Basic Science | Critical Care

Sharven Taghavi, Sarah Abdullah, Juan Duchesne, Derek Pociask, Jay Kolls, Olan Jackson-Weaver

ePoster Presenter: Sharven Taghavi MD, FACS, Tulane School of Medicine

Background: The endothelial glycocalyx (EGX) on the luminal surface of endothelial cells contributes to the permeability barrier of vessels and prevents activation of the coagulation cascade.  EGX damage, which occurs in the shock state, results in endotheliopathy. Interleukin-22 is a cytokine with both pro-inflammatory and anti-inflammatory properties and how IL-22 affects the EGX has not been studied.

Objectives: We hypothesized that IL-22:Fc, a recombinant fusion protein with human IL-22 and the Fc portion of human immunoglobulin G1 (which extends the protein half-life), would not affect EGX shedding in endothelium after injury.

Methods: Human umbilical vein endothelial cells (HUVECs) were exposed to 1 µg/ml lipopolysaccharide (LPS). LPS injured cells (n=284) were compared to HUVECS with LPS injury plus 0.375 µg/ml of IL-22:Fc treatment (n=293) for 12 hours. These two cohorts were compared to control HUVECs (n=286) and HUVECs exposed to IL-22:Fc alone (n=269). Cells were fixed and stained with FITC-labelled wheat germ agglutinin to quantify EGX. Total RNA was collected and select mRNAs quantified by RT-qPCR using SYBR green fluorescence.

Results: Exposure of HUVECS to LPS resulted in degradation of the EGX compared to control (5.86 vs. 6.09 AU, p=0.01).  IL-22:Fc alone also resulted in degradation of EGX when compared to control (5.08 vs. 6.09 AU, p=0.01).  Treatment with IL:22:Fc after LPS injury resulted in less degradation of EGX compared to LPS injury alone (5.86 vs. 5.08 AU, p=0.002).  Expression of the IL-22Ra1 receptor was not different for IL-22:Fc treated compared to LPS injury only (0.72 vs. 0.97 relative expression, p=0.15).  Treatment with IL-22:Fc after LPS injury resulted in less matrix metalloproteinase-2 (0.66 vs. 1.91 relative expression, p=0.04) and matrix metalloproteinase-14 (0.72 vs. 2.47 relative expression, p=0.04).

Conclusion: IL-22:Fc alone induces EGX degradation.  However, IL-22:Fc treatment after LPS injury appears to mitigate EGX degradation.  This protective effect appears to be mediated via reduced expression of metalloproteinases.