Lipopolysaccharide and interferon gamma activate nuclear factor kappa B and induce cyclo-oxygenase-2 in equine vascular smooth muscle cells

Equine endotoxaemia is an important cause of morbidity and mortality in horses caused by the interaction of bacterial lipopolysaccharide (LPS) with cells such as macrophages and vascular smooth muscle. In this study we isolated equine vascular smooth muscle from a variety of vessels and stimulated it with LPS and human interferon (hIFN)-γ. Using reverse transcriptase polymerase chain reaction (rt-PCR) and Western blot analysis we show that cyclooxygenase-2 (COX-2) is readily expressed in equine vascular smooth muscle. Vascular smooth muscle cells produced prostaglandin E2 in response to LPS and hIFNγ. Using similar approaches we saw very limited expression of inducible nitric oxide synthase (iNOS) in only one vascular smooth muscle preparation. LPS and IFNγ caused translocation of the transcription factor nuclear factor kappa B (NfκB) to the nucleus in equine cells suggesting the limited iNOS production seen in our cells is not due to deficits in this signal transduction pathway. These data suggest that in equine vascular smooth muscle COX-2 and NfκB are likely to play important roles in the pathogenesis of equine endotoxaemia.