Mild Hypothermia Alleviates Complement C5a-Induced Neuronal Autophagy During Brain Ischemia-Reperfusion Injury After Cardiac Arrest

Akt/mTOR Pathway Agonist SC79 Inhibits Autophagy and Apoptosis of Oligodendrocyte Precursor Cells Associated with Neonatal White Matter Dysplasia

White matter dysplasia (WMD) in preterm infants due to intrauterine inflammation is caused by excessive apoptosis of oligodendrocyte precursor cells (OPCs). In recent years, studies have found that excessive autophagy and apoptosis are highly interconnected and important in infection and inflammatory diseases in general. Therefore, in this study, we aimed to confirm whether regulation of autophagy by using the Akt phosphorylation agonist SC79 can inhibit abnormal apoptosis of OPCs and promote myelin maturation and white matter development in neonatal rats with WMD. We investigated the effect of inflammation on oligodendrocyte development in P0 neonatal rats by intracerebellar injection of LPS, and collected brain tissue at P2 and P5. Immunohistochemical and immunofluorescence staining were used to evaluate white matter damage, while immunofluorescence staining, terminal deoxynucleotidyl transferase dUTP nick end labeling analysis (TUNEL), and western blotting were used to evaluate autophagy and apoptosis. First, we observed that white matter development was arrested and white matter fiber maturation was impaired in LPS-inflicted pups compared with those in the sham-operated group. Second, treatment with SC79 reduced the levels of LC3II, caspase 3, caspase 9, and Bax/Bcl-2 and increased the levels of p62, p-Akt, and p-mTOR in the brain tissue of neonatal rats. Finally, SC79 treatment inhibited OPC apoptosis by increasing the binding of Beclin 1 to Bcl-2, which promoted OPC differentiation and maturation. However, the opposite results were observed after rapamycin administration. Taken together, our results suggest that SC79 can inhibit the abnormal apoptosis of OPCs caused by excessive autophagy through the Akt/mTOR pathway and that SC79 is a potential therapeutic agent for WMD in preterm infants.

Effects of temperature control on hyperthermia-related cardiac dysfunction in a porcine model of cardiac arrest

The outcome of cardiac arrest is worse when there is fever after spontaneous circulation is restored (ROSC). The purpose of this study was to investigate the mechanism of post-ROSC cardiac dysfunction after hyperthermia treatment and the effects of temperature control. Twenty-four male Bama minipigs were randomized into 3 groups (8 per group): CPR + controlled normothermia (CN), CPR + hyperthermia (HT), and CPR + therapeutic mild hypothermia (TMH). Defibrillation was given to pigs with ventricular fibrillation after 8 min of untreated fibrillation. Subsequently, these animals received the post-ROSC treatments of hyperthermia (38 °C), controlled normothermia (37 °C) or hypothermia (33 °C) according to the groups. Hemodynamic parameters, left ventricular ejection fraction, blood samples and myocardial tissues were assessed. At 24 h after the post-ROSC treatments, the pigs treated with hyperthermia showed increments in heart rate and plasma cardiac troponin I, and decreases in mean arterial pressure, cardiac index, and left ventricular ejection fraction, compared to those with the controlled normothermia pigs. However, the deterioration of the above parameters can be attenuated by TMH. The pigs in the TMH group also had a reduced percentage of apoptotic cardiomyocytes, an increased anti-apoptotic Bcl-2/Bax ratio and a decreased caspase-3 activity in myocardium, as compared with both controlled normothermia and hyperthermia pigs. In conclusion, hyperthermia is associated with a worse myocardial dysfunction. TMH improves hyperthermia-induced myocardial dysfunction by attenuating apoptosis in a porcine model of cardiac arrest.

Cornin protects against cerebral ischemia/reperfusion injury by preventing autophagy via the PI3K/Akt/mTOR pathway

Background

Ischemia stroke is the leading cause of disability, which is a consequence of vascular occlusion. The purpose of this study is to investigate the effect of cornin which is isolated from the fruit of Verbena officinalis L, against astrocytes autophagy induced by cerebral ischemia/reperfusion (CI/R) injury in vitro and in vivo and its potential mechanism.

Methods

Cornin at dose of 2.5, 5 and 10 mg/kg were intravenously injected to MCAO rats at 15 min after reperfusion. The infarction volume, blood–brain barrier (BBB), neurological severity score (mNSS), and autophagy related protein were used to evaluated the protective effects and potential mechanism of cornin in autophagy with or without phosphoinositide-3 kinase (PI3K)inhibitor LY294002 and mammalian target of rapamycin (mTOR) small interfering RNA (siRNA) at 24 h after CI/R injury. The potential protective effects and mechanism of cornin at concention of 10 ~ 1000 nM were also evaluated in oxygen glucose deprivation/reperfusion (OGD/R) in U87 cells.

Results

The results suggest that cornin at dose of 5 or 10 mg/kg significantly reduce the cerebral infarction volume and blood–brain barrier (BBB) leakage, and improve neurological recovery in MCAO rats. Cleaved caspase-3 and Bax levels were significantly decreased, while B-cell lymphoma-2 (Bcl-2) and the apoptosis regulator ratio (Bcl-2/Bax) were markedly increased when treated with 2.5–10 mg/kg cornin. The obvious decreased expressions of glial fibrillary acidic protein (GFAP), myosin-like BCL2 interacting protein (Beclin-1) and microtubule-associated protein light chain 3 II (LC3-II) and increased of neuronal nuclei (NeuN), sequestosome-1 (p62), phosphorylated mTOR (p-mTOR), and phosphorylated Akt (p-Akt) were observed in MCAO rats treated with 10 mg/kg cornin, which was counteracted by LY294002. The expression of autophagy-related proteins with or without LY294002 and mTOR siRNA presented the similar results as in vitro in OGD/R in U87 cells.

Conclusions

These results indicate that cornin improved neurological recovery after cerebral ischemia injury by preventing astrocytes autophagy induced by CI/R via the PI3K/Akt/mTOR signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-022-00620-3.