Bone disease in β thalassemia patients: past, present and future perspectives

Bone Health Impairment in Patients with Hemoglobinopathies: From Biological Bases to New Possible Therapeutic Strategies

Hemoglobinopathies are monogenic disorders affecting hemoglobin synthesis. Thalassemia and sickle cell disease (SCD) are considered the two major hemoglobinopathies. Thalassemia is a genetic disorder and one of the major hemoglobinopathies determined by an impairment of globin chain production, which causes an alteration of erythropoiesis, an improvement in hemolysis, and an alteration of iron homoeostasis. In SCD, the mutations are on the β-globin chain of hemoglobin which results in a substitution of glutamic acid by valine with consequent formation of Hemoglobin S (HbS). Several factors are involved in bone metabolism alteration in patients with hemoglobinopathies, among them hormonal deficiency, bone marrow hyperplasia, iron overload, inflammation, and increased bone turnover. Bone metabolism is the result of balance maintenance between bone deposition and bone resorption, by osteoblasts (OBs) and osteoclasts (OCs). An impairment of this balance is responsible for the onset of bone diseases, such as osteoporosis (OP). Therefore, here we will discuss the alteration of bone metabolism in patients with hemoglobinopathies and the possible therapeutic strategies to contain and/or counteract bone health impairment in these patients, taking into consideration not only the pharmacological treatments already used in the clinical armamentarium, but also the new possible therapeutic strategies.

Rehabilitation Strategies for Wrist Pain in a Patient With Thalassemia Major and Distal Ulnar Hypoplasia: A Case Report

This case study examines the rehabilitation process of a 24-year-old female patient with thalassemia major (TM), a hereditary hemoglobinopathy, who also suffered from distal ulnar hypoplasia, a congenital anomaly that causes pain and affects the wrist joint's strength and range of motion. The patient underwent a comprehensive physical rehabilitation program that aimed to address the challenges posed by ulnar hypoplasia. This program included a combination of customized exercises, splinting, and orthotic interventions to improve hand and wrist function. By adopting a multidisciplinary approach, the patient experienced significant improvements in mobility, strength, and overall quality of life. This case highlights the significance of personalized rehabilitation strategies in managing complex medical conditions, demonstrating the potential for positive outcomes even in patients with dual diagnoses of TM and ulnar hypoplasia.

Enhancing skeletal age estimation accuracy using support vector regression models

OBJECTIVE

The objective of the study was to determine if support vector regression (SVR) models could enhance the accuracy of skeletal age estimation compared to original metrics.

METHOD

The study used a dataset of 5,018 individuals from Wuhan, spanning ages 1 to 17. Optimal model parameters were found using cross-validation and grid search techniques. The study compared SVR-based bone age assessment metrics with original metrics and evaluated the performance of the SVR model across different sample sizes.

RESULTS

The findings unequivocally demonstrated SVR's superior reliability over original metrics in assessing bone age among children in central China. Regardless of the training set size, constructing SVR models based on TW3, CHN05, or a combination of TW3, CHN05, and GP consistently results in top-tier predictive accuracy.

CONCLUSION

This research highlights SVR's potential for accuracy improvement and robustness with limited datasets.

Iron accumulation induced by hepcidin1 knockout accelerates the progression of aging osteoporosis

OBJECTIVE

Iron accumulation is associated with osteoporosis. This study aims to explore the effect of chronic iron accumulation induced by hepcidin1 deficiency on aging osteoporosis.

METHODS

Iron accumulation in hepcidin1 knockout aging mice was assessed by atomic absorption spectroscopy and Perl's staining. Bone microarchitecture was observed using Micro-CT. Hepcidin, ferritin, oxidative stress, and markers of bone turnover in serum were detected by enzyme-linked immunosorbent assay. Bone formation and resorption markers were measured by real-time quantitative PCR. Cell aging was induced by D-galactose treatment. CCK-8, flow cytometry, EdU assays, and Alizarin red staining were performed to reveal the role of hepcidin1 knockout in cell model. Iron Colorimetric Assay Kit and western blot were applied to detect iron and ferritin levels in cells, respectively.

RESULTS

In hepcidin1-knockout mice, the ferritin and iron contents in liver and tibia were significantly increased. Iron accumulation induced by hepcidin1 knockout caused a phenotype of low bone mass and deteriorated bone microarchitecture. Osteogenic marker was decreased and osteoclast marker was increased in mice, accompanied by increased oxidative stress level. The mRNA expression levels of osteoclast differentiation markers (RANKL, Mmp9, OPG, Trap, and CTSK) were up-regulated, while bone formation markers (OCN, ALP, Runx2, SP7, and Col-1) were down-regulated in model group, compared to wild type mice. In vitro, hepcidin1 knockdown inhibited proliferation and osteogenic differentiation, while promoted apoptosis, with increased levels of iron and ferritin.

CONCLUSION

Iron accumulation induced by hepcidin1 deficiency aggravates the progression of aging osteoporosis via inhibiting osteogenesis and promoting osteoclast genesis.

Iron metabolism and ferroptosis in diabetic bone loss: from mechanism to therapy

Osteoporosis, one of the most serious and common complications of diabetes, has affected the quality of life of a large number of people in recent years. Although there are many studies on the mechanism of diabetic osteoporosis, the information is still limited and there is no consensus. Recently, researchers have proven that osteoporosis induced by diabetes mellitus may be connected to an abnormal iron metabolism and ferroptosis inside cells under high glucose situations. However, there are no comprehensive reviews reported. Understanding these mechanisms has important implications for the development and treatment of diabetic osteoporosis. Therefore, this review elaborates on the changes in bones under high glucose conditions, the consequences of an elevated glucose microenvironment on the associated cells, the impact of high glucose conditions on the iron metabolism of the associated cells, and the signaling pathways of the cells that may contribute to diabetic bone loss in the presence of an abnormal iron metabolism. Lastly, we also elucidate and discuss the therapeutic targets of diabetic bone loss with relevant medications which provides some inspiration for its cure.

Influence of systemic comorbidities on the complications of orthognathic surgery: A scoping review

The potential impact of systemic comorbidities has not yet been thoroughly explored in orthognathic surgery. Therefore, the following scoping review was conducted to accumulate evidence on the possible impact of systemic comorbidities on the orthognathic surgery complications. PubMed, Embase, Cochrane, and Web of Science databases were searched up to April 2022 to identify studies about patients with systemic comorbidities who underwent orthognathic surgery. A total of 12,938 articles were screened, and seven articles met the inclusion criteria. Only one study had control group, other six articles had a non-comparative study design. The current evidence suggests a high impact of rheumatic diseases and neuromuscular disorders on the surgery- and patient-related postoperative complications following orthognathic surgery. At the same instance, the findings of the review should be interpreted with caution due to a lack of substantial evidence for extrapolating the findings to a contemporary surgical practice.

Prevalence and risk factors of fractures in transfusion dependent thalassemia - A Hong Kong Chinese population cohort

Objective

To delineate the prevalence and associated risk factors of low BMD, osteoporosis/bone fragility and fracture in transfusion‐dependent thalassemia (TDT) in the Chinese population in Hong Kong.

Design, Patients and Measurements

A retrospective cohort study design was employed. Patients of TDT who had serial Hologic dual‐energy X‐ray absorptiometry (DXA) from 2010 to 2016 and received regular transfusion for at least 5 years were recruited. Clinical and biochemical data, from 5 years before the first DXA scan, were retrieved from the electronic record system of the Hospital Authority, till 30 June 2020. Low bone mineral density and osteoporosis/bone fragility are defined by the ISCD 2019 position guidelines.

Results

Seventy‐seven patients were included in the analysis. The fracture prevalence of TDT among the Chinese population in Hong Kong was 15.58%. Up to 55.84% of patients had low bone mineral density, and 5.19% patients had osteoporosis/bone fragility state. The median age at first fracture was 31.73 years (range 24.06–44.18 years). In the regression analysis, a higher log(10) transformation of average ferritin levels over 5 years before the first DXA scan was significantly associated with fracture occurrence regardless of bisphosphonate treatment (OR 310.73, 95% CI 3.99–24183.89, p = .010). Mean average ferritin level over 5 years was 6695.5 ± 2365.7 pmol/L (fracture group) versus 4350.7 ± 3103.2 pmol/L (non‐fracture group), p = .016. Hip and spine BMD Z‐score did not have statistically significant association with fracture occurrence.

Conclusion

Iron overloading plays an important role in adverse bone health in TDT. Dual X‐ray densitometry is insufficient in predicting fracture risk.

High phosphate intake induces bone loss in nephrectomized thalassemic mice

Although patients with either β-thalassemia or chronic kidney disease (CKD) clinically correlate with severe osteoporosis, the mechanism by which CKD exposed to high phosphate affects bone turnover has not been characterized in β-thalassemia. We aimed to determine the effects of renal insufficiency on high phosphate intake induced changes in bone metabolism after 5/6th nephrectomy in hemizygous β-globin knockout (BKO) mice. Male BKO mice manifested severe anemia and osteopenia. Nephrectomy induced renal fibrosis and reduced renal function as assessed by increased serum urea nitrogen levels. Moreover, nephrectomy increased bone turnover leading to bone loss in wild type (WT) but not BKO mice. In nephrectomized BKO, PBS in drinking water induced hyperphosphatemia, and hypercalcemia along with osteopenia in both cancellous and cortical bone. Histomorphometric analysis confirmed reduced cancellous bone volume due to decreased bone formation rate, osteoblast number and osteoclast number. The mRNA levels for Alpl, Sp7, Kl, Tnfsf11, and Tnfsf11/Tnfrsf11b were decreased in nephrectomized BKO mice drinking PBS. Interestingly, Fgf23, a bone-derived hormone produced by osteocytes and osteoblasts in response to hyperphosphatemia, were remarkably increased in nephrectomized BKO mice following PBS intake. Serum FGF23 and erythropoietin levels were markedly elevated in BKO mice. Nephrectomy decreased serum erythropoietin but not FGF23 levels. Hyperphosphatemia in BKO mice increased serum erythropoietin, FGF23, and PTH levels, nominating these factors as candidate mediators of bone loss in thalassemic mice with CKD during phosphate retention.

Mild-intensity physical activity prevents cardiac and osseous iron deposition without affecting bone mechanical property or porosity in thalassemic mice

Thalassemia causes anemia, ineffective erythropoiesis, bone loss and iron accumulation in several tissues, e.g., liver, bone and heart, the last of which leads to lethal cardiomyopathy and arrhythmia. Although exercise reportedly improves bone density in thalassemic mice, exercise performance is compromised and might pose risk of cardiovascular accident in thalassemic patients. Therefore, we sought to explore whether mild-intensity physical activity (MPA) with 30–50% of maximal oxygen consumption was sufficient to benefit the heart and bone. Herein, male hemizygous β-globin knockout (BKO) mice and wild-type littermates were subjected to voluntary wheel running 1 h/day, 5 days/week for 3 months (MPA group) or kept sedentary (SDN; control). As determined by atomic absorption spectroscopy, BKO-MPA mice had less iron accumulation in heart and bone tissues compared with BKO-SDN mice. Meanwhile, the circulating level of fibroblast growth factor-23—a factor known to reduce serum iron and intestinal calcium absorption—was increased early in young BKO-MPA mice. Nevertheless, MPA did not affect duodenal calcium transport or body calcium retention. Although MPA restored the aberrant bone calcium-phosphorus ratio to normal range, it did not change vertebral calcium content or femoral mechanical properties. Microstructural porosity in tibia of BKO-MPA mice remained unaltered as determined by synchrotron radiation X-ray tomographic microscopy. In conclusion, MPA prevents cardiac and bone iron accumulation, which is beneficial to thalassemic patients with limited physical fitness or deteriorated cardiac performance. However, in contrast to moderate-intensity exercise, MPA does not improve bone mechanical properties or reduce bone porosity.

Musculoskeletal imaging manifestations of beta-thalassemia

Beta-thalassemia is a heterogeneous group of anemic disorders caused by the absence or defective production of beta-globin chains. Their clinical manifestations vary from asymptomatic to severe symptoms leading to a transfusion-dependent anemic state. The genes that cause thalassemia are prevalent in Asian and African populations, particularly concentrated in the Middle East, Mediterranean region, parts of India, and South East Asia. Over time, the disease causes various musculoskeletal abnormalities with complex pathophysiology secondary to chronic anemia. The compensatory mechanisms result in diffuse marrow hyperplasia, yellow to red marrow reconversion, osteopenia, and pathologic fractures. Inability to remove excess iron and inevitable iron overload as a result of multiple blood transfusions in patients with thalassemia major and intermedia is another face of the disease. Musculoskeletal manifestations include osteopenia, coarse trabeculae, bone expansion, synovitis, joint effusion, and metaphyseal dysplasia. These complications have long-lasting effects on the skeletal growth pattern resulting in bone deformity, short stature, premature closure of physes, and predisposition to infection. Additionally, there are radiologic features of iron-chelator therapy, which are unique and unrelated to the disease process itself. Familiarity of radiologists with the imaging features of beta-thalassemia is crucial in both diagnosis and timely management of the disease and its complications.

Vitamin D and bone health status in beta thalassemia patients-systematic review

Thalassemia is a chronic congenital disease characterized by a combination of endocrine and metabolic disorders. Bone disease is a very common complication related to the poor absorption of calcium, the secondary chronic renal disease with low vitamin D, as well as multiple endocrine risk factors. The aim of this systematic review was to estimate the prevalence of vitamin D deficiency in thalassemia, as well as its association with osteoporosis/low bone mass. A systematic review was carried out using PubMed/Medline, Cochrane, and EBSCO databases. The methodological quality of the included studies was assessed with the validated Newcastle-Ottawa Quality Assessment Scale adapted for cross-sectional studies and cohort studies respectfully and the Cochrane Collaboration for clinical trials. After application of predetermined exclusion criteria compatible with the PICOS process, a total of 12 suitable articles were identified. The prevalence of vitamin D deficiency varied considerably. Only five of the reviewed studies examined the correlation between vitamin D levels and BMD of which just three showed a statistically significant positive association of mild/moderate grade. Vitamin D deficiency is a common comorbidity in patients with thalassemia. However, both its prevalence and its severity vary considerably in different populations, and existing evidence is insufficient to conclude whether vitamin D supplementation is also associated with BMD improvement in this special population group.

Therapeutic potential of iron chelators on osteoporosis and their cellular mechanisms

Iron is an essential trace element in the metabolism of almost all living organisms. Iron overload can disrupt bone homeostasis by significant inhibition of osteogenic differentiation and stimulation of osteoclastogenesis, consequently leading to osteoporosis. Iron accumulation is also involved in the osteoporosis induced by multiple factors, such as estrogen deficiency, ionizing radiation, and mechanical unloading. Iron chelators are first developed for treating iron overloaded disorders. However, growing evidence suggests that iron chelators can be potentially used for the treatment of bone loss. In this review, we focus on the therapeutic effects of iron chelators on bone loss. Iron chelators have therapeutic effects not only on iron overload induced osteoporosis, but also on osteoporosis induced by estrogen deficiency, ionizing radiation, and mechanical unloading, and in Alzheimer's disease-associated osteoporotic deficits. Iron chelators differently affect the cellular behaviors of bone cells. For osteoblast lineage cells (bone mesenchymal stem cells and osteoblasts), iron chelation stimulates osteogenic differentiation. Conversely, iron chelation significantly inhibits osteoclast differentiation. These different responses may be associated with the different needs of iron during differentiation. Fibroblast growth factor 23, angiogenesis, and antioxidant capability are also involved in the osteoprotective effects of iron chelators.

Neuroimaging in Sickle Cell Disease: A Review

Sickle cell disease is the most common hereditary hemoglobinopathy, which results in abnormally shaped and rigid red blood cells. These sickle-shaped red blood cells cause vaso-occlusion and ischemic phenomena that can affect any organ in the body. As a common cause of disability, the neurological manifestations of sickle cell disease are particularly important. Neuroimaging has a crucial role in the diagnosis, management, and prevention of the complications of sickle cell disease. These complications can affect the brain parenchyma, vasculature, and skull and can be ascribed directly or indirectly to a vasculopathy of small and large vessels. Vaso-occlusion can cause ischemic stroke. Ischemic damage in the absence of an acute neurological deficit, and therefore only apparent on neuroimaging, is termed silent cerebral ischemia. Weakening of the arterial walls can cause aneurysms. In its most severe form, a vasculopathy of the terminal internal carotid arteries can progress to moyamoya syndrome, characterized by steno-occlusive disease and the formation of friable collateral arteries. Rupture of aneurysms or friable collateral arteries is a potential cause of intracranial hemorrhage. The skull and vertebrae may be affected by extra-medullary hematopoiesis, due to severe anemia, or iron deposition, due to chronic red blood cell transfusion. Impaired blood supply to bone is associated with osteomyelitis and osteonecrosis. Fat embolization syndrome is a rare complication of osteonecrosis, which may cause devastating neurological impairment. Awareness and early recognition of the diverse manifestations of sickle cell disease on neuroimaging is crucial to ensure optimal treatment in a complex patient cohort.

Management of primary and secondary osteoporosis in children

Osteoporosis in children differs from adults in terms of definition, diagnosis, monitoring and treatment options. Primary osteoporosis comprises primarily of osteogenesis imperfecta (OI), but there are significant other causes of bone fragility in children that require treatment. Secondary osteoporosis can be a result of muscle disuse, iatrogenic causes, such as steroids, chronic inflammation, delayed or arrested puberty and thalassaemia major. Investigations involve bone biochemistry, dual-energy X-ray absorptiometry scan for bone densitometry and vertebral fracture assessment, radiographic assessment of the spine and, in some cases, quantitative computed tomography (QCT) or peripheral QCT. It is important that bone mineral density (BMD) results are adjusted based on age, gender and height, in order to reflect size corrections in children. Genetics are being used increasingly for the diagnosis and classification of various cases of primary osteoporosis. Bone turnover markers are used less frequently in children, but can be helpful in monitoring treatment and transiliac bone biopsy can assist in the diagnosis of atypical cases of osteoporosis. The management of children with osteoporosis requires a multidisciplinary team of health professionals with expertise in paediatric bone disease. The prevention and treatment of fragility fractures and improvement of the quality of life of patients are important aims of a specialised service. The drugs used most commonly in children are bisphosphonates, that, with timely treatment, can give good results in improving BMD and reshaping vertebral fractures. The data regarding their effect on reducing long bone fractures are equivocal. Denosumab is being used increasingly for various conditions with mixed results. There are more drugs trialled in adults, but these are not yet licenced for children. Increasing awareness of risk factors for paediatric osteoporosis, screening and referral to a specialist team for appropriate management can lead to early detection and treatment of asymptomatic fractures and prevention of further bone damage.

Bone mineral density among Palestinian patients suffering from hemoglobinopathy disorders

This study aimed to investigate the correlation between bone mineral density (BMD) with hemoglobin and ferritin levels in Palestinian patients suffering from various types of hemoglobinopathies. The study revealed the thresholds of hemoglobin and ferritin to protect against low BMD in these patients.

PURPOSE

Iron overload is the main cause of low BMD in subjects with hemoglobinopathies. We used iron overload-related parameters like hemoglobin and ferritin to estimate the cutoff values required to maintain bone health and identify subjects with low BMD.

METHODS

Palestinian patients (135) suffering from various types of hemoglobinopathies were recruited from various medical centers including 87 β thalassemia major (TM), 13 thalassemia intermedia (TI), 16 sickle cell anemia (SCA), 17 sickle cell thalassemia (SCT), and 1 thalassemia trait (TT). Most subjects (84%) were below the age of 30 years. BMD was measured and the z score was used to identify subjects with low BMD (z < - 2.0). Receiver operator characteristic (ROC) curve analysis was used to estimate the thresholds of hemoglobin and ferritin levels needed to protect against low BMD in these patients.

RESULTS

No difference in means of age, weight, BMI, hemoglobin, and ferritin levels among the recruited male and female subjects were observed. The results showed that 77% of TM subjects had low BMD levels and femoral neck and total hip BMD were significantly lower among female compared to male subjects. Thalassemia patients (TM, TI, and SCT combined) had significantly low BMD and lower hemoglobin mean values compared to normal BMD subjects (8.54 vs. 9.25 g/dL, p = 0.01). Pearson's correlation analysis showed positive correlation between hemoglobin levels and BMD at the three sites, being higher with lumbar spine (r = 0.444) compared to femoral neck (r = 0.291) and total hip (r = 0.224). Ferritin levels in TM patients (4800 ng/ml) and TI subjects (1500 ng/ml) were abnormally high. ROC curve analysis showed that hemoglobin threshold ≤ 9.3 g/dL represents a risk for developing low BMD with an area under the ROC curve (AUC) 0.699 and sensitivity and specificity were 87.9% and 47.7%, respectively. Similar analysis revealed that Ferritin threshold to protect against low BMD should be maintained below 2300 ng/ml with AUC 0.619 and sensitivity and specificity were 55.0% and 71.4%, respectively.

CONCLUSIONS

The results of this study strongly recommend to maintain hemoglobin levels above 9.3 g/dL and ferritin below 2300 ng/ml to protects against low BMD in TM subjects and patients suffering from the other related hemoglobinopathies.

ROS-Mediated Necroptosis Is Involved in Iron Overload-Induced Osteoblastic Cell Death

Excess iron has been reported to lead to osteoblastic cell damage, which is a crucial pathogenesis of iron overload-related osteoporosis. However, the cytotoxic mechanisms have not been fully documented. In the present study, we focused on whether necroptosis contributes to iron overload-induced osteoblastic cell death and related underlying mechanisms. Here, we showed that the cytotoxicity of iron overload in osteoblastic cells was mainly due to necrosis, as evidenced by the Hoechst 33258/PI staining, Annexin-V/PI staining, and transmission electronic microscopy. Furthermore, we revealed that iron overload-induced osteoblastic necrosis might be mediated via the RIPK1/RIPK3/MLKL necroptotic pathway. In addition, we also found that iron overload was able to trigger mitochondrial permeability transition pore (mPTP) opening, which is a critical downstream event in the execution of necroptosis. The key finding of our experiment was that iron overload-induced necroptotic cell death might depend on reactive oxygen species (ROS) generation, as N-acetylcysteine effectively rescued mPTP opening and necroptotic cell death. ROS induced by iron overload promote necroptosis via a positive feedback mechanism, as on the one hand N-acetylcysteine attenuates the upregulation of RIPK1 and RIPK3 and phosphorylation of RIPK1, RIPK3, and MLKL and on the other hand Nec-1, siRIPK1, or siRIPK3 reduced ROS generation. In summary, iron overload induced necroptosis of osteoblastic cells in vitro, which is mediated, at least in part, through the RIPK1/RIPK3/MLKL pathway. We also highlight the critical role of ROS in the regulation of iron overload-induced necroptosis in osteoblastic cells.

Carbonyl iron and iron dextran therapies cause adverse effects on bone health in juveniles with chronic kidney disease

Anemia is a frequent complication of chronic kidney disease (CKD), related in part to the disruption of iron metabolism. Iron therapy is very common in children with CKD and excess iron has been shown to induce bone loss in non-CKD settings, but the impact of iron on bone health in CKD remains poorly understood. Here, we evaluated the effect of oral and parenteral iron therapy on bone transcriptome, bone histology and morphometry in two mouse models of juvenile CKD (adenine-induced and 5/6-nephrectomy). Both modalities of iron therapy effectively improved anemia in the mice with CKD, and lowered bone Fgf23 expression. At the same time, iron therapy suppressed genes implicated in bone formation and resulted in the loss of cortical and trabecular bone in the mice with CKD. Bone resorption was activated in untreated CKD, but iron therapy had no additional effect on this. Furthermore, we assessed the relationship between biomarkers of bone turnover and iron status in a cohort of children with CKD. Children treated with iron had lower levels of circulating biomarkers of bone formation (bone-specific alkaline phosphatase and the amino-terminal propeptide of type 1 procollagen), as well as fewer circulating osteoblast precursors, compared to children not treated with iron. These differences were independent of age, sex, and glomerular filtration rate. Thus, iron therapy adversely affected bone health in juvenile mice with CKD and was associated with low levels of bone formation biomarkers in children with CKD.

Toxicological and pharmacological assessment of a multiherbal phytopharmaceutical on Triton X-1339-induced hyperlipidemia and allied biochemical dysfunctions

This study investigated the safety and therapeutic effect of a multiherbal tea (MHT) on Triton X-1339-induced hyperlipidemia and associated biochemical and tissue dysfunctions. An infusion of the MHT was assessed for phytoconstituents, proximate and mineral composition, and antioxidant activity. Wistar rats administered 200 mg/kg Triton X-1399 were post-treated with MHT for 14 days followed by biochemical estimations in serum, heart, liver, and kidney of animals. Hematological and histopathological evaluations of the blood, and liver, respectively, were also performed. Different phytochemicals were detected in MHT, toxic metals were absent and antioxidant activity was appreciable. Disturbances in glucose level and redox homeostasis, alterations in liver, kidney, and heart function markers, and imbalances in hematological parameters precipitated by triton toxicity were mitigated by posttreatment with MHT. Multiherbal tea also ameliorated triton-induced hepatic histoarchitectural abnormalities. These results suggest that MHT is apparently an effective antilipemic tea with minimal or no side effects. PRACTICAL APPLICATIONS: Hyperlipidemia is one of the core risk factors for arteriosclerosis and a major contributor to other adverse health conditions. The prevalence of hyperlipidemia has increased drastically in the last few decades. Plant and plant products have been extensively used in the management of dyslipidemia and many plant-based antilipemic products with poorly defined toxicity and pharmacological profiles abound in the market. The results of this study demonstrated the protective effects of a MHT against triton-induced hyperlipidemia, atherogenic tendency, and dysfunction of key organs in rats and lent credence to its therapeutic relevance in the management of hyperlipidemia and related diseases.

Deterioration of hematopoietic autophagy is linked to osteoporosis

Hematopoietic disorders are known to increase the risk of complications such as osteoporosis. However, a direct link between hematopoietic cellular disorders and osteoporosis has been elusive. Here, we demonstrate that the deterioration of hematopoietic autophagy is coupled with osteoporosis in humans. With a conditional mouse model in which autophagy in the hematopoietic system is disrupted by deletion of the Atg7 gene, we show that incapacitating hematopoietic autophagy causes bone loss and perturbs osteocyte homeostasis. Induction of osteoporosis, either by ovariectomy, which blocks estrogen secretion, or by injection of ferric ammonium citrate to induce iron overload, causes dysfunction in the hematopoietic stem and progenitor cells (HSPCs) similar to that found in autophagy‐defective mice. Transcriptomic analysis of HSPCs suggests promotion of iron activity and inhibition of osteocyte differentiation and calcium metabolism by hematopoietic autophagy defect, while proteomic profiling of bone tissue proteins indicates disturbance of the extracellular matrix pathway that includes collagen family members. Finally, screening for expression of selected genes and an immunohistological assay identifies severe impairments in H vessels in the bone tissue, which results in disconnection of osteocytes from hematopoietic cells in the autophagy‐defective mice. We therefore propose that hematopoietic autophagy is required for the integrity of H vessels that bridge blood and bone cells and that its deterioration leads to osteoporosis.

The changing epidemiology of the ageing thalassaemia populations: A position statement of the Thalassaemia International Federation

Therapeutic advances in β-thalassaemia have gradually lead to a significant improvement in prognosis over the past few decades. As a result, patients living in areas where disease-specific programmes offering access to modern therapy are in place experience a new era of prolonged survival that tends to reach that of the normal population. This ageing thalassaemia population, however, faces a new spectrum of comorbidities resulting from increasing age that may jeopardise the advances in prognosis provided by current therapy and thus poses new challenges in diagnosis, monitoring and treatment. In this position paper of the Thalassaemia International Federation, we review the changing epidemiology and clinical spectrum of patients with β-thalassaemia and propose actions to be undertaken in order to address the emerging spectrum of comorbidities resulting from ageing.

Iron Overload Associated Endocrine Dysfunction Leading to Lower Bone Mineral Density in Thalassemia Major

CONTEXT

Patients with thalassemia major (TM) have a lower bone mineral density (BMD) and higher risk of fracture than the general population. The possible mechanisms include anemia, iron overload, malnutrition, and hormonal deficiency, but these have not been thoroughly investigated.

OBJECTIVE

To identify major mineral and hormonal factors related to BMD in adult TM patients to provide human evidence for the proposed mechanisms.

DESIGN

Retrospective study.

SETTING

Referral center.

PATIENTS

Twenty-nine patients with β-TM, aged 23 to 44 years who were followed-up during 2017 to 2018 were enrolled.

OUTCOME MEASUREMENTS

Endocrine profiles, including thyroid, parathyroid, and pituitary function, glucose, vitamin D, calcium, phosphate, and fibroblast growth factor 23 (FGF23) were obtained. The relationships among the above parameters, body height, fractures, and BMD were analyzed.

RESULTS

Abnormal BMD was observed in 42.9% of women and 23.1% of men. The mean final heights of women and men were 3.7 cm and 7.3 cm lower than the mean expected values, respectively. Fracture history was recorded in 26.7% of women and 35.7% of men. BMD was negatively correlated with parathyroid hormone, FGF23, thyrotropin, and glycated hemoglobin (HbA1c) levels, and positively correlated with testosterone, IGF-1, and corticotropin levels (all P < .05). Moreover, hypothyroidism was associated with lower BMD in both the lumbar spine (P = .024) and the femoral neck (P = .004). Patients with hypothyroidism had a higher percentage of abnormal BMD (P = .016).

CONCLUSION

Hypothyroidism, higher HbA1c, and lower adrenocorticotropin were predictors of abnormal BMD in patients with β-TM. Whether the correction of these factors improves BMD warrants further research.

Prevalence of endocrine disorders and their associated factors in transfusion-dependent thalassemia patients: a historical cohort study in Southern Iran

PURPOSE

Transfusion-dependent beta-thalassemia (TDT) patients suffer from various endocrinopathies. The main contributing factor associated with these complications is iron overload, secondary to frequent blood transfusions. To improve patients' quality of life, we evaluated the prevalence of endocrine disorders while considering the associated factors for further assessment.

METHODS

Seven hundred thirteen transfusion-dependent thalassemia patients with age range 10-62 years were enrolled in this study. Serum calcium, phosphorous, fast blood sugar, ferritin, 25-OH vitamin D, free thyroxin, thyroid-stimulating hormone and parathyroid hormone were assessed. Bone mineral density was measured by dual-energy X-ray absorptiometry.

RESULTS

In total, 86.8% of the TDT patients suffered from at least one endocrinopathy. The prevalence of endocrinopathies in descending order of frequency was low bone mass (72.6%), hypogonadism (44.5%), diabetes mellitus (15.9%), hypoparathyroidism (13.2%), and hypothyroidism (10.7%). Age, body mass index and splenectomy were significantly associated with most of the endocrine disorders.

CONCLUSION

Endocrine complications are frequently observed in TDT patients. Splenectomy is a major risk factor and should be generally avoided unless it is highly indicated. Periodic surveillance of endocrine function and proper management of iron overload are advised.

Comparative effectiveness of alendronate and zoledronic acid on bone mass improvement in transfusion-dependent thalassemia patients

Thalassemia, as the most prevalent genetic blood disorder, has many associated comorbidities including low bone mass. We studied the comparative effectiveness of alendronate (AL) and zoledronic acid (ZOL) on bone mass improvement in transfusion-dependent thalassemia (TDT) patients a year after treatment. Three hundred seventy-five TDT patients with low bone mass were enrolled in this study. After a year of treatment with either AL or ZOL, a second bone mineral density (BMD) test was ordered to compare the effectiveness of the two aforementioned drugs. Body mass index (BMI), physical activity, sun exposure, and biochemical laboratory data were also considered as associated factors in this study. The BMD test of both groups was almost the same at the baseline and it increased comparably after a year of treatment with AL and ZOL. However, there was a significant difference in lumbar spine BMD delta Z score between both groups of female patients. ZOL was more effective in increasing the lumbar spine BMD of female patients. The choice of bisphosphonates therapy (oral versus parenteral) should be individually selected by considering patient's preference, compliance and the physician's decision. Given the longer administration interval, and TDT patients' compliance issue, it is justified to recommend ZOL as the drug of choice for patients suffering from low bone mass.

Responses of primary osteoblasts and osteoclasts from hemizygous β-globin knockout thalassemic mice with elevated plasma glucose to 1,25-dihydroxyvitamin D3

β-thalassemia is often associated with hyperglycemia, osteoporosis and increased fracture risk. However, the underlying mechanisms of the thalassemia-associated bone loss remain unclear. It might result from abnormal activities of osteoblasts and osteoclasts, and perhaps prolonged exposure to high extracellular glucose. Herein, we determined the rate of duodenal calcium transport in hemizygous β-globin knockout thalassemic (BKO) mice. Their bones were collected for primary osteoblast and osteoclast culture. We found that BKO mice had lower calcium absorption than their wild-type (WT) littermates. Osteoblasts from BKO mice showed aberrant expression of osteoblast-specific genes, e.g., Runx2, alkaline phosphatase and osteocalcin, which could be partially restored by 1,25(OH)₂D₃ treatment. However, the mRNA expression levels of RANK, calcitonin receptor (Calcr), c-Fos, NFATc1, cathepsin K and DMT1 were similar in both BKO and WT groups. Exposure to high extracellular glucose modestly but significantly affected the expression of osteoclast-specific markers in WT osteoclasts with no significant effect on osteoblast-specific genes in WT osteoblasts. Thus, high glucose alone was unable to convert WT bone cells to BKO-like bone cells. In conclusion, the impaired calcium absorption and mutation-related aberrant bone cell function rather than exposure to high blood glucose were likely to be the principal causes of thalassemic bone loss.

Denosumab in transfusion-dependent thalassemia osteoporosis: a randomized, placebo-controlled, double-blind phase 2b clinical trial

Denosumab (DNM) is a fully human monoclonal antibody against the receptor activator of nuclear factor kappa-B ligand (RANKL) that has been licensed for the treatment of different types of osteoporosis. However, the prospective data for the evaluation of DNM efficacy on transfusion-dependent thalassemia (TDT)-induced osteoporosis are rather limited. Thus, we conducted a randomized, placebo-controlled, double-blind, phase 2b clinical trial to evaluate DNM in TDT osteoporosis. Patients were assigned to receive either 60 mg DNM (n = 32) or placebo (n = 31) subcutaneously on day 0 and 180 during a total of 12 months of follow-up. The percentage increase of L1-L4 bone mineral density was higher in the DNM group than the placebo group (5.92% ± 5.25% vs 2.92% ± 5.56%, respectively; P = .043), whereas the advantage of DNM regarding wrist bone mineral density was much higher compared with placebo (-0.26% ± 5.31% vs -3.92% ± 8.71%, respectively; P = .035). No grade 3 or 4 toxicity was observed. DNM reduced pain scores that remained unaltered in the placebo group. DNM showed a significant reduction of soluble RANKL (sRANKL), sRANKL/osteoprotegerin ratio, C-telopeptide of collagen type I, tartrate-resistant acid phosphatase isoform-5b, and bone-specific alkaline phosphatase between baseline and the 12th month (P < .01 for all comparisons) without changes in dickkopf-1, sclerostin, and osteocalcin. On the contrary, placebo patients showed an increase in sRANKL, osteoprotegerin, dickkopf-1, sclerostin, C-telopeptide of collagen type I, tartrate-resistant acid phosphatase isoform-5b, and bone-specific alkaline phosphatase during the study period (P < .01 for all comparisons). In conclusion, DNM increased lumbar spine and wrist bone mineral density and reduced pain and bone remodeling markers, and thus it is another valuable option for the management of TDT-induced osteoporosis. This trial was registered at www.clinicaltrials.gov as #NCT02559648.

Marital status and paternity in patients with Transfusion- Dependent Thalassemia (TDT) and Non Transfusion-Dependent Thalassemia (NTDT): an ICET - A survey in different countries

BACKGROUND

More than five decades ago, thalassemia major (TDT) was fatal in the first decade of life. Survival and quality of life have improved progressively thanks to the implementation of a significant advance in diagnostic and therapeutic methods, consisting mainly of a frequent transfusion program combined with intensive chelation therapy. Improvement also includes imaging methods used to measure liver and cardiac iron overload. Improved survival has led to a growing number of adults requiring specialised care and counselling for specific life events, such as sexual maturity and acquisition of a family.

AIMS OF THE STUDY

The main aim is to present the results of a survey on the marital and paternity status in a large population of adult males with TDT and NTDT living in countries with a high prevalence of thalassemia and a review of current literature using a systematic search for published studies.

RESULTS

Ten out of 16 Thalassemia Centres (62.5%) of the ICET-A Network, treating a total of 966 male patients, aged above 18 years with β- thalassemias (738 TDT and 228 NTDT), participated in the study. Of the 966 patients, 240 (24.8%) were married or lived with partners, and 726 (75.2%) unmarried. The mean age at marriage was 29.7 ± 0.3 years. Of 240 patients, 184 (76.6%) had children within the first two years of marriage (2.1 ± 0.1 years, median 2 years, range 1.8 - 2.3 years). The average number of children was 1.32 ± 0.06 (1.27 ± 0.07 in TDT patients and 1.47 ± 0.15 in NTDT patients; p: >0.05). Whatever the modality of conception, 184 patients (76.6%) had one or two children and 1 NTDT patient had 6 children. Nine (4.8%) births were twins. Of 184 patients, 150 (81.5%) had natural conception, 23 (12.5%) required induction of spermatogenesis with gonadotropins (hCG and hMG), 8 (4.3%) needed intracytoplasmic sperm injection (ICSI) and 3 adopted a child. 39 patients with TDT and NTDT asked for medical help as they were unable to father naturally: 7 TDT patients (17.9%) were azoospermic, 17 (37.7%) [13 with TDT and 4 with NTDT] had dysspermia and 15 (33.3%) [13 with TDT and 2 with NTDT] had other "general medical and non-medical conditions".

CONCLUSIONS

Our study provides detailed information in a novel area where there are few contemporary data. Understanding the aspects of male reproductive health is important for physicians involved in the care of men with thalassemias to convey the message that prospects for fatherhood are potentially good due to progressive improvements in treatment regimens and supportive care.

Despite Genetic Iron Overload, Hfe-Hemochromatosis Mice Do Not Show Bone Loss

One of the most prevalent genetic iron overload disorders in Caucasians is caused by mutations in the HFE gene. Both HFE patients and Hfe‐mouse models develop a progressive accumulation of iron in the parenchymal cells of various tissues, eventually resulting in liver cirrhosis, hepatocellular carcinoma, cardiomyopathies, hypogonadism, and other pathologies. Clinical data and preclinical models have brought considerable attention to the correlation between iron overload and the development of osteoporosis in HFE/Hfe hemochromatosis. Our study critically challenges this concept. We show that systemic iron overload, at the degree present in Hfe^−/− mice, does not associate with the microarchitecture impairment of long bones, thus excluding a negative effect of iron overload on bone integrity. We further reveal that Hfe actions in osteoblasts and osteoclasts are dispensable for the maintenance of bone and iron homeostasis in mice under steady‐state conditions. We conclude that, despite systemic iron overload, Hfe^−/− mice present normal physiological bone homeostasis. © 2019 The Authors. JBMR Plus in published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

The EPO-FGF23 Signaling Pathway in Erythroid Progenitor Cells: Opening a New Area of Research

We provide an overview of the evidence for an erythropoietin-fibroblast growth factor 23 (FGF23) signaling pathway directly influencing erythroid cells in the bone marrow. We outline its importance for red blood cell production, which might add, among others, to the understanding of bone marrow responses to endogenous erythropoietin in rare hereditary anemias. FGF23 is a hormone that is mainly known as the core regulator of phosphate and vitamin D metabolism and it has been recognized as an important regulator of bone mineralization. Osseous tissue has been regarded as the major source of FGF23. Interestingly, erythroid progenitor cells highly express FGF23 protein and carry the FGF receptor. This implies that erythroid progenitor cells could be a prime target in FGF23 biology. FGF23 is formed as an intact, biologically active protein (iFGF23) and proteolytic cleavage results in the formation of the presumed inactive C-terminal tail of FGF23 (cFGF23). FGF23-knockout or injection of an iFGF23 blocking peptide in mice results in increased erythropoiesis, reduced erythroid cell apoptosis and elevated renal and bone marrow erythropoietin mRNA expression with increased levels of circulating erythropoietin. By competitive inhibition, a relative increase in cFGF23 compared to iFGF23 results in reduced FGF23 receptor signaling and mimics the positive effects of FGF23-knockout or iFGF23 blocking peptide. Injection of recombinant erythropoietin increases FGF23 mRNA expression in the bone marrow with a concomitant increase in circulating FGF23 protein. However, erythropoietin also augments iFGF23 cleavage, thereby decreasing the iFGF23 to cFGF23 ratio. Therefore, the net result of erythropoietin is a reduction of iFGF23 to cFGF23 ratio, which inhibits the effects of iFGF23 on erythropoiesis and erythropoietin production. Elucidation of the EPO-FGF23 signaling pathway and its downstream signaling in hereditary anemias with chronic hemolysis or ineffective erythropoiesis adds to the understanding of the pathophysiology of these diseases and its complications; in addition, it provides promising new targets for treatment downstream of erythropoietin in the signaling cascade.

Understanding and managing secondary osteoporosis

INTRODUCTION

The term secondary osteoporosis (SO) identifies a reduction of bone mass related to a well-established disease or pharmacological agent. The identification of the underlying disease often represents a challenging situation in clinical practice.

AREAS COVERED

The prevalence of SO in the real world may vary, ranging from 17% to 80%; therefore, search for a form of SO represents a pillar when evaluating patients with osteoporosis. Guidelines for treatment of specific secondary forms of osteoporosis, such as glucocorticoid-induced osteoporosis, have been published even though often neglected in clinical practice. For the majority of SO, there are currently no specific guidelines concerning treatment with only few trials showing the effect of bone-active drugs on fracture risk reduction.

EXPERT OPINION

Healthcare professionals should be aware of the secondary forms of osteoporosis, in particular when the reason for reduced skeletal resistance is uncertain or when bone mineral density results are unsatisfactory in a patient compliant to therapy. In a few cases (such as, for example: no response to therapy, better classification of bone involvement in patients with kidney failure, suspicion of rare metabolic bone disease) bone biopsy is needed to investigate the patient. This review highlights recent advances in understanding and managing SO.

Bone marrow stromal cells from β-thalassemia patients have impaired hematopoietic supportive capacity

BACKGROUND. The human bone marrow (BM) niche contains a population of mesenchymal stromal cells (MSCs) that provide physical support and regulate hematopoietic stem cell (HSC) homeostasis. β-Thalassemia (BT) is a hereditary disorder characterized by altered hemoglobin beta-chain synthesis amenable to allogeneic HSC transplantation and HSC gene therapy. Iron overload (IO) is a common complication in BT patients affecting several organs. However, data on the BM stromal compartment are scarce.

METHODS. MSCs were isolated and characterized from BM aspirates of healthy donors (HDs) and BT patients. The state of IO was assessed and correlated with the presence of primitive MSCs in vitro and in vivo. Hematopoietic supportive capacity of MSCs was evaluated by transwell migration assay and 2D coculture of MSCs with human CD34⁺ HSCs. In vivo, the ability of MSCs to facilitate HSC engraftment was tested in a xenogenic transplant model, whereas the capacity to sustain human hematopoiesis was evaluated in humanized ossicle models.

RESULTS. We report that, despite iron chelation, BT BM contains high levels of iron and ferritin, indicative of iron accumulation in the BM niche. We found a pauperization of the most primitive MSC pool caused by increased ROS production in vitro which impaired MSC stemness properties. We confirmed a reduced frequency of primitive MSCs in vivo in BT patients. We also discovered a weakened antioxidative response and diminished expression of BM niche–associated genes in BT-MSCs. This caused a functional impairment in MSC hematopoietic supportive capacity in vitro and in cotransplantation models. In addition, BT-MSCs failed to form a proper BM niche in humanized ossicle models.

CONCLUSION. Our results suggest an impairment in the mesenchymal compartment of BT BM niche and highlight the need for novel strategies to target the niche to reduce IO and oxidative stress before transplantation.

FUNDING. This work was supported by the SR-TIGET Core grant from Fondazione Telethon and by Ricerca Corrente.

The experience of a tertiary unit on the clinical phenotype and management of hypogonadism in female adolescents and young adults with transfusion dependent thalassemia

BACKGROUND

Transfusion-dependent β-thalassemia (TDT) is associated with several complications necessitating a multidisciplinary approach for diagnosis, treatment and follow-up. Hypogonadism in female TDT patients is one of the most common endocrine complications, requiring hormone replacement therapy (HRT) throughout reproductive life. Little is known about the balance of benefits versus risks of treatment with sex steroids.

AIM

The aim of this manuscript is to review the action and the associated adverse effects of HRT in hypogonadal TDT females.

DESIGN

Retrospective medical database records from a single centre, over a period of 38 years (January 1980 to June 2018), were reviewed.

STUDY POPULATION

Forty-two cases of hypogonadism in TDT females followed in a pediatric and adolescent outpatient clinics, were in included in the study.

METHODS

Auxological, clinical, laboratory, hormonal and imaging investigations were reviewed, as well as all adverse events registered during HRT.

MAIN RESULTS

In general, HRT was safe for most patients. There were few minor side effects and a couple of rare but serious adverse events.

CONCLUSIONS

The study provides a representative clinical profile of long-term effects of HRT in hypogonadal adolescents and young adult TDT women. Our results highlight also the need for further research in other areas for which HRT may have a role.  We hope this will contribute to a wider understanding, and potential improvement, of patient safety and quality of life.

Denosumab effects on serum levels of the bone morphogenetic proteins antagonist noggin in patients with transfusion-dependent thalassemia and osteoporosis

INTRODUCTION

Noggin is an antagonist of bone morphogenetic proteins (BMPs) and has a strong effect on osteogenesis. Osteoporosis is a common complication of transfusion dependent beta-thalassemia (TDT) and denosumab has been recently emerged as a promising therapeutic option. This was a post hoc investigation of serum noggin levels among TDT patients with osteoporosis who participated in a randomized, placebo-control, phase 2b study.

METHODS

Patients received either 60 mg denosumab (n = 32) or placebo (n = 31) every 6 months for 12 months. Noggin was measured, for the first time in thalassemia patients, at baseline and at 12 months, using a recently developed high sensitivity fluorescent immunoassay.

RESULTS

Both groups showed a significant increase in noggin serum levels (denosumab p < 0.001; placebo p < 0.0001). Interestingly, the increase was higher in the placebo group. Furthermore, we observed a strong correlation between noggin and wrist bone mineral density (r = -0.641, p = 0.002) only in the denosumab group.

CONCLUSION

In conclusion, higher noggin levels reflected more BMP inhibition, since our assay detects free bioactive noggin, which in turn impaired bone formation in placebo group. Therefore, denosumab possibly regulates noggin and favours bone turnover in TDT patients with osteoporosis through a novel mechanism of action.

Influence of Iron on Bone Homeostasis

Bone homeostasis is a complex process, wherein osteoclasts resorb bone and osteoblasts produce new bone tissue. For the maintenance of skeletal integrity, this sequence has to be tightly regulated and orchestrated. Iron overload as well as iron deficiency disrupt the delicate balance between bone destruction and production, via influencing osteoclast and osteoblast differentiation as well as activity. Iron overload as well as iron deficiency are accompanied by weakened bones, suggesting that balanced bone homeostasis requires optimal-not too low, not too high-iron levels. The goal of this review is to summarize our current knowledge about how imbalanced iron influence skeletal health. Better understanding of this complex process may help the development of novel therapeutic approaches to deal with the pathologic effects of altered iron levels on bone.

Effect of serum fibroblast growth factor receptor 2 and CAPS proteins on calcium status in β-thalassaemia major patients who are free from overt inflammation

Bone disorders and disturbed calcium (Ca) homeostasis are common disorders in β-thalassaemia major (β-TM). In the present study, two bone related markers are studied in β-TM patients with negative C-reactive protein for the first time; fibroblast growth factor receptor 2 (FGFR2) and CAPS protein. Another goal is to estimate the correlation between the recent parameters and bone biomaterials as a function of iron status parameters in β-TM patients. The results revealed that, in patients with β-TM serum FGFR2, CAPS, alkaline phosphatase (ALP) and Mg significantly increased while serum Ca levels were low as compared with controls. Ca status is correlated with iron overload in β-TM. A significant correlation was present between CAPS and FGFR2. In conclusion, FGFR2 and CAPS associated with Ca status and subsequent bone disturbances in β-TM patients. Their level can be predicted from the equation: CAPS =0.001ALP +0.48FGFR2-1.26Ca - 3.95Pi +12.76 with acceptable applicability.

Iron-induced oxidative stress stimulates osteoclast differentiation via NF-κB signaling pathway in mouse model

BACKGROUND

Women transitioned to postmenopausal status experience a corresponding gain in iron stores. Recently clinical researches have observed increased serum ferritin level in postmenopausal women, and ferritin level was negatively correlated with bone mineral density.

PURPOSE

To explore the mechanism of iron-induced osteopenia in mouse model.

METHODS

Briefly, in this study, we established an iron accumulation mouse model with ovariectomy. Primary osteoclasts and osteoblasts were extracted for this research. Biomarkers of bone metabolism and cell signaling pathways were measured.

RESULTS

We found that bone mass changed later than ferritin and decreased gradually following overiectomy. We also observed higher levels of bone resorption and oxidative stress when iron was administered. When stimulated with iron, primary osteoclasts derived from bone marrow-derived macrophages (BMMs) underwent differentiation and numerous reactive oxygen species (ROS) were generated. Further, we found that iron activated the JNK, ERK and NF-κB signaling pathways in vivo. In vitro, we found that only NF-κB signaling was stimulated by iron and that suppression of this pathway blocked osteoclast differentiation. To determine whether these effects were related to ROS, osteoclasts were treated with H₂O₂. We found that ROS stimulated osteoclast activity, and that this effect was reversed upon NF-κB suppression.

CONCLUSIONS

These data suggest that ROS might be a downstream factor of iron and regulated NF-κB signaling in osteoclasts in mouse model.