The Relationship Between Gene Polymorphism Of TLR4 And Gram-negative Bacteria Infection In Neonates

Objective The single nucleotide polymorphism (SNP) of TLR4 in neonate of Chinese Han nationality were screened to have a further study on the relationshiop between SNP and G- bacteria infection.Methods 0.3 ml peripheral blood sample was collected from each selected case. A series of experiments were done in sequence with the samples, DNA extraction, Polymerase Chain Reaction (PCR) and sequencing to detect SNP; the continuous variables of the two groups were examined by analysis of variance, meanwhile, the counting data were analysed by chi-square test.Results 465 neonates of Han nationality born in Shanghai were detected, and the classifications are as follows,205 premature cases(133 cases with the gestational age(GA) of 26～32 weeks,172 cases with the GA of 33～36 weeks) and 160 term cases; 186 cases of infectious group with G- bacteria,279 cases of noninfectious group; 68 cases with very low birth weight (VLBW),274 cases with low birth weight(LBW),96 small for gestational age infants.1. It is common to find the SNPs of TLR4 in the Han nationality, such as T-1418C, A-1837G, G-1892A, T-2242C, A-2381G, A-2415G, concentrating on the promoter other than the coding region(CDS) which are common in the genotype of European and American.2.465 cases were all detected the six SNP sites as mentioned, and the 345 cases had one or more sites of the six sites (SNP group),120 cases have none (non-SNP group).①The relationship between SNP and G- bacteria infection:Among the premature cases, the rate of G- bacteria infection is 41.8%(94/225) in SNP group, and the rate of non-SNP group is 25%(20/80), there is significant difference between them.(P=0.008, OR=2.153). But there is no significant difference between SNP group and non-SNP group among the term cases; Among LBW cases, the rate of G- bacteria infection is 45.8%(93/203) in SNP group, while the rate of non-SNP group is 23.9% (17/71), there is significant difference between them(P=0.001, OR=2.686). But there is no significant difference between SNP group and non-SNP group among the term cases and the cases with BW>2500g. Among 465 cases of different gestational age, as for the SNA site A-2381G, the rate of G-bacteria infection is 33.7%(56/166) in the group with genotype of A/A, but the rate is 43.4%(130/299) in the non-A/A group. There is significant difference between them (P=0.040, OR=0.662); In terms of different gestational age, among the cases with GA<33w,the infection rate is 41.3% (19/46) in the group with the genotype of A/A, but the rate is 59.8%(52/87) in the non-A/A group. There is significant difference between them (P=0.042). GA:In the cases of GA(33～36w),the infection rate is 15.6%(10/64) in the group with the genotype of A/A, but the rate is 30.6%(33/108) in the non-A/A group, there is significant difference between them (P=0.029).In this study, there was no relationship between the SNP site on the promoter and the G- bacteria infection in term cases.In terms of different birth weight(BW), among the cases with BW<1500g, as for the SNP site of T-1418C,the infection rate is 61%(25/41) in the group with the genotype of T/T, but the rate is 85.2%(23/27) in the non-T/T group. There is significant difference between them (P=0.032, OR=0.272); As for the SNP site of A-1837G,the infection rate is 100%(10/10) in the group with the genotype of G/G, but the rate is 65.5%(38/58) in the non-G/G group. There is significant difference between them (P=0.027, OR=1.526). As for the SNP site of A-2415G, the infection rate is 100% (12/12) in the group with the genotype of G/G, but the rate is 64.2%(36/56) in the non-G/G group. There is significant difference between them (P=0.014, OR=1.556).BW:Among the cases with BW(1500-2500g), As for the SNP site ofA-1837G, the infection rate is 18.8%(13/69) in the group with the genotype of A/A, but the rate is 35.8%(49/137) in the non-A/A group. There is significant difference between them (P=0.012, OR=0.417).As for the SNP site of T-2242C, the infection rate is 20.5%(15/73) in the group with the genotype of T/T, but the rate is 35.3% (47/133) in the non-T/T group. There is significant difference between them (P=0.027, OR=0.473).As for the SNP site of A-2381G, the infection rate is 18.4% (14/76) in the group with the genotype of A/A, but the rate is 36.9%(48/130) in the non- A/A group. There is significant difference between them(P=0.005, OR=0.386). As for the SNP site of A-2415G, the infection rate is 20.3%(15/74) in the group with the genotype of A/A, but the rate is 35.6%(47/132) in the non-A/A group. There is significant difference between them (P=0.021, OR=0.460); But according to the result, no relationship has been found between the SNP site on the promoter of gene TLR4 and the G- bacteria infection in cases with BW>2500g.②The relationship between SNP and premature:The common six SNP sites on the promoter had no statistically significant differences(P>0.1) with premature.③The relationship between SNP and birth weight:As for the SNP site of T-2242C, in the cases with C/C genotype, the rate of very low birth weight (VLBW) is 18.8% (15/80),the rate of low birth weight(LBW) is 73.8%(59/80) while the other genotype,the rate of VLBW is 13.8%(53/385), the rate of LBW is 55.8% (215/385), R×C chart chi-square test shows P=0.012, the birth weight of C/C genotype is 2170.3±722.2g and the birth weight of non-C/C genotype is 2402.7±822.6g;There is significant difference between them (P=0.019)④The relationship between SNP and intrauterine growth retardation(IUGR):In 465 cases of different gestational ages, there is no significant difference between the six SNP sites and incidence of the SGA. In terms of different gestational ages, the result shows that there is no significant difference between the incidence of SGA and the common SNP sites on the promoter of gene TLR4 in the premature infants; In the term cases,the SGA incidence rate is 50%(5/10) in the cases with homozygote C/C on the SNP site T-1418C,the SGA incidence rate is 27.1%(16/59) in the cases with heterozygote T/C, and 15.8%(13/82) in the cases with homozygote T/T, there is significant difference among the three groups (P=0.028). The genotype C/C is a vital factor of SGA incidence, OR=3.862,and the genotype T/T is an antagonistic factor of SGA,OR=0.431; The SGA incidence rate is 15.9%(14/88) in the cases with G/G genotype on the SNP site G-1892A,the SGA incidence rate is 31.7%(20/63) in the cases with non-G/G,there is significant difference between them(P=0.022).The genotype of G/G plays a role as an antagonistic factor for SGA incidence,OR=0.407.In the term cases, as for the SNP site T-1418C,the birth weight is 2994.09±653.945g in the cases with homozygote C/C,3165.54±455.111g in the cases with heterozygote T/C, and 3251.73±557.371g in the cases with homozygote T/T, there is significant difference among the three groups; As for the SNP site G-1892A,the birth weight is 2838.0±546.0g in the cases with homozygote A/A, 3201.2±529.1g in the cases with heterozygote G/A, and 3276.2±552.2g in the cases with homozygote G/G, there is significant difference among the three groups(P=0.024).Conclusions The gene polymorphism of TLR4 has racial diversity.The common SNP sites concentrate on the promoter of TLR4 but rarely exist on the coding region in neonates of Han nationality; The six common SNP sites on the promoter may have relationship with G- bacteria infection,low birth weight and IUGR.