Bone and bone marrow disruption by endocrine‐active substances

Urinary phthalate metabolites associated with bone mineral density in adults: Data from the NHANES 2011-2018

Phthalates (PAEs) are common environmental endocrine disruptors and environmental bone poisons that can reduce bone mineral density (BMD). The purpose of this study is to investigate whether the concentration of PAE metabolites in urine is related to BMD in many parts of adult bones. We examined a series of cross-sectional data of male (n = 1835) and female (n = 1756) participants aged 18 to 59 years old in the National Health and Nutrition Examination Survey from 2011 to 2018 and measured urine PAE metabolites and dual-energy X-ray absorption to determine BMD (total, lumbar spine, and pelvis). We used linear regression to test the correlation between a single phthalate biomarker and BMD. After adjusting all confounding variables, MEHP was positively correlated with BMD of total body, lumbar spine and pelvis, and BMD levels of the total body, lumbar spine and pelvis decreased with the increase of MECPP concentration. We used the restricted cubic spline function to test the nonlinear correlation between PAE biomarkers and BMD. The results show that urinary PAE metabolites have a nonlinear relationship with total body BMD, lumbar BMD, and pelvic BMD. With the increase in the PAE concentration, the BMD level first increased and then decreased, showing an inverted U-shaped trend (P < 0.05). Gender stratification also shows the same related trend. PAEs may be related to the BMD of adults. When the concentration of PAEs increases to a certain threshold, it will lead to a significant decrease in BMD.

Identification of endocrine-disrupting chemicals targeting key OP-associated genes via bioinformatics and machine learning

Osteoporosis (OP), a metabolic disorder predominantly impacting postmenopausal women, has seen considerable progress in diagnosis and treatment over the past few decades. However, the intricate interplay between genetic factors and endocrine disruptors (EDCs) in the pathogenesis of OP remains inadequately elucidated. The objective of this research is to examine the environmental pollutants and their regulatory mechanisms that could potentially influence the pathogenesis of OP, in order to establish a theoretical foundation for the targeted prevention and medical management of individuals with OP. Utilizing CTD and GEO datasets, network toxicology and bioinformatics analyses were conducted to identify target genes from a pool of 98 co-associated genes. Subsequently, a novel prediction model was developed employing a multiple machine learning algorithm. The efficacy of the model was validated based on the area under the receiver operating characteristic curve. Finally, real-time quantitative polymerase chain reaction (qRT-PCR) was used to confirm the expression levels of key genes in clinical samples. We have identified significant genes (FOXO3 and LUM) associated with OP and conducted Gene Ontology, Kyoto Encyclopedia of Genes and Genomes enrichment analysis, immune infiltration analysis, and molecular docking analysis. Through the analysis of these key genes, we have identified 13 EDCs that have the potential to impact OP. Several endocrine disruptors, such as Dexamethasone, Perfluorononanoic acid, genistein, cadmium, and bisphenol A, have been identified as notable environmental pollutants that impact the OP. Molecular docking analysis revealed significant binding affinity of major EDCs to the post-translational protein structures of key genes. This study demonstrates that EDCs, including dexamethasone, perfluorononanoic acid, genistein, cadmium, and bisphenol A, can be identified as important environmental pollutants affecting OP, and that FOXO3 and LUM have the potential to be diagnostic markers for OP. These results elucidate a novel association between EDCs regulated by key genes and the onset of OP.

Effects of Endocrine-Disrupting Chemicals on Bone Health

This comprehensive review critically examines the detrimental impacts of endocrine-disrupting chemicals (EDCs) on bone health, with a specific focus on substances such as bisphenol A (BPA), per- and polyfluoroalkyl substances (PFASs), phthalates, and dioxins. These EDCs, by interfering with the endocrine system's normal functioning, pose a significant risk to bone metabolism, potentially leading to a heightened susceptibility to bone-related disorders and diseases. Notably, BPA has been shown to inhibit the differentiation of osteoblasts and promote the apoptosis of osteoblasts, which results in altered bone turnover status. PFASs, known for their environmental persistence and ability to bioaccumulate in the human body, have been linked to an increased osteoporosis risk. Similarly, phthalates, which are widely used in the production of plastics, have been associated with adverse bone health outcomes, showing an inverse relationship between phthalate exposure and bone mineral density. Dioxins present a more complex picture, with research findings suggesting both potential benefits and adverse effects on bone structure and density, depending on factors such as the timing and level of exposure. This review underscores the urgent need for further research to better understand the specific pathways through which EDCs affect bone health and to develop targeted strategies for mitigating their potentially harmful impacts.

Associations of pyrethroid exposure with bone mineral density and osteopenia in adults

INTRODUCTION

This study was to investigate the correlations between pyrethroid exposure and bone mineral density (BMD) and osteopenia.

MATERIALS AND METHODS

This cross-sectional study included 1389 participants over 50 years of age drawn from the 2007-2010 and 2013-2014 National Health and Nutrition Examination Survey (NHANES). Three pyrethroid metabolites, 3-phenoxybenzoic acid (3-PBA), trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid (trans-DCCA), and 4-fluoro-3-phenoxybenzoic acid (4-F-3PBA) were used as indicators of pyrethroid exposure. Low BMD was defined as T-score < - 1.0, including osteopenia. Weighted multivariable linear regression analysis or logistic regression analysis was utilized to evaluate the correlation between pyrethroid exposure and BMD and low BMD. Bayesian kernel machine regression (BKMR) model was utilized to analyze the correlation between pyrethroids mixed exposure and low BMD.

RESULTS

There were 648 (48.41%) patients with low BMD. In individual pyrethroid metabolite analysis, both tertile 2 and tertile 3 of trans-DCCA were negatively related to total femur, femur neck, and total spine BMD [coefficient (β) = - 0.041 to - 0.028; all P < 0.05]. Both tertile 2 and tertile 3 of 4-F-3PBA were negatively related to total femur BMD (P < 0.05). Only tertile 2 [odds ratio (OR) = 1.63; 95% CI = 1.07, 2.48] and tertile 3 (OR = 1.65; 95% CI = 1.10, 2.50) of trans-DCCA was correlated with an increased risk of low BMD. The BKMR analysis indicated that there was a positive tendency between mixed pyrethroids exposure and low BMD.

CONCLUSION

In conclusion, pyrethroids exposure was negatively correlated with BMD levels, and the associations of pyrethroids with BMD and low BMD varied by specific pyrethroids, pyrethroid concentrations, and bone sites.

An Overview of the Health Effects of Bisphenol A from a One Health Perspective

Bisphenol A (BPA) is a chemical compound, considered as an "emerging pollutant", that appears ubiquitously, contaminating the environment and food. It is an endocrine disruptor, found in a multitude of consumer products, as it is a constituent of polycarbonate used in the manufacture of plastics and epoxy resins. Many studies have evaluated the effects of BPA, using a wide range of doses and animal models. In this work, we carried out a review of relevant research related to the effects of BPA on health, through studies performed at different doses, in different animal models, and in human monitoring studies. Numerous effects of BPA on health have been described; in different animal species, it has been reported that it interferes with fertility in both females and males and causes alterations in their offspring, as well as being associated with an increase in hormone-dependent pathologies. Similarly, exposure to BPA has been related to other diseases of great relevance in public health such as obesity, hypertension, diabetes, or neurodevelopmental disorders. Its ubiquity and nonmonotonic behavior, triggering effects at exposure levels considered "safe", make it especially relevant when both animal and human populations are constantly and inadvertently exposed to this compound. Its effects at low exposure levels make it essential to establish safe exposure levels, and research into the effects of BPA must continue and be focused from a "One Health" perspective to take into account all the factors that could intervene in the development of a disease in any exposed organism.

Endocrine Disruptor-Induced Bone Damage Due to Hormone Dysregulation: A Review

Hormones are indispensable for bone development, growth, and maintenance. While many of the genes associated with osteogenesis are well established, it is the recent findings in endocrinology that are advancing the fields of bone biology and toxicology. Endocrine-disrupting chemicals (EDCs) are defined as chemicals that interfere with the function of the endocrine system. Here, we report recent discoveries describing key hormone pathways involved in osteogenesis and the EDCs that alter these pathways. EDCs can lead to bone morphological changes via altering hormone receptors, signaling pathways, and gene expression. The objective of this review is to highlight the recent discoveries of the harmful effects of environmental toxicants on bone formation and the pathways impacted. Understanding the mechanisms of how EDCs interfere with bone formation contributes to providing a comprehensive toxicological profile of a chemical.

Associations of maternal gestational urinary environmental phenols concentrations with bone mineral density among 12-year-old children in the HOME Study

BACKGROUND

Early life environmental exposures may affect bone mass accrual in childhood, but only one study has assessed the role of environmental phenols on child bone health.

METHODS

We used data from 223 mother-child dyads enrolled in the Health Outcomes and Measures of the Environment (HOME) Study (Cincinnati, OH; 2003-2006). We quantified benzophenone-3, bisphenol A (BPA), 2,5-dichlorophenol, and triclosan in maternal urine collected at 16- and 26-weeks gestation and calculated the average of creatinine-adjusted concentrations. We performed dual x-ray absorptiometry at age 12 years and calculated Z-scores for whole body (less head), total hip, femoral neck, and 1/3rd distal radius bone mineral content (BMC) and areal bone mineral density (aBMD) as well as ultra-distal radius aBMD and spine BMC and bone mineral apparent density (BMAD). We estimated covariate-adjusted associations per doubling of maternal urinary environmental phenol concentrations in linear regression models. We also examined effect measure modification by child's sex and estimated associations of the environmental phenol mixture with BMC and aBMD using quantile g-computation.

RESULTS

We observed generally null associations for all analytes and bone measures. Yet, in adjusted models, higher urinary 2,5-dichlorophenol concentrations were associated with higher 1/3rd distal radius BMC (β: 0.09; 95% CI: 0.02, 0.17) and aBMD (β: 0.09; 95% CI: 0.02, 0.17) Z-scores in the overall sample. In sex-stratified analyses, the magnitude of the BMC association was positive for females (β: 0.16; 95% CI: 0.06, 0.26) and null for males (β: 0.02; 95% CI: 0.08, 0.13). The environmental phenol mixture was associated with greater 1/3rd distal radius BMC and aBMD Z-scores in both sexes, which was mostly driven by benzophenone-3 in males and 2,5-dichlorophenol in females.

CONCLUSION

In this prospective cohort study, we observed generally null associations for environmental phenols with BMC and aBMD at age 12 years. While there was a positive association of 2,5-dichlorophenol concentrations during fetal development with distal radius BMC and aBMD at age 12 years, future studies utilizing methods capable of differentiating cortical and trabecular bone are needed to elucidate potential mechanisms and implications for bone strength and microarchitecture.

Molecular characterization of physis tissue and hormonal profiles of female rats neonatally exposed to low-dose bisphenol A

Physis is a complex cartilaginous structure that is critical for longitudinal bone growth. As one of the endocrine-disrupting chemicals, bisphenol A (BPA) can interfere with the physis by deranging the complex networks of nutritional, cellular, paracrine, and endocrine factors, and this affects longitudinal bone growth, leading to different growth outcomes. However, the exact mechanisms underlying these phenomena remain unclear. Therefore, understanding the molecular pathways involved in the physis after neonatal exposure to low-dose BPA may permit the identification of research targets for therapeutics, which may aid in modulating the process of growth plate closure. In the present study, female Sprague-Dawley rats were exposed to 0.05 mg·kg^-1·day^-1 of BPA and corn oil vehicle from postnatal day 1 (PND1) to 15 via subcutaneous injection. Next-generation RNA sequencing was performed for the mRNA isolated from the physis. The levels of osteocalcin (OC), growth hormone (GH), and insulin-like growth factor 1 (IGF-1) were measured on PND30 (BPA0.05mg vs. Vehicle; n = 5 for each group). We observed statistically significant enrichment of gene sets in the BPA0.05mg tissues compared with the Vehicle tissues. Further analysis of the differentially expressed genes (DEGs) identified BPA0.05mg-specific networks of secreted proteins (LEP, NPY, AGT, ACE2, C4B, and C4BPA) as well as those of local matrix and protease proteins (FBN2, LAMC2, ADAMTS16, and ADAMTS19). Furthermore, the levels of OC and GH were affected by BPA exposure. Our results revealed the specific molecular characteristics of physis contaminated with BPA and may provide new clues for physis maturation and supervision of industrial products and occupational exposure.

Exposure to environmental contaminants and folic acid supplementation intergenerationally impact fetal skeleton development through the paternal lineage in a rat model

Persistent organic pollutants (POPs) are ubiquitous in the environment, which is of concern since they are broadly toxic for wildlife and human health. It is generally accepted that maternal prenatal folic acid supplementation (FA) may beneficially impact offspring development, but it has been recently shown that the father's exposures also influence the health of his offspring. Bone is an endocrine organ essential for whole-body homeostasis and is susceptible to toxicants. Herein, we tested the hypotheses that prenatal paternal exposure to POPs induces developmental bone disorders in fetuses across multiple generations and that FA supplementation attenuates these disorders. We used a four-generation rat model, in which F0 founder females were divided into four treatment groups. F0 females were gavaged with corn oil or an environmentally-relevant POPs mixture and fed either a control diet (2 mg FA/kg), or FA supplemented diet (6 mg FA/kg) before mating and until parturition (four treatments in total). After the birth of the F1 litters, all F0 females and subsequent generations received the FA control diet. Staining with alcian blue and alizarin red S of male and female fetal skeletons was performed at Gestational Day 19.5. Paternal direct and ancestral exposure to POPs delayed bone ossification and decreased the length of long limb bones in fetuses. Maternal FA supplementation did not counteract the POPs-associated delayed fetal ossification and reduced long bone length. In conclusion, prenatal paternal POPs exposure causes developmental bone abnormalities over multiple generations, which were not corrected by maternal FA supplementation.

Bisphenol A inhibits osteogenic activity and causes bone resorption via the activation of retinoic acid-related orphan receptor α

Bisphenol A (BPA) has deleterious effects on bone metabolism; however, its underlying mechanism has not yet been comprehensively understood. Here, we investigated whether RORα plays an important role in BPA-induced bone resorption both in vitro and in vivo. We found that BPA (0.1-1 μM) inhibited osteogenic activity (including ALP activity and mineralization), decreased the expression levels of osteoblast markers (such as RUNX2, OSX, and ALP) in human MG-63 osteoblast-like osteosarcoma cells, and inhibited spontaneous vertebral formation in zebrafish larvae. Additionally, BPA diminished β-glycerophosphate-induced osteoblast differentiation and vertebral formation, while simultaneously downregulating the expression levels of RUNX2a, OSX, and ALP. Furthermore, molecular docking data showed that a hydroxyl group of BPA dominantly binds to the H3 (ALA70) and/or H5 (ARG107) of RORα-ligand binding domain with hydrogen bonding (ALA330 and/or ARG367 in the full length of RORα, respectively), which another hydroxyl group of BPA fits into H3, H6, and H7 elements with non-covalent interactions, resulting in the activation of RORα. However, an RORα inverse agonist potently inhibited BPA-induced anti-osteogenic activity and vertebral formation in zebrafish larvae, concomitant with inhibition of osteogenic gene expression. Overall, our findings reveal that BPA inhibits osteoblast differentiation and bone formation by activating RORα. These results suggest that BPA exposure (0.1-1 μM) can cause various bone-resorptive diseases, such as osteoporosis.

RS 2247911 polymorphism of GPRC6A gene and serum undercarboxylated-osteocalcin are associated with testis function

PURPOSE

Undercarboxylated-Osteocalcin (ucOCN), acting on its putative receptor GPRC6A, was shown to stimulate testosterone (T) production by Leydig cells in rodents, in parallel with the hypothalamus-pituitary-gonadal axis (HPG) mediated by luteinizing hormone (LH). The aim of this cross-sectional study was to evaluate the association among serum ucOCN, rs2247911 polymorphism of GPRC6A gene and the endocrine/semen pattern in a cohort of infertile males, possibly identifying an involvement of the ucOCN-GPRC6A axis on testis function.

METHODS

190 males, including 74 oligozoospermic subjects, 58 azoosperminc patients and 58 normozoospermic controls, were prospectively recruited at the Orient Hospital for Infertility, Assisted Reproduction and Genetics in Syria (Study N. 18FP), from July 2018 to June 2020. Outpatient evaluation included the clinical history, anthropometrics and a fasting blood sampling for hormonals, serum OCN (both carboxylated and undercarboxylated), glycemic and lipid profile and screening for rs2247911 GPRC6A gene polymorphism.

RESULTS

Higher serum ucOCN associated with higher T and HDL-cholesterol (respectively: r = 0.309, P < 0.001 and r = 0.248, P = 0.001), and with lower FSH (r =  - 0.327, P < 0.001) and LDL-cholesterol (r =  - 0.171; P = 0.018). Patients bearing the GG genotype of rs2247911 had higher sperm count compared to GA genotype (P = 0.043) and, compared to both AG and AA genotypes, had higher serum T (P = 0.004, P = 0.001) and lower triglycerides levels (P = 0.002, P < 0.001). Upon normalization for LH levels and body mass index, rs2274911 and ucOCN were significantly associated with higher serum T at linear stepwise regression analysis (P = 0.013, P = 0.007).

CONCLUSIONS

Our data suggest the involvement of ucOCN-GPRC6A axis in the regulation of T production by the testis, subsidiary to HPG.

Effects of bone marrow-derived mesenchymal stem cells exposed to endocrine-disrupting chemicals on the differentiation of umbilical cord blood hematopoietic stem cells

Endocrine-disrupting chemicals (EDCs), a class of peripheral toxic substances, can cause many environmental and clinical side effects, particularly on the human body's endocrine system. Bisphenol A (BPA) and diethylhexyl phthalate (DEHP) are two well-known EDCs in the medicine industry. However, there are no comprehensive studies on their effects on hematopoiesis. Hence, this study aimed to investigate the effect of these two aforementioned substances on the clonogenic capacity of umbilical cord blood hematopoietic stem cells (CB-HSCs). The HSCs which express CD34 + were isolated from umbilical cord blood by the magnetic-activated cell sorting (MACS) system. To investigate the effects of different optimized concentrations of BPA and DEHP, CB-CD34⁺ HSCs were exposed to EDCs in semisolid medium. For evaluation of coexposures, CB-CD34⁺ HSCs were cocultured with bone marrow-derived mesenchymal stem cells (BM-MSCs) in the presence of BPA and DEHP. Finally, the number and types of colonies were evaluated after 14 days. Statistical analysis was performed by GraphPad Prism through ANOVA. CB-HSC treated by BPA and DEHP showed a lower absolute colony count than the control group (P < 0.05). Decrease in clonogenic potential of HSCs was more significant in coculture condition by MSCs. In particular, there was a significant decrease in the BFU-E colonies in comedicated-derived fractions (P < 0.0001). In the presence of EDCs such as BPA and DEHP, the patterns of differentiation in CD34⁺ CB-HSCs changed from suppressed erythroid differentiation toward stimulated myelogenesis pathways.

Associations of pregnancy phthalate concentrations and their mixture with early adolescent bone mineral content and density: The Health Outcomes and Measures of the Environment (HOME) study

BACKGROUND

The developing fetus may be particularly susceptibility to environmental osteotoxicants, but studies of pregnancy phthalate exposures and childhood bone health are scarce.

OBJECTIVES

To examine relations of pregnancy phthalate exposure biomarkers with early adolescent bone mineral density (BMD) and bone mineral content (BMC) in a prospective birth cohort.

METHODS

We used data from 223 pregnant mothers and their children enrolled in a Cincinnati, OH area cohort from 2003 to 2006. We quantified monoethyl phthalate (MEP), monoisobutyl phthalate, monobutyl phthalate, monobenzyl phthalate, mono-(3-carboxypropyl) phthalate (MCPP), and four metabolites of di-2-ethylhexyl phthalate in maternal urine collected at 16 and 26 weeks gestation, and calculated the average of creatinine-standardized concentrations. Using dual x-ray absorptiometry measures at age 12 years, we calculated BMD and BMC Z-scores for six skeletal sites. In overall and sex-stratified models, we estimated covariate-adjusted associations per 2-fold increase in phthalate biomarker concentrations using linear regression, and estimated joint effects of the phthalate biomarkers mixture using Bayesian kernel machine regression (BKMR) and quantile g-computation.

RESULTS

In single phthalate models, several biomarkers were positively associated with BMC and BMD. For example, each doubling of MEP and MCPP, 1/3rd distal radius BMD Z-score increased by 0.09 (95% CI: 0.01, 0.17) and 0.16 (95% CI: 0.01, 0.31), respectively. For phthalate mixtures, associations were generally U-shaped among males and positive-linear among females, using both statistical methods. Mixture associations were strongest with forearm sites: in BKMR models, increasing all biomarkers from the 50th to 90th percentile was associated with a 0.64 (95% CI: 0.01, 1.28) greater 1/3rd distal radius BMD Z-score in males, and a 0.49 (95% CI: -0.13, 1.10) greater ultradistal radius BMD Z-score in females.

DISCUSSION

In this study, phthalate exposures during gestation were associated with increased BMD Z-scores in early adolescence, though further research is needed to determine implications for long-term skeletal health.

Exosomes in the Healthy and Malignant Bone Marrow Microenvironment

The bone marrow (BM) is a complex organ that sustains hematopoiesis via mechanisms involving the microenvironment. The microenvironment includes several cell types, neurotransmitters from innervated fibers, growth factors, extracellular matrix proteins, and extracellular vesicles. The main function of the BM is to regulate hematopoietic function to sustain the production of blood and immune cells. However, the BM microenvironment can also accommodate the survival of malignant cells. A major mechanism by which the cancer cells communicate with cells of the BM microenvironment is through the exchange of exosomes, a subset of extracellular vesicles that deliver molecular signals bidirectionally between malignant and healthy cells. The field of exosomes is an active area of investigation since an understanding of how the exosomal packaging, cargo, and production can be leveraged therapeutically to deter cancer progression and sensitize malignant cells to other therapies. Altogether, this chapter discusses the crucial role of exosomes in the development and progression of BM-associated cancers, such as hematologic malignancies and marrow-metastatic breast cancer. Exosome-based therapeutic strategies and their limitations are also considered.

Rodent Model of Gender-Affirming Hormone Therapies as Specific Tool for Identifying Susceptibility and Vulnerability of Transgender People and Future Applications for Risk Assessment

Transgenders (TGs) are individuals with gender identity and behaviour different from the social norms; they often undergo gender-affirming hormone therapy (HT). HT for TG men involves testosterone treatment and, for TG women, oestrogen plus androgen-lowering agents. Due-but not limited-to the lifelong lasting HT, usually TG people experience several physical and behavioural conditions leading to different and specific susceptibility and vulnerability in comparison to general population, including the response to chemical contaminants present in daily life. In particular, the exposure to the widespread endocrine disrupters (EDs) may affect hormonal and metabolic processes, leading to tissue and organ damage. Since the endocrine system of TG people is overstimulated by HT and, often, the targets overlap with ED, it is reasonable to hypothesize that TG health deserves special attention. At present, no specific tools are available to study the toxicological effects of environmental contaminants, including EDs, and the potential long-term consequences of HT on TG people. In this context, the development of adequate and innovative animal models to mimic gender-affirming HT have a high priority, since they can provide robust data for hazard identification in TG women and men, leading to more reliable risk assessment.

Endocrine disrupting chemicals and bone

Endocrine-disrupting chemicals (EDCs) are defined as chemicals that interfere with the function of the endocrine system. EDCs exert their hormonal effects through several mechanisms; modulating hormone receptors or changing metabolism of different hormones. EDCs also influence multiple signalling pathways while effecting the hormonal systems and possess complex dose-response curves. EDCs can exert deleterious effects on bone tissue through changing bone modelling and remodelling via altering bone paracrine hormone synthesis, the release of systemic hormones, cytokines, chemokines and growth factors, and effecting stem cell fate, as well as bone marrow mesenchymal stem cell differentiation. Evidence is accumulating of the bone disrupting effect of different groups of EDCs, such as; the perfluoroalkyl substances, the phthalate esters, the bisphenol A, the organotin compounds, the alkylphenols and the dioxin and dioxin-like compounds. This review highlights the recent discoveries of the effects of commonly found environmental chemicals on bone from basic molecular findings to clinical implications.

Associations of Maternal Serum Perfluoroalkyl Substances Concentrations with Early Adolescent Bone Mineral Content and Density: The Health Outcomes and Measures of the Environment (HOME) Study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) may impair bone accrual and strength via endocrine disruption and nuclear receptor agonism, but human studies are primarily of adults or cross-sectional.

OBJECTIVES

We assessed associations of individual PFAS and their mixture during pregnancy with child bone mineral content (BMC) and areal bone mineral density (aBMD) at age 12 y.

METHODS

Among 206 mother-child pairs enrolled in a prospective cohort (2003-2006), we quantified perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonic acid (PFOS) in maternal serum collected during gestation or delivery. When children were age 12 y, we performed dual energy X-ray absorptiometry and calculated BMC, aBMD, and bone mineral apparent density (BMAD) z -scores for six skeletal sites. We estimated covariate-adjusted z -score differences per doubling of individual PFAS using linear regression and assessed the PFAS mixture using quantile g-computation and Bayesian kernel machine regression. We explored whether associations were modified by child's sex or mediated by whole-body lean mass.

RESULTS

In covariate-adjusted models, we found that higher maternal serum concentrations of PFOA, PFNA, and the PFAS mixture were associated with lower total hip and forearm (one-third distal radius) BMC z -scores in children. Differences in forearm BMC z -scores were - 0.17 [95% confidence interval (CI): - 0.35 , 0.01] and - 0.24 (95% CI: - 0.44 , - 0.05 ) per doubling of PFOA and PFNA, respectively, and - 0.18 (95% CI: - 0.34 , - 0.02 ) per quartile increase in the PFAS mixture. Child's sex modified PFOA associations for some skeletal sites; for example, differences in spine BMAD z -score per doubling were - 0.31 (95% CI: - 0.58 , - 0.03 ) among males and 0.07 (95% CI: - 0.16 , 0.30) among females (modification p = 0.04 ). Except for PFNA among females, these associations were not mediated by whole-body lean mass.

DISCUSSION

Maternal PFAS concentrations during pregnancy may be associated with lower bone mineral accrual and strength in early adolescence. https://doi.org/10.1289/EHP9424.

In Search of a Role for Extracellular Purine Enzymes in Bone Function

Bone is one of the major tissues that undergoes continuous remodeling throughout life, thus ensuring both organic body growth during development and protection of internal organs as well as repair of trauma during adulthood. Many endogenous substances contribute to bone homeostasis, including purines. Their role has increasingly emerged in recent decades as compounds which, by interacting with specific receptors, can help determine adequate responses of bone cells to physiological or pathological stimuli. Equally, it is recognized that the activity of purines is closely dependent on their interconversion or metabolic degradation ensured by a series of enzymes present at extracellular level as predominantly bound to the cell membrane or, also, as soluble isoforms. While the effects of purines mediated by their receptor interactions have sufficiently, even though not entirely, been characterized in many tissues including bone, those promoted by the extracellular enzymes providing for purine metabolism have not been. In this review, we will try to circumstantiate the presence and the role of these enzymes in bone to define their close relationship with purine activities in maintaining bone homeostasis in normal or pathological conditions.

Critical Role of Estrogens on Bone Homeostasis in Both Male and Female: From Physiology to Medical Implications

Bone is a multi-skilled tissue, protecting major organs, regulating calcium phosphate balance and producing hormones. Its development during childhood determines height and stature as well as resistance against fracture in advanced age. Estrogens are key regulators of bone turnover in both females and males. These hormones play a major role in longitudinal and width growth throughout puberty as well as in the regulation of bone turnover. In women, estrogen deficiency is one of the major causes of postmenopausal osteoporosis. In this review, we will summarize the main clinical and experimental studies reporting the effects of estrogens not only in females but also in males, during different life stages. Effects of estrogens on bone involve either Estrogen Receptor (ER)α or ERβ depending on the type of bone (femur, vertebrae, tibia, mandible), the compartment (trabecular or cortical), cell types involved (osteoclasts, osteoblasts and osteocytes) and sex. Finally, we will discuss new ongoing strategies to increase the benefit/risk ratio of the hormonal treatment of menopause.

Recent advances in the application of magnetic Fe3O4 nanomaterials for the removal of emerging contaminants

Emerging contaminants (ECs) are widely distributed and potentially hazardous to human health and the ecological system. However, traditional wastewater treatment techniques are not sufficient to remove ECs. Magnetic nanomaterials are made of ferromagnetic or superparamagnetic magnetic elements such as iron and nickel, which can be easily separated from the aqueous solution, making them ideal adsorbents for contaminants in water. This review focused on the synthesis approaches of magnetic Fe₃O₄ nanoparticles (MFNs), as well as surface modification in order to improve their stability and functional diversity. Also, a detailed summary on the state-of-art application of magnetic nanomaterials on the removal of ECs was addressed. Additionally, challenges and future prospective of applying magnetic nanomaterials into real-world cases were discussed, in which the green and simple synthesis and evaluation of the toxic effects of MFNs are still of great challenge. This work summarizes the recent progress of using magnetic nanomaterials as promising and powerful tools in the treatment of ECs-contaminated water, benefiting researchers interested in nanomaterials and environmental studies.

Bone Disruption and Environmental Pollutants

BACKGROUND

Endocrine Disrupting Chemicals (EDCs) are ubiquitous and may significantly contribute in environmental pollution, thus contaminating humans and wildlife. Environmental pollutants could interfere with bone homeostasis by means of different mechanisms, which include hormonal imbalance, direct osteoblasts toxicity and enanchment of osteoclasts activity, thus leading to osteopenia or osteoporosis. Among these, bisphenols, dioxins, polycyclic aromatic hydrocarbons, polychlorobiphenyls, poly- and perfluoroalkyls, phthalates, parabens, organotins and cadmium may play a role in bone distuption.

METHODS

PubMed/MEDLINE, ISI-web of knowledge and Google scholar databases were searched for medical subject headings terms and free-text word related to the aforementioned classes of chemicals and bone metabolism and remodelling for better clarifying and understanding the main mechanisms of bone disruption.

RESULTS

Several of EDCs act as xenoestrogens. Considering that estrogens play a significant role in regulating bone remodeling, most of these chemicals generate hormonal imbalance with possible detrimental consequences on bone tissue structure and its mechanical and non-mechanical properties.

DISCUSSION

A lot of evidences about bone distruptors came from in vitro studies or animal models, and conduct to equivocal results. In addition, a few data derived form humans and most of these data focused on the impact of EDCs on bone mineral density without considering their influence on long-term fracture risk. Moreover, it should be taken into account that humans are exposed to a mixture of EDCs and the final effect on bone metabolism might be the result of either a synergism or antagonist effects among them. Age of first exposure, cumulative dose exposure over time, and the usually observed non-monotonic dose-response curve for EDCs should be considered as other important variable influencing the final effect on bone metabolism.

CONCLUSION

Taking into account these variables, observational studies are needed to better analyze this issue both for echological purpose and to preserve bone health.

Endocrine Disruptors as a New Etiologic Factor of Bone Tissue Diseases (Review)

At present, diseases of bones and joints stand third after cardiovascular and oncological pathologies which demands the necessity of searching for new etiological factors and pathogenetical mechanisms of these illnesses. The accumulating data show the association between the impairment of bone tissue development and regeneration and endocrine disruptor impact. Endocrine disruptors are chemical substances, mainly of anthropogenic origin, capable of affecting endocrine system functioning and interfering with organ morphogenesis and physiological functions. The development and regeneration of bone tissues have a complex hormonal regulation and therefore bone tissue cells, osteoblasts, and osteoclasts can be considered as potential targets for endocrine disruptors. Endocrine disruptors have been established to be able to impair calcium metabolism which also contributes to the development of musculoskeletal system pathology. Data on histogenesis of bone tissue and regeneration, calcium metabolism as well as on hormonal regulation of bone growth and remodeling processes are presented in this work. Recent information on the effect of the main endocrine disruptor classes (diethylstilbestrol, organochlorine pesticides, alkylphenols, bisphenol A, dioxins, polychlorinated biphenyls, and phthalic acid esters) on the development and remodeling of bone tissues and calcium metabolism has been summarized. The established physiological and molecular mechanisms of their action have been also considered.

Microtopography of Immune Cells in Osteoporosis and Bone Lesions by Endocrine Disruptors

Osteoporosis stems from an unbalance between bone mineral resorption and deposition. Among the numerous cellular players responsible for this unbalance bone marrow (BM) monocytes/macrophages, mast cells, T and B lymphocytes, and dendritic cells play a key role in regulating osteoclasts, osteoblasts, and their progenitor cells through interactions occurring in the context of the different bone compartments (cancellous and cortical). Therefore, the microtopography of immune cells inside trabecular and compact bone is expected to play a relevant role in setting initial sites of osteoporotic lesion. Indeed, in physiological conditions, each immune cell type preferentially occupies either endosteal, subendosteal, central, and/or perisinusoidal regions of the BM. However, in the presence of an activation, immune cells recirculate throughout these different microanatomical areas giving rise to a specific distribution. As a result, the trabeculae of the cancellous bone and endosteal free edge of the diaphyseal case emerge as the primary anatomical targets of their osteoporotic action. Immune cells may also transit from the BM to the depth of the compact bone, thanks to the efferent venous capillaries coursing in the Haversian and Volkmann canals. Consistently, the innermost parts of the osteons and the periosteum are later involved by their immunomodulatory action, becoming another site of mineral reabsorption in the course of an osteoporotic insult. The novelty of our updating is to highlight the microtopography of bone immune cells in the cancellous and cortical compartments in relation to the most consistent data on their action in bone remodeling, to offer a mechanist perspective useful to dissect their role in the osteoporotic process, including bone damage derived from the immunomodulatory effects of endocrine disrupting chemicals.

Perfluoroalkyl substances and changes in bone mineral density: A prospective analysis in the POUNDS-LOST study

BACKGROUND

Recent studies suggested an inverse association between exposures to perfluoroalkyl substances (PFASs) and bone mineral density (BMD). Whether exposures to PFASs are also associated with changes in BMD has not been examined.

METHODS

Five major PFASs (perfluorooctanesulfonic acid, PFOS; perfluorooctanoic acid, PFOA; perfluorohexanesulfonic acid, PFHxS; perfluorononanoic acid, PFNA; perfluorodecanoic acid, PFDA) and BMD (g/cm²) at six bone sites (spine, total hip, femoral neck, hip intertrochanteric area, hip trochanter, and hip Ward's triangle area) were measured at baseline among 294 participants in the POUNDS-LOST study, a weight-loss trial, of whom a total of 175 participants had BMD measured at both baseline and year 2. Linear regression was used to model the differences or changes in BMD for each SD increment of PFAS concentrations. In a secondary analysis, interactions between PFASs and baseline body mass index (BMI), as well as a BMI-related genetic risk score (GRS) derived from 97 BMI-predicting SNPs were examined in relation to changes in BMD.

RESULTS

At baseline, both PFOS and PFOA were significantly associated with lower BMD at several sites. For each SD increase of PFOS, the βs (95% CIs) for BMD were -0.020(-0.037, -0.003) for spine, -0.013(-0.026, 0.001) for total hip, -0.014(-0.028, 0.000) for femoral neck, and -0.013(-0.026, 0.000) for hip trochanter. For PFOA, the corresponding figures were -0.021(-0.038, -0.004) for spine, -0.015(-0.029, -0.001) for total hip, and -0.015(-0.029, -0.002) for femoral neck. After adjusting for baseline covariates and 2-year weight change, higher baseline plasma concentrations of PFOS, PFNA, and PFDA were associated with greater reduction in BMD in the hip; the βs (95% CIs) were -0.005(-0.009, -0.001), -0.006(-0.010, -0.001), and -0.005(-0.009, -0.001), respectively. Similar associations were found in hip intertrochanteric area for all PFASs except PFHxS, with βs ranging from -0.006 for PFOA to -0.008 for PFOS and PFNA. Participants with a higher GRS tended to have less PFAS-related BMD decline in total hip (P_interaction = 0.005) and the hip intertrochanteric area (P_interaction = 0.021). There were similar PFAS-related BMD changes by baseline BMI levels, although the interactions did not achieve statistical significance.

CONCLUSIONS

This study demonstrated that higher plasma PFAS concentrations were not only associated with a lower BMD at baseline, but also a faster BMD loss in a weight-loss trial setting. Genetic predisposition to larger body size may somewhat attenuate the deleterious effects of PFASs on BMD. Further exploration of the possible impact of PFAS exposures on bone density is warranted.

High melatonin levels are related to spinal ossification in patients with ankylosing spondylitis

Objectives: To investigate associations of serum melatonin with spinal ossification and cytokines in ankylosing spondylitis (AS).Methods: Serum was obtained from 52 AS patients and 25 healthy controls. Melatonin was measured by ELISA kit; bone morphogenetic protein (BMP)-2, dickkopf-related protein (Dkk)-1, IL-1β, IL-6, IL-17 and TNF-α concentrations were assayed using Luminex multiplex bead system. Osteocalcin and β isomer of C-terminal telopeptide of type I collagen (β-CTX) were measured using electrochemiluminescence immunoassay. Spinal damages were assessed using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) on radiographs.Results: Serum melatonin was significantly increased in AS patients. Serum melatonin correlated positively with mSASSS after multivariate adjustment for age and disease duration (r = 0.70, p < .01). Patients with spinal bone bridge have higher levels of melatonin than those without spinal bone bridge [16.69 (4.65, 41.10) pg/ml vs. 7.43 (3.29, 15.30) pg/ml, p = .03]. The multiple linear regression analysis found that melatonin was a risk factor for spinal bone formation (β = 0.35, p < .05). Additionally, melatonin correlated positively with osteocalcin (r = 0.34, p = .04) and IL-1β (r = 0.39, p = .04) in AS.Conclusion: Melatonin is increased in AS patients, especially in patients with spinal bone bridge. It suggests that melatonin may play an important role in the pathological osteogenesis of AS.

Immunomodulatory effects of synthetic endocrine disrupting chemicals on the development and functions of human immune cells

Endocrine disrupting chemicals (EDCs) are added to food, cosmetics, plastic packages, and children's toys and have thus become an integral part of the human environment. In the last decade, there has been increasing interest in the effect of EDCs on human health, including their impact on the immune system. So far, researchers have proved that EDCs (e.g. bisphenols, phthalates, triclosan, phenols, propanil, tetrachlorodibenzo-p-dioxin, diethylstilbestrol, tributyltin (TBT), and parabens) affect the development, functions, and lifespan of immune cells (e.g., monocytes, neutrophils, mast cells, eosinophils, lymphocytes, dendritic cells, and natural killers). In this review, we have summarized the current knowledge of the multivariable influence of EDCs on immune cells and underlined the novel approach to EDC studies, including dose-dependent effects and low-dose effects. We discuss critically the possible relationship between exposure to EDCs and immunity related diseases (e.g. allergy, asthma, diabetes, and lupus). Moreover, based on the literature, we construct a model of possible mechanisms of EDC action on immune cells at cellular, molecular, and epigenetic levels.