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Title: INCREASED MILK LEVELS OF TRANSFORMING GROWTH FACTOR-ALPHA, B-1 AND B-2 DURING ESCHERICHIA COLI-INDUCED MASTITIS

Author
item CHOCKALINGAM, ANNAPOORANI - PENN STATE UNIVERSIT
item Paape, Max
item Bannerman, Douglas

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2005
Publication Date: 5/20/2005
Citation: Chockalingam, A., Paape, M.J., Bannerman, D.D. 2005. Increased milk levels of transforming growth factor-alpha, b-1 and b-2 during escherichia coli-induced mastitis. Journal of Dairy Science. 88(6):1986-1993.

Interpretive Summary: Nearly 25% of the clinical cases of bovine mastitis caused by Gram-negative bacteria result in culling or death of the animal. Of the Gram-negative bacteria that cause bovine mastitis, Escherichia coli remain the most prevalent. The ability of E. coli to establish infection is due, in part, to the ability of the host to mount an immune/inflammatory response to the bacteria. The present report increases our understanding of mammary gland host immune defense mechanisms by characterizing changes in the expression of the inflammatory modulating growth factors/cytokines, TGF-a, TGF-B1, and TGF-B2. Increased knowledge of mammary gland innate immune responses has the potential to lead to the development of immuno-modulatory interventions that can be used in the treatment of mastitis.

Technical Abstract: Among the Gram-negative bacteria that cause mastitis, Escherichia coli are the most prevalent. The innate immune system provides initial protection against E. coli infection by detecting the presence of the foreign pathogen and by mounting a pro-inflammatory response, the latter of which is mediated by cytokines such as interleukin (IL)-1B, IL-8, and tumor necrosis factor (TNF)-a. Although changes in these cytokines during mastitis have been well-described, it is believed that other mediators moderate mammary gland inflammatory responses as well. The growth factors/cytokines transforming growth factor (TGF)-a, TGF-B1, and TGF-B2 are all expressed in the mammary gland and have been implicated in regulating mammary gland development. Outside of the mammary gland, these growth factors/cytokines have been shown to moderate inflammation. The objective of the current study was to determine whether TGF-a, TGF-B1, and TGF-B2 milk concentrations were altered during the course of E. coli-induced mastitis. The contralateral quarters of eleven mid-lactating Holstein cows were challenged with either saline or 72 CFU of E. coli, and milk samples collected. Basal milk levels of TGF-a', TGF-B1, and TGF-B2 were 98.81 + 22.69 pg/ml, 3.35 + 0.49 ng/ml, and 22.36 + 3.78 ng/ml, respectively. Analysis of whey samples derived from E. coli-infected quarters revealed an increase in milk levels of TGF-' within 16 h of challenge and these increases persisted for an additional 56 h. Elevated TGF-B1 and TGF-B2 milk concentrations were detected in E. coli-infected quarters 32 h after challenge and these elevations were sustained throughout the study. Since TGF-a, TGF-B1, and TGF-B2 have been implicated in mediating inflammatory processes, their induction during mastitis is consistent with a role for these molecules in mediating mammary gland host innate immune responses to infection.