Simvastatin improves cerebrovascular injury caused by ischemia­reperfusion through NF­κB­mediated apoptosis via MyD88/TRIF signaling.

Cerebrovascular injury is the most prevalent human cerebrovascular disease and frequently results in ischemic stroke. Simvastatin may be a potential therapeutic agent for the treatment of patients with cerebrovascular injury. The present study aimed to investigate the efficacy of and the potential mechanisms regulated by simvastatin in a rat model of ischemia­reperfusion (I/R)­induced cerebrovascular injury. Cerebrovascular injury model rats were established and were subsequently treated with simvastatin or a vehicle control following I/R injury. Cell damage, neurological functions and neuronal apoptosis were examined, as well as the nuclear factor (NF)­κB­mediated myeloid differentiation primary response protein 88 (MyD88)/toll­interleukin­1 receptor domain­containing adapter molecule 1 (TRIF) signaling pathway following simvastatin treatment. The results of the present study demonstrated that simvastatin treatment led to a reduction in cell damage, improvement of neurological functions and decreased neuronal apoptosis compared with vehicle­treated I/R model rats, 14 days post­treatment. In addition, simvastatin treatment reduced cerebral water content and blood­brain barrier disruption in cerebrovascular injury induced by I/R. The results also revealed that simvastatin treatment inhibited neuronal apoptosis via the NF­κB­mediated MyD88/TRIF signaling pathway. In conclusion, simvastatin treatment may reduce I/R­induced neuronal apoptosis via inhibition of the NF­κB­mediated MyD88/TRIF signaling pathway.

Macrophages Mediate the Repair of Brain Vascular Rupture through Direct Physical Adhesion and Mechanical Traction.

Hemorrhagic stroke and brain microbleeds are caused by cerebrovascular ruptures. Fast repair of such ruptures is the most promising therapeutic approach. Due to a lack of high-resolution in vivo real-time studies, the dynamic cellular events involved in cerebrovascular repair remain unknown. Here, we have developed a cerebrovascular rupture system in zebrafish by using multi-photon laser, which generates a lesion with two endothelial ends. In vivo time-lapse imaging showed that a macrophage arrived at the lesion and extended filopodia or lamellipodia to physically adhere to both endothelial ends. This macrophage generated mechanical traction forces to pull the endothelial ends and facilitate their ligation, thus mediating the repair of the rupture. Both depolymerization of microfilaments and inhibition of phosphatidylinositide 3-kinase or Rac1 activity disrupted macrophage-endothelial adhesion and impaired cerebrovascular repair. Our study reveals a hitherto unexpected role for macrophages in mediating repair of cerebrovascular ruptures through direct physical adhesion and mechanical traction.

Chronic systemic infection exacerbates ischemic brain damage via a CCL5 (regulated on activation, normal T-cell expressed and secreted)-mediated proinflammatory response in mice.

Infection and systemic inflammation are risk factors for cerebrovascular diseases and poststroke infections impair outcome in stroke patients, although the mechanisms of their contribution are mostly unknown. No preclinical studies have identified how chronic infection affects ischemic brain damage and which key inflammatory mediators are involved. We used a well established model of gut infection (Trichuris muris) to study how chronic infection contributes to brain injury. We show that, in mice, infection that leads to a chronic Th1-polarized immune response dramatically (60%) exacerbates brain damage caused by experimental stroke. Chronic Th1-type infection resulted in systemic upregulation of proinflammatory mediators and profoundly altered stroke-induced early (40 min to 4 h) and late (48 h) inflammation in the brain and peripheral tissues. Using the same infection, we show that a Th1-, but not Th2-polarized response augments brain injury by increasing the Th1 chemokine CCL5 [regulated on activation, normal T-cell expressed and secreted (RANTES)] systemically. This infection-associated response paralleled altered regulatory T-cell response, accelerated platelet aggregation in brain capillaries, and increased microvascular injury and matrix metalloproteinase activation after stroke. Antibody neutralization of RANTES reversed the effect of chronic infection on brain damage, microvascular MMP-9 activation, and cellular inflammatory response. Our results suggest that chronic infection exacerbates ischemic brain damage via a RANTES-mediated systemic inflammatory response, which leads to delayed resolution of inflammation and augmented microvascular injury in the brain.

Proinflammatory cytokines in sera of elderly patients with dementia: levels in vascular injury are higher than those of mild-moderate Alzheimer's disease patients.

Cognitive functions display a progressive impairment with ageing, and this is thought to be due to the accumulation of neuronal loss or acute and/or repeated microvascular accidents. Chronic damage to the brain cortex lead to decreasing ability of elderly subjects to cope with daily events and ultimately result in loss of self-sufficiency. Since proinflammatory cytokines have been implicated both in cerebrovascular injury due to atherosclerosis and in Alzheimer's disease (AD), we investigated 70 elderly subjects with neurocognitive and functional impairment. Diagnosis was established in 54, the others were included in the "mixed" group. Sera were collected and stored at -70 degrees C until measurement of IL-1beta and TNF-alpha, performed by commercial ELISA kits. Data obtained were analysed with respect to other socio-demographic, psychoneurological and clinical variables. The results show that serum TNF-alpha was lower in mild-moderate AD compared to severe AD and dementias due to vascular disease, as well as the TNF-alpha/IL-1beta ratio. Both cytokines showed a significant relationship with age. Our study suggests that proinflammatory cytokines serum profiles seem to discriminate between mild-moderate AD and vascular or mixed forms of dementia. Furthermore, it offers new evidence of a strong implication of inflammatory mechanisms in atherosclerosis, more than in less severe AD.