Spermidine Stimulates T Cell Protein-tyrosine Phosphatase-mediated Protection of Intestinal Epithelial Barrier Function

Harrison M Penrose,Ronald R Marchelletta,Moorthy Krishnan,Declan F Mccole

doi:10.1074/jbc.m113.475962

Abstract

The gene locus encoding protein-tyrosine phosphatase non-receptor type 2 (PTPN2) has been associated with inflammatory bowel disease. Expression of the PTPN2 gene product, T cell protein-tyrosine phosphatase (TCPTP), in intestinal epithelial cells has been shown to play an important role in the protection of epithelial barrier function during periods of inflammation by acting as a negative regulator of the proinflammatory cytokine IFN-γ. Therefore, agents that increase the activity of TCPTP are of general interest as modifiers of inflammatory signaling events. A previous study demonstrated that the small molecule spermidine is a selective activator of TCPTP in vitro. The aim of this study was to investigate whether activation of TCPTP by spermidine was capable of alleviating IFN-γ-induced, proinflammatory signaling and barrier dysfunction in human intestinal epithelial cells. Studies revealed that treatment of T84 and HT29/cl.19A colonocytes with spermidine increased both TCPTP protein levels and enzymatic activity, correlating with a decrease in the phosphorylation of the signal transducers and activators of transcription 1 and 3, downstream mediators of IFN-γ signaling, upon coadministration of spermidine to IFN-γ-treated cells. On a functional level, spermidine protected barrier function in the setting of inflammation, restricting the decrease in transepithelial electrical resistance and the increase in epithelial permeability induced by IFN-γ in coincubation experiments. These data implicate spermidine as a potential therapeutic agent to treat conditions associated with elevated IFN-γ signaling and a faulty mucosal barrier.

Highlights

T cell protein-tyrosine phosphatase (TCPTP) is a negative regulator of proinflammatory cytokine signaling and may be a therapeutic target for Inflammatory bowel disease (IBD)
Spermidine Increases TCPTP Expression at the Protein Level—To study whether spermidine had any effect on TCPTP expression in human IECs, T84 and HT29 cells grown as monolayers on permeable supports were treated with increasing concentrations of spermidine (0.1, 1.0, and 10 ␮M) for 24 h
In T84 cells treated with 10 ␮M spermidine, TCPTP levels were 2.2 Ϯ 0.3fold greater than those found in control cells (p Ͻ 0.05, Fig. 1A)

Summary

Introduction

Expression of the PTPN2 gene product, T cell protein-tyrosine phosphatase (TCPTP), in intestinal epithelial cells has been shown to play an important role in the protection of epithelial barrier function during periods of inflammation by acting as a negative regulator of the proinflammatory cytokine IFN-␥. Spermidine protected barrier function in the setting of inflammation, restricting the decrease in transepithelial electrical resistance and the increase in epithelial permeability induced by IFN-␥ in coincubation experiments. These data implicate spermidine as a potential therapeutic agent to treat conditions associated with elevated IFN-␥ signaling and a faulty mucosal barrier

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Results

Conclusion