Sjogren's syndrome and the danger model

Current experimental methods to investigate the impact of specialized pro-resolving lipid mediators on Sjögren's syndrome

Sjögren's syndrome is a chronic inflammatory autoimmune disease characterized by diminished secretory function of the exocrine glands. Although extensive investigation has been done to understand Sjögren's syndrome, the causes of the disease are as yet unknown and treatments remain largely ineffective, with established therapeutic interventions being limited to use of saliva substitutes with modest effectiveness. A primary feature of Sjögren's syndrome is uncontrolled inflammation of exocrine tissues and previous studies have demonstrated that lipid-based specialized pro-resolving mediators reduce inflammation and restores tissue integrity in salivary glands. However, these studies are limited to a single specialized pro-resolving lipid mediator's family member resolvin D1 or RvD1 and its aspirin-triggered epimer, AT-RvD1. Consequently, additional studies are needed to explore the potential benefits of other members of the specialized pro-resolving lipid mediator's family and related molecules (e.g., additional resolvin subtypes as well as lipoxins, maresins and protectins). In support of this goal, the current review aims to briefly describe the range of current experimental methods to investigate the impact of specialized pro-resolving lipid mediators on Sjögren's syndrome, including both strengths and weaknesses of each approach where this information is known. With this article, the possibilities presented by specialized pro-resolving lipid mediators will be introduced to a wider audience in immunology and practical advice is given to researchers who may wish to take up this work.

Specialized pro-resolving receptors are expressed in salivary glands with Sjögren's syndrome

Our previous studies demonstrated that resolvin D1 (RvD1) and its aspirin-trigged (AT) form AT-RvD1, are effective in decreasing inflammation while restoring saliva flow rates in a Sjögren's syndrome (SS)-like mouse model before and after disease onset. Resolvins are specialized pro-resolving mediators (SPM) that actively regulate inflammation. However, we only have extensive data within the salivary glands for RvD1 and AT-RvD1, both of which bind to the receptor ALX/FPR2. As such, the presence of other SPM receptors is unknown within salivary glands. Therefore, the goal of this study was to determine the expression of SPM receptors in non-SS and SS patients. For this purpose, six human minor salivary glands from female subjects were analyzed by H&E using the Chisholm and Mason classification to determine the degree of lymphocytic infiltration. Next, confocal immunofluorescence analysis was performed to determine the presence and distribution of different SPM receptors in mucous acini and striated ducts. We observed diffuse presence of lymphocytic infiltration and clinical data were consistent with SS diagnosis in three patients. Moreover, confocal immunofluorescence analysis indicated the presence of the receptors ALX/FPR2, BLT1 and CMKLR1 in the mucous acini and striated ducts of both non-SS and SS patients. GPR32 was absent in SS and non-SS minor salivary glands. In summary, our results showed that various SPM receptors are expressed in non-SS and SS minor salivary glands, all of which may pose as potential targets for promoting pro-epithelial and anti-inflammatory/pro-resolution signaling on SS patients.

Making Sense of Intracellular Nucleic Acid Sensing in Type I Interferon Activation in Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a systemic autoimmune rheumatic disease characterized by dryness of the eyes and mucous membranes, which can be accompanied by various extraglandular autoimmune manifestations. The majority of patients exhibit persistent systemic activation of the type I interferon (IFN) system, a feature that is shared with other systemic autoimmune diseases. Type I IFNs are integral to anti-viral immunity and are produced in response to stimulation of pattern recognition receptors, among which nucleic acid (NA) receptors. Dysregulated detection of endogenous NAs has been widely implicated in the pathogenesis of systemic autoimmune diseases. Stimulation of endosomal Toll-like receptors by NA-containing immune complexes are considered to contribute to the systemic type I IFN activation. Accumulating evidence suggest additional roles for cytosolic NA-sensing pathways in the pathogenesis of systemic autoimmune rheumatic diseases. In this review, we will provide an overview of the functions and signaling of intracellular RNA- and DNA-sensing receptors and summarize the evidence for a potential role of these receptors in the pathogenesis of pSS and the sustained systemic type I IFN activation.

Possible Mechanisms of Lymphoma Development in Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a systemic as well as an organ-specific autoimmune disease characterized by lymphocytic infiltration of the glandular epithelial tissue. SS patients have been reported to be at highest risk of developing lymphoproliferative neoplasms, when compared with patients with other rheumatoid diseases. Factors such as cytokine stimulation, environmental factors, viral infection and genetic events as well as vitamin deficiency may contribute to the development of lymphoma. Over the past few decades, numerous efforts have been made to assess the relationship between lymphoma and SS. These include epidemiological surveys, molecular biologic assessments of clonality and well-linked register cohort studies evaluating the predictive value of clinical, laboratory and histological findings. Nevertheless, the mechanisms and factors predictive of lymphoma development in pSS patients remain to be defined. This review summarizes updated knowledge on the incidence of and risk factors for lymphoma development in pSS patients, as well as discussing the most recent findings on the development and treatment of lymphoma in pSS patients and the possible mechanism of lymphoma development.

Progress and regression within primary Sjögren's syndrome

The purpose of this review is to give a modern view and an update of important areas in primary Sjögren's syndrome (SS), which may be the most common of the autoimmune systemic rheumatic diseases. Interest in aspects of primary SS including clinical manifestations, pathogenesis, aetiology, treatment, prognosis, etc has increased during the past three decades, the volume of scientific papers and the number of theses being the indicators. However, only a fraction of the money that is used for research into rheumatoid arthritis (RA) is used for SS, and the statement that SS is under-diagnosed, under-treated and under-researched will still be valid for several years to come. The topics that are focused on in this review are: (a) clinical areas with subsections on signs and symptoms, terminology, predictors for development of non-Hodgkin malignant lymphoma (NHML) and prognosis, (b) treatment, (c) the Danger model (aetiopathogenesis) and (d) pathology, including immunoglobulin G4 (IgG4)-positive cells.

Immunopathogenesis of keratoconjunctivitis sicca in the dog

Keratoconjunctivitis sicca (KCS), more commonly known as dry eye, is an inflammatory condition of the ocular surface caused by a pathologic reduction in the aqueous component of the tear film. It is seen commonly in the dog and defined as a Schirmer tear test with a reading of less than 10 mm in one minute. While KCS may be caused by neurological disease or drug toxicity, most cases are immune-mediated. Whereas the immunological basis of autoimmune KCS has been extensively investigated in humans and experimental rodent models, little research has been undertaken in the dog. It is hoped that this review spurs further research into the etiopathogenic factors in canine KCS.

[Sjögren's syndrome. Current aspects from a rheumatological point of view]

Sjögren's syndrome is an autoimmune disease of the exocrine glands characterized by the leading symptoms of keratoconjunctivitis and stomatitis sicca based on a complex pathogenesis. The prevalence is about 0.5-1%; primary Sjögren's syndrome is differentiated from secondary Sjögren's syndrome associated with other autoimmune disorders. The diagnosis is established by the presence of subjective complaints and objective evidence of sicca symptoms, anti-Ro(SSA)/La(SSB) antibodies, and/or focal lymphocytic infiltration of the glandular tissue. In addition to the typical sicca symptomatology, which is managed symptomatically by substitution and stimulation therapy, some patients exhibit extraglandular manifestations. Complaints involving the musculoskeletal system and inner ear dominate and are treated by the rheumatologist. The indication for base therapy is tailored to individual needs, but the efficacy of this approach has not been established in studies. About 5-10% of the patients with primary Sjögren's syndrome develop a B-cell non-Hodgkin's lymphoma. The disease requires interdisciplinary management including, among others, ophthalmologists, dentists, and otorhinolaryngologists, depending on the clinical picture.

A New Approach to Managing Oral Manifestations of Sjogren's Syndrome and Skin Manifestations of Lupus

Sjogren's syndrome (SS) is an autoimmune disorder that affects the salivary glands, leading to xerostomia, and the lacrimal glands, resulting in xerophthalmia. Secondary SS is associated with other autoimmune disorders such as systemic rheumatic diseases and systemic lupus erythematosis (SLE), which can affect multiple organs, including the epidermis. Recent studies have demonstrated that green tea polyphenols (GTPs) possess both anti-inflammatory and anti-apoptotic properties in normal human cells. Epidemiological evidence has indicated that, in comparison to the United States, the incidence of SS, clinical xerostomia and lupus is considerably lower in China and Japan, the two leading green tea-consuming countries.Thus, GTPs might be responsible, in part, for geographical differences in the incidence of xerostomia by reducing the initiation or severity of SS and lupus. Consistent with this, molecular, cellular and animal studies indicate that GTPs could provide protective effects against autoimmune reactions in salivary glands and skin. Therefore, salivary tissues and epidermal keratinocytes could be primary targets for novel therapies using GTPs. This review article evaluates the currently available research data on GTPs, focusing on their potential application in the treatment of the oral manifestations of SS and skin manifestations of SLE.

Desiccating Stress Induces T Cell-Mediated Sjögren’s Syndrome-Like Lacrimal Keratoconjunctivitis

Chronic dry eye syndrome affects over 10 million people in the United States; it is associated with inflammation of the lacrimal gland (LG) and in some cases involves T cell infiltration of the conjunctiva. We demonstrate that environmental desiccating stress (DS) elicits T cell-mediated inflammation of the cornea, conjunctiva, and LG, but not other organs in mice. The lacrimal keratoconjunctivitis (LKC) was mediated by CD4(+) T cells, which, when adoptively transferred to T cell-deficient nude mice, produced inflammation in the LG, cornea, and conjunctiva, but not in any other organ. Adoptively transferred CD4(+) T cells produced LKC even though recipients were not exposed to DS. LKC was exacerbated in euthymic mice depleted of CD4(+)CD25(+)forkhead/winged helix transcription factor(+) regulatory T cells. The results suggest that DS exposes shared epitopes in the cornea, conjunctiva, and LG that induce pathogenic CD4(+) T cells that produce LKC, which under normal circumstances is restrained by CD4(+)CD25(+)forkhead/winged helix transcription factor(+) regulatory T cells.