Association between an interleukin-6 promoter and 3' flanking region haplotype and reduced Alzheimer's disease risk in a German population

Two New Biocontrol Agents Against Clubroot Caused by Plasmodiophora brassicae

Clubroot disease caused by Plasmodiophora brassicae can lead to serious yield losses in crucifers such as Brassica napus. In this study, 323 bacterial strains were isolated from the rhizosphere of severely diseased B. napus in Dangyang county, Hubei province, China. Antagonistic strains were first identified based on dual culture inhibition zones with Fusarium oxysporum and Magnaporthe oryzae. These were then further screened in germination inhibition and viability assays of resting spores of P. brassicae. Finally, eight of the antagonistic strains were found to significantly reduce the disease severity of clubroot by more than 40% under greenhouse conditions, and two strains, F85 and T113, were found to have efficacy of more than 80%. Root hair infection experiments showed that F85 and T113 can inhibit early infection of root hairs, reduce the differentiation of primary plasmodia of P. brassicae, and inhibit formation of secondary zoosporangia. Based on sequence analysis of 16S rDNA gene, gyrA gene and 22 housekeeping genes as well as carbon source utilization analysis, the F85 was identified as Bacillus velezensis and T113 as Bacillus amyloliquefaciens. Genome analysis, PCR and RT-PCR detection revealed that both F85 and T113 harbor various antibiotic biosynthesis gene clusters required to form peptides with antimicrobial activity. To our knowledge, this is the first report of B. velezensis as a biocontrol agent against clubroot disease.

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.

Association between interleukin-6 -174G/C polymorphism and the risk of Alzheimer's disease: a meta-analysis

BACKGROUND

The -174G/C polymorphism in interleukin 6 (IL-6) gene has been extensively investigated for association to Alzheimer's disease (AD); however, results of different studies have been inconsistent. The objective of this study is to assess the relationship of IL-6 -174G/C polymorphism and Alzheimer's disease (AD) risk by using meta-analysis.

METHODS

All eligible case-control studies were searched in PubMed and EMBASE. Odds ratios (ORs) with the 95% confidence intervals (CIs) were used to assess the association.

RESULTS

A total of 5316 cases and 10 757 controls in 21 case-control studies were included. Obvious heterogeneity among studies was detected, and no significant association was observed between the IL-6 -174G/C polymorphism and AD risk. After exclusion of three studies, the heterogeneity disappeared and significant association was observed between the polymorphism and AD risk in Asians (CC vs. CG+GG: OR = 0.5; 95%CI, 0.33-0.75) but not in Caucasians.

CONCLUSION

This meta-analysis suggested that the -174G/C polymorphism of IL-6 gene would be a protective risk factor for AD in Asians. To further evaluate gene-to-gene and gene-to-environmental interactions between polymorphisms of IL-10 gene and AD risk, more studies with large groups of patients are required.

IL-6-174 G/C and -572 C/G polymorphisms and risk of Alzheimer's disease

Associations between interleukin 6 (IL-6) polymorphisms and Alzheimer's disease (AD) remain controversial and ambiguous. The aim of this meta-analysis is to explore more precise estimations for the relationship between IL-6-174 G/C and -572 C/G polymorphisms and risk for AD. Electronic searches for all publications in databases PubMed and EMBASE were conducted on the associations between IL-6 polymorphisms and risk for AD until January 2012. Odds ratio (OR) and 95% confidence intervals (CIs) were calculated using fixed and random effects models. Twenty-seven studies were included with a total of 19,135 individuals, involving 6,632 AD patients and 12,503 controls. For IL-6-174 G/C polymorphism, the combined results showed significant differences in recessive model (CC vs. CG+GG: OR = 0.65, 95%CI = 0.52-0.82). As regards IL-6-572 C/G polymorphism, significant associations were shown in dominant model (CG+GG vs. CC: OR= 0.73, 95% CI = 0.62-0.86) and in additive model (GG vs. CC, OR= 0.66, 95% CI = 0.46-0.96). In conclusion, genotype CC of IL-6-174 G/C and genotype GG plus GC of IL-6-572 C/G could decrease the risk of AD.

Do gene polymorphism in IL-1β, TNF-α and IL-6 influence therapeutic response in patients with drug refractory epilepsy?

PURPOSE

Pro-inflammatory cytokines may play an important pathophysiological role in patients with epilepsy. To understand the role of genes encoding pro-inflammatory cytokines in epilepsy, this study aimed to evaluate the polymorphisms of the promoter regions of IL-1β-511C>T (rs16944), TNF-α-308G>A (rs1800629) and IL-6-174G>C (rs1800795) genes and to look into the interaction between these genes in influencing seizure susceptibility, seizure frequency and response to therapy.

METHODS

The comparative frequency of polymorphism was determined in rs16944, rs1800629 and rs1800795 using PCR-RFLP in a group of 120 persons with epilepsy (PWE) and 110 ethnically matched healthy subjects of comparable age and sex in the North Indian population.

RESULTS

Alleles and genotypes of rs16944, rs1800629 and rs1800795 were not found to influence the odds ratio of having susceptibility to epilepsy. Also gene-gene interaction of possible nine combinations of these genes did not show any positive association with epilepsy. The genotype and allelic frequency of rs1800795 showed a significant association (p<0.05) in seizure frequency (number of seizures/6-months) and drug refractory epilepsy. However, the genotype and allelic frequency of rs16944 and rs1800629 were not found to have such effect.

CONCLUSION

This study demonstrates that the rs16944, rs1800629 and rs1800795 polymorphism does not act as a strong susceptibility factor for epilepsy in North Indian population. The genotypic association of rs1800795 with seizure frequency and drug-refractory epilepsy raises the issue that a specific set of polymorphic genes can influence seizures and therapeutic response in epilepsy.

Association between polymorphism in the promoter region of Interleukin 6 (-174 G/C) and risk of Alzheimer's disease: a meta-analysis

Studies of the relationship between Alzheimer's disease (AD) and polymorphism in the promoter region of Interleukin 6 (IL-6) -174 G/C have reported inconsistent results. To assess the association between IL-6 -174 G/C promoter polymorphism and AD risk, a meta-analysis containing 3,101 AD cases and 3,860 controls from 18 case-control studies was performed. There were 16 studies involving Europeans and 2 studies involving non-Europeans. The combined results showed significant differences in recessive model [CC versus GC + GG, odds ratio (OR) = 0.70, 95% confidence interval (CI) = 0.54-0.90] and heterozygote comparison (CC versus GC, OR = 0.76, 95% CI = 0.60-0.96) on the basis of all studies. On subgroup analysis by ethnicity, similarly significant differences in recessive model (CC versus GC + GG) were found in both Europeans and non-Europeans, but significant difference in heterozygote comparison (CC versus GC) was found only in non-Europeans. In conclusion, there were statistically significant differences in genotype distribution of IL-6 -174 G/C between AD cases and controls in recessive model (CC versus GC + GG). Genotype CC of IL-6 -174 G/C could decrease the risk of AD. Further studies with large sample size, especially in subgroup analysis, should be done.

Association between variable number tandem repeats within the 3' flanking region of the interleukin-6 gene and systemic lupus erythematosus in Korean patients

Variable number tandem repeat (VNTR) polymorphism located in the 3' flanking region of the interleukin-6 (IL-6) gene was examined in Koreans with systemic lupus erythematosus (SLE). We identified 15 VNTR alleles (K1 to K15) in the 3' flanking region by Genescan analysis. The VNTR K8 allele, a 648-base pair (bp) allele, was most commonly found in Koreans, being present in 74.8% of the SLE patients and 70.3% of the normal controls. The VNTR K9 (642 bp) allele was associated with susceptibility to SLE. In addition, the VNTR K9 was significantly associated with leukopenia (p = 0.048), thrombocytopenia (p = 0.020), and elevated C-reactive protein (p = 0.019). These data suggest that the VNTR K9 in the 3' flanking region of the IL-6 gene may be associated with disease susceptibility and the clinical phenotypes of SLE.

Interleukin 6-174 G/C promoter and variable number of tandem repeats (VNTR) gene polymorphisms in sporadic Alzheimer's disease

BACKGROUND

Previous studies examining the association between the interleukin 6 (IL-6)-174 C/G polymorphism and Alzheimer's disease (AD) have yielded conflicting results. Furthermore, the C allele of the IL-6 variable number of tandem repeats (VNTR) polymorphism was associated with a delayed onset and a decreased risk of AD.

METHODS

A total sample of 149 AD patients, and 298 age- and sex-matched unrelated caregivers from Apulia, southern Italy, were genotyped for the apolipoprotein E (APOE) polymorphism, the VNTR polymorphism in the 3' flanking region, and the -174G/C single-nucleotide polymorphism (SNP) in the promoter region of IL-6 gene on chromosome 7. Furthermore, we performed a haplotype analysis on these two polymorphisms on IL-6 locus.

RESULTS

IL-6 VNTR and -174G/C allele and genotype frequencies were similar between AD patients and controls, also after stratification for late-onset (> or =65 years) and early-onset (<65 years) or APOE epsilon4 status. Furthermore, there was no evidence of linkage disequilibrium between the VNTR and -174G/C polymorphisms, not supporting a previous reported additive effect of both IL-6 polymorphisms on AD risk.

CONCLUSIONS

Our findings did not support a role of IL-6-174 G/C and IL-6 VNTR polymorphisms in the risk of sporadic AD in southern Italy, suggesting that these polymorphisms of IL-6 gene were at most weak genetic determinants of AD.

INTERLEUKIN-6 PROMOTER POLYMORPHISM AND LATE-ONSET ALZHEIMER's DISEASE IN THE FINNISH POPULATION

Recently, the involvement of the inflammatory response in Alzheimer's disease (AD) has received considerable attention. The gene encoding for interleukin-6 (IL-6) is interesting since IL-6 has been reported not only to be involved in immune functions but also in AD. We investigated whether the IL-6-174 G/C polymorphism is associated with late onset AD (LOAD) in the Finnish subjects. The G allele was over-represented in ApoE4-LOAD patients but remained unimportant in all and in the ApoE E4 carriers. Interestingly, the G allele frequency was lower in our population in both AD patients and in controls compared to Southern European populations.

Zinc-gene interaction related to inflammatory/immune response in ageing

The pivotal role played by zinc-gene interaction in affecting some relevant cytokines (IL-6 and TNF-alpha) and heat shock proteins (HSP70-2) in ageing, successful ageing (nonagenarians) and the most common age-related diseases, such as atherosclerosis and infections, is now recognized. The polymorphisms of genes codifying proteins related to the inflammation are predictive on one hand in longevity, on the other hand they are associated with atherosclerosis or severe infections. Since the health life-span has a strong genetic component, which in turn also affected by nutritional factors like zinc, the association of these polymorphisms with innate immune response, zinc ion bioavailability and Metallothioneins (MT) homeostasis is an useful tool to unravel the role played by zinc-gene interactions in longevity, especially due to the inability of MT in zinc release in ageing and chronic inflammation. In ageing, this last fact leads to depressed innate immune response for host defence. In contrast, in very old age the inflammation is lower with subsequent more zinc ion bioavailability, less MT gene expression and satisfactory innate immunity. Therefore, the zinc-gene (IL-6, TNF-alpha, Hsp70-2) interactions, via MT homeostasis, are crucial to achieve successful ageing.

Interleukin 6 Variable Number of Tandem Repeats (VNTR) Gene Polymorphism in Centenarians

Recent population-based studies identified the magnitude of interleukin 6 (IL6) serum levels as a marker for functional disability, and a predictor of disability and mortality among the elderly. We investigated whether there was evidence in Southern Italy of an association between the IL6 gene variable number of tandem repeats (VNTR) polymorphism and extreme longevity, and tested for the possible interaction of apolipoprotein E (APOE) alleles with the IL6 VNTR alleles. Four alleles coding for variants of four different lengths have been identified: allele A [760 base pairs (bp)], allele B (680 bp), allele C (640 bp), and allele D (610 bp). IL6 VNTR and APOE allele and genotype frequencies were studied in a total of 61 centenarians and 94 middle-aged subjects from Southern Italy. The IL6 VNTR allele B was overrepresented in the younger control group compared with centenarians (odds ratio: 0.56, 95% confidence interval: 0.35-0.88, Bonferroni p-value < 0.05). No interactions between IL6 VNTR alleles and APOE alleles on the odds ratios to reach extreme longevity were evaluated for the smallest number of subjects in centenarians and younger controls. Our findings suggested that the presence of the IL6 VNTR allele B could be detrimental for reaching extreme longevity.

Association of cytokine gene polymorphisms with malignant melanoma in Caucasian population

It has been hypothesized that polymorphisms expected to result in functional changes in cytokine genes may influence susceptibility to cancer, including malignant melanoma (MM). Here, we have screened 24 potentially functional polymorphisms in five cytokine genes by PCR-SBT and PCR-SSP methods in 122 MM cell lines derived from Caucasian patients. The polymorphic positions studied were: TNFA -1031, -863, -857, -851, -574, -376, -308, -238, +488; TGFB1 -988, -800, -509, +869, +915, +652, +673, +713, +788; IL10 -1082, -819, -592; IL6 -174; IFNG -333, +874. The frequencies of cytokine genotypes of melanoma tumours were compared with those published for healthy Caucasians. It was found that TNFA -238 GA, TGFB1 -509 CT, -800 GG, IFNG +874 AT, IL6 -174 GG, IL10 -1082 GA genotypes were significantly decreased, while TNFA -238 AA, -857 CC, TGFB1 -509 TT, IFNG +874 AA, IL6 -174 CC, IL10 -1082 AA, -819 TT, -592 AA genotypes were significantly increased, in MM. This suggests that genotypes provisionally associated with low expression of pro-inflammatory and immunomodulatory TNF-alpha, IFN-gamma and IL-6 and anti-inflammatory IL-10 and TGF-beta1 could be involved in the mechanisms of cancer progression and escape from immunosurveillance.

Nutrient-gene interaction in ageing and successful ageing. A single nutrient (zinc) and some target genes related to inflammatory/immune response

In this paper, we reviewed data regarding to the pivotal role played by the zinc-gene interaction in affecting some relevant cytokines (IL-6 and TNF-alpha) and heat shock proteins (Hsp70-2) in ageing, successful ageing (nonagenarians) and in some age-related diseases (atherosclerosis and infections). The polymorphisms of the genes codifying these proteins are predictive on one hand in longevity, such as IL-6 -174G/C locus, on the other hand 1267 Hsp70-2A/B or TNF-alpha -308G/A polymorphisms are associated to worsening atherosclerosis or severe infections, respectively, rather than longevity. Taking into account that longevity has a strong genetic component but, at the same time, is affected by life style and environmental factors, the analysis of these polymorphisms in association to some immune parameters (NK cell cytotoxicity) and nutritional factors (zinc) is a useful tool to unravel the role played by these genetic factors in longevity and in the appearance of age-related diseases. Indeed, these polymorphisms are associated with chronic inflammation, low zinc ion bioavailability, depressed innate immune response and high gene expression of metallothioneins, which have a limited zinc release for an optimal innate immune response in ageing. Therefore, the nutrient (zinc)-gene (IL-6, TNF-alpha and Hsp70-2) interaction is pivotal to keep under control the inflammatory/immune response with subsequent longevity, indicating these genes as "robust" for "healthy ageing".

Interleukin 6-174 G/C promoter gene polymorphism and sporadic Alzheimer's disease: geographic allele and genotype variations in Europe

The interleukin 6 (IL-6) gene in humans is located in the short arm of chromosome 7 and has a-174 G/C polymorphism in its promoter region. The C allele at position-174 in the promoter of the interleukin 6 (IL-6) gene has been associated with reduced gene expression and reduced plasma levels of IL-6. Given the supposed role of several inflammatory mediators in neurodegeneration and Alzheimer's disease (AD), the IL-6-174 G/C promoter polymorphism has been associated with AD with contrasting findings. First aim of the present study was to investigate whether there was evidence in Southern Italy of an association between the IL-6-174 G/C promoter polymorphism and AD. Secondly, we also tested a possible effect of geographic genetic variations on existing reported associations comparing our results with the findings from published studies on other European populations. We examined apolipoprotein E (APOE) and IL-6-174 G/C promoter polymorphisms in a cohort of 168 sporadic AD patients and 220 sex- and age-matched nondemented controls from Southern Italy. No differences have been found in the IL-6-174 G/C promoter allele and genotype frequencies between AD patients and controls nor in early- and late-onset subsets of AD patients. No statistically significant differences in frequencies between IL-6-174 G/C promoter alleles and AD among APOE allele strata were found. Finally, comparing our results with the findings from other European populations, the IL-6*G/*G genotype frequency showed a statistically significant increasing trend from Northern to Southern regions of Europe in AD patients and controls, with a concomitant increase in IL-6*C/*G genotype frequency. Furthermore, an increasing geographical trend from North to South was found for the IL-6*G allele, with a concomitant inverse trend for IL-6*C allele. We suggest that regional European differences in genotype and allele frequencies of the IL-6-174 G/C promoter polymorphism may explain in part controversial findings on this polymorphism in AD in various European studies.

Interleukin-10 and interleukin-6 gene polymorphisms as risk factors for Alzheimer’s disease

In the pathogenesis of Alzheimer disease (AD), it has been proposed that the anti-inflammatory interleukins such as IL-10 regulate beta-amyloid-induced microglial inflammatory responses inhibiting the proinflammatory cytokine IL-6. Since the promoters of the IL-10 and IL-6 genes show single nucleotide polymorphisms (SNPs) (IL-10: -1082 G --> A; IL-6: -174 G --> C), we investigated these SNPs and cytokine production by peripheral blood mononuclear cells in 65 AD patients and 65 controls (HC). In AD there was a significant increase of the -1082A IL-10 allele (P=0.009) and a decrease of -1082GG genotype (P=0.019). The frequency of the GG IL-6 genotype in AD was lower and the C allele significantly higher (P <0.005). The co-occurrence of IL-10 A and IL-6 C alleles significantly raised the odds ratio (OR 11.2, confidence interval: CI 1.3-97.3; P <0.05) independently of apolipoprotein E4 (adjusted OR 10.3, CI 1-108; P <0.05). Only amyloid-stimulated IL-10 production differed between the groups (P=0.023). These results raise questions regarding the inflammatory theory in AD, pointing to a pivotal role of IL-10 and IL-6 and a selective alteration in this network.

Interleukin-6 promoter polymorphism: risk and pathology of Alzheimer's disease

Inflammatory and immune responses are involved in the pathogenesis of Alzheimer's disease (AD). Interleukin-6 (IL-6), an inflammatory cytokine, is thought to play a role in neurodegeneration of the central nervous system and has been associated with increased amyloid precursor protein expression in vitro and greater cognitive decline. Previously a C-174G polymorphism in the promoter of IL-6, which influences expression in vitro, has been found associated in some studies but not all. We investigated this polymorphism in a large independent UK sample of AD cases (n = 356) and controls (n 434) but found no association. We extended the study to genotype/phenotype correlations but found no correlation with age of onset (n = 338), brain amyloid load (n = 126) or Tau load (n = 101), brain microglial cell load (n = 65) or brain reactive astrocytes (n = 127). Our data do not support a pathogenic role in AD for the C-174G polymorphism in isolation.

Interleukin-6 gene alleles affect the risk of Alzheimer's disease and levels of the cytokine in blood and brain

Two different polymorphic regions of the interleukin-6 (IL-6) gene were investigated in patients with Alzheimer's disease (AD) and non-demented controls. The -174 C allele in the promoter region of IL-6 gene was over-represented in AD patients compared to controls and significantly increased the risk of AD. Moreover, the -174 CC genotype was associated with a high risk of the disease in women. The D allele of a variable number of tandem repeat (VNTR) was in strong linkage disequilibrium with the -174 C allele and slightly increased AD risk. On the other hand, the frequency of the VNTR C allele was decreased in patients with AD and was negatively associated with the risk of developing AD. Both the -174 CC and VNTR DD genotypes were also associated with increased IL-6 levels in the blood and brain from AD. These findings suggest that IL-6 may play a multifaceted role in AD by affecting the turnover of the cytokine.

Association between -174 G/C polymorphism of interleukin-6 gene and alcoholism

OBJECTIVES

IL-6 plays the role as a physiological neuromodulator involved in dopaminergic, serotonergic and other neurotransmissions. The aim of the present association study was to examine the effect of the G/C -174 polymorphism of the IL-6 gene on disposition to alcoholism.

METHODS

We investigated the relationship between the G/C -174 polymorphism of the IL-6 gene and alcohol dependence in 281 alcoholics and 242 control subjects.

RESULTS

The significant difference in G allele frequency between alcoholic group (0.52) and control group (0.59) was found (P < 0.03).

CONCLUSION

To our knowledge, this is the first finding providing evidence for an association between alcoholism and the polymorphism of the IL-6 gene. The background of the relationship between the IL-6 gene and alcoholism is discussed.

Association of interleukin-6 promoter variant with bone mineral density in pre-menopausal women

Interleukin-6 (IL6) has many roles essential to the regulation of the immune response, hematopoiesis, and bone resorption. Three single-nucleotide polymorphisms (SNP) in the IL6 promoter region were genotyped by the single-base extension method. The frequencies of each SNP were 0.002 ( IL6-597 G--> A), 0.27 ( IL6-572 G--> C), and 0.002 ( IL6-174 G--> C) in a Korean population ( n=1,082). IL6-597 G--> A and IL6-174 G--> C were totally linked together ( d(2)=1) and showed very low allele frequencies (0.002), which are common in Caucasians. On the other hand, the frequency of the IL6-572 G--> C*C allele was much higher (0.27) than that in Caucasian populations (<0.07). One of the IL6 promoter SNPs, viz., IL6-572 G--> C, showed significant associations with bone mineral density (BMD), i.e., the C allele was associated with increased BMD ( P=0.02, co-dominant model; P=0.007, dominant model). The mean BMD was highest in homozygous C individuals (0.67+/-0.15), lowest in homozygous G individuals (0.58+/-0.19), and intermediate in heterozygotes (0.64+/-0.21). In the present study, we describe a variant in the IL6 promoter region that shows positive association with higher BMD in a gene-dose-dependent manner in pre-menopausal women.

Synergistic effect of -174 G/C polymorphism of the interleukin-6 gene promoter and 469 E/K polymorphism of the intercellular adhesion molecule-1 gene in Italian patients with history of ischemic stroke

BACKGROUND AND PURPOSE

Interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1) are involved in the pathogenetic mechanisms responsible for several ischemic cardiovascular disorders, including cerebral ischemia. IL-6 and ICAM-1 plasma levels and/or function may be genetically influenced. We sought to evaluate distribution and reciprocal interaction of IL-6 G/C gene promoter polymorphism and ICAM-1 E/K gene polymorphism in Italian patients with history of ischemic stroke.

METHODS

One hundred nineteen patients with history of ischemic stroke and 133 age- and sex-matched controls were studied. IL-6 and ICAM-1 genotypes were evaluated by polymerase chain reaction and restriction enzyme analysis.

RESULTS

The GG genotype of -174 IL-6 G/C gene polymorphism was significantly associated with history of ischemic stroke at both univariate (P<0.0001) and multivariate analysis (odds ratio [OR], 8.6; P<0.0001). Additionally, the EE genotype of ICAM-1 E/K gene polymorphism was significantly more common in the group of patients with history of ischemic stroke (P=0.003) and was an independent variable associated with stroke history (OR, 4.0; P=0.002). Interestingly, a further increased risk of stroke was found in subjects who concomitantly carry the IL-6 GG and ICAM-1 EE genotypes (IL-6 GG/ICAM-1 EE double-homozygous subjects) (OR, 10.1; P=0.004).

CONCLUSIONS

There is a synergistic effect of IL-6 G/C and ICAM-1 E/K gene polymorphisms in patients with stroke history. Reciprocal interactions between genotypes may contribute in determining the risk profile for cardiovascular diseases and may merit further investigation as potential therapeutic targets.

The -174 G/C polymorphism of the interleukin-6 gene promoter is associated with Alzheimer's disease in an Italian population [corrected]

Interleukin-6 (IL-6) is a multifunctional cytokine playing a crucial role in inflammation and tissue injury. A role for this molecule in neurodegeneration and Alzheimer's disease (AD) has been proposed. The aim of this study was to evaluate the association between a common polymorphism of the IL-6 gene promoter and AD in the Italian population. We found that the frequency of the GG genotype was significantly higher in AD patients than controls on both univariate ( rho< 0.0001) and multivariate analysis ( rho< 0.0001). In contrast, the CC genotype seems to be associated with a reduced risk of disease ( rho< 0.0001). Our data indicate that the IL-6 gene polymorphism is associated with AD in Italians and confirm that IL-6 is crucial in the pathophysiology of neurodegenerative disorders.

The -174 G/C polymorphism of the interleukin-6 gene promoter is associated with peripheral artery occlusive disease

OBJECTIVE AND DESIGN

high plasma levels of Interleukin-6 (IL-6) are found in patients with atherosclerotic disorders. Recently, a common polymorphism of the IL-6 gene promoter, influencing the transcription rate of the gene, has been described and associated with atherosclerosis of carotid and coronary arteries. The objective of this study was to test whether IL-6 gene promoter polymorphism is associated with peripheral artery occlusive disease (PAOD) in a case-control study.

METHODS

IL-6 gene promoter polymorphism was evaluated by polymerase chain reaction followed by restriction enzyme analysis in 84 patients affected by PAOD and 183 controls.

RESULTS

the distribution of IL-6 genotypes was: patients with PAOD: 44 GG, 30 GC, 10 CC; control subjects: 53 GG, 80 GC, 50 CC. The GG genotype was significantly more common in the PAOD group (p<0.0001), while the CC genotype was significantly more common in control patients (p=0.005).

CONCLUSIONS

this study indicates a strong association between IL-6 gene polymorphism and PAOD and support the hypothesis that IL-6 and IL-6 gene polymorphism are important in the pathophysiology and evolution of ischaemic diseases of the lower limbs.

The -174 G/C polymorphism of the interleukin-6 gene promoter and essential hypertension in an elderly Italian population

Several studies have proposed a relationship between blood pressure and inflammation. Interleukin-6 (IL-6) is a multifunctional cytokine involved in inflammation and tissue injury and potentially influencing blood pressure. Recently, a common polymorphism of the IL-6 gene, associated with differences in the transcription rate of the protein, has been described. The aim of this study was to investigate a possible association between genetic variations of the -174GC polymorphism of the IL-6 gene promoter and hypertension in humans. IL-6 gene promoter polymorphism was evaluated by polymerase chain reaction followed by restriction enzyme analysis in 210 elderly Italian patients affected by essential hypertension (EH) and 177 age- and sex-matched controls. The distribution of IL-6 genotypes was 85 GG, 88 GC, 37 CC in the hypertensive patients and 65 GG, 73 GC, 39 CC in the control subjects. In this elderly cohort, no statistically significant association was found between the two groups (P = 0.45 for GG homozygous, P = 0.89 for GC heterozygous and P = 0.27 for CC homozygous). In conclusion the -174 GC polymorphism of the IL-6 gene promoter is not a marker for EH in this sample of elderly Italians.

-174 G/C interleukin-6 gene polymorphism and increased risk of multi-infarct dementia: a case-control study

The aim of this study was to evaluate the association between the -174 G/C polymorphism of interleukin-6 (IL-6) gene promoter and multi-infarct dementia (MID). We studied a group of 122 patients affected by MID and 134 age- and sex-matched controls and evaluated classical risk factors for MID, as well as the distribution of IL-6 alleles and genotypes by polymerase chain reaction and restriction enzyme analysis. The distribution of IL-6 genotypes was 63 GG, 47 GC, 12 CC in patients with MID and 29 GG, 58 GC, 47 CC in control subjects. The GG genotype was significantly more common in the MID group (P<0.0001), while the CC genotype was more common in control patients (P<0.0001). Logistic regression analysis indicated that the presence of GG genotype significantly increases the risk of MID (odds ratio 9.1 [3.1-26.1], P<0.0001). This study indicates a strong association between the -174 G/C polymorphism of the IL-6 gene and MID. Our data support the hypothesis that IL-6 and inflammatory mechanisms are important in the pathophysiology of the vascular changes responsible for cognitive deterioration.

Effect of IL-6 polymorphism on risk of Alzheimer disease: genotype-phenotype association study in Japanese cases

Interleukin-6 (IL-6), an inflammatory cytokine might be involved in the pathophysiology of Alzheimer disease (AD); several studies have reported that the "C allele of IL-6 variable number of tandem repeat polymorphism" (IL-6vntr) delayed initial onset of AD and also decreased its risk per se. Another polymorphism, G/C allele of IL-6 gene promoter region (IL-6prom), is also a candidate because it has an influence on the regulation of plasma IL-6 concentration. We examined these IL-6 polymorphisms in 128 Japanese AD cases and 83 control cases using a PCR-RFLP method. The results showed the frequency of the IL-6prom G allele was significantly increased in AD, although IL-6vntr polymorphism was not. Plasma IL-6 concentration of the AD cases was also significantly higher than that of the control cases. Moreover, the IL-6prom G allele-positive AD patients showed a tendency to have higher IL-6 concentration in the AD group. These findings suggest that the IL-6prom G allele which may affect plasma IL-6 concentration might be a risk factor for sporadic AD in Japanese.

The G to C polymorphism at -174 of the interleukin-6 gene is rare in a Southern Chinese population

Interleukin-6 is thought to be involved in the pathogenesis of coal workers' pneumoconiosis. Recently, a functional G to C polymorphism at position -174 of the promoter of the IL-6 gene has been described. We examined the -174 polymorphisms in 259 retired Chinese men from Guangxi province (all retired coal miners). Only one GC heterozygous and no CC homozygous variants were found. Our results suggest that the frequency of the C allele in this Chinese population is lower than in Caucasian and east Indian populations.

The -174/-597 promoter polymorphisms in the interleukin-6 gene are not associated with susceptibility to multiple sclerosis

Interleukin-6 (IL-6) has been implicated in the etiology of experimental autoimmune encephalomyelitis (EAE) in transgenic animals and contributes to neuropathology in humans. A single nucleotide polymorphism (SNP) at position -174 in the IL-6 gene promoter (IL-6pr) appears to influence IL-6 expression. Complete linkage disequilibrium was observed between the -174 and the -597 alleles. The aim of this study was to investigate the possible influence of -174/-597 IL-6pr polymorphisms on susceptibility to multiple sclerosis (MS). Genotyping of the -597 variant was performed by an RFLP method in 131 MS patients [88 relapsing-remitting (RR-MS), 43 secondary progressive (SP-MS)] and 157 healthy subjects. No differences were found between MS patients and controls with respect to the distribution of -597 IL-6pr genotypes. Neither was found when genotypes were analyzed according to the clinical course of the disease (RR-MS or SP-MS). Future studies focusing on complex transcriptional interactions between the IL-6pr and 3' flanking region polymorphic sites will be necessary to determine the IL-6 haplotype influence on susceptibility to MS.

Immunological aspects of alzheimer's disease: therapeutic implications

Alzheimer's disease (AD) is a chronic neurodegenerative disease causing progressive impairment of memory and cognitive function. The amyloid cascade hypothesis suggests that mismetabolism of the beta-amyloid (A beta) precursor protein (APP) followed by subsequent formation of non-fibrillar and fibrillar A beta deposits leads to glial activation and eventually to neurotoxicity, causing cognitive impairment. Several lines of evidence indicate that an inflammatory process contributes to the pathology of AD. First, inflammatory proteins have been identified as being associated with neuritic plaques and in glial cells surrounding these plaques. Second, certain polymorphisms of acute-phase proteins and cytokines associated with AD plaques increase the risk or predispose for earlier onset of developing AD. Third, epidemiological studies indicate that anti-inflammatory drugs can retard the development of AD. Several steps in the pathological cascade of AD have been identified as possible targets for actions of nonsteroidal anti-inflammatory drugs. For instance, microglia are considered a target because this cell type is closely involved in AD pathology through secretion of neurotoxic substances and by modulating a positive feedback loop of the inflammatory mechanism that may be involved in the pathological cascade in AD. On the basis of studies in APP transgenic mice, immunisation with A beta was recently suggested as a novel immunological approach for the treatment of AD. Immunisation elicits A beta-specific antibodies that could affect several early steps of the amyloid-driven cascade. Antibodies could prevent A beta from aggregating into fibrils and accelerate clearance of A beta by stimulating its removal by microglial cells. This review outlines the pathological and genetic evidence that an inflammatory mechanism is involved in AD and the therapeutic approaches based on inhibition or mediation of inflammation.

Neuroinflammation and the genetics of Alzheimer's disease: the search for a pro-inflammatory phenotype

The role of interleukin 1 (IL-1) and interleukin 6 (IL-6) in the pathogenesis of Alzheimer's disease (AD) is reviewed within the framework of "inflamm-aging", i.e., the characteristic chronic pro-inflammatory status which develops in old age, and neuroinflammation, i.e., the peculiar inflammatory process which is present in the brain of AD patients. In particular, the data suggesting that several IL-1 and IL-6 gene polymorphisms can contribute to the risk of developing AD are reviewed. The possibility as well as the difficulty in identifying a pro-inflammatory phenotype, and its importance for the prevention, diagnosis and therapy of AD and other age-related pathologies are discussed.

Genetic polymorphisms in the cathespin D and interleukin-6 genes and the risk of Alzheimer's disease

Alzheimer's disease (AD) is a complex multi-factorial disease with the involvement of several possible genes. The apolipoprotein E*4 (APOE*4) allele of the known susceptibility gene, APOE, is neither necessary nor sufficient to cause AD. This has prompted the search for other candidate genes associated with the risk of AD. Cathepsin D (Cat D) is an intracellular aspartyl protease that has been reported to have in vitro beta and gamma-secretase activity. The presence of a C-->T (Ala-->Val) polymorphism in exon 2 of the Cat D gene has been reported to be associated with an increased risk of AD. Further, as inflammation is reported to play a prominent role is AD pathogenesis, IL-6, a known mediator of inflammation, is another candidate gene proposed to be associated with the risk of AD. Genetic variation in the IL-6 gene has been reported to be associated with the risk of AD. We performed a genetic screening of sporadic, late-onset AD cases and age-matched controls to evaluate the role of Cat D and IL-6 polymorphisms in AD. Our data indicate no significant association between these polymorphisms and the risk of AD. When the data were stratified by APOE*4 status, no significant difference was seen either between cases and controls. These data suggest that the Cat D and IL-6 polymorphisms do not significantly alter the risk of AD in our case-control cohort.