Bushen Zhuangjin decoction inhibits TM-induced chondrocyte apoptosis mediated by endoplasmic reticulum stress

Abstract

Chondrocyte apoptosis triggered by endoplasmic reticulum (ER) stress plays a vital role in the pathogenesis of osteoarthritis (OA). Bushen Zhuangjin decoction (BZD) has been widely used in the treatment of OA. However, the cellular and molecular mechanisms responsible for the inhibitory effects of BZD on chondrocyte apoptosis remain to be elucidated. In the present study, we investigated the effects of BZD on ER stress-induced chondrocyte apoptosis using a chondrocyte in vitro model of OA. Chondrocytes obtained from the articular cartilage of the knee joints of Sprague Dawley (SD) rats were detected by immunohistochemical staining for type II collagen. The ER stress-mediated apoptosis of tunicamycin (TM)-stimulated chondrocytes was detected using 4-phenylbutyric acid (4-PBA). We found that 4-PBA inhibited TM-induced chondrocyte apoptosis, which confirmed the successful induction of chondrocyte apoptosis. BZD enhanced the viability of the TM-stimulated chondrocytes in a dose- and time-dependent manner, as shown by MTT assay. The apoptotic rate and the loss of mitochondrial membrane potential (ΔΨm) of the TM-stimulated chondrocytes treated with BZD was markedly decreased compared with those of chondrocytes not treated with BZD, as shown by 4′,6-diamidino-2-phenylindole (DAPI) staining, Annexin V-FITC binding assay and JC-1 assay. To further elucidate the mechanisms responsible for the inhibitory effects of BZD on TM-induced chondrocyte apoptosis mediated by ER stress, the mRNA and protein expression levels of binding immunoglobulin protein (Bip), X-box binding protein 1 (Xbp1), activating transcription factor 4 (Atf4), C/EBP-homologous protein (Chop), caspase-9, caspase-3, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) were measured by reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. In the TM-stimulated chondrocytes treated with BZD, the mRNA and protein expression levels of Bip, Atf4, Chop, caspase-9, caspase-3 and Bax were significantly decreased, whereas the mRNA and protein expression levels of Xbp1 and Bcl-2 were significantly increased compared with the TM-stimulated chondrocytes not treated with BZD. Additionally, all our findings demonstrated that there was no significant difference between the TM-stimulated chondrocytes treated with BZD and those treated with 4-PBA. Taken together, our results indicate that BZD inhibits TM-induced chondrocyte apoptosis mediated by ER stress. Thus, BZD may be a potential therapeutic agent for use in the treatment of OA.

Retracted Article: Salvianolic acid B inhibits inflammatory response and cell apoptosisviathe PI3K/Akt signaling pathway in IL-1β-induced osteoarthritis chondrocytes

“…40 It has been reported that Chinese herbal medicine and its extract can suppress this apoptosis aer OA, but the effect of Sal B on chondrocyte apoptosis has not been reported. [41][42][43] In this study, we examined chondrocyte activity, chondrocyte proliferation marker molecules Col II, Col X and the expression of apoptosis-related proteins Bax and Bcl-2. We also explored the effect of Sal B on chondrocyte proliferation and apoptosis.…”

Insights into the Action Mechanisms of Traditional Chinese Medicine in Osteoarthritis

“…Chondrocytes apoptosis can also be triggered by endoplasmic reticulum (ER) stress, which is caused by the accumulation of unfolded or misfolded proteins. In tunicamycin- (TM-) induced chondrocytes, Bushen Zhuangjin Decoction decreases the mRNA and protein expression of BIP, ATF4, CHOP, caspase-9, caspase-3, and Bax and increases the expression of XBP1 and Bcl-2 [ 54 ]. Our research group shows that 5,7,3′,4′-tetramethoxyflavone (TMF), an active compound isolated from Murraya exotica (L.), can inhibit chondrocytes apoptosis through downregulation of the increased EP/cAMP/PKA signaling pathway and β -catenin signaling pathway induced by PGE 2 [ 55 ].…”

Taurine alleviates endoplasmic reticulum stress in the chondrocytes from patients with osteoarthritis

“…ER stress has been reported to be involved in ischemia reperfusion, diabetes mellitus, liver disease, kidney disease and neuro-degenerative disease [13,[21][22][23][24]. In addition, a large number of studies have proved that ER stress is also associated with chondrocyte death by apoptosis in vivo and in vitro [6,14].…”

“…Chondrocytes, the only cells existing in articular cartilage, can generate and maintain the articular cartilaginous matrix, which is composed mainly of collagen and proteoglycans [4]. Recent reports have demonstrated that elevated chondrocyte loss caused by apoptosis is a major feature of OA [5,6].…”

“…Endoplasmic reticulum (ER) stress, which occurs due to an imbalance between the load of unfolded or misfolded proteins in the ER and the processing capacity of ER, participates in many disease pathologies [6,7]. Recent studies have demonstrated that ER stress in chondrocytes is responsible for chondrocyte apoptosis along with the progression of OA [4,8,9].…”