Association between IGF-1 polymorphisms and risk of osteoporosis in Chinese population: a meta-analysis

Global and Conditional Disruption of the Igf-I Gene in Osteoblasts and/or Chondrocytes Unveils Epiphyseal and Metaphyseal Bone-Specific Effects of IGF-I in Bone

To evaluate the relative importance of IGF-I expression in various cell types for endochondral ossification, we quantified the trabecular bone at the secondary spongiosa and epiphysis of the distal femur in 8-12-week-old male mice with a global knockout of the Igf-I gene, as well as the conditional deletion of Igf-I in osteoblasts, chondrocytes, and osteoblasts/chondrocytes and their corresponding wild-type control littermates. The osteoblast-, chondrocyte-, and osteoblast/chondrocyte-specific Igf-I conditional knockout mice were generated by crossing Igf-I floxed mice with Cre transgenic mice in which Cre expression is under the control of either the Col1α2 or Col2α1 promoter. We found that the global disruption of Igf-I resulted in 80% and 70% reductions in bone size, defined as total volume, at the secondary spongiosa and epiphysis of the distal femur, respectively. The abrogation of Igf-I in Col1α2-producing osteoblasts but not Col2α1-producing chondrocytes decreased bone size by 25% at both the secondary spongiosa and epiphysis. In comparison, the deletion of the Igf-I globally or specifically in osteoblasts or chondrocytes reduced trabecular bone mass by 25%. In contrast, the universal deletion of Igf-I in all cells, but not the conditional disruption of Igf-I in osteoblasts and/or chondrocytes reduced trabecular bone mass in the epiphysis. The reduced trabecular bone mass at the secondary spongiosa in osteoblast- and/or chondrocyte-specific Igf-I conditional knockout mice is caused by the reduced trabecular number and increased trabecular separation. Immunohistochemistry studies found that the expression levels of chondrocyte (COL10, MMP13) and osteoblast (BSP) markers were less in the secondary spongiosa and the epiphyses in the global Igf-I deletion mice. Our data indicate that local and endocrine Igf-I act pleiotropically and in a cell type- and bone compartment-dependent manner in bone.

A unified framework of cell population dynamics and mechanical stimulus using a discrete approach in bone remodelling

Multiphysics models have become a key tool in understanding the way different phenomenon are related in bone remodeling and various approaches have been proposed, yet, to the best of the author's knowledge there is no model able to link a cell population model with a mechanical stimulus model using a discrete approach, which allows for an easy implementation. This article couples two classical models, the cell population model from Komarova and the Nackenhorst model in a 2D domain, where correlations between the mechanical loading and the cell population dynamics can be established, furthermore the effect of different paracrine and autocrine regulators is seen on the overall density of a portion of trabecular bone. A discretization is performed using frame 1D finite elements, representing the trabecular structure. The Nackenhorst model is implemented by using the finite element method to calculate the strain energy as the main mechanical stimulus that determines the bone mass density evolution in time. This density is normalized to be added to the bone mass percentage proposed by the Komarova model, where coupling terms have been added as well that guarantee a stable response. In the simulations, the equations were solved employing the finite element method with a user subroutine implemented in ABAQUS (2017) and by applying a direct formulation. The methodology presented can model the cell dynamics occurring in bone remodelling in accordance with the asynchronous nature of this process, yet allowing to differentiate zones with higher density, the main trabecular groups are obtained for the proximal femur. Finally, the model is tested in pathological cases, such as osteoporosis and osteopetrosis, yielding results similar to the pathology behavior. Furthermore, the discrete modelling technique is shown to be of use in this particular application.

A case-control study coupling with meta-analysis elaborates decisive association between IGF-1 rs35767 and osteoporosis in Asian postmenopausal females

BACKGROUND

Osteoporosis (OP) is prevalent in postmenopausal women. Several studies investigated the association between IGF-1 polymorphisms and OP among postmenopausal females with conflicting outcomes.

OBJECTIVE

To investigate whether the IGF-1 (rs35767, rs2288377, rs5742612) were associated with OP in postmenopausal females.

METHODS

In case-control study, 95 OP cases and 222 healthy controls were recruited between March 2015 and July 2019. OP was diagnosed based on WHO criteria for diagnosis of OP as T score of bone mineral density (BMD) ≤-2.5; normal, as T score of BMD ≥-1. IGF-1 SNPs were genotyped by iPLEX Gold SNP genotyping. To be solid, related studies from PubMed, Embase, Cochrane, Web of science, and previous meta-analysis up until November 2020, along with our case-control study, were incorporated into a meta-analysis with criteria of significance using odds ratios (ORs) with corresponding 95% confidence intervals (CI) to evaluate risk factor of SNPs on OP. TSA was used to estimate the sample sizes required to achieve a conclusion.

RESULTS

In dominant model of our case-control study, we found nonsignificant association of rs35767 [Adj-OR: 0.95 (95% CI: 0.56-1.60)], rs2288377 [Adj-OR: 1.15 (95% CI: 0.67-1.97)], and rs5742612 [Adj-OR: 1.07 (95% CI: 0.62-1.83)] with OP in postmenopausal females. However, integration of our case-control study and 3 published studies, rs35767 [OR: 1.24 (95% CI: 1.05-1.47)] showed a conclusively risk association with OP in postmenopausal females judged by TSA with 2267 Asians.

CONCLUSIONS

This study demonstrates a crucial sample to conclude that IGF-1 rs35767 is significantly associated with OP in postmenopausal women.

Long Non-Coding RNA Metastasis Associated Lung Adenocarcinoma Transcript 1 (LncRNA MALAT1) Shuttling Through Exosome from Bone Marrow Mesenchymal Stem Cell (BMSC) Regulates the Differentiation of Osteoblast in Osteoporosis Rats

This study assesses the effect of LncRNA MALAT1 on osteoblast differentiation in OP rats. The BMSC were transfected with LncRNA MALAT1. The OP rats’ model was established and then assigned into NC set, OP set, BMSC set, BMSCs/LncRNA-NC set and BMSCs/LncRNA MALAT1 set followed by analysis of LncRNA MALAT1, microRNA-34 and cSATB2 expression by RT-PCR, and Bax, Caspase-3 and ALP level in exosome by Western Blot assy. The protein expression of Bax and Caspase-3 in OP set was significantly increased compared with NC set but reduced in BMSCs/LncRNA MALAT1 set without significant differences between BMSC set and BMSC/NC set. There was orderly array of collagenous fiber in lamellar bone of NC set. The quantity of bone lacuna was moderate with orderly array of bone trabecula. There was disorderly array of collagenous fiber in lamellar bone of model set. There were a large number of distribution of osteoblast in the breakdown area with the dissolution of periosteum. The protein level of Bax and Caspase-3 was reduced by LncRNA MALAT1 from BMSC and the level of ALP, microRNA-34 and cSATB2 in the differentiation of osteoblast was increased, thereby promoting the differentiation of osteoblast.

Correlation of hemoglobin with osteoporosis in elderly Chinese population: A cross-sectional study

Introduction

In the elder population, both low hemoglobin (Hb)/anemia and osteoporosis (OP) are highly prevalent. However, the relationship between Hb and OP is still poorly understood. This study was to evaluate the correlation between Hb and OP in Chinese elderly population.

Methods

One thousand and sisty-eight individuals aged 55-85 years were enrolled into this cross-sectional study during June 2019-November 2019. Data on the demographics and clinical characteristics were recorded. Detections of complete blood count, liver/kidney function, glucose metabolism and lipid profile, and thoracolumbar X-ray were performed, and bone mineral density (BMD) at lumbar spine 1-4, femur neck, and total hip was measured by dual-energy X-ray absorptiometry (DXA). Univariate and multivariate linear regression analyses were employed to evaluate the correlation between Hb with BMD T-score. Logistic regression analysis was performed to access the correlation between different Hb levels and the odds ratio (OR) for OP.

Results

Compared with non-OP group, OP patients had lower level of Hb. Univariate linear regression analysis indicated Hb level was positively related to the BMD of lumbar spine 1-4, femur neck and total hip, and this relationship remained after adjusting confounding variables [gender, age, body mass index (BMI), diabetes mellitus (DM) and morphological vertebral fracture]. Logistic regression analysis showed the ORs for OP decreased with the increase of Hb. Compared with the subjects with the lowest quartile of Hb, the OR for OP in the highest quartile group was 0.60 (0.41-0.89) after adjusting for gender, age and BMI, and the OR for OP was 0.62 (0.41-0.92) after further adjustment for gender, age, BMI, DM, and lipid indexes.

Discussion

In conclusion, Lower Hb level is related to lower BMD in the elderly population. However, whether Hb level could be used to predict the risk of OP needs to be further determined in more longitudinal clinical studies.

Sarcopenia and bone health: new acquisitions for a firm liaison

Osteosarcopenia (OS) is a newly defined condition represented by the simultaneous presence of osteopenia/osteoporosis and sarcopenia, the main age-related diseases. The simultaneous coexistence of the two phenotypes derives from the close connection of the main target tissues involved in their pathogenesis: bone and muscle. These two actors constitute the bone-muscle unit, which communicates through a biochemical and mechanical crosstalk which involves multiple factors. Altered pattern of molecular pathways leads to an impairment of both the functionality of the tissue itself and the communication with the complementary tissue, composing the OS pathogenesis. Recent advances in the genetics field have provided the opportunity to delve deeper into the complex biological and molecular mechanisms underlying OS. Unfortunately, there are still many gaps in our understanding of these pathways, but it has proven essential to apply strategies such as exercise and nutritional intervention to counteract OS. New therapeutic strategies that simultaneously target bone and muscle tissue are limited, but recently new targets for the development of dual-action drug therapies have been identified. This narrative review aims to provide an overview of the latest scientific evidence associated with OS, a complex disorder that will pave the way for future research aimed at understanding the bone-muscle-associated pathogenetic mechanisms.

Genetics and Epigenetics of Bone Remodeling and Metabolic Bone Diseases

Bone metabolism consists of a balance between bone formation and bone resorption, which is mediated by osteoblast and osteoclast activity, respectively. In order to ensure bone plasticity, the bone remodeling process needs to function properly. Mesenchymal stem cells differentiate into the osteoblast lineage by activating different signaling pathways, including transforming growth factor β (TGF-β)/bone morphogenic protein (BMP) and the Wingless/Int-1 (Wnt)/β-catenin pathways. Recent data indicate that bone remodeling processes are also epigenetically regulated by DNA methylation, histone post-translational modifications, and non-coding RNA expressions, such as micro-RNAs, long non-coding RNAs, and circular RNAs. Mutations and dysfunctions in pathways regulating the osteoblast differentiation might influence the bone remodeling process, ultimately leading to a large variety of metabolic bone diseases. In this review, we aim to summarize and describe the genetics and epigenetics of the bone remodeling process. Moreover, the current findings behind the genetics of metabolic bone diseases are also reported.

Associations between WNT signaling pathway-related gene polymorphisms and risks of osteoporosis development in Chinese postmenopausal women: a case-control study

BACKGROUND

The WNT signaling pathway is involved in the regulation of bone homeostasis, and the effect of WNT signaling pathway-related gene (WNT16 and LRP5) polymorphisms on osteoporosis risk among Chinese postmenopausal women is still unknown. Hence, we performed a case-control study to assess the association of WNT signaling pathway-related gene polymorphisms and osteoporosis risk.

METHODS

A total of 1026 women (515 osteoporosis patients and 511 controls) of postmenopausal age who were randomly sampled from Xi'an 630 Hospital (Shaanxi Province, China) were involved in this study. Seven genetic polymorphisms in WNT16 (rs3779381, rs3801387, rs917727 and rs7776725) and LRP5 (rs2291467, rs11228240 and rs12272917) were selected and genotyped using the Agena MassARRAY iPLEX system. The association of the genetic polymorphisms and osteoporosis risk was assessed by odds ratios and 95% confidence intervals. The multifactor dimensionality reduction (MDR) method was conducted to analyze single nucleotide polymorphism (SNP)-SNP interaction.

RESULTS

We found that LRP5 polymorphisms (rs2291467, rs11228240 and rs12272917) were significantly associated with a decreased risk of osteoporosis in homozygote, recessive and additive models (p < 0.05). Stratification analysis showed that LRP5 polymorphisms (rs2291467, rs11228240 and rs12272917) significantly decreased the osteoporosis risk in the subgroup of body mass index (BMI) ≤ 24 (p < 0.05) and that individuals carrying a heterozygote genotype of WNT16 polymorphisms (rs3779381, rs3801387, rs917727 and rs7776725) had a higher osteoporosis risk in the subgroup of BMI > 24 (p < 0.05). Two haplotypes (haplotype 1: rs3779381, rs3801387, rs917727 and rs7776725; haplotype 2: rs2291467 and rs11228240) were observed, yet only T_rs2291467T_rs11228240 and C_rs2291467C_rs11228240 had a strong association with a decreased risk of osteoporosis (p < 0.05). Additionally, MDR analysis revealed that LRP5 rs2291467 was the best model in single-locus MDR analysis. A seven-locus model including rs3779381-AG, rs7776725-TC, rs3801387-GA and rs917727-TC in WNT16 and rs11228240-CC, rs12272917-TC and rs2291467-CC in LRP5 was the best model in multiple-loci MDR analysis (p < 0.001). These two best models were the most significantly associated with osteoporosis risk.

CONCLUSIONS

Our findings suggested that WNT16 and LRP5 genetic polymorphisms are associated with osteoporosis risk among Chinese postmenopausal women.

Is diabetes mellitus a risk factor for low bone density: a systematic review and meta-analysis

BACKGROUND

This systematic review aimed to investigate whether diabetes mellitus is a risk factor for low bone density, as this might be important and necessary for doctors specialized in treating patients with low bone density.

METHODS

PubMed, Embase, CINAHL, and SciELO were searched for cohort, case-control, and cross-sectional studies that investigated the effects of diabetes mellitus on bone mineral density till January 2020. Data screening and extraction are done independently, whereas the methodological quality of the studies was assessed according to the Newcastle-Ottawa Scale (NOS).

RESULTS

A total of 14 studies that met the eligibility criteria including 24,340 participants were enrolled. The overall quality of the studies had a scale of over 6 points. The overall odds ratio (OR) regarding the risk of diabetes mellitus in low bone density patients was 1.20 [95% confidence interval (CI)0.80-1.79, P = 0.30], and type 2 diabetes mellitus (T2DM) (OR = 0.69 [0.11, 4.55], P = 0.70). Subgroup analysis revealed that whether females or males, developed or developing countries, T2DM, studies after 2015, and quality over 7 points (all P values > 0.05) showed no significant differences with the risk of low bone density, except type 1 diabetes mellitus (T1DM) (OR = 3.83 [1.64, 8.96], P = 0.002), and studies before 2015 (OR = 1.76 [1.06, 2.92], P = 0.03), and quality below 7 points (OR = 2.27 [1.50, 3.43], P = 0.0001). Funnel plot showed no significant asymmetry.

CONCLUSIONS

These findings revealed no relationship between T2DM and low bone density, and also, the evidence between T1DM and low bone density is inadequate, requiring further analysis of well-designed cohort studies.

MiR-26a regulates the expression of serum IGF-1 in patients with osteoporosis and its effect on proliferation and apoptosis of mouse chondrocytes

OBJECTIVES

To examine the effects of the regulation on IGF-1 by miR-26a on the serum of patients with osteoporosis (OP) and apoptosis and proliferation of chondrocytes of mice with OP.

METHODS

Totally 47 patients with OP treated in our hospital between July 2018 and November 2019 were selected as the research group, and 42 healthy individuals in physical examination over this period were selected as the control group. Serum was sampled from each participant in both groups, and miR-26a in the sampled serum was quantified and compared. In addition, chondrocytes were sampled from mice with OP. The changes of proliferation and apoptosis of the chondrocytes were analyzed via MTT and flow cytometry, and the levels of Caspase3, Caspase9, Bax, and Bcl-2 were quantified by western blot (WB) assay.

RESULTS

MiR-26a was expressed highly in the serum of patients with OP and chondrocytes of mice with OP, while IGF-1 was lowly expressed in them. According to the dual-luciferase reporter assay, there was a targeting correlation between miR-26a and IGF-1, and suppressing miR-26a significantly up-regulated the expression and protein level of IGF-1.

CONCLUSIONS

MiR-26a can serve as a biological marker for the diagnosis of OP, and it can suppress the proliferation of chondrocytes and promote their apoptosis by regulating IGF-1.

Association of the Sp1 binding site and -1997 promoter variations in COL1A1 with osteoporosis risk: The application of meta-analysis and bioinformatics approaches offers a new perspective for future research

As a complex disease, osteoporosis is influenced by several genetic markers. Many studies have examined the link between the Sp1 binding site +1245 G > T (rs1800012) and -1997 G > T (rs1107946) variations in the COL1A1 gene with osteoporosis risk. However, the findings of these studies have been contradictory; therefore, we performed a meta-analysis to aggregate additional information and obtain increased statistical power to more efficiently estimate this correlation. A meta-analysis was conducted with studies published between 1991-2020 that were identified by a systematic electronic search of the Scopus and Clarivate Analytics databases. Studies with bone mineral density (BMD) data and complete genotypes of the single-nucleotide variations (SNVs) for the overall and postmenopausal female population were included in this meta-analysis and analyzed using the R metaphor package. A relationship between rs1800012 and significantly decreased BMD values at the lumbar spine and femoral neck was found in individuals carrying the "ss" versus the "SS" genotype in the overall population according to a random effects model (p < 0.0001). Similar results were also found in the postmenopausal female population (p = 0.003 and 0.0002, respectively). Such findings might be an indication of increased osteoporosis risk in both studied groups in individuals with the "ss" genotype. Although no association was identified between the -1997 G > T and low BMD in the overall population, those individuals with the "GT" genotype showed a higher level of BMD than those with "GG" in the subgroup analysis (p = 0.007). To determine which transcription factor (TF) might bind to the -1997 G > T in COL1A1, 45 TFs were identified based on bioinformatics predictions. According to the GSE35958 microarray dataset, 16 of 45 TFs showed differential expression profiles in osteoporotic human mesenchymal stem cells relative to normal samples from elderly donors. By identifying candidate TFs for the -1997 G > T site, our study offers a new perspective for future research.

p53 plays a central role in the development of osteoporosis

Osteoporosis is a metabolic disease affecting 40% of postmenopausal women. It is characterized by decreased bone mass per unit volume and increased risk of fracture. We investigated the molecular mechanism underlying osteoporosis by identifying the genes involved in its development. Osteoporosis-related genes were identified by analyzing RNA microarray data in the GEO database to detect genes differentially expressed in osteoporotic and healthy individuals. Enrichment and protein interaction analyses carried out to identify the hub genes among the deferentially expressed genes revealed TP53, MAPK1, CASP3, CTNNB1, CCND1, NOTCH1, CDK1, IGF1, ERBB2, CYCS to be the top 10 hub genes. In addition, p53 had the highest degree score in the protein-protein interaction network. In vivo and in vitro experiments showed that TP53 gene expression and serum p53 levels were upregulated in osteoporotic patients and a mouse osteoporosis model. The elevated p53 levels were associated with decreases in bone mass, which could be partially reversed by knocking down p53. These findings suggest p53 may play a central role in the development of osteoporosis.

Evaluation of the effect of CaD on the bone structure and bone metabolic changes in senile osteoporosis rats based on MLP–ANN methods

Senile osteoporosis (SOP) is a related disease of systematic degenerative changes in bones during natural aging.

Dietary Acid Load, IGF-1 Single Nucleotide Polymorphism and Bone Resorption among Postmenopausal Chinese Women

The interaction of dietary and genetic factors may affect the development of bone deterioration. This study investigated whether the effects of dietary acid load (DAL) on bone loss in postmenopausal Chinese women were moderated by the insulin-like growth factor-1 (IGF-1) single nucleotide polymorphism, a known gene that plays a role in the regulation of bone formation and bone remodeling. A total of 217 healthy participants were recruited from the National Council of Senior Citizens Organizations Malaysia. Serum collagen type 1 cross-linked C-telopeptide was used as a surrogate bone marker to assess bone resorption and Agena^® MassARRAY genotyping analysis was used to identify the signaling of IGF-1 rs35767. The dietary acid load was measured by potential renal acid load score while physical activity was ascertained using the Global Physical Activity Questionnaire. Hierarchical regression was applied to test the main and interaction effects of DAL and IGF-1 genotypes in bone resorption. The result supported the diet-dependent acid-base balance theory that higher DAL was positively associated with bone resorption (β = 0.152, p = 0.031, F_(6,207) = 2.11, sig-F = 0.036, R² = 0.079). However, the results indicated that there was no significant correlation between IGF-1 and bone resorption, or any significant interaction between DAL and IGF-1. In conclusion, there was no moderating effect of IGF-1 on the relationship between DAL and bone resorption.