ZAP-70, CTLA-4 and proximal T cell receptor signaling in cows infected with Mycobacterium avium subsp. paratuberculosis

Authors

• Fernando L. Leite, Iowa State University, Ames & University of Minnesota, St. Paul
• Livia B. Eslabão, Federal University of Pelotas
• Bruce Pesch, USDA-ARS, National Animal Disease Center, Ames
• J. P. Bannantine, USDA-ARS, National Animal Disease CenterFollow
• Timothy A. Rienhardt, USDA-ARS, National Animal Disease Center
• Judith R. Stabel, USDA-ARS, National Animal Disease CenterFollow

Document Type

Article

Date of this Version

2015

Citation

Veterinary Immunology and Immunopathology 167 (2015) 15–21

http://dx.doi.org/10.1016/j.vetimm.2015.06.017

Comments

U.S. government works are not subject to copyright.

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 70kDa) 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 subclinical (n = 6) and clinical stages of paratuberculosis (n = 6) were cultured alone (medium only), and with concanavalin A, and a whole cell sonicate of MAP for 24, 72 and 144 h 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.