Focus on growth hormone deficiency and bone in adults

Insights into the role of histone lysine demethylases in bone homeostasis and skeletal diseases: A review

Histone lysine demethylases (KDMs), as important epigenetic regulators, are involved in various biological processes such as energy metabolism, apoptosis, and autophagy. Recent research shows that KDMs activate or silence downstream target genes by removing lysine residues from histone tails, and participate in the regulation of bone marrow mesenchymal stem cells (BM-MSCs), osteoblasts (OB), osteoclasts (OC), chondrocytes and other skeletal cell development, differentiation and formation. Moreover, several members of the KDM family affect the occurrence and development of bone diseases such as osteoporosis (OP), osteoarthritis (OA), osteosarcoma (OS), by regulating target genes. Specific regulation mechanisms of KDMs suggest new strategies for bone disease treatment and prevention. Despite the unique function and importance of KDMs in the skeletal system, previous studies have never systematically summarized their specific role, molecular mechanism, and clinical treatment in bone physiology and pathology. Therefore, this review summarises the expression pattern, intracellular signal transduction, and mechanism of action of the KDM family in several bone physiological and pathological conditions, aiming to highlight the important role of KDMs in bone diseases and provide a reference for the future treatment of bone diseases.

Ketogenic diet and β-hydroxybutyrate in osteoporosis: current progress and controversy

Diet has been proven to have significant impacts on the pathogenesis and treatment of osteoporosis. This review attempts to elucidate the current progress and controversy surrounding the ketogenic diet (KD) and β-hydroxybutyrate (BHB) in osteoporosis and offers a novel perspective on the prevention and treatment of osteoporosis. The ketogenic diet has been broadly used in the treatment of epilepsy, diabetes, obesity, and certain neoplasms by triggering ketone bodies, mainly BHB. However, in most osteoporosis-related clinical and preclinical studies, the ketogenic diet has demonstrated the detrimental effects of inhibiting bone accumulation and damaging bone microarchitecture. In contrast, BHB is thought to ameliorate osteoporosis by promoting osteoblastogenesis and inhibiting osteoclastogenesis. The main purpose of this review is to summarize the current research progress and hope that more basic and clinical experiments will focus on the similarities and differences between ketogenic diet (KD) and BHB in osteoporosis.

The impact of inactivation of the GH/IGF axis during aging on healthspan

Several mouse lines with congenital growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis disruption have shown improved health and extended lifespan. The current study investigated how inactivating this axis, specifically during aging, impacts the healthspan. We used a tamoxifen-inducible global GH receptor (GHR) knockout mouse model starting at 12 months and followed the mice until 24 months of age (iGHRKO12-24 mice). We found sex- and tissue-specific effects, with some being pro-aging and others anti-aging. Measuring an array of cytokines in serum revealed that inactivation of the GH/IGF-1 axis at 12 months did not affect systemic inflammation during aging. On the other hand, hypothalamic inflammation was significantly reduced in iGHRKO12-24 mice, evidenced by GFAP+ (glial fibrillary acidic protein, a marker of astrocytes) and Iba-1+ (a marker for microglia). Liver RNAseq analysis indicated feminization of the male transcriptome, with significant changes in the expression of monooxygenase, sulfotransferase, and solute-carrier-transporter gene clusters. Finally, we found impaired bone morphology, more pronounced in male iGHRKO12-24 mice and correlated with GH/IGF-1 inactivation onset age. We conclude that inhibiting the GH/IGF-1 axis during aging only partially preserves the beneficial healthspan effects observed with congenital GH deficiency.

Effects of Growth Hormone on Osteoarthritis Development

Osteoarthritis (OA), a chronic joint disease characterized by primary or secondary degeneration of articular cartilage and bone dysplasia, is associated with various risk factors and is the leading cause of musculoskeletal pain and disability, severely impacting the quality of life. Growth hormone (GH), secreted by the anterior pituitary gland, is essential in mediating the growth and development of bone and cartilage. Reportedly, osteoarthritis increases, and the growth hormone decreases with age. A negative correlation between GH and OA suggests that GH may be related to the occurrence and development of OA. Considering that abnormal growth hormone levels can lead to many diseases related to bone growth, we focus on the relationship between GH and OA. In this review, we will explain the effects of GH on the growth and deficiency of bone and cartilage based on the local pathological changes of osteoarthritis. In addition, the potential feasibility of treating OA with GH will be further explored and summarized.

Transition Period and Young Adulthood in Patients with Childhood Onset Growth Hormone Deficiency (COGHD): Impact of Growth Hormone Replacement on Bone Mass and Body Composition

The aim of this review article is to highlight the consequences of COGHD after the end of linear growth on bone mass and body composition and the opposing beneficial effects of continuing GH replacement in the transition period and young adults. The role of growth hormone in the period of late adolescence and young adulthood is well established, mainly in achieving peak bone mass and a favorable body composition, characterized by muscle mass increase and fat mass reduction. Patients with childhood onset growth hormone deficiency (COGHD), after reaching the adult height, have a reduced bone mineral density and muscle mass with increased fat mass compared to healthy controls. Inadequate body composition is a predictor for cardiovascular risk, while low bone mass in early youth hallmarks the risk of osteoporosis and bone fractures in later life. Cessation of growth hormone replacement (GHr) after completion of growth will lead to delayed peak bone mass and unbalanced body composition with increased abdominal fat deposits. According to numerous clinical studies monitoring the effects of GH treatment on the physical and psychological status of patients with persistent GHD after completion of growth, we suggest continuing this treatment between 16 and 25 years of age. It is advised that GHr in the transition period be administered in intermediate doses between those for the pediatric population and those for the adult population. Usual daily GHr doses are between 0.3 and 0.5 mg but need to be individually optimized, with the aim of maintaining IGF-I in the age-specific normal range.

Bone Quality Indices Correlate with Growth Hormone Secretory Capacity in Women Affected by Weight Excess: A Cross-Sectional Study

Background/Objectives: Obesity can be associated with impaired growth hormone (GH) secretion, with possible negative repercussions on bone health. We aimed to investigate the relationships between GH secretory capacity, evaluated with GHRH + arginine stimulation test, and bone parameters, assessed with a dual-energy X-ray absorptiometer, in a population of adult female patients affected by overweight and obesity. Methods: We assessed 276 women affected by overweight or obesity referred to the High-Specialization Center for the Care of Obesity, Umberto I Polyclinic, between 2014 and 2019 with signs or symptoms of growth hormone deficiency (GHD). Results: A total of 97 patients were diagnosed with GHD, and 179 patients with normal GH secretion were considered our control group. GHD patients showed a significantly reduced trabecular bone score (TBS) (p = 0.01). Bone quality parameters corrected for body mass index (BMI) had a positive and significant linear correlation with stimulated GH secretory capacity. Conclusions: In conclusion, bone quality, evaluated by TBS and hip structural analysis, correlates with GH-stimulated secretory capacity. GHD may act as an additive factor in the alteration of bone microarchitecture in patients affected by obesity, who are already at a higher risk of fractures.

Crosstalk Between the Neuroendocrine System and Bone Homeostasis

The homeostasis of bone microenvironment is the foundation of bone health and comprises 2 concerted events: bone formation by osteoblasts and bone resorption by osteoclasts. In the early 21st century, leptin, an adipocytes-derived hormone, was found to affect bone homeostasis through hypothalamic relay and the sympathetic nervous system, involving neurotransmitters like serotonin and norepinephrine. This discovery has provided a new perspective regarding the synergistic effects of endocrine and nervous systems on skeletal homeostasis. Since then, more studies have been conducted, gradually uncovering the complex neuroendocrine regulation underlying bone homeostasis. Intriguingly, bone is also considered as an endocrine organ that can produce regulatory factors that in turn exert effects on neuroendocrine activities. After decades of exploration into bone regulation mechanisms, separate bioactive factors have been extensively investigated, whereas few studies have systematically shown a global view of bone homeostasis regulation. Therefore, we summarized the previously studied regulatory patterns from the nervous system and endocrine system to bone. This review will provide readers with a panoramic view of the intimate relationship between the neuroendocrine system and bone, compensating for the current understanding of the regulation patterns of bone homeostasis, and probably developing new therapeutic strategies for its related disorders.

Spina bifida and cardiorespiratory profile: the impact of leisure sport activities on physical fitness

PURPOSE

The aim of the present study is to evaluate a population of young patients affected by Spina Bifida (SB) to describe their cardiorespiratory function and bone mineral density profile, analyzing any differences between people performing and those who do not perform sports activity. The study also aimed to rule out possible congenital heart disease associated with spina bifida, considering the common origin of certain cardiac structures with those found to be altered in SB patients.

METHODS

Thirty-four young patients, aged between 12 and 22 years, diagnosed with spinal dysraphism (SD), have been clinically described and, in order to evaluate their physical fitness, functional capacity and bone mass, almost all of them underwent a complete cardiorespiratory assessment, including electrocardiogram (ECG), echocardiogram, Cardiopulmonary Exercise Test (CPET), body composition analysis using bioimpedance analysis (BIA) and Dual Energy X-ray Absorptiometry (DEXA), as well as the estimation of bone mineral density (BMD) with Computerized Bone Mineralometry (CBM).

RESULTS

Collected data demonstrated that only 35% of the subjects practiced physical activity during the week. BMI and percentage FM values were pathological in at least 50% of the population. On cardiological investigations (ECG and echocardiogram), no significant alterations were found. In all patients who performed CPET (79.4%), pathological values of the main functional capacity parameters were revealed, especially peak oxygen consumption (VO2 peak), even when corrected for BCM or FFM estimated at BIA and DEXA, respectively. In the CBM analysis, out of 27 patients in whom the femoral T-score was evaluated, a condition of osteopenia was revealed in 40.7% of the patients (11/27) and osteoporosis in 18.5% (5/27); out of 27 patients in whom the lumbar T-score was evaluated, 37% of the patients showed osteopenia (10/27) and 29.6% osteoporosis (8/27). When the comparison between exercising and non-exercising patients was performed, the only statistically significant difference that emerged was the median lumbar T-score value, which appeared lower in the group not performing physical activity (p = 0,009).

CONCLUSIONS

The extensive cardiorespiratory evaluation, including CPET, of our cohort of spina bifida patients showed altered values of the main parameters related to cardiorespiratory fitness and is the only study in the literature that analysed bone mineralization values in physically active and sedentary spina bifida patients and demonstrated a statistically significant difference. Furthermore, it is the only study to date that investigated the possible association of congenital heart diseases with SD, without demonstrating the existence of pathological conditions.

Differences between bone health parameters in adults with acromegaly and growth hormone deficiency: A systematic review

Preserving bone health is an important goal of care of patients with acromegaly and growth hormone deficiency (GHD). Both disorders are associated with compromised bone health and an increased risk of fracture. However, parameters of bone health that are routinely used to predict fractures in other populations, such as aBMD measured by DXA, are unreliable for this in acromegaly and GHD. Additional methodologies need to be employed to assess bone health in these patients. This review summarizes available data on the effects of acromegaly and GHD on parameters of bone health such as aBMD, volumetric bone mineral density (vBMD) and microarchitecture assessed by HRpQCT and other techniques, trabecular bone score (TBS) and fracture assessment. More research is needed to identify reliable predictors of fracture risk and to determine how best to screen for and treat those patients at risk so that bone health is optimized in these patients.

The influence of growth hormone deficiency on bone health and metabolisms

Growth hormone (GH) is a key peptide hormone in the regulation of bone metabolism, through its systemic and paracrine action mediated directly as well as by insulin-like growth factor-1 (IGF-1). Growth hormone exerts pleiotropic effects leading to an increase in linear bone growth, accumulation of bone mineral content and preservation of peak bone mass. Furthermore, it influences protein, lipid, and carbohydrate metabolism.Growth hormone deficiency (GHD) causes a low bone turnover rate leading to reduced bone mineral density (BMD) and increased bone fragility. The results of GH insufficiency are the most pronounced among children as it negatively affects longitudinal bone growth, causing short stature and in adolescents, in whom it hinders the acquisition of peak bone mass. Most studies show that treatment with recombinant human growth hormone (rhGH) in GHD patients could improve BMD and decrease fracture risk. This review aims to summarize the pathophysiology, clinical picture and management of bone complications observed in GHD.

Bone and body composition analyses by DXA in adults with GH deficiency: effects of long-term replacement therapy

PURPOSE

The effects of growth hormone (GH) replacement on bone mass and body composition in adult with GH deficiency (AGHD) are still debated with regard to their persistence in the long term. Moreover, the impact of the gender on the response to GH is controversial. Aim of this study was to evaluate the long-term effects of rhGH replacement on bone mass and body composition in a monocentric cohort of patients with AGHD.

METHODS

Data from 118 patients with AGHD (34.8 ± 14.4 years, 43 women and 75 men) treated with rhGH for a period of at least 3 years up to a maximum of 10 were retrospectively collected. Bone mineral density (BMD) at the lumbar spine, femur, and 1/3 radius, and total and truncular body composition were evaluated by dual-energy X-ray absorption (DXA) before and during treatment. Clinical and laboratory evaluations were performed before and during the treatment period on an annual basis.

RESULTS

Lumbar spine BMD consistently increased in males, while it decreased in females after a transient improvement observed during the first 4 years of therapy. There were no significant changes in femoral and 1/3 radial BMD in either sexes. Lean mass significantly increased in both sexes, while fat mass only decreased in males.

CONCLUSIONS

In AGHD patients long-term rhGH replacement therapy induces a positive effect with regard to bone mass and body composition. A sexual dimorphism in the response to treatment is evident, with males displaying a more favorable outcome.

Soluble Expression, One-Step Purification and Characterization of Recombinant Human Growth Hormone Fused with ompA3 in Escherichia coli

BACKGROUND

Human growth hormone (hGH) is the first recombinant protein approved for the treatment of human growth hormone deficiency. However, expression in inclusion bodies and low expression levels are enormous challenges for heterologous expression of hGH in Escherichia coli.

OBJECTIVE

To increase the soluble expression of recombinant hGH with correct folding in E. coli.

METHODS

We constructed a new recombinant expression plasmid containing the coding sequence of the outer membrane protein A (ompA3) which was used for the expression in Transetta (DE3) E. coli. In order to simplify the purification process and cleavage of recombinant proteins, the fusion sequence should contain hexahistidine-tag (His₆) and enterokinase recognition sites (D₄K). The effect of different expression conditions on recombinant hGH expression was optimized in flask cultivations. Furthermore, the periplasmic solution containing soluble hGH was purified by Ni-NTA affinity chromatography. Circular dichroism (CD), western blot and mass spectrometry analyses were used to characterize the protein. Moreover, the growth-promoting effect of the purified hGH was also evaluated by cell proliferation assay.

RESULTS

High-level expression (800 μg/mL) was achieved by induction with 0.5 mM IPTG at 30°C for 10 hours. The purity of hGH was over 90%. The immunological activity, secondary structure and molecular weight of the purified hGH were consistent with native hGH. The purified hGH was found to promote the growth of MC3T3-E1 cells, and was found to show the highest activity at a concentration of 100 ng/mL.

CONCLUSION

Our research provides a feasible and convenient method for the soluble expression of recombinant hGH in E. coli, and may lay a foundation for the production and application of hGH in the industry.

Molecular characterization and analysis of the association of growth hormone 1 gene with growth traits in Chinese indigenous yak (Bos grunniens)

This study aimed to investigate the effects of polymorphisms in growth hormone 1 (GH1) gene on the growth traits in Chinese indigenous yak. Using the polymerase chain reaction-restriction fragment length polymorphism (PCR-PFLP) approach, one novel single-nucleotide polymorphism (SNP), termed as g.1721G>A, was identified in the exon 4 of GH1 gene in 423 individuals of yak population. Based on the chi-square (χ²) test, the frequencies of g.1721G>A alleles agreed with Hardy-Weinberg equilibrium (HWE) (P < 0.05). A significant association was observed between this SNP and several growth traits (P < 0.01 or P < 0.05), in which the genotype GG exhibited the best values. The present study suggested that the identified SNP was a useful genetic marker for the improvement of growth traits in Chinese indigenous yak.

Lower Oxytocin Levels Are Associated with Lower Bone Mineral Density and Less Favorable Hip Geometry in Hypopituitary Men

INTRODUCTION

Hypopituitary patients are at risk for bone loss. Hypothalamic-posterior pituitary hormones oxytocin and vasopressin are anabolic and catabolic, respectively, to the skeleton. Patients with hypopituitarism may be at risk for oxytocin deficiency. Whether oxytocin and/or vasopressin contribute to impaired bone homeostasis in hypopituitarism is unknown.

OBJECTIVES

To determine the relationship between plasma oxytocin and vasopressin levels and bone characteristics (bone mineral density [BMD] and hip structural analysis [HSA]) in patients who have anterior pituitary deficiencies only (APD group) or with central diabetes insipidus (CDI group).

METHODS

This is a cross-sectional study. Subjects included 37 men (17 CDI and 20 APD), aged 20-60 years. Main outcome measures were fasting plasma oxytocin and vasopressin levels, and BMD and HSA using dual X-ray absorptiometry.

RESULTS

Mean BMD and HSA variables did not differ between the CDI and APD groups. Mean BMD Z-scores at most sites were lower in those participants who had fasting oxytocin levels below, rather than above, the median. There were positive associations between fasting oxytocin levels and (1) BMD Z-scores at the spine, femoral neck, total hip, and subtotal body and (2) favorable hip geometry and strength variables at the intertrochanteric region in CDI, but not APD, participants. No associations between vasopressin levels and bone variables were observed in the CDI or ADP groups.

CONCLUSIONS

This study provides evidence for a relationship between oxytocin levels and BMD and estimated hip geometry and strength in hypopituitarism with CDI. Future studies will be important to determine whether oxytocin could be used therapeutically to optimize bone health in patients with hypopituitarism.

Stable bone density in adolescents with severe growth hormone deficiency after six months off rhGH

OBJECTIVE

Severe growth hormone deficiency causes lean body mass loss in male adolescents and increased fat mass in both sexes. The changes appear after a 6 month GH pause.

AIM

The aim was to examine bone density and structure changes in adolescents with severe GHD during a 6-month rhGH treatment interruption.

PATIENTS AND METHODS

In total, 113 adolescents (20 females) paused rhGH treatment for 6 months at near-final height, and they were retested with arginine-GHRH challenge and basal IGF-1. Severe GHD was diagnosed in 19 individuals (5 females, GH peak <16 ng/ml and IGF-1 < -1.9 SDS) and excluded in 94 (15 females). Bone density and structure were measured by pQCT of the forearm and DXA of the total body at cessation of rhGH and 6 months later.

RESULTS

In severe adolescent GHD (sGHD) patients, trabecular density (mg/cm³) decreased from 214 to 202 (p < 0.01); changes in the adolescents with normal test results (tGHD) were from 221 to 214 (p < 0.05). Cortical density (mg/cm³) increased from 1077 to 1099 (p < 0.01) in sGHD patients and from 1060 to 1082 in tGHD patients (p < 0.001). The strength strain index (mm³) showed no significant changes in sGHD patients (306 to 307) but changed from 302 to 315 in tGHD patients (p < 0.05). Total bone area (mm²) shifted from 145.1 to 145.2 in sGHD patients and from 153 to 156 in tGHD patients. Total body aBMD (g/cm²) increased in both groups: from 1.10 to 1.12 in sGHD patients and from 1.11 to 1.14 in tGHD patients (p < 0.01). All bone measurements remained within the reference ranges, and there were no differences between sGHD and tGHD patients.

CONCLUSION

During a 6-month pause of rhGH treatment, the bone structure and density of adolescents with sGHD did not show changes implying harm. Routine retesting of adolescents, including 6 months without GH, is unlikely to be detrimental to the bone.

Low bone mineral density is associated with hypogonadism and cranial irradiation in male childhood cancer survivors

We investigated if bone mineral density was related to testosterone deficiency and/or previous cancer treatment in men who were childhood cancer survivors. Men with untreated testosterone deficiency or previous treatment with cranial irradiation were at increased risk of impaired bone health. Prevention of osteoporosis should be considered in their follow-up.

INTRODUCTION

Childhood cancer survivors (CCS) are at increased risk of hypogonadism. Reduced bone mineral density (BMD) has been reported in CCS but it is unclear whether this is due to hypogonadism or a direct effect of cancer therapy. This study investigated BMD in CCS, and association with hypogonadism, previous treatment and cancer type.

METHODS

Investigation of 125 CCS (median age 33.7 at inclusion; 9.6 at diagnosis) and 125 age-matched population controls. Serum testosterone and luteinizing hormone were assayed and BMD at total hip and lumbar spine L1-L4 measured. The mean difference in BMD (g/cm2; 95% CI) between CCS and controls was analysed. Odds ratios (OR; 95% CI) for low BMD were also calculated.

RESULTS

Overall, BMD in the CCS cohort did not significantly differ from controls. However, compared with eugonadal CCS, the CCS with untreated hypogonadism had lower BMD at the hip (mean difference - 0.139 (- 0.210; - 0.067); p < 0.001) and spine (- 0.102 (- 0.174; - 0.030); p = 0.006). They also had a higher risk of low hip BMD (OR 4.1 (1.3; 14); p = 0.018). CCS treated with cranial irradiation also had lower BMD (hip - 0.076 (- 0.133; - 0.019); p = 0.009; spine - 0.071 (- 0.124; - 0.018); p = 0.009) compared with controls. The latter associations remained statistically significant after adjustment for hypogonadism.

CONCLUSIONS

CCS with hypogonadism or previously treated with cranial irradiation are at increased risk of impaired bone health. Prevention of osteoporosis should be considered as an important part in future follow-up of these men.

Association of Serum Testosterone at 12 Years with a Subsequent Increase in Bone Mineral Apparent Density at 18 Years: A Longitudinal Study of Boys in Puberty

BACKGROUND

Cross-sectional studies have associated serum testosterone with bone mineral density (BMD). However, there is a shortage of prospective longitudinal studies in this domain, leaving it unclear whether changes in testosterone level precede changes in BMD.

OBJECTIVES

To examine the association between serum testosterone concentration at the age of 12 years and a subsequent increase in BMD by the age of 18 years.

METHODS

Eighty-eight boys with a mean age of 12.1 ± 0.7 (time point 1 [T1]) and 18.0 ± 0.7 (T2) were investigated. For both time points, serum testosterone was measured from venous blood samples. Total body (TB) and lumbar spine (LS) BMD and bone mineral apparent density (BMAD) were measured. As different brands of DEXA machines were used at T1 and T2, we calculated SD scores (SDS) from samples at T1 and T2 and their change (Δ). As covariates, bone age at T1 and physical activity (PA) by accelerometer at T1 and T2 were measured.

RESULTS

Serum testosterone at T1 was positively correlated with TB BMD at T2 (r = 0.28; p < 0.01), Δ TB BMAD SDS (r = 0.47; p < 0.0001) and Δ LS BMAD SDS (r = 0.23; p < 0.05). When additionally controlling for bone age and total PA at T1, the correlation between testosterone at T1 and Δ TB BMAD SDS remained significant (r = 0.32; p < 0.05).

CONCLUSIONS

Serum testosterone concentration at the age of 12 years is associated with a subsequent increase in TB BMAD by the age of 18 years. This supports the inference that testosterone levels in early puberty may influence subsequent bone mineral accrual.

The associations between different sleep patterns and osteoporosis based on the Osteoporosis Self-Assessment Tool for Asians

Based on the use of Osteoporosis Self-Assessment Tool for Asians (OSTA) to assess osteoporosis risk, we found that short sleep duration and taking a daytime nap had an increased risk of osteoporosis.

PURPOSE

To explore the associations between different sleep patterns with osteoporosis.

METHODS

3659 postmenopausal women (average age of 60 years) were divided into low, middle, and high osteoporosis risk categories based on the Osteoporosis Self-Assessment Tool for Asians (OSTA). After having collected by a standard questionnaire, total and nocturnal sleep duration was collapsed to form categories of ≤ 6 h, > 6 h and ≤ 7 h, > 7 h and ≤ 8 h, > 8 h and ≤ 9 h, > 9 h, and daytime nap duration of 0 h and > 0 h.

RESULTS

As a categorical variable, the total sleep duration of ≤ 6 h per day (OR = 1.34, 95% CI 1.04-1.72), nocturnal sleep duration of ≤ 6 h per night (OR = 1.65, 95% CI 1.24-2.18), and taking a daytime nap (OR = 1.33, 95% CI 1.09-1.64) had higher osteoporosis risk after adjustment for covariates. As a continuous variable, after the adjustment for covariates, both longer total (OR = 0.86, 95% CI 0.78-0.94) and nocturnal sleep duration (OR = 0.83, 95% CI 0.76-0.91) had lower risk of osteoporosis risk while taking longer daytime nap (OR = 1.10, 95% CI 1.02-1.19) had higher osteoporosis risk.

CONCLUSIONS

Postmenopausal women with both short total and nocturnal sleep duration (6 h or less) and taking a daytime nap had increased osteoporosis risk as assessed by OSTA.

Identification of Haptoglobin as a Readout of rhGH Therapy in GH Deficiency

BACKGROUND

GH deficiency (GHD) is characterized by a cluster of cardiovascular risk factors and subtle inflammation. We aimed to demonstrate, through a proteomic approach, molecules directly modulated by GHD and involved in the inflammatory state.

METHODS

Ten children with isolated GHD were studied before and after 1 year of treatment with rhGH and compared with 14 matched controls. A two-dimensional electrophoresis plasma proteomics analysis was performed at baseline and after GH treatment to identify the top molecules modulated by GH. In vitro studies on human hepatoma (HepG2) cells were performed to validate the data.

RESULTS

Twelve of 20 proteomic spots were predicted to be isoforms α and β of haptoglobin (Hp) and confirmed by liquid chromatography tandem mass spectrometry and Western immunoblot analyses. Hp levels were higher in patients with GHD than controls at baseline (P < 0.001) and were reduced following GH treatment (P < 0.01). In HepG2 cells, both GH and IGF-1 were able to downregulate IL-6-induced Hp secretion. Moreover, Hp secretion was restored in pegvisomant-treated HepG2 cells.

CONCLUSIONS

Hp is a molecule acting in the inflammatory state of GHD and a possible biomarker for GH treatment. Nevertheless, the contribution of other factors and the molecular pathways involved in the GH downregulation of Hp remain to be clearly defined.

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.

Update on bone fragility in spina bifida

BACKGROUND CONTEXT

Patients with spina bifida (SB) are at risk for pathological fractures and low bone mineral density (BMD).

PURPOSE AND METHODS

This article reviews the literature and provides a comprehensive overview of how the characteristics of SB and its associated comorbidities intersect with bone fragility to identify possible pathophysiological mechanisms of fractures and low BMD.

RESULTS

Bone fragility occurs early in the life of patients with SB as a result of a disturbance that determines changes in bone shape, quantity, and quality, as poor mineralization reduces bone stiffness. Bone fragility in SB occurs due to local and systemic factors and may be considered a state of impaired bone quality of multifactorial aetiology, with complex interacting influences of neurological, metabolic, and endocrinological origins and the presence of smaller bones. Bone fragility should be evaluated globally according to skeletal age and Tanner staging. The phases of the evolution of Charcot joints seem to intercept the evolution of epiphyseal fractures. Charcot arthropathy in SB may be initiated by the occurrence of repetitive trauma and fractures in epiphyseal and subepiphyseal regions, where there is a deficit of bone mineralization and greater bone mass deficits.

CONCLUSION

Bone fragility in MMC potentially has a multifactorial neuro-endocrinological-metabolic-renal dimension, with smaller bones, lower bone mass, and mineralization deficits affecting bone strength.