Chronic pediatric inflammatory diseases: effects on bone

Pediatric pituitary neuroendocrine tumors-a 13-year experience in a tertiary center

Introduction

Pediatric pituitary neuroendocrine tumor is a rare condition, and despite previous research focusing on this specific group, the main factors influencing the surgical cure rate have not been identified.

Methods

We conducted a single-center retrospective study on pediatric pituitary neuroendocrine tumor patients who visited Peking Union Medical College Hospital between 2010 and 2023. We collected data on their clinical characteristics, imaging features, surgical outcomes, and follow-up information. Additionally, we used multiple-factor logistic regression to investigate the factors affecting the surgical cure rate of pediatric pituitary neuroendocrine tumor.

Results

232 patients were diagnosed with pediatric pituitary neuroendocrine tumors, with a higher incidence in females. The most common type was ACTH-secreting adenoma (90/232), followed by prolactin-secreting adenoma (63/232), and growth hormone-secreting adenoma (41/232). The majority of pediatric adenomas were macroadenomas (139/232), and some tumors were associated with cystic changes or hemorrhage (58/232), while a few exhibited invasion of the cavernous sinus (33/232). The results of the multivariate analysis indicated that the different hormone secretion types, macroadenoma or the presence of cystic changes or hemorrhage were not significant risk factors for the cure rate after the first surgery. However, the invasion of the cavernous sinus was found to be an important factor influencing the postoperative cure rate. Most pediatric pituitary neuroendocrine tumors with cavernous sinus invasion were macroadenomas, and some displayed characteristics of refractory pituitary neuroendocrine tumors, with some patients experiencing irreversible complications after surgery.

Conclusion

Pediatric pituitary neuroendocrine tumors are complex, and the postoperative cure rate is particularly poor for tumors with cavernous sinus invasion. Although macroadenoma itself does not significantly impact the postoperative cure rate, it is still recommended to diagnose and treat early to avoid unnecessary surgery or surgical complications.

Bone impairment assessed by HR-pQCT in juvenile-onset systemic lupus erythematosus

High-resolution peripheral quantitative computed tomography (HR-pQCT) analysis of female juvenile-onset systemic lupus erythematosus (JoSLE) patients revealed trabecular/cortical bone damage and reduced bone strength primarily at the distal radius compared to healthy controls. We demonstrated for the first time that JoSLE patients with vertebral fracture (VF) present trabecular impairment at the distal radius.

INTRODUCTION

This study investigated the volumetric bone mineral density (vBMD), microarchitecture, and biomechanical features at the distal radius and tibia using HR-pQCT and laboratory bone markers in JoSLE patients compared to controls to determine whether this method discriminates JoSLE patients with or without VF.

METHODS

We compared 56 female JoSLE patients to age- and Tanner-matched healthy controls. HR-pQCT was performed at the distal radius and tibia. Serum levels of the amino-terminal pro-peptide of type I collagen, the C-terminal telopeptide of type I collagen, intact parathormone, sclerostin, and 25-hydroxyvitamin D (25OHD) were evaluated. VFs were analyzed using VFA-dual-energy X-ray absorptiometry (DXA) (Genant's method).

RESULTS

Reduced density and strength parameters and microarchitecture alterations of cortical and trabecular bones were observed in JoSLE patients compared to controls, primarily at the distal radius (p < 0.05). Patients with VF exhibited a significant decrease in trabecular bone parameters solely at the distal radius (Total.BMD, p = 0.034; Trabecular.BMD [Tb.BMD], p = 0.034; bone volume (BV)/trabecular volume (TV), p = 0.034; apparent modulus, p = 0.039) and higher scores for disease damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR-DI), p = 0.002). Bone metabolism markers were similar in all groups. Logistic regression analysis of parameters that were significant in univariate analysis revealed that Tb.BMD (OR 0.98, 95 % CI 0.95-0.99, p = 0.039) and SLICC/ACR-DI (OR 7.37, 95 % CI 1.75-30.97, p = 0.006) were independent risk factors for VF.

CONCLUSION

In conclusion, this study is the first demonstration of bone microstructure and strength deficits in JoSLE patients, particularly at the distal radius. Our results demonstrated that VF was associated with trabecular radius alteration and emphasized the potential detrimental effect of disease damage on this condition.

Pathological fractures in paediatric patients with inflammatory bowel disease

Paediatric inflammatory bowel disease (IBD), especially Crohn's disease (CD), is commonly associated with poor skeletal health, related to the direct effects of chronic inflammation, prolonged use of glucocorticoid (GC), poor nutrition, delayed puberty and low muscle mass. Low bone mineral density is commonly reported, although the prevalence of long bone fractures may not be increased in these patients. Emerging evidence however suggests that there may be an increased risk of vertebral fractures (VFs) in this group. VFs presenting at diagnosis of paediatric CD, prior to any GC exposure, have been reported, highlighting the deleterious effect of inflammation on skeletal health. This paper reviews the published literature on pathophysiology of skeletal morbidity and fractures in paediatric IBD, illustrated with a new case report of multiple VFs in a prepubertal girl with CD, soon after diagnosis, who received minimal amounts of oral GC. Optimising control of disease, addressing vitamin D deficiency, encouraging physical activity and ensuring normal growth and pubertal progression are paramount to management of bone health in these patients. Despite the lack of evidence, there may be a place for bisphosphonate treatment, especially in the presence of symptomatic pathological fractures, but this requires close monitoring by clinicians with expertise in paediatric bone health.

CONCLUSION

Chronic inflammation mediated by pro-inflammatory cytokines may have adverse effects on skeletal health in paediatric patients with IBD. The risk of vertebral fractures may be increased, even without exposure to glucocorticoid. Clinical monitoring of these patients requires careful attention to the various factors that impact on bone health.

Children with nephrotic syndrome have greater bone area but similar volumetric bone mineral density to healthy controls

BACKGROUND

Glucocorticoid use has been associated with an increased fracture risk and reduced bone mineral density (BMD), particularly in the trabecular compartment. However the contribution of the underlying inflammatory disease process to these outcomes is poorly understood. Childhood nephrotic syndrome (NS) typically follows a relapsing-remitting course often requiring recurrent courses of glucocorticoids, but with low systemic inflammation during remission. NS therefore represents a useful clinical model to investigate the effects of glucocorticoids on BMD and bone geometry in childhood.

METHODS

Children with NS were compared to age and sex matched healthy controls. Body composition and areal BMD (whole body, lumbar spine and hip) were assessed by DXA. Peripheral quantitative computed tomography (pQCT) scans were obtained at metaphyseal (4%) and diaphyseal (66%) sites of the tibia to determine volumetric BMD and bone cross-sectional geometry. Lifetime cumulative glucocorticoid exposure was calculated from medical records.

RESULTS

29 children with NS (55% male, age 10.7±3.1years) were compared to 29 healthy controls (55% male, age 11.0±3.0years). The children with NS were of similar height SDS to controls (p=0.28), but were heavier (0.65±1.28SDS vs -0.04±0.89SDS, p=0.022) and had greater body fat percentage SDS (0.31±1.01 vs -0.52±1.10, p=0.008). Tibial trabecular and cortical vBMD were similar between the two groups but bone cross-sectional area (CSA) was significantly greater in children with NS at both the metaphysis (954±234mm(2) vs 817±197mm(2), p=0.002) and diaphysis (534.9±162.7mm(2) vs 463.2±155.5mm(2), p=0.014). Endosteal and periosteal circumferences were greater in children with NS than controls (both p<0.01), resulting in reduced cortical thickness (2.4±0.7mm vs 2.8±0.7mm, p=0.018), but similar cortical CSA (p=0.22). The differences in cortical geometry were not statistically significant when weight was included as a confounding factor. There were no associations between cumulative steroid exposure, duration of NS or number of relapses and any bone parameter.

CONCLUSIONS

Tibial bone CSA is increased in children with NS. We speculate that this is a compensatory response to increased body weight. Defects in trabecular BMD were not identified in this cohort of children with NS.

Chronic low dose tumor necrosis factor-α (TNF) suppresses early bone accrual in young mice by inhibiting osteoblasts without affecting osteoclasts

The inflammatory cytokine tumor necrosis factor-α (TNF-α) is known to cause bone resorption and inhibit bone formation in arthritis and aging but less is known about TNF effects in the young growing skeleton. While investigating the mechanism of bone loss in TNF transgenic mice, we identified an early TNF-sensitive period marked by suppression of osteoblasts and bone accrual as the sole mechanism of TNF action, without an effect on osteoclasts or bone resorption. TgTNF mice express low concentrations of hTNFα (≤5 pg/ml). Osteoblasts cultured from TgTNF mice express reduced levels of RUNX2, Osx, alkaline phosphatase, bone sialoprotein, and osteocalcin and have delayed formation of mineralized nodules. Early accrual of bone in TgTNF mice is suppressed until 6 weeks of age, after which the rate of bone accrual normalizes without catch up. Histomorphometry revealed that TgTNF mice fail to generate a transient surge in osteoblast number that is seen in wild type (WT) mice at 4 weeks. Osteoclasts, TRAP staining, erosive surfaces, serum CTx, and OPG/RANKL expression did not differ between young TgTNF and WT mice. Canonical Wnts and signaling through β-catenin were reduced in TgTNF mice at 4 weeks and partially recovered by 12 weeks, associated with reduced cytoplasm to nuclear transfer of β-catenin and Wnt regulated genes. TgTNF mice were crossed with BatGal Wnt reporter mice. Active Wnt signaling in tibial trabecular lining cells was reduced in TgTNF mice at 4 weeks compared to control littermates. Our results demonstrate that a low dose inflammatory stimulus is sufficient to inhibit the early surge in osteoblasts and optimal bone formation of young mice independent of changes in osteoclasts. TNF inhibition of the Wnt pathway contributes to the suppression of osteoblasts.

Inflammatory bone loss: pathogenesis and therapeutic intervention

Bone is a tissue undergoing continuous building and degradation. This remodelling is a tightly regulated process that can be disturbed by many factors, particularly hormonal changes. Chronic inflammation can also perturb bone metabolism and promote increased bone loss. Inflammatory diseases can arise all over the body, including in the musculoskeletal system (for example, rheumatoid arthritis), the intestine (for example, inflammatory bowel disease), the oral cavity (for example, periodontitis) and the lung (for example, cystic fibrosis). Wherever inflammatory diseases occur, systemic effects on bone will ensue, as well as increased fracture risk. Here, we discuss the cellular and signalling pathways underlying, and strategies for therapeutically interfering with, the inflammatory loss of bone.

The thoracic and lumbar spine in severe juvenile idiopathic arthritis: magnetic resonance imaging analysis in 50 children

OBJECTIVE

To determine the prevalence of vertebral fractures as a complication of juvenile idiopathic arthritis (JIA).

STUDY DESIGN

This cross-sectional study evaluated the prevalence and characteristics of spinal abnormalities in 50 children (aged 7.0-18.7 years) with treatment-resistant JIA by magnetic resonance imaging. Vertebral deformities, endplate irregularities, intervertebral disc involvement, spinal canal, neural foramina, and back muscles were analyzed and correlated with clinical characteristics and bone mineral density.

RESULTS

Magnetic resonance imaging revealed various abnormalities in 31 patients (62%). Vertebral compression was seen in 28%, disc degeneration in 46%, protrusions in 14%, prolapses in 4%, endplate changes in 26%, and anterior vertebral corner lesions in 16%. Two patients (4%) had mild spinal canal narrowing without medullar involvement; none had neural root compression. Six patients (12%) had mild back muscle atrophy. No correlation was observed between spinal fractures or other vertebral changes and disease activity or duration, pain or bone mineral density; patients with spinal fractures tended to have a higher recent glucocorticoid exposure (P=.086).

CONCLUSION

Children with severe JIA have a high prevalence of compression fractures and other vertebral, endplate, and disc abnormalities in the thoracic and lumbar spine.

Correlates of low bone mass in children with generalized forms of epidermolysis bullosa

BACKGROUND

Epidermolysis bullosa (EB) is a family of rare, heterogeneous, genetic disorders characterized by fragility of the skin and mucous membranes. Reduced bone mass and fractures have been recognized as complications of generalized forms of EB.

OBJECTIVES

We sought to describe the range and to estimate the prevalence of low bone mass in children with generalized EB, and to identify correlates of low bone mass in this population.

METHODS

This was a prospective, observational study of 24 patients with generalized EB. Each patient completed a history, physical examination, laboratory studies, bone age, and x-rays of the lumbar spine. Those aged 6 years and older underwent dual energy x-ray absorptiometry scans of the lumbar spine. Primary outcomes were areal bone mineral density (aBMD) based on chronologic age, bone age, and adjusted for height Z-score. Descriptive statistics were used to summarize results, and linear regression was used to determine factors associated with low aBMD.

RESULTS

Mean lumbar spine aBMD Z-scores ± SD were: -2.6 ± 1.4 for chronologic age, -1.7 ± 1.3 for bone age, and -1.0 ± 1.2 after adjusting for height Z-score. aBMD Z-scores were less than or equal to -2 in 64% for chronologic age, 50% for bone age, and 28% after adjusting for height Z-score. aBMD correlated with height Z-score, weight Z-score, extensive blistering, immobility, albumin, hemoglobin, iron, erythrocyte sedimentation rate, and c-reactive protein values.

LIMITATIONS

Small sample size was a limitation.

CONCLUSIONS

Children with severe, generalized recessive dystrophic EB have low aBMD for age. Deficits in aBMD were reduced after adjusting for delayed skeletal maturation and small body size.

Osteoporosis and inflammation

Several inflammatory diseases such as rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, celiac disease, cystic fibrosis and chronic obstructive pulmonary disease have been associated to bone resorption. The link between osteoclast, macrophage colony stimulating factor and pro-inflammatory cytokines, especially tumor necrosis factor-alpha and interleukin-1 explain the association between inflammation and osteoporosis. These diseases are related to osteoporosis and high fracture risk independent of other risk factors common to inflammatory diseases such as reduced physical activity, poor nutritional status, hypovitaminosis D, decrease in calcium intake and glucocorticoid treatment. Erythrocyte sedimentation rate and C-reactive protein should always be performed, but the indication about when to perform the densitometry test should be analyzed for each disease. Bisphosphonates are nowadays the best choice of therapy but new medications such as denosumab, IL-1 receptor antagonist, and TNF-alpha antibody have risen as new potential treatments for osteoporosis secondary to inflammation.

Secondary osteoporosis in patients with juvenile idiopathic arthritis

Bone disease in patients with juvenile idiopathic arthritis (JIA) is associated with focal (joint erosion and juxtaarticular osteopenia) and systemic bone loss (generalized osteopenia or reduction of bone mass density). Pathophysiology of bone loss is multifactorial and involves particularly proinflammatory cytokines and deleterious effects of glucocorticoid therapy. Clinical studies in patients with JIA indicate excessive activation of osteoclastogenesis and reduction of bone formation. Reduction of physical activity, muscle atrophy caused by high disease activity, and compulsory restriction in movements are also associated with bone loss. In patients with JIA, the disease can be complicated by growth cartilage involvement and systemic or local growth retardation. In the absence of preventive measures, fragility fractures can occur even at an early age.

The impact of inflammation on bone mass in children

Bone is a dynamic tissue. Skeletal bone integrity is maintained through bone modeling and remodeling. The mechanisms underlying this bone mass regulation are complex and interrelated. An imbalance in the regulation of bone remodeling through bone resorption and bone formation results in bone loss. Chronic inflammation influences bone mass regulation. Inflammation-related bone disorders share many common mechanisms of bone loss. These mechanisms are ultimately mediated through the uncoupling of bone remodeling. Cachexia, physical inactivity, pro-inflammatory cytokines, as well as iatrogenic factors related to effects of immunosuppression are some of the common mechanisms. Recently, cytokine signaling through the central nervous system has been investigated for its potential role in bone mass dysregulation in inflammatory conditions. Growing research on the molecular mechanisms involved in inflammation-induced bone loss may lead to more selective therapeutic targeting of these pathological signaling pathways.

Assessment of bone remodelling in childhood-onset systemic lupus erythematosus

OBJECTIVE

To identify predictors of bone remodelling in children and young adults with SLE.

METHODS

Ninety subjects with SLE aged 8-22 years underwent yearly measurements of height, bone age, bone turnover markers, serum Type I IFNs, SLEDAI and BMD. Predictors of bone turnover were examined using serum osteocalcin as a marker of bone formation and both serum tartrate-resistant acid phosphatase (TRAP) and urine N-telopeptide (NTx) as markers of bone resorption.

RESULTS

Subjects demonstrated short stature, high BMI and bone age delay. A spine BMD Z-score of less than -2.0 was seen in 16.1% of subject visits. Serum osteocalcin was negatively correlated with glucocorticoid dose (Spearman rank correlation coefficient R = -0.34, P < 0.0001) but was not associated with SLEDAI after adjustment for confounders. Serum TRAP was negatively associated with SLEDAI, even after controlling for confounders (P = 0.04). Similar results were obtained for urine NTx. There was a negative association between TRAP and serum IFN-β (P = 0.03).

CONCLUSIONS

In this population of children and young adults with moderate lupus disease activity, glucocorticoid dose was a negative predictor of bone formation, whereas lupus disease activity was not. Interestingly, lupus disease activity was a negative predictor of bone resorption, suggesting that lupus disease activity is not the primary factor contributing to the bone deficits of childhood-onset SLE. The potential protective role of IFN-β and the effects of SLE treatment on bone loss require further study.

Smurf control in bone cells

The homologous to the E6-associated protein carboxyl terminus (HECT) domain E3 ubiquitin ligase Smurf1 is the first E3 ligase to be implicated in regulating bone cell function. The involvement of Smurf1 in multiple signaling pathways and pathological conditions is presently an area of extensive scientific interest. This review highlights recent works exploring Smurf-regulated biological processes in bone cells and highlights recent discoveries surrounding the regulatory mechanisms modulating its catalytic activity and substrate recognition capability. Moreover, we discuss the relevance of targeting the HECT E3s through the development of small-molecule inhibitors as an anticancer therapeutic strategy.

Osteopenia and osteoporosis in epidermolysis bullosa

Patients with the more severe forms of epidermolysis bullosa (EB) are at risk of developing osteopenia, osteoporosis and fractures. The cause is likely to be multifactorial and includes reduced mobility, a generally proinflammatory state, poor nutrition and hormonal factors. Monitoring this group with dual energy X-ray absorptiometry (DEXA) scans and plain radiographs is necessary to detect these changes. Data are lacking about the optimal approach to managing poor bone health in EB, although it seems that encouraging mobility, supplementation of calcium and vitamin D where necessary, with the addition of a bisphosphonate when there is evidence of fractures, may be helpful.