VA/Duke 4x8 Poster Template

1
Serum Proteomic Profiles Associated with IL28B
Genotype among CHC Patients
Jeanette J. McCarthy1, Derek Cyr1, Joseph Lucas,
1 J. Will Thompson, 1 Keyur Patel2, Alexander
Thompson2, Hans L. Tillmann,2, Paul J. Clark2,
M. Arthur Moseley1 and John G. McHutchison2.
1 Institute for Genome Sciences and Policy, Duke
University, Durham, NC 2 Duke Clinical Research
Institute and Duke University Medical Center,
Durham, NC

• CBG metaprotein composition shown in Figure 2.

• Conclusions
• IL28B rs12979860 is strongly associated with
  serum levels of corticosteroid binding globulin
  peptides.
• CBG, also known as Transcortin, is a major
  high-affinity plasma transport protein for
  glucocorticoids and progestins and is expressed
  primarily in the liver.
• IL28Bs effect on viral clearance may be partly
  mediated through the action of steroid hormones.
• Studies that incorporate direct measures of
  cortisol and CBG may provide further validation
  of the role of corticosteroids in
  IL28B-associated viral clearance.

• Background
• SNP near the gene IL28B (encoding IFN-?3) are
  associated with both spontaneous and treatment
  (Peg-IFN Riba) induced clearance of hepatitis C
  virus (HCV). 
• The underlying genetic variant(s) responsible for
  this observed association remains to be
  identified, yet several SNPs, including
  rs12979860, appear to be robust markers of its
  effect. 
• In an effort to gain further insight into the
  function of this locus, we carried out
  association analysis of rs12979860 with
  expression of serum protein quantitative traits
  in a cohort of patients with chronic hepatitis C
  (CHC).
• Methods
• Subjects 41 HCV genotype 1 CHC patients from
  the Duke Liver Clinic with serum samples
  available prior to treatment and DNA available
  for genetic analysis.
• IL28B rs12979860 genotyping method TaqMan.
• Proteomic data generated using LC-MS/MS analysis
  of pre-treatment serum samples immunodepleted
  using MARS14 columns and digested with trypsin.
• Analysis Peptides with protein identifications
  were grouped using a latent factor model with
  informative priors to classify the peptides into
  110 metaproteins. Metaproteins were each
  analyzed for association with IL28B genotype
  using one-way analysis of variance.

• Results
• Subject characteristics Caucasian (78) males
  (61) mean age 47.4 years sustained virologic
  responders to treatment (63).
• LC-MS/MS generated 4,186 peptides with positive
  identifications, which latent factor modeling
  grouped into 110 metaproteins.
• Two metaproteins significantly associated with
  IL28B genotype the liver protein Corticosteroid
  Binding Globulin (CBG p 9.210-6) and
  complement component C5 (p 0.005). Only CBG
  remained significant after correction for
  multiple testing.
• rs12979860 C (responder) allele was associated
  with lower levels of CBG metaprotein and
  explained 38 of the variance in CBG metaprotein.
  (Figure 1).

Figure 3. Ingenuity Pathway Analysis.
Figure 2. CBG metaprotein peptide composition.
Each gray bar is a representation of the labeled
protein. Red sections represent polypeptides
from isotope groups that are in the factor and
black sections represent polypeptides from the
isotope groups that are identified in the data
set but are not in the factor. Gray represents
sections of the protein that are not identified
in the data set. Coverage is the percent of
identified peptides from that protein that are in
the factor and signature is the percent of the
factor that comes from the associated protein.
Note that the sum of signature is lt1 because
there are unidentified peptides in the factor
that are not shown in the figure.
Figure 1.
This study was funded in large part by a generous
grant from the David H Murdock Institute for
Business and Culture via the M.U.R.D.O.C.K. Study
and NIH CTSA award 1 UL1 RR024128-01 to Duke
University.