Reaction of Cathelicidin-2 Secreted from Goats Milk Leukocytes to Lipopolysaccharide

Abstract

Since mastitis causes a great economic loss for dairy farmers, its prevention and treatment are essential for milk production. Escherichia coli (E.coli) is one of the main bacteria causing mastitis, and its cell membrane component, lipopolysaccharide (LPS), induces mammary in ammation through the recognition by Toll-like receptors (TLR)-4. In human, there are some reports that Cathelicidin (Cath), one of the antimicrobial peptides, could prevent LPS-induced in ammation by neutralization of LPS. The objective of the present study was to examine whether the goat Cath-2 bound to and neutralized LPS. Leukocytes derived from goat milk were cultured for 0, 1, 3, 6, 12, 24 h. Then the concentration of Cath-2 in the medium was measured. The binding ability of synthetic Cath-2 (0~100 ng/ml) to LPS was analyzed. Mammary epithelial cells (MEC) isolated from milk were cultured with LPS and/or Cath-2. Then mRNA expression of cytokines (IL-1 β, IL-6, IL-8 and TNF-α) in the cells and concentration of lactoferrin (LF) in the medium were examined. The concentration of Cath-2 in the cultured medium increased signi cantly with the time of culture. It was con rmed that Cath-2 bound to LPS. The mRNA expression of IL-8 was increased signi cantly in MEC challenged with LPS. No signi cant effect of LPS on the expressions of other cytokines was found. The expressions of all cytokines were not changed by the addition of Cath-2 in MEC challenged with LPS. However, the expression of IL-1 β, IL-6 and TNF-α tended to increase in association with the increase of Cath-2 concentration in the absence of LPS. The addition of Cath-2 together with LPS did not cause signi cant change in LF concentration in the medium. These results suggest that goat Cath-2 was secreted from leukocytes in milk and it has an ability to bind to LPS.