Type II collagen peptide stimulates Akt leading to nuclear factor-κB activation: Its inhibition by hyaluronan

Abstract

While nuclear factor (NF)-κB is a critical pathway for matrix metalloproteinase (MMP)-13 induction in chondrocytes, intracellular upstream events for NF-κB activation by the type II collagen peptide (CB12-II) with catabolic activities remain unclear. Hyaluronan (HA) of high molecular weight is clinically used for treatment of osteoarthritis (OA) by intra-articular injection. Although HA can suppress NF-κB activation by CB12-II, it is still obscure how HA affects intracellular upstream pathways leading to NF-κB up-regulation in response to CB12-II. Thus, this study was aimed to investigate the involvement of phosphoinositide-3-OH kinase (PI3K)/Akt in the inhibition of CB12-II-activated NF-κB pathway by HA in OA chondrocytes. In monolayer cultures, pretreatment with HA of 2700 kDa significantly inhibited MMP-13 production by CB12-II-stimulated chondrocytes. CB12-II activated Akt and NF-κB whereas HA down-regulated CB12-II-stimulated phosphorylation of Akt and NF-κB. Inhibition studies using LY294002 revealed the requirement of PI3K/Akt pathway for CB12-II-stimulated NF-κB activation in association with MMP-13 production. Pretreatment with anti-CD44 antibody reversed the inhibitory effects of HA on CB12-IIinduced production of MMP-13 and activation of Akt and NF-κB. Herein, we provided the first evidence that HA suppresses CB12-II-activated PI3K/Akt pathway leading to down-regulation of NF-κB with diminished MMP-13 production through interaction with CD44.Degradation products of cartilage matrix are recognized as important amplifiers in diseased joints like osteoarthritis (OA) because of the ability to stimulate cartilage destruction through catabolic activities (28). In OA cartilage, type II collagen is cleaved by collagenases, especially matrix metalloproteinase (MMP)-13 (4), resulting in denaturation of the triple helix of the collagen (10). Denaturation and degradation of type II collagen produce proteolytic fragments of type II collagen. Recent reports suggest that type II collagen fragments may alter the environment within cartilage matrix in OA to stimulate MMP induction (24). Our previous studies have demonstrated that a 24-mer synthetic peptide of type II collagen can stimulate type II collagen cleavage with MMP-13 induction in cartilage explant culture (25,35). This synthetic peptide named CB12-II is derived from the CB12 fragment which is generated with cyanogen bromide cleavage of type II collagen, and corresponds to the residues 195-218 of bovine type II collagen. MMP-13 induction by CB12-II has been found to require activation of catabolic intracellular signaling pathways such as p38 mitogen-activated protein kinase (32) and nuclear factor (NF)-κB (33). Nuclear factor (NF)-κB, which consists of p50 and p65 subunits, is critical in the regulation of many genes including cytokines, chemokines, and adhesion molecules. Activation of NF-κB is dependent on the phosphorylation and degradation of IκB, an endogenous inhibitor that binds to NF-κB in the cytoplasm (2). The released NF-κB then translocate...

Glycogen Synthase Kinase-3β Inhibition Links Mitochondrial Dysfunction, Extracellular Matrix Remodelling and Terminal Differentiation in Chondrocytes

“…Healthy articular chondrocytes are post-mitotic cells expected to survive for several years in a maturation arrested state which only requires a low homeostatic turnover of extracellular matrix (ECM) proteins. An intact ECM delivers survival signal to chondrocytes 1 while, conversely, proteolytic enzymes leads to production of bioactive molecules that promote chondrocyte differentiation, thus boosting osteoarthritis (OA) pathogenesis 2 , 3 .…”

Pioglitazone-Loaded Cartilage-Targeted Nanomicelles (Pio@C-HA-DOs) for Osteoarthritis Treatment

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Proportion of collagen type II in the extracellular matrix promotes the differentiation of human adipose‐derived mesenchymal stem cells into nucleus pulposus cells

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