脳梗塞モデルラットにおける虚血後の時期依存的な抗炎症性M2マクロファージ活性化変調の役割

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

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

Rupture related to site-specific MMP-9 elevation

The pathogenesis of subarachnoid hemorrhage (SAH)remains unclear. No models of cerebral aneurysms elicited solely by surgical procedures and diet have been established.Elsewhere we reported that only few rats in our original rat aneurysm model manifested rupture at the anterior-and posterior Willis circle (AW, PW) and thatmany harbored unruptured aneurysms at the anterior cerebral artery-olfactory artery bifurcation (ACA-OA). This suggests that rupture was site-specific. To test our hypothesis that a site-specific responseto hemodynamic changes is associated with aneurysmal rupture, we modified our original aneurysm model by altering the hemodynamics. During 90-day observation, the incidenceof ruptured aneurysms at the AW and PWwas significantly increasedand the high incidence of unruptured aneurysms at the ACA-OA persisted. This phenomenon was associatedwith an increase in the blood flow volume (BFVo). Notably, the level of matrix metalloproteinase(MMP)-9 associated with interleukin (IL)-1βwas augmented by the increase in the BFVo, suggesting that these molecules exacerbated the vulnerability of the aneurysmal wall. The current study first demonstrates that a site-specificincrease in IL-1β and MMP-9 elicited by hemodynamic changes is associated with rupture. Our novel rat model of rupture may help to developpharmaceutical approaches to prevent rupture

Site-specific elevation of interleukin-1β and matrix metalloproteinase-9 in the Willis circle by hemodynamic changes is associated with rupture in a novel rat cerebral aneurysm model

The pathogenesis of subarachnoid hemorrhage remains unclear. No models of cerebral aneurysms elicited solely by surgical procedures and diet have been established. Elsewhere we reported that only few rats in our original rat aneurysm model manifested rupture at the anterior and posterior Willis circle and that many harbored unruptured aneurysms at the anterior cerebral artery-olfactory artery bifurcation. This suggests that rupture was site-specific. To test our hypothesis that a site-specific response to hemodynamic changes is associated with aneurysmal rupture, we modified our original aneurysm model by altering the hemodynamics. During 90-day observation, the incidence of ruptured aneurysms at the anterior and posterior Willis circle was significantly increased and the high incidence of unruptured aneurysms at the anterior cerebral artery-olfactory artery persisted. This phenomenon was associated with an increase in the blood flow volume. Notably, the level of matrix metalloproteinase-9 associated with interleukin-1β was augmented by the increase in the blood flow volume, suggesting that these molecules exacerbated the vulnerability of the aneurysmal wall. The current study first demonstrates that a site-specific increase in interleukin-1β and matrix metalloproteinase-9 elicited by hemodynamic changes is associated with rupture. Our novel rat model of rupture may help to develop pharmaceutical approaches to prevent rupture