Epidermal growth factor reduces autophagy in intestinal epithelium and in the rat model of necrotizing enterocolitis

Abstract

Necrotizing enterocolitis (NEC) is a devastating intestinal disease of premature infants. Epidermal growth factor (EGF) is one of the most promising candidates in NEC prophylaxis. Autophagy regulates cell homeostasis, but uncontrolled activation of autophagy may lead to cellular injury. The aim was to evaluate the effects of EGF on intestinal autophagy in epithelial cells and in the rat NEC model and measure autophagy in NEC patients. Intestinal epithelial cells (IEC-6) and the rat NEC model were used to study the effect of EGF on intestinal autophagy. Protein levels of Beclin 1 and LC3II were measured in the intestinal epithelium in both in vivo and in vitro models. Ultrastructural changes in intestinal epithelium were studied by electron microscopy. Expression of Beclin 1, LC3II, and p62 protein was evaluated in biopsies from NEC patients. Autophagy was induced in IEC-6 cells and inhibited by adding EGF into the culture. In the rat NEC model, EGF treatment of NEC reduced expression of Beclin 1 and LC3II in ileal epithelium. Morphologically, typical signs of autophagy were observed in the epithelium of the NEC group, but not in the EGF group. A strong signal for Beclin 1 and LC3II was detected in the intestine from patients with NEC. Autophagy is activated in the intestinal epithelium of NEC patients and in the ileum of NEC rats. Supplementation of EGF blocks intestinal autophagy in both in vivo and in vitro conditions. Results from this study indicate that EGF-mediated protection against NEC injury is associated with regulation of intestinal autophagy.

Smad7 inhibits autocrine expression of TGF-β2in intestinal epithelial cells in baboon necrotizing enterocolitis

“…IEC6 cells (ATCC, Manassas, VA) were cultured at cell passages 17-21 in DMEM with 4 mM L-glutamine adjusted to contain 1.5 g/l sodium bicarbonate and 4.5 g/l glucose and supplemented with 10% (vol/vol) FBS, 50 U/ml penicillin and 50 g/ml streptomycin at 37°C and 5% (vol/vol) CO2 (33). Media were changed at 24 h postplating and every 72 h thereafter.…”

Relationships between cobalamin, epidermal growth factor, and normal prions in the myelin maintenance of central nervous system

“…We have observed whorls of myelin in the SC white matter of Cbl-D rats (Scalabrino, 2009) that are similar to those of CNS autophagy, and it has been shown that abnormal autophagy plays a role in the pathogenesis of Creutzfeldt-Jakob disease and experimental scrapie (Huang and Klionsky, 2007;Levine and Kroemer, 2008;Martinez-Vicente and Cuervo, 2007;Rubinsztein et al, 2005). We tested this hypothesis by administering rapamycin to ON rats and evaluating its effect on SC white matter by means of optical and electron microscopy for the following reasons: (i) rapamycin is a pharmacological inhibitor of mTOR activity and thus stimulates autophagy (Glick et al, 2010;Huang and Klionsky, 2007;Rubinsztein et al, 2007); (ii) inhibiting mTOR reduces myelination (Norrmén and Suter, 2013;Tyler et al, 2009); (iii) as Cbl deficiency greatly reduces EGF synthesis and levels in rat CNS (see above) and EGF reduces autophagy (Maynard et al, 2010), an increase in autophagy might be expected; and (iv) Cbl deficiency increases the synthesis of TNF-␣ (see above), which has been shown to induce autophagy (Laplante and Sabatini, 2012).…”

Helicobacter hepaticusincreases intestinal injury in a rat model of necrotizing enterocolitis

“…Uncontrolled autophagy leads to increased survival of intracellular bacteria and an uncontrolled proinflammatory response and has been implicated in the pathogenesis of Crohn's disease (48). Our laboratory has discovered the induction of autophagy in the intestinal epithelium of NEC patients and in the rat NEC model (38). Recently, our initial observation was confirmed in the rat and mouse NEC models (43,60).…”