Inhibition of cartilage degeneration and subchondral bone deterioration by Spinacia oleracea in human mimic of ACLT-induced osteoarthritis.

Osteoarthritis (OA) is an aging disorder characterized by degenerated cartilage and sub-chondral bone alteration in affected knee joints. Globally, millions of people suffer from this disease. However, there is a lack of safe and promising therapeutics, making the exploration and development of leads from natural sources urgent. Accordingly, food as medicine may be the most suitable approach for the treatment of this degenerative disease. Herein, we elucidated the protective role of Spinacia oleracea extract (SOE) in an anterior cruciate ligament transection (ACLT) model of osteoarthritis as a mimic of the human condition. ACL transection was done in the tibio-femoral joints of rats. SOE was orally administered at the dosage of 125 and 250 mg kg-1 day-1 for four weeks. It was shown that the animals with SOE treatment had better joint morphology than the ACLT animals, as evident by the shiny appearance of their cartilage. Hematoxylin and safranin-o staining showed that the number of chondrocytes was significantly reduced in the OA model, which was prevented with SOE treatment. The reduction in the cartilage thickness was well observed by toluidine blue staining. The reduced stain by safranin-o and toluidine blue, indicated proteoglycan loss in the ACLT-induced osteoarthritis model. The proteoglycan content and cartilage thickness were restored in the SOE group upon treatment at an SOE dosage of 125 and 250 mg kg-1 day-1. The micro-CT parameters of subchondral bone (SCB) and cartilage degradation markers in the serum corroborated our findings of the protective effects of SOE. In summary, our study suggests that SOE has therapeutic potential, which if taken regularly as a food supplement, can have beneficial effects.

Glucocorticoid aggravates bone micro-architecture deterioration and skeletal muscle atrophy in mice fed on high-fat diet.

High fat diet (HFD) induced obesity has deleterious effect on bone micro-architecture and is associated with low-grade chronic inflammation. Exogenous glucocorticoids (GC) are used to treat inflammatory conditions but with concomitant adverse effect on musculoskeletal system. This study aims to highlight the effect of exogenous GCs on musculoskeletal system in mice fed on HFD. Adult BALB/c mice were fed either normal chow or high fat diet and were exogenously administered with GC for 10 weeks. At the end of the study, animals were autopsied and bone, muscle, serum samples were collected for micro-CT, gene expression and histological study. HFD induced obesity resulted in deterioration in bone micro-architecture predominant in trabecular region of long bones and was significantly amplified with GC administration. Approximately, 37% and 25% loss in femoral and tibial bone volume was observed in obese animals with exogenous GC. Further, deteriorating bone pathology was apparent from reduced bone mineral density (BMD) and bone strength parameter which was correlated to alteration in osteoblast and adipocytes pool of cells in bone marrow. Transcriptional analysis of osteoblast marker genes, bone morphogenetic protein 2 (BMP-2), osteocalcin (OCN) exhibited decreased formation. Moreover, similar degeneration was observed in skeletal muscle physiology with stimulation in muscle atrophy genes atrogin-1, muscle ring finger motif-1 (MuRF-1) and inflammatory markers accompanied with intra-myocellular lipid accumulation. Thus, our results showed that detrimental effect of GC on bone and skeletal muscle is aggravated with HFD, attributed to alteration in bone marrow cell population and skeletal muscle atrophy.

FGF-2 targets sclerostin in bone and myostatin in skeletal muscle to mitigate the deleterious effects of glucocorticoid on musculoskeletal degradation.

AIM: Myokines are associated with regulation of bone and muscle mass. However, limited information is available regarding the impact of myokines on glucocorticoid (GC) mediated adverse effects on the musculoskeletal system. This study investigates the role of myokine fibroblast growth factor-2 (FGF-2) in regulating GC-induced deleterious effects on bone and skeletal muscle. METHODS: Primary osteoblast cells and C2C12 myoblast cell line were treated with FGF-2 and then exposed to dexamethasone (GC). FGF-2 mediated attenuation of the inhibitory effect of GC on osteoblast and myoblast differentiation and muscle atrophy was assessed through quantitative PCR and western blot analysis. Further, FGF-2 was administered subcutaneously to dexamethasone treated mice to collect bone and skeletal muscle tissue for in vivo analysis of bone microarchitecture, mechanical strength, histomorphometry and for histological alterations in treated tissue samples. KEY FINDINGS: FGF-2 abrogated the dexamethasone induced inhibitory effect on osteoblast differentiation by modulating BMP-2 pathway and inhibiting Wnt antagonist sclerostin. Further, dexamethasone induced atrophy in C2C12 cells was mitigated by FGF-2 as evident from down regulation of atrogenes expression. FGF-2 prevented GC-induced impairment of mineral density, biomechanical strength, trabecular bone volume, cortical thickness and bone formation rate in mice. Additionally, skeletal muscle tissue from GC treated mice displayed weak myostatin immunostaining and reduced expression of atrogenes following FGF-2 treatment. SIGNIFICANCE: FGF-2 mitigated GC induced effects through inhibition of sclerostin and myostatin expression in bone and muscle respectively. Taken together, this study exhibited the role of exogenous FGF-2 in sustaining osteoblastogenesis and inhibiting muscle atrophy in presence of glucocorticoid.

MicroRNA-672-5p Identified during Weaning Reverses Osteopenia and Sarcopenia in Ovariectomized Mice.

Post-menopausal condition augments the biological aging process, characterized by multiple metabolic disorders in which bone loss is the most prevalent outcome and usually coupled with sarcopenia. Coexistence of such associated pathogenesis have much worse health outcomes, compared to individuals with osteoporosis only. Pre- and post-natal bone development demands calcium from mother to fetus during pregnancy and lactation leading to a significant maternal skeletal loss. It follows an anabolic phase around weaning during which there is a notable recovery of the maternal skeleton. Here, we have studied the therapeutic effect of microRNA-672-5p identified during weaning when it is predominantly expressed, in ovariectomized mice for both osteopenia and sarcopenia. miR-672-5p induced osteoblast differentiation and mineralization. These actions were mediated through inhibition of Smurf1 with enhanced Runx2 transcriptional activation. In vivo, miR-672-5p significantly increased osteoblastogenesis and mineralization, thus reversing bone loss caused by ovariectomy. It also improved bone-mineral density, load-bearing capacity, and bone quality. Sarcopenia was also alleviated by miR-672-5p, as we observed increased cross-sectional area and Feret's diameter of muscle fibers. We hypothesize that elevated miR-672-5p expression has therapeutic efficacy in estrogen-deficiency-induced osteopenia along with sarcopenia.

Glucose dependent miR-451a expression contributes to parathyroid hormone mediated osteoblast differentiation.

Parathyroid hormone (PTH; amino acid 1-34, known as teriparatide) has reported promoting differentiation and glucose uptake in osteoblasts. However, how PTH regulates glucose metabolism to facilitate osteoblast differentiation is not understood. Here, we report that PTH promotes glucose dependent miR-451a expression which stimulates osteoblast differentiation. In addition to glucose uptake, PTH suppresses AMPK phosphorylation via PI3K-mTOR-AKT axis thereby preventing phosphorylation and inactivation of octamer-binding transcription factor 1 (OCT-1) which has been reported to act on the promoter region of miR-451a. Modulation of AMPK activity controls miR-451a levels in differentiating osteoblasts. Moreover, pharmacological inhibition of PI3K-mTOR-AKT axis suppressed miR-451a via increased AMPK activity. We report that this glucose regulated miRNA is an anabolic target and transfection of miR-451a mimic induces osteoblast differentiation and mineralization in vitro. These actions were mediated through the suppression of Odd-skipped related 1 (Osr1) and activation of Runx2 transcription. When injected in vivo, the miR-451a mimic significantly increased osteoblastogenesis, mineralization, reversed ovariectomy induced bone loss and improved bone strength. Together, these findings suggest that enhanced osteoblast differentiation associated with bone formation in case of PTH therapy is also a consequence of elevated miR-451a levels via glucose regulation. Consequently, this miRNA has the potential to be a therapeutic target for conditions of bone loss.

Benzofuran-pyran hybrids: A new class of potential bone anabolic agents.

Benzofuran moiety is an important pharmacophore showing positive effects on bone health. In the present study, sixteen benzofuran-pyran hybrids were synthesized and were evaluated for their osteogenic effects on primary osteoblast cells isolated from calvaria. Compounds 22 and 24 were found potent in stimulating osteoblast differentiation as assessed by the alkaline phosphatase activity. These compounds were also found to be nontoxic to osteoblast cells as compared to the control cells in MTT assay. Further, Alizarin Red-S staining for visualization of calcium nodules demonstrated compounds 22 and 34 as active in enhancing mineralization in osteoblast cells. Additionally, transcriptional analysis of these compounds on osteoblast cells revealed that compound 22 up-regulated the expression of osteogenic genes RUNX2, BMP-2, COL-1, thus substantiating that compound 22 having two geminal methyl groups in its R3 position is a potent osteogenic agent. Additionally, compound 22 enhanced the ability of bone marrow stromal cells to differentiate towards osteoblast lineage and therefore can be further studied in vivo in bone loss model.

Dietary flavonoid kaempferol inhibits glucocorticoid-induced bone loss by promoting osteoblast survival.

OBJECTIVE: Kaempferol, a dietary flavonoid found in fruits and vegetables, has been reported to reverse osteopenic condition in ovariectomized rats. Because kaempferol is endowed with osteogenic activity, the aim of this study was to determine whether it has a beneficial effect on glucocorticoid (GC)-induced bone loss. METHODS: Adult female rats were divided into four groups as control (vehicle; distilled water), methylprednisolone (MP; 5 mg•kg•d, subcutaneously), MP + kaempferol (5 mg•kg•d, oral), and MP + human parathyroid 1-34 (30 µg/kg, 5 times/wk, subcutaneously) and treated for 4 wk. To study the antagonizing effect of kaempferol on GC-induced inhibition of fracture healing, drill-hole injury was performed on control and GC-treated rats. An oral dose of kaempferol was given for 14 d to observe the effect on callus formation at the site of injury. After treatment, bones were collected for further analysis. RESULTS: GC was associated with a decreased bone mineral density and impaired bone microarchitecture parameters. Consumption of kaempferol induced bone-sparing effects in GC-induced osteopenic condition. Additionally, improved callus formation at site of drill injury in femur diaphysis was observed with kaempferol consumption in animals on GC. Consistent with the in vivo data, kaempferol elicited a higher expression of osteogenic markers in vitro and antagonized the apoptotic effect of dexamethasone on calvarial osteoblasts. CONCLUSION: These results suggested that kaempferol reduced GC-induced bone loss and enhanced bone regeneration at fractured site, thus emphasizing the positive role of flavonoids on bone health.

Spinacia oleracea extract attenuates disease progression and sub-chondral bone changes in monosodium iodoacetate-induced osteoarthritis in rats.

BACKGROUND: Spinacia oleracea is an important dietary vegetable in India and throughout the world and has many beneficial effects. It is cultivated globally. However, its effect on osteoarthritis that mainly targets the cartilage cells remains unknown. In this study we aimed to evaluate the anti-osteoarthritic and chondro-protective effects of SOE on chemically induced osteoarthritis (OA). METHODS: OA was induced by intra-patellar injection of monosodium iodoacetate (MIA) at the knee joint in rats. SOE was then given orally at 250 and 500 mg.kg- 1 day- 1 doses for 28 days to these rats. Anti-osteoarthritic potential of SOE was evaluated by micro-CT, mRNA and protein expression of pro-inflammatory and chondrogenic genes, clinically relevant biomarker's and behavioural experiments. RESULTS: In vitro cell free and cell based assays indicated that SOE acts as a strong anti-oxidant and an anti-inflammatory agent. Histological analysis of knee joints at the end of the experiment by safranin-o and toluidine blue staining established its protective effect. Radiological data corroborated the findings with improvement in the joint space and irregularity of the articular and atrophied femoral condyles and tibial plateau. Micro-CT analysis of sub-chondral bone indicated that SOE had the ability to mitigate OA effects by increasing bone volume to tissue volume (BV/TV) which resulted in decrease of trabecular pattern factor (Tb.Pf) by more than 200%. SOE stimulated chondrogenic marker gene expression with reduction in pro-inflammatory markers. Purified compounds isolated from SOE exhibited increased Sox-9 and Col-II protein expression in articular chondrocytes. Serum and urine analysis indicated that SOE had the potential to down-regulate glutathione S-transferase (GST) activity, clinical markers of osteoarthritis like cartilage oligometric matrix protein (COMP) and CTX-II. Overall, this led to a significant improvement in locomotion and balancing activity in rats as assessed by Open-field and Rota rod test. CONCLUSION: On the basis of in vitro and in vivo experiments performed with Spinacea oleracea extract we can deduce that SOE has the ability to alleviate the MIA induced deleterious effects.

Prevention of articular cartilage degeneration in a rat model of monosodium iodoacetate induced osteoarthritis by oral treatment with Withaferin A.

Withaferin A (WFA), a highly oxygenated withanolide is used for anti-osteoporotic, fracture healing, obesity control as medicine and dietary supplement in Ayurveda and Unani medicine but its potential remains to be investigate for the osteoarthritis studies. In the present study, chondro-protective effects of WFA, under in vitro and in vivo conditions were evaluated. In-vitro pharmacological activity of WFA was tested on rat articular chondrocytes through MTT, DPPH, different staining, FACS and translation studies. In-vivo studies of WFA were evaluated through monosodium iodoacetate (MIA) induced osteoarthritis studies. DPPH assay, alcian blue and toluidine blue staining indicated the chondrogenic potential of WFA. Similarly, WFA enhance chondrogenesis through up-regulation of SOX9 protein. In addition, WFA reduced the ROS generation, mitochondrial depolarization and apoptosis induced by inflammatory cytokines IL-1ß and TNF-α. Furthermore, WFA treatment in MIA treated rats alleviated cartilage erosion and improvement in sub-chondral bone micro-architecture by decrease in Tissue volume (∼32%), and trabecular bone pattern factor (∼28%). Taken together, our study provides convincing evidence for the candidature of WFA (10 mg kg-1 day-1) as a potential agent for the treatment of cartilage degenerative diseases like osteoarthritis.

Benzofuran-dihydropyridine hybrids: A new class of potential bone anabolic agents.

A series of novel benzofuran-dihydropyridine hybrids were designed by molecular hybridization approach and evaluated for bone anabolic activities. Among the screened library, ethyl 4-(7-(sec-butyl)-2-(4-methylbenzoyl)benzofuran-5-yl)-2-methyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate (compound 21) significantly enhanced the ALP production and mineralized nodule formation, which are primary requisites in the process of in vitro osteogenesis. Oral administration of compound 21 at 10 mg.kg-1 day-1 for two weeks led to restoration of trabecular bone microarchitecture in drill hole fracture model by significantly increasing BV/TV and Tb.N. Furthermore, histological and molecular studies showed compound 21 triggering the new bone regeneration in a drill hole defect site by increasing BMP expression. Furthermore, molecular modeling studies were performed to gain insight into the binding approach, which revealed that both benzofuran and dihydropyridine moieties are essential to show similar binding interactions to fit into the active site of BMP2 receptor, an important target of the osteogenic agents. Our results suggest that compound 21 stimulates BMP2 synthesis in osteoblast cells that promotes new bone formation (∼40%) at the fracture site which helps in shorten the healing period.

Detrimental effects of atherogenic and high fat diet on bone and aortic calcification rescued by an isoflavonoid Caviunin ß-d-glucopyranoside.

OBJECTIVE: Atherogenic diet (AD) and high fat diet (HFD) cause deleterious effect on bone micro-architecture and this phenomenon prompts aortic calcification. This study aims to show the effects of Caviunin ß-d-glucopyranoside (CAFG), against bone loss and its associated aortic calcification in presence of AD and HFD challenged diets. METHODS: Five groups of C57BL/6 male mice with 8 animals in each group, comprising of chow, AD, HFD, AD+CAFG and HFD+CAFG were fed with respective diets for 16 weeks. At the end of the treatment period, preventive effects of CAFG on bone tissue were analyzed by assessing the osteogenic potential of bone marrow cells, bone micro-architecture, ability of new bone formation and histomorphometry studies. Aortic calcification was assessed by transcription and translation analysis of osteogenic key markers in aortic tissue and assessment of aortic endothelial function. Plasma lipid profiling was done to assess the effects of diets as its role in both bone loss and aortic calcification. RESULTS: Bone marrow stromal cell (BMSC's) dynamics showed that AD and HFD decreased osteoblast number that led to bone loss, deterioration in bone micro-architecture with up-regulated bone resorptive genes that lead to increase in aortic calcification. CAFG treatment rescued the bone health by modulating BMSC's towards osteogenic lineage. It increased the osteogenic gene expression with simultaneous decrease in osteoclastic genes thus stabilized the receptor activator of nuclear factor-kappa-B ligand/osteoprotegerin ratio that eventually reduced the amount of calcification in aorta. Biochemical studies showed that CAFG reduced the TC, TG and LDL-C content with no marked changes in HDL-C. Moreover, CAFG decreased the osteogenic key markers in the aortic tissue and enhanced endothelial function. CONCLUSION: Overall, this study indicates that CAFG protected against physiologically challenged diet induced bone loss with associated vascular calcification in mice. Moreover, data revealed that atherogenic diet is more detrimental as compared to the excess fatty acid diet to the bone and aorta.

Evaluation of anti-osteoporotic activity of butanolic fraction from Passiflora foetida in ovariectomy-induced bone loss in mice.

OBJECTIVE: In this study, we have evaluated the skeletal effects of butanolic fraction (BF) from Passiflora foetida in an estrogen deficient mice bone loss model. STUDY DESIGN: Skeletal effect of BF was studied in ovariectomized (OVx) female Balb/c mice. BF (50 and 100mg/kg/day dose orally) was given for 8 weeks. Micro-architecture of long bones, biomechanical strength, formations of mineralized nodule by bone marrow osteoprogenitor cells, osteoid formation and bone turnover markers were studied. One way ANOVA was used to test the significance of effects of Passiflora foetida. RESULTS: OVx mice treated with BF represented with better micro-architectural parameters at various anatomical positions, better bone biomechanical strength and more osteoprogenitor cells in the bone marrow compared with OVx group. BF did not exhibit uterine estrogenicity. CONCLUSION: Oral administration of BF at both the doses (50 and 100mg/kg/day) derived from Passiflora Foetida, was found to afford anti-osteoporotic effect under estrogen deficiency by likely stimulation of osteoblast function and inhibition of osteoclast function.

Dried and free flowing granules of Spinacia oleracea accelerate bone regeneration and alleviate postmenopausal osteoporosis.

OBJECTIVE: The aim of this study was to demonstrate the efficacy of extract derived from Spinacia oleracea extract (SOE) in reversing bone loss induced by ovariectomy and bone healing properties in a drill-hole fracture model in rats. METHODS: SOE was administered orally for 12 weeks in adult ovariectomized Sprague Dawley rats after inducing osteopenic condition. Bone micro-architecture, expressions of osteogenic and resorptive gene markers, biomechanical strength, new bone formation, and bone turnover markers were studied. Uterine histomorphometry was used to assess estrogenicity. Bone regeneration potential of SOE was assessed in a drill-hole fracture model. Fracture healing was assessed by calcein intensity and micro-CT analysis of callus at fracture region. RESULTS: SOE prevented ovariectomy-induced bone loss as evident from 122% increase in bone volume/tissue volume (BV/TV) and 29% decline in Tb.Sp in femoral trabecular micro-architecture. This was corroborated by the more than twofold stimulation in the expression of osteogenic genes runt-related transcription factor 2, osterix, osteocalcin, bone morphogenetic protein 2, collagen-1. Furthermore in the fracture healing model, we observed a 25% increase in BV/TV and enhancement in calcein intensity at the fractured site. The extract when converted into dried deliverable Spinaceae oleracea granule (SOG) form accelerated bone regeneration at fracture site, which was more efficient as evident by a 39% increase in BV/TV. Transforming SOE into dried granules facilitated prolonged systemic availability, thus providing enhanced activity for a period of 14 days. CONCLUSIONS: SOE treatment effectively prevents ovariectomy-induced bone loss and stimulated fracture healing in adult rats. The dried granular form of the extract of Spinaceae oleracea was effective in fracture healing at the same dose.

Genetically engineered flavonol enriched tomato fruit modulates chondrogenesis to increase bone length in growing animals.

Externally visible body and longitudinal bone growth is a result of proliferation of chondrocytes. In growth disorder, there is delay in the age associated increase in height. The present study evaluates the effect of extract from transgenic tomato fruit expressing AtMYB12 transcription factor on bone health including longitudinal growth. Constitutive expression of AtMYB12 in tomato led to a significantly enhanced biosynthesis of flavonoids in general and the flavonol biosynthesis in particular. Pre-pubertal ovary intact BALB/c mice received daily oral administration of vehicle and ethanolic extract of wild type (WT-TOM) and transgenic AtMYB12-tomato (MYB12-TOM) fruits for six weeks. Animal fed with MYB12-TOM showed no inflammation in hepatic tissues and normal sinusoidal Kupffer cell morphology. MYB12-TOM extract significantly increased tibial and femoral growth and subsequently improved the bone length as compared to vehicle and WT-TOM. Histomorphometry exhibited significantly wider distal femoral and proximal tibial growth plate, increased number and size of hypertrophic chondrocytes in MYB12-TOM which corroborated with micro-CT and expression of BMP-2 and COL-10, marker genes for hypertrophic cells. We conclude that metabolic reprogramming of tomato by AtMYB12 has the potential to improve longitudinal bone growth thus helping in achievement of greater peak bone mass during adolescence.