Functional promoter region polymorphism of the proinflammatory chemokine IL-8 gene associates with Parkinson's disease in the Irish

Quantitative and causal analysis for inflammatory genes and the risk of Parkinson's disease

Background

The dysfunction of immune system and inflammation contribute to the Parkinson's disease (PD) pathogenesis. Cytokines, oxidative stress, neurotoxin and metabolism associated enzymes participate in neuroinflammation in PD and the genes involved in them have been reported to be associated with the risk of PD. In our study, we performed a quantitative and causal analysis of the relationship between inflammatory genes and PD risk.

Methods

Standard process was performed for quantitative analysis. Allele model (AM) was used as primary outcome analysis and dominant model (DM) and recessive model (RM) were applied to do the secondary analysis. Then, for those genes significantly associated with the risk of PD, we used the published GWAS summary statistics for Mendelian Randomization (MR) to test the causal analysis between them.

Results

We included 36 variants in 18 genes for final pooled analysis. As a result, IL-6 rs1800795, TNF-α rs1799964, PON1 rs854560, CYP2D6 rs3892097, HLA-DRB rs660895, BST1 rs11931532, CCDC62 rs12817488 polymorphisms were associated with the risk of PD statistically with the ORs ranged from 0.66 to 3.19 while variants in IL-1α, IL-1β, IL-10, MnSOD, NFE2L2, CYP2E1, NOS1, NAT2, ABCB1, HFE and MTHFR were not related to the risk of PD. Besides, we observed that increasing ADP-ribosyl cyclase (coded by BST1) had causal effect on higher PD risk (OR[95%CI] =1.16[1.10-1.22]) while PON1(coded by PON1) shown probably protective effect on PD risk (OR[95%CI] =0.81[0.66-0.99]).

Conclusion

Several polymorphisms from inflammatory genes of IL-6, TNF-α, PON1, CYP2D6, HLA-DRB, BST1, CCDC62 were statistically associated with the susceptibility of PD, and with evidence of causal relationships for ADP-ribosyl cyclase and PON1 on PD risk, which may help understand the mechanisms and pathways underlying PD pathogenesis.

Evaluation of interleukin 8 polymorphisms (-251T/A and +781C/T) in patients with hepatocellular carcinoma: a meta-analysis

Aim of the study

We reported the association between interleukin 8 (IL-8) polymorphisms (-251T/A and +781C/T) and hepatocellular carcinoma (HCC) risk in a meta-analysis.

Material and methods

Scopus, PubMed, Web of Science, and Cochrane Library databases were searched until 21 November 2020. The analyses were performed by RevMan 5.3 software using odds ratios (ORs) and 95% confidence intervals (CIs). Also, the analysis of publication bias was performed by CMA 2.0 software.

Results

Searching databases/sources, five articles including ten studies were entered into the meta-analysis. The pooled ORs for -251T/A polymorphism were 1.07 (p = 0.55), 1.04 (p = 0.75), 1.31 (p = 0.24), 1.24 (p = 0.31), and 1.85 (p = 0.29) for allele, homozygote, heterozygote, recessive and dominant models, respectively. With regards to +781C/T polymorphism, the pooled ORs were 0.74 (p = 0.07), 0.53 (p = 0.03), 0.83 (p = 0.41), 0.75 (p = 0.19), and 0.57 (p = 0.02) for allele, homozygote, heterozygote, recessive, and dominant models, respectively.

Conclusions

The findings of the meta-analysis showed a lack of significant association between IL-8 (-251T/A) polymorphism and the HCC risk, whereas the TT genotype of IL-8 (+781C/T) polymorphism had a protective role in HCC.

Polymorphisms of Interleukin-6 and Interleukin-8 Are Not Associated with Parkinson's Disease in Taiwan

Background: Studies have suggested that cytokines are crucial mediators in the pathogenesis of Parkinson’s disease (PD). The multifunctional cytokine interleukin (IL)-6 and its single nucleotide polymorphisms (SNPs) were found to have an impact on the development of PD. However, different studies in associations of IL-6 genetic variants with PD showed inconsistent results and it has never been explored in a Taiwanese population. Both IL-1α and IL-8 contribute to the same inflammation pathway. IL-1α genetic polymorphism has an effect on late-onset PD in Taiwan, whereas the associations of IL-8 genetic variants with PD in Taiwan remain to be investigated. Methods: This study examined the frequencies of polymorphisms within the critical promoter areas of the proinflammatory cytokine genes: IL-6 G-174C (rs1800795) and IL-8 A-251T (rs4073) in Taiwanese PD patients compared with age-and gender-matched healthy subjects. Comparisons were also made in genotype and allele frequencies of IL-6 G-174C (rs1800795) and IL-8 A-251T (rs4073) among different populations in previous studies. Results: In total, 1120 subjects, including 509 PD patients (female/male: 259/250) and 511 control subjects (female/male: 252/259), were recruited. We found no statistically significant differences in IL-6 G-174C (rs1800795) or IL-8 A-251T (rs4073) genotypic and allelic distribution between PD and controls, even after being stratified by age at onset and gender. Conclusions: The results did not demonstrate any association of IL-6 G-174C (rs1800795) or IL-8 A-251T (rs4073) with PD in a Taiwanese population. Despite the negative results, this is the first study in associations of IL-6 G-174C (rs1800795) and IL-8 A-251T (rs4073) with PD in Taiwan. The relevance of genetic variants of IL-6 G-174C (rs1800795) or IL-8 A-251T (rs4073) on PD susceptibility warrants further investigation.

Parkinson disease and the immune system - associations, mechanisms and therapeutics

Multiple lines of evidence indicate that immune system dysfunction has a role in Parkinson disease (PD); this evidence includes clinical and genetic associations between autoimmune disease and PD, impaired cellular and humoral immune responses in PD, imaging evidence of inflammatory cell activation and evidence of immune dysregulation in experimental models of PD. However, the mechanisms that link the immune system with PD remain unclear, and the temporal relationships of innate and adaptive immune responses with neurodegeneration are unknown. Despite these challenges, our current knowledge provides opportunities to develop immune-targeted therapeutic strategies for testing in PD, and clinical studies of some approaches are under way. In this Review, we provide an overview of the clinical observations, preclinical experiments and clinical studies that provide evidence for involvement of the immune system in PD and that help to define the nature of this association. We consider autoimmune mechanisms, central and peripheral inflammatory mechanisms and immunogenetic factors. We also discuss the use of this knowledge to develop immune-based therapeutic approaches, including immunotherapy that targets α-synuclein and the targeting of immune mediators such as inflammasomes. We also consider future research and clinical trials necessary to maximize the potential of targeting the immune system.

Inflammation-related gene polymorphisms associated with Parkinson’s disease: an updated meta-analysis

Background

Strong evidence supports the involvement of inflammation processes in the development and progression of Parkinson’s disease (PD), where increasingly correlations have been identified between genetic variations in inflammation-related genes and PD. However, data varies between studies. Therefore, we conducted a meta-analysis to clarify associations between inflammation-related gene polymorphisms and PD risk.

Methods

All studies were identified through online databases. Pooled and stratified groups based on racial descent were assembled to evaluate associations between polymorphisms and PD.

Results

The pooled results showed that protective effects for PD were observed for (1) IL-1α -889 C/T in Asian populations (T vs. C, OR = 0.831, P = 0.031; TT + CT vs. CC, OR = 0.827, P = 0.049); (2) IL-6 -176 G/C in Caucasian populations (CC + GC vs. GG, OR = 0.656, P = 0.000; GC vs. GG, OR = 0.673, P = 0.000); (3) IL-8 -251 A/T (T vs. A, OR = 0.812, P = 0.041; TT vs. AT + AA, OR = 0.663, P = 0.012), particularly in Caucasian populations (TT vs. AT + AA, OR = 0.639, P = 0.010); (4) IL-10 -819 T/C (C vs. T, OR = 0.742, P = 0.034); (5) IL-18 -607 C/A (AA + CA vs. CC, OR = 0.597, P = 0.015; CA vs. CC, OR = 0.534, P = 0.005), and (6) CCR2 +190 G/A (AA vs. GA + GG, OR = 0.552, P = 0.018; AA vs. GG; OR = 0.554; 95% CI 0.336–0.914, P = 0.005). An increased risk of PD was associated with IL-10 -1082 G/A in Asian populations (A vs. G, OR = 1.731, P = 0.000; AA + GA vs. GG, OR = 1.910, P = 0.000). No significant associations with PD were observed for polymorphisms in IL-1β -511 C/T, IL-10 -592 C/A, IL-18 -137 G/C, TNFα -863 C/A, TNFα -857 C/T, TNFα -308 G/A, IFNΥ +874 T/A, and MCP1/CCL2 +2518 A/G.

Conclusions

We suggest that IL-1α -889, IL-6 -176, IL-8 -251, IL-10 -1082, IL-10 -819, IL-18 -607, and CCR2 +190 polymorphisms may be associated with PD risk; however, further studies must verify these conclusions.

Interleukin-18 promoter polymorphisms and idiopathic Parkinson disease: an Egyptian study

Etiology of sporadic Parkinson's disease (PD) is largely unknown. The contribution of genetic factors to the pathogenesis of PD is supported by the demonstration of high concordance in twins, increased risk among relatives of PD patients and existence of familial cases. This study aimed to examine the relation between interleukin 18 (IL-18) gene promoter polymorphisms and idiopathic PD, and its impact on clinical presentation and disease severity. 30 idiopathic PD patients and 15 age- and sex-matched healthy subjects were included. Disease severity was assessed using Unified Parkinson's Disease Rating Scale (UPDRS). Genetic testing for IL-18 gene promoter -607C/A single nucleotide polymorphisms (SNP) was done using real-time polymerase chain reaction (PCR) technique. A raised risk of PD development was found in patients with A/C and C/C genotypes of the site -607C/A (odds ratios = 1.83 and 1.98, respectively). The distribution of the genotypes showed no significant relation to gender or predominant clinical presentation. The age at onset of disease was significantly lower in C/C and A/A genotypes compared to A/C genotype (p = 0.001 and 0.04, respectively). Patients with A/A genotype showed significantly higher mentation score of UPDRS compared to patients with A/C and C/C genotypes (p = 0.003 and p = 0.002, respectively). Polymorphisms of IL-18 gene promoter increase the risk of developing idiopathic PD. The polymorphisms may affect phenotypic expression rather than being a direct cause of idiopathic PD.

Role of chemokines in Parkinson's disease

Parkinson's disease (PD) is a chronic progressive neurodegenerative disorder with an increasing incidence year by year, particularly as the population ages. The most common neuropathologic manifestation in patients with Parkinson's disease is dopamine neurons degeneration and loss in substantia nigra of middle brain. The main neurochemistry problem is the lack of the neurotransmitter dopamine. Clinically, PD patients may also have higher levels of glutamate, gamma-aminobutyric acid, acetylcholine and other neurotransmitters. At present, many data have shown that some chemokines are involved in regulating the release and transmission of neurotransmitters, and the growth and development of related neurons. In recent years, most of the studies relative to PD is based on immune and inflammatory mechanisms, and chemokines is also the focus on this mechanism. Chemokines are a class of cytokines that have definite chemotaxis effects on the different target cells. They might be involved in the pathogenesis of PD by inducing neuronal apoptosis and microglia activation. Clinical data has shown that the levels of chemokines in plasma and cerebrospinal fluid of PD patients have corresponding changes compared with the healthy persons. This review summarizes recent studies on chemokines and their receptors in Parkinson's disease: (i) to explore the role of chemokines in Parkinson's disease; (ii) to provide new indicators for clinical diagnosis of PD; (iii) to provide new targets for drug research and development in the treatment of Parkinson's disease.

A Case-Control Association Study of RANTES (-28C>G) Polymorphism as a Risk Factor for Parkinson's Disease in Isparta, Turkey

Background. Recent studies have revealed that inflammatory processes are involved in the pathogenesis of Parkinson's disease (PD). Multiple lines of evidence have suggested that chemokines and their receptors are involved in several neurodegenerative disorders. We have examined whether genetic polymorphisms at the genes encoding chemokines IL-8 (-251A>T), MCP-1 (-2518A/G), and RANTES (-28C>G) and chemokine receptors CCR2 (V64I) and CCR5 (-Δ32) were associated with sporadic PD risk in Isparta, Turkey. Method. The pilot case-control association study included 30 PD patients and 60 control subjects, who were all genotyped with PCR-RFLP for the five polymorphisms. Their genotype and haplotype frequencies were compared statistically. Results. One SNP (-28C>G) in RANTES revealed a significant association with PD (P (allele) < 0.0001, p-trend = 0.0007). The risk allele (G) in the homozygous and dominant models (OR = 17.29 and 32.10, 95% CI = 0.86-347.24 and 1.74-591.937, resp.) suggests additional PD risk. The haplotype TGCAN from the IL-8 (-251A>T), MCP-1 (-2518A>G), RANTES (-28C>G), CCR-2 (V64I), and CCR-5 (-Δ32) has protective effect (OR = 0.08 [CI = 0.01-0.63], p = 0.019). Conclusions. Our data are the first indication of the role of RANTES (-28C>G) in PD risk.

An investigation of polymorphisms in the 4q13.3-21.1 CXC chemokine gene cluster for association with multiple sclerosis in Australians

Susceptibility to multiple sclerosis (MS) is believed to result from the complex interaction of a number of genes, each with modest effect. Vital to the migration of cells to sites of inflammation, including the central nervous system, are chemokines, many of which are implicated in MS pathogenesis. Most of the CXC chemokine genes are encoded in a cluster on chromosome 4q13.3-21.1, which has been identified in several genome-wide screens as being potentially associated with MS. We conducted a two-stage analysis to investigate the chemokine gene cluster for association with MS. Initially, we sequenced the chemokine genes in several DNA pools to identify common polymorphisms, and then genotyped selected SNPs in 373 Australian MS trio families. We found no evidence that the CXC chemokine gene cluster is genetically associated with MS. However, the existence of common variants conferring small risk factors or rare variants with significant risk cannot be excluded.

Association of polymorphisms in interleukin-8 gene with cancer risk: a meta-analysis of 22 case-control studies

Interleukin-8 (IL-8) is a kind of chemokine that plays an important role in the development and progression of many human malignancies. Previous studies have uncovered that polymorphisms in IL-8 is associated with the risk of many cancer types, but the results were inconsistent and inconclusive. In the present study, we aimed to explore the roles of IL-8 polymorphisms (rs2227307, rs2227306, +678T/C, rs1126647, and +1633C/T) and cancer risk through a systematic review and meta-analysis. Potential source of heterogeneity was sought out through sensitivity analysis. Desirable data were extracted and registered into databases. Finally, a total of ten publications comprising of 22 case–control studies, including 4,259 cases and 7,006 controls were ultimately eligible for the meta-analysis. No significant association was uncovered for all the five polymorphisms and the overall cancer risk. However, in the stratification analysis by cancer type, a significantly decreased risk of hepatocellular carcinoma was identified for rs2227306 polymorphism (T vs C: odds ratio [OR] =0.721, 95% confidence interval [CI] =0.567–0.916, P_z=0.007; TT vs CC: OR =0.447, 95% CI =0.274–0.728, P_z=0.001; TT vs TC + CC: OR =0.480, 95% CI =0.304–0.760, P_z=0.002). In conclusion, our data shows that rs2227306 polymorphism plays a protective role in hepatocellular carcinoma risk. Future well-designed studies with a larger sample size are warranted to verify our findings.

Role of α-synuclein in inducing innate and adaptive immunity in Parkinson disease

Alpha-synuclein (α-syn) is central to the pathogenesis of Parkinson disease (PD). Gene duplications, triplications and point mutations in SNCA1, the gene encoding α-syn, cause autosomal dominant forms of PD. Aggregated and post-translationally modified forms of α-syn are present in Lewy bodies and Lewy neurites in both sporadic and familial PD, and recent work has emphasized the prion-like ability of aggregated α-syn to produce spreading pathology. Accumulation of abnormal forms of α-syn is a trigger for PD, but recent evidence suggests that much of the downstream neurodegeneration may result from inflammatory responses. Components of both the innate and adaptive immune systems are activated in PD, and influencing interactions between innate and adaptive immune components has been shown to modify the pathological process in animal models of PD. Understanding the relationship between α-syn and subsequent inflammation may reveal novel targets for neuroprotective interventions. In this review, we examine the role of α-syn and modified forms of this protein in the initiation of innate and adaptive immune responses.

Cognitive Status Correlates with CXCL10/IP-10 Levels in Parkinson's Disease

Cognitive impairment and depressive symptoms are of great interest in Parkinson's disease (PD), since they are very common and lead to increased disability with poor quality of life. Inflammatory mechanisms have been implicated in PD and its nonmotor symptoms. In the current pilot study, we aimed to evaluate plasma levels of chemokines in PD patients and to analyze the putative association of chemokines with depressive symptoms and cognitive performance. We hypothesized that higher chemokines levels are associated with worse cognitive performance and increased depressive symptoms in PD. For this purpose, 40 PD patients and 25 age- and gender-matched controls were subjected to a clinical evaluation including cognitive and mood tests. Peripheral blood was drawn and plasma levels of CCL2/MCP-1, CCL11/eotaxin, CCL24/eotaxin-2, and CXCL10/IP-10 were measured by enzyme-linked immunosorbent assay. PD patients and control individuals presented comparable plasma concentrations of all the evaluated chemokines. In PD patients, CXCL10/IP-10 plasma levels correlated positively with Hoehn and Yahr staging scale. In addition, the higher CXCL10/IP-10 levels, the worse performance on cognitive tests. Although there was no significant difference between PD patients and control individuals regarding chemokines levels, our preliminary results showed that CXCL10/IP-10 may be associated with cognitive status in PD.

Inflammatory response in Parkinson's disease (Review)

Parkinson's disease (PD) is one of the most common age‑related neurodegenerative diseases, which results from a number of environmental and inherited factors. PD is characterized by the slow progressive degeneration of dopaminergic (DA) neurons in the substantia nigra. The nigrostriatal DA neurons are particularly vulnerable to inflammatory attack. Neuroinflammation is an important contributor to the pathogenesis of age‑related neurodegenerative disorders, such as PD, and as such anti‑inflammatory agents are becoming a novel therapeutic focus. This review will discuss the current knowledge regarding inflammation and review the roles of intracellular inflammatory signaling pathways, which are specific inflammatory mediators in PD. Finally, possible therapeutic strategies are proposed, which may downregulate inflammatory processes and inhibit the progression of PD.

Association of NQO1 and TNF polymorphisms with Parkinson's disease: A meta-analysis of 15 genetic association studies

Parkinson's disease (PD) is a neurodegenerative movement d'isorder that affects ~2% of the population aged ≥65 years. NAD(P)H-quinone oxidoreductase 1 (NQO1) and tumor necrosis factor-α (TNF-α) are two important factors in the generation of oxidative stress in PD. The aim of the present study was to assess the association of NQO1 and tumor necrosis factor (TNF) polymorphisms with PD. A meta-analysis was performed that included data from 15 studies comprising 2,858 patients and 2,907 healthy controls. The results showed that TNF-1031 (rs1799964) was significantly associated with PD in the recessive [P=0.0005; odds ratio (OR), 3.19; 95% confidence interval (CI), 1.66-6.13] and additive models (P=0.0006; OR, 3.15; 95% CI, 1.63-3.51). However, there was no significant association in NQO1 C609T (rs1800566) and TNF-308 (rs1800629) with PD. To the best of our knowledge, the present study is the first meta-analysis of NQO1 and TNF polymorphisms with PD demonstrating that TNF-1031 polymorphism may be a risk factor for PD under either the recessive or additive models. However, the meta-analyses did not support the involvement of NQO1 C609T and TNF-308 in the risk of PD.

[Hepatic involvement in hereditary alpha-1-antitrypsin deficiency]

Apha-1-antitrypsin deficiency is an autosomal recessive genetic disorder seen in all races. The molecular defect is a specific mutation of the SERPINA1 gene leading to synthesis of an abnormal protein (alpha-1-antitrypsin Z) that cannot be secreted and polymerizes in the endoplasmic reticulum of hepatocytes. The inter-individual variability in the responses to intracellular stress induced by the accumulation of abnormal polymers and the mechanisms allowing their degradation is, without doubt, responsible for the different clinical manifestations of the disease. The disease affects the liver where the abnormal protein is synthesized and the lung, which is its place of action. Liver involvement is well recognized in homozygous infants of the phenotype ZZ. In this situation the disease may present a varying picture from neonatal cholestasis (about 15% of neonatal defects) to cirrhosis. However, evolution towards cirrhosis affects less than 3% of infants with the ZZ phenotype and it is preceded in 80% of cases by neonatal cholestasis. In adolescents or adults the manifestations associated with alpha-1-antitrypsin deficiency are usually limited to biochemical abnormalities but may lead to cirrhosis or hepatocellular carcinoma. The hepatic disorder and its complications are treated symptomatically though the pulmonary involvement may benefit from substitution treatment. More specific treatments targeting the molecular and cellular abnormalities are the subject of research.

Association of interleukin-8 gene polymorphisms with the risk of hepatocellular carcinoma

Interleukin-8 (IL8) polymorphisms have been implicated in several cancers, but their roles in the pathogenesis of hepatocellular carcinoma (HCC) are largely unknown. The present study was designed to explore the association between IL8 polymorphism and the risk of HCC in a Chinese population. Four single nucleotide polymorphisms (SNPs) of the IL8 gene -251A/T, +781C/T, -353A/T and +678T/C were analyzed in 205 HCC patients and 208 healthy controls in a Chinese population. Serum levels of IL8 were detected in HCC patients and healthy controls. The association between IL8 polymorphisms and HCC risk was measured using the adjusted odds ratios (OR) and their 95% confidence intervals (CI) from multiple logistic regression analysis. Haplotype analysis and gene-environment interaction analysis was also performed. The serum level of IL8 was significantly higher in HCC patients compared with healthy controls (P < 0.001). After adjusting for confounding factors, no significant associations were found between -251A/T, +781C/T, -353A/T and +678T/C and HCC risk (all P > 0.05). Haplotype analysis showed that A(251)-C(781)-A(353)-C(678) conferred decreased risk of HCC onset (adjusted OR 0.31, 95% CI 0.13-0.77). No significant interaction effects were found between the four SNPs and HBV infection, cirrhosis, gender smoking and alcohol consumption (all P > 0.05). No association between -251A/T, +781C/T, -353A/T and +678T/C of the IL8 gene and the risk of HCC was found in this Chinese population, and the SNPs did not display any interaction with several environmental factors with regard to HCC risk. However, it appears that A(251)-C(781)-A(353)-C(678) is perhaps a protective haplotype for HCC.

The role of inflammation in sporadic and familial Parkinson's disease

The etiology of Parkinson's disease (PD) is complex and most likely involves numerous environmental and heritable risk factors. Interestingly, many genetic variants, which have been linked to familial forms of PD or identified as strong risk factors, also play a critical role in modulating inflammatory responses. There has been considerable debate in the field as to whether inflammation is a driving force in neurodegeneration or simply represents a response to neuronal death. One emerging hypothesis is that inflammation plays a critical role in the early phases of neurodegeneration. In this review, we will discuss emerging aspects of both innate and adaptive immunity in the context of the pathogenesis of PD. We will highlight recent data from genetic and functional studies that strongly support the theory that genetic susceptibility plays an important role in modulating immune pathways and inflammatory reactions, which may precede and initiate neuronal dysfunction and subsequent neurodegeneration. A detailed understanding of such cellular and molecular inflammatory pathways is crucial to uncover pathogenic mechanisms linking sporadic and hereditary PD and devise tailored neuroprotective interventions.

Neuroimmunological processes in Parkinson's disease and their relation to α-synuclein: microglia as the referee between neuronal processes and peripheral immunity

The role of neuroinflammation and the adaptive immune system in PD (Parkinson's disease) has been the subject of intense investigation in recent years, both in animal models of parkinsonism and in post-mortem PD brains. However, how these processes relate to and modulate α-syn (α-synuclein) pathology and microglia activation is still poorly understood. Specifically, how the peripheral immune system interacts, regulates and/or is induced by neuroinflammatory processes taking place during PD is still undetermined. We present herein a comprehensive review of the features and impact that neuroinflamation has on neurodegeneration in different animal models of nigral cell death, how this neuroinflammation relates to microglia activation and the way microglia respond to α-syn in vivo. We also discuss a possible role for the peripheral immune system in animal models of parkinsonism, how these findings relate to the state of microglia activation observed in these animal models and how these findings compare with what has been observed in humans with PD. Together, the available data points to the need for development of dual therapeutic strategies that modulate microglia activation to change not only the way microglia interact with the peripheral immune system, but also to modulate the manner in which microglia respond to encounters with α-syn. Lastly, we discuss the immune-modulatory strategies currently under investigation in animal models of parkinsonism and the degree to which one might expect their outcomes to translate faithfully to a clinical setting.

AA genotype of IL-8 -251A/T is associated with low PaO(2)/FiO(2) in critically ill patients and with increased IL-8 expression

BACKGROUND AND OBJECTIVE

Interleukin-8 (IL-8) is a central chemokine in acute respiratory distress syndrome (ARDS), and the IL-8 gene contains a functional single nucleotide polymorphism (SNP) -251A/T in its promoter region. We hypothesized that IL-8 -251A/T SNP is associated with PaO(2)/FiO(2) in critically ill patients.

METHODS

We conducted genetic-association studies in intensive care units at academic teaching centres using a derivation septic shock cohort (vasopressin and septic shock trial (VASST), n = 467) and a validation post-cardiopulmonary bypass surgery cohort (CPB, n = 739) of Caucasian patients. Patients in both cohorts were genotyped for IL-8 -251A/T. The primary outcome variable in both cohorts was the fraction of patients who had a PaO(2) /FiO(2) < 200. IL-8 mRNA expression was measured in genotyped lymphoblastoid cells in vitro.

RESULTS

The frequency of the patients with PaO(2)/FiO(2) <200 was significantly greater in patients who had the AA genotype of -251A/T than in patients who had the AT or TT genotypes in both VASST (AA = 60.8% vs AT and TT = 53.8% and 48.0%, P = 0.038) and the CPB cohort (AA = 37.0% vs AT and TT = 27.0% and 26.0%, P = 0.039). Patients having the AA genotype had a higher probability to remain on mechanical ventilation (P = 0.047) in the first 14 days. Lymphoblastoid cells having the AA genotype had significantly higher IL-8 mRNA expression than cells having the AT or TT genotype (P = 0.022).

CONCLUSIONS

Critically ill Caucasian patients who had the AA genotype of IL-8 -251A/T had an increased risk of PaO(2)/FiO(2) <200. The AA genotype was associated with greater IL-8 mRNA expression than the AT or TT genotypes.

Cytokine gene polymorphisms and Parkinson's disease: a meta-analysis

BACKGROUND

Cytokines, which are involved in immunological responses, play and important role in the development and progression of Parkinson's disease (PD). The functional polymorphisms identified in cytokine genes are thought to influence PD risk. However the findings of studies investigating the association between cytokine gene polymorphisms and PD risk are still controversial. Therefore, we conducted a meta-analysis, in order to investigate the potential associations between cytokine gene polymorphisms and PD.

METHODS

Studies of PD and cytokine polymorphisms were identified by searches of PubMed and PDGene. Pooled analyses were performed to assess the association between cytokine gene polymorphisms and PD.

RESULTS

Our results indicated a positive association of TNFα -1031 CC genotype in overall analysis(CC vs. TT: OR=3.146; 95%CI: 1.631-6.070, p=0.008; CC vs. CT+TT: OR=3.187: 95%CI: 1.657-6.128,p=0.008), and an Asian subgroup, C variant(OR=1.328; 95%CI: 1.053-1.675, p=0.034) also conveyed an increased PD risk as well as CC genotype ( CC vs. TT: OR=3.207; 95%CI: 1.614-6.373, p=0.004; CC vs. CT+TT: OR=3.238; 95%CI: 1.636-6.410, p=0.004). A decreased risk for PD was associated with IL-6-174C allele (OR=0.761; 95%CI: 0.641-0.903, p=0.008) and IL-1RA VNTR 2 allele(OR=0.641; 95%CI: 0.456-0.826 p=0.004). For the polymorphisms of IL-1β C[-511]T, IL-1α C[-889]T , TNFα G[-308]A, and IL-10 G[-1082]A no significant association was found between the gene polymorphisms and PD risk.

CONCLUSIONS

Our meta-analysis suggested that gene polymorphisms of TNFα -1031, IL-6-174 and IL-1RA VNTR may be associated with PD risk. However, more large well-designed studies will be necessary to validate our findings.

Inflammation in Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disease that is characterized by the degeneration of dopaminergic neurons in the substantia nigra pars compacta. Inflammatory responses manifested by glial reactions, T cell infiltration, and increased expression of inflammatory cytokines, as well as other toxic mediators derived from activated glial cells, are currently recognized as prominent features of PD. The consistent findings obtained by various animal models of PD suggest that neuroinflammation is an important contributor to the pathogenesis of the disease and may further propel the progressive loss of nigral dopaminergic neurons. Furthermore, although it may not be the primary cause of PD, additional epidemiological, genetic, pharmacological, and imaging evidence support the proposal that inflammatory processes in this specific brain region are crucial for disease progression. Recent in vitro studies, however, have suggested that activation of microglia and subsequently astrocytes via mediators released by injured dopaminergic neurons is involved. However, additional in vivo experiments are needed for a deeper understanding of the mechanisms involved in PD pathogenesis. Further insight on the mechanisms of inflammation in PD will help to further develop alternative therapeutic strategies that will specifically and temporally target inflammatory processes without abrogating the potential benefits derived by neuroinflammation, such as tissue restoration.

Gender differences in the IL6 -174G>C and ESR2 1730G>A polymorphisms and the risk of Parkinson's disease

The -174G>C (rs1800795) single nucleotide polymorphism (SNP) in the promoter of the interleukin-6 (IL6) gene and the 1730G>A (rs4986938) SNP in the estrogen receptor beta (ESR2) may influence the risk of Parkinson's disease (PD). We investigated these SNPs in 380 unrelated US Caucasian PD cases and 522 controls, including 452 individuals of Ashkenazi Jewish (AJ) origin (260 PD, 192 controls). The G allele of the -174G>C SNP was more common in AJ PD cases (p=0.033) as well as in Non-Jewish (NJ) men with PD (p=0.022). The GG genotype increased the risk of PD by over two fold in NJ men (OR=2.11, 95%CI: 1.14-3.89, p=0.017), and approached significance in the total AJ group with PD (OR=1.42, 95%CI: 0.97-2.06, p=0.067). The A allele of the ESR2 1730G>A SNP was associated with a decreased risk for PD in AJ women, and in this group, having the AA genotype decreased the risk of PD by half (OR=0.45, 95%CI: 0.22-0.92, p=0.029). Our data supports a role for the IL6 -174G>C G allele in AJ individuals overall. In NJ Caucasians, this role appears to be gender mediated. In both groups, the effect is independent from ESR2 1730G>A. A separate association for the ESR2 1730G>A SNP was found exclusively in women of AJ descent. Other polymorphisms in tight linkage disequilibrium with the SNP differentially influencing expression, ethnic differences in allele distribution, and gender differences in genetic load related to PD, may underlie our findings. Larger studies in diverse populations, including analysis of surrounding regions are recommended.

Lack of association between IL-1β, TNF-α, and IL-10 gene polymorphisms and sporadic Parkinson's disease in an Italian cohort

OBJECTIVE

There is increasing evidence suggesting that neuroinflammation and microglia activation may play important roles in the pathway leading to neuronal cell death in Parkinson's disease (PD). Chronic activation of microglia may cause neuronal damage through the release of potentially cytotoxic molecules, such as pro-inflammatory cytokines. Different functional promoter polymorphisms within genes coding pro- or anti-inflammatory cytokines involved in the immune reactions in the brain might influence the risk of developing PD or the age of disease onset.

AIM

To investigate the interleukin (IL)-1β-511, tumor necrosis factor alpha (TNF-α)-308, and interleukin (IL)-10-1082 gene polymorphisms as susceptibility factors for PD.

METHODS

We analyzed genotype and allele distributions of these polymorphisms in 146 Italian patients with PD and 156 healthy controls.

RESULTS

None of the polymorphisms we investigated was found to be associated with PD or with age of disease onset. No significant differences between patients with PD and controls were found as regards the concomitant presence of variant alleles in the three polymorphisms studied. We found that only the combined genotype TNF-α-308GG/IL-1β-511T+ is associated with a decreased risk of PD.

CONCLUSION

Our results indicate that the cytokine gene polymorphisms we investigated are not related to the development of PD in the Italian population; further studies are warranted to clarify the role of the TNF-α-308GG/IL-1β-511T+ combined genotype.

A promoter SNP rs4073T>A in the common allele of the interleukin 8 gene is associated with the development of idiopathic pulmonary fibrosis via the IL-8 protein enhancing mode

Background

Interleukin-8 (IL-8) is a potent chemo-attractant cytokine responsible for neutrophil infiltration in lungs with idiopathic pulmonary fibrosis (IPF). The IL-8 protein and mRNA expression are increased in the lung with IPF. We evaluated the effect of single nucleotide polymorphisms (SNPs) of the IL-8 gene on the risk of IPF.

Methods

One promoter (rs4073T>A) and two intronic SNPs (rs2227307T>G and rs2227306C>T) of the IL-8 genes were genotyped in 237 subjects with IPF and 456 normal controls. Logistic regression analysis was applied to evaluate the association of these SNPs with IPF. IL-8 in BAL fluids was measured using a quantitative sandwich enzyme immunoassay, and promoter activity was assessed using the luciferase reporter assay.

Results

The minor allele frequencies of rs4073T>A and rs2227307T>G were significantly lower in the 162 subjects with surgical biopsy-proven IPF and 75 subjects with clinical IPF compared with normal controls in the recessive model (OR = 0.46 and 0.48, p = 0.006 and 0.007, respectively). The IL-8 protein concentration in BAL fluids significantly increased in 24 subjects with IPF compared with 14 controls (p = 0.009). Nine IPF subjects homozygous for the rs4073 T>A common allele exhibited higher levels of the IL-8 protein compared with six subjects homozygous for the minor allele (p = 0.024). The luciferase activity of the rs4073T>A common allele was significantly higher than that of the rs4073T>A minor allele (p = 0.002).

Conclusion

The common allele of a promoter SNP, rs4073T>A, may increase susceptibility to the development of IPF via up-regulation of IL-8.

Peripheral inflammation increases the damage in animal models of nigrostriatal dopaminergic neurodegeneration: possible implication in Parkinson's disease incidence

Inflammatory processes described in Parkinson's disease (PD) and its animal models appear to be important in the progression of the pathogenesis, or even a triggering factor. Here we review that peripheral inflammation enhances the degeneration of the nigrostriatal dopaminergic system induced by different insults; different peripheral inflammations have been used, such as IL-1β and the ulcerative colitis model, as well as insults to the dopaminergic system such as 6-hydroxydopamine or lipopolysaccharide. In all cases, an increased loss of dopaminergic neurons was described; inflammation in the substantia nigra increased, displaying a great activation of microglia along with an increase in the production of cytokines such as IL-1β and TNF-α. Increased permeability or disruption of the BBB, with overexpression of the ICAM-1 adhesion molecule and infiltration of circulating monocytes into the substantia nigra, is also involved, since the depletion of circulating monocytes prevents the effects of peripheral inflammation. Data are reviewed in relation to epidemiological studies of PD.

Correlation of polymorphism of IL-8 and MMP-7 with occurrence and lymph node metastasis of early stage cervical cancer

The IL-8 and MMP-7 genes participate in the carcinogenesis of many malignancies, but the role of both genes in cervical cancer is not fully elucidated. The aim of this study was to determine the frequency of IL-8 and MMP-7 gene mutations and to assess their effects on the risk of early stage cervical cancer and lymph node metastasis. The clinical stage and histological grade of cervical cancer were also studied. The peripheral blood from the patients with early stage cervical cancers and normal controls was collected and the DNA was extracted. The incidence of IL-8 and MMP-7 gene mutations was assessed by using tetra-primer amplification refractory mutation system polymerase chain reaction (ARMS PCR) and restriction fragment length polymorphism (RFLP). The data were statistically analyzed by x2 test. The results showed that: (1) The genotype frequency of IL-8 -251AT and TT was significantly higher in the cervical cancer group than in the normal control group (OR=2.290 and 2.619 respectively, P=0.001), and it was also higher in the lymphatic metastasis group than that without metastasis (OR=2.917, P=0.035); (2) The frequency of MMP-7 -181G/G genotype was significantly higher in the cervical cancer group and in the lymphatic metastasis group (P<0.05); (3) The incidence of IL-8 mutation was two times higher in IIa cervical cancer group than in Ib1 and Ib2 cervical cancer group (P=0.006). For the MMP-7 gene, there was statistically significant difference in the incidence of mutation between the Ib1, Ib2 and the IIa (P=0.000); (4) Different histological types and different grades of cervical cancer had different incidence of mutations, statistically. It was suggested that there was significant difference in the genotype of IL-8 -251TT and MMP-7 -181GG polymorphism between the cervical cancer group and the lymph node metastasis group. Moreover, individuals with IL-8 T allele or MMP-7 G allele carriers were at significantly higher risk of cervical cancer, particularly the early (IIa) and medium, poorly differentiated cervical cancer (G2+G3).

Interleukin-6, a mental cytokine

Almost a quarter of a century ago, interleukin-6 (IL-6) was discovered as an inflammatory cytokine involved in B cell differentiation. Today, IL-6 is recognized to be a highly versatile cytokine, with pleiotropic actions not only in immune cells, but also in other cell types, such as cells of the central nervous system (CNS). The first evidence implicating IL-6 in brain-related processes originated from its dysregulated expression in several neurological disorders such as multiple sclerosis, Alzheimer's disease and Parkinson's disease. In addition, IL-6 was shown to be involved in multiple physiological CNS processes such as neuron homeostasis, astrogliogenesis and neuronal differentiation. The molecular mechanisms underlying IL-6 functions in the brain have only recently started to emerge. In this review, an overview of the latest discoveries concerning the actions of IL-6 in the nervous system is provided. The central position of IL-6 in the neuroinflammatory reaction pattern, and more specifically, the role of IL-6 in specific neurodegenerative processes, which accompany Alzheimer's disease, multiple sclerosis and excitotoxicity, are discussed. It is evident that IL-6 has a dichotomic action in the CNS, displaying neurotrophic properties on the one hand, and detrimental actions on the other. This is in agreement with its central role in neuroinflammation, which evolved as a beneficial process, aimed at maintaining tissue homeostasis, but which can become malignant when exaggerated. In this perspective, it is not surprising that 'well-meant' actions of IL-6 are often causing harm instead of leading to recovery.

Polymorphisms of CXCL8 and its receptor CXCR2 contribute to the development and progression of childhood IgA nephropathy

Many studies have suggested that CXCL8 and CXCR2 play an important role in the pathogenesis of several types of renal diseases. However, there is no prior study on the association between polymorphisms of these genes and IgA nephropathy (IgAN), especially in children. The genotyping data from 192 patients with childhood IgAN and 397 controls showed significant differences in the frequencies of the CXCL8 gene with rs2227306 (dominant, P = 0.019; overdominant, P = 0.009), rs2227543 (dominant, P = 0.01; overdominant, P = 0.0057), and rs4073 (codominant, P = 0.034; dominant, P = 0.011; overdominant, P = 0.022). In addition, 2 single-nucleotide polymorphism frequencies of the CXCR2 gene (rs4674257 and rs4674259) significantly differed between the patients with pathologically mild and patients with advanced disease. Further, 5 single-nucleotide polymorphisms of the CXCL8 and CXCR2 genes significantly differed in the patients with infiltration of inflammatory cells on the renal biopsy samples. The results of this study suggest that polymorphisms of CXCL8 are associated with increased susceptibility to IgAN, and polymorphisms of CXCR2 with the pathological progression of childhood IgAN. These genetic variations might provide insight into novel individualized antichemokine regimens for treatment.

Lack of association between interleukin-1 alpha, beta polymorphisms and Parkinson's disease

The associations between interleukin-1 alpha (IL-1alpha-889) and beta (IL-1beta-511) single nucleotide polymorphisms (SNPs) and the risk for Parkinson's disease (PD) are still controversial and ambiguous. The aim of this study was to determine a more precise estimation of the relationship by meta-analysis. We searched databases through March 2010 for all publications on the association between these variations and PD. A total of 11 studies including 2803 PD patients and 2539 healthy controls were identified. The overall and geographic subgroups analysis was conducted, and odds ratios (OR) and 95% confidence intervals (95% CI) were calculated in the fixed- or random-effects model. We found that the overall OR (95% CI) for TT and CT genotypes versus CC genotype for IL-1alpha-889 was 1.01 (0.88-1.16), while the overall OR (95% CI) for TT and CT genotypes versus CC genotype for IL-1beta-511 was 1.19 (0.87-1.62). The sensitivity analysis strengthened our confidence in the validity of these null associations. There was no publication bias observed in this study. To sum up, there were no associations found between the SNPs of IL-1alpha-889, IL-1beta-511 and risk for PD.

Association of interleukin-8 with cachexia from patients with low-third gastric cancer

Background. Interleukin (IL)-8 has been implicated in the development of cancer cachexia. The polymorphism of IL-8 gene, which may affect the production level of IL-8, may be associated with cancer cachexia. Methods. The serum IL-8 level in our study was examined by radioimmunoassay. We also analyzed single nucleotide polymorphisms (SNPs) −251 A/T and +781 C/T of IL-8 gene, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results. The serum levels of IL-8 were significantly elevated in patients with low-third gastric cancer compared with controls, and were further up-regulated in patients with cachexia than those without (Z = −3.134, P = .002). A significantly increased frequency of +781 T allele was noted in patients with cachexia (OR = 2.247, 95% CI: 1.351–3.737, P = .002). The +781 TT genotype was observed to be associated with a significantly increased risk of cachexia (OR = 3.167, 95% CI: 1.265–7.929, P = .011), and with odds ratio of 3.033 (95% CI: 1.065–8.639, P = .038) for cachexia after adjusting for potential confounding factors. Meanwhile, haplotype analysis indicated a borderline positive association between T²⁵¹T⁷⁸¹ haplotype and cachexia as compared with the T²⁵¹C⁷⁸¹ haplotype (OR = 4.92, 95% CI: 1.00–24.28;, P = .053). Conclusions. IL-8 appears to be associated with cachexia from patients with low-third gastric cancer.

Neuroinflammation in Parkinson's disease: a target for neuroprotection?

Parkinson's disease is characterised by a slow and progressive degeneration of dopaminergic neurons in the substantia nigra. Despite intensive research, the cause of the neuronal loss in Parkinson's disease is poorly understood. Neuroinflammatory mechanisms might contribute to the cascade of events leading to neuronal degeneration. In this Review, we describe the evidence for neuroinflammatory processes from post-mortem and in vivo studies in Parkinson's disease. We further identify the cellular and molecular events associated with neuroinflammation that are involved in the degeneration of dopaminergic neurons in animal models of the disease. Overall, available data support the importance of non-cell-autonomous pathological mechanisms in Parkinson's disease, which are mostly mediated by activated glial and peripheral immune cells. This cellular response to neurodegeneration triggers deleterious events (eg, oxidative stress and cytokine-receptor-mediated apoptosis), which might eventually lead to dopaminergic cell death and hence disease progression. Finally, we highlight possible therapeutic strategies (including immunomodulatory drugs and therapeutic immunisation) aimed at downregulating these inflammatory processes that might be important to slow the progression of Parkinson's disease.

Genetic polymorphisms of interleukin 8 and risk of ulcerative colitis in the Chinese population

BACKGROUND

Interleukin-8 (IL-8), a CXC chemokine that recruits and activates inflammatory cells, plays a critical role in the pathogenesis of ulcerative colitis (UC). There are no studies on the association of single nucleotide polymorphisms (SNPs) of the IL-8 gene with the risk of UC.

METHODS

All 162 unrelated UC patients and 203 control subjects were analyzed for 5 IL-8 SNPs ((-845 (T/C), -738 (T/A), -353 (A/T), -251 (T/A) and +678 (T/C)) using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay and PCR-sequence-specific primers (SSP) method. Serum IL-8 concentrations were measured in all subjects.

RESULTS

Individual SNPs were not associated with risk for UC. However, the frequency of -353A/-251A/+678T haplotype was significantly higher in UC patients than in healthy controls (OR=1.454, p=0.036). By subgroup analyses, this haplotype tended to be more common in severe UC patients than in those with mild-to-moderate disease (OR=2.281, p=0.027). Furthermore, patients with AAT diplotype showed significantly increased serum IL-8 concentrations than those with other diplotypes (p<0.001).

CONCLUSION

These results suggest that IL-8 is a novel susceptibility gene to UC in Chinese UC patients, and furthermore, that IL-8 polymorphisms may be related to severe clinical subtype of UC.

Cytokine gene polymorphisms and cytokine levels in pulmonary tuberculosis

Polymorphisms in the cytokine genes are known to influence cytokine levels and may be associated with outcome of infections. We investigated the polymorphisms in the cytokine genes namely IFN-gamma (+874 and +5644), IL-2 (-330 and +160), IL-4 (VNTR), IL-6 (-174), IL-10 (-1082 and -819) and IL-12B (+1188) in 188 normal healthy subjects (NHS) and 166 pulmonary tuberculosis patients (PTB) using polymerase chain reaction-based methods. To study the influence of cytokine gene polymorphisms on cytokine levels, phytohaemagglutinin and culture filtrate antigen of Mycobacterium tuberculosis-induced cytokine levels were measured by ELISA from 72-h-old peripheral blood mononuclear cell culture supernatants. Significantly decreased frequency of TT genotype of IL-2 -330 polymorphism (p=0.024, odds ratio (OR) 0.53, 95% CI 0.31-0.92) was observed in patients compared to NHS. The genotype frequencies of other polymorphisms were not different between patients and NHS. IL-12p40 levels were significantly decreased among NHS with AA genotype of IL-12B gene polymorphism compared to NHS with AC genotype (p<0.05). Increased levels of IL-12p40 were observed among patients with CC genotype of IL-12B gene compared to patients with other genotypes (p<0.01). The present study suggests that the TT genotype of IL-2 -330 polymorphism may be associated with the protection to PTB in south India. Further, +1188 polymorphism of IL-12B gene either alone or in combination with closely linked genes may regulate IL-12p40 production and may play a major role on acquired immunity to tuberculosis.

Inflammation-related genes and the risk of Parkinson's disease: a multilocus approach

For the first time, the multilocus approach by the set-association method has been applied for the analysis of a cluster of five genes [tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), IL-8, IL-1alpha and IL-10] involved in the brain neuroinflammatory pathway in Parkinson's disease (PD), in a well-defined group of 197 PD patients and 173 control subjects from Spain. Set-association analysis did not reveal an independent or an interactive effect of these inflammatory genes on the PD risk.

The chemokine network. II. On how polymorphisms and alternative splicing increase the number of molecular species and configure intricate patterns of disease susceptibility

In this second review on chemokines, we focus on the polymorphisms and alternative splicings and on their consequences in disease. Because chemokines are key mediators in the pathogenesis of inflammatory, autoimmune, vascular and neoplastic disorders, a large number of studies attempting to relate particular polymorphisms of chemokines to given diseases have already been conducted, sometimes with contradictory results. Reviewing the published data, it becomes evident that some chemokine genes that are polymorphic have alleles that are found repeatedly, associated with disease of different aetiologies but sharing some aspects of pathogenesis. Among CXC chemokines, single nucleotide polymorphisms (SNPs) in the CXCL8 and CXCL12 genes stand out, as they have alleles associated with many diseases such as asthma and human immunodeficiency virus (HIV), respectively. Of CC chemokines, the stronger associations occur among alleles from SNPs in CCL2 and CCL5 genes and a number of inflammatory conditions. To understand how chemokines contribute to disease it is also necessary to take into account all the isoforms resulting from differential splicing. The first part of this review deals with polymorphisms and the second with the diversity of molecular species derived from each chemokine gene due to alternative splicing phenomena. The number of molecular species and the level of expression of each of them for every chemokine and for each functionally related group of chemokines reaches a complexity that requires new modelling algorithms akin to those proposed in systems biology approaches.

Single nucleotide polymorphism and haplotype association of the interleukin-8 gene with nasopharyngeal carcinoma

The cytokine interleukin-8 (IL-8) may play a role in the pathogenesis of nasopharyngeal carcinoma (NPC) through the modulation of tumor immune response or enhanced angiogenesis. Polymorphism of IL-8 gene, which may affect the production level of cytokine, has been inversely associated with a number of cancers. To test this hypothesis, we investigated the relationship of IL-8 gene polymorphisms and NPC in a Chinese population. We analyzed single nucleotide polymorphisms (SNPs) of IL-8 gene -845 T/C, -738 T/A, -353 A/T, -251 A/T and +678 T/C in 280 patients with NPC and 290 age and sex matched controls, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and polymerase chain reaction-sequence specific primers method (PCR-SSP). There were significant differences in the genotype and allele distribution of -251 A/T polymorphism of the IL-8 gene among cases and controls. The -251 AA and AT genotypes were associated with a significantly increased risk of NPC as compared with the -251 TT genotypes (OR=1.820, 95% CI, 1.120-2.959, P=0.015 and OR=1.590, 95% CI, 1.104-2.290, P=0.013, respectively). Haplotype analysis revealed that the homozygosity of the AAT haplotype (defined by SNPs at positions -353, -251 and +678) of IL-8 gene conveys the highest risk for NPC compared with the homozygosity for the TTC haplotype (OR=1.396; 95% CI, 1.064-1.831; P=0.016). The -251 A/T polymorphism of IL-8 and its haplotype are associated with NPC in a Chinese population. Our data suggests that IL-8 gene may play a role in the development of NPC.

Lack of association of IL8 gene polymorphisms with familial vesico-ureteral reflux

Vesico-ureteral reflux (VUR) is the most common inherited disorder of the lower urinary tract. Children with VUR are at risk for ongoing renal damage with subsequent infections. IL8 is an important inflammatory mediator which can be produced by epithelial cells of the renal tract in response to a variety of inflammatory stimuli. High serum concentrations of IL-8 have been reported in patients with chronic renal failure. Elevated IL-8 levels have been reported in the urine of patients with VUR and renal parenchymal scarring (RPS). More recently it was reported that urine IL-8 levels remain elevated in infants with VUR even in the absence of a urinary tract infection (UTI). Increased IL-8 expression has been shown to be associated with polymorphism at position -251 (rs4073) of the IL-8 promoter. The aim of this study was to examine the association of IL-8 gene polymorphism with familial VUR in a cohort of 219 siblings from 109 families affected with VUR, the largest such cohort tested to date. RPS was assessed using dimercaptosuccinic acid scintigraphy. Genotyping was performed in 219 siblings with VUR (157 without RPS, 62 with RPS) and 292 controls for the position -251 of IL-8 gene by polymerase chain reaction with tetra primers and gel analysis. Genotype was compared using the chi square test. Statistical significance was taken as a value of P < 0.05. There were no significant differences in IL-8 -251 genotype frequency between VUR patients and controls. Similarly, gender, severity of VUR and renal parenchymal scarring had no effect on IL-8 -251 genotype frequency. Although IL-8 urinary levels have been reported to be elevated in VUR, our data indicate that IL-8 gene is not involved in the pathogenesis of familial VUR or reflux nephropathy.

Haplotype association of IL-8 gene with Behcet's disease

Interleukin-8 (IL-8), a CXC chemokine that recruits and activates inflammatory cells, plays a critical role in the pathogenesis of Behcet's disease (BD). To investigate the association of the genetic polymorphism of IL-8 and BD, we genotyped IL-8 -845 T/C, -738 T/A, -353 A/T, -251 A/T, +293 G/T, +678 T/C and receptors CXCR-1 +2607 G/C and CXCR-2 +785 C/T polymorphisms in 119 Korean patients with BD and 119 age- and sex-matched healthy blood donors. Then, single nucleotide polymorphisms (SNPs) and haplotypes were analyzed between patients and controls. There were no SNPs associated with BD. However, the frequency of haplotype TAT inferred from SNPs, IL-8 -353 A/T, -251 A/T and +678 T/C, was significantly higher in patients with BD than controls (5.9 vs 0.0%, P = 0.0001), as was haplotype ATC (6.7 vs 0.0%, P < 0.0001). The haplotype difference was still valid in human leukocyte antigen-B51-negative subjects. In conclusion, we found a significant difference in the distribution of IL-8 gene haplotypes between patients with BD and healthy controls. These results suggest that the genetic polymorphisms of proinflammatory chemokine IL-8 can contribute to the pathogenesis of BD.

Temporal mRNA profiles of inflammatory mediators in the murine 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrimidine model of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). With the exception of a few rare familial forms of the disease, the precise molecular mechanisms underlying PD are unknown. Inflammation is a common finding in the PD brain, but due to the limitation of postmortem analysis its relationship to disease progression cannot be established. However, studies using the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD have also identified inflammatory responses in the nigrostriatal pathway that precede neuronal degeneration in the SNpc. To assess the pathological relevance of these inflammatory responses and to identify candidate genes that might contribute to neuronal vulnerability, we used quantitative reverse-transcription polymerase chain reaction (qRT-PCR) to measure mRNA levels of 11 cytokine and chemokine encoding genes in the striatum of MPTP-sensitive (C57BL/6J) and MPTP-insensitive (Swiss Webster, SWR) mice following administration of MPTP. The mRNA levels of all 11 genes changed following MPTP treatment, indicating the presence of inflammatory responses in both strains. Furthermore, of the 11 genes examined only 3, interleukin 6 (Il-6), macrophage inflammatory protein 1 alpha/CC chemokine ligand 3 (Mip-1alpha/Ccl3) and macrophage inflammatory protein 1 beta/CC chemokine ligand 4 (Mip-1beta/Ccl4), were differentially regulated between C57BL/6J and SWR mice. In both mouse strains, the level of monocyte chemoattractant protein 1/CC chemokine ligand 2 (Mcp-1/Ccl2) mRNA was the first to increase following MPTP administration, and might represent a key initiating component of the inflammatory response. Using Mcp-1/Ccl2 knockout mice backcrossed onto a C57BL/6J background we found that MPTP-stimulated Mip-1alpha/Ccl3 and Mip-1beta/Ccl4 mRNA expression was significantly lower in the knockout mice; suggesting that Mcp-1/Ccl2 contributes to MPTP-enhanced expression of Mip-1alpha/Ccl3 and Mip-1beta/Ccl4. However, stereological analysis of SNpc neuronal loss in Mcp-1/Ccl2 knockout and wild-type mice showed no differences. These findings suggest that it is the ability of dopaminergic SNpc neurons to survive an inflammatory insult, rather than genetically determined differences in the inflammatory response itself, that underlie the molecular basis of MPTP resistance.

Glial degeneration and reactive gliosis in alpha-synucleinopathies: the emerging concept of primary gliodegeneration

The concept of gliodegenerative diseases has not been widely established although there is accumulating evidence that glial cells may represent a primary target of degenerative disease processes. In the central nervous system (CNS), examples that provide a "proof of concept" include at least one alpha-synucleinopathy, multiple system atrophy (MSA), but this disease is conventionally discussed under the heading of "neurodegeneration". Additional evidence in support of primary glial affection has been reported in neurodegenerative disorders such as Parkinson's disease, Alzheimer's disease and transmissible spongiform encephalopathies. Based on biochemical, genetic and transcriptomic studies it is also becoming increasingly clear that the molecular changes measured in whole tissue extracts, e.g. obtained from Parkinson's disease brain, are not based on a purely neuronal contribution. This important evidence has been missed in cell culture or laser capture work focusing on the neuronal cell population. Studies of animal and in vitro models of disease pathogenesis additionally suggest glial accountability for some CNS degenerative processes. This review provides a critical analysis of the evidence available to date in support of the concept of gliodegeneration, which we propose to represent an essential although largely disregarded component of the spectrum of classical "neurodegeneration". Examples from the spectrum of alpha-synucleinopathies are presented.

Variation of interleukin 8 -251 A>T polymorphism in worldwide populations and intra-ethnic differences in Japanese populations

BACKGROUND

Interleukin-8 (IL8) is a member of the family of chemokines. The IL8 gene has polymorphic variations, and the genotype of IL8 -251 A>T is associated with smoking behavior and cancer progression.

METHOD

IL8 -251 A>T polymorphism were investigated in Japanese, from 5 different areas, in Ovambo, Turkish, Mongolian and Korean populations by PCR with confronting 2-pair primers (PCR-CTPP) analysis.

RESULTS

A subpopulation analysis of Japan revealed a north-to-south increase in the frequency of the IL8 -251 T allele. Among the 5 groups, the Japanese showed the highest frequency of mutant allele followed by the Turks. The distribution pattern in the Japanese was different from those of Mongolians and Koreans. In the Ovambo population, no mutant allele homozygote subject was found and the frequency of mutant alleles was the lowest, similar to that in Gambians.

CONCLUSION

The present study is the first to demonstrate the Japan population inter-prefecture differences in IL8 -251 A>T polymorphism as well as a certain genetic heterogeneity in the worldwide distribution of IL8 -251 A>T polymorphism. The distribution results may help define the true significance of IL8 -251 A>T polymorphism as a marker for smoking behavior in populations worldwide.

IL-8 (-251 A/T) and CXCR2 (+1208 C/T) gene polymorphisms and risk of multiple sclerosis in Iranian patients

IL-8 plays important roles in CNS development, modulation of neuronal survival and excitability. Among IL-8 receptors, only CXCR2 is known to be present in the brain. The ability of individuals in producing IL-8 is partially determined by IL-8 -251 A/T polymorphism. Therefore, the aim of the present study was to investigate the association between IL-8 -251 A/T and CXCR2 +1208 C/T gene polymorphisms and susceptibility to multiple sclerosis (MS). Two hundred and twenty-three MS patients and 319 healthy and ethnic matched controls were included in this study. IL-8 promoter (-251 A/T) and CXCR2 (+1208 C/T) gene polymorphisms were genotyped via allele specific PCR (AS-PCR) method. A significant difference was found in IL-8 -251 A/T polymorphism between MS patients and controls (p = 0.04). This deference was a result of a higher incidence of the low producer allele of IL-8 (T allele) in MS patients compared to controls. However, there was no significant association between different clinical findings (EDSS score, progression index, disease onset age, and the type of disease) and IL-8 -251 A/T polymorphism. Furthermore, no significant association existed between CXCR2 +1208 C/T polymorphism and MS susceptibility or different clinical parameters in patients. In summary, carriers of IL-8 -251 T allele may have increased susceptibility to MS because of their differences in neuron survival or increased chances of viral persistence compared to carriers of A allele.

The -251T allele of the interleukin-8 promoter is associated with increased risk of gastric carcinoma featuring diffuse-type histopathology in Chinese population

PURPOSE

Persistent interleukin-8 (IL-8) production contributes to chronic inflammation of the stomach. The proinflammatory IL-1beta polymorphisms, which enhance the cytokine production, are associated with increased risk of gastric cancer. The -251A/T polymorphism of the IL-8 promoter is involved in several human diseases. Particularly, the -251A is associated with decreased risk of colorectal cancer. We aimed to determine whether the -251 allele resulting in high IL-8 expression was associated with increased risk of gastric carcinoma.

EXPERIMENTAL DESIGN

The -251A/T promoters were cloned and analyzed by luciferase assay. Binding of nuclear proteins to the -251A/T promoters was analyzed by electrophoretic mobility shift assay. The -251A/T promoters were differentiated by PCR-RFLP. Comparison of gastric cancer risk between the -251A/T promoters was done by a case-control study.

RESULTS

The -251T allele possessed transcriptional activity 2- to 5-fold stronger than the -251A counterpart. Electrophoretic mobility shift assay showed that the -251A promoter had strong ability to bind to an unknown protein or multiprotein complex. The -251T allele was associated with increased risk of noncardia (P(trend) = 0.012) and cardia (P(trend) = 0.029) carcinomas. Gastric carcinoma patients with the low-risk AA genotype had a tendency to sustain intestinal-type carcinomas (chi(2) = 6.816; P = 0.033); however, the high-risk -251T allele was associated with >2-fold increased risk of diffuse-type (AA versus AT + TT: odds ratio, 2.52; 95% confidence interval, 1.16-5.49; P = 0.017) and mixed-type (AA versus AT + TT: odds ratio, 2.22; 95% confidence interval, 1.12-4.40; P = 0.019) carcinomas.

CONCLUSIONS

The IL-8 -251T allele is significantly associated with increased risk of gastric carcinoma, particularly the diffuse and mixed types in Chinese population.

Interaction of polymorphisms in the genes encoding interleukin-6 and estrogen receptor beta on the susceptibility to Parkinson's disease

The multifunctional cytokine interleukin-6 (IL-6) is involved in inflammatory processes in the central nervous system and increased levels of IL-6 have been found in patients with Parkinson's disease (PD). It is known that estrogen inhibits the production of IL-6, via action on estrogen receptors, thereby pointing to an important influence of estrogen on IL-6. In a previous study, we reported an association between a G/A single nucleotide polymorphism (SNP) at position 1730 in the gene coding for estrogen receptor beta (ERbeta) and age of onset of PD. To investigate the influence of a G/C SNP at position 174 in the promoter of the IL-6 gene, and the possible interaction of this SNP and the ERbeta G-1730A SNP on the risk for PD, the G-174C SNP was genotyped, by pyrosequencing, in 258 patients with PD and 308 controls. A significantly elevated frequency of the GG genotype of the IL-6 SNP was found in the patient group and this was most obvious among patients with an early age of onset (</=50 years) of PD. When the GG genotypes of the IL-6 and ERbeta SNPs were combined, the combination was much more robustly associated with PD, and especially with PD with an early age of onset, than respective GG genotype when analyzed separately. Our results indicate that the G-174C SNP in the IL-6 promoter may influence the risk for developing PD, particularly regarding early age of onset PD, and that the effect is modified by interaction of the G-1730A SNP in the ERbeta gene.