Erratum: Transplantation of bone marrow-derived mesenchymal stem cells rescues partially rachitic phenotypes induced by 1,25-Dihydroxyvitamin D deficiency in mice.

[This corrects the article on p. 4382 in vol. 8, PMID: 27830022.

The senolytic agent ABT263 ameliorates osteoporosis caused by active vitamin D insufficiency through selective clearance of senescent skeletal cells.

Background/objective: Active vitamin D insufficiency accelerates the development of osteoporosis, with senescent bone cells and the senescence-associated secretory phenotype (SASP) playing crucial roles. This study aimed to investigate whether the senolytic agent ABT263 could correct osteoporosis caused by active vitamin D insufficiency by selectively clearing senescent cells.

Methods: Bone marrow mesenchymal stem cells (BM-MSCs) from young and aged mice were treated with ABT263 in vitro, and 1,25(OH)D-insufficient (Cyp27b1) mice were administered ABT263 in vivo.

Skewed epithelial cell differentiation and premature aging of the thymus in the absence of vitamin D signaling.

Central tolerance of thymocytes to self-antigen depends on the medullary thymic epithelial cell (mTEC) transcription factor autoimmune regulator (Aire), which drives tissue-restricted antigen (TRA) gene expression. Vitamin D signaling regulates Aire and TRA expression in mTECs, providing a basis for links between vitamin D deficiency and autoimmunity. We find that mice lacking Cyp27b1, which cannot produce hormonally active vitamin D, display profoundly reduced thymic cellularity, with a reduced proportion of Aire mTECs, attenuated TRA expression, and poorly defined cortical-medullary boundaries.

Nrf2 activation by pyrroloquinoline quinone inhibits natural aging-related intervertebral disk degeneration in mice.

Age-related intervertebral disk degeneration (IVDD) involves increased oxidative damage, cellular senescence, and matrix degradation. Pyrroloquinoline quinone (PQQ) is a water-soluble vitamin-like compound with strong anti-oxidant capacity. The goal of this study was to determine whether PQQ can prevent aging-related IVDD, and the underlying mechanism.

Chk2 Modulates Bmi1-Deficiency-Induced Renal Aging and Fibrosis via Oxidative Stress, DNA Damage, and p53/TGFβ1-Induced Epithelial-Mesenchymal Transition.

Renal aging may lead to fibrosis and dysfunction, yet underlying mechanisms remain unclear. We explored whether deficiency of the Polycomb protein Bmi1 causes renal aging via DNA damage response (DDR) activation, inducing renal tubular epithelial cell (RTEC) senescence and epithelial-mesenchymal transition (EMT). Bmi1 knockout mice exhibited oxidative stress, DDR activation, RTEC senescence, senescence-associated secretory phenotype (SASP), and age-related fibrosis in kidneys.

Sedentary behavior does not predict low BMD nor fracture-population-based Canadian Multicentre Osteoporosis Study.

Sedentary behavior (SB) or sitting is associated with multiple unfavorable health outcomes. Bone tissue responds to imposed gravitational and muscular strain with there being some evidence suggesting a causal link between SB and poor bone health. However, there are no population-based data on the longitudinal relationship between SB, bone change, and incidence of fragility fractures.

Geographic variation in bone mineral density and prevalent fractures in the Canadian longitudinal study on aging.

Unlabelled: Awareness of the prevalence of osteoporosis and fractures across jurisdictions can guide the development of local preventive programs and healthcare policies. We observed geographical variations in total hip bone mineral density and in the prevalence of major osteoporotic fractures across Canadian provinces, which persisted after adjusting for important covariates.

Purpose: We aimed to describe sex-specific total hip bone mineral density (aBMD) and prevalent major osteoporotic fractures (MOF) variation between Canadian provinces.

Previous fracture and subsequent fracture risk: a meta-analysis to update FRAX.

Unlabelled: A large international meta-analysis using primary data from 64 cohorts has quantified the increased risk of fracture associated with a previous history of fracture for future use in FRAX.

Introduction: The aim of this study was to quantify the fracture risk associated with a prior fracture on an international basis and to explore the relationship of this risk with age, sex, time since baseline and bone mineral density (BMD).

Methods: We studied 665,971 men and 1,438,535 women from 64 cohorts in 32 countries followed for a total of 19.

Converging evidence from exome sequencing and common variants implicates target genes for osteoporosis.

In this study, we leveraged the combined evidence of rare coding variants and common alleles to identify therapeutic targets for osteoporosis. We undertook a large-scale multiancestry exome-wide association study for estimated bone mineral density, which showed that the burden of rare coding alleles in 19 genes was associated with estimated bone mineral density (P < 3.6 × 10).

Pyrroloquinoline quinone alleviates natural aging-related osteoporosis via a novel MCM3-Keap1-Nrf2 axis-mediated stress response and Fbn1 upregulation.

Age-related osteoporosis is associated with increased oxidative stress and cellular senescence. Pyrroloquinoline quinone (PQQ) is a water-soluble vitamin-like compound that has strong antioxidant capacity; however, the effect and underlying mechanism of PQQ on aging-related osteoporosis remain unclear. The purpose of this study was to investigate whether dietary PQQ supplementation can prevent osteoporosis caused by natural aging, and the potential mechanism underlying PQQ antioxidant activity.

Sirt1 protects against intervertebral disc degeneration induced by 1,25-dihydroxyvitamin D insufficiency in mice by inhibiting the NF-κB inflammatory pathway.

Background: It has been demonstrated that vitamin D deficiency is associated with an increased risk of patients developing lumbar disc herniation. However, intervertebral disc degeneration caused by active vitamin D deficiency has not been reported. Thus, the purpose of this study was to e investigate the role and mechanism of 1,25-dihydroxyvitamin D (1,25(OH)D) insufficiency in promoting intervertebral disc degeneration.

A Fracture Risk Assessment Tool for High Resolution Peripheral Quantitative Computed Tomography.

Most fracture risk assessment tools use clinical risk factors combined with bone mineral density (BMD) to improve assessment of osteoporosis; however, stratifying fracture risk remains challenging. This study developed a fracture risk assessment tool that uses information about volumetric bone density and three-dimensional structure, obtained using high-resolution peripheral quantitative compute tomography (HR-pQCT), to provide an alternative approach for patient-specific assessment of fracture risk. Using an international prospective cohort of older adults (n = 6802) we developed a tool to predict osteoporotic fracture risk, called μFRAC.

Mechanisms of action of vitamin D in delaying aging and preventing disease by inhibiting oxidative stress.

Although several recent studies have shown that vitamin D supplementation beneficially decreases oxidative stress parameters, there is no consensus on this subject in humans. Thus the role of vitamin D supplementation has recently become a controversial topic because large intervention studies in humans have not shown significant benefits. These studies have indicated that supplementation with precursor forms of active vitamin D has no effect on all-cause mortality, cannot reduce the fracture risk of the elderly, cannot reduce the incidence of cancer or cardiovascular disease in the elderly, and cannot significantly reduce the incidence risk of diabetes in the elderly.

1,25-Dihydroxyvitamin D Deficiency Accelerates Aging-related Osteoarthritis via Downregulation of Sirt1 in Mice.

Emerging observational data suggest that vitamin D deficiency is associated with the onset and progression of knee osteoarthritis (OA). However, the relationship between vitamin D level and OA and the role of vitamin D supplementation in the prevention of knee OA are controversial. To address these issues, we analyzed the articular cartilage phenotype of 6- and 12-month-old wild-type and 1α(OH)ase mice and found that 1,25(OH)D deficiency accelerated the development of age-related spontaneous knee OA, including cartilage surface destruction, cartilage erosion, proteoglycan loss and cytopenia, increased OARSI score, collagen X and Mmp13 positive chondrocytes, and increased chondrocyte senescence with senescence-associated secretory phenotype (SASP).

17β-estradiol plays the anti-osteoporosis role via a novel ESR1-Keap1-Nrf2 axis-mediated stress response activation and Tmem119 upregulation.

Increased oxidative stress and decreased osteoblastic bone formation contribute to estrogen deficiency-induced osteoporosis. However, the role and mechanism of estrogen-deficiency in regulating oxidative stress and osteoblastic activity remain unclear. Here, we showed that estrogen-deficient bone marrow stromal/stem cells (BMSCs) exhibited impaired capacity to combat stress, characterized by increased oxidative stress, shortened cell survival and reduced osteogenic differentiation and bone formation, which were due to a decrease of nuclear factor erythroid 2-related factor 2 (Nrf2).

Variation in bone mineral density and fractures over 20 years among Canadians: a comparison of the Canadian Multicenter Osteoporosis Study and the Canadian Longitudinal Study on Aging.

Unlabelled: International variations in osteoporosis and fracture rates have been reported, with temporal trends differing between populations. We observed higher BMD and lower fracture prevalence in a recently recruited cohort compared to that of a cohort recruited 20 years ago, even after adjusting for multiple covariates.

Purpose: We explored sex-specific differences in femoral neck bone mineral density (FN-BMD) and in prevalent major osteoporotic fractures (MOF) using two Canadian cohorts recruited 20 years apart.