Lipid-Rich Extract from Mexican Avocado Seed (Persea americanavar. drymifolia) ReducesStaphylococcus aureusInternalization and Regulates Innate Immune Response in Bovine Mammary Epithelial Cells

Abstract

Bovine mammary epithelial cells (bMECs) are capable of initiating an innate immune response (IIR) to invading bacteria.Staphylococcus aureusis not classically an intracellular pathogen, although it has been shown to be internalized into bMECs.S. aureusinternalizes into nonprofessional phagocytes, which allows the evasion of the IIR and turns antimicrobial therapy unsuccessful. An alternative treatment to control this pathogen is the modulation of the innate immune response of the host. The Mexican avocado (Persea americanavar. drymifolia) is a source of molecules with anti-inflammatory and immunomodulatory properties. Hence, we analyze the effect of a lipid-rich extract from avocado seed (LEAS) onS. aureusinternalization into bMECs and their innate immunity response. The effects of LEAS (1-500 ng/ml) on theS. aureusgrowth and bMEC viability were assessed by turbidimetry and MTT assays, respectively. LEAS did not show neither antimicrobial nor cytotoxic effects.S. aureusinternalization into bMECs was analyzed by gentamicin protection assays. Interestingly, LEAS (1-200 ng/ml) decreased bacterial internalization (60-80%) into bMECs. This effect correlated with NO production and the induction of the gene expression of IL-10, while the expression of the proinflammatory cytokine TNF-αwas reduced. These effects could be related to the inhibition of MAPK p38 (∼60%) activation by LEAS. In conclusion, our results showed that LEAS inhibits theS. aureusinternalization into bMECs and modulates the IIR, which indicates that avocado is a source of metabolites for control of mastitis pathogens.