studies

686A AASLD ABSTRACTS HEPATOLOGY, October, 2015
of CTL (0.606 to 0.942 ng/mg ww) or HFD (0.628 to 0.755
ng/mg ww) over time. CONCLUSION: Reduced hepatic 27HC
concentration observed in this model, is supportive the hypothesis
proposed by previous studies. Enhancement of the reduction
of hepatic 27HC concentration in the presence of IR suggested
a linkage between IR and dysregulation of CYP27A1.
Disclosures:
The following authors have nothing to disclose: Sho-ichiro Yara, Tadashi Ikegami,
Akira Honda, Teruo Miyazaki, Masashi Murakami, Junichi Iwamoto, Yasushi
Matsuzaki
971
Role of Fcgamma receptors in experimental Non-Alcoholic
Steatohepatitis
Daniel Cabrera 1,3 , Evelyn Jara 2 , Ricardo Cruz 1 , Natalia
Muñoz-Durango 2 , Pamela Rojas de Santiago 1 , Alexis Kalergis 2 ,
Marco Arrese 1 ; 1 Departamento de Gastroenterología, Facultad
de Medicina, Pontificia Universidad Católica de Chile, Santiago,
Chile; 2 Departamento de Genética Molecular y Microbiología,
Facultad de Ciencias Biológicas, Pontificia Universidad Católica
de Chile, Santiago, Chile; 3 Departamento de Ciencias Químico-Biológicas,
Universidad Bernardo O Higgins, Santiago, Chile
Background: The role of innate immunity in Non-alcoholic steatohepatitis
(NASH) development is emergent. Different populations
of innate immune cells are present in the liver controlling
tissue cytokine production through Fc gamma receptors (FcγRs),
which are receptors for the Fc region of IgG antibodies. FcγRs
cell-type specifically interact with various other receptors for
selective amplification or inhibition of particular cytokines.
Aim: To evaluate the role of the inhibitory (FcγRIIB) and activatory
(FcγRIII) receptors in NASH pathogenesis. Methods:
Wild Type, FcγRIIb(-/-) and FcγRIII(-/-) mice were fed a methionine-choline
deficient (MCD) diet for 5 weeks. Liver injury was
assessed by measuring serum levels of alanine aminotransferase
(ALT) and histologically. Hepatic triglyceride content (HTC)
and hepatic mRNA levels of selected pro-inflammatory (TNF-α,
IFN-γ, IL-1β, etc.), pro-fibrotic (TGF-β, CTGF, Collagen-1, etc.)
and inflammasome (ASC, NLRP3, Caspase-1, etc.) genes were
also assessed. Serum pro-inflammatory cytokine levels (TNF-α,
IFN-γ, etc.) were determined by cromatographic bead assay
(CBA). By flow cytometry was evaluated different populations
of inflammatory cells infiltrated in the liver such as dendritic,
neutrophils, macrophages and lymphocytes. Results: FcγRIIb(-/-)
MCD-fed mice developed a more robust hepatic inflammatory
(decreased hepatic expression of TNFα and other cytokines)
and fibrotic response (decreased hepatic expression of collagen
I) in comparison with WT MCD-fed mice with no differences
in HTC (Figure 1 A and B). No differences were found
in liver cell populations of lymphoid and myeloid lineages.
The main finding in FcγRIII(-/-) MCD-fed mice was a significant
reduction in histological steatosis and HTC. (see figure 1C,
below) likely related to reduced interleukin-10 production. Liver
lymphoid and myeloid cell populations remained unchanged in
these mice. Conclusion: Our results suggest and important role
of the FcγRs in NASH development. While the absence of Fcγ−
RIIb seems to promote NASH induction, the absence of FcγRIII
strongly reduces liver steatosis. This is the first report that shows
a direct role of FcγRs in the pathogenesis of NASH.(Grant
support: FONDECYT 1150327 to M.A., PD3140396 to D.A.)
Disclosures:
The following authors have nothing to disclose: Daniel Cabrera, Evelyn Jara,
Ricardo Cruz, Natalia Muñoz-Durango, Pamela Rojas de Santiago, Alexis Kalergis,
Marco Arrese
972
Regulation of Hepatocellular Fatty Acid Uptake in
Mouse Models of Fatty Liver Disease With and Without
Functional Leptin Signalling: Roles of NfKB and
Srebp-1c
Fengxia Ge, Jose L. Walewski, Paul D. Berk; Medicine, Columbia
University Medical Center, New York, NY
The specific processes leading to increased hepatic triglycerides
(TGs) in mouse models of hepatic steatosis (HS) due
to EtOH consumption, high fat diets (HFDs), or obesity mutations
remain uncertain. This study focuses on regulation by 5
transcription factors (Nfb, Srebp-1c, AMPK, PPARα, PPARγ) of
the 7 most-studied hepatic LCFA transporters (FABPpm, CD36,
FATP1, FATP2, FATP4, FATP5, & Caveolin-1 [CAV-1]) and
enzymes of LCFA synthesis (SCD-1, FASN) in mice with HS
from various causes. Methods: Seven groups of 20 wk old
male mice (n=8/group; Jackson Labs) were studied: C57BL/6J
controls (C); similar mice with HS from 12 wks of a high fat diet
(HFD) or 10, 14, or 18% EtOH in drinking water (E10, E14,
E18); & genetically obese mice lacking leptin (ob/ob) or its
receptor (db/db). Hepatocyte [ 3 H]-oleate uptake was assayed
by rapid filtration; Vmax for saturable uptake was computed
with SAAM II. Gene expression for the 5 transcription factors,
7 transporters, & for key enzymes of LCFA synthesis was
assayed by qRT-PCR. Hepatic TG was measured biochemically.
Expression ratios for transcription factors and transporter
genes were compared with one another, with Vmax, & with
hepatic TG. Results: [1] LCFA uptake Vmax was increased &
highly correlated with hepatic TG in all groups except ob/ob &
db/db. [2] Increased Vmax & hepatic TG in the EtOH & HFD
groups correlated best with increased expression of genes for
at least one & often multiple transporters. [3] Despite variable
expression of single transporter genes in individual E & HFD
groups, the mean expression ratio for FABPpm, FATPs 1,2,4,&
5, & CD36 in each group was highly correlated with Vmax,
hepatic TG, and expression of transcription factor genes. [4]
Of the transcription factors, SREBP-1c (r = 0.99) and NfKB (r
= 0.94) were by far the most closely correlated with Vmax. [5]
Increased hepatic TGs in ob/ob & db/db mice did not relate
to hepatic LCFA uptake, but instead were highly correlated
with increased expression of LCFA synthetic enzymes (SCD-1,
FASN). Conclusions: [1] The processes underlying increased
hepatic TG are different in mice with vs without functional leptin
signaling. Increased LCFA uptake is the principal cause of HS
in the former, but increased LCFA synthesis predominates in
the latter. [2] Regulation of LCFA transporter expression & participation
of individual transporters in LCFA uptake are more
complex than previously believed. [3] Correlations between
transcription factor expression & mean expression of multiple
transporter genes suggests possible regulatory interaction, and
may support reports postulating that a complex of FABPpm,
CAV-1, CD36 & FATP4 mediates hepatic LCFA uptake.