Maslinic acid alleviates intervertebral disc degeneration by inhibiting the PI3K/AKT and NF-κB signaling pathways.

Intervertebral disc degeneration (IDD) is the cause of low back pain (LBP), and recent research has suggested that inflammatory cytokines play a significant role in this process. Maslinic acid (MA), a natural compound found in olive plants ( Olea europaea), has anti-inflammatory properties, but its potential for treating IDD is unclear. The current study aims to investigate the effects of MA on TNFα-induced IDD in vitro and in other in vivo models. Our findings suggest that MA ameliorates the imbalance of the extracellular matrix (ECM) and mitigates senescence by upregulating aggrecan and collagen II levels as well as downregulating MMP and ADAMTS levels in nucleus pulposus cells (NPCs). It can also impede the progression of IDD in rats. We further find that MA significantly affects the PI3K/AKT and NF-κB pathways in TNFα-induced NPCs determined by RNA-seq and experimental verification, while the AKT agonist Sc-79 eliminates these signaling cascades. Furthermore, molecular docking simulation shows that MA directly binds to PI3K. Dysfunction of the PI3K/AKT pathway and ECM metabolism has also been confirmed in clinical specimens of degenerated nucleus pulposus. This study demonstrates that MA may hold promise as a therapeutic agent for alleviating ECM metabolism disorders and senescence to treat IDD.

Irisin enhances chondrogenic differentiation of human mesenchymal stem cells via Rap1/PI3K/AKT axis.

BACKGROUND: Human mesenchymal stem cells (hMSCs) have been proven to have inherent chondrogenic differentiation potential, which appears to be used in cartilage regeneration. Increasing evidence suggests that irisin enhances osteoblast differentiation of MSCs, but little is known about its potential on chondrogenic differentiation. METHODS: In the study, we investigated the effects of irisin on chondrogenic differentiation of hMSCs using a high-density pellet culture system. The cartilage pellets were evaluated by morphology, and the metabolism of cartilage matrix was detected by qPCR, western blot and immunohistochemistry. Next, RNA-seq was performed to explore the underlying mechanism. Furthermore, using the transduction of plasmid, miRNAs mimics and inhibitor, the activation of Rap1/PI3K/AKT axis, the expression level of SIPA1L2, and the functional verification of miR-125b-5p were detected on day 7 of chondrogenic differentiation of hMSCs. RESULTS: Compared with the controls, we found that irisin treatment could significantly enhance the chondrogenic differentiation of hMSCs, enlarge the induced-cartilage tissue and up-regulate the expression levels of cartilage markers. RNA-seq indicated that irisin activated the Rap1 and PI3K/AKT signaling pathway, and the lower expression level of SIPA1L2 and the higher expression level of miR-125b-5p were found in irisin-treated group. Further, we found that irisin treatment could up-regulate the expression level of miR-125b-5p, targeting SIPA1L2 and consequently activating the Rap1/PI3K/AKT axis on the process of chondrogenic differentiation of hMSCs. CONCLUSIONS: Collectively, our study reveals that irisin can enhance chondrogenic differentiation of hMSCs via the Rap1/PI3K/AKT pathway, suggesting that irisin possesses prospects in cartilage regeneration.

Irisin Ameliorates Intervertebral Disc Degeneration by Activating LATS/YAP/CTGF Signaling.

Unbalanced metabolism of an extracellular matrix (ECM) in nucleus pulposus cells (NPCs) is widely acknowledged as the primary cause of intervertebral disc degeneration (IDD). Irisin, a novel myokine, is cleaved from fibronectin type III domain-containing 5 (FNDC5) and has recently been proven to regulate the metabolism of ECM. However, little is known about its potential on NPCs and the development of IDD. Therefore, this study sought to examine the protective effects and molecular mechanism of irisin on IDD in vivo and in vitro. Decreased expression levels of FNDC5 and anabolism markers (COL2A1 and ACAN) but increased levels of catabolism markers (ADAMTS4) were found in degenerative nucleus pulposus (NP) tissues. In a punctured-induced rat IDD model, irisin treatment was found to significantly slow the development of IDD, and in TNF-α-stimulated NPCs, irisin treatment partly reversed the disorder of ECM metabolism. In mechanism, RNA-seq results suggested that irisin treatment affected the Hippo signaling pathway. Further studies revealed that with irisin treatment, the phosphorylation levels of key factors (LATS and YAP) were downregulated, while the expression level of CTGF was upregulated. Moreover, CTGF knockdown partially eliminated the protective effects of irisin on the metabolism of ECM in NPCs, including inhibiting the anabolism and promoting the catabolism. Taken together, this study demonstrated that the expression levels of FNDC5 were decreased in degenerative NP tissues, while irisin treatment promoted the anabolism, inhibited the catabolism of the ECM in NPCs, and delayed the progression of IDD via LATS/YAP/CTGF signaling. These results shed light on the protective actions of irisin on NPCs, leading to the development of a novel therapeutic target for treating IDD.

[New external spinal skeletal fixation combined with percutaneous injury vertebra bone grafting for the treatment of two-segment thoracolumbar fractures].

OBJECTIVE: To investigate the clinical results of new external spinal skeletal fixation combined with percutaneous injury vertebra bone grafting in the treatment of two-segment thoracolumbar fractures without neural dysfunction. METHODS: The clinical data of 28 patients with two-segment thoracolumbar fractures without neural dysfunction treated from January 2013 to August 2015 were retrospectively analyzed. There were 17 males and 11 females, with a mean age of(37.5±10.3) years (ranging from 19 to 55 years). According to fracture AO classification, all 28 cases were type A, including 2 cases of T10,11, 3 cases of T11,12, 9 cases of T12-L1, 4 cases of L1,2, 5 cases of L2,3, 4 cases of L3,4, 1 case of L4,5. All 28 patients received treatment of new external spinal skeletal fixation and percutaneous injury vertebra bone grafting. Operation time, intraoperative bleeding and related complications were recorded. The informations of vertebral anterior border height percentage and bone fusion were observed by radiography before and after operation, before removed external fixation and final follow-up. Visual analogue scale(VAS) was used to evaluate the clinical effects. RESULTS: All the patients were followed up for 13 to 32 months with an average of (24.5±3.5) months. There was significant difference by the time of 3 days postoperatively, before removed external fixation, final follow-up comparing with the preoperative in vertebral anterior border height percentage and VAS score(P<0.05). There was no significant difference in vertebral anterior border height percentage by the time of 3 days postoperatively, before removed external fixation comparing with final follow-up(P>0.05). While the VAS score showed a gradually declining trend, screw lossening ocurred in 2 cases and nail tracker infection occurred in 1 case after operation, and no other complications were found. CONCLUSIONS: New external spinal skeletal fixation and percutaneous injury vertebra bone grafting can got satisfactory clinical effect in treating two-segment thoracolumbar fractures without neural dysfunction, which is an effective method of minimally invasive surgery.