Impacto da expressão de PD-1 e CTLA-4 em linfócitos na susceptibilidade e ocorrência de mastite durante o período pós parto em vacas primíparas

Abstract

The peripartum is a critical period in all species, especially for the bovine species. It is during this period that the animals go through several anatomical, physiological and behavioral changes. The various changes directly affect the immune system of these animals, often leading to a state of immunosuppression. Thus, the objective of this study was to evaluate the influence of negative inhibitory receptors, PD-1 and CTLA-4, in the susceptibility and occurrence of postpartum mastitis in heifers, as well as to open paths to new therapeutic forms. For this, 30 heifers were selected for the study. All of them had no recent history of diseases and confirmed pregnancy. The evaluations began fifteen days before delivery (M1). With the arrival of the calving, the animals were evaluated at this time (M2), seven (M3), fifteen (M4) and thirty days after calving (M5). The immunological evaluation was performed only at M1, routine evaluations and blood tests occurred at all times, while the evaluation of milk secretion occurred from the time of calving. For immune evaluation, peripheral blood mononuclear cells (PBMC) were separated, and lymphocytes were preserved in order to perform immunophenotyping. During collection, the animals underwent a complete clinical examination, in addition to complementary tests such as blood count, determination of beta-hydroxybutyrate (BHB), non-esterified fatty acids (NFA), glucose, calcium, phosphorus, cholesterol, triglycerides, gamma glutamyl transferase (GGT), alanine amino transferase (ALT), aspartate amino transferase (AST), urea, total protein, and creatinine. Milk was evaluated by dark-bottom mug test, California Mastitis Test (CMT), differential microscopic somatic cell count (DMSC), and bacteriological examination, with subsequent bacterial identification by matrix-assisted laser Ionization and desorption (MALDI-ToF-MS). The results obtained were distributed in three articles, which are arranged as follows.