Immunoregulatory role of IL-35 in T cells of patients with rheumatoid arthritis

The distinct role of IL-34 and IL-35 in gastric cancer

Gastric cancer (GC) remains a major challenge due to its high mortality and morbidity, despite extensive research. Dysregulated host immunity plays a critical role in carcinogenesis, particularly among susceptible cohorts. In the gastric mucosa of GC patients, a reduction in IL-34 and TAM1, accompanied by an increase in TAM2 via M-CSF, enhances Th2 cell function, reduces pro-inflammatory activity, and elevates anti-inflammatory responses. Consequently, TAM2 acts in both paracrine and autocrine manners to polarize and boost TAM2, creating a tumour-favourable microenvironment that supports GC progression. High levels of TAM2, observed during advanced GC stages, suppress gastric IL-34 production, further promoting GC development. In contrast, IL-35, a cytokine involved in immune regulation and suppression, is produced by activated T cells and/or B cells in the affected gastric mucosa. Persistent H. pylori infection in GC tissues is associated with significant infiltration of IL-35-producing B cells and regulatory T cells (Tregs), which enhance the immunosuppressive and pro-tumour microenvironment by disrupting the local immune balance. Upregulated mucosal IL-35 promotes the polarization of TAM2 and Tregs while suppressing TAM1 cells, fostering a tumour-friendly environment that allows transformed gastric mucosal cells to evade immune surveillance, particularly in chronic H. pylori-infected patients. This cascade enhances proliferation and invasion while suppressing differentiation and apoptosis of GC cells. Together, the differential regulation of these cytokines creates an environment that supports cancer progression and resistance to therapy. Targeting the IL-34 and IL-35 pathways may offer a novel therapeutic strategy for improving outcomes in GC patients.

Helicobacter pylori and rheumatoid arthritis: Investigation of relation from traditional Chinese medicine

Rheumatoid arthritis (RA) is an autoimmune condition that predominantly affects synovial joints, manifesting with joint swelling, pain, and stiffness. In advanced stages, unchecked inflammation can inflict damage on bone and cartilage, resulting in disabilities and deformities of the joints. Additionally, systemic and extra-articular complications may arise due to the consequences of uncontrolled inflammation. Helicobacter pylori (H. pylori) is one of the most prevalent chronic bacterial infections in humans. This microorganism is a spiral-shaped, flagellated, microaerophilic gram-negative bacterium. Prolonged exposure leads to the activation of the immune system, with infected gastric mucosa epithelial cells continuously producing cytokines. This production, in turn, triggers the generation of antibodies as well as T Helper 1 and T Helper 2 effector T cells. The persistent antigenic stimulation resulting from H. pylori infection could lead to the progression of autoimmune diseases. Numerous clinical and pharmacological trials have illustrated the efficacy of traditional Chinese medicine against H. pylori. This review aims to delve into the connection between H. pylori and rheumatoid arthritis so as understand the pathogenesis. The concluding section of this review explores the interplay of Chinese medicine and Helicobacter pylori concerning rheumatoid arthritis.

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.

The role of IL-35 and IL-37 in breast cancer - potential therapeutic targets for precision medicine

Breast cancer is still a major concern due to its relatively poor prognosis in women, although there are many approaches being developed for the management of breast cancer. Extensive studies demonstrate that the development of breast cancer is determined by pro versus anti tumorigenesis factors, which are closely related to host immunity. IL-35 and IL-37, anti-inflammatory cytokines, play an important role in the maintenance of immune homeostasis. The current review focuses on the correlation between clinical presentations and the expression of IL-35 and IL-37, as well as the potential underlying mechanism during the development of breast cancer in vitro and in vivo. IL-35 is inversely correlated the differentiation and prognosis in breast cancer patients; whereas IL-37 shows dual roles during the development of breast cancer, and may be breast cancer stage dependent. Such information might be useful for both basic scientists and medical practitioners in the management of breast cancer patients.

Regulatory T cells in rheumatoid arthritis: functions, development, regulation, and therapeutic potential

Rheumatoid arthritis (RA) is an autoimmune disease that mainly affects the joints but also leads to systemic inflammation. Auto-reactivity and dysregulation of self-tolerance are thought to play a vital role in disease onset. In the pathogenesis of autoimmune diseases, disturbed immunosuppressive properties of regulatory T cells contribute to the dysregulation of immune homeostasis. In RA patients, the functions of Treg cells and their frequency are reduced. Therefore, focusing on the re-establishment of self-tolerance by increasing Treg cell frequencies and preventing a loss of function is a promising strategy for the treatment of RA. This approach could be especially beneficial for those patients who do not respond well to current therapies. In this review, we summarize and discuss the current knowledge about the function, differentiation and regulation of Treg cells in RA patients and in animal models of autoimmune arthritis. In addition, we highlight the therapeutic potential as well as the challenges of Treg cell targeting treatment strategies.

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.

Interleukin-35 promotes Breg expansion and interleukin-10 production in CD19+ B cells in patients with ankylosing spondylitis

OBJECTIVE

IL-35 is a potent immunosuppressive and anti-inflammatory cytokine, consisting of a p35 subunit and an Epstein-Barr virus-induced gene 3 (EBI3) subunit, which suppresses CD4⁺ effector T cell proliferation and promotes regulatory T cell (Treg) expansion. However, the effects of IL-35 on regulatory B cells (Bregs) in ankylosing spondylitis (AS) have not been explored. The present study aimed (i) to measure serum IL-35 levels and the percentages of Bregs in the peripheral blood of patients with AS and (ii) to explore their relationships in the pathogenesis of AS.

METHODS

A total of 77 patients with AS (AS group), including 47 inactive AS and 30 active AS cases, and 59 healthy controls (HCs) were enrolled into this study. The serum levels of IL-35 and IL-10 were detected by ELISA, and the mRNA levels of p35 and EBI3 were measured by RT-qPCR. The percentages of CD19⁺CD24^hiCD38^hi and CD19⁺CD24^hiCD27⁺ Bregs and IL-35 receptor (IL-12Rβ2, IL-27Rα and gp130), IL-10, p-STAT1, p-STAT3, and p-STAT4 in CD19⁺ B cells were detected by flow cytometry. The correlations between IL-35 levels and percentages of Bregs were analyzed by determining Pearson's correlation coefficient. The effect of IL-35 on Bregs was determined by mix-culture of recombinant (r) IL-35 with peripheral blood mononuclear cells (PBMCs).

RESULTS

The serum IL-35 and IL-10 levels, p35 and EBI3 mRNA levels, and the percentages of CD19⁺CD24^hiCD38^hi and CD19⁺CD24^hiCD27⁺ Bregs were significantly lower in AS patients than those in HCs. In addition, the percentages of CD19⁺CD24^hiCD38^hi and CD19⁺CD24^hiCD27⁺ Bregs in active AS patients were significantly lower than those in inactive AS patients. The serum IL-35 levels were positively correlated with the percentages of CD19⁺CD24^hiCD38^hi and CD19⁺CD24^hiCD27⁺ Bregs in AS patients. IL-12Rβ2 and IL-27Rα, but not gp130 subunit, were expressed in CD19⁺ B cells in AS patients. RIL-35 could effectively promote CD19⁺CD24^hiCD38^hi Breg expansion and IL-10 production. Meanwhile, rIL-35 also promoted the expression of IL-12Rβ2 and IL-27Rα and the phosphorylation of STAT1 and STAT3 in CD19⁺ B cells.

CONCLUSION

These results demonstrated that reduced IL-35 production may be associated with Bregs defects in AS patients. RIL-35 induced the proliferation of CD19⁺CD24^hiCD38^hi Bregs and IL-10 production, suggesting that IL-35 may serve as a reference for further investigation to develop novel treatments for AS. Key Points • Our study investigated the effects of IL-35 on Bregs in AS patients. • We found the serum IL-35, IL-10 levels, and the percentages of CD19⁺CD24^hiCD38^hi and CD19⁺CD24^hiCD27⁺ Bregs were significantly lower in AS patients. • The serum IL-35 levels were positively correlated with the percentages of CD19⁺CD24^hiCD38^hi and CD19⁺CD24^hiCD27⁺ Bregs in AS patients. • Recombinant IL-35 could effectively promote CD19⁺CD24^hiCD38^hi Breg expansion and IL-10 production.

Association Between Blood PLT and RBC Related Indices and Disease Activity in Patients with Rheumatoid Arthritis

Background

Platelet (PLT) and red blood cell (RBC) have been demonstrated to play a critical role in inflammatory processes. This study aimed to evaluate the association of blood PLT and RBC related parameters with the disease activity in rheumatoid arthritis (RA) patients, and also to investigate the role of these indices in differentiating among RA patients with different disease activity.

Methods

Clinical data from RA patients were retrospectively analyzed. RA patients were divided into inactive group and active group according to DAS28-CRP. The relationship between blood PLT and RBC counts-related indices and DAS28-CRP was detected by Spearman correlation. ROC curve was used to assess the diagnostic value of these indices in differentiating active RA from inactive RA.

Results

Active RA patients exhibited higher level of PLT counts but significantly lower levels of RBC counts, hemoglobin (Hb), red blood cells-platelet ratio (RPR) and hemoglobin-platelet ratio (HPR) compared with inactive RA. PLT counts were positively but RBC counts, Hb, RPR and HPR were negatively related with DAS28-CRP.

Conclusion

Blood PLT and RBC related indices were significantly associated with RA disease activity. These indices may be used to distinguish active RA from inactive RA.

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.

Urine and serum interleukin 35 as potential biomarkers of lupus nephritis

Introduction

Lupus nephritis (LN) is considered a serious manifestation of systemic lupus erythematosus (SLE). Therefore, a reliable non-invasive biomarker is a priority for monitoring renal involvement instead of the kidney biopsy. Interleukin 35 (IL-35) has an immunosuppressive and anti-inflammatory role in many autoimmune diseases. However, its role in LN still needs to be elucidated.

Aim of the study

To evaluate urine and serum levels of IL-35 in SLE patients with LN and without nephritis identifying their potential as biomarkers of renal involvement.

Material and methods

Urine and serum levels of IL-35 were measured in 42 SLE patients, divided into 22 with LN and 20 without LN, and 20 matched healthy controls using enzyme-linked immunosorbent assay (ELISA). SLE disease activity was assessed for patients by the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K).

Results

Levels of serum and urine IL-35 were significantly higher (p < 0.001) in the LN group compared with those without LN and with controls. In LN patients, a strong correlation (p < 0.001) was observed between serum and urine IL-35 levels with SLEDAI-2K score (r = 0.677 and 0.806 respectively). Furthermore, proteinuria had a strong and significant correlation (p ˂ 0.001) with serum and urinary IL-35 levels in the patients with LN. Serum IL-35 had 90.9% sensitivity and 85% specificity while urine IL-35 had 95.5% sensitivity and 75% specificity to differentiate LN from healthy individuals.

Conclusions

Urine and serum IL-35 may aid in assessment of renal involvement in SLE patients, serving as potential biomarkers of LN.

Serum levels and genetic variation of IL-35 are associated with multiple sclerosis: a population-based case-control study

This study aimed to investigate the association between serum levels and polymorphic variants of IL-35 with susceptibility, clinical features, and disease severity in multiple sclerosis (MS) patients.This case-control study recruited 186 MS patients and 195 sex- and age-matched healthy controls. Serum levels and polymorphic variants of IL-35 were determined by ELISA and restriction fragment length polymorphism (RFLP)-PCR or high resolution melting (HRM) analysis methods, respectively. In addition, by in silico analysis, we evaluated the location and function of the polymorphism.Serum levels of IL-35 were significantly lower in the patients than those of healthy controls (49.3 ± 3.7 vs. 69.5 ± 7.8, p = 0.009). EBI3 rs4740 polymorphism of IL-35 was associated with 2.2-fold increased risk of MS susceptibility (95% CI, 1.3-3.9, p = 0.005). However, there were no differences in the genotype distribution and allele frequencies of IL-35 rs568408 between the patients and controls (p > 0.05). In silico results showed that variation in IL-12A and EBI3 may affect on protein pathways of the cells and different components of the immune system such as NF-κB and INF-γ.The results show that IL-35 polymorphisms might be a genetic risk factor for the development of MS.

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 inhibited the production of histamine and pro-inflammatory cytokines through suppression MAPKs pathway in HMC-1 cells

Background

IL-35 is a newly anti-inflammatory cytokine that belongs to the IL-12 family. Mast cells, as one of the major effector cells in the immune response system, plays an important role in the pathogenesis of chronic spontaneous urticarial (CSU). Our study aims to explore the inhibited role of IL-35 in HMC-1.

Methods

The effects of IL-35 on cell proliferation, cytokine expression, and histamine release in a human mast cell line (HMC­1) were investigated by CCK8, ELISA, or RT-PCR. The phosphorylation levels of ERK1/2, p38, and JNK1/2, in PMA plus A23187 induced HMC-1 cells was detected by Western Blot.

Results

We found that IL-35 significantly inhibited the proliferation of HMC-1 cells stimulated by PMA and A23187. IL-35 also down-regulates the release of histamine and the mRNA expression of IL-6 and IL-17 in activated HMC-1. Furthermore, IL-35 markedly inhibited the phosphorylation levels of ERK1/2, p38, and JNK1/2, in PMA plus A23187 induced HMC-1 cells.

Conclusions

This study provides the first observations on the inhibitory and anti-inflammatory effect of IL-35 in activated HMC-1 cells. We suggest that IL35 may play an inhibited role in the pathogenesis of CSU.

Vitamin D as a Key Player in Modulating Rheumatoid Arthritis-derived Immune Response

Rheumatoid arthritis (RA) is a systemic inflammatory disease with chronic nature of joints related to autoimmunity. Vitamin D was found to modulate cell growth, function of immune cells and anti-inflammatory action. The aims of that study were to investigate serum level of vitamin D and some cytokines and to identify the correlation between vitamin D and these cytokines in RA. Totally 40 RA patients without vitamin D supplement were involved in this study. Serum level of vitamin D, interleukin-6 (IL-6), IL-10, IL-35, C-reactive protein (CRP) and tumor necrosis factor α (TNF-α), all of them were measure in all patients by enzyme-linked immunosorbent assay (ELISA). Patients were classified according to Vitamin D levels into two groups; RA patients with Vit. D deficiency (n=25) and RA patients with Vit. D sufficiency (n=15). IL-6 was lower significantly (P = 0.03) in RA patients with Vit. D sufficiency than RA patients with Vit. D deficiency. IL-10 and IL-35 were higher significantly (P = 0.0234, P = 0.0356 respectively) in RA patients with Vit. D sufficiency than RA patients with Vit. D deficiency. Vit. D was significantly positively correlated with both IL-10 (r = 0.4516, P = 0.0034) and IL-35 (r = 0.3424, P = 0.0329) and negatively correlated with IL-6 (r = -0.3188, P = 0.0479). Sufficient serum level of Vit. D is correlated with higher level of anti-inflammatory cytokines (IL-10 and IL-35) and lower level of IL-6. This support the immunomodulatory effect of Vit. D in RA.

Association of IL-35 expression and gene polymorphisms in rheumatoid arthritis

Interleukin (IL)-35 is the newest member of the IL-12 family. It is expressed in many immune cells and has been recognized as a novel inflammatory cytokine that may have bifunctional properties. Recent findings have indicated that the expression of IL-35 is abnormal in rheumatoid arthritis (RA) patients. However, the results were inconsistent. In this study, 400 RA patients were recruited to evaluate serum levels of IL-35 in a Chinese Han population by enzyme-linked immunosorbent assay. The association of IL-35 gene polymorphisms and RA genetic susceptibility was investigated in 400 RA patients and 612 healthy controls. The results showed that serum levels of IL-35 were elevated in 100 RA patients compared to 51 healthy controls, relating to disease activity and synovial fluid IL-35 expression in the training cohort. Another independent 300 RA patients and 369 other rheumatic disease patients (98 lupus, 95 osteoarthritis, 95 gout, 42 Sjogren's syndrome and 39 ankylosing spondylitis patients) confirmed that serum levels of IL-35 were elevated in RA patients, and serum IL-35 has good diagnostic ability for differentiating RA from the other rheumatic diseases. The genotyping of 10 IL-35 polymorphisms, including rs2227314, rs2243115, rs2243123, rs2243131, rs568408, rs583911, rs428253, rs4740, rs9807813 and rs4905, revealed that rs2227314, rs2243131, rs9807813, and rs583911 were correlated with RA risk. Different genotypes (rs2227314, rs583911, and rs9807813) exhibited different expression of IL-35. These findings demonstrate that serum levels of IL-35 are increased in RA patients and that IL-35 polymorphisms are correlated with RA risk.

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.

Elevation in the counts of IL-35-producing B cells infiltrating into lung tissue in mycobacterial infection is associated with the downregulation of Th1/Th17 and upregulation of Foxp3+Treg

IL-35 is an anti-inflammatory cytokine and is thought to be produced by regulatory T (Treg) cells. A previous study found that IL-35 was upregulated in the serum of patients with active tuberculosis (ATB), and IL-35-producing B cells infiltrated to tuberculous granuloma of patients with ATB. Purified B cells from such patients generated more IL-35 after stimulation by antigens of Mycobacterium tuberculosis and secreted more IL-10. However, the function and the underlying mechanisms of IL-35-producing B cells in TB progression have not been investigated. The present study found that the expression of mRNA of IL-35 subsets Ebi3 and p35 was elevated in mononuclear cells from peripheral blood, spleen, bone marrow, and lung tissue in a mouse model infected with Mycobacterium bovis BCG, as tested by real-time polymerase chain reaction. Accordingly, the flow cytometry analysis showed that the counts of a subset of IL-35+ B cells were elevated in the circulating blood and in the spleen, bone marrow, and lung tissue in BCG-infected mice, whereas anti-TB therapy reduced IL-35-producing B cells. Interestingly, BCG infection could drive the infiltration of IL-35-producing B cells into the lung tissue, and the elevated counts of IL-35-producing B cells positively correlated with the bacterial load in the lungs. Importantly, the injection of exogenous IL-35 stimulated the elevation in the counts of IL-35-producing B cells and was associated with the downregulation of Th1/Th17 and upregulation of Foxp3+Treg.The study showed that a subset of IL-35-producing B cells might take part in the downregulation of immune response in mycobacterial infection.

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.

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.

T Cell Dysregulation in Non-silicotic Silica Exposed Workers: A Step Toward Immune Tolerance Breakdown

Background: Chronic silica exposure can lead to silicosis, complicated or not by autoimmune diseases (AID). The pathophysiology of silica-induced AID remains not fully understood, especially immune mechanisms that may develop in patients without yet established silicosis. We conducted a prospective clinical study to analyze the impact of crystalline silica (CS) on T cell phenotype and regulatory T cells (Tregs) frequency, as well as on auto-antibodies development in non-silicotic workers exposed to CS.

Methods: Workers with moderate to high exposure level to CS and aged between 30 and 60 years-old were considered for inclusion. Peripheral blood mononuclear cells were analyzed by flow cytometry. Auto-antibodies were screened in serum by immunofluorescence. Blood from 42 and 45 healthy subjects (HC) was used as control for T cell phenotype and serum analyses, respectively.

Results: Among the 63 included workers exposed to CS, 55 had full data available and were analyzed. Ten were exposed to CS for <5 years, 18 for 5–10 years and 27 for more than 10 years. The frequency of Tregs (CD4⁺CD25⁺CD127⁻FoxP3⁺) was significantly lower in CS exposed workers as compared to HC. We found an increased expression of the activation marker HLA-DR on T cells (CD3⁺, CD4⁺, and CD8⁺) of CS exposed workers as compared to HC. Tregs to activated T cells ratio was also lower in exposed subjects. In the latter, HLA-DR expression level and Tregs frequency were significantly associated with CS exposure duration. Serum autoantibody detection was significantly higher in CS exposed workers as compared to HC. Especially, among workers exposed more than 10 years, antinuclear antibodies and ANCA were detected in 44 and 22% among them, as compared to 5 and 2.5% in HC, respectively.

Conclusion: This work shows that CS exposure is associated with a decrease of Tregs frequency, an increase of T cell activation status, and a tolerance breakdown against auto-antigens. These results show that alterations of the T cell compartment can be detected early over the course of CS exposure, preceding silicosis development or AID onset.

Changes in Serum Cytokines May Predict Therapeutic Efficacy of Tofacitinib in Rheumatoid Arthritis

Objective

Tofacitinib is a novel therapy for rheumatoid arthritis (RA). The aim of this study was to measure various serum cytokines levels and to explore potential markers predictive of therapeutic efficacy of tofacitinib for RA patients.

Methods

Thirty-two patients with RA were given tofacitinib (5 mg bid). Serum cytokines levels of Th1 (IFN-γ), Th2 (IL-6), Th17 (IL-17), Tregs (IL-35), and TNF-α were detected by enzyme-linked immunosorbent assays.

Results

Disease activity was significantly decreased as early as week 4 after tofacitinib treatment. Serum IL-35 levels were significantly increased and serum levels of TNF-α, IL-17, IL-6, and IFN-γ were significantly reduced in response to tofacitinib since week 4.

Conclusions

After treatment with tofacitinib, RA patients may benefit from monitoring of disease activity as early as week 4. IL-35 also might be a predictive indicator of the disease activity and drug efficacy. Meanwhile, tofacitinib might be CS-sparing in RA.

Abnormal numbers of CD4+ T lymphocytes and abnormal expression of CD4+ T lymphocyte‑secreted cytokines in patients with immune‑related haemocytopenia

In the past decade, a group of cases with persisting haemocytopenia were separated from those with idiopathic cytopenia of undetermined significance due to the optimal response of these patients to immunosuppression therapy and due to the detection of autoantibodies in the bone marrow of haemopoietic cells. This condition was termed immune-related haemocytopenia (IRH). However, the quantity of T lymphocytes remained unknown. In the present study, the percentage of CD4⁺ T-cell subsets and related cytokines was measured using flow cytometry and an enzyme-linked immunosorbent assay. An abnormal number of CD4⁺ T cell subsets was found, including increased percentages of T helper (Th)2, Th9 and Th17 cells and a decreased number of regulatory T (Treg) cells. In addition, the results showed downregulation in the levels of interleukin (IL)-2, transforming growth factor-β and IL-35, and upregulation in the levels of IL-4, IL-6, IL-17, IL-23 and interferon-γ in patients who did not receive therapy (untreated patients). These levels were significantly associated with the number of peripheral blood cells and were recovered following treatment. In conclusion, an abnormal number of CD4⁺ T cell subsets and corresponding abnormal levels of regulatory cytokines resulted in the stimulation of B1 lymphocytes to produce autoantibodies in IRH, which may be considered as markers to evaluate disease prognosis and treatment strategies.

Correlation between Serum IL-35 Levels and Bone Loss in Postmenopausal Women with Rheumatoid Arthritis

Objective

IL-35 was reported as a crucial anti-inflammatory cytokine and could efficiently regulate bone metabolism in murine collagen-induced arthritis model. However, the relationship between IL-35 and bone health in human rheumatoid arthritis (RA) has not been clarified. In this study, the aim was to explore the correlations between IL-35 and bone loss in postmenopausal women with RA.

Methods

The study included 76 postmenopausal women with RA and 53 healthy postmenopausal women as healthy controls (HCs). Serum IL-35 levels were detected by enzyme-linked immunosorbent assay. Bone mineral density (BMD) at lumbar spine 1-4 and at total hip was measured using dual-energy X-ray absorptiometry. Alkaline phosphatase (ALP), β-isomerised carboxy-terminal cross-linking telopeptide of type I collagen (β-CTX), and 25-(OH) VitD₃ were measured by turbidimetric inhibition immunoassay.

Results

Serum IL-35 levels were increased compared with HCs, and it positively correlated with BMD and 25-(OH) VitD₃ and negatively correlated with β-CTX in postmenopausal women with RA. Furthermore, serum IL-35 levels in the increased ALP group were higher than those in the normal ALP group.

Conclusions

IL-35, an important anti-inflammatory cytokine, may participate in the pathogenesis of bone loss in postmenopausal women with RA.

MTB driven B cells producing IL-35 and secreting high level of IL-10 in the patients with active pulmonary tuberculosis

Regulatory B cells (Bregs) have critical roles as a negative regulator of immunity, mainly due to the fact that it secrets high a level of interleukin 10 (IL-10). Recently, a new subset of Bregs was identified as a key source of IL-35, which is an immunosuppressive cytokine and conventionally thought to be secreted by regulatory T cells (Tregs). Our previous study showed that the level of IL-35 in serum was elevated in the patients with active tuberculosis (ATB). However, none of the studies reported that IL-35 is secreted by B cells in ATB patients. In the current study, we found that the mRNA expressions of the both subunits (p35 and Ebi3) of IL-35 by circulating B cells were increased in ATB patients. By using immunohistochemistry and immunofluorescence staining, we found a subset of B cells infiltrated into the tuberculous granuloma of ATB patients also expressed IL-35. Moreover, Mycobacterium tuberculosis (MTB) lysate stimulation assay also demonstrated higher levels of IL-35 were exerted by MTB lysate within purified B cells from healthy control group (HC). Flow cytometry analysis further showed that the IL-35-producing B cells from ATB patients produced a higher level of IL-10. Taken together, IL-35-producing B cells may play a regulatory role during MTB infection by producing IL-10.

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.

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.

Investigating the potential immune role of IL-35 in grass carp (Ctenopharyngodon idella)

Interleukin-35 (IL-35) is a member of the IL-12 cytokine family and a heterodimeric protein formed by Epstein-Barr virus-induced gene 3 (EBI3) and IL-12p35. Emerging evidence showed that IL-35 is a key player in the regulation of cellular communication, differentiation, and inflammation. To date, no studies on fish IL-35 have been documented. In this work, we first identify two splicing isoforms of EBI3, EBI3a and EBI3b, from grass carp (Ctenopharyngodon idella). EBI3a is composed of 299 amino acid residues and possesses an immunoglobulin-like (Ig-like) domain and a fibronectin type 3 (FN3) domain that is a conservative domain in vertebrate EBI3. However, the EBI3b is composed of 177 amino acid residues and only contains an Ig-like domain. The result of Co-immunoprecipitation suggests that only EBI3a can associate with IL-12p35 to form IL-35 in grass carp. Like the function of IL-35 in human and mouse, recombinant grass carp IL-35 protein could induce the expression of genes EBI3a, IL-12p35, and CD25-like and downregulate the expression of genes CD4-1, CD4-2, IL-17A/F1, and RORγ2. Taken together, these results indicate for the first time that a teleost IL-35 may also have the ability to induce regulatory T (Treg) cells, inhibit effector T (Teff) cell proliferation and restrict the differentiation and function of T helper 17 (Th17) cells in teleost.

Sexual dimorphism in Th17/Treg axis in lymph nodes draining inflamed joints in rats with collagen-induced arthritis

Collagen type II-induced arthritis (CIA) in Dark Agouti rats, a model of rheumatoid arthritis (RA), reproduces sexual dimorphism in the incidence and severity of the human disease. Th17 cells are central in the induction/propagation of autoimmune inflammation in CIA and RA. To assess mechanisms underlying this dimorphism in CIA rats, in lymph nodes draining inflamed joints and adjacent tissues (dLNs) from CIA rats of both sexes Th17/CD25+Foxp3+CD4+ T-regulatory cell (Treg) ratio, Th17 cell redifferentiation in functionally distinct subsets and Treg transdifferentiation into IL-17-producing cells (exTregs) were examined. In female rats (developing more severe CIA than their male counterparts) the higher frequency of all Th17 cells (reflecting partly their greater proliferation), followed by the higher frequency of highly pathogenic IFN-γ/GM-CSF-co-producing cells, but lower frequency of less pathogenic/immunoregulatory IL-10-producing cells among them was found. Additionally, compared with male rats, in female rats the lower frequency of Tregs was observed. Moreover, Tregs from female rats exhibited diminished proliferative and suppressive capacity (judging by PD-1 expression) and enhanced conversion into IL-17-producing cells. Given that TGF-β concentration was comparable in collagen-type II-stimulated dLN cell cultures from female and male rats, the shift in Th17/Treg ratio followed by augmented Th17 cell redifferentiation into IFN-γ/GM-CSF-co-producing cells and Treg transdifferentiation into IL-17-producing cells in female rats was associated with increased concentration of IL-6 in female rat dLN cell cultures, and the higher frequency of IL-1β- and IL-23-producing cells among their dLN cells. The lower frequency of IL-10-producing B cells, presumably B regulatory cells (Bregs) could also contribute to the shift in Th17/Treg ratio in female rat compared with male rat dLNs. Consistently, the lower expression of IL-35 (the cytokine promoting Treg expansion directly and indirectly, by favoring Breg expansion and conversion into IL-10/IL-35-producing cells) in female rat dLN cells was detected. Thus, the study identified putative cellular and molecular substrates of the sexual dimorphism in the immunopathogenesis and clinical outcome of CIA and suggested mechanisms to be targeted in females to improve control of Th17 response, and consequently clinical outcome of CIA, and possibly RA.

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.

Association between IL-35 and coronary arterial lesions in children with Kawasaki disease

Kawasaki disease (KD) arises due to the acute inflammation and immune system dysfunction. This study investigated the relationship between the serum level of IL-35 and coronary artery lesions (CALs) in patients with KD. We obtained blood samples from 90 children with KD before intravenous immunoglobulin therapy. Levels of IL-35, IL-6, IL-17A, IL-10, MCP-1 and VEGF were measured in 190 cases, including 4 groups: KD with coronary arterial lesions (n = 46), KD without coronary arteries lesions (n = 44), febrile control group (FC, n = 40) and the normal control group (NC, n = 60). White blood cell counts (WBC), red blood cell counts (RBC), hemoglobin, platelet, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and procalcitonin were tested in all subjects. Levels of IL-35, RBC and hemoglobin significantly decreased, and IL-6, IL-17A, IL-10, MCP-1 and VEGF were significantly elevated in the KD group compared with febrile and control groups. IL-35 serum level even decreased, and ESR, IL-6, MCP-1 and VEGF increased in the KD patients with CALs. Serum levels of IL-35 in KD patients were negatively associated with WBC, CRP, IL-6, IL-17A, IL-10, MCP-1 and VEGF in children with KD. IL-35 may have the effect on inhibiting inflammatory process in KD and further preventing KD patients from coronary artery lesion.

IL-35 inhibits human osteoclastogenesis from monocytes induced by receptor-activator of NF-κB ligand

IL-35 is known as a regulatory cytokine produced by regulatory T cells. It has also been reported that IL-35 suppresses the proliferation of Th17 cells, which is involved in the pathogenesis of many autoimmune diseases. However, in rheumatoid arthritis patients, the role of IL-35 is controversial, and the role of IL-35 in bone metabolism has not been clarified. We investigated the effect of IL-35 on human osteoclast differentiation and activation. We first evaluated the effect of rhIL-35 on human osteoclastogenesis from monocytes cultured alone, induced by soluble-RANKL. We also examined the role of IL-35 on the bone-resorption function of mature osteoclasts. Furthermore, we analysed the molecular mechanism of IL-35 function in monocytes or pre-osteoclasts using RT-PCR. rhIL-35 significantly inhibited human osteoclastogenesis in a dose-dependent manner. In addition, rhIL-35 also significantly decreased the area of pit formation by mature osteoclasts. rhIL-35 significantly decreased mRNA expression of RANK in monocytes and RANK and FOS in pre-osteoclasts. Our current findings suggest that IL-35 inhibits osteoclastogenesis and osteoclast activation by inhibiting both RANK and FOS. IL-35 also has an inhibitory effect on osteoclastic-bone resorption, suggesting that IL-35 may have a therapeutic potential for RA.

Immune-inhibitive phenyl-C1 substituent aporphine alkaloids from Thalictrum cirrhosum

Five new phenyl-C₁ substituent aporphine alkaloids, 6aR-2'-methoxycarbonyl-thaliadin (1), 6aR-2'-carboxyl-thaliadin (2), 6aR-3-methoxy-hernandalinol (3), 6aS-1,3,10-trimethoxy-natalamine (4), and 3-methoxy-2'-methoxycarbonyl-oxohernandalincin (5), together with sixteen known isoquinoline alkaloids (6-21) were isolated from the whole herb of Thalictrum cirrhosum (Levl.). Their structures were elucidated by extensive spectroscopic measurements, and six isoquinoline alkaloids showed significant inhibitory activity on concanavalin A-stimulated splenocytes proliferation with IC₅₀ values 36-44 μM by the immunosuppressive bioassay.

Emerging role of IL-35 in inflammatory autoimmune diseases

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

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.

Rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory, autoimmune disease that primarily affects the joints and is associated with autoantibodies that target various molecules including modified self-epitopes. The identification of novel autoantibodies has improved diagnostic accuracy, and newly developed classification criteria facilitate the recognition and study of the disease early in its course. New clinical assessment tools are able to better characterize disease activity states, which are correlated with progression of damage and disability, and permit improved follow-up. In addition, better understanding of the pathogenesis of RA through recognition of key cells and cytokines has led to the development of targeted disease-modifying antirheumatic drugs. Altogether, the improved understanding of the pathogenetic processes involved, rational use of established drugs and development of new drugs and reliable assessment tools have drastically altered the lives of individuals with RA over the past 2 decades. Current strategies strive for early referral, early diagnosis and early start of effective therapy aimed at remission or, at the least, low disease activity, with rapid adaptation of treatment if this target is not reached. This treat-to-target approach prevents progression of joint damage and optimizes physical functioning, work and social participation. In this Primer, we discuss the epidemiology, pathophysiology, diagnosis and management of RA.

Cytokines in the pathogenesis of rheumatoid arthritis: new players and therapeutic targets

In recent years, the landscape of pro- and anti-inflammatory cytokines has rapidly expanded with the identification of new members proven to be involved at different extent in the pathogenesis of chronic immune mediated inflammatory diseases including rheumatoid arthritis (RA). The advance of our understanding of mediators involved in the pathogenesis of RA and in consequence, the development of novel targeted therapies is necessary to provide patients not responding to currently available strategies with novel compounds. The aim of this review article is to provide an overview on recently identified cytokines, emphasizing their pathogenic role and therapeutic potential in RA. A systematic literature review was performed to retrieve articles related to every cytokine discussed in the review. In some cases, evidence from animal models and RA patients is already consistent to move forward into drug development. In others, conflicting observation and the paucity of data require further investigations.Forty years after the discovery of IL-1, the landscape of cytokines is continuously expanding with increasing possibilities to develop novel therapeutic strategies in RA.

Role of the IL-12/IL-35 balance in patients with Sjögren syndrome

BACKGROUND

An interferon signature is involved in the pathogenesis of primary Sjögren syndrome (pSS), but whether the signature is type 1 or type 2 remains controversial. Mouse models and genetic studies suggest the involvement of T_H1 and type 2 interferon pathways. Likewise, polymorphisms of the IL-12A gene (IL12A), which encodes for IL-12p35, have been associated with pSS. The IL-12p35 subunit is shared by 2 heterodimers: IL-12 and IL-35.

OBJECTIVE

We sought to confirm genetic association of the IL12A polymorphism and pSS and elucidate involvement of the IL-12/IL-35 balance in patients with pSS by using functional studies.

METHODS

The genetic study involved 673 patients with pSS from 2 French pSS cohorts and 585 healthy French control subjects. Functional studies were performed on sorted monocytes, irrespective of whether they were stimulated. IL12A mRNA expression and IL-12 and IL-35 protein levels were assessed by using quantitative RT-PCR and ELISA and a multiplex kit for IL-35 and IL-12, respectively.

RESULTS

We confirmed association of the IL12A rs485497 polymorphism and pSS and found an increased serum protein level of IL-12p70 in patients with pSS carrying the risk allele (P = .016). Serum levels of IL-12p70 were greater in patients than control subjects (P = .0001), especially in patients with more active disease (P = .05); conversely, IL-35 levels were decreased in patients (P = .0001), especially in patients with more active disease (P = .05). In blood cellular subsets both IL12p35 and EBV-induced gene protein 3 (EBI3) mRNAs were detected only in B cells, with a trend toward a lower level among patients with pSS.

CONCLUSION

Our findings emphasize involvement of the IL-12/IL-35 balance in the pathogenesis of pSS. Serum IL-35 levels were associated with low disease activity, in contrast with serum IL-12p70 levels, which were associated with more active disease.

An immunosuppressive function of interleukin-35 in chronic hepatitis C virus infection

Interleukin (IL)-35, a newly identified member of the IL-12 cytokine family, has been reported to suppress inflammation and induce immunotolerance. However, little is known regarding the role of IL-35 during chronic hepatitis C virus (HCV) infection. Herein, we measured the serum IL-35 concentration of 73 patients with hepatitis C and 22 healthy individuals, as well as further investigated the modulatory function of IL-35 on CD4⁺CD25⁺CD127^dim/- regulatory T cells (Tregs) and on hepatocytes infected with HCV in cell culture (HCVcc). IL-35 expression was significantly increased in patients with chronic hepatitis C and was positively correlated with the levels of HCV RNA. Inhibition of viral replication led to decreases in the serum levels of IL-35. IL-35 stimulation not only elevated the percentage of Tregs but also robustly inhibited cellular proliferation and up-regulated the production of anti-inflammatory cytokines (e.g., IL-10 and IL-35) in a HCV-specific and non-specific manner, which indicates enhancement of the suppressive function of Tregs. Although IL-35 did not exert anti-HCV activity in HCVcc-infected Huh7.5 cells, it reduced inflammatory cytokine secretion from Huh7.5 cells. This was probably via inhibition of the STAT1 and STAT3 signaling pathways, which could suppress subsequent liver damage due to chronic hepatitis C. The current data suggested that IL-35 contributes to persistent HCV infection by inhibiting antiviral immune activity. Moreover, IL-35 might also protect against HCV-induced liver injury by down-regulating the expression of proinflammatory cytokines. Thus, the immunosuppressive properties of IL-35 might play contradictory roles in maintaining viral persistence and reducing the inflammatory responses in chronic HCV infection.

Interleukin-35: a Potential Therapeutic Agent for Autoimmune Diseases

Autoimmune diseases contain a large number of pathologies characterized by various factors that contribute to a breakdown in self-tolerance. Cytokine-mediated immunity plays an essential role in the pathogenesis of varieties of autoimmune diseases. Recent studies reveal that interleukin-35 (IL-35), a newly identified cytokine of IL-12 family, is implicated in the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), etc. In this review, we will discuss the biological features of IL-35 and summarize recent advances in the role of IL-35 in the development and pathogenesis of autoimmune diseases; the discoveries gained from these findings might translate into future therapies for these diseases.

Major involvement of bacterial components in rheumatoid arthritis and its accompanying oxidative stress, systemic inflammation and hypercoagulability

We review the evidence that infectious agents, including those that become dormant within the host, have a major role to play in much of the etiology of rheumatoid arthritis and the inflammation that is its hallmark. This occurs in particular because they can produce cross-reactive (auto-)antigens, as well as potent inflammagens such as lipopolysaccharide that can themselves catalyze further inflammagenesis, including via β-amyloid formation. A series of observables coexist in many chronic, inflammatory diseases as well as rheumatoid arthritis. They include iron dysregulation, hypercoagulability, anomalous morphologies of host erythrocytes, and microparticle formation. Iron dysregulation may be responsible for the periodic regrowth and resuscitation of the dormant bacteria, with concomitant inflammagen production. The present systems biology analysis benefits from the philosophical idea of "coherence," that reflects the principle that if a series of ostensibly unrelated findings are brought together into a self-consistent narrative, that narrative is thereby strengthened. As such, we provide a coherent and testable narrative for the major involvement of (often dormant) bacteria in rheumatoid arthritis.

Vitamin D in rheumatoid arthritis-towards clinical application

In addition to its well-documented involvement in mineral homeostasis, vitamin D seems to have broad effects on human health that go beyond the skeletal system. Prominent among these so-called nonclassical effects of vitamin D are its immunomodulatory properties. In vitro studies have shown anti-inflammatory effects of 1,25-dihydroxyvitamin D (1,25(OH)2D), the active form of vitamin D. In addition, epidemiological analysis of patients with established inflammatory disease identified associations between vitamin D deficiency (low serum concentrations of inactive 25-hydroxyvitamin D, abbreviated to 25(OH)D) and inflammatory conditions, including rheumatoid arthritis (RA). The association of vitamin D deficiency with RA severity supports the hypothesis of a role for vitamin D in the initiation or progression of the disease, or possibly both. However, whether 25(OH)D status is a cause or consequence of RA is still incompletely understood and requires further analysis in prospective vitamin D supplementation trials. The characterization of factors that promote the transition from preclinical to clinical phases of RA has become a major focus of research, with the aim to facilitate earlier diagnosis and treatment, and improve therapeutic outcomes. In this Review, we aim to describe the current knowledge of vitamin D and the immune system specifically in RA, and discuss the potential benefits that vitamin D might have on slowing RA progression.