studies

500A AASLD ABSTRACTS HEPATOLOGY, October, 2015
585
Persistent Generation of Inflammatory Mediators after
Acetaminophen Overdose in Surviving and Non-Surviving
Patients
Benjamin Woolbright, Mitchell R. McGill, Matthew R. Sharpe,
Hartmut Jaeschke; Pharmacology, Toxicology & Therapeutics, University
of Kansas Medical Center, Kansas City, KS
Acetaminophen (APAP) overdose is a leading cause of drug-induced
liver failure. In both human overdose patients and the
murine model, metabolic activation of acetaminophen leads to
formation of protein adducts, mitochondrial dysfunction, necrosis
and an acute inflammatory response. Considerable debate
occurs over the role of the inflammatory response after APAP
overdose, as to whether sterile inflammation promotes liver
injury through inflammasome activation, or if sterile inflammation
resolves injury through clearance of necrotic debris and
stimulation of regeneration. Currently, there is limited information
on the time course of cytokine formation or complement
activation in human patients, especially in surviving (S) and
non-surviving (NS) populations. This study addressed this deficit,
with the hypothesis that NS patients would accumulate
a greater degree of plasma cytokine levels, and have more
severe complement depletion after APAP overdose. Circulating
plasma levels of IL-1ß, TNF-α, IL-6, IL-8, IL-10, MCP-1, G-CSF,
and GRO were measured by multi-plex ELISA and complement
C3 was measured by ELISA in healthy volunteers (n=8),
patients with APAP overdose but no increase in liver enzymes
(n=10), and S (n=13) and NS (n=8) APAP overdose patients
with liver injury, for the first seven days after study admission.
ALT levels were similar between S and NS groups (5,531 ±
639 U/L v. 5,302 ± 1,139 U/L), although bilirubin was significantly
greater in the NS group (4.1 ± 1.0 mg/dL v. 8.6 ±
3.1 mg/dL). Plasma levels of pro-inflammatory cytokines such
as IL-1ß, GRO, and TNF-α did not rise above control levels at
any point. In contrast, both S and NS patients had persistent,
significant elevations in G-CSF, IL-6, IL-8, and anti-inflammatory
cytokines such as IL-10 and MCP-1. Moreover, levels of IL-6,
IL-8, IL-10 and MCP-1 were significantly higher in NS patients
compared to S patients at multiple time points. MCP-1 levels
rose to the greatest degree in both S patients (6,134 ± 1,134
pg/mL) and NS patients (7,074 ± 1,105 pg/mL); whereas
IL-1ß accumulated the least in both S patients (81.4 ± 64.2
pg/mL) and NS patients (39.2 ± 32.6 pg/mL). Plasma C3
levels were depleted at the same rate in S and NS patients, but
recovered only in S patients. In conclusion, these data support
the hypothesis that NS patients become refractory to anti-inflammatory
cytokine signals, which likely fail to resolve injury
or stimulate regeneration. Furthermore, there is limited inflammasome
activation in human patients, as IL-1ß levels never rise
above baseline. Importantly, however, other cytokines may
have predictive value.
Disclosures:
The following authors have nothing to disclose: Benjamin Woolbright, Mitchell R.
McGill, Matthew R. Sharpe, Hartmut Jaeschke
586
Protective effects of connexin43 signaling in acetaminophen-induced
liver injury
Michaël Maes 1 , Mitchell R. McGill 2 , Tereza Cristina da Silva 3 ,
Margitta Lebofsky 2 , Isabel V. Pereira 3 , Joost Willebrords 1 , Sara
Crespo Yanguas 1 , Anwar Farhood 4 , Maria Lucia Zaidan Dagli 3 ,
Hartmut Jaeschke 2 , Bruno Cogliati 3 , Mathieu Vinken 1 ; 1 In Vitro
Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel,
Brussels, Belgium; 2 Department of Pharmacology, Toxicology and
Therapeutics, University of Kansas Medical Center, Kansas City,
KS; 3 Department of Pathology, School of Veterinary Medicine
and Animal Science, University of São Paulo, São Paulo, Brazil;
4 Department of Pathology, St. David’s North Austin Medical Center,
Austin, MO
Background and aims: Being goalkeepers of liver homeostasis,
gap junctions are also involved in hepatotoxicity. However,
their role in this process is ambiguous, as gap junctions can act
as both targets and effectors of liver toxicity. This particularly
holds true for drug-induced liver insults. In the present study, the
role and functional relevance of connexin32 and connexin43,
the building stones of liver gap junctions, were investigated
in acetaminophen-induced hepatotoxicity. Methods: C57BL/6
mice were overdosed with acetaminophen followed by analysis
of the expression and localization of connexins as well as
monitoring of hepatic gap junction functionality. Furthermore,
acetaminophen-induced liver injury was compared between
mice genetically deficient in either connexin32 or connexin43
and wild type animals. Evaluation of the toxicological response
was based on a set of clinically relevant parameters, including
protein adduct formation, histopathological examination, measurement
of alanine aminotransferase, cytokines, reduced and
oxidized glutathione, and analysis of proliferating cell nuclear
antigen expression. Results: It was found that gap junction communication
deteriorates upon acetaminophen intoxication in
wild type mice, which was associated with a switch in mRNA
and protein production from connexin32 to connexin43. Furthermore,
connexin43-deficient animals showed increased
liver cell death, inflammation and oxidative stress in comparison
with wild type counterparts, whereas the opposite seems
to hold true for mice lacking connexin32. Conclusion: These
results suggest that hepatic connexin43-based signaling protects
against acetaminophen-induced liver toxicity.
Disclosures:
The following authors have nothing to disclose: Michaël Maes, Mitchell R.
McGill, Tereza Cristina da Silva, Margitta Lebofsky, Isabel V. Pereira, Joost
Willebrords, Sara Crespo Yanguas, Anwar Farhood, Maria Lucia Zaidan Dagli,
Hartmut Jaeschke, Bruno Cogliati, Mathieu Vinken
587
The Hepatic “Matrisome” Responds Dynamically to
Inflammatory Injury: Proteomic Characterization of the
Transitional ECM Changes in the Liver
Christine E. Dolin 1 , Veronica L. Massey 1 , Lauren G. Poole 1 ,
Deanna L. Siow 1 , Michael L. Merchant 2 , Daniel W. Wilkey 2 ,
Gavin E. Arteel 1 ; 1 Pharmacology and Toxicology, University of
Louisville, Louisville, KY; 2 Medicine, University of Louisville, Louisville,
KY
Background. The impact of the changes to the hepatic extracellular
matrix (ECM) in the context of collagen accumulation
during fibrosis are well known. However, the hepatic ECM
consists of a myriad of biologically relevant proteins beyond
collagen; furthermore, changes to the hepatic ECM are not
restricted to fibrosis. Indeed, transitional changes to the hepatic
ECM during inflammatory liver injury may be critical in the
balance between restitution versus accumulation of damage.