NK cells prevalence, subsets and function in viral hepatitis C

Host Responses to Live-Attenuated ASFV (HLJ/18-7GD)

African swine fever (ASF) is a highly contagious and fatal disease caused by the African swine fever virus. Recently, the multigene family and CD2v gene-deleted ASF vaccine candidate HLJ/18-7GD was found to be safe and effective in laboratory and clinical trials. However, the immune-protective mechanisms underlying the effects of HLJ/18-7GD remain unclear. We assessed samples from pigs immunized with a single dose of 10⁶ TCID₅₀ HLJ/18-7GD. We found that pigs immunized with HLJ/18-7GD showed high levels of specific antibodies. T lymphocyte subsets (helper T cells (Th); cytotoxic T lymphocytes (CTL); double-positive T cells (DP-T cells)) were temporarily increased in peripheral blood mononuclear cells (PBMCs) after HLJ/18-7GD immunization. Once the HLJ/18-7GD-immunized pigs had been challenged with virulent HLJ/18, the percentage of Th, CTL, and DP-T cells increased significantly. PBMCs extracted from the pigs induced higher levels of CD8⁺ T cells after infection with the HLJ/18 strain in vitro. The levels of GM-CSF, IFN-γ, and TNF-α were upregulated at 7 days post-inoculation; this finding was contrary to the results obtained after HLJ/18 or HLJ/18ΔCD2v infection. The immune protection from HLJ/18-7GD resulted from many synergies, which could provide a theoretical basis for HLJ/18-7GD as a safe and effective ASF vaccine.

Highly differential count of circulating and tumor infiltrating immune cells in patients with non-HCV/non-HBV hepatocellular carcinoma

Background

Liver transplantation and liver resection are curative options for early hepatocellular carcinoma (HCC). The outcome is in part depended on the immunological response to the malignancy. In this study, we aimed to identify immunological profiles of non-HCV/non-HBV HCC patients.

Methods

Thirty-nine immune cell subsets were measured with multicolor flow cytometry. This immunophenotyping was performed in peripheral blood (PB) and tumor specimens of 10 HCC resection patients and 10 healthy donors. The signatures of the highly differential leukocyte count (hDIF) were analyzed using multidimensional techniques. Functional capability was measured using intracellular IFN-γ staining (Trial Registration DRKS00013567).

Results

The hDIF showed activation (subsets of T-, B-, NK- and dendritic cells) and suppression (subsets of myeloid-derived suppressor cells and T- and B-regulatory cells) of the antitumor response. Principal component analysis of PB and tumor infiltrating leukocytes (TIL) illustrated an antitumor activating gradient. TILs showed functional capability by secreting IFN-γ but did not kill HCC cells.

Conclusions

In conclusion, the measurement of the hDIF shows distinct differences in immune reactions against non-HBV/non-HCV HCC and illustrates an immunosuppressive gradient toward peripheral blood.

Trial Registration

DRKS00013567

Supplementary Information

The online version contains supplementary material available at 10.1007/s00262-021-03061-9.

Cytokine Storm in Domestic Pigs Induced by Infection of Virulent African Swine Fever Virus

African swine fever, caused by African swine fever virus (ASFV), is a highly contagious hemorrhagic disease of domestic pigs. The current continent-wide pandemic has persisted for over 10 years, and its economy-devastating effect was highlighted after spreading to China, which possesses half of the world pig industry. So far, development of an effective and safe vaccine has not been finished largely due to the knowledge gaps in pathogenesis and immunology, particularly the role of cytokines in the host's immune response. Therefore, we performed experiments in domestic pigs to analyze the kinetics of representative circulating interferons (IFNs), interleukins (ILs), growth factors, tumor necrosis factors (TNFs), and chemokines induced by infection of type II virulent ASFV SY18. Pigs infected with this Chinese prototypical isolate developed severe clinical manifestations mostly from 3 days post inoculation (dpi) and died from 7 to 8 dpi. Serum analysis revealed a trend of robust and sustained elevation of pro-inflammatory cytokines including TNF-α, IFN-α, IL-1β, IL-6, IL-8, IL-12, IL-18, RANTES (regulated upon activation, normal T cell expressed and secreted), and IFN-γ-induced protein 10 (IP-10) from 3 dpi, but not the anti-inflammatory cytokines IL-10 and transforming growth factor-β (TGF-β). Moreover, secondary drastic increase of the levels of TNF-α, IL-1β, IL-6, and IL-8, as well as elevated IL-10, was observed at the terminal phase of infection. This pattern of cytokine secretion clearly drew an image of a typical cytokine storm characterized by delayed and dysregulated initiation of the secretion of pro-inflammatory cytokine and imbalanced pro- and anti-inflammatory response, which paved a way for further understanding of the molecular basis of ASFV pathogenesis.

Sorafenib Induces Pyroptosis in Macrophages and Triggers Natural Killer Cell-Mediated Cytotoxicity Against Hepatocellular Carcinoma

Antiangiogenic and cytotoxic effects are considered the principal mechanisms of action of sorafenib, a multitarget kinase inhibitor approved for the treatment of hepatocellular carcinoma (HCC). We report that sorafenib also acts through direct immune modulation, indispensable for its antitumor activity. In vivo cell depletion experiments in two orthotopic HCC mouse models as well as in vitro analysis identified macrophages (MΦ) as the key mediators of the antitumoral effect and demonstrate a strong interdependency of MΦ and natural killer (NK) cells for efficient tumor cell killing. Caspase 1 analysis in sorafenib-treated MΦ revealed an induction of pyroptosis. As a result, cytotoxic NK cells become activated when cocultured with sorafenib-treated MΦ, leading to tumor cell death. In addition, sorafenib was found to down-regulate major histocompatibility complex class I expression of tumor cells, which may reduce the tumor responsiveness to immune checkpoint therapies and favor NK-cell response. In vivo cytokine blocking revealed that sorafenib efficacy is abrogated after inhibition of interleukins 1B and 18. Conclusion: We report an immunomodulatory mechanism of sorafenib involving MΦ pyroptosis and unleashing of an NK-cell response that sets it apart from other spectrum kinase inhibitors as a promising immunotherapy combination partner for the treatment of HCC.

Expression of Natural Killer Cell Inhibitory Receptors is Associated with Significant Liver Injury in Chronic Hepatitis C in Children

INTRODUCTION AND AIM

Natural Killer (NK) cells play an important role in innate immune response to viral infections and their high proportion is situated in the liver. The aim of this study was to analyze possible relation between the expression of NK cell receptors and varied intensity of liver lesions in chronic hepatitis C (CHC) in children.

MATERIAL AND METHODS

Study included 105 children with CHC - 54 boys and 51 girls, age 13.62 ± 3.48 years. Blood specimens were taken at the day of the liver biopsy. Histological evaluation was performed according to METAVIR scoring system. Circulating NK cells were evaluated by flow cytometry. The results were shown as a proportion of cells expressing evaluated receptor and its' mean fluorescent intensity (MFI).

RESULTS

In 58 children with CHC (55.2%) significant liver fibrosis was observed ( ≥F2). Higher proportion of cells expressing CD158e inhibitory receptors was observed in the group of children with ALT > 2UNL (21.11 ± 14.60 vs. 12.22 ± 8.99%; p = 0.037). While higher proportion of cells expressing inhibitory CD158b receptor was observed in children with significant fibrosis (F ≥ 2) compared to minimal fibrosis (F < 2) - (34.14 ± 12.44 vs. 27.48 ± 8.71%; p = 0.049). Children with advanced fibrosis (F ≥ 3) had higher MFI of NK cell CD 158b receptor than children with fibrosis scored F < 3 - (5344.20 ± 3407.49 vs. 2979.67 ± 1190.64; p = 0.049). Proportion of NK cells expressing CD158b was found a predictor of significant fibrosis in univariate analysis - [OR 1.065; 95%CI (1.07-1.15); p = 0.046].

CONCLUSIONS

Higher proportion of NK cells expressing inhibitory CD158b and CD158e receptors is associated with significant liver injury.

Association of killer cell immunoglobulin-like receptors with spontaneous clearance of hepatitis C virus in the Chinese population

BACKGROUND

Natural killer (NK) cells are critical components in innate immune response to viral infection. Killer cell immunoglobulin-like receptors (KIRs) are involved in regulating the balance of activation or inhibitory function of NK cells. However, the association of KIRs with the spontaneous clearance of hepatitis C virus (HCV) remains unclear in the Chinese population.

STUDY DESIGN AND METHODS

A total of 407 HCV-seropositive voluntary blood donors were recruited, including 203 with spontaneous viral clearance and 204 with chronic infection. The presence of KIR genes was detected individually by polymerase chain reaction with sequence-specific primers. Data of HLA and interleukin-28B (IL28B) genotypes were extracted from our previous study.

RESULTS

Our results showed that KIR2DL2, 2DS2, 2DL2/2DL3, and 2DL5A-/2DL5B+ were more frequent in subjects with HCV clearance than those with chronic infection (odds ratio [OR], 1.640, p = 0.034; OR, 1.664, p = 0.032; OR, 1.636, p = 0.040; and OR, 2.601, p = 0.012, respectively). Multivariate logistic regression analysis showed that KIR2DL5A-/2DL5B+ associated with HCV clearance (OR, 2.448, p = 0.027), independent of sex, IL28B, and other KIRs. In contrast, KIR2DL3/2DL3 (OR, 0.610, p = 0.034) as well as 2DL3/2DL3+HLA-C1 or C1C1 (OR, 0.580, p = 0.017; and OR, 0.639, p = 0.025, respectively) was found associated with chronic HCV infection. The presence of the homozygous KIR2DL3 with or without its HLA ligand increased the OR of developing chronic HCV infection in the context of IL28B.

CONCLUSIONS

In this study we identified KIR2DL5A-/2DL5B+ associated with HCV spontaneous clearance, while KIR2DL3/2DL3, 2DL3/2DL3+HLA-C1, or C1C1 associated with chronic infection. Our study highlighted the fact that the roles of KIR and KIR-HLA contributed to the control of HCV infection by innate immune responses.

Role of relevant immune-modulators and cytokines in hepatocellular carcinoma and premalignant hepatic lesions

AIM

To assess the levels of different immune modulators in patients with hepatocellular carcinoma (HCC), in relation to other hepatic diseases.

METHODS

Eighty-eight patients were included in the current study and represented patients with HCC (20), liver cirrhosis (28) and chronic hepatitis (CH; 25), and normal controls (NC; 15). Peripheral blood was isolated for immunophenotyping of active myeloid dendritic cells (mDCs; CD1c and CD40), mature inactive myeloid cells (CD1c and HLA), active plasmacytoid cells (pDCs; CD303 and CD40), mature inactive pDCs (CD30 and HLA), active natural killer (NK) cells (CD56 and CD161), active NK cells (CD56 and CD314) and inactive NK cells (CD56 and CD158) was done by flow cytometry. Serum levels of interleukin (IL)-2, IL-10, IL-12, IL-1β, interferon (IFN)-α, IFN-γ and tumor necrosis factor (TNF)-αR2 were assessed by ELISA.

RESULTS

Active mDCs (CD1C+/CD40+) and inactive mDCs (CD1c+/HLA+) were significantly decreased in HCC patients in relation to NC (P < 0.001). CD40+ expression on active pDCs was decreased in HCC patients (P < 0.001), and its level was not significantly changed among other groups. Inactive pDCs (CD303+/HLA+), inactive NKs (CD56+/CD158+) and active NKs (CD56+/CD161+) were not statistically changed among the four groups studied; however, the latter was increased in CH (P < 0.05). NKG2D was statistically decreased in HCC, CH and cirrhosis (P < 0.001), and it was not expressed in 63% (12/20) of HCC patients. There was significant decrease of IL-2, IFN-α and IFN-γ (P < 0.001), and a significant increase in IL-10, IL-1β, and TNF-αR2 (P <0.01, P < 0.001 and P < 0.001; respectively) in HCC patients. There was inverted correlation between IL-12 and IL-1β in HCC (r = -0.565, P < 0.01), with a strong correlation between pDCs (CD303+/CD40+) and NKs (CD56+/CD161+; r = 0.512, P < 0.05) as well as inactive mDCs (CD1c+/HLA+) and inactive NK cells (CD56+/CD158+; r = 0.945, P < 0.001).

CONCLUSION

NKG2D, CD40, IL-2 and IL-10 are important modulators in the development and progression of HCC.

Immunoregulatory Role of NK Cells in Tissue Inflammation and Regeneration

NK cells represent an important first line of defense against viral infection and cancer and are also involved in tissue homeostasis. Studies of NK cell activation in the last decade have revealed that they are able to respond to the inflammatory stimuli evoked by tissue damage and contribute to both progression and resolution of diseases. Exacerbation of the inflammatory response through interactions between immune effector cells facilitates the progression of non-alcoholic fatty liver disease (NAFLD) into steatosis, cirrhosis, and hepatocellular carcinoma (HCC). When hepatic damage is incurred, macrophage activation is crucial for initiating cross talk with neighboring cells present in the liver, including hepatocytes and NK cells, and the importance of this interaction in shaping the immune response in liver disease is increasingly recognized. Inflicted structural damage can be in part regenerated via the process of self-limiting fibrosis, though persistent hepatic damage will lead to chronic fibrosis and loss of tissue organization and function. The cytotoxic activity of NK cells plays an important role in inducing hepatic stellate cell apoptosis and thus curtailing the progression of fibrosis. Alternatively, in some diseases, such as HCC, NK cells may become dysregulated, promoting an immunosuppressive state where tumors are able to escape immune surveillance. This review describes the current understanding of the contributions of NK cells to tissue inflammation and metabolic liver diseases and the ongoing effort to develop therapeutics that target the immunoregulatory function of NK cells.

Immune regulation in chronic hepatitis C virus infection

The immunological result of infection with Hepatitis C virus (HCV) depends on the delicate balance between a vigorous immune response that may clear the infection, but with a risk of unspecific inflammation and, or a less inflammatory response that leads to chronic infection. In general, exhaustion and impairment of cytotoxic function of HCV-specific T cells and NK cells are found in patients with chronic HCV infection. In contrast, an increase in immune regulatory functions is found primarily in form of increased IL-10 production possibly due to increased level and function of anti-inflammatory Tregs. Thus, the major immune players during chronic HCV infection are characterized by a decrease of cytotoxic function and increase of inhibitory functions. This may be an approach to diminish intrahepatic and systemic inflammation. Finally, there has been increasing awareness of regulatory functions of epigenetic changes in chronic HCV infection. A vast amount of studies have revealed the complexity of immune regulation in chronic HCV infection, but the interplay between immune regulation in virus and host remains incompletely understood. This review provides an overview of regulatory functions of HCV-specific T cells, NK cells, Tregs, IL-10, and TGF-β, as well as epigenetic changes in the setting of chronic HCV infection.

Hepatitis C Virus-Induced Myeloid-Derived Suppressor Cells Suppress NK Cell IFN-γ Production by Altering Cellular Metabolism via Arginase-1

The hepatitis C virus (HCV) infects ∼ 200 million people worldwide. The majority of infected individuals develop persistent infection, resulting in chronic inflammation and liver disease, including cirrhosis and hepatocellular carcinoma. The ability of HCV to establish persistent infection is partly due to its ability to evade the immune response through multiple mechanisms, including suppression of NK cells. NK cells control HCV replication during the early phase of infection and regulate the progression to chronic disease. In particular, IFN-γ produced by NK cells limits viral replication in hepatocytes and is important for the initiation of adaptive immune responses. However, NK cell function is significantly impaired in chronic HCV patients. The cellular and molecular mechanisms responsible for impaired NK cell function in HCV infection are not well defined. In this study, we analyzed the interaction of human NK cells with CD33(+) PBMCs that were exposed to HCV. We found that NK cells cocultured with HCV-conditioned CD33(+) PBMCs produced lower amounts of IFN-γ, with no effect on granzyme B production or cell viability. Importantly, this suppression of NK cell-derived IFN-γ production was mediated by CD33(+)CD11b(lo)HLA-DR(lo) myeloid-derived suppressor cells (MDSCs) via an arginase-1-dependent inhibition of mammalian target of rapamycin activation. Suppression of IFN-γ production was reversed by l-arginine supplementation, consistent with increased MDSC arginase-1 activity. These novel results identify the induction of MDSCs in HCV infection as a potent immune evasion strategy that suppresses antiviral NK cell responses, further indicating that blockade of MDSCs may be a potential therapeutic approach to ameliorate chronic viral infections in the liver.

Contradicting roles of miR-182 in both NK cells and their host target hepatocytes in HCV

BACKGROUND AND AIM

Natural killer cells are part of the innate immunity involved in viral eradication and were shown to be greatly affected by HCV infection. Epigenetic regulation of NK cell function by microRNAs was not efficiently studied before and was never studied in HCV infection; therefore the aim of this study was to assess for the first time the role of microRNAs in regulating the function of NK cells of HCV-infected patients and hence viral replication in the target HCV-infected Huh7 cells.

METHODOLOGY

NK cells were isolated from PBMCs of HCV-infected patients as well as controls, and HCV-infected liver biopsies as well as Huh7 cells infected with the virus were used. For the infection of Huh7 cells, first viral vector was in-vitro transcribed into viral RNA that was then used to infect naїve Huh7 cells. Supernatant from the infected cells was then collected and used for further infection. For manipulation of NK cells or Huh7 cells, miR-182 mimics and inhibitors were transfected via lipofection method. RNA was extracted from each cell population, reverse transcribed. Gene expression as well as viral load was quantified using qPCR.

RESULTS

Screening of NKG2A and NKG2D between patients and controls showed no difference in expression of NKG2A, while NKG2D was found to be downregulated. In view of that, bioinformatics analysis was performed and showed that miR-182 has potential binding sites on both the inhibitory receptor NKG2A and the activating receptor NKG2D, and on its ligand ULBP2, as well as on the viral genome itself. In NK cells of HCV-infected patients, miR-182 was found to be over-expressed compared to controls; its ectopic expression was found to decrease NKG2D mRNA level, while miR-182 inhibitors were able to decrease NKG2A mRNA compared to untransfected cells. In addition, co-culturing genotype 4 or 2 HCV-infected Huh7 cells with miR-182 mimicked NK cells of HCV-infected patients showed decreased viral replication, suggesting an enhanced NK cell function. On the other hand, miR-182 and ULBP2 were both found to be downregulated in HCV liver tissues and HCV-infected Huh7 cells compared to their controls. miR-182 mimics were found to decrease ULBP2 mRNA and increase viral replication in genotypes 4 and 2 HCV-infected target (Huh7) cells compared to controls, while miR-182 inhibitor decreased viral replication in the cell models.

CONCLUSION

miR-182 was never investigated before, neither in HCV infection nor in NK cells, and we found it to have dysregulated expression in both liver tissues and NK cells of HCV-infected patients compared to control. In addition to that, miR-182 was found to have a contradicting effect in both effector cell and its HCV-infected target cell regarding HCV replication.

Genetic (KIR, HLA-C) and Some Clinical Parameters Influencing the Level of Liver Enzymes and Early Virologic Response in Patients with Chronic Hepatitis C

Natural killer cells play an important role as effectors of innate immunity and regulators of adaptive immunity. They are important elements of the innate response to viral infections, which they detect using human leukocyte antigen (HLA) class I-binding receptors. Most polymorphic of these are killer cell immunoglobulin-like receptors (KIRs) which exist as two basic isotypes, activating or inhibitory receptors and are encoded by genes distributed differently in unrelated individuals. We searched for links between selected clinical data (including HCV viremia, liver enzymes level and liver histology parameters) and the presence of genes encoding these receptors and their ligands in hepatitis C virus-infected individuals subjected to pegylated interferon-α and ribavirin therapy. Genomic DNA samples from two hundred and ninety-two chronically infected patients were typed by polymerase chain reaction for the presence or absence of genes for KIRs and their ligands, class I HLA molecules, and clinical data of the patients were collected. Our results suggest an importance of clinical parameters and the contribution of KIR and HLA genes to the course of hepatitis C virus infection and the response to therapy. The study revealed that levels of liver enzymes before therapy were about 30 % higher in patients who possessed a variant KIR2DS4 gene with 22-base pair deletion. Decrease of ALT activity after treatment was higher in HLA-C C2-positive than negative individuals. Beside it, patients demonstrated early virologic response to the therapy if the time lag before treatment was short, particularly in women.

Imbalance between CD56+bright and CD56+dim natural killer cell subsets in the liver of patients with recurrent hepatitis C after liver transplantation

Progressive liver fibrosis remains a major problem for patients with recurrent chronic hepatitis C(CHC) after liver transplantation (LT). However, the involvement of natural killer (NK) and natural killer T (NKT) cells, which predominate in the liver, in recurrent CHC after LT remains unclear.In the present study, we investigated the status of NK and NKT cells in the liver and peripheral blood obtained from 10 patients with recurrent CHC after LT (LT-C), 15 patients with CHC, and 7 normal donors for living donor LT. CD56+ NK cells were separated into two subsets: CD56+bright subset, which is identified as major NK cytokine producer, and CD56+dim subset, which has greater spontaneous cytotoxicity. We found a significant decrease in the CD56+bright subset in the liver of patients with LT-C compared to patients with CHC (P<0.01) and normal donors (P=0.03). The expression of inhibitory NK cell receptor NKG2A was significantly increased on intrahepatic CD56+bright subset in LT-C patients, and activated CD69+CD56+dim NK cell subset was significantly increased in the liver of LT-C patients. Our results suggest that a significant imbalance between CD56+bright and CD56+dim NK cell subsets in the liver may contribute to the progression of recurrent CHC after LT.

Contribution of genes for killer cell immunoglobulin-like receptors (KIR) to the susceptibility to chronic hepatitis C virus infection and to viremia

BACKGROUND

Natural killer (NK) cells are an important element of innate immunity against viruses, although their numbers decrease in the liver during chronic HCV infection. NK cells express a large panel of inhibitory and activating receptors. The most polymorphic of these are killer cell immunoglobulin-like receptors (KIRs) which are encoded by multiple genes that may be present or absent in given individuals depending on their genotype. This variability results in differential susceptibility to viral infections and diseases, including HCV infection and its consequences.

AIMS AND METHODS

The aim of this study was to test whether chronical infection with HCV and the viremia levels are associated with any KIR gene in the Polish population. We typed 301 chronically HCV-infected patients and 425 non-infected healthy individuals for the presence or absence of KIR genes and their ligands, HLA-C C1 and C2 groups as well as HLA-B and HLA-A Bw4-positive alleles.

RESULTS

We found that males, but not females, possessing KIR2DS2 and KIR2DL2 genes had a 1.7 higher probability to become chronically HCV-infected than males negative for these genes (p=0.0213). In accord with this, centromeric B region, containing KIR2DS2 and KIR2DL2 genes, was also associated with chronic HCV infection in males. In addition, patients of both genders possessing KIR2DS3 but not KIR2DS5 gene exhibited, on average, 2.6 lower level of viremia than HCV-infected individuals with other genotypes (p=0.00282). This was evident in those infected at a young age. KIR2DS3-positive patients also had lower mean levels of bilirubin than KIR2DS3-negative ones (p=0.02862).

CONCLUSION

Our results suggest a contribution of the KIR2DS2 and KIR2DL2 genes (cenB haplotype) to the susceptibility to chronic HCV infection, and an association of the KIR2DS3 gene in the absence of KIR2DS5 with low viremia levels.

MHC class I-related chain B gene polymorphism is associated with virological response to pegylated interferon plus ribavirin therapy in patients with chronic hepatitis C infection

The outcome of antiviral therapy is associated with viral and host factors. In the present study, the association between MHC class I-related chain B (MICB) genotypes and therapeutic response to pegylated interferon plus ribavirin (PEG-IFN/RBV) therapy was investigated in hepatitis C virus (HCV)-infected patients. In total, 107 patients with chronic HCV infection (74 with HCV serotype 1 and 33 with serotype 2) were enrolled. Genotyping of MICB single-nucleotide polymorphism (SNP) rs3828913 and interleukin-28B (IL28B) SNP rs8099917 was performed using TaqMan^® SNP genotyping assays. The genotype distribution of the MICB alleles was: CC, 79.4%; CA, 17.8%; and AA, 2.8%. Sustained virological response (SVR) was achieved by 55.1% (59/107) of the HCV patients. The SVR rate of patients with MICB major (CC) alleles was 62.3% and this rate was significantly higher than that of the patients with MICB minor (CA and AA) alleles (27.2%) (P=0.0068). A multivariate logistic model showed that the MICB major genotype was an independent factor contributing to SVR (OR, 4.47; 95% CI, 1.46-13.70; P=0.009). In addition, the MICB genotype was identified as the sole independent factor contributing to SVR and non-virological response in HCV serotype 1 patients with the IL28B major genotype. In HCV serotype 2 patients, the MICB genotype was the sole significant factor contributing to SVR (OR, 30.68; 95% CI, 2.72-346.3; P=0.006). In conclusion, the MICB genotype is a strong predictive factor for virological response to PEG-IFN/RBV therapy in HCV patients.

Detection and significance of cytotoxic cell subsets in biopsies of HCV-infected human livers

Chronic viral hepatitis C still remains the clinical challenge. Attempts of the immune system to cope with this infection are unsatisfactory. There is a conviction that the main site of interaction between virus (Hepatitis C virus, HCV) and immune system is in situ, i.e., in liver. Natural killer (NK) cells appeared relevant in the acute hepatitis. Less is known about the immune response in the chronic HCV infection. The aim of this study was to evaluate the prevalence of various cytotoxic cell subsets in chronic HCV⁺ liver tissue and to seek links between them and laboratory data of patients. Sections from paraffin blocks of liver biopsy tissues of HCV⁺ untreated patients were subjected to the reaction with antibodies vs. cytotoxic cell subsets and immunohistochemistry. Positive cells were searched in cellular infiltrates in portal areas and in liver parenchyma. They were classified on the “Yes” or “No” basis. Majority of liver biopsies exhibited cellular infiltrates in portal spaces and as single cells in liver parenchyma. Infiltrates consisted of CD8⁺ T cells, CD56⁺ NK ones, including CD158i⁺ and CD158b⁺. The latter were rarely seen. There were also granzyme B⁺ cells. The most abundant were NKG2D⁺ cells, much more common than NK CD56⁺ ones. It implied that NKG2D was also expressed on T cells. Prevalence of NKG2D⁺ cells correlated with high activity of liver enzymes such as alanine aminotransferase, aspartate aminotransferase and a greater histological severity of liver injury. NKG2D⁺ cells form the bulk of cells infiltrating HCV-infected human liver. Correlation of NKG2D⁺ cells with some laboratory parameters of patients suggests their role in hepatitis C pathogenesis.

Effect of human leukocyte antigen class I and II alleles on hepatitis C viral load among chronic hepatitis C patients in Southern Taiwan

The viral load of hepatitis C virus (HCV) in chronic hepatitis C patients affects clinical outcomes and response to interferon treatment. Various factors may be involved in determining the viral load, including host genetic factors. The aim of this study was to investigate the relationship between HCV viral load and human leukocyte antigen (HLA) class I and class II alleles. One hundred and six HCV RNA positive subjects were enrolled, and viral load was measured. HLA-A, -B, -C, -DR, and -DQ loci were determined by sequence-based genotyping. Univariate analysis indicated that HLA-B(*)40 and HLA-C(*)07 alleles had significantly higher HCV RNA levels (P<0.05). Patients with the HLA-C(*)15 allele exhibited a trend toward a lower HCV viral load (P=0.06). After controlling for confounding factors, multivariate analysis revealed that only HLA-C(*)15 allele was identified as a significant determinant for HCV-RNA level (slope=-0.91, 95% CI: -1.58, -0.24; Holm's P<0.01). Patients expressing the HLA-C(*)15 allele had significantly lower HCV RNA levels. HCV genotype 1 was significantly associated with high HCV RNA levels (P<0.05 by Mann-Whitney U test). In conclusion, HLA-C(*)15 is an important host immunogenetic factor with an inverse association to HCV viral load in CHC patients in Taiwan. HCV genotype 1 is the viral factor that associated with high viral load.

Immunity and hepatitis C: a review

Hepatitis C virus (HCV) is a major cause of chronic hepatitis and hepatocellular carcinoma worldwide. Due to shared transmission routes, the prevalence of HCV is especially high among individuals infected with HIV. HIV uninfected individuals spontaneously clear HCV approximately 30 % of the time, while the rate of control in HIV infected individuals who subsequently acquire HCV is substantially lower. In addition, complications of HCV are more frequent in those with HIV infection, making liver disease the leading cause of non-AIDS-related death in HIV infected individuals. This review summarizes recent advances in understanding the role of the innate and adaptive immune responses to HCV in those with and without HIV. Further defining the interaction between hepatitis C and the host immune system will potentially reveal insights into HCV pathogenesis and the host's ability to prevent persistent infection, as well as direct the development of vaccines.

Cellular immunity in ASFV responses

African swine fever virus (ASFV) infection usually results in an acute haemorrhagic disease with a mortality rate approaching 100% in domestic pigs. However, pigs can survive infection with less-virulent isolates of ASFV and may become chronically infected. Surviving animals are resistant to challenge with homologous or, in some cases, closely related isolates of the virus indicating that pigs can develop protective immunity against ASFV. During asymptomatic, non-virulent ASFV infections natural killer cell activity increases in pigs, suggesting this cell type plays a role in ASFV immunity. Furthermore, depletion of CD8(+) lymphocytes from ASFV immune pigs demolishes protective immunity against related virulent viruses. This suggests that ASFV specific antibody alone is not sufficient for protection against ASFV infection and that there is an important role for the CD8(+) lymphocyte subset in ASFV protective immunity. These results were supported by DNA immunization studies, demonstrating a correlation between the protection afforded against lethal challenge and the detection of a large number of vaccine-induced antigen-specific CD8(+) T-cells. Peripheral blood mononuclear cells (PBMCs) from ASF immune pigs protected from clinical disease show higher proportions of ASFV specific CD4(+)CD8(high+) double positive cytotoxic T cells than PBMCs from ASF immune but clinically diseased pig. The frequency of ASFV specific IFNγ producing T cells induced by immunization correlates to the degree of protection from ASFV challenge, and this may prove to be a useful indicator of any potential cross-protection against heterologous ASFV isolates.