The presence of KIR2DS5 confers protection against adult immune thrombocytopenia

High-Resolution Analysis Identifies High Frequency of KIR-A Haplotypes and Inhibitory Interactions of KIR With HLA Class I in Zhejiang Han

Killer cell immunoglobulin-like receptors (KIR) interact with human leukocyte antigen (HLA) class I molecules, modulating critical NK cell functions in the maintenance of human health. Characterizing the distribution and characteristics of KIR and HLA allotype diversity across defined human populations is thus essential for understanding the multiple associations with disease, and for directing therapies. In this study of 176 Zhejiang Han individuals from Southeastern China, we describe diversity of the highly polymorphic KIR and HLA class I genes at high resolution. KIR-A haplotypes, which carry four inhibitory receptors specific for HLA-A, B or C, are known to associate with protection from infection and some cancers. We show the Chinese Southern Han from Zhejiang are characterized by a high frequency of KIR-A haplotypes and a high frequency of C1 KIR ligands. Accordingly, interactions of inhibitory KIR2DL3 with C1+HLA are more frequent in Zhejiang Han than populations outside East Asia. Zhejiang Han exhibit greater diversity of inhibitory than activating KIR, with three-domain inhibitory KIR exhibiting the greatest degree of polymorphism. As distinguished by gene copy number and allele content, 54 centromeric and 37 telomeric haplotypes were observed. We observed 6% of the population to have KIR haplotypes containing large-scale duplications or deletions that include complete genes. A unique truncated haplotype containing only KIR2DL4 in the telomeric region was also identified. An additional feature is the high frequency of HLA-B*46:01, which may have arisen due to selection pressure from infectious disease. This study will provide further insight into the role of KIR and HLA polymorphism in disease susceptibility of Zhejiang Chinese.

KIR2DL2/S2 and KIR2DS5 in alcoholic cirrhotic patients undergoing liver transplantation

INTRODUCTION

The molecular mechanisms underlying alcoholic liver fibrosis and cirrhosis are not completely understood. Hepatic fibrosis involves the interplay of diverse cells and factors, including hepatic stellate cells (HSCs), Kupffer, NK cells, and T-lymphocyte subsets. Killer-cell immunoglobulin-like receptors (KIR) are membrane receptors involved in mediation between NK and activated HSCs, regulating NK cell function through their interaction with HLA-I molecules. The aim of this study was to analyse the genetic association between KIR genes and the susceptibility to or protection from alcoholic cirrhosis (AC) in a cohort of male AC patients undergoing liver transplantation (LT) with and without concomitant viral infections.

MATERIAL AND METHODS

KIR genotyping was performed in nuclear DNA extracted from 281 AC patients and compared with 319 male controls.

RESULTS

Significant differences between total AC patients and healthy controls were only found in the case of KIR2DL2 and KIR2DS5. KIR2DL2 was significantly underrepresented in non-viral AC patients (52.6% vs. 63.3%; p = 0.015), while patients heterozygous for KIR2DL2 were also underrepresented in the non-viral AC group compared with controls (p = 0.034). KIR2DS5 was overrepresented in this group compared with healthy controls (p = 0.002). All these observations were only evident in AC patients older than 54 years old.

CONCLUSIONS

Our data suggest a contrary effect of KIR2DL2 and KIR2DS5 in AC patients older than 54 years, in whom the presence of KIR2DL2 appears to be protective against AC, whereas the presence of KIR2DS5 seems to promote the fibrotic process, particularly in patients with no associated viral infection.

Significance of KIR like natural killer cell receptors in autoimmune disorders

Killer cell immunoglobulin-like receptors (KIRs), act as the regulators for the cytolytic activity of natural killer and certain T cells by interacting with the HLA class I ligands. KIRs have been shown to contribute to the pathogenesis of several autoimmune diseases. However, their specific roles are still not very clear. Autoimmune diseases are multifactorial in nature, highlighting the influence of both genetic and environmental factors. The innate immune response plays an important role in autoimmunity as it alters the self-glycans that mimic molecular patterns found on different intracellular pathogens. Natural killer (NK) cells have an important position in the innate immune response. NK cell receptors are encoded by the leukocyte receptor complex located on the chromosome 19q13.4 and lectin-like receptors on chromosome 12p13. This review focuses on the role of KIRs and their relationship with different autoimmune diseases.

Activating killer cell immunoglobulin-like receptors: Detection, function and therapeutic use

Killer cell immunoglobulin-like receptors (KIRs) have a central role in the control of natural killer (NK) cell function. The functions of the activating KIRs, as compared to those of the inhibitory KIR, have been more difficult to define due to difficulties in antibody-mediated identification and their apparent low affinities for HLA class I. Immunogenetic studies have shown associations of activating KIRs with the outcome of autoimmune diseases, pregnancy-associated disorders, infectious diseases and cancers. Activating KIR are thus thought to have important roles in the control of natural killer cell functions and their role in disease. In this review, we discuss current knowledge on activating KIR, their ligands and, their roles in the pathogenesis and potential therapy of human diseases.

The Importance of Sex Stratification in Autoimmune Disease Biomarker Research: A Systematic Review

The immune system is highly dynamic and regulated by many baseline characteristic factors. As such, significant variability may exist among different patient groups suffering from the same autoimmune disease (AD). However, contemporary research practices tend to take the reductionist aggregate approach: they do not segment AD patients before embarking on biomarker discovery. This approach has been productive: many novel AD biomarkers have recently been discovered. Yet, subsequent validation studies of these biomarkers tend to suffer from a lack of specificity, sensitivity, and reproducibility which hamper their translation for clinical use. To enhance reproducibility in validation studies, an optimal discovery-phase study design is paramount: one which takes into account different parameters affecting the immune system biology. In this systematic review, we highlight need for stratification in one such parameter, i.e., sex stratification. We will first explore sex differences in immune system biology and AD prevalence, followed by reported sex-bias in the clinical phenotypes of two ADs—one which more commonly affects females: systemic lupus erythematosus, and one which more commonly affects males: ankylosing spondylitis. The practice of sex stratification in biomarker research may not only advance the discovery of sex-specific AD biomarkers but more importantly, promote reproducibility in subsequent validation studies, thus easing the translation of these novel biomarkers from bench to bedside to improve AD diagnosis. In addition, such practice will also promote deeper understanding for differential AD pathophysiology in males and females, which will be useful for the development of more effective interventions for each sex type.

Regulation and Function of NK and T Cells During Dengue Virus Infection and Vaccination

The focus of this review is to discuss findings in the last 10 years that have advanced our understanding of human NK cell responses to dengue virus. We will review recently identified interactions of activating and inhibitory receptors on NK cells with dengue virus, human NK responses to natural dengue infection and highlight possible interactions by which NK cells may shape adaptive immune responses. T cell responses to natural dengue infection will be reviewed by Laura Rivino in Chap. 17 . With the advent of numerous dengue vaccine clinical trials, we will also review T and NK cell immune responses to dengue virus vaccination. As our understanding of the diverse functions of NK cell has advanced, it has become increasingly clear that human NK cell responses to viral infections are more complicated than initially recognized.

Missing or altered self: human NK cell receptors that recognize HLA-C

Natural killer (NK) cells are fast-acting and versatile lymphocytes that are critical effectors of innate immunity, adaptive immunity, and placental development. Controlling NK cell function are the interactions between killer-cell immunoglobulin-like receptors (KIRs) and their HLA-A, HLA-B and HLA-C ligands. Due to the extensive polymorphism of both KIR and HLA class I, these interactions are highly diversified and specific combinations correlate with protection or susceptibility to a range of infectious, autoimmune, and reproductive disorders. Evolutionary, genetic, and functional studies are consistent with the interactions between KIR and HLA-C being the dominant control mechanism of human NK cells. In addition to their recognition of the C1 and C2 epitopes, increasing evidence points to KIR having a previously unrecognized selectivity for the peptide presented by HLA-C. This selectivity appears to be a conserved feature of activating KIR and may partly explain the slow progress made in identifying their HLA class I ligands. The peptide selectivity of KIR allows NK cells to respond, not only to changes in the surface expression of HLA-C, but also to the more subtle changes in the HLA-C peptidome, such as occur during viral infection and malignant transformation. Here, we review recent advances in understanding of human-specific KIR evolution and how the inhibitory and activating HLA-C receptors allow NK cells to respond to healthy cells, diseased cells, and the semi-allogeneic cells of the fetus.

Killer immunoglobulin-like receptor repertoire analysis in a Caucasian Spanish cohort with inflammatory bowel disease

Immunological molecules are implicated in inflammatory disorders, including inflammatory bowel disease (IBD; Crohn disease [CD] and ulcerative colitis [UC]). Killer cell immunoglobulin-like receptors (KIRs) are also genetically variable proteins involved in immune function. They are expressed by NK cells and certain T lymphocytes, regulate specificity and function by interaction with HLA Class I molecules, may be either inhibitory or activating and are polymorphic both in terms of alleles and haplotype gene content. Genetic associations between activating KIRs and certain autoimmune and inflammatory diseases have been reported; however, a possible association between KIR and IBD remains unclear. The aim of this study was to determine the relationship between KIR repertoire and IBD pathologies in a Spanish cohort. KIR variability was analyzed using PCR-sequence specific oligonucleotide probes (SSOP). Inhibitory KIR2DL5 was found more frequently in UC and IBD patient groups than in healthy controls (P = 0.028 and P = 0.01, respectively), as was activating KIR2DS1 (P = 0.02, Pc > 0.05, UC vs. Controls; P = 0.001, Pc = 0.01, IBD vs Controls; P = 0.01, Pc > 0.05, Controls vs CR), KIR2DS5 (P = 0.0028, Pc = 0.04, Controls vs UC; P = 0.0001, Pc = 0.0017, Controls vs IBD; P = 0.01, Pc > 0.05, Controls vs CD) and KIR3DS1 (P = 0.012, Pc > 0.05, Controls vs IBD). Our data suggest that imbalance between activating and inhibitory KIR may partially explain the different pathogeneses of these IBDs and that there is a hypothetical role for the telomeric B region (which contains both KIR2DS5 and KIR2DS1) in these diseases.

KIR2DS2 as predictor of thrombocytopenia secondary to pegylated interferon-alpha therapy

Our aim was to evaluate the killer cell immunoglobulin-like receptors (KIRs) as a marker for the development of thrombocytopenia secondary to Peg-interferon (IFN) therapy in a cohort of human immunodeficiency virus (HIV)/hepatitis C virus (HCV) co-infected patients. Patients were naive to HCV treatment, receiving a first course of Peg-IFN/Ribavirin combination therapy. Total platelet count (cells ml^-1) was determined at each visit, determining platelet decline from baseline to weeks 1, 2, 4, 8 and 12 after starting therapy. The end point of the study was development of thrombocytopenia, defined as a platelet count of <1 50 000 cells ml^-1. Fifty-eight HIV/HCV co-infected patients were included in the study, of whom 20 (34.4%) developed thrombocytopenia. The absence of KIR2DS2 was associated with higher and faster rate of thrombocytopenia (54.2% vs 22.5%; P=0.012; 6.6 vs 10.3 weeks; P=0.008). The absence of KIR2DS2 was associated with a greater decline in platelet count and development of thrombocytopenia during Peg-IFN treatment in HIV/HCV co-infected patients.

A Study of Human Killer Cell Immunoglobulin-Like Receptor and Multidrug Resistance Gene Polymorphisms in Children With Immune Thrombocytopenia

THE OBJECTIVE

This study was undertaken to detect characterization of the different gene polymorphisms in Human killer cell immunoglobulin-like receptor (KIR2) gene and multi-drug resistance (MDR1) gene, among childhood ITP Egyptian patients. In addition to assess the potential role of these polymorphisms in relation to types of ITP and response to different treatment modalities.

PATIENTS AND METHODS

A total of 48 pediatric patients with immune thrombocytopenia (ITP; 24 newly diagnosed and 24 chronic) and 35 healthy controls were investigated via polymerase chain reaction-restriction fragment length polymorphism analysis for multidrug resistance (MDR) 1 and killer cell immunoglobulin-like receptor (KIR) 2 genes.

RESULTS

The frequency of MDR1 gene in patients and control was not significant (P = .090). The CT genotype was the highest distribution among all ITP cases (62.50%, n = 30) and control (48.60%, n = 17). There was a significant difference in age at diagnosis of MDR1 gene with the CC genotype had the eldest age and lowest initial platelets count (P = .029 and P = .004). The distribution of KIR2 gene among all patients with ITP and controls was significant (P = .026) with (KIRDL2-/KIRDS2-) genotype was the most prevalent among patients.

CONCLUSION

The frequency of MDR1 polymorphisms was not associated with susceptibility to the development and clinical progression of the disease. However, KIR2 gene polymorphisms were independently associated with childhood ITP in Egyptian patients with highest prevalence among (KIRDL2-/KIRDS2-) genotypes.