studies

HEPATOLOGY, VOLUME 62, NUMBER 1 (SUPPL) AASLD ABSTRACTS 303A
Disclosures:
The following authors have nothing to disclose: Lu Yao, Chang Han, Tong Wu
186
IL-17 signaling in hepatocellular carcinoma promoted
by ethanol.
Hsiao-Yen Ma 2,1 , Jun Xu 1,2 , Mengxi Sun 1,2 , David A. Brenner 2 ,
Tatiana Kisseleva 1 ; 1 Department of Surgery, UC San Diego, La
Jolla, CA; 2 Department of Medicine, UC San Diego, La Jolla, CA
Hepatocellular carcinoma (HCC) is a malignant tumor made of
cells dedifferentiated from mature hepatocytes, which usually
arises in patients with end stage cirrhosis. Progression of HCC
is associated with upregulation of inflammation and constitutive
activation of STAT3. Meanwhile, prolonged alcohol consumption
has strong immunosuppressive and hepatotoxic effects,
implying chronic alcohol consumption would promote HCC
development. Furthermore, ALD patients showed significant
increase in plasma and hepatic IL-17A expression. Blockage
of IL-17 signaling significantly reduced alcohol induced steatohepatitis
and fibrosis in preclinical mouse models. However,
the role of IL-17 signaling in alcohol promoted HCC remains
unclear. AIM: To determine the role of IL-17A signaling pathway
during alcohol promoted HCC development and evaluate
IL-17A as a therapeutic target for HCC. METHODS: Two different
models were used to assess the IL-17 signaling in alcohol
promoted HCC. First, hepatic carcinogen (DEN) induced
HCC in which WT and IL-17RA null mice (KO) were injected
with single dose of DEN at 14 days old. Second, steatohepatitis
associated HCC in which MUP-uPA transgenic mice were
crossed with WT and IL-17RA KO to generate MUP-uPA|WT
(MWT) and MUP-uPA|IL-17RA KO (MKO) mice. By 12 weeks
old, each genotype was assigned to pair-fed group and EtOH
group to receive Liber-Decarli HFD or alcohol diet for 18 weeks
respctively. The HCC development in both WT and KO mice
were compared and Stat3 signal pathway was evaluated. To
investigate how IL-17A signal regulating HCC associated fibroblasts
and macrophage, MC-38-GFP cancer cells were injected
into the spleen of WT and KO recipients for 10 days and the
tumor size and numbers were compared. RESULTS: Chronic
administration of the Liber-DeCarli alcohol diet accelerated
tumorogenesis in both WT/MWT and KO/MKO mice. Blockade
of IL-17 signaling significantly suppressed tumor size and
tumor number in both pair-fed and EtOH group. In MUP-uPA
mice, liver fibrosis was increased after EtOH feeding, which
was decreased by blockade of IL-17 signaling. Blockade of
IL-17 signaling showed less inflammation (reduced TNFa, IL1b,
TGFb1), mediators of metastasis (MMP7, MMP9) and ROS
production (Nox1, Nox2). As expected, CYP2E1 was elevated
in EtOH group, but suppressed in KO mice. CONCLUSION:
Chronic alcohol consumption accelerated tumor development
which was mediated by IL-17 signaling pathway. The role of
IL-17 signaling during alcohol promoted HCC may be via regulating
STAT3 signaling pathway and upregulation of CYP2E1.
Disclosures:
The following authors have nothing to disclose: Hsiao-Yen Ma, Jun Xu, Mengxi
Sun, David A. Brenner, Tatiana Kisseleva
187
Deletion of fibrocytes in mice attenuates experimental
liver fibrosis.
Jun Xu 1,2 , Min Cong 1,2 , Tae Jun Park 1,2 , David A. Brenner 1 , Tatiana
Kisseleva 2 ; 1 Department of Medicine, UCSD, San Diego, CA;
2 Department of Surgery, UC San Diego, La Jolla, CA
BACKGROUND:Bone marrow (BM) fibrocytes, designated as
CD45 + and Collagen type I + (Col1a1) cells, are recruited to
the injured liver, however, their role in liver fibrosis remains
unclear. AIM: To determine the role of fibrocytes in pathogenesis
of liver fibrosis. METHODS: 1The contribution of fibrocytes to
liver fibrosis was studied in BM chimeric mice devoid of fibrocytes
(DFibrocyte mice), in which fibrocyte death was induced
by expression of Diphtheria toxin a (DTA) in CD45 + Col1a1 +
fibrocytes. Specifically, tamoxifen-inducible Col1a1 ER-Cre
mice were crossed with Rosa26 flox-Stop-flox-YFP reporter mice ±
Rosa26 flox-Stop-flox-DTA mice, and used as donors for BM transplantation
into lethally irradiated wt mice to generate wt and
DFibrocyte mice. 2The role of Col1a1 in regulation of fibrocyte
function was studied in BM chimeric Col1a1 5’SL-/- -into-wt
mice, in which mutation of 5’stemloop (5’SL -/- mice) prevented
proper Col1a1 translation in fibrocytes. 3)All mice were subjected
to CCl 4
for 6 w. The therapeutic potential of Serum
Amyloid P (SAP), a natural inhibitor of fibrocytes, was tested.
4To translate our findings to humans, the role of fibrocytes
as prognostic biomarker was evaluated in patients with liver
cirrhosis. RESULTS: Cell fate mapping revealed that 20% of
hepatic fibrocytes become a-SMA myofibroblasts, while 80%
become myeloid cells, which serve as a significant source of
TGFβ1, IL-6, and IL-1b1 in CCl 4
treated wt mice. Deletion of
fibrocytes/progeny in DFibrocyte mice resulted in inhibition
of CCl 4
induced liver fibrosis by 50%, as shown by reduced
Col1a1, a-SMA, and TGFb1 mRNA expression. Interestingly,
fibrocyte ablation also resulted in suppression of hepatic pro-inflammatory
macrophages (M1) and promote proliferation of
anti-inflammatory macrophages (M2), suggesting that fibrocytes
regulate M1/M2 macrophage polarization. Next, we
tested if Col1a1 expression affects fibrocyte function. Indeed,
liver fibrosis was reduced in Col1a1 5’SL-/- into-wt mice by >30%,
and was associated with impaired proliferation of BM fibrocytes.
Surprisingly, activation of non-fibrocyte-derived myeloid
lineages was also reduced, indicating that fibrocytes have an
important immunoregulatory function. In support, the number
of circulating fibrocytes in patients correlated with the stage
of liver fibrosis, and with low levels of serum SAP. Administration
of SAP significantly ameliorated liver fibrosis in CCl 4
-wt
mice. CONCLUSION: Fibrocytes contribute to liver fibrosis indirectly
by increasing liver inflammation and secreting fibrogenic
agonists. Targeting fibrocytes with SAP may become a novel
therapy of liver fibrosis in patients with reduced serum levels
of SAP.
Disclosures:
The following authors have nothing to disclose: Jun Xu, Min Cong, Tae Jun Park,
David A. Brenner, Tatiana Kisseleva