Defense Date

3-28-2022

Graduation Date

Spring 5-13-2022

Availability

Immediate Access

Submission Type

thesis

Degree Name

MS

Department

Biomedical Engineering

School

Rangos School of Health Sciences

Committee Chair

Melikhan Tanyeri

Committee Member

Kimberly Williams

Committee Member

Gerard Magill

Committee Member

Bin Yang

Keywords

Adhesion, Bacteria, E. coli, Mannose, Microfluidic

Abstract

The study of bacterial adhesion to host cells is important in understanding bacterial pathogenesis and developing new therapeutic approaches. Here, we studied bacterial adhesion under shear stress using a novel microfluidic method. Specifically, the adhesion of a uropathogenic E. coli strain (FimHOn, ATCC 700928/CFT073) to mannose-modified substrates was studied under flow conditions. The FimHOn E. coli strain expresses FimH which is a mannose-specific adhesin found on the fimbriae that binds to glycoproteins on the epithelium. We developed a microfluidic method that mimics bacterial adhesion to urothelial cells. First, the microfluidic channels were modified by sequentially adsorbing BSA-mannose and BSA onto channel surfaces. Bacterial solutions were then introduced to the microfluidic channels and bacterial interactions with the modified surface were imaged at 5 fps for 2 minutes using phase contrast microscopy under flow conditions. Manual tracking and TrackMate extensions of ImageJ were used to analyze and quantify surface adhesion of bacteria on the simulated epithelial surface. Bacteria-surface interactions were studied with substrates modified using 8.3µg/mL, 16.7µg/mL, and 25.0µg/mL BSA-mannose solutions. Through image analysis, the percentage of bacteria interacting with the surface and the total interaction times were determined. The results indicated that as mannose concentration increased the average transient adhesion time and percentage of bacteria adhered to the surface also increased. It was also observed that bacteria permanently attached to the surface increased with time. Overall, our results show that FimHOn E. coli specifically and transiently interacts with the mannose-modified surface. By mimicking molecular interactions and flow-induced shear stress within the gastrointestinal, respiratory, and urogenital tracts, our microfluidic platform may help explain mechanisms underlying bacterial infections at the mucosal epithelium. Overall, our microfluidic approach provides a favorable platform to study bacterial host cell interactions to enable drug discovery and testing.

Language

English

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