Total parenteral nutrition-induced apoptosis in mouse intestinal epithelium: regulation by the Bcl-2 protein family

• Published in: Pediatric surgery international 2002-10, Vol.18 (7), p.570-575
• Main Authors: WILDHABER, B. E, LYNN, K. N, YANG, H, TEITELBAUM, D. H
• Format: Article
• Language: English
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Apoptosis; Biological and medical sciences; Emergency and intensive care: metabolism and nutrition disorders. Enteral and parenteral nutrition; Epithelial Cells - metabolism; Flow Cytometry; Gastroenterology. Liver. Pancreas. Abdomen; Intensive care medicine; Intestinal Mucosa - metabolism; Male; Medical sciences; Mice; Mice, Inbred C57BL; Other diseases. Semiology; Parenteral Nutrition, Total; Proto-Oncogene Proteins c-bcl-2 - physiology; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus
• ISSN: 0179-0358; 1437-9813
• DOI: 10.1007/s00383-002-0869-1

Apoptosis of intestinal epithelial cells (EC) plays a role in total parenteral nutrition (TPN)-induced villus atrophy. Among the mediators of apoptosis in EC are some members of the Bcl-2 family of proteins. Bcl-2 members can either be anti- (Bcl-2, Bcl-x(L), Bcl-w) or pro-apoptotic (Bax, Bak, Bid, Bad, Bcl-x(S)). To determine whether the observed increase in apoptosis induced by TPN is associated with an alteration in these Bcl-2 members' mRNA expression, mice were randomized to either TPN or oral feeding (controls). Animals were killed after 7 days and the intestine was harvested. EC were purified with magnetic beads. Apoptosis was detected by cell-surface expression of phosphatidylserine using flow cytometry. EC mRNA expression was determined by reverse-transcriptase polymerase chain reaction. Results were expressed relative to beta-actin. TPN resulted in a significant ( P < 0.05, unpaired t-test) increase in apoptosis: TPN 29.4 +/- 11.3% versus control 14.4 +/- 5.1%. The expression of the pro-apoptotic members Bax, Bak, Bid, and Bcl-x(S) was significantly ( P < 0.05) decreased after TPN. In contrast, a significant increase was observed in the anti-apoptotic member Bcl-2. mRNA expression of Bcl-w, Bad, and Bcl-x(L) was not significantly different between the control and TPN groups. Thus TPN-induced apoptosis was associated with an increased expression of anti-apoptotic factors and a decrease in pro-apoptotic factors. This contrasts with other reports where these factors showed converse effects under apoptotic conditions. Our results may demonstrate a unique regulatory pathway that may counter the observed increase in TPN-induced EC apoptosis.