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

Current Advancements in Serum Protein Biomarkers for Hepatitis B Virus-Associated Hepatocyte Remodeling and Hepatocellular Carcinoma

BACKGROUND

Hepatitis B virus (HBV)-related liver cancer is the third most common cause of cancer-related death globally. Hepatocyte remodeling, also known as hepatocyte transformation and immortalization, and hepatocellular carcinoma (HCC), are brought on by persistent inflammation caused by HBV in the host hepatocytes. One of the main concerns in the perspective of HBV-induced hepatocyte remodeling and liver cancer is accurately identifying cancer stages to maximize early screening and detection. Biological signatures have a significant impact on solving this problem.

OBJECTIVE

This review article aimed to discuss the novel serum protein biomarkers for HBV-induced hepatocyte remodeling and HCC.

METHODS

The information was collected from various peer-reviewed journals through electronic searches utilizing various search engines, including PubMed, Google Scholar, HINARI, and Cochrane Library from 2017 to 2024. Keywords for searches included "serum protein biomarkers in HBV-HCC," "blood-based biomarkers in HBV-HCC," and "viral biomarkers for HBV-HCC."

RESULTS

Recently, novel protein signatures have been discovered for the early diagnosis, treatment, and prognosis of HBV-induced hepatic cell remodeling and HCC from proteomic data sets. We have discussed the recent literature on the clinical utility of the protein signatures for the diagnosis and forecasting of HBV-associated hepatocyte remodeling and HCC, including golgi protein 73 (GP73), glypican-3 (GPC3), midkine (MDK), des-γ-carboxy-prothrombin (DCP), von Willebrand factor (vWF), pentraxin 3 (PTX3), pseudouridine synthases 7 (PUSs 7), squamous cell carcinoma antigen (SCCA), and osteopontin (OPN).

CONCLUSION

All these protein markers also exhibit the survival of HBV-related HCC patients, the proliferation, migration, antiapoptosis, mitogenesis, transformation, and angiogenesis of HBV-infected hepatocytes.

Cytokine biomarkers for independent prediction of hepatocellular carcinoma prognosis

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide. Although various therapeutic modalities have been established for HCC, the overall outcomes of patients after treatment remain unsatisfactory, highlighting the need for valuable independent prognostic biomarkers. Cytokines are a large group of multifunctional secretory proteins and play critical roles in regulating development and progression of many cancer types, including HCC. Moreover, the expression levels of many cytokines in tumor/peritumor tissues and serum/plasma samples have been validated as important biomarkers for independently predicting the prognosis of HCC patients. This review provides a comprehensive summary of literature evidence for the independent prognostic significance of cytokine biomarkers in HCC patients receiving different therapies.

Role of tertiary lymphoid structures and B cells in clinical immunotherapy of gastric cancer

Gastric cancer is a common malignant tumor of the digestive tract, and its treatment remains a significant challenge. In recent years, the role of various immune cells in the tumor microenvironment in cancer progression and treatment has gained increasing attention. Immunotherapy, primarily based on immune checkpoint inhibitors, has notably improved the prognosis of patients with gastric cancer; however, challenges regarding therapeutic efficacy persist. Histological features within the tumor microenvironment, such as tertiary lymphoid structures (TLSs), tumor-infiltrating lymphocytes, and the proportion of intratumoral stroma, are emerging as potentially effective prognostic factors. In gastric cancer, TLSs may serve as local immune hubs, enhancing the ability of immune cells to interact with and recognize tumor antigens, which is closely linked to the effectiveness of immunotherapy and improved survival rates in patients. However, the specific cell type driving TLS formation in tumors has not yet been elucidated. Mature TLSs are B-cell regions containing germinal centers. During germinal center formation, B cells undergo transformations to become mature cells with immune function, exerting anti-tumor effects. Therefore, targeting B cells within TLSs could provide new avenues for gastric cancer immunotherapy. This review, combined with current research on TLSs and B cells in gastric cancer, elaborates on the relationship between TLSs and B cells in the prognosis and immunotherapy of patients with gastric cancer, aiming to provide effective guidance for precise immunotherapy.

The role of chemokines and interleukins in acute lymphoblastic leukemia: a systematic review

Acute lymphoblastic leukemia (ALL) is the most common childhood hematological malignancy, but it also affects adult patients with worse prognosis and outcomes. Leukemic cells benefit from protective mechanisms, which are mediated by intercellular signaling molecules - cytokines. Through these signals, cytokines modulate the biology of leukemic cells and their surroundings, enhancing the proliferation, survival, and chemoresistance of the disease. This ultimately leads to disease progression, refractoriness, and relapse, decreasing the chances of curability and overall survival of the patients. Targeting and modulating these pathological processes without affecting the healthy physiology is desirable, offering more possibilities for the treatment of ALL patients, which still remains unsatisfactory in certain cases. In this review, we comprehensively analyze the existing literature and ongoing trials regarding the role of chemokines and interleukins in the biology of ALL. Focusing on the functional pathways, genetic background, and critical checkpoints, we constructed a summary of molecules that are promising for prognostic stratification and mainly therapeutic use. Targeted therapy, including chemokine and interleukin pathways, is a new and promising approach to the treatment of cancer. With the expansion of our knowledge, we are able to uncover a spectrum of new potential checkpoints in order to modulate the disease biology. Several cytokine-related targets are advancing toward clinical application, offering the hope of higher disease response rates to treatment.

The molecular landscape of T cell exhaustion in the tumor microenvironment and reinvigoration strategies

Immunotherapy has emerged as a promising therapeutic approach for cancer treatment by harnessing the immune system to target cancer cells. However, the efficacy of immunotherapy is hindered by the tumor microenvironment (TME), comprising regulatory T cells (Tregs), macrophages, myeloid-derived suppressor cells (MDSCs), neutrophils, soluble factors (TGF-β, IL-35, IL-10), and hypoxia. These components interact with inhibitory receptors (IRs) on T cells, leading to alterations in T cell transcriptomes, epigenomes, and metabolism, ultimately resulting in T cell exhaustion and compromising the effectiveness of immunotherapy. T cell exhaustion occurs in two phases: pre-exhaustion and exhaustion. Pre-exhausted T cells exhibit reversibility and distinct molecular properties compared to terminally exhausted T cells. Understanding these differences is crucial for designing effective interventions. This comprehensive review summarizes the characteristics of pre-exhausted and exhausted T cells and elucidates the influence of TME components on T cell activity, transcriptomes, epigenomes, and metabolism, ultimately driving T cell exhaustion in cancer. Additionally, potential intervention strategies for reversing exhaustion are discussed. By gaining insights into the mechanisms underlying T cell exhaustion and the impact of the TME, this review aims to inform the development of innovative approaches for combating T cell exhaustion and enhancing the efficacy of immunotherapy in cancer treatment.

Immunosuppressive tumor microenvironment in the progression, metastasis, and therapy of hepatocellular carcinoma: from bench to bedside

Hepatocellular carcinoma (HCC) is a highly heterogeneous malignancy with high incidence, recurrence, and metastasis rates. The emergence of immunotherapy has improved the treatment of advanced HCC, but problems such as drug resistance and immune-related adverse events still exist in clinical practice. The immunosuppressive tumor microenvironment (TME) of HCC restricts the efficacy of immunotherapy and is essential for HCC progression and metastasis. Therefore, it is necessary to elucidate the mechanisms behind immunosuppressive TME to develop and apply immunotherapy. This review systematically summarizes the pathogenesis of HCC, the formation of the highly heterogeneous TME, and the mechanisms by which the immunosuppressive TME accelerates HCC progression and metastasis. We also review the status of HCC immunotherapy and further discuss the existing challenges and potential therapeutic strategies targeting immunosuppressive TME. We hope to inspire optimizing and innovating immunotherapeutic strategies by comprehensively understanding the structure and function of immunosuppressive TME in HCC.

Estimation of the tissue and serum levels of IL-35 in Mycosis fungoides: a case-control study

Mycosis fungoides (MF) is the most common primary cutaneous T-cell lymphoma (CTCL) with its etiology not yet fully understood. Interleukin (IL)-35 is an inhibitory cytokine that belongs to the IL-12 family. Elevated IL-35 in the plasma and the tumor microenvironment increases tumorigenesis and indicates poor prognosis in different types of malignancies. The objective of this study is to estimate the expression levels of IL-35 in tissue and serum of MF patients versus healthy controls. This case-control study included 35 patients with patch, plaque, and tumor MF as well as 30 healthy controls. Patients were fully assessed, and serum samples and lesional skin biopsies were taken prior to starting treatment. The IL-35 levels were measured in both serum and tissue biopsies by ELISA technique. Both tissue and serum IL-35 levels were significantly higher in MF patients than in controls (P < 0.001) and tissue IL-35 was significantly higher than serum IL-35 in MF patients (P < 0.001). Tissue IL-35 was significantly higher in female patients and patients with recurrent MF compared to male patients and those without recurrent disease (P < 0.001). Since both tissue and serum IL-35 levels are increased in MF, IL-35 is suggested to have a possible role in MF pathogenesis. IL-35 can be a useful diagnostic marker for MF. Tissue IL-35 can also be an indicator of disease recurrence.

IL-35: New Target for Immunotherapy Targeting the Tumor Microenvironment

Interleukin 35(IL-35) is a newly discovered inhibitory cytokine of the IL12 family. More recently, IL-35 was found to be increased in the tumor microenvironment (TME) and peripheral blood of many patients with cancer, indicating that it plays an important role in the TME. Tumors secrete cytokines that recruit myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Treg) into the TME to promote malignant progression, which is a great challenge for cancer treatment. Radiotherapy causes serious adverse effects, and tumor resistance to immune checkpoint inhibitors is still an unsolved challenge. Thus, new cancer therapy approaches are urgently needed. Numerous studies have shown that IL-35 can recruit immunosuppressive cells to enable tumor immune escape by promoting the conversion of immune cells into a tumor growth-promoting phenotype as well as facilitating tumor angiogenesis. IL-35-neutralizing antibodies were found to boost the chemotherapeutic effect of gemcitabine and considerably reduce the microvascular density of pancreatic cancer in mice. Therefore, targeting IL-35 in the TME provides a promising cancer treatment target. In addition, IL-35 may be used as an independent prognostic factor for some tumors in the near future. This review intends to reveal the interplay of IL-35 with immune cells in the TME, which may provide new options for the treatment of cancer.

New insights into T-cell exhaustion in liver cancer: from mechanism to therapy

Liver cancer is one of the most common malignancies. T-cell exhaustion is associated with immunosuppression of tumor and chronic infection. Although immunotherapies that enhance the immune response by targeting programmed cell death-1(PD-1)/programmed cell death ligand 1 (PD-L1) have been applied to malignancies, these treatments have shown limited response rates. This suggested that additional inhibitory receptors (IRs) also contributed to T-cell exhaustion and tumor prognosis. Exhausted T-cells (Tex) in the tumor immune microenvironment (TME) are usually in a dysfunctional state of exhaustion, such as impaired activity and proliferative ability, increased apoptosis rate, and reduced production of effector cytokines. Tex cells participate in the negative regulation of tumor immunity mainly through IRs on the cell surface, changes in cytokines and immunomodulatory cell types, causing tumor immune escape. However, T-cell exhaustion is not irreversible and targeted immune checkpoint inhibitors (ICIs) can effectively reverse the exhaustion of T-cells and restore the anti-tumor immune response. Therefore, the research on the mechanism of T-cell exhaustion in liver cancer, aimed at maintaining or restoring the effector function of Tex cells, might provide a new method for the treatment of liver cancer. In this review, we summarized the basic characteristics of Tex cells (such as IRs and cytokines), discussed the mechanisms associated with T-cell exhaustion, and specifically discussed how these exhaustion characteristics were acquired and shaped by key factors within TME. Then new insights into the molecular mechanism of T-cell exhaustion suggested a potential way to improve the efficacy of cancer immunotherapy, namely to restore the effector function of Tex cells. In addition, we also reviewed the research progress of T-cell exhaustion in recent years and provided suggestions for further research.

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 has a Protective Role in Infectious Mononucleosis-Induced Liver Inflammation Probably by Inhibiting CD8+ T Cell Function

Interleukin (IL)-35 plays an immunosuppressive role in infectious diseases, autoimmune disorders, and cancers. However, IL-35 expression and its regulation of CD8⁺ T cells in infectious mononucleosis (IM) are not fully understood. In this study, three groups of participants were compared, including twenty-three patients of IM without liver inflammation, twenty-eight patients of IM with liver inflammation, and twenty-one controls. Plasma and peripheral blood mononuclear cells (PBMCs) were isolated. CD8⁺ T cells were purified. Plasma IL-35 was measured by ELISA. PBMCs and CD8⁺ T cells were stimulated with recombinant human IL-35 in vitro. Perforin and granzyme B secretion was assessed by ELISPOT. Immune checkpoint molecule expression was investigated by flow cytometry. CD8⁺ T cells were co-cultured with HepG2 cells in direct contact and indirect contact manner. The cytotoxicity of CD8⁺ T cells was calculated by measuring lactate dehydrogenase release and proinflammatory cytokine expression. There was no significant difference in plasma IL-35 levels between patients with IM without liver inflammation and the controls, but the IL-35 level was notably increased in patients with IM who presented with liver inflammation and negatively correlated with aminotransferase. CD8⁺ T cells in patients with IM with liver inflammation showed stronger cytotoxicity. IL-35 stimulation inhibited CD8⁺ T cell-induced target cell death in patients with IM, mainly through suppression of IFN-γ/TNF-α secretion and elevation of immune checkpoint molecule expression, but did not affect perforin or granzyme B secretion. The current data indicated that IL-35 dampened the cytotoxicity of CD8⁺ T cells in patients with IM probably via repression of cytokine secretion. Elevated IL-35 may protect against CD8⁺ T cell-induced liver inflammation in patients with IM.

Heterogeneity and Functions of Tumor-Infiltrating Antibody Secreting Cells: Lessons from Breast, Ovarian, and Other Solid Cancers

Simple Summary

B cells are gaining increasing recognition as important contributors to the tumor microenvironment, influencing, positively or negatively, tumor growth, patient survival, and response to therapies. Antibody secreting cells (ASCs) constitute a variable fraction of tumor-infiltrating B cells in most solid tumors, and they produce tumor-specific antibodies that can drive distinct immune responses depending on their isotypes and specificities. In this review, we discuss the current knowledge of the heterogeneity of ASCs infiltrating solid tumors and how both their canonical and noncanonical functions shape antitumor immunity, with a special emphasis on breast and ovarian cancers.

Abstract

Neglected for a long time in cancer, B cells and ASCs have recently emerged as critical actors in the tumor microenvironment, with important roles in shaping the antitumor immune response. ASCs indeed exert a major influence on tumor growth, patient survival, and response to therapies. The mechanisms underlying their pro- vs. anti-tumor roles are beginning to be elucidated, revealing the contributions of their secreted antibodies as well as of their emerging noncanonical functions. Here, concentrating mostly on ovarian and breast cancers, we summarize the current knowledge on the heterogeneity of tumor-infiltrating ASCs, we discuss their possible local or systemic origin in relation to their immunoglobulin repertoire, and we review the different mechanisms by which antibody (Ab) subclasses and isoforms differentially impact tumor cells and anti-tumor immunity. We also discuss the emerging roles of cytokines and other immune modulators produced by ASCs in cancer. Finally, we propose strategies to manipulate the tumor ASC compartment to improve cancer therapies.

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.

The Molecular Role of IL-35 in Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and a common cause of cancer-related death. Better understanding of the molecular mechanisms, pathogenesis, and treatment of NSCLC can help improve patient outcomes. Significant progress has been made in the treatment of NSCLC, and immunotherapy can prolong patient survival. However, the overall cure and survival rates are low, especially in patients with advanced metastases. Interleukin-35 (IL-35), an immunosuppressive factor, is associated with the onset and prognosis of various cancers. Studies have shown that IL-35 expression is elevated in NSCLC, and it is closely related to the progression and prognosis of NSCLC. However, there are few studies on the mechanism of IL-35 in NSCLC. This study discusses the role of IL-35 and its downstream signaling pathways in the pathogenesis of NSCLC and provides new insights into its therapeutic potential.

Overexpression of ascitic interleukin-35 induces CD8+ T cell exhaustion in liver cirrhotic patients with spontaneous bacterial peritonitis

Interleukin (IL) -35 induces immunotolerance by suppression of CD8⁺ T cells during chronic infections and cancers. In the present study, we amined to investigate the role of IL-35-mediated regulation of CD8⁺ T cells in patients with liver cirrhosis. Seventy-one patients with liver cirrhosis (46 patients with untainted ascites and 25 patients with spontaneous bacterial peritonitis [SBP]) and 22 controls were enrolled. Plasma and ascitic IL-35 levels were measured using ELISA. Peripheral and ascitic CD4⁺ and CD8⁺ T cells were purified to investigate their functional phenotypes. IL-35-stimulated CD8⁺ T cells were cultured with HepG2 cells in direct and indirect contact systems. Lactate dehydrogenase expression and cytokine secretion were measured to determine the cytotoxicity of CD8⁺ T cells. Plasma IL-35 was elevated in patients with liver cirrhosis, and ascitic IL-35 levels were higher in the SBP group than in the untainted ascites group. No significant differences in transcription factor expression or cytokine production in peripheral and ascitic CD4⁺ T cells were observed among groups. In the SBP group, ascitic CD8⁺ T cells expressed decreased cytotoxic molecules, along with the reduced secretion of interferon-γ and tumor necrosis factor-α when compared with the untainted ascites group. IL-35 stimulation suppressed ascitic CD8⁺ T cell cytotoxicity and cytokine production in both direct and indirect contact culture systems. This process was accompanied by decreased cytotoxic molecule expression and increased immune-checkpoint molecules in ascitic CD8⁺ T cells. The present findings revealed that overexpression of ascitic IL-35 dampened the cytotoxicity of CD8⁺ T cells in liver cirrhotic patients with SBP.

Tissue-specific Tregs in cancer metastasis: opportunities for precision immunotherapy

Decades of advancements in immuno-oncology have enabled the development of current immunotherapies, which provide long-term treatment responses in certain metastatic cancer patients. However, cures remain infrequent, and most patients ultimately succumb to treatment-refractory metastatic disease. Recent insights suggest that tumors at certain organ sites exhibit distinctive response patterns to immunotherapy and can even reduce antitumor immunity within anatomically distant tumors, suggesting the activation of tissue-specific immune tolerogenic mechanisms in some cases of therapy resistance. Specialized immune cells known as regulatory T cells (Tregs) are present within all tissues in the body and coordinate the suppression of excessive immune activation to curb autoimmunity and maintain immune homeostasis. Despite the high volume of research on Tregs, the findings have failed to reconcile tissue-specific Treg functions in organs, such as tolerance, tissue repair, and regeneration, with their suppression of local and systemic tumor immunity in the context of immunotherapy resistance. To improve the understanding of how the tissue-specific functions of Tregs impact cancer immunotherapy, we review the specialized role of Tregs in clinically common and challenging organ sites of cancer metastasis, highlight research that describes Treg impacts on tissue-specific and systemic immune regulation in the context of immunotherapy, and summarize ongoing work reporting clinically feasible strategies that combine the specific targeting of Tregs with systemic cancer immunotherapy. Improved knowledge of Tregs in the framework of their tissue-specific biology and clinical sites of organ metastasis will enable more precise targeting of immunotherapy and have profound implications for treating patients with metastatic cancer.

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.

Interleukin-35 suppresses the activity of natural killer-like B cells in patients with hepatocellular carcinoma

Natural killer-like B (NKB) cells are newly identified lymphocyte subset, which present immunomodulatory property in infectious diseases through secretion of interleukin-18 (IL-18). However, the role of NKB cells function and its regulation in hepatocellular carcinoma (HCC) is not elucidated. Seventy-two HCC patients and twenty-five controls were enrolled. Peripheral and liver-infiltrating CD3^-CD19⁺CD56⁺NKp46⁺ cells were investigated by flow cytometry. Serum IL-35 and NKB cell-secreting cytokine level was measured by ELISA. The regulatory activity of IL-35 to peripheral and liver-infiltrating NKB cells was assessed in direct co-culture system between CD8⁺ T cells and HepG2 cells. Peripheral NKB cells and IL-18 secretion were reduced in HCC patients, while liver-infiltrating NKB cells and IL-18 secretion were also decreased in HCC tumor sites. Increased IL-35 level was negatively correlated with NKB cell percentage and IL-18 production in HCC. NKB cells induced the elevation of CD8⁺ T cell cytotoxicty, and this enhancement could be inhibited by IL-18 binding protein. IL-35 stimulation dampened NKB cell percentage and IL-18 production, leading to the suppression of NKB cell-mediated CD8⁺ T cell cytotoxicity in HCC patients. Our current data revealed that IL-35 might suppress NKB cell activity in HCC patients.

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

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