Increased expression of interleukin-7 in labial salivary glands of patients with primary Sjögren's syndrome correlates with increased inflammation

m6A RNA methylation controls salivary gland epithelial cell function and has a protective role in Sjögren's disease

OBJECTIVES

The RNA epitranscriptomic modification known as N6-methyladenosine (m6A) represents a novel mechanism of gene regulation that is poorly understood in human autoimmune diseases. Our research explores the role of this RNA m6A modification in salivary gland epithelial cells (SGEC) and its impact on the pathogenesis of Sjögren's disease (SjD).

METHODS

SGECs from SjD patients and controls were analysed for m6A writers METTL3 and METTL14 expression using RNA-seq, quantitative PCR and immunohistochemistry. Functional assays assessed the impact of METTL3 knockdown or pharmacological inhibition on proinflammatory gene expression and immune cell interactions (using transwell and coculture systems). Mechanistic studies examined METTL3-mediated m6A modifications in double-stranded RNA (dsRNA) formation through immunofluorescence. Unsupervised clustering identified patterns of interferon activation in salivary glands and their correlation with m6A writers.

RESULTS

METTL3 and METTL14 were elevated in SGEC from SjD patients in comparison to controls. Paradoxically, inhibiting METTL3 increased proinflammatory gene expression, enhancing SGEC's ability to attract immune cells and activate B cells. Conversely, inhibiting the eraser FTO had the opposite effect. METTL3-mediated m6A modifications prevented dsRNA formation and IFN signalling activation. SGEC from SjD showed insufficient METTL3 upregulation compared with controls in response to inflammatory triggers, indicating a limited capacity to regulate the inflammatory response. SjD patients with elevated disease activity and higher interferon signature exhibit reduced METTL3 expression.

CONCLUSIONS

Impairment of m6A modifications in SGEC in response to inflammatory triggers favour the formation of dsRNA, potentially amplifying the interferon loop and contributing to SjD pathogenesis.

Identification and verification of inflammatory biomarkers for primary Sjögren's syndrome

INTRODUCTION

Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by inflammatory infiltration, and dysfunction of the salivary and lacrimal glands. This research aimed to explore the disease pathogenesis and improve the diagnosis and treatment of pSS by mining inflammation-associated biomarkers.

METHODS

Five pSS-related datasets were retrieved from the Gene Expression Omnibus (GEO) database. Inflammation-associated biomarkers were determined by the least absolute shrinkage and selection operator (LASSO) and support vector machines recursive feature elimination (SVM-RFE). Single sample gene set enrichment analysis (ssGSEA) was implemented to profile the infiltration levels of immune cells. Real-time quantitative PCR (RT-qPCR) verified the expression of biomarkers in clinical samples.

RESULTS

Four genes (LY6E, EIF2AK2, IL15, and CXCL10) were screened as inflammation-associated biomarkers in pSS, the predictive performance of which were determined among three pSS-related datasets (AUC > 0.7). Functional enrichment results suggested that the biomarkers were involved in immune and inflammation-related pathways. Immune infiltration analysis revealed that biomarkers were notably connected with type 2 T helper cells, regulatory T cells which were significantly expressed between pSS and control. TESTOSTERONE and CYCLOSPORINE were predicted to take effect by targeting CXCL10 and IL15 in pSS, respectively.

CONCLUSION

Four inflammation-associated biomarkers (LY6E, EIF2AK2, IL15, and CXCL10) were explored, and the underlying regulatory mechanisms and targeted drugs associated with these biomarkers were preliminarily investigated according to a series of bioinformatics methods based on the online datasets of pSS, which provided a reference for understanding the pathogenesis of pSS. Key Points • Inflammation-associated biomarkers (LY6E, EIF2AK2, IL15, and CXCL10) were firstly identified in Sjögren's syndrome based on LASSO and SVM-RFE analyses. • CXCL10, EIF2AK2 and LY6E were prominently positively correlated with immature B cells, while IL15 were significantly negatively correlated with memory B cells in Sjögren's syndrome. • LY6E, EIF2AK2, IL15, and CXCL10 were significantly more highly expressed in clinical Sjögren's syndrome samples compared to healthy control samples, which was consistent with the analysis results of the GEO database. •LY6E, EIF2AK2, IL15, and CXCL10 might be used as the biomarkers for the treatment and diagnosis of Sjögren's syndrome.

Salivary inflammatory burden in pre- and postmenopausal women: Associations with body mass index, patient-reported health, serum cytokines, and periodontal parameters

BACKGROUND

The decline of estrogen levels during menopause impacts weight, mood, and overall health, both orally and systemically. This study assessed salivary levels of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), IL-10, and IL-7 in postmenopausal (PMW) and regularly menstruating premenopausal (RMPW) women, while considering serum cytokine levels, body mass index (BMI), periodontal health, and self-reported physical and emotional well-being.

METHODS

In this study, 75 PMW and 71 RMPW were included. Clinical and periodontal parameters were evaluated, and perceived health was assessed with the Women's Health Questionnaire (WHQ). Cytokine levels in both saliva and serum were quantified by enzyme-linked immunosorbent assay (ELISA). Covariate evaluations of salivary cytokines were conducted using hierarchical linear regression modeling.

RESULTS

Cytokines were detectable in saliva from 71 PMW and 67 RMPW. In the initial unadjusted model, IL-7, IL-10, and TNF-α exibited significant differences between RMPW and PMW. However, these differences became non-significant (p > 0.05) in the final model after adjusting for age, which implies a negligible effect of the investigated covariates on salivary cytokine levels when age was considered. Lower levels of IL-6 in PMW, which initially showed no significant difference, became borderline (p = 0.054) in the final model after adjusting for age.

CONCLUSIONS

After adjusting for multiple factors, no significant difference was found in the salivary levels of the investigated cytokines between RMPW and PMW. Factors such as BMI, perceived health, serum cytokine levels, and periodontal parameters seem to minimally influence these levels in PMW. However, age may be a stronger confounding factor.

High-content multimodal analysis supports the IL-7/IL-7 receptor axis as a relevant therapeutic target in primary Sjögren's syndrome

OBJECTIVE

While the involvement of IL-7/IL-7R axis in pSS has been described in relation to T cells, little is known about the contribution of this pathway in relationship with other immune cells, and its implication in autoimmunity. Using high-content multiomics data, we aimed at characterizing IL-7R expressing cells and the involvement of IL-7/IL-7R pathway in pSS pathophysiology.

METHODS

An IL-7 signature established using RNA-sequencing of human PBMCs incubated with IL-7 was applied to 304 pSS patients, and on RNA-Seq datasets from tissue biopsies. High-content immunophenotyping using flow and imaging mass cytometry was developed to characterize peripheral and in situ IL-7R expression.

RESULTS

We identified a blood 4-gene IL-7 module (IKZF4, KIAA0040, PGAP1 and SOS1) associated with anti-SSA/Ro positiveness in patients as well as disease activity, and a tissue 5-gene IL-7 module (IL7R, PCED1B, TNFSF8, ADAM19, MYBL1) associated with infiltration severity. We confirmed expression of IL-7R on T cells subsets, and further observed upregulation of IL-7R on double-negative (DN) B cells, and especially DN2 B cells. IL-7R expression was increased in pSS compared to sicca patients with variations seen according to the degree of infiltration. When expressed, IL-7R was mainly found on epithelial cells, CD4+ and CD8+ T cells, switched memory B cells, DN B cells and M1 macrophages.

CONCLUSION

This exhaustive characterization of the IL-7/IL-7R pathway in pSS pathophysiology established that two IL-7 gene modules discriminate pSS patients with a high IL-7 axis involvement. Their use could guide the implementation of an anti-IL-7R targeted therapy in a precision medicine approach.

Mitochondrial double-stranded RNAs as a pivotal mediator in the pathogenesis of Sjӧgren's syndrome

Sjӧgren's syndrome (SS) is a systemic autoimmune disease that targets the exocrine glands, resulting in impaired saliva and tear secretion. To date, type I interferons (I-IFNs) are increasingly recognized as pivotal mediators in SS, but their endogenous drivers have not been elucidated. Here, we investigate the role of mitochondrial double-stranded RNAs (mt-dsRNAs) in regulating I-IFNs and other glandular phenotypes of SS. We find that mt-dsRNAs are elevated in the saliva and tears of SS patients (n = 73 for saliva and n = 16 for tears) and in salivary glands of non-obese diabetic mice with salivary dysfunction. Using the in-house-developed 3D culture of immortalized human salivary gland cells, we show that stimulation by exogenous dsRNAs increase mt-dsRNAs, activate the innate immune system, trigger I-IFNs, and promote glandular phenotypes. These responses are mediated via the Janus kinase 1 (JAK1)/signal transducer and activator of transcription (STAT) pathway. Indeed, a small chemical inhibitor of JAK1 attenuates mtRNA elevation and immune activation. We further show that muscarinic receptor ligand acetylcholine ameliorates autoimmune characteristics by preventing mt-dsRNA-mediated immune activation. Last, direct suppression of mt-dsRNAs reverses the glandular phenotypes of SS. Altogether, our study underscores the significance of mt-dsRNA upregulation in the pathogenesis of SS and suggests mt-dsRNAs as propagators of a pseudo-viral signal in the SS target tissue.

In patients with primary Sjögren's syndrome innate-like MAIT cells display upregulated IL-7R, IFN-γ, and IL-21 expression and have increased proportions of CCR9 and CXCR5-expressing cells

Introduction

Mucosal-associated invariant T (MAIT) cells might play a role in B cell hyperactivity and local inflammation in primary Sjögren's syndrome (pSS), just like previously studied mucosa-associated CCR9+ and CXCR5+ T helper cells. Here, we investigated expression of CCR9, CXCR5, IL-18R and IL-7R on MAIT cells in pSS, and assessed the capacity of DMARDs to inhibit the activity of MAIT cells.

Methods

Circulating CD161+ and IL-18Rα+ TCRVα7.2+ MAIT cells from pSS patients and healthy controls (HC) were assessed using flow cytometry, and expression of CCR9, CXCR5, and IL-7R on MAIT cells was studied. Production of IFN-γ and IL-21 by MAIT cells was measured upon IL-7 stimulation in the presence of leflunomide (LEF) and hydroxychloroquine (HCQ).

Results

The numbers of CD161+ and IL-18Rα+ MAIT cells were decreased in pSS patients compared to HC. Relative increased percentages of CD4 MAIT cells in pSS patients caused significantly higher CD4/CD8 ratios in MAIT cells. The numbers of CCR9 and CXCR5-expressing MAIT cells were significantly higher in pSS patients. IL-7R expression was higher in CD8 MAIT cells as compared to all CD8 T cells, and changes in IL-7R expression correlated to several clinical parameters. The elevated production of IL-21 by MAIT cells was significantly inhibited by LEF/HCQ treatment.

Conclusion

Circulating CD161+ and IL-18Rα+ MAIT cell numbers are decreased in pSS patients. Given their enriched CCR9/CXCR5 expression this may facilitate migration to inflamed salivary glands known to overexpress CCL25/CXCL13. Given the pivotal role of IL-7 and IL-21 in inflammation in pSS this indicates a potential role for MAIT cells in driving pSS immunopathology.

JAK/STAT Pathway Targeting in Primary Sjögren Syndrome

Primary Sjögren's syndrome (pSS) is an autoimmune systemic disease mainly affecting exocrine glands and resulting in disabling symptoms, as dry eye and dry mouth. Mechanisms underlying pSS pathogenesis are intricate, involving multiplanar and, at the same time, interlinked levels, e.g., genetic predisposition, epigenetic modifications and the dysregulation of both immune system and glandular-resident cellular pathways, mainly salivary gland epithelial cells. Unravelling the biological and molecular complexity of pSS is still a great challenge but much progress has been made in recent years in basic and translational research field, allowing the identification of potential novel targets for therapy development. Despite such promising novelties, however, none therapy has been specifically approved for pSS treatment until now. In recent years, growing evidence has supported the modulation of Janus kinases (JAK) - signal transducers and activators of transcription (STAT) pathways as treatment strategy immune mediated diseases. JAK-STAT pathway plays a crucial role in autoimmunity and systemic inflammation, being involved in signal pathways of many cytokines. This review aims to report the state-of-the-art about the role of JAK-STAT pathway in pSS, with particular focus on available research and clinical data regarding the use of JAK inhibitors in pSS.

Composition and regulation of the immune microenvironment of salivary gland in Sjögren’s syndrome

Primary Sjögren’s syndrome (pSS) is a systemic autoimmune disease characterized by exocrine gland dysfunction and inflammation. Patients often have dry mouth and dry eye symptoms, which seriously affect their lives. Improving dry mouth and eye symptoms has become a common demand from patients. For this reason, researchers have conducted many studies on external secretory glands. In this paper, we summarize recent studies on the salivary glands of pSS patients from the perspective of the immune microenvironment. These studies showed that hypoxia, senescence, and chronic inflammation are the essential characteristics of the salivary gland immune microenvironment. In the SG of pSS, genes related to lymphocyte chemotaxis, antigen presentation, and lymphocyte activation are upregulated. Interferon (IFN)-related genes, DNA methylation, sRNA downregulation, and mitochondrial-related differentially expressed genes are also involved in forming the immune microenvironment of pSS, while multiple signaling pathways are involved in regulation. We further elucidated the regulation of the salivary gland immune microenvironment in pSS and relevant, targeted treatments.

TRP Channels as Molecular Targets to Relieve Endocrine-Related Diseases

Transient receptor potential (TRP) channels are polymodal channels capable of sensing environmental stimuli, which are widely expressed on the plasma membrane of cells and play an essential role in the physiological or pathological processes of cells as sensors. TRPs often form functional homo- or heterotetramers that act as cation channels to flow Na⁺ and Ca²⁺, change membrane potential and [Ca²⁺]_i (cytosolic [Ca²⁺]), and change protein expression levels, channel attributes, and regulatory factors. Under normal circumstances, various TRP channels respond to intracellular and extracellular stimuli such as temperature, pH, osmotic pressure, chemicals, cytokines, and cell damage and depletion of Ca²⁺ reserves. As cation transport channels and physical and chemical stimulation receptors, TRPs play an important role in regulating secretion, interfering with cell proliferation, and affecting neural activity in these glands and their adenocarcinoma cells. Many studies have proved that TRPs are widely distributed in the pancreas, adrenal gland, and other glands. This article reviews the specific regulatory mechanisms of various TRP channels in some common glands (pancreas, salivary gland, lacrimal gland, adrenal gland, mammary gland, gallbladder, and sweat gland).

Proteomic analysis in primary T cells reveals IL-7 alters T cell receptor thresholding via CYTIP/cytohesin/LFA-1 localisation and activation

The ability of the cellular immune system to discriminate self from foreign antigens depends on the appropriate calibration of the T cell receptor (TCR) signalling threshold. The lymphocyte homeostatic cytokine interleukin 7 (IL-7) is known to affect TCR thresholding, but the molecular mechanism is not fully elucidated. A better understanding of this process is highly relevant in the context of autoimmune disease therapy and cancer immunotherapy. We sought to characterise the early signalling events attributable to IL-7 priming; in particular, the altered phosphorylation of signal transduction proteins and their molecular localisation to the TCR. By integrating high-resolution proximity- phospho-proteomic and imaging approaches using primary T cells, rather than engineered cell lines or an in vitro expanded T cell population, we uncovered transduction events previously not linked to IL-7. We show that IL-7 leads to dephosphorylation of cytohesin interacting protein (CYTIP) at a hitherto undescribed phosphorylation site (pThr280) and alters the co-localisation of cytohesin-1 with the TCR and LFA-1 integrin. These results show that IL-7, acting via CYTIP and cytohesin-1, may impact TCR activation thresholds by enhancing the co-clustering of TCR and LFA-1 integrin.

The Role of Interleukins in the Pathogenesis of Dermatological Immune-Mediated Diseases

Autoimmune inflammatory diseases are primarily characterized by deregulated expression of cytokines, which drive pathogenesis of these diseases. A number of approved and experimental therapies utilize monoclonal antibodies against cytokine proteins. Cytokines can be classified into different families including the interleukins, which are secreted and act on leukocytes, the tumor necrosis factor (TNF) family, as well as chemokine proteins. In this review article, we focus on the interleukin family of cytokines, of which 39 members have been identified to this date. We outline the role of each of these interleukins in the immune system, and various dermatological inflammatory diseases with a focused discussion on the pathogenesis of psoriasis and atopic dermatitis. In addition, we describe the roles of various interleukins in psychiatric, cardiovascular, and gastrointestinal comorbidities. Finally, we review clinical efficacy and safety data from emerging late-phase anti-interleukin therapies under development for psoriasis and atopic dermatitis. Collectively, additional fundamental and clinical research remains necessary to fully elucidate the roles of various interleukin proteins in the pathogenesis of inflammatory dermatologic diseases, and treatment outcomes in patients.

Transcriptome Analysis of CCR9+ T Helper Cells From Primary Sjögren's Syndrome Patients Identifies CCL5 as a Novel Effector Molecule

Introduction

CCR9+ Tfh-like pathogenic T helper (Th) cells are elevated in patients with primary Sjögren’s syndrome (pSS) and indicated to play a role in pSS immunopathology. Here we delineate the CCR9+ Th cell-specific transcriptome to study the molecular dysregulation of these cells in pSS patients.

Methods

CCR9+, CXCR5+ and CCR9-CXCR5- Th cells from blood of 7 healthy controls (HC) and 7 pSS patients were FACS sorted and RNA sequencing was performed. Computational analysis was used to identify differentially expressed genes (DEGs), coherent gene expression networks and differentially regulated pathways. Target genes were replicated in additional cohorts.

Results

5131 genes were differentially expressed between CCR9+ and CXCR5+ Th cells; 6493 and 4783 between CCR9+ and CCR9-CXCR5- and between CXCR5+ and CCR9-CXCR5-, respectively. In the CCR9+ Th cell subset 2777 DEGs were identified between HC and pSS patients, 1416 and 1077 in the CXCR5+ and CCR9-CXCR5- subsets, respectively. One gene network was selected based on eigengene expression differences between the Th cell subsets and pathways enriched for genes involved in migration and adhesion, cytokine and chemokine production. Selected DEGs of interest (HOPX, SOX4, ITGAE, ITGA1, NCR3, ABCB1, C3AR1, NT5E, CCR5 and CCL5) from this module were validated and found upregulated in blood CCR9+ Th cells, but were similarly expressed in HC and pSS patients. Increased frequencies of CCR9+ Th cells were shown to express higher levels of CCL5 than CXCR5+ and CCR9-CXCR5- Th cells, with the highest expression confined to effector CCR9+ Th cells. Antigenic triggering and stimulation with IL-7 of the Th cell subsets co-cultured with monocytes strongly induced CCL5 secretion in CCR9+ Th cell cocultures. Additionally, effector CCR9+ Th cells rapidly released CCL5 and secreted the highest CCL5 levels upon stimulation.

Conclusion

Transcriptomic analysis of circulating CCR9+ Th cells reveals CCR9-specific pathways involved in effector T cell function equally expressed in pSS patients and HC. Given the increased numbers of CCR9+ Th cells in the blood and inflamed glands of pSS patients and presence of inflammatory stimuli to activate these cells this suggests that CCR9-specific functions, such as cell recruitment upon CCL5 secretion, could significantly contribute to immunopathology in pSS.

Profiling and Characterization of Localized Cytokine Response in Congenital Cleft Affected Lip Tissue

(1) Background: Despite cleft lips and palates belonging to the most common orofacial congenital anomalies, their morphopathogenesis is not yet fully understood. The study aimed to determine the distribution and relation of cytokines interferon-γ (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-2, IL-7, IL-12, and IL-13 in the cleft affected mucosa of the lip. (2) Materials and Methods: Twenty cleft lip (CL) mucosal samples and seven control tissues of oral cavity mucosa were included in the study. Specimen were obtained during reconstruction surgeries and processed by hematoxylin and eosin staining and immunohistochemistry for IFN-γ, TNF-α, IL-2, IL-7, IL-12, and IL-13. (3) Results: The distribution of cytokines was higher overall in the cleft affected epithelium compared to the connective tissue, with TNF-a, IL-2, and IL-12 displaying the highest number of immunopositive cells. With the exception of IL-2, CL specimen showed higher immunoreactivity. IFN-γ displayed only minor immunoreactivity, with no expression in the control epithelium. Correlation analysis was strongest between CL epithelial IL-13 and IFN-γ (z = 0.71, p < 0.0001). (4) Conclusions: The CLP affected epithelium displays high degrees of plasticity in expressing different cytokines, pointing towards the stimulation of a local adaptive immune response based on consistent inflammatory processes.

Epithelial-immune cell interplay in primary Sjögren syndrome salivary gland pathogenesis

In primary Sjögren syndrome (pSS), the function of the salivary glands is often considerably reduced. Multiple innate immune pathways are likely dysregulated in the salivary gland epithelium in pSS, including the nuclear factor-κB pathway, the inflammasome and interferon signalling. The ductal cells of the salivary gland in pSS are characteristically surrounded by a CD4⁺ T cell-rich and B cell-rich infiltrate, implying a degree of communication between epithelial cells and immune cells. B cell infiltrates within the ducts can initiate the development of lymphoepithelial lesions, including basal ductal cell hyperplasia. Vice versa, the epithelium provides chronic activation signals to the glandular B cell fraction. This continuous stimulation might ultimately drive the development of mucosa-associated lymphoid tissue lymphoma. This Review discusses changes in the cells of the salivary gland epithelium in pSS (including acinar, ductal and progenitor cells), and the proposed interplay of these cells with environmental stimuli and the immune system. Current therapeutic options are insufficient to address both lymphocytic infiltration and salivary gland dysfunction. Successful rescue of salivary gland function in pSS will probably demand a multimodal therapeutic approach and an appreciation of the complicity of the salivary gland epithelium in the development of pSS.

Lymphopenia in primary Sjögren's syndrome is associated with premature aging of naïve CD4+ T cells

OBJECTIVE

To investigate peripheral lymphopenia, a frequent finding in primary Sjögren's syndrome (pSS) associated with higher disease activity and increased mortality.

METHODS

Prospective, cross-sectional study of consecutive patients with pSS (n = 66) and healthy controls (n = 181). Lymphocyte subsets were analysed by flow cytometry, naïve (CD45RA+) and memory (CD45RO+) CD4+ T cells were purified by MACS technology. In vitro proliferation and senescence-associated β-galactosidase (SABG) were assessed by flow cytometry. Telomere length and TCR excision circles (TREC) were measured by real-time PCR. Telomerase activity was analysed according to the telomeric repeat amplification protocols (TRAP).

RESULTS

In pSS, lymphopenia mainly affected naïve CD4+ T cells. We noted a lower frequency of proliferating naïve CD4+ T cells ex vivo and decreased homeostatic proliferation in response to IL-7 stimulation in vitro. Furthermore, naïve CD4+ T cells exhibited signs of immune cell aging including shortened telomeres, a reduction in IL-7R expression and accumulation of SABG. The senescent phenotype could be explained by telomerase insufficiency and drastically reduced levels of T-cell receptor excision circles (TRECs), indicating a history of extensive post-thymic cell division. TRECs correlated with the number of naïve CD4+ T cells linking the extend of earlier proliferation to the inability to sustain normal cell numbers.

CONCLUSION

In pSS, evidence for increased proliferation of naïve CD4+ T cells earlier in life is associated with a senescent phenotype unable to sustain homeostasis. The lack of naïve CD4+ T cells forms the basis of lymphopenia frequently observed in pSS.

Interleukin-7/Interferon Axis Drives T Cell and Salivary Gland Epithelial Cell Interactions in Sjögren's Syndrome

OBJECTIVE

Primary Sjögren's syndrome (SS) is characterized by a lymphocytic infiltration of salivary glands (SGs) and the presence of an interferon (IFN) signature. SG epithelial cells (SGECs) play an active role in primary SS pathophysiology. We undertook this study to examine the interactions between SGECs and T cells in primary SS and the role of the interleukin-7 (IL-7)/IFN axis.

METHODS

Primary cultured SGECs from control subjects and patients with primary SS were stimulated with poly(I-C), IFNα, or IFNγ. T cells were sorted from blood and stimulated with IL-7. CD25 expression was assessed by flow cytometry. SG explants were cultured for 4 days with anti-IL-7 receptor (IL-7R) antagonist antibody (OSE-127), and transcriptomic analysis was performed using the NanoString platform.

RESULTS

Serum IL-7 level was increased in patients with primary SS compared to controls and was associated with B cell biomarkers. IL7R expression was decreased in T cells from patients with primary SS compared to controls. SGECs stimulated with poly(I-C), IFNα, or IFNγ secreted IL-7. IL-7 stimulation increased the activation of T cells, as well as IFNγ secretion. Transcriptomic analysis of SG explants showed a correlation between IL7 and IFN expression. Finally, explants cultured with anti-IL-7R antibody showed decreased IFN-stimulated gene expression.

CONCLUSION

These results suggest the presence of an IL-7/IFNγ amplification loop involving SGECs and T cells in primary SS. IL-7 was secreted by SGECs stimulated with type I or type II IFN and, in turn, activated T cells that secrete type II IFN. An anti-IL-7R antibody decreased the IFN signature in T cells in primary SS and could be of therapeutic interest.

Pathophysiologic role of Interleukin-33/ST2 in Sjögren's syndrome

Interleukin-33 (IL-33) is a member of the IL-1 family and has dual functions as a nuclear factor as well as a cytokine. The pivotal role of IL-33 as an active player contributing to aberrant local and systemic damage has been highlighted in several inflammatory and autoimmune diseases. Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by dry eyes and mouth syndrome due to local dysfunctions of exocrine glands, but also accompanied with systemic manifestations. The pathophysiology of pSS has been advocated as a conjecture of activated B and T cells as well as the production of inflammatory cytokines and autoantibodies, driving epithelial tissue damage and disease progression. In pSS, IL-33 is released in the extracellular space from damaged salivary cells upon pro-inflammatory stimuli and/or dysfunction of epithelial barrier. Counter-regulatory mechanisms are initiated to limit the pro-inflammatory actions of IL-33 as portrayed by an increase in the decoy receptor for IL-33, the soluble form of ST2 (sST2). In pSS and associated diseases, the levels of IL-33 are significantly elevated in the serum or tears of patients. Mechanistically, IL-33 acts in synergy with IL-12 and IL-23 on NK and NKT cells to boost the production of IFN-γ contributing to inflammation. TNF-α, IL-1β and IFN-γ in turn further increase the activation of IL-33/ST2 pathway, thereby constituting a vicious inflammatory loop leading to disease exacerbation. IL-33/ST2 axis is involved in Sjögren's syndrome and opens new perspectives as therapeutic target of one of the culprits in the inflammatory perpetuation.

Thiol/disulfide homeostasis impaired in patients with primary Sjögren's syndrome

Background

Primary Sjögren's syndrome (pSS) is a disease associated with the overexpression of proinflammatory cytokines, and oxidative stress is one of the factors responsible for its etiopathogenesis. This study aimed to investigate the thiol/disulphide homeostasis in pSS patients.

Methods

The study included 68 pSS patients and 69 healthy controls. Thiol/disulphide homeostasis (total thiol, native thiol, and disulphide levels) was measured using the automatic spectrophotometric method developed by Erel and Neselioglu, and the results of the 2 groups were compared.

Results

The gender and age distributions of the pSS and control groups were similar (P = 0.988 and P = 0.065). Total thiol and native thiol levels were lower in the pSS group than in the control group (470.08 ± 33.65 µmol/L vs. 528.21 ± 44.99 µmol/L, P < 0.001, and 439.14 ± 30.67 µmol/L vs. 497.56 ± 46.70 µmol/L, P < 0.001, respectively). There were no differences in disulphide levels between groups [17.00 (range 0.70-217.0) µmol/L vs. 14.95 (range 2.10-40.10) µmol/L, P = 0.195].

Conclusions

It was concluded that the thiol/disulphide balance shifted towards disulphide in patients with pSS.

T Cells Subsets in the Immunopathology and Treatment of Sjogren's Syndrome

Sjogren´s syndrome (SS) is an autoimmune disease whose pathogenesis is characterized by an exacerbated T cell infiltration in exocrine glands, markedly associated to the inflammatory and detrimental features as well as the disease progression. Several helper T cell subsets sequentially converge at different stages of the ailment, becoming involved in specific pathologic roles. Initially, their activated phenotype endows them with high migratory properties and increased pro-inflammatory cytokine secretion in target tissues. Later, the accumulation of immunomodulatory T cells-derived factors, such as IL-17, IFN-γ, or IL-21, preserve the inflammatory environment. These effects favor strong B cell activation, instigating an extrafollicular antibody response in ectopic lymphoid structures mediated by T follicular helper cells (Tfh) and leading to disease progression. Additionally, the memory effector phenotype of CD8+ T cells present in SS patients suggests that the presence of auto-antigen restricted CD8+ T cells might trigger time-dependent and specific immune responses. Regarding the protective roles of traditional regulatory T cells (Treg), uncertain evidence shows decrease or invariable numbers of circulating and infiltrating cells. Nevertheless, an emerging Treg subset named follicular regulatory T cells (Tfr) seems to play a critical protective role owing to their deficiency that enhances SS development. In this review, the authors summarize the current knowledge of T cells subsets contribution to the SS immunopathology, focusing on the cellular and biomolecular properties allowing them to infiltrate and to harm target tissues, and that simultaneously make them key therapeutic targets for SS treatment.

Biologic therapy in Sjögren's syndrome

Sjögren's syndrome (SS) is a chronic autoimmune disease with complex and diverse clinical manifestations. It is characterized by lymphocyte infiltration of exocrine glands such as the salivary gland and lacrimal gland leading to insufficient secretion of the gland, manifested as dry mouth and dry eyes. In addition, it can involve extraglandular organs and cause systemic damage. The pathogenesis of SS is still unclear. At present, symptomatic treatment is the mainstay and there is a lack of effective therapy. With the development of molecular pathways underlying the pathogenesis of SS, more and more novel biological agents are used to treat SS. We summarized and analyzed the existing evidences on the efficacy of biological treatment of SS and their targets. Analysis of the efficacy of biological therapy and improvement of treatment strategies can help to give full play to its therapeutic advantages.

Modulation of Signaling Mediated by TSLP and IL-7 in Inflammation, Autoimmune Diseases, and Cancer

Thymic Stromal Lymphopoietin (TSLP) and Interleukin-7 (IL-7) are widely studied cytokines within distinct branches of immunology. On one hand, TSLP is crucially important for mediating type 2 immunity at barrier surfaces and has been linked to widespread allergic and inflammatory diseases of the airways, skin, and gut. On the other hand, IL-7 operates at the foundations of T-cell and innate lymphoid cell (ILC) development and homeostasis and has been associated with cancer. Yet, TSLP and IL-7 are united by key commonalities in their structure and the structural basis of the receptor assemblies they mediate to initiate cellular signaling, in particular their cross-utilization of IL-7Rα. As therapeutic targeting of TSLP and IL-7 via diverse approaches is reaching advanced stages and in light of the plethora of mechanistic and structural data on receptor signaling mediated by the two cytokines, the time is ripe to provide integrated views of such knowledge. Here, we first discuss the major pathophysiological roles of TSLP and IL-7 in autoimmune diseases, inflammation and cancer. Subsequently, we curate structural and mechanistic knowledge about receptor assemblies mediated by the two cytokines. Finally, we review therapeutic avenues targeting TSLP and IL-7 signaling. We envision that such integrated view of the mechanism, structure, and modulation of signaling assemblies mediated by TSLP and IL-7 will enhance and fine-tune the development of more effective and selective approaches to further interrogate the role of TSLP and IL-7 in physiology and disease.

Sjögren's syndrome: Old and new therapeutic targets

Sjögren's syndrome (SS) is a prototype autoimmune disease characterized by oral and ocular mucosal dryness following chronic inflammation of salivary and lachrymal glands, respectively. Profound B cell hyperactivity along with systemic manifestations including fatigue, musculoskeletal complaints, features related to hepatic, pulmonary, renal and nervous system involvement, as well as lymphoma development can be also present. Despite that activation of both innate and adaptive immune pathways has been long well documented in SS pathogenesis, systemic immunosuppression in SS, in contrast to other autoimmune diseases, has been largely inefficacious. Biological agents previously implemented in successful therapeutic outcomes in rheumatoid arthritis (RA), such as anti-TNF agents, anakinra, tocilizumab and rituximab failed to reach primary outcomes in randomized double-blind controlled trials in the context of SS. Abatacept and belimumab, already licensed for the treatment of RA and lupus respectively, as well combination regimens of both rituximab and belimumab hold some promise in alleviation of SS-specific complaints, but data from large controlled trials are awaited. Recent advances in dissecting the molecular pathways underlying SS pathogenesis led to an expanding number of novel biological compounds directed towards type I interferon system, antigen presentation, costimulatory pathways, B and T cell activation, as well as germinal center formation. While targeting of cathepsin-S (Petesicatib), inducible costimulator of T cells ligand (prezalumab), and lymphotoxin beta receptor (baminercept) failed to fulfil the primary outcome measures, preliminary results from two randomized placebo controlled trials on CD40 blockade (Iscalimab) and B-cell activating factor receptor (Ianalumab) inhibition resulted in significant reduction of SS disease activity, with a favorable so far safety profile. Results from administration of other kinase inhibitors, a transmembrane activator and calcium-modulator and cytophilin ligand interactor TACI fusion protein (RC18), as well as low dose recombinant interleukin-2 to expand T-regulatory cells are currently awaited.

B cell dysregulation in primary Sjögren's syndrome: A review

Primary Sjögren’s syndrome is a chronic autoimmune disorder of unknown etiology and is characterized by progressive focal lymphocytic infiltration of the lacrimal and salivary glands. Comparison of B cell subsets from the peripheral blood and salivary glands of patients with primary Sjögren’s syndrome and those from healthy individuals shows dysregulation and derangement of B cell subsets in both peripheral circulation and in inflamed glandular tissues. This dysregulation is expressed as a decrease in the percentage of CD27+ memory B cells in peripheral blood and an increase in the CD27+ memory B cells in the affected glands. Further, the overall percentage of long-lived autoantibodies-producing plasma cells within the affected glands is increased. In the last two decades, several studies have shown growing evidences that B cells play multiple roles in primary Sjögren’s syndrome pathophysiology, and that dysregulation of these cells may actually play a central role in the disease development.

Autoimmune diseases in China

Autoimmune diseases, such as rheumatoid arthritis, systematic lupus erythematosus and Sjögren's syndrome, are a group of diseases characterized by the activation of immune cells and excessive production of autoantibodies. Although the pathogenesis of these diseases is still not completely understood, studies have shown that multiple factors including genetics, environment and immune responses play important roles in the development and progression of the diseases. In China, there are great achievements in the mechanisms of autoimmune diseases during the last decades. These studies provide new insight to understand the diseases and also shed light on the development of novel therapy.

Pulmonary Manifestations of Primary Sjögren's Syndrome: Underlying Immunological Mechanisms, Clinical Presentation, and Management

Pulmonary involvement in primary Sjögren's syndrome (pSS) is an understudied entity with important clinical implications. Its prevalence has been reported in up to 20% of pSS patients. Pulmonary manifestations of pSS are diverse with involvement of airway and/or lung parenchyma. Histopathology of lung lesions suggests a predominance of submucosal mononuclear cell infiltration consisting predominantly of CD4+ T cells. Current understanding of the pathophysiology of lung disease in pSS suggests a similar process driving the pulmonary process as those in the salivary glands, with epithelial cells playing a critical role in the initiation, maintenance, and symptomatology of the disease. Clinical manifestations of lung involvement in pSS are as varied as the underlying pathology and can be vague and non-specific, thus delaying diagnosis. Management options depend on the underlying pathology but are generally limited due to lack of systematic randomized controlled trials. This review helps summarize our current understanding of lung involvement in pSS.

Interleukin‑12 exacerbates Sjögren's syndrome through induction of myeloid‑derived suppressor cells

Interleukin (IL)-12 modulates the generation and function of various immune cells and plays a vital role in the pathogenesis of Sjögren's syndrome (SS). Myeloid-derived suppressor cells (MDSCs) are involved in autoimmune diseases by regulating various immune responses. However, it has not been confirmed whether inflammatory IL-12 participates in the progression of SS via regulating MSDCs. In the present study, the plasma levels of IL-12 were detected by ELISA in SS-like non-obese diabetic (NOD) mice. The mice were treated by intraperitoneal injection of IL-12 and anti-IL-12 antibody, respectively, and then the salivary flow rate was detected. The pathology of submandibular glands was evaluated in tissue sections stained with hematoxylin and eosin. The proportion of MDSCs was assessed by flow cytometry. The results showed that plasma IL-12 was significantly increased in the SS-like NOD mice comparing with that noted in the control mice. The exogenous IL-12 exacerbated SS-like symptoms of NOD mice and promoted the generation of both bone marrow (BM) and splenic MDSCs in the SS-like NOD mice. Of note, anti-IL-12 alleviated SS-like symptoms of NOD mice and inhibited the generation of BM and splenic MDSCs. Moreover, the generation of MDSCs was crippled in the IL-12-deficient C57BL/6 (Il-12^−/− B6) mice. Our findings suggest that aggravation of SS-like symptoms by IL-12 in NOD mice may be attributed to its promotion of MDSC development.

Salivary gland immunization via Wharton's duct activates differential T-cell responses within the salivary gland immune system

Salivary glands are a major component of the mucosal immune system that confer adaptive immunity to mucosal pathogens. As previously demonstrated, immunization of the submandibular gland with tissue culture-derived murine cytomegalovirus (tcMCMV) or replication-deficient adenoviruses expressing individual murine cytomegalovirus (MCMV) genes protected mice against a lethal MCMV challenge. Here, we report that salivary gland inoculation of BALB/cByJ mice with tcMCMV or recombinant adenoviruses differentially activates T helper (Th)1, -2, and -17 cells in the salivary glands vs. the associated lymph nodes. After inoculation with tcMCMV, lymphocytes from the submandibular gland preferentially express the transcription factor T-cell-specific T-box transcription factor (T-bet), which controls the expression of the hallmark Th1 cytokine, IFN-γ. Lymphocytes from the periglandular lymph nodes (PGLNs) express both T-bet and GATA-binding protein 3 (GATA3), which promotes the secretion of IL-4, -5, and -10 from Th2 cells. In contrast, after inoculation with replication-deficient adenoviruses, lymphocytes from the submandibular gland express T-bet, GATA3, and RAR-related orphan receptor γ, thymus-specific isoform (RORγt) (required for differentiation of Th17 cells) and forkhead box P3 (Foxp3) (required for the differentiation of regulatory T cells). Lymphocytes from the PGLNs were not activated. The differential induction of Th responses in the salivary gland vs. the PGLNs after inoculation with attenuated virus vs. a nominal protein antigen supports the use of the salivary as an alternative mucosal route for administering vaccines.-Liu, G., Zhang, F., Wang, R., London, S. D., London, L. Salivary gland immunization via Wharton's duct activates differential T-cell responses within the salivary gland immune system.

Emerging roles for chemokines and cytokines as orchestrators of immunopathology in Sjögren's syndrome

In primary SS (pSS), chemokines and cytokines orchestrate immunopathology driven by a complex network of interacting inflammatory cells. In recent years, the importance of chemotactic and non-chemotactic cytokines that control function, movement and placing of all cells within the inflamed exocrine glands and directing immunopathology has become increasingly clear. This paper reviews the current knowledge on chemokines and focuses on the emerging roles of novel chemotactic and non-chemotactic mediators in pSS. It highlights their contribution to pathogenic processes such as B cell hyperactivity and the formation of ectopic lymphoid structures. To this end, the role of acquired (CXCR5/CCR9 Th-cell-mediated) and innate (inflammasome/IL-1/IL-18-mediated) pathways in steering immunopathology is discussed.

Anti-IL-7 receptor α monoclonal antibody (GSK2618960) in healthy subjects - a randomized, double-blind, placebo-controlled study

Aim

Interleukin (IL)‐7 signalling modulates T cell activity and is implicated in numerous autoimmune diseases. The present study investigated the safety, pharmacokinetics, target engagement, pharmacodynamics and immunogenicity of GSK2618960, an IL‐7 receptor‐α subunit (CD127) monoclonal antibody.

Methods

A double‐blind (sponsor‐unblind) study of a single intravenous infusion of either GSK2618960 (0.6 mg kg^–1 or 2.0 mg kg^–1) or placebo was carried out in 18 healthy subjects over 24 weeks.

Results

GSK2618960 was well tolerated; there were no serious or significant adverse events. The observed half‐life was 5 (±1) days (2.0 mg kg^–1), with nonlinear pharmacokinetics. Full receptor occupancy (>95%) was observed until day 8 (0.6 mg kg^–1) and day 22 (2.0 mg kg^–1). Maximal inhibition of IL‐7‐mediated signal transducer and activator of transcription 5 (STAT5) phosphorylation was observed in 5/6 subjects until day 22 (2.0 mg kg^–1). Mean circulating IL‐7 and soluble receptor (CD127) levels were increased above baseline during days 2 and 15 (0.6 mg kg^–1) and days 2 and 22 (2.0 mg kg^–1). No meaningful changes were observed in absolute numbers or proportions of immune cell populations or inflammatory cytokine profiles (IL‐6, tumour necrosis factor‐α, interferon‐γ, IL‐2). Persistent antidrug antibodies (ADAs) were detected in 5/6 subjects administered a dose of 0.6 mg kg^–1 (neutralizing in 2/6) and in 6/6 subjects administered 2.0 mg kg^–1 (neutralizing in 5/6).

Conclusion

GSK2618960 was well tolerated and blocked IL‐7 receptor signalling upon full target engagement. Although there was no discernible impact on peripheral T cell subsets in healthy subjects, GSK2618960 may effectively modulate the autoinflammatory activity of pathogenic T cells in diseased tissue. A relatively short half‐life is likely the result of target‐mediated rather than ADA‐mediated clearance.

Involvement of Aquaporins in the Pathogenesis, Diagnosis and Treatment of Sjögren's Syndrome

Sjögren’s syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltration of salivary and lacrimal glands resulting in diminished production of saliva and tears. The pathophysiology of SS has not yet been fully deciphered. Classically it has been postulated that sicca symptoms in SS patients are a double step process whereby lymphocytic infiltration of lacrimal and salivary glands (SG) is followed by epithelial cell destruction resulting in keratoconjunctivitis sicca and xerostomia. Recent advances in the field of the pathophysiology of SS have brought in new players, such as aquaporins (AQPs) and anti AQPs autoantibodies that could explain underlying mechanistic processes and unveil new pathophysiological pathways offering a deeper understanding of the disease. In this review, we delineate the link between the AQP and SS, focusing on salivary glands, and discuss the role of AQPs in the treatment of SS-induced xerostomia.

TRP Channel Involvement in Salivary Glands-Some Good, Some Bad

Salivary glands secrete saliva, a mixture of proteins and fluids, which plays an extremely important role in the maintenance of oral health. Loss of salivary secretion causes a dry mouth condition, xerostomia, which has numerous deleterious consequences including opportunistic infections within the oral cavity, difficulties in eating and swallowing food, and problems with speech. Secretion of fluid by salivary glands is stimulated by activation of specific receptors on acinar cell plasma membrane and is mediated by an increase in cytosolic [Ca²⁺] ([Ca²⁺]_i). The increase in [Ca²⁺]_i regulates a number of ion channels and transporters that are required for establishing an osmotic gradient that drives water flow via aquaporin water channels in the apical membrane. The Store-Operated Ca²⁺ Entry (SOCE) mechanism, which is regulated in response to depletion of ER-Ca²⁺, determines the sustained [Ca²⁺]_i increase required for prolonged fluid secretion. Core components of SOCE in salivary gland acinar cells are Orai1 and STIM1. In addition, TRPC1 is a major and non-redundant contributor to SOCE and fluid secretion in salivary gland acinar and ductal cells. Other TRP channels that contribute to salivary flow are TRPC3 and TRPV4, while presence of others, including TRPM8, TRPA1, TRPV1, and TRPV3, have been identified in the gland. Loss of salivary gland function leads to dry mouth conditions, or xerostomia, which is clinically seen in patients who have undergone radiation treatment for head-and-neck cancers, and those with the autoimmune exocrinopathy, Sjögren’s syndrome (pSS). TRPM2 is a unique TRP channel that acts as a sensor for intracellular ROS. We will discuss recent studies reported by us that demonstrate a key role for TRPM2 in radiation-induced salivary gland dysfunction. Further, there is increasing evidence that TRPM2 might be involved in inflammatory processes. These interesting findings point to the possible involvement of TRPM2 in Sjögren’s Syndrome, although further studies will be required to identify the exact role of TRPM2 in this disease.

Anti-IL-7 receptor-α treatment ameliorates newly established Sjögren's-like exocrinopathy in non-obese diabetic mice

The levels of interleukin (IL)-7 and its receptor are elevated in the salivary glands of patients with Sjögren's syndrome (SS). Our previous study indicates that IL-7 plays a critical pathogenic role in the development and onset of SS in a mouse model of this disease. The present study aims at determining whether IL-7 also plays a role in sustaining SS pathologies after the disease onset, by using the non-obese diabetic (NOD) model. Intraperitoneal administration of a blocking antibody against the IL-7 receptor α chain (IL-7Rα) to female NOD mice aged 10 weeks, which exhibited newly onset clinical SS, for the duration of 3 weeks significantly ameliorated characteristic SS pathologies including hyposalivation and leukocyte infiltration of the submandibular glands (SMGs). These changes were accompanied by a decrease in IFN-γ-producing CD4 T- and CD8 T cells, B cells, and lymphocyte chemoattractants CXCL9, -10, -11 and -13 in the SMGs. Anti-IL-7Rα treatment markedly diminished the amount of TNF-α in the SMGs and increased the level of claudin-1 and aquaporin 5, two molecules critical for normal salivary secretion. Furthermore, neutralization of IFN-γ and TNF-α, individually or in combination, considerably improved salivary secretion, reduced leukocyte infiltration and down-regulated CXCL9 and -13 expression in the SMGs. Collectively, the results indicate that endogenous IL-7R signals promote Th1 and Tc1 responses and IFN-γ- and TNF-α production to sustain the persistence of SS-like sialadenitis in NOD mice. These findings suggest that IL-7 and Th1 cytokines could serve as promising therapeutic targets for this prevalent autoimmune disease.

Cytokines as therapeutic targets in primary Sjögren syndrome

Primary Sjögren syndrome (SjS) is a systemic autoimmune disease that may affect 1 in 1000 people (overwhelmingly women) and that can be a serious disease with excess mortality due to severe organ-specific involvements and the development of B cell lymphoma; systemic involvement clearly marks the disease prognosis, and strongly suggests the need for closer follow-up and more robust therapeutic management. Therapy is established according to the organ involved and severity. As a rule, the management of systemic SjS should be organ-specific, with glucocorticoids and immunosuppressive agents limited to potentially-severe involvements; unfortunately, the limited evidence available for these drugs, together with the potential development of serious adverse events, makes solid therapeutic recommendations difficult. The emergence of biological therapies has increased the therapeutic armamentarium available to treat primary SjS. Biologics currently used in SjS patients are used off-label and are overwhelmingly agents targeting B cells, but the most recent studies are moving on into the evaluation of targeting specific cytokines involved in the SjS pathogenesis. The most recent etiopathogenic advances in SjS are shedding some light in the search for new highly-selective biological therapies without the adverse effects of the standard drugs currently used (corticosteroids and immunosuppressant drugs). This review summarizes the potential pharmacotherapeutic options targeting the main cytokine families involved in the etiopathogenesis of primary SjS and analyzes potential insights for developing new therapies.

Functional effects of proinflammatory factors present in Sjögren's syndrome salivary microenvironment in an in vitro model of human salivary gland

Primary Sjögren’s syndrome (pSS) is an autoimmune exocrinopathy in which the role that the immune response plays in reducing exocrine gland function, including the glandular microenvironment of cytokines, has not been fully understood. Epithelial cells from biopsies of human parotid gland (HPG) were used to establish a model of human salivary gland in vitro. In this model, the functional consequences of several proinflammatory soluble factors present in the pSS glandular microenvironment were assessed. Stimulation with isoproterenol and calcium produced a significant increase in the basal activity of amylase in the HPG cell supernatants. Under these conditions, the presence of TNF-α and CXCL12 increased amylase mRNA cellular abundance, but reduced the amylase activity in the cell-free supernatant in a dose-dependent manner. IL-1β and IFN-γ, but not TGF-β, also diminished amylase secretion by HPG cells. These results suggest that the glandular microenvironment of cytokine, by acting post-transcriptionally, may be responsible, at least in part, for the reduced exocrine function observed in pSS patients. These data may help to a better understanding of the pathogenesis of SS, which in turn would facilitate the identification of new therapeutic targets for this disorder.

Association of Increased Treg Cell Levels With Elevated Indoleamine 2,3-Dioxygenase Activity and an Imbalanced Kynurenine Pathway in Interferon-Positive Primary Sjögren's Syndrome

OBJECTIVE

Indoleamine 2,3-dioxygenase (IDO), the rate-limiting enzyme that converts tryptophan to kynurenine, is driven in part by type I and type II interferons (IFNs). Naive T cells are polarized into FoxP3+ Treg cells upon exposure to either IDO+ cells or kynurenine. Recent studies have suggested that the kynurenine pathway reflects a crucial interface between the immune and nervous system. The aims of the present study were to evaluate whether Treg cell levels are elevated, in conjunction with increased IDO activity, in patients with primary Sjögren's syndrome (SS) who are positive for the IFN gene expression signature, and to investigate the downstream kynurenine pathway in these patients.

METHODS

Serum from 71 healthy controls, 58 IFN-negative patients with primary SS, and 66 IFN-positive patients with primary SS was analyzed using high-performance liquid chromatography to measure the levels of tryptophan and kynurenine. Expression levels of messenger RNA (mRNA) for IDO and downstream enzymes in the kynurenine pathway were assessed in CD14+ monocytes using real-time quantitative polymerase chain reaction. CD4+CD45RO+ T helper memory cell populations were analyzed by flow cytometry.

RESULTS

Significantly increased levels of IDO activity (assessed as the kynurenine:tryptophan ratio) (P = 0.0054) and percentages of CD25(high) FoxP3+ Treg cells (P = 0.039) were observed in the serum from IFN-positive patients with primary SS, and these parameters were significantly correlated with one another (r = 0.511, P = 0.002). In circulating monocytes from IFN-positive patients with primary SS, the expression of IDO1 mRNA was up-regulated (P < 0.0001), and this was correlated with the IFN gene expression score (r = 0.816, P < 0.0001). Interestingly, the proapoptotic and neurotoxic downstream enzyme kynurenine 3-monooxygenase was up-regulated (P = 0.0057), whereas kynurenine aminotransferase I (KATI) (P = 0.0003), KATIII (P = 0.016), and KATIV (P = 0.04) were down-regulated in IFN-positive patients with primary SS compared to healthy controls.

CONCLUSION

These findings demonstrate enhanced IDO activity in conjunction with increased percentages of CD25(high) FoxP3+ Treg cells in primary SS patients who carry the IFN signature. In addition, IFN-positive patients with primary SS exhibit an imbalanced kynurenine pathway, with evidence of a shift toward potentially more proapoptotic and neurotoxic metabolites. Intervening in these IFN- and IDO-induced immune system imbalances may offer a new array of possibilities for therapeutic interventions in patients with primary SS.

A gene network regulated by the transcription factor VGLL3 as a promoter of sex-biased autoimmune diseases

Autoimmune diseases affect 7.5% of the US population, and they are among the leading causes of death and disability. A notable feature of many autoimmune diseases is their greater prevalence in females than in males, but the underlying mechanisms of this have remained unclear. Through the use of high-resolution global transcriptome analyses, we demonstrated a female-biased molecular signature associated with susceptibility to autoimmune disease and linked this to extensive sex-dependent co-expression networks. This signature was independent of biological age and sex-hormone regulation and was regulated by the transcription factor VGLL3, which also had a strong female-biased expression. On a genome-wide level, VGLL3-regulated genes had a strong association with multiple autoimmune diseases, including lupus, scleroderma and Sjögren's syndrome, and had a prominent transcriptomic overlap with inflammatory processes in cutaneous lupus. These results identified a VGLL3-regulated network as a previously unknown inflammatory pathway that promotes female-biased autoimmunity. They demonstrate the importance of studying immunological processes in females and males separately and suggest new avenues for therapeutic development.

High salivary soluble L-selectin and interleukin-7 levels in Asian Indian patients with primary Sjögren's syndrome

In present study, we aimed to study salivary soluble L-selectin (sL-selectin), interleukin-7(IjL-7), and lymphotoxin-α levels in primary Sjögren's syndrome (pSS) and their clinical as well as serological correlations. pSS patients fulfilling either the American European Consensus Group (AECG) and/or the American college of Rheumatology (ACR) criteria were recruited. Age- and sex-matched hospital staff were recruited as healthy controls. Unstimulated saliva was collected by the spitting method; sL-selectin, IL-7, and lymphotoxin-α were measured in the saliva using commercial ELISA kits. Forty-three patients with pSS and 31 healthy controls were included in the study. Increased levels of sL-selectin and IL-7 were found in the saliva of patients as compared to controls. Lymphotoxin-α was undetectable in the saliva of pSS patients and controls. Salivary sL-selectin positively correlated with rheumatoid factor (r = 0.47; p < 0.003). No other variable including ESSDAI was significantly associated with salivary sL-selectin and IL-7 levels. Indian patients with primary Sjögren's syndrome have higher salivary sL-selectin and IL-7 levels than healthy controls.

Sjögren syndrome

Sjögren syndrome (SjS) is a systemic autoimmune disease that primarily affects the exocrine glands (mainly the salivary and lacrimal glands) and results in the severe dryness of mucosal surfaces, principally in the mouth and eyes. This disease predominantly affects middle-aged women, but can also be observed in children, men and the elderly. The clinical presentation of SjS is heterogeneous and can vary from sicca symptoms to systemic disease (characterized by peri-epithelial lymphocytic infiltration of the affected tissue or the deposition of the immune complex) and lymphoma. The mechanism underlying the development of SjS is the destruction of the epithelium of the exocrine glands, as a consequence of abnormal B cell and T cell responses to the autoantigens Ro/SSA and La/SSB, among others. Diagnostic criteria for SjS include the detection of autoantibodies in patient serum and histological analysis of biopsied salivary gland tissue. Therapeutic approaches for SjS include both topical and systemic treatments to manage the sicca and systemic symptoms of disease. SjS is a serious disease with excess mortality, mainly related to the systemic involvement of disease and the development of lymphomas in some patients. Knowledge of SjS has progressed substantially, but this disease is still characterized by sicca symptoms, the systemic involvement of disease, lymphocytic infiltration to exocrine glands, the presence of anti-Ro/SSA and anti-La/SSB autoantibodies and the increased risk of lymphoma in patients with SjS.

Salivary Gland Pathology in Sjögren's Syndrome

Primary Sjögren syndrome (pSS) can be considered a systemic autoimmune disease with a strong organ bias. The involvement of the exocrine glands is prevalent and drives the pathognomonic manifestations of dryness that define the sicca syndrome. The salivary glands also represent the hub of pSS pathology. Elements belonging to both innate and acquired immune responses have been described at this site that contribute to disease establishment and progression. The interaction between those elements and their relative contributions to the clinical manifestations and lymphoma progression largely remain to be addressed.

Targeting IL-10 in auto-immune diseases

IL-10 is a multifunctional cytokine secreted by a variety of cells. It not only inhibits activation of monocyte/macrophage system and synthesis of monocyte cytokine and inflammatory cytokine but also promotes the proliferation and maturation of non-monocyte-dependent T cell, stimulating proliferation of antigen-specific B cell. Increasing evidence indicates that IL-10 plays an important role in both the onset and development of auto-immune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjogren's syndrome (SS), multiple sclerosis (MS), Crohn's disease (CD), and psoriasis. However, the exact mechanisms of IL-10 in auto-immune diseases remain unclear. In the present review, we will summarize the biological effects of IL-10, as well as its role and therapeutic potential in auto-immune diseases.

Decreased serum level of IL-7 in patients with active Graves' disease

BACKGROUND

Graves' disease (GD) is a common autoimmune disease which is one of the major causes of hyperthyroidism. Interleukin 7 (IL-7) has been recently reported to play an important role in various autoimmune diseases, but its role in the pathogenesis of GD has not been assessed. The aim of this study was to evaluate the levels of IL-7 and the soluble form of its receptor (sIL-7R) in the serum of GD patients, and to identify their association with disease activity.

METHODS

A total of 37 GD patients were enrolled into the experimental group and 16 individuals into the control group. All patients were further classified into three subgroups: a GD-active group (hyperthyroidism and TRAb (thyroid stimulating hormone receptor antibody) >7.5 U/L) (N=15), a GD-inactive group (euthyreosis and TRAb<1 U/L) (N=8), and other GD patients (euthyreosis and TRAb>1 U/L) (N=14). Concentrations of IL-7 and sIL-7R were assayed with ELISA. Additionally, the relationship between IL-7 and sIL-7R serum concentrations with disease activity (free triiodothyronine [FT3], free thyroxine [FT4], thyroid stimulating hormone [TSH] and TRAb) was also analyzed.

RESULTS

The serum concentrations of IL-7 in GD-active patients were significantly lower than those of the control group as well as the GD-inactive and GD-other groups. The serum level of IL-7 in GD patients negatively correlated with FT4 and TRAb concentrations. Moreover, no significant difference was observed in the serum level of sIL-7R in GD patients compared to the control group.

CONCLUSIONS

These observations suggest that IL-7 may play a role in the pathogenesis of GD and may be associated with its clinical activity. To this end, the serum level of IL-7 could be an additional diagnostic biomarker predictive of the disease and could be particularly valuable for TRAb-negative GD patients.