High Serum Levels of TGF-β in Iranians With Chronic HBV Infection

Bidirectional Relationship between HIV/HBV Infection and Comorbid Depression and/or Anxiety: A Systematic Review on Shared Biological Mechanisms

BACKGROUND

Mental disorders that are comorbid with chronic infectious diseases may worsen clinical outcomes and patients' quality of life. We hypothesized that depression and/or anxiety syndromes or symptoms comorbid with human immunodeficiency virus (HIV) or hepatitis B virus (HBV) infection might stem from shared biological mechanisms.

METHODS

We conducted a systematic review applying the PRISMA statement by searching into the PubMed, APA PsycInfo, and Scopus databases. We examined the literature on HIV/HBV infection comorbid with depression and/or anxiety in adults ≥18 years.

RESULTS

Thirty-one studies on HIV and three on HBV were analyzed. The Tat protein contributed to HIV-associated mood disorders due to the protein's ability to cause neurodegeneration and induce hypothalamic-pituitary-adrenal (HPA) axis dysregulation in response to natural stressors. The decreased brain-derived neurotrophic factor (BDNF) levels also emerged as a mechanism involved in HIV neuropathogenesis and the associated mood symptoms. Neuroinflammation was implicated in depression and/or anxiety onset in patients with HIV/HBV infections. Microglial activation and release of cytokines, in particular, appeared as potential pathogenetic mechanisms. Furthermore, an altered balance between quinolinic acid and kynurenic acid production emerged in HIV patients with comorbid depression, indicating a glutamatergic dysfunction. Inflammatory cytokine production and the downregulation of cellular immune responses contributed to persisting inflammation, delayed healing, and functional decline in patients with chronic hepatitis B (CHB) infection. A shift in type 1-type 2 cytokine balance might be implicated in HBV-related immune pathogenesis, and depression and anxiety might be considered immunomodulatory factors. Cytokines also caused HPA axis hyperactivity, frequently observed in HIV/HBV patients with comorbid depression/anxiety.

CONCLUSIONS

The present systematic review showed, for the first time, that HIV/HBV and depression and/or anxiety might have several biological mechanisms as common denominators. The longitudinal course of the highlighted biological mechanisms should be explored to establish the causative interrelationship among the involved mechanisms. In addition, future research should investigate the possibility that a patient's clinical outcome might improve using pharmacological treatments acting on the biological mechanisms we described as common denominators of chronic inflammatory infective diseases and depression/anxiety.

The potential role of HLA-G in the pathogenesis of HBV infection: Immunosuppressive or immunoprotective?

The non-classical human leukocyte antigens (HLA)-G could be generally considered as a potent tolerogenic molecule, which modulates immune responses. HLA-G due to the immunosuppressive properties may play an important role in the pathogenesis of infections related to the liver. HLA-G may display two distinct activities in the pathological conditions so that it could be protective in the autoimmune and inflammatory diseases or could be suppressive of the immune system in the infections or cancers. HLA-G might be used as a novel therapeutic target for liver diseases in the future. Indeed, new therapeutic agents targeting HLA-G expression or antibodies which block HLA-G activity are being developed and tested. However, further consideration of the HLA-G function in liver disease is required. This review aims to summarize the role of HLA-G in the liver of patients with HBV infection.

Hepatitis B envelope antigen increases Tregs by converting CD4+CD25- T cells into CD4+CD25+Foxp3+ Tregs

Hepatitis B virus (HBV) can establish a lifelong chronic infection in humans, leading to liver cirrhosis, liver failure and hepatocellular carcinoma. Patients with chronic hepatitis B (CHB) exhibit a weak virus-specific immune response. Regulatory T cells (Tregs) play a key role in regulating the immune response in patients with CHB. Patients with hepatitis B envelope antigen (HBeAg)-positive CHB harbored a higher percentage of Tregs in their peripheral blood than those with HBeAg-negative CHB. However, whether and how HBeAg manipulates the host immune system to increase the population of Tregs remains to be elucidated. The present manuscript describes a preliminary immunological study of HBeAg in a mouse model. Multiple potential CD4⁺ T cell epitopes in HBeAg were identified using Immune Epitope Database consensus binding prediction. It was demonstrated that HBeAg treatment increased the numbers of Tregs in mouse spleens in vitro and in vivo. Furthermore, it was indicated that the HBeAg-mediated increase in Tregs occurred through the conversion of CD4⁺CD25^- T cells into CD4⁺CD25⁺Foxp3⁺ Tregs. Additionally, in vitro study illustrated that HBeAg stimulated murine spleen cells to produce increased transforming growth factor-β, which is required to enable HBeAg to convert T cells into Tregs. The results of the present study may provide further evidence of the effect of HBeAg on Tregs and aid in the development of novel HBeAg-based immunotherapy for CHB.

The Binary Classification Of Chronic Diseases

Acute diseases start with an insult and end when insult disappears. If the trauma induces an immune reaction (which happens in most cases), this reaction must be terminated with some type of resolution mechanism, when the cause of the trauma ceases. Chronicity develops if insult is permanent or if the resolution mechanism is defective. Another way to reach disease chronicity is a positive feedback loop, whereby the immune reaction activates an internal, insult-like reaction. A distinction between chronic states characterized by a persistent, low suppressive effect and those characterized by a persistent, high suppressive effect of regulatory T cells (Treg), is proposed. This two-class division represents two ways to reach chronicity: (a) by maintaining inflammatory reaction long after insult disappears (“low Treg”), or (b) by suppressing inflammatory reaction prior to the disappearance of insult (“high Treg”). This two-class division may explain the strong association between certain pathogens and cancer, on one hand, and between several other pathogens and autoimmunity, on the other hand. The weak association between autoimmune diseases and HIV infection and the relatively weak association between autoimmune diseases and cancer may be elucidated as well. In addition, the model rationalizes why immune-modulating drugs, which are effective in cancer, are also effective in “high Treg” viral infections, while corticosteroids, which are generally effective in autoimmune diseases, are also effective in other “low Treg” diseases (such as asthma, atopic dermatitis, and “low Treg” infections) but are not effective in solid malignancies and “high Treg” infections. Moreover, the model expounds why certain bacteria inhibit tumor growth and why these very bacteria induce autoimmune diseases.

Serum Levels of IL-6, IL-8, TNF-α, and TGF-β in Chronic HBV-Infected Patients: Effect of Depression and Anxiety

Objective

To assess the effects of depression and anxiety on serum cytokine levels in patients with chronic hepatitis B (CHB) infection.

Methods

In this cross-sectional study, 60 healthy control individuals and 60 patients with CHB participated after filling out standard questionnaires. We examined their serum interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, and TGF-β levels using enzyme-linked immunosorbent assay (ELISA) techniques.

Results

In patients with CHB compared with healthy controls, serum levels of IL-8 were significantly increased, whereas IL-6 and TGF-β levels were significantly decreased. Serum levels of TGF-β were significantly decreased in the patients with CHB who had mild depression, compared with patients with CHB without depression and with moderate and severe depression.

Conclusions

Downregulation of IL-8 and TGF-β, respectively, is a corresponding mechanism for induction of chronic inflammation in patients with CHB. Depression also seems to induce inflammation via downregulation of TGF-β in these patients.

Regulation of the Immune Response by TGF-β: From Conception to Autoimmunity and Infection

Transforming growth factor β (TGF-β) is a pleiotropic cytokine involved in both suppressive and inflammatory immune responses. After 30 years of intense study, we have only begun to elucidate how TGF-β alters immunity under various conditions. Under steady-state conditions, TGF-β regulates thymic T-cell selection and maintains homeostasis of the naïve T-cell pool. TGF-β inhibits cytotoxic T lymphocyte (CTL), Th1-, and Th2-cell differentiation while promoting peripheral (p)Treg-, Th17-, Th9-, and Tfh-cell generation, and T-cell tissue residence in response to immune challenges. Similarly, TGF-β controls the proliferation, survival, activation, and differentiation of B cells, as well as the development and functions of innate cells, including natural killer (NK) cells, macrophages, dendritic cells, and granulocytes. Collectively, TGF-β plays a pivotal role in maintaining peripheral tolerance against self- and innocuous antigens, such as food, commensal bacteria, and fetal alloantigens, and in controlling immune responses to pathogens.

Association of mRNA expression of toll-like receptor 2 and 3 with hepatitis B viral load in chronic hepatitis, cirrhosis, and hepatocellular carcinoma

During Hepatitis B virus infection, the pathogen sensors Toll-like receptors (TLRs) play a role in innate immunity system. The study aimed to investigate mRNA expression levels of TLR2 and TLR3 in Hepatitis B virus (HBV) mediated chronic hepatitis B (CHB), cirrhosis (CIRR), and hepatocellular carcinoma (HCC), and to correlate viral load with severity of these diseases and expression of TLRs. A total of 180 HBV DNA positive samples were selected for the study. HVB-DNA was detected by multiplex PCR. Viral load estimation was done by using the Ampisure HBV Quantitative kit as per manufacture instructions. Expression levels of TLR2 and TLR3 were determined by real time PCR. The viral load was estimated to be 6.64log₁₀ IU/ml in CHB, 4.88log₁₀ IU/ml in CIRR, and 4.86log₁₀ IU/ml in HCC. No significant association of viral load was found with increasing age. Upregulation of TLR2 expression in CHB when individually compared with CIRR and HCC was found to be statistically significant. Downregulation of TLR3 expressions in CIRR when compared to both CHB and HCC individually were found to be statistically significant. No significant effect of viral load on the expression of TLR2 and 3 were found. With severity of the disease from CHB to HCC, the HBV load decreases. The study suggests the possibility of HBV interacting with signalling of both analysed TLR receptors which partially explains the induction of immune tolerance pathways by Hepatitis B virus. J. Med. Virol. 89:1008-1014, 2017. © 2017 Wiley Periodicals, Inc.

The link between TLR7 signaling and hepatitis B virus infection

Toll-Like Receptors (TLRs) play crucial roles in recognition and induction of appropriate immune responses against viral infections, including hepatitis B. TLR7 detects intracellular viral single strand RNA which leads to the activation of several pro-inflammatory transcription factors via the MYD88 dependent pathway. Patients with prolonged infectious forms of hepatitis B, including active and inactive chronic forms, are unable to clear HBV from hepatocytes completely. It is believed that the differences in genetic and immunological parameters of the patients and clearance subjects, who successfully clear HBV infections, are the main factors responsible for allowing the long term infections to persist. It appears that defective expression of TLR7 may result in impaired immune responses against HBV. The aim of this review is to address the recent information regarding the crucial roles played by TLR7 in hepatitis B infection and also the main mechanisms used by HBV to escape from recognition by TLR7 in prolonged HBV infected patients. Considering that chronic hepatitis B infection is not yet curable, it could be possible to activate TLR7-related immunological pathways as a therapy directed towards persistent HBV infection. Hence, another aim of this study is to present recent developments of TLR7 agonists as a therapeutic strategy for chronic hepatitis B.

Increased CD86 but Not CD80 and PD-L1 Expression on Liver CD68+ Cells during Chronic HBV Infection

BACKGROUND

The failure to establish potent anti-HBV T cell responses suggests the absence of an effective innate immune activation. Kupffer cells and liver-infiltrating monocytes/macrophages have an essential role in establishing anti-HBV responses. These cells express the costimulatory molecules CD80 and CD86. CD80 expression on antigen-presenting cells (APCs) induces Th1 cell differentiation, whereas CD86 expression drives the differentiation towards a Th2 profile. The relative expression of CD80, CD86 and PD-L1 on APCs, regulates T cell activation. Few studies investigated CD80 and CD86 expression on KCs and infiltrating monocytes/macrophages in HBV-infected liver and knowledge about the expression of PD-L1 on these cells is controversial. The expression of these molecules together in CD68+ cells has not been explored in HBV-infected livers.

METHODS

Double staining immunohistochemistry was applied to liver biopsies of HBV-infected and control donors to explore CD80, CD86 and PD-L1 expression in the lobular and portal areas.

RESULTS

Chronic HBV infection was associated with increased CD68+CD86+ cell count and percentage in the lobular areas, and no changes in the count and percentage of CD68+CD80+ and CD68+PD-L1+ cells, compared to the control group. While CD68+CD80+ cell count in portal areas correlated with the fibrosis score, CD68+CD80+ cell percentage in lobular areas correlated with the inflammation grade.

CONCLUSION

The upregulation of CD86 but not CD80 and PD-L1 on CD68+ cells in HBV-infected livers, suggests that these cells do not support the induction of potent Th1. Moreover, the expression of CD80 on CD68+ cells correlates with liver inflammation and fibrosis.

Manipulation of Regulatory Cells' Responses to Treatments for Chronic Hepatitis B Virus Infection

BACKGROUND

Identification of effective treatments in hepatitis B virus (HBV) infection remains a controversial topic. Although the currently approved drugs for HBV control the disease's progression and also limit associated outcomes, these drugs may not fully eradicate HBV infection. In addition to better managing patients with chronic hepatitis B (CHB) infection, the induction of seroclearance by these drugs has been a commonly discussed topic in recent years.

OBJECTIVES

In this study, we focused on treating CHB infection via the manipulation of T cells' responses to identify possible approaches to cure CHB.

MATERIALS AND METHODS

All studies relevant to the role of cellular and humoral responses in HBV infection (especially regulatory cells) were investigated via a systematic search of different databases, including PubMed, Scopus, and Google Scholar. Considering extracted data and also our unpublished data regarding the association between regulatory cytokines and CHB, we introduced a novel approach for the induction of seroclearance.

RESULTS

Considering the increased levels of regulatory cytokines and also regulatory T cells (Tregs) during CHB, it seems that these cells are deeply involved in CHB infection. The inhibition of regulatory T cells may reverse the dysfunction of effector T cells in patients with CHB infection. In order to inhibit Tregs' responses, different types of approaches could be employed to restore the impaired function of effector T cells. The blockade of IL-10, IL-35, CTLA-4, PD-1, and TIM-3 were discussed throughout this study. Regardless of the efficacy of these methods, CHB patients may experience serious liver injuries due to the cytotoxic action of CD8+ T cells. Antiviral therapy and a decrease in HBV DNA to undetectable levels could also significantly reduce the risk of the hepatitis B flare.

CONCLUSIONS

The inhibition of Tregs is a novel therapeutic approach to cure chronically HBV infected patients. However, further studies are needed to investigate the safety and efficacy of this approach.

Immune-mediated Liver Injury in Hepatitis B Virus Infection

Hepatitis B virus (HBV) is responsible for approximately 350 million chronic infections worldwide and is a leading cause of broad-spectrum liver diseases such as hepatitis, cirrhosis and liver cancer. Although it has been well established that adaptive immunity plays a critical role in viral clearance, the pathogenetic mechanisms that cause liver damage during acute and chronic HBV infection remain largely known. This review describes our current knowledge of the immune-mediated pathogenesis of HBV infection and the role of immune cells in the liver injury during hepatitis B.

Association of cord blood levels of IL-17A, but not TGF-β with pre-term neonate

BACKGROUND

It has been documented that cytokines play important roles in the induction of normal functions of the placenta. It has been hypothesized that abnormal expression of the cytokines may be associated with unsuccessful pregnancy.

OBJECTIVE

The aim of this study was to compare the serum levels of interleukin-17A (IL-17A) and tumor growth factor (TGF-β) in pre-term, term neonates, and their corresponding mothers.

MATERIALS AND METHODS

This study was performed on 100 term and 60 pre-term neonates, and also on their corresponded mothers. Serum levels of IL-17A and TGF-β were examined by enzyme linked immunosorbent assay (ELISA).

RESULTS

Our results revealed that the serum levels of IL-17A were significantly decreased in pre-term neonates in comparison to full-term neonates. However, the serum levels of IL-17A in the mothers either with pre-term or full-term neonates were not different. Also the serum levels of TGF-β were not changed in pre-term neonates and their mothers when compared with full-term neonates and their mothers, respectively.

CONCLUSION

Based on these findings, it can be concluded that IL-17A may play crucial roles in induction of normal pregnancies and also probably participates in normal growth of fetus.

TLR9: an important molecule in the fight against hepatitis B virus

Hepatitis B virus (HBV) is the most prevalent infectious agent that can induce severe liver disease. Patients infected with long-term HBV, including chronic, asymptomatic and occult forms, cannot clear HBV from infected hepatocytes completely. It is not clear why some people can clear the infection while others cannot. Furthermore, the main mechanisms responsible for progression of the infections are not fully understood. It has been hypothesised that differences in genetic and immunological parameters between patients and subjects who successfully clear HBV infections are responsible for inducing the long-term forms of the infection. Previous investigations showed that Toll-like receptors (TLRs) play important roles in immune responses, especially innate immunity, against viral infections, including hepatitis B. TLR9 detects intracellular viral dsDNA, which results in the activation of an immune response against HBV. However, defects in this system may result in an attenuated response ultimately leading to long-term HBV infections. Targeting the defects in TLR9 or reactivating the downstream pathways that are normally switched on by TLR9 in response to HBV infection is a new approach to the treatment of long-term HBV infection. However, the pathways and defects seen in patients with long-term HBV need to be thoroughly explored before therapeutics can be applied in the clinical setting. Furthermore, the apparently multigenic nature of long-term HBV infection suggests that treatment of patients may need to be personalised.

Toll-like receptor 4 and hepatitis B infection: molecular mechanisms and pathogenesis

Hepatitis B virus (HBV) infection mainly causes liver disease, including inflammation, cirrhosis, and hepatocellular carcinoma (HCC). It has been documented that prolonged hepatitis B-infected patients are unable to clear HBV from hepatocytes completely. Previous investigations have suggested that various genetic and immunologic parameters may be responsible for the induction of prolonged infection forms. Toll-like receptors (TLRs), as members of pathogen recognition receptors (PRRs), play critical roles in the recognition of viruses and the induction of appropriate immune responses. Thus, TLRs may be considered as essential sensors for the recognition of HBV and the induction of immune responses against this virus. It has been documented that TLR4 plays key roles in the detection of several microbial pathogen-associated molecular pattern molecules, including bacterial lipopolysaccharide (LPS), as well as endogenous ligands (damage-associated molecular pattern molecules) and subsequently activates pro-inflammatory transcription factors in either MYD88 or TRIF dependent pathways. Previous investigations have proposed that TLR4 might be involved in appropriate immune responses against HBV. Therefore, the aim of this review is to present the recent data regarding the important roles of TLR4 in HBV recognition and regulation of immune responses against this virus, and also its roles in the pathogenesis of cirrhosis and HCC as complications of prolonged hepatitis B infections.

Lack of Association Between Transforming Growth Factor Beta 1 -509C/T and +915G/C Polymorphisms and Chronic Hepatitis B in Iranian Patients

BACKGROUND

Chronic hepatitis B is one of the world's major health concerns [corrected]. The etiological agent of this infection is hepatitis B virus (HBV), which can evade the immune system response. Transforming growth factor beta 1 (TGF-β1) can act against HBV by suppressing the viral replication. The TGF-β1 also plays an important role in preventing liver damage in chronically HBV infected patients.

OBJECTIVES

In this study, the association of TGF-β1 +915G/C and -509C/T gene polymorphisms with chronic hepatitis B was evaluated in Iranian patients.

MATERIALS AND METHODS

A population-based case-control study was conducted in Taleghani Hospital, Tehran. A number of 220 patients with chronic hepatitis B and the same number of healthy control subjects were designated the case and the control groups. The PCR-Restriction Fragment Length Polymorphism Method (PCR-RFLP) method was used for genotyping both polymorphisms. Ten percent of the control samples were sequenced to confirm the results.

RESULTS

No statically significant differences in genotype distribution and allele frequency were observed for both polymorphisms between healthy controls and patients with chronic hepatitis B.

CONCLUSIONS

There was no association between TGF-β1 -509C/T and +915G/C polymorphisms with chronic hepatitis B and it seems that these changes do not play a significant role in increasing the risk of chronic infection in Iranian patients [corrected].

Can Toll-Like Receptor (TLR) 2 be considered as a new target for immunotherapy against hepatitis B infection?

The current literature describes pivotal mechanisms in which hepatitis B virus (HBV) induces liver diseases including inflammation, cirrhosis and hepatocellular carcinoma (HCC). It appears that differences in genetic and immunological parameters between patients and controls may be responsible for inducing the prolonged forms of the infection. Previous studies demonstrated that Toll-Like Receptors (TLRs) play key roles in viral recognition and inducing appropriate immune responses. Therefore, TLRs can be considered as key sensors for HBV recognition and subsequent induction of immune responses against this virus. It has also been shown that the TLR2 detects several microbial PAMPs either in its homodimer form or in a heterodimer with TLR1 or TLR6 and subsequently activates NF-κB in a MYD88 dependent manner. Therefore, defective TLR2 expression may result in impaired immune responses against HBV which is reported in long-term forms of hepatitis B. This review presents the recent data regarding the status and important roles played by TLR2 in HBV recognition and induction or suppression of immune responses against HBV as well as its roles in the pathogenesis of cirrhosis and HCC in prolonged hepatitis B forms.

NK cells in hepatitis B virus infection: a potent target for immunotherapy

Viruses, including hepatitis B virus (HBV), are the most prevalent and infectious agents that lead to liver disease in humans. Hepatocellular carcinoma (HCC) and cirrhosis of the liver are the most serious complications arising from prolonged forms of hepatitis B. Previous studies demonstrated that patients suffering from long-term HBV infections are unable to eradicate HBV from hepatocytes completely. The mechanisms responsible for progression of these forms of infection have not yet been clarified. However, it seems that there are differences in genetic and immunological parameters when comparing patients to subjects who successfully clear HBV infections, and these may represent the causes of long-term infection. Natural killer (NK) cells, the main innate immune cells that target viral infections, play important roles in the eradication of HBV from hepatocytes. NK cells carry several stimulatory and inhibitor receptors, and binding of receptors with their ligands results in activation and suppression of NK cells, respectively. The aim of this review is to address the recent information regarding NK cell phenotype, functions and modifications in hepatitis B. This review addresses the recent data regarding the roles of NK cells as novel targets for immunotherapies that target hepatitis B infection. It also discusses the potential to reduce the risk of HCC or cirrhosis of the liver by targeting NK cells.