Interleukin-35 Suppresses Antiviral Immune Response in Chronic Hepatitis B Virus Infection

Recent advances in understanding T cell activation and exhaustion during HBV infection

Chronic hepatitis B virus (HBV) infection remains a major public health concern globally, and T cell responses are widely believed to play a pivotal role in mediating HBV clearance. Accordingly, research on the characteristics of HBV-specific T cell responses, from activation to exhaustion, has advanced rapidly. Here, we summarize recent developments in characterizing T cell immunity in HBV infection by reviewing basic and clinical research published in the last five years. We provide a comprehensive summary of the mechanisms that induce effective anti-HBV T cell immunity, as well as the latest developments in understanding T cell dysfunction in chronic HBV infection. Furthermore, we briefly discuss current novel treatment strategies aimed at restoring anti-HBV T cell responses.

The Role of Interleukins in HBV Infection: A Narrative Review

Hepatitis B virus (HBV) infection is a worldwide medical issue with significant morbidity and mortality, as it is the main cause of chronic liver disease and hepatocellular carcinoma (HCC). Both innate and adaptive immune responses play a key role in HBV replication and suppression. Recently, the pathophysiological function of interleukins (IL) in the natural course of HBV has gained much attention as a result of the broad use of anti-interleukin agents for a variety of autoimmune diseases and the accompanying risk of HBV reactivation. We present a narrative review regarding the role of IL in HBV infection. Collectively, the pro-inflammatory ILs, namely IL-1, IL-5, IL-6, IL-12 and IL-21, seem to play a critical role in the suppression of HBV replication. In contrast, the anti-inflammatory cytokines IL-10, IL-23 and IL-35 probably act as HBV replication enhancers, while IL-17 has been correlated with HBV-related liver injury. Interestingly enough, IL-2, IL-4 and IL-12 have been tried as therapeutic options against HBV infection with contradictory results. Lastly, the role of IL-22 remains largely ill defined, although preliminary data suggest that it may play a significant role in HBV replication, proliferation and subsequent liver damage.

Potential of Interleukin (IL)-12 Group as Antivirals: Severe Viral Disease Prevention and Management

The interleukin (IL)-12 family consists of pro- and anti-inflammatory cytokines that are able to signal the activation of host antiviral immunity while preventing over-reactive immune reactions due to active virus replication and viral clearance. Amongst others, IL-12 and IL-23 are produced and released by innate immune cells such as monocytes and macrophages to signal the proliferation of T cells and release of effector cytokines, which subsequently activate host defence against virus infections. Interestingly, the dualities of IL-27 and -35 are evidently shown in the course of virus infections; they regulate the synthesis of cytokines and antiviral molecules, proliferation of T cells, and viral antigen presentation in order to maximize virus clearance by the host immune system. In terms of anti-inflammatory reactions, IL-27 signals the formation of regulatory T cells (Treg) which in turn secrete IL-35 to control the scale of inflammatory response that takes place during virus infections. Given the multitasking of the IL-12 family in regards to the elimination of virus infections, its potential in antiviral therapy is unequivocally important. Thus, this work aims to delve deeper into the antiviral actions of the IL-12 family and their applications in antiviral therapies.

Circulating cytokine profile and modulation of regulatory T cells in chronic hepatitis B patients with type 2 diabetes mellitus

The risk of hepatitis B virus (HBV) infection is higher in patients with diabetes mellitus, and diabetes mellitus is one of the metabolic complications of HBV infection. However, the cytokine profile of chronic hepatitis B (CHB) patients with type 2 diabetes mellitus (T2DM) is not fully understood. The aim of this study was to investigate the cytokine expression profile in CHB patients with T2DM, and to assess the regulatory function of cytokines to regulatory T cells (Tregs). Forty-four T2DM patients, 39 CHB patients, 17 patients with CHB and T2DM, and 21 control subjects were enrolled. Cytokine levels in the plasma were measured by Luminex multiplex assay. CD4+CD25+CD127dim/- Tregs were detected by flow cytometry. Tregs were purified and stimulated with recombinant human interleukin-15 (IL-15). The regulation of IL-15 on Tregs function was investigated by measuring cell number, IL-10/IL-35 secretion, and mRNA expression of immune checkpoint molecules in a Tregs+PBMC co-culture system. We found that levels of IL-1α, IL-6, and IL-33 were upregulated, while IFN-α, IL-2, IL-7, and IL-15 were downregulated in T2DM and CHB patients. CHB patients with T2DM had even lower plasma IL-7 and IL-15 levels. Tregs percentage was elevated in T2DM and CHB patients. CHB patients with T2DM had increased levels of Tregs, which correlated negatively with IL-15. Tregs showed stronger inhibitory activity in CHB patients with T2DM than in controls, T2DM, and CHB patients, which presented as reduction in cellular proliferation and induction of IL-10/IL-35 secretion. IL-15 suppressed Tregs function and inhibited the expression of immune checkpoint molecules in Tregs. The current data suggest that insufficient IL-15 levels and decreased responsiveness of Tregs to IL-15 signaling might contribute to strong immune dysfunction in CHB patients with T2DM.

Interleukin-35 dampens T helper 22 phenotype shift in CD4+CD25+CD127dim/- regulatory T cells in primary biliary cholangitis

The phenotype shift in regulatory T cells (Tregs) contributes to immunopathogenesis of autoimmune diseases. The current study was aimed to investigate the regulatory function of interleukin-35 (IL-35) to T helper 22 (Th22) cell phenotype shift in Tregs in primary biliary cholangitis (PBC). Fifty-five PBC patients and twenty-four controls were enrolled. CD4+CD25+CD127dim/- Tregs and Th22 cells were investigated by flow cytometry. Forkhead box P3 (FoxP3) and aryl hydrocarbon receptor (AhR) mRNA levels were assessed by real-time polymerase chain reaction. Plasma IL-10 and IL-22 levels were measured by ELISA. Purified Tregs were stimulated with exogenous IL-35, and were co-cultured with autologous CD4+CD25- T cells. Cellular proliferation and cytokine production was measured. Purified Tregs were also cultured into Th22 condition in the presence or absence of exogenous IL-35, and Th22 phenotype were assessed. PBC patients had lower levels of Treg percentage, FoxP3 mRNA, and plasma IL-10, while had higher levels of Th22 proportion, AhR mRNA, and plasma IL-22. Tregs from PBC patients showed reduced immunosuppressive activity, which presented as increased cellular proliferation, interferon-γ production and decreased IL-35/IL-10 secretion in co-culture system. Tregs shifted into Th22 phenotype in PBC patients with elevated CCR4, CCR6, and CCR10 expression as well as increased IL-22 production. IL-35 not only enhanced inhibitory function of Tregs but also suppressed phenotype shift of Tregs into Th22 phenotype in PBC patients. This process was accompanied by elevation of IL-10 and transforming growth factor-β1 secretion by Tregs from PBC patients. The present data suggested that reduced IL-35 might be insufficient to maintain Tregs function and phenotype shift from Tregs into Th22 phenotype in PBC patients.

Many Ways to Communicate-Crosstalk between the HBV-Infected Cell and Its Environment

Chronic infection with the hepatitis B virus (HBV) affects an estimated 257 million people worldwide and can lead to liver diseases such as cirrhosis and liver cancer. Viral replication is generally considered not to be cytopathic, and although some HBV proteins may have direct carcinogenic effects, the majority of HBV infection-related disease is related to chronic inflammation resulting from disrupted antiviral responses and aberrant innate immune reactions. Like all cells, healthy and HBV-infected cells communicate with each other, as well as with other cell types, such as innate and adaptive immune cells. They do so by both interacting directly and by secreting factors into their environment. Such factors may be small molecules, such as metabolites, single viral proteins or host proteins, but can also be more complex, such as virions, protein complexes, and extracellular vesicles. The latter are small, membrane-enclosed vesicles that are exchanged between cells, and have recently gained a lot of attention for their potential to mediate complex communication and their potential for therapeutic repurposing. Here, we review how HBV infection affects the communication between HBV-infected cells and cells in their environment. We discuss the impact of these interactions on viral persistence in chronic infection, as well as their relation to HBV infection-related pathology.

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.

Serum Interleukins as Potential Prognostic Biomarkers in HBV-Related Acute-on-Chronic Liver Failure

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is relatively common in China and has complex pathogenesis, difficult clinical treatment, and poor prognosis. Immune status is an important factor affecting ACLF prognosis. Interleukins are a family of secreted lymphocyte factors that interact with a host of cell types including immune cells. These signaling molecules play important roles in transmitting information; regulating immune cells; mediating the activation, proliferation, and differentiation of T and B cells; and modulating inflammatory responses. Many studies have investigated the correlation between interleukin expression and the prognosis of HBV-ACLF. This review focuses on the potential use of interleukins as prognostic biomarkers in HBV-ACLF. References were mainly identified through PubMed and CNKI search, including relevant studies published until December 2021. We have summarized reports of several promising diagnostic interleukin biomarkers that predict susceptibility to HBV-ACLF. The use of biomarkers to understand early prognosis can help devise different therapeutic measures and improve patient survival. Ongoing research on prognostic biomarkers of HBV-ACLF is promising, and future preclinical and clinical studies are warranted.

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.

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

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

The Mechanism of Interleukin-35 in Chronic Hepatitis B

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

Activation of Toll-like receptor 2 enhances peripheral and tumor-infiltrating CD8+ T cell cytotoxicity in patients with gastric cancer

BACKGROUND

Toll-like receptors (TLRs) play central roles in the initiation of innate immune response, and also control adaptive immunity activation. Thus, the aim of the study was to investigate the regulation of TLR activation to CD8⁺ T cells has not been fully elucidated in gastric cancer (GC).

MATERIALS AND METHODS

Thirty-two GC patients and twenty-three healthy controls were enrolled. Expression profile of TLRs in peripheral and tumor-infiltrating CD8⁺ T cells was investigated. Purified CD8⁺ T cells were stimulated with Pam3Csk4, an agonist of TLR2, and cytotoxic and co-inhibitory molecules in CD8⁺ T cells was measured. Direct and indirect contact coculture system between CD8⁺ T cells and AGS cells was set up. Modulation of TLR2 activation to CD8⁺ T cells was assessed by measuring lactate dehydrogenase release and cytokine secretion.

RESULTS

TLR2 mRNA and TLR2⁺ cell percentage was down-regulated in GC derived peripheral and tumor-infiltrating CD8⁺ T cells. CD8⁺ T cells from GC patients showed exhausted phenotype, which presented as decreased perforin/granzyme B, increased programmed death-1, and reduced cytotoxicity to AGS cells. TLR2 activation by Pam3Csk4 enhanced perforin and granzyme B expression in CD8⁺ T cells, however, did not affect either proinflammatory cytokine production or co-inhibitory molecules expression. Pam3Csk4 stimulation enhanced cytolytic activation of peripheral and tumor-infiltrating CD8⁺ T cells from GC, but not those from healthy individuals.

CONCLUSION

The present data revealed an important immunomodulatory activity of TLR2 to CD8⁺ T cells in GC patients.

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

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

Immunopathology of Chronic Hepatitis B Infection: Role of Innate and Adaptive Immune Response in Disease Progression

More than 250 million people are living with chronic hepatitis B despite the availability of highly effective vaccines and oral antivirals. Although innate and adaptive immune cells play crucial roles in controlling hepatitis B virus (HBV) infection, they are also accountable for inflammation and subsequently cause liver pathologies. During the initial phase of HBV infection, innate immunity is triggered leading to antiviral cytokines production, followed by activation and intrahepatic recruitment of the adaptive immune system resulting in successful virus elimination. In chronic HBV infection, significant alterations in both innate and adaptive immunity including expansion of regulatory cells, overexpression of co-inhibitory receptors, presence of abundant inflammatory mediators, and modifications in immune cell derived exosome release and function occurs, which overpower antiviral response leading to persistent viral infection and subsequent immune pathologies associated with disease progression towards fibrosis, cirrhosis, and hepatocellular carcinoma. In this review, we discuss the current knowledge of innate and adaptive immune cells transformations that are associated with immunopathogenesis and disease outcome in CHB patients.

In vivo and in vitro Evaluation of Cytokine Expression Profiles During Middle East Respiratory Syndrome Coronavirus (MERS-CoV) Infection

Background

Middle East respiratory syndrome coronavirus (MERS-CoV) first emerged in the Kingdom of Saudi Arabia, is associated with a high mortality rate.

Aim

To determine the effect of MERS-CoV on the immune response in infected patients and investigate cytokine production in the A549 epithelial cell line in response to a recombinant MERS-CoV spike protein (rSP) in the presence or absence of anti-dipeptidyl peptidase 4 (DPP4) antibody (3 independent experiments). Cytokine levels were measured using a cytokine ELISA array.

Methods

A Bio-Plex multiplex assay and cytokine ELISA were used in our study to measure the cytokine levels.

Results

Comparative analysis of MERS-CoV-infected patients (4 samples) and noninfected healthy controls (HCs) (5 samples) showed that serum levels of the following cytokines and chemokines were significantly higher in MERS-CoV patients than in the HCs (*p < 0.05): interferon (IFN)-α2 (43.4 vs 5.4), IFN-β (17.7 vs 6.2), IFN-γ (43.4 vs 9.7), interleukin (IL)-8 (13.7 vs 0), IL-2 (11.2 vs 3), IL-27p28 (57.8 vs 13.8), and IL-35 (167.5 vs 87.5).

Discussion

Our results revealed that MERS-CoV infection induced a slight increase in IFN levels but triggered a more pronounced increase in expression of the regulatory cytokines IL-27 and IL-35. A recombinant version of the full-length MERS-CoV spike protein increased the expression of IL-8 (160 pg/mL), IL-2 (100 pg/mL) and IL-12 (65 pg/mL) in A549 lung epithelial cells compared to that in the unstimulated control cells. The presence of anti-DPP4 antibody did not affect cytokine suppression or induction in A549 cells in vitro but decreased the level of IL-8 from 160 pg/mL to 65 pg/mL.

Conclusion

MERS-CoV can decrease IFN levels to interfere with the IFN pathway and enhance the production of regulatory cytokines. Inhibition of the increases in IL-27 and IL-35 may contribute to halting MERS-CoV in the early stage of infection.

The Effect of Unconventional Cytokine Combinations on NK-Cell Responses to Viral Infection

Cytokines are soluble and membrane-bound factors that dictate immune responses. Dogmatically, cytokines are divided into families that promote type 1 cell-mediated immune responses (e.g., IL-12) or type 2 humoral responses (e.g., IL-4), each capable of antagonizing the opposing family of cytokines. The discovery of additional families of cytokines (e.g., IL-17) has added complexity to this model, but it was the realization that immune responses frequently comprise mixtures of different types of cytokines that dismantled this black-and-white paradigm. In some cases, one type of response may dominate these mixed milieus in disease pathogenesis and thereby present a clear therapeutic target. Alternatively, synergistic or blended cytokine responses may obfuscate the origins of disease and perplex clinical decision making. Most immune cells express receptors for many types of cytokines and can mediate a myriad of functions important for tolerance, immunity, tissue damage, and repair. In this review, we will describe the unconventional effects of a variety of cytokines on the activity of a prototypical type 1 effector, the natural killer (NK) cell, and discuss how this may impact the contributions of these cells to health and disease.

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

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

Role of CD4+ T Cells in the Control of Viral Infections: Recent Advances and Open Questions

CD4+ T cells orchestrate adaptive immune responses through their capacity to recruit and provide help to multiple immune effectors, in addition to exerting direct effector functions. CD4+ T cells are increasingly recognized as playing an essential role in the control of chronic viral infections. In this review, we present recent advances in understanding the nature of CD4+ T cell help provided to antiviral effectors. Drawing from our studies of natural human immunodeficiency virus (HIV) control, we then focus on the role of high-affinity T cell receptor (TCR) clonotypes in mediating antiviral CD4+ T cell responses. Last, we discuss the role of TCR affinity in determining CD4+ T cell differentiation, reviewing the at times divergent studies associating TCR signal strength to the choice of a T helper 1 (Th1) or a T follicular helper (Tfh) cell fate.

Interleukin-35: An emerging player in the progression of liver diseases

Interleukin-35(IL-35), a newly identified immunosuppressive cytokine, has recently been shown to play a significant role in the progression of various autoimmune diseases and malignant tumors. The liver is the largest organ in the body and is generally regarded as an important lymphoid organ by an increasing number of immunologists. A number of reports have demonstrated that IL-35 plays essential roles in maintaining the immune homeostasis of the liver microenvironment. This review summarizes the existing studies of IL-35 in liver diseases, including viral hepatitis, immune liver injury, liver cirrhosis and carcinoma. We aimed to provide a comprehensive overview of the vital roles of IL-35 in hepatic damage and explore new alternative therapeutic targets for these diseases.

Serum Interleukin-35 Level in Correlation with T Regulatory and T helper-17 Cells Frequency in Chronic Viral Hepatitis C Patients

Interleukin-35 (IL-35), secreted mainly by T-regulatory cells (T-regs), has been considered to have immunosuppressive actions in many auto-immune diseases and tumors. However, information about its role in chronic hepatitis C (CHC) infection is still limited. We aimed to study the role of IL-35 within CHC infection and to assess its correlation with T-regs and T-helper 17 cells (Th-17). Therefore, we measured serum IL-35 concentrations using ELISA assay in 25 normal controls (NCs) and in 30 CHC patients before receiving direct antiviral agents (DAA) treatment and after 3 months of treatment end. T-regs and Th-17 cells frequencies were assessed via flow-cytometry in control group and patients’ group before treatment. The results showed that serum IL-35 levels revealed a highly significant increase in CHC patients compared to NCs (P <0.001). Moreover, IL-35 levels significantly decreased in patients 3 months after treatment end (P =0.02). Both Th-17 and T-regs were significantly increased in patients more than in NCs and a positive correlation was observed between them. However, T-regs/Th-17 ratio did not show significant difference from the ratio in NCs. IL-35 levels were positively correlated with viral load and T-regs frequency, but not with Th-17 frequency. IL-35 levels did not correlate with liver enzymes or functions. These results suggested that IL-35 enhances the immunosuppressive functions of T-regs, protecting the liver from HCV induced damage and contributes to viral persistence. IL-35 may represent a possible immunotherapeutic strategy for chronic persistent infection if given with DAA, especially in relapsing or non-responding cases.

Interleukin-35 Suppresses CD8+ T Cell Activity in Patients with Viral Hepatitis-Induced Acute-on-Chronic Liver Failure

BACKGROUND

Interleukin (IL)-35 is a newly indentified cytokine and induces immunotolerance via suppression of CD8⁺ T cell activity in chronic viral hepatitis.

AIMS

To investigate the modulatory function of IL-35 to CD8⁺ T cells in viral hepatitis-induced acute-on-chronic liver failure (ACLF).

METHODS

Fifty-five ACLF patients and 21 healthy controls were enrolled. Serum IL-35 concentration was measured by ELISA. Absolute accounts for T cells, immune checkpoint molecules, and cytotoxic molecules in CD8⁺ T cells were measured by flow cytometry and real-time PCR, respectively. Direct and indirect contact co-culture systems between CD8⁺ T cells and HepG2 cells were set up. The regulatory function of IL-35 to CD8⁺ T cells was assessed by measuring lactate dehydrogenase expression and cytokine production.

RESULTS

Serum IL-35 concentration was elevated in ACLF patients and positively correlated with total bilirubin, but negatively correlated with prothrombin time activity. Peripheral CD8⁺ T cells showed exhausted phenotype in ACLF patients, which manifested as up-regulation of programmed death-1 (PD-1), cytotoxic T-lymphocyte-associated protein-4 (CTLA-4), and lymphocyte activation gene-3 (LAG-3) but down-regulation of perforin, granzyme B, and FasL. Recombinant IL-35 stimulation dampened cytotoxicity and interferon-γ production in both direct and indirect contact co-culture systems. This process was accompanied by elevation of PD-1, CTLA-4, and LAG3, as well as reduction of perforin, granzyme B, and FasL in CD8⁺ T cells.

CONCLUSION

Elevated IL-35 suppressed both cytolytic and non-cytolytic activity of CD8⁺ T cells in ACLF patients.

Cytokine, Genotype, and Viral Load Profile in the Acute and Chronic Hepatitis B

Several hepatitis B virus (HBV) factors, including viral load, genotype, genome mutations, and cytokine production, have been reported to be associated with different risks of progression of liver disease. The aim of this study was to verify if there is an association among the levels of cytokines (interleukin [IL]-35, IL-6, IL-17A, interferon [IFN]-γ) in the plasma, viral load, and the different genotypes of HBV in patients with acute or chronic hepatitis B. Methods: 49 serum samples, 20 from acute and 29 from chronic cases, were submitted to a real-time and nested-polymerase chain reaction to quantify, detect, and genotype HBV DNA. The cytokines IL-35, IL-6, IL-17A, and IFN-γ were detected by an enzyme-linked immunosorbent assay (ELISA). The median viral load was 3.15 log₁₀ IU DNA/mL and 2.90 log₁₀ IU DNA/mL for acute and chronic patients, respectively. Genotype A, D, E, and F were identified in chronic carriers of HBV infection, while only genotype A and F were identified in individuals with acute infection. IFN-γ (p = 0.024) and IL-17A (p = 0.046) levels were significantly increased in chronic patients and IL-6 and IL-35 were higher in patients with acute infection, however, without statistical difference. IL-17A and IFN-γ can be modulating proinflammatory effects and inducing hepatocellular damage, in chronic patients, and IL-6 and IL-35 may be involved in viral elimination and protection against chronicity during the acute phase of infection. These results can contribute to understanding of the complex regulatory mechanisms of the host antiviral response related to cytokine production during acute and chronic HBV infection.

Current strategies against COVID-19

Coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recently was declared a pandemic by world health organization (WHO) Due to sudden outbreaks, currently, no completely effective vaccine or drug is clinically approved. Several therapeutic strategies can be envisaged to prevent further mortality and morbidity. Based on the past contribution of traditional Chinese medicines (TCM) and immune-based therapies as a treatment option in crucial pathogen outbreaks, we aimed to summarize potential therapeutic strategies that could be helpful to stop further spread of SARS-CoV-2 by effecting its structural components or modulation of immune responses. Several TCM with or without modification could be effective against the structural protein, enzymes, and nucleic acid should be tested from available libraries or to identify their immune-stimulatory activities to enhance several antiviral biological agents for effective elimination of SARS-CoV-2 from the host. TCM is not only effective in the direct inhibition of virus attachment and internalization in a cell but can also prevent their replication and can also help to boost up host immune response. Immune-modulatory effects of TCMs may lead to new medications and can guide us for the scientific validity of drug development. Besides, we also summarized the effective therapies in clinical for controlling inflammation. This review will be not only helpful for the current situation of COVID-19, but can also play a major role in such epidemics in the future.

Immunoregulatory Functions of the IL-12 Family of Cytokines in Antiviral Systems

Members of the interleukin 12 (IL-12) family have been known to be inflammatory factors since their discovery. The IL-12 family consists of IL-12, IL-23, IL-27, IL-35, and a new member, IL-39, which has recently been identified and has not yet been studied extensively. Current literature has described the mechanisms of immunity of these cytokines and potential uses for therapy and medical cures. IL-12 was found first and is effective in combatting a wide range of naturally occurring viral infections through the upregulation of various cytokines to clear the infected cells. IL-23 has an essential function in immune networks, can induce IL-17 production, and can antagonize inhibition from IL-12 in the presence of T helper (Th) 17 cells, resulting in type II IFN (IFN-γ) regulation. IL-27 has a competitive relationship to IL-35 because they both include the same subunit, the Epstein–Barr virus-induced gene3 (EBi3). This review provides a simple introduction to the IL-12 family and focuses on their functions relevant to their actions to counteract viral infections.

Notch signaling suppresses CD14+ monocytes cells activity in patients with chronic hepatitis C

Hepatitis C virus (HCV) infection always leads to chronic hepatitis via dysregulation of host immunity. Notch signaling also modulates the response of monocytes/macrophages. Thus, we aimed to investigate the regulatory role of Notch signaling to CD14⁺ monocytes. Forty patients with chronic hepatitis C and twenty normal controls (NC) were enrolled. CD14⁺ monocytes and CD4⁺ T cells were purified from peripheral bloods. Notch receptors' mRNA expression in CD14⁺ monocytes was semi-quantified by real-time PCR. Cytokine production by CD14⁺ monocytes in response to γ-secretase inhibitor (GSI) was investigated by ELISA. GSI-induced CD14⁺ monocytes activity to HCV clearance in Huh7.5 cells and to CD4⁺ T cell differentiation was also assessed in direct and indirect contact co-culture system. Notch1 mRNA relative level was approximately 10-fold elevated in CD14⁺ monocytes from chronic hepatitis C patients when compared with NC. GSI stimulation resulted in enhanced cytokines production by CD14⁺ monocytes from chronic hepatitis C patients. GSI-stimulated CD14⁺ monocytes from chronic hepatitis C patients induced suppression of HCV RNA replication in both direct and indirect contact co-culture system of CD14⁺ monocytes and HCVcc-infected Huh7.5 cells, and this process was accompanied by elevation of interferon-γ production but not increased target cell death. Moreover, GSI stimulation also enhanced CD14⁺ monocytes-induced Th1 and Th17 cells activation, and this process required direct cell-to-cell contact. Effective antiviral therapy down-regulated Notch1 mRNA expression and promoted cytokine production by CD14⁺ monocytes from chronic hepatitis C. Current data revealed an important immunoregulatory property of Notch signaling to CD14⁺ monocytes in chronic HCV infection.

IL-35 inhibits CD8+ T cells activity by suppressing expression of costimulatory molecule CD28 and Th1 cytokine production

Background

Interleukin-35 (IL-35), a novel immune-suppressing cytokine, can promote tumor angiogenesis and inhibits anti-tumor cytotoxic lymphocyte response. Here, we aimed to investigate the potential mechanism of the effects of IL-35 on anti-tumor cytotoxic lymphocyte.

Methods

Dendritic cells (DCs) were used to induce anti-tumor cytotoxic lymphocyte. Flow cytometry, carboxyfluorescein succinimidyl ester staining, ELISA assay and western blotting were used to analyze the effect of IL-35 on anti-tumor cytotoxic lymphocyte.

Results

We observed that IL-35 inhibited the expression of costimulatory molecule CD28 on CD8⁺ T cell surface and Th1 cytokine production. However, IL-35 did not inhibit anti-tumor cytotoxic lymphocyte proliferation nor enhance the expression of apoptosis-related proteins of anti-tumor cytotoxic lymphocyte. Moreover, IL-35 did not repress the expression of Fas ligand (FasL) on cytotoxic lymphocyte surface.

Conclusions

Our findings revealed that IL-35 can inhibit CD8⁺ T cells activity by suppressing the expression of costimulatory molecule CD28 and Th1 cytokine production.

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

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

Elevated interleukin-35 suppresses liver inflammation by regulation of T helper 17 cells in acute hepatitis B virus infection

Interleukin (IL)-35 is a responsive anti-inflammatory cytokine implicated in different diseases processes. It has been reported that elevated IL-35 contributed to immunosuppression in chronic hepatitis by modulation of T helper 17 (Th17) and regulatory T cells. However, the role of IL-35 in acute hepatitis B (AHB) was still not completely elucidated. Thus, in the present study, we analyzed the expression and regulatory activity of IL-35 to Th17 cells and inflammatory response during acute hepatitis B virus (HBV) infection in both peripheral blood cells isolated from AHB patients and in hydrodynamic induced HBV-infected mouse model. Plasma IL-35 level and circulating HBV peptides-induced Th17 frequency was significantly elevated in AHB patients, and IL-35 expression negatively correlated with liver inflammation. In vitro IL-35 stimulation to CD4+ T cells purified from AHB patients down-regulated HBV peptides-induced Th17-phenotype, which presented as reduced IL-17 and IL-22 production. In vivo IL-35 administration dampened liver inflammation in HBV plasmid injected mice, however, did not affect HBV antigens production. This process was accompanied by suppression of natural killer cells and down-regulation of HBV peptides-induced Th17 cells in the liver, but did not affect total intrahepatic lymphocytes and other cell subsets numbers or chemokines expression in the liver. In conclusion, the current data indicated that IL-35 might be a novel mediator associated with hepatocytes damage and liver inflammation by regulating HBV peptides-induced Th17 cells during acute HBV infection. The potential anti-inflammatory property of IL-35 might be pivotal for developing new therapeutic approaches for hepatitis B.

Interleukin-35 modulates the balance between viral specific CD4+CD25+CD127dim/- regulatory T cells and T helper 17 cells in chronic hepatitis B virus infection

Background

Interleukin (IL)-35 regulates imbalance between regulatory T cells (Tregs) and T helper (Th) 17 cells, leading to an important modulator in autoimmune disorder, cancer, and infectious diseases. Our previous study revealed an immunosuppressive activity of IL-35 in chronic hepatitis B virus (HBV) infection. Thus, the aim of the current study was to investigate the role of regulatory function of IL-35 to viral specific Tregs/Th17 cells balance in chronic HBV infection.

Methods

A total of 44 HLA-A2 restricted chronic HBV infected patients, including 21 of chronic hepatitis B (CHB) and 23 of asymptomatic HBV carriers (ASC) were enrolled. Purified CD4⁺ T cells or CD4⁺CD25⁺CD127^dim/− Tregs were stimulated with recombinant IL-35. HBV core antigen specific Tregs and Th17 cells were determined by flow cytometry. FoxP3 and RORγt mRNA was measured by real-time PCR. Cytokines production (IL-10 and IL-17) was investigated by ELISA.

Results

Peripheral viral specific Tregs was comparable between CHB and ASC. However, increased percentage of viral specific Th17 cells was found in CHB, leading to the reduction of Tregs/Th17 ratio in CHB patients. IL-35 stimulation elevated viral specific Tregs, but not Th17 cells frequency, in both CHB and ASC, resulting in the elevation of Tregs/Th17 ratio in both groups. This process was accompanied by increased expression of FoxP3 mRNA and IL-10 production, and decreased IL-17 secretion and STAT3 phosphorylation in purified CD4⁺ T cells. Moreover, IL-35 stimulation inhibited viral specific Th17-like phenotype differentiation from Tregs in CHB patients. Effective anti-HBV therapy did not affect viral specific Tregs/Th17 cells frequency or IL-35 expression in CHB patients, however, reduced responsiveness of CD4⁺ T cells or Tregs to IL-35 stimulation in vitro.

Conclusion

Our findings indicated that IL-35 regulation to viral specific Tregs/Th17 balance may contribute to viral persistence in chronic HBV infection.

Spleen-Associated Effects on Immunity in Hepatitis B Virus-Related Cirrhosis with Portal Hypertension

Our study aimed to investigate the histologic and immunological changes of portal hypertension (PH) pre- and postsplenectomy in hepatitis B virus (HBV)-related cirrhosis. Peripheral blood samples were obtained from 30 patients with HBV-related cirrhosis and PH at pre- and postsplenectomy time points and from 15 healthy subjects. Spleen tissue specimens were collected from 15 of the patients with HBV-related cirrhosis and from 8 control patients who had undergone splenectomy due to trauma. Immunohistochemical staining was performed to evaluate the immune effector cells and the expression of negative immune regulators. Flow cytometry was used to investigate the immunophenotypes and percentages. The spleen of cirrhotic patients with PH showed extensive depletion of splenic CD4, CD8, and human leukocyte antigen DR cells along with overexpression of the inhibitory receptors programmed death-1 (PD-1) and T cell immunoglobulin domain and mucin domain-3 and their ligands (PD-L2 and galectin-9). Peripheral blood of patients with PH showed remarkable decrease in proportions of CD8 T cell and natural killer (NK) cells and increase in regulatory T (Treg) cells, as well as high expression of PD-1 in CD4/8 T cells. Compared with presplenectomy patients, cirrhotic patients with PH showed increased proportions of CD8 and NK cells, decreased proportion of Treg cells, and decreased expression of PD-1 in peripheral blood CD4/8 T cells after splenectomy. PH-spleen could lead to peripheral tolerance and immunosuppression in HBV cirrhotic patients, and splenectomy may cause beneficial immunological changes.

Notch signaling pathway suppresses CD8+ T cells activity in patients with lung adenocarcinoma

Evolution and progression of cancer always leads to CD8⁺ T cells dysfunction/exhaustion. Controversy remains as to the role of Notch signaling pathway in CD8⁺ T cells regulation in tumorigenesis. Thus, the aim of this study was to investigate the immunomodulatory activity of Notch signaling pathway to peripheral and lung-resident CD8⁺ T cells in patients with lung adenocarcinoma. Forty-eight lung adenocarcinoma patients and twenty healthy individuals were enrolled in the current study, and CD8⁺ T cells were purified from both peripheral bloods and bronchoalveolar lavage fluids. Notch receptor mRNA expression was semi-quantified by real-time PCR. Cytolytic and noncytolytic activity of CD8⁺ T cells evaluated in direct and indirect contact co-culture with A549 cells in response to Notch signaling inhibition by measuring of lactate dehydrogenase release and cytokines production. Expression of Fas ligand (FasL), perforin, and granzyme B were also assessed by flow cytometry. Notch2 mRNA expression was elevated in both peripheral and lung-resident CD8⁺ T cells in lung adenocarcinoma patients, however, did not correlated with tumor stages or epidermal growth factor receptor mutation. Peripheral CD8⁺ T cells from healthy individuals exhibited stronger cytotoxicity in direct contact co-culture system, which was not influenced by Notch signaling inhibition. Moreover, suppression of Notch signaling augmented cytotoxicity of peripheral and lung-resident CD8⁺ T cells from lung adenocarcinoma patients in direct contact co-culture system, and promoted interferon-γ production in both systems. This process was accompanied by increased expression of FasL and perforin within CD8⁺ T cells. The current data revealed a potential immunosuppressive property of Notch signaling pathway to CD8⁺ T cells probably via inhibition of FasL and perforin in lung adenocarcinoma patients.