Prediction of Johne's disease state based upon quantification of T cell markers and their interaction with macrophages in the bovine intestine

Authors: JENVEY, C - US Department Of Agriculture (USDA); Shircliff, Adrienne; Obando Marrero, Elsa; Stabel, Judith

Submitted to: Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2021
Publication Date: 4/13/2021
Citation: Jenvey, C.J., Shircliff, A.L., Obando Marrero, E.E., Stabel, J.R. 2021. Prediction of Johne's disease state based upon quantification of T cell markers and their interaction with macrophages in the bovine intestine. Veterinary Research. https://doi.org/10.1186/s13567-021-00925-x.
DOI: https://doi.org/10.1186/s13567-021-00925-x

Interpretive Summary: Confocal microscopy is a widely used method utilizing fluorescence to identify the presence of cell types within tissues and/or bacterial or viral pathogens. This method has been used successfully to detect the presence of bacterial pathogens such as mycobacteria and to correlate that presence with the pathogenesis of disease. Understanding the pathogenesis of the disease and the host immune response to infection will allow us to develop improved diagnostic tools and vaccines. In the present study, mid-ileal tissue from naturally infected cattle was stained for macrophages and T cells, as well as Mycobacterium avium subsp. paratuberculosis (MAP) and visualized by confocal microscopy. The dominant type of T cell present in the intestinal tissue of cows was differentiated by co-staining with markers. Results demonstrated that number and type of T cells present in the tissues of cows that are asymptomatic compared to cows that had severe clinical disease are different. These results provide critical information on the biology of MAP infection within the target tissue and are useful for producers, clinicians and researchers to gauge the involvement of tissue during the different stages of disease.

Technical Abstract: Cell-mediated immune responses to Mycobacterium avium subsp. paratuberculosis (MAP) are regulated by various types of T lymphocytes. The aim of this study was to quantify T cell subsets in the mid-ileum of cows naturally infected with MAP to identify differences during different stages of infection, and to determine whether these subsets could be used as predictors of disease state. Immunofluorescent labeling of T cell subsets and macrophages was performed on frozen mid-ileal tissue sections archived from naturally infected dairy cows in either subclinical or clinical disease status, and noninfected control cows. Comprehensive IF staining for CD4, CD8a, TcR1-N24 (gamma delta), Foxp3, CXCR3 and CCR9 served to define T cell subsets and was correlated with macrophages present. Clinically affected cows demonstrated significantly higher numbers of CXCR3+ (Th1-type) and CCR9+ (total small intestinal lymphocytes) cells at the site of infection compared to the subclinical cows and noninfected controls. Further, predictive modeling indicated a significant interaction between CXCR3+ and AM3K+ (macrophages) cells, suggesting that progression to clinical disease state aligns with increased numbers of these cell types at the site of infection. The ability to predict disease state with this model was improved from previous modeling using immunofluorescent macrophage data.