studies

1250A AASLD ABSTRACTS HEPATOLOGY, October, 2015
2141
Inflammasome Activation Due to Vinyl Chloride Metabolite
Exposure in NAFLD Caused by High Fat Diet in Mice.
Lisanne C. Anders 1 , Adrienne M. Bushau 1 , Anna L. Lang 1 , Gavin
E. Arteel 1 , Matthew C. Cave 2,1 , Craig J. McClain 2,1 , Juliane I.
Beier 1 ; 1 Pharmacology and Toxicology, University of Louisville
health Science Center, Louisville, KY; 2 Medicine, University of Louisville,
Louisville, KY
Background. Vinyl chloride (VC), a ubiquitous environmental
contaminant, ranks 4 th on the ATSDR Hazardous Substances
Priority List. A major paradigm shift in environmental research
is to assess the impact of underlying disorders that may modify
risk. A major health problem in the United States and worldwide
is non-alcoholic fatty liver disease (NAFLD) due to dietary
excess. NAFLD, the hepatic manifestation of metabolic complications
due to obesity, may increase the sensitivity to other
insults. Indeed, studies by our group and others suggest that
obesity increases susceptibility to environmental hepatotoxicants
(e.g., industrial solvents). Recent studies demonstrate a
critical role of the inflammasome in macrophage activation
during NAFLD. Inflammasome activation is induced by pathogen-associated
molecular patterns (“PAMPs”), such as LPS,
as well as by molecules released from dead or dying cells
(damage-associated molecular patterns; “DAMPs”). Previously
we have shown that VC metabolite chloroethanol (ClEtOH)
exacerbated injury and inflammation leading to necrotic cell
death in an experimental model of high-fat diet (HFD) induced
NAFLD. The purpose of the current study was to investigate
the interaction between NAFLD and VC metabolites in the context
of inflammasome activation in an experimental model of
HFD-induced obesity. Methods. Mice, fed a HFD (42% milk
fat) or low fat control diet (LFD; 13% milk fat) for 10 weeks,
were administered a bolus dose of ClEtOH or vehicle. Animals
were sacrificed 0-24 hours after ClEtOH exposure. Plasma and
tissue samples were harvested for determination of liver injury
and inflammasome activation. Results. In LFD-fed control mice,
ClEtOH caused no detectable liver damage, as determined by
plasma parameters (AST and ALT) and histologic indices of
damage. In HFD-fed mice, ClEtOH increased HFD-induced liver
damage, steatosis, hepatocyte ballooning, infiltrating inflammatory
cells, hepatic expression of proinflammatory cytokines
and markers of endoplasmic reticulum (ER) stress. VC-metabolite
induced cell death favors necrosis due to mitochondrial dysfunction
and ATP depletion in this model. Moreover, in animals
on a HFD, ClEtOH exacerbated expression of key markers
involved in inflammasome activation, such as NLRP3 and IL-1β.
Conclusions. Taken together, chloroethanol (as a surrogate VC
exposure) can exacerbate liver injury and inflammasome activation
in HFD-induced NAFLD. This serves as proof-of-concept
that VC hepatotoxicity may be altered by risk-modifying factors
such as diet-induced obesity and NAFLD. These data implicate
exposure to VC as a risk factor in the development of liver disease
in susceptible populations.
Disclosures:
Matthew C. Cave - Advisory Committees or Review Panels: Intercept, Abbvie;
Consulting: Abbvie, Diapharma; Grant/Research Support: Merck, Gilead, Intercept,
Conatus, Lumena, Cepheid, Tobira, Galectin, Bayer; Speaking and Teaching:
BMS, Abbvie, Gilead, Janssen, Genentech
Craig J. McClain - Consulting: Vertex, Gilead, Baxter, Celgene, Nestle, Danisco,
Abbott, Genentech; Grant/Research Support: Ocera, Merck, Glaxo SmithKline;
Speaking and Teaching: Roche
The following authors have nothing to disclose: Lisanne C. Anders, Adrienne M.
Bushau, Anna L. Lang, Gavin E. Arteel, Juliane I. Beier
2142
TNFα mediates the liver:lung axis in alcohol-enhanced
acute lung injury in mice
Lauren G. Poole 1 , Veronica L. Massey 1 , Edilson Torres-Gonzalez 2 ,
Keith C. Falkner 2 , Deanna L. Siow 1 , Nikole L. Warner 3 , Robin H.
Schmidt 1 , Jeffrey D. Ritzenthaler 2 , Jesse Roman 2 , Gavin E. Arteel 1 ;
1 Pharmacology and Toxicology, University of Louisville, Louisville,
KY; 2 Medicine, University of Louisville, Louisville, KY; 3 Microbiology
and Immunology, University of Louisville, Louisville, KY
Background: It is well known that liver and lung injury can
occur simultaneously during severe inflammation (e.g. multiple
organ failure). However, whether these are parallel or interdependent
(i.e. liver:lung axis) mechanisms is unclear. Previous
studies have shown that chronic ethanol exposure increases
the incidence, severity, and mortality of sepsis-induced acute
lung injury (ALI). There is a known liver:lung axis, and previous
studies have suggested that hepatic cytokines can contribute to
pulmonary inflammation; however, this hypothesis in the context
of alcohol exposure has not been tested. Therefore, the purpose
of the current study was to investigate the role of hepatic
cytokine release in alcohol-enhanced lung injury. Methods:
Male mice were exposed to ethanol-containing Lieber-DeCarli
diet or pair-fed control diet for 6 weeks. Some animals were
administered intraperitoneal lipopolysaccharide (LPS) 4 or 24
hours prior to sacrifice to mimic sepsis-induced ALI. The effect
of systemic TNFα depletion on lung injury was determined with
a TNFα-inactivating antibody that is restricted to the plasma
compartment (etanercept). The expression of cytokine mRNA
in lung and liver tissue was determined by qPCR. Cytokine
levels in the bronchoalveolar lavage fluid (BALF) and plasma
were determined by Luminex assay. Results: The combination
of ethanol and LPS caused enhanced liver injury, as indicated
by significantly increased levels of the transaminases ALT/AST
in the plasma and by changes in liver histology. In the lung,
ethanol pre-exposure enhanced pulmonary inflammation and
alveolar hemorrhage caused by LPS. As expected, ethanol
enhanced LPS-induced TNFα expression in the liver; this effect
of ethanol was not observed in the lung. In contrast, TNFα-dependent
chemokines (MIP-2 and KC) were superinduced by the
combination of ethanol and LPS. Systemic TNFα depletion with
etanercept almost completely prevented the enhancement of
lung damage. Furthermore, protecting against this damage correlated
with an almost complete attenuation of the enhanced
induction of TNFα-responsive chemokines MIP-2 and KC. Conclusions:
Chronic ethanol pre-exposure enhanced both liver
and lung injury caused by LPS. Enhanced organ injury corresponded
with unique changes in the pro-inflammatory cytokine
expression profiles in the liver and the lung. Although there
are also likely pulmonary-specific changes caused by alcohol,
these data suggest that systemic (hepatic) TNFα drives alcohol-enhanced
ALI.
Disclosures:
Jesse Roman - Advisory Committees or Review Panels: Cellgene; Grant/Research
Support: Actelion, Intermune, Novartis
The following authors have nothing to disclose: Lauren G. Poole, Veronica L.
Massey, Edilson Torres-Gonzalez, Keith C. Falkner, Deanna L. Siow, Nikole L.
Warner, Robin H. Schmidt, Jeffrey D. Ritzenthaler, Gavin E. Arteel