A novel antagonist of TRPM2 and TRPV4 channels: Carvacrol.

The overload cytosolic free Ca2+ (cCa2+) influx-mediated excessive generation of oxidative stress in the pathophysiological conditions induces neuronal and cellular injury via the activation of cation channels. TRPM2 and TRPV4 channels are activated by oxidative stress, and their specific antagonists have not been discovered yet. The antioxidant and anti-Covid-19 properties of carvacrol (CARV) were recently reported. Hence, I suspected possible antagonist properties of CARV against oxidative stress (OS)/ADP-ribose (ADPR)-induced TRPM2 and GSK1016790A (GSK)-mediated TRPV4 activations in neuronal and kidney cells. I investigated the antagonist role of CARV on the activations of TRPM2 and TRPV4 in SH-SY5Y neuronal, BV-2 microglial, and HEK293 cells. The OS/ADPR and GSK in the cells caused to increase of TRPM2/TRPV4 current densities and overload cytosolic free Ca2+ (cCa2+) influx with an increase of mitochondrial membrane potential, cytosolic (cROS), and mitochondrial (mROS) ROS. The changes were not observed in the absence of TRPM2 and TRPV4 or the presence of Ca2+ free extracellular buffer and PARP-1 inhibitors (PJ34 and DPQ). When OS-induced TRPM2 and GSK-induced TRPV4 activations were inhibited by the treatment of CARV, the increase of cROS, mROS, lipid peroxidation, apoptosis, cell death, cCa2+ concentration, caspase -3, and caspase -9 levels were restored via upregulation of glutathione and glutathione peroxidase. In conclusion, the treatment of CARV modulated the TRPM2 and TRPV4-mediated overload Ca2+ influx and may provide an avenue for protecting TRPM2 and TRPV4-mediated neurodegenerative diseases associated with the increase of mROS and cCa2+. The possible TRPM2 and TRPV4 blocker action of carvacrol (CARV) via the modulation oxidative stress and apoptosis in the SH-SY5Y neuronal cells. TRPM2 is activated by DNA damage-induced (via PARP-1 activation) ADP-ribose (ADPR) and reactive oxygen species (ROS) (H2O2), although it is inhibited by nonspecific inhibitors (ACA and 2-APB). TRPV4 is activated by the treatments of GSK1016790A (GSK), although it is inhibited by a nonspecific inhibitor (ruthenium red, RuRe). The treatment of GSK induces excessive generation of ROS. The accumulation of free cytosolic Ca2+ (cCa2+) via the activations of TRPM2 and TRPV4 in the mitochondria causes the increase of mitochondrial membrane depolarization (ΔΨm). In turn, the increase of ΔΨm causes the excessive generation of ROS. The TRPM2 and TRPV4-induced the excessive generations of ROS result in the increase of apoptosis and cell death via the activations of caspase -3 (Casp-3) and caspase -9 (Casp-9) in the neuronal cells, although their oxidant actions decrease the glutathione (GSH) and glutathione peroxidase (GSHPx) levels. The oxidant and apoptotic adverse actions of TRPM2 and TRPV4 are modulated by the treatment of CARV.

Endoplasmic reticulum stress and NF-kB activation in SARS-CoV-2 infected cells and their response to antiviral therapy.

Unfolded protein response (UPR) and endoplasmic reticulum (ER) stress are aspects of SARS-CoV-2-host cell interaction with proposed role in the cytopathic and inflammatory pathogenesis of this viral infection. The role of the NF-kB pathway in these cellular processes remains poorly characterized. When investigated in VERO-E6 cells, SARS-CoV-2 infection was found to markedly stimulate NF-kB protein expression and activity. NF-kB activation occurs early in the infection process (6 hpi) and it is associated with increased MAPK signaling and expression of the UPR inducer IRE-1α. These signal transduction processes characterize the cellular stress response to the virus promoting a pro-inflammatory environment and caspase activation in the host cell. Inhibition of viral replication by the viral protease inhibitor Nelfinavir reverts all these molecular changes also stimulating c-Jun expression, a key component of the JNK/AP-1 pathway with important role in the IRE-1α-mediated transcriptional regulation of stress response genes with anti-inflammatory and cytoprotection function. The present study demonstrates that UPR signaling and its interaction with cellular MAPKs and the NF-kB activity are important aspects of SARS-CoV-2-host cell interaction that deserve further investigation to identify more efficient therapies for this viral infection.

14-Deoxy-11,12-didehydroandrographolide inhibits apoptosis in influenza A(H5N1) virus-infected human lung epithelial cells via the caspase-9-dependent intrinsic apoptotic pathway which contributes to its antiviral activity.

Influenza A virus (IAV) infection represents a global health challenge. Excavating antiviral active components from traditional Chinese medicine (TCM) is a promising anti-IAV strategy. Our previous studies have demonstrated that 14-deoxy-11,12-didehydroandrographolide (DAP), a major ingredient of a TCM herb called Andrographis paniculata, shows anti-IAV activity that is mainly effective against A/chicken/Hubei/327/2004 (H5N1), A/duck/Hubei/XN/2007 (H5N1), and A/PR/8/34 (H1N1) in vitro and in vivo. However, the underlying anti-IAV molecular mechanism of DAP needs further investigation. In the present work, we found that DAP can significantly inhibit the apoptosis of human lung epithelial (A549) cells infected with A/chicken/Hubei/327/2004 (H5N1). After DAP treatment, the protein expression levels of cleaved PARP, cleaved caspase-3, and cleaved caspase-9, and the activities of caspase-3 and caspase-9 in H5N1-infected A549 cells were all obviously downregulated. However, DAP had no inhibitory effect on caspase-8 activity and cleaved caspase-8 production. Meanwhile, the efficacy of DAP in reducing the apoptotic cells was lost after using the inhibitor of caspase-3 or caspase-9 but remained intact after the caspase-8 inhibitor treatment. Moreover, DAP efficiently attenuated the dissipation of mitochondrial membrane potential, suppressed cytochrome c release from the mitochondria to the cytosol, and decreased the protein expression ratio of Bax/Bcl-2 in the mitochondrial fraction. Furthermore, the silencing of caspase-9 reduced the yield of nucleoprotein (NP) and disabled the inhibitory ability of DAP in NP production in A549 cells. Overall results suggest that DAP exerts its antiviral effects by inhibiting H5N1-induced apoptosis on the caspase-9-dependent intrinsic/mitochondrial pathway, which may be one of the anti-H5N1 mechanisms of DAP.