Interleukin-35-Producing CD8α+ Dendritic Cells Acquire a Tolerogenic State and Regulate T Cell Function

Upregulation of TCPTP in Macrophages Is Involved in IL-35 Mediated Attenuation of Experimental Colitis

Ulcerative colitis (UC) is a chronic intestinal inflammatory disease with complex etiology. Interleukin-35 (IL-35), as a cytokine with immunomodulatory function, has been shown to have therapeutic effects on UC, but its mechanism is not yet clear. Therefore, we constructed Pichia pastoris stably expressing IL-35 which enables the cytokines to reach the diseased mucosa, and explored whether upregulation of T-cell protein tyrosine phosphatase (TCPTP) in macrophages is involved in the mechanisms of IL-35-mediated attenuation of UC. After the successful construction of engineered bacteria expressing IL-35, a colitis model was successfully induced by giving BALB/c mice a solution containing 3% dextran sulfate sodium (DSS). Mice were treated with Pichia/IL-35, empty plasmid-transformed Pichia (Pichia/0), or PBS by gavage, respectively. The expression of TCPTP in macrophages (RAW264.7, BMDMs) and intestinal tissues after IL-35 treatment was detected. After administration of Pichia/IL-35, the mice showed significant improvement in weight loss, bloody stools, and shortened colon. Colon pathology also showed that the inflammatory condition of mice in the Pichia/IL-35 treatment group was alleviated. Notably, Pichia/IL-35 treatment not only increases local M2 macrophages but also decreases the expression of inflammatory cytokine IL-6 in the colon. With Pichia/IL-35 treatment, the proportion of M1 macrophages, Th17, and Th1 cells in mouse MLNs were markedly decreased, while Tregs were significantly increased. In vitro experiments, IL-35 significantly promoted the expression of TCPTP in macrophages stimulated with LPS. Similarly, the mice in the Pichia/IL-35 group also expressed more TCPTP than that of the untreated group and the Pichia/0 group.

Decreased Expression of IL-35 and Its Receptor Contributes to Impaired Megakaryopoiesis in the Pathogenesis of Immune Thrombocytopenia

Recent findings have shown that the level of interleukin-35 (IL-35) is abnormal in several autoimmune diseases. Nonetheless, whether IL-35 participates in the pathogenesis of immune thrombocytopenia (ITP) remains unclear. The current study investigates whether IL-35 modulates megakaryopoiesis. The results show that IL-35 receptors are progressively expressed on bone marrow megakaryocytes during the in vitro differentiation of CD34+ progenitors. IL-35 increases the number of megakaryocyte colony-forming units through the Akt pathway. The level of bone marrow IL-35 is reduced in ITP patients, and the decreased level of IL-35 may inhibit megakaryopoiesis. Then, the potential causes of decreased IL-35 in ITP patients are explored. The primary type of cell that secretes IL-35, known as IL-35-producing regulatory T cells (iTr35), is reduced in ITP patients. Bone marrow mesenchymal stem cells (MSCs) from ITP patients exhibit an impaired capability of inducing iTr35 due to enhanced apoptosis, which may contribute to the reduced level of bone marrow IL-35 in ITP patients. Iguratimod promotes megakaryocyte development and differentiation by elevating the expression of IL-35 receptors on megakaryocytes. Iguratimod improves response rates and reduces bleeding symptoms in corticosteroid-resistant ITP patients.

Revisiting regulatory T cells as modulators of innate immune response and inflammatory diseases

Regulatory T cells (Treg) are known to be critical for the maintenance of immune homeostasis by suppressing the activation of auto- or allo-reactive effector T cells through a diverse repertoire of molecular mechanisms. Accordingly, therapeutic strategies aimed at enhancing Treg numbers or potency in the setting of autoimmunity and allogeneic transplants have been energetically pursued and are beginning to yield some encouraging outcomes in early phase clinical trials. Less well recognized from a translational perspective, however, has been the mounting body of evidence that Treg directly modulate most aspects of innate immune response under a range of different acute and chronic disease conditions. Recognizing this aspect of Treg immune modulatory function provides a bridge for the application of Treg-based therapies to common medical conditions in which organ and tissue damage is mediated primarily by inflammation involving myeloid cells (mononuclear phagocytes, granulocytes) and innate lymphocytes (NK cells, NKT cells, γδ T cells and ILCs). In this review, we comprehensively summarize pre-clinical and human research that has revealed diverse modulatory effects of Treg and specific Treg subpopulations on the range of innate immune cell types. In each case, we emphasize the key mechanistic insights and the evidence that Treg interactions with innate immune effectors can have significant impacts on disease severity or treatment. Finally, we discuss the opportunities and challenges that exist for the application of Treg-based therapeutic interventions to three globally impactful, inflammatory conditions: type 2 diabetes and its end-organ complications, ischemia reperfusion injury and atherosclerosis.

Human IL-35 Inhibits the Bioactivity of IL-12 and Its Interaction with IL-12Rβ2

IL-35 is an immunosuppressive cytokine with roles in cancer, autoimmunity, and infectious disease. In the conventional model of IL-35 biology, the p35 and Ebi3 domains of this cytokine interact with IL-12Rβ2 and gp130, respectively, on the cell surface of regulatory T and regulatory B cells, triggering their suppression of Th cell activity. Here we use a human IL-12 bioactivity reporter cell line, protein binding assays, and primary human Th cells to demonstrate an additional mechanism by which IL-35 suppresses Th cell activity, wherein IL-35 directly inhibits the association of IL-12 with its surface receptor IL-12Rβ2 and downstream IL-12-dependent activities. IL-12 binding to the surface receptor IL-12Rβ1 was unaffected by IL-35. These data demonstrate that in addition to acting via regulatory T and regulatory B cells, human IL-35 can also directly suppress IL-12 bioactivity and its interaction with IL-12Rβ2.

Crosstalk between dendritic cells and regulatory T cells: Protective effect and therapeutic potential in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system related to autoimmunity and is characterized by demyelination, neuroinflammation, and neurodegeneration. Cell therapies mediated by dendritic cells (DCs) and regulatory T cells (Tregs) have gradually become accumulating focusing in MS, and the protective crosstalk mechanisms between DCs and Tregs provide the basis for the efficacy of treatment regimens. In MS and its animal model experimental autoimmune encephalomyelitis, DCs communicate with Tregs to form immune synapses and complete a variety of complex interactions to counteract the unbalanced immune tolerance. Through different co-stimulatory/inhibitory molecules, cytokines, and metabolic enzymes, DCs regulate the proliferation, differentiation and function of Tregs. On the other hand, Tregs inhibit the mature state and antigen presentation ability of DCs, ultimately improving immune tolerance. In this review, we summarized the pivotal immune targets in the interaction between DCs and Tregs, and elucidated the protective mechanisms of DC-Treg cell crosstalk in MS, finally interpreted the complex cell interplay in the manner of inhibitory feedback loops to explore novel therapeutic directions for MS.

Serum IL-35 levels is a new candidate biomarker of cancer-related cachexia in stage IV non-small cell lung cancer

Background

Cancer‐related cachexia is a major cause of treatment resistance and poor prognosis, which is characterized by anorexia and skeletal muscle depletion. To date, there have been no reports on the relationship between IL‐35 and cancer‐related cachexia in patients with stage IV non‐small cell lung cancer.

Methods

Serum IL‐35 levels in 86 patients with stage IV NSCLC were measured and statistically analyzed based on patients' clinicopathological parameters. Serum albumin levels, C‐reactive protein, and skeletal muscle index (SMI) of the patients were also determined. In vivo studies using a mouse model were also conducted by subcutaneously injecting immunodeficiency (SCID) mice with overexpressing IL‐35 cell lines and determining their daily food intake, bodyweight and muscle atrophy. Cachexia indicators were measured again after administering the mice with an anti‐IL35 neutralizing antibody.

Results

Patients with stage IV NSCLC had significantly higher serum IL‐35 levels than the healthy controls. Similarly, circulating IL‐35 levels were significantly higher in patients with cachexia than those without. The SMI values of patients with high serum IL‐35 levels were significantly lower than those with low serum IL‐35 levels. Mice subcutaneously injected with LLC PLV‐IL‐35 cell lines exhibited anorexia, weight loss, and muscle atrophy. Moreover, these symptoms were significantly reduced after administering the mice with an anti‐IL35 neutralizing antibody.

Conclusions

This study reveals that high serum IL‐35 expression is associated with non‐small cell lung cancer cachexia and skeletal muscle atrophy. These findings highlight its potential as a biomarker and therapeutic target for controlling cachexia of advanced lung cancer.

Interleukin-35: Structure, Function and Its Impact on Immune-Related Diseases

The balance between inflammatory and anti-inflammatory immune responses is maintained through immunoregulatory cell populations and immunosuppressive cytokines. Interleukin-35 (IL-35), an inhibitory cytokine that belongs to the IL-12 family, is capable of potently suppressing T cell proliferation and inducing IL-35-producing induced regulatory T cells (iTr35) to limit inflammatory responses. Over the past decade, a growing number of studies have indicated that IL-35 plays an important role in controlling immune-related disorders, including autoimmune diseases, infectious diseases, and cancer. In this review, we summarize the current knowledge about the biology of IL-35 and its contribution in different diseases, and we discuss the potential of and barriers to harnessing IL-35 as a clinical biomarker or immunotherapy.

The Mechanism of Interleukin-35 in Chronic Hepatitis B

Interleukin-35 (IL-35) is a newly identified inhibitory cytokine. It has recently been found to play an extremely important role in chronic hepatitis B disease, which makes it likely to be a target for new therapies for hepatitis B malady. IL-35 modulates a variety of immune mechanisms to cause persistent viral infections, such as affecting the ratio of helper T cells, reducing the activity of cytotoxic T cells, hindering the antigen presentation capacity for dendritic cells, and increasing the transcription level of hepatitis B virus. On the other hand, IL-35 can control the inflammation caused by hepatitis B liver injury. Therefore, to seek a breakthrough in curing hepatitis B disease, the contradictory part of IL-35 in the occurrence and development of this sickness is worthy of further discussion and research. This article will systematically review the biological effects of IL-35 and the specific mechanisms affecting the disease.

A myriad of roles of dendritic cells in atherosclerosis

Atherosclerosis is an inflammatory disease with break-down of homeostatic immune regulation of vascular tissues. As a critical initiator of host immunity, dendritic cells (DCs) have also been identified in the aorta of healthy individuals and atherosclerotic patients, whose roles in regulating arterial inflammation aroused great interest. Accumulating evidence has now pointed to the fundamental roles for DCs in every developmental stage of atherosclerosis due to their myriad of functions in immunity and tolerance induction, ranging from lipid uptake, efferocytosis and antigen presentation to pro- and anti-inflammatory cytokine or chemokine secretion. In this study we provide a timely summary of the published works in this field, and comprehensively discuss both the direct and indirect roles of DCs in atherogenesis. Understanding the pathogenic roles of DCs during the development of atherosclerosis in vascular tissues would certainly help to open therapeutic avenue to the treatment of cardiovascular diseases.

IL-35 Regulates the Function of Immune Cells in Tumor Microenvironment

Interleukin-35 (IL-35) is a heterodimeric cytokine composed of Epstein-Barr virus-induced gene 3 (EBI3) and IL-12p35 that has recently been shown to play diverse and important roles in the tumor microenvironment (TME). Owing to its immunosuppressive activity and ability to promote tumor growth and progression, IL-35 is widely recognized as a key mediator of TME status. Immune cells are key mediators of diverse tumor-related phenotypes, and immunosuppressive cytokines such as IL-35 can promote tumor growth and metastasis in TME. These influences should be considered together. Since tumor immunotherapy based on immune checkpoint blockade remains ineffective in many patients due to tumoral resistance, a new target or efficacy enhancing factor is urgently needed. Suppressing IL-35 production and activity has been demonstrated as an effective factor that inhibits tumor cells viability, and further investigation of this cytokine is warranted. However, the mechanistic basis for IL-35-mediated regulation of immune cells in the TME remains to be fully clarified. In the present review, we explore the roles of IL-35 in regulating immune cells within the TME. In addition, we highlight IL-35 as a specific immunological target and discuss its possible relevance in the context of immunotherapy. Lastly, we sought to summarize potential future research directions that may guide the advancement of current understanding regarding the role of this important cytokine as a regulator of oncogenesis.

Pathogenesis and Function of Interleukin-35 in Rheumatoid Arthritis

It is well known that RA (Rheumatoid arthritis) is an autoimmune disease characterized by multiple and symmetric arthropathy. The main pathological features of RA are synovial hyperplasia, angiogenesis, pannus formation, inflammatory cell infiltration, articular cartilage, bone destruction, and ultimately joint dysfunction, even deformity. IL-35 (Interleukin-35) is a new member of the IL-12 (Interleukin-12) family, which is an immunosuppressive and anti-inflammatory cytokine secreted mainly by Treg (T regulatory cells). There is evidence suggested that IL-35 can attenuate the progression of RA through influencing the immune and pathological process. It suggests that IL-35 played an important role in the pathogenesis of RA, and can be used as a potential target for the future treatment of RA. This review summarizes the recent advances of IL-35 in the pathological roles and the therapeutic potential roles in RA.

Paving the way towards an effective treatment for multiple sclerosis: advances in cell therapy

Multiple sclerosis (MS) is a leading cause of chronic neurological disability in young to middle-aged adults, affecting ~2.5 million people worldwide. Currently, most therapeutics for MS are systemic immunosuppressive or immunomodulatory drugs, but these drugs are unable to halt or reverse the disease and have the potential to cause serious adverse events. Hence, there is an urgent need for the development of next-generation treatments that, alone or in combination, stop the undesired autoimmune response and contribute to the restoration of homeostasis. This review analyzes current MS treatments as well as different cell-based therapies that have been proposed to restore homeostasis in MS patients (tolerogenic dendritic cells, regulatory T cells, mesenchymal stem cells, and vaccination with T cells). Data collected from preclinical studies performed in the experimental autoimmune encephalomyelitis (EAE) model of MS in animals, in vitro cultures of cells from MS patients and the initial results of phase I/II clinical trials are analyzed to better understand which parameters are relevant for obtaining an efficient cell-based therapy for MS.

IL10- and IL35-Secreting MutuDC Lines Act in Cooperation to Inhibit Memory T Cell Activation Through LAG-3 Expression

Dendritic cells (DCs) are professional antigen-presenting cells involved in the initiation of immune responses. We generated a tolerogenic DC (tolDC) line that constitutively secretes interleukin-10 (IL10-DCs), expressed lower levels of co-stimulatory and MHCII molecules upon stimulation, and induced antigen-specific proliferation of T cells. Vaccination with IL10-DCs combined with another tolDC line that secretes IL-35, reduced antigen-specific local inflammation in a delayed-type hypersensitivity assay independently on regulatory T cell differentiation. In an autoimmune model of rheumatoid arthritis, vaccination with the combined tolDCs after the onset of the disease impaired disease development and promoted recovery of mice. After stable memory was established, the tolDCs promoted CD4 downregulation and induced lymphocyte activation gene 3 (LAG-3) expression in reactivated memory T cells, reducing T cell activation. Taken together, our findings indicate the benefits of combining anti-inflammatory cytokines in an antigen-specific context to treat excessive inflammation when memory is already established.

IL-12 Family Cytokines in Cancer and Immunotherapy

The IL-12 family cytokines are a group of unique heterodimeric cytokines that include IL-12, IL-23, IL-27, IL-35 and, most recently, IL-39. Recent studies have solidified the importance of IL-12 cytokines in shaping innate and adaptive immune responses in cancer and identified multipronged roles for distinct IL-12 family members, ranging from effector to regulatory immune functions. These cytokines could serve as promising candidates for the development of immunomodulatory therapeutic approaches. Overall, IL-12 can be considered an effector cytokine and has been found to engage anti-tumor immunity by activating the effector Th1 response, which is required for the activation of cytotoxic T and NK cells and tumor clearance. IL-23 and IL-27 play dual roles in tumor immunity, as they can both activate effector immune responses and promote tumor growth by favoring immune suppression. IL-35 is a potent regulatory cytokine and plays a largely pro-tumorigenic role by inhibiting effector T cells. In this review, we summarize the recent findings on IL-12 family cytokines in the control of tumor growth with an emphasis primarily on immune regulation. We underscore the clinical implications for the use of these cytokines either in the setting of monotherapy or in combination with other conventional therapies for the more effective treatment of malignancies.

Probiotic extracts ameliorate nasal allergy by inducing interleukin-35-producing dendritic cells in mice

BACKGROUND

The therapeutic efficacy of allergic rhinitis (AR) needs to be improved. Probiotics have immunoregulatory functions. In this study we evaluated the effects of protein extracts of probiotics in the amelioration of AR.

METHODS

Extracts of Bifidobacterium infantis (EBI) were prepared by lysing the live probiotics. AR mice were developed to be used to evaluate the therapeutic efficacy of EBI.

RESULTS

The results show that EBI induced interleukin (IL)-10-producing dendritic cells (DCs) via increasing IL-35 and signal transducer and activator of transcription 3 (STAT3) phosphorylation. IL-10-expressing DCs induced IL-10-producing B cells (B10 cells), with the latter showing immunosuppressive functions. After challenge with specific antigens, AR mice showed sneezing, nasal itch, and increases in serum-specific immunoglobulin E (IgE) and mouse mast cell protease-1; higher levels of T helper 2 (Th2) cytokines (IL-4, 67.17 ± 10.66; IL-5, 62.83 ± 9.70; IL-13, 51.00 ± 6.69, before treatment) in nasal mucosal protein extracts, which were significantly suppressed (IL-4, 27.00 ± 6.66; IL-5, 23.86 ± 4.53; IL-13, 25.67 ± 4.93, after treatment (p < 0.001) by administration with EBI nasal drops.

CONCLUSION

EBI can suppress AR via inducing B10 cells. Thus, after carrying out required preclinical experiments and tests, EBI has the translational potential to be used in the treatment of AR and other allergic diseases.

Human placental trophoblast cells contribute to maternal-fetal tolerance through expressing IL-35 and mediating iTR35 conversion

During pregnancy, trophoblast cells sustain the maternal-fetal tolerance via expressing and secreting various chemokines and cytokines. Our previous study revealed the expression of interleukin-35 (IL-35) in human first-trimester trophoblasts. Here we show that IL-35 is expressed in both human first-trimester primary trophoblast cells and a trophoblast cell line. Trophoblast cells inhibit the proliferation of human naive conventional T cells (T_conv cells) and convert suppressed T_conv cells into iT_R35 in an IL-35-dependent manner. Mechanistically, trophoblast cell derived IL-35 mediates its function through phosphorylation of STAT1 and STAT3. In vivo studies confirm that mice with immunologically spontaneous abortion have lower levels of IL-35 and iT_R35 cells at the maternal-fetal interface, and neutralizing anti-IL-35 mAb enhances abortion rates. Meanwhile, exogenous IL-35 induces iT_R35 and prevents immunological abortion. Our findings thus suggest that trophoblast cells have a critical function in preserving maternal-fetal tolerance via secreting IL-35 during pregnancy.

Evidence for IL-35 Expression in Diffuse Large B-Cell Lymphoma and Impact on the Patient's Prognosis

IL-35 is an immunosuppressive cytokine of the IL-12 family consisting of two subunits, EBV-induced gene 3 (EBI3) and p35. It has been shown to play a pro-tumor role in murine tumor models, and in various types of human cancer such as colorectal, pancreatic, or liver carcinoma, its expression has been associated with a worse clinical outcome. Here, we show by analyzing gene expression data from public databases and by immunohistochemical studies that IL-35 is overexpressed by tumor cells in diffuse-large B-cell lymphoma (DLBCL) compared to another type of mature aggressive B-cell lymphoma, Burkitt lymphoma. However, while high IL-35 expression was significantly associated with a worse overall survival in DLBCL patients treated with chemotherapy only (cyclophosphamide, doxorubicin, vincristine, prednisone, CHOP), no significant correlation between IL-35 expression levels and the patient outcome was observed in DLBCL patients treated with CHOP combined to rituximab (R-CHOP), the current conventional treatment. In addition, we found that an anti-IL-35 antibody, clone 15k8D10, used to assess IL-35 expression by immunohistochemistry in various human tissues including tumors does not recognize IL-35 heterodimer, nor its individual subunits EBI3 and p35, but cross-reacts with human IgG1, indicating that IL-35 expression in human cancers needs to be re-evaluated.

Protosappanin A protects against experimental autoimmune myocarditis, and induces metabolically reprogrammed tolerogenic DCs

Autoimmune myocarditis is an immune-mediated myocardial injury that evolves into dilated cardiomyopathy (DCM). Protosappanin A (PrA), an immunosuppressive compound, induces immune tolerance in cardiac transplantation. However, whether PrA confers protective immunosuppression on experimental autoimmune myocarditis (EAM) is unknown. In this study, PrA treatment remarkably suppressed cardiac inflammatory cell infiltration and ameliorated cardiac remodeling in EAM mice. Additionally, PrA treatment reduced splenic T cells response, and induced expansion of immunosuppressive regulatory T cells (Tregs). Meanwhile, PrA induced the splenic dendritic cells (DCs) into a tolerogenic state with reduced co-stimulatory molecules, increased the production of tolerogenic cytokines in vivo. PrA also reprogrammed the metabolism of splenic DCs to a more glycolytic phenotype. To further investigate the effect of PrA on the functional and metabolic phenotype of DCs, the compound was added into the in vitro culture of MyHC-α-loaded DCs. These cells switched to a tolerogenic state and a metabolic profile similar to that found in cells during in ex vivo experiments. Treatment with glycolytic inhibitor 2-DG significantly reversed PrA-mediated DC tolerogenic properties, suggesting that glycolysis is indispensable for PrA-conditioned DCs to maintain their tolerogenic properties. Notably, PrA-conditioned DC vaccinations dampened EAM progress, and promoted Tregs expansion. Similarly, tolerogenic and metabolic patterns were also observed in PrA-modified human DC. In conclusion, PrA endows DC with a tolerogenic profile via glycolytic reprogramming, thereby inducing expansion of immunosuppressive Tregs, and preventing EAM progress. Our results suggested that PrA may confer immunosuppressive and protective effects on EAM by metabolically reprogramming DCs, which could contribute to the development of a new potential immunotherapy for the treatment of EAM and immune-related disorders.

Interleukin-35 as an Emerging Player in Tumor Microenvironment

IL-35 is the newest member of IL-12 family. A dimeric protein consisting of two separate subunits has manifested suppressive actions on immune system, which is counterproductive in the context of cancers. Various reports have confirmed its inhibitory role on immune system which is carried out via formation of IL-35-producing regulatory T cells (iTr35), increased Treg development and suppressive Th17 cells growth. Although last decade has seen a great deal of scientific interest on this subject, the exact role, precise signal transduction and elaborative functions of IL-35 in tumor microenvironment (TME) remained elusive. Search for anti-IL-35 therapies have exhibited limited success in animal models. Contrarily, few studies have denied the idea that IL-35 plays a role in cancer. The purpose of this review is to analyze the reported scientific data on continuous symphony of IL-35 in cancers since the inception of former.

IL-35Ig-expressing dendritic cells induce tolerance via Arginase 1

The cytokine interleukin IL‐35 is known to exert strong immunosuppressive functions. Indoleamine 2,3‐dioxygenase 1 (IDO1) and Arginase 1 (Arg1) are metabolic enzymes that, expressed by dendritic cells (DCs), contribute to immunoregulation. Here, we explored any possible link between IL‐35 and the activity of those enzymes. We transfected a single chain IL‐35Ig gene construct in murine splenic DCs (DC₃₅) and assessed any IDO1 and Arg1 activities as resulting from ectopic IL‐35Ig expression, both in vitro and in vivo. Unlike Ido1, Arg1 expression was induced in vitro in DC₃₅, and it conferred an immunosuppressive phenotype on those cells, as revealed by a delayed‐type hypersensitivity assay. Moreover, the in vivo onset of a tolerogenic phenotype in DC₃₅ was associated with the detection of CD25⁺CD39⁺, rather than Foxp3⁺, regulatory T cells. Therefore, Arg1, but not Ido1, expression in DC₃₅ appears to be an early event in IL‐35Ig–mediated immunosuppression.

Regulatory T Cells and Their Derived Cytokine, Interleukin-35, Reduce Pain in Experimental Autoimmune Encephalomyelitis

Sensory problems such as neuropathic pain are common and debilitating symptoms in multiple sclerosis (MS), an autoimmune inflammatory disorder of the CNS. Regulatory T (Treg) cells are critical for maintaining immune homeostasis, but their role in MS-associated pain remains unknown. Here, we demonstrate that Treg cell ablation is sufficient to trigger experimental autoimmune encephalomyelitis (EAE) and facial allodynia in immunized female mice. In EAE-induced female mice, adoptive transfer of Treg cells and spinal delivery of the Treg cell cytokine interleukin-35 (IL-35) significantly reduced facial stimulus-evoked pain and spontaneous pain independent of disease severity and increased myelination of the facial nociceptive pathway. The effects of intrathecal IL-35 therapy were Treg-cell dependent and associated with upregulated IL-10 expression in CNS-infiltrating lymphocytes and reduced monocyte infiltration in the trigeminal afferent pathway. We present evidence for a beneficial role of Treg cells and IL-35 in attenuating pain associated with EAE independently of motor symptoms by decreasing neuroinflammation and increasing myelination.SIGNIFICANCE STATEMENT Pain is a highly prevalent symptom affecting the majority of multiple sclerosis (MS) patients and dramatically affects overall health-related quality of life; however, this is a research area that has been largely ignored. Here, we identify for the first time a role for regulatory T (Treg) cells and interleukin-35 (IL-35) in suppressing facial allodynia and facial grimacing in animals with experimental autoimmune encephalomyelitis (EAE). We demonstrate that spinal delivery of Treg cells and IL-35 reduces pain associated with EAE by decreasing neuroinflammation and increasing myelination independently of motor symptoms. These findings increase our understanding of the mechanisms underlying pain in EAE and suggest potential treatment strategies for pain relief in MS.

Induction of Tolerogenic Dendritic Cells by Endogenous Biomolecules: An Update

The importance of microenvironment on dendritic cell (DC) function and development has been strongly established during the last two decades. Although DCs with general tolerogenic characteristics have been isolated and defined as a particular sub-population, it is predominantly their unequivocal biological plasticity, which allows for unparalleled responsiveness to environmental ques and shaping of their tolerogenic characteristics when interacting with tolerance-inducing biomolecules. Dendritic cells carry receptors for a great number of endogenous factors, which, after ligation, can importantly influence the development of their activation state. For this there is ample evidence merely by observation of DC characteristics isolated from various anatomical niches, e.g., the greater immunosuppressive potential of DCs isolated from intestine compared to conventional blood DCs. Endogenous biomolecules present in these environments most likely play a major role as a determinant of their phenotype and function. In this review, we will concisely summarize in what way various, tolerance-inducing endogenous factors influence DC biology, the development of their particular tolerogenic state and their subsequent actions in context of immune response inhibition and induction of regulatory T cells.

Emerging role of IL-35 in inflammatory autoimmune diseases

Interleukin 35 (IL-35) is the recently identified member of the IL-12 family of cytokines and provides the possibility to be a target for new therapies for autoimmune, inflammatory diseases. It is composed of an α chain (p35) and a β chain (EBI3). IL-35 mediates signaling by binding to its receptors, activates subsequent signaling pathways, and therefore, regulates the differentiation, function of T, B cells, macrophages, dendritic cells. Recent findings have shown abnormal expression of IL-35 in inflammatory autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, type 1 diabetes, psoriasis, multiple sclerosis, autoimmune hepatitis, experimental autoimmune uveitis. In addition, functional analysis suggested that IL-35 is critical in the onset and development of these diseases. Therefore, the present study will systematically review what had been occurred regarding IL-35 in inflammatory autoimmune disease. The information collected will help to understand the biologic role of IL-35 in immune cells, and give information about the therapeutic potential of IL-35 in these diseases.

Interleukin 35: Inhibitory regulator in monocyte-derived dendritic cell maturation and activation

IL-35, a novel IL-12 family member, is a potent inhibitory cytokine predominantly produced by regulatory T and B lymphocytes that exerts optimal suppression in immune response. However, it remains unclear whether IL-35 plays an inhibitory role on human dendritic cells. In the present study, we focused on the possible immunosuppressive effect of IL-35 on the differentiation, maturation and function of monocyte-derived DCs (MoDCs). Addition of exogenous IL-35 was able to partially suppress MoDCs differentiation in vitro. Subsequently, LPS was used for the maturation of MoDCs and IL-35 was found to mainly restrain the maturation of MoDCs, characterized by the remarkable down-regulation of costimulatory molecules, CD83 and HLA-DR as well as a reduced production of pro-inflammatory cytokines (IL-12p70, IFN-γ, and TNF-α). Furthermore, IL-35-treated MoDCs exhibited strong inhibition in the proliferation of allogeneic CD4⁺/CD8⁺ T lymphocytes. Meanwhile, IL-35-treated MoDCs also suppressed the polarization of naïve CD4⁺ T lymphocytes towards Th1 phenotype and impaired CD8⁺ T cells allogeneic responses. And the foregoing suppression of MoDCs maturation and function by IL-35 might be due to the aberrant activation of STAT1/STAT3 and inhibition of p38 MAPK/NF-κB signaling pathway. Our results demonstrated for the first time that IL-35 played a critical role in modulating not only adaptive immune response, but also innate immune response. The inhibitory effect of IL-35 on MoDCs maturation and function may facilitate the development of promising therapeutic interventions in tumors and other diseases.

Decreased interleukin(IL)-35 Expression is Associated with Active Intraocular Inflammation in Vogt-Koyanagi-Harada (VKH) Disease

Purpose: Recent studies have reported that IL-35 has a protective effect in autoimmune disease. In this study, we explored the role of IL-35 in the pathogenesis of Vogt-Koyanagi-Harada (VKH) disease. Methods: The IL-35/EBI3 and IL-35/P35 mRNA level was assayed by Real-Time PCR. The level of IL-35 in serum was detected by ELISA. PBMCs and monocyte-derived DCs were cultured with or without IL-35 and the concentration of IL-17, IL-10, IFN-γ, IL-6, TNF-α, and IL-1β in supernatants was tested by ELISA. Results: The serum level of IL-35 is reduced in active VKH patients. The mRNA expression of the two subunits IL-35/EBI3 and IL-35/P35 in PBMCs from patients with active VKH was also decreased. IL-35 significantly inhibited IFN-γ and IL-17 expression and induced IL-10 production by PBMCs and inhibited IL-6 production by monocyte-derived DCs. Conclusion: The current study suggests that a decreased IL-35 expression may be involved in the pathogenesis of VKH disease.

Mechanisms of Tolerance Induction by Dendritic Cells In Vivo

Dendritic cells (DCs) are a heterogeneous population playing a pivotal role in immune responses and tolerance. DCs promote immune tolerance by participating in the negative selection of autoreactive T cells in the thymus. Furthermore, to eliminate autoreactive T cells that have escaped thymic deletion, DCs also induce immune tolerance in the periphery through various mechanisms. Breakdown of these functions leads to autoimmune diseases. Moreover, DCs play a critical role in maintenance of homeostasis in body organs, especially the skin and intestine. In this review, we focus on recent developments in our understanding of the mechanisms of tolerance induction by DCs in the body.