Moderate Hydrogen Peroxide Postconditioning Ameliorates Ischemia/Reperfusion Injury in Cardiomyocytes via STAT3-Induced Calcium, ROS, and ATP Homeostasis

Tetrandrine downregulates TRPV2 expression to ameliorate myocardial ischemia/reperfusion injury in rats via regulation of cardiomyocyte apoptosis, calcium homeostasis and mitochondrial function

Our previous study has indicated that tetrandrine (TET) can target miR-202-5p to repress the activation of transient receptor potential vanilloid type 2 (TRPV2), eventually ameliorating the progression of myocardial ischemia/reperfusion injury (MI/RI). This study is aimed to further ascertain the detailed mechanisms between TET and TRPV2 in MI/RI pathogenesis. Here, a myocardial I/R injury rat model and a hypoxia-reoxygenation (H/R) model in rat myocardial cell line (H9C2 cells) were established. We reported that pronounced upregulation of TRPV2 was observed in I/R rats and H/R-induced H9C2 cells. Silencing of TRPV2 could improve cardiac function and myocardial injury, reduced infarction size, and promoted cardiomyocyte proliferation in I/R rats. In I/R rats or H/R-induced H9C2 cells, cardiomyocyte apoptosis was inhibited by knocking-down TRPV2. Meanwhile, the silenced TRPV2 or TET treatment ameliorated the damaged mitochondrial structure, mitigated ROS generation, restored the impaired ΔΨM, inhibited mPTP opening and alleviated Ca2+ overload in H/R-induced H9C2 cells. The results obtained from the overexpression of TRPV2 were contrary to those depicted above. Moreover, TET could downregulate TRPV2 expression, while the overexpression of TRPV2 could reverse the above protective effects of TET in H/R-induced H9C2 cells. The results indicated that TET may function as a TRPV2 blocking agent, thereby attenuating the progression of MI/RI through modulation of cardiomyocyte apoptosis, calcium homeostasis and mitochondrial function. These findings offer a theoretical foundation for potential clinical application of TET therapy in patients with MI/RI.

Gallic Acid Improves Comorbid Chronic Pain and Depression Behaviors by Inhibiting P2X7 Receptor-Mediated Ferroptosis in the Spinal Cord of Rats

Ferroptosis is an inflammatory programmed cell death process that is dependent on iron deposition and lipid peroxidation. The P2X7 receptor not only is involved in the pain process but also is closely related to the onset of depression. Gallic acid (3,4,5-trihydroxybenzoic acid), which is naturally found in a variety of plants, exhibits anti-inflammatory, antioxidant, and analgesic effects. This study established a rat model with the comorbidity of chronic constrictive injury (CCI) plus chronic unpredictable mild stress (CUMS) to explore the role and mechanism of gallic acid in the treatment of pain and depression comorbidity. Our experimental results showed that pain and depression-like behaviors were more obvious in the chronic constriction injury (CCI) plus chronic unpredictable mild stimulation (CUMS) group than they were in the sham operation group, and the P2X7-reactive oxygen species (ROS) signaling pathway was activated. The tissue iron concentration was increased, and mitochondrial damage was observed in the CCI plus CUMS group. These results were alleviated with gallic acid treatment. Therefore, we speculate that gallic acid inhibits the ferroptosis of the spinal microglia by regulating the P2X7-ROS signaling pathway and relieves the behavioral changes in rats with comorbid pain and depression.

COP9 Signalosome Subunit 3 Restricts Neuroinflammatory Responses During Cerebral Ischemia/Reperfusion Injury Through Stabilizing Suppressor of Cytokine Signaling 3 Protein

BACKGROUND

The suppressor of cytokine signaling 3 (SOCS3) is a specific negative regulator of signal transducer and activator of transcription 3 (STAT3) signaling, which is predominantly activated to induce neuroinflammatory response in microglia and functions essential roles during cerebral ischemia-reperfusion (I/R) injury. Constitutive photomorphogenesis 9 (COP9) signalosome (CSN) is a signaling platform controlling protein stability by remodeling of cullin-RING ubiquitin ligases, which is recently reported to specifically recognize proteins with SOCS-box domains. However, whether SOCS3 is related to COP9 signalosome in neuroinflammation during cerebral I/R injury is completely unclear.

METHODS

Mice subjected to transient middle cerebral artery occlusion (MCAO) and reperfusion, and BV2 microglia cells treated with oxygen-glucose deprivation and reoxygenation (OGD/R) were used to mimic cerebral I/R injury. Western blot, qRTPCR, immunofluorescence, and co-Immunoprecipitation assays were performed to explore the regulatory mechanism of SOCS3 on neuroinflammation and the relationship of SOCS3 and COP9 signalosome during cerebral I/R injury.

RESULTS

SOCS3 expression is significantly upregulated in microglia during OGD/R treatment, and overexpression of SOCS3 suppresses OGD/R-induced STAT3 activation and inflammatory factor expression. Furthermore, we find that COP9 signalosome subunit 3 (CSN3) interacts with SOCS3 protein to enhance its stability, thereby resulting in restricting OGD/R-induced STAT3 activation and inflammatory response. Moreover, we find that knockdown of CSN3 evidently accelerates STAT3 activation, and aggravates cerebral I/R injury in vivo.

CONCLUSION

CSN3 restricts neuroinflammatory responses during cerebral I/R injury through stabilizing SOCS3 protein and indicates that CSN3 a potential therapeutic target for cerebral I/R injury.