Exenatide administration time-dependently affects the hepatic circadian clock through glucagon-like peptide-1 receptors in the central nervous system.

Accumulating evidence indicates that disruption of the circadian clock contributes to the development of lifestyle-related diseases. We have previously shown that exenatide, a glucagon-like peptide-1 (GLP-1) receptor agonist, can strongly affect the molecular clocks in the peripheral tissues. This study aimed to investigate the effects of its dosing time and the central nervous system-specific GLP-1 receptor knockdown (GLP1RKD) on the hepatic clock in mice treated with exenatide. Male C57BL/6J and GLP1RKD mice were housed under a 12-h/12-h light/dark cycle, and feeding was restricted to either the light period (L-TRF) or the first 4 h in the dark period (D-TRF). In parallel, exenatide was administered 4-5 times, once daily either at the beginning of the dark (ZT 12) or light period (ZT 0), and we assessed the mRNA expression rhythms of clock genes in the liver thereafter. Exenatide administration at ZT 12 counteracted the phase shift effect of the L-TRF on the hepatic clock of wild-type mice, whereas the dosing at ZT 0 enhanced its effect. However, exenatide did not influence the phase of the hepatic clock under D-TRF regardless of the dosing time. The effect of exenatide in wild-type mice weakened in GLP1RKD mice. These results showed that exenatide dosing time-dependently affects the hepatic circadian clock through the central GLP-1 system. Exenatide administration at the beginning of the active period (i.e., in the morning for humans) might prevent disruption of the peripheral clocks caused by irregular eating habits.

Selectivity Modulation of Multistep Reduction Reactions by Gold Nanoclusters.

The selective synthesis of valuable azo- and azoxyaromatic chemicals via transfer coupling of nitroaromatic compounds has been achieved by fine-tuning the catalyst structure. Here, a direct method to modulate nitrobenzene reduction and selectively alter the product from azobenzene to azoxybenzene by employing the size effect of Au is reported. Au nanoclusters (NCs) with smaller sizes embedded in ZIF-8 controllably converted nitrobenzene into azoxybenzene, while supported Au nanoparticles (NPs) catalyzed nitrobenzene reduction to azobenzene. X-ray photoelectron spectroscopy (XPS) and Diffuse reflectance infrared Fourier transform spectroscopy on CO adsorption (CO-DRIFTS) of Au NC/ZIF-8 revealed a higher valence state and a lower electron density of Au than that of Au NP/ZIF-8, combined with the desorption of azoxybenzene from the Au NC and Au NP surface, suggesting that the Au NCs with lower electron density exhibit stronger adsorption. Density functional theory (DFT) calculations and charge density difference maps indicated that azoxybenzene bonded to Au NC/ZIF-8 with greater adsorption energy, resulting in more electron transfer between azoxybenzene and the generated Au sites, which inhibited further reduction of azoxybenzene and resulted in high azoxybenzene selectivity. The application of the size effect of Au particles to regulate nitrobenzene transfer coupling provided new insights into the structure-selectivity relationships.

Response of microbial communities and biogeochemical cycling functions to sediment physicochemical properties and microplastic pollution under damming and water diversion projects.

Understanding the interactions among flow-sediment, microorganisms, and biogeochemical cycles is crucial for comprehending the ecological response mechanisms of dams and water diversion. This study focused on the spatial patterns of carbon, nitrogen, phosphorus, and sulfur (CNPS) cycle functional genes in the water resource for the middle route of the South-to-North Water Diversion Project in China, specifically the Danjiangkou Reservoir (comprising the Han and Dan reservoirs). The investigation incorporated sediment physicochemical properties and microplastic pollution. Numerous microbial species were identified, revealing that microbial communities demonstrated sensitivity to changes in sedimentary mud content. The communities exhibited greater ß diversity due to finer sediment particles in the Han Reservoir (HR), whereas in the Dan Reservoir (DR), despite having higher sediment nutrient content and MPs pollution, did not display this pattern. Regarding the composition and structure of microbial communities, the study highlighted that sediment N and P content had a more significant influence compared to particle size and MPs. The quantitative microbial element cycling (QMEC) results confirmed the presence of extensive chemolithotrophic microbes and strong nitrogen cycle activity stemming from long-term water storage and diversion operations. The denitrification intensity in the HR surpassed that of the DR. Notably, near the pre-dam area, biological nitrogen fixation, phosphorus removal, and sulfur reduction exhibited noticeable increases. Dam construction refined sediment, fostering the growth of different biogeochemical cycling bacteria and increasing the abundance of CNPS cycling genes. Furthermore, the presence of MPs exhibited a positive correlation with S cycling genes and a negative correlation with C and N cycling genes. These findings suggest that variations in flow-sediment dynamics and MPs pollution have significant impact the biogeochemical cycle of the reservoir.

SHG Assisted Mixed-Phases Anatomizing in a Molecular Ferroelectric.

Anatomizing mixed-phases, referring to analyzing the mixing profiles and quantifying the phases' proportions in a material, which is of great significance in the genuine applications. Here, by using second-harmonic generation (SHG) polarimetry and piezoresponse force microscopy (PFM) techniques, this work elucidates the contributions and distributions of two different symmetric phases mixed in an archetype monoaxial molecular ferroelectric, diisopropylammonium chloride (DIPACl). The two competing phases are preferred in thermodynamics or kinetic process respectively, and this work evidences the switching behavior between the two competing phases facilitated by an external electrical field as opposed to a heating process. This research contributes novel insights into phase engineering in the field of molecular ferroelectrics and is poised to serve as a potent analytical tool for subsequent applications.

Finite element analysis of the effect of tibial osteotomy on the stress of polyethylene liner in total knee arthroplasty.

AIM: To explore the effects of tibial osteotomy varus angle combined with posterior tibial slope (PTS) on the stress of polyethylene liner in total knee arthroplasty (TKA) by building finite element model (FEM). METHODS: Established the FEM of standard TKA with tibial osteotomy varus angle 0° to 9° were established and divided into 10 groups. Next, each group was created 10 FEMs with 0° to 9° PTS separately. Calculated the stress on polyethylene liner in each group in Abaqus. Finally, the relevancy between tibial osteotomy angle and polyethylene liner stress was statistically analyzed using multiple regression analysis. RESULTS: As the varus angle increased, the area of maximum stress gradually shifted medially on the polyethylene liner. As the PTS increases, the percentage of surface contact forces on the medial and lateral compartmental of the polyethylene liner gradually converge to the same. When the varus angle is between 0° and 3°, the maximum stress of the medial compartmental surfaces of polyethylene liner rises smoothly with the increase of the PTS. When the varus angle is between 4° and 9°, as the increase of the PTS, the maximum stress of polyethylene liner rises first and then falls, forming a trough at PTS 5° and then rises again. Compared to the PTS, the varus angle has a large effect on the maximum stress of the polyethylene liner (p < .001). CONCLUSION: When the varus angle is 0° to 3°, PTS 0° is recommended, which will result in a more equalized stress distribution of the polyethylene liner in TKA.

Tobacco toxins trigger bone marrow mesenchymal stem cells aging by inhibiting mitophagy.

Smoking disrupts bone homeostasis and serves as an independent risk factor for the development and progression of osteoporosis. Tobacco toxins inhibit the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), promote BMSCs aging and exhaustion, but the specific mechanisms are not yet fully understood. Herein, we successfully established a smoking-related osteoporosis (SROP) model in rats and mice through intraperitoneal injection of cigarette smoke extract (CSE), which significantly reduced bone density and induced aging and inhibited osteogenic differentiation of BMSCs both in vivo and in vitro. Bioinformatics analysis and in vitro experiments confirmed that CSE disrupts mitochondrial homeostasis through oxidative stress and inhibition of mitophagy. Furthermore, we discovered that CSE induced BMSCs aging by upregulating phosphorylated AKT, which in turn inhibited the expression of FOXO3a and the Pink1/Parkin pathway, leading to the suppression of mitophagy and the accumulation of damaged mitochondria. MitoQ, a mitochondrial-targeted antioxidant and mitophagy agonist, was effective in reducing CSE-induced mitochondrial oxidative stress, promoting mitophagy, significantly downregulating the expression of aging markers in BMSCs, restoring osteogenic differentiation, and alleviating bone loss and autophagy levels in CSE-exposed mice. In summary, our results suggest that BMSCs aging caused by the inhibition of mitophagy through the AKT/FOXO3a/Pink1/Parkin axis is a key mechanism in smoking-related osteoporosis.

Preliminary study of the homeostatic regulation of osseointegration by nanotube topology.

The ideal implant surface plays a substantial role in maintaining bone homeostasis by simultaneously promoting osteoblast differentiation and limiting overactive osteoclast activity to a certain extent, which leads to satisfactory dynamic osseointegration. However, the rational search for implant materials with an ideal surface structure is challenging and a hot research topic in the field of tissue engineering. In this study, we constructed titanium dioxide titanium nanotubes (TNTs) by anodic oxidation and found that this structure significantly promoted osteoblast differentiation and inhibited osteoclast formation and function while simultaneously inhibiting the total protein levels of proline-rich tyrosine kinase 2 (PYK2) and focal adhesion kinase (FAK). Knockdown of the PYK2 gene by siRNA significantly suppressed the number and osteoclastic differentiation activity of mouse bone marrow mononuclear cells (BMMs), while overexpression of PYK2 inhibited osteogenesis and increased osteoclastic activity. Surprisingly, we found for the first time that neither knockdown nor overexpression of the FAK gene alone caused changes in osteogenesis or osteoclastic function. More importantly, compared with deletion or overexpression of PYK2/FAK alone, coexpression or cosilencing of the two kinases accelerated the effects of TNTs on osteoclastic and osteogenic differentiation on the surface of cells. Furthermore, in vivo experiments revealed a significant increase in positiveexpression-PYK2 cells on the surface of TNTs, but no significant change in positiveexpression -FAK cells was observed. In summary, PYK2 is a key effector molecule by which osteoblasts sense nanotopological mechanical signals and maintain bone homeostasis around implants. These results provide a referable molecular mechanism for the future development and design of homeostasis-based regulatory implant biomaterials.

Endoscopic management of duodenal perforation caused by foreign bodies in adults: A retrospective study.

BACKGROUND AND AIMS: Duodenal perforation caused by foreign bodies (FBs) is very rare but is an urgent emergency that traditionally requires surgical intervention. Several case reports have reported the successful endoscopic removal of duodenal perforating FBs. Here we aimed to evaluate the safety and efficacy of endoscopic management of duodenal perforating FBs in adults. METHODS: Between October 2004 and October 2022, 12,851 patients with endoscopically diagnosed gastrointestinal FBs from four tertiary hospitals in China were retrospectively reviewed. Patients were enrolled if they were endoscopically and/or radiographically diagnosed with duodenal perforating FBs. RESULTS: The incidence of duodenal total FBs and perforating FBs was 1.9% and 0.3%, respectively. Thirty-four patients were enrolled. Endoscopic removal was achieved in 25 patients (73.5%), and nine patients (26.5%) received surgery. For the endoscopic group, most perforating FBs were located in the duodenal bulb (36.0%) and descending part (28.0%). The adverse events included 3 mucosal injuries and 1 localized peritonitis. All patients were cured after conventional treatment. In the surgical group, most FBs were lodged in the descending part (55.6%). One patient developed localized peritonitis and one patient died of multiple organ failure. The significant features of FBs requiring surgery included FB over 10 cm, both sides perforation, multiple perforating FBs and massive pus overflow. CONCLUSION: Endoscopic removal of duodenal perforating FBs is safe and effective, and can be the first choice of treatment for experienced endoscopists. Surgical intervention may be required for patients with FBs over 10 cm, both sides perforation, multiple perforating FBs, or severe infections.

Collagen-Based Hydrogels for Cartilage Regeneration.

Cartilage regeneration remains difficult due to a lack of blood vessels. Degradation of the extracellular matrix (ECM) causes cartilage defects, and the ECM provides the natural environment and nutrition for cartilage regeneration. Until now, collagen hydrogels are considered to be excellent material for cartilage regeneration due to the similar structure to ECM and good biocompatibility. However, collagen hydrogels also have several drawbacks, such as low mechanical strength, limited ability to induce stem cell differentiation, and rapid degradation. Thus, there is a demanding need to optimize collagen hydrogels for cartilage regeneration. In this review, we will first briefly introduce the structure of articular cartilage and cartilage defect classification and collagen, then provide an overview of the progress made in research on collagen hydrogels with chondrocytes or stem cells, comprehensively expound the research progress and clinical applications of collagen-based hydrogels that integrate inorganic or organic materials, and finally present challenges for further clinical translation.

Imeglimin profoundly affects the circadian clock in mouse embryonic fibroblasts.

OBJECTIVE: Imeglimin is a novel antidiabetic drug structurally related to metformin. Metformin has been shown to modulate the circadian clock in rat fibroblasts. Accordingly, in the present study, we aimed to determine whether imeglimin can impact the circadian oscillator in mouse embryonic fibroblasts (MEFs). METHODS: MEFs carrying a Bmal1-Emerald luciferase (Bmal1-ELuc) reporter were exposed to imeglimin (0.1 or 1 mM), metformin (0.1 or 1 mM), a nicotinamide phosphoribosyltransferase inhibitor FK866, and/or vehicle. Subsequently, Bmal1-ELuc expression and clock gene mRNA expression levels were measured at 10-min intervals for 55 h and 4-h intervals for 32 h, respectively. RESULTS: Imeglimin significantly prolonged the period (from 26.3 to 30.0 h at 0.1 mM) and dose-dependently increased the amplitude (9.6-fold at 1 mM) of the Bmal1-ELuc expression rhythm; however, metformin exhibited minimal effects on these parameters. Moreover, imeglimin notably impacted the rhythmic mRNA expression of clock genes (Bmal1, Per1, and Cry1). The concurrent addition of FK866 partly inhibited the effects of imeglimin on both Bmal1-ELuc expression and clock gene mRNA expression. CONCLUSION: Collectively, these results reveal that imeglimin profoundly affects the circadian clock in MEFs. Further studies are needed to evaluate whether imeglimin treatment could exert similar effects in vivo.

Personalized radiomics signature to screen for KIT-11 mutation genotypes among patients with gastrointestinal stromal tumors: a retrospective multicenter study.

OBJECTIVES: Gastrointestinal stromal tumors (GISTs) carrying different KIT exon 11 (KIT-11) mutations exhibit varying prognoses and responses to Imatinib. Herein, we aimed to determine whether computed tomography (CT) radiomics can accurately stratify KIT-11 mutation genotypes to benefit Imatinib therapy and GISTs monitoring. METHODS: Overall, 1143 GISTs from 3 independent centers were separated into a training cohort (TC) or validation cohort (VC). In addition, the KIT-11 mutation genotype was classified into 4 categories: no KIT-11 mutation (K11-NM), point mutations or duplications (K11-PM/D), KIT-11 557/558 deletions (K11-557/558D), and KIT-11 deletion without codons 557/558 involvement (K11-D). Subsequently, radiomic signatures (RS) were generated based on the arterial phase of contrast CT, which were then developed as KIT-11 mutation predictors using 1408 quantitative image features and LASSO regression analysis, with further evaluation of its predictive capability. RESULTS: The TC AUCs for K11-NM, K11-PM/D, K11-557/558D, and K11-D ranged from 0.848 (95% CI 0.812-0.884), 0.759 (95% CI 0.722-0.797), 0.956 (95% CI 0.938-0.974), and 0.876 (95% CI 0.844-0.908), whereas the VC AUCs ranged from 0.723 (95% CI 0.660-0.786), 0.688 (95% CI 0.643-0.732), 0.870 (95% CI 0.824-0.918), and 0.830 (95% CI 0.780-0.878). Macro-weighted AUCs for the KIT-11 mutant genotype ranged from 0.838 (95% CI 0.820-0.855) in the TC to 0.758 (95% CI 0.758-0.784) in VC. TC had an overall accuracy of 0.694 (95%CI 0.660-0.729) for RS-based predictions of the KIT-11 mutant genotype, whereas VC had an accuracy of 0.637 (95%CI 0.595-0.679). CONCLUSIONS: CT radiomics signature exhibited good predictive performance in estimating the KIT-11 mutation genotype, especially in prediction of K11-557/558D genotype. RS-based classification of K11-NM, K11-557/558D, and K11-D patients may be an indication for choice of Imatinib therapy.

Effect of hexavalent chromium on growth performance and metabolism in broiler chicken.

Hexavalent chromium Cr (VI) is one of the most hazardous heavy metals in the environment and is toxic to living organisms causing tissue damage, disruption of the intestinal microbiota and cancer. However, there is little information on the relationship between the Cr (VI) and broiler chickens. The current study was performed to investigate the effect of Cr (VI) on growth performance, serum biochemical analysis, histopathological observations, and metabolomics analysis in broilers. Results show that Cr (VI) exposure significantly decreased the body weight (p < 0.01) and caused liver damages in broilers. With the extension of Cr (VI) action time, the liver appeared obvious pathological changes, including hepatic cord disorder, incomplete hepatocyte additionally, decreased serum biochemical indices of calcium (Ca), phosphorus (P), total protein (TP), phosphatase (ALP), and globin (GLB) significantly (p < 0.01). Moreover, metabolomics analysis indicated that 29 differential metabolites were identified, such as phytosphingosine, L-Serine, 12, 13-DHOME, Alpha-dimorphecolic acid, L-Methionine, L-Phenylalanine, 3-Dehydroshikimate, L-Tyrosine, and N-Acetyl-L-phenylalanine were significantly decreased under the action of Cr (VI) (p < 0.05). These 29 differential metabolites are mainly involved in 35 metabolic pathways, such as aminoacyl-tRNA biosynthesis, phenylalanine metabolism, sphingolipid, and linoleic metabolism. The study revealed that exposure to Cr (VI) resulted in a decrease in growth performance and metabolism, with the hazards and toxicity in broiler chicken. The findings provided new insight and a comprehensive understanding of the relationship between Cr (VI) and broiler chickens.

Tobacco toxins induce osteoporosis through ferroptosis.

Clinical epidemiological studies have confirmed that tobacco smoking disrupts bone homeostasis and is an independent risk factor for the development of osteoporosis. The low viability and inferior osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) are important etiologies of osteoporosis. However, few basic studies have elucidated the specific mechanisms that tobacco toxins devastated BMSCs and consequently induced or exacerbated osteoporosis. Herein, our clinical data showed the bone mineral density (BMD) values of femoral neck in smokers were significantly lower than non-smokers, meanwhile cigarette smoke extract (CSE) exposure led to a significant decrease of BMD in rats and dysfunction of rat BMSCs (rBMSCs). Transcriptomic analysis and phenotype experiments suggested that the ferroptosis pathway was significantly activated in CSE-treated rBMSCs. Accumulated intracellular reactive oxygen species activated AMPK signaling, furtherly promoted NCOA4-mediated ferritin-selective autophagic processes, increased labial iron pool and lipid peroxidation deposition, and ultimately led to ferroptosis in rBMSCs. Importantly, in vivo utilization of ferroptosis and ferritinophagy inhibitors significantly alleviated BMD loss in CSE-exposed rats. Our study innovatively reveals the key mechanism of smoking-related osteoporosis, and provides a possible route targeting on the perspective of BMSC ferroptosis for future prevention and treatment of smoking-related bone homeostasis imbalance.

Effects of acupuncture therapy in diabetic neuropathic pain: A systematic review and meta-analysis.

OBJECTIVE: To evaluate the effectiveness of acupuncture in relieving diabetic neuropathic pain and to establish a more reliable and efficient foundation for acupuncture practice in diabetes care. METHODS: The Chinese National Knowledge Infrastructure, Wanfang database, Chongqing Weipu, Chinese Biomedical Literature Database, PubMed, Embase, and Cochrane Library were all searched for a randomized controlled trial research of acupuncture for DNP. Two researchers independently performed literature screening, quality evaluation, and data extraction. After selecting studies and extracting data, we conducted the data analysis using RevMan 5.4 and Stata 14.0. The quality was assessed using the Cochrane Risk of Bias Assessment Tool. RESULTS: An extensive review of 19 studies involving 1276 patients up to April 29, 2023, found that acupuncture was successful in improving pain intensity [MD= -1.09; 95% CI (-1.28, -0.89), P < 0.00001], clinical efficacy indicating pain changes [RR= 1.22; 95% CI (1.15, 1.29), P < 0.00001], and clinical neuropathy [MD= -1.55; 95% CI ( -3.00, -0.09), P = 0.04] in DNP patients. Quality of life was also improved, with few side effects reported. CONCLUSION: According to this meta-analysis, acupuncture therapy significantly improved the clinical efficacy of pain intensity, pain changes, and clinical neuropathy in patients with DNP, improved the quality of life of patients to a certain extent, and had lower side effects. This discovery provides evidence-based and practical recommendations for the treatment of DNP patients.

BOP1 Promotes Prostate Cancer through the DUSP6/MAPK Pathway.

BACKGROUND: Nucleolar prominence is a biomarker of prostate cancer (CaP), and the nucleolar protein block of proliferation 1 (BOP1) participates in the development of CaP, which has great significance for CaP therapy. Thus, this study explored the mechanism of BOP1 in CaP development. METHODS: BOP1 expression levels in the tumor tissues of CaP patients and in PC3 tumor cells were determined. The viability, apoptosis rate of PC3 cells, and apoptosis-related proteins levels were determined to explore the effect of BOP1 on tumor-cell growth in vitro. BOP1 function in the metastasis of PC3 cells was further assessed by Transwell experiment. We also studied the influence of BOP1 on the expression of mitogen-activated protein kinase (MAPK) pathway-related proteins and investigated the regulatory effect of BOP1 on dual-specificity phosphatase 6 (DUSP6). RESULTS: BOP1 expression was upregulated in the tumor tissues and PC3 cells of CaP patients. BOP1 knockout reduced the activity of PC3 cells and induced apoptosis, significantly inhibiting the metastasis of PC3 cells. DUSP6 was overexpressed in tumor tissues and PC3 cells. BOP1 knockout inhibited DUSP6 expression and the MAPK pathway. DUSP6 overexpression reversed the inhibition of BOP1 siRNA (si-BOP1) on PC3 cells and the activated MAPK signaling pathway. CONCLUSIONS: This finding demonstrated that BOP1 promoted CaP progression by regulating the DUSP6/MAPK pathway.

Huangqin decoction alleviates lipid metabolism disorders and insulin resistance in nonalcoholic fatty liver disease by triggering Sirt1/NF-κB pathway.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is a clinicopathological entity characterized by intrahepatic ectopic steatosis. As a consequence of increased consumption of high-calorie diet and adoption of a sedentary lifestyle, the incidence of NAFLD has surpassed that of viral hepatitis, making it the most common cause of chronic liver disease globally. Huangqin decoction (HQD), a Chinese medicinal formulation that has been used clinically for thousands of years, has beneficial outcomes in patients with liver diseases, including NAFLD. However, the role and mechanism of action of HQD in lipid metabolism disorders and insulin resistance in NAFLD remain poorly understood. AIM: To evaluate the ameliorative effects of HQD in NAFLD, with a focus on lipid metabolism and insulin resistance, and to elucidate the underlying mechanism of action. METHODS: High-fat diet-induced NAFLD rats and palmitic acid (PA)-stimulated HepG2 cells were used to investigate the effects of HQD and identify its potential mechanism of action. Phytochemicals in HQD were analyzed by high-performance liquid chromatography (HPLC) to identify the key components. RESULTS: Ten primary chemical components of HQD were identified by HPLC analysis. In vivo, HQD effectively prevented rats from gaining body and liver weight, improved the liver index, ameliorated hepatic histological aberrations, decreased transaminase and lipid profile disorders, and reduced the levels of pro-inflammatory factors and insulin resistance. In vitro studies revealed that HQD effectively alleviated PA-induced lipid accumulation, inflammation, and insulin resistance in HepG2 cells. In-depth investigation revealed that HQD triggers Sirt1/NF-κB pathway-modulated lipogenesis and inflammation, contributing to its beneficial actions, which was further corroborated by the addition of the Sirt1 antagonist EX-527 that compromised the favorable effects of HQD. CONCLUSION: In summary, our study confirmed that HQD mitigates lipid metabolism disorders and insulin resistance in NAFLD by triggering the Sirt1/NF-κB pathway.

Quercetin promotes autophagy to alleviate cigarette smoke-related periodontitis.

BACKGROUND AND OBJECTIVES: Cigarette smoking has been reported as an independent risk factor for periodontitis. Tobacco toxins affect periodontal tissue not only locally but also systemically, leading to the deterioration and recurrence of periodontitis. However, the mechanism of cigarette smoke-related periodontitis (CSRP) is unclear and thus lacks targeted treatment strategies. Quercetin, a plant-derived polyphenolic flavonoid, has been reported to have therapeutic effects on periodontitis due to its documented antioxidant activity. This study aimed to evaluate the effects of quercetin on CSRP and elucidated the underlying mechanism. METHODS: The cigarette smoke-related ligature-induced periodontitis mouse model was established by intraperitoneal injection of cigarette smoke extract (CSE) and silk ligation of bilateral maxillary second molars. Quercetin was adopted by gavage as a therapeutic strategy. Micro-computed tomography was used to evaluate the alveolar bone resorption. Immunohistochemistry detected the oxidative stress and autophagy markers in vivo. Cell viability was determined by Cell Counting Kit-8, and oxidative stress levels were tested by 2,7-dichlorodihydrofluorescein diacetate probe and lipid peroxidation malondialdehyde assay kit. Alkaline phosphatase and alizarin red staining were used to determine osteogenic differentiation. Network pharmacology analysis, molecular docking, and western blot were utilized to elucidate the underlying molecular mechanism. RESULTS: Alveolar bone resorption was exacerbated and oxidative stress products were accumulated during CSE exposure in vivo. Oxidative stress damage induced by CSE caused inhibition of osteogenic differentiation in vitro. Quercetin effectively protected the osteogenic differentiation of human periodontal ligament cells (hPDLCs) and periodontal tissue by upregulating the expression of Beclin-1 thus to promote autophagy and reduce oxidative stress damage. CONCLUSION: Our results established a role of oxidative stress damage and autophagy dysfunction in the mechanism of CSE-induced destruction of periodontal tissue and hPDLCs, and provided a potential application value of quercetin to ameliorate CSRP.

Three-Dimensional Matrix Stiffness Activates the Piezo1-AMPK-Autophagy Axis to Regulate the Cellular Osteogenic Differentiation.

Extracellular matrix (ECM) stiffness is a key stimulus affecting cellular differentiation, and osteoblasts are also in a three-dimensional (3D) stiff environment during the formation of bone tissues. However, it remains unclear how cells perceive matrix mechanical stiffness stimuli and translate them into intracellular signals to affect differentiation. Here, for the first time, we constructed a 3D culture environment by GelMA hydrogels with different amino substitution degrees and found that Piezo1 expression was significantly stimulated by the stiff matrix with high substitution; meanwhile, the expressions of osteogenic markers OSX, RUNX2, and ALP were also observably improved. Moreover, knockdown of Piezo1 in the stiff matrix revealed significant reduction of the abovementioned osteogenic markers. In addition, in this 3D biomimetic ECM, we also observed that Piezo1 can be activated by the static mechanical conditions of the stiff matrix, leading to the increase of the intracellular calcium content and accompanied with a continuous change in cellular energy levels as ATP was consumed during cellular differentiation. More surprisingly, we found that in the 3D stiff matrix, intracellular calcium as a second messenger promoted the activation of the AMP-activated protein kinase (AMPK) and unc-51-like autophagy-activated kinase 1 (ULK1) axis and modestly modulated the level of autophagy, bringing it more similar to differentiated osteoblasts, with increased ATP energy metabolism consumption. Our study innovatively clarifies the regulatory role of the mechanosensitive ion channel Piezo1 in a static mechanical environment on cellular differentiation and verifies the activation of the AMPK-ULK1 axis in the cellular ATP energy metabolism and autophagy level. Collectively, our research develops the understanding of the interaction mechanisms of biomimetic extracellular matrix biomaterials and cells from a novel perspective and provides a theoretical basis for bone regeneration biomaterials design and application.

Nanotube patterning reduces macrophage inflammatory response via nuclear mechanotransduction.

The inflammatory immune environment surrounding titanium bone implants determines the formation of osseointegration, and nanopatterning on implant surfaces modulates the immune microenvironment in the implant region. Among many related mechanisms, the mechanism by which nanopatterning controls macrophage inflammatory response still needs to be elucidated. In this paper, we found that inhibition of the nuclear envelope protein lamin A/C by titania nanotubes (TNTs) reduced the macrophage inflammatory response. Knockdown of lamin A/C reduced macrophage inflammatory marker expression, while overexpression of lamin A/C significantly elevated inflammatory marker expression. We further found that suppression of lamin A/C by TNTs limited actin polymerization, thereby reducing the nuclear translocation of the actin-dependent transcriptional cofactor MRTF-A, which subsequently reduced the inflammatory response. In addition, emerin, which is a key link between lamin A/C and actin, was delocalized from the nucleus in response to mechanical stimulation by TNTs, resulting in reduced actin organization. Under inflammatory conditions, TNTs exerted favourable osteoimmunomodulatory effects on the osteogenic differentiation of mouse bone marrow-derived stem cells (mBMSCs) in vitro and osseointegration in vivo. This study shows and confirms for the first time that lamin A/C-mediated nuclear mechanotransduction controls macrophage inflammatory response, and this study provides a theoretical basis for the future design of immunomodulatory nanomorphologies on the surface of metallic bone implants.