to lymphoma predisposition. Gene ontology (GO) analysis of hypomethylated genes demonstrated enrichment of genes involved in lymphocyte activation and immune response. GO terms for hypermethylated genes included antigen processing and presentation.
This is the first epigenome-wide DNA methylation study in pSS. Our data highlight a role for DNA methylation in pSS and identify disease-associated DNA methylation changes in several genes and pathways in naïve CD4+ T cells in pSS that may be involved in the pathogenesis of this disease.
Genome wide association studies have identified variants in PXK that confer risk for humoral autoimmune diseases, including systemic lupus erythematosus (SLE or lupus), rheumatoid arthritis and more recently systemic sclerosis. While PXK is involved in trafficking of epidermal growth factor Receptor (EGFR) in COS-7 cells, mechanisms linking PXK to lupus pathophysiology have remained undefined. In an effort to uncover the mechanism at this locus that increases lupus-risk, we undertook a fine-mapping analysis in a large multi-ancestral study of lupus patients and controls. We define a large (257kb) common haplotype marking a single causal variant that confers lupus risk detected only in European ancestral populations and spans the promoter through the 3′ UTR of PXK. The strongest association was found at rs6445972 with P < 4.62 × 10−10, OR 0.81 (0.75–0.86). Using stepwise logistic regression analysis, we demonstrate that one signal drives the genetic association in the region. Bayesian analysis confirms our results, identifying a 95% credible set consisting of 172 variants spanning 202 kb. Functionally, we found that PXK operates on the B-cell antigen receptor (BCR); we confirmed that PXK influenced the rate of BCR internalization. Furthermore, we demonstrate that individuals carrying the risk haplotype exhibited a decreased rate of BCR internalization, a process known to impact B cell survival and cell fate. Taken together, these data define a new candidate mechanism for the genetic association of variants around PXK with lupus risk and highlight the regulation of intracellular trafficking as a genetically regulated pathway mediating human autoimmunity.
lupus; PXK; fine-mapping; B cells; BCR
Sjögren’s syndrome is a common autoimmune disease (~0.7% of European Americans) typically presenting as keratoconjunctivitis sicca and xerostomia. In addition to strong association within the HLA region at 6p21 (Pmeta=7.65×10−114), we establish associations with IRF5-TNPO3 (Pmeta=2.73×10−19), STAT4 (Pmeta=6.80×10−15), IL12A (Pmeta =1.17×10−10), FAM167A-BLK (Pmeta=4.97×10−10), DDX6-CXCR5 (Pmeta=1.10×10−8), and TNIP1 (Pmeta=3.30×10−8). Suggestive associations with Pmeta<5×10−5 were observed with 29 regions including TNFAIP3, PTTG1, PRDM1, DGKQ, FCGR2A, IRAK1BP1, ITSN2, and PHIP amongst others. These results highlight the importance of genes involved in both innate and adaptive immunity in Sjögren’s syndrome.
In recent years, vitamin D has been shown to possess a wide range of immunomodulatory effects. Although there is extensive amount of research on vitamin D, we lack a comprehensive understanding of the prevalence of vitamin D deficiency or the mechanism by which vitamin D regulates the human immune system. This study examined the prevalence and correlates of vitamin D deficiency and the relationship between vitamin D and the immune system in healthy individuals.
Healthy individuals (n = 774) comprised of European-Americans (EA, n = 470), African–Americans (AA, n = 125), and Native Americans (NA, n = 179) were screened for 25-hydroxyvitamin D [25(OH)D] levels by ELISA. To identify the most noticeable effects of vitamin D on the immune system, 20 EA individuals with severely deficient (<11.3 ng/mL) and sufficient (>24.8 ng/mL) vitamin D levels were matched and selected for further analysis. Serum cytokine level measurement, immune cell phenotyping, and phosphoflow cytometry were performed.
Vitamin D sufficiency was observed in 37.5% of the study cohort. By multivariate analysis, AA, NA, and females with a high body mass index (BMI, >30) demonstrate higher rates of vitamin D deficiency (p<0.05). Individuals with vitamin D deficiency had significantly higher levels of serum GM-CSF (p = 0.04), decreased circulating activated CD4+ (p = 0.04) and CD8+ T (p = 0.04) cell frequencies than individuals with sufficient vitamin D levels.
A large portion of healthy individuals have vitamin D deficiency. These individuals have altered T and B cell responses, indicating that the absence of sufficient vitamin D levels could result in undesirable cellular and molecular alterations ultimately contributing to immune dysregulation.
Systemic lupus erythematosus (SLE) occurs more frequently among woman than men. We undertook the present study to determine whether the male-female ratio in SLE families is different than expected by chance, and whether excess male fetal loss is found.
All SLE patients met the revised American College of Rheumatology Classification criteria, while SLE-unaffected subjects were shown not to satisfy these same criteria. Putative family relationships were confirmed by genetic testing. Pregnancy history was obtained from all subjects, including unrelated control woman. Adjusted Wald binomial confidence intervals (CI) were calculated for ratio of boys to girls in families and compared to the expected ratio of 1.06
There were 2578 subjects with SLE with 6056 siblings. Considering all subjects, we found 3201 boys and 5434 girls (ratio=0.59, of 95% CI 0.576–0.602). When considering only the SLE-unaffected siblings, there were 2919 boys and 3137 girls (ratio=0.93, 95%CI 0.92–0.94). In both cases, the ratio of males-to-females is statistically different than the known birth rate. Among SLE patients as well as among their sisters and mothers there was an excess of male fetal loss compared to the controls.
Siblings of SLE patients are more likely to be girls than expected. This finding may be in part explained by excess male fetal loss, which is found among SLE patients and their first degree relatives.
Systemic lupus erythematosus; sex ratio; fetal loss; pregnancy
To compare the performance of the American-European Consensus Group (AECG) and the newly proposed American College of Rheumatology (ACR) classification criteria for Sjögren's syndrome in a well-characterized sicca cohort, given ongoing efforts to resolve discrepancies and weaknesses in the systems.
In a multidisciplinary clinic for the evaluation of sicca, we assessed features of salivary and lacrimal gland dysfunction and autoimmunity as defined by tests of both AECG and ACR criteria in 646 participants. Global gene expression profiles were compared in a subset of 180 participants.
Application of the AECG and ACR criteria resulted in classification of 279 and 268 participants with SS, respectively. Both criteria were met by 244 participants (81%). In 26 of the 35 AECG+/ACR- participants, the minor salivary gland biopsy focal score was ≥1 (74%), while 9 had positive anti-Ro/La (26%). There were 24 AECG-/ACR+ who met ACR criteria mainly due to differences in the scoring of corneal staining. All patients with SS, regardless of classification, had similar gene expression profiles, which were distinct from the healthy controls.
The two sets of classification criteria yield concordant results in the majority of cases and gene expression profiling suggests that patients meeting either set of criteria are more similar to other SS participants than to healthy controls. Thus, there is no clear evidence for increased value of the new ACR criteria over the old AECG criteria from the clinical or biological perspective. It is our contention, supported by this report, that improvements in diagnostic acumen will require a more fundamental understanding of the pathogenic mechanisms than is at present available.
Sjögren's syndrome; Classification; Diagnosis
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production and altered type I interferon expression. Genetic surveys and genome-wide association studies have identified more than 30 SLE susceptibility genes. One of these genes, TNIP1, encodes the ABIN1 protein. ABIN1 functions in the immune system by restricting the NF-κB signaling. In order to better understand the genetic factors that influence association with SLE in genes that regulate the NF-κB pathway, we analyzed a dense set of genetic markers spanning TNIP1 and TAX1BP1, as well as the TNIP1 homolog, TNIP2, in case-control sets of diverse ethnic origins.
We fine-mapped TNIP1, TNIP2, and TAX1BP1 in a total of 8372 SLE cases and 7492 healthy controls from European-ancestry, African-American, Hispanic, East Asian, and African-American Gullah populations. Levels of TNIP1 mRNA and ABIN1 protein were analyzed using quantitative RT-PCR and Western blotting, respectively, in EBV-transformed human B cell lines.
We found significant associations between genetic variants within TNIP1 and SLE but not in TNIP2 or TAX1BP1. After resequencing and imputation, we identified two independent risk haplotypes within TNIP1 in individuals of European-ancestry that were also present in African-American and Hispanic populations. These risk haplotypes produced lower levels of TNIP1 mRNA and ABIN1 protein suggesting they harbor hypomorphic functional variants that influence susceptibility to SLE by restricting ABIN1 expression.
Our results confirmed the association signals between SLE and TNIP1 variants in multiple populations and provide new insight into the mechanism by which TNIP1 variants may contribute to SLE pathogenesis.
The replacement of standard immunofluorescence anti-nuclear antibody (ANA) methods with bead-based assays is a new clinical option. A large, multi-racial cohort of SLE patients, blood relatives and unaffected control individuals was evaluated for familial aggregation and subset clustering of autoantibodies by high-throughput serum screening technology and traditional methods.
Serum samples (1,540 SLE patients, 1,127 unaffected relatives, and 906 healthy, population-based controls) were analyzed for SLE autoantibodies using a bead-based assay, immunofluorescence, and immunodiffusion. Autoantibody prevalence, disease sensitivity, clustering, and association with standard immunodiffusion results were evaluated.
ANA frequency in SLE patient sera were 89%, 73%, and 67% by BioPlex 2200 and 94%, 84%, and 86% by immunofluorescence in African-American, Hispanic, and European-American patients respectively. 60kD Ro, La, Sm, nRNP A, and ribosomal P prevalence were compared across assays, with sensitivities ranging from 0.92 to 0.83 and specificities ranging from 0.90 to 0.79. Cluster autoantibody analysis showed association of three subsets: 1) 60kD Ro, 52kD Ro and La, 2) spliceosomal proteins, and 3) dsDNA, chromatin, and ribosomal P. Familial aggregation of Sm/RNP, ribosomal P, and 60kD Ro in SLE patient sibling pairs was observed (p ≤ 0.004). Simplex pedigree patients had a greater prevalence for dsDNA (p=0.0003) and chromatin (p=0.005) autoantibodies than multiplex patients.
ANA frequencies detected by a bead-based assay are lower in European-American SLE patients compared to immunofluorescence. These assays have strong positive predictive values across racial groups, provide useful information for clinical care, and provide unique insights to familial aggregation and autoantibody clustering.
systemic lupus erythematosus; autoantibodies; ancestry
Immunoregulatory cytokine interleukin-10 (IL-10) is elevated in sera from patients with systemic lupus erythematosus (SLE) correlating with disease activity. The established association of IL10 with SLE and other autoimmune diseases led us to fine map causal variant(s) and to explore underlying mechanisms. We assessed 19 tag SNPs, covering the IL10 gene cluster including IL19, IL20 and IL24, for association with SLE in 15,533 case and control subjects from four ancestries. The previously reported IL10 variant, rs3024505 located at 1 kb downstream of IL10, exhibited the strongest association signal and was confirmed for association with SLE in European American (EA) (P = 2.7×10−8, OR = 1.30), but not in non-EA ancestries. SNP imputation conducted in EA dataset identified three additional SLE-associated SNPs tagged by rs3024505 (rs3122605, rs3024493 and rs3024495 located at 9.2 kb upstream, intron 3 and 4 of IL10, respectively), and SLE-risk alleles of these SNPs were dose-dependently associated with elevated levels of IL10 mRNA in PBMCs and circulating IL-10 protein in SLE patients and controls. Using nuclear extracts of peripheral blood cells from SLE patients for electrophoretic mobility shift assays, we identified specific binding of transcription factor Elk-1 to oligodeoxynucleotides containing the risk (G) allele of rs3122605, suggesting rs3122605 as the most likely causal variant regulating IL10 expression. Elk-1 is known to be activated by phosphorylation and nuclear localization to induce transcription. Of interest, phosphorylated Elk-1 (p-Elk-1) detected only in nuclear extracts of SLE PBMCs appeared to increase with disease activity. Co-expression levels of p-Elk-1 and IL-10 were elevated in SLE T, B cells and monocytes, associated with increased disease activity in SLE B cells, and were best downregulated by ERK inhibitor. Taken together, our data suggest that preferential binding of activated Elk-1 to the IL10 rs3122605-G allele upregulates IL10 expression and confers increased risk for SLE in European Americans.
Systemic lupus erythematosus (SLE), a debilitating autoimmune disease characterized by the production of pathogenic autoantibodies, has a strong genetic basis. Variants of the IL10 gene, which encodes cytokine interleukin-10 (IL-10) with known function of promoting B cell hyperactivity and autoantibody production, are associated with SLE and other autoimmune diseases, and serum IL-10 levels are elevated in SLE patients correlating with increased disease activity. In this study, to discover SLE-predisposing causal variant(s), we assessed variants within the genomic region containing IL10 and its gene family member IL19, IL20 and IL24 for association with SLE in case and control subjects from diverse ancestries. We identified SLE-associated SNP rs3122605 located at 9.2 kb upstream of IL10 as the most likely causal variant in subjects of European ancestry. The SLE-risk allele of rs3122605 was dose-dependently associated with elevated IL10 expression at both mRNA and protein levels in peripheral blood samples from SLE patients and controls, which could be explained, at least in part, by its preferential binding to Elk-1, a transcription factor activated in B cells during active disease of SLE patients. Elk-1-mediated IL-10 overexpression could be downregulated by inhibiting activation of mitogen-activated protein kinases, suggesting a potential therapeutic target for SLE.
Sjögren syndrome is a common, chronic autoimmune disease that typically produces inflammation and poor function of the salivary and lacrimal glands. Other organs can be affected, including the nervous system. Sensory peripheral neuropathy is a common manifestation of the disease.
Eight-eight patients attending a dry eyes-dry mouth clinic were classified as primary Sjögren syndrome and underwent a neurological examination. Anti-Ro (or SSA) and anti-La (or SSB) were determined using immunodiffusion as well as Inno-Lia and BioPlex ANA screen. Serum vitamin B12 levels were determined using an enzyme-linked microtiter plate assay.
Twenty-seven (31%) of the 88 patients had peripheral neuropathy as defined by loss of light touch, proprioception or vibratory sensation. Anti-Ro and anti-La were found by immunodiffusion in 12 patients, and 8 of these 12 had neuropathy (χ2=8.46, p=0.0036, odds ratio = 6.0 compared to those without precipitating anti-Ro and anti-La). Of the 27 patients with only anti-Ro by immunodiffusion, 13 (48.1%) of these had neuropathy (χ2 =5.587, p=0.018 compared to those without anti-Ro). There was no relationship of the other, more sensitive measures of anti-Ro and anti-La to neuropathy. In addition, we found no association of serum vitamin B12 levels to neuropathy among these patients with Sjögren syndrome.
Sensory peripheral neuropathy is common among patients with Sjögren syndrome, and is associated with the presence of anti-Ro and anti-La when determined by immunodiffusion.
Sjögren syndrome; autoantibodies; peripheral neuropathy; vitamin B12
Little is known about the genetic etiology of systemic lupus erythematosus (SLE) in individuals of African ancestry, despite its higher prevalence and greater disease severity. Overproduction of nitric oxide (NO) and reactive oxygen species are implicated in the pathogenesis and severity of SLE, making NO synthases and other reactive intermediate related genes biological candidates for disease susceptibility. This study analyzed variation in reactive intermediate genes for association with SLE in two populations with African ancestry.
A total of 244 SNPs from 53 regions were analyzed in non-Gullah African Americans (AA; 1432 cases and 1687 controls) and the genetically more homogeneous Gullah of the Sea Islands of South Carolina (133 cases and 112 controls) and. Single-marker, haplotype, and two-locus interaction tests were computed for these populations.
The glutathione reductase gene GSR (rs2253409, P=0.0014, OR [95% CI]=1.26 [1.09–1.44]) was the most significant single-SNP association in AA. In the Gullah, the NADH dehydrogenase NDUFS4 (rs381575, P=0.0065, OR [95%CI]=2.10 [1.23–3.59]) and nitric oxide synthase gene NOS1 (rs561712, P=0.0072, OR [95%CI]=0.62 [0.44–0.88]) were most strongly associated with SLE. When both populations were analyzed together, GSR remained the most significant effect (rs2253409, P=0.00072, OR [95%CI]=1.26 [1.10–1.44]). Haplotype and two-locus interaction analyses also uncovered different loci in each population.
These results suggest distinct patterns of association with SLE in African-derived populations; specific loci may be more strongly associated within select population groups.
systemic lupus erythematosus; African Americans; genetic association studies; oxygen compounds; single nucleotide polymorphism