Salmonella enteritidis FliC (flagella filament protein) induces human beta-defensin-2 mRNA production by Caco-2 cells.

Antimicrobial peptides are crucial for host defense at mucosal surfaces. Bacterial factors responsible for induction of human beta-defensin-2 (hBD-2) mRNA expression in Caco-2 human carcinoma cells were determined. Salmonella enteritidis, Salmonella typhimurium, Salmonella typhi, Salmonella dublin, and culture supernatants of these strains induced hBD-2 mRNA expression in Caco-2 human carcinoma cells. Using luciferase as a reporter gene for a approximately 2.1-kilobase pair hBD-2 promoter, the hBD-2-inducing factor in culture supernatant of S. enteritidis was isolated. The supernatant factor was heat-stable and proteinase-sensitive. After purification by anion exchange and gel filtration chromatography, the hBD-2-inducing factor was identified as a 53-kDa monomeric protein with the amino-terminal sequence AQVINTNSLSLLTQNNLNK, which is identical to that of the flagella filament structural protein (FliC) of S. enteritidis. Consistent with this finding, the 53-kDa protein reacted with anti-FliC antibody, which prevented its induction of hBD-2 mRNA in Caco-2 cells. In agreement, the hBD-2-inducing activity in culture supernatant was completely neutralized by anti-FliC antibody. In gel retardation analyses, FliC increased binding of NF-kappaB (p65 homodimer) to hBD-2 gene promoter sequences. We conclude that S. enteritidis FliC induces hBD-2 expression in Caco-2 cells via NF-kappaB activation and thus plays an important role in up-regulation of the innate immune response.

Mutational analysis of the BMP-1 gene in patients with gastroschisis.

BACKGROUND: Gastroschisis is a rare abdominal wall defect. Although the pathogenesis of gastroschisis is unknown, there is some evidence of the genetic etiology of gastroschisis. Recently, a functionally null deletion of the mouse bone morphogenic protein-1 (BMP-1) gene resulted in a phenotype that resembled a human neonate with gastroschisis. BMP-1 thus became the first potential candidate gene for gastroschisis. METHODS: To explore this possibility the authors collected blood samples from 11 patients who had gastroschisis. Mutational analysis of exons 2 to 15 of the human BMP-1 gene was performed using genomic polymerase chain reaction, single-strand conformation polymorphism analysis and direct sequencing methods. RESULTS: No mutation of the human BMP-1 gene was observed in any of these patients. CONCLUSION: Although heterogeneous etiologies might be proposed for gastroschisis, our results provide further evidence of a nongenetic etiology for gastroschisis. J Pediatr Surg 36:885-887.