Astrocyte-derived lactate aggravates brain injury of ischemic stroke in mice by promoting the formation of protein lactylation.

Aim: Although lactate supplementation at the reperfusion stage of ischemic stroke has been shown to offer neuroprotection, whether the role of accumulated lactate at the ischemia phase is neuroprotection or not remains largely unknown. Thus, in this study, we aimed to investigate the roles and mechanisms of accumulated brain lactate at the ischemia stage in regulating brain injury of ischemic stroke. Methods and Results: Pharmacological inhibition of lactate production by either inhibiting LDHA or glycolysis markedly attenuated the mouse brain injury of ischemic stroke. In contrast, additional lactate supplement further aggravates brain injury, which may be closely related to the induction of neuronal death and A1 astrocytes. The contributing roles of increased lactate at the ischemic stage may be related to the promotive formation of protein lysine lactylation (Kla), while the post-treatment of lactate at the reperfusion stage did not influence the brain protein Kla levels with neuroprotection. Increased protein Kla levels were found mainly in neurons by the HPLC-MS/MS analysis and immunofluorescent staining. Then, pharmacological inhibition of lactate production or blocking the lactate shuttle to neurons showed markedly decreased protein Kla levels in the ischemic brains. Additionally, Ldha specific knockout in astrocytes (Aldh1l1 CreERT2; Ldha fl/fl mice, cKO) mice with MCAO were constructed and the results showed that the protein Kla level was decreased accompanied by a decrease in the volume of cerebral infarction in cKO mice compared to the control groups. Furthermore, blocking the protein Kla formation by inhibiting the writer p300 with its antagonist A-485 significantly alleviates neuronal death and glial activation of cerebral ischemia with a reduction in the protein Kla level, resulting in extending reperfusion window and improving functional recovery for ischemic stroke. Conclusion: Collectively, increased brain lactate derived from astrocytes aggravates ischemic brain injury by promoting the protein Kla formation, suggesting that inhibiting lactate production or the formation of protein Kla at the ischemia stage presents new therapeutic targets for the treatment of ischemic stroke.

Metabolomics Analysis of Electroacupuncture Pretreatment Induced Neuroprotection on Mice with Ischemic Stroke.

The brain metabolic changes caused by the interruption of blood supply are the initial factors of brain injury in ischemic stroke. Electroacupuncture (EA) pretreatment has been shown to protect against ischemic stroke, but whether its neuroprotective mechanism involves metabolic regulation remains unclear. Based on our finding that EA pretreatment significantly alleviated ischemic brain injury in mice by reducing neuronal injury and death, we performed a gas chromatography-time of flight mass spectrometry (GC-TOF/MS) to investigate the metabolic changes in the ischemic brain and whether EA pretreatment influenced these changes. First, we found that some glycolytic metabolites in the normal brain tissues were reduced by EA pretreatment, which may lay the foundation of neuroprotection for EA pretreatment against ischemic stroke. Then, 6[Formula: see text]h of cerebral ischemia-induced brain metabolic changes, especially the enhanced glycolysis, were partially reversed by EA pretreatment, which was manifested by the brain levels of 11 of 35 up-regulated metabolites and 18 of 27 down-regulated metabolites caused by cerebral ischemia significantly decreasing and increasing, respectively, due to EA pretreatment. A further pathway analysis showed that these 11 and 18 markedly changed metabolites were mainly involved in starch and sucrose metabolism, purine metabolism, aspartate metabolism, and the citric acid cycle. Additionally, we found that EA pretreatment raised the levels of neuroprotective metabolites in both normal and ischemic brain tissues. In conclusion, our study revealed that EA pretreatment may attenuate the ischemic brain injury by inhibiting glycolysis and increasing the levels of some neuroprotective metabolites.

Incremental prognostic value of multichamber deformation imaging and renal function status to predict adverse outcome in heart failure with reduced ejection fraction.

AIMS: Deformation imaging, particularly of left-sided heart, is fast becoming an essential tool in clinical cardiology. However, data are scant regarding the value of biventricular and bi-atrial deformation in association with comorbidities in heart failure with reduced left ventricular ejection fraction (HFREF). METHODS AND RESULTS: Forty-nine subjects (72 ± 13 years; 28 male) with HFREF and 14 age-matched controls underwent deformation imaging including LV global longitudinal strain (LVGLS%), right ventricular strain (RVS%), and left atrial reservoir strain (LARS%). Standard echo parameters included LVEF%, E/E' ratio, and pulmonary artery systolic pressure (PASP). Mean ± SD of LVEF, LVGLS%, and RVS% were 31% ± 8%, 7% ± 3%, and 17% ± 7%, respectively, and were significantly lower compared with controls (all P < .0001). Over a follow-up period of 4.2 years, 24% of patients died and 48% had a composite outcome of death and heart failure hospitalization. In the logistic regression model, taking the composite of death and heart failure hospitalization as a dichotomous variable, RVS%, E/E' ratio, and PASP were the only significant univariate predictors of adverse outcome (R2  = .68, all P < .05). In the multivariate model, however, only PASP predicted adverse outcome. PASP also had the largest AUC (0.8) in the ROC analysis. A creatinine level of >88 µmol/L (SCREAT) and a cutoff value of LA reservoir strain (LARS %) at <16.7% provided the best sensitivity (86%) and specificity (40%) with an odds ratio of 3.8. In the Kaplan-Meier survival estimate, LARS%-SCREAT predicted all-cause mortality and HF hospitalization. CONCLUSION: Multichamber deformation imaging along with renal function and PASP could best predict adverse outcome in HFREF.