Regulatory T cells: a new therapeutic link for Sjögren syndrome?

miRNA let-7f-5p-encapsulated labial gland MSC-derived EVs ameliorate experimental Sjögren's syndrome by suppressing Th17 cells via targeting RORC/IL-17A signaling axis

Sjögren's syndrome (SS) is an autoimmune disease primarily affecting salivary glands, with xerostomia as a distinct clinical manifestation. This disease also poses a significantly increased risk of lymphoma, severely impacting patients' quality of life. The imbalance between Th17 and Treg cells plays a critical role in SS progression, driving severe immune dysregulation, chronic inflammation, and escalating tissue dysfunction. However, current clinical treatments for SS still remain limited, and it continues to be recognized as a refractory disease. Therefore, the development of novel and effective therapeutic strategies is a pressing demand in clinical research. In recent years, extracellular vesicle (EV) therapy has emerged as a promising approach for autoimmune disease treatment, showing encouraging outcomes in modulating immune balance and alleviating symptoms. EVs carry diverse cargo, among which microRNAs (miRNAs) are highly abundant and play critical roles. These small RNAs are essential for EV-mediated functions, particularly in regulating gene expression and modulating the immune microenvironment. Our research team first isolated labial gland mesenchymal stem cells (LGMSCs) and their derived EVs (LGMSC-EVs), which offer potential therapeutic advantages in SS due to their salivary gland origin. Then we screened and identified the highly enriched miRNA let-7f-5p as a key regulator through miRNA profiling analysis. To achieve better therapeutic outcomes, we transfected exogenous miRNA let-7f-5p into LGMSC-EVs to upregulate its expression, thereby constructing let-7f-5p-encapsulated LGMSC-EVs. These modified EVs were subsequently tested in an experimental SS mouse model to evaluate their therapeutic potential. The upregulation of miRNA let-7f-5p in LGMSC-EVs significantly enhanced their therapeutic effects, resulting in clinical improvements such as increased salivary flow and reduced lymphocytic infiltration. Mechanistically, let-7f-5p-encapsulated LGMSC-EVs suppressed Th17 cells by directly targeting the 3'-untranslated region (3'UTR) of RORC, inhibiting the RORC/IL-17A signaling axis, and reducing IL-17A production, thereby restoring Th17/Treg balance and promoting an anti-inflammatory profile. Collectively, this let-7f-5p-encapsulated LGMSC-EV therapy offers a promising target-driven approach for the treatment of SS, achieving improved clinical outcomes and immune rebalance after modification with miRNA let-7f-5p, which presents new potential for the clinical treatment of SS.

How to focus on autoantigen-specific lymphocytes: a review on diagnosis and treatment of Sjogren's syndrome

Sjogren's syndrome (SS) is an autoimmune epithelitis characterized by focal lymphocytic infiltration against self-antigens leading to progressive glandular dysfunction, which can develop to multisystem manifestation. The classification criteria for SS emphasizes glandular lymphocyte infiltrates and anti-SSA/SSB seropositivity, which is usually manifested in advanced patients. Therapeutically, apart from symptomatic treatment, treatment of SS is based on glucocorticoids and conventional synthetic disease-modifying antirheumatic drugs with global immunosuppression, but the efficacy of biologic or targeted synthetic therapies is still sparse. Currently, emerging studies focus on autoantigen-specific immunotherapies to treat autoimmune disorders by directly eliminating autoreactive cell subsets and inducing tolerance by increasing the autoreactive regulatory lymphocytes. Herein, we summarize the current state of research on the autoantigen-specific approaches for detecting autoreactive lymphocytes and outline the current autoantigen-specific immunotherapies in other autoimmune disorders and their attempts in treatment of SS. Last, we discuss the potential value of focusing on autoantigen-specific lymphocytes in the early diagnosis, monitoring, and targeted treatment of SS. Potential strategies for targeting autoreactive lymphocytes need to be confirmed in SS.

Targeted Therapy for Severe Sjogren's Syndrome: A Focus on Mesenchymal Stem Cells

Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by the infiltration of lymphocytes on salivary and lacrimal glands, resulting in their dysfunction. Patients suffering from severe pSS have an increased risk of developing multi-organ dysfunction syndrome due to the development of systemic inflammatory response, which results in immune cell-driven injury of the lungs, kidneys, liver, and brain. Therapeutic agents that are used for the treatment of severe pSS encounter various limitations and challenges that can impact their effectiveness. Accordingly, there is a need for targeted, personalized therapy that could address the underlying detrimental immune response while minimizing side effects. Results obtained in a large number of recently published studies have demonstrated the therapeutic efficacy of mesenchymal stem cells (MSCs) in the treatment of severe pSS. MSCs, in a juxtacrine and paracrine manner, suppressed the generation of inflammatory Th1 and Th17 lymphocytes, induced the expansion of immunosuppressive cells, impaired the cross-talk between auto-reactive T and B cells, and prevented the synthesis and secretion of auto-antibodies. Additionally, MSC-derived growth and trophic factors promoted survival and prevented apoptosis of injured cells in inflamed lacrimal and salivary glands, thereby enhancing their repair and regeneration. In this review article, we summarized current knowledge about the molecular mechanisms that are responsible for the beneficial effects of MSCs in the suppression of immune cell-driven injury of exocrine glands and vital organs, paving the way for a better understanding of their therapeutic potential in the targeted therapy of severe pSS.

IFN-γ-producing TH1 cells and dysfunctional regulatory T cells contribute to the pathogenesis of Sjögren's disease

Sjögren's disease (SjD) is an autoimmune disorder characterized by progressive salivary and lacrimal gland dysfunction, inflammation, and destruction, as well as extraglandular manifestations. SjD is associated with autoreactive B and T cells, but its pathophysiology remains incompletely understood. Abnormalities in regulatory T (Treg) cells occur in several autoimmune diseases, but their role in SjD is ambiguous. We had previously shown that the function and development of Treg cells depend on store-operated Ca2+ entry (SOCE), which is mediated by ORAI1 Ca2+ channels and stromal interaction protein 1 (STIM1) and STIM2. Here, we show that mice with a Foxp3+ Treg cell-specific deletion of Stim1 and Stim2 develop a phenotype that fulfills all classification criteria of human SjD. Mutant mice have salivary and lacrimal gland inflammation characterized by strong lymphocyte infiltration and transcriptional signatures dominated by T helper 1 (TH1) and interferon (IFN) signaling. CD4+ T cells from mutant mice are sufficient to induce SjD-like disease in an IFN-γ-dependent manner. Inhibition of IFN signaling with the JAK1/2 inhibitor baricitinib alleviated CD4+ T cell-induced SjD in mice. These findings are consistent with the transcriptional profiles of CD4+ T cells from patients with SjD, which indicate enhanced TH1 but reduced memory Treg cell function. Together, our study provides evidence for a critical role of dysfunctional Treg cells and IFN-γ-producing TH1 cells in the pathogenesis of SjD.

Single-cell transcriptomic analysis uncovers heterogeneity in the labial gland microenvironment of primary Sjögren's syndrome

Objective

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disorder with an unclear pathogenetic mechanism in the labial gland. This study aims to investigate the cellular and molecular mechanisms contributing to the development of this disease.

Methods

Single-cell RNA sequencing (scRNA-seq) was performed on 32,337 cells of labial glands from three pSS patients and three healthy individuals. We analyzed all cell subsets implicated in pSS pathogenesis.

Results

Our research revealed diminished differentiation among epithelial cells, concomitant with an enhancement of interferons (IFNs)-mediated signaling pathways. This indicates a cellular functional shift in reaction to inflammatory triggers. Moreover, we observed an augmentation in the population of myofibroblasts and endothelial cells, likely due to the intensified IFNs signaling, suggesting a possible reconfiguration of tissue structure and vascular networks in the impacted regions. Within the immune landscape, there was an apparent increase in immunosuppressive macrophages and dendritic cells (DCs), pointing to an adaptive immune mechanism aimed at modulating inflammation and averting excessive tissue harm. Elevated activation levels of CD4+T cells, along with a rise in regulatory T (Treg) cells, were noted, indicating a nuanced immune interplay designed to manage the inflammatory response. In the CD8+T cell subsests, we detected a notable increase in cells expressing granzyme K (GZMK), signaling an intensified cytotoxic activity. Additionally, the escalated presence of T cells with high levels of heat shock proteins (HSPs) suggests a cellular stress condition, possibly associated with persistent low-grade inflammation, mirroring the chronic aspect of the condition.

Conclusions

Our research identified distinct stromal and immune cell populations linked to pSS, revealing new potential targets for its management. The activation of myeloid, B, and T cells could contribute to pSS pathogenesis, providing important guidance for therapeutic approaches.

The potential therapeutic role of IL-35 in pathophysiological processes in type 1 diabetes mellitus

A chronic autoimmune condition known as type 1 diabetes mellitus (T1DM) has characteristics marked by a gradual immune-mediated deterioration of the β-cells that produce insulin and causes overt hyperglycemia. it affects more than 1.2 million kids and teenagers (0-19 years old). In both, the initiation and elimination phases of T1DM, cytokine-mediated immunity is crucial in controlling inflammation. T regulatory (Treg) cells, a crucial anti-inflammatory CD4+ T cell subset, secretes interleukin-35 (IL-35). The IL-35 has immunomodulatory properties by inhibiting pro-inflammatory cells and cytokines, increasing the secretion of interleukin-10 (IL-10) as well as transforming Growth Factor- β (TGF-β), along with stimulating the Treg and B regulatory (Breg) cells. IL-35, it is a possible target for cutting-edge therapies for cancers, inflammatory, infectious, and autoimmune diseases, including TIDM. Unanswered questions surround IL-35's function in T1DM. Increasing data suggests Treg cells play a crucial role in avoiding autoimmune T1DM. Throughout this review, we will explain the biological impacts of IL-35 and highlight the most recently progresses in the roles of IL-35 in treatment of T1DM; the knowledge gathered from these findings might lead to the development of new T1DM treatments. This review demonstrates the potential of IL-35 as an effective autoimmune diabetes inhibitor and points to its potential therapeutic value in T1DM clinical trials.

Functional significance of DNA methylation: epigenetic insights into Sjögren's syndrome

Sjögren's syndrome (SjS) is a systemic, highly diverse, and chronic autoimmune disease with a significant global prevalence. It is a complex condition that requires careful management and monitoring. Recent research indicates that epigenetic mechanisms contribute to the pathophysiology of SjS by modulating gene expression and genome stability. DNA methylation, a form of epigenetic modification, is the fundamental mechanism that modifies the expression of various genes by modifying the transcriptional availability of regulatory regions within the genome. In general, adding a methyl group to DNA is linked with the inhibition of genes because it changes the chromatin structure. DNA methylation changes the fate of multiple immune cells, such as it leads to the transition of naïve lymphocytes to effector lymphocytes. A lack of central epigenetic enzymes frequently results in abnormal immune activation. Alterations in epigenetic modifications within immune cells or salivary gland epithelial cells are frequently detected during the pathogenesis of SjS, representing a robust association with autoimmune responses. The analysis of genome methylation is a beneficial tool for establishing connections between epigenetic changes within different cell types and their association with SjS. In various studies related to SjS, most differentially methylated regions are in the human leukocyte antigen (HLA) locus. Notably, the demethylation of various sites in the genome is often observed in SjS patients. The most strongly linked differentially methylated regions in SjS patients are found within genes regulated by type I interferon. This demethylation process is partly related to B-cell infiltration and disease progression. In addition, DNA demethylation of the runt-related transcription factor (RUNX1) gene, lymphotoxin-α (LTA), and myxovirus resistance protein A (MxA) is associated with SjS. It may assist the early diagnosis of SjS by serving as a potential biomarker. Therefore, this review offers a detailed insight into the function of DNA methylation in SjS and helps researchers to identify potential biomarkers in diagnosis, prognosis, and therapeutic targets.

Regulatory T cells and IFN-γ-producing Th1 cells play a critical role in the pathogenesis of Sjögren's Syndrome

Objectives

Sjögren's Disease (SjD) is an autoimmune disorder characterized by progressive dysfunction, inflammation and destruction of salivary and lacrimal glands, and by extraglandular manifestations. Its etiology and pathophysiology remain incompletely understood, though a role for autoreactive B cells has been considered key. Here, we investigated the role of effector and regulatory T cells in the pathogenesis of SjD.

Methods

Histological analysis, RNA-sequencing and flow cytometry were conducted on glands, lungs, eyes and lymphoid tissues of mice with regulatory T cell-specific deletion of stromal interaction proteins (STIM) 1 and 2 ( Stim1/2 Foxp3 ), which play key roles in calcium signaling and T cell function. The pathogenicity of T cells from Stim1/2 Foxp3 mice was investigated through adoptively transfer into lymphopenic host mice. Additionally, single-cell transcriptomic analysis was performed on peripheral blood mononuclear cells (PBMCs) of patients with SjD and control subjects.

Results

Stim1/2 Foxp3 mice develop a severe SjD-like disorder including salivary gland (SG) and lacrimal gland (LG) inflammation and dysfunction, autoantibodies and extraglandular symptoms. SG inflammation in Stim1/2 Foxp3 mice is characterized by T and B cell infiltration, and transcriptionally by a Th1 immune response that correlates strongly with the dysregulation observed in patients with SjD. Adoptive transfer of effector T cells from Stim1/2 Foxp3 mice demonstrates that the SjD-like disease is driven by interferon (IFN)-γ producing autoreactive CD4 + T cells independently of B cells and autoantiboodies. scRNA-seq analysis identifies increased Th1 responses and attenuated memory Treg function in PBMCs of patients with SjD.

Conclusions

We report a more accurate mouse model of SjD while providing evidence for a critical role of Treg cells and IFN-γ producing Th1 cells in the pathogenesis of SjD, which may be effective targets for therapy.