Myostatin is mainly secreted by skeletal muscle and negatively regulates skeletal muscle growth. However, the roles of myostatin on bone metabolism are still largely unknown. Here, we recruited two large populations containing 6308 elderly Chinese and conducted comprehensive statistical analyses to evaluate the associations among lean body mass (LBM), plasma myostatin, and bone mineral density (BMD). Our data revealed that total myostatin in plasma was mainly determined by LBM. The relative abundance of mature myostatin (mature/total) was significantly lower in high versus low BMD subjects. Moreover, the relative abundance of mature myostatin was positively correlated with bone resorption marker. Finally, we carried out in vitro experiments and found that myostatin has inhibitory effects on the proliferation and differentiation of human osteoprogenitor cells. Taken together, our results have demonstrated that the relative abundance of mature myostatin in plasma is negatively associated with BMD, and the underlying functional mechanism for the association is most likely through inhibiting osteoblastogenesis and promoting osteoclastogenesis.

Background: This study aimed to investigate the association of high-sensitivity C-reactive protein (hs-CRP) with incident frailty as well as its effects on pre-frailty progression and regression among middle-aged and older adults. Methods: Based on the frailty index (FI) calculated with 41 items, 6890 eligible participants without frailty at baseline from China Health and Retirement Longitudinal Study (CHARLS) were categorized into health, pre-frailty, and frailty groups. Logistic regression models were used to estimate the longitudinal association between baseline hs-CRP and incident frailty. Furthermore, a series of genetic approaches were conducted to confirm the causal relationship between CRP and frailty, including Linkage disequilibrium score regression (LDSC), pleiotropic analysis, and Mendelian randomization (MR). Finally, we evaluated the association of hs-CRP with pre-frailty progression and regression. Results: The risk of developing frailty was 1.18 times (95% CI: 1.03–1.34) higher in participants with high levels of hs-CRP at baseline than low levels of hs-CRP participants during the 3-year follow-up. MR analysis suggested that genetically determined hs-CRP was potentially positively associated with the risk of frailty (OR: 1.06, 95% CI: 1.03–1.08). Among 5241 participants with pre-frailty at baseline, we found pre-frailty participants with high levels of hs-CRP exhibit increased odds of progression to frailty (OR: 1.39, 95% CI: 1.09–1.79) and decreased odds of regression to health (OR: 0.84, 95% CI: 0.72–0.98) when compared with participants with low levels of hs-CRP. Conclusions: Our results suggest that reducing systemic inflammation is significant for developing strategies for frailty prevention and pre-frailty reversion in the middle-aged and elderly population.

Background: This study aimed to investigate the effect of systemic inflammation, assessed by high sensitivity C‐reactive protein (hs‐CRP) levels, on prediabetes progression and regression in middle‐aged and older adults based on the China Health and Retirement Longitudinal Study (CHARLS).Methods: Participants with prediabetes from CHARLS were followed up 4 years later with blood samples collected for measuring fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c). The level of hs‐CRP was assessed at baseline and categorized into tertiles (low, middle, and high groups). Prediabetes at baseline and follow‐up was defined primarily according to the American Diabetes Association (ADA) criteria. Logistic regression models were used to estimate the odds ratios (ORs) and confidence intervals (CIs). We also performed stratified analyses according to age, gender, BMI, the presence of hypertension, and the disease history of heart disease and dyslipidemia and sensitivity analyses excluding a subset of participants with incomplete data.Results: Of the 2,874 prediabetes included at baseline, 834 participants remained as having prediabetes, 146 progressed to diabetes, and 1,894 regressed to normoglycemia based on ADA criteria with a 4 year follow‐up. After multivariate logistics regression analysis, prediabetes with middle (0.67–1.62 mg/L) and high (>1.62 mg/L) hs‐CRP levels had an increased incidence of progressing to diabetes compared with prediabetes with low hs‐CRP levels (<0.67 mg/L; OR = 1.846, 95%CI: 1.129–3.018; and OR = 1.632, 95%CI: 0.985–2.703, respectively), and the incidence of regressing to normoglycemia decreased (OR = 0.793, 95%CI: 0.645–0.975; and OR = 0.769, 95%CI: 0.623–0.978, respectively). Stratified analyses and sensitivity analyses showed consistent results.Conclusions: Low levels of hs‐CRP are associated with a high incidence of regression from prediabetes to normoglycemia and reduced odds of progression to diabetes.

Osteoporosis is a complex skeletal disorder characterized by low bone mineral density (BMD). Compared with classical epigenetic modifications, such as DNA methylation and histone modifications, the participation of chromatin-remodeling complexes in osteoporosis remains less explored. To identify chromatin remodeling factors causally associated with bone mineral density (BMD), here we conducted a systematic analysis of 87 genes encoding components of four major chromatin-remodeling complexes using Summary-data-based Mendelian randomization (SMR) analysis. Candidate chromatin-remodeling factors were further cross-referenced with publicly available skeletal phenotyping data from the International Mouse Phenotyping Consortium (IMPC) database. Functional validation revealed that non-canonical BAF (ncBAF) subunit BRD9 is essential for osteoblast differentiation using both in vitro cell culture and in vivo zebrafish models. RNA-Sequencing (RNA-Seq) demonstrated that BRD9 orchestrates osteogenic differentiation by modulating Wnt/β-catenin signaling activity. Mechanistically, the osteogenic master transcription factor Sp7 was identified as a direct transcriptional target of BRD9, whose expression is coordinately controlled through the synergistic interplay between BRD9 and Wnt/β-catenin signaling during osteogenesis. Collectively, this study established a comprehensive framework for identifying causal genes implicated in osteoporosis and elucidated the previously unrecognized regulatory role of BRD9 in osteogenesis.

Previous observational studies on the relationship between sleep characteristics and fracture have yielded contradictory results. The goal of this study was to replicate the findings in a large longitudinal cohort and then conduct a Mendelian randomization (MR) analysis to infer the causality between sleep behaviors and fracture risk. Based on data from the China Health and Retirement Longitudinal Study (CHARLS) including 17,708 participants, we found that individuals with short sleep duration (<5 h) (OR [odds ratio] = 1.62, 95% CI: 1.07–2.44) or restless sleep (OR = 1.55, 95% CI: 1.10–2.19) have a higher risk of hip fracture. A U-shaped relationship between nighttime sleep duration and hip fracture risk (p-nonlinear = 0.01) was observed using restricted cubic spline regression analysis. Through joint effect analysis, we found that participants with short sleep duration (<5 h) combined with midday napping could significantly decrease hip fracture incidence. We further inferred the causal relationship between self-reported sleep behaviors and hip fracture using the MR approach. Among four sleep phenotypic parameters (sleep duration, daytime napping, chronotype, and insomnia), we found a modest causal relationship between sleep duration and fracture (OR = 0.69, 95% CI: 0.48 to 0.99, p = 0.04). However, no causal relationship was observed for other sleep traits. In conclusion, our findings suggest that short sleep duration has a potential detrimental effect on hip fracture. Improving sleep patterns is of significance for developing hip fracture preventive strategies in the middle-aged and the elderly populations.