Changes in Expression of Key Genes in Alzheimer's Disease: A Specific Brain Tissue Change.

Alzheimer's disease (AD) is an irreversible and neurodegenerative disorder. Its etiology is not clear, but the involvement of genetic components plays a central role in the onset of the disease. In the present study, the expression of 10 genes (APP, PS1 and PS2, APOE, APBA2, LRP1, GRIN2B, INSR, GJB1, and IDE) involved in the main pathways related to AD were analyzed in auditory cortices and cerebellum from 29 AD patients and 29 healthy older adults. Raw analysis revealed tissue-specific changes in genes LRP1, INSR, and APP. A correlation analysis showed a significant effect also tissue-specific AD in APP, GRIN2B, INSR, and LRP1. Furthermore, the E4 allele of the APOE gene revealed a significant correlation with change expression tissue-specific in ABPA2, APP, GRIN2B, LRP1, and INSR genes. To assess the existence of a correction between changes in target gene expression and a probability of AD in each tissue (auditory cortices and cerebellum) an analysis of the effect of expressions was realized and showed that the reduction in the expression of the APP in auditory cortex and GRIN2B cerebellum had a significant effect in increasing the probability of AD, in the same logic, our result also suggesting that increased expression of the LRP1 and INSR genes had a significant effect on increasing the probability of AD. Our results showed tissue-specific gene expression alterations associated with AD and certainly opened new perspectives to characterize factors involved in gene regulation and to obtain possible biomarkers for AD.

CDK10, CDK11, FOXO1, and FOXO3 Gene Expression in Alzheimer's Disease Encephalic Samples.

Alzheimer's disease (AD) is a progressive neuroinflammatory and neurodegenerative disorder that affects different regions of the brain. Its pathophysiology includes the accumulation of ß-amyloid protein, formation of neurofibrillary tangles, and inflammatory processes. Genetic factors are involved in the onset of AD, but they are not fully elucidated. Identification of gene expression in encephalic tissues of patients with AD may help elucidate its development. Our objectives were to characterize and compare the gene expression of CDK10, CDK11, FOXO1, and FOXO3 in encephalic tissue samples from AD patients and elderly controls, from the auditory cortex and cerebellum. RT-qPCR was used on samples from 82 individuals (45 with AD and 37 controls). We observed a statistically significant increase in CDK10 (p = 0.029*) and CDK11 (p = 0.048*) gene expression in the AD group compared to the control, which was most evident in the cerebellum. Furthermore, the Spearman test demonstrated the presence of a positive correlation of gene expression both in the auditory cortex in the AD group (r = 0.046/p = 0.004) and control group (r = 0.454/p = 0.005); and in the cerebellum in the AD group (r = 0.654 /p < 0.001). There was no statistically significant difference and correlation in the gene expression of FOXO1 and FOXO3 in the AD group and the control. In conclusion, CDK10 and CDK11 have high expression in AD patients compared to control, and they present a positive correlation of gene expression in the analyzed groups and tissues, which suggests that they play an important role in the pathogenesis of AD.

Decrease of miR-125a-5p in Gastritis and Gastric Cancer and Its Possible Association with H. pylori.

PURPOSE: The aim of this study was to evaluate the expression of miR-125a-5p in patients with dyspeptic symptoms and gastric cancer, correlating them with the development of this cancer and H. pylori. METHODS: Patients were divided in groups according to histopathological analysis (control, gastritis, and cancer groups). Polymerase chain reaction was performed to detect H. pylori and real-time quantitative PCR to determine miR-125a-5p expression. RESULTS: H. pylori was detected in 44% of the patients, with prevalence in the gastritis and cancer groups. A statistically significant decrease of miR-125a-5p expression was found in the control positive (p = 0.0183*), gastritis positive (p = 0.0380*), and cancer positive (p = 0.0288*) groups when compared with the control negative group. CONCLUSION: We suggest that decreased expression of the miRNA-125a-5p associated with the presence of the H. pylori is an important mechanism in gastric diseases and could be a possible marker for early diagnosis of gastric cancer.

Interleukin 8 (-251 T>A) polymorphism in children and teenagers infected with Helicobacter pylori.

BACKGROUND: Helicobacter pylori (H. pylori) is a gram-negative bacterium that colonizes the human stomach and causes a variety of gastric diseases. This study evaluated the correlations between the -251 (T>A) (rs4073) polymorphism of interleukin-8 (IL-8), the etiology of gastric disease, and H. pylori infection in pediatric and adolescent patients. METHODS: DNA samples were obtained from 285 gastric biopsies from pediatric patients. H. pylori was detected by PCR, whereas PCR-RFLP was used to characterize the -251 (T>A) polymorphism of IL-8. RESULTS: The histological analysis revealed the presence of gastritis in 158 patients (55.44%). H. pylori was found in 71 samples (24.9%). The -251 (T>A) polymorphism revealed that 58 (29.47%) samples were TT, 143 (50.18%) samples were TA, and 84 (20.35%) samples were AA. CONCLUSIONS: Our findings suggest that IL8-251 A allele may be an important risk factor for the development of gastric disease when associated with H. pylori infection.

Change in INSR, APBA2 and IDE Gene Expressions in Brains of Alzheimer's Disease Patients.

BACKGROUND: Alzheimer's disease (AD) is defined as a progressive and irreversible neurodegenerative disorder, the onset of which is mainly characterized by decreased cognition, memory loss, and mental confusion. OBJECTIVE: This study sought to quantify mRNA expression of the APBA2, INSR and IDE genes in brain samples from patients with AD and controls. METHODS: We investigated the mRNA expression of the APBA2, INSR and IDE genes in 150 RNA samples from entorhinal cortex, auditory cortex, and the hippocampus of individuals with AD and elderly controls using real time PCR. APOE genotypes were determined by PCR-RFLP. RESULTS: When the total brain samples were analyzed collectively, a decrease in IDE gene expression was found in AD patients relative to healthy elderly controls. However, when the samples were analyzed separately according to the region of the brain, there was a significant upregulation of INSR expression in the hippocampus and the entorhinal cortex in the AD patient group. We did not observe any statistical differences when gene expression was compared in the different regions of the brain of AD patients. When the E4 allele of apolipoprotein-E was considered in AD patients, the presence of this allele was found to be associated with decreased APBA2 gene expression. The same analysis using the INSR and IDE genes showed no significant statistical differences. CONCLUSION: These results support the hypothesis that APBA2, IDE, and particularly INSR gene expression in different areas of Alzheimer's patient's brains could represent new markers for use in clinical diagnoses in the near future.

Downregulated Expression of E-cadherin and TP53 in Patients with Gastric Diseases: the Involvement of H. pylori Infection and Its Virulence Markers.

PURPOSE: Gastritis caused by infection with Helicobacter pylori is characterized by chronic inflammation and damage in gastric tissue, which is a main risk factor for gastric cancer. Associated with H. pylori, the TP53 gene tumor suppressor and the cell adhesion glycoprotein epithelial cadherin develop a relevant role in the integrity and carcinogenesis of the epithelium. We aimed to detection of H. pylori and its main virulence markers and measured the messenger RNA (mRNA) expression levels of E-cadherin and TP53 genes. METHODS: The detection of H. pylori and its virulence markers, as well as the mRNA expression levels of E-cadherin and TP53 genes, were obtained for 161 samples of gastric biopsies including 37 with normal gastric tissue, 70 with gastritis, 24 from neoplastic tissue, and 27 from adjacent non-neoplastic by means of a quantitative real-time polymerase chain reaction. RESULTS: The mRNA expression levels of E-cadherin and TP53 were found to be decreased in patients with gastritis, independently of H. pylori infection. In samples from gastric patients, the neoplastic tissue showed an accentuated decrease of expression; on the other hand, the expression of E-cadherin was normal in adjacent non-neoplastic. CONCLUSIONS: No evidence was found of the involvement of the cagA and vacA genes in the decreased expression of E-cadherin and TP53. The process of carcinogenesis is complex, and the decrease of the E-cadherin gene expression and TP53 gene expression appears to contribute significantly.

Lack of association among TNF-α gene expression, -308 polymorphism (G > A) and virulence markers of Helicobacter pylori.

BACKGROUND: Tumor necrosis factor plays a critical role in the pathogenesis of gastric diseases such as gastric cancer, and an abnormal inflammatory response has frequently been observed in dyspeptic patients. Helicobacter pylori infection can induce a gastric mucosal inflammatory response that may be influenced by -308 (G > A) polymorphisms and gene expression of the TNF-α gene. METHODS: One hundred and thirty-four gastric biopsy samples were collected from patients of both genders (61♂ and 73♀, mean age 40.3 ± 24.2 years) with gastric symptoms. The -308 (G > A) polymorphism of TNF-α was characterized using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). The expression level was measured using real-time PCR, and relative quantification (RQ) was calculated using the comparative CT method (2(-ΔΔCT)). RESULTS: The analysis revealed an increase in TNF-α gene expression in patients with gastritis; on the other hand, no statistical differences were observed in patients with gastric cancer. In addition, no association was found among -308 polymorphism genotypes, virulence markers, or TNF-α gene expression. CONCLUSIONS: Helicobacter pylori induces a large increase in TNF-α expression in patients with gastritis, regardless of tissue inflammation, but after the tissue becomes neoplastic, the presence of bacteria did not influence expression. These results suggest that the TNF-α pathway may play an important role in the progression from gastritis to gastric cancer.

CNP and DPYSL2 mRNA expression and promoter methylation levels in brain of Alzheimer's disease patients.

Alzheimer's disease (AD) is a highly prevalent type of dementia in the elderly population. AD is a complex neurodegenerative disorder. Thus, epigenetic mechanisms that regulate gene expression might have an important role in AD. CNP (2',3'-Cyclic Nucleotide 3' Phosphodiesterase) gene encodes a protein used as an index of myelin alterations. DPYSL2 (Dihydropyrimidinase-like 2) is described as acting in structural and regulatory processes in the central nervous system, such as neural differentiation, neurotransmitter release, and stabilization of microtubules. In this study, we evaluated gene expression and epigenetic regulation of CNP and DPYSL2 genes in three postmortem brain regions (entorhinal and auditory cortices and hippocampus) of AD patients and healthy elderly controls. mRNA quantification was performed using qRT-PCR, and promoter DNA methylation patterns were determined by mass spectrometry using the Sequenom EpiTYPER platform. We observed CNP mRNA downregulation in entorhinal and auditory cortex in relation to the same regions of the control group. CNP alterations in the brain might suggest impairment in myelination leading to a synaptic and cognition loss. No AD-associated differences in CNP and DPYSL2 promoter DNA methylation were observed, suggesting that other mechanisms may be involved in mediating the observed CNP gene expression.

SORL1 and SIRT1 mRNA expression and promoter methylation levels in aging and Alzheimer's Disease.

Alzheimer's Disease (AD) is a neurodegenerative disorder and the most common cause of dementia among the elderly. Efforts have been made to understand the genetic and epigenetic mechanisms involved in the development of this disease. As SORL1 (sortilin-related receptor) and SIRT1 (sirtuin 1) genes have been linked to AD pathogenesis, we aimed to investigate their mRNA expression and promoter DNA methylation in post mortem brain tissues (entorhinal and auditory cortices and hippocampus) from healthy elderly subjects and AD patients. We also evaluated these levels in peripheral blood leukocytes from young, healthy elderly and AD patients, investigating whether there was an effect of age on these profiles. The comparative CT method by Real Time PCR and MALDI-TOF mass spectrometry were used to analyze gene expression and DNA methylation, respectively. SORL1 gene was differently expressed in the peripheral blood leukocytes and might act as a marker of aging in this tissue. Furthermore, we found that SORL1 promoter DNA methylation might act as one of the mechanisms responsible for the differences in expression observed between blood and brain for both healthy elderly and AD patients groups. The impact of these studied genes on AD pathogenesis remains to be better clarified.

Interleukin-8-251T > A, Interleukin-1α-889C > T and Apolipoprotein E polymorphisms in Alzheimer's disease.

An inflammatory process has been involved in numerous neurodegenerative disorders such as Parkinson's disease, stroke and Alzheimer's disease (AD). In AD, the inflammatory response is mainly located in the vicinity of amyloid plaques. Cytokines, such as interleukin-8 (IL-8) and interleukin-1α (IL-1α), have been clearly involved in this inflammatory process. Polymorphisms of several interleukin genes have been correlated to the risk of developing AD. The present study investigated the association of AD with polymorphisms IL-8 -251T > A (rs4073) and IL-1α-889C > T (rs1800587) and the interactive effect of both, adjusted by the Apolipoprotein E genotype. 199 blood samples from patients with AD, 146 healthy elderly controls and 95 healthy young controls were obtained. DNA samples were isolated from blood cells, and the PCR-RFLP method was used for genotyping. The genotype distributions of polymorphisms IL-8, IL-1α and APOE were as expected under Hardy-Weinberg equilibrium. The allele frequencies did not differ significantly among the three groups tested. As expected, the APOE4 allele was strongly associated with AD (p < 0.001). No association of AD with either the IL-1α or the IL-8 polymorphism was observed, nor was any interactive effect between both polymorphisms. These results confirm previous studies in other populations, in which polymorphisms IL-8 -251T > A and IL-1α-889C > T were not found to be risk factors for AD.

Promoter methylation analysis of SIRT3, SMARCA5, HTERT and CDH1 genes in aging and Alzheimer's disease.

Longevity related genes were investigated concerning promoter methylation. SIRT3, SMARCA5, HTERT and CDH1 promoters were analyzed in peripheral blood in relation to gender, age and Alzheimer's disease (AD). Methylation Specific PCR assay (MSP) was used. There were no significant differences in methylation frequencies of SIRT3, SMARCA5 and CDH1 among young, elderly and AD groups (p> 0.05), showing no association with aging or AD. On the other hand, HTERT methylation frequency was associated with the aging process, in that AD patients differed from elderly controls (p=0.0086), probably due to telomere and immune dysfunctions involved in AD pathogenesis.

Interleukin-6 polymorphisms, Helicobacter pylori infection in adult Brazilian patients with chronic gastritis and gastric adenocarcinoma.

BACKGROUND: The discovery of Helicobacter pylori offered the etiologic agent of the initiating event of the inflammatory cascade. It has been confirmed that the development of gastric cancer spans over several decades sequentially starting with the acquisition of H. pylori infection and the development of chronic gastritis. The IL-6 gene (Il-6), inflammatory cytokine and the single-nucleotide polymorphisms (SNPs) at the 5' flanking region of the Il-6 gene promoter (G or C at -174 base and at -572 or -597 C or A) have been identified with increased Il-6 levels. METHODS: Biopsies were collected from 168 patients. SNPs in Il-6-174 were analyzed by PCR-RFLP. RESULTS: Promoter SNP of Il-6 at -174 base were within Hardy-Weinberg equilibrium. We did not find any association between the frequencies of -174 polymorphism with specific histological type of gastric adenocarcinoma, but the G (guanine) allele at -174 was significantly higher in gastric adenocarcinoma than in patients with chronic gastritis. CONCLUSIONS: We observed an association between GG allele on -174 base with gastric cancer.

Apolipoprotein A-V gene polymorphism -1131T>C and Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disorder in the elderly and is also considered a progeroid genetic syndrome. The etiology of AD is complex and the mechanisms underlying its pathophysiology remain to be clarified. It has been suggested that a high serum cholesterol level is a risk factor for (AD), and that some polymorphisms of genes encoding proteins regulating cholesterol metabolism are associated with AD development. APOA5 is a recently discovered apolipoprotein involved primarily with triglyceride (TG) metabolism disorder. This study investigates the association of AD with the APOA5 gene -1131T>C polymorphisms in samples of 106 patients with Alzheimer's disease (AD), 76 elderly healthy controls and 93 young healthy controls. DNA samples were isolated from blood cells, amplified by PCR and digested with Tru1l. We observed that the genotype distributions of APOA5 variants were within Hardy-Weinberg equilibrium in all subject samples. Furthermore, chi-square test comparison for genotype distributions and allele frequencies did not reveal any significant difference among the three groups of subjects P>0.05). These results support the idea that these variants are not involved as a risk factor for developing AD.

Apolipoprotein E4 allele and ribosomal genes in Alzheimer's disease.

Ribosomal genes are involved in cellular transcription, translation and gene expression modulation process. An association between 28S/18S rRNA ratio levels with apoptosis and aging has been reported. Moulder et al. [22] and Hashimoto et al. [8] showed an association between apolipoprotein E4 allele and neuronal cell apoptosis through diverse mechanisms. The apoE 4 allele is considered a late-onset Alzheimer's disease (AD) risk factor associated with AD pathogenesis. We evaluated the association between apoE4 allele genotyping by PCR and rRNA 28S/18S ratio by slot blotting technique using peripheral blood samples of 18 Alzheimer's disease patients, 18 elderly controls and 18 young controls. A rRNA ratio decrease was observed in AD individuals confirming our previous results but this association is independently of the ApoE4 allele genotype. Thus our results pointed that two different mechanisms are involved in the etiology of Alzheimer disease each one leading independently to cell death. Further studies could investigate these factors.

Werner helicase polymorphism is not associated with Alzheimer's disease.

Alzheimer disease (AD) is the most common neurodegenerative disorder in the elderly and is also considered a progeroid genetic syndrome. The etiology of AD is complex and the mechanisms underlying its pathophysiology remains to be clarified. Werner syndrome (WS) is a rare autosomal recessive disorder characterized as a segmental progeroid syndrome. The gene (WRN) was recently identified. Its product acts as a DNA helicase and exonuclease. This study investigates the association of AD with the WRN 1367 polymorphisms in samples of 67 DA patients, 56 elderly healthy and 66 young healthy controls. DNA was isolated from blood cells, amplified by PCR and digested with PmaCI. We observed that the genotype distributions of WRN 1367 variants were within Hardy-Weinberg equilibrium in all subject samples. Furthermore, chi-square test comparison for genotype distributions and allele frequencies did not reveal any significant difference among the three groups of subjects (P>0.05). These results support the idea that these variants are not involved as a risk factor for developing AD.