studies

846A AASLD ABSTRACTS HEPATOLOGY, October, 2015
These findings have direct implications for our understanding
of the roles of IL-22 and IL-22BP in regulating liver immunity.
Disclosures:
The following authors have nothing to disclose: Wagdi Almishri, Julie Deans,
Mark Swain
Disclosures:
Thomas D. Schiano - Advisory Committees or Review Panels: salix, merck, gilead,
pfizer; Grant/Research Support: galectin, massbiologics, biotest
Andrea D. Branch - Grant/Research Support: Gilead, Janssen
The following authors have nothing to disclose: Erin H. Doyle, Adeeb Rahman,
Arielle L. Klepper, Sang Kim, Brandy M. Haydel, Sander S. Florman, M. Isabel
Fiel
1290
Activation of hepatic innate immunity markedly alters
the IL-22/IL-22R1/IL-22BP axis within the liver: Implications
for hepatic immunity.
Wagdi Almishri, Julie Deans, Mark Swain; Medicine, University of
Calgary, Calgary, AB, Canada
IL-22 is an innate cytokine that has been broadly implicated
in the regulation of hepatic immunity, showning both pro- and
anti-inflammatory effects in animal models of liver injury. IL-22
exerts its’ biological functions by interacting with its’ receptor
IL-22R1 which is widely expressed on epithelial cells and
hepatocytes. Importantly, IL-22 activity is regulated by an
endogenous inhibitor, IL-22BP, which binds IL-22 and prevents
its’ biological function. Therefore, we performed a series of
experiments to delineate alterations that occur in the IL-22/
IL-22BP/IL-22R1 axis in the liver, using a mouse model of
hepatic innate immune activation due to NKT cell activation.
In addition, we determined changes in IL-22BP and IL-22R1
expression in liver biopsy samples obtained from patients with
hepatitis B and C, PBC, PSC and autoimmune hepatitis (AIH).
Results: We found (by flow cytometry) the rapid and striking
recruitment of IL-22 producing innate lymphoid cells (ILC3’s)
into the liver, followed later by other IL-22 producing immune
cells, including Th22 cells. In addition, using IL-22 knockout
mice we demonstrate a proinflammatory role of IL-22 in the
liver during innate immune activation. The recruitment of IL-22 +
immune cells was paralleled by recruitment of IL-22BP + immune
cells into the liver, and the marked up-regulation of IL-22BP
expression in hepatocytes. Moreover, despite our findings of
a robust influx of IL-22 + immune cells into the liver after NKT
cell activation, bioavailable hepatic IL-22 levels actually significantly
decreased in the 1-2 days after activation of hepatic
innate immunity. Within the liver IL-22BP expression in recruited
immune cells and in hepatocytes was largely dependent upon
activation of the inflammasome. Viral and autoimmune liver diseases
in patients have been linked to the activation of NKT cells
and an enhancement of hepatic innate immunity. Therefore, we
examined IL-22BP and IL-22R1 expression in liver biopsy specimens
obtained from patients with liver disease, and found a
striking increase in the hepatic expression of both IL-22BP and
IL-22R1 in both viral and autoimmune liver diseases (ie. PBC,
PSC, AIH, hepatitis B and C). Conclusion: These observations
highlight a tight co-regulation of the IL-22/IL-22BP/IL-22R1
axis during hepatic innate immune responses, and suggest
that IL-22BP plays an important role in regulating IL-22 bioactivity
within the liver in the context of innate immune activation.
1291
Impaired TRAF6 methylation and TLR responses in liver
tissue and circulating monocytes from patients with
spontaneous bacterial peritonitis
Irina Tikhanovich, Jody C. Olson, Ryan Taylor, Brian Bridges, Kenneth
Dorko, Benjamin R. Roberts, Steven A. Weinman; University
of Kansas Medical Center, Kanas City, KS
Patients with cirrhosis have a number of abnormalities in their
response to infection including failure to clear bacteria from
the peritoneal space or blood and an exaggerated systemic
inflammatory response. Cirrhotic patients with a history of
spontaneous bacterial peritonitis (SBP) have particularly severe
defect in bacterial clearance. Our previous work has shown
that the arginine methyltransferase PRMT1 and the demethylation
enzyme JMJD6 regulate innate immune signaling
pathways by controlling the arginine methylation of TRAF6,
a critical ubiquitin ligase for TLR responses. We found that a
decrease in the PRMT1/JMJD6 ratio results in a loss of TRAF6
methylation causing preactivation of TLR pathways but reduced
responses to bacterial antigens. The AIM of this study was to
determine whether cell type specific defects in TRAF6 arginine
methylation occur in cirrhosis and can contribute to susceptibility
to infections. METHODS: Liver tissue sections and peripheral
blood monocytes from patients without cirrhosis and cirrhotic
patients with or without a history of SBP were analyzed for
the levels of PRMT1, TRAF6 methylation and cytokine production
in response to LPS using IHC staining, western blotting
and proximity ligation assay. RESULTS: PRMT1 to JMJD6 protein
ratios was lower in total liver protein from cirrhosis than
normal donors (2.2±1.1 vs 0.68±0.43) and lower in patients
with history of SBP compared to those with no history of SBP
(0.92±0.48 vs 0.43±0.16). Tissue staining revealed that in
patients with SBP compared to cirrhotics without an SBP history,
PRMT1 was lower in non-parenchymal cells (p-value 0.029),
and JMJD6 was higher both in hepatocytes and non-parenchymal
cells (p-values 0.0009 and 0.025 respectively). PRMT1/
JMJD6 ratio was significantly lower both in hepatocytes and
non-parenchymal cells of patients with history of SBP (p-values
0.044 and 0.005 respectively). TRAF6 methylation levels
were directly analyzed by PLA and were similarly lower in
livers of patients with history of SBP. Similar to the situation
in liver, blood monocytes from patients with a history of SBP
showed a similar defect in PRMT1 levels compared to monocytes
from patients with cirrhosis without SBP (p-value 0.032)
and the associated decrease in PRMT1/JMJD6 ratio correlated
with decreased TRAF6 methylation and cytokine production
in response to LPS. CONCLUSION: PRMT1 and JMJD6 levels
control TRAF6 methylation and antibacterial innate immune
responses. TRAF6 methylation is decreased in multiple cell
types of patients with a history of SBP, which may contribute to
the abnormal infection responses seen in those patients.
Disclosures:
Jody C. Olson - Advisory Committees or Review Panels: Baxter
Steven A. Weinman - Consulting: Cardax, Inc.
The following authors have nothing to disclose: Irina Tikhanovich, Ryan Taylor,
Brian Bridges, Kenneth Dorko, Benjamin R. Roberts