Decreased CD4+CD25+bright T cells in peripheral blood of patients with primary Sjogren's syndrome

Sphingosine-1-phosphate alleviates Sjögren's syndrome-like symptoms via inducing autophagy and regulating status of Treg cells in NOD mice

BACKGROUND

Sjögren' s syndrome (SS) is a chronic autoimmune disease that causes multiple lesions. Regulatory T (Treg) cells play an important role in the maintenance of immune homeostasis. Weakened Treg-cell-mediated immunosuppression may aggravate SS symptoms by inducing lymphocyte infiltration into the salivary glands. Although Treg cell egress from such glands requires sphingosine-1-phosphate (S1P), the specific effects of S1P on SS-like symptoms remain unclear.

AIMS

To examine the effect of S1P on SS-like symptoms and the crosstalk between such symptoms and autophagy in non-obese diabetic (NOD) mice.

METHODS

NOD mice were taken as SS model mice. Balb/c mice served as controls. Serum anti-SSA and anti-SSB antibodies were quantitated via ELISA. Submandibular gland tissues were subjected to haematoxylin-and-eosin staining, and extracts thereof to reverse transcription-polymerase chain reaction. The numbers of Treg cells; and the levels of cytokines, LC3, and SPHK1 were measured via flow cytometry (FCM). The Treg immunosuppression capacity was assessed in co-culture experiments.

RESULT

Compared to untreated NOD mice, mice treated with S1P exhibited milder disease, and higher numbers of functional Treg cells. FCM revealed that S1P restored LC3 expression in Treg cells, but had little effect on the LC3 levels of Teff cells. RT-PCR showed that S1P increased the expression levels of mRNAs encoding Foxp-3, SPHK1, S1PR1, and LC3 in submandibular glands (SMGs). After administration of PF-543, the disease became aggravated; lymphocyte infiltration into SMGs increased and LC3 expression fell.

CONCLUSION

S1P therapy alleviated SS-like symptoms in NOD mice by increasing the number of Treg cells, by restoring Treg cell function, and by positively regulating autophagy via crosstalk. Such therapy may be a new and valuable SS treatment option.

Single-Cell Transcriptomics Reveals a Pivotal Role of DOCK2 in Sjögren Disease

OBJECTIVE

Sjögren disease (SjD) is an autoimmune condition characterized by the dysfunction of the salivary and lacrimal glands. The study aimed to decipher the pathogenic cell populations and their immunologic pathways in the salivary glands. We further determined the therapeutic effect of inhibiting dedicator of cytokinesis 2 (DOCK2) shared by novel clusters of CD8+ T cells in an SjD mouse model.

METHODS

This study employed single-cell RNA sequencing to examine the composition and dynamics of immune cells in the salivary glands of SjD mice. By analyzing the transcriptomic data and employing clustering analysis, a specific target was identified, leading to the treatment of mice with a targeted inhibitor.

RESULTS

The results showed diverse immune cell types, including B cells, CD4+ T cells, CD8+ T cells, macrophages, and natural killer cells. We identified specific clusters possessing phenotypic characteristics of immune cell subpopulations, thereby showing specific genes/pathways associated with the disease. The most striking finding was the elevated expression of DOCK2 in CD8+ T cells in the SjD model. This discovery is significant because subsequent treatment with a DOCK2 inhibitor 4-[3-(2-Chlorophenyl)-2-propen-1-ylidene]-1-phenyl-3,5-pyrazolidinedione (CPYPP) led to a marked amelioration of SjD signs.

CONCLUSION

The effectiveness of DOCK2 inhibition in alleviating SjD signs highlights the potential of DOCK2 as a therapeutic target, opening new avenues for treatment strategies that could modulate the immune response more effectively in SjD.

Altered characteristics of regulatory T cells in target tissues of Sjögren's syndrome in murine models

Sjӧgren's syndrome (SS), also known as Sjögren's disease, is a chronic autoimmune condition predominantly affecting the salivary and lacrimal glands. The disease is driven by autoimmune responses involving the activation and actions of major innate- and adaptive immune cell subsets. However, the specific characteristics and roles of regulatory T cells (Tregs) in SS remain elusive. This study seeks to clarify the main phenotypic and functional attributes of Tregs in the salivary glands and their draining lymph nodes in murine models of SS. Our flow cytometric analysis revealed that Tregs in the salivary gland-draining lymph nodes of female non-obese diabetic (NOD) mice, a spontaneous model of SS, exhibited a greater proportion of activated Tregs and fewer resting Tregs compared to Balb/c mice. Furthermore, Tregs from the salivary gland-draining lymph nodes of female C57BL/6.NOD-Aec1Aec2 (B6.NOD-Aec) mice, a model for primary SS, demonstrated significantly lower IL-10 production but markedly higher IFNγ- and IL-17 production than their C57BL/6 counterparts. Additionally, treatment of C57BL/6 Tregs with IL-7, a cytokine critical for SS pathogenesis, resulted in diminished IL-10 production and enhanced IFNγ and IL-17 production in these cells. Notably, the alterations in B6.NOD-Aec Tregs also included an increased expression of the immune-inhibitory molecule CTLA-4 compared to the C57BL/6 Tregs. Intriguingly, in vitro co-cultures of Tregs with conventional CD4 T cells and other key immune populations from lymph nodes indicated that Tregs from salivary gland-draining lymph nodes of both B6.NOD-Aec and C57BL/6 strains exhibited comparable and limited immunosuppressive effects on the proliferation and function of conventional CD4 T cells. The ability of B6.NOD-Aec Tregs to directly inflict damages to salivary gland epithelial tissues and contribute to SS pathologies through IFNγ and IL-17 that they produce warrants further investigations. In addition, enhancing the relatively weak immunosuppressive capacities of these Tregs may also serve as a viable strategy to alleviate the SS phenotype in the mouse models and potentially in patients.

Immunomodulatory Effects of Yu-Ping-Feng Formula on Primary Sjögren's Syndrome: Interrogating the T Cell Response

Ethnopharmacological treatments have shown beneficial effects in the clinical practice of autoimmune disorders. However, the underlying mechanism of immunomodulatory effects remains challenging, given the complicate composition of herbal medicines. Here, we developed an immunological approach to interrogate the T helper cell response. Through data mining we hypothesized that Chinese medicine formula, Yu-Ping-Feng (YPF) might be a promising candidate for treating primary Sjögren's syndrome (pSS), a common autoimmune disease manifested by exocrine gland dysfunction. We took advantage of a mouse model of experimental Sjögren's syndrome (ESS) that we previously established for YPF formula treatment. YPF therapy ameliorated the ESS pathology in mice with active disease, showing improved salivary function and decreased serum levels of autoantibodies. Phenotypic analysis suggested that both effector T and B cells were significantly suppressed. Using co-culture assay and adoptive transfer models, we demonstrated that YPF formula directly restrained effector/memory T cell expansion and differentiation into Th17 and T follicular helper (Tfh) cells, the key subsets in ESS pathogenesis. Importantly, we recruited 20 pSS patients and conducted a pilot study of 8-week therapy of YPF formula. YPF treatment effectively improved fatigue symptoms, exocrine gland functions and reduced serum IgG/IgA levels, while effector T and B cell subsets were significantly decreased. There was a trend of reduction on disease activity, but not statistically significant. Together, our findings suggested a novel approach to assess the immunomodulatory effects of YPF formula, which may be favorable for patients with autoimmune disorders.

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.

Treatment with a Lactococcus lactis that chromosomally express E. coli cfaI mitigates salivary flow loss in a Sjögren's syndrome-like disease

Sjögren's Syndrome (SjS) results in loss of salivary and lacrimal gland excretion due to an autoimmune attack on these secretory glands. Conventional SjS treatments address the symptoms, but not the cause of disease. Recognizing this deficit of treatments to reverse SjS disease, studies were pursued using the fimbriae from enterotoxigenic E. coli, colonization factor antigen I (CFA/I), which has anti-inflammatory properties. To determine if CFA/I fimbriae could attenuate SjS-like disease in C57BL/6.NOD-Aec1Aec2 (SjS) females, the Lactococcus lactis (LL) 301 strain was developed to chromosomally express the cfaI operon. Western blot analysis confirmed CFA/I protein expression, and this was tested in SjS females at different stages of disease. Repeated dosing with LL 301 proved effective in mitigating salivary flow loss and in reducing anti-nuclear antibodies (ANA) and inflammation in the submandibular glands (SMGs) in SjS females and in restoring salivary flow in diseased mice. LL 301 treatment reduced proinflammatory cytokine production with concomitant increases in TGF-β+ CD25+ CD4+ T cells. Moreover, LL 301 treatment reduced draining lymph and SMG follicular T helper (Tfh) cell levels and proinflammatory cytokines, IFN-γ, IL-6, IL-17, and IL-21. Such evidence points to the therapeutic capacity of CFA/I protein to suppress SjS disease and to have restorative properties in combating autoimmune disease.

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

Great advancements have been made in understanding the pathogenesis of SS, but there remain unmet needs for effective and targeted treatments. Glandular and extraglandular dysfunction in SS is associated with autoimmune lymphocytic infiltration that invades the epithelial structures of affected organs. Regulatory T (Treg) cells are a subset of CD4+ T lymphocytes that maintain self-tolerance during physiological conditions. Besides inhibiting excessive inflammation and autoimmune response by targeting various immune cell subsets and tissues, Treg cells have also been shown to promote tissue repair and regeneration in pathogenic milieus. The changes of quantity and function of Treg cells in various autoimmune and chronic inflammatory disorders have been reported, owing to their effects on immune regulation. Here we summarize the recent findings from murine models and clinical data about the dysfunction of Treg cells in SS pathogenesis and discuss the therapeutic strategies of direct or indirect targeting of Treg cells in SS. Understanding the current knowledge of Treg cells in the development of SS will be important to elucidate disease pathogenesis and may guide research for successful therapeutic intervention in this disease.

Association of Ocular Surface Immune Cells With Dry Eye Signs and Symptoms in the Dry Eye Assessment and Management (DREAM) Study

Purpose

Dry eye disease (DED) is a multifactorial, heterogeneous disease of the ocular surface with one etiology being ocular surface inflammation. Studies using animal models demonstrate the role of ocular surface immune cells in the inflammatory pathway leading to DED, but few have evaluated humans. This study described the white blood cell population from the ocular surface of patients with DED and assessed its association with DED signs and symptoms in participants of the Dry Eye Assessment and Management (DREAM) study.

Methods

Participants were assessed for symptoms using the Ocular Surface Disease Index, signs via corneal staining, conjunctival staining, tear break-up time, and Schirmer test, and Sjögren's syndrome (SS) based on the 2012 American College of Rheumatology classification criteria. Impression cytology of conjunctival cells from each eye was evaluated using flow cytometry: T cells, helper T cells (Th), regulatory T cells (Tregs), cytotoxic T cells, and dendritic cells.

Results

We assessed 1049 eyes from 527 participants. White blood cell subtype percentages varied widely across participants. Significant positive associations were found for Th and conjunctival staining (mean score of 2.8 for 0% Th and 3.1 for >4.0% Th; P = 0.007), and corneal staining (mean score of 3.5 for 0% Th and 4.3 for >4.0% Th; P = 0.01). SS was associated with higher percent of Tregs (median 0.1 vs. 0.0; P = 0.01).

Conclusions

Th were associated with more severe conjunctival and corneal staining, possibly indicating their role in inflammation leading to damage of the ocular surface. There is no consistent conclusion about Tregs in SS, but these results support that Tregs are elevated in SS.

The decreased of peripheral blood natural killer cell is associated with serum IL-2 level in the renal tubular acidosis in patients with primary sjogren's syndrome

BACKGROUND

Primary Sjogren's Syndrome (pSS) is a lymphoproliferative disease with autoimmune characteristics, which is characterized by lymphocyte infiltration of exocrine glands and involvement and dysfunction of extraglandular organs. Renal tubular acidosis (RTA) is a common renal involvement in pSS. This study investigated the phenotypic characteristics of peripheral blood lymphocyte subsets and cytokines in pSS patients complicated with RTA (pSS-RTA).

METHOD

This retrospective study included 25 pSS patients complicated with RTA and 54 pSS patients without RTA (pSS-no-RTA). To examine the level of peripheral lymphocytes subsets, flow cytometry analysis was used. The level of serum cytokines were detected by flow cytometry bead array(CBA). The influencing factors related to the occurrence of pSS-RTA were identified through logistic regression analyze.

RESULTS

The absolute number of CD4 + T cells and Th2 cells in peripheral blood were decreased in pSS-RTA patients than pSS-no-RTA patients. Moreover, the absolute number of NK cells and Treg cells were also decreased in pSS-RTA patients than pSS-no-RTA. The level of serum IL-2 was higher in pSS-RTA patients than pSS-no-RTA patients, and is negatively correlated with the number of NK cells, the number and percentage of Th17 cells, and Th17/Treg. Serum IL-2 level is also correlated with various cytokines. Multivariate logistic analysis proved that elevated ESR and ALP were risk factors for pSS complicated with RTA, while Treg was a protective factor.

CONCLUSION

The increase of serum IL-2 level and the decrease of peripheral blood NK cells and Treg cells may be the immune mechanism of the development of pSS-RTA disease.

Is peripheral blood immunophenotyping useful to understand the etiology of Idiopathic Granulomatous?

BACKGROUND

The etiology of idiopathic granulomatous mastitis (IGM) has not been clearly established. However, autoimmunity has recently become popular in etiopathogenesis. We aimed to investigate the immunophenotyping of immune cells to help clarify the etiopathogenesis of the disease.

METHODS

Patients with IGM and healthy volunteers were included in the study. Patients were divided into active and remission groups based on their disease status. The ratios of total T cells, helper T cells, cytotoxic T cells, natural killer cells, regulatory T cells, and monocyte subtypes were measured using flow cytometry. In addition, age, complete blood count for leukocyte, lymphocyte, neutrophil, and eosinophil counts, and the smoking status of all volunteers were evaluated.

RESULTS

A total of 33 volunteers, including 11 patients with active IGM, 10 patients with remission IGM, and 12 healthy volunteers, were included in the study. The neutrophil, eosinophil, neutrophil/lymphocyte, and non-classical monocyte values were significantly higher in IGM patients than in healthy volunteers. Additionally, the CD4⁺ CD25⁺ CD127^- regulatory T cell was significantly lower in IGM patients than in healthy volunteers. Furthermore, neutrophil, neutrophil/lymphocyte ratio, CD4⁺ CD25⁺ CD127^- regulatory T cells, and non-classical monocytes showed significant differences when IGM patients were divided into active and remission groups. IGM patients had higher smoking rates, but this was not statistically significant.

CONCLUSION

The changes in many cell types evaluated in our study were similar to the cell profiles of some autoimmune diseases. This could provide minor evidence to suggest that IGM is an autoimmune granulomatous disease with a local course.

The Role of Regulatory T Cells in the Onset and Progression of Primary Sjögren's Syndrome

Regulatory T cells (Tregs) play a key role in maintaining immune balance and regulating the loss of self-tolerance mechanisms in various autoimmune diseases, including primary Sjögren's syndrome (pSS). With the development of pSS primarily in the exocrine glands, lymphocytic infiltration occurs in the early stages, mainly due to activated CD4⁺ T cells. Subsequently, in the absence of rational therapy, patients develop ectopic lymphoid structures and lymphomas. While the suppression of autoactivated CD4⁺ T cells is involved in the pathological process, the main role belongs to Tregs, making them a target for research and possible regenerative therapy. However, the available information about their role in the onset and progression of this disease seems unsystematized and, in certain aspects, controversial. In our review, we aimed to organize the data on the role of Tregs in the pathogenesis of pSS, as well as to discuss possible strategies of cell therapy for this disease. This review provides information on the differentiation, activation, and suppressive functions of Tregs and the role of the FoxP3 protein in these processes. It also highlights data on various subpopulations of Tregs in pSS, their proportion in the peripheral blood and minor salivary glands of patients as well as their role in the development of ectopic lymphoid structures. Our data emphasize the need for further research on Tregs and highlight their potential use as a cell-based therapy.

Altered subgroups of regulatory T cells in patients with primary Sjögren's syndrome

Primary Sjögren syndrome (pSS) is a systemic autoimmune inflammatory disease. Up to now, the role of regulatory T cells (Tregs) and their subgroups in pSS is still in controversial. In this study we tried to elucidate the roles of Tregs and its subgroups in pSS. Total 43 pSS patients and 23 health persons as control were enrolled in this study. We grouped the pSS patients according to the anti-SSa/SSb and the EULAR Sjögren's syndrome disease activity index (ESSDAI). Among the 43 pSS patients, 14 patients were followed after treatment. The percentage of rTregs (resting Treg cells) among Tregs was increased in the pSS group, and decreased after treatment. In the high disease activity subpopulation (ESSDAI ≥ 5), the percentage of rTregs among Tregs decreased after treatment. On the contrary, the percentage of aTregs (activated Treg cells) increased after treatment. It was in an inverse correlation between the percentage of aTreg and rTreg in pSS patients. The Tregs are co-cultured with responder T cells. Tregs from pSS patients showed poorer proliferation inhibitory function. Our results show that the percentages of Tregs and their subgroups altered in pSS patients. The percentage of aTreg and the percentage of rTreg have an inverse correlation in pSS patients. Compared to the control group, the percentage of rTregs among Tregs was increased in the pSS patients and decreased after the treatment. Our study also showed that The Tregs from pSS patients may have poorer inhibitory functions.

Regulatory T cells (Tregs) and their therapeutic potential against autoimmune disorders - Advances and challenges

Autoimmune diseases are caused when immune cells act against self-protein. This biological self-non-self-discrimination phenomenon is controlled by a distinct group of lymphocytes known as regulatory T cells (Tregs), which are key inflammatory response regulators and play a pivotal role in immune tolerance and homeostasis. Treg-mediated robust immunosuppression provides self-tolerance and protection against autoimmune diseases. However, once this system fails to operate or poorly operate, it leads to an extreme situation where immune system reacts against self-antigens and destroys host organs, thus causing autoimmune diseases. Tregs can target both innate and adaptive immunity via modulating multiple immune cells such as neutrophils, monocytes, antigen-presenting cells, B cells, and T cells. This review highlights the Treg-mediated immunosuppression, role of several markers and their interplay during Treg development and differentiation, and advances in therapeutic aspects of Treg cells to reduce severity of autoimmunity-related conditions along with emphasizing limitations and challenges of their usages.

Exploiting the role of T cells in the pathogenesis of Sjögren's syndrome for therapeutic treatment

Sjögrens syndrome (SS) is caused by autoantibodies that attack proprioceptive salivary and lacrimal gland tissues. Damage to the glands leads to dry mouth and eyes and affects multiple systems and organs. In severe cases, SS is life-threatening because it can lead to interstitial lung disease, renal insufficiency, and lymphoma. Histological examination of the labial minor salivary glands of patients with SS reveals focal lymphocyte aggregation of T and B cells. More studies have been conducted on the role of B cells in the pathogenesis of SS, whereas the role of T cells has only recently attracted the attention of researchers. This review focusses on the role of various populations of T cells in the pathogenesis of SS and the progress made in research to therapeutically targeting T cells for the treatment of patients with SS.

Tregs in Autoimmunity: Insights Into Intrinsic Brake Mechanism Driving Pathogenesis and Immune Homeostasis

CD4⁺CD25^highFoxp3⁺ regulatory T-cells (Tregs) are functionally characterized for their ability to suppress the activation of multiple immune cell types and are indispensable for maintaining immune homeostasis and tolerance. Disruption of this intrinsic brake system assessed by loss of suppressive capacity, cell numbers, and Foxp3 expression, leads to uncontrolled immune responses and tissue damage. The conversion of Tregs to a pathogenic pro-inflammatory phenotype is widely observed in immune mediated diseases. However, the molecular mechanisms that underpin the control of Treg stability and suppressive capacity are incompletely understood. This review summarizes the concepts of T_reg cell stability and T_reg cell plasticity highlighting underlying mechanisms including translational and epigenetic regulators that may enable translation to new therapeutic strategies. Our enhanced understanding of molecular mechanism controlling Tregs will have important implications into immune homeostasis and therapeutic potential for the treatment of immune-mediated diseases.

Sphingosylphosphorylcholine ameliorates experimental sjögren's syndrome by regulating salivary gland inflammation and hypofunction, and regulatory B cells

Sjögren syndrome (SS) is an autoimmune disease in which immune cells infiltrate the exocrine gland. Since SS is caused by a disorder of the immune system, treatments should regulate the immune response. Sphingosylphosphorylcholine (SPC) is a sphingolipid that mediates cellular signaling. In immune cells, SPC has several immunomodulatory functions. Accordingly, this study verifies the immunomodulatory ability and therapeutic effect of SPC in SS. To understand the function of SPC in SS, we treated SPC in female NOD/ShiJcl (NOD) mice. The mice were monitored for 10 weeks, and inflammation in the salivary glands was checked. After SPC treatment, we detected the expression of regulatory B (B_reg) cells in mouse splenocytes and the level of salivary secretion-related genes in human submandibular gland (HSG) cells. Salivary flow rate was maintained in the SPC-treated group compared to the vehicle-treated group, and inflammation in the salivary gland tissues was relieved by SPC. SPC treatment in mouse cells and HSG cells enhanced B_reg cells and salivary secretion markers, respectively. This study revealed that SPC can be considered as a new therapeutic agent against SS.

Anti-Ro/SSA and/or anti-La/SSB antibodies are associated with adverse IVF and pregnancy outcomes

Anti-Ro/SSA and/or anti-La/SSB antibodies (anti-SSA/SSB) were reported to increase the risk of recurrent pregnancy loss. However, the effects of anti-SSA/SSB antibodies on in-vitro fertilization (IVF) and pregnancy outcomes were still unclear. The purpose of the study was to determine whether anti-SSA/SSB antibodies were detrimental to IVF and pregnancy outcomes. This study included 55 anti-SSA/SSB antibodies-positive women and 61 anti-SSA/SSB antibodies-negative control women receiving gonadotropin-releasing hormone (GnRH) agonist long protocol (n = 30 and 39, respectively) or GnRH antagonist protocol (n = 25 and 22, respectively) for in-vitro fertilization and embryo transfer (IVF-ET). The impact of anti-SSA/SSB antibodies on immune-related indicators, fertilization, embryo development and pregnancy outcomes were analyzed. With either GnRH agonist or antagonist protocol, women with anti-SSA/SSB had higher levels of peripheral blood cytokines, including TNF-α and IL-17A, lower levels of peripheral blood Th and NK cells, and poor IVF outcomes, including lower number of retrieved oocytes and embryos, lower M II oocytes rate, blastocyst formation rate, and perfect and available embryo rates. Moreover, clinical pregnancy rate, implantation rate, take-home baby rate, and birth weight were significantly lower in the study group as compared with those of the control group. In conclusion, women with anti-SSA/SSB are associated with adverse IVF and pregnancy outcomes. Screening for these antibodies and proper counselling of couples undergoing IVF-ET should be considered. Underlying immunopathology associated with SSA/SSB antibodies and reproduction should be explored further.

Immunobiology of T Cells in Sjögren's Syndrome

Sjögren's syndrome (SjS) is a systemic autoimmune disease marked by xerostomia (dry mouth), keratoconjunctivitis sicca (eye dryness), and other systematic disorders. Its pathogenesis involves an inflammatory process that is characterized by lymphocytic infiltration into exocrine glands and other tissues. Although the development of ectopic lymphoid tissue and overproduction of autoantibodies by hyperactive B cells suggest that they may promote SjS development, treatment directed towards them fails to induce significant laboratory or clinical improvement. T cells are overwhelming infiltrators in most phases of the disease, and the involvement of multiple T cell subsets of suggests the extraordinary complexity of SjS pathogenesis. The factors, including various cellular subtypes and molecules, regulate the activation and suppression of T cells. T cell activation induces inflammatory cell infiltration, B cell activation, tissue damage, and metabolic changes in SjS. Knowledge of the pathways that link these T cell subtypes and regulation of their activities are not completely understood. This review comprehensively summarizes the research progress and our understanding of T cells in SjS, including CD4⁺ T cells, CD8⁺ T_RM cells, and innate T cells, to provide insights into for clinical treatment.

The Involvement of Innate and Adaptive Immunity in the Initiation and Perpetuation of Sjögren's Syndrome

Sjogren’s syndrome (SS) is a chronic autoimmune disease characterized by the infiltration of exocrine glands including salivary and lachrymal glands responsible for the classical dry eyes and mouth symptoms (sicca syndrome). The spectrum of disease manifestations stretches beyond the classical sicca syndrome with systemic manifestations including arthritis, interstitial lung involvement, and neurological involvement. The pathophysiology underlying SS is not well deciphered, but several converging lines of evidence have supported the conjuncture of different factors interplaying together to foster the initiation and perpetuation of the disease. The innate and adaptive immune system play a cardinal role in this process. In this review, we discuss the inherent parts played by both the innate and adaptive immune system in the pathogenesis of SS.

B7-H4 Inhibits the Development of Primary Sjögren's Syndrome by Regulating Treg Differentiation in NOD/Ltj Mice

Background

This study is aimed at exploring the role of B7-H4 in the pathogenesis of primary Sjögren's syndrome (pSS) in NOD/Ltj mouse.

Methods

B7-H4 expression in salivary glands was examined by IHC, and lymphocyte infiltration was showed by H&E. Next, anti-B7-H4 mAb or immunoglobulin isotype was injected into NOD/Ltj mice. Cytokine levels were measured by quantitative RT-PCR, and immunoglobulins were measured by ELISA. T cell subsets were analyzed by flow cytometry. Last, we treated NOD/Ltj mice with B7-H4Ig and control Ig. CD4+Foxp3+ T cells were assessed by immunohistochemistry. Two-tailed Student's t-tests were used to detect the statistical difference in various measures between the two groups.

Results

B7-H4 expression was remarkably reduced in salivary glands of NOD/Ltj mice at 15 weeks compared with the NOD/Ltj mice at 8 weeks. Anti-B7-H4 mAb treatment increased lymphocyte infiltration in salivary glands. Inflammatory cytokines including IL-12, IL-18, IL-1α, TNF-α, IFN-α, and BAFF were upregulated markedly in anti-B7-H4 mAb-treated mice compared to IgG isotype-treated mice. Flow cytometry analysis showed that anti-B7-H4 mAb-treated mice had lower levels of CD4+Foxp3+/CD4+ T cells in spleen. Moreover, Foxp3 mRNA levels of salivary glands were diminished in anti-B7-H4 mAb-treated mice. Flow cytometry analysis showed that anti-B7-H4 mAb inhibited CD4+Foxp3+/CD4+ T cell production, while B7-H4Ig would promote naïve CD4+ T into Treg differentiation. Administration with B7-H4Ig displayed significantly decreased lymphocyte infiltration in salivary glands and low levels of total IgM and IgG in serum. Analysis of inflammatory cytokines in salivary glands after B7-H4Ig treatment revealed that the mRNA levels of IL-12, IL-6, IL-18, IL-1α, TNF-α, and IFN-α were significantly downregulated in B7-H4Ig-treated mice compared to control Ig treatment. B7-H4Ig-treated mice had significantly higher levels of CD4+Foxp3+/CD4+ T cells in spleen. IHC in salivary gland revealed that CD4+Foxp3+ T cells of B7-H4Ig treatment mouse were more than control Ig treatment.

Conclusions

Our findings implicate that B7-H4 has a protective role for salivary gland epithelial cells (SGECs) and therapeutic potential in the treatment of pSS.

Contributions of Major Cell Populations to Sjögren's Syndrome

Sjögren’s syndrome (SS) is a female dominated autoimmune disease characterized by lymphocytic infiltration into salivary and lacrimal glands and subsequent exocrine glandular dysfunction. SS also may exhibit a broad array of extraglandular manifestations including an elevated incidence of non-Hodgkin’s B cell lymphoma. The etiology of SS remains poorly understood, yet progress has been made in identifying progressive stages of disease using preclinical mouse models. The roles played by immune cell subtypes within these stages of disease are becoming increasingly well understood, though significant gaps in knowledge still remain. There is evidence for distinct involvement from both innate and adaptive immune cells, where cells of the innate immune system establish a proinflammatory environment characterized by a type I interferon (IFN) signature that facilitates propagation of the disease by further activating T and B cell subsets to generate autoantibodies and participate in glandular destruction. This review will discuss the evidence for participation in disease pathogenesis by various classes of immune cells and glandular epithelial cells based upon data from both preclinical mouse models and human patients. Further examination of the contributions of glandular and immune cell subtypes to SS will be necessary to identify additional therapeutic targets that may lead to better management of the disease.

Mesenchymal stem cell transplantation alleviates experimental Sjögren's syndrome through IFN-β/IL-27 signaling axis

Rationale: Although mesenchymal stem cell (MSC) transplantation has been proved to be an effective therapeutic approach to treat experimental Sjögren's syndrome (SS), the detailed underlying mechanisms remains unknown. IL-27 has diverse influences on the regulation of T cell differentiation and was involved in SS through modulating immune response. Here we aimed to explore whether IL-27-mediated regulation of immune cells was responsible for the beneficial effects of MSC transplantation on SS.

Methods: The SS-like symptoms were evaluated in IL-27 deficient and recombinant IL-27-treated NOD mice. The MSCs were infused into NOD mice via the tail vein. The histological features of submandibular glands, saliva flow rate and serum IL-27 were examined. The effects of MSCs on the IL-27 production and Th17/Treg cell in SS patients and mice in vitro and in vivo were determined for the mechanistic study.

Results: This study showed that SS patients had decreased IL-27 level and increased ratio of Th17/Treg cells. Consistently, exacerbated SS-like symptoms were observed in IL-27 deficient NOD mice, along with increased ratio of Th17/Treg cells. Importantly, MSC transplantation alleviated SS-like symptoms by elevating the level of IL-27 to restore Th17/Treg balance in NOD mice. Mechanistically, MSC-secreted interferon-β (IFN-β) promote dendritic cells to produce IL-27.

Conclusions: Thus, we have revealed a previously unrecognized function of MSC-mediated IL-27 production by DCs in suppressing SS-like syndrome, which provided evidences for clinical application of MSC in patients with SS.

T cells in primary Sjögren's syndrome: targets for early intervention

A histologic hallmark of primary SS (pSS) is lymphocytic infiltration of the salivary and lacrimal glands, in particular by CD4⁺ T and B cells. In the early stages of the disease, infiltrates are dominated by CD4⁺ T cells, while B cell accumulation occurs at later stages. Activated T cells contribute to pathogenesis by producing pro-inflammatory cytokines and by inducing B cell activation, which results in the establishment of a positive feedback loop. In the inflamed glandular tissues, many different CD4⁺ effector subsets are present, including IFN-γ-producing Th1 cells, IL-17-producing Th17 cells and IL-21-producing T follicular helper cells. In blood from pSS patients, frequently observed abnormalities of the T cell compartment are CD4⁺ T cell lymphopenia and enrichment of circulating follicular helper T (Tfh) cells. Tfh cells are critical mediators of T cell–dependent B cell hyperactivity and these cells can be targeted by immunotherapy. Inhibition of T cell activation, preferably early in the disease process, can mitigate B cell activity and may be a promising treatment approach in this disease.

CP-25 Alleviates Experimental Sjögren's Syndrome Features in NOD/Ltj Mice and Modulates T Lymphocyte Subsets

Primary Sjögren's syndrome (pSS) is a chronic inflammatory autoimmune illness of the moisture-producing glands such as salivary glands that is characterized by various immune abnormalities. The aetiology of pSS remains unclear and there is no curative agent. In this study, we investigated the putative therapeutic effects on a NOD/Ltj mouse model of Sjögren's syndrome-like disorders of an ester derivative of paeoniflorin, paeoniflorin-6'O-benzene (termed CP-25). Our study showed that CP-25 alleviated effectively clinical manifestations in NOD/Ltj mice resulting, for example, in increased salivary flow and reduced histopathological scores. Furthermore, CP-25 decreased lymphocyte viability in NOD/Ltj mice and attenuated the infiltration of Th1 cells and Th2 cells into the salivary glands of NOD/Ltj mice. In the spleen on NOD/Ltj mice, CP-25 skewed the ratio of Th17 and regulatory T cells towards regulatory T cells. After treatment, concentrations of anti-La/SSB and IgG antibodies were reduced and the titre of the inflammatory cytokines IFN-γ, IL-4, IL-6 and IL-17A in the serum on NOD/Ltj mice was alleviated. Thus, we define CP-25 as a novel compound that is a potent therapeutic agent for pSS by modulating T lymphocyte subsets. Future studies will validate the use of CP-25 as a therapeutic strategy for the treatment of pSS.

IL-2 Inhibition of Th17 Generation Rather Than Induction of Treg Cells Is Impaired in Primary Sjögren's Syndrome Patients

Objective

To investigate the role of IL-2 in the balance of Th17 and Tregs and elucidate the underlying mechanisms of enhanced Th17 differentiation in primary Sjögren’s syndrome (pSS) patients.

Methods

This study involved 31 pSS patients, 7 Sicca patients, and 31 healthy subjects. Th17 and Treg cells were determined by flow cytometry, and IL-17A was detected by immunohistochemistry. IL-2 and IL-6 levels were assessed by ELISA and qPCR. p-STAT5 and p-STAT3 in salivary glands (SGs) were evaluated by immunohistochemistry and flow cytometry. The binding of STAT5 and STAT3 to the Il17a gene locus was measured by chromatin immunoprecipitation.

Results

We found that the percentage of Th17 cells was increased in the periphery and SG of pSS patients when compared with healthy subjects, but the Treg cells was unchanged. Meanwhile, the IL-2 level was reduced, and the IL-6 and IL-17A level was increased in the plasma of pSS patients. The ratio of IL-2 and IL-6 level was also decreased and IL-2 level was negatively correlated with the level of IL-17A. The expression of Il6 and Il17a mRNA was significantly increased, whereas Foxp3, Tgfb1, Tnfa, and Ifng mRNA were comparable. Furthermore, the level of STAT5 phosphorylation (p-STAT5) was reduced and p-STAT3 was enhanced in the SGs and in peripheral CD4⁺ T cells of pSS patients. In vitro IL-2 treatment-induced STAT5 competed with STAT3 binding in human Il17a locus, leading to decreased Th17 differentiation, which was associated with the reduced transcription activation marker H3K4me3.

Conclusion

Our findings demonstrated a Treg-independent upregulation of Th17 generation in pSS, which is likely due to a lack of IL-2-mediated suppression of Th17 differentiation. This study identified a novel mechanism of IL-2-mediated immune suppression in pSS.

Could Lymphocyte Profiling be Useful to Diagnose Systemic Autoimmune Diseases?

Considering the implications of B, T, and natural killer (NK) cells in the pathophysiology of systemic autoimmune diseases, the assessment of their distribution in the blood could be helpful for physicians in the complex process of determining a precise diagnosis. In primary Sjögren's syndrome, transitional and active naive B cells are increased and memory B cells are decreased compared to healthy controls and other systemic diseases. However, their utility to improve the accuracy of classification criteria has not been proven. In early untreated rheumatoid arthritis, proportions of regulatory T cells are constantly reduced, but other patterns are difficult to determine given the heterogeneity of published studies. In systemic lupus erythematosus, the lack of studies using large cohorts of patients and the diversity of the possible pathological mechanisms involved are also important impediments. Nevertheless, transitional B cell and plasma cell proportions are increased in most of the studies, the CD4/CD8 ratio is decreased, and the number of NK cells is reduced. Despite the low number of studies, anomalies of lymphocyte subset distribution was also described in ANCA-associated vasculitis, systemic scleroderma, and myositis. For now, flow cytometric analysis of lymphocyte subsets has focused mainly on specific subpopulations and is more useful for basic and translational research than for diagnostics in clinical practice. However, new modern methods such as mass cytometry and bioinformatics analyses may offer the possibility to simultaneously account for the relative proportions of multiple lymphocyte subsets and define a global profile in homogeneous groups of patients. The years to come will certainly incorporate such global lymphocyte profiling in reclassification of systemic autoimmune diseases.

Aberrant Epigenetic Regulation in the Pathogenesis of Systemic Lupus Erythematosus and Its Implication in Precision Medicine

Great progress has been made in the last decades in understanding the complex immune dysregulation in systemic lupus erythematosus (SLE), yet the efforts to pursue an effective treatment of SLE proved to be futile. The pathoetiology of SLE involves extremely complicated and multifactorial interaction among various genetic and epigenetic factors. Multiple gene loci predispose to disease susceptibility, and the interaction with epigenetic modifications mediated through sex, hormones, and the hypothalamo-pituitary-adrenal axis complicates susceptibility and manifestations of this disease. Finally, certain environmental and psychological factors probably trigger the disease via epigenetic mechanisms. In this review, we summarize and discuss recent epigenetic studies of SLE and suggest a personalized approach to the dissection of disease onset and therapy or precision medicine. We speculate that in the future, precision medicine based on epigenetic and genetic information could help guide more effective targeted therapeutic intervention.

The Clinical Relevance of IL-17-Producing CD4+CD161+ Cell and Its Subpopulations in Primary Sjögren's Syndrome

Objective. Th17 cells have been demonstrated to play an important role in the onset and development of primary Sjögren's syndrome (pSS). In this study, we evaluated the expansion and clinical significance of circulating CD4+CD161+ T cell and its “effector” (CD4+CD25−CD161+ T cell) and “regulatory” (CD4+CD25+CD161+ T cell) subpopulations. Methods. Fifty-eight pSS patients and 16 healthy controls (HCs) were recruited in our study. The cell populations and intracellular IL-17 expression were analyzed by flow cytometry. The disease activity was evaluated by the EULAR-SS Disease Activity Index (ESSDAI). Autoantibodies were measured by ELISA or indirect immunofluorescence assay. Results. The CD161+ T cell fractions showed higher proportions of IL-17-producing cells. The frequencies of the overall CD4+CD161+ T cell population and its effector subset were positively correlated with disease activity parameters and more severe disease manifestations. A significant elevation of the CD4+CD25+CD161+ T cell subpopulation was observed in the peripheral blood of pSS patients compared to HCs and this subset showed decreased regulatory functions compared with the CD4+CD25+CD161− population. Conclusion. Circulating CD4+CD161+ T cell populations associated with pSS disease activity and severity. These cells might be involved in the development of pSS and could be potential therapeutic targets in the treatment of pSS.

T Regulatory and T Helper 17 Cells in Primary Sjögren's Syndrome: Facts and Perspectives

Historically, primary Sjögren's syndrome (pSS) was thought to be a T helper (h) 1 driven disease due to the predominance of CD4(+)T lymphocytes and their products in target organs and peripheral blood of patients. In the last decades, the identification of a number of T cell subsets, including Th17, T regulatory (Treg), and follicular helper T cells, challenged this long-standing paradigm and prompted to identify their role in pSS pathogenesis. In addition the impact of abnormal proinflammatory cytokine production, such as IL-6, IL-17, IL-22, and IL-23, has also attracted considerable attention. However, although several studies have been carried out in experimental models and patients with pSS, many aspects concerning the role of Treg cells and IL-17/Th17 cell system in pSS pathogenesis are not fully elucidated. In particular, the role played by different IL-17-producing T cell subsets as well as the effects of pharmacological therapies on Treg/Th17 cell balance represents an intriguing issue. The aim of this review article is to provide an overview of current knowledge on Treg cells and IL-17-producing T cells in pSS pathogenesis. We believe that these insights into pSS pathogenesis may provide the basis for successful therapeutic intervention in this disease.

Sjögren's syndrome: an update on epidemiology and current insights on pathophysiology

Primary Sjögren's syndrome (pSS) is an autoimmune chronic inflammatory disorder affecting 0.2% to 3.0% of the population, with a 9:1 female to male ratio. Features are oral and ocular dryness, local and systemic autoantibody production, and progressive focal mononuclear cell infiltration in the affected salivary and lacrimal glands. Lymphoma is the most severe complication of pSS, occurring in 4% to 5% of patients. Genetic studies identified an association with HLA and susceptibility genes in cytokine genes and genes involved in B-cell differentiation. Genetic variations may help explain why disease manifestations differ among patients and supports the hypothesis of certain distinct disease phenotypes.

Class I and II histone deacetylase inhibition by ITF2357 reduces SLE pathogenesis in vivo

We sought to determine if a specific class I and II HDAC inhibitor (ITF2357) was able to decrease disease in lupus-prone NZB/W mice through regulation of T cell profiles. From 22 to 38 weeks-of-age, NZB/W and non-lupus NZW mice were treated with ITF2357 (5 mg/kg or 10 mg/kg), or vehicle control. Body weight and proteinuria were measured every 2 weeks, while sera anti-dsDNA and cytokine levels were measured every 4 weeks. Kidney disease was determined by sera IgG levels, immune complex deposition, and renal pathology. T lymphocyte profiles were assessed using flow cytometric analyses. Our results showed that NZB/W mice treated with the 10 mg/kgof ITF2357 had decreased renal disease and inflammatory cytokines in the sera. Treatment with ITF2357 decreased the Th17 phenotype while increasing the percentage of Tregs as well as Foxp3 acetylation. These results suggest that specific HDAC inhibition may decrease disease by altering T cell differentiation and acetylation.

Correlations between psoriasis and inflammatory bowel diseases

For a long time the relationship between inflammatory bowel diseases (IBDs) and psoriasis has been investigated by epidemiological studies. It is only starting from the 1990s that genetic and immunological aspects have been focused on. Psoriasis and IBD are strictly related inflammatory diseases. Skin and bowel represent, at the same time, barrier and connection between the inner and the outer sides of the body. The most important genetic correlations involve the chromosomal loci 6p22, 16q, 1p31, and 5q33 which map several genes involved in innate and adaptive immunity. The genetic background represents the substrate to the common immune processes involved in psoriasis and IBD. In the past, psoriasis and IBD were considered Th1-related disorders. Nowadays the role of new T cells populations has been highlighted. A key role is played by Th17 and T-regs cells as by the balance between these two cells types. New cytokines and T cells populations, as IL-17A, IL-22, and Th22 cells, could play an important pathogenetic role in psoriasis and IBD. The therapeutic overlaps further support the hypothesis of a common pathogenesis.

STIM1 and STIM2 protein deficiency in T lymphocytes underlies development of the exocrine gland autoimmune disease, Sjogren's syndrome

Primary Sjögren's Syndrome (pSS) is an autoimmune disease involving salivary and other exocrine glands that leads to progressive lymphocytic infiltration into the gland, tissue damage, and secretory defects. The mechanism underlying this disease remains poorly understood. Here we report that mice with T-cell-targeted deletion of Stromal Interaction Molecule (STIM) 1 and STIM2 [double-knockout (DKO)] mice develop spontaneous and severe pSS-like autoimmune disease, displaying major hallmarks of the disease. In DKO mice, diffuse lymphocytic infiltration was seen in submandibular glands, a major target of pSS, by age 6 wk, progressing to severe inflammation by age 12 wk. Sjögren's syndrome-specific autoantibodies (SSA/Ro and SSB/La) were detected in the serum, and progressive salivary gland destruction and loss of fluid secretion were also seen. Importantly, we report that peripheral blood mononuclear cells as well as lymphocytic infiltrates in submandibular glands from patients with pSS demonstrated significant reductions in STIM1 and STIM2 proteins. Store-operated calcium entry was also reduced in peripheral blood mononuclear cells from pSS patients compared with those from healthy controls. Thus, deficiency of STIM1 and STIM2 proteins in T cells, and consequent defects in Ca(2+) signaling, are associated with salivary gland autoimmunopathy in DKO mice and pSS patients. These data reveal a previously unreported link between STIM1 and STIM2 proteins and pSS.

Immune regulation and B-cell depletion therapy in patients with primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is an autoimmune exocrinopathy characterized by chronic inflammation and destruction of the salivary and lacrimal glands. B- and T- lymphocyte infiltrations in the salivary glands with development of germinal center-like structures are characteristic for pSS. Overexpression of soluble factors, such as interferon α (IFNα) and B-cell activating factor (BAFF), are supposed to be important factors in the initiation and continuation of this disorder. The efficacy and success of B-cell depleting therapy in reducing disease activity in pSS patients for about six to nine months supports the notion that B-cells are major key players in disease manifestation of pSS. In addition to B-cells, also Th-cells (mainly Th17) seem to be involved in the pathogenetic process. In this review, we will discuss recent research findings regarding the cytokines IFNα and BAFF as wells as the role of B- and T-cells in pSS. Emphasis will be put on the impact of B-cell depletion therapy as well as on the presumed impact of therapies aimed for targeting BAFF, either as a sole modality or as a combined treatment with B-cell depletion.

CD4+CD25+ regulatory T cells in systemic sclerosis and other rheumatic diseases

Systemic sclerosis (SSc) is a generalized connective tissue disorder, characterized by a wide spectrum of microvascular and immunological abnormalities, leading to a progressive thickening and fibrosis of the skin and other organs, such as the lungs, GI tract, heart and kidneys. SSc is thought to be an autoimmune disease owing to the presence of high affinity antibodies and possible clinical overlap with other autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. Autoimmune diseases arise because of a breakdown in immunological self tolerance. Self tolerance is maintained via multiple regulatory mechanisms within the immune system, including the thymic deletion of self-reactive T cells and mechanisms of peripheral tolerance. In recent years, the presence of CD4(+)CD25(+)FOXP3(+) Tregs has been identified as a major mechanism of peripheral tolerance, and accumulating evidence indicates that alterations in Treg frequencies and/or function may contribute to autoimmune diseases. Here, we will review recent data on the percentage, function and phenotype of CD4(+)CD25(+) Tregs in rheumatic disease, and discuss how recent developments may guide research in this area in SSc.

[Sensory neuronopathy of Sjögren's syndrome. A diagnostic challenge]

Sjögren's syndrome is an important differential diagnosis in patients with sensory neuronopathy because immunosuppressive therapy may prevent progressive degeneration of sensory fibres, ganglions and axons. Due to the challenges in the diagnostic process the diagnostic criteria have repeatedly changed over the past few years. In patients with negative antibodies (SSA, SSB antibodies) biopsy of the salivary glands of the lip and the parotid gland can be useful to diagnose Sjögren's syndrome. We report on four patients in whom biopsy of the salivary gland was helpful in establishing the diagnosis of Sjögren's syndrome and consequently immunosuppressive therapy was initiated. One of these patients suffered from hypersalivation. This was probably due to denervation hypersensitivity. To our knowledge this has not been reported yet.

Disturbance of cytokine networks in Sjögren's syndrome

The difficulty in predicting the consequences of interactions between different cytokine networks has increased with the expansion of the T helper (Th) cell universe and the discovery of numerous B lymphocyte-derived cytokines. Consequently, it is now difficult to conceptualize a straightforward view of the contribution of these disturbances to the pathogenesis of primary Sjögren's syndrome (SS). Th1 cells, which produce interferon-γ and IL-2, and Th17 cells, which make IL-17 and TNF-α, have been cast in the leading roles of the play. However, the complex role of T-cell subsets in SS is accentuated by the reciprocal effects of Th17 cells and regulatory T cells found in salivary glands of SS patients. Furthermore, B lymphocyte polarization into type-1 B effector (Be1) and Be2 cells and B-cell modulating factors of the TNF family, most notably the B-cell-activating factor (BAFF), and their prominent role in SS are additional complicating factors. Whereas Th17 cells orchestrate autoreactive germinal centers, local BAFF would repress the generation of Th17 cells. Such new insights into interconnected cytokines in primary SS may lead to new treatments for these patients.

Human FoxP3+ regulatory T cells in systemic autoimmune diseases

Since the characterization of CD4(+)CD25(+) regulatory T (Treg) cells in mice, significant progress has been made in the definitions of the phenotype and the function of human Treg cells in health and in pathological conditions. Recent advances in the field leading to a better molecular definition of Treg subsets in humans and the description of the dynamics of differentiation of Treg cells should bring new insights in the understanding of human chronic systemic autoimmune diseases. How Treg cells are compromised in these diseases is a challenging issue because the elucidation of the mechanisms leading to such anomaly might lead to promising novel therapeutic approaches.

FoxP3+ CD4+ T cells in systemic autoimmune diseases: the delicate balance between true regulatory T cells and effector Th-17 cells

Breakdown of tolerance is a hallmark of autoimmune diseases. Over the past 10 years, there has been increased interest in the role of FoxP3(+) regulatory T cells (T(Regs)) in maintaining peripheral tolerance. Dysfunction of these cells is considered to play a major role in the development of autoimmune diseases. Besides their suppressive function, a fraction of these cells has the capacity to differentiate into IL-17-producing cells (Th-17), a phenomenon associated with autoimmune inflammation. The revealed plasticity of T(Regs), therefore, has obvious implications when designing therapeutic strategies for restoring tolerance in autoimmune diseases using T(Regs). In this review, we discuss development, classification, molecular characterization and mechanisms of suppression by T(Regs). In addition, we describe recent data on their potential conversion into Th-17 cells in human systemic autoimmune diseases. We also outline a new strategy for T(Reg)-based therapy via isolation, expansion and re-infusion of highly pure FoxP3(+) T(Regs) free of contaminating effector T cells.

The histone deacetylase inhibitor, trichostatin A, inhibits the development of 2,4-dinitrofluorobenzene-induced dermatitis in NC/Nga mice

Repetitive skin contact with a chemical hapten like 2,4-dinitrofluorobenzene (DNFB) evokes an atopic dermatitis (AD)-like dermatitis reaction in NC/Nga mice maintained under specific pathogen-free (SPF) conditions. The histone deacetylase (HDAC) inhibitor, trichostatin A (TSA), modulates the expression of several genes by inhibiting the activity of HDACs. Furthermore, TSA has been reported to suppress inflammatory cytokine expression and to induce T cell-suppression by increasing regulatory T cell (T reg cell) numbers. In addition, histone deacetylase inhibitors (HDACi) are currently undergoing clinical trials for the treatment of inflammatory disorders. In the present study, we examined whether treatment with TSA suppresses AD-like skin lesions in NC/Nga mice treated with DNFB under SPF conditions. Intraperitoneal (i.p.) administration of TSA to DNFB-treated NC/Nga mice was found to inhibit ear thickness increases and the skin lesions induced by DNFB. Furthermore, IL-4 production by CD4+ T cells from the lymph nodes of DNFB-treated NC/Nga mice was significantly inhibited by TSA, although levels of IFN-γ were not. Flow cytometric analysis of lymphocytes showed an increase in CD4+ CD25+ T cell proportions in mice given TSA-i.p. These findings suggest that TSA suppresses the development of AD-like dermatitis in DNFB-treated NC/Nga mice by reducing IL-4 production and increasing the T reg cell population.

[Regulatory T cells and systemic autoimmune diseases: systemic lupus erythematosus, rheumatoid arthritis, primary Sjögren's syndrome]

Regulatory/suppressor T cells (Tregs) maintain immunologic homeostasis and prevent autoimmunity. They are the guardians of dominant tolerance. Recent research reveals quantitative and/or functional defect of Tregs in systemic autoimmune diseases. In this article, past and recent studies of Tregs in human systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and primary Sjögren's syndrome (pGSS) are reviewed. Most studies report that Tregs are decreased in peripheral blood of subjects with active SLE. A population of CD4+CD25-Foxp3+ is specifically described in SLE. Tregs functions are still discussed. Tregs counts in peripheral blood of RA patients vary across studies. Enrichment of synovial fluid in Tregs contrasts with inflammation. Tregs suppressive effects are altered in vivo in RA secondary to proinflammatory cytokines environment and resistance of effector T cells to Tregs. In pGSS, the conflicting place of Tregs in the balance prevention of autoimmunity/antitumor immunity is unspecified. Immunosuppressive treatments, like corticosteroids and anti-TNF, modulate Tregs cells population. There is increasing interest in the use of Tregs as a biological therapy to preserve and restore tolerance to self-antigen. However, difficulties to characterize these lymphocytes and controversies in the results of studies refrain their use in current clinical practice.

The numbers of Foxp3 + Treg cells are positively correlated with higher grade of infiltration at the salivary glands in primary Sjogren's syndrome

This study was designed to investigate whether Foxp3( +) regulatory T (Treg) cells play a role in the histopathologic changes of primary Sjögren's Syndrome (pSS) and to evaluate other factors possibly associated with Foxp3(+) Treg cells in pSS patients. The number of FoxP3-expressing T cells in peripheral blood (PB) of 39 patients with pSS, 40 patients with rheumatoid arthritis (RA), and 28 healthy controls was measured by flow-cytometer analysis. FoxP3-expressing CD4(+)CD25(+) Treg cells were analyzed in minor salivary gland (SG) tissues of 39 pSS patients. Histopathologic changes were examined by light microscopy according to Chisholm's classification. Immunohistochemistry and immunofluorescence were performed to assess the Foxp3(+) Treg in SG biopsy specim-ens. The numbers of CD4(+) T cells and FoxP3-expressing CD4(+) T cells in PB were similar in all groups. Expression of CD25 on CD4(+) T cells in PB of patients with pSS and RA was significantly higher than in healthy controls, especially for RA patients. Immunohistochemistry and immunofluorescence showed that FoxP3(+) Treg were enriched in the SGs of pSS patients, with a positive correlation between the increase in FoxP3(+) Treg in SG and the Chisholm score in pSS (p < 0.001, r = +0.605). The increase of FoxP3( +) Treg cells in the SGs of pSS patients, which is correlated with gland infiltration, suggests that natural regulatory T cells play an important role in the pathogenesis of pSS. Further studies are required to explore the mechanisms that mediate the relationship between Treg and the pathogenesis of pSS.

Cells with regulatory function of the innate and adaptive immune system in primary Sjögren's syndrome

The aim of the present study was to describe subsets of cells with regulatory properties in primary Sjögren's syndrome (pSS), and to correlate these cell populations with clinical symptoms. Among the 32 investigated patients, 23 had extraglandular manifestations (EGMs), while nine had only glandular symptoms. Twenty healthy individuals served as controls. The percentages of natural killer (NK), natural killer T cells (NK T), interleukin (IL)-10 producing T regulatory type 1 (Tr1) cells and CD4(+)CD25(+) regulatory T cells (T(reg)) cells were determined by flow cytometry and serum cytokine levels of IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma were evaluated by enzyme-linked immunosorbent assay (ELISA). Functional tests were carried out to assess the suppressor properties of T(reg) cells in patients and controls. Peripheral NK, NK T and Tr1 cell percentages were elevated in pSS, while CD4(+)CD25(+) T(reg) cells showed reduced frequencies in patients compared to controls. In pSS, elevated percentages of NK T, Tr1 and CD4(+)CD25(+) T(reg) cells were observed in patients with EGMs, when compared to patients with sicca symptoms only. CD4(+)CD25(+) T(reg) cell percentages showed a negative correlation with sialometry values. The in vitro functional assay demonstrated lower suppression activity of CD4(+)CD25(+) T(reg) cells in patients compared to controls. Serum IL-6 and TNF-alpha levels were elevated, while IL-10 was decreased in patients compared to controls. Negative correlation was found between IL-10 levels and the percentages of Tr1 cells. Changes in the investigated subsets of regulatory cells in pSS may contribute to the development and progression of the disease.

Human T regulatory cell therapy: take a billion or so and call me in the morning

Immune system regulation is of paramount importance to host survival. In settings of autoimmunity and alloimmunity, control is lost, resulting in injury to vital organs and tissues. Naturally occurring, thymic-derived T regulatory (Treg) cells that express CD4, CD25, and the forkhead box protein 3 (FoxP3) are potent suppressors of these adverse immune responses. Preclinical studies have shown that either freshly isolated or ex vivo expanded Treg cells can prevent both local and systemic organ and tissue destruction. Although promising, human Treg cell infusion therapy has heretofore been difficult to implement in the clinic, and relatively few clinical trials have been initiated. This review will focus on the preclinical models that provide the rationale for current trials and it will address both the challenges and opportunities in human Treg cell therapy.