Association of IFNG gene polymorphisms with pulmonary tuberculosis but not with spinal tuberculosis in a Chinese Han population

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.

Research progress on genetic control of host susceptibility to tuberculosis

The "Lübeck disaster", twins studies, adoptees studies, and other epidemiological observational studies have shown that host genetic factors play a significant role in determining the host susceptibility to Mycobacterium tuberculosis infection and pathogenesis of tuberculosis. From linkage analyses to genome-wide association studies, it has been discovered that human leucocyte antigen (HLA) genes as well as non-HLA genes (such as SLC11A1, VDR, ASAP1 as well as genes encoding cytokines and pattern recognition receptors) are associated with tuberculosis susceptibility. To provide ideas for subsequent studies about risk prediction of MTB infection and the diagnosis and treatment of tuberculosis, we review the research progress on tuberculosis susceptibility related genes in recent years, focusing on the correlation of HLA genes and non-HLA genes with the pathogenesis of tuberculosis. We also report the results of an enrichment analysis of the genes mentioned in the article. Most of these genes appear to be involved in the regulation of immune system and inflammation， and are also closely related to autoimmune diseases.

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.

Association between the mannose-binding lectin (MBL)-2 gene variants and serum MBL with pulmonary tuberculosis: An update meta-analysis and systematic review

In recent years, many studies have demonstrated that the MBL-2 gene polymorphisms may be associated with pulmonary tuberculosis (PTB) susceptibility. Moreover, some studies have shown that serum MBL levels were influenced by the MBL-2 gene polymorphisms and that it plays an important role in tuberculosis infection. However, the results of these studies were inconsistent and underpowered. The current meta-analysis and systematic review aimed to evaluate the association between the MBL-2 gene polymorphisms and serum MBL levels with PTB. Finally, 30 eligible articles were included in the study. The overall results indicated that the MBL-2 rs1800450 (54 A/B) and rs5030737 (52 A/D) polymorphisms were risk factors for PTB, but the MBL-2 rs1800451 (57 A/C) and rs7095891 (+4 P/Q) polymorphisms as protective factors against PTB. No associations were found in the other three polymorphisms (exon 1, rs7096206 (-221 X/Y), and rs11003125 (-550 H/L) of the MBL-2 gene. In addition, we could not detect any significant differences between haplotypes among PTB patients and healthy controls. More important, the meta-analysis results indicated that the serum MBL levels in patients with PTB were significantly lower than those in healthy controls (SMD = 0.43, 95% CI = 0.33-0.52). This study suggested that the MBL-2 gene polymorphisms may be involved in the pathogenesis of PTB, and serum MBL may be a biomarker for the diagnosis of PTB. More rigorous research is needed in the future to confirm these findings further.