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Immun AgeingImmunity & ageing : I & A1742-4933BioMed Central London 1742-4933-1-61567992510.1186/1742-4933-1-6Short Report+874(T→A) single nucleotide gene polymorphism does not represent a risk factor for Alzheimer's disease Galimberti Lorenza 1geriatri@policlinico.mi.itArosio Beatrice 1geriatri@policlinico.mi.itCalabresi Carmen 1geriatri@policlinico.mi.itScurati Silvia 1geriatri@policlinico.mi.itHamilton Susanna 1geriatri@policlinico.mi.itCarpini Simona Delli 1geriatri@policlinico.mi.itVergani Carlo 1erice1947@hotmail.comAnnoni Giorgio 2giorgio.annoni@unimib.it1 Department of Geriatrics, Ospedale Maggiore IRCCS, University of Milano, Milan, Italy2 Department of Clinical Medicine, Prevention and Medical Biotechnology, University of Milano-Bicocca, Mila, Italy2004 12 11 2004 1 6 6 30 9 2004 12 11 2004 Copyright © 2004 Galimberti et al; licensee BioMed Central Ltd.2004Galimberti et al; licensee BioMed Central Ltd.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In the recent years, several cytokines have been associated with Alzheimer's disease (AD) development and progression and many studies have correlated this risk with polymorphisms in the genes encoding these molecules. Also the type 1 cytokine interferon (IFN)-γ belongs to a cytokine class that affects the immune function; in fact it plays a major role in defence against viruses and intracellular pathogens but also in the induction of the immune-mediated inflammatory response. The aim of this study was to evaluate the role of IFN-γ in AD by studying the association of +874T→A IFN-γ gene polymorphism with AD. We included in this study 115 AD patients (70 women, 45 men, mean age 80) and 90 sex and age-matched healthy controls (HC, 51 women, 39 men, mean age 82) from northern Italy. Genomic DNA was extracted with the salting-out method from whole blood of all subjects; the genotyping at IFN-γ loci was assessed with ARMS-PCR. The data obtained from the +874T→A IFN-γ gene polymorphism analysis of AD patients and HC lack of any statistically significant differences also when stratified according to gender. In conclusion these results confirm the previous shown lack of association between +874T→A IFN-γ gene polymorphism and the risk of AD. However, other polymorphisms have been demonstrated to influence IFN-γ transcription and since natural killer cells of AD patients show higher production of the cytokine, further analysis will be necessary to clarify the role of this gene in the pathogenesis of the disease.
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In the human brain several cell types are responsible for initiating and amplifying a specific inflammatory response. In Alzheimer disease (AD) signs of an inflammatory activation of microglia and astroglia are present both inside and outside amyloid deposits. Cell cultures and animal models suggest an interactive relationship between inflammatory response activation, reduced neuronal functioning and amyloid deposition. Furthermore cells associated with extracellular plaques within AD brains can produce a variety of cytokines, chemokines and other related proteins that influence plaque and tangle formation [1]. For these reasons cytokines could play a critical role in the pathogenesis of AD. In the recent years, several cytokines have been associated with AD development and progression and many studies have correlated this risk with polymorphisms in the genes encoding these molecules [2-4]. Inside this research area we described that single nucleotide polymorphisms (SNP)s of the intereleukin(IL)-10 and IL-6 genes were associated with highest risk of AD with apparent interaction between these two genes [5]; these results supported the theory that the overall risk of developing AD may be governed by a 'susceptibility profile' and reflected the combined influence of inheriting multiple high-risk alleles. Also the type 1 cytokine interferon (IFN)-γ belongs to a cytokine class that affects the immune function; in fact it plays a major role in defence against viruses and intracellular pathogens but also in the induction of the immune-mediated inflammatory response [6]. It has been reported that the polymorphism +874(T→A) of the gene encoding IFN-γ is associated with a different production of this molecule, in particular the T allele correlates with increased levels of the cytokine [7]. In regards to the hypothesis that IFN-γ SNP may represent a genetic risk factor for AD, a recent study did not support this possibility [8]. Therefore with reference to this paper we try to confirm their hypothesis in a sample of patients, that were already genotyped for apolipoprotein E (ApoE), IL-10 and IL-6 [5]. We included in this study 115 AD patients (70 women, 45 men, mean age 80 ± 2) and 90 sex and age-matched healthy controls (HC, 51 women, 39 men, mean age 82 ± 2) from northern Italy. The clinical diagnosis of AD fulfilled the international criteria of the DMS IV and NINCDS-ADRDA; every patient had a recent brain magnetic resonance imaging (MRI)/computed tomography (CT) scan available. Cognitive performances were assessed according to the Mini-Mental State Evaluation (MMSE). Only AD and HC without clinical signs of inflammation (e.g. normal body temperature, no concomitant inflammatory condition) were eligible in order to minimize the risk of clinical or sub-clinical inflammatory processes. Blood chemistry tests were done and subjects with an abnormal red blood cell sedimentation rate or altered albumin and transferrin plasma levels were excluded. AD patients were further selected according to their C reactive protein (CRP) plasma levels and anyone with CRP above 5 mg/L (mean + 2 standard deviations of control values) were not eligible. Informed consent was obtained from all the subjects or their relatives. Genomic DNA was extracted with the salting-out method from whole blood of all subjects; the genotyping at IFN-γ loci was assessed with the same amplification method (ARMS-PCR) described by Scola et al. [8]. The genotype frequencies in the study groups were compared by the chi-square (χ) test in order to calculate significant different SNP distribution between AD patients and controls (Table 1). The data obtained from the +874T→A IFN-γ gene polymorphism analysis of AD patients and HC lack of any statistically significant differences also when stratified according to gender (data not shown). The percentage of the different genotypes was similar in AD compared with HC (T/T: 17.4% vs. 16.8% ; T/A: 50.4% vs. 55.1% ; A/A 32.2% vs. 28.1%) and consequently also the allele distribution shows no differences (T: 42.6% vs. 44.4% ; A: 57.4% vs. 55.6%). Our genotype distribution looks very similar to that found by Scola et al. [8]. In conclusion these results confirm the lake of association between +874T→A IFN-γ gene polymorphism and the risk of AD. Nevertheless other polymorphisms have been demonstrated to influence IFN-γ transcription and since natural killer cells of AD patients show higher production of the cytokine, further analysis will be necessary to clarify the role of this gene in the pathogenesis of the disease [9,10].

Table 1 IFN-γ genotype and allele distribution

	Genotype	Allele	
	T/T(H)	T/A(I)	A/A(L)	T	A	
	
AD	20(17,4%)	58(50,4%)	37(32,2%)	98(42,6%)	132(57,4%)	
HC	15(16,8%)	49(55,1%)	25(28,1%)	79(44,4%)	99(55,6%)	
Genotype χ2 = 0.488, df = 2, p = 0.783

Allele χ2 = 0.232, df = 1, p = 0.63

In brackets there are the corresponding phenotype high (H), intermediate (I) and low (L).
==== Refs
Hùll M Lieb K Fiebich L  Pathways of inflammatory activation in Alzheimer's disease: potential targets for disease modifying drugs Curr Med Chem 2002 9 83 88 11860350 
Meda L Baron P Prat E Scarpini E Scarlato G Cassatella MA Rossi F  Proinflammatory profile of cytokine production by human monocytes and murine microglia stimulated with beta-amyloid J Neuro immunol 1999 93 45 52 
Mrak RE Griffin WST  Interleukin-1, neuroinflammation, and Alzheimer's disease Neurobiol Aging 2001 22 903 908 11754997 10.1016/S0197-4580(01)00287-1 
Pola R Flex A Gaetani E Dal Lago A Gerardini L Pola P  The -174 G/C polymorphism of the interleukin-6 gene promoter is associated with Alzheimer's disease in an italian population Neuroreport 2002 13 1645 1647 12352619 10.1097/00001756-200209160-00015 
Arosio B Trabattoni D Galimberti L Bucciarelli P Fasano F Calabresi C Cazzullo CL Vergani C Annoni G Clerici M  Interleukin-10 and interleukin-6 gene polymorphisms as risk factors for Alzheimer's disease Neurobiol Aging 2004 25 1009 1015 15212825 10.1016/j.neurobiolaging.2003.10.009 
Billiau A Heremans H Vermeire K Matthys P  Immunomodulatory properties of interferon-gamma. An update Ann NY Acad Sci 1998 856 22 32 9917861 
Pravica V Perrey C Stevens A Lee JH Hutchinson IV  A single nucleotide polymorphism in the first intron of the human IFN-gamma gene: absolute correlation with a polymorphic CA microsatellite marker of high IFN-gamma gene Hum Immunol 2000 61 863 866 11053629 10.1016/S0198-8859(00)00167-1 
Scola L Licastro F Chiappelli M Franceschi C Grimaldi LM Crivello A Colonna-Romano G Candore G Lio D Caruso C  Allele frequencies of +874T -> A single nucleotide polymorphism at the first intron of IFN-gamma gene in Alzheimer's disease patients Aging Clin Exp Res 2003 15 292 295 14661818 
Miyake K Nakashima H Akahoshi M Inoue Y Nagano S Tanaka Y Masutani K Hirakata H Gondo H Otsuka T Harada M  Genetically determined interferon-gamma production influences the histological phenotype of lupus nephritis Rheumatology 2002 41 518 524 12011374 10.1093/rheumatology/41.5.518 
Solerte SB Cravello L Ferrari E Fioravanti M  Overproduction of IFN-gamma and TNF-alpha from natural killer (NK) cells is associated with abnormal NK reactivity and cognitive derangement in Alzheimer's disease Ann NY Acad Sci 2000 917 331 340 11268360

