Temporomandibular joint osteoarthritis (TMJ-OA) is a common disease often accompanied by pain, seriously affecting physical and mental health of patients. Abnormal innervation at the osteochondral junction has been considered as a predominant origin of arthralgia, while the specific mechanism mediating pain remains unclear. To investigate the underlying mechanism of TMJ-OA pain, an abnormal joint loading model was used to induce TMJ-OA pain. We found that during the development of TMJ-OA, the increased innervation of sympathetic nerve of subchondral bone precedes that of sensory nerves. Furthermore, these two types of nerves are spatially closely associated. Additionally, it was discovered that activation of sympathetic neural signals promotes osteoarthritic pain in mice, whereas blocking these signals effectively alleviates pain. In vitro experiments also confirmed that norepinephrine released by sympathetic neurons promotes the activation and axonal growth of sensory neurons. Moreover, we also discovered that through releasing norepinephrine, regional sympathetic nerves of subchondral bone were found to regulate growth and activation of local sensory nerves synergistically with other pain regulators. This study identified the role of regional sympathetic nerves in mediating pain in TMJ-OA. It sheds light on a new mechanism of abnormal innervation at the osteochondral junction and the regional crosstalk between peripheral nerves, providing a potential target for treating TMJ-OA pain.
Animals ; Osteoarthritis/physiopathology* ; Mice ; Sympathetic Nervous System/physiopathology* ; Temporomandibular Joint Disorders/physiopathology* ; Arthralgia ; Sensory Receptor Cells ; Disease Models, Animal ; Norepinephrine ; Male ; Temporomandibular Joint/physiopathology* ; Pain Measurement

Objective To explore the effect of cannabinoid receptor 2(CB2)on orthodontic tooth movement(OTM)rate and periodontal tissue reconstruction of pressure area in mice.Methods Thirty CB2-/-male mice and thirty littermate control WT male mice were individually accepted the orthodontic appliance at their age of 6 weeks.The mice were respectively scarified at 3 days,7 days,14 days and 21 days after the operation.Then the tooth movement distance was examined through the stereomicroscope.Hematoxylin-eosin staining was performed to explore the biological responses of periodontium at the distal mesial root pressure area.Anti-tartrate acid phospha-tase staining was performed to calculate the number and distribution of osteoclasts at the distal mesial root pressure area,and MMP-9 was evaluated by immunohistochemistry to examine the number of MMP-9(+)monocytes and multinucleated cells in the same district as the TRAP staining.Results Compared with those WT mice at 3,7,14 and 21 days,OTM distance showed a gradual increased tendency according with experimental time over 21 days.The widths of periodontal ligament on the pressure side were markedly greater in CB2-/-mice than WT mice at 7,14 and 21 days(P＜0.000 1).The numbers of TRAP positive osteoclasts were significantly greater in CB2-/-mice than those in WT mice at 14 days of OTM(P＜0.001).MMP-9 immunohistochemical staining showed that the number of MMP-9(+)monocytes and multinucleated cells was more in CB2-/-mice than that in WT mice at 14 days of OTM(P＜0.05).Conclusion The absence of CB2 accelerates orthodontic tooth movement under or-thodontic force.The absence of CB2 reinforces bone resorption in orthodontic tooth movement compressive area dur-ing orthodontic tooth movement.

BACKGROUND:Reactive oxygen species is a double-edged sword in the development of periodontitis and the regeneration of periodontal tissue.Low concentration of reactive oxygen species induces the differentiation of periodontal fibroblasts,and excessive reactive oxygen species will cause damage to periodontal tissue.In the process of inflammation,the accumulation of reactive oxygen species in periodontal tissue induces damage to cells and tissues through a variety of signaling pathways or through redox reactions. OBJECTIVE:To review the double-edged sword effect of reactive oxygen species in periodontitis and periodontal tissue regeneration,thereby providing potential targets and treatment ideas for the clinical treatment of periodontitis and periodontal tissue regeneration. METHODS:Databases of CNKI and PubMed were searched for relevant articles published from April 1990 to April 2023 with the key words of"periodontal tissue engineering,periodontal defect,regeneration of periodontal tissue,chronic periodontitis,reactive oxygen species,oxidative stress,antioxidative stress,oxidative injuries,free radicals,reactive nitrogen species"in Chinese and English,respectively.By reading the titles and abstracts,repetitive studies or irrelevant literatures were excluded.Finally,77 articles were included for review. RESULTS AND CONCLUSION:Reactive oxygen species are a kind of free radicals with high reactivity.When bacteria invade,reactive oxygen species are released in large quantities by the respiratory explosion of neutrophils and play a double-edged sword role in the body through their redox reactions or as pleiotropic physiological signal transmitters.In periodontitis,low concentrations of reactive oxygen species can kill invading pathogenic bacteria,but high concentrations of reactive oxygen species promote the secretion of inflammatory factors through JNK,RANK,Wnt/β-Catenin and other pathways,promote immune damage or directly damage tissues through oxidative reactions or through other ways to aggravate periodontitis.In the process of periodontal tissue regeneration,low concentrations of reactive oxygen species can promote the proliferation and differentiation of periodontal ligament stem cells through Nrf2 and other pathways and can promote the secretion of vascular endothelial growth factor to promote vascular regeneration.This provides seeds and a nutrient environment for periodontal tissue regeneration,which is extremely important for promoting periodontal tissue regeneration.However,high concentrations of reactive oxygen species will reduce the activity of periodontal ligament stem cells and damage endothelial cells,which are not conducive to vascular regeneration.This will inhibit wound healing and periodontal tissue regeneration.Therefore,it is important to explore the role of reactive oxygen species in the development of periodontitis and periodontal tissue regeneration and to discover the potential mechanism of its action and to explore the appropriate concentration for its role in reducing periodontal inflammation and promoting periodontal tissue regeneration for the future treatment of periodontitis and periodontal tissue regeneration in clinical practice.Using reactive oxygen species as a target to explore ways to reduce periodontal inflammation and promote periodontal ligament stem cell activity and vascular regeneration may become a clinically effective method for treating periodontitis and promoting periodontal tissue regeneration.

Age-dependent loss of skeletal muscle mass and function is a feature of sarcopenia, and increases the risk of many aging-related metabolic diseases. Here, we report phenotypic and single-nucleus transcriptomic analyses of non-human primate skeletal muscle aging. A higher transcriptional fluctuation was observed in myonuclei relative to other interstitial cell types, indicating a higher susceptibility of skeletal muscle fiber to aging. We found a downregulation of FOXO3 in aged primate skeletal muscle, and identified FOXO3 as a hub transcription factor maintaining skeletal muscle homeostasis. Through the establishment of a complementary experimental pipeline based on a human pluripotent stem cell-derived myotube model, we revealed that silence of FOXO3 accelerates human myotube senescence, whereas genetic activation of endogenous FOXO3 alleviates human myotube aging. Altogether, based on a combination of monkey skeletal muscle and human myotube aging research models, we unraveled the pivotal role of the FOXO3 in safeguarding primate skeletal muscle from aging, providing a comprehensive resource for the development of clinical diagnosis and targeted therapeutic interventions against human skeletal muscle aging and the onset of sarcopenia along with aging-related disorders.
Animals ; Humans ; Sarcopenia/metabolism* ; Forkhead Box Protein O3/metabolism* ; Muscle, Skeletal/metabolism* ; Aging/metabolism* ; Primates/metabolism*

Background: Colorectal cancer (CRC) is one of the most common cancers in China and even in the world, and metastasis is the main cause of death. However, there is lack of sufficient molecular biomarkers for predicting effectively the occurrence of metastasis. Aims: To explore the expression of fibulin-2 (FBLN2) in CRC and the underlying mechanism of its effect on tumor invasion and metastasis. Methods: Bioinformatics data of PRJNA218851 data set from the SRA database were extracted to screen CRC metastasis-associated genes. Then these differentially expressed genes were applied for gene enrichment analysis to identify the most significant pathways. Data from TCGA and clinical CRC samples were used to analyze the expression of FBLN2 in CRC tissues and normal tissues, and the relationship between FBLN2 and clinicopathological features and prognosis of CRC patients. Expression of FBLN2 in normal colorectal mucosal cell line, CRC cell lines, and clinical CRC samples was detected by real-time PCR. After FBLN2 was knockdown or over expressed in CRC cells, CCK-8 assay, clone formation assay, Transwell cell invasion and migration assay, and wound healing assay were performed to observe the effect of FBLN2 on the proliferation, invasion and migration abilities of CRC cells. Gene set enrichment analysis was conducted to screen the potential downstream pathway of FBLN2, and then the pathway screened was verified. Results: The expression of FBLN2 was low in eight CRC cell lines and CRC tissues, yet the expression in metastatic CRC was significantly higher than that in non-metastatic ones. Compared with CRC patients with low FBLN2 expression, CRC patients with high FBLN2 expression were prone to have lymph node metastasis and distant metastasis, and with higher clinical stage and poorer prognosis. Knockdown of FBLN2 could decrease the invasion and migration abilities of CRC cells, but had no impact on cell proliferation. FBLN2 was positively correlated with CDH2, Snai1 and vimentin, indicating that the epithelial-mesenchymal transition (EMT) pathway might be the downstream pathway of FBLN2. Conclusions: FBLN2 is low expressed in CRC but the expression is increased in metastatic CRC. Therefore, it might be used as a molecular biomarker for screening early metastasis. FBLN2 might enhance CRC invasion and metastasis through activating EMT pathway and is associated with poor prognosis.