Transcript interleukin-6 gene polymorphisms and survival after - dr

INTERLEUKIN-6 GENE
POLYMORPHISMS AND SURVIVAL
AFTER ALLOGENEIC HAEMATOPOIETIC
STEM CELL TRANSPLANTATION
Z. Ambruzova1, L. Raida2, P. Jindra3, B. Vidan-Jeras4, F. Mrazek1,
E.Faber2, J. Onderkova1, J. Pretnar5, K. Indrak2, M. Petrek1
1Laboratory
of Immunogenomics, Dept. of Immunology , 2Department of
Haematooncology, Medical Faculty Palacky University and University Hospital
Olomouc, Czech Republic, 3 Department of Haematology and Oncology, University
Hospital Pilsen, 4Blood Transfusion Center of Slovenia, 4Department of
Haematology, University Clinical Centre Ljubljana, Slovenia
Supported by Czech Govt. Funding MSM 6198959205
and IGA MZCR NR9099
BACKGROUND
 the allogeneic haematopoietic stem cell transplantation
(aHSCT) outcome is substantially influenced by various
factors on the side of the recipient and/or donor
 different non-HLA genetic systems are studied for their
potential effect on graft-versus-host disease (GVHD),
infections, transplant-related mortality and overall
survival (Dickinson 2005)
 the identification of particular gene variants as the risk
factors for development of posttransplantation
complications could be used for their prediction,
prevention and individual treatment
INTERLEUKIN-6
 interleukin-6 (IL-6) is a pro-inflammatory cytokine produced
by broad spectrum of cell types
 IL-6 is involved in pathogenesis of the immune-mediated
complications of aHSCT
 IL-6 production is affected by functional single nucleotide
polymorphism in the promoter region at the position -174
G/C (G allele is associated with increased IL-6 levels)
(Fishman 1998)
 IL-6 gene polymorphism of the recipient and/or the donor
was associated with acute or chronic GVHD in several
studies (Cavet 2001, Socie 2001, Rocha 2002, Mullighan 2004, Karabon
2005)
AIM OF THE STUDY
to investigate if there exists an association between:
IL-6 gene polymorphisms
-174 G/C and/or nt565 G/A
Overall survival
Transplant-related
after aHSCT
mortality in 1st year
after aHSCT*
* death from any cause, other than progression of the underlying disease during 1 year after aHSCT
INVESTIGATED SUBJECTS
Number of donor-recipient pairs
center Olomouc
center Ljubljana
center Pilsen
Median age, years (range)
patients
donors
Recipient sex
female
male
Diseases
acute leukemia (AML, ALL)
chronic leukemia (CML,CLL)
NHL
other
Conditioning regimen
non-myeloablative
myeloablative
43 (17-64)
40 (16-70)
72
94
96
26
14
30
70
96
166
88
53
25
Donor HLA compatibility
identical
mismatched
Donor type
sibling
other related donor
unrelated
Graft source
PBSC
BM
Sex of donor and recipient
male with female donor
all others combinations
166
0
117
4
45
144
22
35
131
METHODS
1. Genotyping
Polymerase Chain Reaction with Sequence Specific Primers (PCR-SSP)
IL-6-174 G/C (rs1800795)
(primers adopted from Marshall 2001)
Specific 1 (wild type) *G: 5´AATGTGACGTCCTTTAGCATG3´
Specific 2 (mutant type) *C: 5´AATGTGACGTCCTTTAGCATC3´
Constant: 5´TCGTGCATGACTTCAGCTTTA3´
IL-6 nt565 G/A (rs1800797)
(primers designed according to the reference IL-6 gene sequence NT_007819.16)
Specific 1 (wild type) *G: 5´TAACTGCACGAAATTTGAGGG3´
Specific 2 (mutant type) *A: 5´TAACTGCACGAAATTTGAGGA3´
Constant: 5´TCTGAACTGAGTTTCCTCTGA3´
2. Statistics
Conformity to the Hardy-Weinberg equilibrium: Chi-square test
Overall survival and 1st year TRM statistics: Kaplan-Maier analysis, Log-rank
test (comparison between genotypes)
RESULTS
 decrease of overall survival among IL-6-174 GG
(p=0.026) or GC recipients (p=0.042) compared to CC
homozygous individuals (Figure 1)
 shorter overall survival in IL-6 nt565 GG homozygotes
than in patients with AA genotype (p=0.03) (Figure 2)
 higher probability of 1 year TRM in group of recipients
with IL-6-174 and nt565 GG genotypes compared to
those with IL-6-174 CC (p=0.016) and IL-6 nt565 AA
(p=0.022) genotypes (Figure 3)
 no effect of IL-6 gene polymorphisms of the donor for
overall survival or TRM was observed
Genotype and allele frequencies of the IL-6
SNPs in the groups of patients and donors
IL-6-174 G/C*
Patients
Donors IL-6 nt565 G/A * Patients Donors
Genotype GG
0.28
0.22
Genotype GG
0.30
0.24
Genotype GC
0.49
0.56
Genotype GA
0.49
0.55
Genotype CC
0.23
0.22
Genotype AA
0.21
0.21
Allele G
0.53
0.50
Allele G
0.55
0.51
Allele C
0.47
0.50
Allele A
0.45
0.49
* Distribution of genotypes in particular groups was in compliance with Hardy-Weinberg equilibrium
Both IL-6 SNPs were in tight linkage disequilibrium
Figure 1: Comparison of overall survival
after aHSCT according to IL-6-174
genotypes of the recipient
Mean survival:
GG genotype
GC genotype
CC genotype
28.5 months
43.6 months
53.3 months
Log-rank test:
GG vs. CC
GC vs. CC
p=0.03
p=0.04
Figure 2: Comparison of overall survival
after aHSCT according to IL-6 nt565
genotypes of the recipient
Mean survival:
GG genotype
GA genotype
AA genotype
Log-rank test:
GG vs. AA
27.4 months
46.2 months
50.7 months
p=0.03
Figure 3: Probability of TRM according to
recipient IL-6-174 and nt565 genotypes
IL-6 nt565
GG vs. AA
p=0.016
IL-6-174 GG genotype
IL-6-174 CC genotype
Months
Mean survival:
GG genotype 8.8 months
CC genotype 10.8 months
Probability
Probability
IL-6-174
GG vs. CC
p=0.022
IL-6 nt565 GG genotype
IL-6 nt565 AA genotype
Months
Mean survival:
GG genotype 8.8 months
AA genotype 10.7 months
CONCLUSION
Our study revealed association between IL-6-174 GG and
IL-6 nt565 GG genotypes and decreased overall survival
and increased one year TRM after aHSCT in Czech and
Slovenian patients after aHSCT.
This data suggest that IL-6 gene polymorphisms, beside
its impact on development of graft versus host disease,
may affect also survival after aHSCT.
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