Human leukocyte antigen-C and killer immunoglobulin-like receptors in reproductive medicine. / Antígeno leucocitario humano C y receptores tipo inmunoglobulina en medicina reproductiva.

Proper communication between natural killer cells and the human leukocyte antigens of the embryonic trophoblast at the maternal-fetal interface during pregnancy is essential for successful reproduction. However, specific combinations of embryonic human leukocyte antigen-C with killer immunoglobulin-like receptors on decidual natural killer cells (the immunological code of pregnancy) can be associated with obstetric morbidity and pregnancy loss. This article presents an updated review of the mechanisms underlying the interaction between embryonic human leukocyte antigen-C and maternal killer immunoglobulin-like receptors and their relevance to the physiology and pathophysiology of human reproduction.

Una adecuada comunicación entre las células asesinas naturales en la interfase materno-fetal con las moléculas de los antígenos de histocompatibilidad del trofoblasto embrionario es clave en el éxito de la reproducción. Sin embargo, combinaciones de determinados antígenos leucocitarios humanos tipo C embrionarios con los receptores tipo inmunoglobulina presentes en las células asesinas naturales deciduales (el código inmunológico del embarazo), pueden asociarse con morbilidad obstétrica y pérdidas gestacionales. En este artículo se presenta una revisión actualizada de los mecanismos subyacentes a la interacción entre el antígeno de histocompatibilidad tipo C embrionario y los receptores tipo inmunoglobulina maternos, y su relevancia tanto en la fisiología como en la fisiopatología de la reproducción humana.

Natural killer cell receptor variants and chronic hepatitis B virus infection in the Vietnamese population.

OBJECTIVES: Genes of host immunity play an important role in disease pathogenesis and are determinants of clinical courses of infections, including hepatitis B virus (HBV). Killer-cell immunoglobulin-like receptor (KIR), expressed on the surface of natural killer cells (NK), regulate NK cell cytotoxicity by interacting with human leukocyte antigen (HLA) class I molecules and are candidates for influencing the course of HBV. This study evaluated whether variations in KIR gene content and HLA-C ligands are associated with HBV and with the development of liver cirrhosis and hepatocellular carcinoma. METHODS: A Vietnamese study cohort (HBV n = 511; controls n = 140) was genotyped using multiplex sequence-specific polymerase chain reaction (PCR-SSP) followed by melting curve analysis. RESULTS: The presence of the functional allelic group of KIR2DS4 was associated with an increased risk of chronic HBV (OR = 1.86, pcorr = 0.02), while KIR2DL2+HLA-C1 (OR = 0.62, pcorr = 0.04) and KIR2DL3+HLA-C1 (OR = 0.48, pcorr = 0.04) were associated with a decreased risk. The pair KIR2DL3+HLA-C1 was associated with liver cirrhosis (OR = 0.40, pcorr = 0.01). The presence of five or more activating KIR variants was associated with hepatocellular carcinoma (OR = 0.53, pcorr = 0.04). CONCLUSIONS: KIR gene content variation and combinations KIR-HLA influence the outcome of HBV infection.

Recurrent Spontaneous Abortion (RSA) and Maternal KIR Genes: A Comprehensive Meta-Analysis.

Natural killer cells (NKs) are the most important cells in the fetomaternal immune tolerance induced through interaction of maternal killer-cell immunoglobulin-like receptors (KIR) and fetal human leucocyte antigens (HLA). Hence, we intend to perform a meta-analysis on the role of maternal KIR genes diversity in recurrent spontaneous abortion (RSA). The present paper is a meta-analysis of previous genetic association studies and our previous original study. The results showed that KIR3DL1 was a significantly protecting factor for RSA (p=0.044; OR=0.833 [0.698-0.995]; fixed effect model). KIR2DS2 (p=0.034; OR=1.195 [1.013-1.408]; fixed effect model) and KIR2DS3 (p=0.013; OR=1.246 [1.047-1.483]; fixed effect model) were significantly risk factors for RSA. For KIR2DS1 there was a high heterogeneity and publication bias. Briefly, the inhibitory gene KIR3DL1 was a protecting factor, and the activating genes KIR2DS2 and KIR2DS3 were risk factors for RSA. However, the effect sizes were not suitable. We suggest further studies on different causes of pregnancy loss, to find the role of KIR2DS1.

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.

Cost-effective and fast KIR gene-content genotyping by multiplex melting curve analysis.

Killer cell immunoglobulin-like receptor (KIR) genes encode cell surface molecules that recognize HLA molecules and modulate the activity of natural killer (NK) cells. KIR genes exhibit presence and absence polymorphism, which generates a variety of gene-content haplotypes in worldwide populations. KIR gene-content variation is implicated in many diseases and is also important for placentation and transplantation. Because of the complexity of KIR polymorphism, variation in this family is still mostly studied at the gene-content level, even with the advent of next-generation sequencing (NGS) methods. Gene-content determination is generally expensive and/or time-consuming. To overcome these difficulties, we developed a method based on multiplex polymerase chain reaction with specific sequence primers (PCR-SSP) followed by melting curve analysis that allows cost-effective, precise and fast generation of results. Our method was 100% concordant with a gel-based method and 99.9% concordant with presence and absence determination by NGS. The limit of detection for accurate typing was 30 ng of DNA (0.42 µM) with 260/230 and 260/280 ratios as low as 0.19 and of 0.44. In addition, we developed a user-friendly Java-based computational application called killerPeak that interprets the raw data generated by Viia7 or QuantStudio 7 quantitative PCR machines and reliably exports the final genotyping results in spreadsheet file format. The combination of a reliable method that requires low amount of DNA with an automated interpretation of results allows scaling the KIR genotyping in large cohorts with reduced turnaround time.

Killer-cell immunoglobulin-like receptors associated with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) affects the endocrine system and is associated with low-grade inflammation. Natural killer (NK) cells are involved in the defense of the female reproductive tract, folliculogenesis, ovulation and the menstrual cycle. The killer-cell immunoglobulin-like receptors (KIR) on the surface of NK cells modulate the activation and function of these cells after interacting with human leukocyte antigen (HLA) class I ligands. The objective of this study was to evaluate the possible association of the KIR and their HLA ligands with polycystic ovary syndrome. METHODS: Ninety-three patients with PCOS according to the Rotterdam criteria and 104 healthy controls were included in this study. The HLA class I and KIR genotypes were determined using a PCR-SSO technique, rSSO Luminex®. In order to assess whether the distribution of the HLA and KIR genotypes was in Hardy-Weinberg equilibrium, Arlequin 3.1 software was used. The frequency distributions in the two study groups were compared using the chi-squared statistic with Yates´s correction using Open Epi software. RESULTS: The higher frequencies of KIR3DS1-Bw4 (41% vs. 19%, Pc = 0.002; OR = 2.90) and homozygotic KIR2DS4-del (54% vs. 26%, Pc = 0.0002; OR = 3.316) in patients compared with controls suggest they confer susceptibility to PCOS. A lower frequency of KIR2DS4-full was observed in patients (43% vs. 70%, Pc = 0.0004, OR = 0.320). CONCLUSION: KIR and its HLA ligands were associated with the development of PCOS in the studied population.

Polymorphisms in HLA-C and KIR alleles are not associated with HAM/TSP risk in HTLV-1-infected subjects.

INTRODUCTION: Several genetic polymorphisms may be related to susceptibility or resistance to viral disease outcomes. Immunological or genetic factors may act as major triggers of the immune pathogenesis of HAM/TSP. This study investigated the association of immune related genetic polymorphisms with viral and immunological markers. METHODS: 247 HTLV-1-infected volunteers, drawn from a larger group of HTLV-infected subjects followed at the Institute of Infectious Diseases "Emilio Ribas" (IIER) for up to 19 years, participated in this study, which ran from June 2011 to July 2016. The subjects were classified according to their neurological status into two groups: Group 1 (160 asymptomatic individuals) and Group 2 (87 HAM/TSP patients). Samples were tested for spontaneous lymphocyte proliferation (LPA) and HTLV-1 proviral load (PVL) and for IFN-λ4, HLA-C and KIR genotypes using qPCR. RESULTS: We found associations between LPA (p=0.0001) with HAM/TSP and confirmed the IFN-λ4 polymorphism rs8099917, allele GG, as a protective factor using a recessive model (OR=3.22, CI=1.10-9.47). Polymorphisms in HLA-C and KIR alleles were not associated with risk of developing HAM/TSP. CONCLUSION: We demonstrated that age, LPA and an IFN-λ4 polymorphism were associated with progression to HAM/TSP. Understanding HAM/TSP pathogenesis can provide important markers of prognostic value for clinical management, and contribute to the discovery of new therapeutic interventions in the future.

Killer Cell Immunoglobulin-like Receptors and Their HLA Ligands are Related with the Immunopathology of Chagas Disease.

The aim of this study was to investigate the influence of killer cell immunoglobulin-like receptor (KIR) genes and their human leucocyte antigen (HLA) ligands in the susceptibility of chronic Chagas disease. This case-control study enrolled 131 serologically-diagnosed Chagas disease patients (59 men and 72 women, mean age of 60.4 ± 9.8 years) treated at the University Hospital of Londrina and the Chagas Disease Laboratory of the State University of Maringa. A control group was formed of 165 healthy individuals - spouses of patients or blood donors from the Regional Blood Bank in Maringa (84 men and 81 women, with a mean age of 59.0 ± 11.4 years). Genotyping of HLA and KIR was performed by PCR-SSOP. KIR2DS2-C1 in the absence of KIR2DL2 (KIR2DS2+/2DL2-/C1+) was more frequent in Chagas patients (P = 0.020; Pc = 0.040; OR = 2.14) and, in particular, those who manifested chronic chagasic cardiopathy-CCC (P = 0.0002; Pc = 0.0004; OR = 6.64; 95% CI = 2.30-18.60) when compared to the control group, and when CCC group was compared to the patients without heart involvement (P = 0.010; Pc = 0.020; OR = 3.97). The combination pair KIR2DS2+/2DL2-/KIR2DL3+/C1+ was also positively associated with chronic chagasic cardiopathy. KIR2DL2 and KIR2DS2 were related to immunopathogenesis in Chagas disease. The combination of KIR2DS2 activating receptor with C1 ligand, in the absence of KIR2DL2, may be related to a risk factor in the chronic Chagas disease and chronic chagasic cardiopathy.

Killer cell immunoglobulin-like receptor (KIR) gene diversity in a population naturally exposed to malaria in Porto Velho, Northern Brazil.

Killer cell immunoglobulin-like receptors (KIR) are expressed mainly in natural killer cells and specifically recognize human leukocyte antigen (HLA) class I molecules. The repertoire of KIR genes and KIR-HLA pairs is known to play a key role in the susceptibilities to and the outcomes of several diseases, including malaria. The aim of this study was to investigate the distribution of KIR genes, KIR genotypes and KIR-HLA pair combinations in a population naturally exposed to malaria from Brazilian Amazon. All 16 KIR genes investigated were present in the studied population. Overall, 46 KIR genotypes were defined. The two most common genotypes in the Porto Velho communities, genotypes 1 and 2, were present at similar frequencies as in the Americas. Principal component analysis based on the frequencies of the KIR genes placed the Porto Velho population closer to the Venezuela Mestizos, USA California hispanic and Brazil Paraná Mixed in terms of KIR gene frequencies. This analysis highlights the multi-ethnic profile of the Porto Velho population. Most of the individuals were found to have at least one inhibitory KIR-HLA pair. Seventy-five KIR-HLA pair combinations were identified. The KIR-2DL2/3_HLA-C1, KIR3DL1_HLA-Bw4 and KIR2DL1_HLA-C2 pairs were the most common. There was no association between KIR genes, KIR genotypes or KIR-HLA pair combinations and malaria susceptibility in the studied population. This is the first report on the distribution of KIR and known HLA ligands in the Porto Velho population. Taken together, these results should provide baseline information that will be relevant to population evolutionary history, malaria and other diseases studies in populations of the Brazilian Amazon.

Activating killer immunoglobulin-like receptors genes are associated with increased susceptibility to ankylosing spondylitis.

The aim of this study was to analyse the association of specific killer cell immunoglobulin-like receptors (KIR) genes and haplotypes with susceptibility to ankylosing spondylitis (AS) and its different clinical manifestations in a Spanish population. The presence or absence of all KIR genes was studied for their association with AS. A total of 176 patients with AS and 435 healthy control subjects were selected for this study based on clinical criteria. The commercial KIR-sequence-specific oligonucleotides (SSO) typing kit was used to investigate KIR typing. Frequencies of KIR2DS1 and KIR3DS1 genes were increased significantly in patients compared with healthy controls [52·8 versus 38·2%, PBonf < 0·01, odds ratio (OR) = 1·81 (1·28-2·59); 51·7 versus 37·5%, PBonf < 0·01, OR = 1·79 (1·25-2·54)]. Moreover, the frequency of activating genotypes in the AS patient group was significantly higher than in the healthy control group (P < 0·05). KIR2DS1 and KIR3DS1, in addition to human leucocyte antigen (HLA)-B27, may play an important role in the pathogenesis of AS. However, we show that the contribution of the KIR genes to AS susceptibility extends beyond the association with individual KIRs, with an imbalance between activating and inhibitory KIR genes seeming to influence the susceptibility to AS.

[KIR-HLA class i and pulmonary tuberculosis in the Amerindian population in Chaco, Argentina]. / KIR-HLA clase i y tuberculosis pulmonar en población amerindia del Chaco, Argentina.

INTRODUCTION: The susceptibility to pulmonary tuberculosis (TB) is multifactorial, thus genetic factors such as HLA and immunoglobulins-like killer receptors (KIR) could be predisposed to the development of the disease. Aim To evaluate whether any HLA classi allele and its combination with KIR could be related to the development of TB in the Wichi Amerindian community in north-eastern Argentina. METHODS: A cohort study was conducted that included 18 families, 35 individuals affected with TB, 84 cohabiting families, and 63 controls of the same ethnic group. A and B loci of HLA classi were typed by generic PCR followed by reverse hybridization (Dynal), locus C by PCR-SSOP. KIR receptors were studied using sequence specific PCR. RESULTS: There was a highly significant association with allele B*35:19/47 in TB vs. household contacts [Pc=0.0051] and vs. controls [Pc=0.0033], and with allele HLA-C*03 in TB vs. household contacts [Pc=0.014] and vs. controls [Pc=0.0033]. KIR receptors had shown increased KIR2DL3/KIR2DL3 frequency in combination with the C1 group of HLA-C (P=.018). HLA-C*03 belongs to C1 group, and this combination could have a strong inhibitory action on the infected cell. CONCLUSION: HLA-B35:19/47-C*03 haplotype could be a susceptibility factor to TB and KIR2DL3-HLA-C1 combination have an inhibitory capacity on NK cells, and might contribute to the course of the infection by Mycobacterium tuberculosis.

Role of HLA, KIR, MICA, and cytokines genes in leprosy.

Many genes including HLA, KIR, and MICA genes, as well as polymorphisms in cytokines have been investigated for their role in infectious disease. HLA alleles may influence not only susceptibility or resistance to leprosy, but also the course of the disease. Some combinations of HLA and KIR may result in negative as well as positive interactions between NK cells and infected host cells with M. leprae, resulting in activation or inhibition of NK cells and, consequently, in death of bacillus. In addition, studies have demonstrated the influence of MICA genes in the pathogenesis of leprosy. Specifically, they may play a role in the interaction between NK cells and infected cells. Finally, pro- and anti-inflammatory cytokines have been influencing the clinical course of leprosy. Data from a wide variety of sources support the existence of genetic factors influencing the leprosy pathogenesis. These sources include twin studies, segregation analyses, family-based linkage and association studies, candidate gene association studies, and, most recently, genome-wide association studies (GWAS). The purpose of this brief review was to highlight the importance of some immune response genes and their correlation with the clinical forms of leprosy, as well as their implications for disease resistance and susceptibility.

Evolutionary patterns of killer cell Ig-like receptor genes in Old World monkeys.

Killer cell Ig-like receptors (KIRs) modulate the cytotoxic effects of Natural Killer cells. KIR genes are encoded in the Leucocyte Receptor Complex and are characterized by their high haplotypic diversity and polymorphism. The KIR system has been studied in only three species of Old World monkeys, the rhesus macaque, the cynomolgus macaque, and the sabaeus monkey, displaying a complexity rivaling that of hominids (human and apes). Here we analyzed bacterial artificial chromosome draft sequences spanning the KIR haplotype of three other Old World monkeys, the vervet monkey (Chlorocebus aethiops), the olive baboon (Papio anubis) and the colobus monkey (Colobus guereza). A total of 25 KIR gene models were identified in these species, predicted to encode receptors with 1, 2, and 3 extracellular Ig domains, all of them with long cytoplasmic domains having two putative ITIMs, although three had a positively charged residue in the transmembrane domain. Sequence and phylogenetic analyses showed that most Old World monkeys shared five classes of KIR loci: i) KIR2DL5/3DL20 in the most centromeric region, followed by ii) the single Ig domain-encoding locus KIR1D, iii) the pseudogene KIR2DP, iv) the conserved KIR2DL4, and v) the highly diversified KIR3DL/H loci in the telomeric half of the cluster. An exception to this pattern was the KIR haplotype of the colobus monkey that lacked the KIR1D, KIR2DP, and KIR2DL4 loci of the central region of the cluster. Thus, Old World monkeys display a broad spectrum of KIR haplotype variation that has been generated upon an ancestral haplotype architecture by gene duplication, gene deletion, and non-homologous recombination.

Importance of killer immunoglobulin-like receptors in allogeneic hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation is the treatment of choice for many hematologic diseases, such as multiple myeloma, bone marrow aplasia and leukemia. Human leukocyte antigen (HLA) compatibility is an important tool to prevent post-transplant complications such as graft rejection and graft-versus-host disease, but the high rates of relapse limit the survival of transplant patients. Natural Killer cells, a type of lymphocyte that is a key element in the defense against tumor cells, cells infected with viruses and intracellular microbes, have different receptors on their surfaces that regulate their cytotoxicity. Killer immunoglobulin-like receptors are the most important, interacting consistently with human leukocyte antigen class I molecules present in other cells and thus controlling the activation of natural killer cells. Several studies have shown that certain combinations of killer immunoglobulin-like receptors and human leukocyte antigens (in both donors and recipients) can affect the chances of survival of transplant patients, particularly in relation to the graft-versusleukemia effect, which may be associated to decreased relapse rates in certain groups. This review aims to shed light on the mechanisms and effects of killer immunoglobulin-like receptors - human leukocyte antigen associations and their implications following hematopoietic stem cell transplantation, and to critically analyze the results obtained by the studies presented herein.

Activating killer cell immunoglobulin-like receptor genes' association with recurrent miscarriage.

PROBLEM: Natural killer (NK) cells are regulated through NK cell receptors such as killer cell immunoglobulin-like receptors (KIRs). KIRs are suspected of being involved in the causes of recurrent miscarriage (RM) as a higher proportion of activated NK cells were observed in women with RM when compared with that in controls. The aim of this study was to investigate if KIR genes coding for receptors known to have as ligands HLA class I molecules are correlated with RM. METHOD OF STUDY: A matched case-control study was carried out in 68 south Brazilian Caucasian patient couples with RM and 68 control fertile couples. KIR genes were typed by PCR-Reverse SSO method. RESULTS: The rate of possession of an elevated number of activating KIR genes (positive for five or six activating KIR genes out of six different activating KIR genes analyzed) in RM patient women was significantly higher (P = 0.0201) when compared with that in control fertile women. These data suggest that women carrying a high content of activating KIR genes have about threefold increased probability to develop RM [OR = 2.71; 95% CI (1.23-6.01)]. CONCLUSION: Our results indicate that RM could be associated with NK cell activation mediated by a profile rich in activating KIR genes.

Killer cell immunoglobulin-like receptor gene diversity in a Southern Brazilian population from the state of Paraná.

Killer cell immunoglobulin-like receptors (KIR) are encoded by polymorphic genes and have as binding human leukocyte antigen (HLA) class I molecules. The aim of this study was to investigate the distribution of KIR genes and inhibitory KIR/HLA pairs in a population from Southern Brazil, in the state of Paraná, and to compare the results with results from other populations. The genotyping of 16 KIR genes and HLA class I alleles of 289 unrelated individuals was accomplished by reverse sequence-specific oligonucleotide Luminex (One Lambda, Inc., Canoga Park, CA). This Brazilian population demonstrated several similarities to Caucasian populations with regard to the frequency of KIR genes. Thirty-eight genotypes were defined in which the most frequent was the homozygous haplotype A (33.2%). Therefore, it was possible to define two new genotypes. Most of the individuals demonstrated at least one inhibitory KIR/HLA pair. Two pairs were the most frequent (40.4%), followed by three pairs (38.2%), one pair (14.6%), and four pairs (6.4%). The KIR2DL2/3 + HLA-C1 pair was the most frequent (79.9%) and the least frequent pair was KIR3DL2 + HLA-A3/11 (25.0%). This study demonstrated the diversity of KIR genes in a population of Paraná, as well as the characteristic pattern of Caucasians with racial admixture, which enabled the definition of two new genotypes and the identification of one individual without the inhibitory KIR/HLA pair.