Page 120 - NNS 2014 Program & Abstract Book

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BLOCKING LYSOPHOSPHATIDIC ACID (LPA) INCREASES
SUBVENTRICULAR ZONE PROLIFERATION BUT RE-
DUCES EARLY NEUROBLAST MIGRATION AFTER TBI
McDonald, W.S.1, Sabbadini, R.2, Harris, N.G.1
1University of California, Los Angeles; Department of Neurosurgery,
Los Angeles, USA
2Lpath Inc, San Diego, USA
Lysophosphatidic acid (LPA) is a bioactive phospholipid that increases
locally after injury. LPA can activate early injury responses such as
excitotoxicity, inflammation, gliosis, and necrosis, and can inhibit neu-
ronal differentiation and progenitor survival. It is unknown whether LPA
effects adult neurogenesis after TBI. We have recently demonstrated that
blocking the increase in LPA after controlled cortical impact injury in the
mouse using a monoclonal antibody targeting the bioactive LPA (anti-
LPA) improves behavioral outcome and SVZ neurogenesis. These data
suggest reduction in LPA shortly after injury may improve behavioral
outcome at least partly by inhibiting early neuroblast migration to the
injured cortex. To test this hypothesis, anti-LPA antibody (25 mg/kg) or
the isotype-matched control (n = 6/group) was administered intravenously
to adult C57BL/6 mice, 2 hours after controlled cortical impact injury.
The thymidine analogue CldU (50 mg/kg) was administered 3 times at 4
hour intervals starting 12 hours after the injury and euthanized at 3 days
post injury. The brains were processed for standard double or triple-label
immunohistochemistry to phenotype and then quantify populations of
dividing cells within the subventricular zone (SVZ) and cortex using
stereology. The results revealed a 2-fold increase in dividing neuroblasts
(CldU + /DCX + ) within the SVZ of injured anti-LPA-treated animals
compared to the injured IgG-treated group (P < 0.05). Furthermore, there
was a significant decrease in the total number of dividing cells within the
cortex and in cortical neuroblast in the anti-LPA treated group compared
to the injured controls (P > 0.05) These data suggest that blocking LPA
shortly after injury delays or slows neuroblast migration from the SVZ to
cortex. This would be consistent with overall lower cell death among
progenitors and longer term improvement in recovery. Whether delayed
cell migration and enhanced survival occurs is not known and is currently
being tested. Support: R44NS087641-01
Key words
adult neurogenesis, lysophosphatidic acid, proliferation, SVZ
C2-33
DEGENERATION AND PROTECTION OF AXONAL SUB
DOMAINS AFTER OPTIC NERVE CRUSH
Marin, M.A., Rasband, M.N.
Baylor College of Medicine, Houston, USA
Myelinated axons are divided into several distinct domains, which in-
cludes the axon initial segment (AIS), nodes of Ranvier, paranodes, and
juxtaparanodes. The AIS serves as both a physical barrier between the
axonal and somato-dendritic compartments of the neuron and as the site
of action potential (AP) initiation. Nodes of Ranvier are responsible for
the rapid and efficient propagation of APs along the axon. Disruption of
the AIS or nodes of Ranvier by genetic and/or pharmacological manip-
ulation has a dramatic impact on the central nervous system. With this in
mind, we have designed a series of experiments, which will allow us to
assess the efficacy of neuroprotective paradigms upon axons of the
central nervous system after insult. Using the optic nerve crush injury
model, we have established a timeline for degenerative events of the
nodes of Ranvier of the optic nerve and AIS of retinal ganglion cells. We
have established that loss of nodes of Ranvier begins 6 hours after injury
and progresses both distal and proximal to the injury site. A total loss of
nodes of Ranvier occurs 1 week after injury and persists 1-month post
crush. Loss of AIS in retinal ganglion cells begins 24 hours after injury
and persists 1-month post crush. We have assessed the neuroprotective
efficacy of MDL-28170 - a calpain inhibitor that has been shown to
protect from AIS degeneration after ischemic injury. MDL-28170 spares
nodes of Ranvier and AIS from degeneration 24 hours post injury.
Key words
axon initial segment, beta IV spectrin, nodes of Ranvier, optic nerve
crush
C2-34
THE CYSTEINE PROTEASE CATHEPSIN B IS A KEY DRUG
TARGET AND CYSTEINE PROTEASE INHIBITORS ARE
POTENTIAL THERAPEUTICS FOR TBI
Hook, G.R.1, Yu, J.2,3, Sipes, N.1, Pierschbacher, M.D.1, Hook, V.4,
Kindy, M.S.2,3
1American Life Science Pharmaceuticals, La Jolla, USA
2Medical University of South Carolina, Charleston, USA
3Applied Neurotechnology, Inc., Charleston, USA
4University of California, San Diego, La Jolla, USA
Drug treatments for traumatic brain injury (TBI) may be developed by
validation of new drug targets and demonstration that compounds di-
rected to such targets are efficacious in TBI animal models using clini-
cally relevant methods. The cysteine protease cathepsin B has been
implicated in mediating TBI, but it has not been validated by gene
knockout studies. This investigation evaluated mice with deletion of the
cathepsin B gene receiving controlled cortical impact (CCI) TBI trauma.
Results indicated that knockout of the cathepsin B gene resulted in
amelioration of TBI shown by significant improvement in motor dys-
function, reduced brain lesion volume, greater neuronal density in brain,
and lack of increased pro-apoptotic Bax levels. Notably, oral adminis-
tration of the small molecule cysteine protease inhibitor E64d immedi-
ately after TBI resulted in recovery of TBI-mediated motor dysfunction,
and reduced the increase in cathepsin B activity induced by TBI. The
E64d outcomes were as effective as cathepsin B gene deletion for im-
proving TBI. E64d treatment was effective even when administered 8
hours after injury, indicating a clinically plausible time period for acute
therapeutic intervention. These data demonstrate that a cysteine protease
inhibitor can be orally efficacious in a TBI animal model when admin-
istered at a clinically relevant time point post-trauma, and that E64d-
mediated improvement of TBI is due primarily to inhibition of cathepsin
B activity. Moreover, E64d has clinical potential because it has been
safely used in man. These results validate cathepsin B as a new TBI
therapeutic target.
Key words
cathepsin B, drug, target, TBI
C2-35
EFFICACY OF NEUROPROTECTIVE COMPOUND P7C3-
S243 AFTER BLAST-MEDIATED TRAUMATIC BRAIN
INJURY
Yin, T.C.1, Britt, J.K.1, De Jesu´s-Corte´s, H.2, Genova, R.M.1, Voorhees,
J.R.1, Katzman, A.1, Wassink, C.1, Lu, Y.1, Naidoo, J.2, Dutca, L.M.3,
Harper, M.M.3, McKnight, S.L.2, Ready, J.M.2, Pieper, A.A.1
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