ABSTRACT. Although the role of CD14 in mediating signals from Toll-like receptors to recognize Mycobacterium tuberculosis is known, how polymorphisms in this gene affect the susceptibility to develop tuberculosis are still not clear. We examined whether single nucleotide polymorphisms at positions -1145 and -159 in the promoter region of the CD14 gene are associated with tuberculosis in a Chinese Han population in a case-control study of 432 Chinese patients with tuberculosis and 404 ethnically matched healthy controls. Genotyping was performed to identify polymorphisms of the CD14 gene by PCR-DNA sequencing. Both the frequency of allele T in the C(-159)T polymorphism (odds ratio (OR) = 1.4; 95% confidence interval (95%CI) = 1.148-1.708) and allele G in the G(-1145)A polymorphism (OR = 1.512; 95%CI = 1.236-1.849) were significantly more frequent in cases than in controls. The frequencies of genotypes CC and CT in the C(-159)T polymorphism, as well as the frequencies of genotypes AA and AG, were lower in cases than in controls. Based on our results, we conclude that G(-1145)A and C(-159)T polymorphisms of CD14 are associated with decreased risk for the development of tuberculosis in the Chinese Han population.

ABSTRACT. Toll-interleukin 1 receptor (TIR) domain containing adaptor protein (TIRAP; also known as MAL) is an essential adaptor molecule in Toll-like receptor signaling, involved in activating the innate immune response during infection. Genetic variations in the TIRAP gene may influence human susceptibility to infectious disease. To date, in the Chinese population, a possible predisposition of TIRAP gene variants to tuberculosis has not been reported. We investigated whether TIRAP gene polymorphisms are associated with the development of tuberculosis in a Chinese population. We investigated all the single-nucleotide polymorphisms (SNPs) within the TIRAP exon 5 in a case-control study of 212 patients with tuberculosis and 215 controls in a Chinese population. Genotyping was performed to identify the polymorphisms of TIRAP gene by PCR-DNA sequencing method. Haplotypes for the TIRAP gene variants were constructed using Haplo- view version 4.2. Six polymorphisms of the SNPs listed in the National Center for Biotechnology Information database were detected in these Chinese tuberculosis patients. It was found that both the frequency of the 286A allele (odds ratio (OR) = 13.37; 95% confidence interval (CI) = 0.75-238.3; P < 0.01) and the frequency of 286AG genotype (OR = 13.57; 95%CI = 0.76-242.5; P < 0.01) were significantly higher in patients than in healthy controls. However, two other SNPs, C539T and C558T, reported to be associated with tuberculosis in other populations, were found not to be associated with tuberculosis in this Chinese population. We conclude that TIRAP G286A (D96N) polymorphism is associated with susceptibility to tuberculosis and may be a new risk factor for the development of tuberculosis in China.

DOI 10.4238/vol9-3gmr771 ABSTRACT. Myeloid differentiation-2 (MD-2) is an essential component of the CD14-TLR4/MD-2 receptor complex involved in microbial cell wall component recognition during infection. Genetic variations in the MD-2 gene may influence human susceptibility to infectious diseases. To date, a predisposition of MD-2 gene variants to contract tuberculosis has not been reported. We investigated whether MD-2 gene polymorphisms were associated with the development of tuberculosis in a Chinese population. The six common polymorphisms (rs11465996, rs1809442, rs1809441, rs1809440, rs16938754, and rs7842342) within the MD-2 gene promoter region were all detected in 259 patients with tuberculosis and 276 healthy control subjects by DNA sequencing. None of the allelic frequencies, haplotype patterns or genotype distributions of the assayed polymorphisms was found to be significantly different between patients and controls (P> 0.05). We conclude that these gene variants in the MD-2 gene promoter region are not associated with tuberculosis, and apparently do not play a role in susceptibility to tuberculosis in the Chinese population