Acute pulpitis promotes purinergic signaling to induce pain in rats via P38MAPK/NF-κB signaling pathway.

Toothache is one of the most common types of pain, but the mechanisms underlying pulpitis-induced pain remain unknown. The ionotropic purinergic receptor family (P2X) is reported to mediate nociception in the nervous system. This study aims to investigate the involvement of P2X3 in the sensitisation of the trigeminal ganglion (TG) and the inflammation caused by acute pulpitis. An acute tooth inflammation model was established by applying LPS to the pulp of SD rats. We found that the increased expression of P2X3 was induced by acute pulpitis. A selective P2X3 inhibitor (A-317491) reduced pain-like behavior in the maxillofacial region of rats and depressed the activation of neurons in the trigeminal ganglion induced by pulpitis. The upregulated MAPK signaling (p-p38, p-ERK1/2) expression in the ipsilateral TG induced by pulpitis could also be depressed by the application of the P2X3 inhibitor. Furthermore, the expression of markers of inflammatory processes, such as NF-κB, TNF-α and IL-1ß, could be induced by acute pulpitis and deduced by the intraperitoneal injection of P2X3 antagonists. Our findings demonstrate that purinergic P2X3 receptor signaling in TG neurons contributes to pulpitis-induced pain in rats and that P2X3 signaling may be a potential therapeutic target for tooth pain.

The effect of different storage times on the oxygen-carrying capacity of the exosomes of red blood cells.

BACKGROUND: After storing blood for a period of time, the structure and properties of the red blood cells (RBC) will change, which results in a decrease in the oxygen-carrying capacity, and further has a certain impact on their exosomes. OBJECTIVES: Effective oxygen uptake (Q), P50, 2,3-DPG, and Na+-K+-ATP of RBC after different storage times were detected. Electron microscopy was used to observe the morphology of RBC and the characteristics of secreting exosomes. Western blot was used to detect the expression of phenotypes CD63 and CD81 of exosomes, and the expression of mitochondrial riboprotein MRPS35 of exosomes was also detected to explore the mechanism of decreased function of RBC with the extension of preservation time. MATERIAL AND METHODS: After the RBC suspension was prepared, the effective oxygen-carrying capacity (Q) and P50, as well as 2,3-DPG and Na+-K+-ATP were prepared. This was followed by morphology observation of erythrocyte exosomes using transmission electron microscope (TEM), and by western blot analysis of exosome phenotypes CD63 and CD81. RESULTS: Erythrocytes secrete exosomes, which results in abnormal expression of related proteins in mitochondria. This leads to increased ROS production, mitochondrial apoptosis and, finally, changes in or damage to erythrocytes. CONCLUSIONS: Changes in the rheological properties and oxygen-carrying functions of erythrocytes during preservation are all observable manifestations, and underlying these manifestations are mechanisms of damage to erythrocytes at a molecular level. Erythrocytes secrete exosomes, which results in abnormal expression of related proteins in mitochondria, increasing ROS production, mitochondrial apoptosis and, finally, changes or damage to erythrocytes.

Antishock Characteristics of Erythrocyte-mediated Endoplasmic Reticulum Stress in Macrophages in Severe Hemorrhagic Shock Environment Based on TLR9-cGAS-STING-IFN Signal Axis.

This study aimed to investigate the protective effects of erythrocyte-mediated endoplasmic reticulum (ER) stress in macrophages in hemorrhagic shock. An hemorrhagic shock model was established in male BALB/c mice. Animals were randomly divided into three groups (n = 8): control group (A), erythrocyte reinfusion group (B), and TLR9 inhibition group (C). Eight healthy BALB/c mice were also included as group N (n = 8). Mice in group A were not treated, while mice in groups B and C were transfused with red blood cells separated from the blood of mice in group N. Flow cytometry was used to detect the expression of erythrocyte surface protein TLR9 in each group. Immunofluorescence assay was used to analyze the distribution and relative expression of protein STING in macrophages. Flow cytometry was used to analyze the expression of STING, ATF6, and IRE1 in macrophages. Enzyme-linked immunosorbent assay was used to analyze the levels of inflammatory signal molecules, including IFN-α, IFN-ß, IL-6, CCL4, CCL5, and IL-6. FITC-Annexin V was used to analyze the apoptosis of immune cells (macrophages) in mouse blood samples and to detect the concentration of calcium ions in erythrocyte cytoplasm. The results showed that the expression of erythrocyte surface protein TLR9; the distribution of STING-positive cells in macrophages; the expressions of STING, ATF6, and IRE1 in macrophages; the levels of inflammatory signal molecules; the apoptosis rate of macrophages; and the intracellular calcium concentration in erythrocytes in group B were higher than those in group A, followed by group C. These results suggest that TLR9 regulates ER stress in macrophages of mice with hemorrhagic shock through the TLR9-cGAS-STING-IFN signaling pathway. Increased expression of TLR9 enhanced macrophage activity, reduced apoptosis, enhanced inflammatory response and immune response, and restored electrolyte level, which might be a therapeutic option for the treatment of hemorrhagic shock.