OBJECTIVE: In the present study, the standardized extract of P. amarus was investigated for its suppressive effects on type II collagen-induced rheumatoid arthritis (TCIA) in Sprague Dawley rats.

METHOD: The major components of the extracts, lignans and phenolic compounds were analysed by using a validated reversed phase HPLC and LC-MS/MS. A rheumatoid arthritis rat model was induced by administering a bovine type II collagen emulsion subcutaneously at the base of tail, on day 0 and 7 of the experiment. Effects of the extract on severity assessment, changes in the hind paw volume, bone mineral density, body weight and body temperature were measured. Concentrations of cytokines (TNF-α, IL-1β, IL-1α, IL-6) released, matrix metalloproteinases (MMP-1, MMP-3 MMP-9) and their inhibitor (TIMP-1), haematological and biochemical changes were also measured. ELISA was used to measure the cytokines and proteinases in the rat serum and synovial fluid according to manufacturer's instructions.

RESULTS: The extract dose-dependently modulated the progression in physical parameters (i.e. decrease in body weight, increase in body temperature, reduced hind paw volume, reduced the severity of arthritis), bone mineral density, haematological and biochemical perturbations, serum cytokines production and levels of matrix metalloproteinases and their inhibitor in the synovial fluid. Histopathological examination of the knee joint also revealed that the extract effectively reduced synovitis, pannus formation, bone resorption and cartilage destruction.

MATERIALS AND METHODS: The influx of immune cells, release of pro-inflammatory cytokines and subsequent accumulation of synovial fluid (swelling) and pain manifest into the disease. The present study used CFA induced Balb/c mice model and treated them intraperitoneally with andrographolide and dexamethasone (used as a positive control) on alternate days for six days. After 6 days, blood and peritoneal macrophages were collected to evaluate the expression of various arthritic markers and paw edema was measured on all days.

RESULTS: The in vitro and ex vivo experiments showed that andrographolide treated animal group had reduced paw edema, cell cytotoxicity and nitric oxide production than dexamethasone treated animal group. Further, the study revealed the mechanistic role of andrographolide in treatment of arthritis by suppressing battery of molecules like COX-2, NF-κB, p-p38, CD40, TNF-α, IL-1β and IL-6 involved in arthritis.