Osteoarthritis (OA) is a prevalent joint disease commonly associated with aging and obesity, which can lead to pain, stiffness, joint dysfunction, and disability. Omentin-1 (also called intelectin-1) is a newly discovered adipokine, which plays a protective role in suppressing the secretion of pro-inflammatory cytokines. Based on data from the Gene Expression Omnibus (GEO) dataset and clinical samples obtained at our institution revealed, determined that omentin-1 and IL-4 (an anti-inflammatory cytokine) levels were significantly lower in OA patients than in normal controls. Omentin-1 was shown to induce IL-4-depedent anti-inflammatory responses and M2 macrophage polarization in OA synovial fibroblasts via the PI3K, ERK, and AMPK pathways. Administering omentin-1 was shown to block cartilage degradation and bone erosion resulting from anterior cruciate ligament transection by inhibiting the production of pro-inflammatory cytokines and promoting M2 macrophage polarization in vivo. Our findings indicate omentin-1 as a promising therapeutic avenue for the treatment for OA.

Extracts from Taiwan’s traditional medicinal mushroom, Antrodia cinnamomea, exhibit anti-inflammatory activities in cellular and preclinical studies. However, this paper is the first to report that Antcin K, a triterpenoid isolated from A. cinnamomea, inhibits proinflammatory cytokine production in human rheumatoid synovial fibroblasts (RASFs), which are major players in rheumatoid arthritis (RA) disease. In our analysis of the mechanism of action, Antcin K inhibited the expression of three cytokines (tumor necrosis factor alpha [TNF-α], interleukin 1 beta [IL-1β] and IL-8) in human RASFs; cytokines that are crucial to RA synovial inflammation. Notably, incubation of RASFs with Antcin K reduced the phosphorylation of the focal adhesion kinase (FAK), phosphoinositide 3-kinase (PI3K), protein kinase B (AKT) and nuclear factor-κB (NF-κB) signaling cascades, all of which promote cytokine production in RA. Intraperitoneal injections of Antcin K (10 mg/kg or 30 mg/kg) attenuated paw swelling, cartilage degradation and bone erosion, and decreased serum levels of TNF-α, IL-1β, IL-8 in collagen-induced arthritis (CIA) mice; in further experiments, IL-6 levels were similarly reduced. The inhibitory effects of Antcin K upon TNF-α, IL-1β and IL-8 expression in human RASFs was achieved through the downregulation of the FAK, PI3K, AKT and NF-κB signaling cascades. Our data support clinical investigations using Antcin K in RA disease.

Background: Antcin K, an extract of Antrodia cinnamomea (a medicinal mushroom endemic to Taiwan commonly used in Chinese medicine preparations), inhibits proinflammatory cytokine production and angiogenesis in human rheumatoid arthritis synovial fibroblasts (RASFs), major players in RA disease. Antcin K also inhibits disease activity in mice with collagen-induced arthritis (CIA). Up until now, the effects of Antcin K upon cell adhesion molecules (CAMs) were unknown. Methods: RA and healthy synovial tissue samples (n = 10 in each group) were retrieved from the Gene Expression Omnibus (GEO) database (accession code: GDS5401) to compare CAM and monocyte marker expressions. In addition, synovial tissue samples from six RA patients and six patients undergoing arthroscopy for trauma/joint derangement (healthy controls) were subjected to immunohistochemical (IHC) analysis. mRNA and protein expression levels were analyzed in RASFs using RT-qPCR (Reverse transcription-quantitative polymerase chain reaction) and Western blot. RASFs were incubated with Antcin K and examined for monocyte adherence by fluorescence microscopy. Ankle joint tissue specimens from a CIA mouse model and healthy controls were stained with hematoxylin and eosin (H&E) and Safranin-O/Fast Green to examine histological changes and evidence of bone loss. IHC analysis determined levels of vascular cell adhesion molecule 1 (VCAM-1) and CD11b in CIA ankle tissue and clinical synovial tissue. Results: Levels of VCAM-1 expression were higher in the GEO database specimens and the study’s clinical samples of RA synovial tissue compared with the healthy specimens. Antcin K dose-dependently inhibited VCAM-1 expression and monocyte adhesion in RASFs. Antcin K also significantly inhibited levels of VCAM-1 and monocyte CD11b expression in CIA tissue. These effects appeared to be mediated by MEK1/2-ERK, p38, and AP-1 signaling. Conclusions: Antcin K seems promising for the treatment of RA and deserves further investigations.