Study of KIR genes in Lebanese patients with tuberculosis

Systematic review and meta-analytic findings on the association between killer-cell immunoglobulin-like receptor genes and susceptibility to pulmonary tuberculosis

Several studies have evaluated the association between killer-cell immunoglobulin-like receptors (KIR) genes and susceptibility risk to tuberculosis (TB) infection. Nonetheless, their outcomes have not been conclusive and consistent. Here we implemented a systematic review and meta-analysis of KIR genes association to susceptibility risk of pulmonary TB (PTB) infection to attain a clear understanding of the involvement of these genes in susceptibility to PTB infection. A systematic search was conducted in the MEDLINE/PubMed and Scopus databases to find case-control studies published before November 2020. Pooled odds ratio (OR) and 95% confidence interval (95% CI) were calculated to determine the association between KIR genes and risk of PTB infection. After comprehensive searching and implementing the inclusion and exclusion criteria, 10 case-control studies were included in the meta-analysis. Four KIR genes were found to have significant positive association with PTB susceptibility risk of infection, including 2DL3 (OR = 1.454, 95% CI = 1.157-1.827; P = 0.001), 2DS1 (OR = 1.481, 95% CI = 1.334-1.837; P < 0.001), 2DS4 (OR = 1.782, 95% CI = 1.273-2.495; P = 0.001) and 3DL1 (OR = 1.726, 95% CI = 1.277-2.333; P < 0.001). However, the results showed that the remaining KIR genes (2DS2-4, 2DL1, 2, 4, 3DL1-2) and two pseudogenes (2DP1 and 3DP1) did not have significant associations with risk of PTB infection. This meta-analysis provides reliable evidence that the KIR genes 2DL3, 2DS1, 2DS4, and 3DL1 may be associated with an increased risk of PTB infection.

Antigens of Mycobacterium tuberculosis Stimulate CXCR6+ Natural Killer Cells

Natural killer (NK) cells participate in immunity against several pathogens by exerting cytotoxic and cytokine-production activities. Some NK cell subsets also mediate recall responses that resemble memory of adaptive lymphocytes against antigenic and non-antigenic stimuli. The C-X-C motif chemokine receptor 6 (CXCR6) is crucial for the development and maintenance of memory-like responses in murine NK cells. In humans, several subsets of tissue-resident and circulating NK cells with different functional properties express CXCR6. However, the role of CXCR6+ NK cells in immunity against relevant human pathogens is unknown. Here, we addressed whether murine and human CXCR6+ NK cells respond to antigens of Mycobacterium tuberculosis (Mtb). For this purpose, we evaluated the immunophenotype of hepatic and splenic CXCR6+ NK cells in mice exposed to a cell-wall (CW) extract of Mtb strain H37Rv. Also, we characterized the expression of CXCR6 in peripheral NK cells from active pulmonary tuberculosis (ATB) patients, individuals with latent TB infection (LTBI), and healthy volunteer donors (HD). Furthermore, we evaluated the responses of CXCR6+ NK cells from HD, LTBI, and ATB subjects to the in vitro exposure to CW preparations of Mtb H37Rv and Mtb HN878. Our results showed that murine hepatic CXCR6+ NK cells expand in vivo after consecutive administrations of Mtb H37Rv CW to mice. Remarkably, pooled hepatic and splenic, but not isolated splenic NK cells from treated mice, enhance their cytokine production capacity after an in vitro re-challenge with H37Rv CW. In humans, CXCR6+ NK cells were barely detected in the peripheral blood, although slightly significative increments in the percentage of CXCR6+, CXCR6+CD49a−, CXCR6+CD49a+, and CXCR6+CD69+ NK cells were observed in ATB patients as compared to HD and LTBI individuals. In contrast, the expansion of CXCR6+CD49a− and CXCR6+CD69+ NK cells in response to the in vitro stimulation with Mtb H37Rv was higher in LTBI individuals than in ATB patients. Finally, we found that Mtb HN878 CW generates IFN-γ-producing CXCR6+CD49a+ NK cells. Our results demonstrate that antigens of both laboratory-adapted and clinical Mtb strains are stimulating factors for murine and human CXCR6+ NK cells. Future studies evaluating the role of CXCR6+ NK cells during TB are warranted.

Thinking Outside the Box: Innate- and B Cell-Memory Responses as Novel Protective Mechanisms Against Tuberculosis

Tuberculosis (TB) is currently the deadliest infectious disease worldwide. Failure to create a highly effective vaccine has limited the control of the TB epidemic. Historically, the vaccine field has relied on the paradigm that IFN-γ-mediated CD4+ T cell memory responses are the principal correlate of protection in TB. Nonetheless, the demonstration that other cellular subsets offer protective memory responses against Mycobacterium tuberculosis (Mtb) is emerging. Among these are memory-like features of macrophages, myeloid cell precursors, natural killer (NK) cells, and innate lymphoid cells (ILCs). Additionally, the dynamics of B cell memory responses have been recently characterized at different stages of the clinical spectrum of Mtb infection, suggesting a role for B cells in human TB. A better understanding of the immune mechanisms underlying such responses is crucial to better comprehend protective immunity in TB. Furthermore, targeting immune compartments other than CD4+ T cells in TB vaccine strategies may benefit a significant proportion of patients co-infected with Mtb and the human immunodeficiency virus (HIV). Here, we summarize the memory responses of innate immune cells and B cells against Mtb and propose them as novel correlates of protection that could be harnessed in future vaccine development programs.

Clinical and genetic markers associated with tuberculosis, HIV-1 infection, and TB/HIV-immune reconstitution inflammatory syndrome outcomes

BACKGROUND

Tuberculosis (TB) and AIDS are the leading causes of infectious disease death worldwide. In some TB-HIV co-infected individuals treated for both diseases simultaneously, a pathological inflammatory reaction termed immune reconstitution inflammatory syndrome (IRIS) may occur. The risk factors for IRIS are not fully defined. We investigated the association of HLA-B, HLA-C, and KIR genotypes with TB, HIV-1 infection, and IRIS onset.

METHODS

Patients were divided into four groups: Group 1- TB+/HIV+ (n = 88; 11 of them with IRIS), Group 2- HIV+ (n = 24), Group 3- TB+ (n = 24) and Group 4- healthy volunteers (n = 26). Patients were followed up at INI/FIOCRUZ and HGNI (Rio de Janeiro/Brazil) from 2006 to 2016. The HLA-B and HLA-C loci were typed using SBT, NGS, and KIR genes by PCR-SSP. Unconditional logistic regression models were performed for Protection/risk estimation.

RESULTS

Among the individuals with TB as the outcome, KIR2DS2 was associated with increased risk for TB onset (aOR = 2.39, P = 0.04), whereas HLA-B*08 and female gender were associated with protection against TB onset (aOR = 0.23, P = 0.03, and aOR = 0.33, P = 0.01, respectively). Not carrying KIR2DL3 (aOR = 0.18, P = 0.03) and carrying HLA-C*07 (aOR = 0.32, P = 0.04) were associated with protection against TB onset among HIV-infected patients. An increased risk for IRIS onset was associated with having a CD8 count ≤500 cells/mm3 (aOR = 18.23, P = 0.016); carrying the KIR2DS2 gene (aOR = 27.22, P = 0.032), the HLA-B*41 allele (aOR = 68.84, P = 0.033), the KIR2DS1 + HLA-C2 pair (aOR = 28.58, P = 0.024); and not carrying the KIR2DL3 + HLA-C1/C2 pair (aOR = 43.04, P = 0.034), and the KIR2DL1 + HLA-C1/C2 pair (aOR = 43.04, P = 0.034), CONCLUSIONS: These results suggest the participation of these genes in the immunopathogenic mechanisms related to the conditions studied. This is the first study demonstrating an association of HLA-B*41, KIR2DS2, and KIR + HLA-C pairs with IRIS onset among TB-HIV co-infected individuals.

Influence of Genetic Polymorphism Towards Pulmonary Tuberculosis Susceptibility

Tuberculosis (TB) is still remains the major threat for human health worldwide. Several case-control, candidate-gene, family studies and genome-wide association studies (GWAS) suggested the association of host genetic factors to TB susceptibility or resistance in various ethnic populations. Moreover, these factors modulate the host immune responses to tuberculosis. Studies have reported genetic markers to predict TB development in human leukocyte antigen (HLA) and non-HLA genes like killer immunoglobulin-like receptor (KIR), toll-like receptors (TLRs), cytokine/chemokines and their receptors, vitamin D receptor (VDR) and SLC11A1 etc. Highly polymorphic HLA loci may influence antigen presentation specificities by modifying peptide binding motifs. The recent meta-analysis studies revealed the association of several HLA alleles in particular class II HLA-DRB1 with TB susceptibility and valuable marker for disease development especially in Asian populations. Case-control studies have found the association of HLA-DR2 in some populations, but not in other populations, this could be due to an ethnic specific association of gene variants. Recently, GWAS conducted in case-control and family based studies in Russia, Chinese Han, Morocco, Uganda and Tanzania revealed the association of genes such as ASAP1, Alkylglycerol monooxygenase (AGMO), Forkhead BoxP1 (FOXP1), C-terminal domain phosphatase 1 (UBLCP1) and intergenic SNP rs932347C/T with TB. Whereas, SNP rs10956514A/G were not associated with TB in western Chinese Han and Tibetan population. In this review, we summarize the recent findings of genetic variants with susceptibility/resistance to TB.

Memory of Natural Killer Cells: A New Chance against Mycobacterium tuberculosis?

Natural killer (NK) cells are lymphocytes of the innate immune system, which play an important role in the initial defense against a wide variety of pathogens, including viruses and intracellular bacteria. NK cells produce cytokines that enhance immune responses directed toward pathogens and also exert cytotoxic activity against infected cells, thereby eliminating the reservoir of infection. Their role in defense against Mycobacterium tuberculosis (Mtb) has been recently studied, and there is increasing evidence that highlight the importance of NK cell function during pulmonary tuberculosis (PTB), especially in the absence of optimal T-cell responses. Additionally, in the last years, it has been observed that NK cells mediate secondary responses against antigens to which they were previously exposed, an ability classically attributed to lymphocytes of the adaptive branch of immunity. This phenomenon, called “innate memory,” could have important implications in the efforts to develop therapies and vaccines to improve the initial phases of immune reactions against different microorganisms, especially those to which there is not yet available vaccines to prevent infection, as is the case for tuberculosis. Therefore, the possibility of inducing memory-like NK cells ready to act prior to contact with Mtb or during the earliest stages of infection becomes quite interesting. However, our understanding of the mechanisms of innate memory remains incomplete. Here, we review recent literature about the mechanisms involved in the formation and maintenance of NK cell memory and the role of these cells in the immune response during tuberculosis. Finally, we discuss if the current evidence is sufficient to substantiate that NK cells exert more rapid and robust secondary responses after consecutive encounters with Mtb.

Reproduction, infection and killer-cell immunoglobulin-like receptor haplotype evolution

Killer-cell immunoglobulin-like receptors (KIRs) are encoded by one of the most polymorphic families in the human genome. KIRs are expressed on natural killer (NK) cells, which have dual roles: (1) in fighting infection and (2) in reproduction, regulating hemochorial placentation. Uniquely among primates, human KIR genes are arranged into two haplotypic combinations: KIR A and KIR B. It has been proposed that KIR A is specialized to fight infection, whilst KIR B evolved to help ensure successful reproduction. Here we demonstrate that a combination of infectious disease selection and reproductive selection can drive the evolution of KIR B-like haplotypes from a KIR A-like founder haplotype. Continued selection to survive and to reproduce maintains a balance between KIR A and KIR B.

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.

Evaluation of host genetics on outcome of tuberculosis infection due to differences in killer immunoglobulin-like receptor gene frequencies and haplotypes

Background

Outcome of Mycobacterium tuberculosis (Mtb) infection is affected by virulence of the infecting strain of Mtb, host environment, co-morbidities, and the genetic composition of the host, specifically the presence or absence of genes involved in immune responses/regulation. It is hypothesized that specific killer immunoglobulin-like receptor (KIR) genes may be associated with Mtb infection and clinical outcome. This cross-sectional study examined the KIR gene frequencies, profiles, and haplotypes of individuals with active tuberculosis, latent tuberculosis infection, compared to TB and HIV negative healthy controls.

Results

Analysis of KIR gene frequencies revealed differences among disease status groups, suggesting that enrichment or depletion of specific KIR genes may direct the disease outcome. Mtb infected individuals were more likely to have a centromeric-AA haplotype compared to controls.

Conclusion

The differences in KIR gene frequencies and haplotypes may result in differential cytokine expression, contributing to different disease outcomes, and suggest a genetic influence on Mtb susceptibility and pathogenesis.

KIR genotype distribution among Lebanese patients with Hodgkin's lymphoma

Introduction

In addition to their important role in fighting infection, natural killer cells are cytotoxic to cancer cells. Studies demonstrated that some KIR genes were responsible for the reduction of the risk of Hodgkin's lymphoma (HL) while others were associated with an increased risk of HL.

Aim

The aim of this study is to assess KIR genotypic distribution in Lebanese patients with Hodgkin's lymphoma.

Methods

KIR genotype was analyzed in 41 HL patients and 120 healthy Lebanese individuals using the KIR Genotyping SSP kit.

Results

No significant association between HL and any KIR gene was found. Among HL patients, the AA, AB, and BB genotype frequencies were, respectively, 41.46%, 43.9% and 14.63% with an A:B ratio of 1.73:1. As for the controls, the AA, AB, and BB genotype frequencies were, respectively, 39.17%, 50%, and 10.83% with an A:B ratio of 1.79:1.

Conclusion

In this first study from the Mediterranean region, KIR genotype does not seem to be associated with Hodgkin's lymphoma. Further clinical and translational research is needed to rule out the protective or predisposing role of KIR genes in this important clinical entity.

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KIR genotyping has been implicated in a variety of clinical and immunological disorders.

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This is the second international but first Mediterranean paper describing KIR genes prevalence in Hodgkin’'s lymphoma.

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Results were compared to a control sample and confirmed the negative association between KIR genes and Hodgkin’s lymphoma

Evolutionary changes in the genome of Mycobacterium tuberculosis and the human genome from 9000 years BP until modern times

The demonstration of Mycobacterium tuberculosis DNA in ancient skeletons gives researchers an insight into its evolution. Findings of the last two decades sketched the biological relationships between the various species of tubercle bacilli, the time scale involved, their possible origin and dispersal. This paper includes the available evidence and on-going research. In the submerged Eastern Mediterranean Neolithic village of Atlit Yam (9000 BP), a human lineage of M. tuberculosis, defined by the TbD1 deletion in its genome, was demonstrated. An infected infant at the site provides an example of active tuberculosis in a human with a naïve immune system. Over 4000 years later tuberculosis was found in Jericho. Urbanization increases population density encouraging M. tuberculosis/human co-evolution. As susceptible humans die of tuberculosis, survivors develop genetic resistance to disease. Thus in 18th century Hungarian mummies from Vác, 65% were positive for tuberculosis yet a 95-year-old woman had clearly survived a childhood Ghon lesion. Whole genome studies are in progress, to detect changes over the millennia both in bacterial virulence and also host susceptibility/resistance genes that determine the NRAMP protein and Killer Cell Immunoglobulin-like Receptors (KIRs). This paper surveys present evidence and includes initial findings.

KIR genotype distribution among symptomatic patients with and without Helicobacter pylori infection: is there any role for the B haplotype?

Contact of peripheral blood lymphocytes with Helicobacter pylori was proved to induce non- major histocompatibility complex-restricted cytotoxicity and natural killer cells are thought to play an important role in the immunity against H. pylori.

AIMS

In this research, we investigated any possible association between killer immunoglobulin-like receptors (KIR) genotypes and H. pylori infection.

METHODS

KIR genotype was analysed in 101 Lebanese symptomatic patients (51 H. pylori positive and 50 H. pylori-negative) using the KIR Genotyping SSP kit.

RESULTS

Among the H. pylori-positive patients, the AA, AB and BB genotypical frequencies were, respectively, 43.14%, 41.18% and 15.68% with an A:B ratio of 1.76:1. The AA, AB and BB genotypes frequencies for H. pylori-negative individuals were 18%, 62% and 20%, respectively, with an A:B ratio of 0.96:1. No significant difference between patients and controls was detected.

CONCLUSIONS

We noticed a reduced distribution of A haplotype among the 'H. pylori-negative' patients as compared with the "H. pylori-positive" group. This is the first study in the international literature that targets the correlation between KIR genotypes and H. pylori.

Conjunctival scarring in trachoma is associated with the HLA-C ligand of KIR and is exacerbated by heterozygosity at KIR2DL2/KIR2DL3

BACKGROUND

Chlamydia trachomatis is globally the predominant infectious cause of blindness and one of the most common bacterial causes of sexually transmitted infection. Infections of the conjunctiva cause the blinding disease trachoma, an immuno-pathological disease that is characterised by chronic conjunctival inflammation and fibrosis. The polymorphic Killer-cell Immunoglobulin-like Receptors (KIR) are found on Natural Killer cells and have co-evolved with the Human Leucocyte Antigen (HLA) class I system. Certain genetic constellations of KIR and HLA class I polymorphisms are associated with a number of diseases in which modulation of the innate responses to viral and intracellular bacterial pathogens is central.

METHODOLOGY

A sample of 134 Gambian pedigrees selected to contain at least one individual with conjunctival scarring in the F1 generation was used. Individuals (n = 830) were genotyped for HLA class I and KIR gene families. Family Based Association Tests and Case Pseudo-control tests were used to extend tests for transmission disequilibrium to take full advantage of the family design, genetic model and phenotype.

PRINCIPLE FINDINGS

We found that the odds of trachomatous scarring increased with the number of genome copies of HLA-C2 (C1/C2 OR = 2.29 BHP-value = 0.006; C2/C2 OR = 3.97 BHP-value = 0.0004) and further increased when both KIR2DL2 and KIR2DL3 (C2/C2 OR = 5.95 BHP-value = 0.006) were present.

CONCLUSIONS

To explain the observations in the context of chlamydial infection and trachoma we propose a two-stage model of response and disease that balances the cytolytic response of KIR expressing NK cells with the ability to secrete interferon gamma, a combination that may cause pathology. The data presented indicate that HLA-C genotypes are important determinants of conjunctival scarring in trachoma and that KIR2DL2/KIR2DL3 heterozygosity further increases risk of conjunctival scarring in individuals carrying HLA-C2.

Killer immunoglobulin-like receptor (KIR) centromeric-AA haplotype is associated with ethnicity and tuberculosis disease in a Canadian First Nations cohort

Killer immunoglobulin-like receptors (KIR) on natural killer (NK) cells interact with other immune cells to monitor the immune system and combat infectious diseases, such as tuberculosis (TB). The balance of activating and inhibiting KIR interactions helps determine the NK cell response. In order to examine the enrichment or depletion of KIRs as well as to explore the association between TB status and inhibitory/stimulatory KIR haplotypes, we performed KIR genotyping on samples from 93 Canadian First Nations (Dene, Cree, and Ojibwa) individuals from Manitoba with active, latent, or no TB infection, and 75 uninfected Caucasian controls. There were significant differences in KIR genes between Caucasians and First Nations samples and also between the First Nations ethnocultural groups (Dene, Cree, and Ojibwa). When analyzing ethnicity and tuberculosis status in the study population, it appears that the KIR profile and centromeric haplotype are more predictive than the presence or absence of individual genes. Specifically, the decreased presence of haplotype B centromeric genes and increased presence of centromeric-AA haplotypes in First Nations may contribute to an inhibitory immune profile, explaining the high rates of TB in this population.

Natural Killer Cell Immunoglobulin-like Receptor (KIR) genotypes in Follicular Lymphoma patients: results of a pilot study

AIMS

The Natural Killer Cell Immunoglobulin-like Receptor (KIR) genotype profiling in Follicular Lymphoma has not been reported before in the literature.

MATERIALS AND METHODS

DNA extracted from 20 Follicular Lymphoma patients and 62 healthy controls was analyzed for KIR genotyping using a polymerase chain reaction/sequence specific primers technique (PCR/SSP) for the presence of 16 KIR gene and pseudogene loci.

RESULTS

The AA, AB, and BB genotype frequencies were, respectively, 20%, 60% and 20% with an A:B ratio of 1:1. KIR 2DL4, KIR 3DL2, KIR 3DL3, and KIR 3DP1*003 were presented in all individuals. No significant difference between patients and controls was detected.

CONCLUSION

KIR genotyping profile does not seem to be associated with Follicular Lymphoma. The results presented in this pilot research represent the first international report about this important clinical entity.

Natural killer cells are recruited during pulmonary tuberculosis and their ex vivo responses to mycobacteria vary between healthy human donors in association with KIR haplotype

Humans vary widely in their susceptibility to tuberculosis. While only a minority will progress to disease, the majority of healthy individuals exposed to Mycobacterium tuberculosis mount an immune response that can clear or contain the infection in a quiescent form. Using immunofluorescence on human clinical samples, we identified natural killer (NK) cells infiltrating granulomatous pulmonary lesions during active disease. In order to compare the NK cell ability to react to free mycobacteria in the context of tuberculosis infection and Mycobacterium bovis BCG vaccination, NK cells were isolated from the peripheral blood of anonymous healthy human donors, and stimulated with M. tuberculosis H37Rv or M. bovis BCG. Extracellular M. tuberculosis and M. bovis BCG could equally trigger the release of IFNγ and TNFα from NK cells in the presence of IL-2. However, we found that this response varied 1000-fold between individuals (n = 52), with differences in KIR haplotype providing a significant criterion to distinguish between low and high responders. Our findings suggest that variations at the KIR locus and therefore of the NK cell repertoire may affect cytokine production in response to mycobacteria and we propose that this innate variability couldsustain different levels of susceptibility to M. tuberculosis infection.

Killer cell immunoglobulin like receptor gene association with tuberculosis

NK cells are vital components of innate immune system and are the first cells which come into picture mediating resistance against intracellular pathogens. NK cell cytotoxicity is modulated by a wide variety of cell surface receptors that recognize and respond towards infected cells. Activation of NK cells are controlled by both inhibitory and activating receptors, encoded by KIR genes and bind to HLA ligands. Not much is known about KIR genes and their influence on the pathogenesis with M. tuberculosis infection. Our study aimed at detecting the presence of 14 KIR genes, their distribution and their association with tuberculosis. Total 77 different genotype combinations were observed which belonged to B-haplotype. Fifteen genotypes were similar to those reported in other world populations while remaining 62 were unique to this study group. Inhibitory genes KIR3DL1, KIR2DL3 and activating genes KIR2DS1, KIR2DS5 conferred susceptibility towards TB either individually or in haplotype combinations. The complimentary MHC ligands need to be tested for the functional relevance of the associated genes.