Possible role of lymphocytes in glucocorticoid-induced increase in trabecular bone mineral density

Protective effects of Stephania pierrei tuber-derived oxocrebanine against LPS-induced acute lung injury in mice

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) have high mortality rates. Though corticosteroids are commonly used for the treatment of these conditions, their efficacy has not been conclusively demonstrated and their use can induce various adverse reactions. Hence, the application of corticosteroids as therapeutic modalities for ALI/ARDS is limited. Meanwhile, the aporphine alkaloid oxocrebanine isolated from Stephania pierrei tubers has demonstrated anti-inflammatory efficacy in murine/human macrophage cell lines stimulated by lipopolysaccharide (LPS). Accordingly, the primary objectives of the present study are to investigate the anti-inflammatory effects of oxocrebanine on LPS-induced murine alveolar epithelial (MLE-12) cells and its efficacy against LPS-induced murine ALI. Results show that oxocrebanine downregulates the abundance of interleukin (IL)-1beta, IL-6, and inducible nitric oxide synthase, as well as the phosphorylation of nuclear factor-kappaB (NF-κB), stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK), p38, protein kinase B (Akt), and glycogen synthase kinase-3beta signalling proteins in LPS-induced MLE-12 cells. Moreover, in a murine ALI model, oxocrebanine lowers lung injury scores and lung wet/dry weight ratios while reducing inflammatory cell infiltration. It also suppresses LPS-induced tumour necrosis factor-alpha and IL-6 in the bronchoalveolar lavage fluid and plasma. Moreover, oxocrebanine downregulates NF-κB, SAPK/JNK, p38, and Akt phosphorylation in the lung tissues of LPS-treated mice. Taken together, the foregoing results show that oxocrebanine provides significant protection against LPS-induced ALI in mice primarily by suppressing various inflammatory signalling pathways in alveolar epithelial cells and lung tissues. Hence, oxocrebanine might prove effective as an anti-inflammatory agent for the treatment of lung inflammation.

Combined growth hormone and insulin-like growth factor-1 rescues growth retardation in glucocorticoid-treated mdxmice but does not prevent osteopenia

Short stature and osteoporosis are common in Duchenne muscular dystrophy (DMD) and its pathophysiology may include an abnormality of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis, which is further exacerbated by long-term glucocorticoid (GC) treatment. Hence, an agent that has anabolic properties and may improve linear growth would be beneficial in this setting and therefore requires further exploration. A 5-week-old x-linked muscular dystrophy (mdx) mice were used as a model of DMD. They were treated with prednisolone ± GH + IGF-1 for 4 weeks and then compared to control mdx mice to allow the study of both growth and skeletal structure. GC reduced cortical bone area, bone fraction, tissue area and volume and cortical bone volume, as assessed by micro computed tomography (CT) In addition, GC caused somatic and skeletal growth retardation but improved grip strength. The addition of GH + IGF-1 therapy rescued the somatic growth retardation and induced additional improvements in grip strength (16.9% increase, P < 0.05 compared to control). There was no improvement in bone microarchitecture (assessed by micro-CT and static histomorphometry) or biomechanical properties (assessed by three-point bending). Serum bone turnover markers (Serum procollagen 1 intact N-terminal propeptide (P1NP), alpha C-terminal telopeptide (αCTX)) also remained unaffected. Further work is needed to maximise these gains before proceeding to clinical trials in boys with DMD.

Preclinical Dose-Escalation Study of ZSJ-0228, a Polymeric Dexamethasone Prodrug, in the Treatment of Murine Lupus Nephritis

Glucocorticoids (GCs) are widely used in the clinical management of lupus nephritis (LN). Their long-term use, however, is associated with the risk of significant systemic side effects. We have developed a poly(ethylene glycol) (PEG)-based dexamethasone (Dex) prodrug (i.e., ZSJ-0228) and in a previous study, demonstrated its potential therapeutic efficacy in mice with established LN, while avoiding systemic GC-associated toxicity. In the present study, we have employed a dose-escalation design to establish the optimal dose-response relationships for ZSJ-0228 in treating LN and further investigated the safety of ZSJ-0228 in lupus-prone NZB/W F1 mice with established nephritis. ZSJ-0228 was intravenously (i.v.) administered monthly at four levels: 0.5 (L1), 1.0 (L2), 3.0 (L3), and 8.0 (L4) mg/kg/day Dex equivalent. For controls, mice were treated with i.v. saline every 4 weeks. In addition, a group of mice received intraperitoneal injections (i.p.) of Dex every day or i.v. injections of Dex every four weeks. Treatment of mice with LN with ZSJ-0228 dosed at L1 resulted in the resolution of proteinuria in 14% of the mice. Mice treated with ZSJ-0228 dosed at L2 and L3 levels resulted in the resolution of proteinuria in ∼60% of the mice in both groups. Treatment with ZSJ-0228 dosed at L4 resulted in the resolution of proteinuria in 30% of the mice. The reduction and/or resolution of the proteinuria, improvement in renal histological scores, and survival data indicate that the most effective dose range for ZSJ-0228 in treating LN in NZB/W F1 mice is between 1.0 and 3.0 mg/kg/day Dex equivalent. Typical GC-associated side effects (e.g., osteopenia, adrenal glands atrophy, etc.) were not observed in any of the ZSJ-0228 treatment groups, confirming its excellent safety profile.

Acute fat loss does not affect bone mass

Obesity has previously been thought to protect bone since high body weight and body mass index are associated with high bone mass. However, some more recent studies suggest that increased adiposity negatively impacts bone mass. Here, we aimed to test whether acute loss of adipose tissue, via adipocyte apoptosis, alters bone mass in age-related obese mice. Adipocyte apoptosis was induced in obese male FAT-ATTAC mice through AP20187 dimerizer-mediated activation of caspase 8 selectively in adipocytes. In a short-term experiment, dimerizer was administered to 5.5 month-old mice that were terminated 2 weeks later. At termination, the total fat mass weighed 58% less in dimerizer-treated mice compared with vehicle-treated controls, but bone mass did not differ. To allow for the detection of long-term effects, we used 9-month-old mice that were terminated six weeks after dimerizer administration. In this experiment, the total fat mass weighed less (− 68%) in the dimerizer-treated mice than in the controls, yet neither bone mass nor biomechanical properties differed between groups. Our findings show that adipose tissue loss, despite the reduced mechanical loading, does not affect bone in age-related obese mice. Future studies are needed to test whether adipose tissue loss is beneficial during more severe obesity.

Short-term glucocorticoid excess blunts abaloparatide-induced increase in femoral bone mass and strength in mice

Glucocorticoids (GCs), such as prednisolone, are widely used to treat inflammatory diseases. Continuously long-term or high dose treatment with GCs is one of the most common causes of secondary osteoporosis and is associated with sarcopenia and increased risk of debilitating osteoporotic fragility fractures. Abaloparatide (ABL) is a potent parathyroid hormone-related peptide analog, which can increase bone mineral density (aBMD), improve trabecular microarchitecture, and increase bone strength. The present study aimed to investigate whether GC excess blunts the osteoanabolic effect of ABL. Sixty 12–13-week-old female RjOrl:SWISS mice were allocated to the following groups: Baseline, Control, ABL, GC, and GC + ABL. ABL was administered as subcutaneous injections (100 μg/kg), while GC was delivered by subcutaneous implantation of a 60-days slow-release prednisolone-pellet (10 mg). The study lasted four weeks. GC induced a substantial reduction in muscle mass, trabecular mineral apposition rate (MAR) and bone formation rate (BFR/BS), and endocortical MAR compared with Control, but did not alter the trabecular microarchitecture or bone strength. In mice not receiving GC, ABL increased aBMD, bone mineral content (BMC), cortical and trabecular microarchitecture, mineralizing surface (MS/BS), MAR, BFR/BS, and bone strength compared with Control. However, when administered concomitantly with GC, the osteoanabolic effect of ABL on BMC, cortical morphology, and cortical bone strength was blunted. In conclusion, at cortical bone sites, the osteoanabolic effect of ABL is generally blunted by short-term GC excess.

The glucocorticoid receptor agonistic modulators CpdX and CpdX-D3 do not generate the debilitating effects of synthetic glucocorticoids

Seventy years after the discovery of their anti-inflammatory properties, glucocorticoids (GCs) remain the mainstay treatment for major allergic and inflammatory disorders, such as atopic dermatitis, asthma, rheumatoid arthritis, colitis, and conjunctivitis, among others. However, their long-term therapeutical administration is limited by major debilitating side effects, e.g., skin atrophy, osteoporosis, Addison-like adrenal insufficiency, fatty liver, and type 2 diabetes syndrome, as well as growth inhibition in children. These undesirable side effects are mostly related to GC-induced activation of both the direct transactivation and the direct transrepression functions of the GC receptor (GR), whereas the activation of its GC-induced indirect tethered transrepression function results in beneficial anti-inflammatory effects. We have reported in the accompanying paper that the nonsteroidal compound CpdX as well as its deuterated form CpdX-D3 selectively activate the GR indirect transrepression function and are as effective as synthetic GCs at repressing inflammations generated in several mouse models of major pathologies. We now demonstrate that these CpdX compounds are bona fide selective GC receptor agonistic modulators (SEGRAMs) as none of the known GC-induced debilitating side effects were observed in the mouse upon 3-mo CpdX treatments. We notably report that, unlike that of GCs, the administration of CpdX to ovariectomized (OVX) mice does not induce a fatty liver nor type 2 diabetes, which indicates that CpdX could be used in postmenopausal women as an efficient "harmless" GC substitute.

Activated B Lymphocyte Inhibited the Osteoblastogenesis of Bone Mesenchymal Stem Cells by Notch Signaling

Estrogen is very important to the differentiation of B lymphocytes; B lymphopoiesis induced by OVX was supposedly involved in osteoporosis. But the effects of B lymphocytes on the osteogenic differentiation of bone mesenchymal stem cells (BMSCs) are not clear. In this study, we detected bone quality and bone loss in a trabecular bone by electronic universal material testing machine and microcomputed tomography (micro-CT) in OVX and splenectomized-ovariectomy (SPX-OVX) rats. Additionally, changes in lymphocytes (B lymphocyte, CD4⁺ and CD8⁺ T lymphocytes, and macrophages) in the bone marrow were analyzed by flow cytometry. The osteogenesis of BMSCs cocultured with normal and LPS-pretreated B lymphocytes was detected by BCIP/NBT and Alizarin red S staining. Measurement of the Notch2, Notch4, Hey1, Hey2, Hes1, and runt-related transcription factor 2 (Runx2) expression in BMSCs cocultured with B lymphocytes was done using real-time PCR. The effects of dexamethasone and DAPT (inhibitor of Notch signaling) on osteogenesis of BMSCs were detected by BCIP/NBT, Alizarin red S staining, and real-time PCR. Osteoporosis happened in OVX rats, more serious in SPX-OVX rats, B lymphocytes increased in OVX rats, and sharply higher in SPX-OVX rats. Osteoporosis did not happen in SPX rats which is still companied with a high increase of B lymphocytes. LPS-pretreated B lymphocytes suppressed the osteogenesis of BMSCs, but the normal B lymphocytes could not. The LPS-pretreated B lymphocytes upregulated the expression of Notch4, Hes1, and Hey2 and downregulated the expression of Runx2 in BMSCs. Dexamethasone and DAPT could downregulate the high expression of Notch4, Hes1, Hey2 and upregulate the low expression of Runx2 in BMSCs which cocultured with LPS treated B lymphocytes, the inhibited ALP and Alizarin red staining in BMSCs which cocultured with LPS treated B lymphocytes also partly restored.

Increased bone mass in a mouse model with low fat mass

Mice with impaired acute inflammatory responses within adipose tissue display reduced diet-induced fat mass gain associated with glucose intolerance and systemic inflammation. Therefore, acute adipose tissue inflammation is needed for a healthy expansion of adipose tissue. Because inflammatory disorders are associated with bone loss, we hypothesized that impaired acute adipose tissue inflammation leading to increased systemic inflammation results in a lower bone mass. To test this hypothesis, we used mice overexpressing an adenoviral protein complex, the receptor internalization and degradation (RID) complex that inhibits proinflammatory signaling, under the control of the aP2 promotor (RID tg mice), resulting in suppressed inflammatory signaling in adipocytes. As expected, RID tg mice had lower high-fat diet-induced weight and fat mass gain and higher systemic inflammation than littermate wild-type control mice. Contrary to our hypothesis, RID tg mice had increased bone mass in long bones and vertebrae, affecting trabecular and cortical parameters, as well as improved humeral biomechanical properties. We did not find any differences in bone formation or resorption parameters as determined by histology or enzyme immunoassay. However, bone marrow adiposity, often negatively associated with bone mass, was decreased in male RID tg mice as determined by histological analysis of tibia. In conclusion, mice with reduced fat mass due to impaired adipose tissue inflammation have increased bone mass.

Overexpression of WNT16 Does Not Prevent Cortical Bone Loss Due to Glucocorticoid Treatment in Mice

Glucocorticoids (GC) are commonly used for the treatment of a wide variety of autoimmune, pulmonary, gastrointestinal, and malignancy conditions. One of the devastating side effects of GC use is osteoporotic fractures, particularly in the spine and hip. Bisphosphonates (BP) are the most commonly prescribed pharmacological agents for the prevention and treatment of GC-induced osteoporosis (GIO). However, GIO is marked by reduced bone formation and BP serves mainly to decrease bone resorption. The WNT signaling pathway plays a major role in bone and mineral homeostasis. Previously, we demonstrated that overexpression of WNT16 in mice led to higher bone mineral density and improved bone microarchitecture and strength. We hypothesized that WNT16 overexpression would prevent bone loss due to glucocorticoid treatment in mice. To test our hypothesis, we treated adult wild-type and WNT16-transgenic mice with vehicle and GC (prednisolone; 2.1 mg/kg body weight) via slow-release pellets for 28 days. We measured bone mass and microarchitecture by dual-energy X-ray absorptiometry (DXA) and micro-CT, and performed gene expression and serum biochemical analysis. We found that GC treatment compared with the vehicle significantly decreased femoral areal bone mineral density (aBMD), bone mineral content (BMC), and cortical bone area and thickness in both wild-type and transgenic female mice. In contrast, the trabecular bone parameters at distal femur were not significantly changed by GC treatment in male and female mice for both genotypes. Further, we observed significantly lower level of serum P1NP and a tendency of higher level of serum TRAP in wild-type and transgenic mice due to GC treatment in both sexes. Gene expression analysis showed lower mRNA levels of Wnt16, Opg, and Opg/Rankl ratio in GC-treated female mice for both genotypes compared with the sex-matched vehicle-treated mice. These data suggest that although WNT16 overexpression resulted in higher baseline bone mineral density and bone volume per trabecular volume (BV/TV) in the transgenic mice, this was insufficient to prevent bone loss in mice due to glucocorticoid treatment.

Glucocorticoids and Bone: Consequences of Endogenous and Exogenous Excess and Replacement Therapy

Osteoporosis associated with long-term glucocorticoid therapy remains a common and serious bone disease. Additionally, in recent years it has become clear that more subtle states of endogenous glucocorticoid excess may have a major impact on bone health. Adverse effects can be seen with mild systemic glucocorticoid excess, but there is also evidence of tissue-specific regulation of glucocorticoid action within bone as a mechanism of disease. This review article examines (1) the role of endogenous glucocorticoids in normal bone physiology, (2) the skeletal effects of endogenous glucocorticoid excess in the context of endocrine conditions such as Cushing disease/syndrome and autonomous cortisol secretion (subclinical Cushing syndrome), and (3) the actions of therapeutic (exogenous) glucocorticoids on bone. We review the extent to which the effect of glucocorticoids on bone is influenced by variations in tissue metabolizing enzymes and glucocorticoid receptor expression and sensitivity. We consider how the effects of therapeutic glucocorticoids on bone are complicated by the effects of the underlying inflammatory disease being treated. We also examine the impact that glucocorticoid replacement regimens have on bone in the context of primary and secondary adrenal insufficiency. We conclude that even subtle excess of endogenous or moderate doses of therapeutic glucocorticoids are detrimental to bone. However, in patients with inflammatory disorders there is a complex interplay between glucocorticoid treatment and underlying inflammation, with the underlying condition frequently representing the major component underpinning bone damage.

Inhibition of heat shock protein 90 rescues glucocorticoid-induced bone loss through enhancing bone formation

Endogenous glucocorticoids (GCs) support normal bone development and bone mass maintenance, whereas long-term exposure to pharmacological dosages of GCs uncouples bone formation and resorption, resulting in GC-induced osteoporosis (GIOP). Heat shock protein 90 (HSP90) chaperoning glucocorticoid receptor (GR) signaling prompts us to speculate that HSP90 plays critical roles in GC-mediated bone formation and GIOP. In the present study, inhibition of HSP90 activity by 17-Demethoxy-17-allyaminogeldanmycin (17-AAG) or knockdown of HSP90 expression by siRNAs attenuated dexamethasone(Dex)-induced GR nuclear accumulation and transcriptional output of GR signaling, whereas overexpression of HSP90α or HSP90β enhanced GR transactivity in C3H10T1/2 cells. Though 17-AAG itself enhanced osteoblastic differentiation, it restored the Dex(10-8M)-induced and Dex(10-6M)-negated osteoblastic differentiation in C3H10T1/2 cells and primary calvarial osteoblasts. Moreover, systemic administration of 17-AAG to mice induced not only osteoclastogenesis but also osteoblastogenesis, whereas bone formation possibly exceeded bone resorption, eventually leading to the increased bone masses. Likewise, systemic administration of 17-AAG to mice restored GC-negated osteoblastogenesis and enhanced GC-induced osteoclastogenesis, similarly, 17-AAG-induced bone formation possibly exceeded both 17-AAG- and GC-induced bone resorption, eventually resulting in rescue of GIOP. Together, the present study has revealed that inhibition of HSP90 restores GIOP through enhancing bone formation, and our findings may help to shed light on the pathogenesis of GIOP and provide targets for the therapeutic intervention of the disease.

Dysregulated systemic lymphocytes affect the balance of osteogenic/adipogenic differentiation of bone mesenchymal stem cells after local irradiation

Background

While it is known that irradiation can induce local and systemic bone loss over time, how focal irradiation induces systemic bone complications remains unclear. Immune cells are thought to be crucial to bone homeostasis, and abnormal immune cells lead to serious disruption of bone homeostasis, such as in acute lymphoblastic leukaemia. This disruption primarily occurs due to inhibition of the osteogenic differentiation of bone mesenchymal stem cells (BMSCs).

Methods

In this study, we detected local and systemic bone loss in trabecular bone by micro-computed tomography (micro-CT) and measurement of peroxisome proliferator-activated receptor gamma (PPARγ) and runt-related transcription factor 2 (RUNX2) expression in BMSCs using real-time polymerase chain reaction and western blotting. Additionally, changes in lymphocytes (B cells and CD4⁺ and CD8⁺ T cells) in the peripheral blood and bone marrow were analysed by flow cytometry. BMSC-derived osteoblasts and adipocytes, cultured in osteogenic or adipogenic media or co-cultured with lymphocytes, were detected by BCIP/NBT, Alizarin Red S and Oil Red O staining.

Results

Focal irradiation induced local and systemic bone loss in trabecular bone. Increased PPARγ expression and decreased RUNX2 expression were observed, accompanied by upregulated adipogenesis and downregulated osteogenesis of BMSCs. B cells and CD8⁺ T lymphocytes were increased in the blood and bone marrow after irradiation, while CD4⁺ T lymphocytes were decreased in the blood. Inhibition of RUNX2 expression and reduction of alkaline phosphatase activity and mineralization deposits were observed in lymphocyte-co-cultured BMSCs, accompanied by an increase in PPARγ expression and in the number of lipid droplets.

Conclusions

Focal irradiation induced local and systemic bone loss in trabecular bone. Increased B cells and CD8⁺ T lymphocytes led to systemic bone loss by decreasing BMSC osteogenesis.

Effects of Bu-Shen-Ning-Xin Decoction on immune cells of the spleen and bone marrow in ovariectomized mice

Osteoimmunology is a new discipline that focuses on the interaction between the bones and the immune system. Immune cells play an important role in bone metabolism. The aim of this study was to illustrate the effect of Bu-Shen-Ning-Xin Decoction (BSNXD) on lymphocytes in the spleen and bone marrow to explore the potential role on the bone. C57BL/6 mice were divided into four groups: sham, ovariectomized (OVX), OVX+BSNXD, and OVX+ estrogen. The sham and OVX groups were treated with saline, the OVX+BSNXD group was treated with BSNXD, and the OVX+ estrogen group was treated with estrogen. After mice were sacrificed, the spleens and bones were collected, and the lymphocytes in the spleen and bone marrow were analyzed. We found that BSNXD lessened the extent of the increase of CD4⁺ and bone marrow. In contrast, these numbers were both increased in the OVX group. BSNXD had no influence on the percentage of γδ T cells. However, it increased the proportion of NK cells in the spleen and bone marrow. BSNXD lessened the extent of the increase of monocytes by ovariectomy. In vitro experiment, we found Tregs can decrease osteoclastogenesis when co-cultured with osteoclast precursor cells. This study suggests that BSNXD changes the immune environment and immune cells have a role in bone metabolism in OVX mice.

Liver-derived IGF-I regulates cortical bone mass but is dispensable for the osteogenic response to mechanical loading in female mice

Low circulating IGF-I is associated with increased fracture risk. Conditional depletion of IGF-I produced in osteoblasts or osteocytes inhibits the bone anabolic effect of mechanical loading. Here, we determined the role of endocrine IGF-I for the osteogenic response to mechanical loading in young adult and old female mice with adult, liver-specific IGF-I inactivation (LI-IGF-I(-/-) mice, serum IGF-I reduced by ≈70%) and control mice. The right tibia was subjected to short periods of axial cyclic compressive loading three times/wk for 2 wk, and measurements were performed using microcomputed tomography and mechanical testing by three-point bending. In the nonloaded left tibia, the LI-IGF-I(-/-) mice had lower cortical bone area and increased cortical porosity, resulting in reduced bone mechanical strength compared with the controls. Mechanical loading induced a similar response in LI-IGF-I(-/-) and control mice in terms of cortical bone area and trabecular bone volume fraction. In fact, mechanical loading produced a more marked increase in cortical bone mechanical strength, which was associated with a less marked increase in cortical porosity, in the LI-IGF-I(-/-) mice compared with the control mice. In conclusion, liver-derived IGF-I regulates cortical bone mass, cortical porosity, and mechanical strength under normal (nonloaded) conditions. However, despite an ∼70% reduction in circulating IGF-I, the osteogenic response to mechanical loading was not attenuated in the LI-IGF-I(-/-) mice.

Glucocorticoids inhibit shaft fracture healing but not metaphyseal bone regeneration under stable mechanical conditions

Objectives

Healing in cancellous metaphyseal bone might be different from midshaft fracture healing due to different access to mesenchymal stem cells, and because metaphyseal bone often heals without a cartilaginous phase. Inflammation plays an important role in the healing of a shaft fracture, but if metaphyseal injury is different, it is important to clarify if the role of inflammation is also different. The biology of fracture healing is also influenced by the degree of mechanical stability. It is unclear if inflammation interacts with stability-related factors.

Methods

We investigated the role of inflammation in three different models: a metaphyseal screw pull-out, a shaft fracture with unstable nailing (IM-nail) and a stable external fixation (ExFix) model. For each, half of the animals received dexamethasone to reduce inflammation, and half received control injections. Mechanical and morphometric evaluation was used.

Results

As expected, dexamethasone had a strong inhibitory effect on the healing of unstable, but also stable, shaft fractures. In contrast, dexamethasone tended to increase the mechanical strength of metaphyseal bone regenerated under stable conditions.

Conclusions

It seems that dexamethasone has different effects on metaphyseal and diaphyseal bone healing. This could be explained by the different role of inflammation at different sites of injury.

Cite this article: Bone Joint Res 2015;4:170–175.

Trabecular bone loss in collagen antibody-induced arthritis

Introduction

Postmenopausal women with rheumatoid arthritis (RA) have increased risk of developing osteoporosis due to chronic inflammation and estrogen deprivation. Collagen antibody-induced arthritis (CAIA), an experimental polyarthritis model representing the effector phase of arthritis, is mainly mediated by the innate immune system. Compared to the widely used collagen-induced arthritis model, CAIA is conveniently short and can be used in C57BL/6 mice, enabling studies with knock-out mice. However, the impact on bone of the CAIA model in C57BL/6 mice has not previously been studied. Therefore, the aim of this study was to determine if CAIA can be used to study postmenopausal arthritis-induced osteoporosis.

Methods

CAIA was induced by administration of collagen-type II antibodies and lipopolysaccharide to ovariectomized female C57BL/6J mice. Control mice received lipopolysaccharide, but no antibodies. Nine days later, femurs were collected for high-resolution micro-CT and histomorphometry. Serum was used to assess cartilage breakdown and levels of complement. Frequencies of immune cell subsets from bone marrow and lymph nodes were analyzed by flow cytometery.

Results

Trabecular bone mass was decreased and associated with increased number of osteoclasts per bone surface in the CAIA model. Also, the frequency of interleukin-17⁺ cells in lymph nodes was increased in CAIA.

Conclusion

The present study show that CAIA, a short reproducible arthritis model that is compatible with C57BL/6 mice, is associated with increased number of osteoclasts and trabecular bone loss.