Tanshinone IIA Suppresses Hypoxia-induced Apoptosis in Medial Vestibular Nucleus Cells Via a Skp2/BKCa Axis

Neurological disorders of COVID-19: insights to applications of natural products from plants and microorganisms

In addition to the typical respiratory manifestations, various disorders including involvement of the nerve system have been detected in COVID-19 ranging from 22 to 36%. Although growing records are focusing on neurological aspects of COVID-19, the pathophysiological mechanisms and related therapeutic methods remain obscure. Considering the increased concerns of SARS-CoV-2 potential for more serious neuroinvasion conditions, the present review attempts to focus on the neuroprotective effects of natural compounds as the principle source of therapeutics inhibiting multiple steps of the SARS-CoV-2 infection cycle. The great majority of the natural products with anti-SARS-CoV-2 activity mainly inhibit the attachment, entry and gene expression rather than the replication, assembly, or release. Although microbial-derived natural products comprise 38.5% of the known natural products with neuroprotective effects following viral infection, the neuroprotective potential of the majority of microorganisms is still undiscovered. Among natural products, chrysin, huperzine A, ginsenoside Rg1, pterostilbene, and terrein have shown potent in vitro neuroprotective activity and can be promising for new or repurpose drugs for neurological complications of SARS-CoV-2.

Protective Effect of Brassica rapa Polysaccharide against Acute High-Altitude Hypoxia-Induced Brain Injury and Its Metabolomics

Brassica rapa L., a traditional Tibetan medicine, has been wildly used for treating plateau disease. Polysaccharide is an important chemical component in B. rapa. The present study aimed to evaluate the effect of B. rapa polysaccharide (BRP) against acute high-altitude hypoxia (AHH) induced brain injury and its metabolic mechanism. The rats were randomly divided into six groups: control group, AHH group, Hongjingtian oral liquid group, and three BRP groups (38, 75, and 150 mg/kg/d). Serum levels of superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), oxidized glutathione (GSSG), and lactate dehydrogenase (LDH) were detected by commercial biochemical kits. Hippocampus and cortex histopathological changes were observed by H&E staining and Nissl staining. Neuronal apoptosis was observed by TUNEL staining. The protein and gene expression of Caspase-3, Bax, Bcl-2, p-PI3K, PI3K, p-Akt, Akt, HIF-1α, microRNA 210, ISCU1/2, and COX10 were detected by western blotting and qRT-PCR. Then, a brain metabolomics method based on UPLC-Q-Exactive-MS was performed to discover potential biomarkers and analyze metabolic pathways. It was found that BRP decreased levels of MDA, LDH, and GSSG, increased GSH and SOD, reduced the pathological changes, inhibited apoptosis, and activated the PI3K/Akt/HIF-1α signaling pathway as evidenced by increased phosphorylation of PI3K and Akt, enhanced protein expression of HIF-1α and gene levels of microRNA210, ISCU1/2, and COX10. Furthermore, 15 endogenous potential biomarkers were identified in the brain through metabolomics analysis. BRP can regulate 7 potential biomarkers and the corresponding metabolic pathways were mainly associated with pyruvate metabolism and glycolysis/gluconeogenesis. Collectively, BRP has a clear protective effect on AHH-induced brain injury and its mechanisms may be related to ameliorate oxidative stress injury, inhibit apoptosis by activating PI3K/Akt/HIF-1α signaling pathway, and reverse metabolic pathway disturbances.

Mechanism of Adipose-Derived Mesenchymal Stem Cell-Derived Extracellular Vesicles Carrying miR-21-5p in Hyperoxia-Induced Lung Injury

Hyperoxia-induced lung injury (HILI) tends to develop bronchopulmonary dysplasia. Adipose-derived mesenchymal stem cell (ADMSC)-derived extracellular vesicles (EVs) hold great promise in alleviating lung injury. This study explored the mechanism of ADMSC-EVs in HILI. ADMSC-EVs were isolated and identified. The murine and cell models of HILI were established. HILI mice and cells were pre-treated with ADMSC-EVs. The lung dry/wet ratio, pathological structure, apoptosis, and inflammation of HILI mice were measured. The viability, apoptosis, and oxidative stress of HILI cells were measured. The internalization of EVs in lung and cells was observed by fluorescence labeling. The binding relationships between miR-21-5p and SKP2, and Nr2f2 and C/EBPα were analyzed. The binding of SKP2 and Nr2f2 and the Nr2f2 ubiquitination level were detected. ADMSC-EVs exerted preventive effects on HILI mice, evidenced by reduced lung dry/wet ratio, inflammation, and apoptosis in HILI mice. In vitro, EVs enhanced HILI cell viability and reduced apoptosis, inflammation, and oxidative stress. EVs carried miR-21-5p into lung cells to upregulate miR-21-5p expression and thereby target SKP2. SKP2 bound to Nr2f2 and promoted its ubiquitination degradation. EVs inhibited the binding of Nr2f2 and C/EBPα and further suppressed C/EBPα transcription. Collectively, ADMSC-EVs carrying miR-21-5p alleviated HILI via the SKP2/Nr2f2/C/EBPα axis. Role and mechanism of adipose-derived mesenchymal stem cell-derived extracellular vesicles in hyperoxia-induced lung injury. ADMSC-EVs upregulated miR-21-5p expression in cells by carrying miR-21-5p into lung cells, thereby promoting the binding of miR-21-5p and SKP2 mRNA, inhibiting the expression of SKP2, reducing the ubiquitination level of Nr2f2, increasing the expression of Nr2f2, promoting the binding of Nr2f2 and the C/EBPα promoter, upregulating C/EBPα mRNA level, and eventually alleviating HILI.