The GRA15 protein from Toxoplasma gondii enhances host defense responses by activating the interferon stimulator STING.

Toxoplasma gondii is an important neurotropic pathogen that establishes latent infections in humans that can cause toxoplasmosis in immunocompromised individuals. It replicates inside host cells and has developed several strategies to manipulate host immune responses. However, the cytoplasmic pathogen-sensing pathway that detects T. gondii is not well-characterized. Here, we found that cyclic GMP-AMP synthase (cGAS), a sensor of foreign dsDNA, is required for activation of anti-T. gondii immune signaling in a mouse model. We also found that mice deficient in STING (Stinggt/gt mice) are much more susceptible to T. gondii infection than WT mice. Of note, the induction of inflammatory cytokines, type I IFNs, and interferon-stimulated genes in the spleen from Stinggt/gt mice was significantly impaired. Stinggt/gt mice exhibited more severe symptoms than cGAS-deficient mice after T. gondii infection. Interestingly, we found that the dense granule protein GRA15 from T. gondii is secreted into the host cell cytoplasm and then localizes to the endoplasmic reticulum, mediated by the second transmembrane motif in GRA15, which is essential for activating STING and innate immune responses. Mechanistically, GRA15 promoted STING polyubiquitination at Lys-337 and STING oligomerization in a TRAF protein-dependent manner. Accordingly, GRA15-deficient T. gondii failed to elicit robust innate immune responses compared with WT T. gondii. Consequently, GRA15-/-T. gondii was more virulent and caused higher mortality of WT mice but not Stinggt/gt mice upon infection. Together, T. gondii infection triggers cGAS/STING signaling, which is enhanced by GRA15 in a STING- and TRAF-dependent manner.

Interaction Between Susceptibility Loci in MAVS and TRAF3 Genes, and High-risk HPV Infection on the Risk of Cervical Precancerous Lesions in Chinese Population.

Persistent high-risk HPV infection is considered as a major cause of cervical cancer. Nevertheless, only some infected individuals actually develop cervical cancer. The RIG-I pathway in innate immunity plays an important role in antivirus response. Here, we hypothesized that altered function of mitochondrial antiviral signaling protein (MAVS) and mitochondrial TNF receptor-associated factor 3(TRAF3), key molecules downstream of the viral sensors RIG-I, may impair their ability of clearing HPV and thereby influence the risk for cervical precancerous lesions. To investigate the effects of MAVS and TRAF3 polymorphisms on susceptibility to cervical precancerous lesions, 8 SNPs were analyzed in 164 cervical precancerous lesion cases and 428 controls. Gene-environment interactions were also calculated. We found that CA genotype of rs6052130 in MAVS gene were at 1.48 times higher risk of developing cervical precancerous lesion than individuals with CC genotype (CA vs. CC: ORadjusted = 1.48, 95% CI, 1.02-2.16). In addition, a significant synergetic interaction between high-risk HPV infection and rs6052130 was found on an additive scale. A significantly decreased risk of cervical precancerous lesions for the TC genotype of rs12435483 in the TRAF3 gene (ORadjusted = 0.67, 95% CI, 0.45-0.98) was also found. Moreover, MDR analysis identified a significant three-locus interaction model, involving high-risk HPV infection, TRAF3 rs12435483 and number of full-term pregnancies. Our results indicate that the MAVS rs6052130 and TRAF3 rs12435483 confer genetic susceptibility to cervical precancerous lesions. Moreover, MAVS rs6052130-mutant individuals have an increased vulnerability to high-risk HPV-induced cervical precancerous lesions.

Interactions between polymorphisms in the 3'untranslated region of the cyclin dependent kinase 6 gene and the human papillomavirus infection, and risk of cervical precancerous lesions.

The human papillomavirus (HPV) infection is essential for the development of cervical cancer and its precursor lesions. However, only certain persistently infected individuals develop cervical cancer. Cyclin-dependent kinase 6 (CDK6) is a critical regulatory cancer-associated gene in the cell cycle and in tumorigenesis. Single nucleotide polymorphisms (SNPs) in microRNA sites in the 3'-untranslated region (UTR) of target genes may result in target gene expression level changes and susceptibility to diseases, including cancer. Therefore, the aim of the present study was to determine whether SNPs in the 3'UTR of the CDK6 gene may affect susceptibility to cervical precancerous lesions in a Chinese population. Five polymorphisms in the 3'UTR of the CDK6 gene were evaluated in 164 cervical precancerous lesion cases and 296 control subjects. Differences in environmental factors between cases and controls were evaluated using the χ2 test or unpaired t-test. Logistic regression was used to examine the association between the five polymorphisms and cervical precancerous lesions. The model-free multifactor dimensionality reduction (MDR) method was performed to evaluate the interaction effect of environment variables and gene polymorphisms. Interactions on the additive scale are calculated by using the relative excess risk due to interaction (RERI). After controlling for potential confounders, a significantly decreased risk of cervical precancerous lesions for the GA genotype, rs8179, and the AT genotype, rs42033 [GA vs. GA: odds ratio (OR)adjusted=0.17, 95% confidence interval (CI), 0.05-0.57; AT vs. AA: ORadjusted=0.18, 95% CI, 0.05-0.59, respectively] was identified. Furthermore, following MDR analysis, a significant three-locus interaction model was identified, which involved the HPV infection, the number of pregnancies and rs8179. Additionally, a significant antagonistic interaction between the HPV infection and rs8179 was identified on an additive scale. Haplotype AGTA was associated with a decreased risk of developing cervical precancerous lesions (ORadjusted=0.21; 95% CI, 0.06-0.75). Thus, the present results indicated that the rs8179 and rs42033 polymorphisms confer genetic susceptibility to cervical precancerous lesions. Furthermore, the interaction between the rs8179 polymorphism in CDK6 and the HPV infection and haplotype AGTA may be associated with cervical precancerous lesions.

The effects of TLR3, TRIF and TRAF3 SNPs and interactions with environmental factors on type 2 diabetes mellitus and vascular complications in a Han Chinese population.

Toll-like receptor 3 (TLR3) is involved in type I interferon-ß (IFN-ß) via TIR-domain-containing adapter-inducing interferon-ß (TRIF) and Tumor necrosis factor receptor-associated factor 3 (TRAF3), culminating in inflammation and immunity reactions. TLR3 is implicated in insulin resistance and type 2 diabetes mellitus (T2DM). Eight SNPs of these genes were detected in 552 T2DM patients and 552 matched healthy control subjects. Gene-gene and gene-environment interactions and haplotype associations were also evaluated. We identified a 21% increased risk of T2DM for the T allele of rs12435483 in the TRAF3 gene (OR: 1.21; 95% CI: 1.01-1.44; P=0.036). The GA genotype and GA+AA genotype of TRAF3 rs12147254 were found to increase the risk of coronary heart disease (CHD) among T2DM patients (GA vs. GG: OR=4.17, 95% CI: 1.04-16.79, P=0.045; GA+AA vs. GG: OR=3.97, 95% CI: 1.02-15.48, P=0.047). However, the GACGAC haplotype in TRAF3 had a protective effect on T2DM micro-macrovascular complications (OR=0.33, 95% CI: 0.13-0.85, P=0.017). Two-factor (TRAF3 rs12435483 and LDL) and three-factor (TRAF3 rs12435483, BMI and HDL) interactions of the risk of T2DM were identified. In conclusion, the genetic variants in the TLR3-TRIF-TRAF3-INF-ß signaling pathway and interactions with some particular environmental factors (LDL, BMI and HDL) may contribute to susceptibility to T2DM and vascular complications in the Han Chinese population.

Association of LPP and TAGAP Polymorphisms with Celiac Disease Risk: A Meta-Analysis.

Background: Lipoma preferred partner (LPP) and T-cell activation Rho GTPase activating protein (TAGAP) polymorphisms might influence the susceptibility to celiac disease. Therefore, we performed a meta-analysis by identifying relevant studies to estimate the risks of these polymorphisms on celiac disease. Methods: The PubMed, Web of Science and Embase databases were searched (up to October 2016) for LPP rs1464510 and TAGAP rs1738074 polymorphisms. Results: This meta-analysis included the same 7 studies for LPP rs1464510 and TAGAP rs1738074. The minor risk A allele at both rs1464510 and rs1738074 carried risks (odds ratios) of 1.26 (95% CI: 1.22-1.30) and 1.17 (95% CI: 1.14-1.21), respectively, which contributed to increased risks in all celiac disease patients by 10.72% and 6.59%, respectively. The estimated lambdas were 0.512 and 0.496, respectively, suggesting that a co-dominant model would be suitable for both gene effects. Conclusions: This meta-analysis provides robust estimates that polymorphisms in LPP and TAGAP genes are potential risk factors for celiac disease in European and American. Prospective studies and more genome-wide association studies (GWAS) are needed to confirm these findings, and some corresponding molecular biology experiments should be carried out to clarify the pathogenic mechanisms of celiac disease.

Interaction between susceptibility loci in cGAS-STING pathway, MHC gene and HPV infection on the risk of cervical precancerous lesions in Chinese population.

Human papillomavirus (HPV) infection is a definite risk factor for cervical cancer. Nevertheless, only some infected individuals actually develop cervical cancer. The cGAS-STING pathway in innate immunity plays an important role in protecting against HPV infection. Chen et al. described that the rs2516448 SNP in the MHC locus may affect susceptibility to cervical cancer, a finding that we attempted to replicate in a Chinese population. To investigate the effects of cGAS, STING and MHC polymorphisms on susceptibility to cervical precancerous lesions, 9 SNPs were analyzed in 164 cervical precancerous lesion cases and 428 controls. Gene-gene and gene-environment interactions were also evaluated. We found a significantly decreased risk of cervical precancerous lesions for the GG genotype of rs311678 in the cGAS gene (ORadjusted = 0.40, 95% CI: 0.16-0.98). Moreover, MDR analysis identified a significant three-locus interaction model, involving HPV infection, age at menarche and rs311678 in cGAS. Additionally, a significant antagonistic interaction between HPV infection and rs311678 was found on an additive scale. In conclusion, our results indicate that the rs311678 polymorphism in the cGAS gene confers genetic susceptibility to cervical precancerous lesions. Moreover, the three-way gene-environment interactions further demonstrate that the rs311678 polymorphism in cGAS can significantly decrease the risk of HPV infection and the elder at menarche.

A meta-analysis of interaction between Epstein-Barr virus and HLA-DRB1*1501 on risk of multiple sclerosis.

Infection with Epstein-Barr virus (EBV) and HLA-DRB1*1501-positivity is a risk factor for multiple sclerosis (MS), but whether an interaction between these two factors causes MS is unclear. We therefore conducted a meta-analysis on the effect of the interaction between HLA-DRB1*1501 and EBV infection on MS. Searches of PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), and the Wanfan databases through February 2015 yielded 5 studies that met the criteria for inclusion in the meta-analysis. EBV infection and HLA-DRB1*1501-positivity were dichotomized. The additive (S) and multiplicative interaction indexes (OR) between EBV infection and HLA-DRB1*1501 and their 95% confidence intervals (95%CI) were calculated for each study and then combined in a meta-analysis. EBV infection was significantly associated with MS (OR = 2.60; 95%CI, 1.48-4.59). HLA-DRB1*1501 was associated with a significantly increased risk of MS (OR, 3.06; 95%CI, 2.30-4.08). An interaction effect between EBV infection and HLA-DRB1*1501 on MS was observed on the additive scale (S, 1.43; 95%CI, 1.05-1.95, P = 0.023), but no interaction effect was observed on the multiplicative scale (OR, 0.86, 95%CI, 0.59-1.26). This meta-analysis provides strong evidence that EBV alone, HLA-DRB1*1501 alone or their interaction is associated with an elevated risks of MS.