Progress and regression within primary Sjögren's syndrome

The value of animal models to study immunopathology of primary human Sjögren's syndrome symptoms

Sjögren's syndrome (SjS) is a complex chronic autoimmune disease of multifactorial etiology that results in eventual loss of secretory function in the exocrine glands. The challenges towards finding a therapeutic prevention or treatment for SjS are due primarily to a lack of understanding in the pathophysiological and clinical progression of the disease. In order to circumnavigate this problem, there is a need for appropriate animal models that resemble the major phenotypes of human SjS and deliver a clear underlying biological or molecular mechanism capable of defining various aspects for the disease. Here, we present an overview of SjS mouse models that are providing insight into the autoimmune process of SjS and advance our focus on potential diagnostic and therapeutic targets.

The Interferon-Signature of Sjögren's Syndrome: How Unique Biomarkers Can Identify Underlying Inflammatory and Immunopathological Mechanisms of Specific Diseases

Innate immune responses direct the nature and specificity of downstream adaptive responses in autoimmune diseases. One of the strongest markers of innate immunity is the up-regulated expression of interferon (IFN) and IFN-responsive/stimulated genes (IRGs/ISGs). While multiple IRGs are induced during the innate phase of host responses, transcriptome data suggest unique IRG-signatures for different diseases. Sjögren's syndrome (SjS) is characterized by chronic immune attacks against exocrine glands leading to exocrine dysfunction, plus strong up-regulated expressions of IFN IRG transcripts. Genome-wide transcriptome analyses indicate that differentially expressed IRGs are restricted during disease development and therefore define underlying etiopathological mechanisms. Here we review the innate immune-associated IFN-signature of SjS and show how differential gene expressions of IRG/ISG sets interact molecularly and biologically to identify critical details of SjS etiopathogenesis.

Malignant lymphoma in primary Sjögren's syndrome: an update on the pathogenesis and treatment

OBJECTIVES

Sjögren's syndrome (SS), a chronic autoimmune disorder, particularly compromises the function of exocrine glands. Its association with lymphoma is well documented. Our aim was to systematically review the molecular, clinical, histopathologic, and therapeutic aspects of these SS-related malignant lymphoproliferations.

METHODS

The literature was searched for original articles published between 1968 and 2012 focusing on the risk factors for lymphoma development in Sjögren's syndrome using MEDLINE and PubMed. The search terms we used were "Sjögren's syndrome," "lymphoma," and "risk factors." All papers identified were English-language, full-text papers.

RESULTS

A low-grade marginal-zone lymphoma related to mucosa-associated lymphoid tissue is the commonest lymphoid neoplasia in SS. The majority of SS-associated lymphomas are characterized by localized stage, indolent clinical course, and recurrence in other extranodal sites. Although the transition from a chronic inflammatory condition to malignant lymphoma is a multistep process that is yet poorly understood, there is increasing evidence that chronic antigenic stimulation by an exoantigen or autoantigens plays an essential role in the development of SS-associated lymphoproliferation.

CONCLUSIONS

This review discusses the pathogenetic aspects of lymphomagenesis in SS. Recent advances in the treatment of lymphoma in SS are also stated.

Primary Sjogrens syndrome is associated with impaired autonomic response to orthostasis and sympathetic failure

BACKGROUND

Symptoms in keeping with autonomic dysfunction are commonly described by primary Sjögrens syndrome patients (pSS); whether objective abnormalities of autonomic function occur is unclear. This study set out to explore dynamic cardiovascular autonomic responses in pSS and their relationship with symptoms and quality of life.

METHODS

Twenty-one people from the UK pSS registry, 21 community controls and 21 patients with the autoimmune liver disease primary biliary cirrhosis (PBC) (matched case-wise for age and sex) attended for assessment of autonomic responses to orthostasis and Valsalva manoeuvre (VM). pSS patients also completed EULAR Sjögrens Syndrome patient-reported index (ESSPRI), EULAR Sjögren's syndrome disease activity index (ESSDAI), fatigue impact scale and EURO-QOL 5-dimension (EQ-5D).

RESULTS

Compared with controls, pSS patients had significantly lower baseline systolic blood pressure (SBP) (114 ± 13 vs. 127 ± 20; P = 0.02), which dropped to a significantly lower value (98 ± 22 vs. 119 ± 24, P = 0.009). When area under the curve (AUC) was calculated for when the SBP was below baseline this was significantly greater in pSS compared to both control groups (pSS vs. control vs. PBC: 153 ± 236 vs. 92 ± 85 vs. 1.2 ± 0.3, P = 0.005). Peak phase IV SBP during the VM was significantly lower in pSS (P = 0.007) indicating early sympathetic failure. Increased heart rate associated with fatigue (P = 0.02; r(2) = 0.2) and EQ-5D. A shift in sympathetic-vagal balance associated with overall symptom burden (ESSPRI) (P = 0.04, r(2) = 0.3) and EULAR sicca score (P = 0.016; r(2) = 0.3), the latter also correlated with baroreceptor effectiveness (P = 0.03; r(2) = 0.2) and diastolic blood pressure variability (P = 0.003; r(2) = 0.4).

CONCLUSION

pSS patients have impaired blood pressure response to standing. Dysautonomia correlates with PSS-associated symptoms and quality of life.

Transcriptome analysis of the interferon-signature defining the autoimmune process of Sjögren's syndrome

Sjögren's syndrome (SS) of humans and SS-like (SjS-like) diseases in mouse models are characterized by chronic immune attacks against the salivary and lacrimal glands leading to exocrine dysfunction. One characteristic of SS and SjS-like diseases repeatedly observed is a strong upregulated expression of both the type I (α/β) and type II (γ) interferons (IFNs). In addition, recent global transcriptome studies have identified a variety of IFN-stimulated gene (ISG) transcripts differentially expressed in tissues of SS patients and mouse models exhibiting SjS-like disease. Analyses of these transcriptome databases indicate that the sets of differentially expressed genes are highly restricted, suggesting that there is a unique specificity in ISGs activated (or suppressed) during development and onset of disease. As a result, these observations have led to both SS and SjS-like diseases being designated as 'interferon-signature' diseases. While SS and SjS-like diseases may be designated as such, very little effort has been made to determine what an interferon-signature might signify relative to autoinflammation and whether it might point directly to an underlying etiopathological mechanism. Here, we review these limited data and provide a model of how the products of these genes interact molecularly and biologically to define critical details of SS pathology.

[Is bioptic assurance reasonable in patients with Sjögren's syndrome? From focus score to diagnosing vasculitides]

Sjögren's syndrome is an autoimmune disease which targets the salivary and lacrimal glands in particular, causing sicca syndrome. Extraglandular manifestations are often seen. Chronic sialadenitis of the parotid gland is the most common symptom to be assessed for differential diagnosis. Common HE and Giemsa slices are histopathologically examined and graduated for lymphocyte infiltration (focus): grade 0: absent, grade 1: slight, grade 2: moderate non-focal infiltration, grade 3: 1 focus (> or =50 lymphocytes) per 4 mm2, grade 4: >1 focus. Grade 3 infiltrates correspond to a focus score of 1, which is one of four disease-classifying criteria acknowledged for diagnosis. Bioptic examination is also performed to rule out different (non-) immunologic sialadenitises, such as the necrotizing or epithelioid-like form (in sarcoidosis), and the extranodal marginal-zone lymphoma. Extraglandular manifestations of Sjögren's syndrome can also be safely diagnosed by histopathological examination. Emphases lie on vasculitides and myositides. Bioptic work-up, therefore, is not only reasonable but also an essential tool for diagnostics in Sjögren's syndrome.

Brain-derived neurotrophic factor and nerve growth factor correlate with T-cell activation in primary Sjogren's syndrome

OBJECTIVES

Identification of factors associated with disease activity and B and T cell activation is a challenge in primary Sjogren's syndrome (pSS). Neurotrophins (NTs), recently reported as B cell antiapoptotic, and T-cell activation factors seem to be implicated in autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).

METHODS

Samples from 18 pSS patients and 12 control subjects were studied to determine serum levels of nerve-growth factor (NGF) and brain-derived neurotrophic factor (BDNF), and their relationships with T- and B-cell activation and disease activity. Peripheral blood mononuclear cells (PBMCs) from patients with pSS and controls were examined by flow cytometry for HLA-DR expression by activated T cells. B cell activation was evaluated by B cell activating factor (BAFF) serum levels measured by enzyme-linked immunosorbent assay (ELISA) and immunoglobulin (Ig) and free light chain (FLC) levels.

RESULTS

Mean serum levels of BDNF in pSS patients were significantly higher than in healthy controls and correlated directly with disease activity. NGF levels were associated with the subgroup of patients with hypergammaglobulinaemia. The pSS group was characterized by peripheral CD4+ and CD8+ T cell activation that correlated positively with BDNF and NGF levels, respectively.

CONCLUSION

NT levels are potential biomarkers for lymphocyte activation in pSS patients.

The role of interleukin-10 promoter polymorphisms in primary Sjogren's syndrome

OBJECTIVE

To determine the impact of a broad spectrum of different polymorphisms within the interleukin-10 (IL-10) promoter gene on disease susceptibility to primary Sjogren's syndrome (pSS), clinical manifestations, and autoantibody production.

METHODS

We genotyped 111 unrelated German Caucasian patients with pSS and 145 healthy controls for the single nucleotide polymorphisms (SNPs) at positions -2849, -2776, -2769, -2763, -1349, -1082, -851, -819, -657, and -592 and for the microsatellites IL10.R and IL10.G. Allele and haplotype distributions were compared between patients and controls and between subgroups of patients with different clinical and laboratory findings.

RESULTS

We found no significant differences in the allele or haplotype frequencies between pSS patients and healthy controls. After Bonferroni correction we found a significant association of the ACC haplotype (at the -1082, -819, and -592 loci) with immunoglobulin (Ig)A antibodies to anti-alpha-fodrin.

CONCLUSION

Overall we found no associations of IL-10 promoter polymorphisms with the susceptibility to pSS in our cohort. The finding that the production of IgA anti-alpha-fodrin antibodies is associated with polymorphisms within the IL-10 promoter region suggests a genetic contribution to the generation of these antibodies.

Salivary gland tissue expression of interleukin-23 and interleukin-17 in Sjögren's syndrome: findings in humans and mice

OBJECTIVE

Recently, the Th1/Th2 paradigm has been expanded by the discovery of Th17 cells, a subset of CD4+ memory T cells characterized by their unique ability to secrete interleukin-17 (IL-17) family cytokines. Importantly, Th17 cells appear to be intimately involved in autoimmunity. We undertook the present study to investigate whether the Th17/IL-23 system is up-regulated in Sjögren's syndrome (SS).

METHODS

Sera, saliva, and salivary glands from C57BL/6.NOD-Aec1Aec2 mice (a model for primary SS), as well as sera, saliva, and salivary gland biopsy specimens obtained from patients with primary SS, were evaluated for IL-17 and IL-23 expression by immunohistochemistry, real-time polymerase chain reaction, and the Luminex system.

RESULTS

Immunohistochemical stainings of submandibular glands from C57BL/6.NOD-Aec1Aec2 mice and of salivary gland biopsy specimens from SS patients revealed strong positive staining for both IL-17 and IL-23 within lymphocytic foci and diffuse staining on epithelial tissues. Temporal expression of IL-17 and IL-23 in submandibular glands of C57BL/6.NOD-Aec1Aec2 mice correlated with expression of retinoic acid-related orphan receptor gammat, the Th17 cell master control gene. While IL-17 could not be detected in saliva from 4-20-week-old C57BL/6.NOD-Aec1Aec2 mice, this cytokine was present in the blood of mice up to age 16 weeks. This contrasted with sera and saliva from SS patients, in which IL-17 and IL-6 were present at varying levels.

CONCLUSION

These results suggest that the Th17/IL-23 system is up-regulated in C57BL/6.NOD-Aec1Aec2 mice and SS patients at the time of disease. A correlation between up-regulated IL-17/IL-23 expression and specific clinical manifestations of SS has yet to be identified.

Dysphagia and dysmotility of the pharynx and oesophagus in patients with primary Sjögren's syndrome

OBJECTIVES

To assess the prevalence of pharyngeal and oesophageal symptoms and dysmotility in patients with primary Sjögren's syndrome (pSS) and relate these to autonomic nervous function.

METHODS

Twenty consecutive pSS patients, according to the American-European Consensus Criteria (AECC), and 30 age- and sex-matched controls from the Swedish general population registry were studied. All subjects completed a pharyngeal and oesophageal symptoms questionnaire and were examined by pharyngeal and oesophageal video radiography. In addition, the pSS patients were examined by two different autonomic nervous function tests, the deep breathing test [calculating the expiration/inspiration (E/I) ratio] and the finger skin blood flow test [the vasoconstriction (VAC) index].

RESULTS

pSS patients experienced significantly more dysphagia compared with controls (65% vs. 3%; p<0.001). Pharyngeal (45% vs. 7%; p<0.01), oesophageal (80% vs. 7%; p<0.001) and gastro-oesophageal reflux symptoms (60% vs. 23%; p<0.01) were also more prevalent in pSS patients compared with controls while pharyngeal (15% vs. 17%; p = NS) and oesophageal dysmotility (40% vs. 30%; p = NS) were not. Dysphagia was not associated with dysmotility but was found to be associated with a decreased E/I ratio [-1.05 (-1.51 to -0.40) in patients with dysphagia vs. -0.21 (-0.39 to 0.65) in patients without dysphagia; p<0.01].

CONCLUSION

Subjective swallowing difficulties were more common in pSS patients than in controls while objective signs of pharyngeal and oesophageal dysmotility were not. Dysphagia in pSS patients does not seem to be related to video radiographical signs of dysmotility but may be related to an impaired parasympathetic function.

Clonality analysis of lymphoproliferative disorders in patients with Sjögren's syndrome

The aim of this study was to clarify the nature of the clonal lymphocyte infiltration in Sjögren's syndrome (SS) patients associated with lymphoproliferative disorders. We examined B cell clonality in lymphoproliferative tissues from six primary SS patients associated with lymphoproliferative disorders or lymphoma by cloning and sequencing of the gene rearrangement of the immunoglobulin heavy chain complementarity determining region 3 (IgVH-CDR3). Three patients with sequential observation showed progressional clonal expansion with the presence of the same subclone in different tissues during the course of disease. Among them, one patient developed mucosa-associated lymphoid tissue (MALT) lymphoma in glandular parotid. The other three SS patients concomitant with malignant B cells lymphomas showed different clonal expansion of B cells between nodal sites and salivary glands. The cloanality analysis indicated that monoclonal B cell population could spread from one glandular site to another site during the course of SS, suggesting that the malignant clone may arise from the general abnormal microenvironment, not restricted to the glandular tissue, in some SS patients.

Development of Sjogren's syndrome in nonobese diabetic-derived autoimmune-prone C57BL/6.NOD-Aec1Aec2 mice is dependent on complement component-3

The role of complement in the etiology of Sjögren's syndrome (SjS), a human autoimmune disease manifested primarily by salivary and lacrimal gland dysfunction resulting in dry mouth/dry eye syndrome, remains ill-defined. In the present study, we examined the role of complement component-3 (C3) using a newly constructed C3-gene knockout mouse, C57BL/6.NOD-Aec1Aec2.C3(-/-). Inactivation of C3 in the parental C57BL/6.NOD-Aec1Aec2 strain, a model of primary SjS, resulted in a diminished or total absence of both preclinical and clinical manifestations during development and onset of disease, including reduced acinar cell apoptosis, reduced levels of caspase-3, lack of leukocyte infiltration of submandibular glands, reduced synthesis of disease-associated autoantibodies, maintenance of normal glandular architecture, and retention of normal saliva secretion. In addition, C57BL/6-NOD.Aec1Aec2.C3(-/-) mice did not exhibit increased numbers of marginal zone B cells, a feature of SjS-prone C57BL/6-NOD.Aec1Aec2 mice. Interestingly, C57BL/6-NOD.Aec1Aec2.C3(-/-) mice retained some early pathological manifestations, including activation of serine kinases with proteolytic activity for parotid secretory protein. This improvement in the clinical manifestations of SjS-like disease in C57BL/6.NOD-Aec1Aec2.C3(-/-) mice, apparently a direct consequence of C3 deficiency, supports a much more important role for complement in the adaptive autoimmune response than previously recognized, possibly implicating an essential role for innate immunity.

Can low dose diagnostic dental radiation trigger Sjögren’s syndrome?

Sjögren's syndrome (SS), first described by Swedish ophthalmologist Henrik Sjögren in 1930, is a chronic inflammatory, autoimmune disorder characterized by diminished lacrimal and salivary glands secretion resulting in keratoconjunctivitis sicca and xerostomia. One factor instrumental in severe salivary gland damage and salivary flow decrement is radiation therapy. Apoptosis, implicated in autoimmune diseases, has been shown to be responsible for this damage. However, there are no studies investigating the effect of diagnostic radiation (low dose) on salivary glands. A safe level of radiation has not been established thus far. Diagnostic radiation has been used from 1896, but generally applied only from 1916. Dr. Sjögren identified SS in 1930. It is possible that the introduction of X-rays for diagnostic purposes is associated with SS onset. Available data show drastically reduced use of diagnostic dental radiation in developing countries and a concomitantly drastically reduced or lack of SS in these countries. In countries like India with a population of 1.1 billion (health care level II country), primary SS has been reported to be rare (total of 27 and 23 primary SS and secondary SS patients respectively reported thus far), while a health care level I country like USA, with a population of 300 million, there are about 2-4 million SS patients. Health care level IV countries do not have a single reported case of SS. There is also evidence for ultraviolet radiation inducing subcutaneous lupus erythematosus, an autoimmune disorder. We hypothesize that diagnostic dental radiation could be a factor for the development of SS as a result of either radiation induced apoptosis or through oxidative modification of proteins.