Journal of Cerebral Blood Flow and Metabolism最新文献

Endothelial blood-brain barrier (BBB) dysfunction is critical in the pathophysiology of brain injury. Rho-associated protein kinase (ROCK) activation disrupts BBB integrity in the injured brain. We aimed to test the efficacy of a novel ROCK2 inhibitor in preserving the BBB after acute brain injury. We characterized the molecular structure and pharmacodynamic and pharmacokinetic properties of a novel selective ROCK2 inhibitor, NRL-1049, and its first metabolite, 1-hydroxy-NRL-1049 (referred to as NRL-2017 hereon) and tested the efficacy of NRL-1049 on the BBB integrity in rodent models of acute brain injury. Our data show that NRL-1049 and NRL-2017 both inhibit ROCK activity and are 44-fold and 17-fold more selective towards ROCK2 than ROCK1, respectively. When tested in a mouse model of cortical cryoinjury, NRL-1049 significantly attenuated the increase in water content. Interestingly, 60% of the mice in the vehicle arm developed seizures within 2 hours after cryoinjury versus none in the NRL-1049 arm. In spontaneously hypertensive rats, NRL-1049 attenuated the dramatic surge in Evans Blue extravasation compared with the vehicle arm after transient middle cerebral artery occlusion. Hemorrhagic transformation was also reduced. We show that NRL-1049, a selective ROCK2 inhibitor, is a promising drug candidate to preserve the BBB after brain injury.

Ubiquitin C-terminal hydrolase L1 (UCHL1) is a neuronal protein important in maintaining axonal integrity and motor function and may be important in the pathogenesis of many neurological disorders. UCHL1 may ameliorate acute injury and improve recovery after cerebral ischemia. In the current study, the hypothesis that UCHL1's hydrolase activity underlies its effect in maintaining axonal integrity and function is tested after ischemic injury. Hydrolase activity was inhibited by treatment with a UCHL1 hydrolase inhibitor or by employing knockin mice bearing a mutation in the hydrolase active site (C90A). Ischemic injury was induced by oxygen-glucose deprivation (OGD) in brain slice preparations and by transient middle cerebral artery occlusion (tMCAO) surgery in mice. Hydrolase activity inhibition increased restoration time and decreased the amplitude of evoked axonal responses in the corpus callosum after OGD. Mutation of the hydrolase active site exacerbated white matter injury as detected by SMI32 immunohistochemistry, and motor deficits as detected by beam balance and cylinder testing after tMCAO. These results demonstrate that UCHL1 hydrolase activity ameliorates white matter injury and functional deficits after acute ischemic injury and support the hypothesis that UCHL1 activity plays a significant role in preserving white matter integrity and recovery of function after cerebral ischemia.

Perfusion imaging is useful to assess tissue recovery in patients with acute ischemic stroke (AIS); however, it cannot reflect tissue metabolism. We postulated that amide proton transfer (APT) imaging can characterize the tissue status after reperfusion therapy, thus providing prognostic value for 90-day functional outcomes. We included 63 patients with AIS and large-vessel occlusion (LVO). The APT signals, including APT^# and NOE^# (nuclear Overhauser enhancement) were quantified. Ischemic lesions observed on APT^# and diffusion-weighted imaging (DWI) were classified according to their mismatch patterns (APT^# < DWI; APT^# ≥ DWI). Predictors of 90-day good outcomes (modified Rankin scale score 0-2) were evaluated. Patients with successful reperfusion exhibited higher APT^#, smaller percentage change of APT^#, and a greater likelihood of presenting APT^# < DWI compared to those with poor reperfusion (all P < 0.05). The APT^# (odds ratio [OR] = 11.48, P = 0.046) and a mismatch pattern of APT^# < DWI (OR = 7.41, P = 0.020) independently predicted good outcomes besides the clinical parameters. A mismatch pattern of APT^# ≥ DWI was a significant marker of poor outcomes despite successful reperfusion (P = 0.002). Our study provides preliminary evidence that APT may reveal tissue recovery after reperfusion and predict good outcomes at 90 days in patients with AIS and LVO.

This paper describes the preclinical validation of the radioligand [¹¹C]ORM-13070 and its tritiated analog for addressing selectivity and occupancy of the selective alpha-2C adrenergic receptor (α_2CR) antagonist BAY 292 in the cynomolgus brain. BAY 292 is a novel drug candidate being developed for the treatment of obstructive sleep apnea (OSA) via binding to central α_2CR. In vitro autoradiography studies with sections from non-diseased post-mortem human caudate revealed an excellent specific binding window (>80%) using [³H]ORM-13070. BAY 292 bound to the same binding site as [³H]ORM-13070 and generated a good specific binding signal, with greater selectivity for α_2CR. In non-human primates in vivo, [¹¹C]ORM-13070 demonstrated a reversible behavior, with uptake at baseline highest in striatum (putamen, caudate, ventral striatum, and pallidum) and low in the cerebellar cortex, consistent with the known distribution of the α_2CR. A dose dependent increase in receptor occupancy after BAY 292 administration was observed, confirming BBB penetration and target engagement. The estimated EC₅₀ for BAY 292 is 33.39 ± 11.91 ng/mL. This study aimed to demonstrate the suitability of [¹¹C]ORM-13070 as a PET-radioligand for the study of α_2CR in the non-human primate brain, and to pave the way for future clinical PET tracer studies with BAY 292.

Endovascular thrombectomy has a recanalization rate over 80%; however, approximately 50% of ischemic stroke patients still experience dependency or mortality. Recently, clinical trials demonstrated the benefits of administering neuroprotective agents prior to endovascular thrombectomy. Additionally, recent studies showed neuroprotective effects of mild hypercapnia in patients resuscitated after cardiac arrest. However, its efficacy in ischemic stroke remains unclear. We aimed to investigate whether carbon dioxide (CO₂) per-conditioning has neuroprotective effects in rat models with middle cerebral artery occlusion (MCAO). Rat models received intermittent inhalation of mixed gas during the MCAO period. After surgery, behavioral assessments, infarct size measurement, immunohistochemistry, and western blot analysis were performed. We found CO₂ per-conditioning reduced infarct size and neurological deficit. The number of 8-hydroxy-2-deoxyguanosine (8-OHdG) positive cells and matrix metalloproteinase 9 (MMP-9)/platelet derived growth factor receptor beta (PDGFRβ) double positive cells were significantly decreased after CO₂ per-conditioning. The expressions of tight junction protein and pericytes survival were preserved. This study underscores mild hypercapnia before reperfusion not only reduces neurologic deficit and infarct size, but also maintains the integrity of the blood-brain barrier and neurovascular unit, alongside mitigating oxidative stress in hyperacute stroke rat models. Therapeutic mild hypercapnia before reperfusion is promising and requires further clinical application.

While the concept of pericyte heterogeneity in the brain microvasculature is becoming more widely accepted, little is known about how they arise, or their functional contributions to the blood-brain barrier (BBB). We therefore set out to examine the distribution of subtypes of pericytes at the BBB and sought to elucidate some of their functional characteristics by examining their unique mRNA expression patterns. We demonstrate that type-1 pericytes (PC1) that are associated with young healthy brains and BBB homeostasis, can transition into type-2 pericytes (PC2) that are associated with disease and BBB breakdown, both in vitro and in vivo, in the presence of both endogenous and disease associated ligands. We identified PC1 and PC2 in single-cell RNA-sequencing from vascular enriched mouse brain and identified transcriptional differences between PC1 and PC2. PC2 showed increased expression of genes associated with phagocytosis and peripheral immune cell infiltration. On the contrary, PC1 displayed increased expression of genes involved in hedgehog signaling, which is known to promote tight junction formation at the BBB. Our data support the PC1-to-PC2 transition as an origin of PC diversity and suggest a functional role for PC1 in maintaining BBB homeostasis and PC2 in responding to pathological conditions.

General modeling strategies for sporadic cerebral small blood vessel diseases (CSVDs) include limiting blood stream in large blood vessels and inducing systemic hypertension, in which small blood vessel deficit is either a secondary or concomitant pathology. In the current study, we introduce that intra-cisterna-magna Bevacizumab injection (ICM-BI) directly causes cerebral small blood vessel injury by neutralizing VEGF-A, the indispensable growth factor for angiogenesis. ICM-BI reproduces neuro-functional impairment, tight junction loss, cerebral micro-bleeds (CMBs), amyloid peptide accumulation, neuronal injury, white matter loss, and glial cell activation, which are common manifestations of sporadic CSVDs. Compared with existing CSVD models, small blood vessel injury is more prominent in the ICM-BI brain. Moreover, no significant alteration in large blood vessels or peripheral organs after ICM-BI is recorded. We thus propose that ICM-BI is a neat, economic and applicable methodology to establish murine sporadic CSVD model.

Aging-related cognitive decline is emerging as a health concern during the aging process of the global population. Hahn and colleagues found that glial aging was particularly accelerated in white matter compared to cortical regions. Specialized neuronal populations showed region-specific changes in gene expression. Acute dietary restriction triggers a reprogramming of genes associated with the circadian clock in glial cells, whereas injections of young mouse plasma selectively reverse age-related expression patterns. The discovery of region-specific aging could enhance our understanding of the aging process and offer new possibilities for innovative treatment strategies and interventions for cognitive impairments related to aging.

We investigated the association between cerebral small vessel disease (CSVD) and ipsilateral leptomeningeal collateral (LMC) status in patients with symptomatic intracranial atherosclerotic stenosis (sICAS). In 108 patients with 50-99% symptomatic intracranial internal carotid artery or M1 middle cerebral artery stenosis, 4 CSVD imaging markers (lacunes, cerebral microbleeds, enlarged perivascular spaces [EPVSs], and white matter hyperintensities [WMHs]) were assessed in MRI. Score of 0 or 1 was assigned to each marker and added up as a summary CSVD score (ranging 0-4) to reflect an overall CSVD burden. Ipsilateral LMC status was assessed by determining the laterality of distal vessels in anterior and posterior cerebral artery territories on CT angiography. Moderate-to-severe EPVSs (adjusted odds ratio [aOR] = 4.15; p = 0.031) and WMHs (aOR = 5.90; p = 0.010), and higher summary CSVD score (aOR = 1.66; p = 0.030) were independently associated with poor LMCs. There was significant interaction between stenosis percentage in sICAS and summary CSVD score on poor LMCs (p = 0.022 for interaction), when higher CSVD score was significantly associated with poor LMCs in patients with severe sICAS (aOR = 2.84; p = 0.011) but not in those with moderate sICAS. The findings indicated possibly adverse effect of CSVD on the recruitment or development of LMCs in sICAS patients, especially in patients with severe sICAS.

Cortical spreading depression (CSD) is associated with pronounced alterations in cerebral blood flow. These alterations can be captured using high-field functional magnetic resonance imaging (fMRI). While compelling clinical and experimental data suggest that CSD is involved in the pathogenesis of migraine aura, the mechanistic intricacies remain poorly understood. Here, we use visual stimulus-induced blood oxygen level-dependent (BOLD) fMRI responses to characterize spatiotemporal alterations in cerebral blood flow during spontaneous attacks with migraine aura. Six adult participants diagnosed with migraine with aura underwent BOLD fMRI scans with a visual stimulation paradigm, consisting of flickering checkerboard stimulation. Our results revealed that auras with somatosensory symptoms corresponded with bilateral alterations of stimulus-induced BOLD responses in the somatosensory cortex, exhibiting anterior-to-posterior propagation and absence of antecedent occipital abnormalities. These altered stimulus-induced BOLD responses were bilateral, despite a unilateral manifestation of aura symptoms, and had no relationship with positive or negative aura symptoms. The bilateral abnormalities in stimulus-induced BOLD responses completes our current knowledge on migraine aura.