Absence of αβ T cells accelerates disuse bone loss in male mice after spinal cord injury

Whether T cells promote bone loss following immobilization after spinal cord injury (SCI) remains undetermined. Therefore, wild-type (WT) and T cell-deficient (Tcrb-/- ) male mice underwent sham or contusion SCI to cause hindlimb paralysis. Femurs were isolated and distal and midshaft regions were evaluated by microcomputed tomography scanning. Bone marrow (BM) levels of bone turnover markers, as well as receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG), were measured by ELISA. At 2 weeks post-SCI, immobilization resulted in marked reduction in trabecular fractional bone volume (55%), thickness (40%), connectivity, and cortical thickness only in the Tcrb-/- animals (interaction with P < 0.05). BM analysis revealed lower bone formation (procollagen type 1 intact N-terminal propeptide), higher bone resorption (tartrate-resistant acid phosphatase-5b), and a higher RANKL/OPG ratio in the Tcrb-/- SCI animals. At 5 weeks post-SCI, while both WT and Tcrb-/- paralyzed animals showed deterioration of all indices of bone structure, they were more severe in Tcrb-/- animals. In summary, unlike other skeletal disorders, loss of αβ T cells compromises, rather than preserves, skeletal integrity under conditions of immobilization.

Anti-citrullinated protein antibodies are associated with osteopenia but not with pain at diagnosis of rheumatoid arthritis: data from the BARFOT cohort

BACKGROUND

Anti-citrullinated protein antibodies (ACPA) have been suggested to have a potential role in both bone loss and pain in rheumatoid arthritis (RA), based on studies in vitro and in animal models. Here we addressed if anti-cyclic citrullinated (anti-CCP) antibodies were associated with osteopenia or pain in patients with RA, at the time for diagnosis.

METHODS

Baseline data from the BARFOT (Better Anti-Rheumatic PharmacOTherapy) cohort, which consists of patients with RA with a disease duration of 1 year or less, were analyzed. To be included, they should have been assessed by anti-CCP, dual-energy X-ray absorptiometry (DEXA) of lumbar spine and hip, and/or digital X-ray radiogrammetry (DXR) of the metacarpal bones. Osteopenia was defined as a z-score < - 1 SD. Pain VAS > 40 mm, was defined as patient unacceptable pain. Multiple logistic regression analyses were performed to assess whether anti-CCP was independently associated with osteopenia or unacceptable pain.

RESULTS

Of the 657 patients, 65% were women, 58% were anti-CCP positive, 37% had osteopenia in the lumbar spine, and 29% had osteopenia in the hip. Sixty-one percent had unacceptable pain at diagnosis. Patients positive for anti-CCP had significantly more frequently osteopenia in the femoral neck and Ward's triangle compared with anti-CCP-negative patients (p = 0.016 and 0.003, respectively). This difference was found in men at any anti-CCP titer, but in women, osteopenia in these hip locations was found only in those with high anti-CCP titers (> 500 IU/ml). Anti-CCP was not associated with osteopenia in the lumbar spine or the metacarpal bones. In multiple logistic regression analyses, anti-CCP was independently associated with osteopenia in the femoral neck and/or Ward's triangle but not with unacceptable pain. Instead, inflammatory variables were independently associated with unacceptable pain.

CONCLUSION

These data show that in patients with early RA, anti-CCP positivity was independently associated with osteopenia in the femoral neck and/or Ward, but not in the lumbar spine. In our patients, we could not confirm a recently suggested association between anti-CCP antibodies and pain. Further studies are necessary to explore the possible clinical relevance of interactions between ACPA, bone, and pain found in vitro and in animal models.

The Role of Autoantibodies in Bone Metabolism and Bone Loss

Many autoimmune diseases are associated with deranged bone metabolism. The resulting localized or systemic bone loss can compromise the quality of life of patients by causing local bone deformities or fragility fractures. There is emerging evidence that antibodies have a direct impact on key players of bone homeostasis, in particular osteoclasts. Clinical and pre-clinical studies provide insight into the function of autoantibodies related to Rheumatoid Arthritis (rheumatoid factor, anti-citrullinated protein antibodies, and anti-carbamylated protein antibodies) and their inflammation-independent interaction with bone cells. Furthermore, we summarize the current knowledge about neutralizing antibodies to the antiresorptive protein osteoprotegerin, which have been described in patients with Coeliac Disease, Rheumatoid Arthritis, and Spondyloarthritis.

Bone Disease in Connective Tissue Disease/Systemic Lupus Erythematosus

This article reviews recent advances in the research of the mechanisms of bone loss, as well as clinical features, economic impact and therapeutic implications of osteoporosis and fractures in patients with systemic lupus erythematosus (SLE) as an illustration of bone disease in a complex systemic autoimmune connective tissue disease. Recent studies demonstrated an increased incidence of osteoporosis and peripheral and vertebral fractures in patients with SLE. The aetiology of bone loss in SLE is multifactorial, including clinical osteoporosis risk factors, systemic inflammation, serological factors, metabolic factors, hormonal factors, possibly genetic factors and medication-induced adverse effects. The incidence of symptomatic fractures in patients with SLE is increased 1.2-4.7-fold and age, disease duration, glucocorticoid use, previous cyclophosphamide use, seizures and a prior cerebrovascular event have been identified as important risk factors. Moreover, a high prevalence of morphometric vertebral fractures was demonstrated, while one in three of these patients has normal bone density, which finding points to the multifactorial aetiology of fractures in SLE. The clinical consequences and economic burden of osteoporosis and fractures as glucocorticoid treatment-related adverse events and the high frequency of glucocorticoid therapy underline the importance of reducing glucocorticoid treatment and prescribing steroid-sparing agents. No data on fall risk and its determinants and the relationship with the occurrence of fractures in patients with SLE are currently available. Fall risk might be increased in lupus patients for several reasons. In addition, the recently reported high prevalence (20%) of frailty in SLE patients may contribute to the increased fracture incidence. Therefore, the relationships between fall risk, frailty and fracture occurrence in SLE might be interesting subjects for future studies.

Correlation study between osteoporosis and hematopoiesis in the context of adjuvant chemotherapy for breast cancer

This retrospective study attempts to establish if a correlation exists between osteoporosis and hematopoiesis before and after adjuvant chemotherapy in the context of non-metastatic breast cancer. Osteoporosis is interpreted both as a direct marker of osteoblastic decline and as an indirect marker of increased bone marrow adiposity within the hematopoietic microenvironment. Patients from the “Centre du Sein” at CHUV (Centre Hospitalier Universitaire Vaudois) undergoing adjuvant chemotherapy were included in this study. Evolution of blood counts was studied in correlation with the osteoporosis status. Toxicity of chemotherapy was coded according to published probability of febrile neutropenia. One hundred forty-three women were included: mean age 52.1 ± 12.5 years, mean BMI (body mass index) 24.4 ± 4.1. BMD (bone mineral density) scored osteoporotic in 32% and osteopenic in 45%. Prior to chemotherapy, BMD was positively correlated with neutrophil (p < 0.001) and thrombocyte (p = 0.01) count; TBS (trabecular bone score) was not correlated with blood count. After the first cycle of chemotherapy, an increase of one point in TBS correlated with a decrease of 57% on the time to reach leucocyte nadir (p = 0.004). There was a positive correlation between BMD and risk of infection (p < 0.001). Our data demonstrates an association between osteoporosis and lower blood counts in a younger cohort than previously published, extending it for the first time to neutrophil counts in females. Our results suggest that the healthier the bone, the earlier the lowest leucocyte count value, prompting further research on this area.

Osteoporosis and osteopenia are not associated with T-cell activation in older cART-treated HIV-infected patients

BACKGROUND

A higher risk of developing osteopenia/ osteoporosis has been seen in HIV-infected patients. We compared HIV-infected patients, all treated with combination antiretroviral therapy (cART), with a low bone mineral density (BMD) (T-score < -1) to those with a normal BMD (T-score > -1), examining the relation with T-cell activation and bone turnover markers (c-terminal telopeptide (CTX) and procollagen type 1 amino-terminal propeptide (P1NP)).

METHODS

In this single visit pilot study, bone turnover markers, T-cell activation (CD38 + HLA - DR +) and senescence (CD57+) of T cells were measured in patients who had previously undergone dual energy X-ray absorptiometry scanning.

RESULTS

All study participants (n = 16) were male, on cART, with a median age of 61 years (IQR 56-66). Nine patients had osteopenia/osteoporosis. When comparing the patients with osteopenia/osteoporosis with those with a normal BMD, no differences in activation and senescence were found. A relation was seen between higher bone formation (P1NP) and patients who were on cART for longer. The median length of cART use was 5.5 years (IQR 4.5-7.8), with all patients on nucleoside reverse transcriptase inhibitors, 88% on tenofovir, 63% on non-nucleoside reverse transcriptase inhibitors (NNRTIs) and 38% on protease inhibitors. Osteopenia/osteoporosis was seen in 100% of the patients on protease inhibitors versus 30% of those on NNRTIs.

CONCLUSION

This study did not find an association between activated T cells and BMD, thus did not explain the higher prevalence of osteopenia/osteoporosis in HIV-infected patients. Interestingly, this small pilot showed that cART might influence BMD, with a possible negative effect for protease inhibitors and a possible protective effect for NNRTIs. These results warrant further investigation.

An Antibody to Notch2 Reverses the Osteopenic Phenotype of Hajdu-Cheney Mutant Male Mice

Notch receptors play a central role in skeletal development and bone remodeling. Hajdu-Cheney syndrome (HCS), a disease characterized by osteoporosis and fractures, is associated with gain-of-NOTCH2 function mutations. To study HCS, we created a mouse model harboring a point 6955C>T mutation in the Notch2 locus upstream of the proline, glutamic acid, serine, and threonine domain, leading to a Q2319X change at the amino acid level. Notch2Q2319X heterozygous mutants exhibited cancellous and cortical bone osteopenia. Microcomputed tomography demonstrated that the cancellous and cortical osteopenic phenotype was reversed by the administration of antibodies generated against the negative regulatory region (NRR) of Notch2, previously shown to neutralize Notch2 activity. Bone histomorphometry revealed that anti-Notch2 NRR antibodies decreased the osteoclast number and eroded surface in cancellous bone of Notch2Q2319X mice. An increase in osteoclasts on the endocortical surface of Notch2Q2319X mice was not observed in the presence of anti-Notch2 NRR antibodies. The anti-Notch2 NRR antibody decreased the induction of Notch target genes and Tnfsf11 messenger RNA levels in bone extracts and osteoblasts from Notch2Q2319X mice. In vitro experiments demonstrated increased osteoclastogenesis in Notch2Q2319X mutants in response to macrophage colony-stimulating factor and receptor activator of nuclear factor-κB ligand, and these effects were suppressed by the anti-Notch2 NRR. In conclusion, Notch2Q2319X mice exhibit cancellous and cortical bone osteopenia that can be corrected by the administration of anti-Notch2 NRR antibodies.

Systemic Inflammatory Mediators and Bone Homeostasis in Intestinal Failure

BACKGROUND

A proinflammatory state has been described in patients with intestinal failure. The prevalence of metabolic bone disease in this group is considerable. It is not known whether this proinflammatory state is related to bone parameters, though bone disease is recognized as a proinflammatory process in postmenopausal women. The purpose of this study was to examine whether inflammation was related to bone disease.

METHODS

Eight patients with parenteral nutrition (PN)-dependent intestinal failure but no recent infections or immunosuppressive medications had serum assayed for interleukin-6 (IL-6), tumor necrosis factor (TNF)-alpha, and its receptors (TNFR-I and TNFR-II), C-reactive protein, and whole blood for lymphocyte proliferation. Routine clinical laboratory measures of vitamin D, parathyroid hormone, serum calcium, and phosphorus within 3 months of the inflammatory measures were compared by Pearson's correlation to the inflammatory measures.

RESULTS

Mean values for calcium, phosphorus, and albumin were normal, but 25-hydroxy vitamin D was reduced and parathyroid hormone and alkaline phosphatase elevated. Serum total calcium was negatively related to TNFR-II, TNF-alpha and positively to T-helper cells. Longer PN dependence was associated with inflammation and negatively with T-helper cells.

CONCLUSIONS

These preliminary findings are hypothesis generating only but support an association of low calcium and longer duration of PN with inflammation in patients with intestinal failure. Whether the inflammation results from vitamin D deficiency or the vitamin D deficiency develops secondary to excessive use of activated vitamin D to modulate inflammation from some other cause, such as a component of PN or repeated infectious challenge, requires further study.

Physiological and pathophysiological bone turnover - role of the immune system

Osteoporosis develops when the rate of osteoclastic bone breakdown (resorption) exceeds that of osteoblastic bone formation, which leads to loss of BMD and deterioration of bone structure and strength. Osteoporosis increases the risk of fragility fractures, a cause of substantial morbidity and mortality, especially in elderly patients. This imbalance between bone formation and bone resorption is brought about by natural ageing processes, but is frequently exacerbated by a number of pathological conditions. Of importance to the aetiology of osteoporosis are findings over the past two decades attesting to a deep integration of the skeletal system with the immune system (the immuno-skeletal interface (ISI)). Although protective of the skeleton under physiological conditions, the ISI might contribute to bone destruction in a growing number of pathophysiological states. Although numerous research groups have investigated how the immune system affects basal and pathological osteoclastic bone resorption, recent findings suggest that the reach of the adaptive immune response extends to the regulation of osteoblastic bone formation. This Review examines the evolution of the field of osteoimmunology and how advances in our understanding of the ISI might lead to novel approaches to prevent and treat bone loss, and avert fractures.

Skeletal inflammation and attenuation of Wnt signaling, Wnt ligand expression, and bone formation in atherosclerotic ApoE-null mice

ApoE-null (ApoE-KO) mice fed a high-fat diet (HFD) develop atherosclerosis, due in part to activation of vascular inflammation by oxidized low-density lipoprotein. Since bone loss also occurs in these mice, we used them to investigate the impact of oxidized lipids on bone homeostasis and to search for underlying pathogenic pathways. Four-month-old female ApoE-KO mice fed a HFD for three months exhibited increased levels of oxidized lipids in bone, as well as decreased femoral and vertebral trabecular and cortical bone mass, compared with ApoE-KO mice on normal diet. Despite HFD-induced increase in expression of Alox15, a lipoxygenase that oxidizes LDL and promotes atherogenesis, global deletion of this gene failed to ameliorate the skeletal impact of HFD. Osteoblast number and function were dramatically reduced in trabecular and cortical bone of HFD-fed mice, whereas osteoclast number was modestly reduced only in trabecular bone, indicating that an imbalance in favor of osteoclasts was responsible for HFD-induced bone loss. These changes were associated with decreased osteoblast progenitors and increased monocyte/macrophages in the bone marrow as well as increased expression of IL-1β, IL-6, and TNF. HFD also attenuated Wnt signaling as evidenced by reduced expression of Wnt target genes, and it decreased expression of pro-osteoblastogenic Wnt ligands. These results suggest that oxidized lipids decrease bone mass by increasing anti-osteoblastogenic inflammatory cytokines and decreasing pro-osteoblastogenic Wnt ligands.

Suppression of Experimental Arthritis and Associated Bone Loss by a Tissue-Selective Estrogen Complex

In addition to the systemic inflammation present in rheumatoid arthritis (RA), decreased estradiol levels in postmenopausal RA patients further accelerate bone loss in these patients. The tissue-selective estrogen complex (TSEC), an estrogen combined with a selective estrogen receptor modulator, is a new hormone replacement therapy option. The first approved TSEC, containing conjugated estrogens and bazedoxifene (BZA), reduces menopausal symptoms and prevents osteoporosis with an improved safety profile compared with conventional hormone replacement therapy. Previous studies have shown that estrogens strongly inhibit experimental arthritis whereas BZA is mildly suppressive. In this study the antiarthritic potential of combined BZA and estradiol is explored for the first time. Female ovariectomized DBA/1 mice were subjected to collagen-induced arthritis, an experimental postmenopausal RA model, and treated with BZA, 17β-estradiol (E2), combined BZA and E2 (BZA/E2), or vehicle. BZA/E2 suppressed arthritis severity and frequency, synovitis, and joint destruction, equally efficient as E2 alone. Unwanted estrogenic proliferative effects on the endometrium were blocked by the addition of BZA, determined by collecting uterine weights. Bone mineral density was measured by peripheral quantitative computed tomography, and all treatments protected collagen-induced arthritis mice from both trabecular and cortical bone loss. Moreover, BZA/E2, but not E2 alone, inhibited preosteoclast formation and reduced serum anticollagen type II antibodies. In conclusion, a TSEC, herein combined BZA/E2, suppresses experimental arthritis and prevents associated bone loss as efficiently as E2 alone but with minimal uterine effects, highlighting the need for clinical trials that evaluate the addition of a TSEC to conventional postmenopausal RA treatment.

Evolutionary medicine and bone loss in chronic inflammatory diseases--A theory of inflammation-related osteopenia

OBJECTIVE

Bone loss is typical in chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, ankylosing spondylitis, systemic lupus erythematosus, multiple sclerosis, inflammatory bowel diseases, pemphigus vulgaris, and others. It is also typical in transplantation-related inflammation and during the process of aging. While we recognized that bone loss is tightly linked to immune system activation or inflamm-aging in the form of acute, chronic active, or chronic smoldering inflammation, bone loss is typically discussed to be an "accident of inflammation."

METHODS

Extensive literature search in PubMed central.

RESULTS

Using elements of evolutionary medicine, energy regulation, and neuroendocrine regulation of homeostasis and immune function, we work out that bone waste is an adaptive, evolutionarily positively selected program that is absolutely necessary during acute inflammation. However, when acute inflammation enters a chronic state due to the inability to terminate inflammation (e.g., in autoimmunity or in continuous immunity against microbes), the acute program of bone loss is a misguided adaptive program.

CONCLUSIONS

The article highlights the complexity of interwoven pathways of osteopenia.

SnapShot: Osteoimmunology

Bone and the immune system interact with each other and share molecular mechanisms to maintain the homeostasis. The paradigm of the osteoimmune system is required for both bone biology and immunology, providing an essential framework for understanding the physiology and pathology of metabolic bone diseases and immunological disorders.

Neutrophil-lymphocyte ratio may be superior to C-reactive protein for predicting the occurrence of postmenopausal osteoporosis

OBJECTIVE

Recent studies revealed that inflammation plays a critical role in bone remodeling and the pathogenesis of postmenopausal osteoporosis, a major health concern. Neutrophil-lymphocyte ratio (NLR) is a cost-effective marker of inflammation that has been linked with several diseases. This study aimed to compare NLR and C-reactive protein (CRP) levels in osteopenic, osteoporotic, and control subjects and to assess the correlation between NLR levels, CRP, and bone mineral density (BMD) in postmenopausal women.

METHODS

In this cross-sectional study, the relationship between NLR, CRP, and BMD in 438 women was investigated using uni- and multivariate analyses. BMD (g/cm²) was measured by dual-energy X-ray absorptiometry (DEXA) at the lumbar spine and femur. Complete blood count (CBC), CRP, glucose/lipid metabolism, and established risk factors were determined.

RESULTS

In the osteoporotic group, NLR and CRP levels were found to be elevated as compared to the osteopenic and control groups (NLR: 4.68 ± 0.72, 3.17 ± 0.43, 2.01 ± 0.54; CRP: 12.3 ± 4.1, 4.1 ± 2.7, 3.2 ± 2.1, respectively). A negative correlation was present between NLR and the lumbar spine (L2-L4) and femoral neck BMD after adjusting other risk factors. There was no correlation between CRP levels and BMD after adjusting other risk factors. NLR was significantly associated with L2-L4 BMD (ß = -0.653, p<0.001) and femoral neck BMD (ß = -0.178, p<0.001), but CRP level had no association with BMD in a multivariate model.

CONCLUSIONS

Our data indicate that NLR may be a better predictor than CRP for occurrence of osteoporosis in postmenopausal women.

Running exercise alleviates trabecular bone loss and osteopenia in hemizygous β-globin knockout thalassemic mice

A marked decrease in β-globin production led to β-thalassemia, a hereditary anemic disease associated with bone marrow expansion, bone erosion, and osteoporosis. Herein, we aimed to investigate changes in bone mineral density (BMD) and trabecular microstructure in hemizygous β-globin knockout thalassemic (BKO) mice and to determine whether endurance running (60 min/day, 5 days/wk for 12 wk in running wheels) could effectively alleviate bone loss in BKO mice. Both male and female BKO mice (1-2 mo old) showed growth retardation as indicated by smaller body weight and femoral length than their wild-type littermates. A decrease in BMD was more severe in female than in male BKO mice. Bone histomorphometry revealed that BKO mice had decreases in trabecular bone volume, trabecular number, and trabecular thickness, presumably due to suppression of osteoblast-mediated bone formation and activation of osteoclast-mediated bone resorption, the latter of which was consistent with elevated serum levels of osteoclastogenic cytokines IL-1α and -1β. As determined by peripheral quantitative computed tomography, running increased cortical density and thickness in the femoral and tibial diaphyses of BKO mice compared with those of sedentary BKO mice. Several histomorphometric parameters suggested an enhancement of bone formation (e.g., increased mineral apposition rate) and suppression of bone resorption (e.g., decreased osteoclast surface), which led to increases in trabecular bone volume and trabecular thickness in running BKO mice. In conclusion, BKO mice exhibited pervasive osteopenia and impaired bone microstructure, whereas running exercise appeared to be an effective intervention in alleviating bone microstructural defect in β-thalassemia.

Increased bone formation and bone mass induced by sclerostin antibody is not affected by pretreatment or cotreatment with alendronate in osteopenic, ovariectomized rats

Clinical studies have revealed a blunting of the bone anabolic effects of parathyroid hormone treatment in osteoporotic patients in the setting of pre- or cotreatment with the antiresorptive agent alendronate (ALN). Sclerostin monoclonal antibody (Scl-Ab) is currently under clinical investigation as a new potential anabolic therapy for postmenopausal osteoporosis. The purpose of these experiments was to examine the influence of pretreatment or cotreatment with ALN on the bone anabolic actions of Scl-Ab in ovariectomized (OVX) rats. Ten-month-old osteopenic OVX rats were treated with ALN or vehicle for 6 wk, before the start of Scl-Ab treatment. ALN-pretreated OVX rats were switched to Scl-Ab alone or to a combination of ALN and Scl-Ab for another 6 wk. Vehicle-pretreated OVX rats were switched to Scl-Ab or continued on vehicle to serve as controls. Scl-Ab treatment increased areal bone mineral density, volumetric bone mineral density, trabecular and cortical bone mass, and bone strength similarly in OVX rats pretreated with ALN or vehicle. Serum osteocalcin and bone formation rate on trabecular, endocortical, and periosteal surfaces responded similarly to Scl-Ab in ALN or vehicle-pretreated OVX rats. Furthermore, cotreatment with ALN did not have significant effects on the increased bone formation, bone mass, and bone strength induced by Scl-Ab in the OVX rats that were pretreated with ALN. These results indicate that the increases in bone formation, bone mass, and bone strength with Scl-Ab treatment were not affected by pre- or cotreatment with ALN in OVX rats with established osteopenia.

Loss-of-function of SHARPIN causes an osteopenic phenotype in mice

SHARPIN is a novel protein thought to interact with SHANK family and is widely expressed in multiple tissues/cells, including osteoblasts and osteoclasts. Loss-of-function of Sharpin develops the chronic proliferative dermatitis mutation (CPDM) in mice as well as a severe inflammation in other organs. The actual function of SHARPIN is poorly understood. Our aim was to determine the functional roles of SHARPIN in bone metabolism by using CPDM mice. The skeletal phenotypes were determined by peripheral quantitative computed tomography, micro-computed tomography, and quantitative real-time RT-PCR, the cellular functions of osteoblasts and osteoclasts were investigated by ex vivo cell culture. Compared to wild-type controls, CPDM mice demonstrated significantly lower total and cortical bone mineral content and bone mineral density, trabecular and cortical bone volume, and trabecular number. The mRNA expression of Runx2, osterix, type I collagen, and osteocalcin was significantly lower in the bone from CPDM mice. Osteoclasts and osteoblasts from CPDM mice were functionally defective. Our result suggests that SHARPIN plays important regulating roles in bone metabolism. These functional roles may either come from systemic chronic inflammatory or directly signaling pathway within bone cells.

Administration of Cyclooxygenase-2 Inhibitor Reduces Joint Inflammation but Exacerbates Osteopenia in IL-1α Transgenic Mice Due to GM-CSF Overproduction

IL-1alpha transgenic (Tg) mice exhibit chronic inflammatory arthritis and subsequent osteopenia, with IL-1-induced GM-CSF playing an important role in the pathogenesis. This study analyzed the mechanisms underlying osteopenia in Tg mice, and the therapeutic effects of the cyclooxygenase-2 inhibitor celecoxib on such osteopenia. Inhibited osteoclast formation was observed in RANKL-treated bone marrow cell (BMC) cultures from Tg mice and coculture of Tg-derived BMCs and wild-type-derived primary osteoblasts (POBs). FACS analysis indicated that this inhibition was attributable to a decreased number of osteoclast precursors within Tg-derived BMCs. Moreover, in coculture of Tg-derived POBs and either Tg- or wild-type-derived BMCs, osteoclast formation was markedly inhibited because Tg-derived POBs produced abundant GM-CSF, known as a potent inhibitor of osteoclast differentiation. Histomorphometric analysis of Tg mice revealed that both bone formation and resorption were decreased, with bone formation decreased more prominently. Interestingly, administration of celecoxib resulted in further deterioration of osteopenia where bone formation was markedly suppressed, whereas bone resorption remained unchanged. These results were explained by our in vitro observation that celecoxib dose-dependently and dramatically decreased osteogenesis by Tg mouse-derived POBs in culture, whereas mRNA expressions of GM-CSF and M-CSF remained unchanged. Consequently, blockade of PGE(2) may exert positive effects on excessively enhanced bone resorption observed in inflammatory bone disease, whereas negative effects may occur mainly through reduced bone formation, when bone resorption is constitutively down-regulated as seen in Tg mice.

Prevalence of IgA-antiendomysial antibody in a patient cohort with idiopathic low bone mineral density

AIM: To investigate the frequency of serum IgA-antiendomysial antibody positivity in patients with low bone mineral density and to assess the risk group for screening of celiac disease.

METHODS: One hundred and thirty-five patients (14 male, 121 female) with idiopathic low bone mineral density were evaluated. The median age was 57.2 years (24-81). Antiendomysial antibody was determined by the immunofluorescence method using a commercial kit (INOVA Diagnostics Inc., CA, USA), which employs a 5 μm thin cryostat section of monkey esophagus as a substrate.

RESULTS: Of the 135 patients evaluated, 13 were found to have positive IgA antiendomysial antibody test (9.6%) response. None of the patients had IgA deficiency. Endoscopic appearance and histological examination were normal in all of these patients. Seropositive patients had significantly lower age (48.9 ± 4.3 vs 59.2 ± 6.2, P < 0.05), higher ratio of male gender (61.5% vs 4.9%, P < 0.01) and pre-menopausal status (8.7% vs 1.3%, P < 0.01). Lumbar spine and femoral neck z-scores, but not t-scores were significantly lower in seropositive patients. Seropositive patients had lower serum 25 (OH) vitamin D, calcium and higher serum parathormone levels than seronegative patients.

CONCLUSION: The screening of celiac disease in idiopathic osteoporosis should be restricted to patients without classical risk factors (younger, pre-menopausal, male gender) for osteoporosis. Bone mineral density measurements using z-scores should be considered for identifying risk groups for celiac disease.

Different effects of raloxifene and estrogen on interleukin-1beta and interleukin-1 receptor antagonist production using in vitro and ex vivo studies

The increase in lumbar spine BMD in response to Raloxifene (RLX), a selective estrogen receptor modulator, is smaller in magnitude compared to the response to treatment with estradiol (E2). The reasons for this observation are unclear. Estrogen has a potent effect on the production of proinflammatory cytokines which support osteoclastogenic and bone resorption. Therefore the different response to RLX may relate, at least in part, to a difference in the ability of RLX to modulate the production of proinflammatory cytokines which are abundant in the red marrow of the vertebrae. The aim of this study was to determine the effect of RLX and E2 both in vitro and ex vivo on the production of the pro-resorptive cytokine interleukin-1beta (IL-1beta) and its antagonist, interleukin-1 receptor antagonist (IL-1ra). We obtained samples of peripheral blood from (a) 10 untreated postmenopausal women with osteopenia (ages 53 to 72 years, mean 61 years), (b) 15 postmenopausal women (ages 52 to 72 years, mean 63 years) at baseline and after 6 months of RLX therapy (60 mg/day) and (c) 10 postmenopausal women (ages 60 to 75 years, mean 64 years) at baseline and 6 months after a single E2 implant (25 mg). Cultures of whole blood from the untreated women were incubated with RLX or 17beta-E2 at 1 pM, 100 pM, 10 nM and 1 microM concentrations. LPS-stimulated whole blood cultures from the raloxifene- and estradiol-treated women were prepared at baseline and at 6 months. IL-1beta and IL-1ra were measured by ELISA in the conditioned media. In vitro there was a significant dose-dependent decrease in IL-1beta and IL-1ra in response to 17beta-E2 (both P<0.0001) which was not apparent in response to RLX (both P>0.05). In ex vivo cultures from women receiving 6 months treatment with E2 implants, there was a significant decrease in IL-1beta (-36+/-8%, P=0.01) but no significant change in IL-1ra (+29+/-20%, P=0.3). There was no significant change in either IL-1beta or IL-1ra after 6 months RLX therapy (+20+/-14% and +12+/-10%, both P>0.05). We conclude that treatment with RLX, unlike estradiol does not modulate the production of the proinflammatory cytokines IL-1beta and IL-1ra using in vitro or ex vivo whole blood culture methods. This may account, at least in part for the reduced efficacy of RLX therapy compared to estrogen which has been observed in vivo on bone mineral density, bone turnover and reduction in fracture risk.

[Evaluation of dietary therapy efficiency, based on clinical and biochemical parameters in patients with cardiovascular disease and osteopenia]

Aim of investigation was to analysis of dietary intake in patients with cardiovascular diseases (CVD) and osteopenia. We studied 13 patients with CDV and osteopenia and 117 control subjects with CDV. Analysis of dietary intake in all patients showed high level consumption of fat, excessive consumption of phosphorus and deficiency in consumption of vitamins A, B1, B2. It was shown that diet-therapy has promoted the most positive changes of the clinical, biochemical and immunological parameters of patients had osteopenia less then control group.

Impaired skeletal development in interleukin-6-transgenic mice: a model for the impact of chronic inflammation on the growing skeletal system

OBJECTIVE

To identify the mediator responsible for the impact of chronic inflammation on skeletal development in children (bone loss, defective peak bone mass accrual, stunted growth), we evaluated the effects of chronic interleukin-6 (IL-6) overexpression on the skeletons of growing prepubertal mice.

METHODS

We studied IL-6-transgenic mice that had high circulating IL-6 levels since birth. Trabecular and cortical bone structure were analyzed by microcomputed tomography. Epiphyseal ossification, growth plates, and calvariae were studied by histology/histomorphometry. Osteoclastogenesis, osteoblast function/differentiation, and the effects of IL-6 on bone cells were studied in vitro. Osteoblast gene expression was evaluated by reverse transcriptase-polymerase chain reaction. The mineral apposition rate was evaluated dynamically in cortical bone by in vivo double fluorescence labeling.

RESULTS

In prepubertal IL-6-transgenic mice, we observed osteopenia, with severe alterations in cortical and trabecular bone microarchitecture, as well as uncoupling of bone formation from resorption, with decreased osteoblast and increased osteoclast number and activity. Increased osteoclastogenesis and reduced osteoblast activity, secondary to decreased precursor proliferation and osteoblast function, were present. IL-6-transgenic mice also showed impaired development of growth plates and epiphyseal ossification centers. Intramembranous and endochondral ossification and the mineral apposition rate were markedly affected, showing the presence of defective ossification.

CONCLUSION

Chronic overexpression of IL-6 alone induces a skeletal phenotype closely resembling growth and skeletal abnormalities observed in children with chronic inflammatory diseases, pointing to IL-6 as a pivotal mediator of the impact of chronic inflammation on postnatal skeletal development. We hypothesize that IL-6-modifying drugs may reduce skeletal defects and prevent the growth retardation associated with these diseases.

Tumour necrosis factor-related apoptosis-inducing ligand and osteoprotegerin serum levels in psoriatic arthritis

OBJECTIVES

The degree of bone loss in patients with psoriatic arthritis (PsA) has not been well-defined. We tested the hypothesis, whether serum levels of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), a pro-apoptotic cytokine and osteoprotegerin (OPG), an anti-osteoclastic cytokine, are associated with changes in biochemical markers of bone turnover or bone mineral density (BMD) in patients with PsA.

METHODS

In a cross-sectional study, we evaluated biochemical markers of bone turnover, BMD and serum levels of TRAIL and OPG in 116 patients with PsA (mean age: 52+/-13 yrs).

RESULTS

In patients with PsA, osteopenia was present in one-third of women and men, while osteoporosis was more frequent in men (10.2%) than in women (1.75%). Serum levels of TRAIL were significantly higher in patients with PsA (66.1+/-45.3 pmol/l) compared with controls (50.0+/-20.1 pmol/l, P<0.01), whereas OPG serum levels were not different. There were no associations between TRAIL or OPG serum levels with BMD and biochemical markers of bone turnover. However, TRAIL serum levels were associated with C-reactive protein (CRP) levels (R = 0.201, P<0.05), whereas OPG serum levels were associated with the erythrocyte sedimentation rate (R=0.215, P<0.05).

CONCLUSION

In summary, BMD is decreased in one-third of patients with PsA, and predominantly men with PsA suffer from osteoporosis. While TRAIL serum levels are increased in PsA and correlated with CRP levels, neither TRAIL nor OPG serum levels are correlated with BMD or markers of bone metabolism.

Alterations in the phenotype and function of immune cells in ovariectomy-induced osteopenic mice

BACKGROUND

Within the last few years, much evidence has been presented on the involvement of the immune system in certain types of bone loss, such as activated T cells in rheumatoid arthritis and in periodontitis. Estrogen deficiency induces bone loss; however, how this deficiency affects the immune system has not been sufficiently studied.

METHODS

To evaluate the effects of estrogen withdrawal on the status and functionality of the immune system, mice were ovariectomized or sham-operated, and 5 weeks after surgery, when osteopenia had developed, several parameters were analysed in spleen and in bone marrow. We analysed bone turnover, cell phenotype by flow cytometry, cell function by cell proliferation assays, and the expression of several genes related to the process.

RESULTS

Five weeks after ovariectomy, augmented osteoclastogenesis persisted in the bone marrow. In addition, the ovariectomized mice had more B-cells and CD3+ T-cells expressing the receptor activator of NF-kappaB ligand (CD3+/RANKL+). The ovariectomized mice had lower serum alkaline phosphatase activity, a normal amount of T cells, lower percentages of CD11b+ and CD51+ cells in the bone marrow, and a lower serum interferon-gamma level compared with sham-operated controls.

CONCLUSIONS

The data suggest that, 5 weeks after ovariectomy, bone turnover remains imbalanced, with increased osteoclastogenesis and a decreased rate of bone formation. Moreover, there is an increase in B-cell formation, with normal and decreased percentages of T cells and myelomonocytic cells (CD11b+), respectively, in the bone marrow. Decreased serum interferon-gamma levels could be involved in the increased osteoclastogenesis found in the present work.

Relations between interleukin-1, its receptor antagonist gene polymorphism, and bone mineral density in postmenopausal Korean women

We investigated the relation between polymorphisms in the interleukin-1(IL-1) and IL-1 receptor antagonist (IL-1ra) gene, and bone mineral density (BMD) in postmenopausal Korean women. The IL-1alpha C(-889)T polymorphism, and IL-1beta C(-511)T polymorphism were examined by restriction fragment length polymorphism, and 86-bp variable number tandem repeat polymorphism in the IL-1ra gene was analyzed by the polymerase chain reaction and electrophoresis in 202 postmenopausal Korean women. Serum osteocalcin, and C-telopeptide of type I collagen were measured using a radioimmunoassay and enzyme-linked immunosorbent assay, respectively. BMD at the lumbar spine and proximal femur was measured by dual-energy X-ray absorptiometer. No significant differences in BMD or in serum bone markers levels were noted across the IL-1alpha or IL-1beta genotype. There were no significant differences in the distribution of IL-1alpha or IL-1beta genotype according to the status of bone mass. BMD in women carrying the A2 allele of the IL-1ra gene was significantly lower than those without this allele, and the A2 allele was more frequent in osteoporotic women than in normal women. These data suggest that IL-1ra gene VNTR polymorphism is a genetic factor that may affect BMD in Korean women.

Cytokine production by whole blood cells: relationship to interleukin gene polymorphism and bone mass

The aims of this study were to investigate the relationships between the production of interleukin-1 (IL-1), and IL-6 system by whole blood cells, and bone mineral density (BMD), and polymorphisms in IL-1 system and IL-6 gene in postmenopausal Korean women. The production of IL-1alpha, IL-1beta, IL-1 receptor antagonist (IL-1ra), IL-6, and soluble IL-6 receptor (sIL-6r) by lipopolysaccharide-stimulated whole blood cells was measured by ELISA in 110 subjects. Serum osteocalcin, C-telopeptide of type I collagen, and BMD at lumbar spine and proximal femur were measured. IL-1alphaC(-889)T polymorphism, IL-1beta C(-511)T polymorphism, 86-base pair variable number tandem repeat polymorphism in the IL-1ra gene, and IL-6 C(-634)G polymorphism were analyzed. The production of IL-1beta correlated positively with BMD at femoral neck, whereas the production of other ILs did not correlate with BMD at the skeletal sites examined. No significant differences in the production of ILs were observed among normal, osteopenic and osteoporotic postmenopausal women, and among the different IL system polymorphisms groups studied. No correlation between bone turnover markers and the production of ILs was noted. In conclusion IL-1beta may regulate bone metabolism at femoral neck, and the IL system polymorphism do not affect the production of ILs by whole blood cells.

Pax5-deficient mice exhibit early onset osteopenia with increased osteoclast progenitors

Pax5 encodes BSAP, a member of the paired box domain transcription factors, whose expression is restricted to B lymphocyte lineage cells. Pax5(-/-) mice have a developmental arrest of the B cell lineage at the pro-B cell stage. We show here that Pax5(-/-) mice are severely osteopenic, missing 60% of their bone mass. The osteopenia can be accounted for by a >100% increase in the number of osteoclasts in bone measured histomorphometrically. This is not due to a lack of B cells, because other strains of B cell-deficient mice do not exhibit this phenotype. There was no difference in the number of osteoclasts produced in vitro by wild-type and Pax5(-/-) bone marrow cells. In contrast, spleen cells from Pax5(-/-) mice produce as much as five times the number of osteoclasts as control spleen cells. Culture of Pax5(-/-) spleen cells yields a population of adherent cells that grow spontaneously in culture without added growth factors for >4 wk. These cells have a monocyte phenotype, produce large numbers of osteoclasts when induced in vitro, and therefore are highly enriched in osteoclast precursors. These data demonstrate a previously unsuspected connection between B cell and osteoclast development and a key role for Pax5 in the control of osteoclast development.

Interactions among human immunodeficiency virus (HIV)-1, interferon-gamma and receptor of activated NF-kappa B ligand (RANKL): implications for HIV pathogenesis

We reported recently that exposure of human T cells to soluble HIV-1 envelope glycoprotein gp120 induced biologically active tumour necrosis factor (TNF)-alpha-related cytokine receptor of activated NF-kappaB ligand (RANKL), the primary drive to osteoclast differentiation and bone resorption. Furthermore, certain anti-HIV protease inhibitors linked clinically to accelerated bone loss in HIV disease blocked the physiological control of RANKL activity by interferon (IFN)-gamma through inhibition of degradation of the RANKL nuclear adapter signalling protein, TNF receptor associated protein 6 (TRAF6). We now report a series of reciprocal interactions among HIV-1, RANKL and IFN-gamma. RANKL augmented HIV replication in acutely and chronically infected cells of T lymphocyte and monocyte lineage, effects which occurred at a transcriptional level in conjunction with activation of NF-kappaB. TNF-alpha and RANKL were markedly synergistic in induction of HIV. Low pharmacological levels of IFN-gamma (0.75-3 ng/ml) suppressed RANKL-driven enhancement of HIV replication, as did L-T6DP-1, a cell-permeable peptide inhibitor of TRAF6. In contrast, HIV replication induced by TNF-alpha and phorbol ester were not inhibited, and in some cases augmented, by IFN-gamma. We conclude that a positive feedback loop exists between RANKL production and HIV replication, which may be relevant to both the pathophysiology of HIV-linked osteopenia and control of HIV growth. This pathway appears distinct from those of other cytokine activators of HIV, with respect to its utilization of TRAF6 and its suppression by IFN-gamma. These data raise the possibility that TRAF-specific inhibitory peptides, alone or in conjunction with IFN-gamma, could be used to regulate HIV activation in vivo.

Interleukin 10-deficient mice develop osteopenia, decreased bone formation, and mechanical fragility of long bones

BACKGROUND & AIMS

Bone loss is a common complication of human inflammatory bowel disease (IBD), but its mechanisms are not understood completely. We investigated bone metabolism in interleukin-10-deficient ( IL-10-/- ) mice, an animal model with IBD features.

METHODS

IL-10-/- male mice (8- and 12-weeks-old) and their age-matched wild-type counterparts (C57BL/6J) were studied. Bone mass of the femur was determined by ashing. Tibial cancellous and cortical bone mass and formation was measured by static and dynamic histomorphometry. Biomechanical strength of the femur was tested. Primary bone marrow stromal cell cultures were used to assess osteoblast generation. Serum levels of 25-OH vitamin D 3, insulin-like growth factor-1 (IGF-1), parathyroid hormone, osteocalcin, and deoxy-pyridinoline cross-links were measured. The presence of colitis was determined histologically, and by IL-12 and interferon-gamma (IFN-gamma) secretion from cultured colonic explants.

RESULTS

Eight- and 12-week-old IL-10-/- mice developed osteopenia of both cancellous and cortical bone, evidenced by lower femoral ash weight, cancellous bone area and surface, trabecular number, and decreased cortical bone area and width. Osteopenia was associated with mechanical fragility, manifested by decreased stiffness and mechanical load at fracture, and was caused by suppressed bone formation, indicated by decreased cancellous double-labeled surface, mineralizing surface, serum osteocalcin level, and mineralized nodule number in bone marrow stromal cell cultures. IL-10-/- mice with colitis had significantly less bone mass compared with IL-10-/- mice without colitis.

CONCLUSIONS

IL-10-/- mice develop the hallmarks of osteoporosis, that is, reduced bone mass, increased mechanical fragility, and suppressed bone formation. The presence of colitis is an important contributor to osteoporosis in IL-10-/- mice.

Colonic dendritic cells, intestinal inflammation, and T cell-mediated bone destruction are modulated by recombinant osteoprotegerin

Autoimmune associated bone disease and intestinal inflammation are closely linked with deregulation and hyperactivation of autoreactive CD4 T cells. How these T cells are activated and mediate disease is not clear. Here we show that in the Interleukin 2-deficient mouse model of autoimmunity spontaneous osteopenia and colitis are caused by increased production of the ligand for receptor activator of NFkappaB (RANKL). RANKL acting via its receptor, receptor activator of NFkappaB (RANK), increases bone turnover and promotes intestinal dendritic cell (DC) survival in vivo. Modulation of RANKL-RANK interactions with exogenous recombinant osteoprotegerin (Fc-OPG) reverses skeletal abnormalities and reduces colitis by decreasing colonic DC numbers. This study identifies a common causal link between bone disease and intestinal inflammation and establishes the importance of DC in mediating colonic inflammation in vivo.

Screening for asymptomatic celiac disease among patients referred for bone densitometry measurement

Celiac disease (CD) is a relatively common gastrointestinal disorder that can be asymptomatic. An increased prevalence of subclinical CD has been reported in many populations. Even among asymptomatic patients a reduction in bone mineral density (BMD) has been observed. The aim of this study was to evaluate the prevalence of silent CD in a cohort of consecutive individuals referred for bone densitometry measurement. Serum samples were taken from 454 women attending for bone densitometry (mean age: 56 +/- 11 years). Of the individuals evaluated, 89 had normal BMD and 365 had low BMD (T score < -1.0). Subjects were screened for the presence of serum IgA anti-endomysial antibodies (EMA) and IgA tissue transglutaminase (tTG) antibodies by indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA), respectively. BMD was measured by dual X-ray absorptiometry (DEXA) at the lumbar spine and femoral neck. Eight EMA tTG-positive individuals were identified in this population (1.8% or 1:57). Serologically positive women had a lower mean Z score at both the lumbar spine and femoral neck than EMA tTG-negative women. But this did not approach significance. There was no significant difference in the incidence of CD between the normal- and low-BMD groups in this dataset (P = 0.365). In conclusion, our study indicates that the prevalence of CD in our dataset is high. However, the frequency of asymptomatic CD among low-BMD individuals is similar to that among normal-BMD individuals in our population. These observations do not support the hypothesis that serological testing for CD may be a good accompaniment to DEXA scanning.

[Inflammation mediated osteopenia (IMO): therapeutic effect of D-hormone and the role of cytokines]

Inflammation-mediated osteopenia is an animal model for bone mass reduction following chronic inflammation. We found a reduction of calcitriol serum concentrations during the inflammatory process, in addition cytokines are increased. Treatment of the animals with calcitriol is able to prevent bone mass reduction and to preserve bone formation.

Bone ingrowth to implant surfaces in an inflammatory arthritis model

Many studies have shown enhanced bone apposition to implants coated with hydroxyapatite, but the optimum implant texture, especially in abnormal trabecular bone, is unclear. The purpose of this project was to evaluate the histological and mechanical properties of cylindrical implants with three different surface textures that were placed in the cancellous bone of the distal femur of the rabbit after the production of an inflammatory knee arthritis. The three implant surfaces included a beaded surface (Group A), a beaded surface coated with hydroxyapatite (Group B), and a smooth surface coated with hydroxyapatite (Group C). The right knees of 36 rabbits were injected with carrageenan twice a week for 2 weeks. Then bilateral implantations were performed, with 12 rabbits in each group receiving identical implants in the right and left knees. The rabbits were killed 6 weeks after surgery. Mechanical (push-out test) and histomorphometric analyses were performed to determine the quality and quantity of bone ingrowth. In Group A, there was virtually no direct contact (a 20-60-microm clearance) between the bone and the beaded surfaces. Direct contact between the bone and the implant surfaces was seen in Groups B and C. The thickness and number of trabeculae were smaller on the arthritic side than on the control side for all groups but were not different between groups for either the control or the arthritic side. Mechanical testing showed that the shear strength of the interface was weaker on the arthritic side in all groups. The results suggest that inflammatory arthritis induced by carrageenan may influence the quality of local bone (osteopenic changes) and hence compromise the bone apposition and mechanical stability of the interface between the implant and bone.

Pre- and post-treatment serum levels of cytokines IL-1beta, IL-6, and IL-1 receptor antagonist in celiac disease. Are they related to the associated osteopenia?

OBJECTIVE

Decreased bone mineral density is a common finding in untreated celiac disease patients. However, the precise pathophysiology of osteopenia remains incompletely understood. Pathological features of gluten sensitivity are associated with local release of proinflammatory and antiinflammatory cytokines. We investigated the serum levels of IL-1beta, IL-6, and IL-1 receptor antagonist in celiac patients and correlated them with bone density measurements.

METHODS

We assessed serum samples of 16 female patients at the time of diagnosis (on an unrestricted diet) and after a mean time of 37 months on a gluten-free diet. At the same time, bone mineral density in the lumbar spine and total skeleton was determined by DEXA.

RESULTS

Untreated patients had high serum levels of IL-1beta and IL-6 and normal IL-1-RA. Treatment produced a decrease in median IL-1beta levels (p = NS) and a significant diminution of IL-6 (p < 0.05). On the contrary, IL-1-RA increased significantly after treatment (p < 0.05). Baseline lumbar spine Z-score and IL-6 levels exhibited a significant inverse correlation (r = -0.61; p < 0.01). Patients with more severe baseline osteopenia (< -2 Z-scores) had a significantly lower IL-1-RA than those with less bone compromise (> -2 Z-scores).

CONCLUSIONS

Our data demonstrate that the inflammatory process observed in active celiac disease is associated with high serum levels of IL-1beta and IL-6 and normal levels of IL-1-RA. Treatment significantly reduces both proinflammatory cytokines and significantly increases the antiinflammatory one. We also suggest that these cytokines might have a role in the osteopenia associated with celiac disease.

T lymphocytes play a critical role in the development of cyclosporin A-induced osteopenia

The T lymphocyte suppressor, cyclosporin A, has been shown to cause high turnover osteoporosis. We postulated that cyclosporin A may exert its effects via the T cell rather than direct activity on bone. In this study we administered cyclosporin A (15 mg/kg.day by gavage) to 11 10-week-old Rowett athymic nude rats and to 12 age-matched immunocompetent Sprague-Dawley rats. Placebo was administered to control groups (n = 12 for both). After 28 days of treatment, the Sprague-Dawley rats displayed high turnover bone loss, but the nude rats were largely unaffected by the drug. Sprague-Dawley treated rats had less than half the percent trabecular area of their controls as measured at the secondary spongiosa of the proximal tibial metaphysis (P < 0.001; strain by treatment, P = 0.007). The same pattern was evident for trabecular number, separation, and thickness (strain by treatment, P = 0.034, P = 0.001, and P = 0.021, respectively). Only the Sprague-Dawley rats had an elevated percent eroded perimeter and an elevated bone area referent bone formation rate (strain by treatment, P = 0.002 and P = 0.0003, respectively). Mass, glucose, ionized calcium, PTH, osteocalcin, 1,25-dihydroxyvitamin D, and creatinine all responded similarly to cyclosporin A regardless of strain. T Lymphocytes thus appear to be a prerequisite for the development of cyclosporin A-induced osteopenia.

Periarticular osteopenia in adjuvant induced arthritis: role of interleukin-1 in decreased osteogenic and increased resorptive potential of bone marrow cells

OBJECTIVE

To clarify the local osteogenic and bone resorptive potential of periarticular bone in adjuvant induced arthritis (AIA).

METHODS

Formation of fibroblast colony forming units (FCFU; osteogenic precursor cells) and osteoclast-like cells in bone marrow culture was studied in AIA rats. Osteoclast-inducing activity in the AIA rat bone marrow was assayed by the addition of the marrow supernatant from rats with AIA to control cultures. Bone mineral density was determined by dual x ray absorptiometry.

RESULTS

Marrow from AIA rats and that from animals receiving recombinant human interleukin-1 (IL-1) beta for seven days grew significantly fewer FCFU than control marrow. Formation of osteoclast-like cells was increased in bone marrow cultures from rats with AIA, especially when bone marrow cells were cultured in the presence of marrow supernatant. Formation of resorption lacunae on ivory slices was increased in the marrow cultures from rats with AIA, especially from the right (adjuvant inoculated) tibia. AIA rat marrow supernatant promoted osteoclast-like cell formation in control culture, and this was significantly suppressed by an anti-IL-1 antibody. Rats with AIA showed a significant decrease in the bone mineral density of the periarticular regions of the tibia and femur.

CONCLUSION

An uncoupled state in bone resorption-formation linkage, possibly mediated through an increase of IL-1 in the bone marrow, may contribute to the development of periarticular osteopenia in inflammatory arthritis.