Anti-inflammatory Effects of Fungal Metabolites in Mouse Intestine as Revealed by In vitro Models.

Inflammatory bowel diseases (IBD), which include Crohn's disease and ulcerative colitis, are chronic inflammatory disorders that can affect the whole gastrointestinal tract or the colonic mucosal layer. Current therapies aiming to suppress the exaggerated immune response in IBD largely rely on compounds with non-satisfying effects or side-effects. Therefore, new therapeutical options are needed. In the present study, we investigated the anti-inflammatory effects of the fungal metabolites, galiellalactone, and dehydrocurvularin in both an in vitro intestinal inflammation model, as well as in isolated myenteric plexus and enterocyte cells. Administration of a pro-inflammatory cytokine mix through the mesenteric artery of intestinal segments caused an up-regulation of inflammatory marker genes. Treatment of the murine intestinal segments with galiellalactone or dehydrocurvularin by application through the mesenteric artery significantly prevented the expression of pro-inflammatory marker genes on the mRNA and the protein level. Comparable to the results in the perfused intestine model, treatment of primary enteric nervous system (ENS) cells from the murine intestine with the fungal compounds reduced expression of cytokines such as IL-6, TNF-α, IL-1ß, and inflammatory enzymes such as COX-2 and iNOS on mRNA and protein levels. Similar anti-inflammatory effects of the fungal metabolites were observed in the human colorectal adenocarcinoma cell line DLD-1 after stimulation with IFN-γ (10 ng/ml), TNF-α (10 ng/ml), and IL-1ß (5 ng/ml). Our results show that the mesenterially perfused intestine model provides a reliable tool for the screening of new therapeutics with limited amounts of test compounds. Furthermore, we could characterize the anti-inflammatory effects of two novel active compounds, galiellalactone, and dehydrocurvularin which are interesting candidates for studies with chronic animal models of IBD.

Anti-inflammatory drimane sesquiterpene lactones from an Aspergillus species.

IFN-γ inducible protein 10 (IP-10, CXCL10) is a 10 kDa chemokine, which is secreted from various cell types after exposure to pro-inflammatory stimuli. This chemokine is a ligand for the CXCR3 receptor and regulates immune responses by activating and recruiting leukocytes such as T cells, eosinophils, monocytes, and NK cells to sites of inflammation. Altered expression of CXCL10 has been associated with chronic inflammatory and infectious diseases and therefore CXCL10 represents a promising target for the development of new anti-inflammatory drugs. In a search for inhibitors of CXCL10 promoter activity, three structurally related drimane sesquiterpene lactones (compounds 1-3) were isolated from fermentations of an Aspergillus species. Compounds 1 and 2 inhibited the IFN-γ/TNF-α/IL-1ß induced CXCL10 promoter activity in transiently transfected human DLD-1 colon carcinoma cells in a dose-dependent manner with IC50 values of 12.4 µM for 1 and 55 µM for 2, whereas 3 was devoid of any biological activity. Moreover, compounds 1 and 2 reduced CXCL10 mRNA levels and synthesis in IFN-γ/TNF-α/IL-1ß stimulated DLD-1 cells.

SF002-96-1, a new drimane sesquiterpene lactone from an Aspergillus species, inhibits survivin expression.

Survivin, a member of the IAP (inhibitor of apoptosis) gene family, is overexpressed in virtually all human cancers and is functionally involved in the inhibition of apoptosis, regulation of cell proliferation, metastasis and resistance to therapy. Because of its upregulation in malignancy, survivin has currently attracting considerable interest as a new target for anticancer therapy. In a screening of approximately 200 strains of imperfect fungi for the production of inhibitors of survivin promoter activity, a new drimane sesquiterpene lactone, SF002-96-1, was isolated from fermentations of an Aspergillus species. The compound inhibited survivin promoter activity in transiently transfected Colo 320 cells in a dose dependent manner with IC50 values of 3.42 µM (1.3 µg/mL). Moreover, it also reduced mRNA levels and protein synthesis of survivin and triggered apoptosis.