Ethnopharmacological relevance: Tougu Xiaotong capsule (TXC) is a Chinese herbal compound that belongs to a range of Chinese herbs functioning as 'kidney invigorators and liver softeners' commonly used to treat osteoarthritis (OA) in China.
Aims of the study: The aims of the present study are to confirm the therapeutic effects of TXC in an OA cell model and to determine the mechanisms involved in such effects.
Materials and methods: A tunicamycin (Tm)-exposed OA cell model was employed, and the effects of TXC were confirmed by observing cell viability and apoptosis. The reduced cell viability and increased apoptosis caused by Tm were improved by TXC, confirming the cellular protection of TXC. We then investigated the expression of biomarkers related to the endoplasmic reticulum (ER) stress pathway, including microRNA-211 (miR-211), a regulator in the ER stress pathway.
Results: Downregulation of X-box binding protein 1 (Xbp-1) and miR-211 expression following Tm administration was reversed by TXC. Moreover, the upregulation by Tm of the expression levels of binding immunoglobulin protein, Xbp-1, activating transcription factor 4, C/EBP-homologous protein, Caspase-9 and Caspase-3 was downregulated by TXC. These results indicated that the ER stress pathway-related mechanism may play a potential role in the therapeutic effects of TXC.
Conclusions: The present study provides evidence of the therapeutic effects of TXC at the cell level and describes a cellular model for establishing the mechanisms of the effects of TXC used in the treatment of OA.
Keywords: Apoptosis; Cell viability; Chondrocyte; Endoplasmic reticulum stress pathway; MiR-211; Osteoarthritis; Tougu Xiaotong capsule.
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