The role of the cytokines in udder immunity evaluation in dairy cows

Mastitis are generally recognized as one of the most costly diseases for the dairy industry. The routine diagnostic tools (somatic cells count, bacteriological examination etc) are useful to identify diseased subjects and the causative agent but they give no information about the stage of the infection and the type of immune response. For this reason, the traditional laboratory methods for the diagnosis of mastitis are inadequate from an immunological point of view. In the last two decades, the interest of many researchers focused on the role of immunological mediators, such as the cytokines, in the mechanisms of defence against mastitis. Cytokines are small proteins involved in a variety of physiological/pathological processes and, in particular, these molecules are critical in the induction, modulation, and resolution of the inflammatory response. There are three main directories of research on the role of the cytokines in the evaluation of udder immunity in dairy cows: 1) cytokines as bio-markers to evaluate the immunological status of the animal or of the mammary gland; 2) cytokines in new strategies for immunotherapy; 3) cytokines as “natural adjutants” in developing efficacious vaccines against mastitis. The understanding of the changes in the cytokine profile in healthy and mastitic mammary gland could helpful to detect a pre-inflammatory status or a sub-clinical infection, to evaluate the immunological status of the udder, and to monitor the efficacy of a pharmacological treatment. Furthermore, the comprehension of the role of cytokines in connecting the immune system and the inflammatory cascade is crucial to set up new therapeutic strategies aimed: to inhibit the synthesis and the release of cell mediators; to stimulate the production of anti-inflammatory cytokines; to remove the circulating inflammatory molecules; to block their binding to the cellular receptors or, finally, to inhibit the transduction signals. Moreover cytokines are promising targets for the manipulation of the udder’s immune system in order to reduce the susceptibility of the organ to clinical mastitis. In fact, the cytokine pattern evoked in the mammary gland influence the differentiation of T helper cells toward the Th1-type, which is involved in cell-mediated inflammatory reaction, or the Th2-type which mediate the humoral immune response. The Th-1 response is considered a key mechanism to enhance mammary gland defences against invading bacteria, thus the possibility to polarize the Th-type response using recombinant cytokines has received considerable research attention.