Performing Department
Animal and Avian Sciences
Non Technical Summary
Gastrointestinal (GI) infections can result in significant financial losses for the cattle industry in the USA, amounting to billions of dollars annually. Robust mucosal immune responses can control infections in the gastrointestinal tract. GI mucosal intraepithelial lymphocytes (IELs) primarily consist of T cells, representing over 60% of the total T cell population in the entire organism. IELs patrol the epithelial cells that line the mucosa, ensuring the gut barrier's homeostasis by managing infections through the cytotoxicity of infected and/or damaged epithelial cells, as well as regulating mucosal immune responses. In contrast to T cells found in the circulation and lymphoid tissues, IELs display distinct phenotypic, developmental, and functional characteristics that underscore their essential functions within the GI tract. Induced IELs (iIELs) are conventional T cells that have been activated and are migrating to, as well as residing in, the mucosa. IELs are crucial for managing pathogens and preserving the integrity of the gut barrier. The processes that govern the shift from immunity to tolerance in iIELs are still not well understood. iIELs, similar to conventional T cells, express T cell receptor (TCR) αβ, which is associated with co-receptor CD3 to convey signaling from ligand binding to the TCR. The mechanisms by which iIELs are activated by TCR or pathogens remain unclear.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
This study aims to examine CD4+ iIELs, a significant population of T cells within the bovine gastrointestinal mucosa, to elucidate their responses to antigenic and pathogenic stimulation. The insights gained from this project will identify novel targets associated with the roles of CD4+ iIELs in immunity, tolerance, and immune suppression. This project may facilitate new strategies for immune intervention in chronically infected cattle, particularly in identifying measures to counteract the immune suppression in CD4+ iIELs induced by pathogens. The findings of this project may also provide insights into mucosal immunology in other domestic animals. Cooperia spp. is prevalent in cow/calf operations in the United States, which has exhibited drug resistance and significantly affects cattle productivity by diminishing weight gain and feed intake. Understanding of the role of CD4+ iIELs will greatly benefit the control of Cooperia and other mucosal pathogens in general.
Project Methods
Aim 1: Delineate the activation of CD4+ iIELs in vitro. We will examine how CD4+ iIELs are activated in vitro. We will first investigate how CD4+ iIELs respond to TCR stimulation in terms of cytokine generation and killing capabilities. In addition, we will test the regulatory function of these TCR-stimulated CD4+ iIELs in a coculture system. Then we will determine how CD4+ iIELs respond to pathogen-associated molecular patterns (PAMPs) like the ligands to Toll-like receptors (TLRs). Third, using specific inhibitors, we will determine if the responsiveness of CD4+ iIELs to Cooperia spp. (Cooperia) antigens is dependent on specific TLRs. Lastly, utilizing bovine organoid coculture systems, we will investigate the ability of activated CD4+ iIELs to integrate into small intestinal epithelium.Aim 2: Define modulation of CD4+ iIELs by Cooperia in animals. We will examine how Cooperia regulates CD4+ iIELs in experimentally infected cattle. We will ask a) whether phenotypes of CD4+ iIELs change during acute and chronic infections; b) if functions of CD4+ iIELs alter after acute and chronic infections, including killing ability, inhibitory functions, and integration into organoids; and c) if Cooperia impairs the responsiveness of CD4+ iIELs to subsequent stimulation via TCR and TLRs.Aim 3: Identify protein signatures of CD4+ iIEL activation. We will use high-throughput quantitative proteomics to uncover major molecules responsible for the activation of CD4+ iIELs by comparing CD4+ iIELs activated in vitro and those obtained in infected animals. The identified targets will be confirmed for transcription and functions.