A peptidyl-glucosamine derivative affects IKKα kinase activity in human chondrocytes

The human chondrosarcoma cell line HTB-94 and human primary chondrocytes were stimulated with tumor necrosis factor (TNF)α after pre-treatment with GlcN or NAPA. Gene mRNA expression level was evaluated by real-time PCR. Inhibitor κB protein (IκB)α phosphorylation and p65 nuclear re-localization were analyzed by Western blotting; IKKα nuclear re-localization was also investigated by immunocytochemistry and Western blotting. IKK kinase activity was studied by in vitro kinase assay.After TNFα stimulation, the mRNA expression level of some of the genes under NF-κB control, such as interleukin (IL)-6 and IL-8, increased, while treatment with GlcN and NAPA reverted the effect. We investigated the possibility that GlcN and NAPA inhibit IKK kinase activity and found that NAPA inhibits the IKKα kinase activity, whereas GlcN does not. Interestingly, both GlcN and NAPA inhibit IKKα nuclear re-localization.Our results demonstrate that glucosamine and its peptidyl derivative can interfere with NF-κB signaling pathway by inhibiting IKKα activity in human chondrocytes. However, the mechanism of action of the two molecules is not completely overlapping. While NAPA can both specifically inhibit the IKKα kinase activity and IKKα nuclear re-localization, GlcN only acts on IKKα nuclear re-localization.Osteoarthritis (OA), the most common rheumatic disease, is a major cause of disability. It is strongly associated with aging and its medical relevance is rising in the Western population given the increasing proportion of older people. This pathology is characterized by progressive destruction of the extracellular matrix (ECM), causing pain and disability in patients. OA is a non-curable disease and its pharmacological treatment is based mainly on analgesic agents or non-steroidal anti-inflammatory drugs (NSAIDs). Structure-modifying agents are also administered to OA patients, with the aim of preventing or delaying cartilage degradation by pharmacological treatment [1]. Several chondrop