XAF1 promotes osteoclast apoptosis by antagonizing the XIAP-caspase axis.

Background: Over-activated osteoclast (OC) is a major cause of diseases related to bone loss and bone metabolism. Both bone resorption inhibition and apoptosis induction of osteoclast are crucial in treating these diseases. X-linked inhibitor of apoptosis protein (XIAP)-associated factor 1 (XAF1) is an important interferon-stimulated and apoptotic gene. However, how XAF1 regulates bone formation and remodeling is unknown. Methods: We generate global and chimeric Xaf1 knockout mouse models and utilize these models to explore the function and mechanism of XAF1 in regulating bone formation and remodeling in vivo and in vitro. Results: We show that XAF1 depletion enhances osteoclast generation in vitro. XAF1 knockout increases osteoclast number and bone resorption, thereby exacerbating bone loss in both OVX and osteolysis models. Activation of XAF1 with BV6 (a potent XIAP inhibitor) suppresses osteoclast formation. Mechanistically, XAF1 deletion decreases osteoclast apoptosis by facilitating the interaction between XIAP and caspase-3/7. Conclusions: Our data illustrates an essential role of XAF1 in controlling osteoclastogenesis in both osteoporosis and osteolysis mouse models and highlights its underlying mechanism, indicating a potential role in clinical treatment.The translational potential of this article: The translation potential of this article is that we first indicated that osteoclast apoptosis induced by XAF1 contribute to the progression of osteoporosis and osteolysis, which provides a novel strategy in the prevention of osteoporosis and osteolysis.

G protein subunit alpha i2's pivotal role in angiogenesis.

Here we explored the potential role of Gαi2 (G protein subunit alpha i2) in endothelial cell function and angiogenesis. Methods: Genetic methodologies such as shRNA, CRISPR/Cas9, dominant negative mutation, and overexpression were utilized to modify Gαi2 expression or regulate its function. Their effects on endothelial cell functions were assessed in vitro. In vivo, the endothelial-specific Gαi2 shRNA adeno-associated virus (AAV) was utilized to silence Gαi2 expression. The impact of this suppression on retinal angiogenesis in control mice and streptozotocin (STZ)-induced diabetic retinopathy (DR) mice was analyzed. Results: Analysis of single-cell RNA sequencing data revealed Gαi2 (GNAI2) was predominantly expressed in retinal endothelial cells and expression was increased in retinal endothelial cells following oxygen-induced retinopathy (OIR) in mice. Moreover, transcriptome analysis linking Gαi2 to angiogenesis-related processes/pathways, supported by increased Gαi2 expression in experimental OIR mouse retinas, highlighted its possible role in angiogenesis. In various endothelial cell types, shRNA-induced silencing and CRISPR/Cas9-mediated knockout (KO) of Gαi2 resulted in substantial reductions in cell proliferation, migration, invasion, and capillary tube formation. Conversely, Gαi2 over-expression in endothelial cells induced pro-angiogenic activities, enhancing cell proliferation, migration, invasion, and capillary tube formation. Furthermore, our investigation revealed a crucial role of Gαi2 in NFAT (nuclear factor of activated T cells) activation, as evidenced by the down-regulation of NFAT-luciferase reporter activity and pro-angiogenesis NFAT-targeted genes (Egr3, CXCR7, and RND1) in Gαi2-silenced or -KO HUVECs, which were up-regulated in Gαi2-overexpressing endothelial cells. Expression of a dominant negative Gαi2 mutation (S48C) also down-regulated NFAT-targeted genes, slowing proliferation, migration, invasion, and capillary tube formation in HUVECs. Importantly, in vivo experiments revealed that endothelial Gαi2 knockdown inhibited retinal angiogenesis in mice, with a concomitant down-regulation of NFAT-targeted genes in mouse retinal tissue. In contrast, Gαi2 over-expression in endothelial cells enhanced retinal angiogenesis in mice. Single-cell RNA sequencing data confirmed increased levels of Gαi2 specifically in retinal endothelial cells of mice with streptozotocin (STZ)-induced diabetic retinopathy (DR). Importantly, endothelial Gαi2 silencing ameliorated retinal pathological angiogenesis in DR mice. Conclusion: Our study highlights a critical role for Gαi2 in NFAT activation, endothelial cell activation and angiogenesis, offering valuable insights into potential therapeutic strategies for modulating these processes.

Gold nanorods modified by endogenous protein with light-irradiation enhance bone repair via multiple osteogenic signal pathways.

Fracture is one of the most common clinical diseases that reduce the quality of patients' lives significantly. In this study, we prepared gold nanorods modified by endogenous proteins which collected from the autologous blood of individual mice for enhanced photothermal therapy (PTT) to treat fracture. Due to the outermost layer being endogenous proteins, we find that GNRs neither activate the immune cells in vitro nor cause any rejection immune responses after entering the body as compared with PEG modification. In addition, the internal bleeding and edema of the fracture site result in a rapid enrichment of GNRs after intravenous injection. Under near infrared (NIR) light irradiation, the mild photothermal effect of the accumulated GNRs can effectively promote healing of fracture in mice. The molecular mechanism of osteogenic capability is revealed by transcriptome sequencing and subsequent confirmatory experiments, indicating enhanced two key osteogenic signal transduction (MAPK, PI3K-Akt) and multiple key osteogenesis related factors expression following the treatment. Our strategy offers an alternative way to promote bone regeneration following a fracture.

Application of thromboelastography in comparing coagulation difference of rivaroxaban and enoxaparin for thromboprophylaxis after total hip arthroplasty.

Purpose: The purpose of this study was to compare the coagulation difference in patients with either rivaroxaban or enoxaparin as thromboprophylaxis after total hip arthroplasty (THA) regarding thromboelastography (TEG) and routine coagulation tests. Patients and methods: Two hundred and twenty-eight patients undergoing primary THA were recruited in this study. They were divided into two groups according to a computer-generated random sequence. Patients in the rivaroxaban group received 10 mg of rivaroxaban orally once daily. Patients in the enoxaparin group received 4000 AxaIU (0.4 mL) of enoxaparin subcutaneously once daily. Rivaroxaban and enoxaparin were started 6-8 h after surgery. The administration of the anticoagulant prophylaxis was lasted for a minimum of 14 days. TEG and routine coagulation tests were performed on the day before the operation and 1 day and 7 days after the operation. Results: No difference was observed in the incidence of deep vein thrombosis (DVT) or pulmonary embolism (PE) between the two groups. There was no significant difference with regard to prothrombin time (PT), activated partial thromboplastin time (PTT), international normalized ratio (INR), and thrombin time (TT) between the two groups. However, while considering TEG, R time of the rivaroxaban group was significantly higher than that of the enoxaparin group (p = 0.003), whereas the maximum amplitude (MA) (p = 0.036) value and coagulation index (CI) (p = 0.002) value were significantly lower than those of the enoxaparin group. Conclusion: With regard to TEG analysis, there was coagulation difference in patients with rivaroxaban and those with enoxaparin as thromboprophylaxis after THA. Under recommended dose of rivaroxaban and enoxaparin, patients undergoing THA were in hypercoagulability on 7days postoperative.

Does subcutaneous administration of recombinant human erythropoietin increase thrombotic events in total hip arthroplasty? A prospective thrombelastography analysis.

BACKGROUND: Anemia is one of severe complications in the perioperative period of total hip arthroplasty (THA). Erythropoietin (EPO) has been considered to improve patients' anemia state, but its efficiency and safety remains controversial. METHODS: A total of 152 patients who underwent total hip arthroplasty from January 2017 to March 2019 were randomized to 2 groups. Recombinant human erythropoietin (rHu-EPO) group was treated with rHu-EPO subcutaneous injection 10000 IU after operation and once daily in the next week, while control group was treated with none extra treatment. Routine hematologic examination and thrombelastography (TEG) performed at different time point respectively. Doppler ultrasound for bilateral lower limbs was performed 1 day before surgery and 7 days after surgery. Auxiliary examination outcomes, blood transfusions outcomes, and postoperative complications were recorded as assessment indicators. RESULTS: The difference in the relevant indexes of traditional coagulation and TEG values between two groups were not significantly. No significant difference was observed in the incidence of thromboembolism events and other complications between two groups during postoperative period. The amount of intraoperative blood loss was similar between the two groups. However, the postoperative use and dosage of allogeneic blood in the rHu-EPO group were lower than those in the control group. The hemoglobin and hematocrit level in the rHu-EPO group were higher than that in the control group after surgery. CONCLUSION: Postoperative subcutaneous injection of rHu-EPO can improve hematological anemia-related parameters, reduce the use and dosage of allogeneic blood transfusions (ABTs), and has no significant influence on the formation of thrombosis and other complications in patients undergoing total hip arthroplasty in short term.

Anatomical study based on 3D-CT image reconstruction of the hip rotation center and femoral offset in a Chinese population: preoperative implications in total hip arthroplasty.

BACKGROUND: Several anatomical studies regarding the value of hip rotation center (HRC) and femoral offset (FO) have been performed in Western populations. However, there are a few data on hip morphological values in the Chinese population based on CT scans. This study measured the values of the hip and pelvis, especially HRC and FO, in a Chinese population and compared them with the published values obtained from Western populations. PATIENTS AND METHODS: One hundred patients (50 females and 50 males) were included in the present study, and 3D-CT reconstructions of the hip and pelvis were generated. The mean age was 51.4 ± 8.9 years and mean body mass index (BMI) was 23.5 ± 2.6 kg/m2. All the morphologic measurements were compared between genders and sides, and the relationships between different parameters were analyzed. RESULTS: The mean FO values were 38.4 ± 4.7 mm and 35.6 ± 4.4 mm for the males and females, respectively. A significant negative correlation was noted between FO and neck shaft angle (NSA) in both genders (r = - 0.262, P = 0.009 for the males, r = - 0.350, P ≤ 0.001 for the females). A significant positive correlation was found between horizontal distance (HD) and diameter of the femoral head (DFH) in both genders (r = 0.734, P ≤ 0.001 for the males, r = 0.658, P ≤ 0.001 for the females). A significant positive correlation was noted between HD and pelvic width (PW) in males (r = 0.455, P ≤ 0.001). A significant positive correlation was also noted between HD and pelvic height (PH) in males (r = 0.318, P ≤ 0.001). A significant positive correlation was observed between FO and pelvic cavity height (PCH) in males (r = 0.411, P ≤ 0.001), and a significant positive correlation was observed between VD and PCH in females (r = 0.497, P ≤ 0.001). The tip of the greater trochanter was, on average, 7.0 mm higher than the femoral head center. Relationships between DFH and pelvic morphometric parameters were also observed. CONCLUSION: The present morphological data and the relationships between them can be applied to design better ethnic-specific THA prostheses and preoperative plans.