Meloxicam affects the inflammatory responses of bovine mammary epithelial cells

摘要

Nonsteroidal anti-inflammatory drugs are used assupportive therapy with antimicrobial treatments formastitis in cows to alleviate pain of the inflamed mammarygland. They act mainly by inhibition of cyclooxygenases.Meloxicam (MEL) is a drug designed forcyclooxygenase-2 selectivity, which is upregulated uponinflammation, acting as a key enzyme for the conversionof arachidonic acid to prostaglandins. Althoughsome studies in dairy cows showed positive results inrecovery from mastitis when MEL was added to thetreatments, direct effects of MEL on the immune systemof mastitic cows are unknown. The aim of thisstudy was to investigate effects of MEL on the immuneresponse of bovine mammary epithelial cells (MEC)with or without simultaneous immune stimulation bypathogen-associated molecular patterns of commonmastitis pathogens. Mammary epithelial cells from 4cows were isolated and cultured. To evaluate dose effectsof MEL, MEC were challenged with or without0.2 μg/mL lipopolysaccharide (LPS; serotype O26:B6from Escherichia coli) with addition of increasingconcentrations of MEL (0, 0.25, 0.5, 1.0, 1.5, or 2.0mg/mL). The addition of MEL prevented the increaseof mRNA expression of key inflammatory factors inLPS-challenged MEC in a dose-dependent manner. Toinvestigate the effects of MEL on pathogen-specificimmune responses of MEC, treatments included challengeswith LPS from E. coli and lipoteichoic acid fromStaphylococcus aureus with or without 1.5 mg/mL MELfor 3, 6, and 24 h. Meloxicam prevented the increase ofmRNA abundance of key inflammatory mediators inresponse to LPS and lipoteichoic acid, such as tumornecrosis factor, serum amyloid A, inducible nitric oxidesynthase, and the chemokines IL-8 and CXC chemokineligands 3 and 5. The prostaglandin E2 synthesis in challengedand nonchallenged cells was reduced by MELwithin 24 h. Furthermore, MEL reduced the viabilityand consequently the total RNA yield of the cells. However,mRNA abundance of apoptosis-related enzymeswas not affected by any treatment. Meloxicam hadclear dose-dependent effects on the immune responseof MEC to pathogen-associated molecular patterns ofcommon mastitis pathogens by preventing increasedexpression of important factors involved in inflammation.This nonsteroidal anti-inflammatory drug also hasdetrimental effects on cell viability. How these effectswould influence the elimination of pathogens from aninfected mammary gland during mastitis therapy withmeloxicam needs to be further investigated.