icatibant and Brain-Ischemia

Tissue kallikrein is a serine proteinase capable of cleaving kininogen substrate to produce the potent vasodilator kinin peptide. Kinin mediates a complex set of physiological actions through its receptor signaling. Systemic delivery of the kallikrein gene in an adenoviral vector significantly reduced stroke-induced mortality rate, blood pressure elevation, and aortic hypertrophy in hypertensive Dahl-salt sensitive rats fed a high salt diet. Using a focal cerebral ischemic rat model induced by middle cerebral artery occlusion, intravenous or intracerebroventricular kallikrein gene delivery significantly reduced ischemia/repefusion (I/R)-induced neurological deficits, cerebral infarction, neuronal and glial cell apoptosis, and inflammatory cell infiltration, while promoting angiogenesis and neurogenesis in the ischemic brain. A continuous infusion of a sub-depressor dose of tissue kallikrein protein through implanted minipump decreased I/R-induced neurological dysfunction and cerebral infarction, inflammation and oxidative stress independent of kallikrein's blood pressure-lowering effect. Moreover, kallikrein offered neuroprotection even when delivered at one day after the onset of stroke. Kallikrein's protective effects were blocked by the kinin B2 receptor antagonist icatibant. The role of the kinin B2 receptor in mediating the protective effect against ischemic brain injury was further confirmed by increases in mortality rate and post-ischemic brain injury in kinin B2 receptor-deficient mice. Taken together, these results suggest a novel function of kallikrein as an anti-inflammatory and anti-oxidative agent in protecting the brain against ischemic stroke-induced injuries. These findings also raise the possibility that tissue kallikrein may have value in the treatment of acute ischemic stroke.

Topics: Adenoviridae; Animals; Anti-Inflammatory Agents; Antioxidants; Apoptosis; Bradykinin; Brain Ischemia; Cerebral Infarction; Genetic Therapy; Genetic Vectors; Humans; Inflammation; Kinins; Mice; Neovascularization, Pathologic; Neurons; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Inbred Dahl; Receptors, Peptide; Reperfusion Injury; Salts; Signal Transduction; Stroke; Tissue Kallikreins

Free radical generation is a key event in cerebral reperfusion injury. Bradykinin (Bk) and interleukin-1β (IL-1β) have both been implicated in edema formation after stroke, although acute Bk application itself results in only a modest permeability increase. We have investigated the molecular mechanism by assessing the permeability of single pial venules in a stroke model. Increased permeability on reperfusion was dependent on the duration of ischemia and was prevented by applying the B(2) receptor antagonist HOE 140. Postreperfusion permeability increases were mimicked by applying Bk (5μM) for 10 min and blocked by coapplying the IL-1 receptor antagonist with Bk. Furthermore, 10 min pretreatment with IL-1β resulted in a 3 orders of magnitude leftward shift of the acutely applied Bk concentration-response curve. The left shift was abolished by scavenging free radicals with superoxide dismutase and catalase. Apocynin coapplied with IL-1β completely blocked the potentiation, implying that NADPH oxidase assembly is the immediate target of IL-1β. In conclusion, this is first demonstration that bradykinin, released during cerebral ischemia, leads to IL-1β release, which in turn activates NADPH oxidase leading to blood-brain barrier breakdown.

Topics: Acetophenones; Animals; Bradykinin; Bradykinin Receptor Antagonists; Brain; Brain Ischemia; Capillary Permeability; Catalase; Enzyme Activation; Female; Free Radical Scavengers; Interleukin-1beta; Male; Microspheres; NADPH Oxidases; Rats; Rats, Wistar; Reactive Oxygen Species; Reperfusion Injury; Signal Transduction; Superoxide Dismutase

Systemic or local delivery of human tissue kallikrein gene (hTK) has been shown to be an effective strategy to alleviate cerebral ischemia/reperfusion (I/R) injury, and tissue kallikrein (TK) administration can suppress glutamate- or acidosis-mediated neurotoxicity in vitro. In the present study, the role of TK in hypoxia/reoxygenation (H/R) induced neuronal cell death was investigated. We found that TK administration could remarkably alleviate H/R-induced neuronal injury by reduction of LDH release and promotion of neuron viability. The protective effects of TK could be counteracted by bradykinin B2 receptor (B2R) antagonist HOE140, which could suppress up-regulation of TK on the ERK signal pathway under H/R condition. These results indicate that TK plays an important role in preventing neurons from H/R damage at least partially through the TK-B2R-ERK1/2 pathway.

Topics: Animals; Bradykinin; Bradykinin Receptor Antagonists; Brain Ischemia; Cells, Cultured; Cerebral Cortex; Cytoprotection; Humans; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neurons; Rats; Reperfusion Injury; Tissue Kallikreins

Biomacromolecule like exogenous Kallikrein is difficult to pass through biomembrane and blood brain barrier. So, the use of exogenous Kallikrein for the therapy of nervous system diseases is restricted. We constructed the Protein Transduction Domain-Kallikrein (PTD-Kallikrein), checked its function of penetration and biotoxicity, and observed its influence on neurons and ischemic brain tissues.. PTD-Kallikrein (tissue kallikrein) was prepared by chemical synthesis. After PTD-Kallikrein injected 2.5 hours, rats brains were taken out and contents of Kallikrein were quantitated to observe the function of passing through blood brain barrier. Cell survival rate were measured by XTT methods to determine the peptide's biotoxicity. Apoptosis were inspected by TUNEL. PTD-Kallikrein was administrated immediately after cerebral ischemia. 24h later, infarct volume was determined by TTC stain and IL-1beta, TNF-alpha as well as PGE2 were measured by ELISA.. 1. PTD-Kallikrein can pass through the biomembrane and blood brain barrier; 2. PTD-Kallikrein itself has no obviously biotoxicity. 3. PTD-Kallikrein increases cell survival rate, decreases neurons apoptosis during OGD/recovery; 4. HOE140 inhibits the effects of PTD-Kallikrein. 5. PTD-Kallikrein improves neurological impairment, decreases the infarct volume, and inhibits the release of IL-1beta, TNF-alpha, PGE2. 6. HOE140 inhibits the effects of PTD-Kallikrein on ischemia-reperfusion injury.. 1. PTD-Kallikrein can pass through the biomembrane and BBB efficiently and itself has no obviously biotoxicity. 2. PTD-Kallikrein has neuroprotective effect on neurons and cerebral ischemia injury. 3. PTD-Kallikrein is partially mediated by B2 receptors.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Blood-Brain Barrier; Bradykinin; Brain; Brain Ischemia; Cell Membrane Permeability; Cell Survival; Cells, Cultured; Dinoprostone; Interleukin-1beta; Male; Neurons; Rats; Rats, Wistar; Recombinant Fusion Proteins; Reperfusion Injury; Tissue Kallikreins; Tumor Necrosis Factor-alpha