|LEITE, FERNANDO - Iowa State University|
|ESLABAO, LIVIA - Federal University Of Pelotas|
Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2015
Publication Date: 9/15/2015
Citation: Leite, F.L., Eslabao, L.B., Pesch, B.A., Bannantine, J.P., Reinhardt, T.A., Stabel, J.R. 2015. ZAP-70, CTLA-4, and proximal T cell receptor signaling in cows infected with Mycobacterium avium subsp. paratuberculosis. Veterinary Immunology and Immunopathology. 167(1-2):15-21. doi: 10.1016/j.vetimm.2015.06.017.
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 measurements on immune cells from cows in different stages of disease and how these 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. 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: Paratuberculosis is a chronic intestinal disease of ruminant animals caused by Mycobacterium avium subsp. paratuberculosis (MAP). A hallmark of paratuberculosis is a transition from a cell-mediated Th1 type response to a humoral Th2 response with the progression of disease from a subclinical to clinical state. The objective of this study was to investigate the expression of two crucial molecules in T cell function, ZAP-70 (zeta-chain-associated protein of 70 kDa) and CTLA-4 (cytotoxic T-lymphocyte antigen-4), in cows naturally infected with MAP. Peripheral blood mononuclear cells (PBMCs) isolated from control non-infected cows (n=5), and cows in clinical (n=6) and subclinical stages of paratuberculosis (n=6) were cultured alone (medium only), with concanavalin A, and a whole cell sonicate of MAP for 24, 72 and 144 hours to measure the dynamic changes of ZAP-70 and CTLA-4 expression on CD4, CD8, and gamma delta T cells. Flow cytometry was also performed to measure ZAP-70 phosphorylation to examine proximal T cell receptor signaling in animals of different disease status. The surface expression of CTLA-4 was increased in animals in subclinical stage of infection while levels of ZAP-70 were decreased in CD4+ T cells of both subclinical and clinical animals, indicating a change in T cell phenotype with disease state. Interestingly, proximal T cell receptor signaling was not altered in infected animals. This study demonstrated changes in crucial signaling molecules in animals infected with MAP, thereby elucidating T cell alterations associated with disease progression.