Cathepsin K inhibitor causes changes in crystallinity and crystal structure of newly-formed mandibular bone in rats.

Cathepsin K inhibitors are new drugs with the potential for the treatment of osteoporosis because they sustain bony remodelling better than bone resorption inhibitors such as bisphosphonates. The treatment of osteoporosis with inhibitors of bony resorption is associated with osteonecrosis of the jaw, as the deterioration in bony quality that they induce is thought to be one of its causes. The quality of bone is delineated by structural and material characteristics (which include the degree and quality of mineralisation, and depends on the content of proteoglycan and the structural integrity of the bony collagen).1,2 Animal and clinical studies have shown that cathepsin K inhibitors improve the mineral density and structural characteristics of bone, but their effect on the rest remains unknown. We therefore hypothesised that these inhibitors will affect the material characteristics of newly-formed mandibular bone. To verify our hypothesis, we used Raman microspectroscopy to examine such bone in rats that were given a cathepsin K inhibitor, and found unusual crystallinity and an increased substitution of carbonate (CO32-) in its crystal structure.

Molecular alterations of newly formed mandibular bone caused by zoledronate.

Bone quality is defined by structural and material characteristics. Most studies on the mandible have focused on the analysis of structural characteristics, with insufficient investigation of material characteristics. This study tested whether zoledronate affects the material characteristics of newly formed mandibular bone. Thirty-six female Wistar rats were assigned to three groups: sham-ovariectomized rats (SHAM, n=12), ovariectomized rats (OVX, n=12), and ovariectomized rats treated with zoledronate (ZOL, n=12). The left side of the mandibular ramus of all rats was drilled bicortically. Twenty-eight days after surgery, all surviving rats were euthanized and all mandibles were removed. Raman microspectroscopy was performed, and five spectra per specimen of newly formed mandibular bone were analysed. Compared with OVX rats, the mineral/matrix ratio in ZOL rats was significantly increased (5.43±1.88 vs. 7.86±2.05), while crystallinity (0.055±0.002 vs. 0.050±0.002), relative proteoglycan content (0.43±0.10 vs. 0.31±0.05), and collagen structural integrity (1.16±0.21 vs. 0.72±0.06) were significantly decreased. These changes in material characteristics may explain why rats that received zoledronate exhibited peculiar biological phenomena such as bisphosphonate-related osteonecrosis of the jaw.

Suppressive effects of 1,4-dihydroxy-2-naphthoic acid administration on bone resorption.

SUMMARY: The main component of the metabolic by-products of fermentation by Propionibacterium freudenreichii ET-3 is 1,4-dihydroxy-2-naphthoic acid (DHNA), which has a naphthoquinone skeleton, as in vitamin K2. This study showed that DHNA improved bone mass reduction with osteoporosis model mice caused by FK506. INTRODUCTION: Growth of the intestinal bacterium Lactobacillus bifidus is specifically facilitated by DHNA. The present study used osteoporosis model mice to investigate the effects of DHNA on bone remodeling. METHODS: FK506, an immunosuppressant, was used to prepare osteoporosis model mice. Thirty mice were divided into three groups: FK group, FK+DHNA group, and control group. In the FK group, FK506 was administered to induce bone mass reduction. In the FK-DHNA group, FK506 and DHNA were administered concurrently to observe improvements in bone mass reduction. To ascertain systemic and local effects of DHNA, we investigated systemic pathological changes in colon, kidney function and cytokine dynamics, and morphological and organic changes in bone and osteoclast dynamics as assessed by culture experiments. RESULTS: Compared to the FK group without DHNA, colon damage and kidney dysfunction were milder for FK+DHNA group, and production of inflammatory cytokines (interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNF)-alpha) was more suppressed. Furthermore, compared to the group without DHNA, histological analyses and radiography showed that bone resorption was suppressed for the DHNA group. Culture experiments using osteoclasts from murine bone marrow showed osteoclast suppression for the DHNA group compared to the group without DHNA. CONCLUSION: These results show that DHNA has some effects for improving bone mass reduction caused by FK506.

Expression of osteoclast differentiation factor and osteoclastogenesis inhibitory factor in rat osteoporosis induced by immunosuppressant FK506.

Immunosuppressant drugs are currently required by transplant recipients for the remainder of their lives, despite the many adverse effects associated with these therapies. Acute osteoporosis is one such effect, and a reproducible osteoporosis model has been established through the administration of the immunosuppressant drug FK506 in rats. The cause of this osteoporosis has been shown to be abnormal osteoclast proliferation, altering the process of bone remodeling. However, the reasons why FK506 induces osteoclast proliferation and whether this process is mediated by cytokine changes or an increase in bone resorption factors have been unclear. An investigation was therefore conducted focusing on the recent discoveries of osteoclast differentiation factor (ODF) and osteoclastogenesis inhibitory factor (OCIF). These factors led to elucidation of the osteoclast differentiation-maturation mechanism. An osteoporosis model was produced in rats utilizing intramuscular FK506 injection (1 mg/kg) for 28 consecutive days. Trabecular bone resorption was observed inferior to enchondral ossification in the FK506 group, and tartrate resistant acid phosphatase (TRAP) staining revealed a clear increase in osteoclasts at the site of enchondral ossification, relative to the control group. Real-time PCR and in situ hybridization (ISH) demonstrated minimal differences in OCIF expression between control and the treatment groups. However, Real-time PCR revealed clearly increased ODF expression in the treatment group. ODF expression was also shown to be increased in the treatment group using ISH. This was histologically consistent with a region of osteoclast proliferation inferior to enchondral ossification. The results of this study support the hypothesis that FK506-mediated osteoporosis occurs by action of the drug on osteoclasts, promoting expression of ODF messenger ribonucleic acid (mRNA) and thus prompting osteoclast differentiation and maturation.

Human alpha-and beta-defensin immunoreactivity in oral mucoepidermoid carcinomas.

The purpose of this study was to demonstrate the immunohistochemical localization and distribution of human alpha- and beta-defensins, peptides with antimicrobial activity, in oral mucoepidermoid carcinoma tissue. Tissue samples were embedded in paraffin and alpha- and beta-defensins were immunostained by the streptavidin-biotin coupled peroxidase method. Cancer cells that constituted the ducts, as well as neutrophils, were positively immunostained with the anti-alpha-defensin antibody (HNPs). On the other hand, epidermoid cells and intermediate cells were intensely stained with the anti-beta-defensin-2 (HBD-2) antibody. Mucous-secreting cells were clearly not immunostained with the anti-HBD-2 antibody. The epithelial hyperplasia region adjacent to the tumor tissues was also positively immunostained with the anti-HBD-2 antibody.

Identification of a stop codon mutation in the CBFA1 runt domain from a patient with cleidocranial dysplasia and cleft lip.

We examined a patient with cleidocranial dysplasia (CCD) and cleft lip and found a new stop codon mutation in CBFA1. This mutation was a heterozygous C-to-T transition in exon 3 of CBFA1. This nucleotide change converts a CAA codon to a TAA (stop) codon at amino acid position Gln195 in the runt domain of CBFA1.

Presence of human beta-defensin-2 in oral squamous cell carcinoma.

The purpose of this study was to demonstrate immunohistochemically the localization and distribution of human beta-defensin-2 (HBD-2), a peptide with antimicrobial activity, in oral carcinoma tissues. Tissue samples were embedded in paraffin, and HBD-2 was immunostained by the streptavidin-biotin coupled peroxidase method. Cancer cells in the cornified region of well differentiated squamous cell carcinomas were stained intensely. Stained cancer cells detected by anti-HBD-2 antibody were scattered among the cells of the non-cornified region.

Immunohistochemical staining of human alpha-defensin-1 (HNP-1), in the submandibular glands of patients with oral carcinomas.

The purpose of this study was the immunohistochemical localization and distribution of HNP-1 in the submandibular glands of patients with oral carcinomas. Tissue sections were embedded in paraffin, and HNP-1 was immunostained by the streptavidin-biotin coupled peroxidase method. Striated duct cells in the submandibular glands were stained with anti-defensin antibody. Neutrophils and capillary intimal cells were also stained. Defensins (HNPs) are peptides that occur in neutrophils and protect against bacteria and tumor cells. Human alpha-defensin-1 (HNP-1) is such a peptide, possessing both antimicrobial and cytotoxic activities. The presence of HNP-1 in striated duct cells in the submandibular glands of oral cancer patients, suggests a likely role in tumor immunity, for this peptide.

Presence of defensin in epithelial Langerhans cells adjacent to oral carcinomas and precancerous lesions.

We aimed to immunohistochemically study the localization of defensin (HNPs), a family of peptides with antimicrobial and cytotoxic activity, in oral tumor tissue. Therefore, tissue sections were embedded in paraffin, and defensin was immunostained by the streptavidin-biotin coupled peroxidase method. Langerhans cells were confirmed by indirect immunostaining with anti-S-100 protein polyclonal antibody. Melanocytes were stained with Fontana-Masson's stain. Neutrophils and intimal cells were stained by anti-defensin antibody. Langerhans cells in normal epithelium or dysplasic epithelium adjacent to squamous cell carcinoma and precancerous lesion were also stained. Defensins (HNPs) are nonspecific peptides that occur in neutrophils and protect against bacteria, fungi, and tumor cells. Since defensins are also found in epithelial Langerhans cells adjacent to tumor tissue, these peptides most likely have a role in tumor immunity.

Immunohistochemical demonstration of tenascin and fibronectin in odontogenic tumours and human fetal tooth germs.

The distribution of tenascin and fibronectin (plasma fibronectin) was studied immunohistochemically in ameloblastomas, ameloblastic fibromas and ameloblastic carcinomas, as well as in tooth germs using monoclonal antibodies. Tenascin is an extracellular matrix molecule that was shown to be enriched in the embryonic mesenchyme surrounding the budding epithelium in various organs, including the tooth. Tenascin was strongly expressed in the basement membrane zone of the ameloblastomas and in the early tooth germ and the dental lamina, but not in the dental follicle. The expression of tenascin in the ameloblastic fibroma was seen in the basement membrane of the epithelial islands throughout the stromal tissues. There were clear differences in fibronectin expression in the follicular ameloblastoma and ameloblastic carcinoma. The results suggest that tenascin and fibronectin are involved in epithelial mesenchymal interactions of the tooth germ and in odontogenic tumours.