A case-control study of innate immunity pathway gene polymorphisms in Puerto Ricans reveals association of toll-like receptor 2 +596 variant with asthma

PM2.5 Extracts Induce INFγ-Independent Activation of CIITA, MHCII, and Increases Inflammation in Human Bronchial Epithelium

The capacity of particulate matter (PM) to enhance and stimulate the expression of pro-inflammatory mediators has been previously demonstrated in non-antigen-presenting cells (human bronchial epithelia). Nonetheless, many proposed mechanisms for this are extrapolated from known canonical molecular pathways. This work evaluates a possible mechanism for inflammatory exacerbation after exposure to PM2.5 (from Puerto Rico) and CuSO4, using human bronchial epithelial cells (BEAS-2B) as a model. The induction of CIITA, MHCII genes, and various pro-inflammatory mediators was investigated. Among these, the phosphorylation of STAT1 Y701 was significantly induced after 4 h of PM2.5 exposure, concurrent with a slight increase in CIITA and HLA-DRα mRNA levels. INFγ mRNA levels remained low amidst exposure time, while IL-6 levels significantly increased at earlier times. IL-8 remained low, as expected from attenuation by IL-6 in the known INFγ-independent inflammation pathway. The effects of CuSO4 showed an increase in HLA-DRα expression after 8 h, an increase in STAT1 at 1 h, and RF1 at 8 h We hypothesize and show evidence that an inflammatory response due to PM2.5 extract exposure in human bronchial epithelia can be induced early via an alternate non-canonical pathway in the absence of INFγ.

TLR Signaling Pathway Gene Polymorphisms, Gene-Gene and Gene-Environment Interactions in Allergic Rhinitis

Background

Allergic rhinitis (AR) is a nasal inflammatory disease resulting from a complex interplay between genetic and environmental factors. The association between Toll-like receptor (TLR) signaling pathway and environmental factors in AR pathogenesis remains to be explored. This study aims to assess the genetic association of AR with single nucleotide polymorphisms (SNPs) in TLR signaling pathway, and investigate the roles of gene–gene and gene–environment interactions in AR.

Methods

A total of 452 AR patients and 495 healthy controls from eastern China were enrolled in this hospital-based case–control study. We evaluated putatively functional genetic polymorphisms in TLR2, TLR4 and CD14 genes for their association with susceptibility to AR and related clinical phenotypes. Interactions between environmental factors (such as traffic pollution, residence, pet keeping) and polymorphisms with AR were examined using logistic regression. Models were stratified by genotype and interaction terms, and tested for the significance of gene–gene and gene–environment interactions.

Results

In the single-locus analysis, two SNPs in CD14, rs2563298 (A/C) and rs2569191 (C/T) were associated with a significantly decreased risk of AR. Compared with the GG genotype, the GT and GT/TT genotypes of TLR2 rs7656411 (G/T) were associated with a significantly increased risk of AR. Gene–gene interactions (eg, TLR2 rs7656411, TLR4 rs1927914, and CD14 rs2563298) was associated with AR. Gene–environment interactions (eg, TLR4 or CD14 polymorphisms and certain environmental exposures) were found in AR cases, but they were not significant after Bonferroni correction.

Conclusion

The genetic polymorphisms of TLR2 and CD14 and gene–gene interactions in TLR signaling pathway were associated with susceptibility to AR in this Han Chinese population. However, the present results were limited to support the association between gene–environment interactions and AR.

Association of polymorphisms in TLR2 and TLR4 with asthma risk: An update meta-analysis

BACKGROUND

Several epidemiological studies have focused on the association between polymorphisms in toll-like receptors (TLRs) and asthma. However, the results remained inconclusive.

METHODS

We systematically reviewed the database of PubMed, EMBASE, Web of Science, CNKI, and Google scholar for all related articles on TLR polymorphisms and asthma. We used the software STATA 12.0 to conduct the meta-analysis. The heterogeneity and publication bias were examined, respectively.

RESULTS

Eighteen studies consisting of 3538 asthma cases and 4090 controls were selected into the meta-analysis. The pooled odds ratios (ORs) show that rs3804099 was associated with asthma in dominant model (OR = 1.51, 95% CI = 1.17-1.96, P = .002), and rs4986791 was associated with asthma in additive model (OR = 0.81, 95% CI = 0.64-1.02, P = .07) and dominant model (OR = 0.76, 95% CI = 0.60-0.97, P = .025).

CONCLUSION

The combined results show that rs3804099 in TLR2 and rs4986791 in TLR4 were significantly associated with asthma risk. Polymorphisms in TLRs play important roles in asthma.

Association of single-nucleotide polymorphisms in toll-like receptor 2 gene with asthma susceptibility: A meta-analysis

BACKGROUND

An increasing number of studies have been carried out on the relationship between polymorphisms in toll-like receptor 2 (TLR2) gene and asthma risk. However, the results were controversial. With the purpose of yielding a more reliable estimation of the association, we conducted the present meta-analysis.

METHODS

Multiple electronic databases up to August 22, 2016 were searched for literature retrieval. The association between the asthma susceptibility and the rs5743708 polymorphism, rs3804099 polymorphism, rs3804100 polymorphism, and rs4696480 polymorphism in TLR2 gene was appraised. The odds ratios (ORs) with 95% confidence intervals (CIs) under different genetic models were calculated.

RESULTS

A total of 13 studies were eligible in our meta-analysis according to the predefined inclusion and exclusion criteria. There was no significant association between asthma risk and rs5743708, rs3804099, and rs3804100 polymorphisms in TLR2 gene under any genetic model. With respect to the TLR2 rs4696480 polymorphism, significant association was detected between asthma susceptibility and TLR2 rs4696480 polymorphism under dominant model (OR = 2.455, 95% CI = 1.235-4.88, P = .01) and codominant 3 model (OR = 2.776, 95% CI = 1.199-6.427,  = 0.017).

CONCLUSIONS

Our meta-analysis reveals that the TLR2 rs4696480 polymorphism is significantly associated with asthma susceptibility, and the TLR2 rs4696480 polymorphism is a risk factor for asthma.

Regulation of airway inflammation and remodeling in asthmatic mice by TLR3/TRIF signal pathway

This paper aims to investigate the effect of Toll-like receptors 3 (TLR3)/TIR-domain-containing adapter-inducing interferon-β (TRIF) signal pathway on the airway inflammation and remodeling in asthmatic mice. C57BL/6 and TLR3^-/- mice were randomly divided into three groups (10 mice per group), including Control group (mice inhaled phosphate buffer saline (PBS)), Asthma group (mice inhaled ovalbumin (OVA)) and polyriboinosinic-ribocytidylic acid (poly (I: C)) group (asthmatic mice were injected intraperitoneally with TLR3 agonist poly (I: C)). Hematoxylin-eosin (HE) staining, Wright-Giemsa staining, Enzyme-linked immunosorbent assay (ELISA), Immunohistochemistry, Hydroxyproline assay, quantitative real time polymerase chain reaction (qRT-PCR) and Western blot were used to assess for the indices of airway inflammation and remodeling. In terms of WT mice, all asthma groups with or without the addition of poly (I: C) showed exaggerated inflammation and remodeling in the airways as compared to Control group, which were more seriously in poly (I: C) group than Asthma group. Furthermore, we observed the significant inhibition of airway inflammation and remodeling in the TLR3^-/- mice in both Asthma no matter with or without addition of poly (I: C) than the WT mice. TLR3 knockout could obviously relieve the airway inflammation and remodeling in asthma through inhibiting TLR3/TRIF signaling pathway.