Immunomodulating extracts from Icelandic marine invertebrates

Abstract

Iceland has a 200 nautical miles exclusive economic zone that is largely unexplored with respect to chemical constituents of the marine biota. In particular, the confluence of cold and warm water masses and geothermal activity creates a unique marine environment that has never been evaluated for the potential of marine natural product diversity. The aim of this study was to prepare extracts from Icelandic marine invertebrates and screen for their immunomodulating activity in an in vitro dendritic cell (DC) model, followed by bioassay-guided isolation. The effects of the extracts and fractions were assessed by their ability to alter the maturation of monocyte-derived human DCs, assessed by measuring their cytokine secretion and expression of surface molecules. Extracts of ninety marine invertebrates, collected in Icelandic waters have been tested and ten extracts have been discovered that affect the maturation of the DCs without being cytotoxic. Two active extracts, from the marine sponges Clathria barleei and Isodictya palmata, were selected for further fractionation. These extracts had similar effects; reduction in IL-12 and IL-10 secretion of DCs and down-regulation of CD86 and HLA-DR surface expression. We conclude that the active fractions from these marine sponges have inhibitory effects on the maturation of dendritic cells, and isolated compound(s) could prove to be useful in the treatment of autoimmune diseases.