studies

HEPATOLOGY, VOLUME 62, NUMBER 1 (SUPPL) AASLD ABSTRACTS 907A
1429
Concerted effects of the two major genetic risk factors
for cholestatic (ABCB4) and fatty liver disease (PNPLA3)
on liver fibrosis: elastography-based study in chronic
liver disease
Marcin Krawczyk 2,1 , Frank Grünhage 2 , Frank Lammert 2 ; 1 Laboratory
of Metabolic Liver Diseases, Department of General, Transplantation
and Liver Surgery, Medical University of Warsaw,
Warsaw, Poland; 2 Department of Medicine II, Saarland University
Medical Center, Homburg, Germany
Background: The liver responds uniformly with liver fibrosis
to any chronic injury. Genome-wide association studies
have established the common polymorphism p.I148M of the
PNPLA3 gene as the major genetic determinant of non-alcoholic
and alcoholic fatty liver disease. Whereas rare mutations
of the hepatobiliary phosphatidylcholine transporter ABCB4
are known to cause biliary cirrhosis, large-scale whole-genome
sequencing lead to the identification of the common ABCB4
variant c.711A>T as general risk factor for cholestasis and cirrhosis
(Nat Genet 2015). Hence, our hypothesis now was that
the combination of these two most relevant genetic risk factors
should aggravate fibrosis across chronic liver diseases (CLD).
Patients and methods: To address this issue, we studied 713
patients (age 50±12 years, 434 men) recruited for our non-invasive
elastography-based study (J Hepatol 2011), which confirmed
that the PNPLA3 mutation represents a common fibrosis
risk gene. Liver stiffness was determined non-invasively using
transient elastography (TE, Fibroscan). The PNPLA3 c.444C>G
(p.I148M) and ABCB4 c.711A>T (splice region variant) polymorphisms
were genotyped by PCR-based assays. Association
with transient elastography results was tested in contingency
tables, and TE values in carriers of distinct PNPLA3 and ABCB4
genotypes were compared by non-parametric tests. Results:
The ABCB4 c.711 ([TT] n = 23, [AT] n = 204, [AA] n = 486)
and the PNPLA3 p.I148M ([CC] = 382, [CG] = 280 and [GG]
= 50) genotype distributions were in Hardy-Weinberg equilibrium.
The median liver stiffness in the entire cohort was 6.7
kPa and ranged from 2.2 to 75.0 kPa; 156 patients presented
with TE ≥ 13.0 kPa. Of note, the procholestatic allele ABCB4
c.711A was present in the majority of the patients and did not
significantly influence TE per se. The combination of ABCB4
and PNPLA3 risk alleles lead to incremental increases of mean
TE from 5.6 kPa in carriers of 0 to 7.8 kPa in carriers of 4 risk
alleles. In heterozygous carriers of the PNPLA3 risk variant
p.I148M, the presence of the procholestatic ABCB4 geneotype
[AA] was significantly (P = 0.04) associated with increased
TE; in contrast, this effect was absent in PNPLA3 homozygotes.
Conclusions: This is the first study to assess simultaneously the
effects of the currently known most common mutations in two
distinct core pathways simultaneously in patients with CLD.
Our results suggest that the procholestatic ABCB4 variant
might boost the harmful effects of the major PNPLA3 mutation
and vice versa. Prospective studies are warranted to evaluate
ABCB4-PNPLA3 compound genotypes as genetic determinants
of liver vulnerability.
Disclosures:
Frank Grünhage - Grant/Research Support: Gilead; Speaking and Teaching:
Falk, Abbvie
The following authors have nothing to disclose: Marcin Krawczyk, Frank Lammert
1430
Innate Lymphoid Cell (ILC) Subset Composition of
Human Liver: Enrichment for ILC1s in Hepatic Cirrhosis
Lucy Golden-Mason 1 , Silvia Giugliano 1 , Linling Cheng 1 , Hugo R.
Rosen 1,2 ; 1 GI/Hepatology, Univ Colorado Denver, Aurora, CO;
2 Veteran’s Affairs Medical Center, Denver, CO
Introduction: Innate lymphoid cells (ILCs) are emerging as
important immune effectors that, in addition to stimulating proand
anti-inflammatory responses, are involved in tissue remodeling.
Three groups of ILCs have been identified in humans.
These include pro-inflammatory Group 1 (ILC1) populations
which produce IFN-γ and ILC3s which produce IL-17 and or
IL-22. ILC2s are characterized by the production of anti-inflammatory
cytokines, predominantly IL-13. In an acute liver injury
model, natural cytotoxicity receptor (NCR) negative ILC3s are
tissue protective. The ILC composition of human liver is unexplored.
We hypothesized that the human liver, an established
site for innate immunity, would harbor pro-inflammatory ILCs
(ILC1/ILC3) which would be increased in hepatic inflammation
and cirrhosis. Methods: Single cell suspensions were prepared
from liver tissues using mechanical disruption and enzymatic
digestion. Our study group consisted of normal (n=12), alcoholic
liver disease (ALD, n=6), cholestatic liver disease (PBC/
PSC, n=6) and HCV (n=18). The majority of subjects (88%)
were Caucasian and 68% were male. Multi-parameter flow
cytometric analysis was used to characterize human hepatic
ILCs. Total ILCs were identified by their lymphoid morphology,
absence of markers for myeloid, T, NK, B and stem cells
and by co-expression of CD45 and the IL-7 receptor (CD127).
ILC subsets were identified by the expression pattern of c-kit
(CD117), NCR NKp44 and CRTH2. Results: In normal liver
ILCs represent 4.45% (1.39-9.1) of CD45-positive lineage
negative lymphoid cells. ILC1 are the predominant subset
detected in normal liver followed by NCR neg ILC3s. Anti-inflammatory
ILC2s comprise 2.39-16.8% of total ILCs in normal
liver. In cirrhotic liver tissues levels of total ILCs are stable in
HCV-induced and cholestatic liver disease-related cirrhosis.
However, in alcohol-induced cirrhosis a greater than 3-fold
increase in ILC levels was observed (p