Intestinal tight junctions are severely altered in NEC preterm neonates

Abstract

Background & aims: Necrotizing Enterocolitis (NEC) is a severe inflammatory disorder of the intestine endangering the health and survival of preterm infants. It is well established that the gut barrier is severely damaged in NEC patients, nonetheless an in depth investigation of modifications at the transcriptional and translational levels of tight junction genes and proteins during NEC are still missing. The aim of this study was to investigate changes in the expression of tight junctions and other associated proteins during NEC and determine their correlation to the disease severity. Methods: We examined intestinal specimens from six NEC patients and compared them with six control specimens from patients that underwent surgeries for reasons other than NEC. The expression of genes was analyzed by real time PCR and protein expression by immunohistochemistry. Results: The tight junction genes ZO-1, occludin, cingulin and claudin-4 were significantly down regulated in NEC. Furthermore TLR4, BAX and SIRT1 genes were found to be significantly down regulated while HIF-1A showed a trend of up regulation in NEC patients. These changes were found to correlate with the severity of the disease. Additionally we demonstrated in an ex-vivo model that hypoxic conditions initiated a destructive process of the epithelial barrier. We also showed that the expression of the tight junction proteins ZO-1 and occludin were significantly down regulated in NEC specimens. Conclusions: The expression of tight junction proteins and their encoding genes are significantly altered in NEC. We surmise that SIRT1 and HIF-1A may play a role in controlling these effects. Key Words: hypoxia, necrotizing enterocolitis, tight junctions