Crosstalk between mammary epithelial cells and peripheral blood mononuclear cells in intrammary infections by Staphylococcus aureus and by distinct coagulase-negative staphylococci species and strains: development an in vitro model

Abstract

Immunological approaches have the potential for preventive and therapeutic intervention for Staphylococcus aureus and coagulase-negative staphylococci (CNS) mastitis and consequently for the milk chain production. Striving for a complete elimination of antimicrobial use in dairy cattle is unrealistic though a reduction is recommended and feasible. From that point of view, innovative tools enabling an increase in the natural ability of animals to resist infection could be of great value. The greatest obstacle in establishing this kind of strategies is a lack of understanding of the host immune response. Although, there are studies that have investigated many aspects of the immune response induced by intramammary infections (IMIs) by S. aureus and CNS in dairy cows, there is a large gap in the understanding of some aspects of their pathogenesis, especially the role of mammary epithelial cells and lymphocytes. Regarding the role of mammary epithelial cells (MECs) and lymphocytes is still incomplete, this study will investigate the interdependence of peripheral blood mononuclear cells (PBMCs) and MECs in the regulation of cytokine and chemokine production in response to stimulation by different staphylococci species/strains. For the assays distinct S. aureus strains isolated from different clinical statuses (clinical and subclinical infection) and CNS isolated from different ecological niches will be used. Here, we will: 1) Establishment of an in vitro model to evaluate the crosstalk between MECs and PBMCs under challenge with distinct staphylococcal species; 2) Production of interleukin (IL)-8, IL-1² and tumor necrosis factor (TNF)-± by MECs under challenge with distinct staphylococcal species; 3) Evaluate the production of granulocyte-macrophage stimulating factor (GM-CSF), IL-17A, interferon (IFN)-³ and IL-10 by PBMCs in co-culture with MECs under challenge with distinct staphylococcal species; 4) Lymphocyte proliferation of B, T CD4+, T CD8+ and ³´ T cells in co-culture with MECs under challenge with distinct staphylococcal species. Furthermore, to the best of our knowledge, this is the first study that will evaluate the production of the cytokine IL-17C by MECs. (AU)