Dexmedetomidine facilitates autophagic flux to promote liver regeneration by suppressing GSK3ß activity in mouse partial hepatectomy.

INTRODUCTION: Dexmedetomidine (DEX), a highly selective α2-adrenergic receptor agonist, is widely used for sedation and anesthesia in patients undergoing hepatectomy. However, the effect of DEX on autophagic flux and liver regeneration remains unclear. OBJECTIVES: This study aimed to determine the role of DEX in hepatocyte autophagic flux and liver regeneration after PHx. METHODS: In mice, DEX was intraperitoneally injected 5 min before and 6 h after PHx. In vitro, DEX was co-incubated with culture medium for 24 h. Autophagic flux was detected by LC3-II and SQSTM1 expression levels in primary mouse hepatocytes and the proportion of red puncta in AML-12 cells transfected with FUGW-PK-hLC3 plasmid. Liver regeneration was assessed by cyclinD1 expression, Edu incorporation, H&E staining, ki67 immunostaining and liver/body ratios. Bafilomycin A1, si-GSK3ß and Flag-tagged GSK3ß, α2-ADR antagonist, GSK3ß inhibitor, AKT inhibitor were used to identify the role of GSK3ß in DEX-mediated autophagic flux and hepatocyte proliferation. RESULTS: Pre- and post-operative DEX treatment promoted liver regeneration after PHx, showing 12 h earlier than in DEX-untreated mice, accompanied by facilitated autophagic flux, which was completely abolished by bafilomycin A1 or α2-ADR antagonist. The suppression of GSK3ß activity by SB216763 and si-GSK3ß enhanced the effect of DEX on autophagic flux and liver regeneration, which was abolished by AKT inhibitor. CONCLUSION: Pre- and post-operative administration of DEX facilitates autophagic flux, leading to enhanced liver regeneration after partial hepatectomy through suppression of GSK3ß activity in an α2-ADR-dependent manner.

Calorie restriction mimetic, resveratrol, attenuates hepatic ischemia and reperfusion injury through enhancing efferocytosis of macrophages via AMPK/STAT3/S1PR1 pathway.

Calorie restriction (CR) mimetic, resveratrol (RSV), has the capacity of promoting phagocytosis. However, its role in hepatic ischemia and reperfusion injury (HIRI) remains poorly understood. This study aimed to investigate the effect of RSV on alleviating HIRI and explore the underlying mechanisms. RSV was intraperitoneally injected in mice HIRI model, while RSV was co-incubated with culture medium for 24 h in RAW 264.7 cells and kupffer cells. Macrophage efferocytosis was assessed by immunostaining of PI and F4/80. The clearance of apoptotic neutrophils in the liver was determined by immunostaining of Ly6-G and cleaved-caspase-3. HE staining, Suzuki's score, serum levels of ALT, AST, TNF-α and IL-1ß were analyzed to evaluate HIRI. The efferocytosis inhibitor, Cytochalasin D, was utilized to investigate the effect of RSV on HIRI. Western blot was employed to measure the levels of AMPKα, phospho-AMPKα, STAT3, phospho-STAT3 and S1PR1. SiSTAT3 and inhibitors targeting AMPK, STAT3 and S1PR1, respectively, were used to confirm the involvement of AMPK/STAT3/S1PR1 pathway in RSV-mediated efferocytosis and HIRI. RSV facilitated the clearance of apoptotic neutrophils and attenuated HIRI, which was impeded by Cytochalasin D. RSV boosted macrophage efferocytosis by up-regulating the levels of phospho-AMPKα, phospho-STAT3 and S1PR1, which was reversed by AMPK, STAT3 and S1PR1 inhibitors, respectively. Inhibition of STAT3 suppressed RSV-induced clearance of apoptotic neutrophils and exacerbated HIRI. CR mimetic, RSV, alleviates HIRI by promoting macrophages efferocytosis through AMPK/STAT3/S1PR1 pathway, providing valuable insights into the mechanisms underlying the protective effects of CR on attenuating HIRI.

MLKL Protects Pulmonary Endothelial Cells in Acute Lung Injury.

The role of autophagy in pulmonary microvascular endothelial cells (PMVECs) is controversial in LPS-induced acute lung injury (ALI). Mixed lineage kinase domain-like pseudokinase (MLKL) has recently been reported to maintain cell survival by facilitating autophagic flux in response to starvation rather than its well-recognized role in necroptosis. Using a mouse PMVEC and LPS-induced ALI model, we showed that in PMVECs, MLKL was phosphorylated (p-MLKL) and autophagic flux was accelerated at the early stage of LPS stimulation (1-3 h), manifested by increases in concentrations of lipidated MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 ß; LC3-II), decreases in concentrations of SQSTM1/p62 (sequestosome 1), and fusion of the autophagosome and lysosome by pHluorin-mKate2-human LC3 assay, which were all reversed by either MLKL inhibitor or siRNA MLKL. In mice, the inhibition of MLKL increased vascular permeability and aggravated mouse ALI upon 3-hour LPS stimulation. The p-MLKL induced by short-term LPS formed multimers to facilitate the closure of the phagophore by HaloTag-LC3 autophagosome completion assay. The charged multivesicular body protein 2A (CHMP2A) is essential in the process of phagophore closure into the nascent autophagosome. In agreement with the p-MLKL change, CHMP2A concentrations markedly increased during 1-3-hour LPS stimulation. CHMP2A knockdown blocked autophagic flux upon LPS stimulation, whereas CHMP2A overexpression boosted autophagic flux and attenuated mouse ALI even in the presence of MLKL inhibitor. We propose that the activated MLKL induced by short-term LPS facilitates autophagic flux by accelerating the closure of the phagophore via CHMP2A, thus protecting PMVECs and alleviating LPS-induced ALI.

Salvinorin A moderates postischemic brain injury by preserving endothelial mitochondrial function via AMPK/Mfn2 activation.

Salvinorin A (SA) is a highly selective kappa opioid receptor (KOR) agonist that has significant protective effects on cerebrovascular function after ischemic stroke, but its underlying mechanism is still unclear. This study aimed to investigate whether KOR activation improves the morphology and function of intracellular mitochondria to protect endothelial cells after cerebral ischemia. A transient ischemic brain damage was generated by establishing middle cerebral artery occlusion (MCAO) model in male Sprague-Dawley rats and oxygen glucose deprivation (OGD) model in human brain microvascular endothelial cells (HBMECs). In vivo findings revealed that SA significantly reduced the infarct size, brain edema and Evans blue effusion after MCAO. In vitro findings revealed that SA improved the cell viability and decreased the apoptotic rates in HBMECs OGD model. SA also protected membrane potential and morphology of mitochondria, reduced the ROS level after OGD. SA function was blocked by KOR inhibitor norbinaltorphimine (NB). SA upregulated the phosphorylation levels of AMPK, and Mfn2 expression. Our findings suggest that SA effectively mitigated focal cerebral ischemic injury by activating KOR which potentially preserved mitochondrial function by up-regulating AMPK/Mfn2 in endothelial cells.

Enhancement in Tonically Active Glutamatergic Inputs to the Rostral Ventrolateral Medulla Contributes to Neuropathic Pain-Induced High Blood Pressure.

Neuropathic pain increases the risk of cardiovascular diseases including hypertension with the characteristic of sympathetic overactivity. The enhanced tonically active glutamatergic input to the rostral ventrolateral medulla (RVLM) contributes to sympathetic overactivity and blood pressure (BP) in cardiovascular diseases. We hypothesize that neuropathic pain enhances tonically active glutamatergic inputs to the RVLM, which contributes to high level of BP and sympathetic outflow. Animal model with the trigeminal neuropathic pain was induced by the infraorbital nerve-chronic constriction injury (ION-CCI). A significant increase in BP and renal sympathetic nerve activity (RSNA) was found in rats with ION-CCI (BP, n = 5, RSNA, n = 7, p < 0.05). The concentration of glutamate in the RVLM was significantly increased in the ION-CCI group (n = 4, p < 0.05). Blockade of glutamate receptors by injection of kynurenic acid into the RVLM significantly decreased BP and RSNA in the ION-CCI group (n = 5, p < 0.05). In two major sources (the paraventricular nucleus and periaqueductal gray) for glutamatergic inputs to the RVLM, the ION-CCI group (n = 5, p < 0.05) showed an increase in glutamate content and expression of glutaminase 2, vesicular glutamate transporter 2 proteins, and c-fos. Our results suggest that enhancement in tonically active glutamatergic inputs to the RVLM contributes to neuropathic pain-induced high blood pressure.

Activation of Endocannabinoid Receptor 2 as a Mechanism of Propofol Pretreatment-Induced Cardioprotection against Ischemia-Reperfusion Injury in Rats.

Propofol pretreatment before reperfusion, or propofol conditioning, has been shown to be cardioprotective, while its mechanism is unclear. The current study investigated the roles of endocannabinoid signaling in propofol cardioprotection in an in vivo model of myocardial ischemia/reperfusion (I/R) injury and in in vitro primary cardiomyocyte hypoxia/reoxygenation (H/R) injury. The results showed that propofol conditioning increased both serum and cell culture media concentrations of endocannabinoids including anandamide (AEA) and 2-arachidonoylglycerol (2-AG) detected by LC-MS/MS. The reductions of myocardial infarct size in vivo and cardiomyocyte apoptosis and death in vitro were accompanied with attenuations of oxidative injuries manifested as decreased reactive oxygen species (ROS), malonaldehyde (MDA), and MPO (myeloperoxidase) and increased superoxide dismutase (SOD) production. These effects were mimicked by either URB597, a selective endocannabinoids degradation inhibitor, or VDM11, a selective endocannabinoids reuptake inhibitor. In vivo study further validated that the cardioprotective and antioxidative effects of propofol were reversed by selective CB2 receptor antagonist AM630 but not CB1 receptor antagonist AM251. We concluded that enhancing endogenous endocannabinoid release and subsequent activation of CB2 receptor signaling represent a major mechanism whereby propofol conditioning confers antioxidative and cardioprotective effects against myocardial I/R injury.

Neuroprotective effect of picroside II in brain injury in mice.

Various types of brain injury which led to the damage of brain tissue structure and neurological dysfunction continues to be the major causes of disability and mortality. Picroside II (PII) possesses a wide range of pharmacological effects and has been proved to ameliorate ischemia and reperfusion injury of kidney and brain. However, critical questions remain about other brain injuries. We investigated the protective effect of PII in four well-characterized murine models of brain injury. Models showed a subsequent regional inflammatory response and oxidative stress in common, which might be improved by the administration of PII (20 mg/kg). Meanwhile, a series of morphological and histological analyses for reinforcement was performed. In traumatic, ischemic and infectious induced injuries, it was observed that the survival rate, apoptosis related proteins, Caspase-3, and the expression of acute inflammatory cytokines (IL-1ß, IL-6 and TNF-α) were significantly alleviated after PII injection, but PII treatment alone showed no effect on them as well. The western blot results indicated that TLR4 and NF-κB were clearly downregulated with PII administration. In conclusion, our results suggested that PII with a recommended concentration of 20 mg/kg could provide neuroprotective effects against multi-cerebral injuries in mice by suppressing the over-reactive inflammatory responses and oxidative stress and attenuating the damage of brain tissue for further neurological recovery.

Lugrandoside attenuates LPS-induced acute respiratory distress syndrome by anti-inflammation and anti-apoptosis in mice.

This study aimed to investigate the protective effects and specific mechanisms of lugrandoside (LG) on lipopolysaccharides (LPS)-induced acute respiratory distress syndrome (ARDS). LG is a novel phenylpropanoid glycoside with many biological properties, isolated from the culinary leaves of Digitalis lutea L. and Digitalis grandiflora Miller. The primary indicators to assess the lung injury were infiltration of inflammatory cells; pulmonary edema; expression of proinflammatory cytokines, cyclo-oxygenase 2, and intracellular adhesion molecule 1; activation of nuclear factor-κB pathways; and cellular apoptosis. The results showed that LG evidently alleviated the inflammatory response, decreased the apoptosis of alveolar macrophages, and improved the lung injury in mice with LPS-induced ARDS. In conclusion, LG improved LPS-induced ARDS by anti-inflammation and anti-apoptosis and might be a promising pharmacological therapy for ARDS.

The non-Geldanamycin Hsp90 inhibitors enhanced the antifungal activity of fluconazole.

The molecular chaperone heat shock protein 90 (Hsp90) is highly conserved in eukaryotes and facilitates the correct folding, productive assembly and maturation of a diverse cellular proteins. In fungi, especially the most prevalent human fungal pathogen Candida albicans, Hsp90 influences development and modulates drug resistance. Here, we mainly explore the effect of non-Geldanamycin Hsp90 inhibitor HSP990 on the activity of fluconazole (FLC) against Candida albicans and investigate the underlying mechanism. We demonstrate that HSP990 has potent synergistic antifungal activity with FLC against FLC-resistant C. albicans through the checkerboard microdilution assay,agar diffusion tests and time-kill curves, and shows low cytotoxicity to human umbilical vein endothelial cells. Further study shows that the activity of FLC against C. albicans biofilm formation in vitro is significantly enhanced when used in combination with HSP990. In a murine model of disseminated candidiasis, the therapeutic efficacy of FLC is also enhanced by the pharmacological inhibition of C. albicans Hsp90 function with HSP990. Thus, the combined use of small molecule compound and existing antifungal drugs may provide a potential therapeutic strategy for fungal infectious disease.