Cytokine gene polymorphisms and cytokine levels in pulmonary tuberculosis

Polymorphisms in Immune Genes and Their Association with Tuberculosis Susceptibility: An Analysis of the African Population

Tuberculosis remains a global health concern, with substantial mortality rates worldwide. Genetic factors play a significant role in influencing susceptibility to tuberculosis. This review examines the current progress in studying polymorphisms within immune genes associated with tuberculosis susceptibility, focusing on African populations. The roles of various proteins, including Toll-like receptors, Dendritic Cell-Specific Intercellular Adhesion Molecule-3 Grabbing Non-Integrin, vitamin D nuclear receptor, soluble C-type lectins such as surfactant proteins A and D, C-type Lectin Domain Family 4 Member E, and mannose-binding lectin, phagocyte cytokines such as Interleukin-1, Interleukin-6, Interleukin-10, Interleukin-12, and Interleukin-18, and chemokines such as Interleukin-8, monocyte chemoattractant protein 1, Regulated upon activation, normal T-cell expressed and secreted are explored in the context of tuberculosis susceptibility. We also address the potential impact of genetic variants on protein functions, as well as how these findings align with the genetic polymorphisms not associated with tuberculosis. Functional studies in model systems provide insights into the intricate host-pathogen interactions and susceptibility mechanisms. Despite progress, gaps in knowledge remain, highlighting the need for further investigations. This review emphasizes the association of Single Nucleotide Polymorphisms with diverse aspects of tuberculosis pathogenesis, including disease detection and Mycobacterium tuberculosis infection.

Multi-epitope mRNA Vaccine Design that Exploits Variola Virus and Monkeypox Virus Proteins for Elicitation of Long-lasting Humoral and Cellular Protection Against Severe Disease

Human monkeypox represents a relatively underexplored infection that has received increased attention since the reported outbreak in May 2022. Due to its clinical similarities with human smallpox, this virus represents a potentially tremendous health problem demanding further research in the context of host-pathogen interactions and vaccine development. Furthermore, the cross-continental spread of monkeypox has reaffirmed the need for devoting attention to human poxviruses in general, as they represent potential bioterrorism agents. Currently, smallpox vaccines are utilized in immunization efforts against monkeypox, an unsurprising fact considering their genomic and phenotypic similarities. Though it offers long-lasting protection against smallpox, its protective effects against human monkeypox continue to be explored, with encouraging results. Taking this into account, this works aims at utilizing in silico tools to identify potent peptide-based epitopes stemming from the variola virus and monkeypox virus proteomes, to devise a vaccine that would offer significant protection against smallpox and monkeypox. In theory, a vaccine that offers cross-protection against variola and monkeypox would also protect against related viruses, at least in severe clinical manifestation. Herein, we introduce a novel multi-epitope mRNA vaccine design that exploits these two viral proteomes to elicit long-lasting humoral and cellular immunity. Special consideration was taken in ensuring that the vaccine candidate elicits a Th1 immune response, correlated with protection against clinically severe disease for both viruses. Immune system simulations and physicochemical and safety analyses characterize our vaccine candidate as antigenically potent, safe, and overall stable. The protein product displays high binding affinity towards relevant immune receptors. Furthermore, the vaccine candidate is to elicit a protective, humoral and Th1-dominated cellular immune response that lasts over five years. Lastly, we build a case about the rapidity and convenience of circumventing the live attenuated vaccine platform using mRNA vaccine technology.

Association of IFN-gamma and IL-10 gene variants with the risk of extrapulmonary tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) is a chronic infectious disease. Interferon-gamma (IFN-γ) is an important cytokine imparting resistance to mycobacterial diseases. It is believed that IFN-γ and Interleukin-10 (IL-10) play divergent roles in the host immune system against MTB infection. IL-10 is an important inhibitory cytokine and helps balancing the inflammatory and immune responses. IL-10 is involved in down regulation of Th1 cytokines, MHC class II antigen and co-stimulatory molecular expression on macrophages, while IFN-γ results in macrophage activation allowing them to exert the microbicidal role. The objectives were to find out the association of IL-10 (-1082 A/G) and IFN-γ (+874 A/T) single nucleotide polymorphisms (SNPs) with extrapulmonary tuberculosis in ethnic Kashmiri population. A total of 100 extrapulmonary tuberculosis cases and 102 healthy controls were analyzed for IL-10 (-1082 A/G) and IFN- γ (+874 A/T) SNPs using Allele-Specific PCR. We found a significant association of IFN-γ + 874 'TT' genotype with extrapulmonary tuberculosis (p = 0.006) and in case of IL-10 (-1082 A/G) we found a significant association with extrapulmonary tuberculosis under recessive model (GG vs GA + AA) (p = 0.03) in Kashmiri population. IL-10 (-1082 A/G) and IFN-γ (+874 A/T) have a significant association with extrapulmonary tuberculosis in ethnic Kashmiri population.

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.

Lack of association between polymorphism of IL-2 -330T/G and pulmonary tuberculosis among Caucasians

This meta-analysis was conducted to assess the consistency and strength of the relationship between polymorphism of IL-2 -330T/G and susceptibility to pulmonary tuberculosis (TB). PubMed, Web of Knowledge and CNKI were searched to find eligible studies about the relationship between IL-2 -330T/G polymorphism and susceptibility to pulmonary TB. A total of eight studies comprising 971 cases and 1519 controls were grouped together for the purpose of elucidating the relationship between polymorphism of IL-2 -330T/G and pulmonary TB susceptibility. The allele model (G vs. T: odds ratio (OR) = 1.34; 95% confidence interval (CI) 1.05–1.71, P_het = 0.001) and the recessive model (GG+GT vs. TT: OR = 1.60; 95% CI 1.08–2.38, P_het = 0.0001) showed an increased risk of development of pulmonary TB. However, the homozygous model (GG vs. TT: OR = 1.74; 95% CI 0.98–3.09, P_het = 0.0005) and the dominant model (GG vs. TT + TG: OR = 1.30; 95% CI = 0.80-2.14, P_het =  0.001) failed to show an increased incidence of pulmonary TB. When analysis was stratified by ethnicity, no obvious associations were identified in the Caucasian subgroup under all four genetic models. Additionally, heterogeneity disappeared in the analysis of Caucasian subgroup. Our combined data suggested that there was no association between IL-2 -330T/G polymorphism and pulmonary TB among Caucasians.

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.

Interferon-gamma release assay performance in northeastern Brazil: influence of the IFNG+874 A>T polymorphism

Introduction

Latent tuberculosis infection diagnosis based on the release of interferon-gamma in cultures of peripheral blood cells stimulated with Mycobacterium tuberculosis antigens has replaced the tuberculin skin test in many countries with low tuberculosis prevalence. The IFN-γ production can be influenced by genetic polymorphisms, of which the IFNG + 874 (rs62559044) locus is the most studied. We investigated the possible influence of the IFNG + 874 A/T polymorphism on interferon-gamma test performance.

Methods

Patients diagnosed with pulmonary tuberculosis (75), volunteers with positive tuberculin skin test (70) and healthy volunteers with negative tuberculin skin test and no history of contact with tuberculosis (57) were evaluated regarding the IFNG + 874 genotype and the IFN-γ levels in whole blood cultures performed using an interferon-gamma commercial kit (QuantiFERON-TB^® Gold In-Tube).

Results

IFN-γ production was not influenced by the IFNG + 874 genotype, regardless of antigen or mitogen-based stimulation, which suggests that other genes may influence IFN-γ production in response to mycobacteria. The IFNG + 874 polymorphism was found to exert no influence over QFT-IT test sensitivity in our study.

Conclusions

The IFNG + 874 polymorphism was not shown to influence QuantiFERON-TB^® Gold In-Tube test performance in an admixed population from northeastern Brazil.

Association between the IL-6 gene polymorphism and tuberculosis risk: a meta-analysis

Background

The gene polymorphism of interleukin-6 (IL-6) has been shown to be implicated in tuberculosis susceptibility in many studies, but with conflicting results. This study aimed to provide more accurate estimation of the relationship between IL-6 gene polymorphism and tuberculosis risk through a meta-analysis.

Method

A literature search was performed in PubMed, EMBASE, and other databases. Data were retrieved, and pooled odds ratio (OR) with 95% CI were calculated. Statistical analyses were performed by using STATA 12.0.

Results

Twelve publications with 2635 cases and 3049 controls were included. The pooled analysis demonstrated significant evidence of association between IL-6 (-174G/C) and low risk of tuberculosis in dominant model (CC+GC vs GG: OR =0.693, 95% CI 0.581-0.826, p<0.001). Subgroup analysis got similar results for IL-6 (-174G/C) in Asians and Latinos, but the significance did not exist in Caucasians. IL-6 (-572C/G) polymorphism was also associated with low risk of tuberculosis in dominant model (CC+GC vs GG: OR =0.719, 95% CI 0.577-0.896, p=0.003). No publication bias was detected in either of the polymorphisms.

Conclusion

In summary, IL-6 -572 C/G polymorphism may be associated with a decreased risk of tuberculosis, and C allele is the protective factor against tuberculosis for IL-6 -174G/C among Asians and Latinos, but not in Caucasian population.

IL-10 -1082 A>G (rs1800896) polymorphism confers susceptibility to pulmonary tuberculosis in Caucasians but not in Asians and Africans: a meta-analysis

Background: Earlier studies have shown that interlukin-10 (IL-10) -1082 A>G gene polymorphism is implicated in susceptibility to pulmonary tuberculosis (PTB), but their results are inconsistent and inconclusive. In the present study, a meta-analysis was performed to analyze the potential association between IL-10 -1082 A>G gene polymorphism and PTB susceptibility.

Methods: A quantitative synthesis was done using PubMed (Medline), EMBASE, and Google Scholar web databases search and meta-analysis was performed by calculating pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) for all the genetic models.

Results: A total of 22 eligible studies comprising 4956 PTB cases and 6428 healthy controls were included in the analysis. We did not observe any increased or decreased risk of PTB in allelic contrast (G vs. A: P=0.985; OR = 1.001, 95% CI = 0.863–1.162), homozygous (GG vs. AA: P=0.889; OR = 1.029, 95% CI = 0.692–1.529), heterozygous (GA vs. AA: P=0.244; OR = 0.906, 95% CI = 0.767–1.070), dominant (GG + AG vs. AA: P=0.357; OR = 1.196, 95% CI = 0.817–1.752), and recessive (GG vs. AA + AG: P=0.364; OR = 0.921, 95% CI = 0.771–1.100) genetic models. Likewise, no association of IL-10 -1082 A>G polymorphism with PTB risk was observed in Asian and African population for all the genetic models. Interestingly, the dominant model (GG + AG vs. AA: P=0.004; OR = 1.694, 95% CI = 1.183–2.425) demonstrated increased risk of PTB in Caucasian population.

Conclusions: This meta-analysis concludes that IL-10 -1082 A>G gene polymorphism is not significantly associated with overall, Asian and African population. However, this polymorphism is associated with Caucasian population.

Current immunogenetic predisposition to tuberculosis in the Moroccan population

Tuberculosis (TB) is a serious infectious disease that kills approximately two million people per year, particularly in low- and middle-income countries. Numerous genetic epidemiology studies have been conducted of many ethnic groups worldwide and have highlighted the critical impact of the genetic environment on TB distribution. Many candidate genes associated with resistance or susceptibility to TB have been identified. In Morocco, where TB is still a major public health problem, various observations of clinical, microbiological and incidence distribution are heavily affected by genetic background and external environment. Morocco has almost the same clinical profile as do other North African countries, mainly the increase in more extrapulmonary than pulmonary forms of the diseases, when compared to European, Asian or American populations. In addition, a linkage analysis study that examined Moroccan TB patients identified a unique chromosome region that had a strong association with the risk of contracting TB. Other genes in the Moroccan population that were found to be associated seem to be involved predominantly in modulating the innate immunity. In this review, we appraise the major candidate genes that have been reported in Moroccan immunogenetic studies and discuss their updated role in TB, particularly during the first phase of the immune response to Mycobacterium tuberculosis (Mtb) infection.

Novel mutations in the exon 5, intron 2 and 3' UTR regions of IL-12B gene were observed in clinically proven tuberculosis patients of south India

Interleukin-12 (IL-12) is formed by the interaction of IL-12p35 and IL-12p40 expressed independently from IL-12A and IL-12B genes. This interleukin plays prominent role in the T-helper type-1 (Th1) response against intracellular pathogens. Variations in IL-12B gene causes disruption of various activities one of them is suppression of Th1 response and is one of the characteristic features observed in patients with active tuberculosis. Hence, in the present study IL-12B gene status was evaluated in 50 new sputum smear-positive pulmonary tuberculosis patients (NSP-PTB) as identified by Ziehl-Nielsen (ZN) staining and 50 apparently healthy control subjects (HCS) who were sputum smear-negative. The sequence analysis showed novel missense mutations p.Ser205Ile, p.Leu206Glu, p.Pro207Ser, p.Glu209Lys, p.Val210Ser, p.(Ser205_Cys327delinsIleGlu) and p.(Lys217_Leu218delinsIle) were found in exon 5 of the IL-12B gene in nine patients resulting formation of inactive IL-12 and three patients showed novel frame shift mutations p.(Asn222Leufs∗23) in exon 5 of causing the formation of truncated protein. Several mutations were noted in intron 2 of the IL-12B gene in 5 patients and in 13 patients mutations were observed in 3' UTR region. All together 30/50 patients (60%) showed mutations in IL-12B gene. Decreased levels of interferon-gamma (IFN-γ) and IL-12 as determined by ELISA and flow cytometry were observed in the peripheral blood mononuclear cell culture supernatants in TB patients having mutations compared with control subjects. Further, in silico analysis revealed due to frame shift mutations in exon 5 at Asn222 resulted in deletion of functional fibronectin type-III (FN3) domain which leads to formation of inactive IL-12 in these patients.

IL-6 and IL-18 cytokine gene variants of pulmonary tuberculosis patients with co-morbid diabetes mellitus and their household contacts in Hyderabad

PURPOSE

Association of cytokine genes reflects their susceptibility towards infection and disease in household contacts (HHC) of pulmonary tuberculosis (PTB) patients. Hyperglycemia, a common factor in diabetics might influence their risk towards mycobacterium tuberculosis infection and disease development. This study determines the association of IL-6 and IL-18 cytokine gene variants of TB patients with diabetes mellitus (TBDM) and their HHC in Hyderabad.

METHODS

Single nucleotide polymorphisms of IL-6 (-174 G>C and -572 G>C) and IL-18 (-137 G>C and -607 C>A) cytokine genes were genotyped by Amplification Refractory Mutation System and Restriction Fragment Length polymerase chain reaction in total of 705 subjects comprising of TBDM, their HHC, PTB, DM and Healthy controls (HC).

RESULTS

At IL-6 -174G>C variant, GG genotype, G allele in TBDM and TBDM HHC, at -572G>C variant, C allele in TBDM and GG haplotype in TBDM HHC were showing positive association, however DM have not shown any association at IL-6 polymorphic sites. With respect to the IL-18 gene polymorphisms, at -137 G>C variant, GG genotype was positively associated in PTB while at -607 C>A variant positive association was shown with AC genotype in TBDM, their HHC and DM; GACC diplotype in TBDM and GCGC in PTB.

CONCLUSION

Our findings suggest that susceptible combination of IL-6 and IL-18 cytokine genes associated with disease in the HHCs highlight their risk of inclination towards the disease.

The Goldilocks model of immune symbiosis with Mycobacteria and Candida colonizers

Mycobacteria and Candida species include significant human pathogens that can cause localized or disseminated infections. Although these organisms may appear to have little in common, several shared pathways of immune recognition and response are important for both control and infection-related pathology. In this article, we compare and contrast the innate and adaptive components of the immune system that pertain to these infections in humans and animal models. We also explore a relatively new concept in the mycobacterial field: biological commensalism. Similar to the well-established model of Candida infection, Mycobacteria species colonize their human hosts in equilibrium with the immune response. Perturbations in the immune response permit the progression to pathologic disease at the expense of the host. Understanding the immune factors required to maintain commensalism may aid with the development of diagnostic and treatment strategies for both categories of pathogens.

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.

The association of interleukin-10 -1082, -819, -592 polymorphisms and tuberculosis risk

Objectives:

To assess the association between interleukin (IL)-10 -1082, -819, -592 polymorphisms and tuberculosis (TB) risk.

Methods:

This study was conducted between July and October 2014 in West China Hospital, Chengdu, Sichuan, China. We searched and collected data from PUBMED, EMBASE, Web of Science, China National Knowledge Infrastructure, VIP, and WANGFANG up to October 2014.

Results:

A total of 37 studies were enrolled, including 8625 TB cases, and 9928 healthy controls. The IL-10-1082G/A polymorphism was found to be associated with TB susceptibility in Caucasian (GG versus GA+AA, odds ratio [OR] - 1.83, 95% confidence interval [CI] - 1.03-3.24). The IL-10-819C/T polymorphism was related to TB susceptibility among Asians (C versus T, OR - 0.88, 95% CI - 0.81-0.97; CC versus TT: OR - 0.79, 95% CI - 0.64-0.97; CC+CT versus TT: OR - 0.87, 95% CI - 0.77-0.98; CC versus CT+TT: OR - 0.82, 95% CI - 0.68-0.98). The IL-10-592C/A polymorphism was in association with TB susceptibility in Asians (C versus A: OR - 0.74, 95% CI - 0.65-0.85; CC versus AA: OR - 0.55, 95% CI - 0.41-0.75; CA versus AA: OR - 0.73, 95% CI - 0.60-0.89; CC+CA versus AA: OR - 0.69, 95% CI 0.58-0.83; CA versus AA: OR - 0.66, 95% CI 0.51-0.86), Caucasian (C versus A: OR - 1.25, 95% CI - 1.08-1.45; CC versus CA+AA: OR-1.48, 95% CI - 1.16-1.89), and Europeans (C versus A: OR - 1.31, 95% CI - 1.02-1.67; CC versus AA: OR - 1.88, 95% CI - 1.05-3.37).

Conclusion:

This meta-analysis suggests that IL-10-1082G/A, IL-819C/T, and IL-592C/A polymorphisms might be associated with TB susceptibility in certain ethnicities.

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.

Revisiting the Heterogeneous IFN-γ Response of Bacille of Calmette-Guérin (BCG)-Revaccinated Healthy Volunteers in a Randomized Controlled Trial: Effect of the Body Mass Index and of the IFNG+874 A/T Polymorphism

In trials evaluating the immune responses to Bacille of Calmette-Guérin (BCG), the genetic background and the nutritional status are host-related factors that could affect the heterogeneity in these parameters. The IFNG+874 A/T (rs 62559044) polymorphism has been reported to influence the IFN-γ production by BCG-vaccinated individuals challenged in vitro with mycobacterial antigens. The body mass index (BMI) is a proxy for the nutritional status and has been associated both with the susceptibility to tuberculosis and with the IFN-γ response. We show that although the IFNG+874 A/T polymorphism was not associated with the heterogeneity of IFN-γ production in a randomized controlled trial that evaluated long-term immune responses to BCG revaccination previously conducted in Salvador, Bahia, Brazil, the effect of this polymorphism on the observed increase in IFN-γ production among revaccinated subjects was adjusted in individuals with a low BMI.

Alleles of HLA-DRB1*04 Associated with Pulmonary Tuberculosis in Amazon Brazilian Population

Immunogenetic host factors are associated with susceptibility or protection to tuberculosis (TB). Strong associations of HLA class II genes with TB are reported. We analyzed the HLA-DRB1*04 alleles to identify subtypes associated with pulmonary TB and their interaction with risk factors such as alcohol, smoking, and gender in 316 pulmonary TB patients and 306 healthy individuals from the Brazilian Amazon. The HLA-DRB1*04 was prevalent in patients with pulmonary TB (p<0.0001; OR = 2.94; 95% CI = 2.12 to 4.08). Direct nucleotide sequencing of DRB1 exon 2 identified nine subtypes of HLA-DRB1*04. The subtype HLA-DRB1*04:11:01 (p = 0.0019; OR = 2.23; 95% CI = 1.34 to 3.70) was associated with susceptibility to pulmonary TB while DRB1*04:07:01 (p<0.0001; OR = 0.02; 95% CI = 0.001 to 0.33) to protection. Notably, the interaction between alcohol and HLA-DRB1*04:11:01 increased the risk for developing pulmonary TB (p = 0.0001; OR = 51.3; 95% CI = 6.81 to 386). Multibacillary pulmonary TB, the clinical presentation of disease transmission, was strongly associated with interaction to alcohol (p = 0.0026; OR = 11.1; 95% CI = 3.99 to 30.9), HLA-DRB1*04:11:01 (p = 0.0442; OR = 2.01; 95% CI = 1.03 to 3.93) and DRB1*04:92 (p = 0.0112; OR = 8.62; 95% CI = 1.63 to 45.5). These results show that HLA-DRB1*04 are associated with pulmonary TB. Interestingly, three subtypes, DRB1*04:07:01, DRB1*04:11:01 and DRB1*04:92 of the HLA-DRB1*04 could be potential immunogenetic markers that may help to explain mechanisms involved in disease development.

IL-10 Polymorphisms and Tuberculosis Susceptibility: An Updated Meta-Analysis

PURPOSE

The association of interleukin-10 (IL-10) polymorphisms (-1082G/A, -819C/T, -592A/C) and interleukin-6 (IL-6) poly-morphisms (-174G/C) with tuberculosis (TB) risk has been widely reported. However, the results are controversial. To clarify the role of these polymorphisms in TB, we performed a meta-analysis of all available and relevant published studies.

MATERIALS AND METHODS

Based on comprehensive searches of the PubMed, Medline, Embase, Web of Science, Elsevier Science Direct and Cochrane Library database, we identified outcome data from all articles estimating the association between IL-10 and IL-6 polymorphisms and TB risk.

RESULTS

The results indicated significant association of the allele model, heterozygous model and dominant model of IL-6 -174G/C polymorphism with decreased risk of TB. In the stratified analysis by ethnicity, significantly increased risk was observed for IL-10 -1082G/A polymorphism in Europeans under recessive model, for IL-10 -819C/T polymorphism in Asians under heterozygous model and dominant model and IL-10 -592A/C polymorphism in Asians under Allele model, homozygous model and recessive model. Moreover, significantly decreased risk of TB was associated with Asians for IL-6 -174C/G polymorphism in allele model, heterozygous model and dominant model. We also performed the analyses by sample types in IL-10 -1082G/A polymorphism, and observed significantly increased TB risk in mixed group under homozygous model.

CONCLUSION

The results suggested that the IL-10 -1082G/A polymorphism is associated with increased TB risk in Europeans, while IL-10 -819C/T and IL-10 -592A/C polymorphisms in Asians. However, IL-6 -174G/C polymorphism might be a genetic risk factor that decreases TB susceptibility in Asians.

IL-1β+3953C/T, -511T/C and IL-6 -174C/G polymorphisms in association with tuberculosis susceptibility: A meta-analysis

BACKGROUND

Studies of the association between the interleukin-1β gene (IL-1β) (+3953C/T, -511T/C) and interleukin-6 gene (IL-6) (-174G/C) polymorphisms and susceptibility to tuberculosis (TB) have yielded inconsistent results. The aim of this study was to investigate the relationship between these polymorphisms and TB risk by this meta-analysis.

METHODS

We systematically searched published literatures on IL-1β gene and IL-6 gene polymorphisms and tuberculosis risk by the PubMed, Medline, Embase, Web of Science, Elsevier Science Direct and Cochrane Library databases, and identified outcome data from all articles. Statistical analysis was performed using Stata 12.0. A total of 15 studies comprising 3983TB patients and 3996 controls were included in the present study.

RESULTS

We found that the IL-6 -174C/G polymorphism might be associated with decreased risk of TB (C vs. G: OR=0.77, 95% CI=0.64-0.91; CG vs. GG: OR=0.72, 95% CI=0.57-0.90; CC+CG vs. GG: OR=0.71, 95% CI=0.57-0.88). In the stratified analysis by ethnicity, significantly decreased risk were observed for IL-1β -511T/C polymorphism in Africans (C allele vs. T allele: OR=0.86, 95% CI=0.74-0.99; CC vs. TT: OR=0.74, 95% CI=0.55-0.99). Moreover, the IL-6 -174 C/G polymorphism was also associated with decreased risk of TB in Asians (C vs. G: OR=0.71, 95% CI=0.54-0.93; CG vs. GG: OR=0.61, 95% CI=0.44-0.85; CC+CG vs. GG: OR=0.63, 95% CI=0.46-0.86). We also performed the analyses by sample types in IL-6 -174 C/G polymorphism, and significant decreased TB risk was observed in pulmonary tuberculosis group (C allele vs. G allele: OR=0.69, 95% CI=0.52-0.93; CG vs. GG: OR=0.69, 95% CI=0.52-0.91; CC+CG vs. GG: OR=0.71, 95% CI=0.55-0.93), and pulmonary tuberculosis plus extra-pulmonary tuberculosis mixed group (CC vs. GG: OR=0.44, 95% CI=0.22-0.88; CC vs. CG+GG: OR=0.48, 95% CI=0.25-0.94).

CONCLUSIONS

This meta-analysis indicates that the IL-1β -511T/C polymorphism is associated with TB decreased risk in Africans, and IL-6 -174C/G polymorphism in Asians. Further well-designed, large scale studies are required to confirm this conclusion.

Interleukin-10 promoter gene polymorphisms and susceptibility to tuberculosis: a meta-analysis

Objective

As an update to other recent meta-analyses, the purpose of this study was to explore whether interleukin-10 (IL-10) polymorphisms and their haplotypes contribute to tuberculosis (TB) susceptibility.

Methods

We searched for published case-control studies examining IL-10 polymorphisms and TB in PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), Wanfang databases and the Chinese National Knowledge Infrastructure (CNKI). Odds ratios (ORs) with 95% confidence intervals (CIs) were used to calculate the strengths of the associations.

Results

A total of 28 studies comprising 8,242 TB patients and 9,666 controls were included in the present study. There were no significant associations between the -1082G/A, -819C/T, and -592A/C polymorphisms and TB in the pooled samples. Subgroup analyses revealed that the -819T allele was associated with an increased TB risk in Asians in all genetic models (T vs. C: OR=1.17, 95% CI=1.05-1.29, P=0.003; TT vs. CC: OR=1.37, 95% CI=1.09-1.72, P=0.006; CT+TT vs. CC: OR=1.33, 95% CI=1.09-1.63, P=0.006; TT vs. CT+CC: OR=1.17, 95% CI=1.02-1.35, P=0.03) and that the -592A/C polymorphism was significantly associated with TB in Europeans under two genetic models (A vs. C: OR=0.77, 95% CI=0.60-0.98, P=0.03; AA vs. CC: OR=0.53, 95% CI=0.30-0.95, P=0.03). Furthermore, the GCC IL-10 promoter haplotype was associated with an increased risk of TB (GCC vs. others: P=1.42, 95% CI=1.02-1.97, P=0.04). Subgroup analyses based on ethnicity revealed that the GCC haplotype was associated with a higher risk of TB in Europeans, whereas the ACC haplotype was associated with a lower TB risk in both Asians and Europeans.

Conclusions

This meta-analysis suggests that the IL-10-819T/C polymorphism is associated with the risk of TB in Asians and that the IL-10-592A/C polymorphism may be a risk factor for TB in Europeans. Furthermore, these data indicate that IL-10 promoter haplotypes play a vital role in the susceptibility to or protection against the development of TB.

Insights into pathophysiology of dystropy through the analysis of gene networks: an example of bronchial asthma and tuberculosis

Co-existence of bronchial asthma (BA) and tuberculosis (TB) is extremely uncommon (dystropic). We assume that this is caused by the interplay between genes involved into specific pathophysiological pathways that arrest simultaneous manifestation of BA and TB. Identification of common and specific genes may be important to determine the molecular genetic mechanisms leading to rare co-occurrence of these diseases and may contribute to the identification of susceptibility genes for each of these dystropic diseases. To address the issue, we propose a new methodological strategy that is based on reconstruction of associative networks that represent molecular relationships between proteins/genes associated with BA and TB, thus facilitating a better understanding of the biological context of antagonistic relationships between the diseases. The results of our study revealed a number of proteins/genes important for the development of both BA and TB.

Single nucleotide polymorphic macrophage cytokine regulation by Mycobacterium tuberculosis and drug treatment

Aim: To investigate the survival of Mycobacterium tuberculosis in primary macrophages with SNPs affecting cytokine secretion under treatment with drugs in solution or microparticles. Materials & methods: Volunteers were typed for TNF (-308G/A), IL-10 (-1082A/G) and IL-4 (-590C/T). Monocyte-derived macrophages (MDMs) were infected in vitro. Cytokine secretion and survival of intracellular bacilli were estimated. Results: IL-10 AG associated with high secretion in uninfected and infected MDMs (p < 0.05) and was reduced more effectively by microparticles than drugs, irrespective of genotype (p < 0.05). Differences were observed between IL-4 secretion by MDMs of CC and TT genotypes (p = 0.1). Bacteria proliferated more in MDMs from volunteers with higher IL-4 levels (p = 0.05). Microparticles showed higher efficacy (p = 0.05) than drugs. Conclusion: IL-4 and IL-10 SNPs affect the ability of macrophages to counter infection with M. tuberculosis. Microparticles elicit favorable macrophage cytokines regardless of SNPs.

Original submitted 5 August 2013; Revision submitted 27 November 2013

Association between IL-10 gene polymorphisms and susceptibility of tuberculosis: evidence based on a meta-analysis

Background

A number of observational studies have been conducted to investigate the association of IL-10 gene polymorphisms with tuberculosis (TB) susceptibility. However, the results of different studies were inconsistent. The aim of this study was to investigate the relationship between IL-10 -1082G/A, -819T/C, and -592A/C polymorphisms and TB risk by meta-analysis.

Methods

A literature search was conducted among six English databases (PubMed, Embase, Web of Science, Science Direct, SpringerLink and EBSCO) and two Chinese databases (Wanfang and Chinese National Knowledge Infrastructure databases) to identify studies involving association between IL-10 −1082G/A, −819T/C, and −592A/C polymorphisms and TB susceptibility before May. 2013. Statistical analysis was performed using Revman 5.0 and Stata 12.0.

Results

A total of 31 studies with 6,559 cases and 7,768 controls were included in this meta-analysis. The results showed that three polymorphisms (-1082G/A, -819T/C, and -592A/C) in the IL-10 gene were not associated with the risk of TB in general population. In the subgroup analysis by ethnicity, IL-10 -1082G/A polymorphism was associated with TB risk in Europeans (AA+AG vs. GG: OR =  0.57, 95% CI = 0. 0.37–0.89, P = 0.01) and Americans (AA+AG vs. GG: OR =  0.39, 95% CI = 0.27–0.57, P<0.01), and IL-10 -819T/C (C allele vs. T allele: OR = 0.83, 95% CI = 0.72–0.96, P = 0.01) and -592A/C (CC+AC vs. AA: OR =  0.65, 95% CI = 0.49–0.85, P = 0.002) polymorphisms were significantly associated with TB risk in Asians.

Conclusion

This meta-analysis provides strong evidence that IL-10-1082G/A polymorphism was associated with TB risk in Europeans and Americans, and IL-10 -819T/C and -592A/C polymorphisms could be risk factors for TB in Asians. Additional well designed large studies were required for the validation of our results.

rs2243268 and rs2243274 of Interleukin-4 (IL-4) gene are associated with reduced risk for extrapulmonary and severe tuberculosis in Chinese Han children

Interleukin-4 (IL-4) and IL-10, which are produced by Th2 cells, serve as anti-inflammatory cytokines in the immune responses to tuberculosis (TB). In order to investigate the association between susceptibility to TB and single-nucleotide polymorphisms (SNPs) of the IL-4 and IL-10 genes, a case-control study including 346 TB patients and 374 healthy controls was performed in Chinese Han children in North China. Though no significant differences in the allelic and genotypic distributions of SNPs of these two genes were observed between control group and TB group, rs2243268-A and rs2243274-G of the IL-4 gene were associated with reduced risk of developing extrapulmonary tuberculosis (EPTB) (Prs2243268=0.005 and Prs2243274=0.004) and severe TB (Prs2243268=0.003 and Prs2243274=0.003). The haplotype comprising rs2243268-A and rs2243274-G was found to be a resistance factor against EPTB and severe TB. In addition, after stimulation with inactivated H37Rv, blood samples of the rs2243268 AA+AC carriers showed significantly reduced IL-10 production (P=0.045) compared to the CC carriers. In conclusion, rs2243268-A and rs2243274-G of the IL-4 gene were found to confer resistance to EPTB and severe TB in Chinese Han children.

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.

Association of IL-10 and CCL5 single nucleotide polymorphisms with tuberculosis in the Sudanese population

OBJECTIVE

To investigate the genetic determinants for developing tuberculosis in Sudan.

METHODS

Case study of 232 patients with tuberculosis and 206 healthy matched controls from Sudan. In the study population, three single nucleotide polymorphisms (SNPs) in the promoter regions of CCL5 and two in the promoter region of IL-10 were genotyped using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). These five SNPs influence the expression of these genes.

RESULTS

There were significant differences in allele distribution for CCL5 -28 C/G (rs 2280788) and IL-10 -592 A/C (rs1800872) in patients with tuberculosis compared with healthy controls.

CONCLUSION

This indicates that the genotypes obtained for CCL5 and IL-10 are associated with an increased risk of developing active TB.

Genetic polymorphism and immune response to tuberculosis in indigenous populations: a brief review

We systematically reviewed studies of the immune response to tuberculosis and the genetic polymorphisms associated with Th1- or Th2-mediated cytokine expression in indigenous populations. A bibliographic search was performed on the Medline and ISI databases and included studies published between January 1980 and October 2011. The search terms were tuberculosis, American Indians, Amerindian, indigenous, Indians, native people, aboriginal, immun*, host immune, immune response, cytokine*, polymorphism*, and gene. Regardless of their design, studies that evaluated immunoglobulin, cytokine levels and genetic polymorphisms that altered cytokine expression were included. Thirteen studies met the inclusion criteria. The majority of studies were performed in Latin America, and five investigated the Warao ethnic group of Venezuela. Most of the investigations indirectly evaluated the immune response. Higher anergy to the tuberculin skin test, higher IgG4 and IgM levels, higher IL-5 production and lower TNF-α, IL-12p40 and IFN-γ production were found in the indigenous populations. The studies also reported a predominantly Th2-type response in these populations and a possibly higher susceptibility to tuberculosis. A better understanding of the relevant genetic polymorphisms and their role in immune regulation would help to clarify the immunogenetic mechanisms of TB infection in these populations. This information would be useful for identifying new treatments and preventing infection and progression to active disease.

Cytokine Polymorphisms, Their Influence and Levels in Brazilian Patients with Pulmonary Tuberculosis during Antituberculosis Treatment

Cytokines play an essential role during active tuberculosis disease and cytokine genes have been described in association with altered cytokine levels. Therefore, the aim of this study was to verify if IFNG, IL12B, TNF, IL17A, IL10, and TGFB1 gene polymorphisms influence the immune response of Brazilian patients with pulmonary tuberculosis (PTB) at different time points of antituberculosis treatment (T1, T2, and T3). Our results showed the following associations: IFNG +874 T allele and IFNG +2109 A allele with higher IFN-γ levels; IL12B +1188 C allele with higher IL-12 levels; TNF −308 A allele with higher TNF-α plasma levels in controls and mRNA levels in PTB patients at T1; IL17A A allele at rs7747909 with higher IL-17 levels; IL10 −819 T allele with higher IL-10 levels; and TGFB1 +29 CC genotype higher TGF-β plasma levels in PTB patients at T2. The present study suggests that IFNG +874T/A, IFNG +2109A/G, IL12B +1188A/C, IL10 −819C/T, and TGFB1 +21C/T are associated with differential cytokine levels in pulmonary tuberculosis patients and may play a role in the initiation and maintenance of acquired cellular immunity to tuberculosis and in the outcome of the active disease while on antituberculosis treatment.

Interleukin-2 gene polymorphism in Turkish patients with Behçet's disease and its association with ocular involvement

Behçet's disease (BD) is a chronic immune-mediated systemic disease, characterized by oral and genital lesions and ocular inflammation. Several cytokine genes may play crucial roles in host susceptibility to BD, because the cytokine production capacity varies among individuals and depends on the cytokine gene polymorphisms. The association of the interleukin (IL)-2 gene polymorphisms with the susceptibility to BD was investigated in this study. DNA samples were obtained from a Turkish population of 97 patients with BD and 76 healthy control subjects. Polymorphisms of IL-2 gene at position -330 and +166 were determined using the polymerase chain reaction with sequence-specific primers. In the patients with BD, there was a significantly increased frequency of IL-2 -330 GT genotype. Interestingly, we demonstrated that the frequencies of IL-2 -330 GT and IL-2 + 166 GG genotypes were increased in BD patients with ocular involvement, whilst IL-2 -330 TT genotype was significantly decreased. Also, analysis of allele frequency demonstrated that the presence of G allele at position +166 of IL-2 seems to be a risk factor for ocular involvement. These results reveal that IL-2 -330 GT genotype may be a susceptibility factor for BD, whereas IL-2 -330 TT genotype seems to display a protective association with BD. Additionally, IL-2 gene polymorphisms might be associated with ocular involvement in BD.

Levels of interferon-gamma increase after treatment for latent tuberculosis infection in a high-transmission setting

Objectives. We investigated IFN-γ levels before and after a six month course of isoniazid among individuals with latent tuberculosis infection (LTBI) in a high-transmission setting. Design. A total of 26 household contacts of pulmonary tuberculosis patients who were positive for LTBI by tuberculin skin test completed six months of treatment and submitted a blood sample for a follow-up examination. The IFN-γ response to Mycobacterium tuberculosis-specific antigens was measured, and the results before and after the completion of LTBI treatment were compared. Results. Of the 26 study participants, 25 (96%) showed an IFN-γ level higher than their baseline level before treatment (P ≤ 0.001). Only one individual had a decreased IFN-γ level after treatment but remained positive for LTBI. Conclusion. In a high-transmission setting, the IFN-γ level has increased after LTBI treatment. Further studies must be undertaken to understand if this elevation is transient.

Innate immune gene polymorphisms in tuberculosis

Tuberculosis (TB) is a leading cause worldwide of human mortality attributable to a single infectious agent. Recent studies targeting candidate genes and "case-control" association have revealed numerous polymorphisms implicated in host susceptibility to TB. Here, we review current progress in the understanding of causative polymorphisms in host innate immune genes associated with TB pathogenesis. We discuss genes encoding several types of proteins: macrophage receptors, such as the mannose receptor (MR, CD206), dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN, CD209), Dectin-1, Toll-like receptors (TLRs), complement receptor 3 (CR3, CD11b/CD18), nucleotide oligomerization domain 1 (NOD1) and NOD2, CD14, P2X7, and the vitamin D nuclear receptor (VDR); soluble C-type lectins, such as surfactant protein-A (SP-A), SP-D, and mannose-binding lectin (MBL); phagocyte cytokines, such as tumor necrosis factor (TNF), interleukin-1β (IL-1β), IL-6, IL-10, IL-12, and IL-18; chemokines, such as IL-8, monocyte chemoattractant protein 1 (MCP-1), RANTES, and CXCL10; and other important innate immune molecules, such as inducible nitric oxide synthase (iNOS) and solute carrier protein 11A1 (SLC11A1). Polymorphisms in these genes have been variably associated with susceptibility to TB among different populations. This apparent variability is probably accounted for by evolutionary selection pressure as a result of long-term host-pathogen interactions in certain regions or populations and, in part, by lack of proper study design and limited knowledge of molecular and functional effects of the implicated genetic variants. Finally, we discuss genomic technologies that hold promise for resolving questions regarding the evolutionary paths of the human genome, functional effects of polymorphisms, and corollary impacts of adaptation on human health, ultimately leading to novel approaches to controlling TB.

IFN-γ +875 microsatellite polymorphism as a potential protection marker for leprosy patients from Amazonas state, Brazil

Polymorphisms present in the first intron of IFN-γ may have an important role in the regulation of the immune response, which could have functional consequences for gene transcription. Leprosy patients are characterized by different immune responses in different clinical forms. We investigated a possible association of the +874 polymorphism and CA repeats present in the first intron of IFN-γ with susceptibility to leprosy and with the manifestation of the different clinical forms. Nucleotide sequencing was performed with samples from 108 leprosy patients and 113 controls subjects, as well as immunophenotyping of CD(4)(+), CD(8)(+) and CD(69)(+) T cells by flow cytometry. The data showed that there were no significant differences between patients and control subjects, as well as according classification of Ridley-Jopling. However, the A/A genotype was significantly increased in paucibacillary patients (p=0.028) and the microsatellite encoding 16 CA repeats were significantly associated with paucibacillary compared to multibacillary patients (p=0.019). Individuals homozygous for the +874 A allele, the mean level of CD(4)(+) and CD(69)(+) T cells was higher. Our data suggest that polymorphisms present in the first intron of IFN-γ are not associated with susceptibility to leprosy, nevertheless, the +874 polymorphism and the CA repeats number encoded in IFN-γ gene may be related to a higher cellular immune response in patients and are consistently more frequently detected in PB patients.

A functional single-nucleotide polymorphism in the promoter of the gene encoding interleukin 6 is associated with susceptibility to tuberculosis

BACKGROUND

Genetic variation influences susceptibility or resistance to tuberculosis. Interleukin 6 (IL-6) contributes to protection against tuberculosis in mice. However, its role in regulating susceptibility or resistance to tuberculosis in humans is unclear.

METHODS

Genotyping of polymorphisms in IL-6 and IL-6R (CD126) genes was performed in 2 independent cohorts, an experimental population (495 cases and 358 controls) and a validation population (1383 cases and 1149 controls). The associations of the variants with tuberculosis were tested using 2 case-control association studies. In addition, the regulatory effects of single-nucleotide polymorphism rs1800796 (-572C > G) on IL-6 production in plasma and CD14(+) monocyte cultures stimulated with a Mycobacterium tuberculosis (M. tuberculosis) product were assessed.

RESULTS

The rs1800796 polymorphism is associated with increased resistance to tuberculosis (odds ratio [OR], 0.771; 95% confidential interval, .684-.870). The rs1800796GG genotype is strongly associated with reduced risk to tuberculosis (OR, 0.621; 95% CI, .460-.838). Interestingly, CD14(+) monocytes isolated from individuals with rs1800796GG genotype produced significantly less IL-6 in response to M. tuberculosis 19-kDa lipoprotein than those with CC or CG genotype.

CONCLUSIONS

We identified a genetic polymorphism in the IL-6 promoter that regulates cytokine production and host resistance to pulmonary tuberculosis in Chinese populations.

Differential combination of cytokine and interferon- γ +874 T/A polymorphisms determines disease severity in pulmonary tuberculosis

BACKGROUND

Mycobacterium tuberculosis infects nearly 1/3 of the world population and this reservoir forms the largest pool from which new cases arise. Among the cytokines, IFN-γ is a key determinant in protection against tuberculosis. Single nucleotide polymorphisms (SNPs) in IFN-γ gene (+874 T/A) which determine TT high ((hi)), AA low ((lo)) and TA intermediate ((int)) responder phenotypes have shown variable associations with tuberculosis disease outcome in different ethnic populations. The objective of the current study was to analyze IFN-γ gene combinations with other IFN-γ regulating cytokine genes (IL-10, TNF -α, IL-6) to see the effect of gene- combinations on disease severity outcome in pulmonary tuberculosis.

METHODS AND FINDINGS

Study groups comprised of pulmonary TB patients stratified according to lung tissue involvement into mild (Pmd = 74) or advance (Pad = 23) lung disease and compared with healthy controls (TBNA = 166). Genotype analysis was carried out using amplification refractory mutation system-PCR (ARMS-PCR). IFN-γ gene (+874 T/A) functional SNP combinations in TNFα (-308 G/A), IL-10 (-1082 A/G) and IL-6 (-174 G/C) were analyzed. Single gene analysis (Pearson χ²) showed a dominant association of IFN-γ TT (hi) genotype (p = 0.001) and T allele (p = 0.001) with mild disease. IFN-γ(lo) -IL-10(lo) genotype combination was associated with advanced disease (p = 0.002). IFN-γ(hi) -IL-6(hi) combination was associated with mild disease (p = 0.0005) while IFN-γ(lo) -IL-6(int) was associated with protection against both forms of pulmonary disease (p = 0.002).

CONCLUSION

Our results show that a limited number of IFN-γ gene combinations with other cytokine functional SNPs determine the outcome of disease severity in tuberculosis.

Increased interleukin-10 and interferon-γ levels in Plasmodium vivax malaria suggest a reciprocal regulation which is not altered by IL-10 gene promoter polymorphism

Background

In human malaria, the naturally-acquired immune response can result in either the elimination of the parasite or a persistent response mediated by cytokines that leads to immunopathology. The cytokines are responsible for all the symptoms, pathological alterations and the outcome of the infection depends on the reciprocal regulation of the pro and anti-inflammatory cytokines. IL-10 and IFN-gamma are able to mediate this process and their production can be affected by single nucleotide polymorphisms (SNPs) on gene of these cytokines. In this study, the relationship between cytokine IL-10/IFN-gamma levels, parasitaemia, and their gene polymorphisms was examined and the participation of pro-inflammatory and regulatory balance during a natural immune response in Plasmodium vivax-infected individuals was observed.

Methods

The serum levels of the cytokines IL-4, IL-12, IFN-gamma and IL-10 from 132 patients were evaluated by indirect enzyme-linked immunosorbent assays (ELISA). The polymorphism at position +874 of the IFN-gamma gene was identified by allele-specific polymerase chain reaction (ASO-PCR) method, and the polymorphism at position -1082 of the IL-10 gene was analysed by PCR-RFLP (PCR-Restriction Fragment Length Polymorphism).

Results

The levels of a pro- (IFN-gamma) and an anti-inflammatory cytokine (IL-10) were significantly higher in P. vivax-infected individuals as compared to healthy controls. The IFN-gamma levels in primoinfected patients were significantly higher than in patients who had suffered only one and more than one previous episode. The mutant alleles of both IFN-gamma and IL-10 genes were more frequent than the wild allele. In the case of the IFNG+874 polymorphism (IFN-gamma) the frequencies of the mutant (A) and wild (T) alleles were 70.13% and 29.87%, respectively. Similar frequencies were recorded in IL-10-1082, with the mutant (A) allele returning a frequency of 70.78%, and the wild (G) allele a frequency of 29.22%. The frequencies of the alleles associated with reduced production of both IFN-gamma and IL-10 were high, but this effect was only observed in the production of IFN-gamma.

Conclusions

This study has shown evidence of reciprocal regulation of the levels of IL-10 and IFN-gamma cytokines in P. vivax malaria, which is not altered by the presence of polymorphism in the IL-10 gene.

The +874T/A polymorphism in the interferon-γ gene and tuberculosis risk: an update by meta-analysis

The +874T/A polymorphism in the interferon-γ (IFN-γ) gene has been extensively examined for association to tuberculosis (TB); however, results of different studies have been inconsistent. The aim of this study was to comprehensively analyze the genetic risk of the +874T/A polymorphism in IFN-γ gene for TB by meta-analysis. A total of 4553 cases and 4631 controls in 21 case-control studies were included in this meta-analysis. The results indicated that the variant T allele carriers had a 27% decreased risk of TB, when compared with the homozygote AA (odds ratio [OR] = 0.73, 95% confidence interval [CI] = 0.61-0.87 for TT + TA versus AA). In the subgroup analysis by ethnicity, significant decreased risks were associated with T allele carriers in Asians (OR= 0.71, 95% CI = 0.52-0.97, p = 0.03) but not in Caucasians (OR = 0.87, 95% CI = 0.65-1.17, p = 0.37). Our results suggest that the IFN-γ +874T/A polymorphism contributes to susceptibility to TB.