| Sepsis is one of common complications after severe trauma, burn, shock and major operation, being a leading death cause for critically ill patients. It has been demonstrated that the pro-inflammatory and anti-inflammatory mediators released in response to bacterial endotoxin stimulation play a central role in the pathogenesis of sepsis, and that there is a close relationship between gene polymorphisms and susceptibility to many inflammatory diseases. Therefore, emphasis on studies in association of gene polymorphism with sepsis might deepen the understanding of pathogenesis of sepsis at the level of genes, which will be of significance for uncovering of the molecular basis of its clinical phenotype diversities. Interleukin-1β(IL-1β) has been demonstrated to be one of the key inflammatory mediators participated in the pathogenesis of sepsis. It has reported that base mutations occurred at –511 and -31 loci in the promoter of IL-1β gene, which have shown to be responsible for susceptibility to many kinds of infectious disease. Up to date, there are still little reports about the gene polymorphisms of IL-1β gene among Chinese population. It is unknown whether there exist the same SNPs at –511 and -31 loci or other SNPs in the 5' region of IL-1β gene. Therefore, first, the SNPs in all of important regions of IL-1β gene were analyzed in Chinese population with sequencing method. Next, the allelic and genotypic frequencies of SNPs in the promoter of IL-1β gene in Chongqingnese were further surveyed. Third, the association of the SNPs in the promoter of IL-1β gene with IL-1βproduction was studied with whole blood leukocytes in response to lipopolysaccharide(LPS). Finally, the functional activity of the SNPs in the promoter of IL-1β gene was further investigated through point mutation and gene transfection. The main results and conclusions were summarized as follows: 1. Direct sequencing of all important regions of IL-1β gene in 27 samples from 10 representative nationalities of Mongolian, Tibetan, Uygur, Dai, Bulang, Miao, Zhuang, Yi, Chaoxuan and Han in China revealed base mutations at 6 positions of IL-1β gene, which were located in the 5'flanking and intronic regions, respectively. –1470 G→C transversion in This work was supported by the Major State Basic Research Development Program of China (No.G1999054203)the 5'flanking region may be only occurred among Chinese population. Bioinformatics analysis showed that all of the three SNPs in 5'flanking region were distributed in the promoter region and were responsible for binding of several important nuclear transcription factors. 2. The occurrence frequencies of the three SNPs in 5'flanking region were further conveyed in 259 healthy unrelated volunteers in Chongqing with restriction fragment length polymorphism (RFLP) method. The results further demonstrated that –1470, -511 and –31 were SNP loci with high frequencies, being 43.60%, 50.78% and 47.01% respectively. Linkage disequilibrium (LD) analysis showed that the three loci were in strong linkage disequilibrium. People with simultaneous base variation at all three loci accounted for 32%. The most common SNP genotype was G/C-T/C-C/T (accounting for 29.4%). People with simultaneous base variation at two loci occupied 39%. The most common SNP genotype consisted of –511C and –31T alleles. 3. The relationship of –1470, -511 and –31 SNPs with IL-1βproduction was determined with human whole blood leukocytes in response to LPS stimulation. The results indicated that the base transversion at –511 or –31 locus could enhance LPS-induced IL-1βproduction by whole blood leukocytes, while base variant at –1470 locus inhibited IL-1βproduction. It was recognized for the first time that base mutation at both –511 and –31 had synergistic enhancement of IL-1 production, and base variant at –1470 could attenuate the enhancing effect of –511C and –31T on the IL-1β production. The stronger effects of base mutation at the three loci all occurred in genotype of homozygotes. 4. The functi...
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