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852
SUPPRESSION OF INTRAHEPATIC HEPATITIS B SURFACE
ANTIGEN (HBsAg) PREVENTS INTERFERON MEDIATED LIVER
INJURY
Yasuhito Tanaka1,2, Ian Baudi2, Masanori Isogawa2 and
Keigo Kawashima2, (1)Department of Gastroenterology and
Hepatology, Kumamoto University, (2)Department of Virology
& Liver Unit, Nagoya City University Graduate School of
Medical Sciences
Background: Acute, potentially fatal, hepatitis often precedes
virologic responses to IFN⍺ treatment in some chronic HBV
patients. The molecular determinants for such liver flares are
unclear We previously reported that IFNs induce liver injury in
HBV transgenic mice that overproduce HBsAg (lineage 107-
5D) The aim of the current study was to examine the impact of
differential HBs expression on IFN-mediated liver injury in HBV
mouse models Methods: Two different HBV transgenic mice
were used Lineage 107-5D transgenic mice express HBsAg
in the liver under mouse albumin promoter Lineage 1 3 32
transgenic mice replicate HBV in the liver from a terminally
redundant 1 3-fold HBV DNA genome Groups of transgenic
mice were intravenously injected with a synthetic type I IFN
inducer, poly I:C (10 μg/mouse) The role of HBs transcripts
(HBs mRNA) in IFN-mediated liver damage was examined by
treating lineage 107-5D mice with siRNA targeting HBs mRNA
(siHBs) or control siRNA (siCTRL) one week before IFN⍺
administration (5 million U/kg) To determine the importance
of HBsAg retention in IFN-mediated liver damage, lineage
107-5D mice were first adoptively transferred with HBsAgspecific
CD8+ T cells to eliminate hepatocytes that had
already accumulated HBsAg Seven days later, the mice were
treated with siHBs or siCTRL, and then administered with
IFN⍺ Results: Non-treated lineage 107-5D mice retained
100-fold more HBsAg in the liver than lineage 1 3 32 mice
(852±358 vs 10±4 IU/mg, p=0 015), although serum HBsAg
levels of lineage 107-5D were much lower than lineage
1 3 32 (serum HBsAg: 11±3 vs 395±64 IU/ml, p=0 001)
After poly I:C treatment, lineage 107-5D mice showed severe
liver damage (4194±750 U/L), while no sALT elevation was
observed in lineage 1 3 32 (40±6 U/L), suggesting that IFN
mediated liver injury is directly correlated with intrahepatic
HBsAg levels Treatment with siHBs effectively reduced
HBs mRNA levels, approximately 10-fold, in lineage 107-
5D mice within one week but had no impact on intrahepatic
HBsAg levels Consequently, siHBs treatment alone failed to
prevent liver injury after IFN⍺ -treatment On the other hand, if
HBsAg accumulating hepatocytes were eliminated by HBsAgspecific
CD8+ T cells before siRNA treatment, IFN mediated
liver injury was significantly reduced in siHBs treated mice
compared to siCTRL groups (sALT 425±103 vs 4227±2533,
p=0 027) Conclusion: HBsAg level in the liver determines
the magnitude of IFN⍺ mediated liver injury.
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