Background: Microglial-mediated neuroinflammation plays an important role in vascular dementia, and modulating neuroinflammation has emerged as a promising treatment target. Nicotinamide adenine dinucleotide (NAD⁺) shows anti-inflammatory and anti-oxidant effects in many neurodegenerative disease models, but its role in the chronic cerebral hypoperfusion (CCH) is still unclear. Methods: The bilateral common carotid artery occlusion (BCCAO) was performed to establish CCH models in Sprague-Dawley rats. The rats were given daily intraperitoneal injection of NAD⁺ for 8 weeks. The behavioral test and markers for neuronal death and neuroinflammation were analyzed. Mitochondrial damage and ROS production in microglia were also assessed. RNA-seq was performed to investigate the mechanistic pathway changes. For in vitro studies, Sirt1 was overexpressed in BV2 microglial cells to compare with NAD⁺ treatment effects on mitochondrial injury and neuroinflammation. Results: NAD⁺ administration rescued cognitive deficits and inhibited neuroinflammation by protecting mitochondria and decreasing ROS production in CCH rats. Results of mechanistic pathway analysis indicated that the detrimental effects of CCH might be associated with decreased gene expression of PPAR-γ co-activator1α (PGC-1α) and its upstream transcription factor Sirt1, while NAD⁺ treatment markedly reversed their decrease. In vitro study confirmed that NAD⁺ administration had protective effects on hypoxia-induced neuroinflammation and mitochondrial damage, as well as ROS production in BV2 microglia via Sirt1/PGC-1α pathway. Sirt1 overexpression mimicked the protective effects of NAD⁺ treatment in BV2 microglia. Conclusions: NAD⁺ ameliorated cognitive impairment and dampened neuroinflammation in CCH models in vivo and in vitro, and these beneficial effects were associated with mitochondrial protection and ROS inhibition via activating Sirt1/PGC-1α pathway.

Background: Diabetes mellitus (DM) and chronic cerebral hypoperfusion(CCH)are both risk factors for cognitive impairment. However, whether DM and CCH can synergistically promote cognitive impairment and the related pathological mechanisms remain unknown. Methods: To investigate the effect of DM and CCH on cognitive function, rats fed with high-fat diet (HFD) and injected with low-dose streptozotocin (STZ) followed by bilateral common carotid artery occlusion (BCCAO) were induced to mimic DM and CCH in vivo and mouse BV2 microglial cells were exposed to hypoxia and/or high glucose to mimic CCH complicated with DM pathologies in vitro. To further explore the underlying mechanism, TREM-2-specific small interfering RNA and TREM-2 overexpression lentivirus were used to knock out and overexpress TREM-2, respectively. Results: Cognitive deficits, neuronal cell death, neuroinflammation with microglial activation, and TREM-2-MAPK signaling were enhanced when DM was superimposed on CCH both in vivo and in vitro. Manipulating TREM-2 expression levels markedly regulated the p38 MAPK signaling and the inflammatory response in vitro. TREM-2 knockout intensified while TREM-2 overexpression suppressed the p38 MAPK signaling and subsequent pro-inflammatory mediator production under high glucose and hypoxia condition. Conclusions: These results suggest that TREM-2 negatively regulates p38 MAPK-mediated inflammatory response when DM was synergistically superimposed on CCH and highlight the importance of TREM-2 as a potential target of immune regulation in DM and CCH.

BACKGROUND: Whether it is effective and safe to extend the time window of intravenous thrombolysis up to 24 hours after the last known well is unknown. We aimed to determine the efficacy and safety of tenecteplase in Chinese patients with acute ischemic stroke due to large/medium vessel occlusion within an extended time window. METHODS: Patients with ischemic stroke presenting 4.5 to 24 hours from the last known well, with a favorable penumbral profile and an associated large/medium vessel occlusion, were randomized 1:1 to either 0.25 mg/kg tenecteplase or the best medical treatment. A favorable penumbral profile was defined as a hypoperfusion lesion volume to infarct core volume ratio >1.2, with an absolute volume difference >10 mL, and an ischemic core volume 50% of the involved ischemic territory. Secondary outcomes included recanalization, infarct growth, major neurological improvements, change in the National Institutes of Health Stroke Scale score, hemorrhagic transformation within 24 to 48 hours, systemic bleeding at discharge, and modified Rankin Scale (score 0–1, score 0–2, score 5–6, and modified Rankin Scale distribution) at 90 days. The comparison of the primary outcome between groups was conducted using modified Poisson regression with a log-link function and robust error variance, adjusted for time from the last known well to randomization, the site of vessel occlusion, and planned endovascular treatment. RESULTS: Among 224 enrolled patients, 111 were assigned to receive tenecteplase and 113 to receive the best medical treatment (including 23% [n=26] of participants who received intravenous tissue-type plasminogen activator). The mean (SD) age of the tenecteplase group and the best medical treatment group was 64.2 (10.4) and 63.6 (11.0) years old, with 72.1% (n=80) and 70.8% (n=80) male enrolled, respectively. A proportion of 54.9% (n=123) of patients were transferred to the catheter room for preplanned endovascular treatment. The primary outcome occurred in 33.3% (n=37) of the tenecteplase group versus 10.8% (n=12) in the best medical treatment group (adjusted relative risk, 3.0 [95% CI, 1.6–5.7]; P =0.001). Tenecteplase significantly increased the recanalization rate compared with the best medical treatment (35.8% [n=39] versus 14.3% [n=16], adjusted relative risk, 2.5 [95% CI, 1.4–4.4]; P =0.002). There were no significant differences in clinical efficacy outcomes or rates of hemorrhagic transformation between the groups. CONCLUSIONS: Administered at a dose of 0.25 mg/kg intravenously, tenecteplase increased reperfusion without symptomatic intracranial hemorrhage in patients with ischemic stroke selected by imaging in late-time window treatment but did not change clinical outcomes at 90 days. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04516993.

Neuroinflammation plays critical roles in vascular dementia (VaD), the second leading cause of dementia, which can be induced by chronic cerebral hypoperfusion (CCH). NLRP3 inflammasome-induced pyroptosis, the inflammatory programmed cell death, has been reported to contribute to the development of VaD. ChemR23 is a G protein-coupled receptor that has emerging roles in regulating inflammation. However, the role of ChemR23 signalling in NLRP3 inflammasome-induced pyroptosis in CCH remains elusive. In this study, a CCH rat model was established by permanent bilateral common carotid artery occlusion (BCCAO) surgery. Eight weeks after the surgery, the rats were intraperitoneally injected with the ChemR23 agonist Resolvin E1 (RvE1) or chemerin-9 (C-9). Additionally, primary rat hippocampal neurons and SH-SY5Y cells were adopted to mimic CCH injury in vitro. Our results showed that the levels of ChemR23 expression were decreased from the 8^th week after BCCAO, accompanied by significant cognitive impairment. Further analysis revealed that CCH induced neuronal damage, synaptic injury and NLRP3-related pyroptosis activation in hippocampal neurons. However, pharmacologic activation of ChemR23 with RvE1 or C-9 counteracted these changes. In vitro experiments also showed that ChemR23 activation prevented primary neuron pyroptosis induced by chronic hypoxia. In addition, manipulating ChemR23 expression markedly regulated NLRP3 inflammasome-induced neuronal pyroptosis through PI3K/AKT/Nrf2 signalling in SH-SY5Y cells under hypoglycaemic and hypoxic conditions. Collectively, our data demonstrated that ChemR23 activation inhibits NLRP3 inflammasome-induced neuronal pyroptosis and improves cognitive function via the PI3K/AKT/Nrf2 signalling pathway in CCH models. ChemR23 may serve as a potential novel therapeutic target to treat CCH-induced cognitive impairment.