A mechanistic view of the effects of manzamine A (MZA) on rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) (167.8)

Abstract

Abstract Previous studies suggested that MZA, an alkaloid extracted from a marine sponge, has anti-inflammatory properties which may act via mitogen-activated protein (MAP) kinases. We hypothesized that MZA would decrease phosphorylation of MAP kinases in RA FLS and reduce secretion of proinflammatory cytokines from RA synovial tissue (ST) explants. RA FLS were treated with 10 μM MZA or DMSO (vehicle) for 1 hour prior to stimulation with various dilutions of RA synovial fluid (SF) for 5 minutes and Western blotting was performed on cell lysates. Western blotting with phospho-specific antibodies demonstrated that RA SF increases the phosphorylation of the MAP kinases ERK 1/2 and JNK in RA FLS at dilutions of 1:10 and 1:25. However, pretreatment with MZA did not consistently alter RA SF-stimulated RA FLS phosphorylation of ERK 1/2 or JNK. RA ST explants were incubated with either DMSO or MZA (10, 1.0 or 0.1 µM) and conditioned media (CM) was collected after 24 hours for analysis by ELISA. CM collected 24 hrs after treatment of RA ST explants with MZA or vehicle revealed no significant differences in secretion of RANTES (CCL5) or interleukin (IL)-10. We conclude that RA SF dilutions can be used as a biologically relevant stimulant of RA FLS MAP kinase phosphorylation. We have also shown that MZA has no consistent effect on the phosphorylation of the MAP kinases ERK 1/2 or JNK. We also note that MZA may not alter secretion of IL-10 or RANTES using a RA ST explant model.