Mesenchymal stem cell exosomes as nanotherapeutics for dry age-related macular degeneration.

Oxidative stress-induced retinal pigment epithelial (RPE) cell damage is a major factor in the pathogenesis of dry age-related macular degeneration (AMD). Although the therapeutic effect of mesenchymal stem cell (MSC) exosomes on dry AMD has been preliminarily discussed, the underlying mechanism has yet to be reported. Here, we demonstrate that MSC exosomes, acting as a nanodrug, can effectively reduce the incidence of dry AMD by regulating Nrf2/Keap1 signaling pathway. In the in vitro study, MSC exosomes relieved the damage of ARPE-19 cells, suppressed the activity of lactate dehydrogenase (LDH), decreased the level of reactive oxygen species (ROS) and upregulated the activity of superoxide dismutase (SOD). In the in vivo study, MSC exosomes were administered via intravitreal injection. MSC exosomes effectively protected RPE layer, photoreceptor outer segment/inner segment (OS/IS) layer and outer nuclear layer (ONL) from NaIO3-induced damage. Western blotting results showed that the ratio of Bcl-2/Bax was increased after pre-administration of MSC exosomes in both in vitro and in vivo studies. Moreover, MSC exosomes were found to upregulate the expressions of Nrf2, P-Nrf2, Keap1 and HO-1, while the antioxidant effect of MSC exosomes was blocked by ML385 (a Nrf2 inhibitor). Besides, immunofluorescence results showed that MSC exosomes upregulated the expression of P-Nrf2 in the nucleus compared to the oxidant group. These results indicate that MSC exosomes protect RPE cells from oxidative damage by regulating Nrf2/Kepa1 signaling pathway. In conclusion, MSC exosomes are promising nanotherapeutics for the treatment of dry AMD.

Successful Treatment With Intrathecal and Intravenous Polymyxin B-Based Combination Against MDR Acinetobacter baumannii Meningitis in Pediatric Patient: A Case Report.

Background: Nosocomial meningitis with multidrug-resistant (MDR) or extensively drug-resistant (XDR) Acinetobacter baumannii is a life-threatening complication in neurosurgery. Treatment of these infections is challenging because of poor penetration of the available antibiotics into the cerebrospinal fluid (CSF). Intrathecal (ITH) or intraventricular (IVT) administration of antibiotics is increasingly used as the last treatment option against MDR/XDR Gram-negative bacteria meningitis not responding to intravenous (IV) regimens. However, pertinent data in pediatric patients is scarce. Case Presentation: A 14-year-old male patient developed meningitis from an MDR strain of A. baumannii following endoscopic endonasal resection of craniopharyngioma. Despite a combination therapy involving IV tigecycline, we observed clinical and bacteriologic failure. The patient was then successfully treated with an ITH and IV polymyxin B-based combination. Quantification of tigecycline and polymyxin B in CSF was performed with two-dimensional high-performance liquid chromatography (2D-HPLC) and HDLC coupled with tandem mass spectrometry (HPLC-MS/MS), respectively. Adverse drug reactions (neurotoxicity and skin hyperpigmentation), probably induced by polymyxin B, were acceptable and reversible. Conclusions: The case illustrates ITH and IV Polymyxin B-based combination is an optimal therapeutic option against MDR A. baumannii meningitis in this pediatric patient. In the future, real-time PK/PD data obtained from patients during ITH/IVT polymyxin B therapy should be required to optimize polymyxin use with maximal efficacy and minimal adverse effects.

Hyperoside Protected Against Oxidative Stress-Induced Liver Injury via the PHLPP2-AKT-GSK-3ß Signaling Pathway In Vivo and In Vitro.

Hyperoside, isolated from Drosera rotundifolia L., seeds of Cuscuta chinensis Lam., or Hypericum perforatum L., originally showed to possess an antifungal and antibacterial activity, while recently showed the protective effects against oxidative stress-induced liver injury. This study investigated such a protective effect of hyperoside and the underlying molecular mechanisms in vitro and in carbon tetrachloride (CCl4)-injured rat livers. The data showed that hyperoside was able to prevent the oxidative stress-induced liver morphological changes and CCl4-induced rat liver injury. Hyperoside reversed the decrease of superoxidase dismutase (SOD) level and the increase of malondialdehyde (MDA) level in vivo. Moreover, hyperoside regulated the pleckstrin homology (PH) domain leucine-rich repeat protein phosphatase 2 (PHLPP2)-protein kinase B (AKT)-glycogen synthase kinase 3ß (GSK-3ß) signaling pathway in tert-butylhydroquinone (t-BHP)-treated liver cells, e.g., Hyperoside reduced PHLPP2 expression to activate AKT phosphorylation, induce GSK-3ß phosphorylation, and then increased nuclear factor erythroid-2-related factor 2 (Nrf2) nuclear translocation, reduced nuclear translocation of phosphorylated Fyn, and promoted heme oxygenase-1 (HO-1) expression in vivo and in vitro. In contrast, siRNA-mediated knockdown of PHLPP2 expression enhanced hyperoside-mediated activation of the AKT-GSK-3ß kinase pathway in liver cells. In conclusion, the present study demonstrated that hyperoside could protect against oxidative stress-induced liver injury by regulating the PHLPP2-AKT-GSK-3ß signaling pathway in vivo and in vitro.

A metabolic exposure-oriented network regulation strategy for the identification of effective combination in the extract of Ginkgo biloba L.

Nowadays, network pharmacology-based methods were increasing proposed to screen synergistic or combinatorial compounds from herbal medicines (HMs), while these researches mainly focused on structural prediction or experiment-based interaction between single compound and target protein. The proportion of each chemical in the nature and their metabolic process was ignored, which might decide an optimized composition for their synergistic effect. To exact the effective combination of HMs, a metabolic distribution-oriented network regulation strategy was developed for the identification of effective combination. Firstly, comprehensive chemical profiling and metabolic exposure of HMs in a pathological state were conducted. Then the effective combination for HMs was screened by combining network regulation and the metabolic exposure level of HMs. Finally, with the extract of Ginkgo biloba (EGB) as a case, a combination of 12 active compounds was found for treating ischemia stroke, showing bioactivity equivalence with original herb. The results also indicated that beside the well-known ginkgolides and flavonoids, trace compounds might also play an important role of the holistic effect of EGB. This method can be used as an alternative for effective combination screening.

Ginkgolide K attenuates neuronal injury after ischemic stroke by inhibiting mitochondrial fission and GSK-3ß-dependent increases in mitochondrial membrane permeability.

Ginkgolide K (GK) belongs to the ginkgolide family of natural compounds found in Ginkgo biloba leaves, which have been used for centuries to treat cerebrovascular and cardiovascular diseases. We evaluated the protective effects of GK against neuronal apoptosis by assessing its ability to sustain mitochondrial integrity and function. Co-immunoprecipitation showed that Drp1 binding to GSK-3ß was increased after an oxygen-glucose deprivation/reperfusion (OGD/R) insult in cultured neuroblastoma cells. This induced Drp1 and GSK-3ß translocation to mitochondria and mitochondrial dysfunction, which was attenuated by GK. GK also reduced mitochondrial fission by increasing Drp1 phosphorylation at Ser637 and inhibiting mitochondrial Drp1 recruitment. In addition, GK exposure induced GSK-3ß phosphorylation at Ser9 and enhanced the interaction between adenine nucleotide translocator (ANT) and p-GSK-3ß. This interaction suppressed the interaction between ANT and cyclophilin D (CypD), which inhibited mitochondrial permeability transition pore (mPTP) opening. Similarly, suppression of mitochondrial fission by Mdivi-1 also inhibited GSK-3ß-induced mPTP opening. Treating mice with GK prevented GSK-3ß and Drp1 translocation to mitochondria and attenuated mitochondrial dysfunction after middle cerebral artery occlusion. We therefore propose that by inhibiting mitochondrial fission and attenuating mPTP opening, GK exerts neuroprotective effects that mitigate or prevent neuronal damage secondary to ischemic stroke.

Succinate-induced neuronal mitochondrial fission and hexokinase II malfunction in ischemic stroke: Therapeutical effects of kaempferol.

Mitochondrial dysfunction is known as one of causative factors in ischemic stroke, leading to neuronal cell death. The present work was undertaken to investigate whether succinate induces neuron apoptosis by regulating mitochondrial morphology and function. In neurons, oxygen-glucose deprivation induced succinate accumulation due to the reversal of succinate dehydrogenase (SDH) activation, leading to mitochondrial fission. Kaempferol inhibited mitochondrial fission and maintained mitochondrial HK-II through activation of Akt, and thereby protected neurons from succinate-mediated ischemi injury. Knockdown of Akt2 with siRNA diminished the effect of kaempferol, indicating that kaempferol suppressed dynamin-related protein 1 (Drp1) activation and promoted HK-II mitochondrial binding dependently on Akt. Moreover, we demonstrated that kaempferol potentiated autophagy during oxygen and glucose deprivation, contributing to protecting neuron survival against succinate insult. In vivo, oral administration of kaempferol in mice attenuated the infract volume after ischemic and reperfusion (I/R) injury and reproduced the similar mitochondrial protective effect in the brain infract area. This study indicates that succinate accumulation plays a pivotal role in I/R injury-induced neuronal mitochondrial dysfunction, and suggests that modulation of Drp1 phosphorylation might be potential therapeutic strategy to protect neuron mitochondrial integrity and treat ischemic stroke.