NNS 2015 Abstract Book

disorders, as well as Traumatic Brain Injury (TBI). TBI induces

cognitive changes affecting millions of people, as well as increased

incidence of age-related neurodegeneration. Evidence from our lab

and others suggests tau that forms on route to NFT formation—

oligomers—are the most toxic tau species. We have shown increased

levels of tau oligomers in neurodegenerative disease brains, as well as

in TBI models. Using immunoprecipitation, we isolated tau oligo-

mers from controlled cortical impact injured mice, fluid percussion

injured and blast injured rat brains. Oligomers were characterized

biochemically and by atomic force microscopy and were injected

bilaterally in the hippocampi of mice overexpressing human tau

(Htau mice). Mice were cognitively evaluated using novel object

recognition and Y-maze tasks and brains were collected following

testing. We found that tau oligomers form as a result of brain injury

in three different rodent models of TBI and accelerated the onset of

cognitive deficits, absent increased levels of cell death, in Htau mice.

As we have seen previously in other diseases, oligomers collected

from TBI can seed the aggregation of tau monomer

in vitro.

Moreover, mice injected with oligomers exhibited elevated levels of

oligomeric tau in multiple brain regions, supporting the prion-like

seeding and propagation capability of TBI-derived oligomeric tau.

Our results suggest that tau oligomers play an important role in the

toxicity underlying TBI, making them a viable therapeutic target for

TBI and in preventing the increased acquisition of neurodegenera-

tive disease later in life. These studies were completed as part of an

interdisciplinary research team funded by The Moody Project for

Translational Traumatic Brain Injury Research.

Keywords: TBI, Tau, Protein aggregation, Tau oligomers, Tau

pathology

B2-09

ACUTE REGION OF INTEREST CHANGES IN KEY BRAIN

INJURYMARKERS FOLLOWINGPENETRATINGBALLISTIC-

LIKE BRAIN INJURY

Casandra Cartagena

, Ying Deng-Bryant, Hye Hwang, Frank

Tortella, Angela Boutte

WRAIR, BTNN, Silver Spring, USA

Penetrating brain injury (PBI) is associated with high mortality and

morbidity. PBI involves accelerated infiltration of peripheral immune

cells and increased edema. However, molecular mechanisms under-

lying PBI are not widely studied. Here we evaluated changes in key

markers of PBI across regions of interest (ROIs) including frontal

cortex (FCx), striatum (St), hippocampus (Hc), and residual midbrain

(RMb), using the model of penetrating ballistic-like brain injury

(PBBI). Injury was induced in anesthetized rats by inserting a probe

through the right FCx and St followed by rapid balloon inflation

causing a temporary cavity. Key injury markers were evaluated 24h

post-PBBI to determine molecular effects in ROIs proximal to the

injury tract (FCx, St) versus surrounding areas (Hc, rMb). Targeted

proteins were glial fibrillary acidic protein (GFAP), GFAP breakdown

products (GFAP-BDPs), spectrin, spectrin breakdown products

(SBDPs), B-cell lymphoma-2 (BCL2), BCL2-associated protein X

(BAX), amyloid associated protein (APP), APP

- and

- C-terminal

fragments (APP

CTF, APP

CTF), and

tau

protein. PBBI ROIs were

compared to comparable Sham ROIs (n

10/group). GFAP levels

increased 60% in FCx (p

0.05) and 53% in St (P

0.05). GFAP-

BDPs levels increased 262% in FCx (p

0.05) and 1342% in St

0.01). Spectrinlevels decreased 75% in FCx (p

0.01) and 53% in

St (p

0.05). SBDPs levels increased 251% in FCx (p

0.01), 431% in

St (p

0.01) and 156% in RMb (p

0.01). BCL2 levels decreased 63%

in FCx (p

0.0001). BAX levels increased 1764% in FCx

0.0001), 222% in Hc (p

0.05), 5869% in St (p

0.0001), and

387% in RMb (p

0.01). No significant changes were detected in APP

or APP

CTF levels. However, APP

CTF levels increased 330% in

FCx (p

0.001) and 1089% in St (p

0.001). Total

tau

levels de-

creased 30% (p

0.01) in FCx. These results indicate that acute (24 h)

alterations in astrogliosis and markers of neurodegeneration are lim-

ited to ROIs proximal to the injury tract. However, structural protein

abnormalities and pro-apoptotic mechanisms expand into surrounding

ROIs. Ongoing studies will evaluate these markers at subacute and

chronic time-points post-PBBI.

Keywords: Amyloid, Tau, GFAP, Spectrin, apoptosis

B2-10

BRAIN CATHEPSIN B IS ELEVATED IN BOTH MILD-

CLOSED AND SEVERE-PENETRATING TRAUMATIC

BRAIN INJURY MODELS

Angela Boutte

, Brittany Abbatiello

, Shonnette Grant

, Gregory

Hook

, Vivian Hook

, Frank Tortella

, Deborah Shear

Walter Reed Army Institute of Research, Brain Trauma Neuropro-

tection and Neurorestoration Branch, Silver Spring, USA

American Life Science Pharmaceuticals, Inc., Research and Devel-

opment, San Diego, USA

University of California, San Diego, Skaggs School of Pharmacy and

Pharmaceutical Sciences, Dept. of Neurosciences, La Jolla, USA

Comprehensive analysis of key mediators involved in traumatic brain

injury (TBI) is tantamount to understanding mechanisms involved in

injury progression. Cathepsin B is a cysteine protease implicated in

several neurodegeneration and TBI models, such as controlled cortical

impact. This preliminary study determined if brain cathepsin B was

up-regulated in penetrating ballistic-like brain injury (PBBI) or re-

peated projectile concussive impact (rPCI). For PBBI and sham/

craniotomy controls, coronal brain tissue sections were isolated at

various time-points post-injury. Repeated (r)PCI was conducted once

daily for 4 consecutive days (d). Control groups received anesthesia

alone. Righting-reflex (RR) was determined immediately after injury.

Select PCI brain tissue regions were collected 1d after the last con-

cussion. Both pro-(

37–43 kDa) and mature (

20–25 kDa) Cathe-

psin B protein levels were determined by western blotting and

densitometry (mean

SEM arbitrary units (AU)). Enzymatic ac-

tivity was determined by generation of amino-methyl coumarin

(AMC). Comparisons between injured and control groups are dis-

cussed (2-tailed, t-Test, p

0.05); correlative analysis is indicated

(1-way, Pearson

). Pro-cathepsin B upregulation in brain slices was

monophasic and peaked 2–3 d after PBBI (13.3

1.2 and

15.2

2.3 AU) compared to Sham (1.2

0.1 to 3.1

1.3

AU). Interestingly, mature cathepsin B was maximally increased 7d

after PBBI (384.1

39.7 AU), versus Sham (174.2

25.4 AU).

In rPCI, pro-cathepsin B was increased to (1.7

0.5 AU) in the

prefrontal cortex (not detectable in sham/anesthesia controls). In this

brain region, mature cathepsin B was

7-fold greater after rPCI

(14.2

3.6 AU) compared to controls (2.2

1.5 AU); proteo-

lytic activity was marginally increased. Surprisingly, cerebellar pro-

teolytic activity increased nearly 3-fold after rPCI (3.0

0.6

moles) compared to anesthesia alone (1.4

0.2

moles), and

positively associated with RR (

= +

0.65, p

0.12). Conversely, de-

creased activity in this region was negatively correlated with RR

(

= -

0.98, p

0.008) among anesthesia controls. These findings

suggest that brain cathepsin B has a role in multiple TBI models and is

linked to neurological deficits.

Keywords: Cathepsin B, Penetrating Ballistic-like Brain Injury,

Projectile Concussive Impact

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