Influence of peroxisome proliferator-activated receptor γ gene polymorphism on 24S-hydroxycholesterol levels in Alzheimer’s patients

The nuclear cofactor receptor interacting protein-140 (RIP140) regulates the expression of genes involved in Aβ generation

The receptor interacting protein-140 (RIP140) is a cofactor for several nuclear receptors and has been involved in the regulation of metabolic and inflammatory genes. We hypothesize that RIP140 may also affect Aβ generation because it modulates the activity of transcription factors previously implicated in amyloid precursor protein (APP) processing, such as peroxisome proliferator-activated receptor-γ (PPARγ). We found that the levels of RIP140 are reduced in Alzheimer's disease (AD) postmortem brains compared with healthy controls. In addition, in situ hybridization experiments revealed that RIP140 expression is enriched in the same brain areas involved in AD pathology, such as cortex and hippocampus. Furthermore, we provide evidence using cell lines and genetically modified mice that RIP140 is able to modulate the transcription of certain genes involved in AD pathology, such as β-APP cleaving enzyme (BACE1) and GSK3. Consequently, we found that RIP140 overexpression reduced the generation of Aβ in a neuroblastoma cell line by decreasing the transcription of β-APP cleaving enzyme via a PPARγ-dependent mechanism. The results of this study therefore provide molecular insights into common signaling pathways linking metabolic disease with AD.

Lack of genetic associations between PPAR-γ gene rs1801282 polymorphism and Alzheimer's disease in general population: a meta-analysis

Published studies have evaluated the association between PPAR-γ rs1801282 polymorphism and Alzheimer's disease (AD) susceptibility. However, a definitive conclusion remains elusive. The aim of this study was to derive a more precise estimation of this association. We searched PubMed, Embase, Alzgene database, Chinese National Knowledge Infrastructure (CNKI), China Biological Medicine Database and Wanfang Databases for related studies. Twelve case-control studies with a total of 4874 cases and 5439 controls were finally identified to be eligible studies in this meta-analysis. The association was assessed by summarizing the odds ratios (ORs) with the corresponding 95% confidence intervals (CIs). Overall, there was no significant association between PPAR-γ rs1801282 polymorphism and Alzheimer's disease risk in all genetic models (the allele model G vs. C: OR=1.09, 95% CI 0.99-1.19, p=0.07; the homozygous model GG vs. CC: OR=1.04, 95% CI 0.75-1.44, p=0.80; heterozygote model GC vs. CC: OR=1.11, 95% CI 1,00-1.22, p=0.05; the dominant model GG+GC vs. CC: OR=1.10, 95% CI 1.00-1.22, p=0.05; the recessive model GG vs. GC+CC: OR=1.02, 95% CI 0.74-1.41, p=0.90). In subgroup analysis by ethnicity, no significant difference was found in both Asians and Caucasians. In summary, the present meta-analysis suggests that the PPAR-γ rs1801282 polymorphism may not be associated with genetic susceptibility of AD in general population.

Association between PRO12ALA polymorphism of the PPAR-γ2 gene and type 2 diabetes mellitus in Iranian patients

BACKGROUND:

Peroxisome proliferator-activated receptor (PPARs) have been identified as ligand-activated transcription factors that belong to the nuclear receptor superfamily. It has been shown that an association exists between Proline 12 alanine (Pro12Ala) polymorphism of PPAR-GAMMA2 (PPAR-γ2) gene and increased risk of type 2 diabetes mellitus (T2DM) in different populations. Therefore, the present study was designed to investigate the association between Pro12Ala polymorphism of PPAR-γ2 gene and T2DM in an Iranian population.

MATERIALS AND METHODS:

Two hundred unrelated people, including 100 healthy controls and 100 diabetic patients were recruited diagnosed based on American Diabetes Association criteria. Blood samples were used for isolation of genomic deoxyribonucleic acid (DNA). Having extracted the genomic DNA from human blood leukocytes by means of High Pure polymerase chain reaction (PCR) Template preparation kit, we carried out polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) on each blood sample. Then, Genomic DNA was digested by BstU-I restriction enzyme. Thereafter, restriction products were analyzed by means of Polyacrylamide gel electrophoresis and stained by Ethidium Bromide.

RESULTS:

We found that the frequency of Ala allele in healthy subjects was significantly higher than in diabetic subjects (P = 0003). Moreover, the genotype frequency of Ala/Ala in healthy subjects was significantly higher than in diabetic subjects (P < 0.001). However, the genotype frequency of Ala/Pro in diabetic subjects was significantly higher than in healthy subjects (P < 0.001).

CONCLUSION:

The present study suggests that polymorphism of PPAR-γ2 gene is associated with T2DM. Furthermore, Ala allele is significantly found in non-diabetic individual’s Iranian population.

Lack of Genetic Associations of PPAR-γ and PGC-1α with Alzheimer's Disease and Parkinson's Disease with Dementia

Background and Aims

Similar clinical and pathological features have been observed in Alzheimer's disease (AD) and Parkinson's disease with dementia (PDD). Both the peroxisome proliferator-activated receptor-γ (PPAR-γ) gene and the peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) gene are candidates modifying the risk for both diseases. The aim of this study was to clarify whether common single nucleotide polymorphisms (SNPs) of the PPAR-γ gene and the PGC-1α gene affect the onset of AD and PDD genetically.

Methods

Four exonic SNPs of both genes (rs1801282 and rs3856806 of the PPAR-γ gene, rs3736265 and rs8192678 of the PGC-1α gene) were genotyped in 171 AD patients, 136 age-matched controls and 53 PDD patients. Haplotype analysis and logistic regression analysis with apolipoprotein E (APO E) status were performed for AD.

Results

There was no statistical difference between AD cases and controls for the 4 SNPs, nor was there any statistical difference between PDD cases and controls for the 4 SNPs. We could not find any synergetic associations between these SNPs, APO E4 and AD.

Conclusions

The 4 SNPs studied here did not influence the risk for AD in a Japanese population. As the number of PDD cases was small, comprehensive genetic studies considering diabetes would be needed.

24S-hydroxycholesterol in plasma: a marker of cholesterol turnover in neurodegenerative diseases

Brain cholesterol is mainly involved in the cell membrane structure, in signal transduction, neurotransmitter release, synaptogenesis and membrane trafficking. Impairment of brain cholesterol metabolism was described in neurodegenerative diseases, such as Multiple Sclerosis, Alzheimer and Huntington Diseases. Since the blood-brain barrier efficiently prevents cholesterol uptake from the circulation into the brain, de novo synthesis is responsible for almost all cholesterol present there. Cholesterol is converted into 24S-hydroxycholesterol (24OHC) by cholesterol 24-hydroxylase (CYP46A1) expressed in neural cells. Plasma concentration of 24OHC depends upon the balance between cerebral production and hepatic elimination and is related to the number of metabolically active neurons in the brain. Factors affecting brain cholesterol turnover and liver elimination of oxysterols, together with the metabolism of plasma lipoproteins, genetic background, nutrition and lifestyle habits were found to significantly affect its plasma levels. Either increased or decreased plasma 24OHC concentrations were described in patients with neurodegenerative diseases. A group of evidence suggests that reduced levels of 24OHC are related to the loss of metabolically active cells and the degree of brain atrophy. Inflammation, dysfunction of BBB, increased cholesterol turnover might counteract this tendency resulting in increased levels or, in some cases, in unsignificant changes. The study of plasma 24OHC is likely to offer an insight about brain cholesterol turnover with a limited diagnostic power.

Impact and Therapeutic Potential of PPARs in Alzheimer's Disease

Peroxisome proliferator activated receptors (PPARs) are well studied for their role of peripheral metabolism, but they also may be involved in the pathogenesis of various disorders of the central nervous system (CNS) including multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer's and, Parkinson's disease. The observation that PPARs are able to suppress the inflammatory response in peripheral macrophages and in several models of human autoimmune diseases, lead to the idea that PPARs might be beneficial for CNS disorders possessing an inflammatory component. The neuroinflammatory response during the course of Alzheimer's disease (AD) is triggered by the deposition of the β-amyloid peptide in extracellular plaques and ongoing neurodegeneration. Non-steroidal anti-inflammatory drugs (NSAIDs) have been considered to delay the onset and reduce the risk to develop Alzheimer’s disease, while they also directly activate PPARγ. This led to the hypothesis that NSAID protection in AD may be partly mediated by PPARγ. Several lines of evidence have supported this hypothesis, using AD related transgenic cellular and animal models. Stimulation of PPARγ by synthetic agonist (thiazolidinediones) inducing anti-inflammatory, anti-amyloidogenic and insulin sensitizing effects may account for the observed effects. Several clinical trials already revealed promising results using PPARγ agonists, therefore PPARγ represents an attractive therapeutic target for the treatment of AD.

Plasma 24S-hydroxycholesterol levels in elderly subjects with late onset Alzheimer's disease or vascular dementia: a case-control study

BACKGROUND

In central nervous system cholesterol cannot be degraded but is secreted into circulation predominantly in the form of its polar metabolite 24(S)-hydroxycholesterol (24S-OH-Chol). Some studies suggested an association between 24S-OH-Chol metabolism and different neurological diseases including dementia. A possible decrease in 24S-OH-Chol plasma levels has been reported late onset Alzheimer's disease (LOAD) and vascular dementia (VD), but results of previous studies are partially contradictory.

METHODS

By high-speed liquid chromatography/tandem mass spectrometry we evaluated the plasma levels of 24S-OH-Chol in a sample of 160 older individuals: 60 patients with LOAD, 35 patients with VD, 25 subjects affected by cognitive impairment no-dementia (CIND), and 40 (144 for genetics study) cognitively normal Controls. We also investigated the possible association between PPARgamma Pro12Ala polymorphism and dementia or 24S-OH-Chol levels.

RESULTS

Compared with Controls, plasma 24S-OH-Chol levels were higher in LOAD and lower in VD; a slight not-significant increase in CIND was observed (ANOVA p: 0.001). A positive correlation between 24S-OH-Chol/TC ratio and plasma C reactive protein (CRP) levels was found in the whole sample, independent of possible confounders (multiple regression p: 0.04; r2: 0.10). This correlation was strong in LOAD (r: 0.39), still present in CIND (r: 0.20), but was absent in VD patients (r: 0.08). The PPARgamma Pro12Ala polymorphism was not associated with the diagnosis of LOAD, VD, or CIND; no correlation emerged between the Ala allele and 24S-OH-Chol plasma levels.

CONCLUSIONS

Our results suggest that plasma 24S-OH-Chol levels might be increased in the first stages of LOAD, and this phenomenon might be related with systemic inflammation. The finding of lower 24S-OH-Chol concentrations in VD might be related with a more advanced stage of VD compared with LOAD in our sample, and/or to different pathogenetic mechanisms and evolution of these two forms of dementia.

APOE dependent-association of PPAR-γ genetic variants with Alzheimer's disease risk

The peroxisome proliferator-activated receptor-γ (PPAR-γ) is a ligand-inducible transcription factor that suppresses microglial inflammatory responses and inhibits amyloid beta (Aβ) production through promoting cholesterol efflux from glial cells. PPAR-γ agonists have been advanced as a new disease altering approach to Alzheimer's disease (AD), with rosiglitazone therapy having improved cognition in those AD patients that did not possess an Apolipoprotein E (APOE) ε4 allele. The current study was designed to explore the effect of interactions between PPAR-γ and APOE gene polymorphisms on the AD risk. We examined genetic variations of PPAR-γ by genotyping 7 haplotype tagging SNPs (htSNPs) (rs10510412, rs17793951, rs1801282, rs4135263, rs1151999, rs709149, and rs709154) in a group of 352 Spanish late-onset AD cases and 438 controls. The PPAR-γ TCCA haplotype derived from SNPs in introns 4 (rs4135263), 5 (rs1151999), and 6 (rs709149 and rs709154) showed a strong protective effect against AD in APOE ε4 allele noncarriers (p=0.001, permutation p=0.006, Bonferroni corrected p=0.021), with a frequency of 39% in cases and 50% in controls. Our data suggest that PPAR-γ genetic variants may modify the risk of AD in an APOE ε4 allele-dependent fashion.

Influence of the Pro12Ala polymorphism of PPAR-gamma on age at onset and sRAGE levels in Alzheimer's disease

Peroxisome proliferator-activated receptor gamma (PPAR-gamma) has been described to have a role in the modulation of various genes involved in Abeta homeostasis, inflammation, and energy metabolism, making it a candidate gene for risk of Alzheimer's disease (AD). A functional polymorphism in exon 2 of the PPAR-gamma gene has been related to AD, but the effects are inconsistent across studies. To determine the role of PPAR-gamma in genetic susceptibility to AD in a representative Chinese sample, we genotyped 362 AD patients and 370 healthy controls for PPAR-gamma Pro12Ala polymorphism by polymerase chain reaction-restriction fragment length polymorphism method. We also examined the potential impact of this polymorphism on plasma level of soluble receptor for advanced glycation end products (sRAGE), a decoy receptor whose reduction has been associated with a higher risk of AD. Our results suggest that PPAR-gamma Pro12Ala polymorphism was not associated with an increased risk of AD in the overall sample. Stratification analysis revealed that the PPAR-gamma Pro/Ala genotype may be associated with the development of early-onset AD in the individuals without APOE epsilon4 allele (OR=3.76, 95% CI=1.10-12.84; p=0.03), but this association became insignificant after Bonferroni correction (p (corr)=0.10). Moreover, in the subgroup of APOE epsilon4 noncarriers, Kaplan-Meier survival analyses indicated that AD patients with the Pro/Ala genotype presented with disease onset 4.6 years earlier than carriers of Pro/Pro genotype. Further investigation revealed that AD patients carrying Pro/Ala genotype had significantly lower plasma sRAGE levels than patients with Pro/Pro genotype. These findings suggest that the functional PPAR-gamma Pro12Ala polymorphism may modify the age at onset of AD.

PPARγ2 polymorphism and human health

The nuclear hormone receptor peroxisome proliferator activated receptor gamma (PPARγ) is an important transcription factor regulating adipocyte differentiation, lipid and glucose homeostasis, and insulin sensitivity. Numerous genetic mutations of PPARγ have been identified and these mutations positively or negatively regulate insulin sensitivity. Among these, a relatively common polymorphism of PPARγ, Pro12Ala of PPARγ2, the isoform expressed only in adipose tissue has been shown to be associated with lower body mass index, enhanced insulin sensitivity, and resistance to the risk of type 2 diabetes in human subjects carrying this mutation. Subsequent studies in different ethnic populations, however, have revealed conflicting results, suggesting a complex interaction between the PPARγ2 Pro12Ala polymorphism and environmental factors such as the ratio of dietary unsaturated fatty acids to saturated fatty acids and/or between the PPARγ2 Pro12Ala polymorphism and genetic factors such as polymorphic mutations in other genes. In addition, this polymorphic mutation in PPARγ2 is associated with other aspects of human diseases, including cancers, polycystic ovary syndrome, Alzheimer disease and aging. This review will highlight findings from recent studies.

The PPAR-gamma Pro12Ala polymorphism and risk of cognitive impairment in a longitudinal study

The Pro12Ala polymorphism in the PPAR-gamma gene has been associated with reduced incidence of type 2 diabetes. Although diabetes has been implicated as a risk factor for dementia, the association of Pro12Ala with cognitive impairment is unclear. Dementia and cognitive impairment without dementia (CIND) were determined during six annual follow-up evaluations in a cohort of 929 older Latinos. Among those with diabetes at baseline, there was an increased rate of dementia/CIND for Ala carriers compared to non-carriers (adjusted hazard ratio (HR)=2.5, 95% confidence interval (CI): 1.3-4.9) but not among non-diabetic participants (adjusted HR=0.94; 95% CI: 0.49-1.8). Among males, there was also an increased rate for Ala carriers (adjusted HR=2.7, 95% CI: 1.4-5.2) but not among female carriers (adjusted HR=0.88; 95% CI: 0.47-1.6). The rate of dementia/CIND was highest in diabetic male Ala carriers (adjusted HR=4.2; 95% CI: 1.5-11) compared to non-diabetic male carriers (adjusted HR=2.9; 95% CI: 1.1-7.4), diabetic female carriers (HR=1.6; 95% CI: 0.66-4.1), and non-diabetic female carriers (HR=0.52; 95% CI: 0.21-1.3). These data suggest that although the Ala variant is associated with a reduced risk of type 2 diabetes, it may increase the risk of cognitive impairment in individuals once diabetes has developed. Male Ala carriers may also have a greater risk of dementia/CIND.

Lack of genetic association between PPARG gene polymorphisms and Finnish late-onset Alzheimer's disease

Single nucleotide polymorphisms (SNPs) in diabetes related peroxisome proliferator-activated receptor gamma (PPARG) gene were investigated with a case-control approach. To examine the genetic association of this gene with Alzheimer's disease (AD) risk, we used the TaqMan technique to genotype eight SNP sites for PPARG gene, in 538 Finnish AD cases and 672 controls and conducted a single allele and genotypic distribution comparison as well as estimated haplotype frequencies between cases and controls. No significant differences in AD risk were found in single SNP and haplotype analyses for PPARG gene between the study groups. We conclude that PPARG gene does not play a major role in the genetic predisposition to AD in the Finnish population.

An analysis of peroxisome proliferator-activated receptor gamma (PPAR-gamma 2) Pro12Ala polymorphism distribution and prevalence of type 2 diabetes mellitus (T2DM) in world populations in relation to dietary habits

BACKGROUND AND AIM

The human peroxisome proliferator-activated receptor gamma (PPAR-gamma) is involved in lipid storage, glucose homeostasis and adipocyte differentiation. The Ala allele of the Pro12Ala polymorphism has been associated with a protective effect against T2DM. Ala allele frequencies are known for many populations, but data are absent for other interesting human groups.

METHODS AND RESULTS

We examined samples from Ethiopia, Benin, Ecuador and Italy. In addition, we performed an analysis of the Pro12Ala polymorphism distribution in world populations, also in relation to T2DM prevalence and the diet lipid content. In the European populations, the Ala allele frequencies are distributed according to a latitudinal trend, with the highest in the northern and central European populations and the lowest in the Mediterranean populations. Considering the world populations, a significant inverse relationship between Ala frequency and T2DM prevalence was observed mainly in populations where energy from lipids exceeded 30% of the total energy intake.

CONCLUSION

Northern Europe's cold climate has been hypothesised to have played a role in contributing to the present pattern. Moreover our analysis appears to confirm, at a population level, the protective effect of Ala allele against T2DM, already observed in case-control studies, but only in populations with a diet rich in lipids.

In vitro effect of PPAR-γ2 Pro12Ala polymorphism on the deposition of Alzheimer's amyloid-β peptides

Mounting evidence suggests that peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is involved in the modulation of pathogenic events related to Alzheimer's disease (AD). Such events would include the cerebral deposition of amyloid-beta (Abeta) and the consequent local inflammatory response. PPAR-gamma has been shown to act on both fronts, reducing either the secretion of Abeta or the expression of pro-inflammatory cytokines. Recently, the relatively common Pro12Ala polymorphism in exon 2 of PPAR-gamma has been associated with higher risk for late onset AD. Here, we compare the effect of PPAR-gamma and its genetic variant on the secretion of Abeta. Our results indicate that, in neuronal cultured cells, the Pro12Ala substitution does not affect the anti-amyloidogenic capacity of PPAR-gamma. Additional factors, PPAR-gamma related, may therefore predispose aged subjects, carrying the Ala allele, to develop the neurodegenerative disease.

Association study of cholesterol-related genes in Alzheimer's disease

Alzheimer's disease (AD) is a genetically complex disorder, and several genes related to cholesterol metabolism have been reported to contribute to AD risk. To identify further AD susceptibility genes, we have screened genes that map to chromosomal regions with high logarithm of the odds scores for AD in full genome scans and are related to cholesterol metabolism. In a European screening sample of 115 sporadic AD patients and 191 healthy control subjects, we analyzed single nucleotide polymorphisms in 28 cholesterol-related genes for association with AD. The genes HMGCS2, FDPS, RAFTLIN, ACAD8, NPC2, and ABCG1 were associated with AD at a significance level of P < or = 0.05 in this sample. Replication trials in five independent European samples detected associations of variants within HMGCS2, FDPS, NPC2, or ABCG1 with AD in some samples (P = 0.05 to P = 0.005). We did not identify a marker that was significantly associated with AD in the pooled sample (n = 2864). Stratification of this sample revealed an APOE-dependent association of HMGCS2 with AD (P = 0.004). We conclude that genetic variants investigated in this study may be associated with a moderate modification of the risk for AD in some samples.

The peroxisome proliferator-activated receptor gamma (PPAR-γ2) Pro12Ala polymorphism is associated with higher risk for Alzheimer's disease in octogenarians

Recent observations support the hypothesis that inflammatory processes at the brain level may contribute to the pathogenesis of Alzheimer's disease (AD). Peroxisome proliferator-activated receptor gamma (PPAR-gamma) is involved in such processes, so we thought it interesting to study the Pro12Ala polymorphism in exon 2 of the gene in a sample of late-onset AD patients. We found that Ala genotypes were significantly overrepresented among octogenarian patients compared to controls (p=0.034). Using logistic regression we observed that carrying the Ala allele significantly increased by nearly two-fold the risk of developing AD in subjects 80 years or older (OR=1.98; 95% CI 1.03-3.80, p=0.04). Though this difference was borderline significant after correction for multiple comparisons, our results suggest a possible involvement of the PPAR-gamma gene in susceptibility to late-onset AD in octogenarians.

PPARD haplotype influences cholesterol metabolism but is no risk factor of Alzheimer's disease

Cholesterol metabolism is involved in Alzheimer's disease (AD) pathogenesis: increased cholesterol blood levels are detected in AD patients, and treatment with statins reduces the risk of AD. The peroxisome proliferator-activated receptor delta protein (PPARdelta), is a member of the steroid hormone super family of ligand-inducible transcription factors, and is of major relevance in lipid and cholesterol metabolism. We investigated three frequent polymorphisms located in exons 4 (rs2016520) and 9 (rs3734254 and rs9794) of the PPARdelta gene (PPARD) for their putative influence on the risk of AD and on plasma levels of cholesterol, 24S-hydroxycholesterol and 27-hydroxycholesterol. The study population consisted of 167 AD patients (mean age: 74.27+/-9.37 years; female 78.6%) and 194 controls (mean age: 73.26+/-8.37 years; female 57.2%). Haplotype analysis was perfomed, however, we did not find PPARD haplotypes to influence the risk of AD. In contrast to these results, a two marker haplotype consisting of rs2016520 and rs9794 in AD patients showed a significant effect on the relative plasma levels of 24S-hydroxycholesterol (carriers: 32.1+/-2.8ng/mg; non-carriers: 40.3+/-1.4ng/mg; p=0.016) and 27-hydroxycholesterol (carriers: 40.8+/-7.7ng/mg; non-carriers: 58.6+/-2.3ng/mg; p=0.002) but not in non-demented controls. Our results suggest that PPARD haplotypes might influence levels of cholesterol metabolites in AD patients, but act not as risk factors of AD.

Novel therapeutic opportunities for Alzheimer's disease: focus on nonsteroidal anti-inflammatory drugs

Alzheimer's disease (AD) is the most common form of neurodegenerative disorder with dementia in the elderly. The AD brain pathology is characterized by deposits of amyloid-beta (Abeta) peptides and neurofibrillary tangles but also (among other aspects) by signs of a chronic inflammatory process. Epidemiological studies have shown that long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) reduces the risk of developing AD and delays its onset. Classical targets of NSAIDs include cycloxygenase, nuclear factor kappaB, and peroxisome proliferator-activated receptors. Modulation of these pathways, all of which have been implicated in AD pathogenesis, could explain the NSAID effect on AD progression. However, recent studies indicate that a subset of NSAIDs such as ibuprofen, indomethacin, and flurbiprofen may have direct Abeta-lowering properties in cell cultures as well as transgenic models of AD-like amyloidosis. A renewed interest in the old and a discovery of new pharmacological properties of these drugs are providing vital insight for future clinical trials. In this review we will summarize how the combination of traditional (anti-inflammatory) and new (anti-amyloidogenic) properties of some NSAIDs is providing unprecedented opportunities for drug discovery and could potentially result in novel therapeutic approaches for the treatment of AD.

Contribution of inflammatory processes to Alzheimer's disease: molecular mechanisms

There is compelling evidence that Alzheimer's disease (AD) amyloid-beta (Abeta) deposition is associated with a local inflammatory response, which is initiated by the activation of microglia and the recruitment of astrocytes. These cells secrete a number of cytokines and neurotoxic products that may contribute to neuronal degeneration and cell death. It has been documented that long-term intake of non-steroidal anti-inflammatory drugs (NSAIDs) decrease the risk for developing AD and delay the onset of the disease. The mechanism behind these NSAIDs is still controversial and several hypotheses have been raised, including changes in the amyloid precursor protein (APP) metabolism, in Abeta aggregation and a decrease in inflammatory mediators. Recently, it was proposed that some NSAIDs might activate the peroxisome proliferator-activated receptor-gamma (PPAR-gamma). PPAR-gamma belongs to a family of nuclear receptors that are able to regulate the transcription of pro-inflammatory molecules, such as iNOS. The activation of PPAR-gamma has been recently reported to reduce Abeta levels in cell culture and AD animal models. The implication of PPAR-gamma in the control of Abeta-induced inflammation suggests a new target for AD therapy and emphasize the contribution of neuroinflammatory mechanisms to the pathogenesis of AD.