EndothelinA receptor antagonist BSF-208075 causes immune modulation and neuroprotection after stroke in gerbils

RAGE mediates vascular injury and inflammation after global cerebral ischemia

The receptor for advanced glycation end products (RAGE) is a multi-ligand receptor involved in a diverse range of pathological conditions. To analyze the roles of RAGE and its decoy receptor, endogenous secretory RAGE (esRAGE), in the global cerebral ischemia, three different mouse cohorts, wild-type, RAGE⁻/⁻, and esRAGE transgenic (Tg) mice were subjected to bilateral common carotid artery occlusion (BCCAO). RT-PCR and immunohistochemical analysis revealed that expression of RAGE was induced in the vascular cells at 12 h, and then in the neurons and glia from 3 to 7 days in the hippocampus after BCCAO. The numbers of surviving neurons in the hippocampal CA1 region were significantly higher in RAGE⁻/⁻ and esRAGE Tg mice than those in wild-type mice in the periods between 24 h and 7 days after BCCAO. Lower levels of 3-nitrotyrosine (3-NT) and higher levels of endothelial nitric oxide synthase (eNOS), together with enlarged vascular areas were observed in RAGE⁻/⁻ and esRAGE Tg mice at 12 h after BCCAO. In the later periods, expressions of glia-derived inflammatory mediators TNFα and inducible nitric oxide synthase (iNOS) were reduced in RAGE⁻/⁻ and esRAGE Tg mice. These results suggest that RAGE may contribute to delayed neuronal death after global cerebral ischemia by enhancing vascular injury and deleterious glia-mediated inflammation.

[Novel immunopathological approaches to pulmonary arterial hypertension]

Inflammation is important for the initiation and the maintenance of vascular remodeling in the most commun animal models of pulmonary hypertension (PH), and its therapeutical targeting blocks PH development in these models. In human, pulmonary vascular lesions of PH are also the source of an intense chemokine production, linked to inflammatory cell recruitment. However, arteritis is uncommon in PH patients. Of note, current PH treatments have immunomodulatory properties. In addition, some studies have shown a correlation between levels of circulating inflammatory mediators and patients' survival. The study of autoimmunity in the pathophysiology of pulmonary arterial hypertension is becoming an area of intense investigation. New immunopathological approaches to PH should allow the development of innovative treatments for this very severe condition.

Clazosentan: a review of subarachnoid hemorrhage data

Clazosentan (Ro 61–1790, VML-588 or AXV-034) is a synthetic endothelin (ET)-receptor antagonist that was derived from one of the first nonselective synthetic ET-receptor antagonists, bosentan. The structural modifications were designed to increase selectivity for the ETA receptor and optimize aqueous solubility, both of which were fulfilled. Selectivity is approximately 1000-fold greater for the ETA receptor with a pA2 in the nanomolar range. The half-life in humans is less than 2 h and the main side effects are headache, nausea and vomiting in clinically important doses, although they are not reported to be a problem in target disease populations. Clazosentan reverses established vasospasm in dogs with subarachnoid hemorrhage (SAH) and in preliminary studies in humans. It also prevents vasospasm in the double hemorrhage model of vasospasm in dogs and significantly decreases angiographic vasospasm after aneurysmal SAH in humans. The doses required are in the range of 5 to 15 mg/h in humans and correspond to effective doses in animal studies. These doses are also associated with relevant plasma and cerebrospinal fluid concentrations of the drug. A dose-finding study of clazosentan for prevention of vasospasm after SAH in humans showed a significant dose-dependent decrease in vasospasm and was favorable enough to lead to a Phase III trial.

A new technique allowing prolonged temporary cerebral artery occlusion

OBJECT

Clipping of complex cerebral aneurysms often requires temporary vessel occlusion. The risk of stroke, however, increases exponentially with occlusion time. The authors hypothesized that prolonged temporary occlusion might be tolerated if the occluded vessels were perfused with cold physiological saline solution (CPSS). A low-flow perfusion rate would permit surgical manipulation of an aneurysm distal to the occlusion.

METHODS

To test this hypothesis, the authors temporarily occluded the middle cerebral artery (MCA) with an endovascular catheter in 6 rats. Three animals, the treatment group, were perfused with 5-ml CPSS/hour through the occluding endovascular catheter into the MCA, and the other 3 served as an ischemic control group. In both groups, the catheter was removed after 90 minutes of occlusion. The brain temperature was monitored with a stereotactically placed probe in the caudate-putamen in 2 separate experimental groups (11 animals).

RESULTS

Magnetic resonance imaging perfusion scanning during vessel occlusion confirmed similar reduction of cerebral blood flow during MCA occlusion in both the simple-occlusion and perfusion-occlusion groups. Magnetic resonance imaging diffusion scans performed 24 hours after temporary occlusion revealed infarcts in the ischemic control group of 138.3 +/- 28.0 mm(3) versus 9.9 +/- 9.9 mm(3) in the cold saline group (p < 0.005). A focal cooling effect during perfusion with CPSS was demonstrated (p < 0.05).

CONCLUSIONS

Prolonged temporary cerebral vessel occlusion can be tolerated using superselective CPSS perfusion through an occluding endovascular catheter into the ischemic territory. This technique could possibly be applied in neurosurgery practice to the management of complex intracranial aneurysms.