Bone, inflammation, and inflammatory bowel disease

Role of diet quality in bone health in children and adolescents: a systematic review

CONTEXT

Poor diet quality and unhealthy dietary patterns have been linked to poor bone health, yet few studies have investigated the role of diet quality in bone health in pediatric populations.

OBJECTIVE

This systematic review aims to assess the available evidence on the association between diet quality and bone health markers in children and adolescents.

DATA SOURCES

The PubMed, Scopus, and Virtual Health Library databases were searched electronically from October to November 2022, without any restrictions on date or language. The STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) checklist was used to assess the quality of the studies.

DATA EXTRACTION

Published observational studies in children and adolescents (ages 2 to 19 years) that investigated the association between diet quality and bone health were eligible for inclusion. Two researchers independently analyzed and selected all articles using the Rayyan app. Initially, 965 papers were identified. A total of 12 observational studies qualified, including 8 cross-sectional and 4 longitudinal studies. The sample comprised 7130 individuals aged 3 to 17.9 years, representing both sexes. Bone health was evaluated by measures of bone mineral density and bone mineral content.

DATA ANALYSIS

Seven studies (58.3%) showed significant associations between diet quality and bone health markers, all of which evaluated diet quality by identifying dietary patterns. Diet quality as evaluated by all dietary indexes was not associated with bone health markers.

CONCLUSIONS

Adherence to a healthy diet may benefit bone health in children and adolescents. These findings emphasize the importance of developing effective public health policies that encourage healthy eating habits from childhood to preserve bone health. Longitudinal research using a specific tool to assess diet quality in relation to bone health is warranted. Future studies should also measure bone-regulating hormones and markers of bone turnover.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022368610.

Bone health in inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease (IBD) is a chronic disease characterized by the presence of systemic inflammation, manifesting not only as gastrointestinal symptoms but also as extraintestinal bone complications, including osteopenia and osteoporosis. However, the association between IBD and osteoporosis is complex, and the presence of multifactorial participants in the development of osteoporosis is increasingly recognized. Unlike in adults, delayed puberty and growth hormone/insulin-like growth factor-1 axis abnormalities are essential risk factors for osteoporosis in pediatric patients with IBD.

AREAS COVERED

This article reviews the potential pathophysiological mechanisms contributing to osteoporosis in adult and pediatric patients with IBD and provides evidence for effective prevention and treatment, focusing on pediatric patients with IBD. A search was performed from PubMed and Web of Science inception to February 2023 to identify articles on IBD, osteoporosis, pediatric, and fracture risk.

EXPERT OPINION

A comprehensive treatment pattern based on individualized principles can be used to manage pediatric IBD-related osteoporosis.

Risk Variants in or Near ZBTB40 AND NFATC1 Increase the Risk of Both IBD and Adverse Bone Health Outcomes Highlighting Common Genetic Underpinnings Across Both Diseases

BACKGROUND

Inflammatory bowel disease (IBD) is associated with an increased risk of osteoporosis and bone fracture. The aims of this study were to (1) confirm the association between IBD and low bone density and (2) test for shared risk variants across diseases.

METHODS

The study cohort included patients from the Michigan Genomics Initiative. Student's t tests (continuous) and chi-square tests (categorical) were used for univariate analyses. Multivariable logistic regression was performed to test the effect of IBD on osteoporosis or osteopenia. Publicly available genome-wide association summary statistics were used to identify variants that alter the risk of IBD and bone density, and Mendelian randomization (MR) was used to identify causal effects of genetically predicted IBD on bone density.

RESULTS

There were 51 405 individuals in the Michigan Genomics Initiative cohort including 10 378 (20.2%) cases of osteoporosis or osteopenia and 1404 (2.7%) cases of IBD. Patients with osteoporosis or osteopenia were more likely to be older (64 years of age vs 56 years of age; P < .001), female (67% vs 49%; P < .001), and have a lower body mass index (29 kg/m2 vs 30 kg/m2; P < .001). IBD patients with (odds ratio, 4.60; 95% confidence interval, 3.93-5.37) and without (odds ratio, 1.77; 95% confidence interval, 1.42-2.21) steroid use had a significantly higher risk of osteoporosis or osteopenia. Twenty-one IBD variants associated with reduced bone mineral density at P ≤ .05 and 3 IBD risk variants associated with reduced bone mineral density at P ≤ 5 × 10-8. Of the 3 genome-wide significant variants, 2 increased risk of IBD (rs12568930-T: MIR4418;ZBTB40; rs7236492-C: NFATC1). MR did not reveal a causal effect of genetically predicted IBD on bone density (MR Egger, P = .30; inverse variance weighted, P = .63).

CONCLUSIONS

Patients with IBD are at increased risk for low bone density, independent of steroid use. Variants in or near ZBTB40 and NFATC1 are associated with an increased risk of IBD and low bone density.

Pivotal Role of Intestinal Microbiota and Intraluminal Metabolites for the Maintenance of Gut-Bone Physiology

Intestinal microbiota, and their mutual interactions with host tissues, are pivotal for the maintenance of organ physiology. Indeed, intraluminal signals influence adjacent and even distal tissues. Consequently, disruptions in the composition or functions of microbiota and subsequent altered host-microbiota interactions disturb the homeostasis of multiple organ systems, including the bone. Thus, gut microbiota can influence bone mass and physiology, as well as postnatal skeletal evolution. Alterations in nutrient or electrolyte absorption, metabolism, or immune functions, due to the translocation of microbial antigens or metabolites across intestinal barriers, affect bone tissues, as well. Intestinal microbiota can directly and indirectly alter bone density and bone remodeling. Intestinal dysbiosis and a subsequently disturbed gut-bone axis are characteristic for patients with inflammatory bowel disease (IBD) who suffer from various intestinal symptoms and multiple bone-related complications, such as arthritis or osteoporosis. Immune cells affecting the joints are presumably even primed in the gut. Furthermore, intestinal dysbiosis impairs hormone metabolism and electrolyte balance. On the other hand, less is known about the impact of bone metabolism on gut physiology. In this review, we summarized current knowledge of gut microbiota, metabolites and microbiota-primed immune cells in IBD and bone-related complications.

Exosome-based bone-targeting drug delivery alleviates impaired osteoblastic bone formation and bone loss in inflammatory bowel diseases

Systematic bone loss is commonly complicated with inflammatory bowel diseases (IBDs) with unclear pathogenesis and uncertain treatment. In experimental colitis mouse models established by dextran sulfate sodium and IL-10 knockout induced with piroxicam, bone mass and quality are significantly decreased. Colitis mice demonstrate a lower bone formation rate and fewer osteoblasts in femur. Bone marrow mesenchymal stem/stromal cells (BMSCs) from colitis mice tend to differentiate into adipocytes rather than osteoblasts. Serum from patients with IBD promotes adipogenesis of human BMSCs. RNA sequencing reveals that colitis downregulates Wnt signaling in BMSCs. For treatment, exosomes with Golgi glycoprotein 1 inserted could carry Wnt agonist 1 and accumulate in bone via intravenous administration. They could alleviate bone loss, promote bone formation, and accelerate fracture healing in colitis mice. Collectively, BMSC commitment in inflammatory microenvironment contributes to lower bone quantity and quality and could be rescued by redirecting differentiation toward osteoblasts through bone-targeted drug delivery.

The Relationship between Dietary Pattern and Bone Mass in School-Age Children

Early bone accrual significantly influences adult bone health and osteoporosis incidence. We aimed to investigate the relationship between dietary patterns (DPs), bone mineral content (BMC) and bone mineral density (BMD) in school-age children in China. Children aged six-nine years (n = 465) were enrolled in this cross-sectional study. DPs were identified by principal component factor analysis. Total body (TB) and total body less head (TBLH) BMC and BMD were measured using dual-energy X-ray absorptiometry. Five DPs were identified. After adjustment for covariates, multiple linear regression analysis showed that the "fruit-milk-eggs" dietary pattern was positively associated with TB (β = 10.480; 95% CI: 2.190, 18.770) and TBLH (β = 5.577; 95% CI: 0.214, 10.941) BMC, the "animal organs-refined cereals" pattern was associated with low TB BMC (β = -10.305; 95% CI: -18.433, -2.176), TBLH BMC (β = -6.346; 95% CI: -11.596, -1.096), TB BMD (β = -0.006; 95% CI: -0.011, -0.001) and TBLH BMD (β = -0.004; 95% CI: -0.007, -0.001). In conclusion, our study recommends home or school meals should be rich in fruit, milk, eggs with a moderate amount of vegetables, coarse grains and meat to promote bone development for school-age children.

Structural and Metabolic Changes in Bone

Simple Summary

Bone is an extremely metabolically active tissue that is regenerated and repaired over its lifetime by bone remodeling. Most bone diseases are caused by abnormal restructure processes that undermine bone structure and mechanical strength and trigger clinical symptoms, such as pain, deformity, fracture, and abnormalities of calcium and phosphate homoeostasis. The article examines the main aspects of bone development, anatomy, structure, and the mechanisms of cell and molecular regulation of bone remodeling.

Abstract

As an essential component of the skeleton, bone tissue provides solid support for the body and protects vital organs. Bone tissue is a reservoir of calcium, phosphate, and other ions that can be released or stored in a controlled manner to provide constant concentration in body fluids. Normally, bone development or osteogenesis occurs through two ossification processes (intra-articular and intra-chondral), but the first produces woven bone, which is quickly replaced by stronger lamellar bone. Contrary to commonly held misconceptions, bone is a relatively dynamic organ that undergoes significant turnover compared to other organs in the body. Bone metabolism is a dynamic process that involves simultaneous bone formation and resorption, controlled by numerous factors. Bone metabolism comprises the key actions. Skeletal mass, structure, and quality are accrued and maintained throughout life, and the anabolic and catabolic actions are mostly balanced due to the tight regulation of the activity of osteoblasts and osteoclasts. This activity is also provided by circulating hormones and cytokines. Bone tissue remodeling processes are regulated by various biologically active substances secreted by bone tissue cells, namely RANK, RANKL, MMP-1, MMP-9, or type 1 collagen. Bone-derived factors (BDF) influence bone function and metabolism, and pathophysiological conditions lead to bone dysfunction. This work aims to analyze and evaluate the current literature on various local and systemic factors or immune system interactions that can affect bone metabolism and its impairments.

Polyphenols: Bioavailability, Microbiome Interactions and Cellular Effects on Health in Humans and Animals

Polyphenolic compounds have a variety of functions in plants including protecting them from a range of abiotic and biotic stresses such as pathogenic infections, ionising radiation and as signalling molecules. They are common constituents of human and animal diets, undergoing extensive metabolism by gut microbiota in many cases prior to entering circulation. They are linked to a range of positive health effects, including anti-oxidant, anti-inflammatory, antibiotic and disease-specific activities but the relationships between polyphenol bio-transformation products and their interactions in vivo are less well understood. Here we review the state of knowledge in this area, specifically what happens to dietary polyphenols after ingestion and how this is linked to health effects in humans and animals; paying particular attention to farm animals and pigs. We focus on the chemical transformation of polyphenols after ingestion, through microbial transformation, conjugation, absorption, entry into circulation and uptake by cells and tissues, focusing on recent findings in relation to bone. We review what is known about how these processes affect polyphenol bioactivity, highlighting gaps in knowledge. The implications of extending the use of polyphenols to treat specific pathogenic infections and other illnesses is explored.

Jianpi Qingchang Bushen decoction improves inflammatory response and metabolic bone disorder in inflammatory bowel disease-induced bone loss

BACKGROUND

Bone loss and osteoporosis are commonly described as extra-intestinal manifestations of inflammatory bowel disease (IBD). Jianpi Qingchang Bushen decoction (JQBD) is a prescription used in clinical practice. However, further studies are needed to determine whether JQBD regulates the receptor activator of nuclear factor kappa B (NF-κB) (RANK)/receptor activator of NF-κB ligand (RANKL)/ osteoprotegerin (OPG) pathways and could play a role in treating IBD-induced bone loss.

AIM

To evaluate the therapeutic effect of JQBD in IBD-induced bone loss and explore the underlying mechanisms.

METHODS

An IBD-induced bone loss model was constructed by feeding 12 6-to-8-wk-old interleukin-10 (IL-10)-knockout mice with piroxicam for 10 d. The mice were randomly divided into model and JQBD groups. We used wild-type mice as a control. The JQBD group was administered the JQBD suspension for 2 wk by gavage, while the control and model groups were given normal saline at the corresponding time points. All mice were killed after the intervention. The effect of JQBD on body weight, disease activity index (DAI), and colon length was analyzed. Histopathological examination, colon ultrastructure observation, and micro-computed tomographic scanning of the lumbar vertebrae were performed. The gene expression of NF-κB, tumor necrosis factor-α (TNF-α), IL-1β, IL-6, and IL-8 in the colon was evaluated by real-time polymerase chain reaction. Colon samples were assessed by Western blot for the expression of RANKL, OPG, RANK, and NF-κB proteins.

RESULTS

The model group lost body weight, had a shorter colon, and showed a dramatic increase in DAI score, whereas JQBD had protective and therapeutic effects. Treatment with JQBD significantly improved inflammatory cell infiltration and reduced crypt abscess and ulcer formation. Three-dimensional imaging of the vertebral centrum in the model group revealed a lower bone mass, loose trabeculae, and “rod-shaped” changes in the structure compared to the control group and JQBD groups. The bone volume/total volume ratio and bone mineral density were significantly lower in the model group than in the control group. JQBD intervention downregulated the NF-κB, TNF-α, IL-1β, IL-6, and IL-8 mRNA expression levels. The RANKL and OPG protein levels were also improved.

CONCLUSION

JQBD reduces inflammation of the colonic mucosa and inhibits activation of the RANK/ RANKL/OPG signaling pathway, thereby reducing osteoclast activation and bone resorption and improving bone metabolism.

The Use of Mushrooms and Spirulina Algae as Supplements to Prevent Growth Inhibition in a Pre-Clinical Model for an Unbalanced Diet

Today’s eating patterns are characterized by the consumption of unbalanced diets (UBDs) resulting in a variety of health consequences on the one hand, and the consumption of dietary supplements in order to achieve overall health and wellness on the other. Balanced nutrition is especially crucial during childhood and adolescence as these time periods are characterized by rapid growth and development of the skeleton. We show the harmful effect of UBD on longitudinal bone growth, trabecular and cortical bone micro-architecture and bone mineral density; which were analyzed by micro-CT scanning. Three point bending tests demonstrate the negative effect of the diet on the mechanical properties of the bone material as well. Addition of Spirulina algae or Pleurotus eryngii or Agaricus bisporus mushrooms, to the UBD, was able to improve growth and impaired properties of the bone. 16SrRNA Sequencing identified dysbiosis in the UBD rats’ microbiota, with high levels of pro-inflammatory associated bacteria and low levels of bacteria associated with fermentation processes and bone related mechanisms. These results provide insight into the connection between diet, the skeletal system and the gut microbiota, and reveal the positive impact of three chosen dietary supplements on bone development and quality presumably through the microbiome composition.

Ovariectomy induces bone loss via microbial-dependent trafficking of intestinal TNF+ T cells and Th17 cells

Estrogen deficiency causes a gut microbiome-dependent expansion of BM Th17 cells and TNF-α-producing T cells. The resulting increased BM levels of IL-17a (IL-17) and TNF stimulate RANKL expression and activity, causing bone loss. However, the origin of BM Th17 cells and TNF+ T cells is unknown. Here, we show that ovariectomy (ovx) expanded intestinal Th17 cells and TNF+ T cells, increased their S1P receptor 1-mediated (S1PR1-mediated) egress from the intestine, and enhanced their subsequent influx into the BM through CXCR3- and CCL20-mediated mechanisms. Demonstrating the functional relevance of T cell trafficking, blockade of Th17 cell and TNF+ T cell egress from the gut or their influx into the BM prevented ovx-induced bone loss. Therefore, intestinal T cells are a proximal target of sex steroid deficiency relevant for bone loss. Blockade of intestinal T cell migration may represent a therapeutic strategy for the treatment of postmenopausal bone loss.

The Effect of Inflammation on Bone

Bone remodeling is the continual process to renew the adult skeleton through the sequential action of osteoblasts and osteoclasts. Nuclear factor RANK, an osteoclast receptor, and its ligand RANKL, expressed on the surface of osteoblasts, result in coordinated control of bone remodeling. Inflammation, a feature of illness and injury, plays a distinct role in skewing this process toward resorption. It does so via the interaction of inflammatory mediators and their related peptides with osteoblasts and osteoclasts, as well as other immune cells, to alter the expression of RANK and RANKL. Such chemical mediators include TNFα, glucocorticoids, histamine, bradykinin, PGE2, systemic RANKL from immune cells, and interleukins 1 and 6. Conditions, such as periodontal disease and alveolar bone erosion, aseptic prosthetic loosening, rheumatoid arthritis, and some sports related injuries are characterized by the result of this process. A thorough understanding of bone response to injury and disease, and ability to detect such biomarkers, as well as imaging to identify early structural and mechanical property changes in bone architecture, is important in improving management and outcomes of bone related pathology. While gut health and vitamin and mineral availability appear vitally important, nutraceuticals also have an impact on bone health. To date most pharmaceutical intervention targets inflammatory cytokines, although strategies to favorably alter inflammation induced bone pathology are currently limited. Further research is required in this field to advance early detection and treatments.

Indeterminate Colitis - Update on Treatment Options

Indeterminate colitis (IC) is described in approximately 5-15% of patients with inflammatory bowel disease (IBD). It usually reflects a difficulty or lack of clarity in distinguishing between ulcerative colitis (UC) and Crohn's disease (CD) on biopsy or colectomy specimens. The diagnostic difficulty may explain the variability in the reported prevalence and incidence of IC. Clinically, most IC patients tend to evolve over time to a definite diagnosis of either UC or CD. IC has also been interchangeably described as inflammatory bowel disease unclassified (IBDU). This review offers an overview of the available limited literature on the conventional medical and surgical treatments for IC. In contrast to the numerous studies on the medical management of UC and CD, there are very few data from dedicated controlled trials on the treatment of IC. The natural evolution of IC more closely mimics UC. Regarding medical options for treatment, most patients diagnosed with IC are treated similarly to UC, and treatment choices are based on disease severity. Others are managed similarly to CD if there are features suggestive of CD, including fissures, skin tags, or rectal sparing. In medically refractory IC, surgical treatment options are limited and include total proctocolectomy (TPC) and ileal pouch-anal anastomosis (IPAA), with its associated risk factors and complications. Post-surgical complications and pouch failure rates were historically thought to be more common in IC patients, but recent meta-analyses reveal similar rates between UC and IC patients. Future therapies in IBD are focused on known mechanisms in the disease pathways of UC and CD. Owing to the lack of IC-specific studies, clinicians have traditionally and historically extrapolated the data to IC patients based on their symptomatology, clinical course, and endoscopic findings.

Osteocyte apoptosis: the roles and key molecular mechanisms in resorption-related bone diseases

Vital osteocytes have been well known to function as an important orchestrator in the preservation of robustness and fidelity of the bone remodeling process. Nevertheless, some key pathological factors, such as sex steroid deficiency and excess glucocorticoids, and so on, are implicated in inducing a bulk of apoptotic osteocytes, subsequently resulting in resorption-related bone loss. As much, osteocyte apoptosis, under homeostatic conditions, is in an optimal state of balance tightly controlled by pro- and anti-apoptotic mechanism pathways. Importantly, there exist many essential signaling proteins in the process of osteocyte apoptosis, which has a crucial role in maintaining a homeostatic environment. While increasing in vitro and in vivo studies have established, in part, key signaling pathways and cross-talk mechanism on osteocyte apoptosis, intrinsic and complex mechanism underlying osteocyte apoptosis occurs in various states of pathologies remains ill-defined. In this review, we discuss not only essential pro- and anti-apoptotic signaling pathways and key biomarkers involved in these key mechanisms under different pathological agents, but also the pivotal role of apoptotic osteocytes in osteoclastogenesis-triggered bone loss, hopefully shedding new light on the attractive and proper actions of pharmacotherapeutics of targeting apoptosis and ensuing resorption-related bone diseases such as osteoporosis and fragility fractures.

Hindlimb unloading causes regional loading-dependent changes in osteocyte inflammatory cytokines that are modulated by exogenous irisin treatment

Disuse-induced bone loss is characterized by alterations in bone turnover. Accruing evidence suggests that osteocytes respond to inflammation and express and/or release pro-inflammatory cytokines; however, it remains largely unknown whether osteocyte inflammatory proteins are influenced by disuse. The goals of this project were (1) to assess osteocyte pro-inflammatory cytokines in the unloaded hindlimb and loaded forelimb of hindlimb unloaded rats, (2) to examine the impact of exogenous irisin during hindlimb unloading (HU). Male Sprague Dawley rats (8 weeks old, n = 6/group) were divided into ambulatory control, HU, and HU with irisin (HU + Ir, 3×/week). Lower cancellous bone volume, higher osteoclast surfaces (OcS), and lower bone formation rate (BFR) were present at the hindlimb and 4th lumbar vertebrae in the HU group while the proximal humerus of HU rats exhibited no differences in bone volume, but higher BFR and lower OcS vs. Con. Osteocyte tumor necrosis factor-α (TNF-α), interleukin-17 (IL-17), RANKL, and sclerostin were elevated in the cancellous bone of the distal femur of HU rats vs. Con, but lower at the proximal humerus in HU rats vs. Con. Exogenous irisin treatment increased BFR, and lowered OcS and osteocyte TNF-α, IL-17, RANKL, and sclerostin in the unloaded hindlimb of HU + Ir rats while having minimal changes in the humerus. In conclusion, there are site-specific and loading-specific alterations in osteocyte pro-inflammatory cytokines and bone turnover with the HU model of disuse bone loss, indicating a potential mechanosensory impact of osteocyte TNF-α and IL-17. Additionally, exogenous irisin significantly reduced the pro-inflammatory status of the unloaded hindlimb.

Updated bone mineral density status in Saudi patients with inflammatory bowel disease

BACKGROUND

Little is known about inflammatory bowel disease (IBD) burden and its impact on bone mineral density (BMD) among adult patients in Saudi Arabia. To the best of our knowledge, our study is the only study to give an update about this health problem in adult Saudi patients with IBD. IBD is a great risk factor for reduced BMD due to its associated chronic inflammation, malabsorption, weight loss and medication side effects. Consequently, screening for reduced BMD among patients with IBD is of utmost importance to curb and control anticipated morbidity and mortality among those patients.

AIM

To assess the relationship between IBD and BMD in a sample of adult Saudi patients with IBD.

METHODS

Ninety adult patients with IBD - 62 Crohn's disease (CD) and 28 ulcerative colitis (UC) - were recruited from King Fahad Specialist Hospital gastroenterology clinics in Buraidah, Al-Qassim. All enrolled patients were interviewed for their demographic information and for IBD- and BMD-related clinical data. All patients had the necessary laboratory markers and dual-energy x-ray absorptiometry scans to evaluate their BMD status. Patients were divided into two groups (CD and UC) to explore their clinical characteristics and possible risk factors for reduced BMD.

RESULTS

The CD group was significantly more prone to osteopenia and osteoporosis compared to the UC group; 44% of the CD patients had normal BMD, 19% had osteopenia, and 37% had osteoporosis, while 78% of the UC patients had normal BMD, 7% had osteopenia, and 25% had osteoporosis (P value < 0.05). In the CD group, the lowest t-score showed a statistically significant correlation with body mass index (BMI) (r = 0.45, P < 0.001), lumbar z-score (r = 0.77, P < 0.05) and femur z-score (r = 0.85, P < 0.05). In the UC group, the lowest t-score showed only statistically significant correlation with the lumbar z-score (r = 0.82, P < 0.05) and femur z-score (r = 0.80, P < 0.05). The ROC-curve showed that low BMI could predict the lowest t-score in the CD group with the best cut-off value at ≤ 23.43 (m/kg2); area under the curve was 0.73 (95%CI: 0.59-0.84), with a sensitivity of 77%, and a specificity of 63%.

CONCLUSION

Saudi patients with IBD still have an increased risk of reduced BMD, more in CD patients. Low BMI is a significant risk factor for reduced BMD in CD patients.

Osteocyte-Related Cytokines Regulate Osteoclast Formation and Bone Resorption

The process of bone remodeling is the result of the regulated balance between bone cell populations, namely bone-forming osteoblasts, bone-resorbing osteoclasts, and the osteocyte, the mechanosensory cell type. Osteoclasts derived from the hematopoietic stem cell lineage are the principal cells involved in bone resorption. In osteolytic diseases such as rheumatoid arthritis, periodontitis, and osteoporosis, the balance is lost and changes in favor of bone resorption. Therefore, it is vital to elucidate the mechanisms of osteoclast formation and bone resorption. It has been reported that osteocytes express Receptor activator of nuclear factor κΒ ligand (RANKL), an essential factor for osteoclast formation. RANKL secreted by osteocytes is the most important factor for physiologically supported osteoclast formation in the developing skeleton and in pathological bone resorption such as experimental periodontal bone loss. TNF-α directly enhances RANKL expression in osteocytes and promotes osteoclast formation. Moreover, TNF-α enhances sclerostin expression in osteocytes, which also increases osteoclast formation. These findings suggest that osteocyte-related cytokines act directly to enhance osteoclast formation and bone resorption. In this review, we outline the most recent knowledge concerning bone resorption-related cytokines and discuss the osteocyte as the master regulator of bone resorption and effector in osteoclast formation.

Steroid use and misuse: a key performance indicator in the management of IBD

Corticosteroids remain an important tool for inducing remission in inflammatory bowel disease (IBD) but they have no role in maintenance of remission. The significant adverse side effect profile of these drugs means their use should be avoided where possible or measures taken to reduce their risk. Despite an expanding array of alternative therapies, corticosteroid dependency and excess remain common. Appropriate steroid use is now regarded a key performance indicator in the management of IBD. This article aims to outline indications for corticosteroid use in IBD, their risks and strategies to reduce their use and misuse.

Perspective on skeletal health in inflammatory bowel disease

Osteopenia and osteoporosis are common features in inflammatory bowel disease (IBD), comprising both Crohn's disease and ulcerative colitis. Moreover, Crohn's disease is associated with increased fracture risk. The etiology of bone loss in IBD is multifactorial. It includes insufficient intake or absorption of calcium, vitamin D, and potassium; smoking; a low peak bone mass; a low body mass index; and decreased physical activity. In several studies, it has been shown that elevated concentrations of systemic and local pro-inflammatory cytokines, including tumor necrosis factor alpha (TNF-α), interferon-γ (IFNγ), interleukin (IL)-1β, IL-4, IL-5, IL-6, IL-13, and IL-17, present in IBD patients are potentially detrimental for bone metabolism and may be responsible for bone loss and increased fracture risk. This perspective aims to review the current literature on the role of inflammatory factors in the pathophysiology of skeletal problems in IBD and to suggest potential treatment to improve bone health, based on a combination of evidence and clinical and pathophysiological reasoning.

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

DSS-induced colitis produces inflammation-induced bone loss while irisin treatment mitigates the inflammatory state in both gut and bone

Chronic pediatric inflammatory bowel disease (IBD) leads to lack of bone accrual, bone loss, and increased fractures. Presently there is no cure, and many IBD treatments incur negative side effects. We previously discovered treatment with exogenous irisin resolved inflammatory changes in the colon, gut lymphatics, and bone in a mild IBD rodent model. Here we assess irisin treatment in severe IBD induced via dextran sodium sulfate (DSS). Male Sprague Dawley rats (2-mo-old) were untreated (Con) or given 2% DSS in drinking water. In week two, half of each group (Con + Ir and DSS + Ir) received injections of recombinant irisin (i.p., 2x/wk). After 4 weeks, gut inflammation was associated with declines in bone mineral density and cancellous bone volume. Furthermore, elevated osteocyte TNF-α, interleukin-6, RANKL, OPG, and sclerostin corresponded with higher osteoclast surfaces and lower bone formation rate in DSS animals as well as lower ultimate load. While irisin treatment improved colon inflammation, there were no improvements in bone density or bone mechanical properties; however, irisin elevated bone formation rate, decreased osteoclast surfaces, and reduced osteocyte pro-inflammatory factors. These data highlight the negative impact of chronic gut inflammation on bone as well as the therapeutic potential of irisin as an anti-inflammatory treatment.

Tumor necrosis factor stimulates fibroblast growth factor 23 levels in chronic kidney disease and non-renal inflammation

Fibroblast growth factor 23 (FGF23) regulates phosphate homeostasis, and its early rise in patients with chronic kidney disease is independently associated with all-cause mortality. Since inflammation is characteristic of chronic kidney disease and associates with increased plasma FGF23 we examined whether inflammation directly stimulates FGF23. In a population-based cohort, plasma tumor necrosis factor (TNF) was the only inflammatory cytokine that independently and positively correlated with plasma FGF23. Mouse models of chronic kidney disease showed signs of renal inflammation, renal FGF23 expression and elevated systemic FGF23 levels. Renal FGF23 expression coincided with expression of the orphan nuclear receptor Nurr1 regulating FGF23 in other organs. Antibody-mediated neutralization of TNF normalized plasma FGF23 and suppressed ectopic renal Fgf23 expression. Conversely, TNF administration to control mice increased plasma FGF23 without altering plasma phosphate. Moreover, in Il10-deficient mice with inflammatory bowel disease and normal kidney function, plasma FGF23 was elevated and normalized upon TNF neutralization. Thus, the inflammatory cytokine TNF contributes to elevated systemic FGF23 levels and also triggers ectopic renal Fgf23 expression in animal models of chronic kidney disease.

Osteocytes reflect a pro-inflammatory state following spinal cord injury in a rodent model

Profound bone loss occurs following spinal cord injury (SCI) resulting in a high incidence of fractures. While likely caused in part by loss of weight-bearing, there is greater bone loss following SCI when compared to that observed in other disuse animal models. Patients with SCI have a protracted inflammatory response, with elevated circulating levels of pro-inflammatory markers. This chronic inflammation could compound the bone loss attributed to disuse and the loss of neural signaling. To assess this, we examined inflammatory markers and bone turnover regulators in osteocytes from rats with a moderate spinal contusion injury (SCI) and intact controls (CON). We counted osteocytes positive for cytokines [tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-17 (IL-17), and interleukin-10 (IL-10)], osteoclastogenesis regulators RANKL and OPG, and the bone formation inhibitor sclerostin, 32 days after the spinal contusion. By day 9 post-injury, the majority of SCI rats had recovered significant locomotor function and were bearing weight on their hindlimbs. However, despite weight-bearing, peripheral QCT scans demonstrated lower bone mass due to SCI in the proximal tibia metaphysis compared to CON. SCI animals also had lower cancellous bone volume, lower bone formation rate (BFR), lower osteoid surface (OS), and higher osteoclast surface (Oc.S). Tibial mid-shaft periosteal BFR was also lower after SCI. Immunohistochemical staining of the distal femur bone revealed cancellous osteocytes positive for TNF-α, IL-6, IL-17, and IL-10 were elevated in SCI animals relative to intact controls. Protein expression of RANKL+, OPG+, and sclerostin+ osteocytes was also higher in SCI rats. At the cortical midshaft, osteocyte TNF-α, IL-6, and sclerostin were statistically higher in SCI vs. CON. With regression analysis, inflammatory factors were associated with changes in bone turnover. In conclusion, inflammatory factors as well as altered mechanical loading influence bone turnover following a moderate SCI. Treatments aimed at minimizing fracture risk after SCI may need to target both the chronically altered inflammatory state as well as disuse-induced bone loss.

The Role of Osteocytes in Inflammatory Bone Loss

Osteoimmunology investigations to-date have demonstrated the significant interactions between bone surface cells, osteoclasts and osteoblasts, and immune cells. However, there is a paucity of knowledge on osteocytes, cells embedded in the bone matrix, and their role in inflammation and inflammatory bone loss. Osteocytes communicate through various mechanisms; directly via dendritic processes and through secretion of proteins that can influence the formation and activity of osteoblasts and osteoclasts. Some osteocyte proteins (e.g., interleukin-6 and RANKL) also have roles within the immune system. In the context of mechanical loading/unloading, the regulatory role of osteocytes is well understood. More recent data on osteocytes in various inflammatory models suggest they may also aid in orchestrating inflammation-induced changes in bone turnover. In inflammatory conditions, osteocytes express multiple pro-inflammatory cytokines which are associated with increases in bone resorption and declines in bone formation. Cytokines are known to also influence cell population growth, maturation, and responsiveness via various signaling modalities, but how they influence osteocytes has not been greatly explored. Furthermore, osteocytes may play regulatory roles in orchestrating bone's response to immunological changes in inflammatory conditions. This review will address what is known about osteocyte biology in physiological conditions and in response to varying immunological conditions, as well as highlight key areas of interest for future investigations.

Systemic Bone Loss After Fracture

A history of prior fracture is the most reliable indicator of prospective fracture risk. Increased fracture risk is not confined to the region of the prior fracture, but is operant at all skeletal sites, providing strong evidence of systemic bone loss after fracture. Animal and human studies suggest that systemic bone loss begins shortly after fracture and persists for several years in humans. In fact, bone quantity and bone quality may never fully return to their pre-fracture levels, especially in older subjects, demonstrating a need for improved understanding of the mechanisms leading to systemic bone loss after fracture in order to reduce subsequent fracture risk. Although the process remains incompletely understood, mechanical unloading (disuse), systemic inflammation, and hormones that control calcium homeostasis may all contribute to systemic bone loss. Additionally, individual factors can potentially affect the magnitude and time course of systemic bone loss and recovery. The magnitude of systemic bone loss correlates positively with injury severity and age. Men may also experience greater bone loss or less recovery than women after fracture. This review details the current understanding of systemic bone loss following fracture, including possible underlying mechanisms and individual factors that may affect this injury response.

Whole egg consumption and cortical bone in healthy children

Eggs contain bioactive compounds thought to benefit pediatric bone. This cross-sectional study shows a positive link between childhood egg intake and radius cortical bone. If randomized trials confirm our findings, incorporating eggs into children's diets could have a significant impact in preventing childhood fractures and reducing the risk of osteoporosis.

INTRODUCTION

This study examined the relationships between egg consumption and cortical bone in children.

METHODS

The cross-sectional study design included 294 9-13-year-old black and white males and females. Three-day diet records determined daily egg consumption. Peripheral quantitative computed tomography measured radius and tibia cortical bone. Body composition and biomarkers of bone turnover were assessed using dual-energy X-ray absorptiometry and ELISA, respectively.

RESULTS

Egg intake was positively correlated with radius and tibia cortical bone mineral content (Ct.BMC), total bone area, cortical area, cortical thickness, periosteal circumference, and polar strength strain index in unadjusted models (r = 0.144-0.224, all P < 0.050). After adjusting for differences in race, sex, maturation, fat-free soft tissue mass (FFST), and protein intakes, tibia relationships were nullified; however, egg intake remained positively correlated with radius Ct.BMC (r = 0.138, P = 0.031). Egg intake positively correlated with total body bone mineral density, BMC, and bone area in the unadjusted models only (r = 0.119-0.224; all P < 0.050). After adjusting for covariates, egg intake was a positive predictor of radius FFST (β = 0.113, P < 0.050) and FFST was a positive predictor of Ct.BMC (β = 0.556, P < 0.050) in path analyses. There was a direct influence of egg on radius Ct.BMC (β = 0.099, P = 0.035), even after adjusting for the mediator, FFST (β = 0.137, P = 0.020). Egg intake was positively correlated with osteocalcin in both the unadjusted (P = 0.005) and adjusted (P = 0.049) models.

CONCLUSION

If the positive influence of eggs on Ct.BMC observed in this study is confirmed through future randomized controlled trials, whole eggs may represent a viable strategy to promote pediatric bone development and prevent fractures.

Omentin-1 prevents inflammation-induced osteoporosis by downregulating the pro-inflammatory cytokines

Osteoporosis is a frequent complication of chronic inflammatory diseases and increases in the pro-inflammatory cytokines make an important contribution to bone loss by promoting bone resorption and impairing bone formation. Omentin-1 is a newly identified adipocytokine that has anti-inflammatory effects, but little is known about the role of omentin-1 in inflammatory osteoporosis. Here we generated global omentin-1 knockout (omentin-1-/-) mice and demonstrated that depletion of omentin-1 induces inflammatory bone loss-like phenotypes in mice, as defined by abnormally elevated pro-inflammatory cytokines, increased osteoclast formation and bone tissue destruction, as well as impaired osteogenic activities. Using an inflammatory cell model induced by tumor necrosis factor-α (TNF-α), we determined that recombinant omentin-1 reduces the production of pro-inflammatory factors in the TNF-α-activated macrophages, and suppresses their anti-osteoblastic and pro-osteoclastic abilities. In the magnesium silicate-induced inflammatory osteoporosis mouse model, the systemic administration of adenoviral-delivered omentin-1 significantly protects from osteoporotic bone loss and inflammation. Our study suggests that omentin-1 can be used as a promising therapeutic agent for the prevention or treatment of inflammatory bone diseases by downregulating the pro-inflammatory cytokines.

Inflammation-induced lymphatic architecture and bone turnover changes are ameliorated by irisin treatment in chronic inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic disease with gastrointestinal dysfunction as well as comorbidities such as inflammation-induced bone loss and impaired immune response. Current treatments for IBD all have negative, potentially severe side effects. We aimed to test whether exogenous treatment with irisin, a novel immunomodulatory adipomyokine, could ameliorate IBD-induced lymphatic and bone alterations. Irisin treatment improved both gut and bone outcomes by mitigating inflammation and restoring structure. In the gut, IBD caused colonic lymphatic hyperproliferation into the mucosal and submucosal compartments. This proliferation in the rodent model is akin to what is observed in IBD patient case studies. In bone, IBD increased osteoclast surface and decreased bone formation. Both gut and osteocytes in bone exhibited elevated levels of TNF-α and receptor activator of NF-κB ligand (RANKL) protein expression. Exogenous irisin treatment restored normal colonic lymphatic architecture and increased bone formation rate concurrent with decreased osteoclast surfaces. After irisin treatment, gut and osteocyte TNF-α and RANKL protein expression levels were no different from vehicle controls. Our data indicate that the systemic immunologic changes that occur in IBD are initiated by damage in the gut and likely linked through the lymphatic system. Additionally, irisin is a potential novel intervention mitigating both local inflammatory changes in the gut and distant changes in bone.-Narayanan, S. A., Metzger, C. E., Bloomfield, S. A., Zawieja, D. C. Inflammation-induced lymphatic architecture and bone turnover changes are ameliorated by irisin treatment in chronic inflammatory bowel disease.

Pediatric-onset inflammatory bowel disease poses risk for low bone mineral density at early adulthood

BACKGROUND

Inflammatory bowel disease (IBD) is known to pose a risk for low bone mineral density (BMD) in children and adults. We aimed to evaluate the impact of pediatric-onset IBD on BMD in adulthood.

METHODS

Records of pediatric-IBD patients were retrospectively reviewed for documentation of dual-energy X-ray absorptiometry (DXA) scans in adulthood. BMD was expressed as z-score.

RESULTS

Sixty one patients were included. Mean (±SD) age at diagnosis was 14.7 (±2.4) years. Mean age at first DXA scan in adulthood was 23.9 years (±4.8). Median BMD z-score was -1.2 SD (IQR, -1.8 to -0.4), significantly lower than expected in normal population (p<0.001). Osteopenia (BMD z-score ≤-1 SD) was noted in 44.3% (n=27), and osteoporosis (BMD z-score ≤-2.5 SD) in 8.2% (n=5). Bone-status showed no correlation with age, disease severity, vitamin D status at diagnosis, IBD subtype or duration of disease. Positive correlation (r=0.306) was identified between low weight z-score at diagnosis and abnormal bone-status in adulthood. Among 36 patients with multiple DXA scans, there was no significant change in BMD during follow-up of 2.4 years.

CONCLUSIONS

Osteopenia and osteoporosis are frequent in adult IBD patients with pediatric-onset disease and correlates with low weight z-score at diagnosis.

Inflammatory Bowel Disease in a Rodent Model Alters Osteocyte Protein Levels Controlling Bone Turnover

Bone loss is a common comorbidity of inflammatory bowel disease (IBD), leading to elevated fracture risk in these patients. Inflammatory factors associated with IBD cause increased bone resorption and decreased bone formation with multiple factors implicated as instigators of these alterations. In this project, we examined the influence of IBD on osteocyte proteins in male rats (2 months old) divided into two groups: induced gut inflammation via 2,4,6-trinitrobenzenesulfonic acid (TNBS) enema, and vehicle control. We examined the prevalence of two pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), an anti-inflammatory cytokine, interleukin-10 (IL-10), the anabolic factor insulin-like growth factor-I (IGF-I), osteoclastogenesis regulators RANKL and OPG, and the bone formation inhibitor sclerostin in osteocytes in three bone compartments 4 weeks after initiation of gut inflammation. Histomorphometry of the proximal tibia and fourth lumbar vertebra revealed lower bone volume, lower bone formation rate (BFR), lower osteoid surface (OS), and higher osteoclast surface (Oc.S) with TNBS. Tibial mid-shaft periosteal BFR was also lower with TNBS. Immunohistochemical staining of the distal femur demonstrated that %TNF-α⁺ , %IL-6⁺ , %RANKL⁺ , and %OPG⁺ osteocytes were elevated in cancellous bone in TNBS animals compared to vehicle. These changes were coincident with increased bone resorption. With regression analysis, %RANKL⁺ osteocytes statistically predicted the increase in cancellous Oc.S (R²  = 0.565). Increased %sclerostin⁺ osteocytes observed in the TNBS treatment predicted declines in cancellous OS (R²  = 0.581) as well as BFR in cancellous and cortical bone (R²  = 0.674, R²  = 0.908, respectively). Contrary to our hypothesis, %IGF-I⁺ osteocytes increased in TNBS animals. In conclusion, the IBD model produced a systemic inflammation that altered the regulatory protein profile in osteocytes that control bone resorption and bone formation, likely contributing to IBD-induced bone loss. These data highlight a potential mechanistic role of osteocytes in inflammatory bone loss associated with IBD and systemic inflammation. © 2017 American Society for Bone and Mineral Research.

Impact of Enteric Health and Mucosal Permeability on Skeletal Health and Lameness in Poultry

Intestinal barrier leakage and/or altered gut microbial composition has been shown to markedly impact both osteoblast and osteoclast activities, systemically through circulation of gut immune cells and cytokines and locally by causing inflammation of extraintestinal organs such as the liver and bone marrow. Mild cases of heightened intestinal inflammation can cause bone loss in male mice in the absence of any overt nutritional deficiencies or weight loss, which has also been shown in chickens that have been infected with Salmonella. For poultry, ingredients selected for feed formulation have also a significant impact on gut health, intestinal microbiota, bone quality, and performance parameters. Consumption of diets with a high content of soluble non-starch polysaccharides (NSP) can affect bone quality parameters by reducing the amount of conjugated bile acids in the intestine, therefore diminishing the absorption of fat-soluble vitamins such as vitamin D and minerals like calcium and phosphorus. Recent enteric inflammation studies have shown that high NSP-containing diets have effects on intestinal viscosity, bone mineral content, and breaking strength, along with increased fluorescein isothiocyanate-dextran (FITC-d) leakage. Other skeletal diseases, such as bacterial chondronecrosis with osteomyelitis and enterococcal spondylitis, have a microbial component that is associated with increased mucosal permeability of the gut. Probiotics targeted toward control of enteric inflammation, either created through infectious disease or poor diet, may serve as a strategy for control of predisposing factors that lead to bone disorders.

Vitamin K deficiency leads to exacerbation of murine dextran sulfate sodium-induced colitis

BACKGROUND

Patients with inflammatory bowel disease (IBD) often exhibit vitamin K deficiency. Vitamin K has been shown to inhibit inflammation via interleukin (IL)-6 suppression. This study aimed to evaluate the effect of vitamin K in a murine model of colitis.

METHODS

Colitis was induced using dextran sulfate sodium (DSS) in mice fed either a vitamin K-deficient (K-def) or a vitamin K-supplemented (K-sup) diet. The clinical and histological severity of colitis was assessed, and levels of cytokine production from the spleen and colonic lamina propria were measured by enzyme-linked immunosorbent assay and quantitative real-time reverse transcription polymerase chain reaction. Cytokine expression levels in CD4(+), CD11b(+), and CD19(+) cells in the presence and absence of vitamin K [menatetrenone (MK-4)] were measured in vitro and apoptosis was determined by caspase 3/7 activity and Annexin V staining.

RESULTS

DSS administration resulted in significantly more severe body weight loss, shorter colon length, and higher histological scores in mice fed a K-def diet than those fed a K-sup diet. IL-6 expression in lamina propria mononuclear cells was significantly higher in the K-def group than in the K-sup group. IL-6 expression was significantly decreased in the presence of MK-4 in CD19(+) cells, but not in the CD4(+) and CD11b(+) subpopulations. Apoptotic cell population in CD19(+) cells was increased in the presence of MK-4 in vitro and in vivo.

CONCLUSIONS

Vitamin K exerts a protective effect against DSS colitis; this effect is associated with IL-6 downregulation. Vitamin K could be a potential treatment target for IBD.

Immune complexes regulate bone metabolism through FcRγ signalling

Autoantibody production and immune complex (IC) formation are frequently observed in autoimmune diseases associated with bone loss. However, it has been poorly understood whether ICs regulate bone metabolism directly. Here we show that the level of osteoclastogenesis is determined by the strength of FcRγ signalling, which is dependent on the relative expression of positive and negative FcγRs (FcγRI/III/IV and IIB, respectively) as well as the availability of their ligands, ICs. Under physiological conditions, unexpectedly, FcγRIII inhibits osteoclastogenesis by depriving other osteoclastogenic Ig-like receptors of FcRγ. Fcgr2b(-/-) mice lose bone upon the onset of a hypergammaglobulinemia or the administration of IgG1 ICs, which act mainly through FcγRIII. The IgG2 IC activates osteoclastogenesis by binding to FcγRI and FcγRIV, which is induced under inflammatory conditions. These results demonstrate a link between the adaptive immunity and bone, suggesting a regulatory role for ICs in bone resorption in general, and not only in inflammatory diseases.

Advanced oxidation protein products decrease the expression of calcium transport channels in small intestinal epithelium via the p44/42 MAPK signaling pathway. Eur J Cell Biol. 2015;94:190-203. [PMID: 25801217 DOI: 10.1016/j.ejcb.2015.02.002]

Advanced oxidation protein products (AOPPs), novel protein markers of oxidative damage, accumulate in the plasma of patients with inflammatory bowel disease (IBD). Osteoporosis, which is closely related to the regulation of intestinal calcium transport channels (CTCs), is a prevalent extraintestinal complication of IBD and is associated with oxidative stress. However, the underlying mechanisms are unknown. The present study aimed to verify whether AOPPs inhibit CTCs in the small intestinal epithelium and to identify the underlying mechanisms that may contribute to IBD-associated osteoporosis. Normal Sprague-Dawley rats were treated with AOPP-modified rat serum albumin. The calcium ion level in serum was not significantly altered, while the duodenal expression of CTCs (e.g. transient receptor potential vanilloid [TRPV6], calbindin-D9k [CaBP-D9k], plasma membrane Ca(2+)-ATPase 1 [PMCA1], and Na(+)/Ca(2+) exchanger 1 [NCX1]) were decreased. In contrast, the levels of the related hormones that regulate calcium absorption including parathyroid hormone (PTH), 25-(OH)D₃, and 1,25-(OH)₂D₃ were increased, although the trend toward an increase in PTH levels was not significant. In order to further investigate the effects of AOPP exposure, we also evaluated the expression of CTCs (including the voltage-dependent L-type calcium channel [CaV1.3], TRPV6, CaBP-D9k, PMCA1, and NCX1) in cultured human colorectal adenocarcinoma cells (Caco-2). The expression levels of total CTC protein and mRNA, except for CaV1.3, were significantly down-regulated in a concentration- and time-dependent manner. Moreover, phosphorylation of p44/42 mitogen-activated protein kinase (MAPK) was observed in vivo and in vitro. The p44/42 inhibitor U0126 reversed the down-regulation of CTCs induced by AOPPs in the Caco-2 monolayer. Our results indicate that AOPPs down-regulate the expression of CTCs through p44/42 MAPK signaling mechanisms in the small intestinal epithelium. These data provide new insights regarding the molecular basis of AOPP-induced reductions in intestinal CTCs, and are relevant to understanding the mechanisms of IBD-associated osteoporosis. Further studies are needed to explore these mechanisms in greater detail.

Adherence and efficacy of screening for low bone mineral density among ulcerative colitis patients treated with corticosteroids

OBJECTIVES

Ulcerative colitis (UC) is associated with an increased risk of metabolic bone disease and fragility fractures. The aim of this study was to assess the adherence to the guidelines issued by the American Gastroenterology Association (AGA) for the screening for low bone density in UC patients and to assess the benefits of dual-energy X-ray absorptiometry (DXA) screening among corticosteroid (CS)-treated UC patients.

METHODS

Nationwide Veterans Affairs system (VA) data were obtained. UC patients followed up in the VA between 2001 and 2011 and the occurrence of fragility fractures were identified using International Classification of Diseases, Ninth Revision codes. Exposure to CSs was assessed using pharmacy data. DXA screening was assessed using the VA procedure database. Post DXA screening, medication use was also assessed from the pharmacy database. Cox regression analysis was performed to calculate the hazard ratio (HR) of fragility fractures among those patients who received DXA compared with those who did not.

RESULTS

We included 5,736 patients. Among them, 80 (1.4%) patients suffered from fragility fractures during the follow-up period. Overall adherence rate to AGA guidelines was 23%. Adherence rate was highest among postmenopausal women (48%) and lowest among men above 50 years of age (20%). UC patients who received DXA screening were more likely to be started on bisfosfonates (P<0.001), calcitonin (P<0.001), vitamin D, and calcium (P<0.001) compared with those who did not receive screening. Those who received DXA screening were half as likely (HR=0.5, 0.3-0.9, P=0.03) to develop fragility fractures as compared with those who did not receive screening. The benefits were more prominent among those with higher CS exposure.

CONCLUSIONS

Rates of DXA screening were low among CS-treated UC patients. Those who received DXA screening were more likely to be started on antiresorptive therapy and supplemental medications and had a 50% reduction in the risk of fragility fractures. More efforts should be directed toward raising the adherence to AGA guidelines and the awareness of DXA benefits.

Comparison of fracture risk between patients with ileal pouch-anal anastomosis for ulcerative colitis and the general population

BACKGROUND

Restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the preferred surgical treatment for ulcerative colitis (UC). Little is known of how the operation affects bone metabolism and fracture risk. The aim of this retrospective cohort study was to investigate fracture risk and serum markers of bone metabolism following IPAA in a national cohort of Danish UC patients.

METHODS

Diagnostic codes for 1757 patients and 8785 controls were obtained from the National Patient Register while blood results were collected from a regional database. Postoperative fracture free survival was evaluated on a Kaplan-Meier plot. Fracture hazard ratios (HR) after IPAA were calculated from Cox proportional hazards regression analysis.

RESULTS

Fracture risk after IPAA was significantly reduced (adjusted HR = 0.49, 95% CI: 0.43; 0.55, p<0.001). Prior fractures and alcoholism independently increased fracture risk significantly. Osteoporotic fracture risk after IPAA was reduced, significantly for wrist fractures (aHR = 0.39, 95% CI: 0.22; 0.71, p = 0.002), and borderline insignificantly for spine fractures (aHR = 0.51, 95% CI: 0.26; 1.01, p = 0.054). Vitamin D and calcium levels were significantly higher in the patient group (61.2 nmol/L vs. 58.9 nmol/L, p = 0.04 and 1.24 mmol/L vs. 1.21 mmol/L, p<0.01, respectively), while parathyroid hormone and phosphate levels were significantly lower (4.9 pmol/L vs. 6.2 pmol/L, p<0.01 and 1.08 mmol/L vs. 1.12 mmol/L, p<0.01, respectively).

CONCLUSION

Fracture risk after IPAA is significantly reduced compared to the general population. Prospective studies are needed to verify the biochemical results.

Initiation of tumor necrosis factor α antagonists and risk of fractures in patients with selected rheumatic and autoimmune diseases

OBJECTIVE

We tested the hypothesis that initiation of tumor necrosis factor α (TNFα) antagonists reduced the risk of fractures compared to nonbiologic comparators in patients with autoimmune diseases.

METHODS

Using 4 large administrative databases, we assembled retrospective cohorts of patients with autoimmune diseases who initiated either a TNFα antagonist or a nonbiologic medication. We identified 3 mutually exclusive disease groups: rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and a combined group: psoriasis (PsO), psoriatic arthritis (PsA), or ankylosing spondylitis (AS). We used baseline covariate data to calculate propensity scores (PS) for each disease group and used Cox regression to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs). We compared the risk of combined hip, radius/ulna, humerus, or pelvic fractures between PS-matched cohorts of new users of TNFα antagonists and nonbiologic comparators.

RESULTS

We identified 9,020, 2,014, and 2,663 new PS-matched episodes of TNFα antagonist and nonbiologic comparator use in RA, IBD, and PsO-PsA-AS cohorts, respectively. The risk of combined fractures was similar between new users of TNFα antagonists and nonbiologic comparators for each disease (HR 1.17, 95% CI 0.91-1.51; HR 1.49, 95% CI 0.72-3.11; and HR 0.92, 95% CI 0.47-1.82 for RA, IBD, and PsO-PsA-AS, respectively). In RA, the risk of combined fractures was associated with an average daily dosage of prednisone equivalents >10 mg/day at baseline compared with no glucocorticoid (HR 1.54, 95% CI 1.03-2.30).

CONCLUSION

The risk of fractures did not differ between initiators of a biologic agent and a nonbiologic comparator for any disease studied. Among RA patients, use of >10 mg/day of prednisone equivalents at baseline increased the fracture risk.

Probiotic use decreases intestinal inflammation and increases bone density in healthy male but not female mice

Osteoporosis can result from intestinal inflammation, as is seen with inflammatory bowel disease. Probiotics, microorganisms that provide a health benefit to the host when ingested in adequate amounts, can have anti-inflammatory properties and are currently being examined to treat inflammatory bowel disease. Here, we examined if treating healthy male mice with Lactobacillus reuteri ATCC PTA 6475 (a candidate probiotic with anti-TNFα activity) could affect intestinal TNFα levels and enhance bone density. Adult male mice were given L. reuteri 6475 orally by gavage for 3×/week for 4 weeks. Examination of jejunal and ileal RNA profiles indicates that L. reuteri suppressed basal TNFα mRNA levels in the jejunum and ileum in male mice, but surprisingly not in female mice. Next, we examined bone responses. Micro-computed tomography demonstrated that L. reuteri 6475 treatment increased male trabecular bone parameters (mineral density, bone volume fraction, trabecular number, and trabecular thickness) in the distal femur metaphyseal region as well as in the lumbar vertebrae. Cortical bone parameters were unaffected. Dynamic and static histomorphometry and serum remodeling parameters indicate that L. reuteri ingestion increases osteoblast serum markers and dynamic measures of bone formation in male mice. In contrast to male mice, L. reuteri had no effect on bone parameters in female mice. Taken together our studies indicate that femoral and vertebral bone formation increases in response to oral probiotic use, leading to increased trabecular bone volume in male mice.

Increased fracture risk and osteoporosis not associated with vitamin D levels in Malaysian patients with inflammatory bowel disease

INTRODUCTION

Osteoporosis and osteopenia are well-recognized complications of inflammatory bowel disease. Previous studies have suggested that vitamin D deficiency is an important risk factor for the development of osteoporosis. We hypothesized that low vitamin D levels is the main reason for reduced bone mineral density in patients with inflammatory bowel disease. We aimed to study its potential role in Malaysia, which is a tropical country with 3 large ethnic groups. We also sought to examine the relationship between fracture risk and bone mineral density in this group.

METHODOLOGY

Relevant history as well as 25-hydroxycholecalciferol (vitamin D) levels and bone mineral density were obtained. Normal, inadequate, and low vitamin D levels were defined as 61-160 nmol/L (24-64 ng/mL), 30-60 nmol/L (12-24 ng/mL), and less than 30 nmol/L (<12 ng/mL), respectively.

RESULTS

Seventy-two patients were recruited. The prevalence of osteopenia and osteoporosis, respectively, were 58% and 17% in the spine and 51% and 14% in the hip. Mean vitamin D level in the group was low at 45.12 ± 17.4 nmol/L (18.05 ± 6.96 ng/mL), but there was no significant association between bone mineral density and vitamin D level. Twelve patients (16.7%) had a fragility fracture after the diagnosis of inflammatory bowel disease. The cumulative fracture incidence was 10% at 5 years and 35% at 10 years. There was a statistically significant association between osteoporosis of hip and a history of fracture (odds ratio 5.889; 95% confidence interval 1.41-24.53, P = .009).

CONCLUSION

Osteoporosis is prevalent among Malaysian patients with inflammatory bowel disease and is associated with a 6-fold increased risk of fractures. Most inflammatory bowel disease patients had inadequate or low vitamin D levels, but there was no association between vitamin D levels and BMD.

Prevalence and predictors of low bone mineral density in males with ulcerative colitis

CONTEXT

Low bone mineral density (BMD) is common in patients with inflammatory bowel diseases.

OBJECTIVE

The objective of the study was to assess the prevalence and the predictors of low BMD (osteoporosis or osteopenia) and fragility fractures among men with ulcerative colitis.

DESIGN

This was a retrospective database analysis.

SETTING

The study was conducted at a nationwide Veterans Affairs health care system.

PATIENTS

Male ulcerative colitis patients who were followed up in the Veterans Affairs system between 2001 and 2011 were identified using the International Classification of Diseases, ninth revision (ICD-9).

MAIN OUTCOME MEASURES

We identified patients with low BMD and fragility fractures using ICD-9 codes. Steroid exposure was assessed using pharmacy data. A multivariate analysis was used to identify the independent effect of systemic steroids on the risk of low BMD and fragility fractures.

RESULTS

We identified 34 665 patients. Among them, 31% used steroids. The prevalence of low BMD was 15.8% and 7.1% among those who used and did not use steroids, respectively (P < .001). Prevalence of fragility fractures was 7.9%, 4.4%, and 1.1% for those with osteoporosis and osteopenia and those without low BMD, respectively (P < .001). Steroid exposure showed a dose-response pattern, patients who had cumulative prednisone exposure of greater than 11 136 mg (10th decile) were more likely to develop low BMD (odds ratio 8.9, P < .001) and fragility fractures (odds ratio 1.8, P < .001) as compared with non-steroid users after controlling for other possible predictors.

CONCLUSION

In this nationwide cohort, the prevalence of low BMD was higher than what was reported for the general male population. There was a strong correlation between the cumulative steroid use and the risk of low BMD. Both steroids and low BMD were independent risk factors for fragility fractures.

Diagnosis and therapeutic management of extra-intestinal manifestations of inflammatory bowel disease

Extra-intestinal manifestations (EIMs) are reported frequently in patients with inflammatory bowel disease (IBD) and may be diagnosed before, concurrently or after the diagnosis of IBD. EIMs in IBD may be classified based on their association with IBD disease activity. The first group has a direct relationship with the activity of the bowel disease and includes pauciarticular arthritis, oral aphthous ulcers, erythema nodosum and episcleritis. The second group of EIMs appears to follow an independent course from the underlying bowel disease activity and include ankylosing spondylitis and uveitis. The third group includes EIMs that may or may not be related to intestinal inflammation, such as pyoderma gangrenosum and probably primary sclerosing cholangitis (PSC). Genetic susceptibility, aberrant self-recognition and immunopathogenic autoantibodies against organ-specific cellular antigens shared by the colon and extra-colonic organs may contribute to the pathogenesis and development of these EIMs. The use of biological agents in the IBD armamentarium has expanded the treatment options for some of the disabling EIMs and these agents form the cornerstone in managing most of the disabling EIMs. PSC is one of the most common hepatobiliary manifestations associated with IBD in which no clear treatment options exist other than endoscopic therapy and liver transplantation. Future research targeting the pathogenesis, early diagnosis and treatment of these EIMs is required.

Diagnosis and therapeutic management of extra-intestinal manifestations of inflammatory bowel disease

Extra-intestinal manifestations (EIMs) are reported frequently in patients with inflammatory bowel disease (IBD) and may be diagnosed before, concurrently or after the diagnosis of IBD. EIMs in IBD may be classified based on their association with IBD disease activity. The first group has a direct relationship with the activity of the bowel disease and includes pauciarticular arthritis, oral aphthous ulcers, erythema nodosum and episcleritis. The second group of EIMs appears to follow an independent course from the underlying bowel disease activity and include ankylosing spondylitis and uveitis. The third group includes EIMs that may or may not be related to intestinal inflammation, such as pyoderma gangrenosum and probably primary sclerosing cholangitis (PSC). Genetic susceptibility, aberrant self-recognition and immunopathogenic autoantibodies against organ-specific cellular antigens shared by the colon and extra-colonic organs may contribute to the pathogenesis and development of these EIMs. The use of biological agents in the IBD armamentarium has expanded the treatment options for some of the disabling EIMs and these agents form the cornerstone in managing most of the disabling EIMs. PSC is one of the most common hepatobiliary manifestations associated with IBD in which no clear treatment options exist other than endoscopic therapy and liver transplantation. Future research targeting the pathogenesis, early diagnosis and treatment of these EIMs is required.

Age-of-onset-dependent influence of NOD2 gene variants on disease behaviour and treatment in Crohn's disease

Background

Influence of genetic variants in the NOD2 gene may play a more important role in disease activity, behaviour and treatment of pediatric- than adult-onset Crohn’s disease (CD).

Methods

85 pediatric- and 117 adult-onset CD patients were tested for the three main NOD2 CD-associated variants (p.R702W, p.G908R and p.10007fs) and clinical data of at least two years of follow-up were compared regarding disease behaviour and activity, response to therapy and bone mineral density (BMD).

Results

Chronic active and moderate to severe course of CD is associated in patients with pediatric-onset (p=0.0001) and NOD2 variant alleles (p=0.0001). In pediatric-onset CD the average PCDAI-Score was significantly higher in patients carrying NOD2 variants (p=0.0008). In addition, underweight during course of the disease (p=0.012) was associated with NOD2 variants. Interestingly, osteoporosis was found more frequently in patients carrying NOD2 variant alleles (p=0.033), especially in pediatric-onset CD patients with homozygous NOD2 variants (p=0.037). Accordingly, low BMD in pediatric-onset CD is associated with a higher PCDAI (p=0.0092), chronic active disease (p=0.0148), underweight at diagnosis (p=0.0271) and during follow-up (p=0.0109). Furthermore, pediatric-onset CD patients with NOD2 variants are more frequently steroid-dependent or refractory (p=0.048) and need long-term immunosuppressive therapy (p=0.0213).

Conclusions

These data suggests that the presence of any of the main NOD2 variants in CD is associated with osteoporosis and an age of onset dependent influence towards underweight, higher disease activity and a more intensive immunosuppressive therapy. This observation supports the idea for an early intensive treatment strategy in children and adolescent CD patients with NOD2 gene variants.

Sclerostin: A Novel Player Regulating Bone Mass in Inflammation?

Inflammation is a common albeit overlooked cause of local and systemic bone loss which results from an imbalance between bone formation and bone resorption. The Wnt pathway, which plays an essential role in the regulation of bone turnover, has been proposed as a potential molecular link between inflammation and inflammatory bone loss. We here recapitulate present knowledge about sclerostin, a Wnt pathway inhibitor, and bone damage in inflammation. A better understanding of sclerostin action and regulation might help in designing an effective treatment strategy in inflammatory bone loss.

Effects of anti-tumor necrosis factor α agents on bone. Curr Opin Rheumatol. 2012;24:576-585. [PMID: 22810364 DOI: 10.1097/bor.0b013e328356d212]

PURPOSE OF REVIEW

Tumor necrosis factor (TNF) inhibitors are effective for achieving disease control in several inflammatory diseases. Although anti-TNF agents can inhibit bone loss in vitro, their role in the prevention of clinically relevant outcomes such as osteoporosis and fractures has not been clearly established.

RECENT FINDINGS

There are many studies of the effects of TNF inhibitors on markers of bone turnover; however, few have measured bone mineral density (BMD) or fractures. Most of these studies have small sample sizes and a minority had a placebo control group. Overall these studies suggest that the antiresorptive effects of anti-TNF therapy are related to control of disease activity.

SUMMARY

The antiresorptive effects of TNF inhibitors are likely related to their anti-inflammatory properties. Studies to date have not demonstrated any advantages of TNF inhibitors over traditional nonbiologic therapies in the prevention of bone loss and fractures.