Anti-asthmatic potential of a D-galactose-binding lectin from Synadenium carinatum latex

Extracts from the plant Synadenium carinatum latex are widely and indiscriminately used in popular medicine to treat a great number of inflammatory disorders and although the mechanisms underlying these effects remain undefined, the lectin isolated from S. carinatum latex (ScLL) is thought to be in part responsible for these anti-inflammatory effects. In order to elucidate possible immunoregulatory activities of ScLL, we investigated the effects of ScLL administration in models of acute and chronic inflammation. Oral administration of ScLL significantly inhibited neutrophil and eosinophil extravasation in models of acute and chronic inflammation and reduced eosinophil and mononuclear blood counts during chronic inflammation. ScLL administration reduced IL(interleukin)4 and IL-5 levels but increased interferon-gamma and IL-10 in an asthma inflammatory model, which suggested that it might induce a TH2 to TH1 shift in the adaptive immune response. ScLL also inhibited IkB alpha degradation, a negative regulator of proinflammatory NF-kB. Taken together, these results provide the first description of a single factor isolated from S. carinatum latex extract with immunoregulatory functions and suggest that ScLL may be useful in the treatment of allergic inflammatory disorders.