Implication Of IL-33、ADAM10 Gene Polymorphism In Northern Han Chinese Patients With Late-onset Alzheimer’s Disease

Part I Implication of IL-33 Gene Polymorphism in Chinese Patients with late-onset Alzheimer’s Disease Research BackgroundAlzheimer’s disease (AD) is a generative disease occurred in central nervous system with unknown pathogenesis as yet. This disease is featured by progressive hypomnesis and cognitive dysfunction. It is currently the most common reason for senile dementia. Pathologically, the characteristic changes of AD is senile plaques resulting from (3-amyloid (Aβ) deposition, neurofibrillary tangles derived from aberrant tau protein aggregation, varying degree reduction of cerebral cortex cells, hyperplasia and hypertrophy of astrocytes. According to epidemiologic data, about 35 million people worldwide have Alzheimer’s disease. In addition, the incidence of the disease doubles every five years older with aging. AD can be divided into early-onset familial one and late-onset AD (LOAD) based on the age of onset. The age of onset of LOAD is above 65, accounting for more than 90% of the total AD. Affected greatly by genetic background, the pathogenesis of AD is rather complicated and remains unknown as yet. Some researches indicated that individual innate immune response and consequent neuroimmune response play important role in the pathogenesis of AD. Furthermore, the incidence risk of AD correlated to a great degree with gene mutation of immune matrix, including interleukin-1 (IL-1), IL-6 and IL-18, etc.IL-33 is a new member of the super family of cytokine, IL-1. It is expressed in basal cells like epidermal cells and endothelial cells, and inflammatory stimulus can promote the expression of IL-33. IL-33 can be expressed by multiple cells of central nervous system (CNS) and tissues. Activated by TLR agonist, astrocyte seems to produce IL-33. IL-33 can also produce anti-inflammatory factors after induction by glial cell. IL-33 therefore probably plays a pathogenic role in the inflammatory diseases of CNS. In addition, IL-33 plays a certain protecting role in the generation and development of arterial atherosclerosis. The later is a well-known risk factor of AD. IL-33 therefore probably plays an important role in the pathogenesis of AD.Recent studies demonstrated that gene polymorphism of IL-33 (rs 11792633 and rs7044343) correlates significantly with AD in Caucasian population. In order to test whether IL-33 is also the candidate gene of AD in Asian population and to define the correlation of IL-33 with LOAD in north Chinese Han population, we conducted the initial studies of IL-33 gene polymorphism in Asian Han population.ObjectiveThe correlation of LOAD and IL-33 gene polymorphism was examined by analyzing and comparing the distribution difference of allele frequency and genotype frequency at the polymorphic loci of rsl792633 and rs7044343 of IL-33 genes in the LOAD group and control group.Study objectAccording to the probable criteria of AD in the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s disease and Related Disorders Association (NINCDS-ADRAD),322 cases of LOAD patients were included in this study.382 visitors of body examination at the same period were included as controls. All study objects were from north Chinese Han population and they did not have kinship.MethodsThe ordinary properties of the study objects were determined so that there was insignificant difference in the age, sex, BMI, blood pressure parameters, high-density lipoprotein, low-density lipoprotein, cholesterol and blood sugar between these two study groups. The testees were classified according to ApoE gene. Peripheral blood was collected and genomic DNA was extracted after anti-coagulation treatment. Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) was applied to detect the genotype and alleles at the single nucleotide polymorphic loci rs11792633 and rs7044343 of IL-33 gene.Statistical analysisStatistical analysis was performed by using SPSS 11.5 software package. The difference of general properties between two populations was tested with student-t test and Chi-square test. Alquein 3.0 software was used to test the Hardy-Weinberg balance of genotype distribution frequency of each SNP locus. The distribution frequency of alleles and genotypes of SNPs in LOAD group and control group was tested withχ2 test. Yates calibration was used when necessary. Odds ratio (OR) and 95% confidence interval were calculated and served as the relative risk degree. The confusing factors were calibrated by using multi-factor Logistic regression analysis. Linkage disequilibrium between two SNP was tested by using SHE and Haploview3.32 program and haplotype was constructed. All statistical tests were two-tailed tests and statistical significance was P< 0.05.Results1. Two study groups were classified according to ApoE gene. Number of ApoEs4 (+) cases in the AD group was 138, while that in the control group was 92, and there was statistical significance (P< 0.001). As expected, APOEs4 allele carriers have higher risk of LOAD than APOEε4 (-) patients (OR=2.36,95% CI:1.71-3.26, P< 0.01).2. The distribution of the genotype frequency and allele frequency of SNPrsl 1792633 in both groups has statistical significance (for genotype, p=0.018; for allele, p=0.005). After classified according to ApoEε4 alleles, the distribution of the genotype frequency and allele frequency of rs 11792633 in the subgroup ApoEs4 (-) still has statistical significance (for genotype, p=0.042; for alleles, P=0.013); the subordinate alleles (T) plays protecting role in AD. 3. The distribution of the genotype frequency and allele frequency of SNPrs704434 in both groups did not have statistical significance (or genotype, p=0.153; for alleles, P=0.276). Significant significance was still not observed after classification according to carrying of ApoEε4 alleles.4. After eliminating the effects of age, sex and ApoEs4 alleles, the risk of LOAD in earriers of rs11792633 alleles, T (TT+CT) was 0.67 times higher than that in non-carriers of rs11792633 alleles, T (CC), (OR=0.67,95%CI=0.48-0.92, P=0.015), based on multi-factor logistic regression analysis.5. The frequency of haplotype TC in AD group was lower significantly in the control group (31.9% vs.37.2%, OR=0.77,95% CI=0.62-0.96, P=0.02).Conclusion1. The results suggested that ApoE gene polymorphism correlates with LOAD susceptibility in North Chinese Han population, and that carriers of ApoEs4 alleles have profound higher risk of LOAD.2. The results also suggested that IL-33 gene polymorphism correlates with LOAD susceptibility in North Chinese Han population, and that alleles T of rs11792633 and haplotype TC of IL-33 can reduce the risk of LOAD. Gene polymorphism of SNPrs7044343 was not clearly correlated with LOAD. PartⅡOn the Correlation of Late-onset Alzheimer’s Disease in North Chinese Han Population with Gene Polymorphism of ADAM10Research backgroundAmong the pathogenesis and hypothesis of AD, the most important one is aberrantβ-amyloid (Aβ) deposition. A(3 mainly originates from the amyloid precursor protein (APP). After cleaved by (3-secretase and y-secretase, the neurotoxic Aβis produced. However, APP is believed to have another cleaving pathway, i.e. APP can be cleaved by a secretase, and the resulting cleavage product is APPs-a, thereby blocking the synthesis of Aβand supplying a new target for AD treatment. Currently, it is proved that ADAM 10 (disintegrin-metalloprotease-10) is an a secretase of APP.At present, some experiments have detected nine SNP in ADAM 10 gene, and it was found that rs2305421 gene polymorphism is correlated with AD (P=0.003). Such correlation has proved in a large-scale genome-wide association study. The experiment mentioned above was targeted to Caucasian population. No such experiment has ever targeted to Asian population to the best of our knowledge as yet.ObjectiveThe coRRelation of LOAD and gene polymorphism of ADAM 10 was investigated by analyzing and comparing the distribution difference of allele frequency and genotype frequency at the polymorphic loci rs 2305421 of ADAM 10 in the LOAD group and control group.Study objectAccording to the probable criteria of AD in the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s disease and Related Disorders Association (NINCDS-ADRAD),400 cases of LOAD patients were included in this study.388 visitors of body examination during the same period were included as controls. All study objects were from north Chinese Han population and they did not have kinship. MethodsThe general properties of the study objects were determined so that there was insignificant difference in the age, sex, BMI, blood pressure parameters, high-density lipoprotein, low-density lipoprotein, cholesterol and blood sugar between these two study groups. The testees were classified according to ApoE gene. Peripheral blood was collected and genomic DNA was extracted after anti-coagulation treatment. Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) technology was applied to detect the genotype and alleles at the single nucleotide polymorphic loci rs23054213 of ADAM10 gene.Statistical analysisStatistical analysis was performed by using SPSS11.5 software package. The difference of general properties between two groups was tested with student-t test and Chi-square test. Alquein 3.0 software was used to test the Hardy-Weinberg balance of genotype distribution frequency of each SNP locus. The distribution frequency of alleles and genotypes of SNPs in LOAD group and control group was tested withχ2 test. Yates calibration was used when necessary. Odds ratio (OR) and 95% confidence interval were calculated and served as the relative risk degree. The confusing factors were calibrated by using multi-factor Logistic regression analysis. Linkage disequilibrium between two SNP was tested by using SHE and Haploview3.32 program and haplotype was constructed. All statistical tests were two-tailed tests and statistical significance was P< 0.05.Conclusion1. Testees in two study groups were classified according to ApoE gene. Number of ApoEs4 (+) cases in the AD group was 22, while that in the control group was 86, and there was statistical significance (P< 0.001). As expected, APOEs4 allele earriers have significant higher risk of LOAD than APOEε4 (-) patients (OR=2.36, 95% CI:1.71-3.26, P< 0.01).2. The distribution of the genotype frequency and allele frequency of SNPrs2305421 in both groups has no statistical significance (for genotype, p=0.8; for alleles, P=0.783).3. After classified according to ApoEε4 alleles, the distribution of the genotype frequency and allele frequency of rs 11792633 in the subgroup ApoEε4 (-) still did not have statistical significance (for genotype, p=0.124; for alleles, P=0.08).4. In the subgroup ApoEε4 (+), the distribution of genotype frequency and allele frequency at locus rs2305421 had statistic significance (for genotype, p=0.035; for allele, p=0.037). The frequency of allele G in AD group was significantly lower than that in the control group, and allele G was a protecting gene (OR=0.682; 95%CI=0.476-0.978; P=0.037; Power=55%).5. After eliminating the effects of age, sex and ApoEs4 alleles, the recessive model of gene polymorphism at locus rs2305421 (GG:AA+AG) still significantly correlated with AD. (OR=0.611,95%CI=0.408-0.931, P=0.023) based on multi-factor logistic regression analysis.Conclusion1. The results suggested that ApoE gene polymorphism correlates with LOAD in North Chinese Han population, and that carriers of ApoEε4 alleles have profound higher risk of LOAD.2. The results also suggested that gene polymorphism of AD AM10 correlates with LOAD in North Chinese Han population, especially in the patients with ApoEs4 (+), and that alleles G of rs11792633 of ADAM10 can reduce the risk of LOAD.