Stimulation of liver IGF-1 expression promotes peak bone mass achievement in growing rats: a study with pomegranate seed oil

Dysregulation of histone modifications in bone marrow mesenchymal stem cells during skeletal ageing: roles and therapeutic prospects

Age-associated bone diseases such as osteoporosis (OP) are common in the elderly due to skeletal ageing. The process of skeletal ageing can be accelerated by reduced proliferation and osteogenesis of bone marrow mesenchymal stem cells (BM-MSCs). Senescence of BM-MSCs is a main driver of age-associated bone diseases, and the fate of BM-MSCs is tightly regulated by histone modifications, such as methylation and acetylation. Dysregulation of histone modifications in BM-MSCs may activate the genes related to the pathogenesis of skeletal ageing and age-associated bone diseases. Here we summarize the histone methylation and acetylation marks and their regulatory enzymes that affect BM-MSC self-renewal, differentiation and senescence. This review not only describes the critical roles of histone marks in modulating BM-MSC functions, but also underlines the potential of epigenetic enzymes as targets for treating age-associated bone diseases. In the future, more effective therapeutic approaches based on these epigenetic targets will be developed and will benefit elderly individuals with bone diseases, such as OP.

Sesamol improves bone mass in ovary intact growing and adult rats but accelerates bone deterioration in the ovariectomized rats

Sesamol, an active component in sesame seeds, is known for its health benefits. However, its effect on bone metabolism remains unexplored. The present study aims to investigate the effect of sesamol on growing, adult and osteoporotic skeleton and its mechanism of action. Sesamol at various doses were administered orally to growing, ovariectomized, and ovary-intact rats. Alterations in bone parameters were examined using micro-CT and histological studies. Western blot and mRNA expression from long bones were performed. We further evaluated the effect of sesamol on osteoblast and osteoclast function and its mode of action in the cell culture system. These data showed that sesamol was able to promote peak bone mass in growing rats. However, sesamol had the opposite effect in ovariectomized rats, evident from gross deterioration of trabecular and cortical microarchitecture. Concurrently, it improved the bone mass in adult rats. In vitro results revealed that sesamol enhances the bone formation by stimulating osteoblast differentiation through MAPK, AKT, and BMP-2 signaling. In contrast, it enhances osteoclast differentiation and expression of osteoclast-specific genes in osteoclast differentiation medium. Interestingly, in presence of estrogen, the effect reversed and sesamol decreased osteoclast differentiation, in vitro. Sesamol improves bone microarchitecture in growing and ovary-intact rats, whereas it enhances the bone deterioration in ovariectomized rats. While sesamol promotes bone formation, its opposing effect on the skeleton can be attributed to its dual effect on osteoclastogenesis in presence and absence of estrogen. These findings in the preclinical context suggests a special attention towards the detrimental effect of sesamol in postmenopausal women.

Maternal omega-3 LC-PUFA supplementation programs an improved bone mass in the offspring with a more pronounced effect in females than males at adulthood

Early balanced nutrition is vital in achieving optimal skeletal mass and its maintenance. Although a lower omega-6 (n-6): omega-3 (n-3) long-chain polyunsaturated fatty acid (LC-PUFA) ratio is strongly linked with bone health, its maternal effect in the programming of the offspring's skeleton remains to be elucidated. Plugged C57BL/6 mice were fed either n-3 LC-PUFA Enriched Diet (LED) or a control diet (C) throughout their gestation and lactation. Offspring born to both the groups were weaned onto C till 6, 12, and 24 weeks of their age. Offspring's skeleton metabolism and serum fatty acid composition was studied. In humans, seventy-five mother-female newborns pairs from term gestation were tested for their maternal LC-PUFA status relationships to venous cord blood bone biomarkers. Offspring of maternal LED supplemented mice exhibited a superior bone phenotype over C, more prominent in females than males. A lower serum n-6/n-3 LC-PUFA in the LED group offspring was strongly associated with blood biomarkers of bone metabolism. Sexual dimorphism evidenced had a strong correlation between offspring's LC-PUFA levels and bone turnover markers in serum. A higher potential for osteoblastic differentiation in both LED offspring genders and reduced osteoclastogenesis in females was cell-autonomous effect. The human cross-sectional study also showed a positive correlation between maternal n-3 PUFA and cord blood markers of bone formation in female newborns at birth. Maternal dietary n-6/ n-3 fat quality determines offspring's bone growth and development. Our data suggest that the skeleton of female offspring is likely to be more sensitive to this early exposure.

The Nutraceutical Genistein-Lycopene Combination Improves Bone Damage Induced by Glucocorticoids by Stimulating the Osteoblast Formation Process

Chronic glucocorticoid (GC) therapy is the most common cause of iatrogenic osteoporosis and represents an important risk factor for osteoporosis and bone fractures. New therapeutic approaches are required in order to treat osteoporosis and reduce the side effects related to the use of anti-osteoporotic drugs. In this context, previous studies reported the efficacy of some isoflavones and carotenoids, such as lycopene and genistein, on the reduction of the risk of fracture related to osteoporosis. The aim of this study was to investigate the effects of a combined oral treatment, consisting of genistein and lycopene, in an experimental model of glucocorticoid-induced osteoporosis (GIO). GIO was induced by subcutaneous injection of methylprednisolone (MP, 30 mg/kg) for 60 days, whereas the control group (Sham) received saline solution only. Following induction, MP animals randomly were assigned to receive alendronate, genistein, lycopene, or the association of genistein and lycopene or saline solution for additional 60 days together with MP. Femurs obtained from the Sham group were used for osteoblasts extraction; they were then incubated with dexamethasone (DEX) for 24 h to be then treated with lycopene or genistein or the association of lycopene and genistein for an additional 24 h. Treatments with lycopene and genistein restored the impaired mineralization of cells observed following DEX treatment and stimulated osteoblast differentiation by increasing the depressed expression of bALP and RUNX2 (p < 0.0001). Wnt5a, β-catenin, and Nrf-2 expression were significantly increased following genistein and lycopene treatment (p < 0.0001), thus confirming their antioxidant activity as well as their ability in stimulating osteoblast function, mostly when genistein and lycopene were used in association. The combined treatment of genistein and lycopene improved the bone damage induced by glucocorticoids and significantly restored the normal architecture of bones as well as adequate interconnectivity of bone trabeculae, thus increasing bone mineral density parameters. The obtained data demonstrated that genistein and lycopene but in particular their association might prevent GC’s adverse effects, thus stimulating bone formation and reducing bone resorption, improving bone structure and microarchitecture, through different molecular pathways, such as the Wnt/β-catenin and the Nrf-2 signaling.

Maternal high cholesterol diet negatively programs offspring bone development and downregulates hedgehog signaling in osteoblasts

Cholesterol is one of the essential intrauterine factors required for fetal growth and development. Maternal high cholesterol levels are known to be detrimental for offspring health. However, its long-term effect on offspring skeletal development remains to be elucidated. We performed our studies in two strains of mice (C57BL6/J and Swiss Albino) and human subjects (65 mother–female newborn dyads) to understand the regulation of offspring skeletal growth by maternal high cholesterol. We found that mice offspring from high-cholesterol-fed dams had low birth weight, smaller body length, and delayed skeletal ossification at the E18.5 embryonic stage. Moreover, we observed that the offspring did not recover from the reduced skeletal mass and exhibited a low bone mass phenotype throughout their life. We attributed this effect to reduced osteoblast cell activity with a concomitant increase in the osteoclast cell population. Our investigation of the molecular mechanism revealed that offspring from high-cholesterol-fed dams had a decrease in the expression of ligands and proteins involved in hedgehog signaling. Further, our cross-sectional study of human subjects showed a significant inverse correlation between maternal blood cholesterol levels and cord blood bone formation markers. Moreover, the bone formation markers were significantly lower in the female newborns of hypercholesterolemic mothers compared with mothers with normal cholesterolemic levels. Together, our results suggest that maternal high cholesterol levels deleteriously program offspring bone mass and bone quality and downregulate the hedgehog signaling pathway in their osteoblasts.

Ethanolic extract from the root and leaf of Sida cordifolia promotes osteoblast activity and prevents ovariectomy-induced bone loss in mice

BACKGROUND

Sida cordifolia is traditionally found in the Indian system of medicine, well known for its medicinal and nutritional properties among local natives.

PURPOSE

The present study aims to investigate the osteo-protective effect of root and leaf ethanolic extract of S. cordifolia (RE and LE) and its underlying mechanism.

METHODS

Antioxidant activity of RE and LE was assessed. Total phenolic and flavonoid content were determined. HPLC profiling of RE and LE was performed to examine the polyphenol content. The effect of RE and LE on osteoblast cells proliferation, differentiation, mineralization, and expression of the protein associated with osteogenesis were evaluated using primary calvarial osteoblast culture. Skeletal effects of RE and LE of S. cordifolia were investigated in C57BL/6J ovariectomized mice. Micro CT was employed to evaluate the alteration in trabecular and cortical bone microarchitecture. Histology studies were performed on the isolated vertebra. qPCR analysis and western blotting was done to check the key bone markers.

RESULTS

RE and LE showed a potent antioxidant activity, owing to a notable polyphenol content. Both RE and LE did not alter the cell viability but significantly increased the osteoblast cell proliferation, differentiation, and mineralization. Moreover, they enhanced the mRNA expression of osteogenic genes. Both RE and LE stimulated the activation of ERK, AKT, and CREB. Both RE and LE had no direct effect on osteoclastogenesis, but both increased Opg/Rankl ratio expression in osteoblast cells. Both RE and LE at 750 mg/kg/day significantly improved the trabecular and cortical microarchitecture of femur and tibia by increasing bone mineral density, bone volume fraction, trabecular number, and trabecular thickness, and decreasing trabecular separation and structural model index in ovariectomized mice. Furthermore, vertebral histology of lumbar vertebrae revealed that RE and LE significantly enhance the vertebral bone mass and exert osteo-protective effects by stimulating osteoblast function and inhibiting osteoclast function.

CONCLUSION

In conclusion, both RE and LE stimulate osteoblast differentiation through activating ERK, AKT, and CREB signalling pathways and indirectly inhibits osteoclast differentiation. RE and LE also improve the trabecular and cortical microarchitecture of ovariectomized mice, making it a promising agent to prevent postmenopausal bone loss.

Role of histone modification in the occurrence and development of osteoporosis

Osteoporosis is a systemic degenerative bone disease characterized by low bone mass and damage to bone microarchitecture, which increases bone fragility and susceptibility to fracture. The risk of osteoporosis increases with age; with the aging of the global population, osteoporosis is becoming more prevalent, adding to the societal healthcare burden. Histone modifications such as methylation, acetylation, ubiquitination, and ADP-ribosylation are closely related to the occurrence and development of osteoporosis. This article reviews recent studies on the role of histone modifications in osteoporosis. The existing evidence indicates that therapeutic targeting of these modifications to promote osteogenic differentiation and bone formation may be an effective treatment for this disease.

Anatase and Rutile TiO2 Nanoparticles Lead Effective Bone Damage in Young Rat Model via the IGF-1 Signaling Pathway

PURPOSE

To evaluate the effects of anatase and rutile TiO2 nanoparticles (NPs) on the growth and development of bones in young rats and explore their possible mechanisms.

METHODS

Three-week-old male rats were orally administered anatase TiO2 NPs and rutile TiO2 NPs for 28 days. The indicators of rat growth and development, liver function, bone metabolism, and insulin-like growth factor-1 (IGF-1) levels were evaluated. Micro-computed tomography (micro-CT) and immunohistochemistry were used to evaluate the tibia.

RESULTS

No significant differences were observed among growth and development indicators in young rats. Significant differences were found in IGF-1 levels, phosphorus levels, and liver function. Micro-CT revealed osteoporosis in the bones. The micro-CT data supported the same result. Bone immunohistochemistry results showed that the expression of osteoprotegerin (OPG) was decreased and the expression of receptor activator of nuclear factor-κB ligand (RANKL) and cathepsin K (CTSK) was increased.

CONCLUSION

This study demonstrated that TiO2 NPs can damage bones via the IGF-1/OPG/RANKL/CTSK pathway in young rats. Furthermore, rutile TiO2 NPs damaged the bones more seriously than anatase TiO2 NPs.

Maternal high protein-diet programs impairment of offspring's bone mass through miR-24-1-5p mediated targeting of SMAD5 in osteoblasts

Maternal nutrition is crucial for the offspring's skeleton development and the onset of osteoporosis later in life. While maternal low protein diet has been shown to regulate bone mass negatively, the effect of a high protein diet (HP) remains unexplored. Here, we found that C57BL/6 mice fed with HP delivered offspring with decreased skeletal mineralization at birth and reduced bone mass throughout their life due to a decline in their osteoblast maturation. A small RNA sequencing study revealed that miR-24-1-5p was highly upregulated in HP group osteoblasts. Target prediction and validation studies identified SMAD-5 as a direct target of miR-24-1-5p. Furthermore, mimic and inhibitor studies showed a negative correlation between miR-24-1-5p expression and osteoblast function. Moreover, ex vivo inhibition of miR-24-1-5p reversed the reduced maturation and SMAD-5 expression in the HP group osteoblasts. Together, we show that maternal HP diminishes the bone mass of the offspring through miR-24-1-5p.

Oral Exposure to ZnO Nanoparticles Disrupt the Structure of Bone in Young Rats via the OPG/RANK/RANKL/IGF-1 Pathway

Purpose

To evaluate the effects of ZnO NPs on bone growth in rats and explore the possible mechanisms of action.

Materials and Methods

Three-week-old male rats received ultrapure water or 68, 203, and 610 mg/kg zinc oxide nanoparticles (ZnO NPs) for 28 days, orally.

Results

The high-dosage groups caused significant differences in weight growth rate, body length, and tibia length (P<0.05), all decreasing with increased ZnO NP dosage. There were no significant differences in body mass index (BMI) (P>0.05). The zinc concentration in liver and bone tissue increased significantly with increased ZnO NP dosage (P<0.05). Clearly increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were observed in the 610 mg/kg ZnO NP group (P>0.05), whereas alkaline phosphatase (ALP) increased in the 610 mg/kg ZnO NP group (P<0.05). Significant differences in insulin-like growth factor type 1 (IGF-1) levels and a decrease in calcium (Ca) levels were observed in 203 and 610 mg/kg ZnO NP groups (P<0.05). Phosphorus (P) levels increased and the Ca/P ratio decreased in the 610 mg/kg ZnO NP group (P<0.05). Micro-computed tomography (micro-CT) of the tibia demonstrated signs of osteoporosis, such as decreased bone density, little trabecular bone structure and reduced cortical bone thickness. Micro-CT data further demonstrated significantly decreased bone mineral density (BMD), trabecular number (Tb.N), and relative bone volume (BV/TV) with increasing dosage of ZnO NPs. Osteoprotegerin (OPG) expression and the ratio of OPG to receptor activator of nuclear factor-κB ligand (RANKL) were statistically lower in the 610 mg/kg ZnO NP group (P<0.05), whereas RANKL expression did not change significantly (P>0.05).

Conclusion

We infer that ZnO NPs affect bone growth in young rats directly or indirectly by altering IGF-1 levels. Overall, the results indicate that ZnO NPs promote osteoclast activity and increase bone loss through the OPG/RANK/RANKL/IGF-1 pathway.

Hyperglycemia impairs osteoblast cell migration and chemotaxis due to a decrease in mitochondrial biogenesis

Diabetes is associated with an increase in skeletal fragility and risk of fracture. However, the underlying mechanism for the same is not well understood. Specifically, the results from osteoblast cell culture studies are ambiguous due to contradicting reports. The use of supraphysiological concentrations in these studies, unachievable in vivo, might be the reason for the same. Therefore, here, we studied the effect of physiologically relevant levels of high glucose during diabetes (11.1 mM) on MC3T3-E1 osteoblast cell functions. The results showed that high glucose exposure to osteoblast cells increases their differentiation and mineralization without any effect on the proliferation. However, high glucose decreases their migratory potential and chemotaxis with a decrease in the associated cell signaling. Notably, this decrease in cell migration in high glucose conditions was accompanied by aberrant localization of Dynamin 2 in osteoblast cells. Besides, high glucose also caused a shift in mitochondrial dynamics towards the appearance of more fused and lesser fragmented mitochondria, with a concomitant decrease in the expression of DRP1, suggesting decreased mitochondrial biogenesis. In conclusion, here we are reporting for the first time that hyperglycemia causes a reduction in osteoblast cell migration and chemotaxis. This decrease might lead to an inefficient movement of osteoblasts to the erosion site resulting in uneven mineralization and skeletal fragility found in type 2 diabetes patients, in spite of having normal bone mineral density (BMD).

Rheological, physico-sensory and antioxidant properties of punicic acid rich wheat bread

Punicic acid (PA), a predominant fatty acid (85%) in pomegranate seeds, also called as an ω-5 fatty acid, is known to render various health beneficial effects to humans. The objective of this study was to prepare and observe the effect of replacement of wheat flour with 5-12.5% punicic acid rich pomegranate seed powder (PSP, 9XXX fraction) on rheological, physico-sensory and antioxidant properties of bread. The increasing amount of PSP caused decrease in farinograph water absorption capacity, dough stability; amylograph peak viscosity; bread volume and overall quality score, whereas crumb hardness was increased. The combination of additives (CA) showed significant improvement in dough strength, texture and quality of bread with 10% PSP. The total polyphenol content (TPP) and radical scavenging activity (RSA) increased by 10- to 30-fold while PA was increased to 60-fold when compared to control. The recovery of PA from bread samples was in range of 45-60% and further increased by the addition of CA (65%). Hence, 10% PSP bread having 60% recovery of PA can be successfully considered for formulations without altering the rheological and sensory quality of bread. These results reveal that PA rich PSP prepared from a fruit industry by-product can be utilized for preparing antioxidant rich functional bread which also helps in overall improvement of bone health.

Chlorpyrifos Exposure Induces Parkinsonian Symptoms and Associated Bone Loss in Adult Swiss Albino Mice

Prenatal and early life exposure of chlorpyrifos (CPF), a widely used pesticide, is known to cause neuronal deficits and Parkinson's disease (PD). However, data about the effect of its exposure at adult stages on PD-like symptoms and associated bone loss is scanty. In the present study, we investigated the impact of CPF on the behavioral alterations seen in PD using adult Swiss albino mice. PD is often associated with bone loss. Hence, skeletal changes were also evaluated using micro-computed tomography and histology. MPTP was used as a positive control. Cell culture studies using MC3T3E-1, SHSY5Y, and primary osteoclast cultures were done to understand the cellular mechanism for the behavioral and skeletal changes. Our results showed that CPF treatment leads to PD-like symptoms due to the loss of dopaminergic neurons. Moreover, CPF has a deleterious effect on the trabecular bone through both indirect changes in circulating factors and direct stimulation of multinucleate osteoclast cell formation. The impact on the bone mass was even stronger than MPTP. In conclusion, this is the first report demonstrating that CPF induces parkinsonian features in adult Swiss albino mice and it is accompanied by loss of trabecular bone.

Hepatic Osteodystrophy-Molecular Mechanisms Proposed to Favor Its Development

Almost all patients with chronic liver diseases (CLD) show altered bone metabolism. Depending on the etiology, this manifests in a severe osteoporosis in up to 75% of the affected patients. Due to high prevalence, the generic term hepatic osteodystrophy (HOD) evolved, describing altered bone metabolism, decreased bone mineral density, and deterioration of bone structure in patients with CLD. Once developed, HOD is difficult to treat and increases the risk of fragility fractures. Existing fractures affect the quality of life and, more importantly, long-term prognosis of these patients, which presents with increased mortality. Thus, special care is required to support the healing process. However, for early diagnosis (reduce fracture risk) and development of adequate treatment strategies (support healing of existing fractures), it is essential to understand the underlying mechanisms that link disturbed liver function with this bone phenotype. In the present review, we summarize proposed molecular mechanisms favoring the development of HOD and compromising the healing of associated fractures, including alterations in vitamin D metabolism and action, disbalances in transforming growth factor beta (TGF-β) and bone morphogenetic protein (BMP) signaling with histone deacetylases (HDACs) as secondary regulators, as well as alterations in the receptor activator of nuclear factor kappa B ligand (RANKL)–osteoprotegerin (OPG) system mediated by sclerostin. Based on these mechanisms, we give an overview on the limitations of early diagnosis of HOD with established serum markers.

Bone loss in MPTP mouse model of Parkinson's disease is triggered by decreased osteoblastogenesis and increased osteoclastogenesis

Bone loss is a non-motor symptom of Parkinson's disease (PD). It is unclear whether a patient's immobility or the endocrine changes in the body causes bone deterioration. To address this issue, we used an animal model of the disease where Swiss albino mice were injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on day 1 and were left untreated for eight weeks. Behavioral phenotypes of PD, and striatal acetylcholinesterase and dopamine levels were measured. Cortical and trabecular bones were assessed by μ-CT and histology. Gene expression studies were done through quantitative real-time PCR. Effect of MPP+ and MPTP-treated mice serum on MC3T3E-1, SH-SY5Y, and primary osteoclast cells were also studied. Our results demonstrated that MPTP treatment leads to PD like symptoms. It shows a loss of trabecular bone mass and quality by decreasing osteoblast and increased osteoclast number and activity. This effect was accompanied by reduced osteogenic and elevated osteoclastogenic genes expression. While MPP+ had a cytotoxic effect on dopaminergic neurons, it did not affect bone cells. However, ex-vivo treatment of the serum from MPTP-treated mice decreased osteoblastogenesis and increased osteoclastogenesis in cell culture. In conclusion, our study suggests that MPTP-induced parkinsonian features in mice leads to trabecular bone loss by decreased bone formation and increased bone resorption due to changes in the serum circulating factors. This study characterizes the microarchitectural and cellular changes in the skeleton of a mouse model of PD that can be further utilized to investigate therapeutic avenues to treat bone loss in PD patients.