Intestinal Alkaline Phosphatase Regulates Tight Junction Protein Levels

• Published in: Journal of the American College of Surgeons Vol. 222; no. 6; pp. 1009 - 1017
• Main Authors: Liu, Wei, MD, Hu, Dong, MD, Huo, Haizhong, MD, Zhang, Weifeng, MD, Adiliaghdam, Fatemeh, MD, Morrison, Sarah, MD, Ramirez, Juan M., MD, Gul, Sarah S., MD, Hamarneh, Sulaiman R., MD, Hodin, Richard A., MD, FACS
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2016
• Subjects: Alkaline Phosphatase - deficiency; Alkaline Phosphatase - metabolism; Animals; Biomarkers - metabolism; Blotting, Western; Caco-2 Cells; Down-Regulation; Electric Impedance; Fibroblasts - metabolism; Fluorescent Antibody Technique; Humans; Intestinal Mucosa - metabolism; Mice; Mice, Knockout; Permeability; Real-Time Polymerase Chain Reaction; Surgery; Tight Junctions - metabolism; Up-Regulation; DMEM; IL; RT-PCR; TJ; IAP; TEER; TJP; TNF; LPS; MEF
• ISSN: 1072-7515; 1879-1190
• DOI: 10.1016/j.jamcollsurg.2015.12.006

Structured Abstract Background Intestinal alkaline phosphatase (IAP) plays a pivotal role in maintaining gut health and well-being. Oral supplementation with IAP in mice improves gut barrier function and prevents luminal pro-inflammatory factors from gaining access to the circulation. In the present study we sought to explore the relationship between IAP and tight junction protein (TJP) expression and function. Study Design The effect of IAP deletion on TJP levels was studied in mouse embryonic fibroblasts (MEFs) generated from IAP- Knockout and Wild type mice. Regulation of TJPs by IAP was assayed in the human colon cancer Caco2 and T84 cells by overexpressing the human IAP gene. TJP levels and localization were measured by using RT q-PCR and antibodies targeting the specific TJPs. Finally, the effect of IAP on inflammation-induced intestinal permeability was measured by in vitro trans-well epithelial electrical resistant (TEER). Results IAP gene deletion in MEFs resulted in significantly lower levels of ZO-1 , ZO-2 and OCCLUDIN compared to wild-type control cells, whereas IAP overexpression in Caco-2 and T84 cells resulted in approximate two fold increases in the mRNA levels of ZO-1 and ZO-2. IAP treatment ameliorated Lipopolysaccharide-induced increased permeability in the Caco2 trans-well system. Furthermore, IAP treatment preserved the localization of the ZO-1 and OCCLUDIN proteins during inflammation and was also associated with improved epithelial barrier function. Conclusions IAP is a major regulator of gut mucosal permeability and appears to work at least partly through improving TJP levels and localization. These data provide a strong foundation to develop IAP as a novel therapy to maintain gut barrier function.