Immunological changes in different patient populations with chronic hepatitis C virus infection

New insights into iNKT cells and their roles in liver diseases

Natural killer T cells (NKTs) are an important part of the immune system. Since their discovery in the 1990s, researchers have gained deeper insights into the physiology and functions of these cells in many liver diseases. NKT cells are divided into two subsets, type I and type II. Type I NKT cells are also named iNKT cells as they express a semi-invariant T cell-receptor (TCR) α chain. As part of the innate immune system, hepatic iNKT cells interact with hepatocytes, macrophages (Kupffer cells), T cells, and dendritic cells through direct cell-to-cell contact and cytokine secretion, bridging the innate and adaptive immune systems. A better understanding of hepatic iNKT cells is necessary for finding new methods of treating liver disease including autoimmune liver diseases, alcoholic liver diseases (ALDs), non-alcoholic fatty liver diseases (NAFLDs), and liver tumors. Here we summarize how iNKT cells are activated, how they interact with other cells, and how they function in the presence of liver disease.

Natural Killer Group 2D Receptor and B1a Cells Crosstalk in Post-Hepatitis C Virus Infection Hepatocellular Carcinoma and Cirrhosis

Background

Natural killer (NK) and B1a cells are implicated in innate immune surveillance against chronic hepatitis C virus (CHCV). NK group 2D (NKG2D) receptor is important for B cell differentiation. This study was designed to assess whether B1a cells and NK Cells expressing NKG2D are implicated in post-hepatitis C infection hepatocellular carcinoma (post-HCV HCC) and cirrhosis using flow cytometry and investigate the association between NK-expressing NKG2D and B1a in complications of CHCV infection.

Methods

In this cross-sectional study, 111 participants were included and divided into the post-HCV HCC (n = 50), post-HCV liver cirrhosis (n = 31), and CHCV (n = 30) groups.

Results

The percentage of B1a cells (B1a%) and the mean fluorescence intensity (MFI) of NKG2D (NKG2D MFI) showed a significant increase in the CHCV group compared with those in the post-HCV liver cirrhosis and post-HCV HCC groups (P < 0.05). A positive correlation was observed between NKG2D MFI and B1a% (r = 0.6, P < 0.001). The receiver operating characteristic (ROC) curve revealed that NKG2D MFI and B1a% differentiated between patients with CHCV infection and those with HCC with a sensitivity of 92% and 98%, respectively, and differentiated between patients with CHCV infection and those with liver cirrhosis with a sensitivity of 94% and 90%, respectively.

Conclusion

Downregulation of B1a frequency and NKG2D intensity is implicated in the progression of CHCV infection to cirrhosis and HCC. NKG2D receptor is associated with the frequency of circulating B1a cells. NKG2D intensity and B1a% can be used as indicators of CHCV progression.

Correlation between gut microbiota diversity and psychogenic erectile dysfunction

Background

To analyze the distribution of gut microbiota in erectile dysfunction (ED) patients and explore the relationship between the diversity of gut microbiota and psychogenic ED.

Methods

Stool specimen were collected from 30 patients with ED and 30 healthy persons (healthy donors, HDs) and analyzed Paired end (PE) 300 sequencing on V3-V4 region sequences of bacterial 16S rRNA gene by using Illumina's Miseq platform, whereby sequencing results were analyzed to assess differences in species composition and diversity. The analysis comprised five modules: sequencing data quality control, operational taxonomic units (OTU) species clustering and annotation, alpha diversity, beta diversity and the use of t-tests and analysis of linear discriminant analysis effect size (LEfSe) differences.

Results

The International Index of Erectile Function (IIEF-5) score ranged between 8 and 21. The scores of ED patients were ≥11 and ≤20, and the mean value was 15.67±2.94. The flora diversity in the group of ED patients was significantly different from that of HDs (P<0.01), with the ED group having low bacterial diversity. There were no significant differences in the genus level between the ED and HD group, and abundant bacteria (TOP10) and core flora (90%). Comparison of total flora (the abundance >1%) display, Alloprevotella genera showed differences, whereby Alloprevotella was only be identified in the HD group. Erectile dysfunction and HD showed good separation and clustering respectively in principal component analysis, showing significant differences in two kinds of microflora. T-tests showed that six species were significantly different, and that in the ED group, streptococci and Subdoligranulum were significantly increasing, and Prevotella sp.9, Blautia, Lachnospiraceae NK4A136 groups and Roseburia were significantly lower. Analysis using LEfSe analysis revealed 24 species were significantly different between ED and HD groups.

Conclusions

When gene sequencing was performed of ED and HD specimens, the microbial community structure and diversity showed significant differences, suggesting that ED specimen had lower gut microbiota diversity.

Gender as a factor affecting NK cell activity in patients successfully treated for chronic hepatitis C with direct-acting antivirals

Chronic hepatitis C (CHC) affects the activity of natural killer (NK) cells, but successful interferon- free treatment partially restores it. The goal of this study was to assess whether gender influences NK functionality. We examined 21 post-menopausal women and 24 men with CHC who were treated with direct-acting antivirals (DAA) and 33 healthy volunteers. Using flow cytometry, we analysed KIR2DS4, NKG2D, NKp30, KIR2DL2/DL3, NKG2A and TRAIL on the surface of NK cells. Intracellular granzyme B was also assessed and serum CXCL10 was quantified via ELISA. Overall, patients with CHC had higher expression of KIR2DS4, NKG2A, and NKp30 relative to the control group. Further, CHC patients had a lower percentage of NK cells among lymphocytes relative to the control group. After treatment, KIR2DS4, KIR2DL2/DL, NKG2A, TRAIL and NKp30 on NK cells were decreased whilst the percentage of NK cells and the expression of granzyme B and NKG2D increased. Prior to treatment, serum CXCL10 was elevated, but it was inhibited post-treatment. We observed gender-specific differences in the expression of KIR2DL2/DL3 (higher in women) and NKp30 (elevated in men) compared to CHC/control groups. After treatment, KIR2DL2/DL3, NKp30 and CXCL10 dropped only in the female group while granzyme B increased in the male group. In conclusion, the response of NK cells among men and women of post-menopausal ages with CHC differs. Our research may lead to more studies on the different nature of female and male immune systems in the context of HCV infection and treatment.

Toll-like receptors and hepatitis C virus infection

BACKGROUND

Hepatitis C virus (HCV) infection is a worldwide issue. However, the current treatment for hepatitis C has many shortcomings. Toll-like receptors (TLRs) are pattern recognition receptors involved in HCV infection, and an increasing number of studies are focusing on the role of TLRs in the progression of hepatitis C.

DATA SOURCES

We performed a PubMed search up to January 2021 with the following keywords: hepatitis C, toll-like receptors, interferons, inflammation, and immune evasion. We also used terms such as single-nucleotide polymorphisms (SNPs), susceptibility, fibrosis, cirrhosis, direct-acting antiviral agents, agonists, and antagonists to supplement the query results. We reviewed relevant publications analyzing the correlation between hepatitis C and TLRs and the role of TLRs in HCV infection.

RESULTS

TLRs 1-4 and 6-9 are involved in the process of HCV infection. When the host is exposed to the HCV, TLRs, as important participants in HCV immune evasion, trigger innate immunity to remove the virus and also promote inflammation and liver fibrosis. TLR gene SNPs affect hepatitis C susceptibility, treatment, and prognosis. The contribution of each TLR to HCV is different. Drugs targeting various TLRs are developed and validated, and TLRs can synergize with classic hepatitis C drugs, including interferon and direct-acting antiviral agents, constituting a new direction for the treatment of hepatitis C.

CONCLUSIONS

TLRs are important receptors in HCV infection. Different TLRs induce different mechanisms of virus clearance and inflammatory response. Although TLR-related antiviral therapy strategies exist, more studies are needed to explore the clinical application of TLR-related drugs.

The risk of subclinical carotid atherosclerosis in patients with chronic hepatitis C

INTRODUCTION

The role of hepatitis C virus in the pathogenesis of atherosclerotic disease has been suggested by several studies.

AIM

To assess the association between subclinical carotid atherosclerosis and chronic hepatitis C.

METHODS

40 patients infected with chronic hepatitis C and 40 control cases were evaluated by anthropometric and metabolic measurements. The risk of subclinical atherosclerosis was assessed by ultrasound measurement of carotid intima-media thickness. A high cardiovascular risk atherosclerosis was defined by carotid intima-media thickness > 75th percentile.

RESULTS

The carotid intima-media thickness and the prevalence of high cardiovascular risk atherosclerosis were significantly higher in the group infected with hepatitis C compared to the control group (0.68 VS 0.60, p=0.02) and (82.5% vs. 40%; 0.001) respectively. In multivariate studies, activity ≥ A2 and age> 40 years were the independent factors associated with the carotid intima-media thickness and hepatitis C was the only independent factor associated with high cardiovascular risk atherosclerosis (OR=4.81 CI at 95%: 1.6-14.42).

CONCLUSIONS

In our study, chronic hepatitis C was associated with a high risk of carotid atherosclerosis.

Immunomodulation of the Natural Killer Cell Phenotype and Response during HCV Infection

Hepatitis C virus (HCV) infection develops into chronic hepatitis in over two-thirds of acute infections. While current treatments with direct-acting antivirals (DAAs) achieve HCV eradication in >95% of cases, no vaccine is available and re-infection can readily occur. Natural killer (NK) cells represent a key cellular component of the innate immune system, participating in early defence against infectious diseases, viruses, and cancers. When acute infection becomes chronic, however, NK cell function is altered. This has been well studied in the context of HCV, where changes in frequency and distribution of NK cell populations have been reported. While activating receptors are downregulated on NK cells in both acute and chronic infection, NK cell inhibiting receptors are upregulated in chronic HCV infection, leading to altered NK cell responsiveness. Furthermore, chronic activation of NK cells following HCV infection contributes to liver inflammation and disease progression through enhanced cytotoxicity. Consequently, the NK immune response is a double-edged sword that is a significant component of the innate immune antiviral response, but persistent activation can drive tissue damage during chronic infection. This review will summarise the role of NK cells in HCV infection, and the changes that occur during HCV therapy.

Clinical, Virological Characteristics, and Outcomes of Treatment with Sofosbuvir/Ledipasvir in Two Pediatric Patients Infected by HCV Genotype 4

Direct-acting antiviral drugs to cure infections with Hepatitis C virus (HCV) achieve a sustained virological response (SVR) in more than 90% of adult patients. At present, clinical trials are ongoing and real-life data are still limited in children. Herein, we report two cases of pediatric patients treated with fixed-dose combination of sofosbuvir/ledipasvir, already approved to treat HCV4 genotype. Both young girls achieved SVR even though HCV4 isolates carried L28M and M31L NS5A resistance-associated substitutions (RASs). Therefore, possible effects of these RASs merit further study, especially in children.

Prediction of recurrence following hepatectomy in patients with hepatitis C virus infection-related hepatocellular carcinoma who achieved a sustained virological response

AIM

The risk of hepatitis C virus infection-related hepatocellular carcinoma (HCC) is lower, with a better prognosis, in patients who achieve a sustained virological response (SVR) than in those who do not. We aimed to identify risk factors of post-hepatectomy HCC recurrence in patients who achieved a SVR.

METHODS

This retrospective study included 349 HCC patients who underwent an initial radical hepatectomy at our institution between January 2005 and December 2014. Sixty-eight patients had achieved a SVR (the SVR group) and 281 patients had not (the non-SVR group). Clinical characteristics and long-term outcomes were compared between the two groups. Univariate and multivariate analyses identified variables associated with recurrence-free survival in the SVR group.

RESULTS

Post-hepatectomy overall and recurrence-free survival rates were significantly higher in the SVR group than the non-SVR group (P < 0.01 and <0.05, respectively). Univariate analysis of post-hepatectomy recurrence-free survival in the SVR group revealed multiple significant factors: aspartate aminotransferase, 25 IU/L or more (P = 0.01); indocyanine green retention rate at 15 min, 20.0% or less (P < 0.05); hepatic vascular invasion (P < 0.05); and an interval of months or less between achieving a SVR and hepatectomy (P < 0.01). Multivariate analysis confirmed an interval of 30 months or less between achieving a SVR and hepatectomy as an independent prognostic factor of recurrence-free survival (hazard ratio, 2.30; 95.0% confidence interval, 1.04-5.13; P < 0.05).

CONCLUSION

The interval between achieving a SVR and hepatectomy is an important predictor of recurrence in hepatitis C virus infection-related HCC patients who achieved a SVR.

Increased incidence of cytomegalovirus coinfection in HCV-infected patients with late liver fibrosis is associated with dysregulation of JAK-STAT pathway

Herein, we examined the association between cytomegalovirus (CMV) coinfection and the progression of liver fibrosis in hepatitis C virus (HCV) infection, and investigated the effect of CMV coinfection on JAK-STAT pathway. CMV DNAemia was detected by PCR in DNA from controls (n = 120), and HCV patients with early (F0-F1, n = 131) and late (F2-F4, n = 179) liver fibrosis. By quantitative real time PCR (qRT-PCR), we examined the profile of 8 JAK-STAT transcripts in PBMCs RNA from 90 HCV patients (39 CMV positive and 51 CMV negative), 4 CMV mono-infected patients, and 15 controls. Our results demonstrated higher incidence of CMV in F2-F4 group than in control (OR 5.479, 95% CI 3.033-9.895, p < 0.0001) or F0-F1 groups (OR 2, 95% CI 1.238-3.181, p = 0.005). qRT-PCR showed downregulation of STAT2 (p = 0.006) and IRF7 (p = 0.02) in CMV positive group compared to CMV negative one. The downregulation of STAT2 and IRF7 was mainly in CMV positive patients with late fibrosis compared to CMV negative patients (p = 0.0007 for IRF7 and p = 0.01 for STAT2). Our results are the first to report that CMV coinfection is a possible risk factor for the progression of HCV-induced liver fibrosis, and thereby CMV screening and treatment are important for HCV patients.

Cytomegalovirus-Driven Adaptive-Like Natural Killer Cell Expansions Are Unaffected by Concurrent Chronic Hepatitis Virus Infections

Adaptive-like expansions of natural killer (NK) cell subsets are known to occur in response to human cytomegalovirus (CMV) infection. These expansions are typically made up of NKG2C⁺ NK cells with particular killer-cell immunoglobulin-like receptor (KIR) expression patterns. Such NK cell expansion patterns are also seen in patients with viral hepatitis infection. Yet, it is not known if the viral hepatitis infection promotes the appearance of such expansions or if effects are solely attributed to underlying CMV infection. In sizeable cohorts of CMV seropositive hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis delta virus (HDV) infected patients, we analyzed NK cells for expression of NKG2A, NKG2C, CD57, and inhibitory KIRs to assess the appearance of NK cell expansions characteristic of what has been seen in CMV seropositive healthy individuals. Adaptive-like NK cell expansions observed in viral hepatitis patients were strongly associated with CMV seropositivity. The number of subjects with these expansions did not differ between CMV seropositive viral hepatitis patients and corresponding healthy controls. Hence, we conclude that adaptive-like NK cell expansions observed in HBV, HCV, and/or HDV infected individuals are not caused by the chronic hepatitis infections per se, but rather are a consequence of underlying CMV infection.

MECHANISMS OF INTERACTION OF VIRAL CAUSATIVE AGENTS IN PATIENTS CO-INFECTED WITH HUMAN IMMUNODEFICIENCY AND HEPATITIS C VIRUSES

In patients infected with human immunodeficiency virus (HIV) in 20 - 30% of cases co-infection with hepatitis C virus (HCV) is observed, that is associated with common routes of transmission for these causative agents. The main cause of lethal outcome for co-infected patients is liver damage. Thus, analysis of mechanisms of mutual influence of HIV and HCV under the conditions of co-infection gains special attention, that can be examined from both standpoints of direct inter-molecular interaction of 2 viral causative agents, as well as from the position of their immune-mediated effect. Negative effect of HIV on the course of fibrosis process in liver during HCVinfection is associated with the feature of this virus to cause deep alteration in the immune system by direct damage of CD4+ cells, disruption of mechanisms of immunological memory, suppression of functions of liver fraction of NK and NKT, as well as its ability of co-receptor interaction with hepatocytes and stellate cells, enhancing progress of fibrosis alterations and HCV replication in liver. HCV is also established to effect replication of HIV, stimulate infection of macrophages with this virus. All these events facilitate the rise in lethality during HIV and HCV co-infection.