Jinyu Zhu

Metformin Inhibits Vascular Calcification in Female Rat Aortic Smooth Muscle Cells via the AMPK-eNOS-NO Pathway

Metformin exhibits diverse protective effects against diabetic complications, such as bone loss. Here, we investigated the effect of metformin on vascular calcification, another type 2 diabetes complication. In female rat aortic smooth muscle cells (RASMCs), we observed that metformin significantly alleviated β-glycerophosphate-induced Ca deposition and alkaline phosphatase activity, corresponding with reduced expression of some specific genes in osteoblast-like cells, including Runx2 and bone morphogenetic protein-2, and positive effects on α-actin expression, a specific marker of smooth muscle cells. Mechanistic analysis showed that phosphorylation levels of both AMP-activated protein kinase (AMPK) and endothelial nitric oxide synthase (eNOS) were increased with NO overproduction. After inhibition of either AMPK or eNOS with the pharmacologic inhibitors, compound C or Nω-Nitro-L-arginine methyl ester, NO production was lowered and metformin-meditated vascular protection against β-glycerophosphate-induced Ca deposition was removed. Our results support that metformin prevents vascular calcification via AMPK-eNOS-NO pathway.

Pyrroloquinoline quinone (PQQ) inhibits lipopolysaccharide induced inflammation in part via downregulated NF-κB and p38/JNK activation in microglial and attenuates microglia activation in lipopolysaccharide treatment mice.

Therapeutic strategies designed to inhibit the activation of microglia may lead to significant advancement in the treatment of most neurodegenerative diseases. Pyrroloquinoline quinone (PQQ) is a naturally occurring redox cofactor that acts as an essential nutrient, antioxidant, and has been reported to exert potent immunosuppressive effects. In the present study, the anti-inflammatory effects of PQQ was investigated in LPS treated primary microglia cells. Our observations showed that pretreatment with PQQ significantly inhibited the production of NO and PGE2 and suppressed the expression of pro-inflammatory mediators such as iNOS, COX-2, TNF-a, IL-1b, IL-6, MCP-1 and MIP-1a in LPS treated primary microglia cells. The nuclear translocation of NF-κB and the phosphorylation level of p65, p38 and JNK MAP kinase pathways were also inhibited by PQQ in LPS stimulated primary microglia cells. Further a systemic LPS treatment acute inflammation murine brain model was used to study the suppressive effects of PQQ against neuroinflammation in vivo. Mice treated with PQQ demonstrated marked attenuation of neuroinflammation based on Western blotting and immunohistochemistry analysis of Iba1-against antibody in the brain tissue. Indicated that PQQ protected primary cortical neurons against microglia-mediated neurotoxicity. These results collectively suggested that PQQ might be a promising therapeutic agent for alleviating the progress of neurodegenerative diseases associated with microglia activation.

Pyrroloquinoline Quinine Inhibits RANKL-Mediated Expression of NFATc1 in Part via Suppression of c-Fos in Mouse Bone Marrow Cells and Inhibits Wear Particle-Induced Osteolysis in Mice

The effects of pyrroloquinoline quinine (PQQ) on RANKL-induced osteoclast differentiation and on wear particle-induced osteolysis were examined in this study. PQQ inhibited RANKL-mediated osteoclast differentiation in bone marrow macrophages (BMMs) in a dose-dependent manner without any evidence of cytotoxicity. The mRNA expression of c-Fos, NFATc1, and TRAP in RANKL-treated BMMs was inhibited by PQQ treatment. Moreover, RANKL-induced c-Fos and NFATc1 protein expression was suppressed by PQQ. PQQ additionally inhibited the bone resorptive activity of differentiated osteoclasts. Further a UHMWPE-induced murine calvaria erosion model study was performed to assess the effects of PQQ on wear particle-induced osteolysis in vivo. Mice treated with PQQ demonstrated marked attenuation of bone erosion based on Micro-CT and histologic analysis of calvaria. These results collectively suggested that PQQ demonstrated inhibitory effects on osteoclast differentiation in vitro and may suppress wear particle-induced osteolysis in vivo, indicating that PQQ may therefore serve as a useful drug in the prevention of bone loss.

Peri-implant and systemic effects of high-/low-affinity bisphosphonate-hydroxyapatite composite coatings in a rabbit model with peri-implant high bone turnover

BackgroundHydroxyapatite (HA) coatings composed with bisphosphonates (BPs) which have high mineral-binding affinities have been confirmed to successfully enhance implant stability. However, few previous studies focused on HA coatings composed with low-affinity BPs or on systemic effects of locally released BPs.MethodsIn this long-term study, we developed two kinds of BP-HA composite coatings using either high-affinity BP (alendronate, ALN) or low-affinity BP (risedronate, RIS). Thirty-six rabbits were divided into three groups according to different coating applications (group I: HA, group II: ALN-HA, and group III: RIS-HA). Implants were inserted into the proximal region of the medullary cavity of the left tibiay. At insertion, 2 × 108 wear particles were injected around implants to induce a peri-implant high bone turnover environment. Both local (left tibias) and systemic (right tibias and lumbar vertebrae) inhibitory effect on bone resorption were compared, including bone-implant integration, bone architecture, bone mineral density (BMD), implant stability, and serum levels of bone turnover markers.ResultsThe results indicated that ALN-HA composite coating, which could induce higher bone-implant contact (BIC) ratio, bone mass augmentation, BMD, and implant stability in the peri-implant region, was more potent on peri-implant bone, while RIS-HA composite coating, which had significant systemic effect, was more potent on non-peri-implant bone, especially lumbar vertebrae.ConclusionsIt is instructive and meaningful to further clinical studies that we could choose different BP-HA composite coatings according to the patient’s condition.

Angelica sinensis extract inhibits RANKL-mediated osteoclastogenesis by down-regulated the expression of NFATc1 in mouse bone marrow cells

BackgroundDestructive erosion of bone or osteolysis is a major complication of inflammatory conditions such as rheumatoid arthritis (RA), periodontal disease, and periprosthetic osteolysis. Natural plant-derived products have received recent attention as potential therapeutic and preventative drugs in human disease.MethodsThe effect of Angelica sinensis (AS) extract on RANKL-induced osteoclast differentiation was examined in this study. The osteoclast precursor cell line bone marrow macrophages (BMMs) was cultured and stimulated with RANKL followed by treatment with AS at several doses. Gene expression profiles of c-Fos, c-Jun, NFATc1, TRAP, and OSCAR were sequentially evaluated.ResultsAS extract inhibited RANKL-mediated osteoclast differentiation in BMMs in a dose-dependent manner without any evidence of cytotoxicity. AS extract strongly inhibited p38, ERK, JNK, p65 phosphorylation and I-κB degradation in RANKL-stimulated BMMs. AS extract also inhibited the mRNA expression of c-Fos, c-Jun, NFATc1, TRAP, and OSCAR in RANKL-treated BMMs. Moreover, RANKL-induced c-Fos, c-Jun and NFATc1 protein expression was suppressed by AS extract.ConclusionsThese results collectively suggested that AS extract demonstrated inhibitory effects on RANKL-mediated osteoclast differentiation in bone marrow macrophages in vitro, indicating that AS may therefore serve as a useful drug in the prevention of bone loss.

Comparison of the effects of pretreatment with repeated electroacupuncture at GV20 and ST36 on fatigue in rats

Objective To investigate and compare the effects of electroacupuncture (EA) pretreatment at GV20 and ST36 on fatigue in rats. Methods Rats were randomly allocated into 4 groups: control, fatigue, fatigue+GV20 and fatigue+ST36. The last two groups received EA pretreatment at GV20 or ST36 for 5 days before being maintained in cages filled with water to a height of 1.5 cm to establish an animal model of fatigue. We used the weight-loaded forced swimming test and open-field test and measured 5-hydroxyindoleacetic acid (5-HIAA)/5-hydroxytryptamine (5-HT) ratios and serum levels of blood urea nitrogen (BUN), lactic dehydrogenase (LDH) and testosterone as behavioural and biochemical markers of fatigue in the rats. Results Compared with controls, rats in the (untreated) fatigue group exhibited reduced weight-loaded swimming times and total movement/distance in the open-field test, plus higher BUN/LDH and lower testosterone levels. Both EA pretreatment at GV20 and ST36 increased swimming times, and reduced serum BUN/LDH. EA pretreatment at GV20 (but not ST36) increased serum testosterone. The 5-HIAA/5-HT ratios in four brain regions were decreased in the fatigue+GV20 group compared with the fatigue group (p<0.05). By contrast, 5-HIAA/5-HT ratios in striatum and hypothalamus (but not hippocampus or midbrain) were decreased in the fatigue+ST36 group compared with the fatigue group (p<0.05). Furthermore, only pretreatment at GV20 affected the results of the open-field test. Conclusions These results suggest that EA pretreatment had a positive effect on the prevention of fatigue. Pretreatment at GV20 had a greater anti-fatigue effect than pretreatment at ST36.

Valgus deformity caused by dysplasia epiphysealis hemimelica in the knee

A rare case of dysplasia epiphysealis hemimelica in the left knee which caused valgus deformity and dysfunction of the limb is presented in this article. Subtotal excision of the lesion, distal femoral medial wedge osteotomy, and reconstruction of the medial collateral ligament were performed for treatment. Cannulated screws and plaster casts were used to stabilize the ligament and distal femur. Two years after removal and reconstruction, the knee was symptom free. The left knee laxity was restored and the mechanical axis of the distal femur was realigned.

Metformin suppresses UHMWPE particle-induced osteolysis in the mouse calvaria by promoting polarization of macrophages to an anti-inflammatory phenotype

BackgroundImplant failure remains a major obstacle to successful treatment via TJA. Periprosthetic osteolysis and aseptic loosening are considered as proof of wear debris-induced disruption of local regulatory mechanisms related to excessive bone resorption associated with osteolysis and the damage at the bone-prosthesis interface. Therefore, there is an immediate need to explore strategies for limiting and curing periprosthetic osteolysis and aseptic loosening.MethodsWe analyzed the in vitro cytokine production by primary mouse bone marrow macrophages (BMMs) that were exposed to ultra-high molecular weight polyethylene (UHMWPE) particles and treated with metformin at different concentrations with or without 5-aminoimidazole-4-carboxamide ribonucleoside to activate or inhibit AMPK. A mouse calvarial model was used to examine the in vivo effects of metformin on UHMWPE particle-induced osteolysis.ResultsWith particles, primary mouse BMMs secreted more pro-inflammatory cytokines tumor necrosis factor-α and interleukin (IL)-6. Treatment with metformin inhibited these variations and promoted the release of cytokine IL-10 with anti-inflammatory capability. In vivo, metformin reduced the production of pro-inflammatory cytokines, osteoclastogenesis, and osteolysis, increasing IL-10 production. Metformin also promoted the polarization of macrophages to an anti-inflammatory phenotype in vivo via AMPK activation.DiscussionA crucial point in limiting and correcting the periprosthetic osteolysis and aseptic loosening is the inhibition of inflammatory factor production and osteoclast activation induced by activated macrophages. The ability of metformin to attenuate osteolysis induced in mouse calvaria by the particles was related to a reduction in osteoclast number and polarization of macrophages to an anti-inflammatory functional phenotype.ConclusionsMetformin could limit the osteolysis induced by implant debris. Therefore, we hypothesized that metformin could be a potential drug for osteolysis induced by implant debris.