TDK conference 2016

Matriptase is a type II transmembrane serine protease found in almost all types of epithelial cells. It is found in abundance in the GI tract, particularly in the small intestine. Many intestinal pathologies result in epithelial denudation and compromised barrier and most treatment options target the specific pathogens with less emphasis on repair of the intestinal wall and restoration of the physiological epithelial barrier.

The aim of this study was to gain a more detailed understanding of the mechanisms by which this transmembrane serine protease is able to affect the intestinal epithelium using porcine intestinal epithelial IPEC-J2 cells cultured on membrane inserts. These monolayers were treated with selective matriptase inhibitor, MI-432 at 10, 25, 50 μM, and sphingosine-1-phosphate (S1P) as a matriptase activator at 200 ng/ml. Neutral red uptake assay proved that cell viability was not altered in cells treated with matriptase modulators compared to that of control groups. After exposure of the cells to matriptase inhibitor, it was found that not only did the transepithelial electrical resistance (TER) decrease but there were acute disturbances in the cellular redox environment, which was detected by Amplex red method. Using immunofluorescence staining it was observed that after inhibition of matriptase tight junction protein, occluding showed decreased expression along the cell membrane to controls. In contrast, in the IPEC-J2 cell monolayers that were treated with S1P, time dependant increase in TER could be seen and there were no detectable changes in the ROS activity. Occludin could be seen with an enhanced presence in the tight junctions of the monolayers.

In conclusion, it was found that inhibition of matriptase with MI-432 has a negative effect on the intestinal barrier which is at least partly related to disturbances in the ROS environment and the redistribution of occludin. However, the treatment of the monolayers with S1P resulted in enhanced TER values without significant ROS fluctuations. S1P had also a beneficial impact on the distribution of occludin to the tight junction. Considering that post treatment cell viability studies were positive, these results are encouraging and should prompt further investigation into what therapeutical potential of matriptase activation has in terms of restoring normal barrier function in the treatment of pathologies such as IBD, Crohn’s disease, Johne’s disease, colitis ulcerosa and different types of gastroenteritis affecting livestock which could be important in decreasing the degree of production losses and mortality on a herd level.