Submitted to: Journal of Dairy Science
Publication Type: Review Article
Publication Acceptance Date: 12/20/2006
Publication Date: 6/1/2007
Citation: Burvenich, C., Bannerman, D.D., Lippolis, J.D., Peelman, L., Nonnecke, B.J., Kehrli, Jr., M.E., Paape, M.J. 2007. Cumulative physiological events influence the inflammatory response of the bovine udder to Escherichia coli infections during the transition period. Journal of Dairy Science. 90(E.Suppl.):E39-E54. Interpretive Summary:
Technical Abstract: A high proportion of intramammary coliform infections present at parturition may develop disease characterized by severe inflammatory signs and sepsis during the first 60-70 days of lactation. In the lactating bovine mammary gland innate immunity is the most important defense system. Since the beginning of the 1990's, research on bovine mammary innate defense mechanisms in connection with the pathogenesis of coliform mastitis has increased significantly. There is no doubt that the viable neutrophil in the cisterns and ducts is a key factor in the protection of the mammary gland an that its function is influenced by many physiological events occurring during the transition period. Opportunistic infections occur when the integrity of the host immune system is compromised by physical and physiological conditions that make the host more susceptible. This immunocompromised condition refers to a defense system that functions in an abnormal or incomplete manner. The innate immune system of many periparturient cows is immunocompromised. It is unlikely that periparturient immunosuppression is the result of a single physiological factor; more likely, several entities act in concert with profound effects on the function of many organ systems of the periparturient dairy cow. These cows are at risk for infections with opportunistic bacteria from the environment. Their defense system is unable to modulate the complex network of innate immune responses leading to incomplete resolution of the pathogen and the inflammatory reaction. During the last 30 years most efforts have been focused on diapedesis, phagocytosis and killing by neutrophils, one of the most important components of the efferent arm of the innate immune system. How these functions modulate the clinical outcome of coliform mastitis and how they can be influenced by hormones and metabolism, the focus of this review, has also been the subject of intensive research. The study of the afferent (sensing) arm of innate immunity that recognizes a diverse array of pathogens is a new area of interest and may also contribute to the variation in inflammatory responses. The development of novel interventions that modulate the inflammatory response elicited by LPS and/or contribute to the elimination of the pathogen, remains an important animal health priority.