Protective Effects of Prunasin A against the Differentiation of Osteoclasts and Destruction of Cartilage via the Receptor Activator of Nuclear Factor-Kappa-Β Ligand/Mitogen-Activated Protein Kinase/Osteoprotegerin Pathway in a Rat Model of Arthritis

Abstract

The present study evaluated the protective effects of pseurotin A against inflammation and the destruction of cartilage in a rat model of rheumatoid arthritis (RA). RA was induced by intradermal injections of Freund’s complete adjuvant (1 mg/mL), and the treatment with pseurotin A (50 and 100 mg/kg, p.o.) was administered over 1 week. The effects of pseurotin A were assessed by estimating hind paw volume (HPV) and determining the levels of inflammatory mediators in the serum and synovial fluid of collagen-induced arthritis (CIA)-induced RA rats. Western blot and histopathological assays were performed to assess changes in synovial tissues. Additionally, in vitro analyses of receptor activator of nuclear factor-kappa-Β ligand (RANKL)-stimulated RAW264.7 cells treated with pseurotin A at different concentrations (1, 10, and 100 µg/mL) were conducted to assess the effects of pseurotin A on apoptosis ratio, real-time polymerase chain reaction data, and tartrate-resistant acid phosphatase staining. Compared to the RA group, treatment with pseurotin A significantly decreased HPV and reduced the levels of inflammatory mediators in the synovial fluid and blood. Additionally, pseurotin A ameliorated the protein expressions of osteoprotegerin, nuclear factor of activated T-cells, nuclear factor-kappa beta (NF-κB), IκBα, extracellular signal regulated kinase, and P38 as well as histopathological changes in the synovial tissue of CIA-induced RA rats. The in vitro findings revealed that pseurotin A treatment did not alter the apoptosis ratio in RANKL-stimulated RAW264.7 cells but significantly reduced the mRNA expressions of calcitonin receptor, NF-κB, and matrix metallopeptidase-9. The present findings suggest that pseurotin A ameliorated the differentiation of osteoclasts and the destruction of cartilage in RA rats via regulation of the mitogen-activated protein kinase/RANKL/NF-kB pathway.

Pseurotin D Inhibits the Activation of Human Lymphocytes

“…Previously, pseurotin D inhibited the endotoxin-mediated activation of RAW 264.7 murine macrophages in vitro, as was documented by the inhibition of IL-6 and nitric oxide release [14]. Furthermore, inhibition of the production of pro-inflammatory mediators including TNF-α and IL-6 by pseurotin A was observed in the synovial fluid of rats with rheumatoid arthritis [33]. The inhibition of the activation of both CD4+ and CD8+ T cells by pseurotin D was accompanied by a dose-dependent decline in T-cell proliferation.…”

“…Further, a reduction of delayed-type hypersensitivity response by pseurotin D was observed using a murine in vivo model [15]. The therapeutic potential of pseurotin A was discussed in osteoclast-related bone diseases such as osteoporosis [36] and rheumatoid arthritis [33] during which loss of T cell tolerance occurs. Pseurotin A was also reported to suppress the progression of hormone-dependent BT-474 breast tumors in a nude mouse xenograft model [38].…”

“…Meanwhile, Asami et al observed that the natural pseurotin analog azaspirene inhibited angiogenesis [12], which was accompanied by decreased activation of the Raf-1 pathway [10]. Further, the inhibition of extracellular signal-regulated kinases (ERK) and p38 kinase and the activation of nuclear factor kappa B (NF-κB) transcription factor by pseurotin A was observed in cells from synovial tissue of rats with rheumatoid arthritis [33]. In bone marrow macrophages activated by the receptor activator of NF-κB ligand, pseurotin A reduced the phosphorylation of MAPK family members-namely, ERK, p-38, and c-Jun N-terminal kinases, as well as the activation of the NF-κB pathway [36].…”