Role of post-ischemic phase-dependent modulation of anti-inflammatory M2-type macrophages against rat brain damage.

Cerebral ischemia triggers inflammatory changes, and early complications and unfavorable outcomes of endovascular thrombectomy for brain occlusion promote the recruitment of various cell types to the ischemic area. Although anti-inflammatory M2-type macrophages are thought to exert protective effects against cerebral ischemia, little has been clarified regarding the significance of post-ischemic phase-dependent modulation of M2-type macrophages. To test our hypothesis that post-ischemic phase-dependent modulation of macrophages represents a potential therapy against ischemic brain damage, the effects on rats of an M2-type macrophage-specific activator, Gc-protein macrophage-activating factor (GcMAF), were compared with vehicle-treated control rats in the acute (day 0-6) or subacute (day 7-13) phase after ischemia induction. Acute-phase GcMAF treatment augmented both anti-inflammatory CD163+ M2-type- and pro-inflammatory CD16+ M1-type macrophages, resulting in no beneficial effects. Conversely, subacute-phase GcMAF injection increased only CD163+ M2-type macrophages accompanied by elevated mRNA levels of arginase-1 and interleukin-4. M2-type macrophages co-localized with CD36+ phagocytic cells led to clearance of the infarct area, which were abrogated by clodronate-liposomes. Expression of survival-related molecules on day 28 at the infarct border was augmented by GcMAF. These data provide new and important insights into the significance of M2-type macrophage-specific activation as post-ischemic phase-dependent therapy.

Activation of the NLRP3/IL-1ß/MMP-9 pathway and intracranial aneurysm rupture associated with the depletion of ERα and Sirt1 in oophorectomized rats.

OBJECTIVE: Subarachnoid hemorrhage (SAH) due to intracranial aneurysm (IA) rupture is often a devastating event. Since the incidence of SAH increases especially in menopause, it is crucial to clarify the detailed pathogenesis of these events. The activation of vascular nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasomes has been studied in ischemic stroke and cardiovascular disease. However, the role of NLRP3 in IA rupture still needs to be explained. The authors sought to test their hypothesis that, under estrogen-deficient conditions, activation of NLRP3 inflammasomes via downregulation of the estrogen receptor (ER) facilitates IA rupture. METHODS: Ten-week-old female Sprague Dawley rats with and without oophorectomy were subjected to hemodynamic changes and hypertension (OVX+/HT and OVX-/HT, respectively) and fed a high-salt diet. Separately, using human brain endothelial cells (HBECs) and human brain smooth muscle cells (HBSMCs), the authors tested the effect of NLRP3 under estrogen-free conditions and in the presence of estradiol or of ER agonists. RESULTS: In OVX+/HT rats, the frequency of IA rupture was significantly higher than in OVX-/HT rats (p = 0.03). In the left posterior cerebral artery prone to rupture in OVX+/HT rats, the levels of the mRNAs encoding ERα and Sirt1, but not of that encoding ERß, were decreased, and the levels of the mRNAs encoding NLRP3, interleukin-1ß (IL-1ß), and matrix metalloproteinase 9 (MMP-9) were elevated. Immunohistochemical analysis demonstrated that the expression profiles of these proteins correlated with their mRNA levels. Treatment with an ER modulator, bazedoxifene, normalized the expression profiles of these proteins and improved SAH-free survival. In HBECs and HBSMCs under estrogen-free conditions, the depletion of ERα and Sirt1 and the accumulation of NLRP3 were counteracted by exposure to estradiol or to an ERα agonist but not to an ERß agonist. CONCLUSIONS: To the authors' knowledge, this work represents the first demonstration that, in an aneurysm model under estrogen-deficient conditions, the depletion of ERα and Sirt1 may contribute to activation of the NLRP3/IL-1ß/MMP-9 pathway, facilitating the rupture of IAs in the estrogen-deficient rat IA rupture model.

An imbalance between RAGE/MR/HMGB1 and ATP1α3 is associated with inflammatory changes in rat brain harboring cerebral aneurysms prone to rupture.

BACKGROUND AND PURPOSE: An aneurysmal subarachnoid hemorrhage is a devastating event. To establish an effective therapeutic strategy, its pathogenesis must be clarified, particularly the pathophysiology of brain harboring intracranial aneurysms (IAs). To elucidate the pathology in brain harboring IAs, we examined the significance of the receptor for advanced glycation end-products (RAGE)/mineralocorticoid receptor (MR) pathway and Na+/K+-ATPase (ATP1α3). METHODS: Ten-week-old female rats were subjected to oophorectomy as well as hypertension and hemodynamic changes to induce IAs, and were fed a high-salt diet. Brain damage in these rats was assessed by inflammatory changes in comparison to sham-operated rats fed a standard diet. RESULTS: Six weeks after IA induction (n = 30), irregular morphological changes, i.e., an enlarged vessel diameter and vascular wall, were observed in all of the left posterior cerebral arteries (Lt PCAs) prone to rupture. Approximately 20% of rats had ruptured IAs within 6 weeks. In brain harboring unruptured IAs at the PCA, the mRNA levels of RAGE and MR were higher, and that of ATP1α3 was lower than those in the sham-operated rats (p < 0.05, each). Immunohistochemically, elevated expression of RAGE and MR, and decreased expression of ATP1α3 were observed in the brain parenchyma adjacent to the Lt PCA, resulting in increased Iba-1 and S100B expression that reflected the inflammatory changes. There was no difference between the unruptured and ruptured aneurysm rat groups. Treatment with the MR antagonist esaxerenone abrogated these changes, and led to cerebral and vascular normalization and prolonged subarachnoid hemorrhage-free survival (p < 0.05). CONCLUSIONS: Regulation of the imbalance between the RAGE/MR pathway and ATP1α3 may help attenuate the damage in brain harboring IAs, and further studies are warranted to clarify the significance of the down-regulation of the MR/RAGE pathway and the up-regulation of ATP1α3 for attenuating the pathological changes in brain harboring IAs.

Chronic subdural hematoma associated with dural metastasis leads to early recurrence and death: A single-institute, retrospective cohort study.

The prevalence of chronic subdural hematoma (CSDH) associated with dural metastasis is uncertain, and appropriate treatment strategies have not been established. This study aimed to investigate the characteristics of and appropriate treatment strategies for CSDH associated with dural metastasis. We retrospectively reviewed the charts of 214 patients who underwent surgery for CSDH. The patients were divided into the dural metastasis group (DMG; n = 5, 2.3%) and no dural metastasis group (No-DMG; n = 209, 97.3%). Patient characteristics, treatment, and outcomes were compared between the two groups. Active cancer was detected in 31 out of 214 patients, 5 of whom (16.1%) had dural metastasis. In-hospital death (80.0% vs. 0%; p < 0.001) and recurrence within 14 days (80.0% vs. 2.9%; p < 0.001) and 60 days (80.0% vs. 13.9%; p = 0.002) were significantly prevalent in the DMG. All patients in the DMG developed subdural hematoma re-accumulation requiring emergent surgery because of brain herniation, and patients in the DMG had significantly worse recurrence-free survival (p < 0.001). This relationship remained significant (p < 0.001) even when the analysis was limited to the active cancer cohort (n = 31). CSDH associated with dural metastasis leads to early recurrence and death because of the difficulty in controlling subdural hematoma re-accumulation by common drainage procedures. Depending on the primary cancer status, withdrawal of active treatment and change to palliative care should be discussed after diagnosing CSDH associated with dural metastasis.

Involvement of Neutrophil Extracellular Traps in Cerebral Arteriovenous Malformations.

BACKGROUND: Cerebral arteriovenous malformations (cAVMs) represent tangles of abnormal vasculature without intervening capillaries. High-pressure vascular channels due to abnormal arterial and venous shunts can lead to rupture. Multiple pathways are involved in the pathobiology of cAVMs including inflammation and genetic factors such as KRAS mutations. Neutrophil release of nuclear chromatin, known as neutrophil extracellular traps (NETs), plays a multifunctional role in infection, inflammation, thrombosis, intracranial aneurysms, and tumor progression. However, the relationship between NETs and the pathobiology of cAVMs remains unknown. We tested whether NETs play a role in the pathobiology of cAVMs. METHODS: We analyzed samples from patients who had undergone surgery for cAVM and immunohistochemically investigated expression of citrullinated histone H3 (CitH3) as a marker of NETs. CitH3 expression was compared among samples from cAVM patients, epilepsy patients, and normal human brain tissue. Expressions of thrombotic and inflammatory markers were also examined immunohistochemically in samples from cAVM patients. RESULTS: Expression of CitH3 derived from neutrophils was observed intravascularly in all cAVM samples but not other samples. Nidi of AVMs showed migration of many Iba-I-positive cells adjacent to the endothelium and endothelial COX2 expression, accompanied by expression of IL-6 and IL-8 in the endothelium and intravascular neutrophils. Unexpectedly, expression of CitH3 was not necessarily localized to the vascular wall and thrombus. CONCLUSIONS: Our results offer the first evidence of intravascular expression of NETs, which might be associated with vascular inflammation in cAVMs.

Downregulation of the CCL2/CCR2 and CXCL10/CXCR3 axes contributes to antitumor effects in a mouse model of malignant glioma.

Glioblastoma multiforme involves glioma stem cells (GSCs) that are resistant to various therapeutic approaches. Here, we studied the importance of paracrine signaling in the glioma microenvironment by focusing on the celecoxib-mediated role of chemokines C-C motif ligand 2 (CCL2), C-X-C ligand 10 (CXCL10), and their receptors, CCR2 and CXCR3, in GSCs and a GSC-bearing malignant glioma model. C57BL/6 mice were injected with orthotopic GSCs intracranially and divided into groups administered either 10 or 30 mg/kg celecoxib, or saline to examine the antitumor effects associated with chemokine expression. In GSCs, we analyzed cell viability and expression of chemokines and their receptors in the presence/absence of celecoxib. In the malignant glioma model, celecoxib exhibited antitumor effects in a dose dependent manner and decreased protein and mRNA levels of Ccl2 and CxcL10 and Cxcr3 but not of Ccr2. CCL2 and CXCL10 co-localized with Nestin+ stem cells, CD16+ or CD163+ macrophages and Iba-1+ microglia. In GSCs, celecoxib inhibited Ccl2 and Cxcr3 expression in a nuclear factor-kappa B-dependent manner but not Ccr2 and CxcL10. Moreover, Ccl2 silencing resulted in decreased GSC viability. These results suggest that celecoxib-mediated regulation of the CCL2/CCR2 and CXCL10/ CXCR3 axes may partially contribute to glioma-specific antitumor effects.

Active Cancer and Elevated D-Dimer Are Risk Factors for In-Hospital Ischemic Stroke.

BACKGROUND AND PURPOSE: Little attention has been paid to the pathogenesis of in-hospital stroke, despite poor outcomes and a longer time from stroke onset to treatment. We studied the pathophysiology and biomarkers for detecting patients who progress to in-hospital ischemic stroke (IHS). METHODS: Seventy-nine patients with IHS were sequentially recruited in the period 2011-2017. Their characteristics, care, and outcomes were compared with 933 patients who had an out-of-hospital ischemic stroke (OHS) using a prospectively collected database of the Tokushima University Stroke Registry. RESULTS: Active cancer and coronary artery disease were more prevalent in patients with IHS than in those with OHS (53.2 and 27.8% vs. 2.0 and 10.9%, respectively; p < 0.001), the median onset-to-evaluation time was longer (300 vs. 240 min; p = 0.015), and the undetermined etiology was significantly higher (36.7 vs. 2.4%; p < 0.001). Although there was no significant difference in stroke severity at onset between the groups, patients with IHS had higher modified Rankin Scale (mRS) scores (3-6) at discharge (67.1 vs. 50.3%; p = 0.004) and rates of death during hospitalization (16.5 vs. 2.9%; p < 0.001). D-dimer (5.8 vs. 0.8 µg/mL; p < 0.001) and fibrinogen (532 vs. 430 mg/dL; p = 0.014) plasma levels at the time of onset were significantly higher in patients with IHS after propensity score matching. Multivariate logistic regression analysis revealed that active cancer (odds ratio [OR] 2.30; 95% confidence interval [CI] 1.26-4.20), prestroke mRS scores 3-5 (OR 6.78; 95% CI 3.96-11.61), female sex (OR 1.57; 95% CI 1.19-2.08), and age ≥75 years (OR 2.36; 95% CI 1.80-3.08) were associated with poor outcomes. CONCLUSIONS: Patients with IHS had poorer outcomes than those with OHS because of a higher prevalence of active cancer and functional dependence before stroke onset. Elevated plasma levels of D-dimer and fibrinogen, especially with active cancer, can help identify patients who are at a higher risk of progression to IHS.

Down-regulation of MDR1 by Ad-DKK3 via Akt/NFκB pathways augments the anti-tumor effect of temozolomide in glioblastoma cells and a murine xenograft model.

BACKGROUND: Glioblastoma multiforme (GBM) is the most malignant of brain tumors. Acquired drug resistance is a major obstacle for successful treatment. Earlier studies reported that expression of the multiple drug resistance gene (MDR1) is regulated by YB-1 or NFκB via the JNK/c-Jun or Akt pathway. Over-expression of the Dickkopf (DKK) family member DKK3 by an adenovirus vector carrying DKK3 (Ad-DKK3) exerted anti-tumor effects and led to the activation of the JNK/c-Jun pathway. We investigated whether Ad-DKK3 augments the anti-tumor effect of temozolomide (TMZ) via the regulation of MDR1. METHODS: GBM cells (U87MG and U251MG), primary TGB105 cells, and mice xenografted with U87MG cells were treated with Ad-DKK3 or TMZ alone or in combination. RESULTS: Ad-DKK3 augmentation of the anti-tumor effects of TMZ was associated with reduced MDR1 expression in both in vivo and in vitro studies. The survival of Ad-DKK3-treated U87MG cells was inhibited and the expression of MDR1 was reduced. This was associated with the inhibition of Akt/NFκB but not of YB-1 via the JNK/c-Jun- or Akt pathway. CONCLUSIONS: Our results suggest that Ad-DKK3 regulates the expression of MDR1 via Akt/NFκB pathways and that it augments the anti-tumor effects of TMZ in GBM cells.

Correction to: Treatment with the PPARγ Agonist Pioglitazone in the Early Post-ischemia Phase Inhibits Pro-inflammatory Responses and Promotes Neurogenesis Via the Activation of Innate- and Bone Marrow-Derived Stem Cells in Rats.

In the original publication of the article, the second author (Keiko T. Kitazato) was missing.

Treatment with the PPARγ Agonist Pioglitazone in the Early Post-ischemia Phase Inhibits Pro-inflammatory Responses and Promotes Neurogenesis Via the Activation of Innate- and Bone Marrow-Derived Stem Cells in Rats.

Neurogenesis is essential for a good post-stroke outcome. Exogenous stem cells are currently being tested to promote neurogenesis after stroke. Elsewhere, we demonstrated that treatment with the PPARγ agonist pioglitazone (PGZ) before cerebral ischemia induction reduced brain damage and activated survival-related genes in ovariectomized (OVX) rats. Here, we tested our hypothesis that post-ischemia treatment with PGZ inhibits brain damage and contributes to neurogenesis via activated stem cells. Bone marrow (BM) cells of 7-week-old Wistar female rats were replaced with BM cells from green fluorescent protein-transgenic (GFP+BM) rats. Three weeks later, they were ovariectomized (OVX/GFP+BM rats). We subjected 7-week-old Wistar male and 13-week-old OVX/GFP+BM rats to 90-min cerebral ischemia. Male and OVX/GFP+BM rats were divided into two groups, one was treated with PGZ (2.5 mg/kg/day) and the other served as the vehicle control (VC). In both male and OVX/GFP+BM rats, post-ischemia treatment with PGZ reduced neurological deficits and the infarct volume. In male rats, PGZ decreased the mRNA level of IL-6 and M1-like macrophages after 24 h. In OVX/GFP+BM rats, PGZ augmented the proliferation of resident stem cells in the subventricular zone (SVZ) and the recruitment of GFP+BM stem cells on days 7-14. Both types of proliferated stem cells migrated from the SVZ into the peri-infarct area. There, they differentiated into mature neurons, glia, and blood vessels in association with activated Akt, MAP2, and VEGF. Post-ischemia treatment with PGZ may offer a new avenue for stroke treatment through contribution to neuroprotection and neurogenesis.

Bazedoxifene, a selective estrogen receptor modulator, reduces cerebral aneurysm rupture in Ovariectomized rats.

BACKGROUND: Estrogen deficiency is thought to be responsible for the higher frequency of aneurysmal subarachnoid hemorrhage in post- than premenopausal women. Estrogen replacement therapy appears to reduce this risk but is associated with significant side effects. We tested our hypothesis that bazedoxifene, a clinically used selective estrogen receptor (ER) modulator with fewer estrogenic side effects, reduces cerebral aneurysm rupture in a new model of ovariectomized rats. METHODS: Ten-week-old female Sprague-Dawley rats were subjected to ovariectomy, hemodynamic changes, and hypertension to induce aneurysms (ovariectomized aneurysm rats) and treated with vehicle or with 0.3 or 1.0 mg/kg/day bazedoxifene. They were compared with sham-ovariectomized rats subjected to hypertension and hemodynamic changes (HT rats). The vasoprotective effects of bazedoxifene and the mechanisms underlying its efficacy were analyzed. RESULTS: During 12 weeks of observation, the incidence of aneurysm rupture was 52% in ovariectomized rats. With no effect on the blood pressure, treatment with 0.3 or 1.0 mg/kg/day bazedoxifene lowered this rate to 11 and 17%, almost the same as in HT rats (17%). In ovariectomized rats, the mRNA level of ERα, ERß, and the tissue inhibitor of metalloproteinase-2 was downregulated in the cerebral artery prone to rupture at 5 weeks after aneurysm induction; the mRNA level of interleukin-1ß and the matrix metalloproteinase-9 was upregulated. In HT rats, bazedoxifene restored the mRNA level of ERα and ERß and decreased the level of interleukin-1ß and matrix metalloproteinase-9. These findings suggest that bazedoxifene was protective against aneurysmal rupture by alleviating the vascular inflammation and degradation exacerbated by the decrease in ERα and ERß. CONCLUSIONS: Our observation that bazedoxifene decreased the incidence of aneurysmal rupture in ovariectomized rats warrants further studies to validate this response in humans.

Hyperhomocysteinemia induced by excessive methionine intake promotes rupture of cerebral aneurysms in ovariectomized rats.

BACKGROUND: Hyperhomocysteinemia (HHcy) is associated with inflammation and a rise in the expression of matrix metalloproteinase-9 (MMP-9) in the vascular wall. However, the role of HHcy in the growth and rupture of cerebral aneurysms remains unclear. METHODS: Thirteen-week-old female Sprague-Dawley rats were subject to bilateral ovariectomy and ligation of the right common carotid artery and fed an 8 % high-salt diet to induce cerebral aneurysms. Two weeks later, they underwent ligation of the bilateral posterior renal arteries. They were divided into two groups and methionine (MET) was or was not added to their drinking water. In another set of experiments, the role of folic acid (FA) against cerebral aneurysms was assessed. RESULTS: During a 12-week observation period, subarachnoid hemorrhage due to aneurysm rupture was observed at the anterior communicating artery (AcomA) or the posterior half of the circle of Willis. HHcy induced by excessive MET intake significantly increased the incidence of ruptured aneurysms at 6-8 weeks. At the AcomA of rats treated with MET, we observed the promotion of aneurysmal growth and infiltration by M1 macrophages. Furthermore, the mRNA level of MMP-9, the ratio of MMP-9 to the tissue inhibitor of metalloproteinase-2, and the level of interleukin-6 were higher in these rats. Treatment with FA abolished the effect of MET, suggesting that the inflammatory response and vascular degradation at the AcomA is attributable to HHcy due to excessive MET intake. CONCLUSIONS: We first demonstrate that in hypertensive ovariectomized rats, HHcy induced by excessive MET intake may be associated with the propensity of the aneurysm wall to rupture.

The accumulation of brain water-free sodium is associated with ischemic damage independent of the blood pressure in female rats.

Estrogen deficiency worsens ischemic stroke outcomes. In ovariectomized (OVX(+)) rats fed a high-salt diet (HSD), an increase in the body Na(+)/water ratio, which characterizes water-free Na(+) accumulation, was associated with detrimental vascular effects independent of the blood pressure (BP). We hypothesized that an increase in brain water-free Na(+) accumulation is associated with ischemic brain damage in OVX(+)/HSD rats. To test our hypothesis we divided female Wistar rats into 4 groups, OVX(+) and OVX(-) rats fed HSD or a normal diet (ND), and subjected them to transient cerebral ischemia. The brain Na(+)/water ratio was increased even in OVX(+)/ND rats and augmented in OVX(+)/HSD rats. The increase in the brain Na(+)/water ratio was positively correlated with expansion of the cortical infarct volume without affecting the BP. Interestingly, OVX(+) was associated with the decreased expression of ATP1α3, a subtype of the Na(+) efflux pump. HSD increased the expression of brain Na(+) influx-related molecules and the mineralocorticoid receptor (MR). The pretreatment of OVX(+)/HSD rats with the MR antagonist eplerenone reduced brain water-free Na(+) accumulation, up-regulated ATP1α3, down-regulated MR, and reduced the cortical infarct volume. Our findings show that the increase in the brain Na(+)/water ratio elicited by estrogen deficiency or HSD is associated with ischemic brain damage BP-independently, suggesting the importance of regulating the accumulation of brain water-free Na(+). The up-regulation of ATP1α3 and the down-regulation of MR may provide a promising therapeutic strategy to attenuate ischemic brain damage in postmenopausal women.

Protective Role of Peroxisome Proliferator-Activated Receptor-γ in the Development of Intracranial Aneurysm Rupture.

BACKGROUND AND PURPOSE: Inflammation is emerging as a key component of the pathophysiology of intracranial aneurysms. Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear hormone receptor of which activation modulates various aspects of inflammation. METHODS: Using a mouse model of intracranial aneurysm, we examined the potential roles of PPARγ in the development of rupture of intracranial aneurysm. RESULTS: A PPARγ agonist, pioglitazone, significantly reduced the incidence of ruptured aneurysms and the rupture rate without affecting the total incidence aneurysm (unruptured aneurysms and ruptured aneurysms). PPARγ antagonist (GW9662) abolished the protective effect of pioglitazone. The protective effect of pioglitazone was absent in mice lacking macrophage PPARγ. Pioglitazone treatment reduced the mRNA levels of inflammatory cytokines (monocyte chemoattractant factor-1, interleukin-1, and interleukin-6) that are primarily produced by macrophages in the cerebral arteries. Pioglitazone treatment reduced the infiltration of M1 macrophage into the cerebral arteries and the macrophage M1/M2 ratio. Depletion of macrophages significantly reduced the rupture rate. CONCLUSIONS: Our data showed that the activation of macrophage PPARγ protects against the development of aneurysmal rupture. PPARγ in inflammatory cells may be a potential therapeutic target for the prevention of aneurysmal rupture.

PPARγ-Dependent and -Independent Inhibition of the HMGB1/TLR9 Pathway by Eicosapentaenoic Acid Attenuates Ischemic Brain Damage in Ovariectomized Rats.

High mobility group box 1 (HMGB1) elevation after cerebral ischemia activates inflammatory pathways via receptors such as the receptor for advanced glycation end products (RAGE) and toll-like receptors (TLRs) and leads to brain damage. Eicosapentaenoic acid (EPA), a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, attenuates postischemic inflammation and brain damage in male animals. However, postischemic HMGB1 signaling and the effects of EPA on ovariectomized (OVX(+)) rats remain unclear. We hypothesized that EPA attenuates brain damage in OVX(+) rats via the inhibition of HMGB1 signaling in a PPARγ-dependent manner. Seven-week-old female Sprague-Dawley rats were divided into 3 groups; nonovariectomized (OVX(-)) rats and EPA-treated and EPA-untreated OVX(+) rats before cerebral ischemia induction. Another set of EPA-treated OVX(+) rats was injected with the PPARγ inhibitor GW9662. OVX(+) decreased the messenger RNA level of PPARγ and increased that of HMGB1, RAGE, TLR9, and tumor necrosis factor alpha (TNFα) in parallel with ischemic brain damage. EPA restored the PPARγ expression, downregulated the HMGB1 signal-related molecules, and attenuated the ischemic brain damage. Neither OVX(+) nor EPA affected the expression of TLR2 or TLR4. Interestingly, GW9662 partially abrogated the EPA-induced neuroprotection and the downregulation of RAGE and TLR9. In contrast, GW9662 did not affect HMGB1 or TNFα. These results suggest that EPA exerts PPARγ-dependent and PPARγ-independent effects on postischemic HMGB1/TLR9 pathway. The cortical infarct volume exacerbated by OVX(+) is associated with the upregulation of the HMGB1/TLR9 pathway. Suppression of this pathway may help to limit ischemic brain damage in postmenopausal women.

Improvement of Plasma Biomarkers after Switching Stroke Patients from Other Angiotensin II Type I Receptor Blockers to Olmesartan.

BACKGROUND: Managing hypertension is crucial for preventing stroke recurrence. Some stroke patients experience resistant hypertension. In our experimental stroke model, olmesartan increased the expression of angiotensin (Ang) II converting enzyme-2. We hypothesized that switching to olmesartan affects biomarkers and the blood pressure (BP) in stroke patients whose BP is insufficiently controlled by standard doses of Ang II type I receptor blockers (ARBs) other than olmesartan. METHODS: We recruited 25 patients to study our hypothesis. All had a history of stroke or silent cerebral infarction. We switched them to olmesartan (10-40 mg per day) for 12 weeks and determined their plasma level of Ang-(1-7), peroxiredoxin, oxidized low-density lipoprotein (oxLDL)/ß-2-glycoprotein I (ß2GPI) complex, adiponectin, high mobility group box 1 (HMGB1), and tumor necrosis factor-α (TNFα) and recorded their BP before and after olmesartan treatment. RESULTS: After switching the patients to olmesartan, their plasma level of Ang-(1-7) as a vasoprotective indicator and adiponectin regulating metabolic syndrome was increased, and peroxiredoxin and the oxLDL/ß2GPI complex indicating its antioxidative stress and its proatherogenicity were lower than their baseline. This suggests that olmesartan may be more effective than other ARBs to improve these conditions. Neither HMGB1 nor TNFα reflecting an inflammatory response was affected, suggesting that the anti-inflammatory effects of olmesartan are similar to those of other ARBs. The recommended BP (<140/90) was obtained in 10 of the 25 patients after switching to olmesartan. No adverse events occurred. CONCLUSIONS: Switching from other ARBs to olmesartan may be a promising therapeutic option in patients with resistant hypertension.

Angiotensin-(1-7) protects against the development of aneurysmal subarachnoid hemorrhage in mice.

Angiotensin-(1-7) (Ang-(1-7)) can regulate vascular inflammation and remodeling, which are processes that have important roles in the pathophysiology of intracranial aneurysms. In this study, we assessed the effects of Ang-(1-7) in the development of intracranial aneurysm rupture using a mouse model of intracranial aneurysms in which aneurysmal rupture (i.e., aneurysmal subarachnoid hemorrhage) occurs spontaneously and causes neurologic symptoms. Treatment with Ang-(1-7) (0.5 mg/kg/day), Mas receptor antagonist (A779 0.5 mg/kg/day or 2.5 mg/kg/day), or angiotensin II type 2 receptor (AT2R) antagonist (PD 123319, 10 mg/kg/day) was started 6 days after aneurysm induction and continued for 2 weeks. Angiotensin-(1-7) significantly reduced the rupture rate of intracranial aneurysms without affecting the overall incidence of aneurysms. The protective effect of Ang-(1-7) was blocked by the AT2R antagonist, but not by the Mas receptor antagonist. In AT2R knockout mice, the protective effect of Ang-(1-7) was absent. While AT2R mRNA was abundantly expressed in the cerebral arteries and aneurysms, Mas receptor mRNA expression was very scarce in these tissues. Angiotensin-(1-7) reduced the expression of tumor necrosis factor-α and interleukin-1ß in cerebral arteries. These findings indicate that Ang-(1-7) can protect against the development of aneurysmal rupture in an AT2R-dependent manner.

Blocking of the interaction between Wnt proteins and their co-receptors contributes to the anti-tumor effects of adenovirus-mediated DKK3 in glioblastoma.

The effect of the third member of the Dickkopf family (DKK3) in the Wnt pathway in glioblastoma remains unclear. We first demonstrated the non-specific interaction of Wnt3a and Wnt5a with the receptors LRP6 and ROR2 and the up-regulation of the Wnt pathway in glioblastoma cells. We used an adenovirus vector and found that an increase in DKK3 protein attenuated the expression of Wnt3a, Wnt5a and LRP6, but not of ROR2, and their interaction, thereby affecting both canonical- and non-canonical Wnt downstream cascades. This produced anti-tumor effects in GBM xenograft models. The suppression of Wnt pathways upstream by DKK3 may have promise for the treatment of glioblastoma.

Roles of estrogen in the formation of intracranial aneurysms in ovariectomized female mice.

BACKGROUND: Epidemiological studies have indicated that postmenopausal women have a higher incidence of intracranial aneurysms than men in the same age group. OBJECTIVE: To investigate whether estrogen or estrogen receptors (ERs) mediate protective effects against the formation of intracranial aneurysms. METHODS: Intracranial aneurysms were induced in mice by combining a single injection of elastase into the cerebrospinal fluid with deoxycorticosterone acetate salt hypertension. The mice were treated with estrogen (17ß-estradiol), an ERα agonist (propyl pyrazole triol), and an ERß agonist (diarylpropionitrile) with and without a nitric oxide synthase inhibitor. RESULTS: The ovariectomized female mice had a significantly higher incidence of aneurysms than the male mice, which was consistent with findings in previous epidemiological studies. In ovariectomized female mice, an ERß agonist, but not an ERα agonist or 17ß-estradiol, significantly reduced the incidence of aneurysms. The protective effect of the ERß agonist was absent in the ovariectomized ERß knockout mice. The protective effect of the ERß agonist was negated by treatment with a nitric oxide synthase inhibitor. CONCLUSION: The effects of sex, menopause, and estrogen treatment observed in this animal study were consistent with previous epidemiological findings. Stimulation of estrogen receptor-ß was protective against the formation of intracranial aneurysms in ovariectomized female mice.

Estrogen protects against intracranial aneurysm rupture in ovariectomized mice.

Clinical observations suggest that postmenopausal women have a higher incidence of aneurysmal rupture than premenopausal women. We hypothesize that a relative deficiency in estrogen may increase the risks of aneurysmal growth and subarachnoid hemorrhage in postmenopausal women. We assessed the effects of estrogen and selective estrogen receptor subtype agonists on the development of aneurysmal rupture in ovariectomized female mice. We used an intracranial aneurysm mouse model that recapitulates the key features of human intracranial aneurysms, including spontaneous rupture. Ten- to 12-week-old ovariectomized female mice received treatment with estrogen, nonselective estrogen receptor antagonist, estrogen receptor-α agonist, or estrogen receptor-ß agonist starting 6 days after aneurysm induction so that the treatments affected the development of aneurysmal rupture without affecting aneurysmal formation. Estrogen significantly reduced the incidence of ruptured aneurysms and rupture rates in ovariectomized mice. Nonselective estrogen receptor antagonist abolished the protective effect of estrogen. Although estrogen receptor-α agonist did not affect the incidence of ruptured aneurysms or rupture rates, estrogen receptor-ß agonist prevented aneurysmal rupture without affecting the formation of aneurysms. The protective role of estrogen receptor-ß agonist was abolished by the inhibition of nitric oxide synthase. We showed that estrogen prevented aneurysmal rupture in ovariectomized female mice. The protective effect of estrogen seemed to occur through the activation of estrogen receptor-ß, a predominant subtype of estrogen receptor in human intracranial aneurysms and cerebral arteries.