Eosinophil chemotactic factor-L (ECF-L) enhances osteoclast formation by increasing in osteoclast precursors expression of LFA-1 and ICAM-1

Significance of cancer stroma for bone destruction in oral squamous cell carcinoma using different cancer stroma subtypes

Stromal cells in the tumor microenvironment (TME) can regulate the progression of numerous types of cancer; however, the bone invasion of oral squamous cell carcinoma (OSCC) has been poorly investigated. In the present study, the effect of verrucous SCC-associated stromal cells (VSCC-SCs), SCC-associated stromal cells (SCC-SCs) and human dermal fibroblasts on bone resorption and the activation of HSC-3 osteoclasts in vivo were examined by hematoxylin and eosin, AE1/3 (pan-cytokeratin) and tartrate-resistant acid phosphatase staining. In addition, the expression levels of matrix metalloproteinase (MMP)9, membrane-type 1 MMP (MT1-MMP), Snail, receptor activator of NF-κB ligand (RANKL) and parathyroid hormone-related peptide (PTHrP) in the bone invasion regions of HSC-3 cells were examined by immunohistochemistry. The results suggested that both SCC-SCs and VSCC-SCs promoted bone resorption, the activation of osteoclasts, and the expression levels of MMP9, MT1-MMP, Snail, RANKL and PTHrP. However, SCC-SCs had a more prominent effect compared with VSCC-SCs. Finally, microarray data were used to predict potential genes underlying the differential effects of VSCC-SCs and SCC-SCs on bone invasion in OSCC. The results revealed that IL1B, ICAM1, FOS, CXCL12, INS and NGF may underlie these differential effects. In conclusion, both VSCC-SCs and SCC-SCs may promote bone invasion in OSCC by enhancing the expression levels of RANKL in cancer and stromal cells mediated by PTHrP; however, SCC-SCs had a more prominent effect. These findings may represent a potential regulatory mechanism underlying the bone invasion of OSCC.

Cellular and molecular actors of myeloid cell fusion: podosomes and tunneling nanotubes call the tune

Different types of multinucleated giant cells (MGCs) of myeloid origin have been described; osteoclasts are the most extensively studied because of their importance in bone homeostasis. MGCs are formed by cell-to-cell fusion, and most types have been observed in pathological conditions, especially in infectious and non-infectious chronic inflammatory contexts. The precise role of the different MGCs and the mechanisms that govern their formation remain poorly understood, likely due to their heterogeneity. First, we will introduce the main populations of MGCs derived from the monocyte/macrophage lineage. We will then discuss the known molecular actors mediating the early stages of fusion, focusing on cell-surface receptors involved in the cell-to-cell adhesion steps that ultimately lead to multinucleation. Given that cell-to-cell fusion is a complex and well-coordinated process, we will also describe what is currently known about the evolution of F-actin-based structures involved in macrophage fusion, i.e., podosomes, zipper-like structures, and tunneling nanotubes (TNT). Finally, the localization and potential role of the key fusion mediators related to the formation of these F-actin structures will be discussed. This review intends to present the current status of knowledge of the molecular and cellular mechanisms supporting multinucleation of myeloid cells, highlighting the gaps still existing, and contributing to the proposition of potential disease-specific MGC markers and/or therapeutic targets.

The Role of Vitamin D in the Immune System as a Pro-survival Molecule

PURPOSE

Vitamin D is a fascinating and attractive molecule that has gained particular attention in medicine in recent years. Its immunomodulatory and anti-inflammatory potential might resemble the activity of many nature-derived molecules (eg, flavonoids), but its role in biology was selected during a long evolutionary pathway to dampen the damaging effect of cell stress response and of the immune reaction. In this sense, this molecule can be considered an ancient hormone that serves, in its primary role, as a pro-survival agent. The goal of this review was to elucidate this topic.

METHODS

The article reviews current literature on the field, focusing on issues regarding the role of vitamin D in immunity.

FINDINGS

Vitamin D participates in the survival machinery used by the cell, and in particular it plays a major role in synchronizing calcium oscillatory signaling to allow cell autophagy or apoptosis during a stress response.

IMPLICATIONS

Vitamin D should be better highlighted in its molecular action and vitamin D receptor genomics to conceive a more suited therapeutic supplementation protocol in clinics.

Soluble antigen derived from IV larva of Angiostrongylus cantonensis promotes chitinase-like protein 3 (Chil3) expression induced by interleukin-13

Angiostrongyliasis caused by Angiostrongylus cantonensis (A. cantonensis) is an emerging food-borne parasitic disease, which refers basically to eosinophilic meningitis. Chitinase-like protein 3 (Chil3), a member of chitinase-like protein family which has chemotactic activity for eosinophils, is reported to be highly upregulated in brain of mouse infected with A. cantonensis. The mechanisms of high expression of Chil3 and the association between A. cantonensis and Chil3 are rarely reported. In order to understand the mechanism of high expression of Chil3 in A. cantonensis-infected mouse, we measured the level of Chil3 in RAW 264.7 and BV2 cell lines stimulated with soluble antigen of A. cantonensis by qPCR and ELISA. To explore the role of Chil3 in inflammation caused by A. cantonensis, we extracted and cultured brain mononuclear cells (BMNCs) and detected the eosinophil chemotactic activity of Chil3 using transwell assay and flow cytometer. Furthermore, we treated the infected mice by injection with rmChil3 and then counted the number of larvae in brains of infected mice and treated mice to examine the association between the worm and Chil3. Our results showed the soluble antigen from A. cantonensis could promote the Chil3 expression in macrophage and microglial cell lines induced by interleukin-13. In conclusion, we supposed that high expression of Chil3 enhanced by soluble antigens from A. cantonensis might be the reason of serious eosinophil infiltration in mouse brain after A. cantonensis infection.

The preventive effect of biochanin a on bone loss in ovariectomized rats: involvement in regulation of growth and activity of osteoblasts and osteoclasts

Biochanin A (BCA) is a major isoflavone abundant in red clover (Trifolium pretense). The protective effect of BCA on bone loss in an ovariectomized (OVX) animal model has never been clarified. The objective of this study was to investigate the biological effects of BCA on bone loss in OVX rats in vivo and on the development of osteoblasts and osteoclasts in vitro. Ovariectomy resulted in a marked increase in body weight and a decrease in femoral bone mineral density and trabecular bone volume that was prevented by BCA or 17 β -estradiol (E2) treatment. However, an increase in uterine weight was observed in E2-treated OVX rats, but not in response to BCA treatment. Treatment with BCA increased the mRNA expression of osterix, collagen type I, alkaline phosphatase (ALP), and osteocalcin and decreased the mRNA expression of tartrate-resistant acid phosphatase (TRAP) and the receptor activator of nuclear factor- κ B ligand (RANKL)/osteoprotegerin (OPG) ratio in the femur of OVX rats. Treatment with BCA or E2 prevented the OVX-induced increase in urinary deoxypyridinoline (DPD) and serum tumor necrosis factor α (TNF- α ) and interleukin-1 β (IL-1 β ). In vitro, BCA induced preosteoblasts to differentiate into osteoblasts and increased osteoblast mineralization. BCA inhibited preosteoclasts and osteoclast proliferation and decreased osteoclast bone resorption. These findings suggest that BCA treatment can effectively prevent the OVX-induced increase in bone loss and bone turnover possibly by increasing osteoblastic activities and decreasing osteoclastic activities.

Combined effect of soy isoflavones and vitamin D3 on bone loss in ovariectomized rats

OBJECTIVE

Several studies have shown that soy isoflavones have estrogen-like activities and might constitute an alternative to hormone replacement treatment. The present study investigated the effects of soy isoflavones alone and combined with vitamin D3 on prevention of bone loss.

METHODS

Sprague-Dawley rats were sham-operated (n = 8) or ovariectomized (OVX; n = 40), and then the OVX rats were randomly assigned to five groups that were untreated or treated for 14 wk with vitamin D3, 17β-estradiol, soy isoflavone extract (SIE), or vitamin D3 plus SIE. The effects of the isoflavones and 1α,25(OH)(2)D(3) on cultured osteoblasts and osteoclasts also were investigated.

RESULTS

In OVX rats, the bone mineral density and trabecular bone volume loss were improved by 17β-estradiol, SIE, or SIE plus vitamin D3 treatment. SIE treatment was more effective than vitamin D3 or 17β-estradiol in inhibiting increases in serum tumor necrosis factor-α levels and osteoblast osteoprotegerin expression. SIE plus vitamin D3 was more effective in increasing osterix expression than each alone. Bone cell cultures showed that the isoflavones induced preosteoblasts to differentiate into osteoblasts and increased osteoblast mineralization. Isoflavones inhibited preosteoclasts and osteoclast proliferation and decreased osteoclast resorption. The combination of isoflavones plus 1α,25(OH)(2)D(3) showed additive effects on the increase in cell proliferation of cultured preosteoblasts.

CONCLUSION

Treatment with soy isoflavones might be an alternative to hormone replacement therapy in decreasing bone loss from postmenopausal estrogen deficiency. In addition, there are further effects on increasing transcription factor osterix expression and preosteoblast proliferation when these were combined with vitamin D3.

Role of intercellular adhesion molecule-2 in osteoclastogenesis

Osteoclasts, multinucleated bone-resorbing cells, are specialized cells derived from the monocyte/macrophage lineage. Therefore, it is essential for mononuclear precursors to find a fusion partner during its differentiation. Our previous study showed an important role of cell communication via Mac-1 (CD11b/CD18) during osteoclastogenesis. However, the counter receptor of Mac-1 was still unknown. Flow cytometric analysis showed that bone marrow-derived mononuclear cells, used as osteoclast precursors, expressed intercellular adhesion molecule-1 and -2. Quantitative RT-PCR analysis revealed that expression level of ICAM-2 was higher than that of ICAM-1 in bone marrow cells. The osteoclastogenesis induced by receptor activator of NF-kappaB ligand (RANKL) was inhibited by anti-ICAM-2 neutralizing antibody but not by anti-ICAM-1 neutralizing antibody. The inhibitory effect of anti-ICAM-2 antibody on osteoclastogenesis was enhanced by simultaneous treatment of anti-CD11b neutralizing antibody. Furthermore, osteoclastogenesis induced by tumor necrosis factor α (TNFα) was also inhibited by anti-ICAM-2 neutralizing antibody. The involvement of lymphocytes in osteoclastogenesis was excluded, because anti-ICAM-2 antibody inhibited osteoclastogenesis using bone marrow-derived cells from immunodeficiency mice. Immunocytochemical staining demonstrated colocalization of ICAM-2 and Mac-1 during osteoclastogenesis; however, Mac-1 immunoreactivity was lost in differentiated multinucleated osteoclast. These results suggest the important role of ICAM-2/Mac-1 binding in osteoclastogenesis induced by either RANKL or TNFα.

Sex-specific effects of estrogen and androgen on gene expression in human monocyte-derived osteoclasts

Estrogen and androgen are both critical for the maintenance of bone, but the target cells, mechanisms, and responses could be sex-specific. To compare sex-specific actions of estrogen and androgen on osteoclasts, human peripheral blood mononuclear precursor cells from adult Caucasian males (n = 3) and females (n = 3) were differentiated into osteoclasts and then treated for 24 h with 17β-estradiol (10 nM) or testosterone (10 nM). Gene expression was studied with a custom designed qPCR-based array containing 94 target genes related to bone and hormone action. In untreated osteoclasts, 4 genes showed significant gender differences. 17β-estradiol significantly affected 12 genes in osteoclasts from females and 6 genes in osteoclasts from males. Fifteen of the 18 17β-estradiol-responsive genes were different in the cells from the two sexes; 2 genes affected by 17β-estradiol in both sexes were regulated oppositely in the two sexes. Testosterone significantly affected 6 genes in osteoclasts from females and 2 genes in osteoclasts from males; all except one were different in the two sexes. 17β-estradiol and testosterone largely affected different genes, suggesting that conversion of testosterone to 17β-estradiol had a limited role in the responses. The findings indicate that although osteoclasts from both sexes respond to 17β-estradiol and testosterone, the effects of both 17β-estradiol and testosterone differ in the two sexes, highlighting the importance of considering gender in the design of therapy.

Phosphatidylserine-containing liposomes inhibit the differentiation of osteoclasts and trabecular bone loss

Liposomes containing phosphatidylserine (PS) are engulfed by phagocytes including macrophages, microglia, and dendritic cells. PS liposomes (PSLs) mimic the effects of apoptotic cells on these phagocytes to induce the secretion of anti-inflammatory molecules and to inhibit the maturation of dendritic cells. However, the effects of PSLs on osteoclasts, which are also differentiated from the common myeloid precursors, remain to be determined. This study investigated the effects of PSLs on the osteoclastogenesis. In the rat bone marrow culture system, osteoclast precursors phagocytosed PSLs to secrete TGF-beta1 and PGE(2), which in turn inhibited osteoclastogenesis through the downregulation of receptor activator for NF-kappaB ligand, receptor activator of NF-kappaB, ICAM-1, and CD44. Consistent with these in vitro observations, i.m. injection of PSLs significantly increased the plasma level of TGF-beta1 and PGE(2) and decreased the expression of receptor activator for NF-kappaB ligand, receptor activator of NF-kappaB, and ICAM-1 in the skeletal tissues of ankle joints of rats with adjuvant arthritis (AA). A quantitative analysis using microcomputed tomography revealed that PSLs as well as TGF-beta1 together with PGE(2) significantly inhibited AA-induced trabecular bone loss. These observations strongly suggest that PSLs generate TGF-beta1 and PGE(2) release, leading to inhibit osteoclastogenesis and AA-induced trabecular bone loss. Because PS is a component of the cell membrane, PSLs therefore can be a potentially effective pharmacological intervention against abnormal bone loss, such as osteoporosis without deleterious side effects.

The role of Mac-1 (CD11b/CD18) in osteoclast differentiation induced by receptor activator of nuclear factor-kappaB ligand

Multinuclear osteoclasts are derived from CD11b-positive mononuclear cells in bone marrow and in circulation. FACS sorting experiments showed impaired osteoclastogenesis in RAW264.7 cells with low CD11b expression. Neutralizing antibodies and siRNA against CD11b inhibited osteoclastogenesis induced by RANKL. Although primary cultured mouse bone marrow macrophages expressed CD11a and CD11b, osteoclastogenesis induced by M-CSF and RANKL was inhibited in the presence of anti-CD11b or anti-CD18 but not anti-CD11a antibodies. Furthermore, anti-CD11b antibodies inhibited NFATc1 expression induced by M-CSF and RANKL in BMMs. These findings suggest, at least partly, an important role of CD11b in osteoclastogenesis.

The molecular basis of macrophage fusion

Multinucleated giant cells (MGCs), characteristic of granulomatous infections as well as multinucleated osteoclasts originate from fusion of macrophages. While intracellular and viral membrane fusion have been studied in detail, much less is known about the machinery which mediates cell-to-cell fusion, in particular macrophage polykaryon formation. Several molecules have been implicated in this process which may involve the action of multiple glycoproteins mediating membrane attachment and fusion. Macrophage fusion can be induced by soluble mediators such as cytokines and growth factors, even though several other stimuli may be involved, especially for the induction of granuloma-associated giant cells. The function of MGCs during granulomatous diseases is currently unknown. However, a better understanding of the mechanistic basis of macrophage fusion may lead to a better understanding of the function of MGCs found in granulomas.