SummaryInflammatory 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 noninflamed 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 noninflamed 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.

Innate immunity and urinary tract response play a central role in the development of urinary tract infection (UTI). Heat shock protein (HSP) 72 and Toll-like receptor (TLR) 4 are among the key elements of innate defence mechanisms. This study assesses the role of HSPA1B A(1267)G and TLR4 A(896)G polymorphisms using allele-specific polymerase chain reaction in 103 patients treated with recurrent UTI. Allelic prevalence was compared with reference values of 235 healthy controls. Clinical data were also statistically evaluated. TLR4 (896)AG genotype and TLR4 (896)G allele had also higher prevalence in UTI patients versus controls (p = 0.031 and 0.041, respectively). Our data indicates a relationship between the carrier status of HSPA1B (1267)G and TLR4 (896)G alleles and the development of recurrent UTI in childhood independently of other renal abnormalities, while raising further questions about the clinical and therapeutic relevance of these polymorphisms in everyday pediatric nephrology.

The alteration of TLR2 and TLR4 expression in the duodenal mucosa of patients with CD supports the potential implication of innate immune system in the pathomechanism of this disease.

Carrier state of the tested CD14, TLR4, and CARD15 SNPs is not associated with NEC risk in VLBW infants.

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.