Hypoxic preconditioned mesenchymal stem cells ameliorate rat brain injury after cardiopulmonary resuscitation by suppressing neuronal pyroptosis.

Cardiac arrest (CA) can result in cerebral ischaemia-reperfusion injury and poor neurological outcomes. While bone marrow-derived mesenchymal stem cells (BMSCs) have been shown to have protective effects in brain ischaemic disease, their efficacy can be reduced by the poor oxygen environment. In this study, we investigated the neuroprotective effects of hypoxic preconditioned BMSCs (HP-BMSCs) and normoxic BMSCs (N-BMSCs) in a cardiac arrest rat model by examining their ability to ameliorate cell pyroptosis. The mechanism underlying the process was also explored. Cardiac arrest was induced in rats for 8 min and surviving rats received 1 × 106 normoxic/hypoxic BMSCs or PBS via intracerebroventricular (ICV) transplantation. Neurological function of rats was evaluated using neurological deficit scores (NDSs) and examined for brain pathology. Serum S100B and neuron-specific enolase (NSE) levels and cortical proinflammatory cytokines were measured to evaluate brain injury. Pyroptosis-related proteins in the cortex after cardiopulmonary resuscitation (CPR) were measured using western blotting and immunofluorescent staining. Transplanted BMSCs were tracked using bioluminescence imaging. Results showed significantly better neurological function and neuropathological damage after transplantation with HP-BMSCs. In addition, HP-BMSCs reduced levels of pyroptosis-related proteins in the rat cortex after CPR and significantly reduced levels of biomarkers for brain injury. Mechanistically, HP-BMSCs alleviated brain injury by reducing the expressions of HMGB1, TLR4, NF-κB p65, p38 MAPK and JNK in the cortex. Our study demonstrated that hypoxic preconditioning could enhance the efficacy of BMSCs in alleviating post-resuscitation cortical pyroptosis. This effect may be related to the regulation of the HMGB1/TLR4/NF-κB, MAPK signalling pathways.

[Role of caspase-8 in stem cell transplantation alleviates rat cerebral cortex apoptosis after cardiopulmonary resuscitation].

OBJECTIVE: To explore the effects and the possible mechanism of bone marrow mesenchymal stem cell (BMMSC) transplantation on apoptosis in rats cerebral cortex after cardiac arrest/cardiopulmonary resuscitation (CA/CPR). METHODS: The BMMSC of 2 Sprague-Dawley (SD) rats aged 4-5weeks was extracted, and the 3rd passage was used in experimental study. Eighteen Sprague-Dawley (SD) rats were divided into sham group, model group (CA/CPR group) and intervention group (BMMSC group) according to random number table method, with 6 rats in each group. CPR was performed 6 minutes after asphyxia induced CA. In sham group, CA was not induced except performing general surgical procedure. At 1 hour after return of spontaneous circulation (ROSC), 0.5 mL phosphate buffered saline (PBS) was injected through tail vein in CA/CPR group. 2×109/L green fluorescence protein (GFP)-labeled BMMSC was injected through tail vein 1 hour after ROSC in BMMSC group. Neurological deficit score (NDS) were assessed in every group at 72 hours after CPR. Serum S100 calcium binding protein B (S100B) levels were assayed by enzyme linked immunosorbent assay (ELISA). Distribution of BMMSC in brain was observed under a fluorescent microscope. Apoptosis rate in cerebral cortex was assayed by TdT-mediated dUTP nick-end labeling (TUNEL). Western blotting was performed to measure the expression levels of active aspartic acid specific cysteine proteinase (caspase-8 and caspase-9) in cerebral cortex. RESULTS: At 3 days after CPR, compared with sham group, the apoptosis of cerebral cortex cells was increased and brain damage was obvious, NDS score was decreased significantly (56.6±5.5 vs. 80.0±0.0, P < 0.05), and serum S100B was increased markedly (ng/L: 45.1±4.7 vs. 19.1±1.4, P < 0.05), apoptosis rate of cerebral cortex cells increased significantly [(52.9±11.8)% vs. (10.1±1.5)%, P < 0.05], the level of active caspase-8 expression in cerebral cortex was significantly higher (caspase-8/GAPDH: 0.689±0.047 vs. 0.330±0.108, P < 0.05), and there was no significant difference in active caspase-9 protein expression (caspase-9/GAPDH: 0.428±0.014 vs. 0.426±0.021, P > 0.05) in CA/CPR group. After BMMSC transplantation, GFP-labeled BMMSC were primarily detected in cerebral cortex, compared with CA/CPR group, the apoptosis of cerebral cortex cells and brain injury were significantly improved in BMMSC group, NDS score increased significantly (70.6±2.1 vs. 56.6±5.5, P < 0.05), serum S100B levels in BMMSC group were lower (ng/L: 32.0±3.2 vs. 45.1±4.7, P < 0.05), apoptosis rate of cerebral cortex cells decreased significantly [(31.1±3.4)% vs. (52.9±11.8)%, P < 0.05], and the active caspase-8 expression in cerebral cortex in BMMSC group was significantly decreased (caspase-8/GAPDH: 0.427±0.067 vs. 0.689±0.047, P < 0.05). The active caspase-9 expression in cerebral cortex in BMMSC group and CA/CPR group were not significantly different (caspase-9/GAPDH: 0.431±0.022 vs. 0.428±0.014, P > 0.05). CONCLUSIONS: BMMSC transplantation can alleviate rat brain damage after CA/CPR possibly by inhibiting the death receptor mediated apoptotic pathway to inhibit the apoptosis of brain cells.

LncGBP9 knockdown alleviates myocardial inflammation and apoptosis in mice with acute viral myocarditis via suppressing NF-κB signaling pathway.

BACKGROUND: Myocardial inflammation and apoptosis are key processes in coxsackievirus B3 (CVB3)-induced acute viral myocarditis (AVMC). Accumulating evidence reveals the essential roles of long noncoding RNAs (lncRNAs) in the pathogenesis of AVMC. Here, we aimed to evaluate the biological functions of a novel lncRNA guanylate-binding protein 9 (lncGBP9) in AVMC progression and further explore its underlying mechanisms. METHODS: Initially, mouse models of AVMC were constructed by CVB3 infection. The expression and localization of lncGBP9 in heart tissues were analyzed using RT-qPCR and FISH. Adeno-associated virus serotype 9 (AAV9)-mediated lncGBP9 knockdown was then employed to clarify its roles in survival, cardiac function, and myocardial inflammation and apoptosis. Moreover, the mRNA and protein levels of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1ß) were detected by RT-qPCR and ELISA, and the regulation of lncGBP9 knockdown on the NF-κB signaling pathway was investigated by Western blotting. Using an in vitro model of HL-1 cardiomyocytes exposed to CVB3 infection, the effects of lncGBP9 knockdown on cell viability, inflammation, and apoptosis were further evaluated in vitro. RESULTS: Increased lncGBP9 expression was detected in the heart tissues of AVMC mice and CVB3-infected HL-1 cells, and was mainly located in the cytoplasm. Knockdown of lncGBP9 remarkably alleviated the severity of AVMC in CVB3-infected mice, as verified by improved cardiac function, and reduced myocardial inflammation and apoptosis. Additionally, lncGBP9 knockdown suppressed the NF-κB signaling pathway and consequently reduced productions of pro-inflammatory cytokines in vivo. In vitro functional assays further confirmed that lncGBP9 knockdown promoted cell viability, inhibited cell apoptosis, and reduced pro-inflammatory cytokines release in CVB3-infected HL-1 cells through suppressing NF-κB activation. CONCLUSIONS: Collectively, lncGBP9 knockdown exerts anti-inflammatory and anti-apoptotic effects in CVB3-induced AVMC, which may be mediated in part via NF-κB signaling pathway. These findings highlight lncGBP9 as an attractive target for therapeutic interventions.