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Increased Expression and Internalization of the Endotoxin Coreceptor CD14 in Enterocytes Occur as an Early Event in the Development of Experimental Necrotizing Enterocolitis

Exposure of IEC-6 enterocytes to LPS led to an initial, transient increase in CD14 expression. The early increase in CD14 expression was associated with internalization of CD14 to a perinuclear compartment where increased colocalization with TLR4 was noted. The in vivo significance of these findings is suggested as treatment of mice with LPS led to an early increase in CD14 expression in the intestinal mucosa, whereas the persistent endotoxemia of experimental NEC was associated with decreased CD14 expression within enterocytes.  This process may contribute to the early activation of the intestinal inflammatory response that is observed in the development of NEC.
 
Here, CD14 is internalized along with TLR4 in IEC-6 cells stimulated with LPS. IEC-6 cells were stimulated with media alone or LPS (50 μg/mL) for 1 hour and prepared for confocal immunofluorescence microscopy. A to C, Untreated cells; D to F, LPS-treated cells. Shown are the expression of CD14 (A and D), TLR4 (B and E), or colocalization (C and F), as calculated using ImageJ software.

Above, the transient response of CD14 expression to LPS is implicated in the development of NEC. C57Bl/6 mice were subjected to an experimental model of NEC. Semiquantitative reverse transcriptase PCR analysis of ileal mucosa mRNA (A) and Western blot analysis of ileal mucosal scrapings (B) demonstrate decreased expression of CD14 as compared with control mice.
 
Authors
Mollen KP, Gribar SC, Anand RJ, Kaczorowski DJ, Kohler JW, Branca MF, Dubowski TD, Sodhi CP, Hackam DJ
J Pediatr Surg
2008 June
 
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Last Update
January 18, 2011
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Last Update
January 18, 2011
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