IL-1beta mediates MMP secretion and IL-1beta neosynthesis via upregulation of p22phox and NOX4 activity in human articular chondrocytes

Objectives: Osteoarthritis (OA) is characterized by a progressive alteration of the biochemical properties of the articular cartilage. Inflammation plays a major role in OA, particularly through the cytokine Interleukine-1β, promoting reactive oxygen species (ROS) generation and matrix metalloproteinases (MMP) synthesis by the chondrocytes, orchestrating matrix proteolysis. NADPH oxidases (NOX) are membrane enzymes dedicated to the production of ROS. Role of oxidative stress is well established in OA; however, contribution of NOX in this process is still poorly documented. In this study, we addressed the role of NOX in primary human articular chondrocytes (HAC) upon inflammatory conditions - namely IL-1β and OA. Design: HAC were collected from patients undergoing hip surgery. Chondrocytes were treated with IL-1β and NOX inhibitors Diphenylene Iodonium, GKT136901, Tiron and Heme oxygenase-1 before MMP expression and NOX activity assessment. Finally, NOX4 expression was compared between OA and non OA parts of hip cartilage (n = 14). Results: This study establishes for the first time in human that NOX4 is the main NOX isoform expressed in chondrocytes. We found a significant upregulation of NOX4 mRNA in OA chondrocytes. Expression of NOX4/p22phox as well as ROS production is enhanced by IL-1β. On the other hand, the use of NOX4 inhibitors decreased IL-1β-induced collagenase synthesis by chondrocytes. Moreover, our study support the existence of a redox dependant loop sustaining pro-catabolic pathways induced by IL-1β. Conclusions: This study points out NOX4 as a new putative target in OA and suggests that NOX-targeted therapies could be of interest for the causal treatment of the pathology. © 2015 Osteoarthritis Research Society International

Selenoglycoproteins attenuate adhesion of tumor cells to the brain microvascular endothelium via a process involving NF-κB activation

Selenium-containing compounds and selenized yeast have anti-cancer properties. In order to address possible mechanisms involved in these effects, selenoglycoproteins (SGP) were extracted from selenium-enriched yeast at pH 4.0 and 6.5 (the fractions are called SGP40 and SGP65, respectively), followed by evaluation of their impact on the interactions of lung and breast tumor cells with human brain microvascular endothelial cells (HBMEC). Extracted SGPs, especially SGP40, significantly inhibited adhesion of tumor cells to HBMEC and their transendothelial migration. Because the active component(s) of SGPs are unknown, small selenium-containing compounds (leucyl-valyl-selenomethionyl-arginine [LVSe-MR] and methylseleno adenosine [M-Se-A]), which are normally present in selenized yeast, were introduced as additional treatment groups. Treatment of HBMEC with SGP40, LVSe-MR, and M-Se-A induced changes in gene signatures, which suggested a central involvement of NF-κB-dependent pathway. These observations were confirmed in the subsequent analysis of NF-κB DNA binding activity, quantitative measurements of the expression of selected genes and proteins, and tumor cell adhesion assay with a specific NF-κB inhibitor as the additional treatment factor. These findings indicate that specific organic selenium-containing compounds have the ability to inhibit tumor cell adhesion to brain endothelial cells via downregulation of NF-κB. SGPs appear to be more effective than small selenium-containing compounds, suggesting the role of not only selenium but also the glycoprotein component in the observed protective impact