Dexmedetomidine attenuates oxygen-glucose deprivation/ reperfusion-induced inflammation through the miR-17-5p/ TLR4/ NF-κB axis.

BACKGROUND: Dexmedetomidine (DEX) is a selective agonist of α2-adrenergic receptors with anesthetic activity and neuroprotective benefits. However, its mechanism of action at the molecular level remains poorly defined. In this study, we investigated the protective effects of DEX on oxygen-glucose deprivation/ reperfusion (OGD/R)-induced neuronal apoptosis in PC12 cells, and evaluated its underlying mechanism(s) of neuroprotection and anti-inflammation. METHODS: An OGD/R model in PC12 cells was established. PC12 cells were cultured and divided into control, OGD/R, and OGD/R + DEX (1 µM, 10 µM, 50 µM) groups. Cell apoptosis was analyzed by flow cytometry and expression profiles were determined by qRT-PCR, western blot analysis, and enzyme linked immunosorbent assays (ELISA). The interaction between miRNA and its downstream targets was evaluated through luciferase reporter assays. RESULTS: DEX significantly decreased apoptosis rates and inhibited interleukin 1 beta (IL-1ß), tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6) release (P < 0.05). While expression of the pro-apoptotic proteins Bax and Caspase-3 was down-regulated, expression of Bcl-2 was upregulated in a dose-dependent manner (P < 0.05). Interestingly, miR-17-5p expression was down-regulated in the OGD/R group (compared to controls). Toll-like receptor 4 (TLR4), a key regulator of nuclear factor kappa-B (NF-κB) signaling, was identified as a novel target of miR-17-5p in PC12 cells. miR-17-5p expression was upregulated in the OGD/R + DEX group, suppressing TLR4 expression and reducing the secretion of proinflammatory cytokines. CONCLUSION: DEX inhibits OGD/R-induced inflammation and apoptosis in PC12 cells by increasing miR-17-5p expression, downregulating TLR4, and inhibiting NF-κB signaling.

Dexmedetomidine alleviates sevoflurane-induced neurotoxicity via mitophagy signaling.

Dexmedetomidine, a class of α2-adrenergic agonist, was reported to exert a neuroprotective effect on sevoflurane-induced neurotoxicity. However, the specific mechanisms have not been fully clarified yet. The aim of our study is to uncover the role of dexmedetomidine in sevoflurane-induced neurotoxicity. The rats pretreated with dexmedetomidine and/or Rapamycin 3-Methyladenine were housed in a box containing 30% O2, 68% N2 and 2% sevoflurane for 4 h for anesthesia. 24 h after drug injection, Morris water maze test was used to evaluate rats' learning and memory ability. Hematoxylin & eosin (H&E) staining was adopted to analyze the pathological changes of hippocampus. TUNEL assay was performed to measure cell apoptosis in hippocampus. Immunofluorescent assay was utilized to detect HSP60 level. The protein levels of LC3I, LC3II, Beclin-1, CypD, VDAC1 and Tom20 were examined by western blot. 5 weeks after drug injection, Morris water maze test was used to evaluate rats' learning and memory ability again. Dexmedetomidine alleviated sevoflurane-induced nerve injury and the impairment of learning and memory abilities. Additionally, dexmedetomidine inhibited sevoflurane-induced cell apoptosis in hippocampus. In mechanism, dexmedetomidine activated mitophagy to mitigate neurotoxicity by enhancing LC3II/LC3I ratio, HSP60, Beclin-1, CypD, VDAC1 and Tom20 protein levels in hippocampus. Dexmedetomidine alleviates sevoflurane-induced neurotoxicity via mitophagy signaling, offering a potential strategy for sevoflurane-induced neurotoxicity treatment.

Single or multiple encounters of general anaesthesia do not cause any cognitive dysfunction: Findings from a retrospective population-based, case-control study.

General anesthesia and surgery have been associated with acute cognitive impairment in several elderly individuals. Present study was conducted to determine whether the general anaesthesia exposure and cognitive dysfunction are linked or not. This is a China-based retrospective, population-based and case-control study. Using Chinese database inhabitants of Shenyang, China, incident cases detected with cognitive abnormalities between January 2007 and December 2012 were identified. With respective to every incident case, age- and gender-matched control subject was chosen among the general population pool of Shenyang inhabitants who were not having cognitive anomalies in the year. Medical records were scrutinized to examine the exposures to surgical procedures necessitating anesthesia after 45-years of age. We examined 577 cases of cognition-impaired (dementia) patients, every incident case with a conforming control subject. Among the cognitive impaired patients, 414 (71.7%) underwent 821 surgical operations needing general anesthesia exposure; of the controls, 404 (70%) underwent 833 surgical procedures. The present study found that general anaesthetic agents encounter was not markedly associated with cognitive anomalies (odds ratio, 0.87; 95% CI, 0.71-1.09; P=0.29). Moreover, no substantial relation was observed when the anaesthetic agents encounter was measured as number of surgical operations (odds ratios (OR), 0.83, 0.89, and 1.0 for 1, 2-3, and 4 exposures, correspondingly, matched with none; P=0.52). Our present work witnessed no substantial link between surgical procedures requiring single or multiple general anesthesia exposure post 45-years of age and cognitive dysfunction.

Dexmedetomidine facilitates the expression of nNOS in the hippocampus to alleviate surgery-induced neuroinflammation and cognitive dysfunction in aged rats.

Postoperative cognitive dysfunction (POCD) is a common complication in the postoperative nervous system of elderly patients. Surgery-induced hippocampal neuroinflammation is closely associated with POCD. Dexmedetomidine (DEX) is an effective α2-adrenergic receptor agonist, which can reduce inflammation and has neuroprotective effects, thereby improving postoperative cognitive dysfunction. However, the mechanism by which DEX improves POCD is currently unclear. The purpose of the present study was therefore to identify how DEX acted on POCD. Male Sprague Dawley rats with exposed carotid arteries were used to mimic POCD. Locomotor activity was accessed by the open field test and the Morris water maze was performed to estimate spatial learning, memory and cognitive flexibility. Following animal sacrifice, the hippocampus was collected and cell apoptosis was determined by terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling staining. Subsequently, the expression of apoptosis-related proteins Bax, Bcl-2, cleaved caspase-3 and cleaved caspase-9 was determined by western blotting and the concentrations of TNF-α, IL-6, IL-1ß and IL-10 were measured in serum using ELISA. Nitric oxide synthase and neuronal nitric oxide synthase activities in the hippocampus were also measured. The T lymphocyte subsets were analyzed by flow cytometry to evaluate the immune function in each group. Compared with the surgery group, DEX ameliorated POCD by improving cognitive dysfunctions and immune function loss, and attenuated neuroinflammation and neuronal apoptosis.

CircRNA 001372 Reduces Inflammation in Propofol-Induced Neuroinflammation and Neural Apoptosis through PIK3CA/Akt/NF-κB by miRNA-148b-3p.

OBJECTIVES: To investigate effects of circular RNA (circRNA) 001372 and its antagonist miRNAs-148b-3p on propofol-induced neurotoxicity and neuroinflammation in rat brain and pheochromocytoma cells. METHODS: Sprague Dawley rats in propofol model group (n = 6) were intraperitoneal injected with propofol (50 mg/kg) and in sham control group (n = 6) without any treatment. Twenty-four h later, brain tissues were acquired during pentobarbital anesthesia. PC-12 cells were transfected with or without circRNA001372 mimics, circRNA001372 inhibitor, negative mimics or miRNA-148b-3p for 48 h and then treated with propofol (100 µM) for 48 h. Quantitative reverse transcription PCR and gene chips were used for detecting levels of circRNA001372, Haemotoxylin and Eosin staining for cell morphology, MTT for cell viability, flow cytometry for apoptosis, enzyme-linked immunosorbent assay for lactate dehydrogenase (LDH), interleukin-1ß (IL-1ß), IL-6, IL17 and IL-18, and Western blots for phosphoinositide 3-kinase (PI3K), Akt, phosphorylated Akt, and nuclear factor (NF) κB, dual-light luminescent reporter gene assay for luciferase reporter. RESULTS: The propofol anesthesia in rats decreases levels of circRNA001372 and increases levels of cytokines including IL-1ß, IL-6, IL17 and IL-18, resulting in the neurocyte damage in brain. In propofol-treated PC-12 cells, the inhibition of circRNA001372 increases apoptosis and cell damage makers, including LDH, IL-1ß, IL-6, IL17, IL-18, resulting in the reduction of cell viability, which have been revised after over-expression of circRNA001372. MiRNA-148b-3p reduces circRNA001372-incresed PI3K and pAKt levels but enhances the circRNA001372-decreased NFκB level. CONCLUSIONS: CircRNA001372 suppresses propofol-induced neurotoxicity and neuroinflammation through PI3K/Akt/NF-κB signaling pathway in rat brain and neurocytes. MiRNA-148b-3p antagonizes the effects of circRNA001372.

Isoflurane Suppresses Proliferation, Migration, and Invasion and Facilitates Apoptosis in Colorectal Cancer Cells Through Targeting miR-216.

Objective: Surgery is the first line treatment of colorectal cancer (CRC). Anesthetic isoflurane may improve outcomes of cancer surgery. Herein, we investigated the effects of isoflurane on malignant behaviors of CRC cells and its underlying therapeutic target. Methods: SW620 and HCT116 CRC cells were exposed to a series of concentrations of isoflurane. CCK-8 assay was utilized for determination of the optimal concentration of isoflurane. Under treatment with isoflurane, proliferation, migration, and invasion were separately assessed via clone formation and transwell assays. Apoptotic levels were observed via flow cytometry and expression of Bax, Bcl-2, and Caspase3 proteins was quantified through western blot. MiR-216 expression was detected in isoflurane-induced SW620 and HCT116 cells by RT-qPCR. Following transfection with miR-216 mimic, malignant biological behaviors were examined in isoflurane-treated SW620 and HCT116 cells. Results: 40 µM isoflurane distinctly restrained proliferative, migrated, and invasive capacities and elevated apoptotic levels in SW620 and HCT116 cells. Up-regulation of miR-216 was found in CRC cells. Its expression was suppressed by isoflurane. MiR-216 mimic ameliorated the reduction in proliferation, migration, and invasion and the increase in apoptosis for 40 µM isoflurane-induced SW620 and HCT116 cells. Conclusion: Isoflurane, a promising drug of CRC, may suppress malignant biological behaviors of tumor cells. Furthermore, miR-216 is an underlying target of isoflurane. Thus, isoflurane could be adopted for CRC treatment.

Recent advances in studies of molecular hydrogen in the treatment of pancreatitis.

Pancreatitis is an inflammatory disease of the pancreas characterized by acinar cell injury and is associated with the abnormal release of trypsin, which results in high mortality due to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). The inflammatory response, impaired autophagic flux, endoplasmic reticulum stress (ERS) and their interactions are involved in the development of pancreatitis. Molecular hydrogen (H2) is a novel antioxidant that possesses the features of selective scavenging of oxygen free radicals and nontoxic metabolites and has been shown to be efficacious for treating infection, injury, tumors, ischemia-reperfusion organ injury, metabolic disease and several other diseases. Recent studies have found that H2 is also useful in the treatment of pancreatitis, which may be related to the mechanism of antioxidative stress, anti-inflammation, anti-apoptosis, regulation of immunity and regulation of molecular pathways. This review focuses on the pathogenesis of pancreatitis and the research progress and potential mechanisms of H2 against pancreatitis to provide theoretical bases for future research and clinical application of H2 therapy for pancreatitis.

Pivotal role of endothelial cell autophagy in sepsis.

Sepsis is a fatal organ dysfunction resulting from a disordered host response to infection. Endothelial cells (ECs) are usually the primary targets of inflammatory mediators in sepsis; damage to ECs plays a pivotal part in vital organ failure. In recent studies, autophagy was suggested to play a critical role in the ECs injury although the mechanisms by which ECs are injured in sepsis are not well elucidated. Autophagy is a highly conserved catabolic process that includes sequestrating plasma contents and transporting cargo to lysosomes for recycling the vital substrates required for metabolism. This pathway also counteracts microbial invasion to balance and retain homeostasis, especially during sepsis. Increasing evidence indicates that autophagy is closely associated with endothelial function. The role of autophagy in sepsis may or may not be favorable depending upon conditions. In the present review, the current knowledge of autophagy in the process of sepsis and its influence on ECs was evaluated. In addition, the potential of targeting EC autophagy for clinical treatment of sepsis was discussed.

[Role of autophagy in pancreatic injury in sepsis].

Sepsis is a life-threatening systemic inflammatory response syndrome (SIRS) caused by the host's maladjustment response to infection, which eventually leads to septic shock and multiple organ failure. Pancreatic injury was found to be an important pathological change in sepsis. Autophagy is a crucial way to maintain the normal metabolism of cell substances and energy, which plays an important role in many diseases. Recent studies have found that autophagy plays a dual role in pancreatic injury in sepsis. Moderate autophagy can protect the pancreas and reduce the injury, while excessive autophagy can cause apoptosis-related autophagic cell death and aggravate the pancreatic injury. In sepsis, activated nuclear factor-κB (NF-κB) has a promoting effect on autophagy, and lysosome associated membrane protein (LAMP) degradation can result in impaired autophagy flux and aggravate pancreatic injury. The exploration of the mechanism of autophagy in pancreatic injury of sepsis will help to restore the normal autophagy function, so as to find a new target for the treatment of pancreatic injury of sepsis.