Neuroendocrine manifestations in Sjögren's syndrome

Stress, mindfulness, and systemic lupus erythematosus: An overview and directions for future research

Although the pathogenesis of autoimmunity is not fully understood, it is thought to involve genetic, hormonal, immunologic, and environmental factors. Stress has been evaluated as a potential trigger for autoimmunity and disease flares in patients with systemic lupus erythematosus (SLE). The physiologic changes that occur with stress involve numerous catecholamines, hormones, and cytokines that communicate intricately with the immune system. There is some evidence that these systems may be dysregulated in patients with autoimmune disease. Mindfulness-based techniques are practices aimed at mitigating stress response and have been shown to improve quality of life in general population. This review will discuss pathophysiology of chronic stress as it relates to SLE, evidence behind mindfulness-based practices in these patients, and directions for future research.

Transcriptomic and Network Analysis of Minor Salivary Glands of Patients With Primary Sjögren's Syndrome

Primary Sjögren’s syndrome (pSS) is a systemic autoimmune disease characterized primarily by immune-mediated destruction of exocrine tissues, such as those of the salivary and lacrimal glands, resulting in the loss of saliva and tear production, respectively. This disease predominantly affects middle-aged women, often in an insidious manner with the accumulation of subtle changes in glandular function occurring over many years. Patients commonly suffer from pSS symptoms for years before receiving a diagnosis. Currently, there is no effective cure for pSS and treatment options and targeted therapy approaches are limited due to a lack of our overall understanding of the disease etiology and its underlying pathology. To better elucidate the underlying molecular nature of this disease, we have performed RNA-sequencing to generate a comprehensive global gene expression profile of minor salivary glands from an ethnically diverse cohort of patients with pSS. Gene expression analysis has identified a number of pathways and networks that are relevant in pSS pathogenesis. Moreover, our detailed integrative analysis has revealed a primary Sjögren’s syndrome molecular signature that may represent important players acting as potential drivers of this disease. Finally, we have established that the global transcriptomic changes in pSS are likely to be attributed not only to various immune cell types within the salivary gland but also epithelial cells which are likely playing a contributing role. Overall, our comprehensive studies provide a database-enriched framework and resource for the identification and examination of key pathways, mediators, and new biomarkers important in the pathogenesis of this disease with the long-term goals of facilitating earlier diagnosis of pSS and to mitigate or abrogate the progression of this debilitating disease.

How stress contributes to autoimmunity-lessons from Sjögren's syndrome

A large body of clinical evidence on the association between stressful life events and autoimmune diseases suggests that stress may play an important role in the pathogenesis of these disorders. In this article, we discuss the effects of stress, not on the immune system but on specific cell populations against which the autoimmune reactivity is directed. Using Sjögren's syndrome as a model autoimmune disease, we review the role of stress in the initiation and perpetuation of autoimmune reactivity. We present data that reveal the effects of stress on salivary gland epithelial cells, suggesting that stress can become immunogenic through its various effects on salivary gland epithelium.

The relationship between the presence of autoantibodies, indicators of local and systemic inflammation, the serum concentration of B-cell activating factor (BAFF) and the intensity of salivary gland infiltration in patients with primary Sjögren's syndrome - a preliminary study

OBJECTIVES

The aim of this study was to find markers related to activation of B cells, which show a correlation with the systemic inflammation markers - erythrocyte sedimentation rate and C-reactive protein and with the intensity of in situ inflammation.

MATERIAL AND METHODS

Forty-one primary Sjögren's syndrome (pSS) patients (33 female, 8 male) of the mean age 52.9 ±15 years were included. A group of 20 healthy volunteers was applied as a control. Erythrocyte sedimentation rate (ESR), concentration of gamma-globulins, C-reactive protein (CRP) and rheumatoid factor (RF) were measured by routine laboratory tests. Titres of antinuclear antibodies (ANAs) were determined by the indirect immunofluorescence method, while anti-SS-A/SS-B antibodies were detected by both the dot-blot method and an enzyme immunoassay. The concentrations of BAFF in sera were measured by sandwich ELISA. Biopsies of minor salivary glands were taken and the focus score (FS) was calculated. Correlations between quantitative variables were assessed using the Spearman correlation coefficient (r).

RESULTS

Serum concentrations of BAFF was significantly higher in the pSS patients than in the control group. The study revealed a statistically significant correlation between ANAs titre and the FS (r = 0.421). Anti-SS-A/Ro and anti-SS-B/La antibodies positively correlated with ESR. There was also a positive correlation between the gamma globulin level and the titres of all tested autoantibodies.

CONCLUSIONS

The positive correlation between ANAs and FS confirms the importance of these autoantibodies in the local inflammatory process. The positive correlation between anti-SS-A/SS-B antibodies and ESR suggests involvement of these antibodies in generalization of the inflammatory response. In the pSS group serum concentrations of BAFF were statistically significantly higher than healthy volunteers. All presented results confirm the role of activity of B cells in the course of pSS.

Sjögren's syndrome: still not fully understood disease

Primary Sjögren's syndrome is an autoimmune disorder with external exocrine glands dysfunction and multiorgan involvement. The pathogenesis of primary Sjogren’s syndrome is still unclear; however, our knowledge of the involvement of different cells (e.g., B and T cells, macrophages and dendritic cells) and pathways (BAFF/APRIL and interferons) leading to the development of autoimmunity is continually expanding. For clinicians, the most frequent symptoms are dryness of eyes and mouth, but often the patients have musculoskeletal symptoms and systemic manifestations. However, the increased risk of lymphoproliferative disorders in this group of patients, most commonly B-cell marginal zone lymphoma, is particularly important. Recent separation of IgG4-related diseases and attempts to create further diagnostic criteria for pSS testify to the difficulties, and at the same time a large interest, in understanding the disease so as to allow the effective treatment. This article draws attention to the problems faced by the clinician wishing to securely identify pSS by using accurate laboratory biomarkers and useful imaging tools and predict the development of complications associated with this, still not fully understood, autoimmune disease.

Role of vacuolar ATPase and Skp1 in Sjögren's syndrome

Immune mechanisms alone cannot directly account for exocrine gland dysfunction and extraglandular features such as renal tubular acidosis, neuropathy, hearing loss and fatigue in Sjögren's syndrome (SS). Absence of Vacuolar ATPase (V-ATPase) has been reported in SS related renal tubular acidosis (RTA). We hypothesise how defect in V-ATPase could account for decreased neurotransmitter release leading onto exocrine dysfunction, neuroendocrine manifestations and hearing loss which are well described manifestations in SS. S-phase-kinase-associated protein-1 (Skp1) is a constituent of RAVE which is involved in V-ATPase assembly. It is also a component of SCF ligase which is crucial in NFκB signalling. SKP1 also interacts with TRIM 21/Ro 52 which is an autoantigen in SS. By virtue of these interactions, we postulate how a defective skp1 could fit into the existing pathogenesis of SS and also account for increased risk of lymphoma in SS as well as congenital heart block in fetus of mothers with SS.

Early menopause and severity of rheumatoid arthritis in women older than 45 years

Introduction

We aimed to investigate whether recognized hormonal predictors of rheumatoid arthritis (RA) also influence the severity of RA.

Methods

One hundred thirty-four incident RA cases identified by four different local and national registers, who had participated in a community-based health survey between 1991 and 1996, were included. By a retrospective structured review of the medical records, information on the use of disease-modifying antirheumatic drugs (DMARDs), erosions on radiographs, rheumatoid factor (RF) status, and disability measured by using the health assessment questionnaire (HAQ) were collected. The variables were added to the SPSS TwoStep Cluster Analysis to reveal natural groupings of RA severity. Known hormonal predictors analyzed were breastfeeding history, history of oral contraceptive (OC) use, and menopausal age.

Results

The mean age at RA diagnosis was 63.4 years; 72% were RF positive, and 28% had received biological treatment. Three clusters were identified, one with severe RA, one with mild/moderate RF-positive RA, and one with mild/moderate RF-negative RA. A significant difference (P = 0.005) was found in the distribution of clusters between patients with a history of early menopause compared with those with menopause after 45 years, with a higher proportion with mild/moderate RF-negative RA in the early-menopause subset. No major difference in severity of the disease was noted depending on OC use or history of breastfeeding.

Conclusions

Early menopause was associated with a milder form of RA. Hormonal changes may influence pathways that are distinct from those leading to severe, progressive disease.

Endocrine alterations in primary Sjogren's syndrome: an overview

Involvement of several components of the endocrine system has been proposed as significant player in primary Sjogren's syndrome (SS) pathogenesis and clinical expression. Hypoactivity of the hypothalamic-pituitary-adrenal (HPA) axis has been previously demonstrated in patients with primary SS as a result either of a pituitary defect and/or of adrenal gland dysfunction. In support of the latter hypothesis, antibodies to 21-hydroxylase (OH)--a marker of autoimmune adrenal disease--have been detected in sera from approximately one fifth of primary SS patients, in association with B-cell activating cytokines and adrenal hyporesponsiveness. As a result of HPA hypofunction, adrenal androgens and particularly dehydroepiandrosterone-sulfate (DHEA-S) have been reportedly low in primary SS individuals. Epithelial salivary gland cells undergo apoptosis in lack of both estrogens and active androgens. In the absence of a compensatory action of the latter, menopausal status can lead to salivary gland apoptotic process triggering an aberrant immune response. On the other hand, given that salivary gland tissue remodeling has been shown to be under androgenic control, the observed androgen deficiency in these patients might account for the observed alterations in the salivary gland architecture. Heightened serum and salivary gland tissue prolactin levels in primary SS patients have been also suggested as contributors in disease pathogenesis. Finally, autoimmune thyroid disease (ATD) occurs quiet commonly in the setting of primary SS and subclinical hypothyroidism is the main functional abnormality observed in these patients.

Combination treatment with progesterone and vitamin D hormone may be more effective than monotherapy for nervous system injury and disease

More than two decades of pre-clinical research and two recent clinical trials have shown that progesterone (PROG) and its metabolites exert beneficial effects after traumatic brain injury (TBI) through a number of metabolic and physiological pathways that can reduce damage in many different tissues and organ systems. Emerging data on 1,25-dihydroxyvitamin D(3) (VDH), itself a steroid hormone, have begun to provide evidence that, like PROG, it too is neuroprotective, although some of its actions may involve different pathways. Both agents have high safety profiles, act on many different injury and pathological mechanisms, and are clinically relevant, easy to administer, and inexpensive. Furthermore, vitamin D deficiency is prevalent in a large segment of the population, especially the elderly and institutionalized, and can significantly affect recovery after CNS injury. The combination of PROG and VDH in pre-clinical and clinical studies is a novel and compelling approach to TBI treatment.

Autoimmune thyroid diseases in a large group of Hungarian patients with primary Sjögren's syndrome

BACKGROUND

Previous studies on relatively small populations of patients with primary Sjögren's syndrome (pSS) suggested an association between pSS and Hashimoto's thyroiditis (HT). As some findings in the literature regarding the relationship between pSS and thyroid disease are contradictory, and there is little information on the sequence of pSS and HT, we conducted a study with a population of patients with pSS that was about three times larger than previously studied populations. Our objective was to determine the prevalence of HT and Graves' disease (GD) in patients with pSS and to assess the sequence of pSS and autoimmune thyroid diseases.

METHODS

A total of 479 patients with pSS were retrospectively studied. Thyroid ultrasound and scintigraphy were performed, and serum thyrotropin, free triiodothyronine, free thyroxine, antithyroid peroxidase antibody (TPOAb), and anti-thyroglobulin autoantibody (TgAb) measurements were carried out. Solitary thyroid nodules were investigated by fine-needle aspiration biopsy.

RESULTS

Thyroid dysfunction was found in 95 patients (21.25%). Thirty of these patients had HT and 18 had GD. HT predated pSS in eight patients, developed at approximately the same time in seven patients, and followed pSS in 15 patients. Almost all (90%) patients with HT had persistently elevated serum TgAb or TPOAb titers.

CONCLUSIONS

An association between HT and pSS was found based on the fact that the frequency of HT was greater among pSS patients (6.26%) than in the general population (1-2%). In contrast, no association between GD and pSS was found. We noted that both HT and GD can appear either before or after the onset of pSS. Since most cases of pSS predate the appearance of autoimmune thyroid diseases it is important to determine if pSS is a predisposing factor for the development of autoimmune thyroiditis.

Corticotropin releasing hormone and the immune/inflammatory response

Hypothalamic corticotropin-releasing hormone (CRH) acts as the major physiologic ACTH secretagog. Moreover, CRH is distributed in the brain and spinal cord, adrenal medulla, testes, ovaries, gastrointestinal tract, pancreas, myometrium, endometrium, placenta, and diverse inflammatory sites. Immunoreactive CRH has been found in the cytoplasm of immune accessory cells (macrophages, endothelial cells, and tissue fibroblasts), and in inflammatory sites of both acute and chronic inflammation (synovial lining cell layers and blood vessels from the joints of patients with rheumatoid arthritis and osteoarthritis). Additionally, the local presence of CRH in the uveitic eyes, cytoplasm of inflammatory cells (macrophages, lymphocytes, and polymorphonuclear cells) infiltrating the iris, ciliary body, vitreous, retina, and choroid appears to be of pivotal importance in the process of experimental autoimmune uveoretinitis. Traditionally, hypothalamic CRH has been considered to act indirectly in an anti-inflammatory fashion, since the end product of the hypothalamic–pituitary–adrenal axis is cortisol, a well-known anti-inflammatory compound. However, CRH produced at peripheral inflammatory sites has been shown to participate in an autocrine/paracrine stimulation of inflammation. Thus, CRH may have a peripheral, primarily activating role on the immune system. The mechanisms of the CRH-mediated component of the immune/inflammatory response are still unclear. CRH in inflammatory sites seems to be involved in the activation of the Fas/Fas ligand system. Furthermore, locally produced embryonic and endometrial CRH plays a role in both the aseptic inflammatory process of implantation and the anti-rejection process that protects the fetus from the maternal immune system. There are two types of G-protein-coupled CRH receptors (CRH-R1 and CRH-R2). Pyrrolopyrimidine compounds, such as antalarmin, have been developed as CRH-R1 receptor antagonists. Confirming the peripheral pro-inflammatory actions of CRH, antalarmin has been shown to suppress experimental aseptic inflammation. Thus, antalarmin may represent the first in a new class of anti-inflammatory agents operating through CRH-R1. Studies of CRH genetics have provided new insights on the pathogenesis of rheumatoid arthritis in humans. DNA variation across the CRH gene-containing region has been examined in families with multiple cases of rheumatoid arthritis. Transmission Disequilibrium Test analysis showed significant association at the CRH locus.

Sjögren's syndrome in the NOD mouse model is an interleukin-4 time-dependent, antibody isotype-specific autoimmune disease

NOD.B10-H2b and NOD/LtJ mice manifest many features of primary and secondary Sjögren's syndrome (SjS), respectively, an autoimmune disease affecting primarily the salivary and lacrimal glands leading to xerostomia (dry mouth) and xerophthalmia (dry eyes). A previous study suggested that the T(H2) cytokine, interleukin (IL)-4, plays an integral role in the development and onset of SjS-like disease in the NOD mouse model. To define further the role of IL-4 in onset of murine SjS-like disease, we have examined two IL4 gene knockout (KO) mouse strains, NOD.IL4-/- and NOD.B10-H2b.IL4-/-. Unlike NOD.IL4-/- mice, NOD.B10-H2b.IL4-/- mice are resistant to development of diabetes. The presence of a dysfunctional IL4 gene did not impede leukocyte infiltration of the salivary glands, yet prevented development of secretory dysfunction. Whereas NOD.B10-H2b.IL4-/- mice exhibited many pathophysiological manifestations of SjS-like disease common to the parental strains, these mice failed to produce anti-muscarinic acetylcholine type-3 receptor (M3R) autoantibodies of the IgG1 isotype. Cytokine mRNA expression profiles and adoptive transfers of T lymphocytes from NOD.B10-H2b.Gfp mice into NOD.B10-H2b.IL4-/- mice at different ages suggest IL-4 is required during the pre-clinical disease stage (around 12 weeks of age) to initiate clinical xerostomia. The results of this study indicate that the failure of NOD.IL4-/- and NOD.B10-H2b.IL4-/- mice to synthesize anti-M3R autoantibodies of the IgG1 isotype apparently explains why these mice fail to develop exocrine gland dysfunction, despite exhibiting pre-clinical manifestations of SjS-like disease.

Role of complement and B lymphocytes in Sjögren's syndrome-like autoimmune exocrinopathy of NOD.B10-H2b mice

Sjögren's syndrome (SjS) is a human autoimmune disease characterized by the loss of exocrine function as a result of a chronic immune attack directed primarily against the salivary and lacrimal glands leading to xerostomia (dry mouth) and xerophthalmia (dry eyes). NOD.B10-H2b mice manifest many features of SjS, exhibiting exocrine gland dysfunction concomitant with leukocyte infiltration of the salivary and lacrimal glands. Recent studies have shown that both SjS patients and NOD.B10-H2b mice exhibit increased B lymphocyte survival, B cell hyper-reactivity and hyper-gammaglobulinemia with high production of autoantibodies. To study the possible influence of complement on the development and expression of SjS-like disease of the NOD.B10-H2b, we have utilized a prophylactic treatment with CVF known to interfere with the action of complement C3 factor. NOD.B10-H2b mice, injected with CVF starting at 10 weeks of age, a time when leukocyte infiltration is expected to begin, failed to develop salivary dysfunction out to 24 weeks of age, a time when reduced salivary flow rates are known to occur in non-treated animals. Concomitant with retention of salivary exocrine function, CVF-treated mice showed reduced levels of leukocytic infiltration, reduction of anti-nuclear autoantibodies and major alterations in the B lymphocyte profiles while maintaining general pathophysiological measures of disease. These data suggest that C3 plays a significant role in development and onset of SjS-like disease, yet additional studies need to be carried out to identify the precise mode of action.

The hypothalamic-pituitary-adrenal axis in the pathogenesis of rheumatic diseases

Many studies have demonstrated altered HPA axis activity in patients with rheumatic diseases. In the case of autoimmune inflammatory diseases, circumstantial evidence suggests that failure of the neuroendocrine-immune regulatory loop may lead to insufficient production of endogenous glucocorticoid. Nevertheless, in human autoimmune disease, it is not possible to determine if altered HPA axis activity predates the onset of chronic inflammation. Animal studies and some early genetic studies in RA patients lend credibility to the argument that insufficient HPA axis response to inflammatory stimuli may increase susceptibility to, or severity of, these diseases. Most patients with rheumatic diseases complain of musculoskeletal pain. There is evidence of HPA axis involvement in acute and chronic pain. In the case of FM, pain cannot be explained on the basis of inflammation or altered musculoskeletal anatomy. This has led to the hypothesis that central nervous system mechanisms contribute to the symptom of somatic pain. Again, it is unclear if the observed HPA axis abnormalities reflect pre-existing vulnerability to the FM spectrum of disease, or whether chronic somatic symptoms alter HPA axis activity. Availability of technology to study better central components of the HPA axis may shed further light on its role in the pathogenesis of inflammatory autoimmune rheumatic diseases and musculoskeletal pain syndromes.

Use of muscarinic agonists in the treatment of Sjögren's syndrome

Two muscarinic agonists (pilocarpine and cevimeline) have recently been approved for the treatment of symptoms of xerostomia in Sjögren's syndrome (SS). These agents stimulate the M1 and M3 receptors present on salivary glands, leading to increased secretory function. The use of these agents emphasizes the importance of neuroendocrine mechanisms in SS, which is considered an autoimmune disorder. We review recent studies on the release of cytokines and metalloproteinases in SS-affected glands and their influence on the release of and response to neurotransmitters. Also, we review the structure and function of muscarinic receptors as they may relate to SS and the potential use of novel muscarinic agonists in SS.

Neuroendocrine immune mechanisms in rheumatic diseases. An overview and future implications

A new physiopathogenetic paradigm may be proposed for RA and possibly its related systemic rheumatic diseases (i.e., mechanisms whereby multiple risk factors initially perturb the homeostasis of core physiologic components over an extended premorbid phase, which may progress to clinical disease in later decompensated stages). These complex interactive processes are likely to be individualized according to genetic, nongenomic somatic, developmental, behavioral, and environmental influences. Future research promises to further elucidate the roles of neuroendocrine mechanisms in the rheumatic diseases and offers promise for enhanced therapies and possible avenues for disease modification if not eventual prevention.