Association of interleukin-1 gene polymorphisms with dementia in a community-based sample: The Honolulu-Asia Aging Study

A systematic review/meta-analysis of prevalence and incidence rates illustrates systemic underrepresentation of individuals racialized as Asian and/or Asian-American in ADRD research

We investigate Alzheimer's disease and related dementia (ADRD) prevalence, incidence rate, and risk factors in individuals racialized as Asian and/or Asian-American and assess sample representation. Prevalence, incidence rate, risk factors, and heterogeneity of samples were assessed. Random-effects meta-analysis was conducted, generating pooled estimates. Of 920 records across 14 databases, 45 studies were included. Individuals racialized as Asian and/or Asian-American were mainly from Eastern and Southern Asia, had higher education, and constituted a smaller sample relative to non-Hispanic white cohorts. The average prevalence was 10.9%, ranging from 0.4% to 46%. The average incidence rate was 20.03 (12.01-33.8) per 1000 person-years with a range of 75.19-13.59 (12.89-14.33). Risk factors included physiological, genetic, psychological, behavioral, and social factors. This review underscores the systemic underrepresentation of individuals racialized as Asian and/or Asian-American in ADRD research and the need for inclusive approaches accounting for culture, language, and immigration status. HIGHLIGHTS: There is considerable heterogeneity in the prevalence of ADRD among studies of Asian-Americans. There is limited data on group-specific risk factors for ADRD among Asian-Americans. The average prevalence of (ADRD) among Asian-Americans was found to be 7.4%, with a wide range from 0.5% to 46%.

Early treatment with an M1 and sigma-1 receptor agonist prevents cognitive decline in a transgenic rat model displaying Alzheimer-like amyloid pathology

The application of the selective allosteric M1 muscarinic and sigma-1 receptor agonist, AF710B (aka ANAVEX3-71), has shown to attenuate Alzheimer's disease-like hallmarks in McGill-R-Thy1-APP transgenic rats when administered at advanced pathological stages. It remains unknown whether preventive treatment strategies applying this compound may be equally effective. We tested whether daily oral administration of AF710B (10 µg/kg) in 7-month-old, preplaque, McGill-R-Thy1-APP rats for 7 months, followed by a 4-week washout period, could prevent Alzheimer's disease-like pathological hallmarks. Long-term AF710B treatment prevented the cognitive impairment of McGill-R-Thy1-APP rats. The effect was accompanied by a reduction in the number of amyloid plaques in the hippocampus and the levels of Aβ42 and Aβ40 peptides in the cerebral cortex. AF710B treatment also reduced microglia and astrocyte recruitment toward CA1 hippocampal Aβ-burdened neurons compared to vehicle-treated McGill-R-Thy1-APP rats, also altering the inflammatory cytokines profile. Lastly, AF710B treatment rescued the conversion of brain-derived neurotrophic factor precursor to its mature and biologically active form. Overall, these results suggest preventive and disease-modifying properties of the compound.

Traditional Chinese medicine promotes the control and treatment of dementia

Dementia is a syndrome that impairs learning and memory. To date, there is no effective therapy for dementia. Current prescription drugs, such as cholinesterase inhibitors, fail to improve the condition of dementia and are often accompanied by severe adverse effects. In recent years, the number of studies into the use of traditional Chinese medicine (TCM) for dementia treatment has increased, revealing a formula that could significantly improve memory and cognitive dysfunctions in animal models. TCM showed fewer adverse effects, lower costs, and improved suitability for long-term use compared with currently prescribed drugs. Due to the complexity of ingredients and variations in bioactivity of herbal medicines, the multi-target nature of the traditional Chinese formula affected the outcome of dementia therapy. Innovations in TCM will create a platform for the development of new drugs for the prevention and treatment of dementia, further strengthening and enhancing the current influence of TCM.

Preparation and Evaluation of IL-1ra-Loaded Dextran/PLGA Microspheres for Inhibiting Periodontal Inflammation In Vitro

Periodontitis is a chronic infectious disease, the course and progression of which are determined by the interaction between microorganisms and the host. Interleukin 1β plays an important role in the destruction of periodontal tissues. Interleukin 1 receptor antagonist (IL-1ra) can inhibit the biological activity of IL-1β without triggering any intracellular signaling. This study aimed to prepare IL-1ra-loaded dextran/PLGA microspheres and evaluate the physical and chemical characteristics and anti-inflammatory properties. Results suggested that the microspheres can be easily prepared into a drug carrier with good biocompatibility and can effectively inhibit the gene expression of pro-inflammatory factors induced by IL-1β in human gingival fibroblasts. Hence, the microspheres are excellent candidate for periodontitis treatment.

Genetic architecture of common non-Alzheimer's disease dementias

Frontotemporal dementia (FTD), dementia with Lewy bodies (DLB) and vascular dementia (VaD) are the most common forms of dementia after Alzheimer’s disease (AD). The heterogeneity of these disorders and/or the clinical overlap with other diseases hinder the study of their genetic components. Even though Mendelian dementias are rare, the study of these forms of disease can have a significant impact in the lives of patients and families and have successfully brought to the fore many of the genes currently known to be involved in FTD and VaD, starting to give us a glimpse of the molecular mechanisms underlying these phenotypes. More recently, genome-wide association studies have also pointed to disease risk-associated loci. This has been particularly important for DLB where familial forms of disease are very rarely described. In this review we systematically describe the Mendelian and risk genes involved in these non-AD dementias in an effort to contribute to a better understanding of their genetic architecture, find differences and commonalities between different dementia phenotypes, and uncover areas that would benefit from more intense research endeavors.

Apelin-13 Suppresses Neuroinflammation Against Cognitive Deficit in a Streptozotocin-Induced Rat Model of Alzheimer's Disease Through Activation of BDNF-TrkB Signaling Pathway

Alzheimer’s disease (AD), a progressive neurodegenerative disease characterized by impairments of cognitive function as a result of synaptic deficits and neuronal loss, is associated with inflammation. Apelin-13, a predominant neuropeptide with inhibiting effect on inflammation, has beneficial effects on cognition memory and neuronal damage. However, whether apelin-13 can protect neurons to ameliorate cognitive deficits in AD by inhibiting the inflammatory response remains largely unknown. To test this hypothesis, rats were intracerebroventricularly (ICV) injected with streptozotocin (3 mg/kg) alone or in combination with apelin-13 (2 μg). And tyrosine receptor kinase B (TrkB) blocker K252a (200 nM) was administrated 10 min before apelin injection. Furthermore, cognitive performance was assessed by new object recognition (NOR) and Y-maze tests. Protein expression of apelin, APJ, microglial marker (IBA1), astroglia marker (GFAP), interleukin 1 beta (IL-1β), tumor necrosis factor-α (TNF-α), synaptophysin (SYP), brain-derived neurotrophic factor (BDNF), TrkB, phospho-TrkB (p-TrkB) in the hippocampus were examined by western blotting or immunohistochemistry. And the gene expression of IBA1, GFAP, IL-1β, TNF-α, and SYP were detected by real-time quantitative polymerase chain reaction (PCR). Inflammatory disorder in the hippocampus was tested by hematoxylin and eosin (H&E) staining. The enzyme-linked immunosorbent assay (ELISA) was used to study the expression level of acetylcholine. And the activity of acetylcholinesterase was detected by Acetylcholinesterase Assay Kit. We observed that apelin/APJ signaling was downregulated in the hippocampus of rats administrated with STZ. Apelin-13 was found to significantly ameliorate STZ-induced AD-like phenotypes including congnitive deficit, cholinergic disfunction and the damage of neuron and synaptic plasticity. Moreover, apelin-13 inhibited microglia and astrocyte activation, reduced IL-1β and TNF-α expression and hippocampal BDNF/TrkB expression deficit in AD rats. Finally, apelin-13-mediated effects were blocked by TrkB receptor antagonist K252a. These results suggest that apelin-13 upregulates BDNF/TrkB pathway against cognitive deficit in a STZ-induced rat model of sporadic AD by attenuating inflammation.

Icariin and Its Metabolites as Potential Protective Phytochemicals Against Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder affecting more than 35 million people worldwide. As the prevalence of AD is dramatically rising, there is an earnest need for the identification of effective therapies. Available drug treatments only target the symptoms and do not halt the progression of this disorder; thus, the use of natural compounds has been proposed as an alternative intervention strategy. Icariin, a prenylated flavonoid, has several therapeutic effects, including osteoporosis prevention, sexual dysfunction amelioration, immune system modulation, and improvement of cardiovascular function. Substantial studies indicate that icariin may be beneficial to AD by reducing the production of extracellular amyloid plaques and intracellular neurofibrillary tangles and inhibiting phosphodiesterase-5 activity. Moreover, increasing evidence has indicated that icariin exerts a protective role in AD also by limiting inflammation, oxidative stress and reducing potential risk factors for AD such as atherosclerosis. This mini-review discusses the multiple potential mechanisms of action of icariin on the pathobiology of AD including explanation regarding its bioavailability, metabolism and pharmacokinetic.

Polymorphism IL-1RN rs419598 reduces the susceptibility to generalized periodontitis in a population of European descent

Interleukin (IL) 1-ra is a potent endogenous competitive inhibitor of IL-α and β and has an anti-inflammatory role. Study objectives were: 1) to assess the associations of IL-1RN genetic single nucleotide polymorphism (SNP) (rs419598) with generalized chronic periodontitis (GCP), generalized aggressive periodontitis (GAgP), and absence of periodontitis and 2) to assess its association with the load of five periodontopathogenic bacteria and periodontal clinical variables. A cross-sectional analytic study was conducted in 123 patients with GCP, 60 patients with GAgP, and 20 controls. Reverse hybridization PCR was used for genotyping analysis to detect SNPs in IL-1A (rs1800587), IL-1B (rs1143634), and IL-1RN (rs419598) genes and for determination of the load of five periodontopathogenic bacteria. The severity and extension of periodontitis were assessed. Multinomial logistic regression and mediated regression analyses were performed. Considering results for GCP and GAgP patients together, the presence of polymorphism in IL-1A and/or IL-1B gene was associated with a higher likelihood of periodontitis, (OR = 8.11; 95%CI [1.85–35.48]), but this likelihood was reduced when IL-1RN polymorphism was also present, (OR = 5.91; 95%CI [1.08–32.27]). IL-1RN polymorphism was significantly associated with lower counts of red complex bacteria, specifically Porphyromona gingivalis, Tannerella forsythia, and Prevotella intermedia, which were associated with improved clinical outcomes. The polymorphic expression of IL-1RN (rs419598) gene may be associated with a reduced susceptibility to GAgP and GCP in populations of European descent. This effect may be mediated by a decreased load of Porphyromona gingivalis, Tannerella forsythia, and Prevotella intermedia.

Inflammatory Cytokines and Alzheimer's Disease: A Review from the Perspective of Genetic Polymorphisms

Neuroinflammatory processes are a central feature of Alzheimer's disease (AD) in which microglia are over-activated, resulting in the increased production of pro-inflammatory cytokines. Moreover, deficiencies in the anti-inflammatory system may also contribute to neuroinflammation. Recently, advanced methods for the analysis of genetic polymorphisms have further supported the relationship between neuroinflammatory factors and AD risk because a series of polymorphisms in inflammation-related genes have been shown to be associated with AD. In this review, we summarize the polymorphisms of both pro- and anti-inflammatory cytokines related to AD, primarily interleukin-1 (IL-1), IL-6, tumor necrosis factor alpha, IL-4, IL-10, and transforming growth factor beta, as well as their functional activity in AD pathology. Exploration of the relationship between inflammatory cytokine polymorphisms and AD risk may facilitate our understanding of AD pathogenesis and contribute to improved treatment strategies.

Genetic susceptibility to vascular cognitive impairment: a pathophysiological view

The heterogeneity of the vascular cognitive impairment (VCI) creates challenges for research on its genetic basis and pathophysiology. Despite well-known monogenic forms may be useful to understand some pathogenic mechanisms leading to VCI, most of VCIs are sporadic disorders resulting from the interaction between environmental, vascular and genetic factors. Genetic investigation for VCI may encompass both candidate genes that affect critical biological processes to VCI and common and rare genetic variants identified across the entire genome study technology, thereby enabling us to confirm or expose new biological mechanisms in VCI and develop new therapeutic and preventive approaches. Notwithstanding genetic susceptibility to VCI remains largely unknown owing to methodological issues. Collaborative efforts emerge as an interesting strategy to overcome these problems.

Interleukin-1β Promoter Polymorphism Enhances the Risk of Sleep Disturbance in Alzheimer's Disease

Sleep alleviates Alzheimer’s disease (AD)-related neuropathological processes, whereas sleep disturbance in AD patients is associated with elevated peripheral inflammatory cytokine levels. In the present study, we assessed interleukin (IL)-1β and APOEε4 polymorphisms for association with susceptibility of sleep disturbances in AD patients. A total of 123 pretreated AD patients and 120 age-, gender- and education level-matched healthy controls were recruited for two consecutive full-night polysomnography and measurement of Epworth Sleepiness Scale (ESS) scores for sleep-wake disturbance. Their genomic DNA was analyzed for IL-1β and APOEε4 SNPs using ligase detection reaction (LDR) technology. Blood levels of IL-1β, IL-6, and tumor necrosis factor alpha (TNF-α) were measured using ELISA after lipopolysaccharide (LPS) stimulation. The odds ratio and 95% confidence interval for genotype-specific risk were calculated using an unconditional logistic regression model and adjusted by age, gender, educational levels, body mass index (BMI), and activities of daily living (ADL). Compared to the non-APOEε4/ε4 genotype, APOEε4/ε4 significantly increased the risk of AD (APOEε4/ε4 vs. non-APOEε4/ε4, adjusted OR = 4.33, 95% CI = 1.33–14.10, p = 0.015). Compared to the IL-1β CC genotype (-31), the TT genotype significantly increased the risk of AD (TT vs. CC, adjusted OR = 1.72, 95% CI = 1.13–2.61, p = 0.010). AD patients carrying the APOEε4 allele and the IL-1β TT genotype showed less time in bed, longer sleep latency and REM latency, more awakenings, and a lower SWS percentage than those carrying CC/CT combined genotypes. In addition, blood IL-1β levels were significantly greater in AD patients carrying both the APOEε4 allele and the IL-1β-31TT genotype than in those carrying the APOEε4 allele and the -31 TC or CC genotype. In conclusion, this study provides the first evidence indicating that the IL-1β-31TT genotype and homozygous APOEε4 combined are associated with increased risk of developing AD with sleep disturbance.

Evaluation of inflammation-related genes polymorphisms in Mexican with Alzheimer's disease: a pilot study

Amyloid peptide is able to promote the activation of microglia and astrocytes in Alzheimer’s disease (AD), and this stimulates the production of pro-inflammatory cytokines. Inflammation contributes to the process of neurodegeneration and therefore is a key factor in the development of AD. Some of the most important proteins involved in AD inflammation are: clusterin (CLU), complement receptor 1 (CR1), C reactive protein (CRP), tumor necrosis factor α (TNF-α), the interleukins 1α (IL-1α), 6 (IL-6), 10 (IL-10) and cyclooxygenase 2 (COX-2). In particular, COX-2 is encoded by the prostaglandin-endoperoxide synthase 2 gene (PTGS2). Since variations in the genes that encode these proteins may modify gene expression or function, it is important to investigate whether these variations may change the developing AD. The aim of this study was to determine whether the presence of polymorphisms in the genes encoding the aforementioned proteins is associated in Mexican patients with AD. Fourteen polymorphisms were genotyped in 96 subjects with AD and 100 controls; the differences in allele, genotype and haplotype frequencies were analyzed. Additionally, an ancestry analysis was conducted to exclude differences in genetic ancestry among groups as a confounding factor in the study. Significant differences in frequencies between AD and controls were found for the single-nucleotide polymorphism (SNP) rs20417 within the PTGS2 gene. Ancestry analysis revealed no significant differences in the ancestry of the compared groups, and the association was significant even after adjustment for ancestry and correction for multiple testing, which strengthens the validity of the results. We conclude that this polymorphism plays an important role in the development of the AD pathology and further studies are required, including their proteins.

Impaired regulation of immune responses in cognitive decline and Alzheimer’s disease: lessons from genetic association studies

Altered levels of cytokines and acute-phase proteins have been described in the blood and brain of patients with Alzheimer's disease. Microglia are resident cells of the brain and metabolic upregulation of these cells may play a crucial role in the development of the neurodegeneration associated with Alzheimer's disease. Studies focusing on gene polymorphisms of molecules with immune regulatory function have demonstrated an association with increased risk of the disease and confirmed the pivotal role of immune responses in Alzheimer's disease pathogenesis. Several gene variants may also influence the rate of the cognitive decline associated with the disease. A definite immune-related gene polymorphism profile may be a feature of a limited group of patients with early onset of the disease and fast clinical deterioration. Only this group of patients may benefit from anti-inflammatory treatment.

Functions of intronic nucleotide variants in the gene encoding pleckstrin homology like domain beta 2 (PHLDB2) on susceptibility to vascular dementia

OBJECTIVES

A genome-wide association study (GWAS) failed to detect any genetic associations with susceptibility to vascular dementia (VaD) by the Bonferroni multiple test. This study aimed to discover false negative associations from the GWAS.

METHODS

We selected a candidate gene in which multiple associations were identified with its single nucleotide polymorphisms (SNPs). Genetic associations were intensively examined with its SNPs using 207 VaD patients and 207 age- and sex-matched control subjects. Functions of candidate SNPs on splicing of the gene were predicted by an in silico analysis and evaluated by a minigene assay.

RESULTS

Genetic analysis with 80 SNPs of pleckstrin homology like domain beta 2 (PHLDB2) revealed 6 SNPs associated with VaD (P < 6.25 × 10(-4)). Among them, four SNPs in introns 2 and 3 were in complete linkage and associated also with VaD-related phenotypes (P < 0.05). Especially, rs951660 was predicted to produce splicing enhancers or serine/arginine-rich protein binding sites, and its minor allele (A) delayed expression of mRNA in vivo.

CONCLUSIONS

The current study suggested a novel association of susceptibility to VaD with the gene encoding PHLDB2. The minor allele, A, of its intronic SNP 'rs951660' might induce a delayed splicing and thus increase the susceptibility to VaD.

Complex genetic susceptibility to vascular dementia and an evidence for its underlying genetic factors associated with memory and associative learning

Genetic basis for vascular dementia (VD) as a typical complex disease has been limitedly reported from association studies conducted with candidate genes. Even recent genomewide association studies (GWAS) could hardly identify additional genetic factors for VD. Although a considerable complexity for its genetic architecture was suspected, there were some challenges to identify false negative associations that resulted from the GWAS. Challenges to identifying genetic factors and their functions after the trials of GWAS revealed that splicing of primary transcript was inhibited (SYK) or delayed (PHLDB2) by a nucleotide substitution of the corresponding gene. The studies gave us the lesson that integrated investigations with statistical genomics as well as functional genomics are needed to identify false negatives from the GWAS. Such endeavors would provide key insights into aspects of underlying nucleotide architectures of VD and incorporate the genetic factors into clinical practice. The recent genetic association studies for susceptibility to VD were briefly overviewed in this article. We also showed a challenge to understanding genetic dissection of VD by a genomic region enrichment analysis with distal cis-regulatory sequences. The analysis with a variant set of potential false negatives from the GWAS revealed that the variants were significantly enriched near genes involved in critical biological processes to VD.

Glutathione transferases, regulators of cellular metabolism and physiology

BACKGROUND

The cytosolic glutathione transferases (GSTs) comprise a super family of proteins that can be categorized into multiple classes with a mixture of highly specific and overlapping functions.

SCOPE OF REVIEW

The review covers the genetics, structure and function of the human cytosolic GSTs with particular attention to their emerging roles in cellular metabolism.

MAJOR CONCLUSIONS

All the catalytically active GSTs contribute to the glutathione conjugation or glutathione dependant-biotransformation of xenobiotics and many catalyze glutathione peroxidase or thiol transferase reactions. GSTs also catalyze glutathione dependent isomerization reactions required for the synthesis of several prostaglandins and steroid hormones and the catabolism of tyrosine. An increasing body of work has implicated several GSTs in the regulation of cell signaling pathways mediated by stress-activated kinases like Jun N-terminal kinase. In addition, some members of the cytosolic GST family have been shown to form ion channels in intracellular membranes and to modulate ryanodine receptor Ca(2+) channels in skeletal and cardiac muscle.

GENERAL SIGNIFICANCE

In addition to their well established roles in the conjugation and biotransformation of xenobiotics, GSTs have emerged as significant regulators of pathways determining cell proliferation and survival and as regulators of ryanodine receptors that are essential for muscle function. This article is part of a Special Issue entitled Cellular functions of glutathione.

Genetic polymorphism of interleukin 1β -511C/T and susceptibility to sporadic Alzheimer's disease: a meta-analysis

A large number of epidemiological studies have been performed to investigate the association between Alzheimer's disease (AD) risk and interleukin-1β -511C/T genetic polymorphism, however, inconsistent results have been reported. The effect of the IL-1β -511C/T polymorphism on AD susceptibility was evaluated by a meta-analysis. Series of databases were researched. 14 studies involving 2640 AD case and 3493 control subjects were identified. The pooled results showed there were no statistical associations of interleukin-1β -511C/T genetic polymorphism with susceptibility to AD for five analysis models in all subjects. However, obvious heterogeneity among studies was detected. When stratifying for age at onset, ethnicity and geographic distribution of population to explore the original source of heterogeneity, the meta-analysis results based on geographic distribution of population showed the significant difference (CC vs CT, OR 1.26, 95 % CI: 1.03, 1.54, z = 2.25, P = 0.025; CC vs CT+TT, OR 1.24, 95 % CI: 1.03, 1.50, z = 2.24, P = 0.025) only in non-Europe. These findings indicate that the IL-1β -511C/T polymorphism might be associated with AD risk, and individuals with IL-1β -511C/C genotype might be at higher risk of AD in non-Europe. Further larger sample research would be warranted to confirm these conclusions.

Association of interleukin 1β polymorphisms and haplotypes with Alzheimer's disease

Our study aimed to associate IL-1β and IL-1RN polymorphisms with AD disease in comparison with elderly control group from São Paulo - Brazil. We genotyped 199 Alzheimer's disease (AD) patients, 165 elderly control and 122 young control samples, concerning VNTR (IL-1RN) and -511C>T and -31T>C (IL-1β) polymorphisms. Our findings revealed that -511C/-31T/2-repetitions VNTR haplotype had a protective effect for AD when compared to EC (p=0.005), whereas -511C/-31C/1-repetition VNTR haplotype was associated as a risk factor for AD (p=0.021). Taken together, we may suggest that there is a relevant role of IL-1 genes cluster in AD pathogenesis in this Brazilian population.

Panel of Genetic Variations as a Potential Non-invasive Biomarker for Early Diagnosis of Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent form of dementia. Biomarkers such as levels of amyloid beta (Aβ) in cerebrospinal fluid and ApoE genotyping were suggested for the diagnosis of AD, however, the result is either non-conclusive or with invasive procedure. Genome-wide association studies (GWASs) for AD suggested single nucleotide polymorphisms (SNPs) in many genes are associated with the risk of AD, but each only contributed with small effect to the disease. By incorporating a panel of established genetic susceptibility factors, the risk of an individual in getting AD could be better estimated. Further research will be required to reveal if adding to the current well-developed clinical diagnosis protocol, the accuracy and specificity of diagnosis of AD would be greatly improved and if this might also be beneficial in identifying pre-symptomatic AD patients for early diagnosis and intervention of the disease.

The role of inflammation in the pathogenesis of delirium and dementia in older adults: a review

AIMS

To review recent evidence that suggests inflammation plays a similar role in the pathogenesis of delirium and dementia.

METHODS

We performed a literature search of original research and review articles in PubMed using the keywords: delirium, dementia, and inflammation. We summarized the evidence linking inflammation to the pathogenesis of delirium and dementia.

DISCUSSION

Delirium and dementia share similarities in clinical and pathogenic features, leading to the speculation that instead of being distinct clinical entities, the two age-related conditions may be linked by a common pathogenic mechanism. Inflammatory markers have been shown to be elevated in both delirium and dementia, thereby implicating inflammation as a possible mediating factor in their genesis. There is evidence in both basic science and clinical research literature that elevated cytokines play a crucial role in the development of cognitive dysfunction observed in both dementia and delirium.

CONCLUSION

Mounting evidence supports the role of inflammation in the development of both dementia and delirium. Further studies are needed to elucidate the mechanisms underlying these relationships.

Association of adiposity status and changes in early to mid-adulthood with incidence of Alzheimer's disease

Adiposity status and change are potential risk factors for Alzheimer's disease (AD). The authors used data on 2,322 participants in the Baltimore Longitudinal Study of Aging to analyze the relation between AD incidence and adiposity in Cox proportional hazards models, with adjustment for sociodemographic factors and smoking status. Body mass index (BMI; weight (kg)/height (m)(2)) and waist circumference at specific ages were predicted by empirical Bayes estimators from mixed-effects regression models. After a median of 23.4 years of follow-up between 1958 and 2006, 187 participants developed AD. Among men, being underweight (BMI <or=18.5) at age 30, 40, or 45 years increased the likelihood of AD (hazard ratio (HR) = 5.76, 95% confidence interval (CI): 2.07, 16.00); among women, being obese (BMI >or=30) at age 30, 40, or 45 years and jointly centrally obese (waist circumference >or=80th percentile) at age 30, 35, or 50 years increased AD risk (HR = 6.57, 95% CI: 1.96, 22.02). Women who lost weight (BMI change <10th percentile) between ages 30 and 45 years were also at increased risk (HR = 2.02, 95% CI: 1.06, 3.85). Weight gain among men (BMI change >90th percentile) between ages 30 and 50 years increased AD risk (HR = 3.70, 95% CI: 1.43, 9.56). Future studies should identify age- and gender-specific optimal weights and weight-loss strategies for preventing AD and investigate potential mechanisms.

Association between the interleukin-1beta polymorphisms and Alzheimer's disease: a systematic review and meta-analysis

The pro-inflammatory cytokine interleukin(IL)-1beta is a main component in inflammatory pathways and is overexpressed in the brain of Alzheimer's disease (AD) patients. Several studies report associations between IL-1beta polymorphisms and AD, but findings from different studies are controversial. Our aim was to verify the correlation between the single nucleotide polymorphisms (SNPs) of the IL-1beta, at sites -511 and +3953, and AD by meta-analysis. Computerized bibliographic searches of PUBMED and AlzGene database (http://www.alzgene.org) were supplemented with manual searches of reference lists. There is evidence for association between IL-1beta +3953 SNP and AD, with an OR=1.60 (95% C.I.: 1.16-2.22; Z=2.83 p=0.005) for TT genotype. No significant difference in genotype distribution of the IL-1beta -511 SNP in AD was obtained, but high between-study heterogeneity was found. To reduce heterogeneity, subgroup analyses were performed using, as stratifying variables, characteristics of the population under study (age, gender, type of AD diagnosis, Mini Mental State Examination of the controls) and characteristics related to the study design (statistical power of individual studies). The frequency of the IL-1beta -511 TT genotype resulted significantly higher than other genotypes only when the Caucasian studies with the highest statistical power were included in the subgroup analysis (OR=1.32; 95% C.I.: 1.03-1.69; p=0.03), with no evidence of between-study heterogeneity. Our data support an association between the TT genotype of IL-1beta +3953 SNP and AD, and suggest a possible association of the -511 TT genotype. Unreplicability of the results seems to be due mainly to the lack of statistical power of the individual studies.

Association of interleukin-1 receptor antagonist +2018 gene polymorphism with Japanese chronic periodontitis patients using a novel genotyping method

Genetic variants at multiple loci have been shown to be associated with periodontitis risk. In this study, we have focused on nine functional gene polymorphisms encoding immunoregulation-related molecules such as cytokines (interleukin-1 (IL-1), transforming growth factor-beta1 (TGF-beta1)) and cell surface receptors (immunoglobulin G and A Fc receptors (Fc gamma R and Fc alpha R)). In total, 113 Japanese patients with chronic periodontitis (CP) and 108 race-matched healthy controls were genotyped with the modified serial invasive signal amplification reaction. There was a significant difference in the distribution of IL-1 receptor antagonist (RN) +2018 T/C allele between the patient and control groups, with enrichment of the +2018 C in controls (P = 0.021, odds ratio = 0.38). An increased frequency of the IL-1 haplotype comprising IL-1A +4845 G, IL-1B -31 C, and IL-1RN +2018 C was observed in controls (P = 0.004). Moreover, a multivariate logistic regression analysis revealed that subjects with IL-1RN +2018 C allele were less likely to have CP (P = 0.016, odds ratio = 0.29). These findings document the association of IL-1RN +2018 C with reduced susceptibility to CP in the Japanese.

Tooth loss, dementia and neuropathology in the Nun study

BACKGROUND

Numerous studies have linked dementia to the subsequent deterioration of oral health. Few investigators, however, have examined oral disease as a potential risk factor in the development of dementia. The authors conducted a study to investigate a potential association between a history of oral disease and the development of dementia.

METHODS

Longitudinal dental records supplemented data collected from 10 annual cognitive assessments of 144 Milwaukee participants in the Nun Study, a longitudinal study of aging and Alzheimer disease, who were 75 to 98 years old. Neuropathologic findings at autopsy were available for 118 participants who died.

RESULTS

A low number of teeth increased the risk of higher prevalence and incidence of dementia.

CONCLUSION

Participants with the fewest teeth had the highest risk of prevalence and incidence of dementia.

CLINICAL IMPLICATIONS

Edentulism or very few (one to nine) teeth may be predictors of dementia late in life.

Interleukin-1alpha and -1beta promoter polymorphisms in Taiwanese patients with dementia

BACKGROUND

Inflammatory events may contribute to the pathogenesis of dementia and interleukin-1 (IL-1) may exert both neurotoxic and neuroprotective effects. We investigated whether IL-1alpha -889 C/T and IL-1beta -511 C/T promoter polymorphisms are associated with the risk of Alzheimer's disease (AD) and vascular dementia (VaD).

METHODS

AD patients (n = 219) and VaD patients (n = 82), who fulfilled the criteria of the NINCDS-ADRDA and NINDS-AIREN, and ethnic-matched and nondemented controls (n = 209) were analyzed by means of genotype association method.

RESULTS

No significant difference in the genotype distribution of the analyzed single nucleotide polymorphisms was found between AD or VaD cases and controls. However, the frequency of the IL-1alpha -889 CT genotype was notably lower in VaD patients aged over 70 years than the age-matched controls (9.1 vs. 22.9%, p = 0.036) andtheIL-1alpha -889 CT genotype demonstrated a trend toward decrease in risk of developing VaD (odds ratio: 0.34; 95% confidence interval: 0.12-0.83, p = 0.026). Multivariate analysis revealed that the IL-1beta -511T-carrying genotype slightly strengthens the negative association of the IL-1alpha -889 CT genotype with VaD (odds ratio: 0.26; 95% confidence interval: 0.08-0.79, p = 0.024).

CONCLUSION

Our data suggest a protective role of the IL-1alpha -889 CT genotype in VaD susceptibility among Taiwanese aged over 70 years.

Genetic priming of a proinflammatory profile predicts low IQ in octogenarians

The purpose of the study was to test the hypothesis that single nucleotide polymorphisms (SNPs) within interleukin (IL)-18, TNF-alpha, IL-6 and IL-10 gene promoter regions are risk factors for cognitive decline in healthy octogenarians, and to isolate the strongest inflammatory biomarkers of cognitive function in the peripheral blood. The Wechsler Adult Intelligence Scale was administered to 112 individuals at ages 80 and 85. An IL-18 haplotype was an independent risk factor of poor Performance IQ. The TNF-308GA genotype was related to individual declines in Verbal IQ, and the IL-10-592 CC genotype was related to better Verbal IQ at the age of 80. Circulating levels of TNF-alpha, sTNFRs, and IL-6 were negatively correlated with IQ at age 85 and less strongly to IQ at age 80 with activation of the TNF system as the strongest biomarker. In conclusion, SNPs related to high proinflammatory or low anti-inflammatory activity are independent risk factors of reduced cognitive function in octogenarians. Only the IL-18 haplotype was associated with inflammation in the peripheral blood and only with regard to circulating TNF-alpha.

Interleukin-1 genotype-selective inhibition of inflammatory mediators by a botanical: a nutrigenetics proof of concept

OBJECTIVE

Although observational studies have shown that genotype may influence nutritional effects on target outcomes, there are few reported studies that stratified subjects by genotype before a nutritional intervention. This proof-of-concept trial determined whether specifically formulated botanical mixtures reduced inflammation in individuals with genetic variations that predispose to overexpression of interleukin-1beta (IL-1beta) and early heart disease.

METHODS

Healthy adults with elevated C-reactive protein (CRP) were stratified into genetic groups based on being positive (IL1(Pos)) or negative (IL1(Neg)) for the at-risk IL-1 gene variations. IL1(Pos) (n = 39) and IL1(Neg) (n = 40) subjects were then randomized to the candidate botanical formulation or placebo. The botanical formulation included rose hips, a blueberry and blackberry mixture, and a grapevine extract.

RESULTS

At 12 wk of dosing with the botanical formulation, IL-1beta gene expression by stimulated peripheral blood mononuclear cells was significantly lower than at baseline and significantly lower than placebo in IL1(Pos) and IL1(Neg) subjects. Mean IL-1beta gene expression treatment effect over the 12-wk period was greater in IL1(Pos) than in IL1(Neg) subjects. At 12 wk of dosing the botanical mixture produced no mean change in serum CRP levels. However, in IL1(Pos) subjects, significantly more subjects achieved a reduction in CRP with the botanical mixture than with placebo. No CRP effect was observed in the IL1(Neg) subjects.

CONCLUSION

This study represents one of a few prospective clinical trials in which genetic variations were shown to differentially influence nutrient effects on outcomes.

Interleukin 18 gene polymorphisms predict risk and outcome of Alzheimer's disease

BACKGROUND AND AIM

Inflammation has been extensively implicated in the pathogenesis of Alzheimer's disease (AD). Although there is evidence of a key role for cytokines in neuroinflammation processes, so far the proinflammatory cytokine interleukin (IL)-18 has not been associated with AD. The aim of this study was to investigate the impact of two polymorphisms of the human IL-18 gene promoter at positions -607 (C/A) and -137 (G/C) on both susceptibility to and progression of AD.

RESULTS

The results revealed that the genotype distribution of the -607 (C/A) polymorphism was different between patients with AD and control subjects (chi2 = 7.99, df = 2, p = 0.0184). In particular, carriers of the CC genotype were at increased risk of developing AD (OR 2.33; 95% CI 1.29 to 4.22; p = 0.0052). The observed genotypes were in Hardy-Weinberg equilibrium, as for the -607 polymorphism, whereas the -137 polymorphism appeared in Hardy-Weinberg disequilibrium only in the patient group (p = 0.0061). Finally, in a 2 year follow-up study, the -137 CC genotype was strongly and specifically associated with a faster cognitive decline (F = 4.024; df = 4,192; p = 0.0037 for time by IL-18 -137 G/C group interaction) with no interaction effect with the apolipoprotein E epsilon4/non-epsilon4 allele presence.

CONCLUSION

As IL-18 cytokine promoter gene polymorphisms have been previously described to have functional consequences on IL-18 expression, it is possible that individuals with a prevalent IL-18 gene variant have a dysregulated immune response, suggesting that IL-18 mediated immune mechanisms may play a crucial role in AD.

Interleukin-1 alpha polymorphism has influence on late-onset sporadic Parkinson's disease in Taiwan

Inflammatory events may contribute to the pathogenesis of Parkinson's disease (PD) and interleukin 1 (IL-1) may exert both neurotoxic and neuroprotective effects. We conducted a case-control study in a cohort of 493 PD cases and 388 ethnically matched controls to investigate the association of IL-1alpha C-889T and IL-1beta C-511T polymorphisms with the risk of PD. No significant difference in the genotype distribution of the analyzed polymorphisms was found between PD and controls. However, after stratification by age, individuals over 70 years of age carrying IL-1alpha-889 C/T genotype demonstrated a significant decrease in risk of developing PD (OR = 0.44; 95% CI = 0.22-0.88, p = 0.021) and the decrease is strengthened by IL-1beta-511 T-carrying genotype (OR = 0.28; 95% CI = 0.11-0.71, p = 0.008). Our data suggest that IL-1alpha, acting synergistically with IL-1beta, plays role in PD susceptibility among Taiwanese people older than 70 years of age.

Genetic influences on outcome following traumatic brain injury

Several genes have been implicated as influencing the outcome following traumatic brain injury (TBI). Currently the most extensively studied gene has been APOE. APOE can influence overall and rehabilitation outcome, coma recovery, risk of posttraumatic seizures, as well as cognitive and behavioral functions following TBI. Pathologically, APOE is associated with increased amyloid deposition, amyloid angiopathy, larger intracranial hematomas and more severe contusional injury. The proposed mechanism by which APOE affects the clinicopathological consequences of TBI is multifactorial and includes amyloid deposition, disruption of cytoskeletal stability, cholinergic dysfunction, oxidative stress, neuroprotection and central nervous system plasticity in response to injury. Other putative genes have been less extensively studied and require replication of the clinical findings. The COMT and DRD2 genes may influence dopamine dependent cognitive processes such as executive/frontal lobe functions. Inflammation which is a prominent component in the pathophysiological cascade initiated by TBI, is in part is mediated by the interleukin genes, while apoptosis that occurs as a consequence of TBI may be modulated by polymorphisms of the p53 gene. The ACE gene may affect TBI outcome via mechanisms of cerebral blood flow and/or autoregulation and the CACNA1A gene may exert an influence via the calcium channel and its effect on delayed cerebral edema. Although several potential genes that may influence outcome following TBI have been identified, future investigations are needed to validate these genetic studies and identify new genes that might influence outcome following TBI.

Inflammation and dementia: epidemiologic evidence

Based on experimental and neuropathologic studies, inflammation is postulated to play a central role in processes leading to neurodegeneration as well as vascular injury. To better understand the role of inflammation in cognitive disorders (CD), identify potential biomarkers for CD, and select individuals who may have a genetic susceptibility to CD, several different measures of inflammation have been employed in epidemiologic studies of CD, which are reviewed here. An inverse association of non-steroidal anti-inflammatory medications has been consistently reported. More variable are reports on the associations of various serum markers of cytokines to CD. There are few epidemiologic studies that have examined the association of CD and single nucleotide polymorphisms (SNP) regulating cytokines, although these have been examined in clinical case-control series. Data are summarized on the association of interleukin-1 SNPs from the Honolulu Asia Aging Study. There are many outstanding questions about the role of inflammation in CD and how best to measure it in the context of population-based studies.

Polymorphisms in the interleukin 6 and transforming growth factor beta1 gene and risk of dementia. The Rotterdam Study

Inflammatory mechanisms are involved in the pathogenesis of dementia. Inflammatory cytokines, including interleukin-6 (IL-6) and transforming growth factor beta1 (TGFbeta1), have been found in association with Alzheimer pathology and there is evidence for direct involvement of these cytokines in formation of amyloid plaques. Polymorphisms in genes encoding for IL-6 and TGFbeta1 are associated with plasma levels of IL-6 and TGFbeta1. Studies examining the association between polymorphisms in these genes and dementia yielded conflicting results. The purpose of this study was to examine the association between genetic variance in IL-6 and TGFbeta1 and risk of dementia. We examined this association in the Rotterdam Study, a prospective population-based cohort study in the elderly. Polymorphisms in the IL-6 (-174G>C) and TGFbeta1 gene (-800G>A, -509C>T, +10T>C, +25G>C and 263C>T) were genotyped and haplotypes of the TGFbeta1 gene were constructed. In a random subset IL-6 plasma levels were measured. During follow-up (mean 9.2 years), 743 dementia cases were identified. We estimated the association between individual polymorphisms and haplotypes with dementia with Cox' proportional hazard models. No association was found between the -174G>C polymorphism in the IL-6 gene and risk of dementia. No association was found between polymorphisms and constructed haplotypes in the TGFbeta1 gene and risk of dementia or Alzheimer's disease. No association was found between IL-6 genotype and IL-6 plasma levels in the random subset. Associations did not differ across APOE genotypes. Our findings do not suggest involvement of genetic variance in IL-6 and TGFbeta1 in the development of dementia.