Osteoblast-specific down-regulation of NLRP3 inflammasome by aptamer-functionalized liposome nanoparticles improves bone quality in postmenopausal osteoporosis rats.

Rationale: NLRP3 inflammasome is critical in the development and progression of many metabolic diseases driven by chronic inflammation, but its effect on the pathology of postmenopausal osteoporosis (PMOP) remains poorly understood. Methods: We here firstly examined the levels of NLRP3 inflammasome in PMOP patients by ELISA. Then we investigated the possible mechanisms underlying the effect of NLRP3 inflammasome on PMOP by RNA sequencing of osteoblasts treated with NLRP3 siRNA and qPCR. Lastly, we accessed the effect of decreased NLRP3 levels on ovariectomized (OVX) rats. To specifically deliver NLRP3 siRNA to osteoblasts, we constructed NLRP3 siRNA wrapping osteoblast-specific aptamer (CH6)-functionalized lipid nanoparticles (termed as CH6-LNPs-siNLRP3). Results: We found that the levels of NLRP3 inflammasome were significantly increased in patients with PMOP, and were negatively correlated with estradiol levels. NLRP3 knock-down influenced signal pathways including immune system process, interferon signal pathway. Notably, of the top ten up-regulated genes in NLRP3-reduced osteoblasts, nine genes (except Mx2) were enriched in immune system process, and five genes were related to interferon signal pathway. The in vitro results showed that CH6-LNPs-siNLRP3 was relatively uniform with a dimeter of 96.64 ± 16.83 nm and zeta potential of 38.37 ± 1.86 mV. CH6-LNPs-siNLRP3 did not show obvious cytotoxicity and selectively delivered siRNA to bone tissue. Moreover, CH6-LNPs-siNLRP3 stimulated osteoblast differentiation by activating ALP and enhancing osteoblast matrix mineralization. When administrated to OVX rats, CH6-LNPs-siNLRP3 promoted bone formation and bone mass, improved bone microarchitecture and mechanical properties by decreasing the levels of NLRP3, IL-1ß and IL-18 and increasing the levels of OCN and Runx2. Conclusion: NLRP3 inflammasome may be a new biomarker for PMOP diagnosis and plays a key role in the pathology of PMOP. CH6-LNPs-siNLRP3 has potential application for the treatment of PMOP.

Astragalus polysaccharides attenuate rat aortic endothelial senescence via regulation of the SIRT-1/p53 signaling pathway.

BACKGROUND: Astragalus polysaccharides (APS) have been verified to have antioxidative and antiaging activities in the mouse liver and brain. However, the effect of APS on aortic endothelial senescence in old rats and its underlying mechanism are currently unclear. Here, we aimed to elucidate the effects of APS on rat aortic endothelial oxidative stress and senescence in vitro and in vivo and investigate the potential molecular targets. METHODS: Twenty-month-old natural aging male rats were treated with APS (200 mg/kg, 400 mg/kg, 800 mg/kg daily) for 3 months. Serum parameters were tested using corresponding assay kits. Aortic morphology was observed by staining with hematoxylin and eosin (H&E) and Verhoeff Van Gieson (VVG). Aging-related protein levels were evaluated using immunofluorescence and western blot analysis. Primary rat aortic endothelial cells (RAECs) were isolated by tissue explant method. RAEC mitochondrial function was evaluated by the mitochondrial membrane potential (MMP) measured with the fluorescent lipophilic cationic dye JC­1. Intracellular total antioxidant capacity (T-AOC) was detected by a commercial kit. Cellular senescence was assessed using senescence-associated-ß-galactosidase (SA-ß-Gal) staining. RESULTS: Treatment of APS for three months was found to lessen aortic wall thickness, renovate vascular elastic tissue, improve vascular endothelial function, and reduce oxidative stress levels in 20-month-old rats. Primary mechanism analysis showed that APS treatment enhanced Sirtuin 1 (SIRT-1) protein expression and decreased the levels of the aging marker proteins p53, p21 and p16 in rat aortic tissue. Furthermore, APS abated hydrogen peroxide (H2O2)-induced cell senescence and restored H2O2-induced impairment of the MMP and T-AOC in RAECs. Similarly, APS increased SIRT-1 and decreased p53, p21 and p16 protein levels in senescent RAECs isolated from old rats. Knockdown of SIRT-1 diminished the protective effect of APS against H2O2-induced RAEC senescence and T-AOC loss, increased the levels of the downstream proteins p53 and p21, and abolished the inhibitory effect of APS on the expression of these proteins in RAECs. CONCLUSION: APS may reduce rat aortic endothelial oxidative stress and senescence via the SIRT-1/p53 signaling pathway.

New insights into the properties, functions, and aging of skeletal stem cells.

Bone-related diseases pose a major health burden for modern society. Bone is one of the organs that rely on stem cell function to maintain tissue homeostasis. Stem cell therapy has emerged as an effective new strategy to repair and replace damaged tissue. Although research on bone marrow mesenchymal stem cells has been conducted over the last few decades, the identity and definition of the true skeletal stem cell population remains controversial. Due to technological advances, some progress has been made in the prospective separation and function research of purified skeletal stem cells. Here, we reviewed the recent progress of highly purified skeletal stem cells, their function in bone development and repair, and the impact of aging on skeletal stem cells. Various studies on animal and human models distinguished and isolated skeletal stem cells using different surface markers based on flow-cytometry-activated cell sorting. The roles of different types of skeletal stem cells in bone growth, remodeling, and repair are gradually becoming clear. Thanks to technological advances, SSCs can be specifically identified and purified for functional testing and molecular analysis. The basic features of SSCs and their roles in bone development and repair and the effects of aging on SSCs are gradually being elucidated. Future mechanistic studies can help to develop new therapeutic interventions to improve various types of skeletal diseases and enhance the regenerative potential of SSCs.

Cervical metastasis of gingival carcinoma misdiagnosed as branchiogenic carcinoma, a rare entity - report of a case and review of literature.

BACKGROUND: A cervical cystic mass is associated with a number of pathologies that present with similar symptoms. These conditions are difficult to differentiate using fine-needle aspiration (FNA), ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI). Another dilemma in the differential diagnosis of cervical cystic masses is due to the controversies associated with the existence of branchiogenic carcinoma (BC). BC is an extremely rare disease that must be differentiated from other conditions presenting with cervical cystic masses, especially cystic metastasis from occult primary lesions. CASE PRESENTATION: We present a case report of a right cervical cystic metastasis from a significantly small squamous cell carcinoma primary gingival lesion misdiagnosed as BC by histopathology. A 62-year-old female presented with a painless progressively enlarging cervical mass at the anterior edge of the sternocleidomastoid muscle in the right submandibular region. Preoperative MRI and US revealed a well-defined cystic round mass. Postoperative histological examination indicated BC. Positron emission tomography/computed tomography (PET/CT) revealed high 18F-FDG (18F 2-fluoro-2-deoxy-D-glucose) uptake in surgical regions with a SUV (standard uptake value) max 4.0 and ipsilateral nasopharynx with a SUVmax 4.4, without any distant metastasis. Pathologic results revealed nasopharyngeal lymphadenosis. Considering the low incidence of BC and the limitation of diagnosis in one institution, the patient was referred to another hospital. Physical examination detected a significantly small neoplasm (~3 mm diameter) in the right lower gingiva. Histopathological examination of the neoplasm revealed a well-differentiated squamous cell carcinoma. Surgery, including a partial mandibulectomy and modified neck dissection (neck level I-V and submental lymph nodes) were undertaken. Postoperative histopathological results revealed a well-differentiated squamous cell carcinoma of right lower gingiva and two metastatic lymph nodes in the 18 lymph nodes of level II. A month later, recurrence occurred in the right cervical level II. The patient was placed on postoperative concurrent chemo-radiotherapy and supportive care. The patient suffered from cachexia and survived for only six months after surgery. CONCLUSIONS: In cases of cervical cystic masses that appear after the age of 40, clinicians should bear in mind that occult primary lesions should be excluded and examination of the gingiva should be undertaken. PET/CT has a limited role in identifying small occult primary lesions and a comprehensive physical examination must be carefully performed.