Distinguishing the proapoptotic and antiresorptive functions of risedronate in murine osteoclasts: role of the Akt pathway and the ERK/Bim axis

OBJECTIVE

Nitrogen-containing bisphosphonates are one of the most successful therapeutics for osteoporosis. The aim of this study was to elucidate the functional mechanism of one of the typical nitrogen-containing bisphosphonates, risedronate.

METHODS

Osteoclasts generated from murine bone marrow macrophages were treated with risedronate in vitro, and its effects on apoptosis and bone-resorbing activity were examined. The mechanism of action of risedronate was examined by gene induction of constitutively active Akt-1 and constitutively active MEK-1, and by gene deletion of Bim. Bim(-/-) mice, in which osteoclasts were resistant to apoptosis, were treated with risedronate and analyzed radiographically, biochemically, and histologically.

RESULTS

Risedronate induced osteoclast apoptosis through the mitochondria-dependent pathway with an increased expression of Bim, and the proapoptotic effect of risedronate was suppressed by Bim deletion and constitutively active MEK-1 introduction. In contrast, the risedronate-induced suppression of bone resorption was completely reversed by inducing constitutively active Akt-1, but not by Bim deletion or constitutively active MEK-1 introduction. These results suggested that apoptosis and bone-resorbing activity of osteoclasts were regulated through the ERK/Bim axis and the Akt pathway, respectively, both of which were suppressed by risedronate. Although osteoclast apoptosis in response to risedronate administration was suppressed in the Bim(-/-) mice, risedronate treatment increased bone mineral density in Bim(-/-) mice at a level equivalent to that in wild-type mice.

CONCLUSION

Our findings indicate that the antiresorptive effect of risedronate in vivo is mainly mediated by the suppression of the bone-resorbing activity of osteoclasts and not by the induction of osteoclast apoptosis.

Chemotherapy-related hypersensitivity reaction in Japanese patients with gynecologic malignancy

PURPOSE OF INVESTIGATION

Chemotherapy-related hypersensitivity reaction seems to be problematic in the safe management of chemotherapy. In this study we investigated chemotherapy-related hypersensitivity reaction in patients with gynecologic malignancy.

METHODS

Between January 2009 and December 2010, we examined hypersensitivity reaction (> or = grade2) using the Common Terminology Criteria for Adverse Events (CTCAE) v.4.0. We analyzed the incidence, clinical features, management, and outcome.

RESULTS

We administered over 1,057 infusions (24 regimens) to 205 patients. We found a total of four hypersensitivity reactions (> or = grade 2) cases (carboplatin: 2; nedaplatin: 1; docetaxel: 1). Signs and symptoms were varied. In two cases, the same regimen was rechallenged by using anti-allergic drugs. The docetaxel case was successful. The carboplatin case was not successful.

CONCLUSION

Chemotherapy-related hypersensitivity reaction (> or = grade2) does not occur frequently. In the case of platinum, especially, carboplatin, re-administering after hypersensitivity reaction should be done carefully though platinum is a key drug in patients with gynecologic malignancies.

Epigenetic regulation of osteoclast differentiation: possible involvement of Jmjd3 in the histone demethylation of Nfatc1

Gene expression is controlled by epigenetic mechanisms such as histone acetylation and methylation, and recent studies have revealed that key developmental steps are regulated by the trimethylation of histone H3 lysine 4 (H3K4me3) and lysine 27 (H3K27me3). Using ChIP sequencing technology combined with real-time PCR, we here demonstrate that the H3K27me3 observed in the Nfatc1 gene in bone marrow-derived macrophages (BMMs) was markedly reduced in mature osteoclasts. Jumonji domain-containing 3 (Jmjd3), a H3K27 demethylase, was induced in bone marrow-derived macrophages and in the vicinity of the transcription start site (TSS) of nuclear factor-activated T cells (NFAT) c1 in response to receptor activator of nuclear factor-κB ligand (RANKL) stimulation. Gene silencing of the Jmjd3 gene by short hairpin RNA reduced demethylation of H3K27me3 at the TSS of Nfatc1 and suppressed RANKL-induced osteoclastogenesis. These results suggest that the demethylation of H3K27me3 in the Nfatc1 gene locus by Jmjd3 plays a critical role in RANKL-induced osteoclast differentiation.

Immunohistochemical aspects of anti-microbial properties in goat submandibular glands

Salivary glands are known as the principal source of anti-microbial substances, which are considered to be essential components of saliva. The distribution of anti-microbial substances in the submandibular glands of Japanese miniature (Shiba) goat was studied using immunohistochemical methods as performed by physical development procedures. In the goat, anti-microbial substances such as lysozyme, IgA, lactoferrin and β-defensin were demonstrated to be immunolocalized in the submandibular glands, especially in the serous demilunes and duct cells. The results obtained are discussed with regard to the specific functions of the saliva. The presence and secretion of anti-microbial substances suggest that they participate in the maintenance of oral health among the elements of saliva.

Histochemical properties of sialic acids and antimicrobial substances in canine anal glands

The functional properties of sialic acids appear to be manifold. Additionally, antimicrobial substances serve as a non-specific defense against microorganisms. In this study, therefore, the localization of sialic acids and antimicrobial substances in the anal glands of dog was studied by sialoglycoconjugate histochemistry and immunohistochemistry. The secretory epithelium, luminal secretions and excretory ducts exhibited high levels of sialoglycoconjugates that terminated in Siaα2-6Gal/GalNAc or Siaα2-3Gal1-4GlcNAc. Additionally, O-acetylated sialic acids were detectable in these glandular structures. Antimicrobial substances, such as lysozyme, immunoglobulin A (IgA), lactoferrin and the peptide group of β-defensins, were also demonstrated as products of the anal glands. The results obtained are discussed with regard to the functional significance of the anal glands. These secretory products may create a defensive barrier against microbial invasion at the anal mucosa.

Regulation of RANKL-induced osteoclastogenesis by TGF-β through molecular interaction between Smad3 and Traf6

Previous studies have shown that transforming growth factor β (TGF-β) promotes receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. However, the underlying molecular mechanisms have not been elucidated. When TGF-β signals were blocked either by a specific inhibitor of TGF-β type 1 receptor kinase activity, SB431542, or by introducing a dominant-negative mutant of TGF-β type 2 receptor, RANKL-induced osteoclastogenesis was almost completely suppressed. Blockade of Smad signaling by overexpression of Smad7 or c-Ski markedly suppressed RANKL-induced osteoclastogenesis, and retroviral induction of an activated mutant of Smad2 or Smad3 reversed the inhibitory effect of SB431542. Immunoprecipitation analysis revealed that Smad2/3 directly associates with the TRAF6-TAB1-TAK1 molecular complex, which is generated in response to RANKL stimulation and plays an essential role in osteoclast differentiation. TRAF6-TAB1-TAK1 complex formation was not observed when TGF-β signaling was blocked. Analysis using deletion mutants revealed that the MH2 domain of Smad3 is necessary for TRAF6-TAB1-TAK1 complex formation, downstream signal transduction, and osteoclast formation. In addition, gene silencing of Smad3 in osteoclast precursors markedly suppressed RANKL-induced osteoclast differentiation. In summary, TGF-β is indispensable in RANKL-induced osteoclastogenesis, and the binding of Smad3 to the TRAF6-TAB1-TAK1 complex is crucial for RANKL-induced osteoclastogenic signaling.

MAPKs, activator protein-1 and nuclear factor-κB mediate production of interleukin-1β-stimulated cytokines, prostaglandin E₂ and MMP-1 in human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Determination of the interleukin-1 (IL-1) signaling cascades that lead to the production of various inflammatory mediators and catabolic factors may clarify attractive targets for therapeutic intervention for periodontitis. We comprehensively assessed the involvement of MAPKs, activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) in IL-1β-induced production of interleukin-6 (IL-6), interleukin-8 (IL-8), prostaglandin E(2) (PGE(2) ) and MMP-1 in human periodontal ligament cells.

MATERIAL AND METHODS

Human periodontal ligament cells were pretreated with an inhibitor for each of the MAPKs or NF-κB and subsequently treated with IL-1β. Following treatment, phosphorylation of three types of MAPK (ERK, p38 MAPK and c-Jun N-terminal kinase), IκB kinase (IKK) α/β/γ and IκB-α, as well as the DNA binding activity of AP-1 and NF-κB and the production of IL-6, IL-8, PGE(2) and MMP-1, were determined by western blotting, a gel mobility shift assay and ELISA, respectively.

RESULTS

The three MAPKs, simultaneously activated by IL-1β, mediated the subsequent DNA binding of AP-1 at various magnitudes, while IKKα/β/γ, IκB-α and NF-κB were also involved in the IL-1 signaling cascade. Furthermore, IL-1β stimulated the production of IL-6, IL-8, PGE(2) and MMP-1 via activation of the three MAPKs and NF-κB, because inhibitors of these significantly suppressed the IL-1β-stimulated production of these factors.

CONCLUSION

Our results strongly suggest that MAPK, AP-1 and NF-κB mediate the IL-1β-stimulated synthesis of IL-6, IL-8, PGE(2) and MMP-1 in human periodontal ligament cells. Therefore, inhibition of activation of MAPK, AP-1 and/or NF-κB may lead to therapeutic effects on progression of periodontitis.

Recent trends in orthopedic surgery performed in Japan for rheumatoid arthritis

The aim of this report was to review the use of orthopedic surgeries performed to manage rheumatoid arthritis (RA). Our review of studies published in English indicates that there has been a decrease in RA-associated surgeries in Western countries. Improvements in medical treatment may partly explain the reduction in numbers of orthopedic joint surgeries, which also suggests a worldwide trend toward improved long-term outcomes. However, the results of our multicenter study in Japan indicate that the number of RA-associated operations has not decreased, and that the numbers of operations performed annually have been relatively stable from 1998 to 2008. Although there definitely has been a decline in the numbers of synovectomy surgeries, the numbers of operations on the upper limbs and foot arthroplasties have increased. With the trend toward milder disease because of improved medical treatment, we speculate that RA patients may want and need better function for the activities of daily living. The combination of medical treatment and surgical intervention is thought to improve outcomes in RA patients who will develop joint destruction. Additional studies, including analyses of RA databases containing long-term data on a variety of surgical interventions, are needed.

Antiapoptotic molecule Bcl-2 is essential for the anabolic activity of parathyroid hormone in bone

The antiapoptotic molecule Bcl-2 inhibits apoptosis by preventing cytochrome c release from mitochondria. Although several studies have indicated the importance of Bcl-2 in maintaining skeletal integrity, the detailed cellular and molecular mechanisms remain elusive. Since Bcl-2(-/-) mice die before six weeks of age on account of renal failure and cannot be compared to adult wild-type mice, we generated Bcl-2(-/-)Bim(+/-) mice, in which a single Bim allele was inactivated, and compared them with their Bcl-2(+/-)Bim(+/-) littermates. Bcl-2(-/-)Bim(+/-) mice grew normally, but exhibited decreased bone mass compared to Bcl-2(+/-)Bim(+/-) mice, mainly due to impaired osteoblast function. Interestingly, the anabolic effect of parathyroid hormone (PTH) was not observed in Bcl-2(-/-)Bim(+/-) mice. This data demonstrates that Bcl-2 is indispensable for the anabolic activity of PTH in bone.

Effects of intrauterine undernutrition on hypothalamic Kiss1 expression and the timing of puberty in female rats

Recent studies have suggested that intrauterine undernutrition is closely associated with the pathogenesis of diseases after birth. Perinatal undernutrition is known to disturb the development of reproductive function and delay the onset of puberty in some species. Using a rat model, we determined the effects of prenatal undernutrition on the development of the hypothalamic kisspeptin system and evaluated whether the alteration of the kisspeptin system contributes to the delayed onset of puberty induced by prenatal undernutrition. We also evaluated the effects of prenatal undernutrition on the developmental changes in serum leptin levels because leptin was a putative positive regulator of the hypothalamic kisspeptin system. We compared the timing of vaginal opening (VO) and the developmental changes in body weight, hypothalamic Kiss1 mRNA levels, and serum leptin concentrations between offspring with prenatal undernutrition (UN offspring) and normal nutrition (NN offspring). After birth, the UN offspring showed rapid growth and had caught up to body weight of the NN offspring by postnatal day 12. After postnatal day 16, the UN offspring showed significantly lower Kiss1 mRNA levels than the NN offspring, despite their significantly higher serum leptin levels (at days 20 and 28). The timing of VO in the UN offspring was delayed compared with that in the NN offspring, and chronic central injection of kisspeptin normalized the timing of VO in the UN offspring. These results suggest that decreased hypothalamic kisspeptin action contributes to the delayed onset of puberty in prenatally undernourished female rats. Increased leptin resistance in the kisspeptin system might be involved in these alterations.

Anti-apoptotic molecule Bcl-2 regulates the differentiation, activation, and survival of both osteoblasts and osteoclasts

The anti-apoptotic molecule Bcl-2 inhibits apoptosis by preventing cytochrome c release from mitochondria. Although several studies have indicated the importance of Bcl-2 in maintaining skeletal integrity, the detailed cellular and molecular mechanisms remain elusive. Bcl-2(-/-) mice are growth-retarded and exhibit increased bone volume of the primary spongiosa, mainly due to the decreased number and dysfunction of osteoclasts. Osteoblast function is also impaired in Bcl-2(-/-) mice. Ex vivo studies on osteoblasts and osteoclasts showed that Bcl-2 promoted the differentiation, activation, and survival of both cell types. Because Bcl-2(-/-) mice die before 6 weeks of age due to renal failure and cannot be compared with adult wild type mice, we generated Bcl-2(-/-)Bim(+/-) mice, in which a single Bim allele was inactivated, and compared them with their Bcl-2(+/-)Bim(+/-) littermates. Loss of a single Bim allele restored normal osteoclast function in Bcl-2(-/-) mice but did not restore the impaired function of osteoblasts, and the mice exhibited osteopenia. These data demonstrate that Bcl-2 promotes the differentiation, activity, and survival of both osteoblasts and osteoclasts. The balance between Bcl-2 and Bim regulates osteoclast apoptosis and function, whereas other pro-apoptotic members are important for osteoblasts.

The antiapoptotic protein Bcl-xL negatively regulates the bone-resorbing activity of osteoclasts in mice

The B cell lymphoma 2 (Bcl-2) family member Bcl-xL has a well-characterized antiapoptotic function in lymphoid cells. However, its functions in other cells--including osteoclasts, which are of hematopoietic origin--and other cellular processes remain unknown. Here we report an unexpected function of Bcl-xL in attenuating the bone-resorbing activity of osteoclasts in mice. To investigate the role of Bcl-xL in osteoclasts, we generated mice with osteoclast-specific conditional deletion of Bcl-x (referred to herein as Bcl-x cKO mice) by mating Bcl-xfl/fl mice with mice in which the gene encoding the Cre recombinase has been knocked into the cathepsin K locus and specifically expressed in mature osteoclasts. Although the Bcl-x cKO mice grew normally with no apparent morphological abnormalities, they developed substantial osteopenia at 1 year of age, which was caused by increased bone resorption. Bcl-x deficiency increased the bone-resorbing activity of osteoclasts despite their high susceptibility to apoptosis, whereas Bcl-xL overexpression produced the opposite effect. In addition, Bcl-x cKO osteoclasts displayed increased c-Src activity, which was linked to increased levels of vitronectin and fibronectin expression. These results suggest that Bcl-xL attenuates osteoclastic bone-resorbing activity through the decreased production of ECM proteins, such as vitronectin and fibronectin, and thus provide evidence for what we believe to be a novel cellular function of Bcl-xL.

Vascular endothelial growth factor in monochorionic twins with twin-twin transfusion syndrome

OBJECTIVE

The purpose of this study was to determine vascular endothelial growth factor (VEGF) concentrations in the donor and the recipient in monochorionic twin pregnancies with twin-twin transfusion syndrome (TTTS) and single pregnancies in order to investigate the involvement of VEGF in the pathophysiology of TTTS.

METHODS

Six twin pregnancies in 11 monochorionic twin pregnancies complicated with TTTS and 11 single control pregnancies were compared. Gestational age-matched fetal blood and placental samples were obtained at birth. Serum VEGF concentration in the umbilical vein was measured by an enzyme-linked immunoabsorbant assay. Tissue protein expression of VEGF was determined by using immunohistochemistry. Western blot analysis and scanning densitometry were used to quantify and compare the VEGF expression in the terminal villi.

RESULTS

Serum VEGF concentrations in the umbilical vein in both donors and recipients tended to be higher than those in the controls. Immunolocalization of VEGF in terminal villous placenta samples in both donors and recipients was mainly observed in the syncytiotrophoblastic layer and vascular endothelial cells with less intense staining in stromal cells. The expression of VEGF in the donor placenta increased significantly (p=0.006) compared to that in the control placenta, but the expression of VEGF in the recipients tended to be higher than in the controls.

CONCLUSION

Intrauterine circulatory imbalance may induce changes in VEGF expression and these alterations may be involved in both donor and recipient in the pathogenesis of TTTS, due to the maintenance of hemodynamic stability between the circulation of the twins.

Decreased expression of kisspeptin mediates acute immune/inflammatory stress-induced suppression of gonadotropin secretion in female rat

Kisspeptin and its corresponding receptor, the G protein-coupled receptor 54, play an important role in reproductive systems. It has been suggested that reproductive disorders in metabolically disrupted animals are caused by the alteration of hypothalamic KiSS-1 systems. Immune/inflammatory challenge is also known to disrupt reproductive function. However, the effects of immune/inflammatory challenge on KiSS-1 systems have not been investigated. In this study, we showed that lipopolysaccharide (LPS) injection decreased hypothalamic KiSS-1 mRNA expression as well as plasma LH levels in ovariectomized rats. Indomethacin completely blocked the suppressive effects of LPS on LH secretion and KiSS-1 mRNA level. Furthermore, we showed that i.v. injection of kisspeptin increased plasma LH levels in LPS-administrated rats to the same degree as in saline-injected rats. These results suggest that KiSS-1 systems are sensitive to immune/inflammatory challenge conditions and transmit these signals into the central reproductive system.

Circulating profiles of osteoprotegerin and soluble receptor activator of nuclear factor kappaB ligand in post-menopausal women

OBJECTIVE

The aim of this study was to elucidate the detail profiles of circulating osteoprotegerin (OPG) and soluble receptor activator of nuclear factor kappaB ligand (sRANKL) in post-menopausal women.

METHODS

Eighty Japanese post-menopausal women were enrolled in this cross-sectional study. Circulating OPG and free fraction of sRANKL (free sRANKL), PTH, calcium and phosphorus, age, years since menopause, body mass index, bone mineral density of the vertebral bodies (LBMD) and bone turnover markers were determined in each subject.

RESULTS

In rank order correlation analysis, serum OPG concentrations had a significant positive correlation with age (r=0.291, p=0.024) and a marginal significant negative correlation with LBMD (r=-0.247, p=0.062). However they did not have correlations with LBMD or other parameters after adjustment for age. Serum free sRANKL concentrations had a significant positive correlation with age (r=0.332, p=0.010) and a significant negative correlation with LBMD (r=-0.608, p<0.001). This correlation with LBMD persisted after adjustment for age. In a multiple regression analysis with a stepwise model, the main determinants of LBMD were age and serum free sRANKL (p=0.015 and p=0.006, respectively).

CONCLUSIONS

We found the increase in circulating OPG and sRANKL with age and a robust negative correlation between circulating free sRANKL and LBMD after adjustment for age. The increase in circulating free sRANKL may reflect directly or indirectly the conditions coexistent with bone loss in post-menopausal women.

The type 2 corticotrophin-releasing hormone receptor mediates orexin A-induced luteinising hormone suppression in ovariectomised rats

Orexins are thought to be regulatory factors of the arousal and sleep patterns. They also affect immune, feeding, autonomic and neuroendocrine systems. We have previously shown that intracerebroventricular (i.c.v.) injection of orexin decreases pulsatile luteinising hormone (LH) secretion in ovariectomised (OVX) rats. However, the details of this mechanism have not been fully examined. Intracerebroventricular injection of orexin A also stimulates corticotrophin-releasing hormone (CRH) systems, which have been implicated in the stress-induced suppression of reproductive function. In the present study, we investigated the role of CRH systems in orexin-induced LH suppression. OVX rats were implanted with i.c.v. and intravenous (i.v.) cannulae. After i.c.v. injection of orexin and/or CRH receptor antagonists, blood samples were collected through the i.v. cannula at 6-min intervals for 120 min for LH measurement. Intracerebroventricular injection of orexin A or B (3 nmol/2.5 microl) suppressed pulsatile LH secretion. Coadministration of orexin A and alpha-helical corticotrophic-releasing factor (CRF), a nonselective CRH receptor antagonist (13 nmol/2.5 microl), or astressin(2)B, a selective type2 (CRH-R2) CRH receptor antagonist (28 nmol/2.5 microl), partly restored pulsatile LH secretion. Orexin B-induced LH suppression was not restored by alpha-helical CRF. In addition, i.c.v. injection of orexin A increased CRH and urocortin II (UcnII), but not Ucn mRNA levels, in the hypothalamus. These findings suggest that CRH-R2 mediates orexin A-induced LH suppression and it is possible that CRH and UcnII in the hypothalamus are involved in this pathway.

Association of osteopontin gene haplotypes with nephrolithiasis

Osteopontin (OPN) is one of the glycosylated phosphoproteins produced in the kidney that can modulate nephrolithiasis. We had previously found a modest association between OPN gene polymorphisms and the risk for urinary stone formation. In order to determine if sequence variants within the OPN gene could be linked to the risk of nephrolithiasis; we sequenced the entire OPN gene of 45 stone forming patients and 54 control patients of Japanese ancestry. We identified 61 polymorphisms and of these evaluated four haplotype-tagging single nucleotide polymorphisms in a total of 126 kidney stone cases and 214 healthy individuals; all of Japanese ancestry. There was a significant association of two of these haplotypes located in the OPN promoter with the relative probability of nephrolithiasis; one of increased and one of reduced risk. Our findings provide potential support for significant increased and decreased associations between OPN gene haplotypes and the relative potential of stone formation in the Japanese population. We suggest that such genetic findings may help to clarify the function of OPN in nephrolithiasis.

Stiffened ultrathin Pt films confirmed by acoustic-phonon resonances

Resonances of coherent acoustic phonons were excited and detected by femtosecond light pulses for determining the normal elastic constant of ultrathin platinum films. The elastic constant increases with the decrease of the film thickness, exceeds the bulk value at the thickness near 5 nm, and significantly increases at low temperatures. It shows a correlation with the normal lattice distance. Thus, this Letter provides evidence of the stiffness enhancement in ultrathin films caused by lattice anharmonicity.