455609 Dextran Sodium Sulfate Exposure Affects Intestinal Mucus Integrity

Monday, November 14, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Jaclyn Lock1, Taylor Carlson2, Albert Chen2 and Rebecca L. Carrier1,2, (1)Bioengineering, Northeastern University, Boston, MA, (2)Chemical Engineering, Northeastern University, Boston, MA

Dextran Sodium Sulfate Exposure Affects Intestinal Mucus Integrity

Jaclyn Y. Lock1, Taylor Carlson2, Albert Chen2, Rebecca L. Carrier1,2

1Department of Bioengineering, 2Department of Chemical Engineering, Northeastern University

Introduction: Dextran sodium sulfate (DSS) is frequently utilized to induce intestinal inflammation in animal models of colitis. This model is heavily used since it mimics the histological features of colitis, but the mechanism by which DSS induces inflammation remains unclear. Mucus, a natural biomaterial, covers the entire gastrointestinal tract and selectively controls the diffusion of molecules, particulate matter, and microorganisms to the underlying epithelial layer. Thus, we hypothesize that DSS may impact the mucus barrier. In this study, we investigated how DSS exposure affects mucus barrier properties through particle and microbe tracking, and micro-structural analysis. These studies may provide information on the potential role of an altered mucus barrier in progression of inflammation.

Materials and Methods: Native porcine intestinal mucus was harvested within two hours of sacrifice. Transport properties of green fluorescent protein (GFP) expressing Escherichia coli (E. coli), and 200 nm fluorescent particles with surface carboxyl, amine, and polyethylene glycol (PEG) functionalization were probed using multiple particle tracking technique. Briefly, microbes or particles were diluted in the presence of 1% DSS or maleate buffer (MB) control. 20 sec video particle trajectories were analyzed using a modification of a MATLAB script developed by Maria Kilfoil3 to calculate mean mean-squared displacement (<MSD>) and effective diffusivity (Deff), where MSD = [x(t + τ) – x(t)]2 + [y(t + τ) – y(t)]2 and Deff = MSD * 4τ, x(t) and y(t) represent the particle coordinates at a given time and τ is the time scale. To image the changes in particle and microbe distribution within lectin-stained mucus exposed to DSS or MB control, z-stack images were obtained using a confocal microscope. Scanning electron microscopy was utilized to visualize micro-structural changes when 1% DSS was dosed to porcine intestinal mucus. StudentÕs T-test was used to determine significance between particle and microbe transport with α = 0.05.

Fig 1: Escherichia coli mixed with MB control or 1% DSS and dosed to intestinal mucus.

Results and Discussion:  Particle diffusion in mucus  exposed to 1% DSS was significantly hindered. Specifically, there was a 8-, 3-, and 5- fold decrease in <MSD> for amine-, carboxyl-, and PEGylated particles when dosed with 1% DSS compared to MB control. Interestingly, for E. coli undergoing active transport, the microbes moved faster in the presence of 1% DSS in intestinal mucus and there was an increase in linear trajectories (Fig. 1).

Conclusion: These results indicate that a 1% DSS solution does alter mucus barrier properties, both with respect to particles and microbes. Further in vivo studies investigating impact of orally dosed DSS on a mucus layer on intact tissue will facilitate understanding the role of DSS in inflammation.

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