NNS 2015 Program & Abstract Book

C7-27

CCL2 LEVELS IN CSF AND ITS CORRELATION WITH

BLAST-INDUCED NEUROTRAUMA IN RATS

Ying Wang

, Yanling Wei, Samuel Oguntayo, Donna Wilder,

Peethambaran Arun, Irene Gist, Joseph Long

Walter Reed Army Institute of Research, Blast-Induced Neurotrauma

Branch, Silver Spring, USA

Chemokines and their receptors are of particular interest in the milieu

of immune responses elicited in the CNS in response to trauma. The

chemokine-mediated accumulation of inflammatory cells in the brain

parenchyma is a critical step in the pathogenesis of neuroin-

flammatory diseases. The neuroinflammatory chemokine ligand 2

(Ccl2) is primarily secreted by blood leukocytes, astrocytes, microglia

as well as neurons and has been implicated in the pathogenesis of

Alzheimer’s disease, brain ischemia and other neurodegenerative

diseases. Its role(s) in neurodegeneration and/or neurorestoration

after injury remain an area of exploration. Using a rat model of blast-

induced traumatic brain injury utilizing an air-driven shock tube, we

have investigated the time-course of Ccl2 accumulation in the CSF

following single and repeated blast exposures in association with

neuro-motor coordination disruptions, inflammatory gene and pro-

tein expression changes, and neuropathological changes evoked by

these insults. The results reveal that repeated blast exposures caused

appreciably greater functional deficits, pathological and biochemical

changes compared to a single blast. In addition, acute increases in

CSF Ccl2 levels occurred in a severity-dependent manner, suggest-

ing that this response might provide a biological dosimeter following

blast exposure. Paralleling its proposed roles in other neurodegen-

erative disorders, sustained high levels of Ccl2 and increases in its

receptor expression in the CNS after blast may contribute to neu-

rodegeneration including chronic traumatic encephalopathy, and

therefore should be recognized as a potentially important target for

therapeutic intervention.

Keywords: Blast, Neurotrauma, Chemokine, CSF

C7-28

HYPOXEMIA AND HEMORRHAGIC SHOCK DELAY IN-

FLAMMATION AND GFAP-DEGRADATION IN RAT PENE-

TRATING BALLISTIC-LIKE BRAIN INJURY

Angela Boutte

, Bernard Wilfred, Shonnette Grant, Brittany

Abbatiello, Katherine Cardiff, Deborah Shear, Frank Tortella,

LaiYee Leung

Walter Reed Army Institute of Research, Brain Trauma Neuropro-

tection and Neurorestoration Branch, Silver Spring, USA

Traumatic brain injury (TBI) often occurs in conjunction with addi-

tional trauma. Hypoxemia (HX) and hemorrhagic shock (HS) that

occurs either alone or in concert with TBI may affect acute inflam-

matory cytokine production as well as subsequent astrogliosis or

protein degradation in brain tissues. This preliminary study sought to

quantitate abundance of cytokines and glial fibrillary acidic protein

(GFAP) in brain tissues after HS

HX in the rodent model of severe

TBI/polytrauma. Interleukin (IL)-1

and macrophage inflammatory

protein (MIP)-1

, were measured by ELISA 2h-1day (d) post-injury.

GFAP and breakdown product (BDP) quantitation by Western blot-

ting (arbitrary units, AU) was determined 1–7 days post-injury. Sta-

tistically significant (p

0.05) mean values were determined by 1-or

2-way ANOVA. At 4h post-injury, IL-1

progressively increased and

remained elevated in injured groups (0.06 pg/mL in PBBI, 0.07 pg/mL

in PBBI

HS). However, 1d after injury only PBBI

led to an increase of IL-1

(0.04 pg/mL, vs. Sham and PBBI). The

PBBI-mediated rise of MIP-1

2h (0.27 pg/mL, vs. Sham) was

somewhat abrogated in PBBI

HS cohorts (0.14 pg/mL, vs.

PBBI). MIP-1

was significantly upregulated in PBBI and PBBI

HS (0.13–0.18 pg/mL, vs. Sham and HX

HS) 4h post-injury.

After 1d, PBBI led to an increase (0.28 pg/mL, vs. Sham) was, again,

attenuated by PBBI

HS (0.17 pg/mL, vs. PBBI). GFAP and its

BDPs were also differentially affected. As expected based on previous

studies, total GFAP was vastly increased at 2d (6.2AU, vs. Sham) and

remained elevated at 7d (7.5AU, vs. Sham) after PBBI. This increase

in total GFAP was less robust in PBBI

HS (3.7AU, vs. Sham).

GFAP-BDPs increased 1–2 d after HX

HS alone (0.13AU and

0.40AU, vs. Sham), were most robust 2 days after PBBI (5.9AU, vs.

PBBI), but less so in PBBI

HS cohorts (3.3AU, vs. PBBI).

Overall, HX

HS delayed early (2h) PBBI-mediated increases in

IL-1

and MIP-1

and subsequent (2d) total GFAP or GFAP-BDPs.

This data suggests that HX

HS temporarily delays inflammatory

processes.

Keywords: Penetrating, Polytrauma, Hypoxemia, Hemorrhagic

Shock, Cytokines

C7-29

TEMPORAL AND REGIONAL CHANGES IN MICROGLIAL

PROLIFERATION FOLLOWING PENETRATING BALLIS-

TIC-LIKE BRAIN INJURY IN RATS

Sindhu Kizhakke Madathil

, Lai Yee Leung, Katherine Cardiff,

Xiaofang Yang, Frank Tortella, Deborah Shear, Ying Deng-Bryant

Walter Reed Army Institute of Research, BTNN, Silver Spring, USA

Enhanced cellular proliferation that contributes to gliogenesis and

neurogenesis occurs after brain trauma. While post-injury neurogen-

esis stimulates neurorepair, microglial proliferation can cause neu-

roinflammation that may be detrimental to reparative processes. To

design strategies that limit neuroinflammation, we need to understand

the temporal course of microgliosis following brain injury. Here we

examined the effects of penetrating ballistic-like brain injury (PBBI) on

microglial proliferation at various time points (1–14 days) post-injury.

Adult rats were subjected to PBBI or sham craniotomy (n

5–7/

time-point/group). To capture microglial proliferation, rats were in-

jected with BrdU (50 mg/kg

3 times at 4h-intervals) prior to different

euthanization end points. Iba-1/BrdU/DAPI triple labeling was per-

formed to identify proliferating microglia. In sham rats, microglial

proliferation was detected primarily in the dentate gyrus (DG) and

sub-ventricular zone. BrdU positive cells were observed throughout

the hippocampus, cortex and thalamus in PBBI rats indicating a

widespread proliferative response to brain injury. Quantification of

proliferating microglia (BrdU/Iba-1) in DG and hippocampus was

conducted using a fluorescence microscope equipped with multi-

channel filter sets. Although sham rats showed some proliferation,

only a sparse number of proliferating cells were Iba-1 positive indi-

cating no inflammatory response after sham injury. However, fol-

lowing PBBI, both contralateral and ipsilateral DG and hippocampus

showed increased microglial proliferation (p

0.05, compared to

sham) at 2 and 3 days that subsided to sham levels at 7 and 14 days

post-injury. Although a short sustained burst was observed in micro-

glial proliferation, activated microglia at different activation states

(hypertrophied, rod shaped, amoeboid) were present at all the time

points studied. Most notably, ‘‘train-like’’ rod shaped microglia were

observed in brain regions most proximal to the lesion. Overall, our

results indicate robust microglial proliferation and activation after

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