E Cifrian1, A Guidry, W W Marquardt. 1. Department of Animal Sciences, University of Maryland, College Park, MD 20705, USA.
Abstract
OBJECTIVE: To determine the effect of milk and blood serum constituents on cytotoxicity of Staphylococcus aureus on mammary epithelial cells. DESIGN: In vitro incubation of cells with cytotoxic agents and milk and serum constituents. SAMPLE POPULATION: Mammary cells, milk, and blood obtained from 3 cows. PROCEDURE: Staphylococcal alpha-toxin and culture supernatants from S aureus M60 and an alpha-toxin-negative mutant of M60 were incubated with bovine mammary epithelial cells in the presence of milk fractions, serum, and divalent cations. Propidium iodide fluorescence was used as a measure of cell damage. RESULTS: Skim milk and milk whey inhibited S aureus cytotoxic agents. Skim milk protected against alpha-toxin damage to a greater extent than milk whey. Serum from an adult animal was more protective than was fetal serum. Milk fat and serum albumin had no protective effect. Divalent calcium and Mg2+ were more effective inhibitors of mammary epithelial cell damage caused by alpha-toxin than of damage attributable to M60 culture supernatant. Divalent calcium and Mg2+ at concentrations similar to those of free Ca2+ and Mg2+ in normal bovine milk decreased cytotoxic damage attributable to alpha-toxin. However, concentrations similar to those of total Ca2+ and Mg2+ in normal milk were required to decrease cell damage caused by M60 culture supernatant. The alpha-toxin-negative mutant was less cytotoxic than the M60 parent strain. CONCLUSIONS: Casein, as well as Ca2+ and Mg2+ in bovine milk, inhibit the cytotoxic effect of S aureus on mammary epithelial cells.
OBJECTIVE: To determine the effect of milk and blood serum constituents on cytotoxicity of Staphylococcus aureus on mammary epithelial cells. DESIGN: In vitro incubation of cells with cytotoxic agents and milk and serum constituents. SAMPLE POPULATION: Mammary cells, milk, and blood obtained from 3 cows. PROCEDURE: Staphylococcal alpha-toxin and culture supernatants from S aureus M60 and an alpha-toxin-negative mutant of M60 were incubated with bovine mammary epithelial cells in the presence of milk fractions, serum, and divalent cations. Propidium iodide fluorescence was used as a measure of cell damage. RESULTS: Skim milk and milk whey inhibited S aureus cytotoxic agents. Skim milk protected against alpha-toxin damage to a greater extent than milk whey. Serum from an adult animal was more protective than was fetal serum. Milk fat and serum albumin had no protective effect. Divalent calcium and Mg2+ were more effective inhibitors of mammary epithelial cell damage caused by alpha-toxin than of damage attributable to M60 culture supernatant. Divalent calcium and Mg2+ at concentrations similar to those of free Ca2+ and Mg2+ in normal bovine milk decreased cytotoxic damage attributable to alpha-toxin. However, concentrations similar to those of total Ca2+ and Mg2+ in normal milk were required to decrease cell damage caused by M60 culture supernatant. The alpha-toxin-negative mutant was less cytotoxic than the M60 parent strain. CONCLUSIONS: Casein, as well as Ca2+ and Mg2+ in bovine milk, inhibit the cytotoxic effect of S aureus on mammary epithelial cells.
Authors: Scott J Roberts; Helen C Owen; Wai Long Tam; Lien Solie; Sophie J Van Cromphaut; Greet Van den Berghe; Frank P Luyten Journal: Stem Cells Transl Med Date: 2013-12-27 Impact factor: 6.940