HBsAg loss in patients treated with peginterferon alfa-2a and adefovir is associated with SLC16A9 gene variation and lower plasma carnitine levels.
OBJECTIVE
Achievement of HBsAg loss remains the hallmark of chronic hepatitis B treatment. In order to identify host factors contributing to treatment-induced HBsAg loss, we performed a genome-wide screen of single nucleotide polymorphisms (SNPs) and studied its immunological consequence.


METHODS
Chronic hepatitis B patients (40 HBeAg-positive and 44 HBeAg-negative) treated with peginterferon alfa-2a and adefovir were genotyped for 999,091 SNPs, which were associated with HBsAg loss at week 96 (n = 9). Plasma carnitine levels were measured by tandem-mass spectrometry, and the effect of carnitine on the proliferative capacity of hepatitis B virus (HBV)-specific and non-specific CD8 T cells was studied in vitro.


RESULTS
One polymorphism, rs12356193 located in the SLC16A9 gene, was genome-wide significantly associated with HBsAg loss at week 96 (p = 1.84 × 10(-8)). The previously reported association of rs12356193 with lower carnitine levels was confirmed in our cohort, and baseline carnitine levels were lower in patients with HBsAg loss compared to patients with HBsAg persistence (p = 0.02). Furthermore, we demonstrated that carnitine suppressed HBV-specific CD8 T cell proliferation.


CONCLUSIONS
In chronic hepatitis B patients treated with peginterferon and adefovir, we identified strong associations of SLC16A9 gene variation and carnitine levels with HBsAg loss. Our results further suggest that a lower baseline plasma carnitine level increases the proliferative capacity of CD8 T cells, making patients more susceptible to the immunological effect of this treatment. These novel findings may provide new insight into factors involved in treatment-induced HBsAg loss, and play a role in the prediction of treatment outcome.
Department of Gastroenterology and Hepatology, Academic Medical Center (AMC), University of Amsterdam (UvA), Amsterdam, The Netherlands; Department of Experimental Immunology, AMC, UvA, The Netherlands.
Louis
L
Jansen
Department of Gastroenterology and Hepatology, Academic Medical Center (AMC), University of Amsterdam (UvA), Amsterdam, The Netherlands; Department of Experimental Immunology, AMC, UvA, The Netherlands.
Annikki
A
de Niet
Department of Gastroenterology and Hepatology, Academic Medical Center (AMC), University of Amsterdam (UvA), Amsterdam, The Netherlands; Department of Experimental Immunology, AMC, UvA, The Netherlands.
Femke
F
Stelma
Department of Clinical Epidemiology, Biostatistics, and Bioinformatics, AMC, UvA, The Netherlands; Durrer Center for Cardiogenetic Research, Amsterdam, The Netherlands.
Erik P A
EP
van Iperen
Department of Experimental Immunology, AMC, UvA, The Netherlands.
Karel A
KA
van Dort
Department of Gastroenterology and Hepatology, Academic Medical Center (AMC), University of Amsterdam (UvA), Amsterdam, The Netherlands; Department of Experimental Immunology, AMC, UvA, The Netherlands.
Marjan J Tempelmans
MJ
Plat-Sinnige
Department of Gastroenterology and Hepatology, Academic Medical Center (AMC), University of Amsterdam (UvA), Amsterdam, The Netherlands.
R Bart
RB
Takkenberg
Hoffman La Roche, Nutley, USA.
Daniel J
DJ
Chin
Department of Clinical Epidemiology, Biostatistics, and Bioinformatics, AMC, UvA, The Netherlands.
A H Koos
AH
Zwinderman
Assembly Pharmaceuticals, Bloomington, IN, USA.
Uri
U
Lopatin
Department of Experimental Immunology, AMC, UvA, The Netherlands.
Neeltje A
NA
Kootstra
Department of Gastroenterology and Hepatology, Academic Medical Center (AMC), University of Amsterdam (UvA), Amsterdam, The Netherlands. Electronic address: h.w.reesink@amc.nl.
Hendrik W
HW
Reesink
D000225:Adenine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D000328:Adult; D000998:Antiviral Agents / Q000008:administration & dosage; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002331:Carnitine / Q000097:blood*; D004359:Drug Therapy, Combination; D005260:Female; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D006513:Hepatitis B e Antigens / Q000097:blood*; D006515:Hepatitis B virus / Q000187:drug effects / Q000502:physiology; D019694:Hepatitis B, Chronic / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics; D006801:Humans; D016898:Interferon-alpha / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D027501:Monocarboxylic Acid Transporters / Q000235:genetics*; D063065:Organophosphonates / Q000008:administration & dosage*; D011092:Polyethylene Glycols / Q000008:administration & dosage*; D020641:Polymorphism, Single Nucleotide; D011379:Prognosis; D011994:Recombinant Proteins / Q000008:administration & dosage; D016896:Treatment Outcome; D014803:Vitamin B Complex / Q000097:blood
D000998:Antiviral Agents; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens; D016898:Interferon-alpha; D027501:Monocarboxylic Acid Transporters; D063065:Organophosphonates; D011994:Recombinant Proteins; C549233:SLC16A9 protein, human; D014803:Vitamin B Complex; D011092:Polyethylene Glycols; C053001:adefovir; D000225:Adenine; C100416:peginterferon alfa-2a; D002331:Carnitine
Adefovir; Carnitine; Chronic hepatitis B; Genome-wide association study; HBV-specific T cells; HBsAg loss; Peginterferon-alfa 2a; Response marker; SNP