Purpose. To investigate the expression of innate immunity components and cytokines in the gastric mucosa among H. pylori infected and uninfected children. Materials and Methods. Biopsies of the antral gastric mucosa from children with dyspeptic symptoms were evaluated. Gene expressions of innate immunity receptors and cytokines were measured by quantitative real-time PCR. The protein expression of selected molecules was tested by immunohistochemistry. Results. H. pylori infection did not lead to a significant upregulation of MyD88, TLR2, TLR4, CD14, TREM1, and TREM2 mRNA expression but instead resulted in high mRNA expression of IL-6, IL-10, IFN-γ, TNF-α, and CD163. H. pylori cagA(+) infection was associated with higher IL-6 and IL-10 mRNA expression, as compared to cagA(−) strains. H. pylori infected children showed increased IFN-γ and TNF-α protein levels. IFN-γ mRNA expression correlated with both H. pylori density of colonization and lymphocytic infiltration in the gastric mucosa, whereas TNF-α protein expression correlated with bacterial density. Conclusion. H. pylori infection in children was characterized by (a) Th1 expression profile, (b) lack of mRNA overexpression of natural immunity receptors, and (c) strong anti-inflammatory activities in the gastric mucosa, possibly resulting from increased activity of anti-inflammatory M2 macrophages. This may explain the mildly inflammatory gastric inflammation often observed among H. pylori infected children.

Most inflammatory bowel diseases (IBDs) are classic complex disorders represented by common alleles. Here we aimed to define the genetic architecture of pediatric and adult-onset IBDs for the Polish population. A total of 1495 patients were recruited, including 761 patients with Crohn’s disease (CD; 424 pediatric), 734 patients with ulcerative colitis (UC; 390 pediatric), and 934 healthy controls. Allelotyping employed a pooled-DNA genome-wide association study (GWAS) and was validated by individual genotyping. Whole exome sequencing (WES) was performed on 44 IBD patients diagnosed before 6 years of age, 45 patients diagnosed after 40 years of age, and 18 healthy controls. Altogether, out of 88 selected SNPs, 31 SNPs were replicated for association with IBD. A novel BRD2 (rs1049526) association reached significance of P = 5.2 × 10−11 and odds ratio (OR) = 2.43. Twenty SNPs were shared between pediatric and adult patients; 1 and 7 were unique to adult-onset and pediatric-onset IBD, respectively. WES identified numerous rare and potentially deleterious variants in IBD-associated or innate immunity-associated genes. Deleterious alleles in both groups were over-represented among rare variants in affected children. Our GWAS revealed differences in the polygenic architecture of pediatric- and adult-onset IBD. A significant accumulation of rare and deleterious variants in affected children suggests a contribution by yet unexplained genetic components.

Twenty-six weeks likely represent the safe duration of combined IFX/immunomodulatory therapy in our sample of pediatric patients with CD.

These data suggest that MBL deficiency may be associated with CD but not with UC in pediatric patients. The possible role of MBL in IBD requires confirmation in larger series and further investigation of the mechanisms involved.

In H. pylori-negative children, gastritis was associated with an increased percentage of activated NK and T cells, and intermediate-differentiated peripheral blood CD4(+) T cells, which was more pronounced in H. pylori-positive children who also showed an increased B-cell response. However, increased inflammation was only associated with the elevation of CD4(+) T-cell percentage in H. pylori-positive children as well as B-cell percentage in H. pylori-negative children with gastritis.