Can Bone Morphogenetic Protein 1 (BMP1) Be a Potential Biomarker of Obesity?

Background Obesity has long been a severe threat to public health as an epidemic, and studies on its pathogenesis and treatment have been ongoing. Our study aims to compare the serum levels of bone morphogenetic protein 1 (BMP1), neuregulin 4 (NRG4), and apolipoprotein A5 (ApoA5) in obese and non-obese individuals and investigate their association with obesity. Methodology Our study included a total of 111 participants, of whom 46 were obese (body mass index (BMI) ≥30 kg/m2), aged 18-65 years, and had no comorbidities, and 65 were non-obese (BMI = 18.5-29.9 kg/m2) without any additional disease. For all participants, BMP1, NRG4, and ApoA5 levels were determined and compared with clinical and biochemical parameters. Results Overall, 60.4% (n = 67) of the participants were female and 39.6% (n = 44) were male. In terms of the BMI scores, 58.6% (n = 65) had a BMI <30 kg/m2 and 41.4% (n = 46) had a BMI ≥30 kg/m2. Both, the BMI and the gender groups did not differ significantly in terms of age (p = 0.093 and p = 0.795, respectively). The weight, fat-free mass, mineral quantity, protein quantity, fluid weight, and fluid ratio values of the male participants were significantly higher than females (p = 0.011, p = 0.001, p = 0.001, p = 0.001, p = 0.001, and p = 0.001, respectively). The aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratios and the triglyceride/glucose (TG/Glu) ratios were found to be significantly higher in males than in females (p = 0.001 and p = 0.001, respectively). The respective BMP1 (15.88 vs. 13.35), AST/ALT (1.36 vs. 1.04) and TG/Glu ratios (1.47 vs. 1.29) were significantly higher, while the quantitative insulin sensitivity check index (QUICKI) was lower in obese individuals than in non-obese individuals (0.32 vs. 0.34). NRG4 and ApoA5 values were similar between the two groups. BMP1, QUICKI values, and AST/ALT ratios proved to be statistically significant in obesity through the univariable logistic regression analysis (ß = 1.066, p = 0.048; ß = 0.0001, p = 0.001, and ß = 3.707, p = 0.003, respectively). On multiple logistic regression analysis, QUICKI values (ß = 0.001, p = 0.001) had a negative and significant effect on obesity, and the AST/ALT ratios (ß = 2.803, p = 0.033) had a positive and significant effect on obesity. Conclusions Our study indicates that detecting an important link between BMP1 in obese patients will help elucidate the pathogenesis of obesity and come up with a potential therapeutic candidate. BMP1 levels, along with AST/ALT and TG/Glu ratios, were significantly higher in obese patients. BMP1 levels were also an independent significant predictor of obesity together with AST/ALT ratio and QUICKI in this study, suggesting that it may exhibit a metabolic deterioration in obese individuals. However, the results cannot absolutely tell whether it supported deterioration or was a component of the repair mechanism. Althoughit is generally known from recent studies that BMP1 plays a role in osteogenesis, some encouraging results were obtained in our study indicating that BMP1 may play a role in the pathogenesis of obesity. It is expected that our results will not only promote the elucidation of the pathogenesis of obesity, but also provide a therapeutic agent.

DDIT3 switches osteogenic potential of BMP9 to lipogenic by attenuating Wnt/ß-catenin signaling via up-regulating DKK1 in mesenchymal stem cells.

Bone morphogenetic protein 9 (BMP9) functions as a potent inducer of osteogenic differentiation in mesenchymal stem cells (MSCs), holding promise for bone tissue engineering. However, BMP9 also concurrently triggers lipogenic differentiation in MSCs, potentially compromising its osteogenic potential. In this study, we explored the role of DNA damage inducible transcript 3 (DDIT3) in regulating the balance between BMP9-induced osteogenic and lipogenic differentiation in MSCs. Utilizing techniques such as PCR, Western blot, histochemical staining, and in vivo experiments, we analyzed the osteogenic and lipogenic markers induced by BMP9 and delved into the underlying molecular mechanism. We found a significant upregulation of DDIT3 in C3H10T1/2 cells treated with BMP9. This upregulation led to a reduction in BMP9-induced osteogenic markers but an enhancement in lipogenic markers. Conversely, knocking down DDIT3 produced the opposite effects. Furthermore, BMP9-induced bone formation was decreased in the presence of DDIT3, but adipocyte formation was increased. Further investigations demonstrated that BMP9 increased the phosphorylation level of GSK-3ß and promoted nuclear translocation of ß-catenin, both of which were suppressed by DDIT3. Moreover, DDIT3 decreased the total ß-catenin protein level while BMP9 increased the DKK1 protein level, which was further enhanced by DDIT3. Notably, knocking down DKK1 partially reversed the effect of DDIT3 on reducing BMP9-induced osteogenic markers and increasing lipogenic markers. Our findings indicated that DDIT3 enhances lipogenic differentiation by diminishing BMP9's osteogenic potential, possibly through inhibiting Wnt/ß-catenin signaling via DKK1 upregulation in MSCs.

The prodomain of bone morphogenetic protein 2 promotes dimerization and cleavage of BMP6 homodimers and BMP2/6 heterodimers.

Bone morphogenetic protein 2 (BMP2) and BMP6 are key regulators of systemic iron homeostasis. All BMPs are generated as inactive precursor proteins that dimerize and are cleaved to generate the bioactive ligand and inactive prodomain fragments, but nothing is known about how BMP2 or BMP6 homodimeric or heterodimeric precursor proteins are proteolytically activated. Here, we conducted in vitro cleavage assays, which revealed that BMP2 is sequentially cleaved by furin at two sites, initially at a site upstream of the mature ligand, and then at a site adjacent to the ligand domain, while BMP6 is cleaved at a single furin motif. Cleavage of both sites of BMP2 is required to generate fully active BMP2 homodimers when expressed in Xenopus embryos or liver endothelial cells, and fully active BMP2/6 heterodimers in Xenopus. We analyzed BMP activity in Xenopus embryos expressing chimeric proteins consisting of the BMP2 prodomain and BMP6 ligand domain, or vice versa. We show that the prodomain of BMP2 is necessary and sufficient to generate active BMP6 homodimers and BMP2/6 heterodimers, whereas the BMP6 prodomain cannot generate active BMP2 homodimers or BMP2/6 heterodimers. We examined BMP2 and BMP6 homodimeric and heterodimeric ligands generated from native and chimeric precursor proteins expressed in Xenopus embryos. Whereas native BMP6 is not cleaved when expressed alone, it is cleaved to generate BMP2/6 heterodimers when co-expressed with BMP2. Furthermore, BMP2-6 chimeras are cleaved to generate BMP6 homodimers. Our findings reveal an important role for the BMP2 prodomain in dimerization and proteolytic activation of BMP6.

Osteogenic effect of poly(lactic-co-glycolic acid) microcapsules with different molecular weights encapsulating bone morphogenetic protein 2.

OBJECTIVES: This study aimed to explore the effects of bone morphogenetic protein 2 (BMP-2) encapsula-ted in poly(lactic-co-glycolic acid) (PLGA) microcapsules with different molecular weights on the osteogenic ability of osteoblasts. METHODS: PLGA microcapsules with different molecular weights (12 000, 30 000) encapsulating BMP-2, were prepared using a dual-channel microinjection pump. The morphology and structure of the microcapsules were characterized by optical microscopy and scanning electron microscopy. The sustained-release performance of the microcapsules was characterized by phosphate buffered saline immersion method. The cell compatibility of the microcapsules was detected by the Calcein-AM/PI staining and CCK-8 method. The chemotactic effect of BMP-2-encapsulated microcapsules on MC3T3-E1 cells after 48 h of treatment was detected by the Transwell assay. The alkaline phosphatase activity assay and Alizarin Red S staining were used to characterize the effect of microcapsules on the osteogenic ability of MC3T3-E1 cells. RESULTS: Both types of microcapsules with different molecular weights exhibited smooth surfaces, as well as uniform and good cell compatibility. The chemotactic effect of the 12 000 microcapsules was outstanding. The 30 000 microcapsules had a longer sustained-release time, and the initial burst release was reduced by approximately 25% compared with the 12 000 microcapsules. In addition, 30 000 microcapsules performed better in long-term osteogenesis induction than 12 000 microcapsules. CONCLUSIONS: In this study, the release of BMP-2 is regulated by adjusting the molecular weight of PLGA, and the results indicate that 30 000 microcapsules can better induce the long-term osteogenic ability of MC3T3-E1 cells.

Association between TGF-ß/BMP signaling pathway polymorphisms and the risk of primary ovarian insufficiency in Korean women.

BACKGROUND: Primary ovarian insufficiency (POI) is one of the leading female infertility diseases in which ovarian function stops before the age of 40. Reports that POI is associated with transforming growth factor (TGF)-ß/bone morphogenetic protein (BMP) signaling pathway-associated genes (e.g., TGF-ß, and BMP15) have been continuous since publication that the TGF-ß superfamily acts as important regulators for ovary and placenta function in humans. Mechanistically, the secretion of follicle-stimulating hormone, progesterone, and estrogen is affected by the TGF-ß superfamily in granulosa cells, which are involved in the development of theca cells, oocytes, and granulosa cells. OBJECTIVE: This study aimed to identify the association between genes related to the TGF-ß/BMP signaling pathway and the risk of POI pathogenesis. METHODS: Possible associations between six gene polymorphisms and POI susceptibility were examined in 139 patients with POI and 345 control subjects. RESULTS: Allele combination of TGFBR1 rs334348 G > A and TGFBR3 rs1805110G > A exhibited association with decreased POI risk (adjusted odds ratio [AOR] = 0.165; 95% confidence interval [CI] 0.032-0.847; P = 0.031). Also, TGFBR1 rs1590 G > T and rs334348 G > A and TGFBR3 rs1805110 G > A allele combination exhibited association with decreased POI risk (OR = 0.553; 95% CI 0.374-0.816; P = 0.003). CONCLUSION: This study suggests that polymorphisms in the TGF-ß signaling pathway genes can be useful biomarkers for POI diagnosis and treatment.

Bone morphogenetic protein 4 ameliorates bleomycin-induced pulmonary fibrosis in mice by repressing NLRP3 inflammasome activation and epithelial-mesenchymal transition.

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive and deadly lung disease with limited therapeutic options. Bone morphogenetic protein 4 (BMP4), a multifunctional growth factor that belongs to the transforming growth factor-ß superfamily, is able to relieve pulmonary fibrosis in mice; nevertheless, the potential mechanism of action remains largely unknown. Growing evidence supports the notion that reiterant damage to the alveolar epithelial cells (AECs) is usually the "prime mover" for pulmonary fibrosis. Here, we examined the effect and mechanisms of BMP4 on bleomycin (BLM)-induced activation of NLR family pyrin domain containing 3 (NLRP3) inflammasome and epithelial-mesenchymal transition (EMT) in vivo and in vitro. Methods: The in vivo impact of BMP4 was investigated in a BLM mouse model. Histopathologic changes were analyzed by hematoxylin-eosin (H&E) and Masson's trichrome staining. The NLRP3 inflammasome activation was determined by quantitative real time polymerase chain reaction (qRT-PCR) and immunofluorescence staining. Biomarkers of EMT were measured by qRT-PCR, Western blot and immunofluorescence staining. The in vitro impact of BMP4 on BLM-induced NLRP3 inflammasome activation and EMT was explored in A549 AECs. We also evaluated whether BMP4 inhibited BLM-activated ERK1/2 signaling to address the possible molecular mechanisms. Results: BMP4 was significantly downregulated in the mouse lungs from BLM-induced pulmonary fibrosis. BMP4+/- mice presented with more severe lung fibrosis in response to BLM, and accelerated NLRP3 inflammasome activation and EMT process compared with that in BMP4+/+ mice. Whereas overexpression of BMP4 by injecting adeno-associated virus (AAV) 9 into mice attenuated BLM-induced fibrotic changes, NLRP3 inflammasome activation, and EMT in the mouse lungs, thus exerting protective efficacy against lung fibrosis. In vitro, BMP4 significantly reduced BLM-induced activation of NLRP3 inflammasome and EMT in human alveolar epithelial A549 cells. Mechanically, BMP4 repressed BLM-induced activation of ERK1/2 signaling in vivo and in vitro, suggesting that ERK1/2 inactivation contributes to BMP4-induced effects on BLM-induced activation of NLRP3 inflammasome and EMT. Conclusions: Our findings suggest that BMP4 can suppress NLRP3 inflammasome activation and EMT in AECs via inhibition of ERK1/2 signaling pathway, thus has a potential for the treatment of pulmonary fibrosis.

Bone morphogenetic protein 4 inhibits corneal neovascularization by blocking NETs-induced disruption to corneal epithelial barrier.

Corneal neovascularization (CoNV) is the second leading cause of visual impairment worldwide, and current drugs have certain limitations. Inflammatory response is the core pathological process of CoNV. Neutrophil extracellular traps (NETs) are generated after neutrophil activation, which promotes neovascularization. Prior studies demonstrated that bone morphogenetic protein 4 (BMP4) could significantly reduce inflammation and CoNV formation, its exact molecular mechanism remains unclear. Therefore, we stimulated human peripheral blood neutrophils with phorbol myristate acetate (PMA) or deoxyribonuclease I (DNase I) to induce or inhibit NETs formation. By using corneal sutures and subconjunctival injections of NETs or DNase I, rat CoNV models were established. Compared with the suture group, NETs formation and inflammatory cell infiltration in the corneal stroma were significantly increased, corneal edema was aggravated, and the length, area and diameter of CoNV were significantly enhanced in the NETs group. Furthermore, by curetting the corneal epithelial apical junctional complexes (AJCs), a crucial component in preserving the function of the corneal epithelial barrier, we discovered that the damage of AJCs had a significant role in inducing CoNV formation. NETs could induce CoNV formation by injuring corneal epithelial AJCs. Finally, by comparing the aforementioned indicators after the intervention of BMP4, BMP4 inhibitor Noggin and NADPH oxidase (NOX) inhibitor, we finally demonstrated that BMP4 could inhibit NETs-induced inflammation and corneal epithelial AJC injury, repair corneal epithelial barrier function and eventually inhibit CoNV formation by blocking NOX-2-dependent NETs formation.

The effects of BMP2 and the mechanisms involved in the invasion and angiogenesis of IDH1 mutant glioma cells.

PURPOSE: This study investigated the effect of an isocitrate dehydrogenase 1 (IDH1) mutation (mutIDH1) on the invasion and angiogenesis of human glioma cells. METHODS: Doxycycline was used to induce the expression of mutIDH1 in glioma cells. Transwell and wound healing assays were conducted to assess glioma cell migration and invasion. Western blotting and cell immunofluorescence were used to measure the expression levels of various proteins. The influence of bone morphogenetic protein 2 (BMP2) on invasion, angiogenesis-related factors, BMP2-related receptor expression, and changes in Smad signaling pathway-related proteins were evaluated after treatment with BMP2. Differential gene expression and reference transcription analysis were performed. RESULTS: Successful infection with recombinant lentivirus expressing mutIDH1 was demonstrated. The IDH1 mutation promoted glioma cell migration and invasion while positively regulating the expression of vascularization-related factors and BMP2-related receptors. BMP2 exhibited a positive regulatory effect on the migration, invasion, and angiogenesis of mutIDH1-glioma cells, possibly mediated by BMP2-induced alterations in Smad signaling pathway-related factors.After BMP2 treatment, the differential genes of MutIDH1-glioma cells are closely related to the regulation of cell migration and cell adhesion, especially the regulation of Smad-related proteins. KEGG analysis confirmed that it was related to BMP signaling pathway and TGF-ß signaling pathway and cell adhesion. Enrichment analysis of gene ontology and genome encyclopedia further confirmed the correlation of these pathways. CONCLUSION: Mutation of isocitrate dehydrogenase 1 promotes the migration, invasion, and angiogenesis of glioma cells, through its effects on the BMP2-driven Smad signaling pathway. In addition, BMP2 altered the transcriptional patterns of mutIDH1 glioma cells, enriching different gene loci in pathways associated with invasion, migration, and angiogenesis.

Developing a risk score to inform the use of rhBMP-2 in adult spinal deformity surgery.

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has not shown superior benefit overall in cost-effectiveness during adult spinal deformity (ASD) surgery. STUDY DESIGN/SETTING: Retrospective PURPOSE: Generate a risk score for pseudarthrosis to inform the utilization of rhBMP-2, balancing costs against quality of life and complications. METHODS: ASD patients with 3-year data were included. Quality of life gained was calculated from ODI to SF-6D and translated to quality-adjusted life years (QALYs). Cost was calculated using the PearlDiver database and CMS definitions for complications and comorbidities. Established weights were generated for predictive variables via logistic regression to yield a predictive risk score for pseudarthrosis that accounted for frailty, diabetes, depression, ASA grade, thoracolumbar kyphosis and three-column osteotomy use. Risk score categories, established via conditional inference tree (CIT)-derived thresholds were tested for cost-utility of rhBMP-2 usage, controlling for age, prior fusion, and baseline deformity and disability. RESULTS: 64% of ASD patients received rhBMP-2 (308/481). There were 17 (3.5%) patients that developed pseudarthrosis. rhBMP-2 use overall did not lower pseudarthrosis rates (OR: 0.5, [0.2-1.3]). Pseudarthrosis rates for each risk category were: No Risk (NoR) 0%; Low-Risk (LowR) 1.6%; Moderate Risk (ModR) 9.3%; High-Risk (HighR) 24.3%. Patients receiving rhBMP-2 had similar QALYs overall to those that did not (0.163 vs. 0.171, p = .65). rhBMP-2 usage had worse cost-utility in the LowR cohort (p < .001). In ModR patients, rhBMP-2 usage had equivocal cost-utility ($53,398 vs. $61,581, p = .232). In the HighR cohort, the cost-utility was reduced via rhBMP-2 usage ($98,328 vs. $211,091, p < .001). CONCLUSION: Our study shows rhBMP-2 demonstrates effective cost-utility for individuals at high risk for developing pseudarthrosis. The generated score can aid spine surgeons in the assessment of risk and enhance justification for the strategic use of rhBMP-2 in the appropriate clinical contexts. LEVEL OF EVIDENCE: III.

A Narrative Review on Recombinant Human Bone Morphogenetic Protein 2: Where Are We Now?

Spinal fusion is a prevalent surgical intervention for degenerative spinal diseases, with increasing demand driven by ageing populations. The coexistence of multiple chronic conditions, termed multimorbidity, often complicates surgical outcomes, making advanced bone grafts crucial for successful fusions. This paper reviews the development, clinical application, and controversies surrounding the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in spinal fusion surgeries. A comprehensive narrative review was conducted, focusing on literature from January 1980 to January 2024, sourced from PubMed and Google Scholar. Studies included those examining rhBMP-2 specifically in spinal fusion contexts, excluding other bone morphogenetic proteins (BMPs) and non-spinal applications. This review presents an overarching synopsis of rhBMP-2, its development history and clinical efficacy, the emergence of side effects, and evolving patterns of clinical use. As discussed in this review, clinical practice has adjusted usage and dosages to mitigate adverse effects, yet the need for safer delivery mechanisms persists. rhBMP-2 remains a potent osteoinductive agent with comparable fusion success, as measured by radiographic fusion and good clinical outcomes, to autologous grafts but poses unique risks. This review sets out how further research is essential to optimise the delivery of rhBMP-2 to reduce side effects. Enhanced understanding and innovation of spatio-temporal presentation relative to endogenous BMP could significantly improve patient outcomes in spinal fusion surgeries. The review contributes to the growing body of literature on the use of rhBMP-2 in spine surgery and discusses changing patterns of clinical use over time.

BMP10 accelerated spinal astrocytic activation in neuropathic pain via ALK2/smad1/5/8 signaling.

Background: Astrocytic activation in the spinal dorsal horn contributes to the central sensitization of neuropathic pain. Bone morphogenetic protein (BMP) 10, one of the BMPs highly expressed in the central nervous system, has been demonstrated to have an accelerated effect on astrocytic activation. This study aimed to investigate the functional effects of BMP10 on the activation of astrocytes in the spinal dorsal horn of animal model of neuropathic pain and to explore potential mechanisms involved in this process. Methods: A neuropathic pain mice model was established using the spared nerve injury (SNI). Western blot analysis was performed to detect the expressional levels of BMP10, activin receptor-like receptor 2 (ALK2), Smad1/5/8, phosphorylated Smad1/5/8, and glial fibrillary acidic protein (GFAP). Immunofluorescence staining was used to detect BMP10, ALK2, and GFAP distribution and expression. The behavioral changes in mice were evaluated using paw withdrawal threshold (PWT), thermal withdrawal latency (TWL), and open field test (OFT). The BMP10 siRNA, Smad1 siRNA, BMP10 peptide, and ALK2-IN-2 (ALK2 inhibitor) were intrathecally administrated to mice. A model of lipopolysaccharide (LPS)-stimulated astrocytes was established to investigate the effect of Smad1. The transfection efficiency of siRNAs was detected by western blot and qRT-PCR analysis. Results: BMP10 levels were increased in the L4-6 ipsilateral spinal dorsal horn of SNI mice and particularly elevated in astrocytes. Consistently, GFAP and phosphorylated Smad1/5/8 were upregulated in the L4-6 ipsilateral spinal dorsal horn after SNI, indicating the activation of astrocytes and Smad1/5/8 signaling. An intrathecal injection of BMP10 siRNA abrogated pain hypersensitivity and astrocytic activation in SNI mice. In addition, intrathecal administration of BMP10 peptide evoked pain hypersensitivity and astrocytic activation in normal mice, and this action was reversed by inhibiting the ALK2. Furthermore, targeting Smad1 in vitro with the help of siRNA inhibited the activation of astrocytes induced by LPS. Finally, targeting Smad1 abrogated BMP10-induced hypersensitivity and activation of astrocytes. Conclusion: These findings indicate that the BMP10/ALK2/Smad1/5/8 axis plays a key role in pain hypersensitivity after peripheral nerve injury, which indicates its stimulative ability toward astrocytes.

Biomarker-based prediction of sinus rhythm in atrial fibrillation patients: the EAST-AFNET 4 biomolecule study.

BACKGROUND AND AIMS: In patients with atrial fibrillation (AF), recurrent AF and sinus rhythm during follow-up are determined by interactions between cardiovascular disease processes and rhythm-control therapy. Predictors of attaining sinus rhythm at follow-up are not well known. METHODS: To quantify the interaction between cardiovascular disease processes and rhythm outcomes, 14 biomarkers reflecting AF-related cardiovascular disease processes in 1586 patients in the EAST-AFNET 4 biomolecule study (71 years old, 46% women) were quantified at baseline. Mixed logistic regression models including clinical features were constructed for each biomarker. Biomarkers were interrogated for interaction with early rhythm control. Outcome was sinus rhythm at 12 months. Results were validated at 24 months and in external datasets. RESULTS: Higher baseline concentrations of three biomarkers were independently associated with a lower chance of sinus rhythm at 12 months: angiopoietin 2 (ANGPT2) (odds ratio [OR] 0.76 [95% confidence interval 0.65-0.89], p=0.001), bone morphogenetic protein 10 (BMP10) (OR 0.83 [0.71-0.97], p=0.017) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) (OR 0.73 [0.60-0.88], p=0.001). Analysis of rhythm at 24 months confirmed the results. Early rhythm control interacted with the predictive potential of NT-proBNP (pinteraction=0.033). The predictive effect of NT-proBNP was reduced in patients randomized to early rhythm control (usual care: OR 0.64 [0.51-0.80], p<0.001; early rhythm control: OR 0.90 [0.69-1.18], p=0.453). External validation confirmed that low concentrations of ANGPT2, BMP10 and NT-proBNP predict sinus rhythm during follow-up. CONCLUSIONS: Low concentrations of ANGPT2, BMP10 and NT-proBNP identify patients with AF who are likely to attain sinus rhythm during follow-up. The predictive ability of NT-proBNP is attenuated in patients receiving rhythm control.

Osteoimmunological Principles Adapted to Achieve Mechanically Superior Posterolateral Fusion in a New Zealand White Rabbit Model Using Antigen-Coated, Electrospun Beta-Tricalcium Phosphate.

Introduction Triggering the immune system via antigenic stimulation at the time of spinal fusion surgery may enhance bone morphogenesis and result in successful bony arthrodesis. We sought to demonstrate that bone morphogenesis could be enhanced via antigenic immunologic stimulation of a surgical fusion site. Methods New Zealand white rabbits underwent non-instrumented posterolateral fusion of L5-6 with implantation of either an immunologically activated graft (inert beta-tricalcium phosphate) or harvested autograft. Fusion was evaluated using plain radiographs, micro-computed tomography (CT), mechanical palpation, and biomechanical testing. The final evaluation was carried out at 12 weeks postoperatively. Results Eight rabbits received immunologically activated grafts; 10 received autografts and served as historical controls. Fusion rates were identical between groups (both 50%). Radiographs and micro CT of the fusion mass showed no significant difference between groups, and both showed good incorporation of the transverse processes into the fusion masses with radiographic evidence confirming trabeculation and bone remodeling. However, mechanical testing of the fusion sites showed superior fusion strength in the rabbits that received immunologically activated grafts, approaching a factor of two on flexion/extension, lateral bending, and axial rotation. Little to no graft material was appreciable in the non-fused antigen-treated specimens. Conclusions There is a long-standing need for a graft material that can replace autograft bone, due to the negative clinical consequences and financial costs pertaining to autologous bone harvesting. No allograft bone substitute to date has been able to reliably replicate the success of harvested autograft bone. This study suggests that immunological enhancement of inert beta-tricalcium phosphate can potentially be a substitute for allograft bone that can meet and even exceed the success of harvested autograft bone.

Sinus Savvy: Exploring the Current Techniques of Maxillary Sinus Augmentation.

Sinus ridge augmentation is a surgical procedure aimed at increasing the volume of bone in the posterior maxilla to permit successful dental implant placement. The current review article presents an overview of various techniques used for sinus ridge augmentation, including the lateral window technique, crestal approach, transalveolar technique, and piezoelectric osteotomy. The article examines the advantages and limitations of each technique, such as invasiveness, surgical difficulty, and the requirement for additional procedures. Additionally, the article discusses the factors that influence the success of the procedure, including patient age, residual bone height, and the kind of bone graft substance used. The review also emphasizes the importance of proper case selection, surgical planning, and postoperative care to ensure optimal outcomes. Overall, the article provides valuable insights into the current techniques used for sinus ridge augmentation, highlighting the need for further research to improve patient outcomes and the success of placing dental implants over the long run.

Glycinamide Facilitates Nanocomplex Formation and Functions Synergistically with Bone Morphogenetic Protein 2 to Promote Osteoblast Differentiation In Vitro and Bone Regeneration in a Mouse Calvarial Defect Model.

BACKGROUND: This study aimed to identify glycine analogs conducive to the formation of cell-absorbable nanocomplexes, enhancing collagen synthesis and subsequent osteogenesis in combination with BMP2 for improved bone regeneration. METHODS: Glycine and its derivatives were assessed for their effects on osteogenic differentiation in MC3T3-E1 cells and human bone marrow mesenchymal stem cells (BMSCs) under osteogenic conditions or with BMP2. Osteogenic differentiation was assessed through alkaline phosphatase staining and real-time quantitative polymerase chain reaction (RT-qPCR). Nanocomplex formation was examined via scanning electron microscopy, circular dichroism, and ultraviolet-visible spectroscopy. In vivo osteogenic effects were validated using a mouse calvarial defect model, and bone regeneration was evaluated through micro-computed tomography and histomorphometric analysis. RESULTS: Glycine, glycine methyl ester, and glycinamide significantly enhanced collagen synthesis and ALP activity in conjunction with an osteogenic medium (OSM). GA emerged as the most effective inducer of osteoblast differentiation marker genes. Combining GA with BMP2 synergistically stimulated ALP activity and the expression of osteoblast markers in both cell lines. GA readily formed nanocomplexes, facilitating cellular uptake through strong electrostatic interactions. In an in vivo calvarial defect mouse model, the GA and BMP2 combination demonstrated enhanced bone volume, bone volume/tissue volume ratio, trabecular numbers, and mature bone formation compared to other combinations. CONCLUSION: GA and BMP2 synergistically promoted in vitro osteoblast differentiation and in vivo bone regeneration through nanocomplex formation. This combination holds therapeutic promise for individuals with bone defects, showcasing its potential for clinical intervention.

Pulmonary Hypertension Induced by Right Pulmonary Artery Occlusion: Hemodynamic Consequences of Bmpr2 Mutation.

BACKGROUND: The primary genetic risk factor for heritable pulmonary arterial hypertension is the presence of monoallelic mutations in the BMPR2 gene. The incomplete penetrance of BMPR2 mutations implies that additional triggers are necessary for pulmonary arterial hypertension occurrence. Pulmonary artery stenosis directly raises pulmonary artery pressure, and the redirection of blood flow to unobstructed arteries leads to endothelial dysfunction and vascular remodeling. We hypothesized that right pulmonary artery occlusion (RPAO) triggers pulmonary hypertension (PH) in rats with Bmpr2 mutations. METHODS AND RESULTS: Male and female rats with a 71 bp monoallelic deletion in exon 1 of Bmpr2 and their wild-type siblings underwent acute and chronic RPAO. They were subjected to full high-fidelity hemodynamic characterization. We also examined how chronic RPAO can mimic the pulmonary gene expression pattern associated with installed PH in unobstructed territories. RPAO induced precapillary PH in male and female rats, both acutely and chronically. Bmpr2 mutant and male rats manifested more severe PH compared with their counterparts. Although wild-type rats adapted to RPAO, Bmpr2 mutant rats experienced heightened mortality. RPAO induced a decline in cardiac contractility index, particularly pronounced in male Bmpr2 rats. Chronic RPAO resulted in elevated pulmonary IL-6 (interleukin-6) expression and decreased Gdf2 expression (corrected P value<0.05 and log2 fold change>1). In this context, male rats expressed higher pulmonary levels of endothelin-1 and IL-6 than females. CONCLUSIONS: Our novel 2-hit rat model presents a promising avenue to explore the adaptation of the right ventricle and pulmonary vasculature to PH, shedding light on pertinent sex- and gene-related effects.

Bone morphogenetic protein 4 alleviates pulmonary fibrosis by regulating macrophages.

Fibrosis is a pathological change mainly characterized by an increase of fibrous connective tissue and decrease of parenchymal cells. Its continuous progress may lead to the destruction of organ structure and function decline. An excess of alternatively activated M2 macrophages have been considered crucial candidates in the progression of fibrosis. Bone morphogenetic proteins (BMPs), a group of multifunctional growth factors, are essential for organ development and pathophysiological process, however, the roles that BMPs play in innate immune homeostasis in the development of fibrosis and the downstream signals have not been fully explored. In the current study, we firstly found that the expression of BMP4 was significantly down-regulated in human and mouse fibrosis samples. Then we investigated the effects of BMP4 on macrophage polarization in IL-4 environment and related molecular mechanisms, and found that BMP4 caused a decrease in polarized response towards M2, reflected in the expression of the markers Fizz1, Ym1 and Arg1, together with an inhibition in Stat6 phosphorylation. This relied on the Smad1/5/8 signaling, which had a crosstalk with Stat6. Moreover, the in vivo study showed that BMP4 treatment can reduce collagen deposition and delay the development of experimental pulmonary fibrosis in mice by inhibiting M2 macrophages through adoptive transfer experiment. These findings revealed a novel role of BMP4 in regulating macrophages, offering potential strategies for treating pulmonary fibrosis.

Loss of bmp15 function in the seasonal spawner Atlantic salmon results in ovulatory failure.

Bone morphogenetic protein 15 (BMP15) is an oocyte-specific growth factor important for successful female reproduction in mammals. While mutations in BMP15/Bmp15 cause ovulatory deficiency and/or infertility in certain mammalian species, loss of bmp15 in zebrafish, a continuous spawner and the only bmp15 knockout model in fish to date, results in complete arrest of follicle development and later female-to-male sex reversal, preventing to examine effects on ovulation/fertilization. Here, we used Atlantic salmon, a seasonal spawner, and generated bmp15 mutants to investigate ovarian development and fertility. Histological and morphometric analyses revealed that in biallelic frameshift (bmp15 fs/fs) mutant ovaries, folliculogenesis started earlier, resulting in an advanced development compared to wild-type (WT) controls, accompanied by a weaker expression of the (early) oocyte-specific factor figla. This precocious ovarian development was followed in bmp15 fs/fs females by enhanced follicle atresia during vitellogenic stages. Although genes involved in steroid synthesis and signaling (star, cyp11b, cyp17a1 and esr1) were dramatically higher in late vitellogenic bmp15 fs/fs mutant ovaries, estradiol-17ß plasma levels were lower than in WT counterparts, potentially reflecting compensatory changes at the level of ovarian gene expression. At spawning, bmp15 fs/fs females displayed lower gonado-somatic index values and reduced oocyte diameter, and the majority (71.4%), showed mature non-ovulating ovaries with a high degree of atresia. The remaining (28.6%) females spawned eggs but they either could not be fertilized or, upon fertilization, showed severe malformations and embryonic mortality. Our results show that Bmp15 is required for proper follicle recruitment and growth and later ovulatory success in Atlantic salmon, providing an alternative candidate target to induce sterility in farmed salmon. Moreover, since loss of bmp15 in salmon, in contrast to zebrafish, does not result in female-to-male sex change, this is the first mutant model in fish allowing further investigations on Bmp15-mediated functions in the ovulatory period.

Exercise Hemodynamics Predict Pulmonary Arterial Hypertension in BMPR2 Mutation Carriers.

BACKGROUND: Exercise hemodynamics are recommended for early detection of pulmonary arterial hypertension (PAH) and have been suggested to be predictive of future development of PAH in high-risk populations such as BMPR2 mutation carriers. However, the optimal exercise hemodynamic screening parameter remains to be determined. Recent data suggest that pulmonary vascular distensibility coefficient (α) may serve as a useful parameter for early detection of PAH. RESEARCH QUESTION: What is the value of exercise hemodynamics, including α, for predicting the occurrence of PAH during long-term follow-up in BMPR2 mutation carriers? STUDY DESIGN AND METHODS: Fifty-two asymptomatic BMPR2 mutation carriers who underwent symptom-limited exercise hemodynamic assessment were followed up for a median of 10 years. The impact of hemodynamics at rest and exercise, presence of exercise pulmonary hypertension, and α on occurrence of PAH during long-term follow-up were assessed. RESULTS: During long-term follow-up, five patients demonstrated PAH. Patients who demonstrated PAH showed a significantly lower α (0.8 ± 0.4%/mm Hg) than patients without PAH (1.8 ± 0.8%/mm Hg; P = .008). The only hemodynamic parameter that predicted the occurrence of PAH during long-term follow-up at regression analysis was α. Receiver operating characteristic analysis showed that α ≤ 1.5%/mm Hg predicted PAH occurrence with a specificity of 75% and sensitivity of 100%. INTERPRETATION: Before development of PAH in BMPR2 mutation carriers, α is reduced markedly and may serve as a useful parameter in the setting of early disease detection. Given the low event rate, caution is warranted in interpreting these results, highlighting the need for validation studies.