Major histocompatibility complex class I-recognizing receptors are disease risk genes in rheumatoid arthritis

The Role of Killer Ig-like Receptors in Diseases from A to Z

Killer Ig-like Receptors (KIRs) regulate immune responses, maintaining the balance between activation and inhibition of the immune system. KIRs are expressed on natural killer cells and some CD8 T cells and interact with HLA class I molecules, influencing various physiological and pathological processes. KIRs' polymorphism creates a variability in immune responses among individuals. KIRs are involved in autoimmune disorders, cancer, infections, neurological diseases, and other diseases. Specific combinations of KIRs and HLA are linked to several diseases' susceptibility, progression, and outcomes. In particular, the balance between inhibitory and activating KIRs can determine how the immune system responds to pathogens and tumors. An imbalance can lead to an excessive response, contributing to autoimmune diseases, or an inadequate response, allowing immune evasion by pathogens or cancer cells. The increasing number of studies on KIRs highlights their essential role as diagnostic and prognostic biomarkers and potential therapeutic targets. This review provides a comprehensive overview of the role of KIRs in all clinical conditions and diseases, listed alphabetically, where they are analyzed.

Rheumatoid Vasculitis in Modern Era: A Case Report and Comprehensive Literature Review

Rheumatoid vasculitis (RV) is a rare extraarticular manifestation of severe seropositive rheumatoid arthritis (RA), affecting small and medium vessels and associated with significant morbidity and mortality. The incidence of RV has significantly decreased in the last three decades due to early diagnosis and better management of RA with biologics. Still, the mortality rate remains high and there are insufficient controlled studies guiding RV treatment. Here, we discussed a case of a 75-year-old male who presented with a non-healing ulcer on lateral malleolus without significant joint pain, the workup showed very high titer rheumatoid factor with erosive joint disease raising high clinical suspicion of RV. Skin biopsy was negative for histologic evidence of vasculitis. He had complete healing of the ulcer with prednisone and methotrexate (MTX). This case highlights the importance of promptly recognizing this rare entity and that a negative biopsy does not rule out RV, and appropriate treatment helps decrease morbidity and mortality.

Rheumatoid vasculitis in 2023: Changes and challenges since the biologics era

BACKGROUND

Significant changes in the epidemiology and natural history of rheumatoid vasculitis (RV) have occurred with the introduction of biological therapies such as TNF inhibitors (TNFi) and rituximab.

PURPOSE

This scoping review aims to address the key current challenges and propose updated criteria for RV. This will aid future descriptive observational studies and prospective therapeutic trials.

METHODOLOGY

The MEDLINE database was searched for eligible articles from inception through December 2022. Articles were selected based on language and publication date after 1998, corresponding to the approval of the first TNFi in rheumatic diseases.

RESULTS

Sixty articles were included in the review. The mean incidence of RV has decreased since the approval of biologic therapies in RA, from 9.1 (95% CI: 6.8-12.0) per million between 1988 and 2000 to 3.9 (95% CI: 2.3-6.2) between 2001 and 2010, probably due to significant improvement in RA severity and a decrease in smoking habits. Factors associated with an increased risk of RV include smoking at RA diagnosis, longer disease duration, severe RA, immunopositivity, and male gender (regardless of age). Homozygosity for the HLA-DRB104 shared epitope is linked to RV, while the presence of HLA-C3 is a significant predictor of vasculitis in patients without HLA-DRB104. Cutaneous (65-88%), neurologic (35-63%), and cardiac (33%) manifestations are common in RV, often associated with constitutional symptoms (70%). Histologic findings range from small vessel vasculitis to medium-sized necrotizing arteritis, but definite evidence of vasculitis is not required in the 1984 Scott and Bacon diagnostic criteria. Existing data on RV treatment are retrospective, and no formal published guidelines are currently available.

CONCLUSION

The understanding of RV pathogenesis has improved since its initial diagnostic criteria, with a wider range of clinical manifestations identified. However, a validated and updated criteria that incorporates these advances is currently lacking, impeding the development of descriptive observational studies and prospective therapeutic trials.

PRIMARY FUNDING SOURCE

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Pathogenesis of Extraarticular Manifestations in Rheumatoid Arthritis-A Comprehensive Review

Rheumatoid arthritis (RA) is among the most prevalent and debilitating autoimmune inflammatory chronic diseases. Although it is primarily characterized by destructive peripheral arthritis, it is a systemic disease, and RA-related extraarticular manifestations (EAMs) can affect almost every organ, exhibit a multitude of clinical presentations, and can even be asymptomatic. Importantly, EAMs largely contribute to the quality of life and mortality of RA patients, particularly substantially increased risk of cardiovascular disease (CVD) which is the leading cause of death in RA patients. In spite of known risk factors related to EAM development, a more in-depth understanding of its pathophysiology is lacking. Improved knowledge of EAMs and their comparison to the pathogenesis of arthritis in RA could lead to a better understanding of RA inflammation overall and its initial phases. Taking into account that RA is a disorder that has many faces and that each person experiences it and responds to treatments differently, gaining a better understanding of the connections between the joint and extra-joint manifestations could help to create new treatments and improve the overall approach to the patient.

Immunity at maternal-fetal interface: KIR/HLA (Allo)recognition

Both KIR and HLA are the most variable gene families in the human genome. The recognition of the semi-allogeneic embryo-derived trophoblasts by maternal decidual NK (dNK) cells is essential for the establishment of the functional placenta. This recognition is based on the KIR-HLA interactions and trophoblast expresses a specific HLA profile that constitutes classical polymorphic HLA-C and non-classical oligomorphic HLA-E, HLA-F, and HLA-G molecules. This review highlights some features of the KIR/HLA-C (allo)recognition by decidual NK (dNK) cells as a main immune cell population specifically enriched at maternal-fetal interface during human early pregnancy. How KIR/HLA-C axis operates in pregnancy disorders and in the context of transplacental infections is discussed as well. We summarized old and new data on dNK-cell functional plasticity, their selective expression of KIR and fetal maternal/paternal HLA-C haplotypes present. Results showed that KIR-HLA-C combinations and the corresponding axis operate differently in each pregnancy, determined by the variability of both maternal KIR haplotypes and fetus' maternal/paternal HLA-C allotype combinations. Moreover, the maturation of NK cells strongly depends on if or not HLA allotypes for certain KIR are present. We suggest that the unique KIR/HLA combinations reached in each pregnancy (normal and pathological) should be studied according to well-defined guidelines and unified methodologies to have comparable results ease to interpret and use in clinics.

Rheumatoid Arthritis and JAK-STAT Inhibitors: Prospects of Topical Delivery

Abstract:

Rheumatoid arthritis (RA) is the most common musculoskeletal disease in the world. The clinical prospects have increased tremendously since the advent of biological agents as therapy options. NSAIDs such as indomethacin, celecoxib, and etoricoxib are used often in the treatment of RA but off-target effects decreased their use. DMARDs such as methotrexate and etanercept were also effective in the treatment of RA, but tolerance to methotrexate developed in many cases. Janus kinase inhibitors (JAKi) have also gained popularity as a treatment option for rheumatoid arthritis. Tofacitinib is the foremost JAK inhibitor that is used to treat RA as an individual agent or in combination with other DMARDs. The most frequently used route of administration for JAKi is oral. Since oral formulations of JAK inhibitors have a number of health hazards, such as systemic toxicity and patient noncompliance, topical formulations of JAK inhibitors have emerged as a preferable alternative for administering JAK inhibitors. Tofacitinib delivered topically, seems to have the potential to eliminate or reduce the occurrences of negative effects when compared to tofacitinib taken orally. Given the scarcity of knowledge on the techniques for topical distribution of JAKi, more effort will be required to develop a stable topical formulation of JAKi to address the limitations of oral route. The current review looks at JAK inhibitors and the ways that have been used to generate topical formulations of them.

Autoimmunity in psoriatic arthritis: pathophysiological and clinical aspects

Psoriatic arthritis (PsA) is an underdiagnosed entity with a broad impact on the quality of life. Although the pathogenesis is largely unknown, autoimmune footprints of the inflammation in PsA have increasingly been recognized. Most of the genetic variation predisposing to PsA is mapped to the class I major histocompatibility complex (MHC) region and shared by a variety of autoimmune diseases. Polymorphisms in the genes IL12B, IL23R, IL13, TNIP1, TRAF3IP2, TYK2, and many others explain the non- HLA genetic risk with little known functional consequences. Entheseal and synovial cellular infiltrate with oligoclonal CD8+ T cells and occasional germinal centers, loss of regulatory T cell function, and specific autoantibodies such as anti-PsA peptide, anti-LL-37, and anti-ADAMTSL5 are the immunopathological findings suggestive of autoimmunity. These were supported by clinical observations of autoimmune multimorbidity and treatment response to calcineurin/mTOR and co-stimulation inhibition.

HLA Allele Prevalence in Disease-Modifying Antirheumatic Drugs-Responsive Enthesitis and/or Arthritis Not Fulfilling ASAS Criteria: Comparison with Psoriatic and Undifferentiated Spondyloarthritis

Spondyloarthritis (SpA) is a group of inflammatory rheumatic diseases characterized by common clinical features, such as inflammatory enthesitis, arthritis and/or back pain. SpA is strongly associated with human leukocyte antigen (HLA) class I allotype B27. Ankylosing spondylitis has historically been the SpA subgroup with one of the strongest, best-proven associations with HLA-B27. The remaining SpA subgroups, namely psoriatic arthritis (PsA), inflammatory bowel diseases-associated arthritis/spondylitis, reactive arthritis, and undifferentiated SpA (uSpA), have also been associated with HLA allotypes other than HLA-B27. In this retrospective study, we analyzed the association between the HLA class I and II haplotypes and the susceptibility to enthesitis and/or arthritis (E/A). Special attention was paid to E/A responding to disease-modifying antirheumatic drugs (DMARDs) not fulfilling ASAS classification criteria (ASAS⁻), as compared to ASAS⁺ forms including PsA and uSpA. The whole E/A group showed significant independent associations with HLA-A28(68), B27, Cw3, Cw12, and DQ1; taken singly, PsA was associated with HLA-B27 and DQ1, uSpA with HLA-B16(38,39) and B27, and E/A ASAS⁻ with HLA-A28(68), Cw8, and Cw12. This study identified novel risk HLA allotypes for different SpA subgroups in an Italian population. HLA typing could aid the diagnosis and treatment of E/A subgroups, including DMARDS-responsive forms not fulfilling ASAS classification criteria.

Chronic T cell receptor stimulation unmasks NK receptor signaling in peripheral T cell lymphomas via epigenetic reprogramming

Peripheral T cell lymphomas (PTCLs) represent a significant unmet medical need with dismal clinical outcomes. The T cell receptor (TCR) is emerging as a key driver of T lymphocyte transformation. However, the role of chronic TCR activation in lymphomagenesis and in lymphoma cell survival is still poorly understood. Using a mouse model, we report that chronic TCR stimulation drove T cell lymphomagenesis, whereas TCR signaling did not contribute to PTCL survival. The combination of kinome, transcriptome, and epigenome analyses of mouse PTCLs revealed a NK cell-like reprogramming of PTCL cells with expression of NK receptors (NKRs) and downstream signaling molecules such as Tyrobp and SYK. Activating NKRs were functional in PTCLs and dependent on SYK activity. In vivo blockade of NKR signaling prolonged mouse survival, demonstrating the addiction of PTCLs to NKRs and downstream SYK/mTOR activity for their survival. We studied a large collection of human primary samples and identified several PTCLs recapitulating the phenotype described in this model by their expression of SYK and the NKR, suggesting a similar mechanism of lymphomagenesis and establishing a rationale for clinical studies targeting such molecules.

Rheumatoid Arthritis Susceptibility Is Associated with the KIR2DS4-Full of Killer-Cell Immunoglobulin-Like Receptor Genes in the Lur Population of Iran

Background

The pathophysiology underlying the progression and development of autoimmune conditions, such as Rheumatoid Arthritis (RA), is a result of dysregulations of the immune system. Research has explored the genetic alterations present in RA; however, limited studies have examined the role of Killer cell Immunoglobulin-like Receptors (KIR) and Human Leukocyte Antigen (HLA) molecules in RA. Therefore, the aim of this study was to examine KIR genes, their HLA ligands, and KIR-HLA compounds in patients with RA.

Methods

In this case-control study, a total of 50 patients with RA and 100 healthy individuals were enrolled. DNA samples were evaluated using PCR with sequence specific Primers (PCR-SSP). Odds ratio (OR) with a 95% confidence interval (CI) were reported.

Results

Among the KIR genes examined, KIR2DLA (p= 0.0255, OR= 0.389, 95% CI= 0.210-0.722) and KIR2DS4-full (p< 0.0001, OR= 6.163, 95% CI= 3.174-11.968) were observed to have a statistically significant correlation with disease susceptibility to RA. As an inhibitory gene, KIR2DLA was observed to have a protective effect against RA while KIR2DS4-full as an activating gene, was found to increase risk for RA. No significant associations were found between any of the other KIR genotypes, HLA ligands, or KIR-HLA compounds examined in this study to RA susceptibility.

Conclusion

In this study of RA in the Lur population of Iran, KIR2DS4-full was observed to increase susceptibility to RA, while KIR2DL5A was found to act as a protecting factor based on both the cross Table and regression analyses. Further research should focus on repeating this study in additional populations.

Natural killer cells in inflammatory autoimmune diseases

Natural killer (NK) cells are a specialised population of innate lymphoid cells (ILCs) that help control local immune responses. Through natural cytotoxicity, production of cytokines and chemokines, and migratory capacity, NK cells play a vital immunoregulatory role in the initiation and chronicity of inflammatory and autoimmune responses. Our understanding of their functional differences and contributions in disease settings is evolving owing to new genetic and functional murine proof-of-concept studies. Here, we summarise current understanding of NK cells in several classic autoimmune disorders, particularly in rheumatoid arthritis (RA), multiple sclerosis (MS), systemic lupus erythematosus (SLE) and type 1 diabetes mellitus (T1DM), but also less understood diseases such as idiopathic inflammatory myopathies (IIMs). A better understanding of how NK cells contribute to these autoimmune disorders may pave the way for NK cell-targeted therapeutics.

CTLA4-Ig prolongs graft survival specifically in young but not old mice

Elderly organ transplant recipients have remained underrepresented in clinical trials, despite representing a rapidly growing population. Here, we assessed age-specific effects of CTLA4-Ig (cytotoxic T-lymphocyte antigen 4-Ig), a fusion protein blocking costimulatory signaling between antigen-presenting cells and T cells through CD28. Cardiac allografts in young mice (2-3 months) treated with CTLA4-Ig survived indefinitely, whereas 80% of old recipients (18 months) had lost their graft after 100 days. CTLA4-Ig was also significantly less effective in older recipients of skin transplants. CTLA4-Ig reduced CD4⁺ central memory and effector memory T cells and diminished systemic interferon-gamma levels only in young recipients. These differences corresponded to a reduced expression of CD28 on antigen-experienced CD4⁺ T cells in old mice. In support, adoptive transfer of old CD4⁺ T cells that were transfected with a lentiviral vector inducing constant expression of CD28 accelerated the rejection of allogeneic skin grafts in young RAG2^-/- recipient mice. Regulatory T cells (Tregs), in contrast, demonstrated an increased expression of CD28 with aging and CTLA4-Ig treatment in old recipients resulted in reduced frequencies, compromised proliferation, and diminished suppressive capacity of Tregs. These findings may prove to have unique clinical consequences for immunosuppression in the growing population of elderly transplant recipients.

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, p^corr = 0.02), while KIR2DL2+HLA-C1 (OR = 0.62, p^corr = 0.04) and KIR2DL3+HLA-C1 (OR = 0.48, p^corr = 0.04) were associated with a decreased risk. The pair KIR2DL3+HLA-C1 was associated with liver cirrhosis (OR = 0.40, p^corr = 0.01). The presence of five or more activating KIR variants was associated with hepatocellular carcinoma (OR = 0.53, p^corr = 0.04).

CONCLUSIONS

KIR gene content variation and combinations KIR-HLA influence the outcome of HBV 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.

Killer cell immunoglobulin-like receptors (KIR) and human leukocyte antigen-C (HLA-C) allorecognition patterns in women with endometriosis

Endometriosis shares similarities with several autoimmune diseases. The human leukocyte antigen (HLA)-C genotype is associated with several human autoimmune diseases. HLA-C is a ligand of killer cell immunoglobulin receptors (KIRs) and is an essential regulator of natural killer cell activity, which is associated with endometriosis progression. Polymorphisms in HLA-C and KIR affect the activity of NK cells and susceptibility to several diseases. Therefore, we attempted to investigate an association between HLA-C genotype and KIR polymorphism and the occurrence of endometriosis. We tested the association of certain KIR and HLA-C combinations and the development of endometriosis by characterizing both KIR and HLA-C genes in 147 women with endometriosis and 117 controls. The HLA-C genotypes and KIR polymorphisms were analyzed via DNA-based method for higher-resolution genotyping. We found that the occurrence of HLA-C*03:03*01 was increased in endometriosis than in control groups. Analysis of various KIR haplotypes revealed differences between the endometriosis and control cohorts. The number of KIR centromeric A/A haplotypes was increased in the endometriosis group than controls. Moreover, the endometriosis cohort was characterized by reduced number of KIR2DS2-positive individuals in the Han Chinese population. Our current findings suggest that the KIR and HLA-C genotypes are associated with the pathogenesis of endometriosis.

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.

HLA-C: An Accomplice in Rheumatic Diseases

Human leukocyte antigen c (HLA-C) is a polymorphic membrane protein encoded by the HLA-C gene in the class I major histocompatibility complex. HLA-C plays an essential role in protection against cancer and viruses but has also been implicated in allograft rejection, preeclampsia, and autoimmune disease. This review summarizes reports and proposed mechanisms for the accessory role of HLA-C in rheumatic diseases. Historically, contributions of HLA-C to rheumatic diseases were eclipsed by the stronger association with HLA-DRB1 alleles containing the "shared epitope" with rheumatoid arthritis. Larger genetic association studies and more powerful analytical approaches have revealed independent associations of HLA-C with rheumatic disease-associated phenotypes, including development of anticitrullinated peptide antibodies. HLA-C functions by presenting antigens to T cells and by binding activatory and inhibitory receptors on natural killer (NK) cells, but the exact mechanisms by which the HLA-C locus contributes to autoimmunity are largely undefined. Studies have suggested that HLA-C and NK cell receptor polymorphisms may predict responsiveness to pharmacotherapy. Understanding the mechanisms of the role of HLA-C in rheumatic disease could uncover therapeutic targets or guide precision pharmacologic treatments.

The association of HLA/KIR genes with non-small cell lung cancer (adenocarcinoma) in a Han Chinese population

The host immune system plays a crucial role in the surveillance, recognition and elimination of tumor cells. Recent studies found that Human lymphocyte antigen class I (HLA I) genes, Killer cell immunoglobulin-like receptor (KIR) genes and HLA/KIR combinations play a role in the defense against tumor cells. To evaluated the associations between HLA I genes, KIR genes and HLA/KIR combinations and non-small cell lung cancer (NSCLC) in a Chinese Han population, a total of 229 patients with NSCLC (adenocarcinoma) and 217 healthy individuals were studied. Our results showed that the HLA-C*08:01 allele occurred at a significantly higher frequency in the NSCLCs compared with the controls (P=0.034). The HLA haplotype frequencies bearing HLA-A, -B, and -C loci between the NSCLC and control groups were not different (P>0.05). And there were no differences in the KIR gene, genotype and haplotype frequencies between the NSCLC and control groups (P>0.05). Also, there were no differences between the HLA/KIR combinations in the KIR3D genes and HLA-A3/A11, HLA-Bw4 ligands and KIR2D genes and HLA-C1/C2 ligands between the NSCLC and control groups (P>0.05). Our results indicate that the HLA-C*08:01 allele could be a risk factor for NSCLC (adenocarcinoma) in the Chinese Han population (OR=2.395; 95% CI: 1.359-4.221).

Human leukocyte antigen (HLA)-Cw0303, HLA-Cw04, and HLA-Cw07 polymorphisms are associated with susceptibility of rheumatoid arthritis in Chinese Han patients from Southern China

OBJECTIVES

This study aimed to investigate the association between human leukocyte antigen Cw (HLA-Cw) polymorphisms and rheumatoid arthritis (RA) in Chinese Han patients in the Jiangsu area (Southern China).

MATERIALS AND METHODS

Polymerase chain reaction-sequence specific primers were used to detect HLA-Cw01-08 of 201 RA patients and 211 healthy individuals from Zhongda Hospital (China). The allele frequency distribution of HLA-Cw and genotypic differences between the two groups were analyzed.

RESULTS

The frequency of HLA-Cw0303 in patients with RA was significantly higher than that in controls, while the frequency of HLA-Cw04 was lower than that in controls (P<0.05). The gene frequency of HLA-Cw07 in anti-cyclic citrullinated peptide (anti-CCP)-negative patients was higher than that in controls (P=0.044). The frequency of HLA-Cw04 was decreased in the short duration subgroup and increased in the long duration subgroup (P<0.05). Compared to controls, the frequency of HLA-Cw0303 in patients with RA and morning stiffness was increased (P=0.004), while the frequency of HLA-Cw04 was decreased ( 0.005).

CONCLUSION

These results suggest that HLA-Cw0303 is a susceptibility gene for RA in Chinese Han patients in the Jiangsu area of southern China. The HLA-Cw04 gene may be a protective factor against RA, while HLA-Cw07 might play a protective role in the production of anti-CCP in the long-term course in patients with RA.

HLA and killer cell immunoglobulin-like receptor (KIRs) genotyping in patients with acute ischemic stroke

INTRODUCTION

In humans, a major component of natural killer (NK) and T cell target recognition depends on the surveillance of human leukocyte antigen (HLA) class I molecules by killer immunoglobulin-like receptors (KIRs).

AIMS

To implement the knowledge about the immunological genetic background of acute ischemic stroke susceptibility in relation to the frequency of the KIR genes and HLA alleles.

METHODS

Subjects with acute ischemic stroke and subjects without stroke were genotyped for the presence of KIR genes and of the three major KIR ligand groups, HLA-C1, HLA-C2, and HLA-Bw4, both HLA-B and HLA-A loci.

RESULTS

Between November 2013 and February 2016, consecutive patients with acute ischemic stroke were recruited. As healthy controls, we enrolled subjects without acute ischemic stroke. Subjects with acute ischemic stroke in comparison with controls showed a higher frequency of 2DL3, 2DL5B, 2DS2, and 2DS4 KIR genes and a lower frequency of HLA-B-Bw4I alleles. Subjects without acute ischemic stroke showed a higher frequency of interaction between KIR 2DS2 and HLAC2. We also observed a higher frequency of 2DL3 and 2 DL4 KIR genes in subjects with atherosclerotic (LAAS) subtype. Multiple logistic regression analysis showed a protective effect towards stroke of HLA-B-Bw4I and interaction between KIR 2DL2 and HLAC1 and 2DS2-HLAC2 and a detrimental effect of 2DL2-HLA-C1_A interactions.

CONCLUSION

Our findings of a higher frequency of activating KIR genes seem to be consistent with findings previously reported patients with coronary syndrome. This higher frequency of "proinflammatory" genes in subjects with ischemic stroke could also explain the immunoinflammatory activation of the acute phase of stroke.

Human Natural Killer Receptors, Co-Receptors, and Their Ligands

In the last 20 years, the study of human natural killer (NK) cells has moved from the first molecular characterizations of very few receptor molecules to the identification of a plethora of receptors displaying surprisingly divergent functions. We have contributed to the description of inhibitory receptors and their signaling pathways, important in fine regulation in many cell types, but unknown until their discovery in the NK cells. Inhibitory function is central to regulating NK-mediated cytolysis, with different molecular structures evolving during speciation to assure its persistence. More recently, it has become possible to characterize the NK triggering receptors mediating natural cytotoxicity, unveiling the existence of a network of cellular interactions between effectors of both natural and adaptive immunity. This unit reviews the contemporary history of molecular studies of receptors and ligands involved in NK cell function, characterizing the ligands of the triggering receptor and the mechanisms for finely regulating their expression in pathogen-infected or tumor cells. © 2018 by John Wiley & Sons, Inc.

Diversity and association of HLA/KIR receptors with type 2 diabetes in South India

The present study was undertaken to delineate the association(s) of KIR-HLA combination in South Indian Type 2 diabetes mellitus (T2DM) patients. The T2DM patients (n = 343) and healthy controls (n = 309) were genotyped for KIR/HLA ligands by PCR-SSP method. The increased frequency of activatory KIR (aKIR) 2DS2 (OR = 1.91; p < 2.91 × 10^-4 ) was observed in patients suggesting a susceptible association. The frequencies of iKIR 2DL2 (OR = 0.38; p < 1.55 × 10^-5 ) and aKIRs 2DS1 (OR = 0.60; p < 0.001) and 3DS1 (OR = 0.52; p < 5.83 × 10^-5 ) were decreased in patients suggesting protective associations. The C1/C2 combinatorial analysis has revealed an increased frequency of C1⁺ /C2^- in T2DM patients (OR = 1.62; p < 0.014). The KIR "AB" genotype (OR = 2.41; p < 3.87 × 10^-5 ) was observed to be higher in patients. However, the "BB" genotype (OR = 0.32; p < 4.71 × 10^-7 ) was increased in controls. The KIR motifs, "Tel-B/B" (OR = 1.84; p < 0.007), were observed higher among patients. However, the frequency of "Tel-A/B" motif genotype was decreased in patients (OR = 0.56; p < 3.13 × 10^-4 ). The iKIR/HLA combinations such as 2DL2/3 +C1 and 3DL2+A3/A11 were increased in patients (OR = 3.90; p < 7.5 × 10^-5 ) suggesting susceptible associations. On the contrary, the aKIR+HLA combinations such as 2DS2+C1, 2DS1+C2 and 3DS1+Bw4 were less frequent in patients (OR = 0.32; p < 4.2 × 10^-4 ) suggesting protective associations. Thus, the present study clearly establishes the positive and negative associations of different KIR-HLA receptor combinations with T2DM in South India.

Association study between KIR polymorphisms and rheumatoid arthritis disease: an updated meta-analysis

Background

Currently published studies investigating association between the killer cell immunoglobulin-like receptor (KIR) gene polymorphisms and rheumatoid arthritis (RA) reported inconsistent and contradictory results. Hence, we aim to carry out this comprehensive meta-analysis of all eligible studies meeting the inclusion criteria to achieve precise and comprehensive relationships between genetic variations in KIR gene cluster and risk of RA.

Methods

Databases of Medline/PubMed and Scopus were searched to investigate case-control studies prior to May 2018. The associations between KIR gene polymorphisms and RA susceptibility were analyzed by computing the odds ratio (OR) and 95% confidence interval (95% CI) for each study.

Results

A total of 11 comparative case-control studies involving 1847 RA patients and 2409 healthy individuals were included in this meta-analysis. Four significant associations of 2DL3 (OR = 0.591, 95% CI = 0.351–0.994; P = 0.047), 2DL5 (OR = 0.716, 95% CI = 0.601–0.853; P < 0.001), 2DS5 (OR = 0.623, 95% CI = 0.393–0.988; P = 0.045), and 3DL3 (OR = 0.324, 95% CI = 0.129–0.814; P = 0.016) genes with decreased RA risk were discovered in this meta-analysis. Although, other KIR receptors including 2DL1, 2DL2, 2DL4, 3DL1, 3DL2, 3DS1, 2DS1-2DS4, and two pseudo gens of 2DP1 and 3DP1 displayed no significant association with predisposition to RA.

Conclusions

These findings provide reliable evidence that 2DL3, 2DL5, 3DL3, and 2DS5 might have a potential protective role for RA.

Rheumatoid Vasculitis: A Diminishing Yet Devastating Menace

PURPOSE OF REVIEW

Rheumatoid vasculitis (RV) is an unusual complication of long-standing rheumatoid arthritis, which is characterized by the development of necrotizing or leukocytoclastic vasculitis involving small or medium-sized vessels. In this review, we aim to provide an update on the epidemiology, pathogenesis, clinical presentation, and management of this challenging extra-articular manifestation.

RECENT FINDINGS

RV is heterogenous in its clinical presentation depending on the organ and size of blood vessels involved. The most common organs involved are the skin and peripheral nerve. Based on recent population studies, the incidence has significantly decreased with early recognition and the advent of immunosuppressive drugs and biologics; however, the mortality rates remain high. RV remains a serious extra-articular manifestation of RA that needs to be promptly recognized and treated. No consensus is available on treatment, given the ongoing debate of whether the biologics can trigger or treat RV.

HLA-C1 ligands are associated with increased susceptibility to systemic lupus erythematosus

Recently, the role of killer cell immunoglobulin-like receptor (KIR) in autoimmune diseases has received increasing attention. The present study was undertaken to determine the association of KIR genes and the human leukocytes antigen (HLA) ligands with Systemic Lupus Erythematosus (SLE) and accompanying oxidative stress. Presence or absence of 17 KIR and 5 HLA loci was performed using the polymerase chain reaction-sequence specific primer (PCR-SSP) method by case-control study. A total of 45 SLE patients, and 60 healthy controls, all of Sicilian descent, were enrolled. Plasma values of the anti-oxidant molecule Taurine were determined in all subjects by capillary electrophoresis UV detection. The carrier frequency of the KIR2DS2 gene was significantly increased in SLE patients compared to healthy controls (73.3 versus 45.0%; OR = 3.36; 95% CI = 1.46-7.74; p = .005) suggesting a role of KIR2DS2 gene in the susceptibility to disease. We also observed a strong positive association between the presence of HLA-C1 ligands group and the disease (82.2% in SLE patients versus 41.7% in controls; OR = 6.47, 95% CI = 2.58-16.26; p < .0001). Stepwise logistic regression analysis supported the effect of the HLA-C1 ligands in SLE patients (OR = 7.06, 95% CI = 0.07-2.19; p = .002), while the KIR genes were no longer significant. Interestingly, we found that SLE patients HLA-C1 positive showed significantly decreased plasma levels of antioxidant activity marker Taurine (69.38 ± 28.49 μmol/L) compared to SLE patients HLA-C1 negative (108.37 ± 86.09 μmol/L) (p = .03). In conclusion, HLA-C1 ligands group was significantly associated with an increased risk of SLE as well as an increased oxidative stress status overall in SLE patients.

Association between KIR gene polymorphisms and type 1 diabetes mellitus (T1DM) susceptibility: A PRISMA-compliant meta-analysis

BACKGROUND

Type 1 diabetes mellitus (T1DM) is a T-cell mediated autoimmune disease with a complex genetic and immunological background. Evidence suggests that killer cell immunoglobulin-like receptor (KIR) genes are associated with T1DM, but the results are inconsistent. Here, we conducted a meta-analysis to comprehensively evaluate the effect of KIR genes on the risk of T1DM.

METHODS

The PubMed, Web of Science, the Chinese Biomedical Database, and Chinese National Knowledge Infrastructure databases were systematically searched to select studies on the association between KIR polymorphisms and T1DM. The quality of each study was scoring in term of the Newcastle-Ottawa Scale. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of this association. Subgroup analysis stratified by ethnicity was also conducted. Funnel plot and Egger test were conducted to assess the publication bias.

RESULTS

A total of 13 independent case-control studies comprising 2076 T1DM cases and 1967 controls were included in this meta-analysis. We found a negative association between the KIR2DL1 polymorphism and susceptibility to T1DM in the overall population (OR = 0.71, 95%CI = 0.51-0.98, P = .038), but not in ethnic-specific analysis. Additionally, a negative association between the KIR2DS1 polymorphism and susceptibility to T1DM was found in the Asians (OR = 0.76, 95%CI = 0.63-0.92, P = .004), but not in the Caucasians. However, the associations could not withstand Bonferroni correction. Conversely, no association between the other KIRs genes (KIR2DL2, KIR2DL3, KIR2DL4, KIR2DL5, KIR2DS2, KIR2DS3, KIR2DS4, KIR2DS5, KIR3DL1, KIR3DL2, KIR3DL3, and KIR3DS1) and T1DM susceptibility was found in overall and subgroup ethnicity. No publication bias was detected in all comparisons.

CONCLUSIONS

In summary, this meta-analysis suggested that the KIR2DL1 and 2DS1 polymorphism might be a potential protective factor for T1DM in the specific ethnicity. Further subtle design studies with more sample size are still needed for a definitive conclusion.

Association of killer cell immunoglobulin-like receptor (KIR) genes and their HLA ligands with susceptibility to Behçet's‎ disease

OBJECTIVES

Behçet's disease (BD) is a systemic inflammatory disorder with remissions and exacerbations. It is thought that defects in the natural killer (NK) cell repertoire may be involved in BD through killer cell immunoglobulin-like receptors (KIRs). This study aimed to evaluate KIR and HLA genes, their interactions in BD patients, and their associations with clinical manifestations.

METHOD

The presence or absence of KIR and HLA alleles and genotypes was analysed by polymerase chain reaction sequence-specific primer on genomic DNA of 397 BD patients and 300 healthy controls.

RESULTS

None of the KIR genes showed significant effects on BD susceptibility. HLA-C1^Asn80 showed a protective effect against BD, whereas HLA-C2^Lys80, HLA-B-Bw4^Ile80, HLA-B5, and HLA-B51 were associated with a susceptibility risk for BD. In the combination of KIR and HLA genes, the frequencies of HLA genotypes no. 2, 3, 5, and 8, and inhibitory KIR no. 4 were significantly higher in patients than in controls. The frequencies of KIR genotype no. 3 and HLA genotypes no. 1, 4, 6, 7, and 9 were significantly lower in patients than in controls. There were many associations between KIR and HLA genes with clinical features of BD.

CONCLUSION

Differences in the frequency of HLA genes, KIR-HLA interactions, and genotypes between BD and healthy controls and their associations with clinical manifestations indicate that NK cells are involved in BD pathogenesis. The observed differences indicated an NK cell activity imbalance in BD patients, and suggest a role of the KIR-HLA repertoire in the development of BD.

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.

Cytotoxic lymphocytes and atherosclerosis: significance, mechanisms and therapeutic challenges

Cytotoxic lymphocytes encompass natural killer lymphocytes (cells) and cytotoxic T cells that include CD8+ T cells, natural killer (NK) T cells, γ, δ (γδ)-T cells and human CD4 + CD28- T cells. These cells play critical roles in inflammatory diseases and in controlling cancers and infections. Cytotoxic lymphocytes can be activated via a number of mechanisms that may involve dendritic cells, macrophages, cytokines or surface proteins on stressed cells. Upon activation, they secrete pro-inflammatory cytokines as well as anti-inflammatory cytokines, chemokines and cytotoxins to promote inflammation and the development of atherosclerotic lesions including vulnerable lesions, which are strongly implicated in myocardial infarctions and strokes. Here, we review the mechanisms that activate and regulate cytotoxic lymphocyte activity, including activating and inhibitory receptors, cytokines, chemokine receptors-chemokine systems utilized to home to inflamed lesions and cytotoxins and cytokines through which they affect other cells within lesions. We also examine their roles in human and mouse models of atherosclerosis and the mechanisms by which they exert their pathogenic effects. Finally, we discuss strategies for therapeutically targeting these cells to prevent the development of atherosclerotic lesions and vulnerable plaques and the challenge of developing highly targeted therapies that only minimally affect the body's immune system, avoiding the complications, such as increased susceptibility to infections, which are currently associated with many immunotherapies for autoimmune diseases.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

KIR2DL2 and KIR2DS2 as genetic markers to the methotrexate response in rheumatoid arthritis patients

CONTEXT

Disease Modifying Anti-Rheumatic Drugs (DMARDs) are aimed to interfere with rheumatoid arthritis (RA) progression and reduce the joint damage; however, not all patients respond alike. Killer-cell immunoglobulin-like receptors (KIR) and their ligands, human leucocyte antigen class I (HLA-I), have been associated with RA pathology; therefore, KIR and HLA genes may influence the treatment response.

MATERIALS AND METHODS

We evaluated the association of KIR genotype and their ligands HLA-C genes with the response to DMARDs in RA patients. We included 69 patients diagnosed with RA and 82 healthy individuals as the reference group. KIR and HLA-C genotyping was performed using SSP-PCR. RA patients were assessed at baseline and under treatment at 6 and 12 months; subsequently classified as responders and non-responders in each time period. We evaluated the association between DMARD response and genes using statistical analysis by using Fisher exact test with Bonferroni correction; results were regarded as statistically significant at p < 0.05.

RESULTS

Significant difference was observed in gene frequencies of patients and the reference group, KIR2DL2 was associated with RA (p = 0.031, OR = 2.119). We also observed an association between KIR2DS2 and the response to methotrexate (MTX), moreover, the combination KIR2DL2+/KIR2DS2+ was more frequent in responders to MTX (p = 0.043).

DISCUSSION AND CONCLUSIONS

In our results, responders and non-responders to DMARDs showed KIR2DS2 and KIR2DL2 different gene frequencies, therefore, these genes could be used as response predictors to DMARDs treatment. Thus, these genes were also associated with disease severity, as well as the treatment response possibly by the immunoregulatory function of NK cells.

Unusual CD4+CD28- T Cells and Their Pathogenic Role in Chronic Inflammatory Disorders

CD28 is a primary co-stimulatory receptor that is essential for successful T cell activation, proliferation, and survival. While ubiquitously expressed on naive T cells, the level of CD28 expression on memory T cells is largely dependent on the T-cell differentiation stage in humans. Expansion of circulating T cells lacking CD28 was originally considered a hallmark of age-associated immunological changes in humans, with a progressive loss of CD28 following replicative senescence with advancing age. However, an increasing body of evidence has revealed that there is a significant age-inappropriate expansion of CD4⁺CD28⁻ T cells in patients with a variety of chronic inflammatory diseases, suggesting that these cells play a role in their pathogenesis. In fact, expanded CD4⁺CD28⁻ T cells can produce large amounts of proinflammatory cytokines such as IFN-γ and TNF-α and also have cytotoxic potential, which may cause tissue damage and development of pathogenesis in many inflammatory disorders. Here we review the characteristics of CD4⁺CD28⁻ T cells as well as the recent advances highlighting the contribution of these cells to several disease conditions.

Association of NKG2D gene variants with susceptibility and severity of rheumatoid arthritis

NKG2D (KLRK1) is a C-type lectin receptor present on natural killer (NK) cells, γδ, CD8⁺ and CD4⁺ T cells. Upon ligand binding, NKG2D mediates activatory and co-stimulatory signals to NK cells and activated CD4⁺ T cells, respectively. Polymorphisms in NKG2D predispose to infectious diseases, cancer, transplantation and autoimmune disorders. We studied the influence of this NK receptor polymorphism on predisposition to and modification of the disease phenotype in patients with rheumatoid arthritis (RA). Eight different single nucleotide polymorphisms (SNP) in the NKG2 gene were genotyped in 236 patients with RA and 187 controls using Taqman 5' nuclease assays. NKG2D genotype/allele frequency did not differ between patients and controls. Subgroup analysis showed that the frequency of A allele of NKG2D9 and T allele of NKG2D10 was significantly higher in patients with deformities (a marker of severe disease) [11 versus 5%, Pc = 0·03, odds ratio (OR) = 2·44, 95% confidence interval (CI) = 1·09-5·98 and 10 versus 4%, Pc = 0·04, OR = 2·45, 95% CI = 1·05-6·39, respectively], while the frequency of alleles G of NKG2D9 and A of NKG2D10 was greater in patients without deformities (Pc = 0·03, OR = 0·41, 95% CI = 0·17-0·91 and Pc = 0·04, OR = 0·41, 95% CI = 0·16-0·96). Similar trends of association were observed with deforming phenotype of RA in female patients and deforming young onset RA subgroups. Haplotype analysis revealed that the frequency of haplotype G-C-A-G-A-T-C-C was higher in patients than in controls (12 versus 8%, P = 0·04, OR = 1·61, 95% CI = 1·01-2·55), suggesting that it may predispose to RA. Our study suggests that the NKG2D gene polymorphisms may modify the risk of development and severity of RA.

Exploiting Gene-Expression Deconvolution to Probe the Genetics of the Immune System

Sequence variation can affect the physiological state of the immune system. Major experimental efforts targeted at understanding the genetic control of the abundance of immune cell subpopulations. However, these studies are typically focused on a limited number of immune cell types, mainly due to the use of relatively low throughput cell-sorting technologies. Here we present an algorithm that can reveal the genetic basis of inter-individual variation in the abundance of immune cell types using only gene expression and genotyping measurements as input. Our algorithm predicts the abundance of immune cell subpopulations based on the RNA levels of informative marker genes within a complex tissue, and then provides the genetic control on these predicted immune traits as output. A key feature of the approach is the integration of predictions from various sets of marker genes and refinement of these sets to avoid spurious signals. Our evaluation of both synthetic and real biological data shows the significant benefits of the new approach. Our method, VoCAL, is implemented in the freely available R package ComICS.

Quantitative trait locus (QTL) studies have identified a plethora of genetic variants that lead to inter-individual variation in the abundance of immune cell subpopulations, both in normal and disease states. Cell sorting is an effective method of monitoring immune cell type quantities; however, owing to the large number of possible immune cell subsets, it can be difficult to apply this method to each cell type over multiple individuals. Recent QTL studies dealt with this difficulty by focusing on an a priori selection of one or a few cell subsets. Here we introduce VoCAL, a deconvolution-based method that utilizes transcriptome data to infer the quantities of immune cell types, and then uses these quantitative traits to uncover the underlying DNA loci. Our results in synthetic data and lung cohorts show that the VoCAL method outperforms other alternatives in revealing the genetic basis of immune physiology.

The early onset of type 1 autoimmune hepatitis has a strong genetic influence: role of HLA and KIR genes

We have previously reported a strong association between HLA-DRB1*1301 and type 1 pediatric autoimmune hepatitis (PAH) and between HLA-DR*0405 and adult autoimmune hepatitis (AAH). Because human killer cell immunoglobulin-like receptors are known to be associated with susceptibility to autoimmune diseases, we investigated the frequencies of HLA-A, B, C, DRB1 and KIR genes in 144 type 1 PAH and 86 AAH patients, which were compared with 273 healthy controls. We demonstrated in PAH the increased frequency of the functional form of KIR2DS4-Full Length (KIR2DS4-FL), which in combination with HLA-DRB1*1301 revealed a strong synergistic effect (odds ratio=36.5). PAH-KIR2DS4-FL+ subjects have shown an increased frequency of their putative HLA-C*02, 04 and 06 ligands. KIR analysis of PAH also revealed a decreased frequency of KIR2DL2 gene and its ligand. In contrast, AAH cases have shown a weaker increased frequency of KIR2DS4-FL, a lack of synergistic effect with HLA class II antigens and a moderate association with HLA-DRB1*0405. Of note, we demonstrated that liver T cells have a unique pattern of KIR expression. These results show a KIR gene involved in autoimmune hepatitis and suggest a stronger genetic influence for the early onset type I autoimmune hepatitis.

Killer immunoglobulin receptor genes and their HLA-C ligand are associated with Type 1 diabetes in an Eastern Indian population

AIM

Killer immunoglobulin-like receptors (KIRs) and their interaction with HLA class I ligands have been shown to be associated with Type 1 diabetes mellitus. The aim of our study was to investigate the influence of KIR genes and their HLA-C ligands for susceptibility to Type 1 diabetes in patients from Eastern India.

METHODS

A total of 135 patients with Type 1 diabetes and 98 healthy subjects from Eastern India were typed for KIR genes and HLA-C ligands using PCR-based genotyping. The frequencies of these genes were compared between patients and controls.

RESULTS

Comparison of KIR genes between Type 1 diabetes patients and healthy subjects revealed significantly different frequencies of KIRs 2DL2 and 2DS4. The presence of HLA-C1 was negatively associated with disease. The presence of both HLA-C1 and -C2 showed a negative association with Type 1 diabetes, whereas the absence of C1 and presence of C2 was positively associated with disease. Stratification analysis of HLA-C ligands and KIRs showed significant associations between Type 1 diabetes and 2DL2+/C1-, 2DL2-/C1+, 2DL3+/C1+, 2DL3+/C1- and 2DS2+/C1-.

CONCLUSIONS

Our results suggest that the interaction of KIRs with HLA-C ligands are significant and certain combinations contribute to susceptibility to and protection against Type 1 diabetes.

Association of Killer Cell Immunoglobulin- Like Receptor Genes in Iranian Patients with Rheumatoid Arthritis

Objectives

Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by persistent synovitis, ultimately leading to cartilage and bone degeneration. Natural Killer cells and CD28 null T-cells are suspected as role players in RA pathogenesis. These cells are similar in feature and function, as they both exert their cytotoxic effect via Killer Cell Immunoglobulin- Like Receptors (KIR) on their surface. KIR genes have either an inhibitory or activating effect depending on their intracytoplasmic structure. Herein we genotyped 16 KIR genes, 3 pseudo genes and 6 HLA class І genes as their corresponding ligands in RA patients and control subjects.

Methods

In this case-control study, KIR and HLA genes were genotyped in 400 RA patients and 372 matched healthy controls using sequence-specific primers (SSP-PCR). Differences in the frequency of genes and haplotypes were determined by χ² test.

Results

KIR2DL2, 2DL5a, 2DL5b and activating KIR: KIR2DS5 and 3DS1 were all protective against RA. KIR2DL5 removal from a full Inhibitory KIR haplotype converted the mild protection (OR = 0.56) to a powerful predisposition to RA (OR = 16.47). Inhibitory haplotype No. 7 comprising KIR2DL5 in the absence of KIR2DL1 and KIR2DL3 confers a 14-fold protective effect against RA.

Conclusion

Individuals carrying the inhibitory KIR haplotype No. 6 have a high potential risk for developing RA.

Killer Cell Immunoglobulin-Like Receptor (KIR) Genotype Distribution in Familial Mediterranean Fever (FMF) Patients

BACKGROUND Familial Mediterranean fever (FMF) is an autosomal recessive autoinflammatory disease predominantly affecting Mediterranean populations. The gene associated with FMF is the MEFV gene, which encodes for a protein called pyrin. Mutations of pyrin lead to uncontrolled attacks of inflammation, and subclinical inflammation continues during attack-free intervals. Killer cell immunoglobulin-like receptor (KIR) genes encode HLA class I receptors expressed by NK cells. The aim this study was to look for immunogenetic determinants in the pathogenesis of FMF and find out if KIR are related to susceptibility to disease or complications like renal amyloidosis. MATERIAL AND METHODS One hundred and five patients with FMF and 100 healthy individuals were involved in the study. Isolated DNA from peripheral blood was amplified by sequence specific PCR probes and analyzed by Luminex for KIR genotypes. Fisher Exact test was used to evaluate the variation of KIR gene distribution. RESULTS All patients and healthy controls expressed the framework genes. An activator KIR gene, KIR2DS2, was significantly more frequent in FMF patients (p=0.036). Renal amyloidosis and presence of arthritis were not associated with KIR genes and genotype. KIR3DL1 gene was more common in patients with high serum CRP (p=0.016). CONCLUSIONS According to our findings, we suggest that presence of KIR2DS2, which is an activator gene for NK cell functions, might be related to the autoinflammation in FMF. The potential effect of KIR genes on amyloidosis and other clinical features requires studies with larger sample sizes.

Molecular studies on ancient M. tuberculosis and M. leprae: methods of pathogen and host DNA analysis

Humans have evolved alongside infectious diseases for millennia. Despite the efforts to reduce their incidence, infectious diseases still pose a tremendous threat to the world population. Fast development of molecular techniques and increasing risk of new epidemics have resulted in several studies that look to the past in order to investigate the origin and evolution of infectious diseases. Tuberculosis and leprosy have become frequent targets of such studies, owing to the persistence of their molecular biomarkers in ancient material and the characteristic skeletal lesions each disease may cause. This review examines the molecular methods used to screen for the presence of M. tuberculosis and M. leprae ancient DNA (aDNA) and their differentiation in ancient human remains. Examples of recent studies, mainly from Europe, that employ the newest techniques of molecular analysis are also described. Moreover, we present a specific approach based on assessing the likely immunological profile of historic populations, in order to further elucidate the influence of M. tuberculosis and M. leprae on historical human populations.

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.

Association between KIR gene polymorphisms and rheumatoid arthritis susceptibility: A meta-analysis

OBJECTIVES

The results of studies on association between KIR (killer cell immunoglobulin-like receptors) polymorphisms and susceptibility to RA (rheumatoid arthritis) are inconsistent. To comprehensively evaluate the effect of KIR polymorphisms on the risk of RA, a meta-analysis was carried out.

METHODS

The Web of Science, PubMed, the Chinese Biomedical Database (CBM) and Chinese National Knowledge Infrastructure (CNKI) databases were systematically searched to select studies on the association between KIR polymorphisms and RA. The odds ratio (OR) with 95% confidence interval (95%CI) was obtained.

RESULTS

Nine qualified case-control studies were included in this meta-analysis. The results showed there were two positive associations of 2DL1, 2DS1 (OR2DL1=2.20, 95%CI=1.20-4.01, Praw=0.01, PFDR=0.03; OR2DS1=1.84, 95%CI=1.19-2.85, Praw=0.006, PFDR=0.018) and one negative association of 2DL3 (OR2DL3=0.42, 95%CI=0.22-0.79, Praw=0.006, PFDR=0.018) with susceptibility to RA in East Asians, but not in Caucasians.

CONCLUSION

The current meta-analysis provides evidence that 2DL3 might be a potential protective factor and 2DL1, 2DS1 might be risk factors for RA in East Asians but not in Caucasians.

Association of killer cell immunoglobulin-like receptor and human leucocyte antigen-Cw gene combinations with systemic lupus erythematosus

Killer cell immunoglobulin-like receptors (KIRs) are a diverse family of activating and inhibitory receptors expressed on natural killer (NK) cells and T cells, the genes of which show extreme polymorphism. Some KIRs bind to human leucocyte antigen (HLA) class I subgroups, and genetic interactions between KIR genes and their ligand HLA have been shown to be associated with several autoimmune diseases. The present study aimed to investigate whether the combinations of KIR genes and HLA-Cw ligands associate with the susceptibility of systemic lupus erythematosus (SLE). Polymerase chain reaction using sequence-specific primers was used to determine the genotypes of KIR genes and HLA-Cw alleles. We found that the frequencies of HLA-Cw07 were statistically significantly higher in the patient group than those in the control group (P = 0·009). KIR2DS1(+) HLA(-) Cw(Lys) was more common in subjects with SLE compared to control subjects (P = 0·015). In addition, the frequency of KIR2DS1 was increased in SLE when KIR2DL1/HLA-Cw are absent, and the difference was significant (P = 0·001). KIR genotype and HLA ligand interaction may potentially influence the threshold for NK (and/or T) cell activation mediated through activating receptors, thereby contributing to the pathogenesis of SLE.

Killer cell immunoglobulin receptor profile on CD4(+) CD28(-) T cells and their pathogenic role in non-dialysis-dependent and dialysis-dependent chronic kidney disease patients

There is a progressive increase in cardiovascular disease with declining renal function, unexplained by traditional risk factors. A CD4(+) T-cell subpopulation (CD4(+)  CD28(-) ), activated by human heat-shock protein 60 (hHSP 60), expands in patients with acute coronary syndrome and is associated with vascular damage. These cells exhibit cytotoxicity via expression of activating killer cell-immunoglobulin-like receptor KIR2DS2, mainly in the absence of inhibitory KIR2DL3. We investigated expansion of these cells and the pathogenic role of the KIR in non-dialysis-dependent chronic kidney disease (NDD-CKD) and end-stage haemodialysis-dependent renal disease (HD-ESRD) patients. CD4(+)  CD28(-) cells were present in 27% of the NDD-CKD and HD-ESRD patients (8-11% and 10-11% of CD4(+) compartment, respectively). CD4(+)  CD28(-) cells were phenotyped for KIR and DAP12 expression. Cytotoxicity was assessed by perforin and pro-inflammatory function by interferon-γ expression on CD4(+)  CD28(-) clones (NDD-CKD n = 97, HD-ESRD n = 262). Thirty-four per cent of the CD4(+)  CD28(-) cells from NDD-CKD expressed KIR2DS2 compared with 56% in HD-ESRD patients (P = 0·03). However, 20% of clones expressed KIR2DL3 in NDD-CKD compared with 7% in HD-ESRD patients (P = 0·004). DAP12 expression in CD28(-)  2DS2(+) clones was more prevalent in HD-ESRD than NDD-CKD (92% versus 60%; P < 0·001). Only 2DS2(+)  2DL3(-)  DAP12(+) clones were cytotoxic in response to hHSP 60. CD4(+)  CD28(-) cells exhibited increased KIR2DS2, reduced KIR2DL3 and increased DAP12 expression in HD-ESRD compared with NDD-CKD patients. These findings suggest a gradual loss of expression, functionality and protective role of inhibitory KIR2DL3 as well as increased cytotoxic potential of CD4(+)  C28(-) cells with progressive renal impairment. Clonal expansion of these T cells may contribute to heightened cardiovascular events in HD-ESRD.

Cell mediators of autoimmune hepatitis and their therapeutic implications

Autoimmune hepatitis is associated with interactive cell populations of the innate and adaptive immune systems, and these populations are amenable to therapeutic manipulation. The goals of this review are to describe the key cell populations implicated in autoimmune hepatitis and to identify investigational opportunities to develop cell-directed therapies for this disease. Studies cited in PubMed from 1972 to 2014 for autoimmune hepatitis, innate and adaptive immune systems, and therapeutic interventions were examined. Dendritic cells can promote immune tolerance to self-antigens, present neo-antigens that enhance the immune response, and expand the regulatory T cell population. Natural killer cells can secrete pro-inflammatory and anti-inflammatory cytokines and modulate the activity of dendritic cells and antigen-specific T lymphocytes. T helper 2 lymphocytes can inhibit the cytotoxic activities of T helper 1 lymphocytes and limit the expansion of T helper 17 lymphocytes. T helper 17 lymphocytes can promote inflammatory activity, and they can also up-regulate genes that protect against oxidative stress and hepatocyte apoptosis. Natural killer T cells can expand the regulatory T cell population; gamma delta lymphocytes can secrete interleukin-10, stimulate hepatic regeneration, and induce the apoptosis of hepatic stellate cells; and antigen-specific regulatory T cells can dampen immune cell proliferation and function. Pharmacological agents, neutralizing antibodies, and especially the adoptive transfer of antigen-specific regulatory T cells that have been freshly generated ex vivo are evolving as management strategies. The cells within the innate and adaptive immune systems are key contributors to the occurrence of autoimmune hepatitis, and they are attractive therapeutic targets.

The role of KIR2DL3/HLA-C*0802 in Brazilian patients with rheumatoid vasculitis

OBJECTIVES

Rheumatoid arthritis is a polygenically controlled systemic autoimmune disease. Rheumatoid vasculitis is an important extra-articular phenotype of rheumatoid arthritis that can result in deep cutaneous ulcers. The objective of this study was to establish a correlation between the frequency of major histocompatibility complex class I/II alleles and killer immunoglobulin-like receptor genotypes in patients with cutaneous rheumatoid vasculitis.

METHODS

Using the Scott & Bacon 1984 criteria to diagnose rheumatoid vasculitis and after excluding any other causes such as diabetes, atherosclerosis, adverse drug reactions, infection, and smoking, patients who met the criteria were selected. All of the selected rheumatoid vasculitis patients presented deep cutaneous ulcers. Identification of the major histocompatibility complex class I/II and killer immunoglobulin-like receptor genotypes was performed by polymerase chain reaction assays of samples collected from the 23 rheumatoid vasculitis patients as well as from 80 controls (40 non-rheumatoid vasculitis RA control patients and 40 healthy volunteers).

RESULTS

An association between the presence of the HLA-DRB1*1402 and HLA-DRB1*0101 alleles and cutaneous lesions in rheumatoid vasculitis patients and a correlation between the inhibitor KIR2DL3 and the HLA-C*0802 ligand in rheumatoid vasculitis patients were found.

CONCLUSION

An association was found between the presence of the HLA-DRB1*1402 and HLA-DRB1*0101 alleles and the development of cutaneous lesions in rheumatoid vasculitis patients. Additionally, the HLA-C*0802 ligand protects these individuals from developing cutaneous lesions.