Association of an interleukin 1 alpha polymorphism with Alzheimer's disease.
BACKGROUND
Retrospective epidemiologic studies suggest that individuals exposed to anti-inflammatory agents such as nonsteroidal anti-inflammatory drugs have a lower probability of developing AD as well as an older age at onset for the illness. Neuroinflammation may play an important role in the pathogenesis of AD. Interleukin 1 (IL-1), a potent proinflammatory cytokine, is colocalized immunohistochemically to neuritic plaques, a requisite neuropathologic feature for AD. A polymorphism in the 5'-flanking regulatory region at -889 of the IL-1 alpha gene (a C-to-T transition designated as IL-1A[-889] allele 2) may cause an overexpression of IL-1 alpha, a finding shown to be associated with inflammatory diseases. The IL-1A(-889) allele 2 polymorphism may be associated with AD pathogenesis.


METHODS
A total of 259 patients with AD and 192 nondemented control subjects were included from two different centers (Indianapolis, IN, and Munich, Germany). Genotyping for APOE alleles and IL-1A(-889) allele 2 was performed by PCR-based amplification followed by restrictive endonuclease digestion. Statistical analyses were conducted by center-, gender group-, and age group-stratified Mantel-Haenszel odds ratios, CI, and p values.


RESULTS
The allele frequency of IL-1A(-889) allele 2 was 46% in clinically diagnosed patients with probable AD versus 34% in control subjects from the combined centers.


CONCLUSIONS
The authors found an increased risk for AD with an estimated Mantel-Haenszel odds ratio of 1.68 (95% CI 1.1 to 2.6; p = 0.022) for heterozygous carriers and 7.2 (95% CI 2.0 to 24.5; p = 0.003) for individuals homozygous for IL-1A(-889) allele 2. They found no evidence for an interaction between the IL-1A and the apoE epsilon 4 polymorphisms (carriers and homozygotes), age, or gender with regard to conferred risk. The data strongly support an association between the IL-1A(-889) allele 2, especially in homozygotes, and later-onset AD.
Du
Y
Y
Departments of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, 46202, USA.
Dodel
R C
RC
Eastwood
B J
BJ
Bales
K R
KR
Gao
F
F
Lohmüller
F
F
Müller
U
U
Kurz
A
A
Zimmer
R
R
Evans
R M
RM
Hake
A
A
Gasser
T
T
Oertel
W H
WH
Griffin
W S
WS
Paul
S M
SM
Farlow
M R
MR
D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D000544:Alzheimer Disease / Q000235:genetics* / Q000276:immunology; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics; D016022:Case-Control Studies; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D005260:Female; D005787:Gene Frequency; D006580:Genetic Carrier Screening; D005838:Genotype; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007375:Interleukin-1 / Q000235:genetics*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011110:Polymorphism, Genetic / Q000235:genetics*; D018570:Risk Assessment
D053327:Apolipoprotein E4; D001057:Apolipoproteins E; D007375:Interleukin-1