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Title: ELEVATED MILK SOLUBLE CD14 IN COWS CHALLENGED BY ESCHERICHIA COLI LIPOPOLY SACCHARIDE

Author
item Paape, Max
item LEE, JAI-WEI - MCGILL UNIV, CANADA
item ZHAO, XIN - MCGILL UNIV, CANADA

Submitted to: Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 11/27/2001
Publication Date: 3/1/2002
Citation: PAAPE, M.J., LEE, J., ZHAO, X. ELEVATED MILK SOLUBLE CD14 IN COWS CHALLENGED BY ESCHERICHIA COLI LIPOPOLY SACCHARIDE. EXPERIMENTAL BIOLOGY. 2002.

Interpretive Summary:

Technical Abstract: The pathogenesis of Gram-negative bacterial infections has been shown to be sophisticatedly modulated by the interaction among lipopolysaccharide (LPS), LPS-binding protein (LBP) and CD14 (both membrane-bound and soluble forms). However, the role of soluble CD14 (sCD14) plays in bovine mastitis induced by E. coli has not been well defined. Seven healthy lactating cows were challenged by E. coli LPS (100 mg) in the left front quarters, and milk samples from all quarters were collected at various time points until 72 h after infusion. Rectal temperature and milk somatic cell count (SCC) increased dramatically, and peaked at 6 h and 24 h postinfusion, respectively. The concentration of sCD14 elevated quickly in the challenged quarters, peaked at 10 h, and started to decline after 24 h. Serum leakage, as characterized by the level of bovine serum albumin (BSA) in milk, reached its peak at 2 h and gradually dropped after 4 h postinfusion. Both sCD14 and BSA remained at their basal levels in the control quarters during this study. In vitro experiments indicated that neutrophils release sCD14 in response to LPS, in a dose-dependent manner, without the presence of LBP. We therefore conclude that the concentration of sCD14 is significantly increased in the milk after LPS challenge, and this is not likely due to serum leakage. In contrast, local and infiltrated neutrophils activated by LPS, might be the main source of the sCD14 in the milk during E. coli mastitis.