Document Type

Thesis - Open Access

Award Date

2018

Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

First Advisor

Radhey Shyam Kaushik

Abstract

Gastro-intestinal (GI) tract harbors largest number of microbiota as well as the largest number of immune cells for a given tissue. The host needs to mount an effective immune response against invading pathogens and tolerance against commensals. Thus, regulatory mechanism and barrier function of the GI tract are of utmost importance for appropriate host microbe interaction and gut homeostasis. Intestinal epithelial cells (IECs) act as the first line of defense against invading pathogens. IECs recognize pathogens and commensals and mount an effective innate immune response. Such recognition of pathogens is mediated through germ line encoded pattern recognition receptors (PRRs). Intestinal sub-epithelial myofibroblasts (ISEMFs) reside just beneath the surface epithelium and are involved in maturation and differentiation of epithelium. ISEMFs protect from pathogens that breach surface epithelium by expressing PRRs. Lack of stable intestinal epithelial and sub-epithelial myofibroblast cell lines has slowed down scientific studies on these cells. In this study, we established and characterized ISEMF cells from the ileum of a 2-day old calf. We also had generated stable bovine ileal epithelial cell (BIEC-c4) cultures in our lab. On real time-quantitative polymerase chain reaction (RT-qPCR) analysis both these cell types expressed Toll-like receptors (TLRs) 1-9. To investigate their responses to various pathogen-associated molecular patterns (PAMPs), we stimulated both cell types for 3 hours and 24 hours with various PAMPs. The RT-qPCR assay was used to investigate changes in TLR gene expression and in cytokine genes following stimulation. Lipopolysaccharide, peptidoglycan, and flagellin were used as bacterial ligands of surface PRRs. Similarly, γ-D-Glu-mDAP, muramyl dipeptide, polyinosonic:polycytidylic acid, poly I:C complexed with lyovec, and imiquimod were used as ligands of cytosolic and endosomal PRRs. Bovine ileal ISEMFs responded to bacterial PAMPs and to ligands of cytosolic and endosomal PRRs by significantly altering TLR gene expression. Unlike bovine ISEMFs, BIEC-c4 cells responded only to bacterial ligands. Thus, we conclude that bovine ileal ISEMF can be a good model to study innate immune responses and signaling pathways occurring at subepithelial compartment. However, BIEC-c4 cells may serve as a good in-vitro model to study enteric infectious disease pathogenesis and innate immune responses associated with them.

Library of Congress Subject Headings

Myofibroblasts.
Epithelial cells.
Cattle -- Immunology.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

164

Publisher

South Dakota State University

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Rights Statement

In Copyright