Are asthmatic patients prone to bone loss?

CCL12 induces trabecular bone loss by stimulating RANKL production in BMSCs during acute lung injury

In the last three years, the capacity of health care systems and the public health policies of governments worldwide were challenged by the spread of SARS-CoV-2. Mortality due to SARS-CoV-2 mainly resulted from the development of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Moreover, millions of people who survived ALI/ARDS in SARS-CoV-2 infection suffer from multiple lung inflammation-induced complications that lead to disability and even death. The lung-bone axis refers to the relationship between lung inflammatory diseases (COPD, asthma, and cystic fibrosis) and bone diseases, including osteopenia/osteoporosis. Compared to chronic lung diseases, the influence of ALI on the skeleton has not been investigated until now. Therefore, we investigated the effect of ALI on bone phenotypes in mice to elucidate the underlying mechanisms. In vivo bone resorption enhancement and trabecular bone loss were observed in LPS-induced ALI mice. Moreover, chemokine (C-C motif) ligand 12 (CCL12) accumulated in the serum and bone marrow. In vivo global ablation of CCL12 or conditional ablation of CCR2 in bone marrow stromal cells (BMSCs) inhibited bone resorption and abrogated trabecular bone loss in ALI mice. Furthermore, we provided evidence that CCL12 promoted bone resorption by stimulating RANKL production in BMSCs, and the CCR2/Jak2/STAT4 axis played an essential role in this process. Our study provides information regarding the pathogenesis of ALI and lays the groundwork for future research to identify new targets to treat lung inflammation-induced bone loss.

Mast Cells and Vitamin D Status: A Clinical and Biological Link in the Onset of Allergy and Bone Diseases

The immune system is made up by an extremely composite group of cells, whose regulated and harmonious activity is fundamental to maintain health. The mast cells are an essential effector of inflammatory response which is characterized by a massive release of mediators accumulated in cytoplasmic secretory granules. However, beyond the effects on immune response, mast cells can modify bone metabolism and are capable of intervening in the genesis of pathologies such as osteoporosis and osteopenia. Vitamin D is recognized to induce changes in bone metabolism, but it is also able to influence immune response, suppressing mast cell activation and IgE synthesis from B cells and increasing the number of dendritic cells and IL-10-generating regulatory T cells. Vitamin D deficit has been reported to worsen sensitization and allergic manifestations in several different experimental models. However, in clinical situations, contradictory findings have been described concerning the correlation between allergy and vitamin D deficit. The aim of this review was to analyze the close relationships between mast cells and vitamin D, which contribute, through the activation of different molecular or cellular activation pathways, to the determination of bone pathologies and the onset of allergic diseases.

Does anti-IgE therapy prevent chronic allergic asthma-related bone deterioration in asthmatic mice?

Current evidence on the association between allergic diseases and bone metabolism indicates asthma may be a potential risk factor for bone health. Using anti-IgE has been proven effective in allergic asthma treatment with a good safety profile; however, its effects on bone health are unknown. Thus, we aimed to investigate whether: (i) chronic allergic asthma (CAA) causes any meaningful changes in bone, and if any, (ii) anti-IgE therapy prevents any CAA-induced adverse alteration. A murine model was used to study CAA. Thirty-two BALB/c male-mice were assigned into four groups (eight-mice/group): Control, CAA (treated with saline), CAA + 100 µg of anti-IgE (CAA + 100AIgE), and CAA + 200 µg of anti-IgE (CAA + 200AIgE) groups. After immunization, saline or anti-IgE was performed intraperitoneally for 8-weeks (in five-sessions at 15-days interval). Three-point bending test was used for the mechanical analysis. Bone calcium (Ca²⁺) and phosphorus (P^3-) as well as Ca/P ratio were evaluated using inductively-coupled plasma-mass-spectrometer (ICP-MS). Compared to control, reductions observed in yield and ultimate moments, rigidity, energy-to-failure, yield and ultimate stresses, elastic modulus, toughness, and post-yield toughness parameters of the CAA group were found significant (P < 0.05). Similar declines were also detected regarding bone Ca²⁺, P^3- and Ca/P ratio (P < 0.05). Compared to control, we observed that 200 µg administration of anti-IgE in CAA + 200AIgE group hindered CAA-related impairments in mineral and mechanical characteristics of bone, while 100 µg in CAA + 100AIgE failed to do so. Our results showed CAA may cause bone loss, leading to a decrease in bone strength, and anti-IgE administration may dose-dependently inhibit these impairments in bone.

The association of asthma and its subgroups with osteoporosis: a cross-sectional study using KoGES HEXA data

Background

A few studies have reported the association between asthma and osteoporosis. We aimed to analyze the association of asthma and its subgroups with osteoporosis in the Korean adult population.

Methods

We used the health examinee (HEXA) data from the Korean Genome and Epidemiology Study (KoGES) obtained between 2004 and 2016. We included 162,579 participants (n = 3,160 with asthma; n = 159,419 controls) who reported their previous histories of asthma and osteoporosis. The participants were categorized into 3 groups based on asthma management: participants who did not need further treatment due to controlled symptoms (well controlled); participants with ongoing treatment (being treated); participants who were not treated even though they had symptoms (not being treated). Multiple logistic regression analyses were used to calculate the adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for osteoporosis. Subgroup analyses for age and sex were conducted.

Results

The prevalence of osteoporosis was higher in patients with asthma (13.6%) than in controls (6.8%). In the full-adjusted model, the aORs for osteoporosis were 1.74 (95% CI 1.55-1.94, P < 0.001) in patients with asthma compared to controls. There were consistent findings across the age and sex subgroups. The aORs for osteoporosis were 1.43 (95% CI 1.10-1.86, P = 0.008) in the well-controlled asthma group; 1.55 (95% CI 1.28-1.89, P < 0.001) in the being treated asthma group; and 1.96 (95% CI 1.66-2.31, P < 0.001) in the not being treated asthma group compared to the control group.

Conclusion

Asthma was associated with osteoporosis in the Korean adult population. Patients with asthma not being treated showed the highest ORs for osteoporosis.

Does Allergy Break Bones? Osteoporosis and Its Connection to Allergy

: Osteoporosis and allergic diseases are important causes of morbidity, and traditionally their coexistence has been attributed to causality, to independent processes, and they were considered unrelated. However, the increasing knowledge in the field of osteoimmunology and an increasing number of epidemiological and biological studies have provided support to a correlation between bone and allergy that share pathways, cells, cytokines and mediators. If the link between allergic pathology and bone alterations appears more subtle, there are conditions such as mastocytosis and hypereosinophilic or hyper-IgE syndromes characterized by the proliferation of cells or hyper-production of molecules that play a key role in allergies, in which this link is at least clinically more evident, and the diseases are accompanied by frank skeletal involvement, offering multiple speculation cues. The pathophysiological connection of allergy and osteoporosis is currently an intriguing area of research. The aim of this review is to summarize and bring together the current knowledge and pursue an opportunity to stimulate further investigation.

Trabecular Bone Score Is More Sensitive to Asthma Severity and Glucocorticoid Treatment Than Bone Mineral Density in Asthmatics

PURPOSE

In asthmatic patients, treatment with corticosteroids, in addition to conventional risk factors for osteoporosis, may lead to bone loss. Trabecular bone score (TBS) is an indirect new parameter of bone quality. This study aimed to evaluate TBS in asthmatics in comparison to propensity score-matched controls and to investigate correlations between TBS and cumulative systemic and inhaled corticosteroid doses 1 year prior to bone mineral density (BMD) measurement in patients with asthma.

METHODS

In total, 627 patients with asthma and the same number of non-asthmatic controls matched for sex and age were included in this retrospective cohort study. TBS was calculated in the lumbar region, based on 2 dimensional projections of dual-energy X-ray absorptiometry.

RESULTS

Patients with severe asthma exhibited lower vertebral TBS values (1.32 ± 0.1) than those with non-severe asthma (1.36 ± 0.1, P = 0.001), with non-active asthma (1.38 ± 0.1, P < 0.001), and without asthma (1.39 ± 0.1, P < 0.001). No significant differences in BMD were noted among the study groups. TBS was significantly correlated with cumulative systemic and inhaled corticosteroid doses as well as asthma duration, lung function and airway hyper-responsiveness. A generalized linear model revealed that age, severe asthma, and frequency of oral corticosteroid burst were significant predictors for TBS levels.

CONCLUSIONS

TBS can be used as an early indicator of altered bone quality stemming from glucocorticoid therapy or, possibly, more severe asthma.

An osteoclastogenesis system, the RANKL/RANK signalling pathway, contributes to aggravated allergic inflammation

BACKGROUND AND PURPOSE

As an osteoclast differentiation factor, receptor activator of NF-κB ligand (RANKL) is produced by various immune cells and may be involved in the pathogenesis of osteoporosis and inflammation. Although RANKL is expressed in most immune cells and tissues, it is not clear how this might affect allergic inflammation.

EXPERIMENTAL APPROACH

The roles of RANKL in allergic rhinitis (AR) were analysed in an ovalbumin (OVA)-induced animal model, human subjects, and a human mast cell line (HMC-1). Small interfering RNA experiments were performed in an OVA-induced AR model.

KEY RESULTS

RANKL and RANKL receptor (RANK) were up-regulated in serum or nasal mucosal tissues of AR patients and AR mice. RANKL and RANK were colocalised in mast cells of nasal mucosa tissue. Depletion of RANKL by RANKL siRNA ameliorated AR symptoms and reduced AR-related biomarkers, including thymic stromal lymphopoietin (TSLP), IgE, histamine, and inflammatory cell infiltration, whereas recombinant RANKL increased AR responses and TSLP levels. In addition, functional deficiency of TSLP decreased AR responses induced by RANKL. In human mast cells, interaction of RANKL with RANK increased production of TSLP and inflammatory cytokines. Production of TSLP by RANKL stimulation was mediated through activation of the PI3K, MAPK, caspase-1, and NF-κB pathways. Furthermore, dexamethasone alleviated RANKL-induced inflammatory reactions in AR models.

CONCLUSION AND IMPLICATIONS

Collectively, these data suggest that RANKL may induce development of AR through up-regulation of TSLP.

Sex differences impact the lung-bone inflammatory response to repetitive inhalant lipopolysaccharide exposures in mice

Skeletal health consequences associated with inflammatory diseases of the airways significantly contribute to morbidity. Sex differences have been described independently for lung and bone diseases. Repetitive inhalant exposure to lipopolysaccharide (LPS) induces bone loss and deterioration in male mice, but comparison effects in females are unknown. Using an intranasal inhalation exposure model, 8-week-old C57BL/6 male and female mice were treated daily with LPS (100 ng) or saline for 3 weeks. Bronchoalveolar lavage fluids, lung tissues, tibias, bone marrow cells, and blood were collected. LPS-induced airway neutrophil influx, interleukin (IL)-6 and neutrophil chemoattractant levels, and bronchiolar inflammation were exaggerated in male animals as compared to female mice. Trabecular bone micro-CT imaging and analysis of the proximal tibia were conducted. Inhalant LPS exposures lead to deterioration of bone quality only in male mice (not females) marked by decreased bone mineral density, bone volume/tissue volume ratio, trabecular thickness and number, and increased bone surface-to-bone volume ratio. Serum pentraxin-2 levels were modulated by sex differences and LPS exposure. In proof-of-concept studies, ovarectomized female mice demonstrated LPS-induced bone deterioration, and estradiol supplementation of ovarectomized female mice and control male mice protected against LPS-induced bone deterioration findings. Collectively, sex-specific differences exist in LPS-induced airway inflammatory consequences with significant differences found in bone quantity and quality parameters. Male mice demonstrated susceptibility to bone loss and female animals were protected, which was modulated by estrogen. Therefore, sex differences influence the biologic response in the lung-bone inflammatory axis in response to inhalant LPS exposures.

Abnormal microarchitecture and stiffness in postmenopausal women using chronic inhaled glucocorticoids

Postmenopausal (PM) women using inhaled glucocorticoids (IGCs) had substantial abnormalities in volumetric BMD (vBMD), microarchitecture, and stiffness using high resolution peripheral computed tomography (HRpQCT) compared to age- and race-matched controls. Abnormalities were most severe at the radius. These preliminary results suggest that there may be major, heretofore unrecognized, skeletal deficits in PM women using IGCs.

INTRODUCTION

While oral glucocorticoids are well recognized to have destructive skeletal effects, less is known about the effects of IGCs. The detrimental skeletal effects of IGCs may be greatest in PM women, in whom they compound negative effects of estrogen loss and aging. The goal of this study was to evaluate microarchitecture and stiffness in PM women using chronic IGCs.

METHODS

This case-control study compared PM women using IGCs for ≥ 6 months (n = 20) and controls matched for age and race/ethnicity (n = 60). Skeletal parameters assessed included areal BMD (aBMD) by DXA, trabecular and cortical vBMD and microarchitecture by HRpQCT of the radius and tibia, and whole bone stiffness by finite element analysis.

RESULTS

By DXA, mean values in both groups were in the osteopenic range; hip aBMD was lower in IGC users (P < 0.04). By HRpQCT, IGC users had lower total, cortical, and trabecular vBMD at both radius and tibia (all P < 0.05). IGC users had lower cortical thickness, lower trabecular number, greater trabecular separation and heterogeneity at the radius (all P < 0.03), and greater heterogeneity at the tibia (P < 0.04). Whole bone stiffness was lower in IGC users at radius (P < 0.03) and tended to be lower at the tibia (P = 0.09).

CONCLUSIONS

PM women using IGCs had substantial abnormalities in vBMD, microarchitecture, and stiffness compared to controls. These abnormalities were most severe at the radius. These preliminary results suggest that there may be major, heretofore unrecognized, skeletal deficits in PM women using IGCs.

The Effect of Inhalant Organic Dust on Bone Health

PURPOSE OF REVIEW

Agriculture remains a major economic sector globally, and workers experience high rates of chronic inflammatory lung and musculoskeletal diseases. Whereas obstructive pulmonary diseases are known risk factors for bone loss, the underlying relationship between lung inflammation and bone health is not well known.

RECENT FINDINGS

An agriculture organic dust extract inhalation animal model has recently linked lung injury-induced inflammation to systemic bone loss. This process is dependent upon lipopolysaccharide and the toll-like receptor 4 (TLR4) signaling pathway. Downstream systemic interleukin-6 is a key mediator that subsequently activates osteoclastogenesis. Age is a host factor that impacted bone disease with younger mice demonstrating increased susceptibility to bone loss following inhalant exposures as compared to older mice. Supplemental dietary vitamin D was shown to prevent organic dust-induced bone loss, but not lung disease, in animals. Recent animal studies provide new mechanistic insight into the lung-bone inflammatory axis. Host factors, diet, and lipopolysaccharide/TLR4 signaling pathways play a significant role in explaining how inhalant organic dust exposures impact bone health. These investigations might lead to specific targeted therapeutic approaches.

Osteoblasts Are Rapidly Ablated by Virus-Induced Systemic Inflammation following Lymphocytic Choriomeningitis Virus or Pneumonia Virus of Mice Infection in Mice

A link between inflammatory disease and bone loss is now recognized. However, limited data exist on the impact of virus infection on bone loss and regeneration. Bone loss results from an imbalance in remodeling, the physiological process whereby the skeleton undergoes continual cycles of formation and resorption. The specific molecular and cellular mechanisms linking virus-induced inflammation to bone loss remain unclear. In the current study, we provide evidence that infection of mice with either lymphocytic choriomeningitis virus (LCMV) or pneumonia virus of mice (PVM) resulted in rapid and substantial loss of osteoblasts from the bone surface. Osteoblast ablation was associated with elevated levels of circulating inflammatory cytokines, including TNF-α, IFN-γ, IL-6, and CCL2. Both LCMV and PVM infections resulted in reduced osteoblast-specific gene expression in bone, loss of osteoblasts, and reduced serum markers of bone formation, including osteocalcin and procollagen type 1 N propeptide. Infection of Rag-1-deficient mice (which lack adaptive immune cells) or specific depletion of CD8+ T lymphocytes limited osteoblast loss associated with LCMV infection. By contrast, CD8+ T cell depletion had no apparent impact on osteoblast ablation in association with PVM infection. In summary, our data demonstrate dramatic loss of osteoblasts in response to virus infection and associated systemic inflammation. Further, the inflammatory mechanisms mediating viral infection-induced bone loss depend on the specific inflammatory condition.

Limethason reduces airway inflammation in a murine model of ovalbumin-induced chronic asthma without causing side effects

Airway inflammation is the major pathological feature of asthma. Thus, the current therapeutic strategy for asthma is to control inflammation. Limethason, an anti-inflammation drug, is widely used in rheumatoid arthritis treatment. The aim of the present study was to detect the anti-inflammatory effect and side effects of limethason on airways that were sensitized with ovalbumin in a murine model of chronic asthma. In the present study, BALB/c mice were sensitized with ovalbumin. Airway hyperresponsiveness was estimated, and hematoxylin and eosin staining, Periodic acid-Schiff staining and bronchoalveolar lavage were used to detect the effect on chronic asthma. Limethason effectively reduced airway hyperresponsiveness, and inhibited inflammatory cell infiltration and mucus secretion. Bronchoalveolar lavage fluid analysis revealed that limethason suppressed levels of airway eosinophils. In the period of treatment, limethason exhibited no influence on morphology of the femoral head, bone mineral content or bone mineral density, which were detected by histological studies and dual-energy X-ray absorptiometry. The index of liver, spleen, kidney, gastrocnemius and brown adipose tissue also demonstrated that limethason had no adverse effects on organs and tissues. The present study revealed that limethason could effectively reduce inflammation in an asthma mouse model without side effects. Therefore, limethason may have therapeutic potential for treating chronic asthma clinically.

Association Between Inhaled Corticosteroid Use and Bone Fracture in Children With Asthma

IMPORTANCE

Daily use of inhaled corticosteroids is a widely recommended treatment for mild persistent asthma in children. There is concern that, similar to systemic corticosteroids, inhaled corticosteroids may have adverse effects on bone health.

OBJECTIVE

To determine whether there is an increased risk of bone fracture associated with inhaled corticosteroid use in children with asthma.

DESIGN, SETTING, AND PARTICIPANTS

In this population-based nested case-control study, we used health administrative databases to identify a cohort of children aged 2 to 18 years with a physician diagnosis of asthma between April 1, 2003, and March 31, 2014, who were eligible for public drug coverage through the Ontario Drug Benefit Program (Ontario, Canada). We matched cases of first fracture after asthma diagnosis to fracture-free controls (ratio of 1 to 4) based on date of birth (within 1 year), sex, and age at asthma diagnosis (within 2 years). We used a 1-year lookback period to ascertain history of inhaled corticosteroid use. Multivariable conditional logistic regression was used to obtain an odds ratio (OR) with 95% confidence interval for fracture, comparing no inhaled corticosteroid use vs current, recent, and past use.

EXPOSURES

Inhaled corticosteroid use during the child's 1-year lookback period, measured as current user if the prescription was filled less than 90 days prior to the index date, recent user (91-180 days), past user (181-365 days), or no use.

MAIN OUTCOMES AND MEASURES

First emergency department visit for fracture after asthma diagnosis, identified using International Statistical Classification of Diseases and Related Health Problems, 10th Revision codes.

RESULTS

This study included 19 420 children (61.0% male; largest proportion of children, 31.5%, were aged 6-9 years at their index date). The multivariable regression results did not show a significant association between first fracture after asthma diagnosis and current use (OR, 1.07; 95% CI, 0.97-1.17), recent use (OR, 0.96; 95% CI, 0.86-1.07), or past use (OR, 1.00; 95% CI, 0.91-1.11) of inhaled corticosteroids, compared with no use, while adjusting for sociodemographic factors and other medication use. However, use of systemic corticosteroids in the 1-year lookback period resulted in greater odds of fracture (OR, 1.17; 95% CI, 1.04-1.33).

CONCLUSIONS AND RELEVANCE

Systemic corticosteroids, but not inhaled corticosteroids, were significantly associated with increased odds of fracture in the pediatric asthma population.

Quantitative Ultrasound Measurement at the Hand Phalanges Does Not Reveal Skeletal Disturbances in Children With Bronchial Asthma: A Longitudinal Observation

OBJECTIVES

To assess the skeletal status in asthmatic children treated with inhaled corticosteroids in a longitudinal observation by quantitative ultrasound (US) measurement at the hand phalanges.

METHODS

Thirty-four children were studied prospectively. Quantitative US measurements were performed at baseline and after a mean ± SD of 2.35 ± 0.20 years. The obtained results were compared to age-, sex-, and body size-matched control participants selected from a database of previously examined healthy children. Individual changes in the amplitude-dependent speed of sound (Ad-SoS) during the follow-up period were also analyzed.

RESULTS

The mean age of the asthmatic children was 10.6 ± 2.5 years. The mean Ad-SoS in the asthmatic children at baseline was 1940.5 ± 49.6 m/s, and the mean Z score was -0.26 ± 0.80. Corresponding values at the follow-up examination were 1976.2 ± 63.6 m/s and -0.18 ± 1.16. The results did not differ significantly in comparison to the healthy controls. The analysis of individual changes in Ad-SoS revealed that 18 participants had a significant increase in this parameter (ie, exceeding the least significant change threshold), and 16 did not have a significant change in their values. No one had a significant decrease in Ad-SoS.

CONCLUSIONS

Quantitative US at the hand phalanges applied as a diagnostic tool revealed no essential differences in the pattern of skeletal development between asthmatic children treated with inhaled glucocorticosteroids and healthy controls.

Systemic IL-6 Effector Response in Mediating Systemic Bone Loss Following Inhalation of Organic Dust

Airway and skeletal diseases are prominent among agriculture workers. Repetitive inhalant exposures to agriculture organic dust extract (ODE) induces bone deterioration in mice; yet the mechanisms responsible for connecting the lung-bone inflammatory axis remain unclear. We hypothesized that the interleukin (IL)-6 effector response regulates bone deterioration following inhalant ODE exposures. Using an established intranasal inhalation exposure model, wild-type (WT) and IL-6 knockout (KO) mice were treated daily with ODE or saline for 3 weeks. ODE-induced airway neutrophil influx, cytokine/chemokine release, and lung pathology were not reduced in IL-6 KO animals compared to WT mice. Utilizing micro-computed tomography, analysis of tibia showed that loss of bone mineral density, volume, and deterioration of bone micro-architecture, and mechanical strength induced by inhalant ODE exposures in WT mice were absent in IL-6 KO animals. Compared to saline treatments, bone-resorbing osteoclasts and bone marrow osteoclast precursor populations were also increased in ODE-treated WT but not IL-6 KO mice. These results show that the systemic IL-6 effector pathway mediates bone deterioration induced by repetitive inhalant ODE exposures through an effect on osteoclasts, but a positive role for IL-6 in the airway was not demonstrated. IL-6 might be an important link in explaining the lung-bone inflammatory axis.

Adequate Vitamin D Intake but Low Serum Levels in Pediatric Asthma Patients: A Pilot Study, Alberta Children's Hospital

Background. We assessed vitamin D intakes and serum 25(OH) vitamin D levels in pediatric asthma patients on moderate-to-high dose inhaled steroids and compared them to published findings of healthy children in our city. Methods. Parents and/or patients were interviewed to estimate the children's vitamin D intakes from foods and supplements (using an adapted validated food frequency questionnaire) and asthma duration and management. Vitamin D status: serum 25-hyroxy vitamin D (25(OH)D) was obtained from the medical records. Results. Vitamin D intakes from food and supplements of the asthma patients (n = 20, 742 ± 185 IU/day) were significantly higher compared to healthy Canadian children (n = 1442, 229 ± 121 IU/day). Despite higher vitamin D intakes, the children had nonsignificantly lower serum 25(OH) vitamin D levels compared to the comparison group. Serum 25(OH)D levels increased by 3.6 nmol/L with each 100 IU of vitamin D intake (95% Confidence interval = 2.0-4.0, R² = 0.931, and p = 0.001). Conclusion. Since adequate vitamin D status in asthma patients is necessary to support bone mineral accretion, it is important to achieve adequate vitamin D status by checking serum 25(OH)D status and supplement accordingly.

Toll-Like Receptor 4 Signaling Pathway Mediates Inhalant Organic Dust-Induced Bone Loss

Agriculture workers have increased rates of airway and skeletal disease. Inhalant exposure to agricultural organic dust extract (ODE) induces bone deterioration in mice; yet, mechanisms underlying lung-bone crosstalk remain unclear. Because Toll-like receptor 2 (TLR2) and TLR4 are important in mediating the airway consequences of ODE, this study investigated their role in regulating bone responses. First, swine facility ODE stimulated wild-type (WT) bone marrow macrophages to form osteoclasts, and this finding was inhibited in TLR4 knock-out (KO), but not TLR2 KO cells. Next, using an established intranasal inhalation exposure model, WT, TLR2 KO and TLR4 KO mice were treated daily with ODE or saline for 3 weeks. ODE-induced airway neutrophil influx and cytokine/chemokine release were similarly reduced in TLR2 and TLR4 KO animals as compared to WT mice. Utilizing micro-computed tomography (CT), analysis of tibia showed loss of bone mineral density, volume and deterioration of bone micro-architecture and mechanical strength induced by ODE in WT mice were significantly reduced in TLR4 but not TLR2 KO animals. Bone marrow osteoclast precursor cell populations were analyzed by flow cytometry from exposed animals. In WT animals, exposure to inhalant ODE increased osteoclast precursor cell populations as compared to saline, an effect that was reduced in TLR4 but not TLR2 KO mice. These results show that TLR2 and TLR4 pathways mediate ODE-induced airway inflammation, but bone deterioration consequences following inhalant ODE treatment is strongly dependent upon TLR4. Thus, the TLR4 signaling pathway appears critical in regulating the lung-bone inflammatory axis to microbial component-enriched organic dust exposures.

Abnormal bone mineral density and bone turnover marker expression profiles in patients with primary spontaneous pneumothorax

BACKGROUND

To examine the bone mineral density (BMD) and the role of bone biomarkers, including bone formation marker procollagen type I aminoterminal propeptide (PINP) and N-terminal midmolecule fragment osteocalcin (N-MID), bone resorption marker b-C-telopeptides of type I collagen (b-CTX) and tartrate-resistant acid phosphatase 5b (TRACP5b) in the pathogenesis of PSP.

METHODS

Eighty-three consecutive primary spontaneous pneumothorax (PSP) patients (PSP group) and 87 healthy individuals (control group) were enrolled in this study. General data, including gender, age, height, weight, and body mass index (BMI), were recorded. Dual-energy X-ray absorptiometry, electrochemiluminescence immunoassay (ECLIA), and ELISA were used to evaluate bone mineral density and expression levels of bone metabolism markers, including PINP, b-CTX, TRACP5b, N-MID, and 25-hydroxyvitamin D (25-OH VD).

RESULTS

Mean height was significantly greater in the PSP group compared with the control group, whereas weight and BMI were lower. Patients in the PSP group had significantly lower average bone mineral density, which mainly manifested as osteopenia (11/12, 91.7%); however, only one patient (8.3%) developed osteoporosis. Serum overexpression of PINP, b-CTX, TRACP5b, and N-MID were found in PSP patients. Expression of 25-OH VD was low in PSP patients. Bone resorption markers showed positive linear relationships with bone formation markers in all participants; whereas only TRACP5b expression negatively correlated with 25-OH VD. Expression levels of all bone turnover markers negatively correlated with BMI. Regression analysis identified risk factors of PSP as age, height, weight, and TRACP5b and 25-OH VD expression levels; whereas gender and PINP, b-CTX, and N-MID expression levels were not significantly associated with the onset of PSP.

CONCLUSIONS

It had lower bone mineral density in PSP patients. Bone formation marker PINP, N-MID and bone resorption marker b-CTX, TRACP5b were upregulated in PSP patients. 25-OH VD expression was relatively low in this population of PSP patients. Age, height, weight, and expression levels of TRACP5b and 25-OH VD may be risk factors for PSP.

The Skeletal Effects of Inhaled Glucocorticoids

The skeletal effects of inhaled glucocorticoids are poorly understood. Children with asthma treated with inhaled glucocorticoids have lower growth velocity, bone density, and adult height. Studies of adults with asthma have reported variable effects on BMD, although prospective studies have demonstrated bone loss after initiation of inhaled glucocorticoids in premenopausal women. There is a dose-response relationship between inhaled glucocorticoids and fracture risk in asthmatics; the risk of vertebral and non-vertebral fractures is greater in subjects treated with the highest doses in the majority of studies. Patients with COPD have lower BMD and higher fracture rates compared to controls, however, the majority of studies have not found an additional detrimental effect of inhaled glucocorticoids on bone. While the evidence is not conclusive, it supports using the lowest possible dose of inhaled glucocorticoids to treat patients with asthma and COPD and highlights the need for further research on this topic.

Vitamin D supplementation protects against bone loss following inhalant organic dust and lipopolysaccharide exposures in mice

Systemic bone loss is associated with airway inflammatory diseases; yet, strategies to halt disease progression from inhalant exposures are not clear. Vitamin D might be a potentially protective approach against noxious respirable environmental exposures. We sought to determine whether vitamin D supplementation represents a viable lung- and bone-protective strategy following repetitive inhalant treatments with organic dust extract (ODE) or lipopolysaccharide (LPS) in mice. C57BL/5 mice were maintained on diets with low (1 IU/D/g) or high (10 IU/D/g) vitamin D for 5 weeks and treated with ODE from swine confinement facilities, LPS, or saline daily for 3 weeks per established intranasal inhalation protocol. Lungs, hind limbs, and sera were harvested for experimental outcomes. Serum 25-hydroxyvitamin D levels were tenfold different between low and high vitamin D treatment groups with no differences between inhalant agents and saline treatments. Serum calcium levels were not affected. There was no difference in the magnitude of ODE- or LPS-induced inflammatory cell influx or lung histopathology between high and low vitamin D treatment groups. However, high vitamin D treatment reversed the loss of bone mineral density, bone volume, and bone micro-architecture deterioration induced by ODE or LPS as determined by micro-CT analysis. Bone-resorbing osteoclasts were also reduced by high vitamin D treatment. In the low vitamin D treatment groups, ODE induced the greatest degree of airway inflammatory consequences, and LPS induced the greatest degree of bone loss. Collectively, high-concentration vitamin D was protective against systemic bone loss, but not airway inflammation, resulting from ODE- or LPS-induced airway injury.

Impact of treatment with inhaled corticosteroids on bone mineral density of patients with asthma: related with age

The effect of inhaled corticosteroid on bone mineral density (BMD) was investigated in 44 asthmatic patients after median treatment duration of 6.5 years. Compared with controls, BMD decreased only in patients aged <50 years in both the spine (11.3 %, p = 0.013) and hip (8.8 %, p = 0.044), whereas in patients ≥50 years BMD did not decrease significantly.

INTRODUCTION

The results of studies which addressed the impact of inhaled corticosteroid (ICS) therapy on BMD of patients with asthma are conflicting. This case-control study aimed to compare BMD status in ICS user with asthma with healthy controls according to age.

METHODS

BMD at the lumbar spine (LS), femoral neck (FN) was measured by dual energy X-ray absorptiometry (DEXA). Patients and controls were compared according to BMD gr/cm(2), BMD T-score, BMD Z-score, frequency of osteoporosis (defined as BMD T-score ≤-2.5), and frequency of patients with BMD Z-score <-1 at LS and FN with regard to age <50 and ≥50 years old.

RESULTS

Forty-four ICS user patients (females 63.6 %) with median treatment duration of 6.5 years and 50 controls (females, 69.4 %) with respective mean age of 49.2 ± 9.5 and 47.4 ± 10.5 years (p = 0.38 and p = 0.35) entered the study. Overall LS-BMD and FN-BMD gr/cm2 in total patients were lower than in controls by 6 % (p = 0.065) and 5.9 % (p = 0.09), respectively. In patients <50 years, mean LS-BMD gr/cm(2) was lower than controls by 11.3 % (p = 0.013) and FN-BMD by 8.8 % (p = 0.044). Mean BMD T-score and BMD Z-score in both measurement sites were also lower than controls (p = 0.013 and 0.01, respectively. Frequency of osteoporosis did not differ but frequency of patients with BMD Z-score <-1 was significantly higher in patients (odds ratio (OR) = 6.57 95 % CI, 1.8-23.9, p = 0.004). In age group ≥50 years old, reduction of BMD in both measurement sites did not reach to a significant level.

CONCLUSION

This study indicates that BMD reduction in ICS user with asthma is dependent on age and appears that younger patients are at greater risk of BMD loss. These findings suggest preventive measures particularly in patients <50 years.

Vitamin D as an adjunctive therapy in asthma. Part 1: A review of potential mechanisms

Vitamin D deficiency (VDD) is highly prevalent worldwide. The classical role for vitamin D is to regulate calcium absorption form the gastrointestinal tract and influence bone health. Recently vitamin D receptors and vitamin D metabolic enzymes have been discovered in numerous sites systemically supporting diverse extra-skeletal roles of vitamin D, for example in asthmatic disease. Further, VDD and asthma share several common risk factors including high latitude, winter season, industrialization, poor diet, obesity, and dark skin pigmentation. Vitamin D has been demonstrated to possess potent immunomodulatory effects, including effects on T cells and B cells as well as increasing production of antimicrobial peptides (e.g. cathelicidin). This immunomodulation may lead to asthma specific clinical benefits in terms of decreased bacterial/viral infections, altered airway smooth muscle-remodeling and -function as well as modulation of response to standard anti-asthma therapy (e.g. glucocorticoids and immunotherapy). Thus, vitamin D and its deficiency have a number of biological effects that are potentially important in altering the course of disease pathogenesis and severity in asthma. The purpose of this first of a two-part review is to review potential mechanisms whereby altering vitamin D status may influence asthmatic disease.