Early intravenous infusion of sodium nitrite protects brain against in vivo ischemia-reperfusion injury

BACKGROUND AND PURPOSE: The rate of nitric oxide (NO) generation from nitrite is linearly dependent on reductions in oxygen and pH levels. Recently, nitrite-derived NO has been reported to exert a profound protection against liver and heart ischemia-reperfusion injury. In this study, we hypothesized that nitrite would be reduced to NO in the ischemic brain and exert NO-dependent neuroprotective effects. METHODS: Cerebral ischemia-reperfusion injury was induced by intraluminal thread occlusion of middle cerebral artery in the adult male rats. Solutions of sodium nitrite were infused intravenously at the time of reperfusion. Sodium nitrate and carboxy-PTIO (30 minutes before ischemic surgery), a direct NO scavenger, were infused for comparisons. RESULTS: Nitrite reduced infarction volume and enhanced local cerebral blood flow and functional recovery. The effects were observed at concentrations of 48 nmol and 480 nmol, but not at 4800 nmol nitrite and 480 nmol nitrate. The neuroprotective effects of nitrite were inhibited completely by the carboxy-PTIO. The 480 nmol nitrite attenuated dihydroethidium activity, 3-nitrotyrosine formation, and lipid peroxidation in the ischemic brain. CONCLUSIONS: Nitrite exerted profound neuroprotective effects with antioxidant properties in the ischemic brains. These results suggest that nitrite, as a biological storage reserve of NO, may be a novel therapeutic agent in the setting of acute stroke.This study was supported by a Korean Research Foundation grant funded by the Korean Government (MOEHRD, Basic Research Promotion Fund, KRF-2005-015-E00182)

Circulating endothelial progenitor cells as a new marker of endothelial dysfunction or repair in acute stroke

BACKGROUND AND PURPOSE: Understanding on distinct subsets of endothelial progenitor cells may provide insights of endothelial dysfunction or repair in the acute ischemic event. Recent in vitro data have reported the colony-forming unit (CFU) and outgrowth cell population as a subset of endothelial progenitor cells. In this study, we undertook to validate the significance of CFU number and outgrowth cell yield in acute stroke. METHODS: Mononuclear cells were isolated from the peripheral blood of 75 patients with acute stroke, 45 patients with chronic stroke, and 40 age-matched healthy volunteers. CFU numbers were counted after culturing them for 7 days, and outgrowth cell appearance was measured during the 2 months of culture. Endothelial progenitor cell function was also evaluated by matrigel plate assays. Independent parameters predicting CFU number and outgrowth cell yield were assessed using logistic regression analysis. RESULTS: The CFU numbers and tube formation abilities in matrigel assays were significantly reduced in patients with acute stroke compared with patients with chronic stroke or healthy control subjects. Moreover, patients with large artery atherosclerosis had much lower CFU numbers and functional activities than ones with cardioembolism. Outgrowth cells were isolated from 10% of healthy control subjects and 22% of patients with chronic stroke during the cultures, but from 71% of patients with stroke. Multivariate analysis identified glycosylated hemoglobin and National Institutes of Health Stroke Scale on admission as significant independent predictors of a low CFU number and a high isolation frequency of outgrowth cells, respectively. CONCLUSIONS: CFU number may thus represent an accumulated endothelial progenitor cell dysfunctional status, whereas outgrowth cell appearance may reflect the resilience of the systemic circulation to acute ischemic stress

High‐Intensity Statin Reduces the Risk of Mortality Among Chronic Liver Disease Patients With Atherosclerotic Cardiovascular Disease: A Population‐Based Cohort Study

Background 2018 American Heart Association/American College of Cardiology cholesterol guideline recommends statin in patients with chronic and/or stable liver disease for secondary prevention of atherosclerotic cardiovascular disease yet remains equivocal on the adequate intensity of statin for patients with chronic liver disease (CLD). We aimed to assess the association between statin intensity and mortality among patients with CLD with atherosclerotic cardiovascular disease. Methods and Results We conducted a population‐based cohort study in South Korea. We assessed the risk of survival and clinical outcomes using inverse probability of treatment‐weighted Cox proportional hazards regression. We also estimated the absolute risk difference between treatment groups based on the Poisson distribution. During an average of 2.35 person‐years, 10 442 patients with CLD with atherosclerotic cardiovascular disease were identified. Among those patients, 5515 (52.8%) received high‐intensity statin, and 4927 (47.2%) received low/moderate‐intensity statin. High‐intensity statin was associated with lower risk for all‐cause mortality (hazard ratio [HR], 0.83 [95% CI, 0.75–0.92]), cardiovascular‐cause mortality (HR, 0.85 [0.71–1.01]), liver‐cause mortality (HR, 0.72 [0.54–0.97]) compared with low/moderate‐intensity statin. Although both hospitalizations for recurrent myocardial infarction and stroke were shown to be increased among high‐intensity statin users, effect estimate was homogeneous in the absolute scale (myocardial infarction: HR, 1.12 [1.04–1.19], risk difference, 7.57 [−0.69 to 15.84] per 1000 person‐years; stroke: HR, 1.11 [0.97 to 1.27]; risk difference, −1.70 [−5.19 to 1.78]). Conclusions Among patients with CLD with atherosclerotic cardiovascular disease, high‐intensity statin was significantly associated with a lower risk of mortality. These findings herein support the guidelines for statin use in patients with CLD while demonstrating potential benefit of optimal intensity use

Combined neuroprotective effects of celecoxib and memantine in experimental intracerebral hemorrhage

Memantine, a N-methyl-D-aspartate (NMDA) receptor antagonist, inhibits hematoma expansion and celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, reduces perihematomal inflammation in intracerebral hemorrhage. We examined whether the combination treatment has additive effects in experimental intracerebral hemorrhage (ICH). ICH was induced using stereotaxic infusion of collagenase into brains of adult rats. After the induction of ICH, rats were treated with intraperitoneal injection of memantine (20 mg/kg), celecoxib (20 mg/kg) or both agents. Only vehicles were administrated in rats of the control group. Results showed that the combination treatment of memantine and celecoxib reduced both hematoma volume and brain edema. Combination treatment also induced the better functional recovery with further attenuation of cerebral inflammation and apoptosis compared to the control group. When compared to the single agent groups, the combination treatment showed better effects in neuroprotection and anti-inflammation. These results suggest the feasible combined application of memantine and celecoxib in ICH treatment.This study was supported by a Korean Research Foundation Grant funded by theKorean Government (MOEHRD, Basic Research Promotion Fund, KRF-2005-015-E00182)

Granulocyte colony-stimulating factor stimulates neurogenesis via vascular endothelial growth factor with STAT activation

The adult brain harbors multipotent stem cells, which reside in specialized niches that support self-renewal. Granulocyte colony-stimulating factor (G-CSF) induces bone marrow stem cells proliferation and mobilization from their niche, and activates endothelial cell proliferation, which might help to establish a vascular niche for neural stem cells (NSCs). Here, we show that G-CSF induced receptor-mediated proliferation and differentiation of neural precursors in human NSCs cultures and in adult rat brain in vivo. In human NSCs cultures, G-CSF activated STAT3 and 5, and increased VEGF and its receptor, VEGFR2 (Flk-1) expression, and VEGFR2 tyrosine kinase inhibitor blocked the neurogenesis stimulated by G-CSF. G-CSF also activated endothelial cell proliferation in adult rat brain in vivo. Our results indicate that G-CSF stimulates neurogenesis through reciprocal interaction with VEGF and STAT activation

Quantification of human neural stem cell engraftments in rat brains using ERV-3 real-time PCR

Few sensitive and reliable methods have been available for quantifying the number of transplanted human neural stem cells (hNSC) in the animal brain. To develop an accurate method for quantifying the number of hNSC incorporated in rat brain, we performed real-time PCR on hNSC-transplanted rat brains using a target sequence for ERV-3, which is an endogenous retrovirus present with a known copy number in all human cells, but not present in rodent cells. A standard curve was developed for known amount of different mixes of hNSC and rat fibroblasts, and test samples were prepared by manually incorporating variable, predefined numbers of hNSCs into rat brains. A cerebral rat hemisphere injected with 10(7) hNSC revealed 1.125% chimerism. Moreover, a linear correlation was found between hNSC numbers injected and their concentrations in the rat brain. In conclusion, the developed quantitative ERV-3 assay enables a simple, fast, and reproducible detection and quantitation of hNSC numbers in the rat brain.This research was supported by a grant (SC3060) from Stem Cell Research Center of the 21st Century Frontier Research Program funded by the Ministry of Science and Technology, Republic of Korea

Cyclooxygenase-2 inhibitor, celecoxib, inhibits the altered hippocampal neurogenesis with attenuation of spontaneous recurrent seizures following pilocarpine-induced status epilepticus

Recent evidences suggest key roles of abnormal neurogenesis and astrogliosis in the pathogenesis of epilepsy. Alterations in the microenvironment of the stem cell, such as microglial activation and cyclooxygenase-2 induction may cause ectopic neurogenesis or astrogliosis. Here, we examined if inflammatory blockade with celecoxib, a selective cyclooxygenase-2 inhibitor, could modulate the altered microenvironment in the epileptic rat brain. Celecoxib attenuated the likelihood of developing spontaneous recurrent seizures after pilocarpine-induced prolonged seizure. During the latent period, celecoxib prevented neuronal death and microglia activation in the hilus and CA1 and inhibited the generation of ectopic granule cells in the hilus and new glia in CA1. The direct inhibition of precursor cells by celecoxib was further demonstrated in human neural stem cells culture. These findings raise the evidence of COX-2 induction to act importantly on epileptogenesis and suggest a potential therapeutic role for COX-2 inhibitors in chronic epilepsy

Proteasomal inhibition in intracerebral hemorrhage: neuroprotective and anti-inflammatory effects of bortezomib

Inflammation is an important pathophysiologic mechanism of injury induced by intracerebral hemorrhage (ICH). The ubiquitin-proteasome system (UPS) regulates the inflammatory responses via the up-regulation of several pro-inflammatory molecules. In this study, we determined that a potent proteasome inhibitor, bortezomib, exerted therapeutic effects in experimental model of ICH. Either bortezomib (0.05, 0.2, 0.5, 1mg/kg) or vehicle was intravenously administered 2h after ICH induction. The high doses of bortezomib caused high mortality rates. Bortezomib at 0.2 mg/kg reduced the early hematoma growth and alleviated hematoma volume and brain edema at 3 days after ICH, compared with the ICH-vehicle group. The numbers of myeloperoxidase(+) neutrophils, Ox42(+) microglia, and TUNEL(+) cells in the perihematomal regions were decreased by bortezomib. Bortezomib induced significant decrements of mRNA expression of TNF-alpha and IL-6. The production of iNOS and COX2 was also reduced significantly by bortezomib. We concluded that the early treatment with bortezomib induced a reduction in the early hematoma growth and mitigated the development of brain edema, coupled with a marked inhibitory effect on inflammation in ICH