Adaptive plasticity of natural interleukin-35-induced regulatory T cells (Tr35) that are required for T-cell immune regulation

Background: IL-35 potently inhibits immune responses both in vivo and in vitro. However, the specific characteristics of IL-35-producing cells, including their developmental origin, cellular phenotype, and function, are unknown. Methods: By using a novel IL-35 reporter mouse (Ebi3-Dre-Thy1.1) and double transgenic fate-mapping reporter mice (35EbiT-Rosa26-rox-tdTomato reporter mice or Foxp3 fate-mapping system), we tracked and analyzed the differentiation and developmental trajectories of Tr35 cells in vivo. And then we investigated the therapeutic effects of OVA-specific Tr35 cells in an OVA-induced allergic airway disease model. Results: We identified a subset of cells, denoted Tr35 cells, that secrete IL-35 but do not express Foxp3. These cells have high expression of molecules associated with T-cell activation and can inhibit T-cell proliferation in vitro. Our analyses showed that Tr35 cells are a distinct subpopulation of cells that are independent of Tr1 cells. Tr35 cells exhibit a unique gene expression profile and tissue distribution. The presence of Thy1.1 (Ebi3) expression in Tr35 cells indicates their active secretion of IL-35. However, the proportion of ex-Tr35 cells (Thy1.1-) is significantly higher compared to Tr35 cells (Thy1.1+). This suggests that Tr35 cells possess the ability to regulate IL-35 expression rapidly in vivo. Tr35 cells downregulated the expression of the inflammatory cytokines IL-4, IFN-γ and IL-17A. However, once Tr35 cells lost IL-35 expression and became exTr35 cells, the expression of inflammatory cytokines was upregulated. Importantly, our findings indicate that Tr35 cells have therapeutic potential. In an OVA-induced allergic airway disease mouse model, Tr35 cell reinfusion significantly reduced airway hyperresponsiveness and histopathological airway and lung inflammation. Conclusions: We have identified a subset of Tregs, Tr35 cells, that are distinct from Tr1 cells. Tr35 cells can dynamically regulate the secretion of inflammatory cytokines by controlling IL-35 expression to regulate inflammatory immune responses.

Interleukin-35 protein inhibits osteoclastogenesis and attenuates collagen-induced arthritis in mice

Rheumatoid arthritis (RA) is a chronic autoimmune disease. Its pathological features include synovial inflammation, bone erosion, and joint structural damage. Our previous studies have shown that interleukin (IL)-35 is involved in the pathogenesis of bone loss in RA patients. In this study, we are further evaluating the efficacy of IL-35 on collagen-induced arthritis (CIA) in the mouse model. Male DBA/1J mice (n = 10) were initially immunized, 2 μg/mouse IL-35 was injected intraperitoneally every week for 3 weeks after the establishment of the CIA model. Clinical arthritis, histopathological analysis, and three-dimensional micro-computed tomography (3D micro-CT) were determined after the mice were anesthetized on the 42th day. In vitro, RANKL/M-CSF induced mouse preosteoclasts (RAW264.7 cells line) was subjected to antiarthritis mechanism study in the presence of IL-35. The results of clinical arthritis, histopathological analysis, and 3D micro-CT, the expression of RANK/RANKL/OPG axis, inflammatory cytokines, and osteoclastogenesis-related makers demonstrated decreasing severity of synovitis and bone destruction in the ankle joints after IL-35 treatment. Furthermore, IL-35 attenuated inflammatory cytokine production and the expression of osteoclastogenesis-related makers in a mouse preosteoclasts cell line RAW264.7. The osteoclastogenesis-related makers were significantly reduced in IL-35 treated RAW264.7 cells line after blockage with the JAK/STAT1 signaling pathway. These results demonstrated that IL-35 protein could inhibits osteoclastogenesis and attenuates CIA in mice. We concluded that IL-35 can exhibit anti-osteoclastogenesis effects by reducing the expression of inflammatory cytokines and osteoclastogenesis-related makers, thus alleviating bone destruction in the ankle joint and could be a potential therapeutic target for RA.

Regulatory B cells induced by interleukin-35 inhibit inflammation and alveolar bone resorption in ligature-induced periodontitis

BACKGROUND

Regulatory B cells (Bregs) have been reported to suppress immune responses and alveolar bone loss in murine periodontitis models. These cells could be induced by interleukin (IL)-35 which is increased upon periodontal inflammation. Thus, this study aimed to explore the role of Bregs induced by IL-35 in periodontitis.

METHODS

Experimental periodontitis was induced in mice by ligature. Two weeks after ligation, the test group was systemically treated with IL-35 for 1 week. Four weeks after ligation, all mice were euthanized, and alveolar bone loss was evaluated by microcomputed tomography. Cytokines associated with periodontitis were analyzed using reverse transcription-quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. Bregs in spleens, cervical lymph nodes, and periodontal tissues were detected by flow cytometry and immunofluorescence staining.

RESULTS

In the mouse model of periodontitis, IL-35 induced the expansion of CD1dhi CD5+ B10 cells with increased interleukin-10 (IL-10) and IL-35 production. IL-35 administration also attenuated alveolar bone loss and reduced the levels of proinflammatory cytokines in situ.

CONCLUSIONS

Following ligature-induced periodontitis in mice, IL-35 inhibited periodontal inflammation and alveolar bone resorption at least partially through the induction of B10 cells and IL-35+ Bregs.

Impaired Regulation by IL-35 in Systemic Sclerosis

This study investigated the role of IL-35 in systemic sclerosis (SSc) patients, focusing on CD4+ T cell response and immunomodulatory cytokine production. By comparing the cytokine levels in healthy donors (HD) and SSc patients using ELISAs, we found a significantly lower plasma IL-35 concentration in the SSc patients (52.1 ± 5.6 vs. 143 ± 11.1, p < 0.001). Notably, the IL-35 levels showed a negative correlation with TGF-β (p < 0.001) and IL-17 (p = 0.04). Assessing the IL-35R expression across cell types in the SSc patients and HDs via flow cytometry, we found higher levels on monocytes (40.7 + 5.7 vs. 20.3 ± 1.9, p < 0.001) and lower levels on CD8+ T cells (61.8 ± 9.2 vs. 83.4 ± 0.8, p < 0.05) in the SSc patients. The addition of recombinant IL-35 to stimulated peripheral blood mononuclear cells reduced the IL-17+CD4+ T cell percentage (9.0 ± 1.5 vs. 4.8 ± 0.7, p < 0.05) and increased the IL-35+CD4+ T percentage (4.1 ± 2.3 vs. 10.2 ± 0.8, p < 0.001). In a Treg:Tresponder cell Sco-culture assay with HD and SSc samples, rIL35 decreased the cell proliferation and levels of IL-17A (178.2 ± 30.5 pg/mL vs. 37.4 ± 6.4 pg/mL, p < 0.001) and TGF-β (4194 ± 777 pg/mL vs. 2413 ± 608 pg/mL, p < 0.01). Furthermore, we observed a positive correlation between the modified Rodnan skin score (mRSS) and TGF-β (p < 0.001), while there was a negative correlation between mRSS and IL-35 (p = 0.004). Interestingly, higher levels of plasmatic IL-35 were detected in individuals with limited disease compared to those with diffuse disease (60.1 ± 8.0 vs. 832.3 ± 4.1, p < 0.05). These findings suggest that IL-35 exhibits anti-inflammatory properties in SSc and it may serve as a marker for disease severity and a therapeutic target.

JNK/c-Jun pathway activation is essential for HBx-induced IL-35 elevation to promote persistent HBV infection

BACKGROUND

Immunoregulation plays pivotal roles during chronic hepatitis B virus (HBV) infection. Studies have shown that Interleukin (IL)-35 is an important molecule associated with inadequate immune response against HBV. However, the mechanisms involved in the up-regulation of IL-35 expression during persistent HBV infection remain unknown.

METHODS

In this study, we constructed a plasmid expressing the HBV X protein (pCMV-HBx) to evaluate the relationship between HBx and IL-35. Activation of the JNK/c-Jun pathway was analyzed and chromatin immunoprecipitation followed by sequencing and luciferase reporter assays were performed to determine whether c-Jun could regulate IL-35 transcription.

RESULTS

HBx can significantly activate IL-35 promoter in both LO2 and HepG2 cells compared to the control plasmid (pCMV-Tag2) using the dual-luciferase assay. Whereas other viral proteins, such as S, preS1, the core protein, had no significant effect on IL-35 expression. Similarly, WB and qRT-PCR also showed that HBx can significantly promote IL-35 expression at protein and mRNA levels in the aforementioned cells. The relevant pathway mechanism showed that the expression of JNK and c-Jun genes was significantly higher in transfected cells carrying pCMV-HBx than in the pCMV-Tag2-transfected and -untransfected cells. WB analysis revealed that phosphorylated JNK and c-Jun were overexpressed after HBx action. Conversely, the addition of the JNK/c-Jun signaling pathway inhibitor could significantly suppress HBx-induced IL-35 expression in a dose-dependent manner.

CONCLUSIONS

A novel molecular mechanism of HBV-induced IL-35 expression was revealed, which involves JNK/c-Jun signaling in up-regulating IL-35 expression via HBx, resulting in transactivation of the IL-35 subunit EBI3 and p35 promoter.

Interleukin 35: protective role and mechanism in type 1 diabetes

Interleukin 35 (IL-35), a cytokine secreted by regulatory T (Treg) cells from the differentiation of conventional CD4+ T cells, is a member of the IL-12 family. The IL-12 family of cytokines exhibits an anti-inflammatory property. IL-35 has recently been shown to influence the immune modulation in various diseases, including inflammatory bowel disease, Graves' disease, rheumatoid arthritis, colitis, psoriasis, and type 1 diabetes (T1D). T1D is an immune-related disease caused by destruction of pancreatic β cells, characterized by an absolute lack of insulin. Recently, studies have suggested that protective effects of IL-35 work by improving blood glucose levels and preventing an attack of inflammatory factors on the islets. The protective mechanism may be closely related to the anti-inflammatory properties of IL-35, which include regulating macrophage phenotype, suppressing T cell proliferation, decreasing the differentiation of Th17 cells, increasing the Treg cell population, and inducing IL-35-producing regulatory T cells (iTr35). Here, we review the protective effects and mechanisms of action of IL-35 in T1D.

Pomegranate extract supplementation improves lung function parameters and IL-35 expression in participants with mild and moderate persistent allergic asthma: A randomized, double-blind, placebo-controlled trial

Existing asthma treatments are associated with side effects and limitations, which has led to an interest in alternative and complementary therapies. Given the anti-inflammatory properties of pomegranate, the present study aimed to determine the impact of pomegranate extract supplementation on lung function parameters evaluated through spirometry, high-sensitivity C-reactive protein (hs-CRP), pro-oxidant antioxidant balance, and interleukin 35) (IL-35) in participants with mild and moderate allergic asthma (based on forced expiratory volume in 1 second (FEV1) and clinical symptoms). Participants with mild and moderate allergic asthma (n = 64) were randomly assigned to two groups: the intervention group, which received two pomegranate extract capsules (500 mg/day), or the control group for eight weeks. Also, the physician prescribed similar drugs to the participants in the study. Independent samples T-test and Mann-Whitney U were used to compare the quantitative outcomes between the intervention group and the comparison group. The Wilcoxon test and the paired T-test were applied for within-group comparisons. A p-value <0.05 was considered significant. At the end of the study, the change levels of IL-35 in the intervention group increased significantly compared to the control group. In terms of the lung function parameters, FEV1/ forced vital capacity (FVC) (FEV1/FVC) ratio enhanced significantly in the intervention group compared to the control group. Also, the pomegranate extract significantly improved forced expiratory flow 25-75% (FEF25-75%), FEV1/FVC ratio, and FEV1 in the intervention group. No significant changes in FEV1 values were observed between the two groups at the end of the study. Also, no significant changes were seen in other indicators. It seems that pomegranate extract can improve lung function parameters and IL-35 expression in mild and moderate allergic asthma.

Clinical trial registration

https://www.irct.ir/trial/45612; identifier: IRCT20200205046384N1.

Association Between Interleukin 35 Gene Single Nucleotide Polymorphisms and the Uveitis Immune Status in a Chinese Han Population

Autoimmune uveitis is characterized by immune disorders of the eyes and the whole body and is often recurrent in young adults, but its pathogenesis is still unclear. IL-35 is an essential regulatory factor in many autoimmune diseases, which is produced by Breg cells and can induce Breg cells to regulate the immune response. The relationship between the expression and gene polymorphism of IL-35 and the immune status of patients with autoimmune uveitis has not been reported. The peripheral blood of the subjects was collected from patients with Behçet’s Disease (BD) and those with Vogt–Koyanagi–Harada (VKH) syndrome. The percentage of immune cell subsets including B cells, DC, and T cells, and the expression of IL-35 in serum of these two kinds of disease were analyzed. And then, the associations between seven IL-35 single nucleotide polymorphism (SNP) sites and disease susceptibility, the immune status, the clinical characteristics, and the serum IL-35 levels were analyzed. Our results showed that the percentage of Breg cells was significantly decreased in the blood of patients with VKH syndrome compared to that of healthy controls. The levels of IL-35 in the serum of patients with VKH syndrome or BD patients were not changed significantly, compared to that of healthy controls. Furthermore, the associations between two subunits of IL-35 (IL-12p35 and EBI3) and BD or VKH patients were analyzed. We found that there was an association between the EBI3 rs428253 and the occurrence of BD. There was an association between the IL-12p35 rs2243131 and the low level of Breg cell of VKH patients. In addition, there were associations between the polymorphisms of EBI3 rs4740 and the occurrence of headache and tinnitus of VKH patients, respectively. And the genotype frequency of IL-12p35 rs2243115 was related to the concentration of serum IL-35 in patients with VKH syndrome. Thus, the specific SNP sites change of IL-35 were correlated to the immune disorders in uveitis. And they may also play a guiding role in the occurrence of clinical symptoms in patients with uveitis, especially for VKH syndrome.

Curcumin Promotes the Expression of IL-35 by Regulating Regulatory T Cell Differentiation and Restrains Uncontrolled Inflammation and Lung Injury in Mice

Interleukin (IL)-35, which has an anti-inflammatory role in acute respiratory distress syndrome (ARDS)/acute lung injury (ALI), is relatively promising as a drug target. Studies have shown that curcumin may play a therapeutic role in ALI and enhance the suppressive function of regulatory T cells (Tregs). To illustrate the effect of curcumin on the regulation of Treg cell differentiation and expression of IL-35, we built a cecal ligation and puncture (CLP)-induced acute lung injury mouse mode with curcumin pretreatment. The expression of IL-35 in serum, severity of lung injury, IL-17A in lung tissue, survival rate, Treg-related cytokines levels in serum, nuclear factor-kappa B (NF-κB)'s nuclear translocation in lung tissue, and splenic CD4+CD25+FOXP3+ Tregs were assessed. Furthermore, the proportion of Tregs, STAT5, and IL-35 expression during naïve CD4+ T cell differentiation in vitro was measured. Compared with the CLP group, the increased IL-35 expression in CLP with the curcumin pretreatment (CLP + Cur) group was consistent with the decreased severity of lung injury, IL-17A protein levels in lung tissue, and Treg-related cytokines levels. Pretreatment with curcumin, the survival rate climbed to 50%, while the mortality rate was 100% in the CLP group. In addition, splenic CD4+CD25+FOXP3+ Treg cells increased in the CLP + Cur group. In vitro, CD4+CD25+FOXP3+ Treg cells from naïve CD4+ T cells, STAT5 proportion, and IL-35 expression increased after curcumin treatment. These findings showed that curcumin might regulate IL-35 by activating the differentiation of Treg cells to control the inflammation in acute lung injury.

Interleukin-35 Suppresses Interleukin-9-Secreting CD4+ T Cell Activity in Patients With Hepatitis B-Related Hepatocellular Carcinoma

Chronic hepatitis B virus (HBV) infection induces dysfunction of immune response and chronic liver damage. However, the mechanisms that account for HBV-related hepatocellular carcinoma (HCC) are poorly understood. The aim of present study was to investigate the modulatory role of interleukin (IL)-35, an immunosuppressive cytokine, to IL-9-secreting T cells in hepatitis B-related HCC. Twenty-two HBV-related HCC patients, twenty-seven chronic hepatitis B (CHB) patients, and eleven controls were enrolled. Serum IL-35 and IL-9 concentration was measured by ELISA. Peripheral and liver-infiltrating non-specific and HBV-specific Th9 and Tc9 cells were assessed by flow cytometry. The regulatory activity of IL-35 to peripheral and liver-infiltrating Th9 cells was assessed in co-culture system between CD8⁺ T cells and HepG2.2.15 cells. Serum IL-35 was up-regulated, while IL-9 was down-regulated in HBV-related HCC patients compared with in CHB patients and controls. Peripheral non-specific and HBV-specific Th9 cells, but not Tc9 cells, were decreased in HBV-related HCC patients. Liver-infiltrating non-specific and HBV-specific Th9 cells were also reduced in HCC tumor sites. CD8⁺ T cells from CHB and HBV-related HCC patients revealed decreased cytotoxicity compared with those from controls. Autologous Th9 cells mediated the elevation of CD8⁺ T cell cytotoxicity, and this process was depending on IL-9 secretion. Recombinant IL-35 stimulation inhibited IL-9 secretion and PU.1 mRNA expression in non-specific and HBV-specific Th9 cells, leading to the suppression of Th9-mediated CD8⁺ T cell cytotoxicity in CHB and HBV-related HCC patients. Our current data indicated that IL-35 might dampen non-specific and HBV-specific Th9 cells activity in HBV-related HCC patients.

Epigenetic DNA Methylation of EBI3 Modulates Human Interleukin-35 Formation via NFkB Signaling: A Promising Therapeutic Option in Ulcerative Colitis

Ulcerative colitis (UC), a severe chronic disease with unclear etiology that is associated with increased risk for colorectal cancer, is accompanied by dysregulation of cytokines. Epstein–Barr virus-induced gene 3 (EBI3) encodes a subunit in the unique heterodimeric IL-12 cytokine family of either pro- or anti-inflammatory function. After having recently demonstrated that upregulation of EBI3 by histone acetylation alleviates disease symptoms in a dextran sulfate sodium (DSS)-treated mouse model of chronic colitis, we now aimed to examine a possible further epigenetic regulation of EBI3 by DNA methylation under inflammatory conditions. Treatment with the DNA methyltransferase inhibitor (DNMTi) decitabine (DAC) and TNFα led to synergistic upregulation of EBI3 in human colon epithelial cells (HCEC). Use of different signaling pathway inhibitors indicated NFκB signaling was necessary and proportional to the synergistic EBI3 induction. MALDI-TOF/MS and HPLC-ESI-MS/MS analysis of DAC/TNFα-treated HCEC identified IL-12p35 as the most probable binding partner to form a functional protein. EBI3/IL-12p35 heterodimers (IL-35) induce their own gene upregulation, something that was indeed observed in HCEC cultured with media from previously DAC/TNFα-treated HCEC. These results suggest that under inflammatory and demethylating conditions the upregulation of EBI3 results in the formation of anti-inflammatory IL-35, which might be considered as a therapeutic target in colitis.

Elevated levels of interleukin-35 and interleukin-37 in adult patients with obstructive sleep apnea

Background

Systemic inflammation has a critical role in the pathogenesis of obstructive sleep apnea (OSA). Interleukin (IL)‐35 and IL‐37 have been identified as novel immune‐modulating cytokines with anti‐inflammatory activities in numerous types of inflammatory disease. The present study aimed to examine the serum levels of IL‐35 and IL‐37 in patients with OSA, and to investigate their associations with the severity of OSA.

Methods

A total of 97 patients, including 67 cases of OSA and 30 age‐ and gender‐matched healthy control subjects, were enrolled in the present study. All subjects were evaluated by overnight polysomnography. Serum IL‐35, IL‐37, and pro‐inflammatory cytokine IL‐1β levels were examined by ELISA.

Results

Compared with those in the control subjects, serum IL‐35, IL‐37, and IL‐1β levels were significantly elevated in patients with mild, moderate, or severe OSA. Furthermore, a severity‐dependent increase in serum IL‐35 and IL‐37 levels was observed in patients with OSA. IL‐35 and IL‐37 levels were positively correlated with the apnea‐hypopnea index (r = 0.742 and 0.578, respectively; both p < 0.001), while they were negatively correlated with the mean oxygen saturation (r = −0.461 and −0.339, respectively; both p < 0.001) and lowest oxyhaemoglobin saturation (r = −0.616 and −0.463, respectively; both p < 0.001) in patients with OSA. In addition, a positive correlation was observed between IL‐35 or IL‐37 and IL‐1β levels (all p < 0.001).

Conclusion

The serum levels of IL‐35 and IL‐37 were significantly increased in patients with OSA and associated with the severity of OSA, implying that IL‐35 and IL‐37 may have a protective role in OSA by counteracting inflammatory responses.

Altered CD4+ T cell and cytokine levels in peripheral blood and skin samples from systemic sclerosis patients and IL35 in CD4+ T cell growth

OBJECTIVE

This study explored the role of IL-35 in CD4+ T lymphocyte and skin fibroblast (HSF) activity and cytokine levels in systemic sclerosis.

METHODS

Blood and skin biopsies were collected from 41 patients and 39 healthy controls to assess CD4+ T lymphocytes and IL-35-related factors. CD4+ T lymphocytes were co-cultured with HSFs, rhIL-35, and IL-35 mAb to evaluate the cell viability, activation of CD4+T lymphocytes, and HSF cells.

RESULTS

The proportion of blood Th1/Th2 was lower and Th17/regulatory T cells (Treg) were higher in patients than in controls (p < 0.05). IL-35 and IL-17A levels were higher and IFN-γ, IL-10, and TGF-β levels were lower in patients than in controls. IL-17A, FoxP3, TGF-β1, and COL-1 mRNA and p-STAT1 and p-STAT4 were higher in skin tissues from patients than in those from controls (p < 0.05). IL-6 levels were higher, whereas IL-10 levels were lower in cell culture supernatants. α-SMA and COL-1 proteins and Ki67 positivity were higher in CD4+ T + HSF cells from patients than in those from controls. rhIL-35 treatment inhibited proliferation (p < 0.001), but increased IL-10 and decreased IL-17A, α-SMA, and COL-1 secretion into the conditioned medium of CD4+ T lymphocytes + HSFs from patients compared with those from controls. IL-35 mAb blocked the effects of IL-35 in CD4+ T + HSF cells (p < 0.05).

CONCLUSIONS

IL-35 plays an inhibitory role in CD4+ T lymphocyte proliferation but induces Treg cell differentiation by STAT1 signalling activation, HSF proliferation, and collagen expression in systemic sclerosis.

Elevated M-MDSCs in Circulation Are Indicative of Poor Prognosis in Diffuse Large B-Cell Lymphoma Patients

Myeloid-derived suppressor cells (MDSCs) are defined as negative regulators that suppress the immune response through a variety of mechanisms, which usually cluster in cancer, inflammation, and autoimmune diseases. This study aims to investigate the correlation between M-MDSCs and the clinical features of diffuse large B-cell lymphoma (DLBCL) patients, as well as the possible accumulation mechanism of M-MDSCs. The level of M-MDSCs is significantly increased in newly diagnosed and relapsed DLBCL patients. Regarding newly diagnosed DLBCL patients, the frequency of M-MDSCs is positively correlated with tumor progression and negatively correlated with overall survival (OS). More importantly, the level of M-MDSCs can be defined as a biomarker for a poor prognosis in DLBCL patients. Additionally, interleukin-35 (IL-35) mediates the accumulation of M-MDSCs in DLBCL patients. Anti-IL-35 treatment significantly reduces levels of M-MDSCs in Ly8 tumor-bearing mice. Thus, M-MDSCs are involved in the pathological process of DLBCL. Targeting M-MDSCs may be a promising therapeutic strategy for the treatment of DLBCL patients.

IL-35: A Novel Immunomodulator in Hepatitis B Virus-Related Liver Diseases

Chronic hepatitis B virus (HBV) infection is a risk factor for liver cirrhosis (LC) and hepatocellular carcinoma (HCC), however, little is known about the mechanisms involved in the progression of HBV-related diseases. It has been well acknowledged that host immune response was closely related to the clinical outcomes of patients with HBV infection. As the factors closely related to the immunomodulatory process, cytokines are crucial in the cell-cell communication and the host responses to HBV infection. Recently, a newly discovered cytokine, designated as interleukin-35 (IL-35), has been proved to be essential for the progression of chronic HBV infection, the development of cirrhosis, the transformation of cirrhosis to HCC, and the metastasis of HCC. Specifically, it showed various biological activities such as inhibiting the HBV-specific cytotoxic T lymphocyte (CTL) proliferation and cytotoxicity, deactivating the immature effector T-cells (Teffs), as well as delaying the proliferation of dendritic cells. It regulated the immune responses by acting as a “brake” on the activation of Teffs, which subsequently played important roles in the pathogenesis of various inflammatory diseases and malignancies. In this review, we focused on the most recent data on the relationship between IL-35 and chronic HBV infection, LC and HCC.

Interleukin-35 Is Involved in Angiogenesis/Bone Remodeling Coupling Through T Helper 17/Interleukin-17 Axis

OBJECTIVE

Osteoporosis is a common metabolic bone disease mainly involving bone remodeling and blood vessels. The current study aimed to explore the suppressive role of interleukin (IL)-35 in nuclear factor kappa-B ligand receptor activator (RANKL) and macrophage colony stimulating factor (M-CSF)-induced osteoclastogenesis and angiogenesis in osteoclasts.

METHODS

Osteoclasts differentiation were induced by incubation of mouse leukemic monocyte/macrophage cell line RAW264.7 cells in the presence of RANKL and M-CSF and was assessed with tartrate-resistant acid phosphatase (TRAP) staining assay. The viability and apoptosis of RAW264.7 was measured using CCK-8 assay and flow cytometry, respectively. The expression of angiogenic genes and proteins were measured using RT-PCR, Western blots and ELISA. The inhibition of Th17/IL-17 axis was examined using plumbagin, which was demonstrated as an IL-17A related signaling pathway inhibitor.

RESULTS

IL-35 inhibited the viability of RAW264.7 cells and promoted the apoptosis of RAW264.7 cells in a dose-dependent manner. Furthermore, IL-35 dose-dependently suppressed the expression of angiogenic markers including VEGF and its receptor. The suppressive effect of IL-35 was confirmed through the activation of Th17/IL-17 axis.

CONCLUSIONS

We demonstrated for the first time the immuno-suppressive function of IL-35 on RANKL and M-CSF-induced osteoclastogenesis and angiogenesis through Th17/IL-17 axis. Therapeutic approach involving augmentation of IL-35 regulatory response may serve as a novel treatment option for osteoporosis, especially by suppressing bone resorption and angiogenesis.

IL35 predicts prognosis in gastric cancer and is associated with angiogenesis by altering TIMP1, PAI1 and IGFBP1

Tumor angiogenesis is required for tumor growth and metastasis. Interleukin‐35 (IL35), a member of the IL12 family, is a dimer composed of IL12A and EBV‐induced gene 3（EBI3）. Elevated plasma IL35 levels have been reported to be associated with the occurrence and development of tumors. However, the role of IL35 in the angiogenesis of gastric cancer (GC) is still unclear. Here, we report that expression of IL35 is correlated with higher microvessel density, distant metastasis and poor prognosis in GC. Moreover, in vitro tube formation assays were performed to show that IL35 may contribute to the tube formation abilities of human umbilical vein endothelial cells. IL12A was observed to be the dominant subunit in promotion of tube formation. IL12A also inhibited expression of tissue inhibitor of metalloproteinase 1 and enhanced expression of plasminogen activator inhibitor 1 and insulin‐like growth factor‐binding protein 1 in a GC cell line. In conclusion, our data suggest that IL35 is involved in angiogenesis and is associated with poor prognosis for GC.

Interleukin-35 has a tumor-promoting role in hepatocellular carcinoma

Hepatic inflammatory response is a risk factor for liver cancer initiation and progression. Interleukin (IL)-35 is the newest member of the IL-12 cytokine family, and has been reported to play an essential role in the immunosuppressive liver microenvironment. Herein we focus on the expression profiles of IL-35 in hepatocellular carcinoma (HCC) and effects on local immune status. HCC transcriptome array data were downloaded from Gene Expression Omnibus (GEO). Analysis was performed by BRB-Array Tools and Ingenuity Pathway Analysis (IPA) software. Serum IL-35 level was detected by AimPlet bead-based immunoassay. In-situ IL-35 detection was performed by immunohistochemical staining and Western blot. The n-vitro effect of IL-35 on CD4⁺ or CD8⁺ T cell function was detected by flow cytometry. Our results showed that there were large amounts of IL-35 expressed in HCC serum and tumor tissues. IL-35 expression affects the transcript of thousands of genes, most differentially expressed genes (DEGs), in tumor tissues correlated with T cell immunity. The IL-35 high-expression group exhibited enhancement of regulatory T cells (T_regs ) and impairment of cytolytic T cells. In-vitro experiments proved that exogenous IL-35 stimulated the expression of programmed cell death 1 (PD-1) and lymphocyte activation gene-3 (LAG3) in CD4⁺ and CD8⁺ T cells. In addition, the stimulating effect was time-dependent. Furthermore, IL-35 inhibited interferon (IFN)-γ secretion by CD4⁺ and CD8⁺ T cells. Elevated IL-35 had an immune suppressive role in HCC tumor microenvironments through affecting inhibitor receptor expression and cytokine secretion of CD4⁺ and CD8⁺ T cells. Dissection of the precise targets and underlying molecular mechanisms would mean alternative treatments for HCC patients.

Serum level of interleukin-35 as a potential prognostic factor for gastric cancer

AIMS

Interleukin-35 (IL-35), a novel anti-inflammatory cytokine, has recently been implicated in tumor development, progression, and survival. However, the relationship between serum IL-35 levels and gastric cancer (GC) is inconclusive. Here, we performed this study to clarify the role of serum level of IL-35 in GC patients.

METHODS

We enrolled 180 GC patients and 170 healthy controls and used enzyme-linked immunosorbent assay to detect serum IL-35 levels. The clinical relevance between IL-35 and clinical pathology parameters was assessed. Univariate and multivariate logistic regressions were used to determine the feasibility of IL-35 as a clinical biomarker.

RESULTS

We observed that serum IL-35 levels were significantly higher in GC patients (17.559 ± 13.266 pg/mL) than in healthy controls (8.077 ± 3.801 pg/mL, P < .001). High serum IL-35 levels were significantly associated with clinical stage (P = .048) and Helicobacter pylori (HP) infection (P < .001). The Kaplan-Meier survival analysis indicated that patients in the high-IL-35 group had poor overall survival (OS) and progression-free survival (PFS) (median OS: 26.0 vs 36.0 months, P < .001; median PFS: 18.0 vs.26.0 months, P = .044). Multivariate analyses demonstrated that serum IL-35 was an independent prognostic factor for GC (OS: hazard ratio [HR] = 1.031 [95% CI, 1.017-1.045], P < .001; PFS: HR = 1.029 [95% CI, 1.015-1.043], P < .001).

CONCLUSIONS

High serum IL-35 levels are associated with poor disease prognosis in GC patients, and it may be become a new and promising biomarker for prognosis of gastric cancer.

[The expression and significance of interleukin-35 receptor in oral lichen planus]

OBJECTIVE

To investigate the expression of glycoprotein 130 (gp130) and interleukin 12 receptor β2 (IL-12Rβ2) in two subunits of interleukin-35 receptor (IL-35R), singal transducer and activator of transcription (STAT) 1 and STAT4 in oral lichen planus (OLP) tissues, and to explore the role and significance of IL-35R in the formation and development of OLP lesions.

METHODS

Totally 41 samples of OLP tissues (OLP group) and 15 samples of normal oral mucosa (control group) were collected. The expression levels of gp130, IL-12Rβ2, STAT1, STAT4 mRNA in the tissues were detected by real-time fluorescent quantitative polymerase chain reaction and the distribution and expression of protein gp130 and IL-12Rβ2 were detected by immunohistochemistry. The potential relationship between gp130 and IL-12Rβ2 and clinical features of OLP was analyzed.

RESULTS

1) The expression levels of gp130, IL-12Rβ2, STAT1 and STAT4 mRNA in the OLP group were significantly higher than those in the control group (P<0.05). 2) The positive expression rates of gp130 and IL-12Rβ2 protein in the OLP group were higher than those in the control group (P<0.05). The expression of gp130 and IL-12Rβ2 proteins in OLP tissues were positively correlated (r=0.984, P<0.001). 3) The expression rates of gp130 and IL-12Rβ2 protein in erosive OLP tissues were significantly higher than those in non-erosive ones (P<0.05).

CONCLUSIONS

The expression of IL-35R and STAT is up-regulated in OLP tissues, and the expression of IL-35R is related to the clinical classification of OLP, suggesting that IL-35R might play an important role in the formation and development of damage OLP lesions.

Evaluation of Transforming Growth Factor-β1 and Interleukin-35 Serum Levels in Patients with Placenta Accreta

OBJECTIVE

Placenta accreta is a pregnancy-related disorder with extreme trophoblast invasion and the adherence of the placenta to the uterine wall. This study aimed to investigate the serum level of transforming growth factor-beta 1 (TGF-β1) and interleukin (IL)-35 in patients with placenta accreta.

METHODS

Thirty-one women with placenta accreta and 57 healthy pregnant women were enrolled. The serum levels of TGF-β1 and IL-35 were measured using the enzyme-linked immunosorbent assay method.

RESULTS

The serum levels of both TGF-β and IL-35 were significantly higher in the placenta accreta group compared with the group of healthy women (1082.48 pg/mL vs 497.33 pg/mL and 4541.14 pg/mL vs 1306.04 pg/mL; P <.001, respectively). Moreover, the level of TGF-β1 positively correlated with the IL-35 level but other factors such as age, gestations, live births, and abortions did not correlate with IL-35 and TGF-β1 levels.

CONCLUSION

The serum levels of IL-35 and TGF-β1 may contribute to the pathogenesis of placenta accreta and could be considered as potential targets in clinical and diagnostic approaches.

Adalimumab and methotrexate affect the concentrations of regulatory cytokines (interleukin-10, transforming growth factor-β1, and interleukin-35) in patients with plaque psoriasis

Dysfunctional regulatory T lymphocytes are important for the pathogenesis of psoriasis and atherosclerosis. We analyzed the severity of atherosclerosis and the concentration of regulatory cytokines in patients with psoriasis who were administered methotrexate or adalimumab for 12 weeks. We included 34 patients with psoriasis (17 each, administered methotrexate or adalimumab) and eight healthy volunteers. BMI, psoriasis area and severity index (PASI), body surface area (BSA), and at least 75% and 90% improvements in PASI were observed. The 10-year risk of fatal cardiovascular disease was estimated using Systematic Coronary Risk Evaluation charts. The plasma interleukin (IL)-10, IL-35, and transforming growth factor β1 (TGF-β1) levels were determined using enzyme-linked immunosorbent assay before and after the 12-week treatment regimen. PASI (P = .0006) and BSA (P = .0001) were positively correlated with the BMI, IL-35 (-0.38), and IL-10 (0.48) levels. Baseline IL-35 concentrations were the highest in healthy volunteers; the IL-10 and TGF-β1 level were the highest in the methotrexate group. IL-10 concentration decreased in both treatment groups (P = .02 for the methotrexate and P = .09 for adalimumab group), and IL-35 decreased in the adalimumab group (P = .019), consistent with skin lesion recovery. Thus, this study demonstrates the dysregulated secretion of regulatory cytokines in psoriatic patients under systemic treatment.

Interleukin-35 regulates the balance of Th17 and Treg responses during the pathogenesis of connective tissue diseases

Interleukin (IL)-35 belongs to the IL-12 cytokine family and is a heterodimer of the p35 and Epstein-Barr virus-induced gene 3 (EBI3) subunits. Functionally, IL-35 can promote the proliferation and activation of regulatory T cells (Tregs) and suppress the function of T helper 17 (Th17) cells and other inflammatory cells to inhibit immune responses. In recent years, an abnormal IL-35 expression causing a Th17/Treg imbalance has been associated with the development and progression of several connective tissue diseases (CTDs), such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), dermatomyositis (DM)/polymyositis (PM), and primary Sjögren's syndrome (pSS). Here, we review the role of IL-35 in regulating the balance of Th17/Treg responses in different types of CTDs and provide new insights into the role of IL-35 in these diseases.

PD-L1 Is Expressed and Promotes the Expansion of Regulatory T Cells in Acute Myeloid Leukemia

Intratumoral accumulation of CD4⁺CD25⁺Foxp3⁺ regulatory T (Treg) cells occurs in acute myeloid leukemia (AML), but little is known about the role of tumor cells themselves in this process. Here, we showed that an immune checkpoint PD-L1 expressed by AML cells promoted the conversion and expansion of Treg cells sustaining high expression of Foxp3 and PD-1 as well as a suppressive function. Furthermore, an AML cell line HEL overexpressed PD-L1 promoted the conversion and expansion of Treg cells and CD4⁺PD-1⁺Foxp3⁺ T (PD-1⁺Treg) cells from the conventional CD4⁺ T cells. CD4⁺CD25^highPD-1⁺ T cells secreted more IL-10 production than CD4⁺CD25^highPD-1⁻ T cells. IL-35, another cytokine secreted by Treg cells, promoted the proliferation of HL-60 cells and enhanced chemoresistance to cytarabine. Blockade of PD-1 signaling using anti-PD-L1 antibody dramatically impaired the generation of Treg cells and sharply retarded the progression of a murine AML model injected with C1498 cells. The frequency of intratumoral PD-1⁺ Treg cells was capable of predicting patient survival in patients with AML. In conclusion, our data suggest that PD-L1 expression by AML cells may directly drive Treg cell expansion as a mechanism of immune evasion and the frequency of PD-1⁺ Treg cells is a potential prognostic predictor in patients with AML.

The effects of phenanthrene exposure on Treg and Th17 cells related cytokines in female rats

Phenanthrene (Phe) female rat model was established to explore the mechanism of Phe on immune impairment. The rats were randomly divided into three groups, including control (C), low (L), and high (H) groups. Phe was supplied to L and H groups at the dose of 180 and 900 mg/kg orally at first day and with the dose of 90 and 450 mg/kg by intraperitoneal injection at the last 2 days. The C group was enriched with the same volume of corn oil. The liver tissue was collected. Then, the protein and mRNA expressions of interleukin (IL)-35 and the concentration IL-17 were detected to evaluate the function of regulatory T cells (Treg cells) and T helper 17 cells (Th17 cells). In addition, IL-1β and interferon-γ (IFN-γ) were analyzed to evaluate the immune impairment. The results showed that the protein and mRNA expressions of IL-35 decreased significantly in H groups (P < 0.05). Meanwhile, there were significant increases in IL-17, IFN-γ and IL-1β in the liver of H group (P < 0.05). This study demonstrated that Phe exposure might be associated with the immune impairment via changing inflammatory mediators including IL-35 and IL-17 in female rats.

Hepatitis B Virus Core Particles Containing a Conserved Region of the G Protein Combined with Interleukin-35 Protected Mice against Respiratory Syncytial Virus Infection without Vaccine-Enhanced Immunopathology

Respiratory syncytial virus (RSV) is the most important cause of lower respiratory tract infection in infants and young children. The vaccine-enhanced disease (VED) has greatly hindered the development of an RSV vaccine. Currently, there are no licensed vaccines for RSV. In this study, immunization of mice with hepatitis B virus core particles containing a conserved region of the G protein (HBc-tG) combined with interleukin-35 (IL-35) elicited a Th1-biased response and a high frequency of regulatory T (Treg) cells and increased the levels of IL-10, transforming growth factor β, and IL-35 production. Importantly, immunization with HBc-tG together with IL-35 protected mice against RSV infection without vaccine-enhanced immunopathology. To explore the mechanism of how IL-35 reduces lung inflammation at the gene expression level, transcription profiles were obtained from lung tissues of immunized mice after RSV infection by the Illumina sequencing technique and further analyzed by a systems biology method. In total, 2,644 differentially expressed genes (DEGs) were identified. Twelve high-influence modules (HIMs) were selected from these DEGs on the basis of the protein-protein interaction network. A detailed analysis of HIM10, involved in the immune response network, revealed that Il10 plays a key role in regulating the host response. The selected DEGs were consistently confirmed by quantitative real-time PCR (qRT-PCR). Our results demonstrate that IL-35 inhibits vaccine-enhanced immunopathology after RSV infection and has potential for development in novel therapeutic and prophylactic strategies.IMPORTANCE In the past few decades, respiratory syncytial virus (RSV) has still been a major health concern worldwide. The vaccine-enhance disease (VED) has hindered RSV vaccine development. A truncated hepatitis B virus core protein vaccine containing the conserved region (amino acids 144 to 204) of the RSV G protein (HBc-tG) had previously been shown to induce effective immune responses and confer protection against RSV infection in mice but to also lead to VED. In this study, we investigated the effect of IL-35 on the host response and immunopathology following RSV infection in vaccinated mice. Our results indicate that HBc-tG together with IL-35 elicited a balanced immune response and protected mice against RSV infection without vaccine-enhanced immunopathology. Applying a systems biology method, we identified Il10 to be the key regulator in reducing the excessive lung inflammation. Our study provides new insight into the function of IL-35 and its regulatory mechanism of VED at the network level.

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.

IL-35 and RANKL Synergistically Induce Osteoclastogenesis in RAW264 Mouse Monocytic Cells

Interleukin (IL)-35 is an immunosuppressive cytokine mainly produced by regulatory T cells. IL-35 mediates immunological functions by suppressing the inflammatory immune response. However, the role of IL-35 in bone-destructive diseases remains unclear, especially in terms of osteoclastogenesis. Therefore, the current study investigated the synergistic effect of IL-35 on osteoclastogenesis that is involved the pathogeneses of periodontitis and rheumatoid arthritis. Osteoclastic differentiation and osteoclastogenesis of RAW264 (RAW) cells induced by receptor activator of nuclear factor (NF)-κB ligand (RANKL) and IL-35 were evaluated by tartrate-resistant acid phosphate staining, hydroxyapatite resorption assays, and quantitative polymerase chain reaction. The effect of IL-35 on RANKL-stimulated signaling pathways was assessed by Western blot analysis. Costimulation of RAW cells by RANKL and IL-35 induced osteoclastogenesis significantly compared with stimulation by RANKL alone. Phosphorylations of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase tended to be increased by RANKL and IL-35 compared with RANKL or IL-35 alone. Additionally, the osteoclastogenesis induced by RANKL and IL-35 was suppressed by inhibition of ERK. In this study, IL-35 and RANKL induced osteoclastogenesis synergistically. Previous reports have shown that IL-35 suppresses the differentiation of osteoclasts. Therefore, IL-35 might play dual roles of destruction and protection in osteoclastogenesis.

Lower serum interleukin-22 and interleukin-35 levels are associated with disease status in neuromyelitis optica spectrum disorders

AIMS

The exact pathogenesis of neuromyelitis optica spectrum disorder (NMOSD) remains unclear. A variety of cytokines are involved, but few studies have been performed to explore the novel roles of interleukin-22 (IL-22) and interleukin-35 (IL-35) in NMOSD. Therefore, this study was designed to investigate serum levels of IL-22 and IL-35, and their correlations with clinical and laboratory characteristics in NMOSD.

METHODS

We performed a cross-section study, 18 patients with acute NMOSD, 23 patients with remission NMOSD, and 36 healthy controls were consecutively enrolled. Serum levels of IL-22 and IL-35 were measured by enzyme-linked immunosorbent assay (ELISA). The correlations between serum IL-22 and IL-35 levels and clinical and laboratory characteristics were evaluated by Spearman's rank or Pearson's correlation coefficient.

RESULTS

The serum levels of IL-22 and IL-35 were significantly lower in patients with acute NMOSD and remission NMOSD than in healthy controls (IL-22: 76.96 ± 13.62 pg/mL, 87.30 ± 12.79 pg/mL, and 94.02 ± 8.52 pg/mL, respectively, P < .0001; IL-35: 45.52 ± 7.04 pg/mL, 57.07 ± 7.68 pg/mL, and 60.05 ± 20.181 pg/mL, respectively, P < .0001). Serum levels of IL-35 were negatively correlated with EDSS scores and cerebrospinal fluid protein levels (r = -.5438, P = .0002 and r = -.3523, P = .0258, respectively) in all patients.

CONCLUSIONS

Lower serum levels of IL-22 and IL-35 are associated with disease status in NMOSD. Additionally, lower serum levels of IL-35 are associated with disease severity in NMOSD.

Interleukin-35 reduces inflammation in acute lung injury through inhibiting TLR4/NF-κB signaling pathways

Acute lung injury (ALI) in children is a complex disease that is accompanied by an inflammatory response. The pathogenesis of ALI in children is not yet well understood. Mice with ALI exhibit inflammation of the lungs and decreased expression of interleukin (IL)-35. To investigate whether the function of IL-35 affects lipopolysaccharide (LPS)-induced ALI, IL-35 was overexpressed in cells. Enzyme-linked immunosorbent assays indicated decreased levels of IL-6 and tumor necrosis factor-α in LPS-induced and agomir-IL-35-treated murine RAW264.7 macrophages. Finally, toll-like receptor 4 (TLR4)/NF-κB signaling pathways were analyzed. The expression of TLR4, NF-κB p65 and NF-κB p50 were decreased, as was the degradation of NF-κB inhibitor-α, in LPS-induced and agomir-IL-35-treated murine RAW264.7 macrophages. The results of the present study demonstrated that IL-35 may exhibit a protective role in ALI by modulating the TLR4/NF-κB signaling pathways.

Interleukin-35 suppresses antitumor activity of circulating CD8+ T cells in osteosarcoma patients

Purpose/Aim of the study: Interleukin (IL)-35 is a newly identified IL-12 cytokine family member and reveals immunosuppressive activity to CD8⁺ T cells in inflammation, infectious diseases, and cancers. However, little is known regarding IL-35 function in osteosarcoma. Thus, the aim of the current study was to investigate the regulatory function of IL-35 to CD8+ T cells in osteosarcoma. Materials and methods: Thirty-five osteosarcoma patients and 20 healthy individuals were enrolled. Serum CD4⁺CD25⁺CD127^dim/- regulatory T cells (Tregs) and CD8⁺ T cells were purified. IL-35 concentration in serum and cultured supernatants was measured by enzyme-linked immunosorbent assay. Osteosarcoma cell line MG-63 cells and CD8⁺ T cells were stimulated with recombinant IL-35 in vitro, and modulatory function of IL-35 on these cells was assessed by investigation of cellular proliferation, cell cycle, apoptosis, and cytokine production. Results: Serum IL-35 and Treg-secreting IL-35 were significantly elevated in osteosarcoma patients. IL-35 stimulation did not affect proliferation, apoptosis, or cell cycle of MG-63 cells. Purified peripheral CD8⁺ T cells from osteosarcoma patients revealed dysfunctional property, which presented as decreased mRNA expressions for perforin, granzyme B, and granulysin, as well as reduced cytolytic (direct lysis of target MG-63 cells) and noncytolytic (interferon-γ and tumor necrosis factor-α production) function in coculture systems. Moreover, IL-35 stimulation further diminished cytolytic and noncytolytic activity of CD8⁺ T cells from osteosarcoma patients. Conclusions: The current data indicated that IL-35 contributed to CD8⁺ T-cell dysfunction and limited antitumor immune response in osteosarcoma.

Interleukin-35 Dampens CD8+ T Cells Activity in Patients With Non-viral Hepatitis-Related Hepatocellular Carcinoma

Interleukin (IL)-35 is a newly identified IL-12 cytokine family member, which has been demonstrated to induce immunotolerance by suppression of CD8⁺ T cells function in chronic viral hepatitis. However, the role of IL-35 in modulating CD8⁺ T cells activity in non-viral hepatitis-related hepatocellular carcinoma (HCC) was not fully elucidated. Forty-four patients with non-viral hepatitis-related HCC and 20 healthy individuals were enrolled. Serum IL-35 concentration was measured by ELISA. CD8⁺ T cells were purified from peripheral bloods and liver tissues. mRNA expression of cytotoxic/inhibitory molecules in CD8⁺ T cells with IL-35 stimulation was semi-quantified by real-time PCR. Direct and indirect contact co-culture systems of CD8⁺ T cells and HCC cell lines were set up. The modulatory function of IL-35 on peripheral and liver-resident CD8⁺ T cells was assessed by measurement of lactate dehydrogenase release and cytokine production in the co-culture supernatants. Serum IL-35 was notably elevated in HCC patients, while effective anti-tumor therapies down-regulated IL-35 concentration. Recombinant IL-35 stimulation suppressed cytotoxicity and proinflammatory cytokine secretion of peripheral and liver-resident CD8⁺ T cells in direct and indirect contact co-culture systems. This process was accompanied by reduction of perforin expression and interferon-γ production, as well as programmed death-1 and cytotoxic T-lymphocyte-associated protein 4 elevation in CD8⁺ T cells. The current data suggested that IL-35 inhibited both cytolytic and non-cytolytic function of CD8⁺ T cells to non-viral hepatitis-related HCC probably via repression of perforin expression. IL-35 might be considered to be one of the therapeutic targets for patients with HCC.

Interleukin-35 in immune-related diseases: protection or destruction

Interleukin-35 (IL-35) is a recently identified heterodimeric cytokine in the IL-12 family. It consists of an IL-12 subunit α chain (P35) and IL-27 subunit Epstein-Barr virus-induced gene 3 (EBI3) β chain. Unlike the other IL-12 family members, it signals through four unconventional receptors: IL-12Rβ2-IL-27Rα, IL-12Rβ2-IL-12Rβ2, IL-12Rβ2-GP130, and GP130-GP130. Interleukin-35 signaling is mainly carried out through the signal transducer and activator of transcription family of proteins. It is secreted not only by regulatory T (Treg) cells, but also by CD8+ Treg cells, activated dendritic cells and regulatory B cells. It exhibits immunosuppressive functions distinct from those of other members of the IL-12 family; these are mediated primarily by the inhibition of T helper type 17 cell differentiation and promotion of Treg cell proliferation. Interleukin-35 plays a critical role in several immune-associated diseases, such as autoimmune diseases and viral and bacterial infections, as well as in tumors. In this review, we summarize the structure and function of IL-35, describe its role in immune-related disorders, and discuss the mechanisms by which it regulates the development and progression of diseases, including inflammatory bowel disease, collagen-induced arthritis, allergic airway disease, hepatitis, and tumors. The recent research on IL-35, combined with improved techniques of studying receptors and signal transduction pathways, allows for consideration of IL-35 as a novel immunotherapy target.

Association between Interleukin 35 Gene Single Nucleotide Polymorphisms and Systemic Lupus Erythematosus in a Chinese Han Population

Interleukin-35 (IL-35) exerts crucial roles in the pathogenesis and development of systemic lupus erythematosus (SLE), in this study we aim to explore the associations between IL-35 gene polymorphisms and the susceptibility, clinical features and plasma IL-35 levels of SLE patients, respectively. 490 SLE patients and 489 healthy controls were recruited in our study. The correlations between the polymorphisms of seven SNPs of IL-35 encoding gene and the susceptibility, main clinical manifestations of SLE were evaluated, respectively. Plasma IL-35 levels were assessed in 76 SLE patients, and the associations between plasma IL-35 levels and the polymorphisms of genotyped SNPs were explored. There were significant associations between the polymorphisms of rs4740 and the occurrence of renal disorder, hematological disorder in SLE patients, respectively (p = 0.001; p = 0.001). In addition, there were no significant associations observed between the genotype frequencies of genotyped SNPs and the risk of SLE, plasma IL-35 levels, respectively. The polymorphism of rs4740 of IL-35 encoding gene is associated with the occurrence of renal disorder and hematological disorder of SLE patients.

EB1-3 Chain of IL-35 Along With TGF-β Synergistically Regulate Anti-leishmanial Immunity

Immunosuppression is a characteristic feature of chronic leishmaniasis. The dynamicity and the functional cross talks of host immune responses during Leishmania infection are still not clearly understood. Here we explored the functional aspects of accumulation of immune suppressive cellular and cytokine milieu during the progression of murine visceral leishmaniasis. In addition to IL-10 and TGF-β, investigation on the responses of different subunit chains of IL-12 family revealed a progressive elevation of EBI-3 and p35 chains of IL-35 with Leishmania donovani infection in BALB/c mice. The expansion of CD25 and FoxP3 positive T cells is associated with loss of IFN-γ and TNF-α response in advanced disease. Ex-vivo and in vivo neutralization of TGF-β and EBI-3 suggests a synergism in suppression of host anti-leishmanial immunity. The down-regulation of EBI-3 and TGF-β is crucial for re-activation of JAK-STAT pathway for induction as well as restoration of protective immunity against L. donovani infection.

Serum interleukin-35 and pentraxin-3 levels in patients with mild acute pancreatitis

Introduction

Interleukin-35 (IL-35) is a newly defined potent anti-inflammatory cytokine that is predominantly produced by regulatory T cells, and pentraxin-3 belongs to the acute-phase proteins.

Aim

To measure the serum IL-35 and pentraxin-3 levels in the early phase of mild acute pancreatitis (AP).

Material and methods

Eighty-three patients with mild AP and 30 healthy controls were included in the study. The serum levels of IL-35 and pentraxin-3 were measured by enzyme-linked immunosorbent assay upon admission and at the 48^th hour after diagnosis.

Results

The mean value of serum IL-35 levels in patients with mild acute pancreatitis at admission was 5.91 ng/ml (4.21–7.90) and was significantly lower than those in healthy controls (25.53 ng/ml (12.79–54.73, p < 0.001)) and 48-hour value were (6.79 ng/ml (4.42–9.62) (p = 0.015)). The mean value of serum pentraxin-3 levels in patients at the time of admission was 6.75 ng/ml (4.42–9.62) and there was no significant difference from healthy controls, at 7.64 ng/ml (6.58–8.62, p > 0.05). Also there was no significant difference between the mean value at admission and the mean value at 48-hour, 6.75 ng/ml (4.74–9.06, p > 0.05).

Conclusions

Interleukin-35 can be used in diagnosis and follow-up in patients with mild AP.

Interleukin-35 is associated with the tumorigenesis and progression of prostate cancer

Interleukin (IL)-35 is a novel member of the IL-12 cytokine family, which exhibits a unique immune regulatory function. Previously, it was demonstrated that IL-35 expression is significantly increased in a wide range of tumor tissues, promoting angiogenesis and inhibiting the anti-tumor immune response. In the present study, the IL-35 protein expression levels were measured in the plasma and tumor tissue of patients with prostate cancer (PCA), and its role was determined in the occurrence and progression of PCA. Plasma IL-35 expression levels were measured using ELISA, and the associations of plasma IL-35 and clinicopathological parameters were analyzed. Receiver operating characteristic curves were plotted to analyze the role of IL-35 as a clinical biomarker for the diagnosis of PCA. Survival curve analysis demonstrated a significant decrease in the survival time in months in patients with PCA and increased expression levels of IL-35 compared with the participants with relatively lower IL-35 protein expression levels. IL-35 expression was detected using immunohistochemical staining of a human PCA tissue microarray. Plasma IL-35 expression levels in the patients with PCA were significantly increased compared with the patients with benign prostatic hyperplasia and the healthy controls. An increase in the plasma concentration of IL-35 was associated with progression of PCA stage and an increase in the Gleason score. Significant differences in AUCs for IL-35 and prostate-specific antigen were observed with regard to the presence of lymph node and distant metastases in patients with PCA. The expression levels of Epstein-barr virus-induced gene 3 (EBI3) and IL-12A (p35; the subunits which together form IL-35) were significantly increased in the tumor tissue compared with the adjacent normal tissue. An association was identified between the Gleason score and the expression of EBI3 and p35. Therefore, increased expression of IL-35 in the plasma and tumor tissues may contribute to the progression and metastasis of PCA, and IL-35 may serve as a novel prognostic biomarker or therapeutic target for the treatment of PCA.

Inhibition of cardiac allograft rejection in mice using interleukin-35-modified mesenchymal stem cells

Interleukin-35 (IL-35) is a cytokine recently discovered to play a potent immunosuppressive role by intensifying the functions of regulatory T cells and inhibiting the proliferation and functions of T helper 1 and T helper 17 cells. Mesenchymal stem cells (MSCs) have recently emerged as promising candidates for cell-based immune therapy, and our previous study showed that IL-35 gene modification can effectively enhance the therapeutic effect of MSCs in vitro. In this study, we isolated adipose tissue-derived MSCs in vitro and infected them with lentiviral vectors overexpressing the IL-35 gene, thereby creating IL-35-MSCs. Subsequently, IL-35-MSCs were then injected into mice of the allogeneic heterotopic abdominal heart transplant model to determine their effect on allograft rejection. The results showed that IL-35-MSCs could continuously secrete IL-35 in vivo and in vitro, successfully alleviate allograft rejection and prolong graft survival. In addition, compared to MSCs, IL-35-MSCs showed a stronger immunosuppressive ability and further reduced the percentage of Th17 cells, increased the proportion of CD4⁺ Foxp3⁺ T cells, and regulated Th1/Th2 balance in heart transplant mice. These findings suggest that IL-35-MSCs have more advantages than MSCs in inhibiting graft rejection and may thus provide a new approach for inducing immune tolerance during transplantation.

Clinical and biochemical effects of erbium, chromium: yttrium, scandium, gallium, garnet laser treatment as a complement to periodontal treatment

Objective

The purpose of this study was to investigate the clinical effects of erbium, chromium: yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser treatment as a complementary to scaling and root planning (SRP) during the treatment of chronic periodontitis and gingival crevicular fluid (GCF) interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and interleukin-35 (IL-35) levels.

Materials and Methods

Forty patients with chronic periodontitis were divided into two equal groups at random to receive SRP alone and SRP followed by Er, Cr: YSGG laser treatment, which are control and test groups, respectively. Clinical attachment level (CAL), probing depth (PD), bleeding on probing (BOP), gingival index (GI), and plaque index (PI) were measured for all patients in both groups at baseline and again at the end of the 1^st, 3^rd, and 6^th months following the treatment. Levels of GCF IL-1β, IL-6, and IL-35 were analyzed by enzyme-linked immunosorbent assay.

Results

After periodontal treatment, CAL, PD, BOP, GI, and PI, which are clinical parameters analyzed, decreased significantly (P < 0.05) in both test and control groups. GCF volume, IL-1 β, IL-6, and IL-35, levels in both groups proved statistically significant reductions compared to the baseline (P < 0.05), but no substantial variations were detected among both groups.

Conclusion

According to these results, we can suggest that IL-35 may be related to the pathogenesis of periodontitis and that Er, Cr: YSGG laser can be used as an adjunct to SRP in periodontal treatment.

Decreased regulatory T-cell frequency and interleukin-35 levels in patients with rheumatoid arthritis

Interleukin-35 (IL-35) is a newly discovered anti-inflammatory cytokine predominantly released by regulatory T cells (Tregs) and may serve an important role in the pathogenesis of autoimmune diseases. The levels of IL-35 and corresponding Treg frequencies in patients with rheumatoid arthritis (RA) have scarcely been reported. The present study aimed to detect serum IL-35 levels and Treg frequencies in patients with RA, and analyze their association with each other and with indicators of RA. A total of 55 patients with RA, including 37 active-phase (AP) and 18 chronic-phase (CP) cases, as well as 20 healthy controls (HC), were recruited. Clinical parameters, including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) levels, rheumatoid factor (RF), anti-cyclic citrullinated peptide (CCP) antibody and 28-joint disease activity score (DAS28) were assessed. The Treg frequency in peripheral blood (PB) was determined by flow cytometry. IL-35 mRNA in PB mononuclear cells of the patients with RA was measured by reverse transcription-quantitative polymerase chain reaction analysis, and IL-35 levels in the serum were detected by ELISA. The correlations between IL-35 levels and the abovementioned indexes were analyzed by determining Pearson's correlation coefficient. The results of the present study indicated that the Treg frequency was significantly decreased in patients with RA compared with that in HC. No significant difference in Treg frequency between the AP and CP groups of RA patients was identified. In addition, the serum IL-35 levels and mRNA expression in RA patients were obviously lower than those in the HC. Of note, the serum IL-35 levels were negatively correlated with the ESR and DAS28 of patients with RA, while no correlation with CRP, RF or anti-CCP antibodies was identified. In addition, a significant positive correlation was revealed between serum IL-35 levels and the Treg frequency. These results suggest that IL-35 and Tregs have a protective role regarding the development of RA.

Clinical effects of tanshinone IIA sodium sulfonate combined with trimetazidine and levocarnitine in the treatment of AVMC and its effects on serum TNF-α, IL-18 and IL-35

Clinical effects of tanshinone IIA sodium sulfonate combined with trimetazidine and levocarnitine in the treatment of acute viral myocarditis (AVMC) were investigated. Eighty-six patients with AVMC treated in Dongying City People's Hospital from August 2016 to July 2017 were selected and randomly divided into control group (n=43) and observation group (n=43). Patients in control group were treated with tanshinone IIA sodium sulfonate, while those in observation group were treated with trimetazidine and levocarnitine. The curative effect and improvement in clinical symptoms were compared between the two groups of patients, and enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of heart-type fatty acid-binding protein (H-FABP), creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI) in patients after treatment. Besides, the changes in levels of serum tumor necrosis factor-α (TNF-α), interleukin (IL)-18 and IL-35 were detected via ELISA. The total effective rate of treatment in observation group was significantly higher than that in control group (p<0.05). The improvement in clinical symptoms in observation group was significantly superior to that in control group (p<0.05). After treatment, levels of H-FABP, CK-MB and cTnI in observation group were obviously lower than those in control group (p<0.05). At 3, 5 and 7 days after treatment, the levels of TNF-α and IL-18 in both groups of patients were decreased compared with those before treatment, but the level of IL-35 was increased compared with that before treatment, and changes in observation group were more significant than those in control group (p<0.05). Tanshinone IIA sodium sulfonate combined with trimetazidine and levocarnitine has definite curative effects in the treatment of patients with AVMC, which can alleviate myocardial injury with higher safety, and effectively mitigate the inflammatory response in patients, so it is of great clinical significance.

Interleukin-35 Attenuates D-Galactosamine/Lipopolysaccharide-Induced Liver Injury via Enhancing Interleukin-10 Production in Kupffer Cells

Interleukin (IL) -35 is an anti-inflammatory cytokine which exerts various beneficial effects on autoimmune diseases. However, whether IL-35 plays a role in endotoxin induced hepatitis demands clarification. This study aims to reveal the effect and mechanism of IL-35 on endotoxin induced liver injury. Acute hepatic injury was induced by D-galactosamine (D-GalN, 400 mg/kg) and lipopolysaccharide (LPS, 5 μg/kg) administration in mice. IL-35 treatment ameliorated D-GalN/LPS induced liver injury in a dose dependent manner as shown by histological examination, ALT determination and Caspase-3 activity assay. It also reduced production of pro-inflammatory cytokines, tumor necrosis factor (TNF)-α, IL-1β, and IL-6, and increased production of anti-inflammatory cytokines, IL-4, IL-10, and transforming growth factor (TGF)-β. This hepato-protective effect was proved mainly mediated by Kupffer cells (KC) via gadolinium chloride depletion and cell adoptive transfer experiment. In addition, IL-35 emolliated the cytotoxicity of LPS-triggered KCs to hepatocytes, suppressed nitric oxide (NO) and TNF-α production, and elevated IL-10 production in LPS stimulated KCs. Furthermore, IL-35 could not exert hepato-protective effect in IL-10-deficient mice in vivo and it could not suppress LPS induced NO and TNF-α production in IL-10-deficient KCs in vitro. In conclusion, IL-35 protects endotoxin-induced acute liver injury, which mainly acts thought increasing IL-10 production in KCs. This finding demonstrates a role of IL-35 in anti-infectious immunity and provides a potential therapeutic target in treating fulminant hepatitis.

Increased serum IL-17 and decreased serum IL-10 and IL-35 levels correlate with the progression of COPD

Purpose

This study aimed to measure the serum levels of interleukin (IL)-17, IL-10, and IL-35 in patients with stable chronic obstructive pulmonary disease (COPD) and disclose the correlations between their expression levels and clinical factors of patients.

Methods

A total of 75 patients with stable COPD (47 males and 28 females) and 30 healthy controls (15 males and 15 females) were included in this study. The serum levels of IL-17, IL-10, and IL-35 were determined by enzyme-linked immunosorbent assay. The correlations between their expression levels and clinical factors of patients were determined using linear regression methods.

Results

The serum level of IL-17 was upregulated in stable COPD, and increased IL-17 expression was positively correlated with the Global Initiative for Chronic Obstructive Lung Disease (GOLD) grading, modified Medical Research Council (mMRC) score, and long clinical history (P<0.05), but negatively correlated with the pulmonary function (P<0.05) of patients. The serum levels of IL-10 and IL-35 were downregulated in stable COPD, and decreased IL-10 and IL-35 levels negatively correlated with the smoking status, GOLD grading, mMRC score, and long clinical history (P<0.05), but positively correlated with the pulmonary function (P<0.05) of patients. Moreover, the level of IL-17 negatively correlated with IL-10 and IL-35, but IL-10 positively correlated with IL-35.

Conclusion

The serum levels of IL-17, IL-10, and IL-35 correlated with the clinical factors of COPD, indicating that they can serve as indicators to estimate the progression of COPD.

Diminished circulating concentration of interleukin-35 in Helicobacter pylori-infected patients with peptic ulcer: Its association with FOXP3 gene polymorphism, bacterial virulence factor CagA, and gender of patients

BACKGROUND

IL-35 modulates immune and inflammatory responses during infections. Here, we investigated IL-35 levels and a single nucleotide polymorphism, rs3761548, in FOXP3 gene in Helicobacter pylori-infected patients with peptic ulcer (PU), to clarify possible associations.

MATERIALS AND METHODS

This study includes 100 H. pylori-infected PU patients, 100 H. pylori-infected asymptomatic subjects (AS), and 100 noninfected healthy subjects (NHSs). Serum IL-35 levels and the genotyping were determined using ELISA and RFLP-PCR methods, respectively.

RESULTS

In PU patients, the IL-35 levels were lower than AS and NHS groups (P < .001). The IL-35 levels in CagA⁺ H. pylori-infected participants from PU and AS groups were lower than individuals infected with CagA^- strains (P < .02 and P < .04, respectively). Women had higher IL-35 levels than men among PU, AS, and NHS groups (P < .0001). In PU patients, AA genotype and A allele at rs3761548 were more frequent than total healthy subjects (AS + NHS groups) and associated with an increased PU risk (AA genotype: OR = 5.51, P < .0001; A allele: OR = 3.857, P < .002). In PU and AS groups, IL-35 levels were lower in subjects displaying AA genotype or A allele than subjects displaying CC genotype or C allele, respectively (P < .0001 and P < .03 for PU patients; P < .001 and P < .02 for AS group, respectively).

CONCLUSIONS

Decreased IL-35 levels could be involved in PU development in H. pylori-infected individuals. IL-35 levels are affected by CagA status of H. pylori, participants gender, and genetic variations at rs3761548. The AA genotype and A allele at rs3761548 could represent a risk factor for PU development.

Interleukin-35 Inhibits TNF-α-Induced Osteoclastogenesis and Promotes Apoptosis via Shifting the Activation From TNF Receptor-Associated Death Domain (TRADD)-TRAF2 to TRADD-Fas-Associated Death Domain by JAK1/STAT1

Over-activated osteoclasts derived from myeloid or peripheral blood monocytes by inflammatory cytokines results in osteoporosis, osteoarthritis, and other bone erosion-related diseases. Interleukin 35 (IL-35) is a novel anti-inflammatory and immunosuppressive factor. This study investigated the effect of IL-35 on TNF-α-induced osteoclastogenesis. In the presence of IL-35, this process was detected by Tartrate-Resistant Acid Phosphatase (TRAP) staining, F-actin staining, and bone resorption assays. The effects of IL-35 on TNF-α-induced apoptosis were demonstrated by TUNEL staining, cell viability assays, and flow cytometry. Moreover, a microarray was performed to detect the effect of IL-35 on TNF-α-activated phosphatase kinase. The effect of IL-35 on the TNF-α-mediated activation of NF-κB, MAPK, TRAF2, RIP1, Fas-associated death domain (FADD), and caspase3 was further investigated. In addition, a murine calvarial osteolysis model was established via the subcutaneous injection of TNF-α onto the calvaria, and histological analysis was subsequently performed. As a result, IL-35 inhibited TNF-α-induced osteoclast formation and bone resorption in vitro and osteolysis calvaria in vivo. NFATc1, c-fos, and TRAP were downregulated by IL-35 through the inhibition of NF-κB and MAPK, during which JAK1/STAT1 was activated. Moreover, based on TUNEL staining and flow cytometry, IL-35 was shown to enhance TNF-α-induced osteoclast apoptosis. Meanwhile, FADD and cleaved-caspase 3 were increased in cells treated with TNF-α and IL-35, whereas the DNA-binding activity of NF-κB was increased in TNF-α-treated cells, but was decreased in cells treated with both TNF-α and IL-35. In conclusion, IL-35 inhibits TNF-α-induced osteoclastogenesis and promotes apoptosis by activating JAK1/STAT1 and shifting activation from TNF receptor-associated death domain (TRADD)-TRAF2/RIP1-NF-κB to TRADD-FADD-caspase 3 signaling.

Mesenchymal stem cell expression of interleukin-35 protects against ulcerative colitis by suppressing mucosal immune responses

BACKGROUND

Interleukin-35 (IL-35) has recently been identified as an immunosuppressive cytokine that has been used as a potential therapy for chronic inflammatory and autoimmune diseases. However, there remains a paucity of data regarding its potential benefits after integration into mesenchymal stem cells (MSCs).

METHODS

We used a dextran sulfate sodium (DSS)-induced colitis mice model and treated them with IL-35-MSCs, MSCs or saline. The body weight was recorded daily and inflammatory processes were determined. Cytokine secretion by lamina propria lymphocytes (LPLs) and percentage of regulatory T cells (Tregs) were also measured.

RESULTS

The data showed that mice in the two treated groups recovered their body weight more rapidly than mice treated with saline in the later stage of colitis. The colon lengths of IL-35-MSC-treated mice were markedly longer than those in the other two groups and the inflammation reduced significantly. Furthermore, the percentage of Foxp3 + Tregs increased significantly and the level of proinflammatory cytokines produced by LPLs decreased significantly in the IL-35-MSC-treated group.

DISCUSSION

The results demonstrate that IL-35-MSCs could ameliorate ulcerative colitis by down-regulating the expression of pro-inflammatory cytokines.

The Role, Involvement and Function(s) of Interleukin-35 and Interleukin-37 in Disease Pathogenesis

The recently identified cytokines-interleukin (IL)-35 and interleukin (IL)-37-have been described for their anti-inflammatory and immune-modulating actions in numerous inflammatory diseases, auto-immune disorders, malignancies, infectious diseases and sepsis. Either cytokine has been reported to be reduced and in some cases elevated and consequently contributed towards disease pathogenesis. In view of the recent advances in utilizing cytokine profiles for the development of biological macromolecules, beneficial in the management of certain intractable immune-mediated disorders, these recently characterized cytokines (IL-35 and IL-37) offer potential as reasonable targets for the discovery of novel immune-modulating anti-inflammatory therapies. A detailed comprehension of their sophisticated regulatory mechanisms and patterns of expression may provide unique opportunities for clinical application as highly selective and target specific therapeutic agents. This review seeks to summarize the recent advancements in discerning the dynamics, mechanisms, immunoregulatory and anti-inflammatory actions of IL-35 and IL-37 as they relate to disease pathogenesis.

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.

Elevated level of interleukin-35 in colorectal cancer induces conversion of T cells into iTr35 by activating STAT1/STAT3

IL-35 is a novel heterodimeric and inhibitory cytokine, composed of interleukin-12 subunit alpha (P35) and Epstein-Barr virus -induced gene 3 (EBI3). IL-35 has been reported to be produced by a range of cell types, especially regulatory T cells, and to exert immunosuppressive effects via the STATx signaling pathway. In this study, we demonstrated that IL-35 expression was elevated in both serum and tumors in patients with colorectal cancer. IL-35 mainly expressed in CD4⁺ T cells in human colorectal cancer tumors and adjacent tissues. Increased IL-35 expression in tumor-adjacent tissues was significantly associated with tumor metastasis. IL-35 inhibited the proliferation of CD4⁺CD25⁻ T effector cells in vitro in a dose-dependent manner, and its suppression was partially reversed by applying IL-35-neutralizing antibodies. IL-35 treatment activated the phosphorylation of both STAT1 and STAT3 in human CD4⁺ T cells. Meanwhile, IL-35 induced a positive feedback loop to promote its own production. We observed that Tregs obtained from colorectal cancer patients were capable of inducing more IL-35 production. In addition, EBI3 promoter-driven luciferase activity was higher than that of the mock plasmid after IL-35stimulation. Thus, our study indicates that the high level of IL-35 in colorectal cancer promotes the production of IL-35 via STAT1 and STAT3, which suppresses T cell proliferation and may participate in tumor immunotolerance.