Reciprocal suppression between TGFß signaling and TNF stimulation finetunes the macrophage inflammatory response.

Inflammation plays a crucial role in the development of various disease conditions or is closely associated with them. Inflammatory cytokines like TNF often engage in interactions with other cytokines and growth factors, including TGFß, to orchestrate inflammatory process. Basal/endogenous TGFß signaling is a universal presence, yet the precise way TNF communicates with TGFß signaling to regulate inflammation and influence inflammatory levels in macrophages has remained elusive. To address this question, this study utilized genetic approaches and a combination of molecular and cellular methods, including conditional TGFß receptor knockout mice, human cells, RNAseq, ATACseq and Cut & Run-seq. The results reveal that the TGFß signaling functions as a vital homeostatic pathway, curtailing uncontrolled inflammation in macrophages in response to TNF. Conversely, TNF employs two previously unrecognized mechanisms to suppress the TGFß signaling. These mechanisms encompass epigenetic inhibition and RBP-J-mediated inhibition of the TGFß signaling pathway by TNF. These mechanisms empower TNF to diminish the antagonistic influence exerted by the TGFß signaling pathway, ultimately enhancing TNF's capacity to induce heightened levels of inflammation. This reciprocal suppression dynamic between TNF and the TGFß signaling pathway holds unique physiopathological significance, as it serves as a crucial "braking" mechanism. The balance between TNF levels and the activity of the endogenous TGFß signaling pathway plays a pivotal role in determining the overall extent of inflammation. The potential for therapeutically augmenting the TGFß signaling pathway presents an intriguing avenue for countering the impact of TNF and, consequently, developing innovative strategies for inflammation control.

A p38 MAP kinase inhibitor suppresses osteoclastogenesis and alleviates ovariectomy-induced bone loss through the inhibition of bone turnover.

Inhibition of excessive osteoclastic activity is an efficient therapeutic strategy for many bone diseases induced by increased bone resorption, such as osteoporosis. BMS-582949, a clinical p38α inhibitor, is a promising drug in Phase II studies for treating rheumatoid arthritis. However, its function on bone resorption is largely unknown. In this study, we find that BMS-582949 represses RANKL-induced osteoclast differentiation in a dose-dependent manner. Moreover, BMS-582949 inhibits osteoclastic F-actin ring formation and osteoclast-specific gene expression. Mechanically, BMS-582949 treatment attenuates RANKL-mediated osteoclastogenesis through mitogen-activated protein kinases (MAPKs) and protein kinase B (AKT) signaling pathways without disturbing nuclear factor-κB (NF-κB) signaling. Interestingly, BMS-582949 impairs osteoclastic mitochondrial biogenesis and functions, such as oxidative phosphorylation (OXPHOS). Furthermore, BMS-582949 administration prevents bone loss in ovariectomized mouse mode by inhibiting both bone resorption and bone formation in vivo. Taken together, these findings indicate that BMS-582949 may be a potential and effective drug for the therapy of osteolytic diseases.

RBP-J regulates homeostasis and function of circulating Ly6Clo monocytes.

Notch-RBP-J signaling plays an essential role in the maintenance of myeloid homeostasis. However, its role in monocyte cell fate decisions is not fully understood. Here, we showed that conditional deletion of transcription factor RBP-J in myeloid cells resulted in marked accumulation of blood Ly6Clo monocytes that highly expressed chemokine receptor CCR2. Bone marrow transplantation and parabiosis experiments revealed a cell-intrinsic requirement of RBP-J for controlling blood Ly6CloCCR2hi monocytes. RBP-J-deficient Ly6Clo monocytes exhibited enhanced capacity competing with wildtype counterparts in blood circulation. In accordance with alterations of circulating monocytes, RBP-J deficiency led to markedly increased population of lung tissues with Ly6Clo monocytes and CD16.2+ interstitial macrophages. Furthermore, RBP-J deficiency-associated phenotypes could be genetically corrected by further deleting Ccr2 in myeloid cells. These results demonstrate that RBP-J functions as a crucial regulator of blood Ly6Clo monocytes and thus derived lung-resident myeloid populations, at least in part through regulation of CCR2.

Malat1 fine-tunes bone homeostasis by orchestrating cellular crosstalk and the ß-catenin-OPG/Jagged1 pathway.

The IncRNA Malat1 was initially believed to be dispensable for physiology due to the lack of observable phenotypes in Malat1 knockout (KO) mice. However, our study challenges this conclusion. We found that both Malat1 KO and conditional KO mice in the osteoblast lineage exhibit significant osteoporosis. Mechanistically, Malat1 acts as an intrinsic regulator in osteoblasts to promote osteogenesis. Interestingly, Malat1 does not directly affect osteoclastogenesis but inhibits osteoclastogenesis in a non-autonomous manner in vivo via integrating crosstalk between multiple cell types, including osteoblasts, osteoclasts and chondrocytes. Our findings substantiate the existence of a novel remodeling network in which Malat1 serves as a central regulator by binding to ß-catenin and functioning through the ß-catenin-OPG/Jagged1 pathway in osteoblasts and chondrocytes. In pathological conditions, Malat1 significantly promotes bone regeneration in fracture healing. Bone homeostasis and regeneration are crucial to well-being. Our discoveries establish a previous unrecognized paradigm model of Malat1 function in the skeletal system, providing novel mechanistic insights into how a lncRNA integrates cellular crosstalk and molecular networks to fine tune tissue homeostasis, remodeling and repair.

Optineurin regulates osteoblast function in an age-dependent fashion in a mouse model of Paget's disease of bone.

Paget's disease of bone (PDB) is a degenerative disorder affecting the skull and bones. Hyperactive osteoclasts (OCs) initiate bone degradation in the early stage, followed by increased bone formation by osteoblasts (OBs) in trabecular bones during the advanced stage. This OB-OC uncoupling results in bone deformations and irregular trabecular bone patterns. Current mouse models poorly replicate the advanced-stage characteristics of PDB. Optineurin (Gene: OPTN in humans, Optn in mice, protein: OPTN) has been implicated in PDB by genetic analyses. We identified PDB-like cortical lesions associated with OC hyperactivation in an Optn knockout (Optn-/-) mouse model. However, the effects of OPTN dysfunction on OBs and trabecular bone in advanced PDB remain unclear. In this study, we used the Optn-/- mouse model to investigate trabecular bone abnormalities and OB activity in PDB. Micro-computed tomography analysis revealed severe pagetic alterations in craniofacial bones and femurs of aged Optn-/- mice, resembling clinical manifestations of PDB. Altered OB activity was observed in aged Optn-/- mice, implicating compensatory OB response in trabecular bone anomalies. To elucidate the role of OC-OB interactions in PDB, we conducted in vitro experiments using OC conditioned media (CM) to examine the effects on OB osteogenic potential. We found OC CM restored compromised osteogenic induction of Optn-/- bone marrow stromal cells (BMSCs) from young mice, suggesting OCs maintain OB activity through secreted factors. Strikingly, OC CM from aged Optn-/- mice significantly enhanced osteogenic capability of Optn-/- BMSCs, providing evidence for increased OB activity in advanced stages of PDB. We further identified TGF-ß/BMP signaling pathway in mediating the effects of OC CM on OBs. Our findings provide insights into Optn's role in trabecular bone abnormalities and OB activity in PDB. This enhances understanding of PDB pathogenesis and may contribute to potential therapeutic strategies for PDB and related skeletal disorders.

Severity assessment to guide empiric antibiotic therapy for cholangitis in children after Kasai portoenterostomy: a multicenter prospective randomized control trial in China.

BACKGROUND: Cholangitis is common in patients with biliary atresia following Kasai portoenterostomy (KPE). The prompt use of empiric antibiotics is essential due to the lack of identified microorganisms. The authors aimed to validate a severity grading system to guide empiric antibiotic therapy in the management of post-KPE cholangitis. MATERIALS AND METHODS: This multicenter, prospective, randomized, open-label study recruited patients with post-KPE cholangitis and was conducted from January 2018 to December 2019. On admission, patients were categorized into mild, moderate, and severe cholangitis according to the severity grading system. Patients in the mild cholangitis group were randomized to receive cefoperazone sodium tazobactam sodium (CSTS) or meropenem (MEPM). Patients with severe cholangitis were randomized to treatment with MEPM or a combination of MEPM plus immunoglobulin (MEPM+IVIG). Patients with moderate cholangitis received MEPM. RESULTS: The primary endpoint was duration of fever (DOF). Secondary outcomes included blood culture, length of hospital stay, incidence of recurrent cholangitis, jaundice clearance rate, and native liver survival (NLS). For mild cholangitis, DOF, and length of hospital stay were similar between those treated with CSTS or MEPM (all P >0.05). In addition, no significant difference in recurrence rate, jaundice clearance rate, and NLS was observed between patients treated with CSTS and MEPM at 1-month, 3-month, and 6-month follow-up. In patients with moderate cholangitis, the DOF was 36.00 (interquartile range: 24.00-48.00) h. In severe cholangitis, compared with MEPM, MEPM+IVIG decreased DOF and improved liver function by reducing alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, and direct bilirubin at 1-month follow-up. However, recurrence rate, jaundice clearance rate, and NLS did not differ significantly between MEPM+IVIG and MEPM at 1-month, 3-month, and 6-month follow-up. CONCLUSIONS: In patients with post-KPE cholangitis, MEPM is not superior to CSTS for the treatment of mild cholangitis. However, MEPM+IVIG treatment was associated with better short-term clinical outcomes in patients with severe cholangitis.

Jagged1 Acts as an RBP-J Target and Feedback Suppresses TNF-Mediated Inflammatory Osteoclastogenesis.

TNF plays a crucial role in inflammation and bone resorption in various inflammatory diseases, including rheumatoid arthritis (RA). However, its direct ability to drive macrophages to differentiate into osteoclasts is limited. Although RBP-J is recognized as a key inhibitor of TNF-mediated osteoclastogenesis, the precise mechanisms that restrain TNF-induced differentiation of macrophages into osteoclasts are not fully elucidated. In this study, we identified that the Notch ligand Jagged1 is a previously unrecognized RBP-J target. The expression of Jagged1 is significantly induced by TNF mainly through RBP-J. The TNF-induced Jagged1 in turn functions as a feedback inhibitory regulator of TNF-mediated osteoclastogenesis. This feedback inhibition of osteoclastogenesis by Jagged1 does not exist in RANKL-induced mouse osteoclast differentiation, as RANKL does not induce Jagged1 expression. The Jagged1 level in peripheral blood monocytes/osteoclast precursors is decreased in RA compared with the nonerosive inflammatory disease systemic lupus erythematosus, suggesting a mechanism that contributes to increased osteoclast formation in RA. Moreover, recombinant Jagged1 suppresses human inflammatory osteoclastogenesis. Our findings identify Jagged1 as an RBP-J direct target that links TNF and Notch signaling pathways and restrains TNF-mediated osteoclastogenesis. Given that Jagged1 has no effect on TNF-induced expression of inflammatory genes, its use may present a new complementary therapeutic approach to mitigate inflammatory bone loss with little impact on the immune response in disease conditions.

Median mandibular flexure-the unique physiological phenomenon of the mandible and its clinical significance in implant restoration.

Mandibular flexure, characterized by unique biomechanical behaviors such as elastic bending and torsion under functional loading, has emerged as a crucial factor in oral clinical diagnosis and treatment. This paper presents a comprehensive review of the current research status on mandibular flexure, drawing insights from relevant studies retrieved from the PubMed database (www.ncbi.nlm.nih.gov/pubmed), including research conclusions, literature reviews, case reports, and authoritative reference books. This paper thoroughly explores the physiological mechanisms underlying mandibular flexure, discussing different concurrent deformation types and the essential factors influencing this process. Moreover, it explores the profound implications of mandibular flexure on clinical aspects such as bone absorption around dental implants, the precision of prosthesis fabrication, and the selection and design of superstructure materials. Based on the empirical findings, this review provides crucial clinical recommendations. Specifically, it is recommended to exert precise control over the patients mouth opening during impression-taking. Those with a high elastic modulus or bone-tissue-like properties should be prioritized when selecting superstructure materials. Moreover, this review underscores the significance of customizing framework design to accommodate individual variations in facial morphology and occlusal habits. Future research endeavors in this field have the potential to advance clinical diagnosis and treatment approaches, providing opportunities for improvement.

Bone marrow Adipoq-lineage progenitors are a major cellular source of M-CSF that dominates bone marrow macrophage development, osteoclastogenesis, and bone mass.

M-CSF is a critical growth factor for myeloid lineage cells, including monocytes, macrophages, and osteoclasts. Tissue-resident macrophages in most organs rely on local M-CSF. However, it is unclear what specific cells in the bone marrow produce M-CSF to maintain myeloid homeostasis. Here, we found that Adipoq-lineage progenitors but not mature adipocytes in bone marrow or in peripheral adipose tissue, are a major cellular source of M-CSF, with these Adipoq-lineage progenitors producing M-CSF at levels much higher than those produced by osteoblast lineage cells. The Adipoq-lineage progenitors with high CSF1 expression also exist in human bone marrow. Deficiency of M-CSF in bone marrow Adipoq-lineage progenitors drastically reduces the generation of bone marrow macrophages and osteoclasts, leading to severe osteopetrosis in mice. Furthermore, the osteoporosis in ovariectomized mice can be significantly alleviated by the absence of M-CSF in bone marrow Adipoq-lineage progenitors. Our findings identify bone marrow Adipoq-lineage progenitors as a major cellular source of M-CSF in bone marrow and reveal their crucial contribution to bone marrow macrophage development, osteoclastogenesis, bone homeostasis, and pathological bone loss.

Optineurin regulates NRF2-mediated antioxidant response in a mouse model of Paget's disease of bone.

Degenerative diseases affecting the nervous and skeletal systems affect the health of millions of elderly people. Optineurin (OPTN) has been associated with numerous neurodegenerative diseases and Paget's disease of bone (PDB), a degenerative bone disease initiated by hyperactive osteoclastogenesis. In this study, we found age-related increase in OPTN and nuclear factor E2-related factor 2 (NRF2) in vivo. At the molecular level, OPTN could directly interact with both NRF2 and its negative regulator Kelch-like ECH-associated protein 1 (KEAP1) for up-regulating antioxidant response. At the cellular level, deletion of OPTN resulted in increased intracellular reactive oxygen species and increased osteoclastogenic potential. At the tissue level, deletion of OPTN resulted in substantially increased oxidative stress derived from leukocytes that further stimulate osteoclastogenesis. Last, curcumin attenuated hyperactive osteoclastogenesis induced by OPTN deficiency in aged mice. Collectively, our findings reveal an OPTN-NRF2 axis maintaining bone homeostasis and suggest that antioxidants have therapeutic potential for PDB.

The effect of mandibular flexure on the design of implant-supported fixed restorations of different facial types under two loading conditions by three-dimensional finite element analysis.

Objective: Investigating the biomechanical effects of mandibular flexure (MF) on the design of implant-supported fixed restorations in edentulous jaws of different facial types. Methods: Three-dimensional finite element models were established to analyze mandibular displacement and stress distribution of implant-supported fixed restorations (four or six implants, different implant numbers and sites, and the design of the superstructure across the dental arch in one or two or three pieces, under the loading conditions of maximum opening or right unilateral molar occlusion) in mandibular edentulous patients of three different facial types (brachyfacial, mesofacial, and dolichofacial types). Results: The brachyfacial type presented higher mandibular flexure and stress in the overall restorative system, followed by the mesofacial and dolichofacial types. During jaw opening and occlusal movements, the one-piece framework showed the lowest bone stress values surrounding the anterior implants and gradually increased to the distal position, and the three-piece framework showed the highest stress values for peri-implant bones. Also, the split framework could greatly increase the stress on abutments and frameworks. Moreover, fixed implant prostheses with cantilevers can generate high amounts of biomechanical stress and strain on implants and surrounding bones. The bone surrounding the anterior implant increased in stress values as the most distal implants were more distally located regardless of frameworks. The zirconia framework demonstrated higher stresses than the titanium framework. Conclusion: The design of edentulous fixed implant-supported restorations can be optimized for facial types. For patients of the brachyfacial type or with high masticatory muscle strength, the non-segmented framework without a cantilever provides an optimal biomechanical environment.

Advances in the superhydrophilicity-modified titanium surfaces with antibacterial and pro-osteogenesis properties: A review.

In recent years, the rate of implant failure has been increasing. Microbial infection was the primary cause, and the main stages included bacterial adhesion, biofilm formation, and severe inhibition of implant osseointegration. Various biomaterials and their preparation methods have emerged to produce specific implants with antimicrobial or bactericidal properties to reduce implant infection caused by bacterial adhesion and effectively promote bone and implant integration. In this study, we reviewed the research progress of bone integration promotion and antibacterial action of superhydrophilic surfaces based on titanium alloys. First, the adverse reactions caused by bacterial adhesion to the implant surface, including infection and bone integration deficiency, are briefly introduced. Several commonly used antibacterial methods of titanium alloys are introduced. Secondly, we discuss the antibacterial properties of superhydrophilic surfaces based on ultraviolet photo-functionalization and plasma treatment, in contrast to the antibacterial principle of superhydrophobic surface morphology. Thirdly, the osteogenic effects of superhydrophilic surfaces are described, according to the processes of osseointegration: osteogenic immunity, angiogenesis, and osteogenic related cells. Finally, we discuss the challenges and prospects for the development of this superhydrophilic surface in clinical applications, as well as the prominent strategies and directions for future research.

Cytokine-mediated immunomodulation of osteoclastogenesis.

Cytokines are an important set of proteins regulating bone homeostasis. In inflammation induced bone resorption, cytokines, such as RANKL, TNF-α, M-CSF, are indispensable for the differentiation and activation of resorption-driving osteoclasts, the process we know as osteoclastogenesis. On the other hand, immune system produces a number of regulatory cytokines, including IL-4, IL-10 and IFNs, and limits excessive activation of osteoclastogenesis and bone loss during inflammation. These unique properties make cytokines powerful targets as rheostat to maintain bone homeostasis and for potential immunotherapies of inflammatory bone diseases. In this review, we summarize recent advances in cytokine-mediated regulation of osteoclastogenesis and provide insights of potential translational impact of bench-side research into clinical treatment of bone disease.

Mechanical properties and marginal fit of prefabricated versus customized dental implant abutments: A comparative study.

INTRODUCTION: Dental implant abutments play an important role in the health and aesthetics of soft and hard tissues around implants. PURPOSE: To compare mechanical properties and marginal fit of prefabricated and customized dental implant abutments and provide references to evaluate the relationship between abutment choice and clinical indications. METHODS: Titanium abutments were randomly divided into prefabricated and customized abutments. Static and dynamic loads were applied according to ISO14801:2016. Mechanical properties, including fracture strength, fatigue strength, rotational torque value, and torque loss rate, were measured. The biological properties of the implant abutments were assessed using an internal marginal fit. The samples were sliced, and the internal marginal fit was examined using a scanning electron microscope before and after cyclic loading. The length of the tight contact was calculated at the level of the conical connection, lower internal connection, and screw threads. Microleakage was evaluated by immersing the samples in 1% methylene blue and measuring the absorbance. RESULTS: The fracture strengths of the prefabricated abutments were greater than those of the customized abutments before and after cyclic loading. The average fatigue strengths of the prefabricated and customized abutments were 350 and 300 N, respectively. The removal torque loss of the customized abutments was significantly greater than that of the prefabricated abutments. Significant differences were found in conical connection before loading, while the screw threads showed substantial differences between the two groups after loading. Microleakage in the customized abutments was significantly higher than that in the prefabricated abutments before and after loading. CONCLUSIONS: Prefabricated abutments showed superior mechanical and biological properties compared with customized abutments in vitro, suggesting a greater risk of mechanical and biological complications occurring with the use of customized abutments. This study provides a reference for the clinical selection of implant abutments.

TGFß reprograms TNF stimulation of macrophages towards a non-canonical pathway driving inflammatory osteoclastogenesis.

It is well-established that receptor activator of NF-κB ligand (RANKL) is the inducer of physiological osteoclast differentiation. However, the specific drivers and mechanisms driving inflammatory osteoclast differentiation under pathological conditions remain obscure. This is especially true given that inflammatory cytokines such as tumor necrosis factor (TNF) demonstrate little to no ability to directly drive osteoclast differentiation. Here, we found that transforming growth factor ß (TGFß) priming enables TNF to effectively induce osteoclastogenesis, independently of the canonical RANKL pathway. Lack of TGFß signaling in macrophages suppresses inflammatory, but not basal, osteoclastogenesis and bone resorption in vivo. Mechanistically, TGFß priming reprograms the macrophage response to TNF by remodeling chromatin accessibility and histone modifications, and enables TNF to induce a previously unrecognized non-canonical osteoclastogenic program, which includes suppression of the TNF-induced IRF1-IFNß-IFN-stimulated-gene axis, IRF8 degradation and B-Myb induction. These mechanisms are active in rheumatoid arthritis, in which TGFß level is elevated and correlates with osteoclast activity. Our findings identify a TGFß/TNF-driven inflammatory osteoclastogenic program, and may lead to development of selective treatments for inflammatory osteolysis.

Evaluation the loosening of abutment screws in fluid contamination: an in vitro study.

Screw loosening is one of the most common clinical problems of dental implants. Research on the influencing factors of screw loosening is very important to prevent screw loosening. The purpose of this in vitro study was to evaluate the influence of liquid contamination on the screw loosening. According to the contamination condition, forty-five abutment screws were divided into three groups (n = 15): no contamination, artificial saliva contamination, and mouthwash contamination. The preload and friction coefficient of the abutment screws were recorded. Then, the reverse torque values (RTVs) and settlement were measured after 3.0 × 105 and 6.0 × 105 cycles. The surface wear of the screws was analyzed. Finally, the stress distribution of the abutment screws was calculated by finite element analysis (FEA). The results showed that fluid contamination reduced the friction coefficient, increased the preload, decrease the settlement, improved resistance to screw loosening, and reduced wear on the thread surface. Appropriate antimicrobial lubrication may improve the anti-loosening performance of abutment screws and prevent excessive wear on the threaded surface.

Fatigue properties of plasma nitriding for dental implant application.

STATEMENT OF PROBLEM: Fatigue failure of implant components is a common clinical problem. Plasma nitriding, an in situ surface-strengthening method, may improve fatigue properties of dental implants. PURPOSE: The purpose of this in vitro study was to evaluate the effect of plasma nitriding on the fatigue behavior of implant systems. MATERIAL AND METHODS: The preload and friction coefficient of plasma nitrided abutment screws, as well as settlement of the implant-abutment interface, were measured. Then, the reverse torque values and pullout force were evaluated after cyclic loading. Finally, the fatigue properties of the implant system were investigated with static fracture and dynamic fatigue life tests, and the morphology of the fracture on the surface of the implant system was observed. RESULTS: The plasma nitriding treatment reduced the friction coefficient; increased the preload, settlement value, reverse torque values, pullout force, and static fracture load; and prolonged fatigue life. Furthermore, abutment screws with plasma nitriding treatment showed a different fatigue fracture mode. CONCLUSIONS: Plasma nitriding improved mechanical performance and may be a suitable way to optimize the fatigue behavior of dental implants.

Factors associated with brain white matter damage in type 2 diabetes mellitus: a tract-based spatial statistics study.

BACKGROUND: The pathogenesis and related factors of central nervous system abnormality in patients with type 2 diabetes mellitus (T2DM) have always been the focus of clinical research. PURPOSE: To compare and analyze the area of white matter (WM) damage in patients with T2DM based on their level of hemoglobin A1C (HBA1c) and discuss any related factors. MATERIAL AND METHODS: Based on their levels of HBA1c, 87 patients with T2DM were divided into three groups (Group B, C, or D), of which 29 non-diabetic volunteers served as the control group (Group A). DTI data analysis was based on tract-based spatial statistics (TBSS). The obtained parameters were compared among each group and the relevant clinical factors were analyzed. RESULTS: For age, sex, mini-mental state examination (MMSE), and Montreal Cognitive Assessment (MoCA) scores, there were no statistically significant differences among groups. For fractional anisotropy (FA) and radial diffusivity (RD) of WM, there were statistically significant differences (P < 0.05, two-tailed, FWE corrected) in the local area of corpus callosum, corona radiate, superior longitudinal fasciculus, etc. Most of these were significantly correlated with body mass index (BMI), left systolic blood pressure (SBP_L), and ß2 microglobulin. CONCLUSION: Before the cognitive function was obviously impaired, abnormalities of FA and RD had been found in the corpus callosum, corona radiate, and upper fasciculus in patients with T2DM, which suggested that the damage mainly occurred in the myelin sheath of WM and may be related to systemic vascular damage.