Evaluating the cytokine profile of the WC1+ gamma delta T cell subset in the ileum of cattle with the subclinical and clinical forms of MAP infection

Authors: ALBARRAK, S - Iowa State University; Waters, Wade; Stabel, Judith; HOSTETTER, J - Iowa State University

Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2018
Publication Date: 5/19/2018
Citation: Albarrak, S.M., Waters, W.R., Stabel, J.R., Hostetter, J.M. 2018. Evaluating the cytokine profile of the WC1+ gamma delta T cell subset in the ileum of cattle with the subclinical and clinical forms of MAP infection. Veterinary Immunology and Immunopathology. 201:26-31. https://doi.org/10.1016/j.vetimm.2018.05.003.
DOI: https://doi.org/10.1016/j.vetimm.2018.05.003

Interpretive Summary: Johne's disease is a chronic, debilitating intestinal disorder in cattle characterized by diarrhea, reduced feed intake, weight loss and death. Cattle usually become infected as young calves by ingesting feces containing the causative bacteria. However, symptoms of disease do not usually present themselves until the animals reach 3 to 5 years of age or even older. During this time the animal is infected and may be shedding the organism in its feces without showing any clinical signs of disease. In addition to reduced milk production by these animals, they also present a potential infective threat to the rest of the herd. Little is known how the cow controls this infection in the early stages and what happens to allow full-blown disease to develop. This study presents information on the role of a specific group of T cells in cows in different stages of disease and how the responses of these cells differ between the stages of disease. This information helps us with understanding key events in the progression of disease from the early asymptomatic stage to more advanced clinical disease. Results suggest this group of T cells is part of a protective mechanism in animals in the early stage of infection. Understanding the host immune response to this pathogen will help us develop new therapeutic strategies as well as new diagnostic tools and vaccines to prevent the spread of disease.

Technical Abstract: In the present study, we evaluated expression of IFN-gamma, IL-17, TNF-alpha, IL-10 and TGF-beta by mucosal cells, including WC1+ gamma delta T cells, in ileal tissues taken from non-infected cattle and cattle naturally infected with Mycobacterium avium subsp paratuberculosis (MAP). Infected cattle were either in the subclinical or clinical stage of infection. We hypothesized that the cytokine profile of the WC1+ gamma delta T cell subset would be different between subclinical and clinical cattle. Our data indicate a significant increase in the numbers of mucosal cells, including WC1+ gamma delta T cells, expressing IL-10 in clinical cattle compared to subclinical and non-infected cattle. We observed a significant increase in TGF-beta expression by total mucosal cells in clinically infected cattle. Expression of IFN-gamma, IL-17 and TNF-alpha in mucosal cells, including the WC1+ gamma delta T cell subset, was identified in all examined groups. However, our data indicate that the stage of infection did not significantly influence expression of these proinflammatory cytokines. This study demonstrates changes in the cytokine mRNA expression profile of mucosal cells in the ileum, and specifically WC1+ gamma delta T cells, as cattle progress to the clinical disease. The change is characterized by an increase in expression of anti-inflammatory cytokines.