Frequencies of genetic polymorphisms of TLR4 and CD14 and of HLA-DQ genotypes in children with celiac disease, type 1 diabetes mellitus, or both.

OBJECTIVES: Besides the central role of the adaptive immune system, a disturbance of innate immunity is also involved in the pathogenesis of celiac disease (CD). Inasmuch as CD and type 1 diabetes mellitus (T1DM) frequently coexist because of a common genetic predisposition, our aim was to study the frequency of CD14 C-260T and TLR4 A+896G single nucleotide polymorphisms (SNPs) and the distribution of HLA-DQ genotypes in children affected by CD, T1DM, or both. PATIENTS AND METHODS: TLR4 and CD14 SNPs were tested by polymerase chain reaction, followed by restriction fragment length polymorphism analysis in 80 children with T1DM, 100 children with CD, and 47 children with both CD and T1DM. Determination of HLA-DQ alleles was done by sequence-specific polymerase chain reaction. Frequencies were compared with those of healthy control children. RESULTS: The prevalence of the homozygous CD14 C-260TT genotype was significantly (P = 0.0081) lower in children with T1DM but not in those with CD and T1DM, compared with control children. No difference was found in the genotype and allele frequencies of TLR4 between the studied groups. In patients with T1DM, the frequency of the homozygous HLA-DQ8 genotype was significantly higher than in CD, whereas the frequency of homozygous or heterozygous HLA-DQ2 genotypes did not differ from that in control children. In patients with CD, both homozygous and heterozygous HLA-DQ2 genotypes were significantly more frequent than in the control and T1DM groups, and no elevation in the frequency of the HLA-DQ8 genotypes was observed. In patients with T1DM and those with CD and T1DM, the occurrence of HLA-DQ2/8 heterozygosity was significantly higher than in children with CD only and in control children. CONCLUSIONS: Our results suggest that in patients with T1DM, the CD14 C-260TT homozygous genotype increases the risk for the development of CD. The distribution of HLA-DQ genotype is different in children with CD and T1DM than in children with CD or T1DM only. Determination of the HLA-DQ genotype in children with T1DM may help in estimating the risk for the development of CD.

Increased expression of Toll-like receptor (TLR) 2 and TLR4 in the colonic mucosa of children with inflammatory bowel disease.

Inflammatory bowel disease (IBD) may result from exaggerated stimulation of the mucosal immune system by luminal bacterial flora. Bacterial products are recognized by pattern recognition receptors such as Toll-like receptors (TLRs), which are key regulators of the innate immune system. Therefore, the expression of TLR2, TLR3 and TLR4 in colonic biopsy samples taken from children with active IBD were studied and compared to controls. Colonic biopsy samples were collected from macroscopically inflamed and non-inflamed regions of the mucosa of 12 children with freshly diagnosed IBD (fdIBD) and 23 children with relapsed IBD (rIBD). Specimens were also obtained from eight controls. TLR2, TLR3 and TLR4 mRNA expression and protein levels were determined by real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blot. We found higher TLR2 and TLR4 mRNA and protein levels in the inflamed colonic mucosa of children with fdIBD and rIBD compared to controls. In the non-inflamed colonic mucosa of children with fdIBD and rIBD, TLR2 and TLR4 mRNA and protein levels were similar to controls. TLR2 and TLR4 mRNA and protein levels also did not differ between children with fdIBD or rIBD in either inflamed or non-inflamed colonic mucosa. TLR3 mRNA expression and protein levels were similar in all groups studied. Our results of increased levels of TLR2 and TLR4 in the inflamed colonic mucosa of children with IBD confirm the hypothesis that innate immunity has an important role in the pathogenesis of this disease.

Twelve year observation of primary and secondary antibiotic-resistant Helicobacter pylori strains in children.

BACKGROUND: The effectiveness of Helicobacter pylori eradication regimens is influenced by antibiotic susceptibility of infecting strains. Data concerning antibiotic resistance in children are limited. We report the evolution of primary and secondary resistance in a series of Belgian children during the last 12 years. PATIENTS AND METHODS: From 1989 through 2000, H. pylori gastritis was diagnosed in 569 children, and antibiotic susceptibility tests were performed in 555. Eradication, using different schemes, failed in 128 of 457 treated children. After eradication failure antibiotic susceptibility determination was performed in 87 of 128. Comparison of antibiotic susceptibility of strains isolated from the gastric body and from the antrum was performed in 238 samples. RESULTS: Resistance to amoxicillin was not observed. The rate of primary resistance to nitroimidazole derivatives was 18.0% (101 of 555) and remained constant throughout this period, whereas primary resistance to macrolides increased from an average of 6.0% (range, 0 to 10%) before 1995 to 16.6% (range, 10 to 25%, P < 0.001) thereafter. Antibiotic consumption in Belgium, especially macrolides, did not show important fluctuations during the study period. Secondary resistance developed in 39 of 87 patients (46%). Strains isolated from different gastric locations show identical susceptibility testing in all but 5 of 238. CONCLUSIONS: Resistance of H. pylori to macrolides increased in our pediatric population which did not appear to correlate with macrolides prescription habits in our country. After eradication failure acquired secondary resistance was observed in one-half of the patients.