Profiling the mouse brain endothelial transcriptome in health and disease models reveals a core blood-brain barrier dysfunction module.

Blood vessels in the CNS form a specialized and critical structure, the blood-brain barrier (BBB). We present a resource to understand the molecular mechanisms that regulate BBB function in health and dysfunction during disease. Using endothelial cell enrichment and RNA sequencing, we analyzed the gene expression of endothelial cells in mice, comparing brain endothelial cells with peripheral endothelial cells. We also assessed the regulation of CNS endothelial gene expression in models of stroke, multiple sclerosis, traumatic brain injury and seizure, each having profound BBB disruption. We found that although each is caused by a distinct trigger, they exhibit strikingly similar endothelial gene expression changes during BBB disruption, comprising a core BBB dysfunction module that shifts the CNS endothelial cells into a peripheral endothelial cell-like state. The identification of a common pathway for BBB dysfunction suggests that targeting therapeutic agents to limit it may be effective across multiple neurological disorders

Role of macrophage autophagy in postoperative pain and inflammation in mice

Abstract Background Postoperative pain and inflammation are significant complications following surgery. Strategies that aim to prevent excessive inflammation without hampering natural wound-healing are required for the management of postoperative pain and inflammation. However, the knowledge of the mechanisms and target pathways involved in these processes is lacking. Recent studies have revealed that autophagy in macrophages sequesters pro-inflammatory mediators, and it is therefore being recognized as a crucial process involved in regulating inflammation. In this study, we tested the hypothesis that autophagy in macrophages plays protective roles against postoperative pain and inflammation and investigated the underlying mechanisms. Methods Postoperative pain was induced by plantar incision under isoflurane anesthesia in mice lacking macrophage autophagy (Atg5flox/flox LysMCre +) and their control littermates (Atg5flox/flox). Mechanical and thermal pain sensitivity, changes in weight distribution, spontaneous locomotor activity, tissue inflammation, and body weight were assessed at baseline and 1, 3, and 7 days after surgery. Monocyte/macrophage infiltration at the surgical site and inflammatory mediator expression levels were evaluated. Results Atg5flox/flox LysMCre + mice compared with the control mice exhibited lower mechanical and thermal pain thresholds and surgical/non-surgical hindlimb weight-bearing ratios. The augmented neurobehavioral symptoms observed in the Atg5flox/flox LysMCre + mice were associated with more severe paw inflammation, higher pro-inflammatory mediator mRNA expression, and more monocytes/macrophages at the surgical site. Conclusion The lack of macrophage autophagy augmented postoperative pain and inflammation, which were accompanied by enhanced pro-inflammatory cytokine secretion and surgical-site monocyte/macrophage infiltration. Macrophage autophagy plays a protective role in postoperative pain and inflammation and can be a novel therapeutic target

Neuroprotective effects of amiodarone in a mouse model of ischemic stroke

Abstract Background Ion channels play a crucial role in the development of ischemic brain injury. Recent studies have reported that the blockade of various types of ion channels improves outcomes in experimental stroke models. Amiodarone, one of the most effective drugs for life-threatening arrhythmia, works as a multiple channel blocker and its characteristics cover all four Vaughan-Williams classes. Although it is known that amiodarone indirectly contributes to preventing ischemic stroke by maintaining sinus rhythm in patients with atrial fibrillation, the direct neuroprotective effect of amiodarone has not been clarified. The purpose of this study was to investigate the direct effect of amiodarone on ischemic stroke in mice. Methods Focal cerebral ischemia was induced via distal permanent middle cerebral artery occlusion (MCAO) in adult male mice. The amiodarone pre-treatment group received 50 mg/kg of amiodarone 1 h before MCAO; the amiodarone post-treatment groups received 50 mg/kg of amiodarone immediately after MCAO; the control group received vehicle only. In addition, the sodium channel opener veratrine and selective beta-adrenergic agonist isoprotelenol were used to elucidate the targeted pathway. Heart rate and blood pressure were monitored perioperatively. Infarct volume analysis was conducted 48 h after MCAO. The body asymmetry test and the corner test were used for neurological evaluation. Results Amiodarone pre-treatment and post-treatment reduced the heart rate but did not affect the blood pressure. No mice showed arrhythmia. Compared with the control group, the amiodarone pre-treatment group had smaller infarct volumes (8.9 ± 2.1% hemisphere [mean ± SD] vs. 11.2 ± 1.4%; P < 0.05) and improved functional outcomes: lower asymmetric body swing rates (52 ± 17% vs. 65 ± 18%; P < 0.05) and fewer left turns (7.1 ± 1.2 vs. 8.3 ± 1.2; P < 0.05). In contrast, amiodarone post-treatment did not improve the outcomes after MCAO. The neuroprotective effect of amiodarone pre-treatment was abolished by co-administration of veratrine but not by isoproterenol. Conclusions Amiodarone pre-treatment attenuated ischemic brain injury and improved functional outcomes without affecting heart rhythm and blood pressure. The present results showed that amiodarone pre-treatment has neuroprotective effects, at least in part, via blocking the sodium channels

Role Of Myeloid Lineage Cell Autophagy In Ischemic Brain Injury

Background and Purpose-Inflammatory cells play a significant role in secondary injury after ischemic stroke. Recent studies have suggested that a lack of autophagy in myeloid cells causes augmented proinflammatory cytokine release and prolonged inflammation after tissue injury. In this study, we investigated the roles of myeloid cell autophagy in ischemic brain injury. Methods-Focal cerebral ischemia was induced via transient middle cerebral artery occlusion in mice with autophagydeficient myeloid lineage cells (Atg5flox/flox LysMCre+) and in their littermate controls (Atg5flox/flox). Infarct volume, neurological function, inflammatory cell infiltration, and proinflammatory cytokine expression levels were evaluated. Results-Mice lacking autophagy in myeloid lineage cells had a lower survival rate for 14 days than control mice (20% versus 70%; P\u3c0.05). Although there was no difference in infarct volume at 12 hours between the 2 groups, mice lacking autophagy in myeloid lineage cells had larger infarct volumes at later time points (3 and 7 days after reperfusion) with worse neurological deficit scores and lower grip test scores. There were a higher number of ionized calcium binding adaptor molecule 1-positive cells and cells expressing M1 marker CD16/32 in mice lacking autophagy in myeloid cells at the later time points. Moreover, these mice had higher expression levels of proinflammatory cytokines at later time points; however, there was no difference in ionized calcium binding adaptor molecule 1-positive cells or mRNA levels of proinflammatory cytokines at the earlier time point (12 hours after reperfusion). Conclusions-These data suggest that the lack of myeloid cell autophagy aggravates secondary injury by augmenting and prolonging inflammation after ischemic stroke without affecting the initial injury

Potential Influences Of Gut Microbiota On The Formation Of Intracranial Aneurysm

Gut microbiota modulates metabolic and immunoregulatory axes and contributes to the pathophysiology of diseases with inflammatory components, such as atherosclerosis, diabetes mellitus, and ischemic stroke. Inflammation is emerging as a critical player in the pathophysiology of an intracranial aneurysm. Therefore, we hypothesized that the gut microbiota affects aneurysm formation by modulating inflammation. We induced intracranial aneurysms in mice by combining systemic hypertension and a single injection of elastase into the cerebrospinal fluid. Depletion of the gut microbiota was achieved via an oral antibiotic cocktail of vancomycin, metronidazole, ampicillin, and neomycin. Antibiotics were given 3 weeks before aneurysm induction and either continued until the end of the experiment or stopped 1 day before aneurysm induction. We also assessed the effects of the gut microbiota depletion on macrophage infiltration and mRNA levels of inflammatory cytokines. Gut microbiota depletion by antibiotics reduced the incidence when antibiotics were started 3 weeks before aneurysm induction and continued until the end of the experiment (83% versus 6%, P\u3c0.001). Even when antibiotics were stopped 1 day before aneurysm induction, the gut microbiota depletion significantly reduced the incidence of aneurysms (86% versus 28%, P\u3c0.05). Both macrophage infiltration and mRNA levels of inflammatory cytokines were reduced with gut microbiota depletion. These findings suggest that the gut microbiota contributes to the pathophysiology of aneurysms by modulating inflammation. Human studies are needed to determine the exact contribution of the gut microbiota to the pathophysiology of aneurysm formation and disease course in humans

Profiling the mouse brain endothelial transcriptome in health and disease models reveals a core blood-brain barrier dysfunction module

Blood vessels in the CNS form a specialized and critical structure, the blood-brain barrier (BBB). We present a resource to understand the molecular mechanisms that regulate BBB function in health and dysfunction during disease. Using endothelial cell enrichment and RNA sequencing, we analyzed the gene expression of endothelial cells in mice, comparing brain endothelial cells with peripheral endothelial cells. We also assessed the regulation of CNS endothelial gene expression in models of stroke, multiple sclerosis, traumatic brain injury and seizure, each having profound BBB disruption. We found that although each is caused by a distinct trigger, they exhibit strikingly similar endothelial gene expression changes during BBB disruption, comprising a core BBB dysfunction module that shifts the CNS endothelial cells into a peripheral endothelial cell-like state. The identification of a common pathway for BBB dysfunction suggests that targeting therapeutic agents to limit it may be effective across multiple neurological disorders