Variants in toll-like receptor 9 gene influence susceptibility to tuberculosis in a Mexican population

Background: The control of Mycobacterium tuberculosis (Mtb) infection begins with the recognition of mycobacterial structural components by toll like receptors (TLRs) and other pattern recognition receptors. Our objective was to determine the influence of TLRs polymorphisms in the susceptibility to develop tuberculosis (TB) in Amerindian individuals from a rural area of Oaxaca, Mexico with high TB incidence. Methods: We carried out a case–control association community based study, genotyping 12 polymorphisms of TLR2, TLR4, TLR6 and TLR9 genes in 90 patients with confirmed pulmonary TB and 90 unrelated exposed but asymptomatic household contacts. Results: We found a significant increase in the frequency of the allele A of the TLR9 gene polymorphism rs352139 (A>G) in the group of TB patients (g.f. = 0.522) when compared with controls (g.f. = 0.383), (Pcorr = 0.01, OR = 1.75). Under the recessive model (A/G + A/A vs G/G) this polymorphism was also significantly associated with TB (Pcorr = 0.01, OR= 2.37). The association of the SNP rs352139 was statistically significant after adjustment by age, gender and comorbidities by regression logistic analysis (Dominant model: p value = 0.016, OR = 2.31; Additive model: p value = 0.023, OR = 1.68). The haplotype GAA of TLR9 SNPs was also associated with TB susceptibility (Pcorr = 0.02). Differences in the genotype or allele frequencies of TLR2, TLR4 and TLR6 polymorphisms between TB patients and healthy contacts were not detected. Conclusions: Our study suggests that the allele A of the intronic polymorphism rs352139 on TLR9 gene might contribute to the risk of developing TB in Mexican Amerindians

Risk factors for idiopathic pulmonary fibrosis in a Mexican population. A case-control study

SummaryThe etiology of idiopathic pulmonary fibrosis (IPF) remains poorly understood, but some studies have suggested that cigarette smoking or other occupational or environmental exposures, diabetes mellitus, or gastroesophageal reflux may play a role. In this study we evaluated the clinical records of a group of 97 consecutive patients with IPF, and 560 patients suffering 5 different respiratory disorders that were examined as controls: asthma (n=111), chronic obstructive pulmonary disease (n=132), squamous cell lung carcinoma (n=118), lung adenocarcinoma (n=101) and patients with otorhinolaryngology problems but without lung disease (n=98). In bivariate analyses male sex, diabetes mellitus and being former cigarette smoker were associated with IPF. After adjusting by these variables, multivariate analysis revealed that type 2 diabetes mellitus [11.3% in IPF patients vs 2.9% in controls, OR=4.3 (95% CI: 1.9–9.8), p<0.0001] was an independent risk factor associated to IPF. Our results provide additional evidence of a putative relationship between DM2 and idiopathic pulmonary fibrosis. Experimental research is necessary for thorough assessment of the pathogenic mechanisms involved in this association