Vascular adhesion protein-1 (VAP-1), also called semicarbazide-sensitive amine oxidase (SSAO), is reported to play an important role in the adhesion and endothelial transmigration of multiple leukocyte subsets (i.e., neutrophils, monocytes, lymphocytes) in peripheral vascular beds. Our laboratory recently reported that pharmacologic blockade of VAP-1/SSAO, during the reperfusion period following transient forebrain ischemia (TFI), prevented neutrophil infiltration into the brain, and was associated with a 6h post-ischemic therapeutic window in animals where heightened neutrophil diapedesis (which begins at ~6h reperfusion) had been documented. These results strongly suggested that post-TFI neutrophil infiltration and neuropathology were linked. However, the rats used in that study (diabetic, estrogen-treated ovariectomized females) are known to exhibit an exaggerated post-ischemic neutrophil infiltration response and, therefore, such findings may not necessarily be taken to suggest a beneficial role for VAP-1/SSAO inhibition over a wide spectrum of rodent models of ischemia/reperfusion. In the present project, we will examine the effect of a highly- selective inhibitor of VAP-1/SSAO, LJP-1586. Treatments will be initiated at 0-24h reperfusion in adult male rats subjected to 1h MCAo (intraluminal suture) and 1-14 days recovery. The proposal is guided by two Specific Aims designed to test the following hypotheses: (1) VAP-1/SSAO blockade will provide long-term neuroprotection (i.e., reduced infarct volumes;improved neurobehavioral function) with extended therapeutic windows that may, in part, be linked to diminished expression/activation of selected adhesion molecules. (2) The neuroprotection will largely involve interference with non- neutrophil leukocyte subsets. Experiments will involve selective depletion of neutrophils (anti-PMNL antibody) and monocytes (liposome-encapsulated clodronate), coupled with analysis of post-MCAo intracerebral expression of neutrophils, hematogenous monocytes, and T-lymphocytes using immunohistochemistry and FACS analyses. Preliminary evidence supports both hypotheses, suggesting a restricted role for neutrophils, but favoring a significant contribution from non-neutrophil subsets (i.e., mononuclear leukocytes) in the neuropathology accompanying temporary MCAo. Published evidence that mononuclear leukocytes do not display increased intracerebral adhesion and transmigration until many hours (even days) following the appearance of neutrophils may account for the long therapeutic windows (6-12h) we have observed in these early experiments (based upon results using 2 different, but selective, VAP- 1/SSAO blockers). The characterization of a validated pharmacologic approach that affects multiple leukocyte subsets, but with limited off-target actions, has substantial translational implications, since it may prove to be efficacious over a wide range of clinical stroke and ischemic presentations.
Post-ischemic brain inflammation can play a major role in the cerebral neuropathology that occurs following stroke. One potentially key player in that inflammatory attack is the leukocyte. These blood-derived cells may enter the brain after a stroke and release neurotoxic agents. The failure of anti-leukocyte strategies in clinical trials to date may, in part, relate to the presence of multiple leukocyte subsets and redundancy in the pathways responsible for their passage into the brain. The present project utilizes a selective pharmacologic approach that targets a novel protein which appears to be important in the trafficking of all leukocyte subsets and, therefore, may prove to have wide-ranging clinical efficacy.
|Xu, Hao-Liang; Pelligrino, Dale A; Paisansathan, Chanannait et al. (2015) Protective role of fingolimod (FTY720) in rats subjected to subarachnoid hemorrhage. J Neuroinflammation 12:16|
|Testai, Fernando D; Xu, Hao-Liang; Kilkus, John et al. (2015) Changes in the metabolism of sphingolipids after subarachnoid hemorrhage. J Neurosci Res 93:796-805|
|Xu, Haoliang; Testai, Fernando D; Valyi-Nagy, Tibor et al. (2015) VAP-1 blockade prevents subarachnoid hemorrhage-associated cerebrovascular dilating dysfunction via repression of a neutrophil recruitment-related mechanism. Brain Res 1603:141-9|
|Xu, Hao-Liang; Garcia, Maggie; Testai, Fernando et al. (2014) Pharmacologic blockade of vascular adhesion protein-1 lessens neurologic dysfunction in rats subjected to subarachnoid hemorrhage. Brain Res 1586:83-9|
|Vetri, Francesco; Chavez, Rafael; Xu, Hao-Liang et al. (2013) Complex modulation of the expression of PKC isoforms in the rat brain during chronic type 1 diabetes mellitus. Brain Res 1490:202-9|
|Watcharotayangul, Jittiya; Mao, Lizhen; Xu, Haoliang et al. (2012) Post-ischemic vascular adhesion protein-1 inhibition provides neuroprotection in a rat temporary middle cerebral artery occlusion model. J Neurochem 123 Suppl 2:116-24|
|Pelligrino, Dale A; Vetri, Francesco; Xu, Hao-Liang (2011) Purinergic mechanisms in gliovascular coupling. Semin Cell Dev Biol 22:229-36|
|Paisansathan, Chanannait; Xu, Haoliang; Vetri, Francesco et al. (2010) Interactions between adenosine and K+ channel-related pathways in the coupling of somatosensory activation and pial arteriolar dilation. Am J Physiol Heart Circ Physiol 299:H2009-17|
|Shen, Bin; Vetri, Francesco; Mao, Lizhen et al. (2010) Aldose reductase inhibition ameliorates the detrimental effect of estrogen replacement therapy on neuropathology in diabetic rats subjected to transient forebrain ischemia. Brain Res 1342:118-26|
|Paulson, Olaf B; Hasselbalch, Steen G; Rostrup, Egill et al. (2010) Cerebral blood flow response to functional activation. J Cereb Blood Flow Metab 30:2-14|
Showing the most recent 10 out of 11 publications