Combination of human leukocyte antigen and killer cell immunoglobulin-like receptor genetic background influences the onset age of hepatocellular carcinoma in male patients with hepatitis B virus infection

KIR/HLA ligands immunogenetics markers associated with outcome of hepatitis B virus infection in the Bulgarian population

BACKGROUND

Hepatitis B virus (HBV) infection is one of the most common infections worldwide, having negative impact on world health due to the tendency for chronification with late complications such as liver cirrhosis and hepatocellular carcinoma. Natural killer (NK) cells as part of innate antiviral defense influence the clinical course of HBV infection: elimination of the virus or chronic disease.

AIM

Therefore, we investigated the polymorphisms of the main gene systems, regulating NK-cell function: killer cell immunoglobulin-like receptors (KIRs) and their appropriate HLA class I ligands in 144 HBV infected patients (124 chronic carriers and 20 spontaneously recoved) and 126 ethnically matched healthy controls from the Bulgarian population in a case-control study.

METHODS

KIRs and HLA ligands were determined by PCR-SSP or PCR high-resolution typing methods.

RESULTS

KIR2DL5B allele variant was significantly less frequent in spontaneously recovered (SR) patients compared to healthy controls (10.0% vs. 45.5%, P^corr=0.006). The presence of KIR3DL1*004 allele was higher in chronic HBV carriers (CH) than in controls (33.1% vs. 17.6%, P^corr=0.036). Additionally, SR patients differed from healthy individuals by the lower frequency of HLA-Bw4^Ile80 group ligands (30.0% vs 63.7%, P=0.015). Three KIR genotypes were found more frequent in healthy in comparison with HBV infected individuals: ID2 (13.5% vs 5.6%, P=0.025), KIR genotype containing 6 activating KIRs (18.0% vs 7.6%, P=0.017), and KIR genotype composed of 4 activating and 5 inhibitory KIRs (23.8% vs 5.6%, P=0.001).

CONCLUSION

These data suggest that inherited KIR and HLA class I ligand polymorphisms may influence the clinical course of HBV infection.

Imbalance of Genes Encoding Natural Killer Immunoglobulin-Like Receptors and Human Leukocyte Antigen in Patients With Biliary Cancer

BACKGROUND & AIMS

Bile duct tumors are rare and have poor prognoses. Natural killer (NK) cells are frequent in human liver and infiltrate these tumors but do not control their progression. Responses of NK cells are regulated by NK immunoglobulin-like receptors (KIRs), which interact with HLA class I ligands. We aimed to characterize the features of the KIR gene loci and their ligands in patients with bile duct cancer (BDC).

METHODS

We performed combined multidimensional characterization of genes that encode KIRs and their ligands in blood samples from patients with BDC from Sweden, followed for up to 8 years after diagnosis (n = 148), in 2 geographically matched cohorts of healthy individuals from Northern Europe (n = 204 and n = 900), and in healthy individuals from 6 geographically unrelated populations (n = 2917). We used real-time polymerase chain reaction, RNA sequencing, immunohistochemistry, and flow cytometry to evaluate NK-cell presence, as well as KIR and KIR-ligand expression in bile duct tumors and control tissues.

RESULTS

Patients with bile duct tumors had multiple alterations at the KIR gene loci. KIR loci are grouped into genotypes that encode more inhibitory (group A) and more activating (group B) receptors, which can be subdivided into centromeric and telomeric fragments. Patients with BDC had a lower prevalence of KIR2DL3, which was linked to disequilibrium in centromeric A/B and B/B genotypes, compared with control individuals. The associations between KIRs and KIR ligands differed between patients with BDC and control individuals; patients had an altered balance between activating and inhibitory KIRs. KIR-positive NK cells infiltrated biliary tumors that expressed matched KIR ligands.

CONCLUSIONS

In a multidimensional analysis of DNA from blood samples of patients with BDC in Europe, we found patients to have multiple alterations at the KIR and HLA gene loci compared with control individuals. These alterations might affect NK-cell tumor surveillance. NK cells from bile duct tumors expressed KIRs and were found in tumors that expressed cognate ligands. This should be considered in development of immune-based therapies for BDC.

Natural Killer Cell Dysfunction in Hepatocellular Carcinoma: Pathogenesis and Clinical Implications

Hepatocellular carcinoma (HCC) is currently the third leading cause of malignancy-related mortalities worldwide. Natural killer (NK) cells are involved in the critical role of first line immunological defense against cancer development. Defects in NK cell functions are recognized as important mechanisms for immune evasion of tumor cells. NK cell function appears to be attenuated in HCC, and many previous reports suggested that NK cells play a critical role in controlling HCC, suggesting that boosting the activity of dysfunctional NK cells can enhance tumor cell killing. However, the detailed mechanisms of NK cell dysfunction in tumor microenvironment of HCC remain largely unknown. A better understanding of the mechanisms of NK cell dysfunction in HCC will help in the NK cell-mediated eradication of cancer cells and prolong patient survival. In this review, we describe the various mechanisms underlying human NK cell dysfunction in HCC. Further, we summarize current advances in the approaches to enhance endogenous NK cell function and in adoptive NK cell therapies, to cure this difficult-to-treat cancer.

Natural killer cell education in human health and disease

Natural killer (NK) cells maintain immune homeostasis by detecting and eliminating damaged cells. Simultaneous activating and inhibitory input are integrated by NK cells, with the net signal prompting cytotoxicity and cytokine production, or inhibition. Chief among the inhibitory ligands for NK cells are 'self' human leukocyte antigen (HLA) molecules, which are sensed by killer immunoglobulin-like receptors (KIR). Through a process called 'education', the functional capabilities of each NK cell are counterbalanced by their sensitivity for inhibition by co-inherited 'self' HLA. HLA and their ligands, the killer immunoglobulin-like receptors (KIR), are encoded by polymorphic, polygenic gene loci that segregate independently, therefore, NK education and function differ even between related individuals. In this review, we describe how variation in NK education, reactivity and sensitivity for inhibition impacts reproductive success, infection, cancer, inflammatory and autoimmune diseases.

Association of the genetic diversity of killer cell immunoglobulin-like receptor genes and HLA-C ligand in Saudi women with breast cancer

Breast cancer (BC) progression and metastases have been linked to antitumor immunity inefficiency and particularly to natural killer (NK) cells. Killer cell immunoglobulin-like receptors (KIRs) are the most polymorphic receptors of NK cells. Through their interactions with human leukocyte antigen (HLA)-C ligands, they modulate NK and T cell actions against target cells. Therefore, we studied the combinatorial effect of KIR genes and their HLA-C ligands on the susceptibility to development of BC in Saudi women. The presence of KIR genes and HLA-C1 and HLA-C2 groups was typed in 50 Saudi patients living in Riyadh and 65 healthy controls using polymerase chain reaction with sequence-specific primers. Our results indicated a protective effect by the KIR2DS2, 2DS3, and 2DL5A genes against BC (OR = 0.25, 0.21, and 0.27, respectively, and p < 0.01). The synergistic action of the three genes was observed when they occurred together, and the absence of the three genes increased BC occurrence by 6.5-fold. Distribution of the HLA-C1/C2 ligand between patients and controls showed an increase in the risk of BC occurrence for the heterozygote C1/C2 (OR = 2.33; 95 % CI = 1.08-5.02; p = 0.037) and a protective effect of the homozygote C2C2 (OR = 0.03; 95 % CI = 0.009-0.098; p < 0.001). Combinatory analyses of KIR genes and their HLA-C ligands showed protective effects of KIR2DL2 and 2DL3 in the absence of their HLA-C1 ligand. These results suggested that KIR-gene content combined with their ligand could influence the risk of BC development in women in Saudi Arabia.

Immune checkpoint inhibitors for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer deaths worldwide, and advanced HCC generally caries a poor prognosis. The treatment of advanced disease is limited to sorafenib, which provides only a limited improvement in survival, and novel therapies are, thus, sorely needed. Among emerging alternative approaches, immune checkpoint inhibitors are a particularly promising treatment modality. In this review, we summarize current knowledge of the mechanisms for the two primary targets of immune checkpoint inhibitors and discuss the relevance of these pathways to the immunology of HCC. We also review the state of ongoing and forthcoming trials of immune checkpoint blockade in HCC.

Clinical Relevance of HLA Gene Variants in HBV Infection

Host gene variants may influence the natural history of hepatitis B virus (HBV) infection. The human leukocyte antigen (HLA) system, the major histocompatibility complex (MHC) in humans, is one of the most important host factors that are correlated with the clinical course of HBV infection. Genome-wide association studies (GWASs) have shown that single nucleotide polymorphisms (SNPs) near certain HLA gene loci are strongly associated with not only persistent HBV infection but also spontaneous HBV clearance and seroconversion, disease progression, and the development of liver cirrhosis and HBV-related hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB). These variations also influence the efficacy of interferon (IFN) and nucleot(s)ide analogue (NA) treatment and response to HBV vaccines. Meanwhile, discrepant conclusions were reached with different patient cohorts. It is therefore essential to identify the associations of specific HLA allele variants with disease progression and viral clearance in chronic HBV infection among different ethnic populations. A better understanding of HLA polymorphism relevance in HBV infection outcome would enable us to elucidate the roles of HLA SNPs in the pathogenesis and clearance of HBV in different areas and ethnic groups, to improve strategies for the prevention and treatment of chronic HBV infection.

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.

Familial correlations of onset age of hepatocellular carcinoma: a population-based case-control family study

BACKGROUND

There was lack of evidence for familial aggregation in onset age of hepatocellular carcinoma (HCC) in Chinese population. We conducted a population-based case-control family study to examine familial correlation of age of HCC onset in Taixing, China.

METHODS

A total of 202 cases and 202 matched controls as well as their relatives were included in the study. Lifetime cumulative risks of HCC were estimated using the Kaplan-Meier approach. Cross ratios (CRs) were obtained from stratified Cox proportional hazard models, to assess the familial correlation of onset age.

RESULTS

The mean age of HCC onset was decreased as increasing number of HCC cases in a family. The onset age was the earliest for first-degree relatives, intermediate for second-degree relatives, and latest for non-blood relatives (spouse) (log-rank test, P<0.01). The onset age was significantly correlated between probands and their relatives. In stratified Cox proportional hazard models, the CRs for the probands versus their fathers, mothers, siblings and uncles/aunts were 6.25 (95% confidence interval (CI): 1.84-21.25), 9.81 (95% CI: 1.24-77.56), 6.22 (95% CI: 1.37-28.36) and 3.24 (95% CI: 1.26-8.33), respectively. After adjustment for hepatitis B virus infection, the CRs remained significant.

CONCLUSION

This current study suggested a significant correlation of onset age for HCC among blood relatives. Familial HCC cases yielded earlier age of onset and their relatives have higher HCC risk in early age, highlighting intensive surveillance should be start at an earlier age for individuals with family history of HCC.