Increased Th17 and regulatory T cell responses in EBV-induced gene 3-deficient mice lead to marginally enhanced development of autoimmune encephalomyelitis

Interleukin-27 Promotes the Generation of Myeloid-derived Suppressor Cells to Alleviate Graft-versus-host Disease

BACKGROUND

Stimulation of myeloid-derived suppressor cell (MDSC) formation represents a potential curative therapeutic approach for graft-versus-host disease (GVHD), which significantly impacts the prognosis of allogeneic hematopoietic stem cell transplantation. However, the lack of an effective strategy for inducing MDSC production in vivo has hindered their clinical application. In our previous study, MDSC expansion was observed in interleukin (IL)-27-treated mice.

METHODS

In this study, we overexpressed exogenous IL-27 in mice using a recombinant adeno-associated virus vector to investigate its therapeutic and exacerbating effects in murine GVHD models.

RESULTS

In our study, we demonstrated that exogenous administration of IL-27 significantly suppressed GVHD development in a mouse model. We found that IL-27 treatment indirectly inhibited the proliferation and activation of donor T cells by rapidly expanding recipient and donor myeloid cells, which act as MDSCs after irradiation or under inflammatory conditions, rather than through regulatory T-cell expansion. Additionally, IL-27 stimulated MDSC expansion by enhancing granulocyte-monocyte progenitor generation. Notably, we verified that IL-27 signaling in donor T cells exerted an antagonistic effect on GVHD prevention and treatment. Further investigation revealed that combination therapy involving IL-27 and T-cell depletion exhibited remarkable preventive effects on GVHD in both mouse and xenogeneic GVHD models.

CONCLUSIONS

Collectively, these findings suggest that IL-27 promotes MDSC generation to reduce the incidence of GVHD, whereas targeted activation of IL-27 signaling in myeloid progenitors or its combination with T-cell depletion represents a potential strategy for GVHD therapy.

SARS-CoV-2 infection elucidates unique features of pregnancy-specific immunity

Pregnancy is a risk factor for increased severity of SARS-CoV-2 and other respiratory infections. The mechanisms underlying this risk have not been well-established, partly due to a limited understanding of how pregnancy shapes immune responses. To gain insight into the role of pregnancy in modulating immune responses at steady state and upon perturbation, we collected peripheral blood mononuclear cells (PBMC), plasma, and stool from 226 women, including 152 pregnant individuals (n = 96 with SARS-CoV-2 infection and n = 56 healthy controls) and 74 non-pregnant women (n = 55 with SARS-CoV-2 and n = 19 healthy controls). We found that SARS-CoV-2 infection was associated with altered T cell responses in pregnant compared to non-pregnant women. Differences included a lower percentage of memory T cells, a distinct clonal expansion of CD4-expressing CD8 + T cells, and the enhanced expression of T cell exhaustion markers, such as programmed cell death-1 (PD-1) and T cell immunoglobulin and mucin domain-3 (Tim-3), in pregnant women. We identified additional evidence of immune dysfunction in severely and critically ill pregnant women, including a lack of expected elevation in regulatory T cell (Treg) levels, diminished interferon responses, and profound suppression of monocyte function. Consistent with earlier data, we found maternal obesity was also associated with altered immune responses to SARS-CoV-2 infection, including enhanced production of inflammatory cytokines by T cells. Certain gut bacterial species were altered in pregnancy and upon SARS-CoV-2 infection in pregnant individuals compared to non-pregnant women. Shifts in cytokine and chemokine levels were also identified in the sera of pregnant individuals, most notably a robust increase of interleukin-27 (IL-27), a cytokine known to drive T cell exhaustion, in the pregnant uninfected control group compared to all non-pregnant groups. IL-27 levels were also significantly higher in uninfected pregnant controls compared to pregnant SARS-CoV-2-infected individuals. Using two different preclinical mouse models of inflammation-induced fetal demise and respiratory influenza viral infection, we found that enhanced IL-27 protects developing fetuses from maternal inflammation but renders adult female mice vulnerable to viral infection. These combined findings from human and murine studies reveal nuanced pregnancy-associated immune responses, suggesting mechanisms underlying the increased susceptibility of pregnant individuals to viral respiratory infections.

Interleukin-35 Promote Osteogenesis and Inhibit Adipogenesis: Role of Wnt/β-Catenin and PPARγ Signaling Pathways

Mesenchymal stem cells (MSCs) are multipotent stem cells that are able to differentiate into several cell types, including cartilage, fat, and bone. It has been reported that the decision process of MSCs into fat and bone cells is competing and reciprocal. Interleukin (IL)-35 is an important effector protein in the Wnt/β-catenin signaling pathway that acts as a bone metabolism regulator. However, it is unclear whether IL-35 is also important for regulating MSC differentiation to fat and bone. In the current study, we evaluated the role of IL-35 in C3H10T1/2 cells, which are a good cell model for investigating osteogenesis and adipogenesis in bone marrows. The role of IL-35 on osteoblast proliferation and apoptosis was assessed using cell counting kit-8 assay and flow cytometry, respectively. Extracellular matrix mineralization and lipid accumulation were measured by Alizarin Red S staining and Oil Red O staining, respectively. The most important transcription factor of the process of osteogenesis Runx2 and Wnt/β-catenin signaling pathway components β-catenin and Axin2 were investigated in response to IL-35 treatment. Furthermore, the adipogenic markers PPAR-γ and C/EBPα were also investigated. Our observations showed that IL-35 could promote the proliferation of MSCs and inhibit the apoptosis of MSCs. We found that IL-35 treatment resulted in a dramatic stimulation of osteogenesis and inhibition of adipogenesis. Moreover, IL-35 enhanced Wnt/β-catenin pathway key component β-catenin as well as Axin2 expression during MSCs differentiated to osteoblasts. Our findings suggested that IL-35 might control the balance between osteogenic and adipogenic differentiation of progenitor cells through the Wnt/β-catenin-PPARγ signaling pathway, suggesting its potential application in providing an intervention in osteoporosis and obesity.

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.

Interleukin-35 ameliorates cardiovascular disease by suppressing inflammatory responses and regulating immune homeostasis

The immune response is of great significance in the initiation and progression of a diversity of cardiovascular diseases involving pro-and anti-inflammatory cytokines. Interleukin-35 (IL-35), a cytokine of the interleukin-12 family, is a novel anti-inflammation and immunosuppressive cytokine, maintaining inflammatory suppression and regulating immune homeostasis. The role of IL-35 in cardiovascular diseases (CVDs) has aroused enthusiastic attention, a diversity of experimental or clinical evidence has indicated that IL-35 potentially has a pivot role in protecting against cardiovascular diseases, especially atherosclerosis and myocarditis. In this review, we initiate an overview of the relationship between Interleukin-35 and cardiovascular diseases, including atherosclerosis, acute coronary syndrome, pulmonary hypertension, abdominal aortic aneurysm, heart failure, myocardial ischemia-reperfusion, aortic dissection and myocarditis. Although the specific molecular mechanisms entailing the protective effects of IL-35 remain an unsolved issue, targeted therapies with IL-35 might provide a promising and effective solution to prevent and cure cardiovascular diseases.

At Embryo Implantation Site IL-35 Secreted by Trophoblast, Polarizing T Cells towards IL-35+ IL-10+ IL-4+ Th2-Type Cells, Could Favour Fetal Allograft Tolerance and Pregnancy Success

We investigated the role of rhIL-35, at low concentrations compatible with those produced by human trophoblast cells (less than 1 ng/mL), on human T helper (Th) cell functions and the presence of decidual IL-35-producing Th cells in human pregnancy. We found that human trophoblast cells produced IL-35 but not IL-4 or IL-10. RhIL-35, at concentrations produced by human trophoblasts, polarized T cells towards IL-35+, IL-10+, IL-4+ Th2-type cells and to Foxp3+ EBI3+ p35+ T reg cells producing IL-35 but not IL-10 and IL-4. Moreover, rhIL-35 at low concentrations did not suppress the proliferation of Th cells but stimulated IL-4 and IL-10 production by established Th clones. In particular, Th1-type clones acquired the capacity to produce IL-4. In addition, purified human trophoblast cell supernatants containing IL-35 upregulated IL-4 and IL-10 production by Th clones. Finally, IL-35+, IL-10+, IL-4+ Th2-type cells, which were found to be induced by low concentrations of IL-35 compatible with those produced by human trophoblasts, are exclusively present in the decidua of a successful pregnancy and at the embryo implantation site, suggesting their stringent dependence on trophoblast cells. Thus, the proximity of Th cells to IL-35-producing trophoblasts could be the determining factor for the differentiation of IL-35+, IL-10+, IL-4+ Th2-type cells that are crucial for human pregnancy success.

CD24 is expressed on FoxP3+ regulatory T cells and regulates their function

CD24 is a glycosyl-phosphatidylinositol (GPI) anchored cell surface glycoprotein with a variety of immunomodulatory functions such as inhibition of thymic generation of autoreactive T cells, regulation of antigen presenting cell functions, and mediation of autoimmunity. Given the autoimmune nature of FoxP3+ regulatory T cells and their importance in autoimmune diseases, we hypothesize that CD24 regulates the generation and functions of Treg cells. Through the analysis of the Treg repertoire in two strains of CD24-deficient mice, we found that CD24 does not globally affect the thymic generation of Treg cells. However, CD24 is abundantly expressed on Treg cells, and CD24 antibody treatment of Treg cells enhances their suppressive functions. Concurrently, we observed CD24-deficient Treg cells exhibit increased suppressive functions and produce more IL-10 compared to their wild type counterparts. In addition, CD24-deficient Treg cells exhibited more potent suppressive capacity in inhibiting the development of experimental autoimmune encephalomyelitis (EAE) in mice. Thus, CD24 on Treg cells regulates their suppressive functions. Our findings can partially explain the resistance of EAE development in CD24-deficient mice and CD24 polymorphism-associated susceptibility of human autoimmune diseases. Further investigations regarding mechanisms of CD24 regulation of Treg function may lead to a new approach for the immunotherapy of human autoimmune diseases.

Interleukin 35 contributes to immunosuppression by regulating inflammatory cytokines and T cell populations in the acute phase of sepsis

Cytokines interact closely with each other and play a crucial role in the progression of sepsis. We focused on the associations of a cytokine network with IL-35 in sepsis. First, the retrospective study included 42 patients with sepsis and 23 healthy controls. Blood samples were collected from patients on days 1, 2, 4. Levels of IL-35, IL-1β, IL-4, IL-6, IL-10, IL-17A, TNF-α and IFN-γ were measured. They all increased to various extend on days 1, 2, 4, and strongly associated with markers of disease severity. Network analysis revealed a network formed by IL-35, with IL-6, IL-10, IL-17A, TNF-α and IFN-γ throughout the acute phase of sepsis(days 1, 2 and4). Then, the CLP-induced septic rats were used. The recombinant human IL-35(rIL-35) upregulated the levels of IL-10, but downregulated IL-4, IL-6, IL-17A, TNF-α and IFN-γ, while it had no significant effect on IL-1β, and upregulated the percentages of CD4⁺CD25⁺Tregs, and iTR35, but downregulated Teff cells in the peripheral blood. The rIL-35 reduced inflammation damage and improved prognosis of the septic rats. IL-35 forms a network with other cytokines and plays a major role in the immunopathogenesis of sepsis.

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.

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.

Interleukin-35 pathobiology in periodontal disease: a systematic scoping review

Background

Interleukin (IL)-35 is a novel anti-inflammatory cytokine that is produced by regulatory T cells. IL-35 mediates immunological functions and plays a protective role in several diseases such as asthma and rheumatoid arthritis. However, the role of IL-35 in gingivitis and periodontitis remains unclear. The aim of this study was to systematically review the literature and collecting the available evidence regarding the role of IL-35 in pathogenesis of periodontal disease.

Methods

A systematic search of electronic databases including MEDLINE, Google Scholar, Cochrane Library, Web of Science, and Scopus was conducted in November 2020 to identify studies addressing the Interleukin-35 pathobiology in periodontal disease. The identified studies were subjected to pre-identified inclusion criteria. The retrived papers were assessed by the authours independently and consensus was reached in cases where disagreement occurred. Articles written in languages other than English, case reports, letters to editors, conference abstracts, theses, and dissertations were excluded from the review.

Results

A total of 176 possibly relevant articles were identified through the search strategy. Finally, 15 papers which met the criteria of eligibility were included in this review by consensus. The included articles were classified based on their design and level of evidence.Three subclinical study, ten cross sectional investigation and two randomized clinical trials constituted the final set of studies in this review. At preclinical level, Il-35 showed inhibitory characteristics regarding alveolar bone resorption of animal periodontitis models. The results of observatory human studies confirmed the presence of high levels of IL-35 in saliva, GCF, serum, and gingival biopsies of patients suffering from inflammatory periodontal disease. Moreover, two included clinical trials showed that non-surgical periodontal therapy could downregulate IL-35 production in chronic periodontitis patients.

Conclusion

Interleukin-35 has an undeniable role in pathobiology of inflammatory periodontal disease. Further well-controlled studies are needed to better elucidate the functional pattern of IL-35 in pathogeneisis of gingival and periodontal disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01515-1.

EBV-induced gene 3 augments IL-23Rα protein expression through a chaperone calnexin

Epstein-Barr virus-induced gene 3 (EBI3) is a subunit common to IL-27, IL-35, and IL-39. Here, we explore an intracellular role of EBI3 that is independent of its function in cytokines. EBI3-deficient naive CD4+ T cells had reduced IFN-γ production and failed to induce T cell-dependent colitis in mice. Similarly reduced IFN-γ production was observed in vitro in EBI3-deficient CD4+ T cells differentiated under pathogenic Th17 polarizing conditions with IL-23. This is because the induction of expression of one of the IL-23 receptor (IL-23R) subunits, IL-23Rα, but not another IL-23R subunit, IL-12Rβ1, was selectively decreased at the protein level, but not the mRNA level. EBI3 augmented IL-23Rα expression via binding to the chaperone molecule calnexin and to IL-23Rα in a peptide-dependent manner, but not a glycan-dependent manner. Indeed, EBI3 failed to augment IL-23Rα expression in the absence of endogenous calnexin. Moreover, EBI3 poorly augmented the expression of G149R, an IL-23Rα variant that protects against the development of human colitis, because binding of EBI3 to the variant was reduced. Taken together with the result that EBI3 expression is inducible in T cells, the present results suggest that EBI3 plays a critical role in augmenting IL-23Rα protein expression via calnexin under inflammatory conditions.

Inflammatory versus Anti-inflammatory Profiles in Major Depressive Disorders-The Role of IL-17, IL-21, IL-23, IL-35 and Foxp3

Background: The authors of this research study intended to verify whether there are any changes in gene expression in depressed patients without coexisting inflammatory diseases for selected immune-inflammatory factors that are particularly important in autoimmune disease pathogenesis (IL-17, IL-21, IL-23, IL-35, Foxp3). Methods: The study was carried out on a group of 190 patients with depression and 100 healthy volunteers. The severity of depressive symptoms was assessed using the Hamilton Depression Scale. RT-PCR was used to evaluate mRNA expression and ELISA was used to measure protein expression of these genes. Results: The level of gene expression for IL-17, IL-21, IL-23, and IL-35 was substantially higher in the group of patients with depression compared to the control group. The mean mRNA expression of Foxp3 was considerably reduced in patients suffering from depressive disorders. There was a statistically significant correlation between the number of hospitalizations and the expression of specific inflammatory factors. Conclusions: Expression of specific inflammatory genes may be a factor in the etiopathogenesis of depressive disorders. The duration of the disease seems to be more important for the expression of the genes in question than the severity of depression. These cytokines may affect the metabolism of neurotransmitters and neuroendocrine functions in the brain as well as be a marker and a new potential therapeutic target for recurrent depressive disorders.

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.

Immunomodulatory cytokine interleukin-35 and immune thrombocytopaenia

Considerable attention has been paid to interleukin (IL)-35 because of its immunosuppressive effects in a variety of autoimmune diseases. IL-35, a recently identified cytokine of the IL-12 family, is a negative regulatory factor secreted by IL-35-inducible regulatory T cells (iTr35 cells) and the recently reported regulatory B cells (Breg cells). Four biological effects of IL-35 have been discovered in vitro and in vivo: (i) suppression of T cell proliferation; (ii) conversion of naive T cells into iTr35 cells; (iii) downregulation of type 17 helper T (Th17) cells; and (iv) conversion of Breg cells into a Breg subset that produces IL-35 and IL-10. IL-35 plays an important role in a variety of autoimmune diseases, such as rheumatoid arthritis, allergic asthma and systemic lupus erythematosus. Primary immune thrombocytopaenia (ITP), which is characterized by isolated thrombocytopaenia and mild mucocutaneous to life-threatening bleeding, is an autoimmune disease with complex dysregulation of the immune system. Both antibody-mediated and/or T cell-mediated platelet destruction are key processes. In addition, impairment of T cells and cytokine imbalances have now been recognized to be important. This review summarizes the immunomodulatory effects of IL-35 and its role in the pathogenesis of ITP as mediated by T and B cells.

Interleukin-35 promotes the differentiation of regulatory T cells and suppresses Th2 response in IgG4-related type 1 autoimmune pancreatitis

BACKGROUND

IgG4-related disease (IgG4-RD) is a systemic inflammatory disease, which includes type 1 autoimmune pancreatitis (AIP). Interleukin-35 (IL-35) exhibits immunosuppressive effects in several autoimmune diseases. However, the expression of IL-35 had not been reported so far in type 1 AIP. We evaluated the association between IL-35 and several cytokines, which mediate the function of Tregs in type 1 AIP.

METHODS

Plasma was collected from patients with type 1 AIP, alcoholic chronic pancreatitis (ACP), and healthy controls (HC) and assayed for cytokine expression. Total mRNA separated from peripheral blood was isolated from naïve Tregs (nTregs) and effector Tregs (eTregs). EBI3 and IL-12p35 gene expressions were tested in these cells by quantitative PCR. In addition, expression of IL-35 subunits in the pancreatic tissues of patients with type 1 AIP and ACP was analyzed by immunohistochemistry.

RESULTS

IL-35 was significantly elevated in type 1 AIP (n = 32) plasma compared with ACP (n = 16) and HC (n = 22), but IL-27 was not. We also detected many cells expressing both EBI3 and IL-12p35 in type 1 AIP tissues. Moreover, in peripheral blood lymphocyte, the percentage of nTregs and eTregs of CD4⁺ T cells in patients with type 1 AIP (n = 14) compared with HC (n = 15) was significantly decreased and increased, respectively. There were no significant differences of gene expression in patients with type 1 AIP and HC.

CONCLUSIONS

This study identified elevated expression of plasma IL-35 and tissue IL-35 subunits in patients with type 1 AIP. This might lead to inflammation suppression via activated eTregs. IL-35 might be associated with this anti-inflammatory role, especially against the Th2 response through several cytokines and the differentiation of Tregs in type 1 AIP.

Regulatory T cells: Master thieves of the immune system

Treg cells are the immune system's in-house combatants against pathological immune activation. Because they are vital to maintenance of peripheral tolerance, it is important to understand how they perform their functions. To this end, various mechanisms have been proposed for Treg-mediated immune inhibition. A major group of mechanisms picture Treg cells as skilled thieves stealing a plethora of molecules that would otherwise promote immune effector functions. This suggests that several million years of evolution have endowed Treg cells with efficient ways to deprive immune effectors of activating stimuli to prevent immunopathology for survival of the host. Although we are still long way from deciphering their complete set of tricks, this review will focus on the types of "crimes" committed by these master thieves in both secondary lymphoid organs and non-lymphoid tissue.

Different expression levels of interleukin-35 in asthma phenotypes

Background

Interleukin (IL)-35 is a newly discovered inhibitory cytokine which is produced by regulatory B and T lymphocytes and belongs to the IL-12 family. It plays a suppressive role in human inflammatory diseases; however, its role in asthma phenotypes is unclear. Our study focuses on the sputum IL-35 level in patients and investigates different airway inflammation capacities of sputum IL-35 in patients with different asthma phenotypes.

Objective

We aimed to determine the sputum IL-35 levels in asthmatic patients with clinical remission phenotypes and control subjects and to investigate possible correlations among lung function, age, sex, fractional exhaled nitric oxide (FeNO), and smoking history in these phenotypes.

Methods

Sputum samples were collected from patients with clinical asthma remission (n = 89, 37 males, age 52.24 ± 13.32 years) and a healthy control group (n = 19, 9 males, age 44.58 ± 16.3 years). All subjects underwent sputum induction. Induced sputum was assessed for inflammatory cell count, and sputum levels of IL-35 and other cytokines were measured by ELISA and Cytometric Bead Array, respectively.

Results

Sputum IL-35 (median (q1, q3)) levels showed no significant difference between asthma patients (4.89 ng/mL (2.97, 22.75)) and healthy controls (6.01 ng/mL (4.09, 30.47)). However, the sputum IL-35 level was significantly reduced in patients with eosinophilic asthma (EA) (3.95 ng/mL (2.80, 11.00)) compared to patients with neutrophilic asthma (NA) (40.59 ng/mL (20.59, 65.06), p = 0.002), paucigranulocytic asthma (PA) (6.25 ng/mL (3.10, 24.60), p = 0.012), and mixed granulocytic asthma (MA) (22.54 ng/mL (2.58, 52.45), p = 0.026). IL-35 levels in sputum showed a positive correlation with sputum neutrophil cells and a negative correlation with FeNO, FEV1% predicted, and FVC predicted. Furthermore, sputum IL-35 had a significant positive association with Th1-related factors and a negative correlation with Th2-related factors.

Conclusions

Sputum IL-35 is likely involved in different pathophysiological mechanisms of NA and EA and exerts different effects in asthma phenotypes.

Interleukin-35 inhibits alveolar bone resorption by modulating the Th17/Treg imbalance during periodontitis

AIM

T lymphocytes play a central role during the pathogenesis of periodontitis, and the imbalance between the pathogenic T-helper type 17 (Th17) and protective T-regulatory (Treg) lymphocytes determines the tooth-supporting alveolar bone resorption. Interleukin (IL)-35 is a novel anti-inflammatory cytokine with therapeutic properties in diseases whose pathogenesis is associated with the Th17/Treg imbalance; however, its role during periodontitis has not been established yet. This study aimed to elucidate whether IL-35 inhibits the alveolar bone resorption during periodontitis by modulating the Th17/Treg imbalance.

MATERIALS AND METHODS

Mice with ligature-induced periodontitis were treated with locally or systemically administrated IL-35. As controls, periodontitis-affected mice without IL-35 treatment and non-ligated mice were used. Alveolar bone resorption was measured by micro-computed tomography and scanning electron microscopy. The Th17/Treg pattern of the immune response was analysed by qPCR, ELISA, and flow cytometry.

RESULTS

IL-35 inhibited alveolar bone resorption in periodontitis mice. Besides, IL-35 induced less detection of Th17 lymphocytes and production of Th17-related cytokines, together with higher detection of Treg lymphocytes and production of Treg-related cytokines in periodontitis-affected tissues.

CONCLUSION

IL-35 is beneficial in the regulation of periodontitis; particularly, IL-35 inhibited alveolar bone resorption and this inhibition was closely associated with modulation of the periodontal Th17/Treg imbalance.

Interleukin-35 Regulates Immune Microenvironment of Autoimmune Hepatitis Through Inducing the Expansion of Myeloid-Derived Suppressor Cells

Interleukin-35 (IL-35) is a novel anti-inflammatory cytokine of IL12 cytokine family, however, the role of IL-35 in patients with AIH and its effect on myeloid-derived suppressor cells (MDSCs) has not yet been analyzed. The expression of IL-35 subunits (p35 and EBI3) in liver tissues was quantified by immunochemistry and its correlation with clinical parameters was explored in patients with AIH. The expression of MDSCs and IL-35 receptor (gp130 and IL-12Rβ2) were analyzed using flow cytometry and confocal staining. Besides, we utilized in vitro culture to explore the role of IL-35 on MDSCs expansion and activation. We found that the elevated expression of both IL-35 subunits (EBI3 and p35) in liver tissue was positively associated with degrees of hepatic inflammatory and fibrosis in patients with AIH. Furthermore, the expression of EBI3 in liver was positively correlated with patient age, serum IgG levels and serum AST, and was negatively correlated with hemoglobin and albumin. Moreover, our results showed that ratio of MDSC in peripheral blood increased significantly in AIH patients as compared with healthy controls. Further study showed that CD33, a representative marker of MDSCs, co-localized well with gp130 and IL12Rβ2, suggesting MDSCs as target cell for IL-35. Consistently, MDSCs from AIH displayed a substantial higher abundance of gp130 and IL12Rβ2 and were expanded by IL-35 in vitro. IL-35-induced MDSCs showed a significant increase in Nitric oxide (NO) production but not reactive oxygen species (ROS). Conclusions: IL-35 might play an important role in AIH by regulating MDSCs and it could provide new insights into the therapy of AIH.

IL-27, IL-30, and IL-35: A Cytokine Triumvirate in Cancer

The role of the immune system in anti-tumor immunity cannot be overstated, as it holds the potential to promote tumor eradication or prevent tumor cell escape. Cytokines are critical to influencing the immune responses and interactions with non-immune cells. Recently, the IL-12 and IL-6 family of cytokines have accumulated newly defined members each with specific immune functions related to various cancers and tumorigenesis. There is a need to better understand how cytokines like IL-27, IL-30, and IL-35 interact with one another, and how a developing tumor can exploit these interactions to enhance immune suppression. Current cytokine-based immunotherapies are associated with cytotoxic side effects which limits the success of treatment. In addition to this toxicity, understanding the complex interactions between immune and cancer cells may be one of the greatest challenges to developing a successful immunotherapy. In this review, we bring forth IL-27, IL-30, and IL-35, “sister cytokines,” along with more recent additions to the IL-12 family, which serve distinct purposes despite sharing structural similarities. We highlight how these cytokines function in the tumor microenvironment by examining their direct effects on cancer cells as well their indirect actions via regulatory functions of immune cells that act to either instigate or inhibit tumor progression. Understanding the context dependent immunomodulatory outcomes of these sister cytokines, as well as their regulation within the tumor microenvironment, may shed light onto novel cancer therapeutic treatments or targets.

Schistosoma japonicum peptide SJMHE1 suppresses airway inflammation of allergic asthma in mice

Helminths and their products can shape immune responses by modulating immune cells, which are dysfunctional in inflammatory diseases such as asthma. We previously identified SJMHE1, a small molecule peptide from the HSP60 protein of Schistosoma japonicum. SJMHE1 can inhibit delayed-type hypersensitivity and collagen-induced arthritis in mice. In the present study, we evaluated this peptide's potential intervention effect and mechanism on ovalbumin-induced asthma in mice. SJMHE1 treatment suppressed airway inflammation in allergic mice, decreased the infiltrating inflammatory cells in the lungs and bronchoalveolar lavage fluid, modulated the production of pro-inflammatory and anti-inflammatory cytokines in the splenocytes and lungs of allergic mice, reduced the percentage of Th2 cells and increased the proportion of Th1 and regulatory T cells (Tregs). At the same time, Foxp3 and T-bet expression increased, and GATA3 and RORγt decreased in the lungs of allergic mice. We proved that SJMHE1 can interrupt the development of asthma by diminishing airway inflammation in mice. The down-regulation of Th2 response and the up-regulation of Th1 and Tregs response may contribute to the protection induced by SJMHE1 in allergic mice. SJMHE1 can serve as a novel therapy for asthma and other allergic or inflammatory diseases.

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.

The Immunobiology of the Interleukin-12 Family: Room for Discovery

The discovery of interleukin (IL)-6 and its receptor subunits provided a foundation to understand the biology of a group of related cytokines: IL-12, IL-23, and IL-27. These family members utilize shared receptors and cytokine subunits and influence the outcome of cancer, infection, and inflammatory diseases. Consequently, many facets of their biology are being therapeutically targeted. Here, we review the landmark discoveries in this field, the combinatorial biology inherent to this family, and how patient datasets have underscored the critical role of these pathways in human disease. We present significant knowledge gaps, including how similar signals from these cytokines can mediate distinct outcomes, and discuss how a better understanding of the biology of the IL-12 family provides new therapeutic opportunities.

The immunomodulatory role of interleukin-35 in fibrotic diseases

INTRODUCTION

Fibrosis makes numerous diseases in all organs more complicated and leads to severe consequences in the lung, liver, heart, kidney, and skin. In essence, fibrosis results from excessive, persistent and oftentimes nonreversible aggregation of extracellular matrix (ECM) or simply as collagen during the process of tissue injury and repair. Recent studies suggest the pathology of fibrosis, especially in pulmonary and liver fibrosis, involves various types of immune cells and soluble mediators including interleukin (IL)-35, a recently identified heterodimeric cytokine that belongs to the IL-12 cytokine family. Furthermore, IL-35 may inhibit fibrotic diseases. However, the side effects of inhibiting IL-35 also need attention and we have a long way to go to make better use of it in fibrotic diseases. Areas covered: This review focuses on recent evidence regarding the role of IL-35 in the pathogenesis of pulmonary, hepatic, cardiac, renal and skin fibrosis. It also discusses targeting of IL-35 as a promising novel strategy for treatment of fibrotic diseases. Expert commentary: Understanding as fully as possible the relationship between IL-35 and fibrotic diseases is important for the development of new therapeutic approaches.

Role of IL-35 in sublingual allergen immunotherapy

BACKGROUND

Grass pollen-specific immunotherapy involves immunomodulation of allergen-specific T_H2 responses and induction of IL-10⁺ and/or TGF-β⁺CD4⁺CD25⁺ regulatory T cells (induced Treg cells). IL-35⁺CD4⁺CD25⁺ forkhead box protein 3-negative T (IL-35-inducible regulatory T [iT_R35]) cells have been reported as a novel subset of induced Treg cells with modulatory characteristics.

OBJECTIVE

We sought to investigate mechanisms underlying the induction and maintenance of immunologic tolerance induced by IL-35 and iT_R35 cells.

METHODS

The biological effects of IL-35 were assessed on group 2 innate lymphoid cells (ILC2s); dendritic cells primed with thymic stromal lymphopoietin, IL-25, and IL-33; and B and T_H2 cells by using flow cytometry and quantitative RT-PCR. Grass pollen-driven T_H2 cell proliferation and cytokine production were measured by using tritiated thymidine and Luminex MagPix, respectively. iT_R35 cells were quantified in patients with grass pollen allergy (seasonal allergic rhinitis [SAR] group, n = 16), sublingual immunotherapy (SLIT)-treated patients (SLIT group, n = 16), and nonatopic control subjects (NACs; NAC group, n = 16).

RESULTS

The SAR group had increased proportions of ILC2s (P = .002) and IL-5⁺ cells (P = .042), IL-13⁺ cells (P = .042), and IL-5⁺IL-13⁺ ILC2s (P = .003) compared with NACs. IL-35 inhibited IL-5 and IL-13 production by ILC2s in the presence of IL-25 or IL-33 (P = .031) and allergen-driven T_H2 cytokines by effector T cells. IL-35 inhibited CD40 ligand-, IL-4-, and IL-21-mediated IgE production by B cells (P = .015), allergen-driven T-cell proliferation (P = .001), and T_H2 cytokine production mediated by primed dendritic cells. iT_R35 cells suppressed T_H2 cell proliferation and cytokine production. In addition, allergen-driven IL-35 levels and iT_R35 cell counts were increased in patients receiving SLIT (all, P < .001) and NACs (all, P < .001) compared with patients with SAR.

CONCLUSION

IL-35 and iT_R35 cells are potential novel immune regulators induced by SLIT. The clinical relevance of SLIT can be underscored by restoration of protective iT_R35 cells.

Differing Outcome of Experimental Autoimmune Encephalitis in Macrophage/Neutrophil- and T Cell-Specific gp130-Deficient Mice

gp130 cytokines are differentially involved in regulating the T helper (H) 17-driven pathogenesis of experimental autoimmune encephalomyelitis (EAE), the animal model of human multiple sclerosis. Interleukin (IL)-6 directly promotes the development of TH17 cells through the gp130/IL-6R complex. By contrast, IL-27 has been shown to suppress a TH17 immune response by gp130/IL-27R-alpha (α) receptor ligation. The IL-27-dependent regulation of a TH17 development could be mediated on the level of CD4 T cells. However, because IL-27 also suppresses the secretion of the TH17-driving cytokines IL-6 and IL-12/23p40 in accessory cells, TH17 immune responses may also be controlled by IL-27 on the level of macrophages and/or neutrophils. To analyze these opposing effects of gp130 engagement on the pathogenesis of EAE, we immunized CD4⁺ T cell-specific gp130-deficient (CD4cre^posgp130^loxP/loxP) and macrophage/neutrophil-specific gp130-deficient (LysMcre^posgp130^loxP/loxP) mice with the myelin-oligodendrocyte-glycoprotein peptide MOG_35-55. Whereas inflammatory immune responses, TH17 differentiation, and pathology in CD4cre^posgp130^loxP/loxP mice were mitigated, disease progression was eventually enhanced in LysMcre^posgp130^loxP/loxP mice. Exacerbated disease in MOG_35-55-immunized LysMcre^posgp130^loxP/loxP mice was associated with an elevated development of TH17 cells and increased infiltration of the central nervous system with leukocytes indicating a suppressive role of macrophage/neutrophil-gp130. To further prove IL-6 to be responsible for the control of inflammation during EAE through gp130 on macrophages/neutrophils, we immunized LysMcre^posIL-6R^loxP/loxP mice. In contrast to LysMcre^posgp130^loxP/loxP mice, neuropathology in MOG_35-55-immunized macrophage/neutrophil-specific IL-6R-deficient mice was not enhanced indicating that the alleviation of EAE through macrophage/neutrophil-gp130 is mediated independently of IL-6. Together, this different pathology in macrophage/neutrophil- and CD4 T cell-specific gp130-deficient mice suggests that gp130 cytokines modulate TH17 inflammation differentially by targeting distinct cell types.

Interleukin-35 stimulates hepatitis B virus transcription and replication by targeting transcription factor HNF4α

Hepatitis B virus (HBV) infection is a major health problem worldwide. Interleukin-35 (IL-35) is a definite immunosuppressive cytokine belonging to the IL-12 family. Nevertheless, the role of IL-35 in HBV replication remains elusive. In this study, we found that the level of HBV DNA replicative intermediates detected by qPCR and Southern blotting analysis was significantly increased by rhIL-35 in a dose-dependent manner. Moreover, HBV 3.5 kb mRNA levels were up-regulated by rhIL-35. The HBV core protein level as well as the HBsAg and HBeAg secretion levels were also increased by rhIL-35. Moreover, a mechanistic study demonstrated that IL-35 promoted HBV replication by enhancing the HBV core promoter activity. Importantly, hepatocyte nuclear factor 4α (HNF4α) was probably the target of IL-35. Mutation of the HNF4α-binding site on HBV core promoter or silencing HNF4α abolished the enhancement of HBV replication induced by IL-35. Finally, rhIL-35 was able to increase HBV replication in HBV transgenic mice. Taken together, our findings demonstrated that IL-35 has a novel role in HBV replication.

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.

Interleukin-35 Level Is Elevated in Patients with Chronic Hepatitis B Virus Infection

Backgrounds: As one of the major public health problems, the hepatitis B virus (HBV) infection would activate the immune system. The outcome of HBV infection was affect significantly by the interactions between HBV and host immune response. Interleukins play important role in anti-viral immunity. Here we investigated the role of interleukin-35 (IL-35) in chronic HBV infection patients. Methods/Results: Serum IL-35 in 72 chronic hepatitis B virus infection patients and 41 healthy control subjects were analyzed by ELISA assay. The mRNA level of IL-35 in PBMCs was determined by RT-qPCR. In this study, we found that both protein and mRNA levels of IL-35 were significantly decreased in chronic HBV patients compared to the healthy controls. Furthermore, the statistical analysis found that serum IL-35 was significantly associated with HBV DNA (P =0.0158), ALT (P =0.0003), AST (P =0.0216), TB (P =0.0270) and AFP (P =0.0369). Importantly, correlation analysis also found that serum IL-35 level was negatively correlated with HBV DNA copies, ALT, AST, TB and AFP. Meanwhile, IL-35 treatment inhibited the level of HBV DNA, HBsAg and HBeAg in HepAD38 cells. Conclusion: Our study identified that IL-35 may be a novel marker associated with HBV infection and hepatocytes injury. These data suggested the potential use of IL-35 in the HBV treatment.

Evaluation of IL-12A, IL-12B, IL-23A and IL-27 mRNA expression level genes in peripheral mononuclear cells of inflammatory bowel disease patients in an Iranian population

AIM

Aim of this study was to compare the gene expression of Interleukin 12 members in two phase of IBD.

BACKGROUND

Inflammatory bowel disease (IBD) is a well-known gastrointestinal disorder in the world that fluctuates between remission and flare-up phases. Each of these phases has an individual immune system response profile. Therefore, analyzing the interleukins (IL) expression status improves the diagnosis and the classification of the IBD cases.

METHODS

In this a case-control study, among 400 patients whom admitted to the IBD clinic, forty nine IBD patients were included. Patients were divided into three categories based on 1) the phase of the disease, 2) the type of IBD, Ulcerative colitis (UC) or Crohn's disease (CD), and 3) the therapeutic pathways. Using the real-time PCR method, the expression levels of IL-12A, IL-12B, IL-23A, and IL-27 were examined in the peripheral blood mononuclear cell (PBMC) and compared to the pre-described subgroups.

RESULTS

the data showed upregulation in the expression levels of IL-12A and IL-12B in the remission phase in comparison with the flare-up. However, no significant changes were obtained from the evaluation of IL-23A and IL-27. In addition, the mRNA levels of the target genes in the subgroups of Category 2 as well as Category 3 were similar.

CONCLUSION

Our results showed that expression patterns of the IL-12A and IL-12B genes varied between the remission and flare-up phases for the IBD patients, and may be considered as potential biomarkers for the detection and the classification of IBD cases.

IL-35 recombinant protein reverses inflammatory bowel disease and psoriasis through regulation of inflammatory cytokines and immune cells

Interleukin‐35 (IL‐35), a member of the IL‐12 family, functions as a new anti‐inflammatory factor involved in arthritis, psoriasis, inflammatory bowel disease (IBD) and other immune diseases. Although IL‐35 can significantly prevent the development of inflammation in many diseases, there have been no early studies accounting for the role of IL‐35 recombinant protein in IBD and psoriasis. In this study, we assessed the therapeutic potential of IL‐35 recombinant protein in three well‐known mouse models: the dextransulfate sodium (DSS)‐induced colitis mouse model, the keratin14 (K14)‐vascular endothelial growth factor A (VEGF‐A)‐transgenic (Tg) psoriasis mouse model and the imiquimod (IMQ)‐induced psoriasis mouse model. Our results indicated that IL‐35 recombinant protein can slow down the pathologic process in DSS‐induced acute colitis mouse model by decreasing the infiltrations of macrophages, CD4⁺T and CD8⁺T cells and by promoting the infiltration of Treg cells. Further analysis demonstrated that IL‐35 recombinant protein may regulate inflammation through promoting the secretion of IL‐10 and inhibiting the expression of pro‐inflammatory cytokines such as IL‐6, TNF‐α and IL‐17 in acute colitis model. In addition, lower dose of IL‐35 recombinant protein could achieve long‐term treatment effects as TNF‐α monoclonal antibody did in the psoriasis mouse. In summary, the remarkable therapeutic effects of IL‐35 recombinant protein in acute colitis and psoriasis mouse models indicated that IL‐35 recombinant protein had a variety of anti‐inflammatory effects and was expected to become an effective candidate drug for the treatment of inflammatory diseases.

IL-27, but not IL-35, inhibits neuroinflammation through modulating GM-CSF expression

IL-27 and IL-35 are heterodimeric cytokines, members of the IL-12 family and considered to have immunomodulatory properties. Their role during neuroinflammation had been investigated using mutant mice devoid of either one of their subunits or lacking components of their receptors, yielding conflicting results. We sought to understand the therapeutic potential of IL-27 and IL-35 delivered by gene therapy in neuroinflammation. We constructed lentiviral vectors expressing IL-27 and IL-35 from a single polypeptide chain, and we validated in vitro their biological activity. We injected IL-27 and IL-35-expressing lentiviral vectors into the cerebrospinal fluid (CSF) of mice affected by experimental neuroinflammation (EAE), and performed clinical, neuropathological and immunological analyses. Both cytokines interfere with neuroinflammation, but only IL-27 significantly modulates disease development, both clinically and neuropathologically. IL-27 protects from autoimmune inflammation by inhibiting granulocyte macrophages colony-stimulating factor (GM-CSF) expression in CD4⁺ T cells and by inducing program death-ligand 1 (PD-L1) expression in both CNS-resident and CNS-infiltrating myeloid cells. We demonstrate here that IL-27 holds therapeutic potential during neuroinflammation and that IL-27 inhibits GM-CSF and induces pd-l1 mRNA in vivo.

IL-35 may maintain homeostasis of the immune microenvironment in periodontitis

T lymphocyte cells, including regulatory T (Treg) and T helper 17 cells, have important roles in the human periodontium. However, the basis for Treg cytokine expression in various compartments of the periodontium remains unclear. The aim of the present study was to investigate the expression of interleukin (IL)-35 in the peripheral blood mononuclear cells (PBMCs) and periodontal tissues of patients with chronic periodontitis (CP), with a view to understanding its role in this disease, and ultimately providing improved treatments. Peripheral blood, periodontal tissues and gingival crevicular fluids (GCFs) were collected from patients with CP or impacted teeth, the latter serving as healthy controls. The expression levels of IL-35 subunit mRNAs in PBMCs and periodontal tissues were determined using reverse transcription-quantitative polymerase chain reaction, while the IL-35 protein expression in GCFs and sera was quantified by ELISA. The relative expression of IL-35 subunit mRNAs in the affected tissues of patients with CP was significantly higher compared with that in samples from healthy controls (P<0.05). The mean concentration of IL-35 protein in the GCFs and sera of patients with periodontitis was also significantly higher compared with that in samples from healthy controls (P<0.001). IL-35 protein and periodontal clinical indicators were negatively correlated. It was hypothesized that the increased level of IL-35 plays a protective role in periodontal disease by maintaining immune system homeostasis and dampening the inflammatory response, and highlights IL-35 as a potential new therapy for the treatment of periodontitis.

Interluekin-35 in Asthma and Its Potential as an Effective Therapeutic Agent

Interleukin- (IL-) 35 is a member of the IL-12 cytokine family and a heterodimeric protein formed by Epstein-Barr-induced gene 3 (EBI3) and IL-12p35. Emerging evidence shows that IL-35 is a key player in the regulation of cellular communication, differentiation, and inflammation. Altered IL-35 expression has been found in disease conditions such as cancer, rheumatoid arthritis, and, more recently, asthma. In cancer, IL-35 is involved in the regulation of tumorigenesis, cancer progression, and metastasis. In rheumatoid arthritis, IL-35 acts as a negative regulator of inflammation. Similarly, IL-35 also appears to suppress allergic inflammation in asthma. In an in vivo murine model of asthma, transfer of adenovirus-mediated IL-35 markedly reduced the degree of airway hyperresponsiveness (AHR) and inflammatory cell infiltration. Many studies have shown the involvement of IL-35 in a number of aspects of allergic inflammation, such as eosinophil and neutrophil recruitment as well as inhibition of inflammatory mediators of the Th2 subtype. However, the exact molecular mechanisms underlying the role of IL-35 in human asthma have yet to be fully elucidated. This review describes the current evidence regarding the role of IL-35 in the pathophysiology of asthma and evaluates the potential of IL-35 as a biomarker for airway inflammation and a therapeutic target for the treatment of asthma.

Epstein-Barr virus-induced gene 3 (EBI3) can mediate IL-6 trans-signaling

Epstein-Barr virus-induced gene 3 (EBI3) is a subunit of the composite cytokines IL-27 and IL-35. Both have beneficial functions or effects in models of infectious and autoimmune diseases. This suggests that administration of EBI3 could be therapeutically useful by binding free p28 and p35 to generate IL-27 and IL-35. IL-27- and IL-35-independent functions of EBI3 could compromise its therapeutic uses. We therefore assessed the effects of EBI3 on cytokine receptor-expressing cells. We observed that EBI3 activates STAT3 and induces the proliferation of the IL-6-dependent B9 mouse plasmacytoma cell line. Analyses using blocking mAbs and Ba/F3 transfectants expressing gp130 indicate that EBI3 activity was linked to its capacity to mediate IL-6 trans-signaling, albeit less efficiently than soluble IL-6Rα. In line with this interpretation, co-immunoprecipitation and SPR experiments indicated that EBI3 binds IL-6. An important pro-inflammatory function of IL-6 trans-signaling is to activate blood vessel endothelial cells. We observed that EBI3 in combination with IL-6 could induce the expression of chemokines by human venal endothelial cells. Our results indicate that EBI3 can promote pro-inflammatory IL-6 functions by mediating trans-signaling. These unexpected observations suggest that use of EBI3 as a therapeutic biologic for autoimmune diseases will likely require co-administration of soluble gp130 to prevent the side effects associated with IL-6 trans-signaling. Together with previous studies that demonstrated activation of IL-6R by p28 (IL-30), new findings further suggest a complex interrelation between IL-27 and IL-6.

Interleukin 35 Polymorphisms Are Associated with Decreased Risk of Premature Coronary Artery Disease, Metabolic Parameters, and IL-35 Levels: The Genetics of Atherosclerotic Disease (GEA) Study

Interleukin 35 (IL-35) is a heterodimeric cytokine involved in the development of atherosclerosis. The aim of the present study was to establish if the polymorphisms of IL-12A and EBI3 genes that encode the IL-35 subunits are associated with the development of premature coronary artery disease (CAD) in Mexican individuals. The IL-12A and EBI3 polymorphisms were determined in 1162 patients with premature CAD and 873 controls. Under different models, the EBI3 rs428253 (OR = 0.831, P_add = 0.036; OR = 0.614, P_rec = 0.033; OR = 0.591, P_cod2 = 0.027) and IL-12A rs2243115 (OR = 0.674, P_add = 0.010; OR = 0.676, P_dom = 0.014; OR = 0.698, P_het = 0.027; OR = 0.694, P_cod1 = 0.024) polymorphisms were associated with decreased risk of developing premature CAD. Some polymorphisms were associated with clinical and metabolic parameters. Significant different levels of IL-35 were observed in EBI3 rs4740 and rs4905 genotypes only in the group of healthy controls. In summary, our study suggests that the EBI3 and IL-12A polymorphisms play an important role in decreasing the risk of developing premature CAD; it also demonstrates the relationship of the EBI3 rs4740 and rs4905 genotypes with IL-35 levels in healthy individuals.

Molecular Pathways: Interleukin-35 in Autoimmunity and Cancer

Immunosuppressive functions conferred by regulatory cytokines are important for maintaining homeostasis in immune responses. IL35 has recently emerged as a novel regulator of immune responses. Once thought to be specifically expressed by T regulatory cells, induction of IL35 expression has now been detected in multiple cell types in a variety of diseases, prompting research into regulation of its expression, signaling specificity, target cell populations, and functional outputs. Recent studies have revealed that by directing de novo generation of regulatory T and B cells and inhibiting T effector responses, IL35 plays an important role in the development of autoimmune diseases and cancer. IL35 is overexpressed in a variety of cancers and may exert its function both on antitumor immune responses as well as directly on tumor cells. As such, IL35 is rapidly emerging as a promising biomarker and an attractive cancer therapy target. Clin Cancer Res; 22(20); 4973-8. ©2016 AACR.

IL-35 and Autoimmunity: a Comprehensive Perspective

Interleukin 35 (IL-35) is the most recently identified member of the IL-12 family of cytokines and offers the potential to be a target for new therapies for autoimmune, inflammatory, and infectious diseases. Similar to other members of the IL-12 family including IL-12, IL-23, and IL-27, IL-35 is composed of a heterodimer of α and β chains, which in the case of IL-35 are the p35 and Epstein-Barr virus-induced gene 3 (EBI3) proteins. However, unlike its proinflammatory relatives, IL-35 has immunosuppressive effects that are mediated through regulatory T and B cells. Although there are limited data available regarding the role of IL-35 in human autoimmunity, several murine models of autoimmunity suggest that IL-35 may have potent effects in regulating immunoreactivity via IL-10-dependent mechanisms. We suggest that similar effects are operational in human disease and IL-35-directed therapies hold significant promise. In particular, we emphasize that IL-35 has immunosuppressive ability that are mediated via regulatory T and B cells that are IL-10 dependent. Further, although deletion of IL-35 does not result in spontaneous breach of tolerance, recombinant IL-35 can improve autoimmune responses in several experimental models.

Gene Expression and Antiviral Activity of Interleukin-35 in Response to Influenza A Virus Infection

Interleukin-35 (IL-35) is a newly described member of the IL-12 family. It has been reported to inhibit inflammation and autoimmune inflammatory disease and can increase apoptotic sensitivity. Little is known about the role of IL-35 during viral infection. Herein, high levels of IL-35 were found in peripheral blood mononuclear cells and throat swabs from patients with seasonal influenza A virus (IAV) relative to healthy individuals. IAV infection of human lung epithelial and primary cells increased levels of IL-35 mRNA and protein. Further studies demonstrated that IAV-induced IL-35 transcription is regulated by NF-κB. IL-35 expression was significantly suppressed by selective inhibitors of cyclooxygenase-2 (COX-2) and inducible nitric-oxide synthase, indicating their involvement in IL-35 expression. Interestingly, IL-35 production may have suppressed IAV RNA replication and viral protein synthesis via induction of type I and III interferons (IFN), leading to activation of downstream IFN effectors, including double-stranded RNA-dependent protein kinase, 2',5'-oligoadenylate synthetase, and myxovirus resistance protein. IL-35 exhibited extensive antiviral activity against the hepatitis B virus, enterovirus 71, and vesicular stomatitis virus. Our results demonstrate that IL-35 is a novel IAV-inducible cytokine, and its production elicits antiviral activity.

Interleukin-35 attenuates collagen-induced arthritis through suppression of vascular endothelial growth factor and its receptors

OBJECTIVE

To investigate the effect of interleukin-35 (IL-35) on vascular endothelial growth factor (VEGF) and its receptors, Flt-1 and Flk-1, in a collagen-induced arthritis (CIA) mouse model of rheumatoid arthritis (RA).

METHODS

We established a CIA mouse model and injected IL-35 intraperitoneally. The articular index (AI) was measured based on the amount of erythema, swelling, or joint rigidity and synovial histology was measured by hematoxylin and eosin staining (HE staining). The levels of VEGF, Flt-1, Flk-1, and von Willebrand factor (vWF) expression in CIA synovial tissue were determined by immunohistochemistry. The mRNA and protein expression levels of VEGF, Flt-1, Flk-1, TNF-α, and INF-γ were detected by reverse transcription PCR (RT-PCR) and western blots, respectively.

RESULTS

The IL-35 treatment decreased the AI and the synovial histological scores of CIA mice. Immunohistochemistry results revealed that the IL-35 treatment downregulated VEGF, Flt-1, Flk-1, and vWF expression in the CIA mice. RT-PCR results showed that the IL-35-treated mice had lower levels of VEGF, Flt-1, Flk-1, and TNF-α mRNA expression than those of the PBS-treated mice. While there was no significant difference in the level of INF-γ mRNA expression between IL-35-treated and PBS-treated mice. Western blot results showed that the IL-35 treatment downregulated the levels of VEGF, Flt-1, Flk-1, and TNF-α in CIA mice, but the level of INF-γ was not significantly affected.

CONCLUSION

These findings show that IL-35 may represent a novel therapeutic agent for RA, and the probable mechanisms may rely on inhibiting VEGF and its receptors Flt-1 and Flk-1.

IL-12Rβ2 has a protective role in relapsing-remitting experimental autoimmune encephalomyelitis

IL-12Rβ2 is a common receptor subunit of heterodimeric receptors for IL-12 and IL-35, two cytokines that are implicated in immunopathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. We evaluated the role of IL-12Rβ2 in relapsing-remitting EAE (RR-EAE). IL-12Rβ2-deficient SJL/J mice developed markedly more severe clinical EAE, and had greater mortality and more severe relapses compared with wild-type controls. IL-12Rβ2-deficient EAE mice also had more infiltrating mononuclear cells in the CNS, as well as higher T cell proliferative capacity and decreased IFN-γ production at the periphery. These findings demonstrate a protective role of IL-12Rβ2 in RR-EAE.

IL-35 inhibits acute graft-versus-host disease in a mouse model

Acute graft-versus-host disease (aGVHD) is a serious complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Our previous study found that the novel anti-inflammatory cytokine IL-35 could suppress aGVHD in patients after allo-HSCT. In this study, we used C57BL/6 (B6, H-2b) mice as donors and (B6×DBA/2) F1 (BDF1, H-2b×d) mice as recipients to create a model of aGVHD and explore the relationship between IL-35 and aGVHD. The mice receiving IL-35 survived longer than did the control mice. We observed that treatment with IL-35 and RAPA could reduce the incidence of aGVHD. Additionally, this treatment inhibited intestinal and thymic epithelial cell apoptosis and liver infiltration by the donor T-cells, thereby ameliorating the enteropathy and liver injury caused by aGVHD. We found that IL-35 and RAPA also markedly suppressed TNF-α and IL-17A expression and enhanced IFN-γ expression in the intestine and liver. We measured Tregs in spleen and found that IL-35 and RAPA treatment expanded the number of Tregs in spleen. We found that the phosphorylation of STAT1 and STAT4 were inhibited in mice with aGVHD. In contrast, STAT1 and STAT4 were phosphorylated when the mice were treated with IL-35. IL-35 may have therapeutic potential in the treatment of aGVHD after allo-HSCT.

Remission of systemic lupus erythematosus disease activity with regulatory cytokine interleukin (IL)-35 in Murphy Roths Large (MRL)/lpr mice

The immunological mechanisms mediated by regulatory cytokine interleukin (IL)-35 are unclear in systemic lupus erythematosus (SLE). We investigated the frequency of CD4(+) CD25(+) forkhead box protein 3 (FoxP3)(+) regulatory T (Treg ) and IL-10(+) regulatory B (Breg ) cells and related immunoregulatory mechanisms in a female Murphy Roths Large (MRL)/lpr mouse model of spontaneous lupus-like disease, with or without IL-35 treatment. A remission of histopathology characteristics of lupus flare and nephritis was observed in the MRL/lpr mice upon IL-35 treatment. Accordingly, IL-35 and IL-35 receptor subunits (gp130 and IL-12Rβ2) and cytokines of MRL/lpr and BALB/c mice (normal controls) were measured. The increased anti-inflammatory cytokines and decreased proinflammatory cytokines were possibly associated with the restoration of Treg and Breg frequency in MRL/lpr mice with IL-35 treatment, compared to phosphate-buffered saline (PBS) treatment. mRNA expressions of Treg -related FoxP3, IL-35 subunit (p35 and EBI3) and soluble IL-35 receptor subunit (gp130 and IL12Rβ2) in splenic cells were up-regulated significantly in IL-35-treated mice. Compared with the PBS treatment group, IL-35-treated MRL/lpr mice showed an up-regulation of Treg -related genes and the activation of IL-35-related intracellular Janus kinase/signal transducer and activator of transcription signal pathways, thereby indicating the immunoregulatory role of IL-35 in SLE. These in vivo findings may provide a biochemical basis for further investigation of the regulatory mechanisms of IL-35 for the treatment of autoimmune-mediated inflammation.

A potential immunopathogenic role for reduced IL-35 expression in allergic asthma

OBJECTIVE

Allergic asthma is a chronic airway inflammation resulting from an imbalance of T helper (Th) cell responses to allergens. Interleukin (IL)-35 has been shown to have potent immunoregulatory properties. Whether IL-35 participates in the immunopathogenesis of allergic asthma patients is still unknown.

METHODS

CD4+ T cells and CD4+ CD25- T cells were obtained from peripheral blood mononuclear cells (PBMCs) using magnetic separation. The concentration of IL-35 in plasma was measured by enzyme-linked immunosorbent assay (ELISA). The mRNA expression levels of the IL-35 subunits, EBI3 and IL-12p35, were detected by quantitative real-time PCR (qPCR). The proliferative responses of CFSE-labeled CD4+ CD25- T cells in the presence or absence of rhIL-35 were evaluated by flow cytometry. Cytokine production of activated CD4+ CD25- T cells was examined by flow cytometry and ELISA.

RESULTS

IL-35 protein and mRNA levels were decreased in allergic asthmatics. The frequencies of CD4+ CD25+ Foxp3+ Tregs and CD4+ IL-12p35+ T cells in allergic asthma patients were lower than in healthy controls. Moreover, the addition of rhIL-35 suppressed CFSE+ CD4+ CD25- T cell proliferation in vitro in a dose-dependent manner, and the suppression induced by rhIL-35 was associated with decreases in IL-4 but not IFN-γ and IL-17 production of activated CD4+ CD25- T cells. The increased level of Th1/Th2 was observed in allergic asthmatics in the presence of rhIL-35.

CONCLUSIONS

Our data suggest that IL-35 can effectively suppress the proliferation and IL-4 production of activated CD4+ CD25- T cells in allergic asthma, and that IL-35 may be a new immunotherapy for asthma patients.