EZH2 upregulates the expression of MAPK1 to promote intervertebral disc degeneration via suppression of miR-129-5p.

BACKGROUND: This study was designed to verify whether enhancer of zeste homolog 2 (EZH2) affects intervertebral disc degeneration (IVDD) development through regulation of microRNA (miR)-129-5p/MAPK1. METHODS: Initially, we collected lumbar nucleus pulposus (NP) tissue samples from patients with juvenile idiopathic scoliosis (n = 14) and IVDD (n = 34). We measured the expression of related genes in clinical IVDD tissues and a lipopolysaccharide (LPS)-induced NP cell model. After loss- and gain-of-function assays, NP cell proliferation and senescence were examined. The targeting relationship between miR-129-5p and MAPK1 was explored by dual luciferase reporter gene and RNA immunoprecipitation (RIP) assays. The enrichment of EZH2 and H3K27me3 in miR-129-5p promoter was verified by chromatin immunoprecipitation (ChIP). Finally, an IVDD rat model was established to test the effects of transduction with lentiviral vector carrying miR-129-5p agomir and/or oe-EZH2 in vivo. RESULTS: miR-129-5p was underexpressed, and EZH2 and MAPK1 levels were overexpressed in lumbar nucleus pulposus from human IVDD patients and in LPS-induced NP cells. miR-129-5p overexpression or silencing of MAPK1 promoted proliferation of NP cells, while inhibiting their senescence. EZH2 inhibited miR-129-5p through H3K27me3 modification in the miR-129-5p promoter. miR-129-5p could target the downregulation of MAPK1 expression. EZH2 overexpression increased the release of inflammatory factors and cell senescence factors, which was reversed by miR-129-5p agomir in vivo. CONCLUSIONS: Taken together, EZH2 inhibits miR-129-5p through H3K27me3 modification, which upregulates MAPK1, thereby promoting the development of IVDD.

KLF2 regulates osteoblast differentiation by targeting of Runx2.

Osteoblast differentiation plays a critical role in bone formation and maintaining balance in bone remodeling. Runt-related transcription factor 2 (Runx2) is a central transcription factor regulating osteoblast differentiation and promoting bone mineralization. Until now, the molecular regulatory basis and especially the gene regulatory network of osteogenic differentiation have been unclear. Krüppel-like factor 2 (KLF2) is a zinc finger structure and DNA-binding transcription factor. The current study aimed to investigate the physiological function of KLF2 in osteoblast differentiation. Our results indicate that KLF2 is expressed in pre-osteoblast MC3T3-E1 cells and primary osteoblasts. Interestingly, KLF2 expression is increased in osteoblasts during the osteoblastic differentiation process. Overexpression of KLF2 in MC3T3-E1 cells promoted the expression of the osteoblastic differentiation marker genes Alp, Osx, and Ocn, and stimulated mineralization by increasing Runx2 expression at both the mRNA and protein levels. In contrast, knockdown of KLF2 produced the opposite effects. Importantly, we found that KLF2 could physically interact with Runx2. KLF2 promoted osteoblast differentiation by regulating Runx2 and physically interacting with Runx2. Taken together, the findings of this study identify KLF2 as a novel regulator of osteoblast differentiation. Our findings suggest that KLF2 might be a new therapeutic target for bone disease.

Theaflavin-3,3'-Digallate Ameliorates Collagen-Induced Arthritis Through Regulation of Autophagy and Macrophage Polarization.

Purpose: Previous studies have presented that theaflavin-3,3'-digallate (TFDG), one of natural flavonoids, have protective effects on collagen-induced arthritis (CIA). Besides, it was reported that TFDG could affect inflammatory signaling pathways, like NF-κB, JNK, and so on, to ameliorate inflammation. However, the anti-inflammatory mechanisms mentioned above are common to natural flavonoid products including TFDG. Therefore, this study aimed to further investigate the other mechanisms of TFDG against CIA. Methods: DBA/1 mice (8-10 weeks) were intravenously injected Freund's Adjuvant (100µL) at the base of tail and intraperitoneally injected PBS or different dosage of TFDG (1 mg/kg or 10 mg/kg). Then the paw and knee tissues were collected to assess the severity of joint destruction. In vitro experiments, bone marrow macrophages (BMMs) were exposed to TNF-α (10ng/mL) with or without different concentrations of TFDG (0.1µmol/L or 1.0µmol/L). Besides, the targets of TFDG were predicted with docking software and were verified through experiment. Results: TFDG treatment could reduce M1 macrophage (pro-inflammatory) and inflammatory cytokines, such as IL-1, IL- 6 and TNF-α, both in vitro and in vivo. At the same time, the M2 macrophage (alternatively activated) polarization was promoted by TFDG. Animal experiments showed TFDG ameliorated joint destructions. For investigating the mechanisms, the targets of TFDG were predicted by bioinformatics tools. According to predictions, we hypothesized that TFDG could act with BCL-2 to weaken the interaction between BCL-2 and Beclin1. Beclin1 plays a central role in autophagy, and we found that the autophagy level of BMMs was recovered by TFDG. Besides, 3-MA, an autophagy inhibitor, could attenuate the therapeutic effect of TFDG. Conclusion: TFDG protected against collagen-induced arthritis by attenuating the inflammation and promoting anti-inflammatory M2 macrophage polarization through controlling autophagy.

Theaflavin-3,3'-Digallate Promotes the Formation of Osteoblasts Under Inflammatory Environment and Increases the Bone Mass of Ovariectomized Mice.

Postmenopausal osteoporosis is a disease of bone mass reduction and structural changes due to estrogen deficiency, which can eventually lead to increased pain and fracture risk. Chronic inflammatory microenvironment leading to the decreased activation of osteoblasts and inhibition of bone formation is an important pathological factor that leads to osteoporosis. Theaflavin-3,3'-digallate (TFDG) is an extract of black tea, which has potential anti-inflammatory and antiviral effects. In our study, we found that TFDG significantly increased the bone mass of ovariectomized (OVX) mice by micro-CT analysis. Compared with OVX mice, TFDG reduced the release of proinflammatory cytokines and increased the expression of osteogenic markers in vivo. In vitro experiments demonstrated that TFDG could promote the formation of osteoblasts in inflammatory environment and enhance their mineralization ability. In this process, TFDG activated MAPK, Wnt/ß-Catenin and BMP/Smad signaling pathways inhibited by TNF-α, and then promoted the transcription of osteogenic related factors including Runx2 and Osterix, promoting the differentiation and maturation of osteoblasts eventually. In general, our study confirmed that TFDG was able to promote osteoblast differentiation under inflammatory environment, enhance its mineralization ability, and ultimately increase bone mass in ovariectomized mice. These results suggested that TFDG might have the potential to be a more effective treatment of postmenopausal osteoporosis.

A scalable data transmission scheme for implantable optogenetic visual prostheses.

OBJECTIVE: This work described a video information processing scheme for optogenetic forms of visual cortical prosthetics. APPROACH: The architecture is designed to perform a processing sequence: Initially simplifying the scene, followed by a pragmatic visual encoding scheme which assumes that initially optical stimulation will be stimulating bulk neural tissue rather than driving individual phosphenes. We demonstrate an optical encoder, combined with what we called a zero-run length encoding (zRLE) video compression and decompression scheme-to wirelessly transfer information to an implantable unit in an efficient manner. In the final step, we have incorporated an even power distribution driver to prevent excessive power fluctuations in the optogenetic driving. SIGNIFICANCE: The key novelty in this work centres on the completeness of the scheme, the new zRLE compression algorithm and our even power distributor. MAIN RESULTS: Furthermore, although the paper focusses on the algorithm, we confirm that it can be implemented on real time portable processing hardware which we will use for our visual prosthetics.

Combined anteversion technique in total hip arthroplasty for Crowe IV developmental dysplasia of the hip.

BACKGROUND: A high rate of postoperative dislocation in total hip arthroplasty (THA) for Crowe IV developmental dysplasia of the hip (DDH) has been reported, 1 of the main reasons being higher true acetabular anteversion. If the cup is fixed with normal anteversion, the anterior rim will be excessively exposed, which reduces the contact areas of the cup and bone, affects prosthesis stability, and leads to iliopsoas tendinitis and persistent hip pain after THA. The aim of this study was to demonstrate that when cup anteversion is larger, adjusting femoral anteversion to bring the combined anteversion (CA) into the "safe zone" might prevent dislocation. METHODS: After having fixed the cup in the acetabulum according to the patients' native acetabular anteversion, we shortened and rotated the proximal femur to reduce femoral anteversion, adjusting the CA into the "safe zone". The Harris Hip Score (HHS) was used to evaluate hip joint function. Computerised tomography scanning was used to measure the anteversion angles. RESULTS: All patients were followed up without any dislocation. Preoperative and 12 months after surgery, the mean HHS were 43.3 ± 2.6 (38-47) and 88.1 ± 3.3 (78-92) respectively. Pre- and post-operation, the mean CA angles were 88.6° ± 9.4° (80.3°-119.4°) and 49.2° ± 2.6° (43.4°-54.4°) respectively. The bone healing time of femoral osteotomy ranged from 4 to 14 months, with a mean time of 7.5 months. CONCLUSIONS: This CA technique in THA for Crowe IV DDH can effectively prevent postoperative dislocation and provide good hip function.

Melatonin attenuates titanium particle-induced osteolysis via activation of Wnt/ß-catenin signaling pathway.

Wear debris-induced inhibition of bone regeneration and extensive bone resorption were common features in peri-prosthetic osteolysis (PPO). Here, we investigated the effect of melatonin on titanium particle-stimulated osteolysis in a murine calvariae model and mouse-mesenchymal-stem cells (mMSCs) culture system. Melatonin inhibited titanium particle-induced osteolysis and increased bone formation at osteolytic sites, confirmed by radiological and histomorphometric data. Furthermore, osteoclast numbers decreased dramatically in the low- and high-melatonin administration mice, as respectively, compared with the untreated animals. Melatonin alleviated titanium particle-induced depression of osteoblastic differentiation and mineralization in mMSCs. Mechanistically, melatonin was found to reduce the degradation of ß-catenin, levels of which were decreased in presence of titanium particles both in vivo and in vitro. To further ensure whether the protective effect of melatonin was mediated by the Wnt/ß-catenin signaling pathway, ICG-001, a selective ß-catenin inhibitor, was added to the melatonin-treated groups and was found to attenuate the effect of melatonin on mMSC mineralization. We also demonstrated that melatonin modulated the balance between receptor activator of nuclear factor kappa-B ligand and osteoprotegerin via activation of Wnt/ß-catenin signaling pathway. These findings strongly suggest that melatonin represents a promising candidate in the treatment of PPO. STATEMENT OF SIGNIFICANCE: Peri-prosthetic osteolysis, initiated by wear debris-induced inhibition of bone regeneration and extensive bone resorption, is the leading cause for implant failure and reason for revision surgery. In the current study, we demonstrated for the first time that melatonin can induce bone regeneration and reduce bone resorption at osteolytic sites caused by titanium-particle stimulation. These effects might be mediated by activating Wnt/ß-catenin signaling pathway and enhancing osteogenic differentiation. Meanwhile, the ability of melatonin to modulate the balance between receptor activator of nuclear factor kappa-B ligand and osteoprotegerin mediated by Wnt/ß-catenin signaling pathway, thereby suppressing osteoclastogenesis, may be implicated in the protective effects of melatonin on titanium-particle-induced bone resorption. These results suggested that melatonin can be considered as a promising therapeutic agent for the prevention and treatment of peri-prosthetic osteolysis.

Titanium particle-induced osteogenic inhibition and bone destruction are mediated by the GSK-3ß/ß-catenin signal pathway.

Wear debris-induced osteogenic inhibition and bone destruction are critical in the initiation of peri-prosthetic osteolysis. However, the molecular mechanism underlying this phenomenon is poorly understood. In this study, we analyzed the involvement of the GSK-3ß/ß-catenin signal pathway, which is important for bone formation in this pathological condition. We established a titanium (Ti) particle-stressed murine MC3T3-E1 cell culture system and calvariae osteolysis model to test the hypothesis that Ti particle-induced osteogenic inhibition and bone destruction are mediated by the GSK-3ß/ß-catenin signal pathway. Our findings showed that Ti particles reduced osteogenic differentiation induced by osteogenesis-related gene expression, alkaline phosphatase activity and matrix mineralization, as well as pSer9-GSK-3ß expression and ß-catenin signal activity. Downregulation of GSK-3ß activity attenuated Ti particle-induced osteogenic inhibition, whereas the ß-catenin inhibitor reversed this protective effect. Moreover, the GSK-3ß/ß-catenin signal pathway mediated the upregulation of RANKL and downregulation of OPG in Ti particle-stressed MC3T3-E1 cells. In addition, our in vivo results showed that Ti particles induced bone loss via regulating GSK-3ß and ß-catenin signals. Based on these results, we concluded that the GSK-3ß/ß-catenin signal pathway mediates the adverse effects of Ti particles on osteoblast differentiation and bone destruction, and can be used as a potential therapeutic target for the treatment of peri-prosthetic osteolysis.