Resistance to IL-10 inhibition of interferon gamma production and expression of suppressor of cytokine signaling 1 in CD4+ T cells from patients with rheumatoid arthritis

Defining Human Regulatory T Cells beyond FOXP3: The Need to Combine Phenotype with Function

Regulatory T cells (Tregs) are essential to maintain immune homeostasis by promoting self-tolerance. Reduced Treg numbers or functionality can lead to a loss of tolerance, increasing the risk of developing autoimmune diseases. An overwhelming variety of human Tregs has been described, based on either specific phenotype, tissue compartment, or pathological condition, yet the bulk of the literature only addresses CD25-positive and CD127-negative cells, coined by naturally occurring Tregs (nTregs), most of which express the transcription factor Forkhead box protein 3 (FOXP3). While the discovery of FOXP3 was seminal to understanding the origin and biology of nTregs, there is evidence in humans that not all T cells expressing FOXP3 are regulatory, and that not all Tregs express FOXP3. Namely, the activation of human T cells induces the transient expression of FOXP3, irrespective of whether they are regulatory or inflammatory effectors, while some induced T cells that may be broadly defined as Tregs (e.g., Tr1 cells) typically lack demethylation and do not express FOXP3. Furthermore, it is unknown whether and how many nTregs exist without FOXP3 expression. Several other candidate regulatory molecules, such as GITR, Lag-3, GARP, GPA33, Helios, and Neuropilin, have been identified but subsequently discarded as Treg-specific markers. Multiparametric analyses have uncovered a plethora of Treg phenotypes, and neither single markers nor combinations thereof can define all and only Tregs. To date, only the functional capacity to inhibit immune responses defines a Treg and distinguishes Tregs from inflammatory T cells (Teffs) in humans. This review revisits current knowledge of the Treg universe with respect to their heterogeneity in phenotype and function. We propose that it is unavoidable to characterize human Tregs by their phenotype in combination with their function, since phenotype alone does not unambiguously define Tregs. There is an unmet need to align the expression of specific markers or combinations thereof with a particular suppressive function to coin functional Treg entities and categorize Treg diversity.

Cell-based therapies for the treatment of rheumatoid arthritis

Autoimmune diseases, including rheumatoid arthritis that is the most prevalent rheumatic autoimmune disorder, affect autologous connective tissues caused by the breakdown of the self-tolerance mechanisms of the immune system. During the last two decades, cell-based therapy, including stem cells and none-stem cells has been increasingly considered as a therapeutic option in various diseases. This is partly due to the unique properties of stem cells that divide and differentiate from the specialized cells in the damaged tissue. Moreover, stem cells and none-stem cells, impose immunomodulatory properties affecting the diseases caused by immunological abnormalities such as rheumatic autoimmune disorders. In the present review, the efficacy of cell-based therapy with four main types of stem cells, including mesenchymal stem cells, hematopoietic stem cells, embryonic stem cells, and human amniotic membrane cells, as well as none-stem cells, including regulatory T cells, chimeric antigen receptor T cells, and tolerogenic dendritic cells will be evaluated. Moreover, other related issues, including safety, changes in immunological parameters, suitable choice of stem cell and none-stem cell origin, conditioning regimen, limitations, and complications will be discussed.

Assessment of Expression of SOCS Genes in Acquired Immune-Mediated Polyneuropathies

Acquired immune-mediated polyneuropathies are classified to some subtypes among them are acute and chronic inflammatory demyelinating polyradiculoneuropathies (AIDP and CIDP). These two conditions share some common signs and underlying mechanisms. Based on the roles of Suppressor of cytokine signaling (SOCS) genes in the modulation of immune system reactions, these genes might be involved in the pathogenesis of these conditions. We evaluated expression of SOCS1-3 and SOCS5 genes in the leukocytes of 32 cases of CIDP, 19 cases of AIDP and 40 age- and sex-matched controls using real time PCR method. The Bayesian regression model was used to estimate differences in mean values of genes expressions between cases and control group. Expression levels of SOCS1 and SOCS2 were significantly lower in male patients compared with controls. This sex-specific pattern was also observed for SOCS3 down-regulation. Based on the area under curve values in Receiver Operating Characteristics (ROC) curve, diagnostic powers of SOCS1, SOCS2, SOCS3 and SOCS5 genes in the mentioned disorder were 0.61, 0.73, 0.68 and 0.58, respectively. Expression of none of genes was correlated with age of enrolled cases. The current study shows evidences for participation of SOCS genes in the pathophysiology of acquired immune-mediated polyneuropathies.

Suppressors of cytokine signaling (SOCS) proteins in inflammatory bone disorders

Suppressor of cytokine signaling (SOCS) proteins are significant regulators of cellular immune responses. Therefore, the role of SOCS in bone-inflammatory disorders, including arthritis and periodontitis, has been investigated in experimental and clinical conditions. Recent evidence shows that SOCS proteins are expressed in major bone-related cells, including osteoblasts, osteoclasts, chondrocytes and synoviocytes, although their direct role in these cells is not fully described. These signaling molecules, especially SOCS1, 2 and 3, were shown to play critical roles in the control of bone resorption associated to inflammation. This review focuses on the involvement of SOCS proteins in inflammatory bone remodeling, including their direct and indirect role in the control of osteoclast hyperactivation, during arthritis and periodontitis. The description of the roles of SOCS proteins in inflammatory bone diseases highlights the pathways involved in the pathophysiology of these conditions and, thus, may contribute to the development and improvement of potential therapeutic interventions.

Identification of a Human SOCS1 Polymorphism That Predicts Rheumatoid Arthritis Severity

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by an autoimmune response in the joints and an exacerbation of cytokine responses. A minority of patients with RA experience spontaneous remission, but most will show moderate/high disease activity, with aggressive joint damage and multiple systemic manifestations. There is thus is a great need to identify prognostic biomarkers for disease risk to improve diagnosis and prognosis, and to inform on the most appropriate therapy. Here we focused on suppressor of cytokine signaling 1 (SOCS1), a physiological negative regulator of cytokines that modulates cell activation. Using four independent cohorts of patients with arthritis, we characterized the correlation between SOCS1 mRNA levels and clinical outcome. We found a significant inverse correlation between SOCS1 mRNA expression and disease activity throughout the follow-up of patients with RA. Lower baseline SOCS1 levels were associated with poorer disease control in response to methotrexate and other conventional synthetic disease-modifying anti-rheumatic drugs in early arthritis, and to rituximab in established (active) RA. Moreover, we identified several single nucleotide polymorphisms in the SOCS1 gene that correlated with SOCS1 mRNA expression, and that might identify those patients with early arthritis that fulfill RA classification criteria. One of them, rs4780355, is in linkage disequilibrium with a microsatellite (TTTTC)₃₋₅, mapped 0.9 kb downstream of the SNP, and correlated with reduced SOCS1 expression in vitro. Overall, our data support the association between SOCS1 expression and disease progression, disease severity and response to treatment in RA. These observations underlie the relevance of SOCS1 mRNA levels for stratifying patients prognostically and guiding therapeutic decisions.

IL‑1β increases the expression of inflammatory factors in synovial fluid‑derived fibroblast‑like synoviocytes via activation of the NF‑κB‑mediated ERK‑STAT1 signaling pathway

Interleukin (IL)-1β serves a crucial role in the progression of rheumatoid arthritis. Previous studies have indicated that the ERK/STAT1 signaling pathway may be involved in the inflammatory response in synovial fluid-derived fibroblast-like synoviocytes (sfd-FLSs). However, the molecular mechanisms underlying the pathological effects of the inflammatory factors induced by IL-1β in sfd-FLSs remain unclear. The aim of the present study was to investigate the IL-1β-mediated signaling pathways involved in the expression of inflammatory factors in sfd-FLSs and in a rat model of rheumatoid arthritis. Reverse transcription-quantitative PCR, western blotting, and immunohistochemistry were used to analyze the role of IL-1β in the rat model of rheumatoid arthritis. The results suggested that IL-1β administration exacerbated rheumatoid arthritis, bone injury and increased the expression levels of inflammatory factors, such as IL-17 and tumor necrosis factor α (TNF-α), whereas treatment with anti-IL-1β exhibited opposite effects. In vitro experiments in sfd-FLSs further suggested that treatment with IL-1β influenced the expression levels of various inflammatory factors. In specific, IL-1β increased the expression of IL-17 and TNF-α, and decreased the expression of IL-6 and IL-10 in sfd-FLSs. Additionally, treatment with IL-1β increased the mRNA expression and protein phosphorylation of NF-κB, ERK and STAT1 in sfd-FLSs. Treatment with anti-IL-1β exhibited opposite effects on the expression levels of inflammatory factors and suppressed the NF-κB-mediated ERK-STAT1 signaling pathway activation in sfd-FLSs. Finally, treatment with a NF-κB inhibitor suppressed the effects of IL-1β, and NF-κB overexpression reversed the effects of anti-IL-1β on the expression levels of IL-17, TNF-α, NF-κB, ERK and STAT1. In conclusion, the present results demonstrated that treatment with IL-1β increased the expression levels of inflammatory factors in sfd-FLSs via the regulation of the NF-κB-mediated ERK/STAT1 signaling pathway in a rat model of rheumatoid arthritis. Therefore, the NF-κB/ERK/STAT1 signaling pathway may represent a potential target for the development of novel treatments for rheumatoid arthritis.

The role of α7nAChR in controlling the anti-inflammatory/anti-arthritic action of galantamine

OBJECTIVE

The evolution of the "cholinergic anti-inflammatory pathway" and the fact that the α 7 subunit of the nicotinic acetylcholine receptor (α7nAChR) is present in the spleen, joint and on the surface of lymphocytes, opened up the prospective in this study of targeting the α7nAChR by the anticholinesterase and cholinergic drug, galantamine, to control inflammation in rheumatoid arthritis (RA).

METHODS

Twelve-adjuvant arthritic rats were exposed to the selective α7nAChR blocker methylcaconitine citrate 15 min before galantamine treatment. As control, six adjuvant arthritic rats were treated with galantamine and six others were untreated. After five days TNF-α levels were assessed in spleen and joints, while reduced glutathione was measured in blood and joint tissue. In the second part, magnetically sorted CD4 + T cells from peripheral blood mononuclear cells of RA patients and healthy donors were used to sort CD4 + CD25 - primary T cells (Tresp) and CD4 + CD25 + CD127low Tregs. The suppressive function of Tregs was investigated after incubation with galantamine using flow cytometry. Cell culture supernatants were analyzed for TNF-α and IL-10 levels after three days incubation period of Tregs with Tresp. The effect of galantamine on Tregs was then blocked by α-Bungarotoxin and the same assay has been repeated.

RESULTS & CONCLUSION

Selective α7nAChR blockade interrupted the anti-inflammatory effect of galantamine in the spleen and joints of arthritic rats. In healthy donors, galantamine could strengthen the suppressive activity of Tregs; while in RA patients it did not modulate the function of Tregs significantly. Further studies are necessary to investigate whether modulation of the cholinergic nervous system, especially α7nAChR, could have impact on the disturbed immune system in RA, which may open up a new treatment option of autoimmune diseases.

Suppressor of cytokine signaling-1 gene therapy induces potent antitumor effect in patient-derived esophageal squamous cell carcinoma xenograft mice

Chronic inflammation is involved in cancer growth in esophageal squamous cell carcinoma (ESCC), which is a highly refractory cancer with poor prognosis. This study investigated the antitumor effect and mechanisms of SOCS1 gene therapy for ESCC. Patients with ESCC showed epigenetics silencing of SOCS1 gene by methylation in the CpG islands. We infected 10 ESCC cells with an adenovirus-expressing SOCS1 (AdSOCS1) to examine the antitumor effect and mechanism of SOCS1 overexpression. SOCS1 overexpression markedly decreased the proliferation of all ESCC cell lines and induced apoptosis. Also, SOCS1 inhibited the proliferation of ESCC cells via multiple signaling pathways including Janus kinase (JAK)/signal transducer and activator of transcription (STAT) and focal adhesion kinase (FAK)/p44/42 mitogen-activated protein kinase (p44/42 MAPK). Additionally, we established two xenograft mouse models in which TE14 ESCC cells or ESCC patient-derived tissues (PDX) were subcutaneously implanted. Mice were intra-tumorally injected with AdSOCS1 or control adenovirus vector (AdLacZ). In mice, tumor volumes and tumor weights were significantly lower in mice treated with AdSOCS1 than that with AdLacZ as similar mechanism to the in vitro findings. The Ki-67 index of tumors treated with AdSOCS1 was significantly lower than that with AdLacZ, and SOCS1 gene therapy induced apoptosis. These findings demonstrated that overexpression of SOCS1 has a potent antitumor effect against ESCC both in vitro and in vivo including PDX mice. SOCS1 gene therapy may be a promising approach for the treatment of ESCC.

Xuebijing injection alleviates cytokine-induced inflammatory liver injury in CLP-induced septic rats through induction of suppressor of cytokine signaling 1

Dysregulation of inflammatory cytokines and liver injury are associated with the pathogenesis of sepsis. Xuebijing injection, a Chinese herbal medicine, has been used in the treatment of sepsis and can contribute to the improvement of patients' health. However, the underlying molecular mechanisms are not yet clearly illuminated. In the present study, a septic rat model with liver injury was established by the cecal ligation and puncture (CLP) method. Histological alterations to the liver, activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), levels of inflammatory cytokine secretion and the expression of suppressors of cytokine signaling 1 (SOCS-1) in the CLP model rats with and without Xuebijing treatment were determined. The results showed that Xuebijing injection ameliorated the pathological changes in liver tissues caused by sepsis, and reduced the sepsis-induced elevation in serum ALT and AST levels. Furthermore, Xuebijing injection markedly downregulated the expression of tumor necrosis factor α and interleukin (IL)-6, and upregulated the expression of IL-10. More importantly, SOCS1 expression levels at the protein and mRNA levels were further increased by Xuebijing. These findings demonstrate that Xuebijing injection can significantly alleviate liver injury in CLP-induced septic rats via the regulation of inflammatory cytokine secretion and the promotion of SOCS1 expression. The protective effects of Xuebijing injection suggest its therapeutic potential in the treatment of CLP-induced liver injury.

Seeking balance: Potentiation and inhibition of multiple sclerosis autoimmune responses by IL-6 and IL-10

The cytokines IL-6 and IL-10 are produced by cells of the adaptive and innate arms of the immune system and they appear to play key roles in genetically diverse autoimmune diseases such as relapsing remitting multiple sclerosis (MS), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Whereas previous intense investigations focused on the generation of autoantibodies and their contribution to immune-mediated pathogenesis in these diseases; more recent attention has focused on the roles of cytokines such as IL-6 and IL-10. In response to pathogens, antigen presenting cells (APC), including B cells, produce IL-6 and IL-10 in order to up-or down-regulate immune cell activation and effector responses. Evidence of elevated levels of the proinflammatory cytokine IL-6 has been routinely observed during inflammatory responses and in a number of autoimmune diseases. Our recent studies suggest that MS peripheral blood B cells secrete higher quantities of IL-6 and less IL-10 than B cells from healthy controls. Persistent production of IL-6, in turn, contributes to T cell expansion and the functional hyperactivity of APC such as MS B cells. Altered B cell activity can have a profound impact on resultant T cell effector functions. Enhanced signaling through the IL-6 receptor can effectively inhibit cytolytic activity, induce T cell resistance to IL-10-mediated immunosuppression and increase skewing of autoreactive T cells to a pathogenic Th17 phenotype. Our recent findings and studies by others support a role for the indirect attenuation of B cell responses by Glatiramer acetate (GA) therapy. Our studies suggest that GA therapy temporarily permits homeostatic regulatory mechanisms to be reinstated. Future studies of mechanisms underlying dysregulated B cell cytokine production could lead to the identification of novel targets for improved immunoregulatory therapies for autoimmune diseases.

Engulfment of activated apoptotic cells abolishes TGF-β-mediated immunoregulation via the induction of IL-6

Phagocytosis of apoptotic cells (ACs) is usually a potent immunoregulatory signal but can also promote inflammation. In this article, we show that administration of apoptotic dendritic cells (DCs) inhibited inflammation in vivo through increasing production of TGF-β from intrinsic DCs and B cells. However, ACs derived from LPS-activated DCs failed to restrain inflammation because of a short-lived but marked IL-6 response, which abolished the increase in TGF-β. Inhibition of IL-6 restored the protective anti-inflammatory properties of aACs and the TGF-β response. DCs isolated from mice that had received resting but not activated ACs could transfer the suppression of inflammation to recipient mice. These transferred DCs stimulated B cell TGF-β production and relied on an intact B cell compartment to limit inflammation. These results highlight how the activation state of AC governs their ability to control inflammation through reciprocal regulation of IL-6 and TGF-β.

Content of IL-10 and CD4+CD210+ cells in mice with adjuvant arthritis before and after treatment with cryopreserved placental cells

We analyzed the serum level of IL-10, blood content of CD4+СD210+ cells, and expression of IL-10 receptors in adjuvant arthritis before and after treatment with native and cryopreserved placental cells. In animals with experimental adjuvant arthritis, a negative correlation was found between the index of arthritis and IL-10 concentration (r=-0.7; p=0.03); in addition, a considerable decrease in the content of CD4+СD210+ cells and changes in the expression of IL-10 receptors on cells of the lymph nodes and spleen were demonstrated. After administration of cryopreserved DMSO-protected placental cells (in contrast to administration of cryopreserved propanedioxysacharol-protected cell suspension), the content of CD4+СD210+ cells in the spleen of animals with experimental adjuvant arthritis returned to normal.

SOCS signaling in autoimmune diseases: molecular mechanisms and therapeutic implications

Suppressor of cytokine signaling (SOCS) proteins are mainly induced by various cytokines and have been described as classical inhibitors of cytokine signaling. SOCS signaling is involved in the regulation of immune cells, and recent findings suggest that SOCS proteins, especially SOCS1 and SOCS3, are often dysregulated in a wide variety of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, psoriasis, and multiple sclerosis. Recent studies suggest that SOCS signaling could be therapeutically targeted in various autoimmune diseases. In this review, we discuss recent studies on the role of SOCS proteins in the development and pathogenesis of autoimmune diseases, as well as their clinical implications.

Tolerogenic dendritic cell therapy for rheumatoid arthritis: where are we now?

Dendritic cells with tolerogenic function (tolDC) have become a promising immunotherapeutic tool for reinstating immune tolerance in rheumatoid arthritis (RA) and other autoimmune diseases. The concept underpinning tolDC therapy is that it specifically targets the pathogenic autoimmune response while leaving protective immunity intact. Findings from human in-vitro and mouse in-vivo studies have been translated into the development of clinical grade tolDC for the treatment of autoimmune disorders. Recently, two tolDC trials in RA and type I diabetes have been carried out and other trials are in progress or are imminent. In this review, we provide an update on tolDC therapy, in particular in relation to the treatment of RA, and discuss the challenges and the future perspectives of this new experimental immunotherapy.

Comparing the immunosuppressive potency of naïve marrow stromal cells and Notch-transfected marrow stromal cells

Background

SB623 cells are expanded from marrow stromal cells (MSCs) transfected with a Notch intracellular domain (NICD)-expressing plasmid. In stroke-induced animals, these cells reduce infarct size and promote functional recovery. SB623 cells resemble the parental MSCs with respect to morphology and cell surface markers despite having been in extended culture. MSCs are known to have immunosuppressive properties; whether long-term culture of MSCs impact their immunomodulatory activity has not been addressed.

Methods

To assess the possible senescent properties of SB623 cells, we performed cell cycle related assays and beta-galactosidase staining. To assess the immunomodulatory activity of these expanded NICD-transfected MSCs, we performed co-cultures of SB623 cells or MSCs with either enriched human T cells or monocytes and assessed cytokine production by flow cytometry. In addition, we monitored the immunosuppressive activity of SB623 cells in both allogenic and xenogenic mixed lymphocyte reaction (MLR).

Results

Compared to MSCs, we showed that a small number of senescent-like cells appear in each lot of SB623 cells. Nevertheless, we demonstrated that these cells suppress human T cell proliferation in both the allogeneic and xenogeneic mixed lymphocyte reaction (MLR) in a manner comparable to MSCs. IL-10 producing T cells were generated and monocyte-dendritic cell differentiation was dampened by co-culture with SB623 cells. Compared to the parental MSCs, SB623 cells appear to exert a greater inhibitory impact on the maturation of dendritic cells as demonstrated by a greater reduction in the surface expression of the co-stimulatory molecule, CD86.

Conclusion

The results demonstrated that the immunosuppressive activity of the expanded NICD-transfected MSCs is comparable to the parental MSCs, in spite of the appearance of a small number of senescent-like cells.

Negative regulation of cytokine signaling and immune responses by SOCS proteins

Immune and inflammatory systems are controlled by multiple cytokines, including interleukins and interferons. Many of these cytokines exert their biological functions through JAKs (Janus tyrosine kinases) and STAT (signal transduction and activators of transcription) transcription factors. CIS (cytokine-inducible SH2 (Src homology 2) protein) and SOCS (suppressor of cytokine signaling) are a family of intracellular proteins, several of which have emerged as key physiological regulators of cytokine-mediated homeostasis, including innate and adaptive immunity. In this review we focus on the molecular mechanism of the action of CIS/SOCS family proteins and their roles in immune regulation and inflammatory diseases including rheumatoid arthritis.