Supersulfides support bone growth by promoting chondrocyte proliferation in the growth plates.

OBJECTIVES: While chondrocytes have mitochondria, they receive little O2 from the bloodstream. Sulfur respiration, an essential energy production system in mitochondria, uses supersulfides instead of O2. Supersulfides are inorganic and organic sulfides with catenated sulfur atoms and are primarily produced by cysteinyl tRNA synthetase-2 (CARS2). Here, we investigated the role of supersulfides in chondrocyte proliferation and bone growth driven by growth plate chondrocyte proliferation. METHODS: We examined the effects of NaHS, an HS-/H2S donor, and cystine, the cellular source of cysteine, on the proliferation of mouse primary chondrocytes and growth of embryonic mouse tibia in vitro. We also examined the effect of RNA interference acting on the Cars2 gene on chondrocyte proliferation in the presence of cystine. RESULTS: NaHS (30 µmol/L) enhanced tibia longitudinal growth in vitro with expansion of the proliferating zone of their growth plates. While NaHS (30 µmol/L) also promoted chondrocyte proliferation only under normoxic conditions (20 % O2), cystine (0.5 mmol/L) promoted it under both normoxic and hypoxic (2 % O2) conditions. Cars2 gene knockdown abrogated the ability of cystine (0.5 mmol/L) to promote chondrocyte proliferation under normoxic conditions, indicating that supersulfides produced by CARS2 were responsible for the cystine-dependent promotion of bone growth. CONCLUSIONS: The presented results indicate that supersulfides play a vital role in bone growth achieved by chondrocyte proliferation in the growth plates driven by sulfur respiration.

Malignant peripheral nerve sheath tumour of the oesophagus: a case report.

BACKGROUND: Malignant peripheral nerve sheath tumour (MPNST) is a very rare disease, and its pathogenesis is unknown. There are few reports of MPNST of the oesophagus. We report a case of an MPNST that was diagnosed and resected. CASE PRESENTATION: A 30-year-old female presented with dysphagia. She had been aware of the dysphagia approximately 6 months before presentation. The chest X-ray showed shadows in the right mediastinum. Barium fluoroscopy revealed a semicircular raised lesion in the lower oesophagus. Upper gastrointestinal endoscopy revealed a type 1 oesophageal tumour centred on the posterior wall 26-35 cm from the incisors. The surface was ulcerated, and the tumour was exposed. The affected area showed no iodine uptake. The EUS showed an isoechoic mass. The CT scan showed a mass of 71 × 61 × 55 mm in the beginning of the lower oesophagus with low density mass and swelling of the right recurrent nerve lymph node to 12 mm. On FDG-PET, the tumour showed an SUVmax of 11.05, and no abnormal accumulation was found in lymph nodes or other organs. The MRI showed a hyperintense mass on the T2WI, which had prolonged contrast enhancement, and no findings of invasion into surrounding tissue were found. The patient underwent right thoracotomy and open thoracic oesophagectomy. The affected lymph node was tumour negative by rapid pathological diagnosis during the operation. Histologically, spindle cells with different-sized nuclei were mixed throughout the tissue. Some regions showed nuclear polymorphism or a storiform pattern, and locally, there were approximately 7 mitoses/10 HPFs. The margin was relatively clear, but spindle-shaped tumour cells infiltrated the surrounding interstitium and basal myoepithelium, and the patient was diagnosed with MPNST. In this case, the postoperative course was good, and 16 months after the operation, the patient is currently under observation at the outpatient stage without recurrence. CONCLUSIONS: MPNST in the oesophagus is a relatively rare disease. Diagnosis before treatment is sometimes difficult, but the prognosis is good if radical resection is possible.

[A Case of Ascending Colon Cancer Recurrence with Para-Aortic Lymph Node Metastases That Was Successfully Treated with Resection and Adjuvant Chemotherapy].

A laparoscopy-assisted right hemicolectomy and D3 lymph node dissection were performed to treat a 60-year-old woman with ascending colon cancer. Microscopically, the resected specimen was diagnosed as adenocarcinoma(tub1>tub2, pSS, pN1, M0). Adjuvant chemotherapy using UFT/UZEL was administered for 6 months. Enlarged para-aortic lymph nodes were identified by follow-up CT 2 years post operation, and a para-aortic lymph node dissection was performed. Microscopic examination revealed that the #216 b1 int lymph node contained poorly differentiated metastatic adenocarcinoma. After 36 courses of FOLFOX as adjuvant chemotherapy, the chemotherapy was discontinued because of an adverse event. She has remained well without recurrence for 5 years after the second surgery. There have been reports of survival improvements by surgical resections in patients with solitary para-aorta lymph node metastases of colorectal cancer. These observations suggest that the surgical therapy may have contributed to the improved prognosis in the present case.

8-Nitro-cGMP promotes bone growth through expansion of growth plate cartilage.

In endochondral ossification, growth of bones occurs at their growth plate cartilage. While it is known that nitric oxide (NO) synthases are required for proliferation of chondrocytes in growth plate cartilage and growth of bones, the precise mechanism by which NO facilitates these process has not been clarified yet. C-type natriuretic peptide (CNP) also positively regulate elongation of bones through expansion of the growth plate cartilage. Both NO and CNP are known to use cGMP as the second messenger. Recently, 8-nitro-cGMP was identified as a signaling molecule produced in the presence of NO in various types of cells. Here, we found that 8-nitro-cGMP is produced in proliferating chondrocytes in the growth plates, which was enhanced by CNP, in bones cultured ex vivo. In addition, 8-nitro-cGMP promoted bone growth with expansion of the proliferating zone as well as increase in the number of proliferating cells in the growth plates. 8-Nitro-cGMP also promoted the proliferation of chondrocytes in vitro. On the other hand, 8-bromo-cGMP enhanced the growth of bones with expansion of hypertrophic zone of the growth plates without affecting either the width of proliferating zone or proliferation of chondrocytes. These results indicate that 8-nitro-cGMP formed in growth plate cartilage accelerates chondrocyte proliferation and bone growth as a downstream molecule of NO.

Porphyromonas gingivalis-derived lysine gingipain enhances osteoclast differentiation induced by tumor necrosis factor-α and interleukin-1ß but suppresses that by interleukin-17A: importance of proteolytic degradation of osteoprotegerin by lysine gingipain.

Periodontitis is a chronic inflammatory disease accompanied by alveolar bone resorption by osteoclasts. Porphyromonas gingivalis, an etiological agent for periodontitis, produces cysteine proteases called gingipains, which are classified based on their cleavage site specificity (i.e. arginine (Rgps) and lysine (Kgps) gingipains). We previously reported that Kgp degraded osteoprotegerin (OPG), an osteoclastogenesis inhibitory factor secreted by osteoblasts, and enhanced osteoclastogenesis induced by various Toll-like receptor (TLR) ligands (Yasuhara, R., Miyamoto, Y., Takami, M., Imamura, T., Potempa, J., Yoshimura, K., and Kamijo, R. (2009) Lysine-specific gingipain promotes lipopolysaccharide- and active-vitamin D3-induced osteoclast differentiation by degrading osteoprotegerin. Biochem. J. 419, 159-166). Osteoclastogenesis is induced not only by TLR ligands but also by proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, and IL-17A, in inflammatory conditions, such as periodontitis. Although Kgp augmented osteoclastogenesis induced by TNF-α and IL-1ß in co-cultures of mouse osteoblasts and bone marrow cells, it suppressed that induced by IL-17A. In a comparison of proteolytic degradation of these cytokines by Kgp in a cell-free system with that of OPG, TNF-α and IL-1ß were less susceptible, whereas IL-17A and OPG were equally susceptible to degradation by Kgp. These results indicate that the enhancing effect of Kgp on cytokine-induced osteoclastogenesis is dependent on the difference in degradation efficiency between each cytokine and OPG. In addition, elucidation of the N-terminal amino acid sequences of OPG fragments revealed that Kgp primarily cleaved OPG in its death domain homologous region, which might prevent dimer formation of OPG required for inhibition of receptor activator of nuclear factor κB ligand. Collectively, our results suggest that degradation of OPG by Kgp is a crucial event in the development of osteoclastogenesis and bone loss in periodontitis.

Downregulation of carbonic anhydrase IX promotes Col10a1 expression in chondrocytes.

Carbonic anhydrase (CA) IX is a transmembrane isozyme of CAs that catalyzes reversible hydration of CO(2). While it is known that CA IX is distributed in human embryonic chondrocytes, its role in chondrocyte differentiation has not been reported. In the present study, we found that Car9 mRNA and CA IX were expressed in proliferating but not hypertrophic chondrocytes. Next, we examined the role of CA IX in the expression of marker genes of chondrocyte differentiation in vitro. Introduction of Car9 siRNA to mouse primary chondrocytes obtained from costal cartilage induced the mRNA expressions of Col10a1, the gene for type X collagen α-1 chain, and Epas1, the gene for hypoxia-responsible factor-2α (HIF-2α), both of which are known to be characteristically expressed in hypertrophic chondrocytes. On the other hand, forced expression of CA IX had no effect of the proliferation of chondrocytes or the transcription of Col10a1 and Epas1, while the transcription of Col2a1 and Acan were up-regulated. Although HIF-2α has been reported to be a potent activator of Col10a1 transcription, Epas1 siRNA did not suppress Car9 siRNA-induced increment in Col10a1 expression, indicating that down-regulation of CA IX induces the expression of Col10a1 in chondrocytes in a HIF-2α-independent manner. On the other hand, cellular cAMP content was lowered by Car9 siRNA. Furthermore, the expression of Col10a1 mRNA after Car9 silencing was augmented by an inhibitor of protein kinase A, and suppressed by an inhibitor for phosphodiesterase as well as a brominated analog of cAMP. While these results suggest a possible involvement of cAMP-dependent pathway, at least in part, in induction of Col10a1 expression by down-regulation of Car9, more detailed study is required to clarify the role of CA IX in regulation of Col10a1 expression in chondrocytes.