Background and Purpose-Although chemokines have been implicated in cardiovascular diseases, few studies have addressed the role of these inflammatory mediators in ischemic stroke. This study tested the hypothesis that RANTES (CCL5; regulated on activation, normal T-cell expressed and secreted) mediates the cerebral microvascular dysfunction, inflammation, and tissue injury induced by brain ischemia and reperfusion. Methods-After 60-minute middle cerebral artery occlusion and reperfusion, the adhesion of leukocytes and platelets in cerebral venules, infarct volume, and blood-brain barrier permeability were measured in wild-type mice (WT), RANTES-deficient mice (RANTES Ϫ/Ϫ ), WT mice transplanted with RANTES Ϫ/Ϫ bone marrow (RANTESϾWT), and control bone marrow chimeras (WTϾWT). The concentration of RANTES and several cytokines was also measured by enzyme-linked immunosorbent assay and a cytometric bead array. Results-The enhanced leukocyte and platelet adhesion, increased blood-brain barrier permeability, and tissue infarction elicited in WT and WTϾWT mice after middle cerebral artery occlusion and reperfusion were significantly blunted in RANTES Ϫ/Ϫ mice. Similar attenuation of the middle cerebral artery occlusion and reperfusion-induced responses were noted in RANTESϾWT chimeras. Although RANTES deficiency did not alter the changes in tissue cytokine levels elicited by middle cerebral artery occlusion and reperfusion, plasma concentrations interleukin-6, interleukin-10, and interleukin-12 were all reduced. Conclusions-These findings implicate blood cell-derived RANTES in the microvascular, inflammatory, and tissue injury responses of the brain to ischemia and reperfusion.

Background and Purpose-Although epidemiological studies reveal an increased incidence of obesity and an association between obesity and the prevalence/severity of ischemic stroke, little is known about the mechanisms that link obesity to ischemic stroke. This study tested the hypothesis that obesity exacerbates the cerebrovascular dysfunction and tissue injury induced by brain ischemia and reperfusion. Methods-The adhesion of leukocytes and platelets in cerebral venules, blood-brain barrier permeability, brain water content, and infarct volume were measured in wild-type, obese (ob/ob), and leptin-reconstituted ob/ob mice subjected to 30 minutes middle cerebral artery occlusion and reperfusion. Tissue and plasma cytokine levels were determined by cytometric bead array, and a role for monocyte chemoattractant protein-1 and interleukin-6 was assessed using blocking antibodies. Results-Compared with wild-type mice, ob/ob exhibited larger increases in leukocyte and platelet adhesion, blood-brain barrier permeability, water content, and infarct volume after middle cerebral artery occlusion-reperfusion. Reconstitution of leptin in ob/ob mice tended to further enhance all reperfusion-induced responses. Ob/ob mice also exhibited higher plasma levels of monocyte chemoattractant protein-1 and interleukin-6 than wild-type mice. Immunoneutralization of monocyte chemoattractant protein-1, but not interleukin-6, reduced infarct volume in ob/ob mice. Conclusions-Obesity worsens the inflammatory and injury responses to middle cerebral artery occlusion and reperfusion by a mechanism independent of leptin deficiency. monocyte chemoattractant protein-1 appears to contribute to the exaggerated responses to ischemic stroke in obese mice.

Changes in mitochondrial genome such as mutation, deletion and depletion are common in cancer and can determine advanced phenotype of cancer; however, detailed mechanisms have not been elucidated. We observed that loss of mitochondrial genome reversibly induced overexpression and activation of proto-oncogenic Ras, especially K-Ras 4A, responsible for the activation of AKT and ERK leading to advanced phenotype of prostate and breast cancer. Ras activation was induced by the overexpression of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR), the rate-limiting enzyme of the mevalonate pathway. Hypoxia is known to induce proteasomal degradation of HMGR. Well differentiated prostate and breast cancer cells with high mitochondrial DNA content consumed a large amount of oxygen and induced hypoxia. Loss of mitochondrial genome reduced oxygen consumption and increased in oxygen concentration in the cells. The hypoxic-to-normoxic shift led to the overexpression of HMGR through inhibiting proteasomal degradation. Therefore, reduction of mitochondrial genome content induced overexpression of HMGR through hypoxic to normoxic shift and subsequently the endogenous induction of the mevalonate pathway activated Ras that mediates advanced phenotype. Reduction of mitochondrial genome content was associated with the aggressive phenotype of prostate cancer in vitro cell line model and tissue specimens in vivo. Our results elucidate a coherent mechanism that directly links the mitochondrial genome with the advanced progression of the disease.