Recruitment of dendritic cells is responsible for intestinal epithelial damage in the pathogenesis of necrotizing enterocolitis by Cronobacter sakazakii.

Abstract

Cronobacter sakazakii is a Gram-negative pathogen associated with the cases of necrotizing enterocolitis (NEC) that result from formula contamination. In a mouse model of NEC, we demonstrate that C. sakazakii infection results in epithelial damage by recruiting greater numbers of dendritic cells (DCs) than macrophages and neutrophils in the gut and suppresses DC maturation, which requires outer membrane protein A (OmpA) expression in C. sakazakii. Pretreatment of intestinal epithelial cell monolayers with supernatant from OmpA(+) C. sakazakii/DC culture markedly enhanced membrane permeability and enterocyte apoptosis, whereas OmpA(-) C. sakazakii/DC culture supernatant had no effect. Analysis of OmpA(+) C. sakazakii/DC coculture supernatant revealed significantly greater TGF-β production compared with the levels produced by OmpA(-) C. sakazakii infection. TGF-β levels were elevated in the intestinal tissue of mice infected with OmpA(+) C. sakazakii. Cocultures of CaCo-2 cells and DCs in a "double-layer" model followed by infection with OmpA(+) C. sakazakii significantly enhanced monolayer leakage by increasing TGF-β production. Elevated levels of inducible NO synthase (iNOS) were also observed in the double-layer infection model, and abrogation of iNOS expression prevented the C. sakazakii-induced CaCo-2 cell monolayer permeability despite the presence of DCs or OmpA(+) C. sakazakii/DC supernatant. Blocking TGF-β activity using a neutralizing Ab suppressed iNOS production and prevented apoptosis and monolayer leakage. Depletion of DCs in newborn mice protected against C. sakazakii-induced NEC, whereas adoptive transfer of DCs rendered the animals susceptible to infection. Therefore, C. sakazakii interaction with DCs in intestine enhances the destruction of the intestinal epithelium and the onset of NEC due to increased TGF-β production.

• Authors: Claudia N Emami, Rahul Mittal, Larry Wang, Henri R Ford, Nemani V Prasadarao
• Journal: Journal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 186 Issue 12 Pg. 7067-79 (Jun 15 2011) ISSN: 1550-6606 [Electronic] United States
• PMID: 21551359 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Bacterial Outer Membrane Proteins
• Transforming Growth Factor beta
• OMPA outer membrane proteins
• Nitric Oxide Synthase Type II

Topics

• Animals
• Bacterial Outer Membrane Proteins (physiology)
• Caco-2 Cells
• Coculture Techniques
• Cronobacter sakazakii (pathogenicity)
• Dendritic Cells (microbiology, pathology)
• Enterocolitis, Necrotizing (etiology, microbiology, pathology)
• Humans
• Intestinal Mucosa (microbiology, pathology)
• Mice
• Nitric Oxide Synthase Type II (metabolism)
• Transforming Growth Factor beta (metabolism)