Pivotal roles of the interleukin-23/T helper 17 cell axis in hepatitis B

Differential T-cell profiles determined by Hepatitis B surface antigen decrease among people with Human Immunodeficiency Virus /Hepatitis B Virus coinfection on treatment

BACKGROUND

Several studies have reported that combination antiretroviral therapy (cART) enhances the hepatitis B surface antigen (HBsAg) clearance rate in Human Immunodeficiency Virus-1/Hepatitis B Virus (HIV/HBV) coinfected patients, yet the associated immunological characteristics remain unclear.

METHODS

Global and specific immune phenotypic profiles were examined in 48 patients with HIV/HBV coinfection before cART and at 1-year, and 3-year after cART using flow cytometry. In addition, 61 patients with HBV monoinfection were included for comparison.

RESULTS

HBsAg response (sAg-R) was defined as > 0.5 log decrease within six months of cART initiation, and 16 patients achieved it. Patients with sAg-R (the sAg-R group) exhibited distinct immune phenotypes compared to those of HBsAg-retained patients (the sAg-NR group). Notably, patients with sAg-R had lower CD4+ T cell counts and a higher number of HBcAg-specific T cells. Further, the sAg-R group exhibited upregulation of HLA-DR, Ki67, and PD-1 in CD4+ T cells and heightened HLA-DR and T-bet in CD8+ T cells. However, the sAg-R group had fewer TEMRA cells but more TEM and Th17 cells than those in the sAg-NR group. Expression of various markers, including HLA-DR+CD4+, Ki67+CD4+, PD-1+CD4+, CD38+CD8+, HLA-DR+CD8+, TIM-3+CD8+, HBV-specific CD4+ T cell secreting IFN-γ and IL-2, and specific CD8+ T cell secreting IFN-γ and IL-2, correlated with HBsAg decrease.

CONCLUSION

The decline in HBsAg levels during cART in HIV/HBV coinfection involves significant alterations in CD4+ and CD8+ T cells phenotypes, offering a novel perspective on a functional HBV cure.

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.

Safety of secukinumab in the treatment of patients with axial spondyloarthritis and concurrent hepatitis B virus infection or latent tuberculosis infection

OBJECTIVE

To evaluate the safety of secukinumab (SEC) in the treatment of patients with axial spondyloarthritis (axSpA) and concurrent hepatitis B virus (HBV) infection or latent tuberculosis infection (LTBI).

METHODS

This is a retrospective cohort study. Adult axSpA patients with HBV infection or LTBI receiving SEC treatment for at least 3 months from March 2020 to July 2022 in Guangdong Provincial People's Hospital were included. Patients were screened for HBV infection and LTBI before SEC treatment. During follow-up, reactivation of HBV infection and LTBI was monitored. Relevant data were collected and analyzed.

RESULTS

A total of 43 axSpA patients with HBV infection or LTBI were included, of whom 37 were with HBV infection, 6 were with LTBI. Six out of thirty-seven (16.2%) patients with axSpA and concurrent HBV infection exhibited HBV reactivation after 9.0 ± 5.7 months of SEC treatment. Among them, 3 patients had chronic HBV infection and received anti-HBV prophylaxis, 2 patients had chronic HBV infection but did not receive anti-HBV prophylaxis, and 1 patient had occult HBV infection and did not receive antiviral prophylaxis. None of the 6 axSpA patients with LTBI developed reactivation of LTBI, whether received anti-TB prophylaxis or not.

CONCLUSIONS

HBV reactivation can occur in axSpA patients with different types of HBV infection undergoing SEC treatment, whether receive antiviral prophylaxis or not. Close monitoring of HBV reactivation in axSpA patients with HBV infection undergoing SEC treatment is mandatory. Anti-HBV prophylaxis may be beneficial. In contrast, SEC may be safe in axSpA patients with LTBI, even in patients not receiving anti-TB prophylaxis. Key Points •Currently, most evidence about the safety of SEC in patients with HBV infection and LTBI were from patients with psoriasis. Our study adds data about the safety of SEC in Chinese axSpA patients with concurrent HBV infection or LTBI in real-world clinical setting. •Our study showed that HBV reactivation can occur in axSpA patients with different types of HBV infection undergoing SEC treatment, whether receive antiviral prophylaxis or not. •Close monitoring of serum HBV markers, HBV DNA load, and liver function is mandatory in axSpA patients with chronic, occult, and resolved HBV infection undergoing SEC treatment. Anti-HBV prophylaxis may be beneficial in all HBsAg-positive patients and HBsAg-negative, HBcAb-positive patients at high risk of HBV reactivation who are receiving SEC therapy. •None of the axSpA patients with LTBI, whether received anti-TB prophylaxis or not, developed reactivation of LTBI in our study. SEC may be safe in axSpA patients with LTBI, even in patients not receiving anti-TB prophylaxis.

Host immunity and HBV S gene mutation in HBsAg-negative HBV-infected patients

Background

Clinically, some patients whose HBsAg becomes negative owing to antiviral therapy or spontaneously still show a low level of HBV DNA persistence in serum. T-lymphocyte subsets, cytokine levels and HBV S gene sequences were analyzed in this study.

Methods

A total of 52 HBsAg-negative and HBV DNA-positive patients(HBsAg-/HBV DNA+ patients), 52 persistently HBsAg-positive patients(HBsAg+/HBV DNA+ patients) and 16 healthy people were evaluated. T-lymphocyte subsets of these patients were detected by flow cytometry, serum cytokines and chemokines were detected by the Luminex technique, and the HBV S region was evaluated by Sanger sequencing. T%, T-lymphocyte, CD8+ and CD4+T lymphocyte were lower in the HBsAg-negative group than in the HC group. Compared with the HBsAg-positive group, the HBsAg-negative group had lower levels in T lymphocyte %, CD8+T lymphocyte %, CD8+T lymphocyte and CD4/CD8. These difference were statistically significant (P<0.05). Serum IFN-γ, IFN-α and FLT-3L levels were significantly higher in the HBsAg-negative group than in the HBsAg-positive group (P<0.05). However, levels of many cytokines related to inflammation (i.e., IL-6, IL-8, IL10, IL-12, IL-17A) were lower in the HBsAg-negative group. Fifty-two HBsAg-negative samples were sequenced, revealing high-frequency amino acid substitution sites in the HBV S protein, including immune escape mutations (i.e., Y100C, S114T, C124Y, P127L, G130R, T131N, M133T, C137S, G145A) and TMD region substitutions (i.e., E2K/R/D, G7D/R, G10D, A17R, F20L/S, L21V, L22V).

Conclusions

According to the results of T-lymphocyte subsets and serum cytokines, it can be deduced that the cellular immune function of HBsAg-negative patients is superior to that of HBsAg-positive patients, with attenuation of liver inflammation. HBsAg-negative patients may show a variety of mutations and amino acid replacement sites at high frequency in the HBV S region, and these mutations may lead to undetectable HBsAg, HBsAg antigenic changes or secretion inhibition.

The Double Game Played by Th17 Cells in Infection: Host Defense and Immunopathology

T-helper 17 (Th17) cells represent a subpopulation of CD4+ T lymphocytes that play an essential role in defense against pathogens. Th17 cells are distinguished from Th1 and Th2 cells by their ability to produce members of the interleukin-17 (IL-17) family, namely IL-17A and IL-17F. IL-17 in turn induces several target cells to synthesize and release cytokines, chemokines, and metalloproteinases, thereby amplifying the inflammatory cascade. Th17 cells reside predominantly in the lamina propria of the mucosa. Their main physiological function is to maintain the integrity of the mucosal barrier against the aggression of infectious agents. However, in an appropriate inflammatory microenvironment, Th17 cells can transform into immunopathogenic cells, giving rise to inflammatory and autoimmune diseases. This review aims to analyze the complex mechanisms through which the interaction between Th17 and pathogens can be on the one hand favorable to the host by protecting it from infectious agents, and on the other hand harmful, potentially generating autoimmune reactions and tissue damage.

Plasma interleukin-7 correlation with human immunodeficiency virus RNA and CD4+ T cell counts, and interleukin-5 with circulating hepatitis B virus DNA may have implications in viral control

Chronic viral infections represent a leading cause of global morbidity and mortality. Chronic HBV, HCV, and HIV infections result in cytokine perturbations that may hold key implications in understanding the complex disease mechanisms driving virus persistence and/or resolution. Here, we determined the levels of various plasma cytokines using a commercial Bio-Plex Luminex cytokine array in chronic HBV (n = 30), HCV (n = 15), and HIV (n = 40) infections and correlated with corresponding plasma viral loads (PVLs) and liver parameters. We observed differential perturbations in cytokine profiles among the study groups. The cytokines levels positively correlated with PVL and liver transaminases. The monocyte-derived cytokines viz., MIP-1β, IL-8, and TNF-α, and Th2 cytokines like IL-4, IL-5, and IL-13 showed a better correlation with liver enzymes as compared to their corresponding PVLs. Our investigation also identified two cytokines viz., IL-5 and IL-7 that inversely correlated with HBV DNA and HIV PVLs, respectively. Regression analysis adjusted for age showed that every increase of IL-5 by one unit was associated with a reduction in HBV PVL by log10 0.4, whereas, every elevation by a unit of IL-7 was associated with decreased HIV PVL by log10 2.5. We also found that IL-7 levels correlated positively with absolute CD4+ T cell counts in HIV-infected patients. We concluded that plasma IL-5 and IL-7 may likely have a key role on viral control in HBV and HIV infections, respectively. A noteworthy increase in cytokines appears to bear protective and pathological significance, and indeed is reflective of the host's versatile immune armory against viral persistence.

The efficacy of pegylated interferon alpha-2a and entecavir in HBeAg-positive children and adolescents with chronic hepatitis B

Background and objectives

Pegylated interferon alpha-2a (peg-IFN α-2a) and entecavir (ETV) are both recommended as the first-line antiviral drugs for chronic hepatitis B (CHB) at present. We aimed to compare the efficacy and safety between peg-IFN α-2a and ETV initial therapy in children and adolescents with CHB and investigate the potential factors affecting the treatment response during the first 48 weeks.

Methods

We retrospectively selected 70 treatment-naïve children and adolescents with CHB who received peg-IFN α-2a(n = 26) or ETV(n = 44) as initial therapy and completed 48-week follow-up for data analysis. Blood samples before treatment were collected from 26 patients of the cohort to assess the cytokine profiles.

Results

We found that initial peg-IFN therapy results in higher rates of hepatitis B surface antigen (HBsAg) serological response (SR) but lower rates of virological and biochemical response rates compared to ETV at week 48. As for achieving hepatitis B e antigen (HBeAg) SR, peg-IFN was comparable to ETV in the univariate analysis and turned out to be better than ETV after adjustment for important baseline factors. We also found that elevated pre-treatment IL-18 level was significantly associated with HBeAg SR, and remained as the only independent factor of predicting HBeAg SR after adjustment for other important factors. No serious adverse effects of the 2 drugs were reported during the 48-week follow-up.

Conclusions

comparing to ETV, peg-IFN was superior in achieving HBsAg and HBeAg SR; higher baseline IL-18 levels were independently associated with HBeAg SR in this study of children and adolescents with CHB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03482-0.

Anti-rheumatic drug-induced hepatitis B virus reactivation and preventive strategies for hepatocellular carcinoma

To date, an estimated 3 million people worldwide have been infected with chronic hepatitis B virus (HBV). Although anti-HBV therapies have improved the long-term survival profile of chronic carriers, viral reactivation still poses a significant challenge for preventing HBV-related hepatitis, hepatocellular carcinoma (HCC), and death. Immuno-modulating drugs, which are widely applied in managing rheumatic conditions, are commonly associated with HBV reactivation (HBVr) as a result of drug-induced immune suppression. However, there are few reports on the risk of HBVr and the medication management plan for HBV carriers, especially rheumatic patients. In this review, we summarize immuno-modulating drug-induced HBVr during rheumatoid therapy and its preventive strategies for HBVr-induced liver diseases, especially cirrhosis and HCC. These findings will assist with developing treatments for rheumatic patients, and prevent HBV-related cirrhosis and HCC.

Cytokine profile during occult hepatitis B virus infection in chronic hepatitis C patients

Background

The hepatitis B virus (HBV) is one of the leading causes of acute, chronic and occult hepatitis (OBI) representing a serious public health threat. Cytokines are known to be important chemical mediators that regulate the differentiation, proliferation and function of immune cells. Accumulating evidence indicate that the inadequate immune responses are responsible for HBV persistency. The aim of this study were to investigate the cytokines IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10 and IL-17A in patients with OBI and verify if there is an association between the levels of these cytokines with the determination of clinical courses during HBV occult infection.

Methods

114 patients with chronic hepatitis C were investigated through serological and molecular tests, the OBI coinfected patients were subjected to the test for cytokines using the commercial human CBA kit. As controls, ten healthy donors with no history of liver disease and 10 chronic HBV monoinfected patients of similar age to OBI patients were selected.

Results

Among 114 HCV patients investigated, 11 individuals had occult hepatitis B. The levels of cytokines were heterogeneous between the groups, most of the cytokines showed higher levels of production detection among OBI/HCV individuals when compared to control group and HBV monoinfected pacients. We found a high level of IL-17A in the HBV monoinfected group, high levels of TNF-α, IL-10, IL-6, IL-4 and IL-2 in OBI/HCV patients.

Conclusion

These cytokines could be involved in the persistence of HBV DNA in hepatocytes triggers a constant immune response, inducing continuous liver inflammation, which can accelerate liver damage and favor the development of liver cirrhosis in other chronic liver diseases.

The role of Th17 cells in viral infections

The present review provides an overview of recent advances regarding the function of Th17 cells and their produced cytokines in the progression of viral diseases. Viral infections alone do not lead to virus-induced malignancies, as both genetic and host safety factors are also involved in the occurrence of malignancies. Acquired immune responses, through the differentiation of Th17 cells, form the novel components of the Th17 cell pathway when reacting with viral infections all the way from the beginning to its final stages. As a result, instead of inducing the right immune responses, these events lead to the suppression of the immune system. In fact, the responses from Th17 cells during persistent viral infections causes chronic inflammation through the production of IL-17 and other cytokines which provide a favorable environment for tumor growth and its development. Additionally, during the past decade, these cells have been understood to be involved in tumor progression and metastasis. However, further research is required to understand Th17 cells' immune mechanisms in the vast variety of viral diseases. This review aims to determine the roles and effects of the immune system, especially Th17 cells, in the progression of viral diseases; which can be highly beneficial for the diagnosis and treatment of these infections.

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.

Hepatitis B Virus Reactivation Potentiated by Biologics

Hepatitis B virus (HBV) reactivation can be a serious complication for patients with chronic or resolved HBV infection when treated with biologics. For HBsAg-positive patients receiving biologics, the risk of HBV reactivation is moderate to high. HBsAg-negative/anti-HBc positive patients are at lower risk of HBV reactivation than HBsAg-positive patients. However, patients taking anti-CD20 agents, such as rituximab, have high risk of HBV reactivation (>10%), so antiviral prophylactic therapies are required. This review provides the different classes of biologics associated with HBV reactivation, stratifies the various reactivation risk levels by HBV status and biologic agent, and discusses management strategies.

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.

Special aspects of biologics treatment in psoriasis: management in pregnancy, lactation, surgery, renal impairment, hepatitis and tuberculosis

Background of the article: Biologics are modern immunomodulatory drugs, whose use in the treatment of psoriasis has led to remarkable results in psoriatic patients. The administration of these agents in special population groups, such as patients with chronic infections and renal impairment, as well as perioperative, pregnant or lactating patients, has not been thoroughly addressed, mostly because these patients are excluded from clinical studies. Materials and methods: This report is an updated systematic overview of the use of biologics in the above-mentioned types of patients and was conducted according to the PRISMA Guidelines for systematic reviews. Articles derived from the databases PubMed, EMBASE and SCOPUS, published between 1999 and 2018, were analyzed for the study. Results: Research efforts as well as clinical reporting are necessary in order to provide more insight on the management of these therapeutic dilemmas. Conclusion: The aim of this review, other than providing a summarized update on the clinical knowledge on this special topic, is also to raise awareness for the need to conduct larger systematic studies in order to adequately evaluate the use of biologics in these special patient categories and therefore draw definite conclusions on their safety profile.

Interleukin-17D and Nrf2 mediate initial innate immune cell recruitment and restrict MCMV infection

Innate immune cells quickly infiltrate the site of pathogen entry and not only stave off infection but also initiate antigen presentation and promote adaptive immunity. The recruitment of innate leukocytes has been well studied in the context of extracellular bacterial and fungal infection but less during viral infections. We have recently shown that the understudied cytokine Interleukin (IL)-17D can mediate neutrophil, natural killer (NK) cell and monocyte infiltration in sterile inflammation and cancer. Herein, we show that early immune cell accumulation at the peritoneal site of infection by mouse cytomegalovirus (MCMV) is mediated by IL-17D. Mice deficient in IL-17D or the transcription factor Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), an inducer of IL-17D, featured an early decreased number of innate immune cells at the point of viral entry and were more susceptible to MCMV infection. Interestingly, we were able to artificially induce innate leukocyte infiltration by applying the Nrf2 activator tert-butylhydroquinone (tBHQ), which rendered mice less susceptible to MCMV infection. Our results implicate the Nrf2/IL-17D axis as a sensor of viral infection and suggest therapeutic benefit in boosting this pathway to promote innate antiviral responses.

Liver Illness and Psoriatic Patients

Psoriasis is a chronic inflammatory disease of the skin affecting approximately 2% of the world's population. Systemic treatments, including methotrexate and cyclosporin, are associated with potential hepatotoxicity, due to either direct liver damage or immunosuppression or both immunomediated and a direct liver injury; therefore, treatment of patients with psoriasis poses a therapeutic challenge. The aim of this minireview is to help clinicians in the management of psoriatic patients who develop signs of liver dysfunction. To find relevant articles, a comprehensive search was performed on PubMed, EMBASE, and Cochrane with appropriate combinations of the following keywords being considered: viral hepatitis, nonalcoholic fatty liver disease, psoriasis, hepatotoxicity, drug toxicity, cholestasis, and autoimmune liver diseases.

High serum resistin associates with intrahepatic inflammation and necrosis: an index of disease severity for patients with chronic HBV infection

BACKGROUND

Studies have revealed that resistin plays a role as an intrahepatic cytokine with proinflammatory activities. This study investigated the association between serum resistin and fibrosis severity and the possible marker role of resistin in the inflammatory process of chronic hepatitis B.

METHODS

In this study, 234 subjects with HBV infection were retrospectively selected, including 85 patients with chronic hepatitis B (CHB), 70 patients with HBV-related liver cirrhosis (LC-B), and 79 patients with HBV-related liver failure (LF-B). Serum levels of resistin, IL-1, IL-6, IL-17, IL-23, TNF-α, and TGF-β1 were assayed by ELISA. Demographic and clinical characteristics of patients were extracted from clinical databases of Taihe Hospital, Hubei University of Medicine, including serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBil), and liver stiffness (LS).

RESULTS

All the selected patients with HBV infection showed significantly increased levels of serum resistin, which was rarely detectable in the healthy controls. Serum resistin levels in patients with CHB, LC-B, and LF-B were 4.119 ± 5.848 ng/mL, 6.370 ± 6.834 ng/mL, and 6.512 ± 6.076 ng/mL, respectively. Compared with the CHB group, patients with LC-B or LF-B presented with significantly higher serum levels of resistin (p < 0.01). On the other hand, all of the enrolled patients had high serum levels of IL-1, IL-6, IL-17, TNF-α, and TGF-β1, but not IL-23. Interestingly, serum levels of resistin was significantly positively correlated with serum levels of TGF-β1 in LC-B patients (R = 0.3090, p = 0.0290), with IL-17 in LC-B (R = 0.4022, p = 0.0038) and LF-B patients (R = 0.5466, p < 0.0001), and with AST (R = 0.4501, p = 0.0036) and LS (R = 0.3415, p = 0.0310) in CHB patients.

CONCLUSIONS

High serum resistin associates with intrahepatic inflammation and necrosis and may be used as an index of disease severity for patients with chronic HBV infection.

Cytokine-Mediated Immunopathogenesis of Hepatitis B Virus Infections

Hepatitis B virus (HBV) infection is a worldwide health problem, with approximately one third of populations have been infected, among which 3-5% of adults and more than 90% of children developed to chronic HBV infection. Host immune factors play essential roles in the outcome of HBV infection. Thus, ineffective immune response against HBV may result in persistent virus replications and liver necroinflammations, then lead to chronic HBV infection, liver cirrhosis, and even hepatocellular carcinoma. Cytokine balance was shown to be an important immune characteristic in the development and progression of hepatitis B, as well as in an effective antiviral immunity. Large numbers of cytokines are not only involved in the initiation and regulation of immune responses but also contributing directly or indirectly to the inhibition of virus replication. Besides, cytokines initiate downstream signaling pathway activities by binding to specific receptors expressed on the target cells and play important roles in the responses against viral infections and, therefore, might affect susceptibility to HBV and/or the natural course of the infection. Since cytokines are the primary causes of inflammation and mediates liver injury after HBV infection, we have discussed recent advances on the roles of various cytokines [including T helper type 1 cells (Th1), Th2, Th17, regulatory T cells (Treg)-related cytokines] in different phases of HBV infection and cytokine-related mechanisms for impaired viral control and liver damage during HBV infection. We then focus on experimental therapeutic applications of cytokines to gain a better understanding of this newly emerging aspect of disease pathogenesis.

Involvement of the Interleukin-23/Interleukin-17 Axis in Chronic Hepatitis C Virus Infection and Its Treatment Responses

Interleukin-23 (IL-23) and its downstream factor IL-17 are the key cytokines involved in immune and inflammatory response in chronic liver diseases. This study aimed to investigate the role and molecular mechanisms of the IL-23/Th17 axis in chronic hepatitis C virus (HCV) infection, and the efficacy of IL-23/Th17 modulation in response to anti-HCV therapy. Sixty-six HCV-infected patients and 20 healthy controls were enrolled. The patients received PegIFNa-2a and ribavirin therapy for at least 48 weeks. The plasma level of IL-23 and the number of IL-17A-, IFN-γ-, and IL-21-producing peripheral blood mononuclear cells (PBMCs) at baseline and 12, 24, and 48 weeks following treatment were determined. The mRNA level of Th17 immune-associated molecules in PBMCs was evaluated by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) following treatment with IL-23 agonist or antagonist. Our data showed that, compared to healthy controls, HCV-infected patients had an increased plasma level of IL-23 and increased frequencies of IL-17A- and IFN-γ-producing PBMCs, whereas the HCV patients exhibited a reduced number of IL-21-producing PBMCs. However, the baseline frequencies of IL-21-producing PBMCs were markedly higher in HCV patients who achieved rapid virological response (RVR) than those without RVR. Additionally, the mRNA expressions of IL-21, IFN-γ, myxovirus resistance protein A (MxA), and suppressor of cytokine signaling 3 (SOCS3) were significantly upregulated in PBMCs, while FoxP3 expression was suppressed by IL-23 agonist. Thus, the IL-23/Th17 axis plays an important role in development of chronic HCV infection and antiviral response. IL-23 may enhance the antiviral activity of interferon-based therapy by modulating the expression of Th17 cells-associated molecules in HCV-infected patients.

Association of IL-17A and IL-17F gene polymorphisms with chronic hepatitis B and hepatitis B virus-related liver cirrhosis in a Chinese population: A case-control study

BACKGROUND

Interleukin (IL)-17 has been shown to play an important role in tissue inflammation and in the pathogenesis of immune-related liver damage. Genetic variations in IL-17 gene may be associated with the development of hepatitis B virus (HBV) infection. However, literature is scanty regarding their association.

METHODS

We conducted a case-control study including 433 subjects (171 healthy controls, 130 patients with chronic hepatitis B [CHB]; and 132 patients with HBV-related liver cirrhosis [HBV-LC] to assess the association between IL-17A rs4711998, IL-17A rs2275913 and IL-17F rs763780 polymorphisms and risk of CHB and HBV-LC. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing.

RESULTS

Our results revealed a statistically significant association between IL-17A rs4711998 G allele and increased risk of HBV-LC risk (OR=1.541, 95% CI 1.057-2.246, P=0.025). Subjects carrying the IL-17A rs4711998 AG genotype were 1.75 times more likely to develop HBV-LC (OR=1.757, 95% CI 1.096-2.817, P=0.026). Stratification analysis indicated that IL-17A rs4711998 G allele and AG genotype enhanced the risk of HBV-LC development among men and older age (≥50years) subject groups. In addition, we found that GCT haplotype also might be a risk factor for HBV-LC (OR=2.448, 95% CI 1.137-5.271, P=0.019). Furthermore, no significant association between IL-17A rs2275913 and IL-17F rs763780 polymorphisms and CHB, HBV-LC risk was observed (P>0.05).

CONCLUSION

Our data provide the first evidence that the IL-17A rs4711998 genetic variant may contribute to HBV-LC susceptibility in a Chinese population.

Autoimmunity as a double agent in tumor killing and cancer promotion

Cancer immunotherapy through manipulation of the immune system holds great potential for the treatment of human cancers. However, recent trials targeting the negative immune regulators cytotoxic T-lymphocyte antigen 4, programed death 1 (PD-1), and PD-1 receptor ligand (PD-L1) demonstrated that clinically significant antitumor responses were often associated with the induction of autoimmune toxicity. This finding suggests that the same immune mechanisms that elicit autoimmunity may also contribute to the destruction of tumors. Given the fact that the immunological identity of tumors might be largely an immunoprivileged self, autoimmunity may not represent a wholly undesirable outcome in the context of cancer immunotherapy. Rather, targeted killing of cancer cells and autoimmune damage to healthy tissues may be intricately linked through molecular mechanisms, in particular inflammatory cytokine signaling. On the other hand, since chronic inflammation is a well-recognized condition that promotes tumor development, it appears that autoimmunity can be a "double agent" in mediating either pro-tumor or antitumor effects. This review surveys the tumor-promoting and tumoricidal activities of several prominent cytokines: IFN-γ, TNF-α, TGF-β, IL-17, IL-23, IL-4, and IL-13, produced by three major subsets of T helper cells that interact with innate immune cells. Many of these cytokines exert divergent and seemingly contradictory effects on cancer development in different human and animal models, suggesting a high degree of context dependence in their functions. We hypothesize that these inflammatory cytokines could mediate a feedback loop of autoimmunity, antitumor immunity, and tumorigenesis. Understanding the diverse and paradoxical roles of cytokines from autoimmune responses in the setting of cancer will advance the long-term goal of improving cancer immunotherapy, while minimizing the hazards of immune-mediated tissue damage and the possibility of de novo tumorigenesis, through proper monitoring and preventive measures.

Kinetics of Th17 cytokines during telbivudine therapy in patients with chronic hepatitis B

Th17 cells and the secreting cytokines play an important role in the immune response and inflammation that is induced by hepatitis B virus (HBV). However, it remains not fully elucidated how the antiviral agents affect Th17 cytokines and signal pathway. Telbivudine therapy has been proved to inhibit HBV replication effectively and to improve clinical outcome of chronic hepatitis B (CHB). Thus, in this study, the effect of decrease in viral load and liver dysfunction resulting from telbivudine treatment on Th17 cells and the related cytokines IL-17, IL-22, and IL-23 were analyzed. Peripheral blood mononuclear cells and serum from twenty-four CHB patients were harvested at 0, 12, 24, 36, and 48 weeks after initiation of telbivudine treatment. In parallel to the reduction of HBV DNA and normalization of serum ALT, significant declines in circulating HBV-specific Th17 cells and IL-22 production were found during antiviral therapy. The expression of serum IL-22 and IL-23, but not IL-17 also decreased during therapy. Our findings suggest that antiviral effect of telbivudine may attribute to both direct virus inhibition and regulation of inflammation, which further improve the understanding of pathogenesis of HBV infection and develop antiviral strategy for controlling viral hepatitis.

The role of T helper (TH)17 cells as a double-edged sword in the interplay of infection and autoimmunity with a focus on xenobiotic-induced immunomodulation

Extensive research in recent years suggests that exposure to xenobiotic stimuli plays a critical role in autoimmunity induction and severity and that the resulting response would be exacerbated in individuals with an infection-aroused immune system. In this context, heavy metals constitute a prominent category of xenobiotic substances, known to alter divergent immune cell responses in accidentally and occupationally exposed individuals, thereby increasing the susceptibility to autoimmunity and cancer, especially when accompanied by inflammation-triggered persistent sensitization. This perception is learned from experimental models of infection and epidemiologic studies and clearly underscores the interplay of exposure to such immunomodulatory elements with pre- or postexposure infectious events. Further, the T_H17 cell subset, known to be associated with a growing list of autoimmune manifestations, may be the “superstar” at the interface of xenobiotic exposure and autoimmunity. In this review, the most recently established links to this nomination are short-listed to create a framework to better understand new insights into T_H17's contributions to autoimmunity.

IL-23 protection against Plasmodium berghei infection in mice is partially dependent on IL-17 from macrophages

Although IL-12 is believed to contribute to protective immune responses, the role played by IL-23 (a member of the IL-12 family) in malaria is elusive. Here, we show that IL-23 is produced during infection with Plasmodium berghei NK65. Mice deficient in IL-23 (p19KO) had higher parasitemia and died earlier than wild-type (WT) controls. Interestingly, p19KO mice had lower numbers of IL-17-producing splenic cells than their WT counterparts. Furthermore, mice deficient in IL-17 (17KO) suffered higher parasitemia than the WT controls, indicating that IL-23-mediated protection is dependent on induction of IL-17 during infection. We found that macrophages were responsible for IL-17 production in response to IL-23. We observed a striking reduction in splenic macrophages in the p19KO and 17KO mice, both of which became highly susceptible to infection. Thus, IL-17 appears to be crucial for maintenance of splenic macrophages. Adoptive transfer of macrophages into macrophage-depleted mice confirmed that macrophage-derived IL-17 is required for macrophage accumulation and parasite eradication in the recipient mice. We also found that IL-17 induces CCL2/7, which recruit macrophages. Our findings reveal a novel protective mechanism whereby IL-23, IL-17, and macrophages reduce the severity of infection with blood-stage malaria parasites.

Hepatitis B virus induces IL-23 production in antigen presenting cells and causes liver damage via the IL-23/IL-17 axis

IL-23 regulates myriad processes in the innate and adaptive immune systems, and is a critical mediator of the proinflammatory effects exerted by Th17 cells in many diseases. In this study, we investigated whether and how hepatitis B virus (HBV) causes liver damage directly through the IL-23 signaling pathway. In biopsied liver tissues from HBV-infected patients, expression of both IL-23 and IL-23R was remarkably elevated. In vivo observations also indicated that the main sources of IL-23 were myeloid dendritic cells (mDCs) and macrophages. Analysis of in vitro differentiated immature DCs and macrophages isolated from healthy donors revealed that the HBV surface antigen (HBsAg) efficiently induces IL-23 secretion in a mannose receptor (MR)-dependent manner. Culture with an endosomal acidification inhibitor and the dynamin inhibitor showed that, upon binding to the MR, the HBsAg is taken up by mDCs and macrophages through an endocytosis mechanism. In contrast, although the HBV core antigen (HBcAg) can also stimulate IL-23 secretion from mDCs, the process was MR- and endocytosis-independent. In addition, IL-23 was shown to be indispensible for HBsAg-stimulated differentiation of naïve CD4(+) T cells into Th17 cells, which were determined to be the primary source of IL-17 in HBV-infected livers. The cognate receptor, IL-17R, was found to exist on the hepatic stellate cells and mDCs, both of which might represent the potential target cells of IL-17 in hepatitis B disease. These data provide novel insights into a yet unrecognized mechanism of HBV-induced hepatitis, by which increases in IL-23 expression, through an MR/endocytosis-dependent or -independent manner, produce liver damage through the IL-23/IL-17 axis.

Association of IL-17, IL-21, and IL-23R gene polymorphisms with HBV infection in kidney transplant patients

Inflammatory cytokine gene polymorphisms may influence the hepatic and extrahepatic HBV-related disease in transplant patients. In this study, the association between IL-17, IL-23R, and IL-21 gene polymorphisms with hepatitis B virus (HBV) infection was evaluated in kidney transplant patients. In total, 220 kidney transplant patients were enrolled in this cross-sectional study between years 2007 and 2011. The genomic HBV DNA was identified using an HBV PCR detection Kit according to the manufacturer's instruction. The cytokine gene polymorphisms, including IL-17 197 A/G (rs2275913), IL-21 +1472 G/T (rs2055979), IL-21 5250 C/T (rs4833837), and IL-23R C/A (rs10889677) were evaluated by PCR-RFLP and ARMS-PCR protocols. The serum levels of IL-17 and IL-21 were analyzed in HBV infected and noninfected transplant patients by ELISA methods according to manufacturer's instructions. 70 of 220 (35%) transplant patients experienced acute rejection. HBV DNA was detected in 52 of 220 (23.64%) transplant patients. 16 of 52 (30.8%) HBV-infected kidney transplant patients experienced acute rejection. A significant higher frequency of C allele of IL-23R (rs10889677) polymorphism, a higher frequency of AG heterozygote genotype and A allele of IL-17-G197A (rs2275913) polymorphism, a higher frequency of TT homozygote genotype and T allele of IL-21-G1472T (rs2055979) polymorphism, and a higher frequency of CC homozygote genotype and C allele of IL-21-C5250T (rs4833837) polymorphism were found in HBV-infected kidney transplant patients with acute rejection. Diagnosis of the higher frequency of the IL-17, IL-21, and IL-23R cytokine genotypes and allele polymorphisms in HBV-infected kidney transplant patients who experienced acute rejection, illustrates the importance of Th17-related cytokine genetic patterns. A better evaluation of HBV infection in kidney transplant patients is needed.

Th17 cells and liver diseases

In recent years, it has been demonstrated that T helper cells 17 (Th17) are closely related to the occurrence and development of many kinds of liver diseases such as viral hepatitis, autoimmune liver diseases and fatty liver diseases. Th17 cells are a new CD4⁺ T cell subset, which can interact with Th1, Th2 and Treg cells. There exists complex antagonistic or collaborative relationship among these cells. Understanding the role of Th17 cells in liver diseases will help explore the pathogenesis and treatment of these diseases.

Anti-cancer versus cancer-promoting effects of the interleukin-17-producing T helper cells

Research on T helper 17 (Th17) cells with regard to immunoediting has revealed elusive results. Whereas enhanced Th17 response and related molecules such as interleukin (IL)-17, IL-21, IL-22, IL-23 and STAT3 accompanied tumor induction and progression, finding that tumor growth/stage was negatively correlated with increased infiltration of Th17 cells in the tumor mass has prompted elucidation of various antitumor mechanisms elicited by Th17 and their related molecules. The pro-tumor efficacy of Th17 response included promotion of neutrophilia and induction of angiogenic (e.g. VEGF, MMP2 and MMP9) and anti-apoptotic factors (e.g. Bcl-XL), as well as expansion and activation of myeloid-derived suppressor cells, which facilitate generation of tumor-specific regulatory T cells. Other tumor immunogenic settings revealed anti-tumor pathways including induction of cytotoxic activity, expression of MHC antigens, the ability Th17 cells to reside within the tumor, and to convert into IFN-γ producers. Notably, Th17 cell related molecules exert indirect pro- or anti-tumor effects via inducing viral persistence or mediating protective mechanisms against bacterial and viral infection. Herein, the recent literature revealing such immunoediting events mediated by Th17 cells and their associated molecules as delivered by various experimental regimens and observed in cancer patient are revised, with a focus on some proposed anti-cancer therapies.