Sex Steroid Regulation of Oxidative Stress in Bone Cells: An In Vitro Study

Nanoplastic impact on bone microenvironment: A snapshot from murine bone cells

Our world is made of plastic. Plastic waste deeply affects our health entering the food chain. The degradation and/or fragmentation of plastics due to weathering processes result in the generation of nanoplastics (NPs). Only a few studies tested NPs effects on human health. NPs toxic actions are, in part, mediated by oxidative stress (OS) that, among its effects, affects bone remodeling. This study aimed to assess if NPs influence skeleton remodeling through OS. Murine bone cell cultures (MC3T3-E1 preosteoblasts, MLOY-4 osteocyte-like cells, and RAW264.7 pre-osteoclasts) were used to test the NPs detrimental effects on bone cells. NPs affect cell viability and induce ROS production and apoptosis (by caspase 3/7 activation) in pre-osteoblasts, osteocytes, and pre-osteoclasts. NPs impair the migration capability of pre-osteoblasts and potentiate the osteoclastogenesis of preosteoclasts. NPs affected the expression of genes related to inflammatory and osteoblastogenic pathways in pre-osteoblasts and osteocytes, related to the osteoclastogenic commitment of pre-osteoclasts. A better understanding of the impact of NPs on bone cell activities resulting in vivo in impaired bone turnover could give more information on the possible toxicity consequence of NPs on bone mass and the subsequent public health problems, such as bone disease.

Association between global biomarker of oxidative stress and quantitative ultrasound parameters in middle-aged and elderly adults: A cross-sectional study

Introduction

With the population aging, osteoporosis has become a major public health concern. Elevated oxidative stress is a vital detrimental factor for bone health. Compared to common oxidative stress-related biomarkers, Fluorescent Oxidation Products (FlOPs) reflect the global levels of oxidation from proteins, lipids, and DNA. Nevertheless, whether plasma FlOP levels are related to bone health measured by Quantitative ultrasound (QUS) is unclear. Thus, the present study examined the association between FlOPs and QUS parameters in middle-aged and elderly adults.

Methods

This community-based cross-sectional study was conducted in Changchun, northeast China. Plasma FlOPs were determined by a fluorescent microplate reader at a wavelength of 320/420 nm (excitation/emission). QUS parameters [speed of sound (SOS) and broadband ultrasound attenuation (BUA)] of the calcaneus were assessed by an ultrasound bone densitometer. We used multivariable linear regression to examine the association between FlOPs and QUS parameters.

Results

A total of 491 subjects were included in this study. Their average age was 65.2 years (standard deviation [SD]: 9.7 years). FlOPs were inversely associated with SOS (β for an increase of logarithmic interquartile range = -10.64; P = 0.018). Higher FlOP levels were marginally associated with lower SOS in females (β for an increase of logarithmic interquartile range = -9.68, P = 0.066), but not in males (β for an increase of logarithmic interquartile range = -11.84, P = 0.131). No significant relationship between FlOPs and BUA was observed.

Conclusions

Plasma FlOP levels were inversely associated with SOS, but not with BUA in middle-aged and elderly adults.

Micro-computed tomography assessment of bone structure in aging mice

High-resolution computed tomography (CT) is widely used to assess bone structure under physiological and pathological conditions. Although the analytic protocols and parameters for micro-CT (μCT) analyses in mice are standardized for long bones, vertebrae, and the palms in aging mice, they have not yet been established for craniofacial bones. In this study, we conducted a morphometric assessment of craniofacial bones, in comparison with long bones, in aging mice. Although age-related changes were observed in the microarchitecture of the femur, tibia, vertebra, and basisphenoid bone, and were more pronounced in females than in males, the microarchitecture of both the interparietal bone and body of the mandible, which develop by intramembranous ossification, was less affected by age and sex. By contrast, the condyle of the mandible was more affected by aging in males compared to females. Taken together, our results indicate that mouse craniofacial bones are uniquely affected by age and sex.