Acute ischemic stroke (AIS) is a global cerebrovascular disease with high disability and mortality, which has no effective therapy. Studies have demonstrated that astrocyte-derived exosomes (ADEXs) provided neuroprotection in experimental stroke models. Nevertheless, the role of exosomes derived from oxygen-glucose-deprivation/reoxygenation-stimulated astrocytes (OGD/R-stimulated astrocytes; OGD/R-ADEXs) in AIS remains largely unknown. Here, we found that OGD/R-ADEXs significantly reduced OGD/R-induced neuronal death and promoted neuronal autophagy. These effects were reversed when astrocytes were pretreated with GW4869, an exosome secretion inhibitor, or when hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) was knocked down. Neuroprotection was also observed during treatment with OGD/R-ADEXs in vivo. Further studies showed that Nampt, played a vital effect in the regulation of autophagy, was significantly increased in OGD/R-ADEXs. Knockdown of Nampt in astrocytes abolished the above-mentioned effects of OGD/R-ADEXs. Mechanistically, Nampt increased autophagy and decreased cell death by modulating AMPK/mTOR signaling, which recognized as a key signaling pathway of autophagy after AIS. Collectively, these results showed that Nampt released by OGD/R-ADEXs ameliorated acute ischemic stroke during neuronal injury by targeting AMPK/mTOR signaling to induce autophagy. Our study revealed a new key factor in the secretion of exosomes by OGD/R astrocytes, which regulated autophagy and induced neuroprotection in a mouse stroke model.

Our previous studies have shown that berberine can improve the nerve function deficits in ischemic stroke by inhibiting inflammation. The cellular communication between astrocytes and neurons via exosomes might affect neurological function after ischemic stroke, which plays a vital role in the therapy of ischemic stroke. The present study focused on the effects of exosomes released from astrocytes induced by the glucose and oxygen deprivation model with berberine pretreatment (BBR-exos) treatment for ischemic stroke and its regulatory mechanism. Oxygen-glucose-deprivation/Reoxygenation (OGD/R)-treated primary cells were used to mimic cerebral ischemia/reperfusion conditions in vitro. With the treatment of BBR-exos and exosomes released from primary astrocytes induced by the glucose and oxygen deprivation model (OGD/R-exos), the cell viability was detected. C57BL/6J mice were used to establish middle cerebral artery occlusion/reperfusion (MCAO/R) model. The anti-neuroinflammation effects of BBR-exos and OGD/R-exos were evaluated. Subsequently, the key miRNA in BBR-exos was identified by exosomal miRNA sequencing and cell validation. miR-182-5p mimic and inhibitors were provided to verify the effects in inflammation. Finally, the binding sites between miR-182-5p and Rac1 were predicted online and verified by using a dual-luciferase reporter assay. BBR-exos and OGD/R-exos both improved the decreased activity of OGD/R-induced neurons, and decreased the expression of IL-1β, IL-6 and TNF-α (all P ＜ 0.05), which reduced neuronal injury and inhibited neuroinflammation in Vitro. And BBR-exos showed better effects (P ＜ 0.05). The same effect has been verified in vivo experiments: BBR-exos and OGD/R-exos both reduced cerebral ischemic injury and inhibited neuroinflammation in MCAO/R mice (all P ＜ 0.05). Likewise, BBR-exos showed better effects (P ＜ 0.05). The exosomal miRNA sequencing results showed that miR-182-5p was highly expressed in BBR-exos and inhibited neuroinflammation by targeting Rac1 (P ＜ 0.05). BBR-exos can carry miR-182-5p to injured neurons and inhibit the expression of Rac1, which could inhibit neuroinflammation and improved brain injury after ischemic stroke.

Introduction: Huangkui capsule (HKC) is made from the ethanol extract of Abelmoschus manihot (L.) Medik [Malvaceae; abelmoschi corolla] and received approval from the China Food and Drug Administration (Z19990040) in 1999. Currently, HKC is used for treatment of the patients with diabetic nephropathy (DN) in China. The bioactive chemical constituents in HKC are total flavonoids of A. manihot (L.) Medik (TFA). The present study aims to identify the primary flavonoid metabolites in HKC and TFA and their metabolism fates in db/db mice, the animal model for the study of type 2 diabetes and DN.Methods: HKC (0.84 g/kg/d) and TFA (0.076 g/kg/d) or vehicle were respectively administered daily via oral gavage in db/db mice for 4 weeks. The metabolism fate of the main metabolites of HKC in serum, liver, kidney, heart, jejunum, colon, jejunal contents, colonic contents, and urine of db/db mice were analyzed with a comprehensive metabolite identification strategy.Results and Discussion: In db/db mice administered with HKC and TFA, 7 flavonoid prototypes and 38 metabolites were identified. The related metabolic pathways at Phases I and II reactions included dehydroxylation, deglycosylation, hydrogenation, methylation, glucuronidation, sulphation, and corresponding recombined reactions. Quercetin, isorhamnetin, quercetin sulphate, quercetin monoglucuronide, and isorhamnetin monoglucuronide presented a high exposure in the serum and kidney of db/db mice. Thereby, the present study provides a pharmacodynamic substance basis for better understanding the mechanism of A. manihot (L.) Medik for medication of DN.