Polymorphism within the interferon-gamma/receptor complex is associated with pulmonary tuberculosis

Association between interferon-gamma (IFN-γ) gene polymorphisms and tuberculosis susceptibility: a systematic review and meta-analysis

Interferon-gamma (IFN-γ) has been established to play a pivotal role in the pathogenesis of tuberculosis (TB). Existing evidence suggests a potential association between the genetic poly-morphisms of IFN-γ and the susceptibility to TB. However, this association remains a topic of controversy. To address this knowledge gap, a meta-analysis was conducted to provide more accurate results regarding their relationship. The pooled odds ratio along with its corresponding 95% confidence interval was calculated using four different gene models. This analytical approach served to evaluate the strength of the association between single nucleotide polymorphisms (SNPs) and TB susceptibility. Additionally, we determined whether a fixed effect model or a random effect model should be applied based on the extent of heterogeneity. Egger's test was used to evaluate publication bias. This study included a total of nine studies, involving 4509 patients with TB and 4378 healthy controls. In non-Asian populations, a C > T mutation at polymorphic variant rs2069705 and a T > C mutation at rs2069718 was associated with an increased risk of TB. Conversely, among Asians, the variants rs2069705, rs2069718, and rs1861494 were not significantly associated with the risk of TB. Importantly, our investigation did not reveal any significant publication bias in the pooled results of the four gene models. In conclusion, this meta-analysis suggests that two SNPs in IFN-γ may be associated with TB susceptibility in non-Asian populations. However, for Asians, there is no evidence to support a conclusive relationship between these SNPs and the risk of TB.

Single nucleotide polymorphism rs2234711 of interferon gamma receptor 1 is associated with pulmonary tuberculosis in the population of North India

Interferon-gamma (IFN-γ) is a pro-inflammatory cytokine playing essential role in immunity against tuberculosis (TB). IFN-γ performs function by binding to its receptor complex, consisting of two polypeptide chains viz. IFN-γ receptor 1 (IFN-γR1) and IFN-γ receptor 2 (IFN-γR2). Structural and functional deficiencies in IFN-γR1 can make individual vulnerable to even weak mycobacterial infections. Studies from different populations of the world have reported the association of single nucleotide polymorphisms (SNPs) present in IFNGR1 gene with TB, however, there are no such studies from India. Thus, the present study was designed to analyse the association of rs2234711 (C/T), rs7749390 (C/T) and rs1327475 (C/T) SNPs of IFNGR1 with TB in the population of North India. For the present study, 263 TB patients (at zero day of anti-tuberculosis therapy) and 256 healthy controls (HCs) were recruited. The genotyping of selected SNPs was done by high-resolution melting (HRM) curve analysis. The mRNA and surface expression data of IFNGR1 was extracted from our previous study and was grouped according to the genotypes of studied SNPs. The genotype 'TT' and 'T' allele of SNP rs2234711 (C/T) were found to be associated with TB in studied population ['T' vs 'C': OR (CI) = 1.79 (1.39-2.29); p-value < 0.0001]. The haplotypes 'C-C-C' of rs2234711-rs7749390-rs1327475 confers protection, while haplotype 'T-C-C' is a risk factor for TB in studied population. It was also found that 'TT' genotype of rs2234711 in HCs is associated with lower surface expression of IFNGR1 (p-value = 0.0078). In conclusion, 'TT' genotype is associated with lower surface expression of IFNGR1 and is increasing the susceptibility to TB in North Indian population.

Association between IFNGR1 gene polymorphisms and tuberculosis susceptibility: A meta-analysis

The association of IFN-γ receptor 1 (IFNGR1) gene polymorphisms with tuberculosis (TB) susceptibility has not been systematically studied. We therefore conducted a meta-analysis to assess their association. Literature search was conducted in PubMed, EMBASE, Web of Science, and the Cochrane Library. Odds ratio (OR) and 95% confidence interval (CI) was pooled by the random-effect model. Statistical analyses were performed using STATA 12.0 software. Fourteen studies involved 7,699 TB cases and 8,289 controls were included in this meta-analysis. A significant association was found between the IFNGR1 rs2234711 polymorphism and TB susceptibility among Africans in dominant model (OR = 1.24, 95%CI:1.01-1.52), and among Asians in allele model (OR = 0.89, 95%CI: 0.79-0.99), homozygote model (OR = 0.82, 95%CI: 0.70-0.98) and additive model (OR = 0.90, 95%CI: 0.83-0.97). In addition, a significant association was observed between the IFNGR1 rs7749390 polymorphism and TB susceptibility among Africans in allele model (OR = 0.89, 95%CI: 0.82-0.98). No significant association was found between the IFNGR1 rs1327474 polymorphism and TB susceptibility. In summary, IFNGR1 rs2234711 polymorphism was associated with increased TB susceptibility in Africans and decreased TB susceptibility in Asians, while IFNGR1 rs7749390 polymorphism was associated with decreased TB susceptibility in Africans.

Frequency distribution of cytokine and associated transcription factor single nucleotide polymorphisms in Zimbabweans: Impact on schistosome infection and cytokine levels

Cytokines mediate T-helper (TH) responses that are crucial for determining the course of infection and disease. The expression of cytokines is regulated by transcription factors (TFs). Here we present the frequencies of single nucleotide polymorphisms (SNPs) in cytokine and TF genes in a Zimbabwean population, and further relate SNPs to susceptibility to schistosomiasis and cytokine levels. Individuals (N = 850) were genotyped for SNPs across the cytokines IL4, IL10, IL13, IL33, and IFNG, and their TFs STAT4, STAT5A/B, STAT6, GATA3, FOXP3, and TBX21 to determine allele frequencies. Circulatory levels of systemic and parasite-specific IL-4, IL-5, IL-10, IL-13, and IFNγ were quantified via enzyme-linked immunosorbent assay. Schistosoma haematobium infection was determined by enumerating parasite eggs excreted in urine by microscopy. SNP allele frequencies were related to infection status by case-control analysis and logistic regression, and egg burdens and systemic and parasite-specific cytokine levels by analysis of variance and linear regression. Novel findings were i) IL4 rs2070874*T’s association with protection from schistosomiasis, as carriage of ≥1 allele gave an odds ratio of infection of 0.597 (95% CIs, 0.421–0.848, p = 0.0021) and IFNG rs2069727*G’s association with susceptibility to schistosomiasis as carriage of ≥1 allele gave an odds ratio of infection of 1.692 (1.229–2.33, p = 0.0013). Neither IL4 rs2070874*T nor IFNG rs2069727*G were significantly associated with cytokine levels. This study found TH2-upregulating SNPs were more frequent among the Zimbabwean sample compared to African and European populations, highlighting the value of immunogenetic studies of African populations in the context of infectious diseases and other conditions, including allergic and atopic disease. In addition, the identification of novel infection-associated alleles in both TH1- and TH2-associated genes highlights the role of both in regulating and controlling responses to Schistosoma.

Association of single nucleotide polymorphisms of interferon-γ with pulmonary tuberculosis in population of Himachal Pradesh, India

Interferon-gamma (IFN-γ) plays an integral role in the host immunity against tuberculosis (TB). The gene encoding IFN-γ is polymorphic and several studies have reported the association of its genetic polymorphisms with TB in different populations of the world. The present study investigated the association of rs2069705 (C/T), rs1861494 (C/T), rs1861493 (A/G) and rs2069718 (C/T) single nucleotide polymorphisms (SNPs) of IFN-γ with pulmonary TB in a population of Himachal Pradesh, India. For present study, 210 pulmonary TB patients and 205 healthy controls (HCs) were recruited. The selected SNPs of IFN-γ were genotyped by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and plasma IFN-γ levels were measured by ELISA. The 'T' allele of rs1861494 SNP was found to increase susceptibility to TB in the studied population (OR = 2.18, 95%CI = 1.57-3.03; p < 0.001). After stratifying the subjects on basis of sex, males with 'T' allele of rs2069718 SNP were found to be at higher risk to TB (OR = 1.55, 95%CI = 1.07-2.25; p = 0.02). We also found moderate linkage disequilibrium among the studied SNPs. The haplotypes C-T-A-T and T-T-G-T of rs2069705-rs1861494-rs1861493-rs2069718 were overrepresented in TB patients and found to increase susceptibility to TB (p = 0.012). The plasma IFN-γ levels in TB patients were around seven times higher in comparison to HCs (p < 0.0001). The HCs with genotype 'AA' of SNP rs1861493 were found with higher plasma IFN-γ levels than 'AG/GG' genotype (p = 0.023). In conclusion, the results suggest the association of rs1861494 (C/T) and rs2069718 (C/T) SNPs of IFN-γ with TB and genotype 'AA' of rs1861493 is associated with higher plasma IFN-γ levels in the population of Himachal Pradesh, India.

Cytokine Receptors-Regulators of Antimycobacterial Immune Response

Cytokine receptors are critical regulators of the antimycobacterial immune response, playing a key role in initiating and coordinating the recruitment and activation of immune cells during infection. They recognize and bind specific cytokines and are involved in inducing intracellular signal transduction pathways that regulate a diverse range of biological functions, including proliferation, differentiation, metabolism and cell growth. Due to mutations in cytokine receptor genes, defective signaling may contribute to increased susceptibility to mycobacteria, allowing the pathogens to avoid killing and immune surveillance. This paper provides an overview of cytokine receptors important for the innate and adaptive immune responses against mycobacteria and discusses the implications of receptor gene defects for the course of mycobacterial infection.

Obesity-Induced Dysbiosis Exacerbates IFN-γ Production and Pulmonary Inflammation in the Mycobacterium tuberculosis Infection

The microbiota of the gut-lung axis affects local and far-reaching immune responses and might also trigger chronic and inflammatory diseases. We hypothesized that gut dysbiosis induced by obesity, which coexists in countries with a high tuberculosis burden, aggravates the host susceptibility and the pulmonary damage tolerance. To assess our hypothesis, we used a model of high-fat diet (HFD)-induced obesity, followed by infection of C57BL/6 mice with Mycobacterium tuberculosis. We showed that obesity increased the susceptibility, the pulmonary inflammation and IFN-γ levels in M. tuberculosis-infected mice. During the comorbidity obesity and tuberculosis, there is an increase of Bacteroidetes and Firmicutes in the lungs, and an increase of Firmicutes and butyrate in the feces. Depletion of gut microbiota by antibiotic treatment in the obese infected mice reduced the frequencies of CD4+IFN-γ+IL-17- cells and IFN-γ levels in the lungs, associated with an increase of Lactobacillus. Our findings reinforce the role of the gut-lung axis in chronic infections and suggest that the gut microbiota modulation may be a potential host-directed therapy as an adjuvant to treat TB in the context of IFN-γ-mediated immunopathology.

IFN-γ +874 A>T (rs2430561) gene polymorphism and risk of pulmonary tuberculosis: a meta-analysis

INTRODUCTION

The role of interferon gamma (IFN-γ) +874 A>T (rs2430561) gene polymorphism has been evaluated in different ethnicities with pulmonary tuberculosis (PTB) infection, and inconsistent results have been reported. In this study, a meta-analysis was performed to determine the precise association between IFN-γ +874 A>T gene polymorphism and PTB susceptibility.

MATERIAL AND METHODS

A total of 21 studies comprising 4281 confirmed PTB cases and 5186 healthy controls were included in this meta-analysis by searching the PubMed (Medline), EMBASE, and Google Scholar web-databases.

RESULTS

We observed reduced risk of PTB in allelic contrast (T vs. A: p = 0.001; OR = 0.818, 95% CI: 0.723-0.926), homozygous (TT vs. AA: p = 0.017; OR = 0.715, 95% CI: 0.543-0.941), heterozygous (AT vs. AA: p = 0.002; OR = 0.782, 95% CI: 0.667-0.917), dominant (TT+AT vs. AA: p = 0.002; OR = 0.768, 95% CI: 0.652-0.906), and recessive (TT vs. AA+AT: p = 0.042; OR = 0.802, 95% CI: 0.649-0.992) genetic models. In ethnicity-wise subgroup analysis, reduced risk of PTB was found in the Caucasian population. However, we did not find an association with any of the genetic models in the Asian population.

CONCLUSIONS

In conclusion, the IFN-γ +874 A>T gene polymorphism is significantly associated with reduced risk of PTB, showing a protective effect in the overall and in the Caucasian population. However, this polymorphism is not associated with PTB risk in the Asian population.

A family-based genome-wide association study of recurrent aphthous stomatitis

OBJECTIVES

The aetiology of recurrent aphthous stomatitis (RAS) remains unknown. Individuals may share features of genetic susceptibility, and there may also be a hereditary component. The aim was to identify patterns of association and segregation for genetic variants and to identify the genes and signalling pathways that determine the risk of developing RAS, through a family-based genome-wide association study (GWAS).

SUBJECTS AND METHODS

DNA was extracted from buccal swabs of 91 individuals in 16 families and analysed in an Illumina core exome single nucleotide polymorphism (SNP) array. A family-based association test (dFAM) was used to derive SNP association values across all chromosomes.

RESULTS

None of the final 288,452 SNPs reached the genome-wide significant threshold of 5 × 10^-8 . The most significant pathways were the Ras and PI3K-Akt signalling pathways, pathways in cancer, circadian entrainment and the Rap 1 signalling pathway.

CONCLUSIONS

This confirms that RAS is not monogenic but results as a consequence of interactions between multiple host genes and possibly also environmental factors. The present approach provides novel insights into the mechanisms underlying RAS and raises the possibility of identifying individuals at risk of acquiring this condition.

Regulation of Interferon-γ receptor (IFN-γR) expression in macrophages during Mycobacterium tuberculosis infection

Interferon-gamma (IFN-γ) is a key cytokine that mediates immunity to tuberculosis (TB). Mycobacterium tuberculosis (M. tb) is known to downregulate the surface expression of IFN-γ receptor (IFN-γR) on macrophages and peripheral blood mononuclear cells (PBMCs) of patients with active TB disease. Many M. tb antigens also downmodulate IFN-γR levels in macrophages when compared with healthy controls. In the current study, we aimed at deciphering key factors involved in M. tb mediated downregulation of IFN-γR levels on macrophage surface. Our data showed that both M. tb H37Rv and M. bovis BCG infections mediate downmodulation of IFN-γR on human macrophages. This downmodulation is regulated at the level of TLR signaling pathway, second messengers such as calcium and cellular kinases i.e. PKC and ERK-MAPK, indicating that fine tuning of calcium response is critical to maintaining IFN-γR levels on macrophage surface. In addition, genes in the calcium and cysteine protease pathways which were previously identified by us to play a negative role during M. tb infection, also regulated IFN-γR expression. Thus, modulations in IFN-γR levels by utilizing host machinery may be a key immune suppressive strategy adopted by the TB pathogen to ensure its persistence and thwart host defense.

Genetic variants in IFNG and IFNGR1 and tuberculosis susceptibility

BACKGROUND

Tuberculosis (TB) is the type of chronic infectious disease which majorly caused by Mycobacterium tuberculosis (M. TB). Emerging data suggest that interferon gamma (IFNG) and its receptor IFNGR1 may be involved in the risk of TB.

METHODS

A total of 636 TB patients and 608 healthy controls were selected. The association between single nucleotide polymorphisms (SNPs) and TB was estimated by logistic analyses adjusting for age, gender and smoking status. SNPs genotyping was done by using the improved multiplex ligase detection reaction (iMLDR).

RESULTS

The IFNG rs1861494 allele C was related to an increased risk for TB (OR = 1.25, 95%CI: 1.06-1.48; P = 0.009). Compared with TT genotype, CT (OR = 1.28, 95%CI: 1.01-1.63; P = 0.040) and CC (OR = 1.51, 95%CI: 1.04-2.19; P = 0.031) were also risk factors for TB. In the subgroup analysis, the association was stronger among participants < 25 years (OR = 2.40, 95%CI: 1.70-3.38; P < 0.001) and male groups (OR = 1.31, 95%CI: 1.03-1.66; P = 0.030). In addition, IFNG rs1861494 was associated with anti-TB treatment outcome (OR = 0.70, 95%CI: 0.52-0.94; P = 0.017). We also detected that IFNGR1 rs2234711 influenced the IFNG production.

CONCLUSION

IFNG rs1861494 polymorphism was associated with TB, particularly in the younger and male subgroups.

Genetic Polymorphisms of IFNG and IFNGR1 with Latent Tuberculosis Infection

Previous studies indicated that single-nucleotide polymorphisms (SNPs) of interferon gamma (IFNG) and IFNG receptor 1 (IFNGR1) may be involved in the pathogenesis of pulmonary tuberculosis (PTB) in different populations. In order to further explore the results in a Chinese Han population, this study was designed to investigate potential associations between the polymorphisms in IFNG and IFNGR1 and susceptibility to latent tuberculosis infection (LTBI) and/or PTB in a Chinese Han population. A total of 209 PTB, 173 LTBI, and 183 healthy control subjects (HCS) were enrolled in our study. Genotyping was conducted using an improved multiplex ligase detection reaction (iMLDR). We performed a logistic regression including sex and age as covariates to test the effect of alleles/genotypes on LTBI and/or TB. All six markers studied in IFNG and IFNGR1 conformed to the Hardy-Weinberg equilibrium (HWE). The IFNG rs1861494 was significantly associated with LTBI in recessive model, and the CC+CT genotype decreased risk of LTBI by 50% (P = 0.046, OR = 0.50, 95%CI: 0.25-0.99). The IFNGR1 rs2234711 was significantly associated with LTBI, and allele A increased the risk of LTBI by 55% (P = 0.047, OR = 1.55, 95%CI: 1.00-2.40). In the present study, we found that IFNG and IFNGR1 polymorphisms were associated with LTBI.

The Research Progress of Host Genes and Tuberculosis Susceptibility

BACKGROUND/AIMS

Nucleotide diversity may affect the immune regulation of tuberculosis (TB) patients, leading to the individual susceptibility to TB. In recent years, there are a lot of researches on the association of host genetic factors and TB susceptibility which has attracted increasing attention, and the in-depth study of its mechanism is gradually clear.

MATERIALS

We made a minireview on the association of many candidate genes with TB based on recent research studies systematically, such as the human leukocyte antigen (HLA) gene, the solute carrier family 11 member 1 (SLC11A1) gene system, the vitamin D receptor (VDR) gene, the mannan-binding lectin (MBL) gene, the nitric oxide synthase 2A (NOS2A) gene, the speckled 110 (SP110) gene, and the P2X7 receptor (P2X7) gene. The discovery of these candidate genes could reveal the pathogenesis of TB comprehensively and is crucial to provide scientific evidence for formulating the related measures of prevention and cure.

DISCUSSION

The host genes play important roles in the development of TB, and the host genes may become new targets for the prevention and treatment of TB. Effective regulation of host genes may help prevent or even treat TB.

CONCLUSION

This minireview focuses on the association of host genes with the development of TB, which may supply some clues for future therapies and novel drug targets for TB.

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.

The Distribution Frequency of Interferon-Gamma Receptor 1 Gene Polymorphisms in Interferon-γ Release Assay-Positive Patients

Tuberculosis is caused by mycobacterium, a potentially fatal infectious bacterium. In recent years, TB cases increased in the whole world. WHO statistics data shows that the world's annual tuberculosis incidence was 8~10 million with about 3 million deaths. Several studies have shown that susceptibility to tuberculosis may be associated with IFNGR1 gene polymorphisms. Here, we report the distribution frequency of IFNGR1 gene polymorphisms in 103 cases of IGA-negative patients and 100 cases of IGA-positive patients from China by sequencing the IFNGR1 proximal ~750 bp promoter region. We found a total of 5 types of site mutations: -611 (G/A), -56 (T/C), -255 (C/T), -359 (T/C), and -72 (C/T). The two main types of gene polymorphisms among the IGA-negative and IGA-positive groups were -611 (G/A), with mutation rates of 88.3% and 78.4%, respectively, and -56 (T/C), with mutation rates of 84.5% and 83.8%, respectively, which had no statistical significance, and there was no correlation with the incidence of tuberculosis.

Genomics of human pulmonary tuberculosis: from genes to pathways

Purpose of review

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), remains a major public health threat globally. Several lines of evidence support a role for host genetic factors in resistance/susceptibility to TB disease and MTB infection. However, results across candidate gene and genome-wide association studies (GWAS) are largely inconsistent, so a cohesive genetic model underlying TB risk has not emerged.

Recent Findings

Despite the difficulties in identifying consistent genetic associations, genetic studies of TB and MTB infection have revealed a few well-documented loci. These well validated genes are presented in this review, but there remains a large gap in how these genes translate into better understanding of TB. To address this, we present a pathway based extension of standard association analyses, seeding the results with the best validated genes from candidate gene and GWAS studies.

Summary

Several pathways were significantly enriched using pathway analyses that may help to explain population patterns of TB risk. In conclusion, we advocate for novel approaches to the study of host genetic analysis of TB that extend traditional association approaches.

Susceptibility to Mycobacterium ulcerans Disease (Buruli ulcer) Is Associated with IFNG and iNOS Gene Polymorphisms

Buruli ulcer (BU) is a chronic necrotizing disease of the skin and subcutaneous fat tissue. The causative agent, Mycobacterium ulcerans, produces mycolactone, a macrolide toxin, which causes apoptosis of mammalian cells. Only a small proportion of individuals exposed to M. ulcerans develop clinical disease, as surrounding macrophages may control the infection by bacterial killing at an early stage, while mycolactone concentration is still low. Otherwise, bacterial multiplication leads to in higher concentrations of mycolactone, with formation of necrotizing lesions that are no more accessible to immune cells. By typing a cohort of 96 Ghanaian BU patients and 384 endemic controls without BU, we show an association between BU and single nucleotide polymorphisms (SNPs) in iNOS (rs9282799) and IFNG (rs2069705). Both polymorphisms influence promoter activity in vitro. A previously reported SNP in SLC11A1 (NRAMP, rs17235409) tended to be associated with BU. Altogether, these data reflect the importance of IFNG signaling in early defense against M. ulcerans infection.

Association of Interferon-γ Receptor-1 Gene Polymorphism with Nontuberculous Mycobacterial Lung Infection among Iranian Patients with Pulmonary Disease

Nontuberculous mycobacteria (NTM) cause significant pulmonary infections in humans. Researchers have reported an association between interferon-gamma receptor-1 (IFN-γR1 or IFNGR1) deficiency and susceptibility to NTM, but the relevance of polymorphism within these genes is not yet clear. In this study, a single nucleotide polymorphism (SNP), T to C, at position-56 in NTM patients with pulmonary disease was investigated. Molecular identification of Mycobacterium isolates was performed with hsp65 genes using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Then, the host genomic DNA from confirmed NTM patients (N = 80) and control subjects (N = 80) were screened for SNPs of IFNGR1 (T-56C) by PCR-RFLP. The results indicated that NTM patients had higher TC (26/80; 32.5%) or CC (46/80; 57.5%) genotypes in comparison with control groups (TC genotypes [22/80, 27.5%]; CC genotypes [6/80, 7.5%]) (P < 0.05). In this regard, all the patients infected with rapid-growing Mycobacterium (RGM, i.e., Mycobacterium chelonae and Mycobacterium fortuitum) had CC genotypes (100%). In contrary, only 50.7% (35/69) of infected patients with slow-growing Mycobacterium (i.e., Mycobacterium simiae, Mycobacterium kansasii, and Mycobacterium avium-intracellulare) had CC genotypes. Thus, patients with CC mutation in IFNGR1 at position-56 are more likely to develop RGM infection. In overall, there is a significant association between SNP of IFNGR1 at position-56 and susceptibility to NTM infection. Based on these data, we propose SNP of IFNGR1 at position-56 as a suitable "biomarker" for identifying populations at higher risk of infection.

A single nucleotide polymorphism in the interferon-γ gene (IFNG +874 T/A) is associated with susceptibility to tuberculosis

Interferon-γ (Interferon gamma, IFNG) is an important cytokine involved in providing resistance to mycobacterial diseases. Common variants of IFNG, such as IFNG +874 T/A(rs2430561), may be related to tuberculosis susceptibility, but this association has not been consistently observed. We performed an updated meta-analysis to evaluate the association between the IFNG +874 T/A (rs2430561) polymorphism and tuberculosis susceptibility. PubMed and SinoMed databases were searched up to October 2016, and odds ratios (OR) and 95% confidence intervals (CI) were used to assess the association strength. Based on search criteria for manuscripts reporting tuberculosis susceptibility and its relationship with the IFNG +874 T/A(rs2430561)polymorphism, 42 case-control studies from 39 different articles were retrieved. Significantly positive, decreased, and protective associations were found between the IFNG +874 T/A(rs2430561)polymorphism and tuberculosis risk in five genetic models. Moreover, in the stratified subgroup analysis, a protective relationship was detected in four different ethnicities and sources of the control groups. Furthermore, the IFNG +874 T/A(rs2430561)polymorphism played an important role in protecting individuals from both pulmonary tuberculosis and extra-pulmonary tuberculosis. Our meta-analysis suggests that the IFNG +874 T/A(rs2430561)polymorphism is potentially associated with tuberculosis susceptibility and may be used as a predictive biomarker. Further studies with larger sample sizes and consideration of gene-environment interactions should be conducted to elucidate the role of IFNG +874 T/A(rs2430561) polymorphism in tuberculosis susceptibility.

A post-GWAS analysis of predicted regulatory variants and tuberculosis susceptibility

Utilizing data from published tuberculosis (TB) genome-wide association studies (GWAS), we use a bioinformatics pipeline to detect all polymorphisms in linkage disequilibrium (LD) with variants previously implicated in TB disease susceptibility. The probability that these variants had a predicted regulatory function was estimated using RegulomeDB and Ensembl's Variant Effect Predictor. Subsequent genotyping of these 133 predicted regulatory polymorphisms was performed in 400 admixed South African TB cases and 366 healthy controls in a population-based case-control association study to fine-map the causal variant. We detected associations between tuberculosis susceptibility and six intronic polymorphisms located in MARCO, IFNGR2, ASHAS2, ACACA, NISCH and TLR10. Our post-GWAS approach demonstrates the feasibility of combining multiple TB GWAS datasets with linkage information to identify regulatory variants associated with this infectious disease.

Properties of STAT1 and IRF1 enhancers and the influence of SNPs

BACKGROUND

STAT1 and IRF1 collaborate to induce interferon-γ (IFNγ) stimulated genes (ISGs), but the extent to which they act alone or together is unclear. The effect of single nucleotide polymorphisms (SNPs) on in vivo binding is also largely unknown.

RESULTS

We show that IRF1 binds at proximal or distant ISG sites twice as often as STAT1, increasing to sixfold at the MHC class I locus. STAT1 almost always bound with IRF1, while most IRF1 binding events were isolated. Dual binding sites at remote or proximal enhancers distinguished ISGs that were responsive to IFNγ versus cell-specific resistant ISGs, which showed fewer and mainly single binding events. Surprisingly, inducibility in one cell type predicted ISG-responsiveness in other cells. Several dbSNPs overlapped with STAT1 and IRF1 binding motifs, and we developed methodology to rapidly assess their effects. We show that in silico prediction of SNP effects accurately reflects altered binding both in vitro and in vivo.

CONCLUSIONS

These data reveal broad cooperation between STAT1 and IRF1, explain cell type specific differences in ISG-responsiveness, and identify genetic variants that may participate in the pathogenesis of immune disorders.

Polymorphisms of Cytokine Genes and Polycystic Ovary Syndrome: A Review

BACKGROUND

Polycystic ovary syndrome (PCOS) is the endocrinopathy that affects women in their reproductive age. The physiopathology involves multifactorial mechanisms, including cytokine gene regulation.

METHODS

The review was conducted in the database PubMed, with articles published between 2005 and 2015. The selected studies evaluated the single-nucleotide polymorphisms (SNPs) of cytokines genes in association with PCOS. Twenty-four studies met the inclusion criteria and showed the SNPs of cytokines that were associated or not with PCOS.

RESULTS

The disease susceptibility was associated with interleukin (IL) 1A, IL1B, IL1RN, and IL6 alleles and genotypes. The tumor necrosis factor (TNF) -1032 C/T genotype and C allele were risk factors and T/T genotype was a protector marker to disease. The IL18 SNPs were not associated with PCOS per se, but IL18-137 C and G alleles were related to the protection of insulin resistance and glucose tolerance, respectively. One research found association between TGFB1 and PCOS. However, the TNF -308, IL10, and interferon (IFN) SNPs did not appear to influence PCOS genetic susceptibility.

CONCLUSIONS

This study sought to contribute and clarify the SNPs in cytokine genes that influence the development of PCOS. Most studies occurred in Asia; most SNPs studied were in IL1B -511, TNF -1031, and IL6-174; and most of them were associated with the susceptibility to PCOS development. Nevertheless, further investigations based on genome-wide association studies and cytokine gene SNPs are needed to better characterize the risk factors to PCOS.

The Role of Host Genetics (and Genomics) in Tuberculosis

Familial risk of tuberculosis (TB) has been recognized for centuries. Largely through studies of mono- and dizygotic twin concordance rates, studies of families with Mendelian susceptibility to mycobacterial disease, and candidate gene studies performed in the 20th century, it was recognized that susceptibility to TB disease has a substantial host genetic component. Limitations in candidate gene studies and early linkage studies made the robust identification of specific loci associated with disease challenging, and few loci have been convincingly associated across multiple populations. Genome-wide and transcriptome-wide association studies, based on microarray (commonly known as genechip) technologies, conducted in the past decade have helped shed some light on pathogenesis but only a handful of new pathways have been identified. This apparent paradox, of high heritability but few replicable associations, has spurred a new wave of collaborative global studies. This review aims to comprehensively review the heritability of TB, critically review the host genetic and transcriptomic correlates of disease, and highlight current studies and future prospects in the study of host genomics in TB. An implicit goal of elucidating host genetic correlates of susceptibility to Mycobacterium tuberculosis infection or TB disease is to identify pathophysiological features amenable to translation to new preventive, diagnostic, or therapeutic interventions. The translation of genomic insights into new clinical tools is therefore also discussed.

Missense splice variant (g.20746A>G, p.Ile183Val) of interferon gamma receptor 1 (IFNGR1) coincidental with mycobacterial osteomyelitis - a screen of osteoarticular lesions

Previously, dominant partial interferon-gamma receptor 1 (IFN-g-R1) susceptibility to environmental mycobacteria was found with IFNGR1 deletions or premature stop. Our aim was to search for IFNGR1 variants in patients with mycobacterial osteoarticular lesions. Biopsies from the patients were examined for acid-fast bacilli, inflammatory cell infiltration, and mycobacterial niacin. Mycobacterial rRNA was analyzed using a target-amplified rRNA probe test. Peripheral-blood-leukocyte genomic DNA was isolated from 19 patients using the QIAamp DNA Mini Kit, and all IFNGR1 exons were sequenced using an ABIPRISM 3130 device. After the discovery of an exon 5 variant, a Polish newborn population sample (n = 100) was assayed for the discovered variant. Splice sites and putative amino acid interactions were analyzed. All patients tested were positive for mycobacteria; one was heterozygous for the IFNGR1 exon 5 single-nucleotide-missense substitution (g.20746A>G, p.Ile183Val). No other variant was found. The splice analysis indicated the creation of an exonic splicing silencer, and alternatively, molecular graphics indicated that the p.Ile183Val might alter beta-strand packing (loss of van der Waals contacts; Val183/Pro205), possibly altering the IFN-g-R1/IFN-g-R2 interaction. The probability of non-deleterious variant was estimated as <10%. Heterozygous IFNGR1:p.Ile183Val (frequency 0.003%) was found to be coincidental with mycobacterial osteomyelitis. The small amount of variation detected in the patients with osteoarticular lesions indicates that screens should not yet be restricted: Intronic variants should be analyzed as well as the other genes affecting Type 1 T-helper-cell-mediated immunity.

Discriminative expression of whole blood genes in HIV patients with latent and active TB in Ethiopia

BACKGROUND

Transcriptomic host biomarkers could assist in developing effective diagnostics, vaccines and therapeutics for tuberculosis (TB). However, different biomarkers may be discriminatory in different populations depending on the host and bacillary genetics and HIV infection, and need to be addressed.

METHODS

The expression levels of 45 genes that are known to be involved in or affected by TB pathogenesis were analyzed using dual color Reverse Transcriptase Multiplex Ligation-dependent Probe Amplification (dcRT-MLPA) assay in whole blood of 106 HIV positive individuals including active TB patients (TB(+)HIV(+), n = 29), and non TB patients that are tuberculin skin test positive (TST+) (TST(+)HIV(+), n = 26), or TST negative (TST(-)HIV(+), n = 51).

RESULTS

Between the two clinical groups (TB(+)HIV(+) vs. TST(-)HIV(+)) 8 genes were differently expressed (CCL19, CD14, CD8A, FPR1, IL7R, CCL22, TNFRSF1A, and FCGR1A); between TB(+)HIV(+) vs. TST(+)HIV(+), 6 genes (CD14, IL7R, TIMP2, CCL22, TNFRSF1A, and FCGR1A) were differently expressed. Since no difference in gene expression was revealed between TST(+)HIV(+) vs. TST(-)HIV(+), we clustered both the TST(+)HIV(+) and TST(-)HIV(+) individuals as one group (TST(+/-)HIV(+)) and compared gene expression with TB(+)HIV(+) patients. Thus, the results revealed that the levels of five genes (CD8A, TIMP2, CCL22, FCGR1A and TNFRSF1A) were the most accurate single gene markers for differentiation between TB(+)HIV(+) and TST(+/-)HIV(+), with AUCs of 0.71, 0.71, 0.79, 0.83 and 0.73, respectively. However, the combination of two genes (CCL22 + FCGR1A) and FCGR1A alone were the most accurate marker for differentiation between the two groups (TB(+)HIV(+) and TST(+/-)HIV(+)) with AUC of 0.85 and 0.83, respectively.

CONCLUSIONS

We showed that five genes (CD8A, TIMP2, CCL22, FCGR1A and TNFRSF1A), specifically FCGR1A and CCL22 have the potential to discriminate active TB from non-active TB in HIV patients in Ethiopia and could be used to improve diagnostic tools for active TB in HIV patients, and to understand the pathogenesis of TB/HIV coinfection.

Association study of polymorphisms in interferon-γ receptor genes with the risk of pulmonary tuberculosis

Tuberculosis (TB) is an infectious disease caused by mycobacterium, which most commonly affects the lungs. The adaptive immune response in Mycobacterium tuberculosis is predominantly mediated by the interferon-γ (IFN-γ) signaling pathway, which is regulated by IFN-γ receptors (IFNGR). IFN-γ activates the transcription of a number of genes that are important in immune responses, thus the appropriate function of IFNGR appears to be important in host defense against mycobacteria. In the present study, 22 genetic variants in IFNGR1 and IFNGR2 were genotyped in 673 patients and 592 normal controls to investigate the association between IFNGR1 and IFNGR2 polymorphisms and the risk of TB. Statistical analyses revealed that four genetic variants in IFNGR1, rs9376269, rs9376268, rs9376267 and rs56251346 were marginally associated with the risk of TB (P = 0.02-0.04), while other single nucleotide polymorphisms in IFNGR1 and IFNGR2 did not exhibit any associations. However, the significance of the four genetic variants rs9376269, rs9376268, rs9376267 and rs56251346 was eliminated following a multiple testing correction of the data (P>0.05). The present results revealed that certain genetic variants in IFNGR genes may be associated with TB development, which may be useful preliminary data for future investigation.

Gene polymorphisms of stress hormone and cytokine receptors associate with immunomodulatory profile and psychological measurement

OBJECTIVE

We sought to identify whether stable single nucleotide polymorphisms (SNPs) of various endocrine and immune molecules could be used as biomarkers associated with specific immune alterations and chronic stress measures in normal humans.

METHODS

A total of 207 volunteer participants answered stress questionnaire and gave peripheral blood cells for identification of SNPs in genes coding for glucocorticoid receptor (GR), beta 2 adrenergic receptor (B2AR), interferon-gamma receptors (IFNGR1, IFNGR2), and interleukin-4 receptor (IL4R). Immunoregulatory profiles were measured by flow cytometry and genotyping assays were performed by allelic discrimination real-time PCR.

RESULTS

Several significant differences were revealed in associations between stress marker and immune indicators based on SNP categories. For instance, Th1 levels of the minor alleles of GR TthIIII (AA) and IFNGR2 Q64R (Arg/Arg) groups were positively associated with chronic stress (PSS) (p = 0.024 and 0.005, respectively) compared with wild type (WT) and negatively associated with PSS in the heterozygous genotypes of GR BclI and IL4R Ile50Val (p = 0.040 and p = 0.052, respectively). Treg levels of the minor alleles of BclI (GG) and IFNGR1 T-56C (CC) groups were positively associated with PSS (p = 0.045 and p = 0.010, respectively) and negatively associated in the minor allele (Val/Val) of IL4R Ile50Va and the heterozygous genotype of IL4R Q576R (p = 0.041 and p = 0.017, respectively) compared to WT.

CONCLUSION

The data support the notion that gene polymorphisms from various components of the psychoneuroendocrine-immune network may be useful as biomarkers to categorize individual stress-associated immune responses.

Single nucleotide polymorphisms in the interferon gamma gene are associated with distinct types of retinochoroidal scar lesions presumably caused by Toxoplasma gondii infection

The association of single nucleotide polymorphisms (SNPs) in the interferon (IFN)-γ gene ( IFNG ) with different types of retinal scar lesions presumably caused by toxoplasmosis were investigated in a cross-sectional population-based genetic study. Ten SNPs were investigated and after Bonferroni correction, only the associations between SNPs rs2069718 and rs3181035 with retinal/retinochoroidal scar lesions type A (most severe scar lesions) and C (least severe scar lesions), respectively, remained significant. The associations of two different IFNG SNPs with two different types of retinal lesions attributable to toxoplasmosis support the hypothesis that different inflammatory mechanisms underlie the development of these lesions. The in vitro analysis of IFN-γ secretion by peripheral blood mononuclear cells stimulated with Toxoplasma gondii antigens was also investigated. The association between SNP rs2069718 and type A scar lesions revealed that differential IFN-γ levels are correlated with distinct genotypes. However, no correlation was observed with IFN-γ secretion levels and the SNP rs3181035 , which was significantly associated with type C scar lesions. Our findings strongly suggest that immunogenetic studies of individuals with congenital or postnatally acquired infection are needed to better understand the role of IFN-γ and its polymorphisms in the pathogenesis of ocular toxoplasmosis.

New insights into the interaction of Mycobacterium tuberculosis and human macrophages

Mycobacterium tuberculosis is a facultative intracellular pathogen. It infects macrophages where it avoids elimination by interfering with host defense mechanisms. Until recently, it was assumed that the acidification of phagosomes is the major strategy of macrophages to eliminate M. tuberculosis. However, there is emerging evidence demonstrating that human macrophages are equipped with additional antimicrobial effector functions. Specifically, autophagy, efferocytosis and antimicrobial peptides have been identified as mechanisms to restrict mycobacterial proliferation. Here we review recent findings on effector functions of human macrophages and mechanisms of the pathogen to interfere with them.

Clinical implications of interferon-γ genetic and epigenetic variants

Interferon-γ (IFN-γ) is an integral and critical molecule of the immune system, with multiple functions, mostly related to the T helper type 1 (Th1) response to infection. It is critical for defence against mycobacterial infection and is of increasing interest in defence against fungi. In this article, we review the genetic and epigenetic variants affecting IFN-γ expression and investigate its role in disease, with an emphasis on fungal diseases such as invasive and chronic pulmonary aspergillosis. Over 347 IFN-γ gene variants have been described, in multiple ethnic populations. Many appear to confer a susceptibility to disease, especially tuberculosis (TB) and hepatitis, but also some non-infectious conditions such as aplastic anaemia, cervical cancer and psoriasis. Several epigenetic modifications are also described, increasing IFN-γ expression in Th1 lymphocytes and reducing IFN-γ expression in Th2 lymphocytes. Recombinant IFN-γ administration is licensed for the prophylaxis of infection (bacterial and fungal) in patients with the phagocyte functional deficiency syndrome chronic granulomatous disease, although the benefits appear limited. Interferon-γ therapy is given to patients with profound defects in IFN-γ and interleukin-12 production and appears to be beneficial for patients with invasive aspergillosis and cryptococcal meningitis, but the studies are not definitive. A high proportion of patients with chronic pulmonary aspergillosis are poor producers of IFN-γ in response to multiple stimuli and could also benefit from IFN-γ administration. The investigation and management of patients with possible or demonstrated IFN-γ deficiency in adulthood is poorly studied and could be greatly enhanced with the integration of genetic data.

Gene polymorphisms in patients with pulmonary tuberculosis from Mozambique

Several host and environmental factors contribute to tuberculosis outcome, interestingly single nucleotide polymorphisms (SNPs) in candidate genes have been evaluated in populations with different ethnicities and TB infection. In the present study we focused on SNPs in cytokine and inflammatory mediator genes: tumor necrosis factor (TNF) -308G>A (rs1800629), interleukin-10 (IL10) -819C>T (rs1800871), interferon-gamma (IFNG) +874T>A (rs2430561), and leukotriene A4 hydrolase (LTA4H) rs1978331, rs17525495 and rs2660898 in a case-control study involving 102 pulmonary tuberculosis patients and 456 controls from Mozambique. LTA4H, IL10 and IFNG SNPs showed no associations with pulmonary tuberculosis. However, distribution of the TNF -308A allele, genotype and carrier frequencies showed a significant risk association with tuberculosis that was maintained after adjustment for non-genetic variables and Bonferroni correction (AA genotype, OR = 1.9, p Bonf < 0.001; A allele OR = 2.9, p Bonf = 0.005 and GA/AA carrier OR = 2.6, p Bonf = 0.035). Interestingly, this association has not been reported in a sub-Saharan African population before. Our results suggest a role of -308 TNF polymorphism and tuberculosis susceptibility.

Combination of gene expression patterns in whole blood discriminate between tuberculosis infection states

Background

Genetic factors are involved in susceptibility or protection to tuberculosis (TB). Apart from gene polymorphisms and mutations, changes in levels of gene expression, induced by non-genetic factors, may also determine whether individuals progress to active TB.

Methods

We analysed the expression level of 45 genes in a total of 47 individuals (23 healthy household contacts and 24 new smear-positive pulmonary TB patients) in Addis Ababa using a dual colour multiplex ligation-dependent probe amplification (dcRT-MLPA) technique to assess gene expression profiles that may be used to distinguish TB cases and their contacts and also latently infected (LTBI) and uninfected household contacts.

Results

The gene expression level of BLR1, Bcl2, IL4d2, IL7R, FCGR1A, MARCO, MMP9, CCL19, and LTF had significant discriminatory power between sputum smear-positive TB cases and household contacts, with AUCs of 0.84, 0.81, 0.79, 0.79, 0.78, 0.76, 0.75, 0.75 and 0.68 respectively. The combination of Bcl2, BLR1, FCGR1A, IL4d2 and MARCO identified 91.66% of active TB cases and 95.65% of household contacts without active TB. The expression of CCL19, TGFB1, and Foxp3 showed significant difference between LTBI and uninfected contacts, with AUCs of 0.85, 0.82, and 0.75, respectively, whereas the combination of BPI, CCL19, FoxP3, FPR1 and TGFB1 identified 90.9% of QFT^- and 91.6% of QFT⁺ household contacts.

Conclusions

Expression of single and especially combinations of host genes can accurately differentiate between active TB cases and healthy individuals as well as between LTBI and uninfected contacts.

Incidence of active pulmonary tuberculosis in patients with coincident filarial and/or intestinal helminth infections followed longitudinally in South India

BACKGROUND

Filarial (and other helminth) infections are known to modulate mycobacteria-specific pro-inflammatory cytokine responses necessary for maintaining latency in tuberculosis (TB). We sought to address whether helminth co-infection alters progression to active pulmonary TB in a co-endemic area of South India.

METHODS/PRINCIPAL FINDINGS

Incidence of active pulmonary TB was assessed in 5096 subjects from five villages among helminth-infected (hel⁺) and -uninfected (hel⁻) groups. Baseline stool examinations, circulating filarial antigen, and tuberculin skin testing (PPD) were performed along with chest radiographs, sputum microscopy, and culture. During three follow-up visits each 2.5 years, patients were assessed using PPD tests and questionnaires and--for those with potential symptoms of TB--sputum microscopy and culture. Of the 5096 subjects, 1923 were found to be hel⁺ and 3173 were hel⁻. Follow up interval stool examination could not be performed. In each group, 21 developed active TB over the course of the study. After adjusting for sex, age, BCG vaccination status, and PPD positivity, no difference was seen in active TB incidence between hel⁺ and hel- groups either at baseline (relative risk (RR) 1.60; 95% confidence interval (CI): 0.69, 3.71, P = 0·27), or when followed prospectively (RR 1.24; 95% CI: 0.48, 3.18, P = 0·66).

CONCLUSIONS/SIGNIFICANCE

Our findings suggest that, despite the immunomodulatory effects of helminth infection, baseline co-morbid infection with these parasites had little effect on the clinical progression from latent to active pulmonary TB.

Associations between cytokine receptor polymorphisms and variability in laboratory immune parameters in normal humans

In every study involving human immune parameters, large inter-subject variability occurs which can make interpretation of results difficult. The aim of this study was to evaluate whether genetic variants in cytokine receptors could associate with variability in laboratory immune measures. A total of 207 normal volunteers were recruited in this study. Immunoregulatory profiles were measured by flow cytometry and genotyping assays were performed by allelic discrimination real-time PCR. Immunoregulatory profiles were categorized according to various single nucleotide polymorphisms (SNPs) of cytokine receptors including T-56C and G-611A of IFN-γ receptor 1 (IFNGR1); Q64R of IFNGR2; and Ile50Val, Q576R and S503P of IL4R. Results reveal that Th1 levels were significantly higher in the heterozygous of the IFNGR1 T-56C polymorphism (minor allele) compared to wild-type (WT, major allele) (p = 0.006). For the Q576R of IL4R, Th1/Th2 ratio was significantly lower for the homozygous SNP (Arg/Arg) compared to the WT (Gln/Gln) (p = 0.035). In addition, the significant interaction effects of demographic characteristics on SNP-immune parameter associations were reported as well. We conclude that cytokine receptor polymorphisms might associate with variability in laboratory immune measures. Approach of SNP analysis of cytokine receptors can be useful in categorizing baseline immune responses to more accurately evaluate clinical immune data.

Host genome polymorphisms and tuberculosis infection: What we have to say?

Several epidemiology studies suggest that host genetic factors play important roles in susceptibility, protection and progression of tuberculosis infection. Here we have reviewed the implications of some genetic polymorphisms in pathways related to tuberculosis susceptibility, severity and development. Large case-control studies examining single-nucleotide polymorphisms (SNPs) in genes have been performed in tuberculosis patients in some countries. Polymorphisms in natural resistance-associated macrophage protein 1 (NRAMP1), toll-like receptor 2 (TLR2), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), interleukin-1 receptor antagonist (IL-1RA), IL-10, vitamin D receptor (VDR), dendritic cell-specific ICAM-3-grabbing non-integrin (DC-SIGN), monocyte chemoattractant protein-1 (MCP-1), nucleotide oligomerization binding domain 2 (NOD2), interferon-gamma (IFN-γ), inducible nitric oxide synthase (iNOS), mannose-binding lectin (MBL) and surfactant proteins A (SP-A) have been reviewed. These genes have been variably associated with tuberculosis infection and there is strong evidence indicating that host genetic factors play critical roles in tuberculosis susceptibility, severity and development.

Host Gene Polymorphisms in Relation to Helicobacter Pylori Infection and Associated Diseases in a Population Based Cohort

Background

This prospective population based cohort study explores possible associations between host gene polymorphisms, blood group and life style factors on the one hand, and Helicobacter pylori infection, peptic ulcer, and the grade of inflammation, atrophy and intestinal metaplasia of the gastric mucosa, on the other hand.

Methods

The study population (472 volunteers) has previously undergone screening with gastroduodenoscopy, biopsy and blood sampling. The host gene polymorphisms of IL1B-31C/T, IFNGR1-56T/C, the IL1RN VNTR in exon 2 and the HLA-DRB1 gene alleles were analyzed using PCR and pyrosequencing.

Results

H. pylori infection was negatively related to HLA DRB1*03 (odds ratio (OR) 95% CI: 0.388 - 0.989) and was more frequent in individuals with blood group O than A (OR 95% CI: 1.121 - 2.677). There was a lower risk of moderate to severe inflammation in the antrum among individuals with IL1B-31 TC compared to CC carriers (OR 95% CI: 0.094 - 0.733). The IL1RN*L2 genotype was associated with higher risk of IM in the antrum than the *LL genotype (OR 95% CI: 1.570 - 15.878). There was a negative relation between the HLA DRB1 alleles *04 (OR 95% CI: 0.234 - 0.831) and *08 (OR 95% CI: 0.013 - 0.915), and IM in the antrum.

Conclusion

The IL1RN VNTR and the IL1β-31 alleles seem to be associated with intestinal metaplasia of the corpus mucosa and the grade of inflammation of the antrum, respectively. However, no unambiguous correlations could be identified between the host polymorphisms and the occurrence of H. pylori infection, peptic ulcer, and the grade of inflammation, atrophy and IM of the gastric mucosa.

Potential association of pulmonary tuberculosis with genetic polymorphisms of toll-like receptor 9 and interferon-gamma in a Chinese population

Background

Association studies have been employed to investigate the relationships between host single nucleotide polymorphisms (SNPs) and susceptibility to pulmonary Tuberculosis (PTB). However, such candidate genetic markers have not been widely studied in Chinese population, especially with respect to the disease development from latent M. tuberculosis infection (LTBI).

Methods

In this case–control study, 44 candidate SNPs were examined in a total of 600 participants (PTB patients, LTBI controls and healthy controls without M. tuberculosis infection) from Zhengzhou, China. The two groups of controls were frequency matched on gender and age with PTB patients. Genotyping was carried out by the Illumina Golden Gate assay.

Results

When comparing PTB patients with LTBI controls but not healthy controls without M. tuberculosis infection, significant associations with disease development were observed for TLR9 1174 A/G, TLR9 1635 A/G and IFNG 2109G/A. The two loci in TLR9 were in LD in our study population (r²=0.96, D’=1.00). A combined effect of the genotypes associated with increased risk of PTB (i.e. TLR9 1174G/G and IFNG 2109 A/A) was found when comparing PTB patients with LTBI controls (p=0.004) but not with healthy controls without infection (p=0.433).

Conclusions

Potential associations between TLR9 and IFN-γ genetic polymorphisms and PTB were observed in a Chinese population which supports further study of the roles played by TLR9/IFN-γ pathway during the development of PTB.

Meta-analysis on the associations of TLR2 gene polymorphisms with pulmonary tuberculosis susceptibility among Asian populations

BACKGROUND

Publications regarding the associations of toll-like receptor 2 (TLR2) G2258A and T597C polymorphisms with pulmonary tuberculosis (PTB) susceptibility are inconsistent. A meta-analysis was conducted to investigate the relationship between TLR2 G2258A and T597C polymorphisms with PTB susceptibility.

METHODS

A systematic search was performed for published studies on the relationship between TLR2 polymorphisms and PTB susceptibility. Information was gathered from each eligible study, and statistically analyzed.

RESULTS

6 eligible studies, totaling 1301 cases and 1217 controls on G2258A genotypes, and 8 studies, totaling 2175 cases and 2069 controls on T597C genotypes, were included in the analysis. TLR2 2258G allele and 2258GG genotype were found to be associated with decreased PTB susceptibility (A vs. G: OR  = 3.02, 95% CI: 2.22-4.12, P<0.001, GA+AA vs. GG: OR  = 2.69, 95% CI = 1.49-4.87, P = 0.001). In the subgroup analyses, the 2258G allele and 2258GG genotype also exhibited a protective effect of PTB risk in Asians (A vs. G: OR  = 2.95, 95% CI: 1.91-4.55, P<0.001; GA+AA vs. GG: OR  = 3.59, 95% CI: 2.23-5.78, P<0.001), while no associations were observed in Caucasians. No significant associations between T597C polymorphism and PTB were found in the allele model (C vs. T: OR  = 0.95, 95% CI: 0.86-1.04, P = 0.28), co-dominant model (CC vs. TT: OR  = 0.88, 95% CI = 0.92-1.40, P = 0.25; CT vs. TT: OR  = 0.92, 95% CI = 0.80-1.06, P = 0.28), recessive model (CC vs. TT+TC: OR  = 0.96, 95% CI: 0.80-1.16, P = 0.69), or dominant model (TC+CC vs. TT: OR  = 0.93, 95% CI = 0.76-1.15, P = 0.51). The associations of T597C polymorphism with PTB susceptibility, in the ethnic-specific analyses, were still not significant.

CONCLUSION

TLR2 2258G allele may provide protective effects against PTB susceptibility, particularly among Asians, whereas TLR2 T597C polymorphism might not be associated with PTB susceptibility.

Type I IFNs downregulate myeloid cell IFN-γ receptor by inducing recruitment of an early growth response 3/NGFI-A binding protein 1 complex that silences ifngr1 transcription

The ability of type I IFNs to increase susceptibility to certain bacterial infections correlates with downregulation of myeloid cell surface IFNGR, the receptor for the type II IFN (IFN-γ), and reduced myeloid cell responsiveness to IFN-γ. In this study, we show that the rapid reductions in mouse and human myeloid cell surface IFNGR1 expression that occur in response to type I IFN treatment reflect a rapid silencing of new ifngr1 transcription by repressive transcriptional regulators. Treatment of macrophages with IFN-β reduced cellular abundance of ifngr1 transcripts as rapidly and effectively as actinomycin D treatment. IFN-β treatment also significantly reduced the amounts of activated RNA polymerase II (pol II) and acetylated histones H3 and H4 at the ifngr1 promoter and the activity of an IFNGR1-luc reporter construct in macrophages. The suppression of IFNGR1-luc activity required an intact early growth response factor (Egr) binding site in the proximal ifngr1 promoter. Three Egr proteins and two Egr/NGFI-A binding (Nab) proteins were found to be expressed in bone macrophages, but only Egr3 and Nab1 were recruited to the ifngr1 promoter upon IFN-β stimulation. Knockdown of Nab1 in a macrophage cell line prevented downregulation of IFNGR1 and prevented the loss of acetylated histones from the ifngr1 promoter. These data suggest that type I IFN stimulation induces a rapid recruitment of a repressive Egr3/Nab1 complex that silences transcription from the ifngr1 promoter. This mechanism of gene silencing may contribute to the anti-inflammatory effects of type I IFNs.

No association of IFNG+874T/A SNP and NOS2A-954G/C SNP variants with nitric oxide radical serum levels or susceptibility to tuberculosis in a Brazilian population subset

Tuberculosis (TB) is one of the most common infectious diseases in the world. Mycobacterium tuberculosis infection leads to pulmonary active disease in approximately 5-10% of exposed individuals. Both bacteria- and host-related characteristics influence latent infection and disease. Host genetic predisposition to develop TB may involve multiple genes and their polymorphisms. It was reported previously that interferon gamma (IFN-γ) and nitric oxide synthase 2 (NOS2) are expressed on alveolar macrophages from TB patients and are responsible for bacilli control; thus, we aimed this study at genotyping single nucleotide polymorphisms IFNG+874T/A SNP and NOS2A-954G/C SNP to estimate their role on TB susceptibility and determine whether these polymorphisms influence serum nitrite and NOx(-) production. This case-control study enrolled 172 TB patients and 179 healthy controls. Neither polymorphism was associated with susceptibility to TB. NOS2A-954G/C SNP was not associated with serum levels of nitrite and NOx(-). These results indicate that variants of IFNG+874T/A SNP and NOS2A-954G/C SNP do not influence TB susceptibility or the secretion of nitric oxide radicals in the study population.

IFNG polymorphisms are associated with tuberculosis in Han Chinese pediatric female population

Host genetic factors play a major role in determining differential susceptibility to human tuberculosis (TB), a re-emerging infectious disease throughout the world. Genetic variations in the IFNG gene coding for interferon gamma (IFN-γ), have been identified in TB patients. To investigate the association of the IFNG polymorphisms with TB susceptibility in Chinese pediatric population. A case-control study of 189 TB patients and 164 controls was performed using single-nucleotide polymorphism (SNP) analysis. Genomic DNA was extracted from leukocytes in peripheral blood. Three SNPs of IFNG, including -1616C/T (rs2069705), +874A/T (rs2430561), and +3234C/T (rs2069718), were selected for genotyping and analysis. The +874A and +3234C alleles were more frequent among TB patients (P = 0.108 and P = 0.088), especially in females (both P = 0.029), although this difference was not significant since Bonferroni corrected significance threshold was 0.025 (two of three SNPs were found to be in linkage disequilibrium). More pronounced differences for the +874 and +3234 polymorphisms were found under the genotype comparison between TB cases and controls in the total population [P = 0.026 (borderline non-significance) and P = 0.020, respectively], and in the female subgroup (P = 0.020 and P = 0.020). The dominant model of inheritance was shown to be significant for +874A and +3234C alleles (both P = 0.019) in the female subgroup. The +874A and +3234C alleles were more frequently found in extrapulmonary TB patients than in controls (P = 0.039). Haplotype analysis carried out on these three SNPs showed the TTT haplotype to be more frequent in controls than in TB cases, and this difference showed a strong significance (P = 0.005). The +874A and +3234C alleles may be related to TB susceptibility in the female subgroup in the Chinese pediatric population of North China. The higher rate of +874A (known to correlate with lower IFN-γ expression) in the extrapulmonary TB subgroup suggests a sufficient IFN-γ expression to be not only an important factor for the onset of TB disease but also for limiting its dissemination to lungs.

Non-tuberculous mycobacterial pulmonary infection in the immunocompetent host

Throughout much of the world, the incidence of non-tuberculous mycobacterial pulmonary infections in immunocompetent hosts is on the rise. These organisms are widespread in the natural environment; the explanation for what appears to be an increased susceptibility among human hosts is uncertain. Among more than 120 known species, the most common pathogenic isolate in the USA is Mycobacterium avium complex. The diagnosis of pulmonary disease caused by M. avium complex requires a compatible history, suggestive radiographic findings (on chest computed tomography) and microbiologic confirmation on culture of respiratory samples (sputum or direct lung sampling). Treatment options have improved with inclusion of macrolide antibiotics in a multi-drug regimen, but failure rates remain high (20-40%) even after a prolonged course of therapy. Newer, less toxic and more effective anti-mycobacterial agents are greatly needed for treatment of this increasingly common respiratory disease.

The -2518A/G polymorphism in the MCP-1 gene and tuberculosis risk: a meta-analysis

Background

The -2518A/G polymorphism in the monocyte chemoattractant protein-1 (MCP-1) gene has been implicated in the susceptibility to tuberculosis (TB), but the results are not conclusive. The aim of this study is to investigate the association between the -2518A/G polymorphism in the MCP-1 gene and the risk of tuberculosis by meta-analysis.

Methods

We searched Pubmed, Embase, CNKI and Wanfang databases, covering all studies until April 29^th, 2011. Statistical analyses were performed using the Revman4.2 and STATA10.0 software.

Results

A total of 5341 cases and 6075 controls in 13 case-control studies were included in the meta-analysis. The results indicated that the GG homozygote carriers had a 67% increased risk of TB compared with the A allele carriers (GG vs. GA+AA: OR = 1.67, 95%CI = 1.25–2.23, P = 0.0006). In the subgroup analysis by ethnicity, significant elevated risks were found in Asians and Latinos, but not in Africans (GG vs. GA+AA: OR = 1.79, 95%CI = 1.19–2.70 and P = 0.005 for Asians; OR = 2.15, 95%CI = 1.32–3.51 and P = 0.002 for Latinos; OR = 1.28, 95%CI = 0.45–3.64 and P = 0.65 for Africans).

Conclusion

This meta-analysis suggested that the -2518A/G polymorphism of MCP-1 gene would be a risk factor for TB in Asians and Latinos, while not in Africans.

Association of polymorphism +874 A/T of interferon-γ and susceptibility to the development of tuberculosis: meta-analysis

The immune defence against Mycobacterium tuberculosis is complex and involves multiple interacting cells. Studies in subjects with polymorphisms in genes for IFN or its receptor gene evaluate their relationship with mycobacterium infections. The purpose of this study was to analyze the evidence of the effect of polymorphism +874 A/T from interferon-γ on the occurrence of tuberculosis. We performed a meta-analysis of studies published between June 2002 and April 2012. The articles analyzed assessed the relationship between the polymorphism +874 A/T and the development of tuberculosis. The meta-analysis was performed with a random effect model, considering the heterogeneity among studies. Genotype TT showed a protective effect (OR, 0.77; 95% CI = 0.67-0.88) while genotype AA may be associated with increased susceptibility to developing tuberculosis (OR, 1.51; 95% CI = 1.38-1.65). In relation to alleles, we can verify that the A allele is related to the development of tuberculosis (OR, 1.56; 95% CI = 1.42-1.71). This information reinforces the importance of host genetics in the development of infectious diseases. Studies in this area can result in the promotion of new and more accurate genetic markers.

Association of IFNGR2 gene polymorphisms with pulmonary tuberculosis among the Vietnamese

Interferon-γ (IFN-γ) is a key molecule of T helper 1 (Th1)-immune response against tuberculosis (TB), and rare genetic defects of IFN-γ receptors cause disseminated mycobacterial infection. The aim of the present study was to investigate whether genetic polymorphisms found in the Th1-immune response genes play a role in TB. In our study, DNA samples were collected from two series of cases including 832 patients with new smear-positive TB and 506 unrelated individuals with no history of TB in the general population of Hanoi, Vietnam. Alleles of eight microsatellite markers located around Th1-immune response-related genes and single nucleotide polymorphisms near the promising microsatellites were genotyped. A set of polymorphisms within the interferon gamma receptor 2 gene (IFNGR2) showed a significant association with protection against TB (P = 0.00054). Resistant alleles tend to be less frequently found in younger age at diagnosis (P = 0.011). Luciferase assays revealed high transcriptional activity of the promoter segment in linkage disequilibrium with resistant alleles. We conclude that the polymorphisms of IFNGR2 may confer resistance to the TB development of newly infected individuals. Contribution of the genetic factors to TB appeared to be different depending on age at diagnosis.