melitten and Crohn-Disease

Prostaglandins (PG), which are responsible for a large array of biological functions in eukaryotic cells, are produced from arachidonic acid by phospholipases and cyclooxygenase enzymes COX-1 and COX-2. We demonstrated that PG levels in cells were partly controlled by a regulatory protein, phospholipase A2 (PLA2)-activating protein (PLAA). Treatment of murine macrophages with lipopolysaccharide, interleukin-1beta, and tumor necrosis factor-alpha increased PLAA levels at early time points (2-30 min), which correlated with an up-regulation in cytosolic PLA2 and PGE2 levels. Both COX-2 and secretory PLA2 were also increased in lipopolysaccharide-stimulated macrophages, however, at later time points of 4-24 h. The role of PLAA in eicosanoid formation in macrophages was confirmed by the use of an antisense plaa oligonucleotide. Within amino acid residues 503-538, PLAA exhibited homology with melittin, and increased PGE(2) production was noted in macrophages stimulated with melittin. In addition to PLA2, we demonstrated that activation of phospholipase C and D significantly controlled PGE2 production. Finally, increased antigen levels of PLAA, COX-2, and phospholipases were demonstrated in biopsy specimens from patients with varying amounts of intestinal mucosal inflammation, which corresponded to increased levels of phospholipase activity. These results could provide a basis for the development of new therapeutic tools to control inflammation.

Topics: Amino Acid Sequence; Animals; Arachidonic Acid; Cell Line; Colitis; Colonic Diseases, Functional; Crohn Disease; Cyclooxygenase 2; Dinoprostone; Humans; Inflammation Mediators; Interleukin-1; Isoenzymes; Lipopolysaccharides; Macrophage Activation; Macrophages; Melitten; Membrane Proteins; Mice; Molecular Sequence Data; NF-kappa B; Phospholipase D; Prostaglandin-Endoperoxide Synthases; Protease Inhibitors; Protein Transport; Proteins; Tumor Necrosis Factor-alpha; Type C Phospholipases