Autoantibody synthesis in salivary glands of Sjögren's syndrome patients

Immunoassay Detects Salivary Anti-SSA/Ro-52 Autoantibodies in Seronegative Patients with Primary Sjögren's Syndrome

The diagnostic work-up for Sjögren's syndrome is challenging and complex, including testing for serum autoantibodies to SSA/Ro and a labial salivary gland biopsy. Furthermore, the diagnosis is often delayed. In this study, we tested the hypothesis that anti-SSA/Ro autoantibodies are detectable in the saliva of patients with primary Sjögren's syndrome (pSS) because the disease affects the salivary glands, and these autoantibodies display greater discriminatory performance in saliva than in serum. SSA/Ro-52 Ags were used to develop what is, to our knowledge, a novel quantitative electrochemical-based immunoassay: the electric field-induced release and measurement (EFIRM) platform. The clinical utility was determined by measuring salivary anti-SSA/Ro-52 autoantibodies in patients with pSS and sicca (n = 34), patients without pSS with sicca (n = 35), and healthy subjects (n = 41). The statistical analysis of discrimination included the area under the receiver operating characteristic curve. Salivary anti-SSA/Ro-52 autoantibodies were measured in 94% (32 of 34) of patients with pSS with 85% (29 of 34) seropositivity. Four of the five seronegative patients with pSS had EFIRM-measurable anti-SSA/Ro-52 autoantibodies in saliva. Additionally, 60% (21 of 35) of the seronegative patients without pSS who had sicca had EFIRM-detectable SSA/Ro-52 autoantibodies in saliva, indicating the onset of autoimmune disease. Two of the 41 healthy control subjects had EFIRM-detectable SSA/Ro-52 autoantibodies in their saliva. Salivary SSA/Ro-52 autoantibodies significantly discriminated patients with pSS or patients with the initial stage of autoimmune disease from healthy subjects with an area under the receiver operating characteristic curve of 0.91. Our findings suggest that the proposed saliva SSA/Ro-52 immunoassay improves early and accurate diagnosis of seronegative patients with pSS and patients with early-onset autoimmune disease.

Saliva-based SARS-CoV-2 serology using at-home collection kits returned via mail

Serology provides tools for epidemiologic studies, and may have a role in vaccine prioritization and selection. Automated serologic testing of saliva, especially specimens that are self-collected at home and sent to a laboratory via the mail without refrigeration, could be a highly-scalable strategy for population-wide testing. In this prospective study, non-vaccinated patients were recruited after PCR testing to self-collect saliva and return their specimens via mail. Longitudinal specimens were analyzed in order to monitor seroconversion in the weeks after a diagnostic PCR test for SARS-CoV-2. Diverse users self-collected saliva and returned specimens via mail in compliance with shipping regulations. At our pre-established threshold (0.963 AU/mL), salivary IgG reactivity to full-length spike protein achieved 95.8% sensitivity and 92.4% specificity at 2–4 weeks after diagnostic testing, which is comparable to the typical sensitivity and specificity achieved for serum testing. Reactivity to N antigen also was detected with 92.6% sensitivity and 90.7% specificity at 4–8 weeks after diagnostic testing. Moreover, serologic testing for endemic coronaviruses performed in multiplex with SARS-CoV-2 antigens has the potential to identify samples that may require retesting due to effects of pre-analytical factors. The easy-to-use saliva collection kit, coupled with thresholds for positivity and methods of flagging samples for retest, provides a framework for large-scale serosurveillance of SARS-CoV-2.

Correlations between clinical parameters of dry eye disease and serologic profiles in Sjögren's syndrome

PURPOSE

To investigate the difference in clinical parameters of dry eye disease (DED) according to the presence of serum anti-La antibodies and evaluate the correlations of autoantibody titers with DED parameters in patients with primary Sjögren's syndrome (pSS).

METHODS

Sixty-two patients diagnosed with pSS according to the 2016 ACR-EULAR classification criteria were classified into two groups depending on the presence of anti-La antibodies: group 1 (anti-Ro positive alone, n = 31) and group 2 (both anti-Ro and anti-La positive, n = 31). DED parameters (conjunctival and corneal ocular staining score (OSS), tear film break-up time (TBUT), Schirmer I test, lipid layer thickness (LLT), meiboscore, and ocular surface disease index), serum autoantibodies (anti-Ro, anti-La, rheumatoid factor (RF), and antinuclear antibody) and focus score were assessed.

RESULTS

The DED parameters were not significantly different between the two groups (P > 0.05). The anti-Ro titers, RF-positive rate, and the focus score were significantly higher in group 2 than in group 1 (P = 0.001, P = 0.049, P = 0.001, respectively). The anti-Ro titers had a significant positive correlation with conjunctival OSS (r = 0.273, P = 0.033) and the focus score had a positive correlation with LLT and meiboscore (r =  - 0.358, P = 0.072; r = 0.379, P = 0.056).

CONCLUSION

In this study, anti-Ro titers significantly correlated with conjunctival staining score, whereas anti-La did not statistically correlated with clinical DED parameters in SS. Meanwhile, anti-Ro titers and focus score were significantly higher in patients positive for both anti-Ro and anti-La, which suggests that examining anti-La with anti-Ro would be helpful in predicting clinical severities of SS patients.

Quantitative serology for SARS-CoV-2 using self-collected saliva and finger-stick blood

Convenient and widespread serology testing may alter the trajectory of the COVID-19 pandemic. This study seeks to leverage high-throughput, multiplexed serologic assays, which have been adopted as benchmarks for vaccine efficacy, to support large-scale surveys of SARS-CoV-2 immunity using finger-stick blood and/or saliva. Specifically, we optimized MSD’s serology assays, which were analytically validated for serum, to test self-collected finger-stick blood and saliva samples to identify prior infection. We show that these assays can be used with FDA-registered specimen collection devices to obtain quantitative measurements for self-collected samples. First, we show that salivary antibodies are stable without refrigeration or preservatives for at least 5 days. We selected classification thresholds for antibodies against SARS-CoV-2 N, RBD and Spike in finger-stick blood and saliva that provided 98% specificity in a set of individuals without known COVID-19 exposure. Using matched samples, we show that testing of saliva and finger-stick blood equivalently identified individuals with humoral responses to CoV-2 antigens. Moreover, we piloted a simple saliva collection kit that can be used to safely send samples through the mail using written instructions only. This work establishes key parameters to robustly assay self-collected finger-stick blood and saliva using quantitative immunoassays that could support large-scale serology testing.

Immune complexome analysis reveals the presence of immune complexes and identifies disease-specific immune complex antigens in saliva samples from patients with Sjögren's syndrome

Sjögren's syndrome (SS) is a chronic autoimmune disease that mainly damages the salivary and lacrimal glands. Immune complex (IC) formation triggers local inflammation through IC deposition and decreased antigen function. Some ICs can leak from the lesion and into the saliva, but no salivary ICs have been reported to date. We used immune complexome analysis to comprehensively identify antigens incorporated into IC (IC-antigens) in saliva samples from patients with SS (n = 9) or with xerostomia (n = 7). Neutrophil defensin 1 (67%), small proline-rich protein 2D (67%), myeloperoxidase (44%), neutrophil elastase (44%), cathepsin G (33%), nuclear mitotic apparatus 1 (33%) and phosphatidylinositol 4-phosphate 3-kinase C2 domain-containing subunit gamma (33%) were identified as new IC-antigens specifically and frequently detected in the saliva of SS patients. Of these, neutrophil defensin 1, myeloperoxidase, neutrophil elastase and cathepsin G are neutrophil intracellular proteins, which suggests that repeated destruction of neutrophils due to abnormal autoimmunity may be involved in the pathogenesis of SS. We also analyzed serum samples from three SS patients. There was little overlap of IC-antigens between two of the samples (fewer than 30% of the IC-antigens in the saliva samples), suggesting that many ICs are formed locally and independently of the circulation. In addition, we found that four SS-specific salivary antigens show sequence homology with several proteins of oral microbiomes but no antigen has homology with Epstein-Barr virus proteins. The homology between some IC-antigens and oral microbiome proteins may indicate the impact of oral infection on local autoimmunity through molecular mimicry theory.

Nephrological disorders and neurological involvement in pediatric primary Sjogren syndrome:a case report and review of literature

BACKGROUND

Sjögren syndrome (SS) is a rare disease in pediatrics, and little attention has been paid to the clinical feature in these patients. To date, there are few cases concern about neurological and nephrological disorders in childhood Sjögren syndrome. We describe a case of Sjögren syndrome in a 12-year-old girl who developed neurological disorders and interstitial nephritis and review the literature currently available on this topic.

CASE PRESENTATION

A 12-year-old girl was admitted to our hospital for arthritis and glucosuria. She was required to do labial gland and renal biopsy, because the positive for anti-nuclear antibody and anti-Sjögren syndrome B (anti-SSB) antibody. Then the biopsy was performed revealing the lymphocytic infiltrate in the small area and renal tubular interstitial damage,thus the diagnosis of Sjögren syndrome with tubular interstitial damage was made. Three months later, she presented again with headache, fever, nausea, vomiting and was recovered without drug therapy. Based on the patient's medical history, laboratory and imaging examination, and treatment, we speculate that the disorders of the nervous system were caused by the Sjögren syndrome. The girl has stable renal function and no residual nervous system damage in the next 1.5 years, but she underwent low dose prednisone therapy because of persistent renal glucosuria.

CONCLUSIONS

Nephrological disorders and neurological involvement are rare manifestations of Sjögren syndrome in children, and rarely presented as the initial symptoms. It should be suspected in children presenting with unexplained renal diseases, neurological abnormalities, or unexplained fever. Although there is no guidelines on the diagnosis and treatment of children Sjögren syndrome are currently available, early recognition and the appropriate treatment of renal damage and neurologic involvement would improve prognosis and prevent complications.

Epigenetic Regulation in the Pathogenesis of Sjögren Syndrome and Rheumatoid Arthritis

Autoimmune rheumatic diseases, such as Sjögren syndrome (SS) and rheumatoid arthritis (RA), are characterized by chronic inflammation and autoimmunity, which cause joint tissue damage and destruction by triggering reduced mobility and debilitation in patients with these diseases. Initiation and maintenance of chronic inflammatory stages account for several mechanisms that involve immune cells as key players and the interaction of the immune cells with other tissues. Indeed, the overlapping of certain clinical and serologic manifestations between SS and RA may indicate that numerous immunologic-related mechanisms are involved in the physiopathology of both these diseases. It is widely accepted that epigenetic pathways play an essential role in the development and function of the immune system. Although many published studies have attempted to elucidate the relation between epigenetic modifications (e.g. DNA methylation, histone post-translational modifications, miRNAs) and autoimmune disorders, the contribution of epigenetic regulation to the pathogenesis of SS and RA is at present poorly understood. This review attempts to shed light from a critical point of view on the identification of the most relevant epigenetic mechanisms related to RA and SS by explaining intricate regulatory processes and phenotypic features of both autoimmune diseases. Moreover, we point out some epigenetic markers which can be used to monitor the inflammation status and the dysregulated immunity in SS and RA. Finally, we discuss the inconvenience of using epigenetic data obtained from bulk immune cell populations instead specific immune cell subpopulations.

Antigen-driven selection of antibodies against SSA, SSB and the centromere 'complex', including a novel antigen, MIS12 complex, in human salivary glands

OBJECTIVES

Recent evidences have revealed that anti-SSA/SSB antibodies, the major autoantibodies in Sjögren's syndrome (SS), are produced in salivary glands. This study aims to clarify overall of autoantibody production at lesion site, including anti-centromere antibody (ACA)-positive SS.

METHODS

Antibodies of antibody-secreting cells in human salivary glands were produced as recombinant antibodies. The reactivity of these antibodies and their revertants were investigated by ELISA and newly developed antigen-binding beads assay, which can detect conformational epitopes. The target of uncharacterised antibodies was identified by immunoprecipitation and mass spectrometry. Autoantibody-secreting cells in salivary gland tissue were identified by immunohistochemistry using green fluorescent protein-autoantigen fusion proteins.

RESULTS

A total of 256 lesion antibodies were generated, and 69 autoantibodies including 24 ACAs were identified among them. Beads assay could detect more autoantibodies than ELISA, suggesting autoantibodies target to antigens with native conformation. After somatic hypermutations were reverted, autoantibodies drastically decreased antigen reactivity. We showed that MIS12 complex, a novel target of ACA, and CENP-C are major targets of ACA produced in salivary glands by examining cloned antibodies and immunohistochemistry, whereas few anti-CENP-B antibodies were detected. The target profiling of serum ACA from 269 patients with SS, systemic sclerosis (SSc), primary biliary cirrhosis (PBC) and healthy controls revealed that ACA-positive patients have antibodies against various sites of centromere complex regardless of disease.

CONCLUSION

We showed direct evidences of antigen-driven maturation of anti-SSA/SSB antibody and ACA in SS lesion. ACA recognises centromere 'complex' rather than individual protein, and this feature is common among patients with SS, SSc and PBC.

Comparative Glycomics of Immunoglobulin A and G From Saliva and Plasma Reveals Biomarker Potential

The N-glycosylation of immunoglobulin (Ig) G, the major antibody in the circulation of human adults, is well known for its influence on antibody effector functions and its alterations with various diseases. In contrast, knowledge on the role of glycans attached to IgA, which is a key immune defense agent in secretions, is very scarce. In this study we aimed to characterize the glycosylation of salivary (secretory) IgA, including the IgA joining chain (JC), and secretory component (SC) and to compare IgA and IgG glycosylation between human plasma and saliva samples to gain a first insight into oral cavity-specific antibody glycosylation. Plasma and whole saliva were collected from 19 healthy volunteers within a 2-h time window. IgG and IgA were affinity-purified from the two biofluids, followed by tryptic digestion and nanoLC-ESI-QTOF-MS(/MS) analysis. Saliva-derived IgG exhibited a slightly lower galactosylation and sialylation as compared to plasma-derived IgG. Glycosylation of IgA1, IgA2, and the JC showed substantial differences between the biofluids, with salivary proteins exhibiting a higher bisection, and lower galactosylation and sialylation as compared to plasma-derived IgA and JC. Additionally, all seven N-glycosylation sites, characterized on the SC of secretory IgA in saliva, carried highly fucosylated and fully galactosylated diantennary N-glycans. This study lays the basis for future research into the functional role of salivary Ig glycosylation as well as its biomarker potential.

Inducible Bronchus-Associated Lymphoid Tissue: Taming Inflammation in the Lung

Following pulmonary inflammation, leukocytes that infiltrate the lung often assemble into structures known as inducible Bronchus-Associated Lymphoid Tissue (iBALT). Like conventional lymphoid organs, areas of iBALT have segregated B and T cell areas, specialized stromal cells, high endothelial venules, and lymphatic vessels. After inflammation is resolved, iBALT is maintained for months, independently of inflammation. Once iBALT is formed, it participates in immune responses to pulmonary antigens, including those that are unrelated to the iBALT-initiating antigen, and often alters the clinical course of disease. However, the mechanisms that govern immune responses in iBALT and determine how iBALT impacts local and systemic immunity are poorly understood. Here, we review our current understanding of iBALT formation and discuss how iBALT participates in pulmonary immunity.

Defective DNA methylation in salivary gland epithelial acini from patients with Sjögren's syndrome is associated with SSB gene expression, anti-SSB/LA detection, and lymphocyte infiltration

The pathogenesis of primary Sjögren's syndrome (pSS) is complex, in part due to DNA methylation abnormalities. This study was undertaken to evaluate the importance of global DNA methylation ((5m)C) as determined in minor salivary glands (MSG) from well characterized pSS patients. Twenty-two pSS patients and ten controls were selected, and MSG were stained with anti-(5m)C, anti-(5m)C/anti-cytokeratin (KRT)19, or with anti-SSB/La antibodies (Ab). The DNA methylation status at the SSB gene promoter P1 and P1' was evaluated by methylation-sensitive restriction enzymes (MSRE) coupled with PCR. The effect of the DNA demethylating drug 5 azacytidine (5-Aza) was tested in the human salivary gland (HSG) cell line. In pSS, the reduction of global DNA methylation ((5m)C) was associated with lymphocyte infiltration, the emergence of (5m)C(low) and KRT19(high) acini, and the detection of circulating anti-SSB/La Ab, but not with disease activity (ESSDAI). Next, treating HSG cells with 5-Aza was effective in inducing SSB expression. Finally in pSS patients positive for anti-SSB/La Ab, we further observed DNA demethylation at the SSB gene promoter P1 with consequent SSB overexpression at both the transcriptional and protein levels in salivary gland epithelial cells. In conclusion, our results highlight the importance of DNA methylation in the pathophysiology of pSS and to the emergence of anti-SSB/La Ab.

Salivary biomarkers--an update

Saliva is the most easily available and accessible body fluid, which makes it one of the most sought after tools in diagnostic pathology. Markers expressed in saliva can be used for diagnosis and concurrent patient follow-up of diseases ranging from hereditary disorders to infections, as well as malignancies and also analysis of therapeutic levels of drugs. The emergence of hand-held devices has made possible the elucidation of point-of-care methods and research in the field has resulted in the assimilation of knowledge useful for clinical applications.

CLINICAL RELEVANCE

This article describes some of the latest research in saliva diagnostics and provides some information on the various hand-held devices available.

Subgroups of Sjögren syndrome patients according to serological profiles

Sjögren Syndrome (SS) is a systemic, autoimmune disorder characterized by lymphocytic infiltration of the exocrine glands. Different clinical associations have been described for each of the diverse autoantibodies found in SS patients. Antibodies directed against the Ro/La ribonucleoprotein complexes have been correlated with younger age, more severe dysfunction of the exocrine glands and a higher prevalence of extraglandular manifestations. Anti-nuclear antibodies and rheumatoid factors have been associated to extraglandular manifestations and an active immunological profile, while cryoglobulins are markers of more severe disease and correlate to lymphoma development and death. Antibodies to cyclic citrullinated peptides are scarce in SS and have been linked in some cases to the development of non-erosive arthritis. Furthermore, the presence of anti-mitochondrial antibodies and anti-smooth muscle antibodies in the sera of primary SS patients is considered indicative of primary biliary cirrhosis and autoimmune hepatitis, respectively. In addition, anti-centromere antibodies have been associated with a clinical phenotype intermediate between primary SS and systemic sclerosis, while antibodies against carbonic anhydrase have been related to renal tubular acidosis. Finally, an association of anti-muscarinic antibodies with cytopenias and a higher disease activity has also been described in primary SS. In conclusion, although not all of the above mentioned antibodies are useful for predicting distinct patient subgroups in SS, knowledge of the clinical associations of the different autoantibody specificities encountered in SS can advance our understanding of the disease and improve patient management.

Autoantibodies in Sjögren's syndrome: clinical presentation and regulatory mechanisms

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease mostly affecting the exocrine glands. A large number of autoantibodies have been detected in the serum of patients with pSS. Among them, anti-Ro/SSA and anti-La/SSB autoantibodies are the most common; they serve as disease markers and are involved in the pathogenesis of neonatal lupus syndrome (NLS). Other autoantibodies are associated with significant clinical phenotypes, such as cryoglobulins with development of non-Hodgkin's lymphoma, anti-centromere antibodies with Raynaud's phenomenon and anti-mitochondrial antibodies with liver pathology. As a result, pSS patients can be schematically categorized in subgroups according to their serological profile. Although the clinical utility of these autoantibodies is appreciated, little is known about the mechanisms related to their production and the regulation of the autoimmune response. In the present review, the clinical subsets of patients with pSS related to different autoantibodies as well as the regulating mechanisms of their production with special emphasis on idiotypic/anti-idiotypic network are discussed.

Diagnostic potential of saliva: current state and future applications

BACKGROUND

Over the past 10 years, the use of saliva as a diagnostic fluid has gained attention and has become a translational research success story. Some of the current nanotechnologies have been demonstrated to have the analytical sensitivity required for the use of saliva as a diagnostic medium to detect and predict disease progression. However, these technologies have not yet been integrated into current clinical practice and work flow.

CONTENT

As a diagnostic fluid, saliva offers advantages over serum because it can be collected noninvasively by individuals with modest training, and it offers a cost-effective approach for the screening of large populations. Gland-specific saliva can also be used for diagnosis of pathology specific to one of the major salivary glands. There is minimal risk of contracting infections during saliva collection, and saliva can be used in clinically challenging situations, such as obtaining samples from children or handicapped or anxious patients, in whom blood sampling could be a difficult act to perform. In this review we highlight the production of and secretion of saliva, the salivary proteome, transportation of biomolecules from blood capillaries to salivary glands, and the diagnostic potential of saliva for use in detection of cardiovascular disease and oral and breast cancers. We also highlight the barriers to application of saliva testing and its advancement in clinical settings.

SUMMARY

Saliva has the potential to become a first-line diagnostic sample of choice owing to the advancements in detection technologies coupled with combinations of biomolecules with clinical relevance.

Sjögren's syndrome: History, clinical and pathological features

The history, ocular and oral clinical features, and histopathology of Sjögren's syndrome are described. Primary Sjögren's syndrome is defined when only the ocular and oral components are present, while the secondary form refers to the association with a connective tissue disorder, especially rheumatoid arthritis, or other illness such as AIDS, hepatitis C infection, or biliary cirrhosis. Sjögren's syndrome is a common, but often overlooked disorder. Patients with severe disease run a forty-times risk of developing lymphoma usually of the B cell type.

Induction of autoimmunity by pristane and other naturally occurring hydrocarbons

Tetramethylpentadecane (TMPD, or commonly known as pristane)-induced lupus is a murine model of systemic lupus erythematosus (SLE). Renal disease and autoantibody production strictly depend on signaling through the interferon (IFN)-I receptor. The major source of IFN-I is immature monocytes bearing high levels of the surface marker Ly6C. Interferon production is mediated exclusively by signaling through TLR7 and the adapter protein MyD88. It is likely that endogenous TLR7 ligands such as components of small nuclear ribonucleoprotein complexes are involved in triggering disease. Lupus autoantibodies are produced in ectopic lymphoid tissue developing in response to TMPD. This model is well suited for examining links between dysregulated IFN-I production and the pathogenesis of human SLE, which like TMPD-lupus, is associated with high levels of IFN-I.

B-cell depletion in autoimmune diseases. Advances in autoimmunity

B cells play an important role in the pathogenesis of the autoimmune diseases. New advances in biological therapy provided a correct way in the management of these pathologies. Depletion of B cells with monoclonal antibodies reach an important place in the control of the diseases. I will present our experience with rituximab in the treatment of 131 patients with different autoimmune conditions, and conclude that this kind of therapy is safe, effective and constitutes a big step in the control of the majority of patients in which humoral response were aberrant. It is one of the many avenues that will allow to have a better future in the assessment and treatment of autoimmune diseases.

B cells in Sjögren's syndrome: indications for disturbed selection and differentiation in ectopic lymphoid tissue

Primary Sjögren's syndrome (pSS) is an autoimmune disorder characterized by specific pathological features. A hallmark of pSS is B-cell hyperactivity as manifested by the production of autoantibodies, hypergammaglobulinemia, formation of ectopic lymphoid structures within the inflamed tissues, and enhanced risk of B-cell lymphoma. Changes in the distribution of peripheral B-cell subsets and differences in post-recombination processes of immunoglobulin variable region (IgV) gene usage are also characteristic features of pSS. Comparison of B cells from the peripheral blood and salivary glands of patients with pSS with regard to their expression of the chemokine receptors CXCR4 and CXCR5, and their migratory capacity towards the corresponding ligands, CXCL12 and CXCL13, provide a mechanism for the prominent accumulation of CXCR4⁺CXCR5⁺ memory B cells in the inflamed glands. Glandular B cells expressing distinct features of IgV light and heavy chain rearrangements, (re)circulating B cells with increased mutations of cμ transcripts in both CD27^- and CD27⁺ memory B-cell subsets, and enhanced frequencies of individual peripheral B cells containing IgV heavy chain transcripts of multiple isotypes indicate disordered selection and incomplete differentiation processes of B cells in the inflamed tissues in pSS. This may possibly be related to a lack of appropriate censoring mechanisms or different B-cell activation pathways within the ectopic lymphoid structures of the inflamed tissues. These findings add to our understanding of the pathogenesis of this autoimmune inflammatory disorder and may result in new therapeutic approaches.

Proteomic diagnosis of Sjögren's syndrome

In the last few years, a growing interest has arisen in the application of proteomic analysis to rheumatic disease. Sjögren's syndrome is a systemic disease that affects exocrine glands directly, and is therefore expected to influence the composition of the whole human saliva and lachrymal fluid. Therefore, a rising number of studies have been performed in an attempt to characterize the salivary and lachrymal protein profiles of patients with Sjögren's syndrome by using a proteomic approach. This review summarizes the state of the art and the potential application of proteomics in the systematic search for diagnostic biomarkers in Sjögren's syndrome.

Analysis of parotid glands of primary Sjögren's syndrome patients using proteomic technology reveals altered autoantigen composition and novel antigenic targets

Sjögren's syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration, destruction of the salivary and lacrimal glands and production of autoantibodies against a variety of cellular proteins. The aberrant immune response against these autoantigens may begin or extend to other proteins that are not yet defined. Several studies have shown that autoantibody production is taking place in the affected salivary glands. In the present study, using proteomic approaches, we aimed to: (a) identify new autoantigens in the salivary glands of primary SS (pSS) patients and (b) evaluate the epigenetic changes of known autoantigens. Total parotid gland extracts of pSS patients were analysed using two-dimensional gel electrophoresis, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot with pSS patients' sera or purified autoantibodies and immunoprecipitation using homologous IgG. Identification of the unknown proteins was performed using mass spectrometry (MS). Immunoblot analysis on two-dimensional gels using purified anti-La/SSB antibodies revealed that pSS salivary glands contain high levels of post-translationally modified La/SSB autoantigen, while the native form of the protein is recognized faintly, in contrast to normal controls. Moreover, salivary glands of pSS patients contain post-translationally modified actin that becomes immunogenic in the microenviroment of the affected tissue. The alteration of the physicochemical properties of self-proteins could thus contribute to the break of immune tolerance against them.

Antagonist of interferon-inducible protein 10/CXCL10 ameliorates the progression of autoimmune sialadenitis in MRL/lpr mice

OBJECTIVE

Mononuclear cell infiltration of the salivary glands is a major feature of Sjögren's syndrome (SS) and its animal model. Local generation of chemokines and the presence of chemokine receptors on the infiltrating cells may be involved in this process. We undertook the present study to investigate the expression of chemokines during the development of autoimmune sialadenitis in MRL/lpr mice and the therapeutic effect of chemokine antagonists on sialadenitis.

METHODS

NH2-terminal-truncated interferon-inducible protein 10 (IP-10)/CXCL10 analogs were transfected into a nonmetastatic fibroblastoid cell line, MRL/N-1, and injected subcutaneously into MRL/lpr mice, and the effects on sialadenitis were monitored.

RESULTS

IP-10 analogs truncated by 5 or more amino acid residues from the N-terminal failed to induce chemotaxis and calcium influx by CXCR3-expressing cells. Of these, the most potent antagonist (AT) (IP-10-AT) was a molecule with methionine added after removal of the 5 N-terminal amino acid residues. Significantly increased expression of the Th1-associated chemokines IP-10, monokine induced by interferon-gamma/CXCL9, and interferon-inducible T cell chemoattractant/CXCL11 was induced in the ductal epithelium by interferon-gamma produced in the salivary glands, whereas expression of the Th2-associated chemokines thymus and activation-regulated chemokine (TARC)/CCL17 and monocyte-derived chemokine/CCL22 was almost undetectable during sialadenitis. Inoculation of IP-10-AT into MRL/lpr mice during the early stage of sialadenitis significantly reduced periductal mononuclear cell infiltration and parenchymal destruction compared with these features in control and TARC-AT-bearing mice. This was due to a significant reduction in infiltration of CXCR3+ T cells, predominantly Th1 cells, resulting in decreased interferon-gamma production.

CONCLUSION

We prepared a novel potent IP-10 antagonist and demonstrated its ability to ameliorate the progression of autoimmune sialadenitis. This agent may provide a new therapeutic approach to SS.

Assessment of SS-A and SS-B in parotid saliva of patients with Sjogren's syndrome

BACKGROUND

The purpose of this study was to compare the sensitivity of parotid saliva to that of serum in detecting anti-SSA/Ro and anti-SSB/La autoantibodies in patients with Sjögren's syndrome.

METHODS

Forty patients and 20 controls participated in the study; all patients met the 1993 European Community criteria for the diagnosis of Sjögren's syndrome. Healthy controls were age- and sex-matched individuals with no signs or symptoms of Sjögren's syndrome. Serum and saliva samples were evaluated using AffiniTech SSA/Ro and SSB/La antibodies kits (AffiniTech, Ltd. Bentonville, AR, USA). The results were also compared with serological status of SS-A and SS-B as reported by an independent clinical laboratory.

RESULTS

Serum was significantly more sensitive than saliva in detecting SSA/Ro and SSB/La antibodies (P = 0.001). There was high agreement between the results with the AffiniTech kits and the independent laboratory (kappa = 0.80; P < 0.001). However, there was poor agreement between saliva and serum results (kappa = 0.174; P = 0.168).

CONCLUSIONS

The overall results appear to support that serum analysis is effective method for evaluating the presence of SS-A and SS-B autoantibodies.

Anti-Ro/SSA and anti-La/SSB autoantibodies in the tear fluid of patients with Sjögren's syndrome

PURPOSE

To investigate the presence of anti-Ro/SSA and anti-La/SSB antibodies in the tear fluid and serum of patients with Sjögren's syndrome and to evaluate the association of these autoantibodies with the severity of keratoconjunctivitis sicca.

METHODS

Tear fluid and serum were obtained from 28 patients with Sjögren's syndrome and 17 age matched normal control subjects. Evaluation of tear fluid and sera anti-Ro/SSA and anti-La/SSB levels was done by using a quantitative enzyme linked immunosorbent assay kit designed for the quantitative measurement of IgG class autoantibodies directed against highly purified SSA and SSB antigens. Tear function and ocular surface were evaluated by Schirmer I test, tear break up time, and rose bengal staining. Dry eye symptom scores were recorded.

RESULTS

Increased levels of anti-Ro/SSA and anti-La/SSB antibodies were detected in sera of 57.1% and 50% of SS patients, respectively. Six patients had increased levels of anti-Ro/SSA in the tear fluid, in one case anti-Ro/SSA being detected in tear fluid when it was negative in serum. Ten patients had positive anti-La/SSB titres in tear fluid and in four of these patients, anti-La/SSB titres were not elevated in serum. A positive correlation was observed between serum and tear fluid titres of anti-Ro/SSA (r = 0.43, p = 0.02), but not of anti-La/SSB. Serum anti-Ro/SSA and anti-La/SSB concentrations correlated positively with dry eye symptom scores (r = 0.42, p = 0.02 and r = 0.48, p = 0.01, respectively) and negatively correlated with Schirmer I test scores (r = -0.39, p = 0.04 and r = -0.40, p = 0.03, respectively). Significant correlations were found between tear anti-La/SSB concentrations and dry eye symptom score (r = 0.56, p = 0.02) and also rose bengal staining scores of the ocular surface (r = 0.44, p = 0.02).

CONCLUSION

This study shows that autoantibodies against Ro/SSA and La/SSB antigens are present in the tear fluid of some patients with SS and their presence in serum or tear fluid is associated with the severity of keratoconjunctivitis sicca. Additional measurement of tear fluid levels of anti-Ro/SSA and anti-La/SSB may serve as a valuable diagnostic indicator of SS.

Cellular basis of ectopic germinal center formation and autoantibody production in the target organ of patients with Sjögren's syndrome

OBJECTIVE

To investigate functional properties of the germinal center (GC)-like structures observed in salivary glands of patients with Sjögren's syndrome (SS) and to determine the frequency with which such structures develop.

METHODS

Hematoxylin and eosin-stained sections from 165 minor salivary gland biopsy samples were screened for GC-like structures. Expression of markers for GCs (CD3, CD20, Ki-67, CD35, CD31), adhesion molecules (intercellular adhesion molecule 1, lymphocyte function-associated antigen 1, vascular cell adhesion molecule 1, very late activation antigen 4), chemokines (CXCL13, CCL21, CXCL12), and production of autoantibodies (anti-Ro/SSA and anti-La/SSB) was investigated by immunohistochemistry. Apoptosis was investigated by TUNEL staining.

RESULTS

GC-like structures were observed in 28 of 165 patients (17%). When GCs were defined as T and B cell aggregates with proliferating cells with a network of follicular dendritic cells and activated endothelial cells, such microenvironments were found in all patients in whom structures with GC-like morphology were observed. The defined microenvironments were not found in patients without apparent GC-like structures. The GCs formed within the target tissue showed functional features with production of autoantibodies (anti-Ro/SSA and anti-La/SSB) and apoptotic events (by TUNEL staining), and the local production of anti-Ro/SSA and anti-La/SSB autoantibodies was significantly increased (P = 0.04) in patients with GC development.

CONCLUSION

Lymphoid neogenesis and functional ectopic GC formation take place in salivary glands of a subset of patients with SS. Our data suggest that the ectopic secondary lymphoid follicles contain all elements needed for driving the autoimmune response. Our findings underscore a key role for the target organ in recruitment of inflammatory cells and propagation of the disease process.

Michael Mason prize essay 2003. Why do leucocytes accumulate within chronically inflamed joints?

Chronic inflammation is characterized by the accumulation of leucocytes within tissues. In rheumatoid arthritis the inflammatory infiltrate shares many architectural features with lymphoid tissue. For example, CD4 T cells and B cells accumulate in perivascular lymphoid structures within synovial tissue. CD8 T cells and neutrophils are found predominantly within synovial fluid. What drives these distinctive lymphoid microstructures and the relative contribution of lymphocytes and stromal cells such as fibroblasts to this process is the subject of this review. Cellular interactions between leucocytes and stromal cells such as macrophages and fibroblasts are important in generating tumour necrosis factor-alpha within the inflamed synovium. Therefore understanding how leucocytes accumulate within the inflamed synovium is likely to provide new therapeutic approaches to modify the inflammatory process. We have found that fibroblasts play a dominant role in defining the disordered synovial microenvironment in rheumatoid arthritis. Through their production of a variety of cytokines (interferon-beta, transforming growth factor-beta) and constitutive chemokines (stromal cell-derived factor-1, CXCL12) they directly alter the behaviour of lymphocytes that accumulate within chronically inflamed joints leading to their inappropriate survival and retention. We have extended these observations to another chronic persistent rheumatic disease, Sjögren's syndrome, and found that ectopic production of the constitutive B cell-attracting chemokine BCA-1 (CXCL13) is associated with lymphocyte accumulation and lymphoid tissue formation. These findings suggest that stromal cells such as fibroblasts play an important role in the switch from acute resolving to chronic persistent arthritis by allowing lymphocytes to accumulate in the wrong place at the wrong time.

The diagnostic applications of saliva--a review

This review examines the diagnostic application of saliva for systemic diseases. As a diagnostic fluid, saliva offers distinctive advantages over serum because it can be collected non-invasively by individuals with modest training. Furthermore, saliva may provide a cost-effective approach for the screening of large populations. Gland-specific saliva can be used for diagnosis of pathology specific to one of the major salivary glands. Whole saliva, however, is most frequently used for diagnosis of systemic diseases, since it is readily collected and contains serum constituents. These constituents are derived from the local vasculature of the salivary glands and also reach the oral cavity via the flow of gingival fluid. Analysis of saliva may be useful for the diagnosis of hereditary disorders, autoimmune diseases, malignant and infectious diseases, and endocrine disorders, as well as in the assessment of therapeutic levels of drugs and the monitoring of illicit drug use.

Subcellular redistribution and surface exposure of the Ro52, Ro60 and La48 autoantigens during apoptosis in human ductal epithelial cells: a possible mechanism in the pathogenesis of Sjögren's syndrome

The Ro52, Ro60 and La48 autoantigens are associated with Sjögren's syndrome (SS) and systemic lupus erythematosus (SLE). The mechanisms behind tolerance breakdown of these self-peptides remain unclear; however, apoptosis has been proposed to cause their presentation to the immune system. We have examined the localization of transiently expressed enhanced green fluorescent protein (EGFP)-tagged Ro52, Ro60 and La48 autoantigens in a human salivary gland (HSG) cell line by laser confocal microscopy under normal growth conditions and during apoptosis. Surface exposure of Ro52, Ro60 and La48 was demonstrated on nonfixed apoptotic cells with monoclonal antibodies (MoAbs) or with primary SS patient antisera. Laser scanning cytometry determined the apoptotic frequency. EGFP alone was studied as control. We found that Ro52 mainly is cytoplasmic, Ro60 both nuclear and cytoplasmic, while La48 only resides in the nucleus under normal conditions. During early apoptosis, La48 is dramatically redistributed to the cytoplasm, while the localization of Ro52 and Ro60 is maintained. All three autoantigens filled apoptotic blebs and covered TUNEL (terminal-deoxynucleotidyl-transferase-mediated dUTP-digoxigenin nick end labelling)-positive apoptotic bodies. Identical results were obtained in COS-7 cells. We have developed a transfection system to study the intracellular localization of the three autoantigens Ro52, Ro60 and La48, without antibody detection. During apoptosis, there is an intracellular redistribution of endogenous and EGFP-tagged Ro52, Ro60 and La48, leading to surface exposure. These findings may indicate a role for apoptosis in the induction and facilitation of humoral responses to Ro52, Ro60 and La48 in the autoimmune exocrinopathy of SS.

Intracellular trafficking and surface expression of SS-A (Ro), SS-B (La), poly(ADP-ribose) polymerase and alpha-fodrin autoantigens during apoptosis in human salivary gland cells induced by tumour necrosis factor-alpha

Autoantibodies directed against nucleic acid and protein complexes present in cell nuclei characterize autoimmune diseases and are employed in diagnosis. The mechanisms by which these autoantigens escape immunological tolerance are largely unknown, but a number of recent observations suggest that modified self-protein generated during apoptosis my play an important part in the development of autoimmunity. To investigate the possibility that autoantibodies in patients with Sjögren's syndrome are induced by apoptosis and presented on the surface of the cell, the internal distribution of autoantigens in apoptotic human salivary gland cells was studied in vitro. Salivary gland cells were treated with tumour necrosis factor-alpha, an apoptosis inducer. At increasing times after induction, cells were homogenized and cytoplasmic, cell surface membrane and nuclear compartments were fractionated using a sucrose density-gradient system. Autoantigens alpha-fodrin, SS-A (Ro), SS-B (La), and the enzyme poly(ADP-ribose) polymerase, were detected by conventional immunofluorescence and confirmed by Western immunoblotting. At increasing times after apoptosis, nuclear proteins SS-A (Ro) and SS-B (La), but not poly(ADP-ribose) polymerase were relocated from the cell nucleus to the cell surface membrane. Fodrin, a cytoplasmic protein, was also translocated to the cell membrane after cleavage of alpha-fodrin. These results show that autoantigens fodrin, SS-A (Ro) and SS-B (La) in human salivary gland cells undergo a striking redistribution during apoptosis and relocate to the cell membrane of apoptotic cells. The appearance of autoantigens on the surface of induced cells could form the basis of a mechanism for autoantigen presentation, processing and autoantibody induction.

Current issues in Sjögren's syndrome

Sjögren's syndrome is a chronic autoimmune and rheumatic disorder with prominent sicca complaints from the mucous membranes because of lack of proper exocrine secretions. There is no straightforward and simple diagnostic test for Sjögren's syndrome, although several classification criteria have been designed including several oral diagnostic tests. A new set of classification criteria in a joint effort by research groups in Europe and USA has recently been presented. A large number of autoantibodies have been reported in Sjögren's syndrome where, in some cases, the antibodies are correlated with the extent and severity of disease. The finding of serum autoantibodies directed against the muscarinic M3 receptor is an important advance in understanding the pathogenesis of not only the impaired glandular function but also associated features of autonomic dysfunction in some patients. The treatment of primary Sjögren's syndrome is still mainly symptomatic.

Expression of the B cell-attracting chemokine CXCL13 in the target organ and autoantibody production in ectopic lymphoid tissue in the chronic inflammatory disease Sjögren's syndrome

Sjögren's syndrome is an autoimmune disease characterized by lymphocytic infiltrates resembling secondary lymphoid organs in salivary glands. In this study, we demonstrate the expression of the lymphoid tissue homing chemokine CXCL13 (BCA-1/BLC), which has attracting properties for B cells and subsets of activated T cells, in salivary glands of patients with Sjögren's syndrome using immunohistochemistry and in situ hybridization. CXCL13 expression was primarily observed in epithelial cells in acini and ducts of inflamed glands while its receptor, CXCR5 (BLR-1), was expressed on the infiltrating mononuclear cells. In addition, cells producing antibodies against one of the major autoantigens in Sjögren's syndrome, Ro 52, were identified at the periphery of the follicular infiltrates indicating that the ectopic lymphoid tissue is directly involved in the disease process. Identification of CXCL13 and CXCR5 in salivary glands suggests that the target organ plays an essential role in the inflammatory process by recruiting B and T cells. These results also provide a molecular mechanism by which lymphoid neogenesis and ectopic germinal centre formation might occur in the glands of these patients, which may be the key step in the development of the chronic inflammatory process in Sjögren's syndrome.

Ectopic expression of the B cell-attracting chemokine BCA-1 (CXCL13) on endothelial cells and within lymphoid follicles contributes to the establishment of germinal center-like structures in Sjögren's syndrome

OBJECTIVE

To test the hypothesis that the formation of ectopic germinal center (GC)-like structures in Sjögren's syndrome (SS) is associated with the ectopic expression of the constitutive lymphoid tissue-homing chemokines B cell-attracting chemokine 1 (BCA-1; or, CXCL13) and stromal cell-derived factor 1 (SDF-1; or, CXCL12).

METHODS

Immunohistochemical and immunofluorescence analysis was used to determine the expression of the constitutive chemokines BCA-1 (CXCL13) and SDF-1 (CXCL12) in salivary glands from 5 SS patients and 3 non-SS patients. In addition, the expression of their respective receptors (CXCR5 and CXCR4) was examined on infiltrating lymphocytes. Human tonsil was used as a positive control for secondary lymphoid tissue.

RESULTS

BCA-1 (CXCL13) was expressed within lymphoid aggregates in SS, which shared many structural features with GCs in tonsil. BCA-1 (CXCL13) was completely absent in control biopsy samples from patients who did not have SS. High levels of BCA-1 (CXCL13) were also found on endothelial cells in salivary glands from SS patients. Diseased SS tissue was infiltrated by CXCR5-expressing B cells which organized into GC-like clusters. In complete contrast, SDF-1 (CXCL12), a constitutive chemokine involved in leukocyte retention within lymphoid tissue, was expressed by epithelial cells in both diseased and control samples. The chemokine receptor for SDF-1, CXCR4, was expressed on T cells that accumulated in a periductal distribution in diseased tissue.

CONCLUSION

The ectopic expression of BCA-1 (CXCL13) on endothelial cells and within GC-like structures, together with the strong expression of SDF-1 (CXCL12) on ductal epithelial cells, is a unique feature of inflamed glands in SS. By creating a local microenvironment supportive of focal B cell aggregation and differentiation, with structural features that are remarkably similar to GCs, BCA-1 (CXCL13) and SDF-1 (CXCL12) may contribute to the excessive production of high-affinity, class-switched autoantibodies and to the high incidence of B cell lymphomas classically associated with SS.

Inflamed kidneys of NZB / W mice are a major site for the homeostasis of plasma cells

(NZB x NZW)F1 (NZB / W) mice develop a disease similar to human systemic lupus erythematosus (SLE), including autoantibody production, hypergammaglobulinaemia and inflammation of the kidneys. It is known that large numbers of lymphocytes infiltrate the kidneys of these mice. Here, we compare the roles of bone marrow, spleen and inflamed kidneys of NZB / W mice in the activation of B cells and the persistence of antibody-secreting cells (ASC). ASC are present in the kidneys of NZB / W mice with full-blown disease, as many as in the spleen and bone marrow. The specificity of the ASC in the inflamed kidneys is not restricted to self-antigens. After immunization of NZB / W mice with ovalbumin (OVA) the OVA-specific ASC are found initially in the spleen. Weeks later, OVA-specific ASC are found in high numbers in the bone marrow and the kidneys of these mice, but no longer in the spleen. As determined by FACS, B cells with a germinal center phenotype (B220(+) / PNA(+)) are found only in very low numbers in the kidneys, but in high numbers in the spleen of NZB / W mice. Germinal centers could not be detected in the kidneys, but in the spleen, and plasma cells appear to be scattered over the tissue. These data suggest that in autoimmune NZB / W mice, plasma cells generated in immune reactions of secondary lymphoid organs, later accumulate and persist in the inflamed kidneys, were they enhance the local concentrations of Ab and immunocomplexes. These experiments identify the inflamed kidneys of NZB / W mice as a site of prime relevance for the homeostasis of plasma cells, irrespective of their specificity.

Primary Sjögren's syndrome: oral aspects on pathogenesis, diagnostic criteria, clinical features and approaches for therapy

Primary Sjögren's syndrome (pSS) is a chronic inflammatory systemic autoimmune disease affecting the exocrine glands and predominantly the salivary and lacrimal glands. The impaired gland function is assumed to be a result of progressive lymphocyte-mediated destruction of the exocrine gland tissue leading to the cardinal manifestations, hyposalivation and keratoconjunctivitis sicca (KCS), as well as devastating symptoms of oral and ocular dryness. Although primarily characterised as an exocrine dysfunction, non-exocrine organs may also be affected. The onset and course of pSS is usually insidious but may develop into a disabling disease, which profoundly affects the patient's general well being and quality of life. Moreover, pSS may even evolve into a lymphoid malignancy. The aetiology of pSS remains unknown but the pathogenesis of exocrine cell damage is apparently multi-factorial, including immunological, genetic, hormonal and viral components. Recent research also includes neurogenic aspects of exocrine gland dysfunction, including the interference of immune mediators with glandular response to neurotransmitters released from nerve fibres. pSS usually affects middle-aged women and the female:male ratio is 9:1. The prevalence varies from 0.29-4.8%, depending on the population sampled and the diagnostic criteria used. At present, there are no specific diagnostic tests for pSS and no universally accepted diagnostic criteria. The current therapy is primarily symptomatic. This review focuses on the current oral clinical, diagnostic, pathogenic and therapeutic aspects of pSS.

Secretory autoantibodies in primary biliary cirrhosis (PBC)

It is unclear how breakdown in immune tolerance to the ubiquitous self-antigen pyruvate dehydrogenase complex (PDC), seen in the autoimmune liver disease PBC, gives rise to tissue damage with such a limited distribution (restricted to the liver and salivary and lachrymal glands). One property shared by these tissues is the ability to export secretory IgA by the process of transcytosis. The aim of this study was to address whether active transcytosis of anti-PDC IgA occurs across epithelial surfaces in PBC, a finding that might implicate mucosal specific immune mechanisms in the pathogenesis of this disease. Parotid saliva was collected from PBC patients (n = 44), normal controls (n = 28) and PBC patients post-liver transplantation (n = 11). IgA and secretory component-positive antibodies specific for human PDC were quantified by ELISA and immunoblotting. PBC patients (but not control subjects) had anti-PDC IgA in their saliva. The strong correlation seen between titres detected using anti-IgA and anti-secretory component antibodies suggests that this is predominantly secretory IgA reaching the saliva by the active process of epithelial transcytosis. Titres of anti-PDC IgA remain high in PBC patients saliva post-liver transplant. Findings from studies of IgA in viral infection models raise the possibility that anti-PDC IgA could, whilst undergoing transcytosis, bind to newly translated PDC components in the cytoplasm of the epithelial cells transporting them out of the cell and inducing metabolic damage. This model would, if correct, help to explain the mechanism and tropism of tissue damage in PBC and the aberrant pattern of expression of PDC on the apical surface of biliary and salivary epithelial cells reported in this disease.

Saliva in health and disease: an appraisal and update

Saliva plays an important role in oral health monitoring, regulating and maintaining the integrity of the oral hard tissues and some soft tissues. This paper reviews the role of saliva, the prevalence of oral dryness and the consequent importance of salivary flow as well as the relationship between xerostomia and salivary gland hypofunction amongst the causes of oral dryness. Other aspects of oral conditions associated with saliva are also reviewed including Sjögren's Syndrome and oesophageal function. Finally, knowledge, and the current use of salivary tests and the utilisation of saliva as a diagnostic fluid are surveyed.

Autoantibodies to La/SSB in patients with primary Sjögren's syndrome (pSS) are associated with upregulation of La/SSB mRNA in minor salivary gland biopsies (MSGs)

Recent studies have shown that minor salivary glands (MSGs) of patients with primary Sjögren's syndrome (pSS) are sites of anti-La/SSB autoantibody production. The aim of this study was to investigate the expression of La/SSB mRNA in MSGs of patients with pSS. La/SSB mRNA expression was studied by in situ hybridization in six biopsies of pSS patients with anti-La/SSB antibodies, nine pSS patients without anti-La/SSB and 10 patients with non-specific sialadenitis. Oligonucleotide probes corresponding to c-DNA encoding four linear epitopes of La/SSB (bp 423-471, bp 861-909, bp 903-954 and bp 1048-1092) were utilized. cDNA encoding linear epitopes of Ro52 (bp 786-837), Ro60 (bp 654-702) and the housekeeping genes of Sm and GAPDH were used as controls. The results were expressed as percent of positive cells by image analysis. Serum levels of anti-La/SSB autoantibodies were correlated with the presence and the intensity of La/SSB mRNA labeling. All pSS patients with anti-La/SSB antibodies in their serum expressed mRNA transcripts of epitopes 301-318 aa and 349-364 aa (encoded by the cDNA probes bp 903-954 and bp 1048-1092 respectively), predominantly in acinar and mononuclear cells of MSGs. These epitopes are the major targets of anti-La/SSB antibodies. Serum levels of anti-La/SSB antibodies were correlated with the number of positively stained cells in MSGs. Two of the nine pSS patients without anti-La/SSB autoantibodies and 2/10 non-pSS patients expressed the mRNA of the La/SSB molecule. The probes of RO52 and Ro60 epitopes did not react, while mRNA encoding the housekeeping genes of Sm and GAPDH was positive in all samples. In conclusion, pSS patients with anti-La/SSB antibodies showed upregulation of La/SSB mRNA in acinar and mononuclear cells of MSGs. Thus, active synthesis of La/SSB in MSGs of pSS seems to play an important role in the autoimmune response of the affected tissues.

Salivary gland cytokine expression in NOD and normal BALB/c mice

The autoimmune diabetes-prone nonobese diabetic (NOD) mouse develops a chronic lymphocytic infiltration of endocrine and exocrine glands. The objectives of this study were to characterize the salivary immune infiltration and cytokine expression of NOD mice and compare these findings to those of normal BALB/c mice. A decline in salivary flow rates in NOD mice began between 8 and 12 weeks of age. At this same time lymphocytic foci are detectable in the salivary glands. Lymphocytic infiltration in the salivary glands of NOD mice increased with age and simultaneously salivary function declined. No lymphocytic infiltration was seen in BALB/c salivary tissues. Messenger RNA expression of several inflammatory cytokines, including interleukin-1beta (IL-1beta), IL-2, IL-10, interferon-gamma, and tumor necrosis factor-alpha was detected in the submandibular glands of both NOD and BALB/c mice by the reverse transcription polymerase chain reaction. IL-4 synthesis was also present in some tissues. Immunohistochemical analysis demonstrated the intense expression of inflammatory cytokines within lymphocytic infiltrates and epithelial cells of all NOD mice. Minimal expression of the same cytokines was detected only occasionally in BALB/c tissues stained in parallel. These results demonstrate cytokine expression in the salivary glands of normal mice and suggest that the overexpression of these inflammatory cytokines is likely involved in the development and progression of the organ-localized autoimmunity in the salivary glands of NOD mice.

Salivary proteins in rheumatoid arthritis and Sjögren's syndrome: one-dimensional and two-dimensional electrophoretic studies

Parotid saliva from patients with rheumatoid arthritis and Sjögren's syndrome contains elevated levels of multiple anionic proteins of pI approximately 3.75-4.75 and Mr approximately 32,000. Further studies on these components involving narrow range pH 3.5-5.0 immobilized pH gradients (IPGs) and two-dimensional (2D) electrophoresis with narrow- or broad-range IPGs in the first dimension have confirmed their association with these disorders. Immunoblotting showed that these proteins include multiple forms of tissue kallikrein. Treatment with neuraminidase results in removal of these anionic substances from the pH 3.75-4.75 region of gels, thereby indicating that heterogeneity arises from differences in sialation of the carbohydrate residues. The results of treatment with endo-beta-N-acetylglucosaminidase (Endo F) or peptide N-glycosidase (PNGase F) and comparison of the results with studies on human urinary kallikrein suggest that proteins other than kallikrein may also comigrate in the anionic region of gels and that deglycosylation of kallikrien is incomplete in the experimental conditions used, probably because of inadequate denaturation. The paper also reviews the limitations of current criteria used in the investigation of salivary gland function associated with connective tissue disorders and the diagnosis of these. It assesses the potential of electrophoresis in forming the basis of new diagnostic techniques and furthering the understanding of the nature of these diseases. The findings presented in this paper could make a key contribution to this.

Ro/SS-A-reactive B lymphocytes in salivary glands and peripheral blood of patients with Sjögren's syndrome

The aim of this study was to investigate the production of anti-Ro/SS-A antibodies in labial salivary glands (LSG) and peripheral blood (PB) of Sjögren's syndrome (SS) patients. The ELISPOT method was performed to quantify the frequency of LSG lymphocytes and PB lymphocytes spontaneously secreting anti-Ro/SS-A antibodies. The total number of IgG-, IgA- and IgM-producing cells was also quantified. The bovine Ro 60-kD protein was used as target antigen. Six of six primary SS patients had LSG B cells producing anti-bovine Ro 60 kD of the IgG isotype, and two of two primary SS patients had in addition PB lymphocytes producing anti-bovine Ro 60 kD of the IgG isotype. The six patients who had IgG antibodies against the Ro/SS-A antigen in LSG all had focus scores of >/= 7 in biopsies of LSG. The results indicate that SS patients with a high degree of local inflammation in LSG have B cells producing anti-Ro/SS-A antibodies in both LSG and PB. Thus, the anti-Ro/SS-A antibodies may have pathogenic importance in the progression of the exocrinopathy of SS.

Ro/SS-A- and La/SS-B-reactive B lymphocytes in peripheral blood of patients with Sjögren's syndrome

The aim of this study was to investigate the production of anti-Ro/SS-A and anti-La/SS-B antibodies in peripheral blood (PB) of patients with Sjögren's syndrome (SS). The ELISPOT method was performed to quantify the frequency of PB lymphocytes spontaneously secreting anti-Ro/SS-A and/or anti-La/SS-B antibodies. The total number of IgG-, IgA- and IgM-producing cells was also quantified. The recombinant Ro 52-kD, Ro 60-kD and La 48-kD proteins were used as target antigens. Three of 18 SS patients had PB lymphocytes secreting IgG antibodies against the recombinant Ro 52-kD protein. The same three patients had high serum titres of anti-Ro 52-kD antibodies. In addition, these patients were classified as having severe disease, and all three had focus scores of >/= 8 in biopsies of the labial salivary glands (LSG). The correlation between the number of PB cells producing IgG antibodies against the recombinant Ro 52-kD protein and the focus score was significant (P < 0.01). The results indicate that only SS patients with severe disease and high degree of local inflammation in LSG have B cells producing anti-Ro/SS-A antibodies in PB. Thus, most of the spontaneous autoantibody production must take place in other body compartments, e.g. in exocrine glands and probably also in the lymphoid organs and/or other mucosal sites.

Detection of anti-Ro/SSA and anti-La/SSB autoantibody-producing cells in salivary glands from patients with Sjögren's syndrome

OBJECTIVE

To investigate and identify the presence of cells producing anti-Ro/SSA and anti-La/SSB autoantibodies in salivary glands from patients with Sjögren's syndrome (SS).

METHODS

Submucosal salivary gland biopsy samples from 10 SS patients (8 with and 2 without circulating Ro and La autoantibodies) and 14 control subjects were evaluated. Frozen tissue sections were immunostained by an avidin-biotin complex technique, using biotinylated recombinant Ro and La proteins as detection reagents. Autoantibody levels in SS patient sera were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Cells producing autoantibodies to the Ro 52-kd, Ro 60-kd, and La proteins were recorded in 8, 6, and 7 of the 10 SS patient biopsy samples, respectively. Samples from the 2 SS patients without circulating Ro and La autoantibodies were negative for these autoantibody-producing cells, as were all control biopsy samples. A strong positive correlation between the presence of autoantibodies in sera and the presence of autoantibody-producing cells in glandular biopsy tissues was evident. The number of autoantibody-producing cells and the serum autoantibody levels were also correlated (r(s)=0.94, P < 0.0001).

CONCLUSION

Using a novel technique, we have demonstrated the presence of Ro and La autoantibody-producing cells in salivary gland biopsy tissues from patients with SS. These findings indicate that anti-Ro/ SSA and anti-La/SSB autoantibodies are produced and are present at sites of inflammation and indicate their potential involvement in the autoimmune exocrinopathy of this disease.