HIF-1α facilitates osteocyte-mediated osteoclastogenesis by activating JAK2/STAT3 pathway in vitro.

Osteocytes, entrapped within the mineralized bone matrix, has been found to have numerous functions such as acting as an orchestrator of bone remodeling through regulation of both osteoclast and osteoblast activity and also functioning as an endocrine cell. Due to a specialized morphology and surrounding structure, osteocytes are more tolerant to hypoxia during osteoporosis, fracture, osteoarthritis, and orthodontic-orthognathic combination therapy. Hypoxia-inducible factor-1α (HIF-1α) is one of the master regulators of hypoxia reactions, playing an important role in bone modeling, remodeling, and homeostasis. This study aimed to investigate the pivotal functional role of HIF-1α in osteocytes initiating of bone remodeling under hypoxia. In the present study, the osteoclasts formation induced by RAW264.7 was significantly promoted in conditioned media (CM) from osteocytic MLO-Y4 exposed to hypoxia in vitro. Therefore, hypoxic MLO-Y4 cells simulated by 100 µmol/L CoCl2 or 2% O2 stably expressed HIF-1α proteins and upregulated the expression of receptor activator of nuclear factor-κB ligand (RANKL) at both the messenger RNA (mRNA) and protein level. Furthermore, with the Knockdown of HIF-1α, the expression of RANKL mRNA and protein decreased after transient transfection. In addition, the phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription (STAT3) was also correlated with HIF-1α and RANKL levels under hypoxia. Then AG490, a JAK2 inhibitor, inhibited p-JAK2, p-STAT3 and RANKL expression. It was possible that AG490 disturbed the contact of HIF-1α and RANKL by JAK2/STAT3 pathway, influencing osteoclastogenesis. Our findings suggested that HIF-1α promoted the expression of RANKL by activating JAK2/STAT3 pathway in MLO-Y4 cells, and enhanced osteocyte-mediated osteoclastic differentiation in vitro.

[Effect of zoledronic acid on mandibular socket healing process of mice at an early stage].

PURPOSE: To investigate how bisphosphonates affect early process of socket healing in mice model. METHODS: Eighteen 8-9 weeks C57BL/6 male mice were randomly divided into control and experimental group. Bisphosphonate-related osteonecrosis of the jaw（BRONJ）model was conducted by intraperitoneal injection of zoledronate（ZOL） and extraction of lower left first molar in mice. Three, five, seven day after surgery, the mice were sacrificed and paraffin-embedded slides were made. H-E staining was used to evaluate the gross condition. The distribution and amounts of osteoclasts were measured by TRAP staining. Finally, immunochemical staining was used to detect RUNX2 and CTSK level. All experiments were duplicated thrice, ImageJ was used for transformation of pictures and SPSS 20.0 software package was used for statistical analysis. RESULTS: In comparison with the control group, early process of socket healing in the experimental group was generally delayed. RUNX2,CTSK,TRAP expression level was decreased. On the whole, early bone remodeling process in ZOL injection group was suppressed. CONCLUSIONS: Zoledronic acid inhibited the migration of fibroblasts into socket, and reduced the expression of Runx2, hindering new bone formation. It also can reduce the expression of TRAP 3，5，7 days after tooth extraction and CTSK expression three days after operation, thus inhibiting the bone resorption function of osteoclasts.

Organic-inorganic calcium lignosulfonate compounds for soil acidity amelioration.

Soil acidification is a problem widely occurring worldwide, which severely threaten food security and agricultural sustainability. Calcium lignosulfonate (CaLS), a cheap and ecofriendly compound, is used for the first time to amend acid soil by utilizing its unique organic and inorganic functional moieties simultaneously. Both column leaching and incubation experiments were conducted to investigate the comparative effects of CaLS (four rates at 5, 10, 15, 20 g kg-1) and compared with conventional amendments, including gypsum (5 g kg-1), lignin (5 g kg-1), L + G (each at 5 g kg-1), and control. The soil pH, exchangeable acidity and base cations, organic carbon, and different Al fractions were determined to unravel the ameliorative performance and mechanism of the treatments. Regardless of application modes and dosages, the results demonstrated that CaLS incorporation significantly increased soil pH, exchangeable Ca2+, cation exchange capacity, and organic carbon and decreased the contents of exchangeable acidity, especially exchangeable Al3+. The ameliorative mechanism was that amendment material led to the displacement of H+ and Al3+ off soil colloids by Ca2+. These released H+ and Al3+ which complexed with lignosulfonate anions into soluble organo-Al were all quickly leached from the soil column. The CaLS addition enhanced the transformation of exchangeable Al3+ and low-to-medium organo-Al complexes into highly stable organically bound fractions and immobilized into the soil. The complexing of CaLS functional groups with Al3+ impeded Al3+ from undergoing hydrolysis to produce more H+. As an environmental-friendly material, CaLS can be a promising amendment for soil acidity and Al toxicity amelioration.

[Expression of hypoxia inducible factor-1alpha during mouse mandibular first molar eruption and its significance].

PURPOSE: To investigate the expression of hypoxia inducible factor-1alpha (HIF-1α) during the eruption of mouse lower first molar, and to explore the correlation between its expression and the activity of osteoclasts. METHODS: Mouse mandibles were dissected from mice at day 1.5 to 14.5 after birth. They were then serially sectioned and stained respectively using hemotoxylin, tartrate-resistant acid phosphatase (TRAP) staining, and immunohistochemical staining. SPSS 25.0 software package was used for data analysis. RESULTS: During the eruption of mouse lower first molar, the thickness of the crown alveolar bone gradually decreased, so did the number of osteoclasts and the expression of HIF-1α. CONCLUSIONS: During the eruption of mouse lower first molar, the less expression of HIF-1α, the fewer osteoclasts there were. HIF-1α may be involved in the eruption of mouse lower first molar by regulating the activity of osteoclasts.

Smart Nanovesicle-Mediated Immunogenic Cell Death through Tumor Microenvironment Modulation for Effective Photodynamic Immunotherapy.

Combination therapy that could better balance immune activation and suppressive signals holds great potential in cancer immunotherapy. Herein, we serendipitously found that the pH-responsive nanovesicles (pRNVs) self-assembled from block copolymer polyethylene glycol-b-cationic polypeptide can not only serve as a nanocarrier but also cause immunogenic cell death (ICD) through preapoptotic exposure of calreticulin. After coencapsulation of a photosensitizer, 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH) and an indoleamine 2,3-dioxygenase inhibitor, indoximod (IND), pRNVs/HPPH/IND at a single low dose elicited significant antitumor efficacy and abscopal effect following laser irradiation in a B16F10 melanoma tumor model. Treatment efficacy attributes to three key factors: (i) singlet oxygen generation by HPPH-mediated photodynamic therapy (PDT); (ii) increased dendritic cell (DC) recruitment and immune response provocation after ICD induced by pRNVs and PDT; and (iii) tumor microenvironment modulation by IND via enhancing P-S6K phosphorylation for CD8+ T cell development. This study exploited the nanocarrier to induce ICD for the host's immunity activation. The "all-in-one" smart nanovesicles allow the design of multifunctional materials to strengthen cancer immunotherapy efficacy.