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suggests that both iron and NOX4 are involved in this response and

targeting of NOX4 may have therapeutic benefits.

Keywords: Microglia, Inflammation, NOX4, Iron

C7-16

ALTERATIONS OF PROTEASOME DYNAMICS FOLLOW-

ING TRAUMATIC BRAIN INJURY

Kasey Moritz

, Barrington Burnett

Uniformed Services University of the Health Sciences, Neuroscience,

Rockville, USA

Traumatic brain injury (TBI) is a debilitating disorder that can per-

manently impair brain function leading to long term cognitive, af-

fective and motor deficits. The primary injury often leads to numerous

secondary effects including microglia activation, inflammation and

disturbances in protein homeostasis. By selectively targeting proteins

and peptides for degradation, the ubiquitin-proteasome system (UPS)

helps maintain optimal levels of cellular proteins and in so doing

mitigates some of the primary and secondary effects of brain injuries.

The 26S proteasome is a dynamic enzyme complex that responds to

cellular injury by altering the rate of protein degradation and level of

antigen presentation. However, the molecular mechanisms controlling

these processes remain unclear. We performed controlled cortical

impact injury on adult mice to assess proteasome assembly and

function. We found increased expression of the immunoproteasome

catalytic subunits and interferon gamma (IF-g) in injured mice com-

pared to sham controls indicative of a mounting immune response.

Given the role of activated microglia in the CNS immune response,

we investigated proteasome dynamics in BV2 microglia cell line

following activation with interferon gamma IF-g. Using native gel

electrophoresis we found that microglia activation resulted in in-

creased assembly of immunoproteasomes and reduced presence of the

constitutive proteasome. Furthermore, the non-catalytic proteasome

subunits were unchanged and chaperone proteins responsible for de

novo constitutive and immunoproteasome synthesis were unaltered.

Our findings suggest that the 26S proteasome is converted to the

immunoproteasome following injury by substituting the catalytic

subunits in order to facilitate the immune response to trauma.

Keywords: Proteasome, Interferon gamma, microglia

C7-17

MULTIPLE AROMATIZATION MECHANISMS INFLUENCE

MORTALITY AND CNS SECONDARY INJURY PROFILES

AFTER SEVERE TBI

Amy Wagner

1,2

, Raj Kumar

1

, Yvette Conley

3,4

, Patrick Kochanek

3,5

,

Sarah Berga

6

1

Univ Pittsburgh, PhysicalMed/Rehab, Pittsburgh, USA

2

Univ Pittsburgh, Neuroscience, Pittsburgh, USA

3

Univ Pittsburgh, Safar Center, Pittsburgh, USA

4

Univ Pittsburgh, Nursing, Pittsburgh, USA

5

Univ Pittsburgh, Critical Care, Pittsburgh, USA

6

Wake Forest Health System, Obstetrics/Gynecology, Winston-Salem,

USA

Although estradiol (E2) has several neuroprotective qualities, high

systemic E2 levels can occur early after severe TBI, despite the uni-

form occurrence of acute hypogonadotropic hypogonadism, and can

contribute to poor outcome. To better understand the production (via

aromatization) and complexity of E2 in TBI, we evaluated 1) systemic

and CNS contributors to E2 production, 2) E2 associations with

6-month mortality, and 3) CNS E2 associations with CNS s100b,

cytochrome-C, and inflammatory load. We studied 187 subjects with

severe TBI, aromatase genotypes, and available serum and cerebro-

spinal fluid (CSF) samples collected over 5d post-injury for hormone

and TBI biomarkers. After controlling for covariates, serum bio-

markers (E2, estradiol/testosterone (E2:T) ratio, TNF

a

), and ar-

omatase genetics (rs4646), relevant interactions were modeled to

assess 6-month mortality risk. There was a significant interaction

between E2:T ratio*rs4646 where CC homozygotes with higher E2:T

had reduced mortality risk versus A-carriers (p

=

0.001). Also, E2 and

the E2:T ratio*TNF

a

interaction tended to be associated with mor-

tality (p

=

0.06) suggesting unique aromatization mechanisms leading

to serum E2 production. Importantly, aromatization mechanisms that

contributed to serum E2/T and mortality risk accounted for

*

19% of

the variance observed with CSF E/T ratios. A separate CSF and ge-

netics mortality prediction model showed rs4646, rs2470152,

rs2470152*CSF E2:T ratio interaction influenced mortality, where

higher ratios, among those with the rs2470152 risk variant, were

protective (p

=

0.018). Finally, higher covariate adjusted CSF E2/T

ratios were associated with lower CSF inflammation, S100b levels,

and cytochrome-C levels. Together, these data show 1) multiple

mechanisms contribute to aromatization and E2 production after TBI

2) E2 has complex opposing effects on mortality in the periphery vs.

CNS, and 3) CNS E2 protective effects are associated with bio-

chemical evidence of a reduction in secondary injury.

Keywords: rehabilomics, aromatization, modeling, mortality, TBI,

genetics

C7-18

SERUM TUMOR NECROSIS FACTOR-

a

ASSOCIATION

WITH MORTALITY SIX MONTHS AFTER TBI: MECHAN-

ISTIC RELATIONSHIPS WITH ESTRADIOL

Amy Wagner

1,3,4

, Raj Kumar

1

, Anne Ritter

1

, Patrick Kochanek

2,3

,

Sarah Berga

5

1

Univ Pittsburgh, PhysMedicine/Rehab, Pittsburgh, USA

2

Univ Pittsburgh, Critical Care, Pittsburgh, USA

3

Univ Pittsburgh, Safar Center, Pittsburgh, USA

4

Univ Pittsburgh, Neuroscience, Pittsburgh, USA

5

Wake Forest Health System, Obstetrics Gynecology, Winston-Salem,

USA

Traumatic Brain Injury (TBI) causes

*

1/3 of injury-related deaths

yearly in the USA, and there are no approved neuroprotective

therapies, justifying continued study of acute pathophysiological

contributors to mortality. Tumor necrosis factor-

a

(TNF

a

) is a

pleiotropic, pro-inflammatory cytokine that is acutely elevated and a

primary initiator of the immunological response to TBI. TNF

a

is also

critical for aromatization and adipose tissue production of estradiol

(E2), a known mortality marker in TBI. We established how acute

serum TNF

a

measured from samples (collected over the first 5d after

TBI) influenced mortality outcomes, using time-to-event analyses in

a prospective cohort (n

=

130). After quartiling TNF

a

and E2 levels

for the cohort, we determined relationships between acute serum

TNF

a

and 1) serum E2 and 2) cerebrospinal fluid (CSF) TNF

a

, with

respect to mortality. Among a subgroup of survivors (n

=

37), mean

sub-acute (weeks 2–12) serum TNF

a

was explored for relationships

to sub-acute E2. After controlling for covariates, there was a 2-fold

increase in the hazard of death per quartile increase in acute serum

TNF

a

[HR

=

2.00, 95% CI (1.31, 3.08), p

=

0.001]. Acute serum E2

A-92