A proliferation-inducing ligand (APRIL) is expressed by astrocytes and is increased in multiple sclerosis

A proliferation-inducing ligand (APRIL) is a newly described member of the tumour necrosis factor (TNF) superfamily that was first identified as a factor favouring tumorigenesis. APRIL is also important for several immune functions, including B-cell survival. Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system (CNS) that is commonly diagnosed in early adulthood. Several TNF superfamily members have been identified in brains of patients with MS, although their exact function within the CNS is presently unknown. To investigate whether APRIL is expressed in the CNS, we studied APRIL protein expression by immunohistochemistry in MS patients and controls. Morphologically, APRIL-positive cells appeared to be astrocytes. A two-colour immunohistochemistry revealed that APRIL expression was cytoplasmic, granular and restricted to GFAP-positive cells. Conversely, HLA class II-positive microglial cells were negative for APRIL expression. APRIL-positive cells were fewer in brains of controls compared with those with MS. We further corroborated our findings by studying APRIL protein expression in several glioblastoma cell lines, and found APRIL to be expressed by most cell lines analysed. APRIL's binding partner syndecan-1 (CD138) was detected in brains of neither MS nor control patients. Furthermore, B cells were detectable in the brain of one of five patients with MS. We conclude that APRIL is expressed by reactive astrocytes in MS and may be of relevance in gliotic scar formation.

Role of B cells in Sjögren´s syndrome - from benign lymphoproliferation to overt malignancy

The classical view of B cell biology is that these cells respond to foreign and self antigens and in this way promote protection, primarily by production of antibodies. However, recent studies suggest that B cells have diverse functions within the immune system other than antibody production, which could contribute to autoimmunity. This involves organization of lymphoid tissue, regulation of dendritic cells, antigen presentation, activation of T cells and production of cytokines. Both abnormalities in the distribution of B cell subsets, and recent discovery of clinical benefit after B cell depletion highlight the pivotal role of B cells in autoimmunity. This change in view of the role of B cells will be exemplified in one autoimmune disease namely Sjögren's syndrome.

Synovial inflammation in active rheumatoid arthritis and psoriatic arthritis facilitates trapping of a variety of oral bacterial DNAs

OBJECTIVE

To investigate the presence of oral bacterial DNAs in serum and synovial fluid (SF) of patients with active rheumatoid arthritis (RA) and psoriatic arthritis (PsA).

METHODS

Serum and SF samples from 16 RA patients, 14 PsA patients, and 9 osteoarthritis (controls) patients were extracted for oral bacterial DNA. This was used in a checkerboard DNA-DNA-hybridization set up, to identify 40 different bacteria.

RESULTS

Mean number +/- standard deviation (SD) of oral bacterial species in sera were 6.2 (3.2) in the RA group (p = 0.004) and 5.4 (2.7) in the PsA group (p = 0.009) compared to 2.1 (1.7) in the controls. Periodontitis associated species Porphyromonas gingivalis and Prevotella nigrescens were exclusively detected in RA and PsA. Mean number (+/- SD) of oral bacterial species in SF were 14.0 (6.8) in the RA (p = 0.001) and 19.4 (7.1) in the PsA group (p < 0.001) compared to 4.0 (1.7) in controls. P. gingivalis, Tannerella forsythensis and Prevotella intermedia were exclusively identified in RA and PsA SF. Higher means of DNAs were found in RA SF compared to RA serum (p < 0.001), and in PsA SF compared to PsA serum (p < 0.001). Higher concentrations of bacterial DNAs were found in RA and PsA compared to controls.

CONCLUSION

Higher variety and concentrations of oral bacterial DNAs were found in SF compared to serum of RA and PsA patients. These findings indicate that synovial inflammation in RA and PsA may favor trapping of oral bacterial DNAs, suggesting a perpetuating effect of oral pathogens in joint disease.

Gene therapeutics in Sjögren's syndrome

Sjögren's syndrome (SS) is a complex autoimmune disorder, characterised by mononuclear cell infiltration of exocrine glands, principally the lacrimal and salivary glands. Both cellular, in the form of autoreactive immune cells, and humoral factors, such as autoantibodies, contribute to the expression of the disease. SS can also occur as a systemic disease affecting several organs, and approximately 5% of the patients develop malignant lymphoproliferation. Today SS is considered uncurable. The treatment available is only palliative, and the treatment goals are to manage symptoms and prevent or limit tissue damage. This may involve both local and systemic measures. However, the existing systemic treatment of chronic inflammatory autoimmune diseases has several limitations and unwanted side effects. In recent years the possibility to treat diseases with gene therapy has gained interest and has become a subject of investigation. Given the multitude of factors contributing to the pathogenesis of SS, gene therapy is a major challenge, but may elicit great benefits if successful. Keeping this in mind, the possibility for gene therapeutics in SS in general and potential targets for gene therapy are discussed.

Genome-scale Assessment of Molecular Pathology in Systemic Autoimmune Diseases using Microarray Technology: A Potential Breakthrough Diagnostic and Individualized Therapy-design Tool

Systemic autoimmune rheumatic diseases are of complex aetiology, characterized by an intricate interplay of various factors. A myriad of genes lies behind the heterogeneous manifestations of these diseases, and the overexpression and repression of particular genes form a specific gene-expression profile (genetic fingerprints) that is characteristic to the given disease phenotype. Besides the description of various cell types by using gene-expression profiling, the data should be directly applicable to the design of individual therapeutic protocols for patients suffering from various autoimmune diseases. In this review, we summarize the gene-expression profile, various genetic signatures of different autoimmune diseases and give an overview on the possible interpretations of the data. The application of recent breakthroughs in high-throughput molecular profiling technologies, such as microarray technology has been the basis for a revolution in biomedical research, as well as diagnostics and pharmaceutical development. It is easy to envision a day when personalized medicine, which is the diagnosis and treatment of a given patient with agents and procedures tailored to that patient's genetics, physiology and pathology, will become the standard of care.

Dietary nucleotides and human immune cells. II. Modulation of PBMC growth and cytokine secretion

OBJECTIVE

The immune system is dependent on purines and pyrimidines as building blocks for DNA and RNA synthesis to enable rapid cell proliferation and protein synthesis. Emerging evidence suggests that dietary nucleotides optimize immune function. We investigated whether growth and function of human immune cells were affected by an exogenous source of nucleotides during specific antigen challenge.

METHODS

Peripheral blood mononuclear cells from healthy individuals (n = 10) were stimulated with influenza virus antigen and either DNA sodium from fish soft roe (DNA), RNA from bakers yeast (Saccharomyces cerevisiae) (RNA), 2' deoxyadenosine 5'-monophosphate sodium (dAMP), 2' deoxycytidine 5'-monophosphate sodium (dCMP), 2' deoxyguanosine 5'-monophosphate sodium (dGMP), 2' deoxyuridine 5'-monophosphate sodium (dUMP) or thymidine sodium (TMP). Growth effects were ascertained by measuring the amount of tritium-labeled thymidine, incorporated into cell DNA. Cell function was measured by detection of IFN-gamma, TNF-alpha and IL-10 production.

RESULTS

Specific nucleotide derivatives alone did not affect the growth of healthy peripheral blood mononuclear cells. However, the nucleotide derivatives influenced immune cell growth and cytokine secretion when cocultured with specific antigen. DNA, RNA, dAMP, dCMP and dUMP increased influenza virus antigen induced immune cell proliferation. In contrast dGMP and TMP inhibited the antigen-induced growth response. RNA and dAMP cocultured with virus antigen significantly increased peripheral blood mononuclear cell secretion of IFN-gamma, IL-10 and TNF-alpha. DNA increased virus antigen-induced immune cell secretion of IFN-gamma only, whereas dUMP significantly increased secretion of IL-10 only. dGMP completely inhibited virus-triggered IFN-gamma secretion, whereas TMP did not change the virus induced secretion pattern of measured cytokines.

CONCLUSION

Nucleotide derivatives affect growth and function of specific virus antigen-stimulated human immune cells in vitro.

The thymus is a source of B-cell-survival factors-APRIL and BAFF-in myasthenia gravis

The accumulation of B cells in the thymus is a common feature of myasthenia gravis (MG). To understand whether factors enhancing B-cell survival are increased in MG, we studied the expression of APRIL, BAFF and three of their receptors in the thymus. In hyperplastic thymi, macrophages expressed APRIL and BAFF, and germinal-center B cells, BAFF-R. CD138-positive plasma cells were abundant in MG thymi. By contrast, BCMA-positive plasma cells were scarce. The expression of APRIL and BAFF in MG thymi may reflect the establishment of an environment favorable to B-cell survival.

Human cell lines used in a micro neutralization test for measuring influenza-neutralizing antibodies

An in situ neutralization test (NT) including ELISA for the measurement of influenza antigen was developed and evaluated. Two human cell lines, fibroblasts (HS27) cells and salivary gland epithelial duct (HSG) cells, were compared with Madin-Darby Canine Kidney (MDCK) cells. The viral production in the human cell lines was lower than that for MDCK cells, which influenced the results of the assay in the HSG and HS27 cells. However, when lowering the infectious dose, the NT using HS27 cells gave a sensitive and stable assay with low background in the ELISA. The NT titres were very low when using HSG cells compared to MDCK cells. The HS27 NT was used to analyze the humoral response after an influenza A infection in patients from a placebo-controlled zanamivir study. We found no differences in NT titres between patients treated with zanamivir or placebo. The MDCK and HS27 NT gave higher titres and more pronounced titre differences than the gold standard haemagglutinin inhibition (HAI) assay. Compared to the HAI assay, the sensitive NT using HS27 cells also revealed heterologous NT-titre rises after influenza infection in the patients.

A genome-scale assessment of peripheral blood B-cell molecular homeostasis in patients with rheumatoid arthritis

OBJECTIVE

While rheumatoid arthritis (RA) is considered a prototypical autoimmune disease, the specific roles of B-cells in RA pathogenesis is not fully delineated.

METHODS

We performed microarray expression profiling of peripheral blood B-cells from RA patients and controls. Data were analysed using differential gene expression analysis and 'gene networking' analysis (characterizing clusters of functionally inter-relelated genes) to identify both regulatory genes and the pathways in which they participate. Results were confirmed by quantitative real-time polymerase chain reaction and by measuring the levels of 10 serum cytokines involved in the pathways identified.

RESULTS

Genes regulating and effecting the cell-cycle, proliferation, apoptosis, autoimmunity, cytokine networks, angiogenesis and neuro-immune regulation were differentially expressed in RA B-cells. Moreover, the serum levels of several soluble factors that modulate these pathways, including IL-1beta, IL-5, IL-6, IL-10, IL-12p40, IL-17 and VEGF were significantly increased in this cohort of RA patients.

CONCLUSIONS

These results outline aspects of the multifaceted role B-cells play in RA pathogenesis in which immune dysregulation in RA modulates B-cell biology and thereby contributes to the induction and perpetuation of a pathogenic humoral immune response.

Immunization with short peptides from the 60-kDa Ro antigen recapitulates the serological and pathological findings as well as the salivary gland dysfunction of Sjogren's syndrome

Sjögren's syndrome is a poorly understood autoimmune inflammatory illness that affects the salivary and lacrimal glands as well as other organ systems. We undertook the present study to determine whether mice immunized with short peptides from the 60-kDa Ro (or SSA) Ag, which is a common target of the autoimmunity of Sjögren's syndrome, develop an illness similar to Sjögren's syndrome. BALB/c mice were immunized with one of two short peptides from 60-kDa Ro that are know to induce epitope spreading. The animals were analyzed for the presence of anti-Ro and anti-La (or SSB) in the sera by immunoblot and ELISA. Salivary glands were collected and examined by histology after H&E staining. Salivary lymphocytes were purified and studied for cell surface makers by fluorescence-activated cell sorting. Timed stimulated salivary flow was measured. As reported previously, BALB/c mice immunized with 60-kDa Ro peptides developed an immune response directed against the entire Ro/La ribonucleoprotein particle that was similar to that found in humans with lupus or Sjögren's syndrome. Functional studies showed a statistical decrease in salivary flow in immunized mice compared with controls. Furthermore, there were lymphocytic infiltrates in the salivary glands of immunized animals that were not present in controls. The infiltrates consisted of both CD4- and CD8+ T lymphocytes as well as B lymphocytes. BALB/c mice immunized with 60-kDa Ro peptides develop anti-Ro, salivary gland lymphocyte infiltrates, and salivary dysfunction that is highly reminiscent of human Sjögren's syndrome.

The BAFF/APRIL system in systemic autoimmune diseases with a special emphasis on Sjögren's syndrome

Systemic autoimmune diseases, such as Sjögren's syndrome (SS), are characterized by a complex aetiology with multiple pathogenic factors. In SS, disturbed B-cell biology and humoral immunity including B-cell-activating factor (BAFF)-mediated processes have been described. Dysregulated BAFF expression has been described to lead to disease progression and perpetuation of humoral autoimmunity. Moreover, BAFF has been proposed to contribute to the development of B-cell malignancies. In this review, we summarize the current knowledge on BAFF with regard to SS pathology and discuss special features such as germinal centre (GC) formation and lymphomagenesis. Locally, in SS salivary glands, the reduced level of apoptosis among BAFF-expressing cells might lead to longer-existing BAFF expression and thereby maintain signalling for tissue-infiltrating B cells to proliferate and supposedly to become autoantibody-producing plasma cells. We assume that prolonged BAFF signalization may contribute to GC formation and/or lymphoma development in the disease. Finally, we discuss possibilities of novel treatments targeting the BAFF-system in SS.

Dietary nucleotides and human immune cells. II. Modulation of PBMC growth and cytokine secretion

OBJECTIVE

The immune system is dependent on purines and pyrimidines as building blocks for DNA and RNA synthesis to enable rapid cell proliferation and protein synthesis. Emerging evidence suggests that dietary nucleotides optimize immune function. We investigated whether growth and function of human immune cells were affected by an exogenous source of nucleotides during specific antigen challenge.

METHODS

Peripheral blood mononuclear cells from healthy individuals (n = 10) were stimulated with influenza virus antigen and DNA-Na+ from fish soft roe, RNA from bakers yeast (Saccharomyces cerevisiae), 2'deoxyadenosine 5'-monophosphate sodium, 2'deoxycytidine 5'-monophosphate sodium, 2'deoxyguanosine 5'-monophosphate sodium, or 2'deoxyuridine 5'-monophosphate disodium. Growth effects were ascertained by measuring the amount of tritium-labeled Thymidine 5'-monophosphate sodium incorporated into cell DNA. Cell function was measured by detection of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha, and interleukin-10 production.

RESULTS

Specific nucleotide derivatives alone did not affect the growth of healthy peripheral blood mononuclear cells. However, the nucleotide derivatives influenced immune cell growth and cytokine secretion when cocultured with specific antigen. DNA, RNA, deoxyadenosine monophosphate, deoxycytidine monophosphate, and deoxyuridine monophosphate increased influenza virus antigen-induced immune cell proliferation. In contrast, deoxyadenosine monophosphate and thymosine monophosphate inhibited the antigen-induced growth response. RNA and deoxyadenosine monophosphate cocultured with virus antigen significantly increased peripheral blood mononuclear cell secretion of IFN-gamma, interleukin-10, and tumor necrosis factor-alpha. DNA increased virus antigen-induced immune cell secretion of IFN-gamma only, whereas deoxyuridine monophosphate significantly increased secretion of interleukin-10 only. Deoxyguanosine monophosphate completely inhibited virus-triggered IFN-gamma secretion, whereas thymosine monophosphate did not change the secretion pattern of measured cytokines.

CONCLUSION

Nucleotide derivatives affect growth and function of specific virus antigen-stimulated human immune cells in vitro.

Distinct profiles of Sjögren's syndrome patients with ectopic salivary gland germinal centers revealed by serum cytokines and BAFF

The formation of ectopic germinal centers (GC) has been described in Sjögren's syndrome (SS), although little is known about the molecular basis of this phenomenon. These structures are a focus of in situ autoantibody production and have been hypothesized to be involved in lymphomagenesis in SS patients. Serum cytokines also play an important role in SS pathogenesis in part via immune dysregulation and may therefore contribute to ectopic GC formation. Herein, highly multiplex cytokine screening of SS patients with (SSGC+) and without (SSGC-) GC formation was done to identify cytokine profiles that correlate with this phenomenon. Serum levels of B-cell activating factor (BAFF) were also screened as a potential biomarker of immune dysregulation in SS and SSGC formation. Univariate analysis demonstrated that serum levels of a broad spectrum of immune and inflammatory modulating cytokines are upregulated in SSGC+ and SSGC- patients relative to unaffected controls IL-1beta, IL-2, IL-6, IL-15, IFN-gamma and CCL4 (MIP-1beta). SSGC+ patients were distinguished from healthy individuals by higher levels of IL-4, IL-10, GM-CSF, IFN-alpha, CCL3 (MIP-1alpha), CCL11 (Eotaxin) and BAFF, while SSGC+ and SSGC- patients differed in CCL2 (MCP-1) expression. Discriminant function analysis (DFA), a multivariate discrimination method that uses observed differences to characterize groups when casual relationships are not well understood, was employed to identify a subset of these biomarkers that maximally discriminate among SSGC+, SSGC- and unaffected individuals. The biomarker having the strongest discriminatory power identified by DFA besides CCL11 (Eotaxin) and IFN-gamma was BAFF. The variables identified by DFA are interdependent and are often of mechanistic significance to the pathologic states they distinguish, suggesting that these factors modulate SS pathology and SSGC formation in a synergistic manner.

The long-term effect of anti TNF-α treatment on temporomandibular joints, oral mucosa, and salivary flow in patients with active rheumatoid arthritis: A pilot study

OBJECTIVE

The objective of this study was to evaluate the long-term effects of anti-TNF-alpha treatment on temporomandibular joints (TMJs), oral mucosa, and salivary flow in RA.

STUDY DESIGN

Seventeen patients received infusions of TNF-alpha blocking agents after 0, 2, and 6 weeks, and then every 8 weeks until week 54 (follow-up). Clinical dysfunction index (Di) for the TMJ system, salivary flow, disease activity score (DAS28), and other medical assessments were calculated at weeks 0 and 54.

RESULTS

Median Di was 5.0 (range 0-21) at baseline and 1.0 (range 0-6) (P = .001) at follow-up. Mean salivary flow was 3.2 mL/15 minutes at baseline and 4.6 at follow-up (P = .055). Two (11.7%) of the patients developed oral candidiasis during the period of treatment. The median DAS28 was 6.2 (range, 4.7-7.7) at baseline and 4.1 (range, 1.6-6.8) at follow-up (P = .001).

CONCLUSION

We conclude that anti-TNF-alpha blocking treatments have beneficial effects on oral as well as general manifestations of RA.

Programmed cell death of peripheral blood B cells determined by laser scanning cytometry in Sjögren's syndrome with a special emphasis on BAFF

Functionally impaired B cells play an important role in the pathogenesis of Sjögren's syndrome (SS). The aim of the study was to investigate the apoptosis susceptibility of peripheral blood B cells from patients with SS and the impact of B cell activating factor (BAFF) on the apoptosis capability of these cells in correlation with IgG production. Peripheral blood B cells were isolated and stained for apoptosis markers (Bax, Bcl-2) and members of the TNF-R superfamily, CD95 and CD40. The apoptosis frequency of cells bearing these markers were assessed. Also, the apoptosis capability of cultured B-lymphocytes was investigated in medium alone, with anti-CD95 or with soluble BAFF. Quantitative ELISA was performed to detect plasma levels of sBAFF. Furthermore, the level of circulating B-cell cytokines was measured. BAFF levels were compared between patients with normal and elevated IgG levels. In SS, Bcl-2 positive B cell counts were significantly higher then in controls, also in this population the apoptosis frequency was reduced. Apoptosis within Bax+ and CD40+ B cells were significantly decreased in patients. BAFF induced a significant antiapoptotic effect in SS; also this effect was clearly evident in B cells from SS with hypergammaglobulinaemia. Plasma BAFF levels were significantly higher in SS, mostly in patients with hypergammaglobulinaemia. Plasma B-cell cytokines were raised in SS. In Sjögren's syndrome B cells, a general antiapoptotic tendency might lead to prolonged B-cell survival driven at least partly by elevated levels of BAFF and supposedly by B-cell cytokines. Also, the exaggerated BAFF stimulation might lead to excessive immunoglobulin production. The B-cell apoptosis defects, the increased BAFF levels-correlating with hypergammaglobulinaemia-together with the raised B-cell cytokine levels indicates the disturbed B-cell biology in the disease.

Polymyalgia rheumatica in primary Sjögren's syndrome

The aim of the study was to describe the clinical and laboratory aspects of primary Sjögren's syndrome (pSS) associated with polymyalgia rheumatica (PMR). The retrospective study compares the clinical and laboratory aspects of patients with pSS associated with PMR on a relatively large cohort of patients (n=16) and pSS patients without PMR (n=531). The prevalence of PMR among pSS patients was 3%, while in the average population, the prevalence of PMR is only 0.75%. PMR developed 8.7 years after the diagnosis of pSS in the older female pSS population (over 50 years of age), and in those with only glandular features. Interestingly the pSS/PMR patients had hypo gammaglobuline levels, while in the pSS patient group hypergammaglobulinaemia presented. Furthermore, positive ANA serology was more frequent among pSS/PMR patients. Since the clinical management of pSS/PMR is different from pSS, a better understanding of this clinical entity is essential.

Gene expression profiling of minor salivary glands clearly distinguishes primary Sjögren's syndrome patients from healthy control subjects

OBJECTIVE

To identify gene expression signatures in minor salivary glands (MSGs) from patients with primary Sjogren's syndrome (SS).

METHODS

A 16K complementary DNA microarray was used to generate gene expression profiles in MSGs obtained from 10 patients with primary SS and 10 control subjects. The data were analyzed by 2 different strategies, one strict primary analysis and one subanalysis that allowed for inclusion of genes with no signal in more than 3 samples from each group. The results were validated by quantitative reverse transcriptase-polymerase chain reaction techniques.

RESULTS

We found a distinct difference in gene expression levels in MSGs, enabling a simple class prediction method to correctly classify 19 of the 20 samples as either patient or control, based on the top 5 differentially expressed genes. The 50 most differentially expressed genes in the primary SS group compared with the control group were all up-regulated, and a clear pattern of genes involved in chronic inflammation was found. CXCL13 and CD3D were expressed in >/=90% of primary SS patients and in </=10% of the controls. Lymphotoxin beta, as well as a number of major histocompatibility complex genes, cytokines, and lymphocyte activation factors, manifested its role in the pathogenesis of SS. Numerous type I interferon genes related to virus infection were found among the top 200 genes, with increased expression in primary SS. Interestingly, the expression of carbonic anhydrase II, which is essential in saliva production and secretion, and the apoptosis regulator Bcl-2-like 2 were down-regulated in primary SS patients.

CONCLUSION

We have identified distinct gene expression profiles in MSGs from patients with primary SS that provide new knowledge about groups of genes that are up-regulated or down-regulated during disease, constituting an excellent platform for forthcoming functional studies.

Neuropsychiatric disturbances in SLE are associated with antibodies against NMDA receptors

To determine whether neuropsychiatric manifestations in patients with systemic lupus erythematosus (SLE) are influenced by antibodies against the human N-methyl-D-aspartate (NMDA) receptor types NR2a or NR2b. A decapeptide was synthesized containing a sequence motif present in the extracellular ligand-binding domain of NMDA receptors NR2a and NR2b, bound by the monoclonal murine anti-DNA antibody R4A. In an ELISA with the murine monoclonal R4v as positive control, plasma samples of 57 patients with SLE were examined for the anti-peptide (anti-NR2) antibody after the patients had been subjected to comprehensive psychological and cognitive testing. Poor performance on the Visual Paired Associates test (immediate), the Grooved Pegboard test, as well as high scores on the Beck Depression Inventory, and scales D-2 (depression), Pd-4 (psychopathic deviate), Sc-8 (schizophrenia), and Ma-9 (hypomania) of the MMPI-2 were significantly associated with elevated levels of anti-NR2 antibodies. The findings in several domains indicate an association between anti-NR2 antibodies and depressed mood in addition to decreased short-time memory and learning. Antibodies to NMDA receptors thus may represent one of several mechanisms for cerebral dysfunction in patients with SLE.

Association between circulating levels of the novel TNF family members APRIL and BAFF and lymphoid organization in primary Sjögren's syndrome

B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) are members of the tumour necrosis factor superfamily. We have examined circulating BAFF and APRIL in relation to serological deviations and lymphoid organization in the salivary glands of the chronic, autoimmune disorder Sjögren's syndrome. Lymphoid organization in the shape of ectopic germinal centers were detected in 33 of 130 consecutive minor salivary gland biopsies and coincided with increased focus score and elevated levels of serum IgG. Follicular dendritic cell networks, proliferation of mononuclear cells and altered B/T cell ratio also separated the two subgroups. Serum levels of sBAFF and sAPRIL were increased in Sjögren's syndrome compared to healthy blood donors, especially in anti-Ro/La+ patients. Though the differences could not be related to germinal center formation, positive correlations between serum levels of sBAFF and sAPRIL, focus score and IgG denotes their possible role in the disease progression of primary Sjögren's syndrome.

Induction of Oral Tolerance in Experimental Sjogren's Syndrome Autoimmunity

Previous studies have showed that immunization with peptides from Ro 60 results in Sjogren's syndrome (SS)-like condition in BALB/c mice. We hypothesized that oral feeding with Ro 60 peptide or Ro 60 would prevent the disease. Four groups (each consisting of 10) of BALB/c mice were used. Group I-III were immunized with Ro 274 peptide. Group IV mice were administered adjuvant only. Group II mice were fed orally with Ro 274 peptide and Group III with Ro 60 for 5 days before immunization. There was a significant reduction in the binding of sera from both Group II and Group III mice to most of the Ro multiple antigenic peptides bound by Group I mice. In Group III mice, salivary flow was maintained above that of the Group I mice (average: 117.5 versus 58.6 microl; t = 2.7; P = 0.02). Salivary infiltrates were drastically decreased in the Ro peptide or Ro 60-fed groups, compared to non-tolerized group. Two of eight mice in Group II and 3/6 mice in Group III had no infiltrates, whereas all eight mice studied in Group I had a significant number of infiltrates. Thus, epitope spreading was prevented, lymphocytic infiltration was blocked and saliva flow was restored by means of oral feeding of either Ro 274 or Ro 60 in this animal model of SS.

Sjogren's syndrome

Sjögren's syndrome (SS) is a chronic autoimmune disease affecting the exocrine glands, primarily the salivary and lacrimal glands. It has been suggested that exogenous agents may trigger SS in genetically predisposed individuals. However, at present, the etiology of SS is far from being understood, and no direct evidence for any of these triggers has been presented. The salivary and lacrimal glands from patients with SS harbor unique and highly selected T- and B-cell populations. Disturbance in glandular cell apoptosis may be one possible explanation for the sicca symptoms in SS. However, discrepancies between glandular destruction and salivary flow give rise to processes causing glandular dysfunction preceding or triggering glandular cell destruction. Recent reports suggested autoantibodies inhibiting neuronal innervation of acinar cells and defective water transport to be implicated in salivary secretion deficiency observed in SS. Several types of autoantibodies have been suggested to contribute to the pathogenesis of SS. However, how the tolerance to these structures is broken down is unknown at present. Studies on B-cell activating factor indicated that diminished apoptosis and disturbed B-cell maturation could be responsible for the occurrence of autoreactive B-cells and B-cell hyperreactivity. B-cell activation may also provide a basis for lymphoma development observed in up to 5% of the patients with SS.