The hormone melatonin has many properties, including antioxidant, anti‐inflammatory, and immunomodulatory effects. Melatonin has been demonstrated to be beneficial in several inflammatory autoimmune diseases, but its effects in rheumatoid arthritis (RA) remain controversial. We sought to determine how melatonin regulates inflammation in RA. We found that melatonin dose‐dependently inhibits tumor necrosis factor‐α (TNF‐α) and interleukin (IL)‐1β expression through the PI3K/AKT, ERK, and NF‐κB signaling pathways. We also identified that melatonin inhibits TNF‐α and IL‐1β production by upregulating miR‐3150a‐3p expression. Synovial tissue specimens from RA patients and culture of human rheumatoid fibroblast‐like synoviocytes confirmed that the MT1 receptor is needed for the anti‐inflammatory activities of melatonin. Importantly, melatonin also significantly reduced paw swelling, cartilage degradation, and bone erosion in the collagen‐induced arthritis mouse model. Our results indicate that melatonin ameliorates RA by inhibiting TNF‐α and IL‐1β production through downregulation of the PI3K/AKT, ERK, NF‐κB signaling pathways, as well as miR‐3150a‐3p overexpression. The role of melatonin as an adjuvant treatment in patients with RA deserves further clinical studies.

Angiogenesis, the growth of new blood vessels, is essential in the pathogenesis of joint inflammatory disorders such as rheumatoid arthritis (RA) and osteoarthritis (OA), facilitating the invasion of inflammatory cells and increase in local pain receptors that contribute to structural damage and pain. The angiogenic process is perpetuated by various mediators such as growth factors, primarily vascular endothelial growth factor (VEGF) and hypoxia-inducible factors (HIFs), as well as proinflammatory cytokines, various chemokines, matrix components, cell adhesion molecules, proteases, and others. Despite the development of potent, well-tolerated nonbiologic (conventional) and biologic disease-modifying agents that have greatly improved outcomes for patients with RA, many remain resistant to these therapies, are only partial responders, or cannot tolerate biologics. The only approved therapies for OA include symptom-modifying agents, such as analgesics, non-steroidal anti-inflammatory drugs (NSAIDs), steroids, and hyaluronic acid. None of the available treatments slow the disease progression, restore the original structure or enable a return to function of the damaged joint. Moreover, a number of safety concerns surround current therapies for RA and OA. New treatments are needed that not only target inflamed joints and control articular inflammation in RA and OA, but also selectively inhibit synovial angiogenesis, while preventing healthy tissue damage. This narrative review of the literature in PubMed focuses on the evidence illustrating the therapeutic benefits of modulating angiogenic activity in experimental RA and OA. This evidence points to new treatment targets in these diseases.

Resistin has a proinflammatory function in human that contributes to the link between inflammation and cardiovascular disease and is also associated with rheumatoid arthritis (RA).The aim of this study was to examine the potential function ofresistin in human circulating endothelial progenitor cells (EPCs) during angiogenesis in RA.EPCs isolated from healthy donors were used to investigate the mechanisms underlying EPCs migration and tube formation. In addition, potential microRNA‐206 (miR‐206) targets were validated using real‐time quantitative polymerase chain reaction, western blotting, and a luciferase reporter assay. Resistin is highly expressed in synovial fluids and tissues in RA patients and mice with collagen‐induced arthritis and promotes both EPC homing to synovia and angiogenesis. We show that resistin directly induces significant upregulation of vascular endothelial growth factor (VEGF) expression in EPCs and promotes expression of the VEGF 3ʹ untranslated region in the absence of a miR‐206 binding site. Our study is the first to demonstrate that a signaling pathway involving miR‐206 is involved in resistin‐induced VEGF expression and that EPCs migrate into RA joints in vitro and in vivo; these results provide support for resistin as a therapeutic target of RA.

Angiogenesis is the formation of new capillaries from preexisting vasculature.

Accumulating evidence indicates that subchondral bone might play an essential role in rheumatoid arthritis (RA). Osteopontin (OPN) induces the production of an important proinflammatory cytokine involved in the pathogenesis of RA. This study evaluated the activation of oncostatin M (OSM) by OPN in human primary osteoblasts to understand RA pathogenesis and characterized the intracellular signaling pathways involved in this activation. Quantitative PCR, ELISA, and Western blot results indicated that stimulation of human primary osteoblasts with OPN induces OSM expression through αvβ3 integrin/c-Src/platelet-derived growth factor receptor transactivation/MEK/ERK. Treatment of osteoblasts with OPN also increased c-Jun phosphorylation, AP-1 luciferase activity, and c-Jun binding to the AP-1 element on the OSM promoter, as demonstrated using chromatin immunoprecipitation assay. Moreover, inhibition of OPN expression using lentiviral-OPN short hairpin RNA resulted in the amelioration of articular swelling, cartilage erosion, and OSM expression in the ankle joint of mice with collagen-induced arthritis as shown using microcomputed tomography and immunohistochemistry staining. Our results imply that OSM expression in osteoblasts increases in response to OPN-induced inflammation in vitro. Finally, lentiviral-OPN short hairpin RNA ameliorates the inflammatory response and bone destruction in mice with collagen-induced arthritis. Therefore, OPN may be a potential therapeutic target for RA.

No abstract

Leptin, an adipocyte-derived cytokine that is closely associated with obesity, has recently been shown to be involved in carcinogenesis and cancer progression. Integrins are the major adhesive molecules in mammalian cells and have been associated with metastasis of cancer cells. In this study, we found that leptin increased the migration and the expression of alphavbeta3 integrin in human chondrosarcoma cells. We also found that human chondrosarcoma tissues and chondrosarcoma cell lines had significant expression of the long form (OBRl) leptin receptor, which was higher than that in normal cartilage and human primary chondrocyte. Leptin-mediated migration and integrin upregulation were attenuated by OBRl receptor antisense oligonucleotide. Activations of insulin receptor substrate (IRS)-1, phosphatidylinositol 3-kinase (PI3K), Akt and nuclear factor-kappaB (NF-kappaB) pathways after leptin treatment were demonstrated, and leptin-induced expression of integrin and migration activity was inhibited by the specific inhibitor, small-interfering RNA and mutant of IRS-1, PI3K, Akt and NF-kappaB cascades. Taken together, our results indicated that leptin enhances the migration of chondrosarcoma cells by increasing alphavbeta3 integrin expression through the OBR1/IRS-1/PI3K/Akt/NF-kappaB signal transduction pathway.

Hepatocellular carcinoma (HCC) is a liver malignancy and a major cause of cancer mortality worldwide. AURKA (aurora kinase A) is a mitotic serine/threonine kinase that functions as an oncogene and plays a critical role in hepatocarcinogenesis. We report on the association between 4 single nucleotide polymorphisms (SNPs) of the AURKA gene (rs1047972, rs2273535, rs2064836, and rs6024836) and HCC susceptibility as well as clinical outcomes in 312 patients with HCC and in 624 cancer-free controls. We found that carriers of the TT allele of the variant rs1047972 were at greater risk of HCC compared with wild-type (CC) carriers. Moreover, carriers of at least one A allele in rs2273535 were less likely to progress to stage III/IV disease, develop large tumors or be classified into Child-Pugh class B or C. Individuals with at least one G allele at AURKA SNP rs2064863 were at lower risk of developing large tumors or progressing to Child-Pugh grade B or C. Our results indicate that genetic variations in the AURKA gene may serve as an important predictor of early-stage HCC and be a reliable biomarker for the development of HCC.