Clock gene Per1 regulates rat temporomandibular osteoarthritis through NF-κB pathway: an in vitro and in vivo study.

PURPOSE: Temporomandibular joint osteoarthritis (TMJOA) is a common disease that negatively affects the life quality of human beings. Circadian rhythm acts an important role in life activities. However, whether the clock genes are rhythmic expressed in mandibular condylar chondrocytes, or the clock genes have an effect on the progression of TMJOA remains unknown. In this study, we aim to explore expression of clock genes and regulatory mechanism of TMJOA in rat mandibular condylar chondrocytes. METHODS: After synchronized by dexamethasone, the expression of core clock genes Per1, Per2, Clock, Cry1, Cry2 and Bmal1 and cartilage matrix degrading factor gene Mmp13 were analyzed in mandibular condylar chondrocytes every 4 h with RT-qPCR. The mandibular condylar chondrocytes were stimulated with IL-1ß, and expression of Per1, Mmp13, P65 and p-P65 was assessed by RT-qPCR and Western blot. Sh-Per1 lentivirus was used to assess the effect of clock gene Per1 in IL-1ß-induced chondrocytes, and expression of Mmp13, P65 and p-P65 was measured. After establishing a rat TMJOA model using unilateral anterior crossbite (UAC), micro-CT, H & E, Alcian Blue & Nuclear Fast Red and Safranin O & Fast Green, cartilage thickness was utilized to assess the damage of cartilage and subchondral bone. Immunohistochemistry of PER1, MMP13 and P65 was performed in condylar sections. RESULTS: All core clock genes and Mmp13 were rhythmically expressed. And Mmp13 expression curve was closed in phase and amplitude with Per1. After stimulation with IL-1ß, the expression of MMP13, PER1 and P65 and ratio of p-P65/P65 increased in condylar chondrocytes. After Per1 was down-regulated in condylar chondrocytes, the expression of MMP13 and P65 and ratio of p-P65/P65 decreased. Compared with the condyles of Sham group, the bony parameters of UAC group were significantly worse. The thickness of cartilage in UAC group significantly reduced. The modified Mankin scores and the expression of PER1, MMP13 and P65 in cartilage of UAC group significantly increased compared with Sham group. CONCLUSION: Core clock genes and Mmp13 are rhythmic expressed in rat mandibular condylar chondrocytes. PER1 can regulate the expression of MMP13 through NF-κB pathway in IL-1ß-induced mandibular condylar chondrocytes.

Dopamine Suppresses Osteogenic Differentiation of Rat Bone Marrow-Derived Mesenchymal Stem Cells via AKT/GSK-3ß/ß-Catenin Signaling Pathway.

Nervous system is critically involved in bone homeostasis and osteogenesis. Dopamine, a pivotal neurotransmitter, plays a crucial role in sympathetic regulation, hormone secretion, immune activation, and blood pressure regulation. However, the role of dopamine on osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (rBMSCs) remains poorly understood. In this study, we firstly investigated the effect of dopamine on the apoptosis, proliferation, and osteogenic differentiation of rBMSCs. Dopamine did not, however, interfere with the apoptosis and proliferation of rBMSCs. Interestingly, dopamine suppressed the osteogenic differentiation of rBMSCs, as characterized by reduced ALP staining, ALP activity, mineralized nodule formation, and the mRNA and protein levels of osteogenesis-related genes (Col1a1, Alp, Runx2, Opn, and Ocn). Furthermore, dopamine inactivated AKT/GSK-3ß/ß-catenin signaling pathway. Treatment of LiCl (GSK-3ß inhibitor) rescued the inhibitory effects of dopamine on osteogenic differentiation of rBMSCs. LY294002 (AKT inhibitor) administration exacerbated the inhibitory effects of dopamine on osteogenic differentiation of rBMSCs. Taken together, these findings indicate that dopamine suppresses osteogenic differentiation of rBMSCs via AKT/GSK-3ß/ß-catenin signaling pathway. Our study provides new insights into the role of neurotransmitters in bone homeostasis.

IL-12RB1: a novel immune prognostic biomarker for oral squamous cell carcinoma and linked to PD-1/PD-L1 expression in the tumor immune microenvironment.

Background: This study aimed to screen and identify potential immune biomarker to predict the prognosis of oral squamous cell carcinoma (OSCC). Methods: Data of OSCC patient from The Cancer Genome Atlas (TCGA) database were downloaded, and the ESTIMATE algorithm was used to calculate stromal and immune scores. Differentially expressed genes (DEGs) between the high and low immune score groups were screened, and Kaplan-Meier survival analysis was performed to identify the DEGs linked to the overall survival (OS) time of OSCC patients. Then, those DEGs were validated in anther cohort. A correlation analysis was used to further screen the prognostic genes which were tightly linked to the expression of programmed cell death 1 (PD-1)/programmed death-ligand 1 (PD-L1). The expression profiles of the candidate genes interleukin 12 receptor subunit beta 1 (IL-12RB1), cytotoxic T-lymphocyte associated protein 4 (CTLA4), and G protein-coupled receptor 25 (GPR25) were identified in the single-cell RNA sequence OSCC dataset from GSE103322. Finally, immunohistochemistry (IHC) and immunofluorescence (IF) were applied to confirm the expression pattern of IL-12RB1 in OSCC tissue microarray. Kaplan-Meier analysis was used to assess the prognostic significance of IL-12RB1 staining score in the malignant and non-malignant cells among the patients. Results: The high immune score group showed better OS compared with that of the low immune scores group. Among 339 DEGs, 90 were identified as being tightly linked to OS time. In the validation set, 23 genes were confirmed to be closely associated with survival prognosis, and the expression levels of IL-12RB1, CTLA4, and GPR25 were commonly associated with the expression of PD-1/PD-L1. The RNA-sequencing showed that IL-12RB1 was expressed in epithelial and immune cells, whereas CTLA4 and GPR25 were relatively poorly expressed in the OSCC tissue. IHC showed that IL-12RB1 was positively expressed in both malignant and non-malignant cells. IF showed that IL-12RB1 was co-expressed with CD3, CD68, PD-1, and PD-L1 on the cytomembrane. Additionally, high score of IL-12RB1 expression in the non-malignant cells was a prognostic risk factor for OS of OSCC. Conclusions: IL-12RB1 was tightly associated with survival of OSCC and with the expression levels of PD-1/PD-L1 in the tumor immune microenvironment.

Role of osteoprotegerin in the regulation of dental epithelial­mesenchymal signaling during tooth development.

Dental epithelial­mesenchymal signaling is crucial for tooth development, but the detailed mechanism is not fully understood. Using microarray analysis, it was revealed that the expression of osteoprotegerin, an important factor regulating bone remodeling, significantly increased after removal of the dental epithelium. Immunohistochemical staining revealed that osteoprotegerin expression within the dental mesenchyme was quite low during the prenatal period, but significantly increased after birth. To investigate the influence of osteoprotegerin upon tooth development, first­molar tooth germs from embryonic day 14.5 (E14.5) Chinese Kunming mice were treated with different concentrations of osteoprotegerin. It was revealed that osteoprotegerin could inhibit the expression of odontogenic markers while promoting the expression of osteogenic markers, thereby disrupting tooth morphogenesis. These findings were further supported by in vitro and in vivo cultures. Finally, quantitative reverse transcription­polymerase chain reaction and immunofluorescence studies revealed that, after osteoprotegerin treatment, the activity of the wingless/integrated (Wnt)/ß­catenin pathway increased, indicating that increased osteoprotegerin expression in prenatal tooth development could lead to uncontrolled upregulation of the Wnt/ß­catenin pathway.