Paneth cell hyperplasia and metaplasia in necrotizing enterocolitis.

Paneth cell dysfunction has been suggested in necrotizing enterocolitis (NEC). The aim of this study was to i) study Paneth cell presence, protein expression, and developmental changes in preterm infants with NEC and ii) determine Paneth cell products and antimicrobial capacity in ileostomy outflow fluid. Intestinal tissue from NEC patients (n = 55), preterm control infants (n = 22), and term controls (n = 7) was obtained during surgical resection and at stoma closure after recovery. Paneth cell abundance and protein expression were analyzed by immunohistochemistry. RNA levels of Paneth cell proteins were determined by real-time quantitative RT-PCR. In ileostomy outflow fluid, Paneth cell products were quantified, and antimicrobial activity was measured in vitro. In acute NEC, Paneth cell abundance in small intestinal tissue was not significantly different from preterm controls. After recovery from NEC, Paneth cell hyperplasia was observed in the small intestine concomitant with elevated human alpha-defensin 5 mRNA levels. In the colon, metaplastic Paneth cells were observed. Ileostomy fluid contained Paneth cell proteins and inhibited bacterial growth. In conjunction, these data suggest an important role of Paneth cells and their products in various phases of NEC.