Polymorphisms in the interleukin-8 gene in patients with chronic obstructive pulmonary disease

Association of Genetic Polymorphisms and Serum Levels of IL-6 and IL-8 with the Prognosis in Children with Neuroblastoma

Simple Summary

Neuroblastoma (NB) presents diverse biological and clinical characteristics, from spontaneous regression to highly malignant and aggressive unfavorable tumors that condition the therapeutic failure of conventional treatments. The tumorigenesis of NB can be the result of different genetic variants, which can influence the clinical outcome, and the survival of patients who have metastatic tumors is low. The role of cytokines such as interleukin (IL)-6 has been described in the NB microenvironment promoting tumor progression and metastasis. Single nucleotide polymorphism (SNP)-174 G > C in IL-6 and -251 T > A and +781 C > T in IL-8 regulate the expression of these cytokines, and could be associated with the clinical outcome in patients with NB. Our objective was to evaluate the association of the genetic polymorphisms of IL-6 and IL-8, as well as the serum levels of these cytokines in patients with NB, as this will allow the genetic bases of NB to be characterized and understood, in order to predict the outcome of the disease and develop new therapeutic strategies.

Abstract

There is evidence that high circulating levels of IL-6 and IL-8 are markers of a poor prognosis in various types of cancer, including NB. The participation of these cytokines in the tumor microenvironment has been described to promote progression and metastasis. Our objective was to evaluate the prognostic role of genetic polymorphisms and serum levels of IL-6 and IL-8 in a cohort of Mexican pediatric patients with NB. The detection of the SNPs rs1800795 IL-6 and rs4073 and rs2227306 IL-8 was carried out by PCR-RFLP and the levels of cytokines were determined by the ELISA method. We found elevated circulating levels of IL-8 and IL-6 in NB patients compared to the control group. The genotype frequencies of the rs1800795 IL-6 and rs4073 IL-8 variants were different between the patients with NB and the control group. Likewise, the survival analysis showed that the GG genotypes of rs1800795 IL-6 (p = 0.014) and AA genotypes of rs4073 IL-8 (p = 0.002), as well as high levels of IL-6 (p = 0.009) and IL-8 (p = 0.046), were associated with lower overall survival. We confirmed the impact on an adverse prognosis in a multivariate model. This study suggests that the SNPs rs1800795 IL-6 and rs4073 IL-8 and their serum levels could be promising biomarkers of a poor prognosis, associated with overall survival, metastasis, and a high risk in Mexican children with NB.

Immune-related gene polymorphisms in pulmonary diseases

Between the DNA sequences of two randomly-selected human genomes, which consist of over 3 billion base pairs and twenty five thousand genes, there exists only 0.1% variation and 99.9% sequence identity. During the last couple of decades, extensive genome-wide studies have investigated the association between single-nucleotide polymorphisms (SNPs), the most common DNA variations, and susceptibility to various diseases. Because the immune system's primary function is to defend against myriad infectious agents and diseases, the large number of people who escape serious infectious diseases underscores the tremendous success of this system at this task. In fact, out of the third of the global human population infected with Mycobacterium tuberculosis during their lifetime, only a few people develop active disease, and a heavy chain smoker may inexplicably escape all symptoms of chronic obstructive pulmonary disease (COPD), lung cancer, and other smoke-associated lung diseases. This may be attributable to the genetic makeup of the individual(s), including their SNPs, which provide some resistance to the disease. Pattern recognition receptors (PRRs), transcription factors, cytokines and chemokines all play critical roles in orchestrating immune responses and their expression/activation is directly linked to human disease tolerance. Moreover, genetic variations present in the immune-response genes of various ethnicities may explain the huge differences in individual outcomes to various diseases and following exposure to infectious agents. The current review focuses on recent advances in our understanding of pulmonary diseases and the relationship of genetic variations in immune response genes to these conditions.

Association between interleukin 8-251 T/A and +781 C/T polymorphisms and glioma risk

Background

Gliomas are aggressive tumors of the central nervous system that rely on production of growth factors for tumor progression. Interleukin 8 (IL-8) is up-regulated in gliomas to promote angiogenesis and proliferation. The aim of this study was to evaluate the association of the IL-8 -251 T/A and +781 C/T polymorphisms and glioma risk.

Methods

We enrolled 300 glioma patients and 300 age- and gender-matched healthy controls. A prospective hospital-based case–control design and logistic regression analysis were utilized. The IL-8 gene polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

Results

Glioma patients had a significantly higher frequency of IL-8 -251 AA genotype [odds ratio (OR) =1.91, 95 % confidence interval (CI) = 1.22, 3.00; P = 0.005] and IL-8 -251 A allele (OR =1.36, 95 % CI = 1.08, 1.70; P = 0.009) than controls. When stratified by the grade of glioma, patients with WHO IV glioma had a significantly higher frequency of IL-8 -251 AA genotype (OR =1.56, 95 % CI = 1.01, 2.39; P = 0.04).

Conclusions

To the best of our knowledge, this is the first report in the literature that the IL-8 -251 AA genotype and A allele were at a higher risk for glioma.

Relation between inflammatory cytokine levels in serum and bronchoalveolar lavage fluid and gene polymorphism in young adult patients with bronchiectasis

AIM

Bronchiectasis develops as a result of genetic and environmental factors and its etiopathogenesis is not still clear. Recent studies have revealed that inflammatory cytokines, which are formed as a result of chronic infection and inflammation, play a role in the pathogenesis of bronchiectasis. For this purpose, the level of inflammatory cytokines in bronchiectasis and the presence or absence of a genetic predisposition with the gene polymorphism of these cytokines was investigated.

MATERIAL AND METHODS

A total of 60 patients, 40 study cases and 20 controls, which were monitored with the diagnosis of bronchiectasis were included in the study. In these individuals, cytokine levels [interleukin (IL)-6, IL-8, IL-10, and tumor necrosis factor (TNF)-α] in serum and bronchoalveolar lavage (BAL) fluid, along with the routine blood tests, were determined. Furthermore, the polymorphism in IL-6, IL-8, IL-10, and TNF-α cytokine genes and its frequency were studied in the obtained DNA by the automatic sequence analysis method and the results were compared.

FINDINGS

It was found that in serum and BAL fluid of the patient group, the IL-8 level was high, whereas the IL-10 level was low (P<0.05). No significant difference was detected in the other cytokines (P>0.05). It was found that in cytokine gene polymorphisms IL-8 -251 A/T, IL-10 -592 A/C, and IL-10 -819 T/C genotypes are associated with increased risk of bronchiectasis. It was detected that the IL-8 -251 A/T genotype increased the risk of having the disease by 4.19 fold. (OR =4.19, 95% CI =1.24-14.17, P=0.021). The IL-10 -592 C/A genotype increased the risk of having the disease by 5.71 fold (OR = 5.71, 95% CI =1.35-24.06, P=0.017) and the IL-10 -819 T/C genotype increased the risk of having the disease by 5.06 fold (OR =5.06, 95% CI =1.20-21.27, P=0.048). No significant correlation was found between the other polymorphisms and bronchiectasis.

CONCLUSIONS

The IL-8, IL-10 levels and the gene polymorphism of these cytokines differ. In addition to detecting higher levels of pro-inflammatory IL-8 and lower levels of anti-inflammatory IL-10, detection of gene polymorphism related to these two cytokines in bronchiectasis gives rise to the thought that cytokines may have role in a predisposition to bronchiectasis. However, as the number of patients is small, precise remarks could not be made on this subject. There is need for further studies include a larger number of patients.

IL-8 gene variants are associated with lung function decline and multidimensional BODE index in COPD patients but not with disease susceptibility: a validation study

BACKGROUND AND OBJECTIVE

COPD is a leading cause of dead worldwide and tobacco smoking is its major risk factor. IL8 is a proinflammatory chemokine mainly involved in the acute inflammatory reaction. The aim of this study was to test the association of IL-8, CXCR1 and CXCR2 gene variants and COPD susceptibility as part of a replication study and explore the effect of these variations in disease progression.

METHODS

9 tagSNPs were genotyped in 728 Caucasian individuals (196 COPD patients, 80 smokers and 452 non-smoking controls). Pulmonary compromise was evaluated using spirometry and clinical parameters at baseline and annually over a 2 years period. We also determined plasma levels of TNF-α, IL-6, IL-8 and IL-16 in COPD patients.

RESULTS

There was a lack of association between gene variants or haplotypes with predisposition to COPD. No correlation was observed between the polymorphisms and cytokines levels. Interestingly, significant associations were found between carriers of the rs4073A (OR = 3.53, CI 1.34-9.35, p = 0.01), rs2227306C (OR = 5.65, CI 1.75-18.88, p = 0.004) and rs2227307T (OR = 4.52, CI = 1.49-12.82, p = 0.007) alleles in the IL-8 gene and patients who scored higher in the BODE index and showed an important decrease in their FEV1 and FVC during the 2 years follow-up period (p < 0.05).

CONCLUSIONS

Despite no association was found between the studied genes and COPD susceptibility, three polymorphisms in the IL-8 gene appear to be involved in a worse progression of the disease, with an affectation beyond the pulmonary function and importantly, a reduction in lung function along the follow-up years.

The tumor necrosis factor α (-308 A/G) polymorphism is associated with cystic fibrosis in Mexican patients

Environmental and genetic factors may modify or contribute to the phenotypic differences observed in multigenic and monogenic diseases, such as cystic fibrosis (CF). An analysis of modifier genes can be helpful for estimating patient prognosis and directing preventive care. The aim of this study is to determine the association between seven genetic variants of four modifier genes and CF by comparing their corresponding allelic and genotypic frequencies in CF patients (n = 81) and control subjects (n = 104). Genetic variants of MBL2 exon 1 (A, B, C and D), the IL-8 promoter (-251 A/T), the TNFα promoter (TNF1/TNF2), and SERPINA1 (PI*Z and PI*S) were tested in CF patients and control subjects from northeastern Mexico by PCR-RFLP.

RESULTS

The TNF2 allele (P = 0.012, OR 3.43, 95% CI 1.25-9.38) was significantly associated with CF under the dominant and additive models but was not associated with CF under the recessive model. This association remained statistically significant after adjusting for multiple tests using the Bonferroni correction (P = 0.0482). The other tested variants and genotypes did not show any association with the disease.

CONCLUSION

An analysis of seven genetic variants of four modifier genes showed that one variant, the TNF2 allele, appears to be significantly associated with CF in Mexican patients.

Effect of Helicobacter pylori eradication according to the IL-8-251 polymorphism in Koreans

Previous studies suggested that polymorphisms of proinflammatory cytokine genes are important host genetic factors in Helicobacter pylori infection. The present study evaluated whether IL-8-251 polymorphism affected H. pylori eradication rate and to investigate the effect of H. pylori eradication on angiogenesis and the inflammatory process according to the IL-8-251 polymorphism. A total of 250 H. pylori-positive patients treated by endoscopic resection of the gastric neoplasm were classified into 3 groups (134 H. pylori-eradicated group, 19 H. pylori-eradication failure group, and 97 H. pylori-infected group). H. pylori status, histology, and angiogenic factor levels were evaluated at baseline, 6 months, and 18 months. H. pylori eradication rate was 92.9% in AA genotype, 85.7% in AT genotype and 88.4% in TT genotype (P value = 0.731). Elevated IL-8 and matrix metalloproteinase-9 concentrations in H. pylori-infected gastric mucosa were reversible by successful eradication of H. pylori, independent of the IL-8-251 polymorphism. It is suggested that elevated IL-8 and MMP-9 concentrations in H. pylori-infected gastric mucosa are altered significantly after successful eradication and these conditions continue for 18 months. However, IL-8-251 polymorphism does not affect H. pylori eradication rate and the sequential changes of related angiogenic factors after H. pylori eradication in Koreans.

Updates on the COPD gene list

A genetic contribution to develop chronic obstructive pulmonary disease (COPD) is well established. However, the specific genes responsible for enhanced risk or host differences in susceptibility to smoke exposure remain poorly understood. The goal of this review is to provide a comprehensive literature overview on the genetics of COPD, highlight the most promising findings during the last few years, and ultimately provide an updated COPD gene list. Candidate gene studies on COPD and related phenotypes indexed in PubMed before January 5, 2012 are tabulated. An exhaustive list of publications for any given gene was looked for. This well-documented COPD candidate-gene list is expected to serve many purposes for future replication studies and meta-analyses as well as for reanalyzing collected genomic data in the field. In addition, this review summarizes recent genetic loci identified by genome-wide association studies on COPD, lung function, and related complications. Assembling resources, integrative genomic approaches, and large sample sizes of well-phenotyped subjects is part of the path forward to elucidate the genetic basis of this debilitating disease.

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.

The interleukin-8-251 A allele is associated with increased risk of noncardia gastric adenocarcinoma in Helicobacter pylori-infected Koreans

BACKGROUND AND GOALS

Chronic inflammation associated with Helicobacter pylori infection is a risk factor of gastric adenocarcinoma. Interleukin-8 (IL-8) plays an important role in gastric mucosal inflammation induced by H. pylori infection. Recently, studies on the association of genetic polymorphisms of various proinflammatory cytokines with gastric carcinogenesis showed varying results on the basis of the ethnicity. We conducted this study to investigate the association of IL-8-251 A/T polymorphism with gastric carcinogenesis in H. pylori-infected Koreans.

STUDY

The IL-8-251 A/T polymorphism was identified by polymerase chain reaction-restriction fragment length polymorphism using DNA from a total of 605 H. pylori-infected subjects; 206 controls, 149 chronic atrophic gastritis and/or intestinal metaplasia, 97 gastric dysplasia, and 153 gastric adenocarcinoma. Degrees of gastric mucosal inflammation and mucosal IL-8 level were also assessed.

RESULTS

The IL-8-251 A carriers showed a higher risk of gastric adenocarcinoma (adjusted odds ratio 2.06, 95% confidence interval 1.16-3.68) than IL-8-251 T/T genotypes. The IL-8-251 A allele was also significantly associated with the degree of neutrophil infiltration, atrophy, and intestinal metaplasia in a younger age group. Among the chronic atrophic gastritis and/or intestinal metaplasia group, mucosal IL-8 level was significantly higher in subjects with IL-8-251 A allele than those with IL-8-251 T/T genotypes (P=0.011).

CONCLUSIONS

The IL-8-251 A allele is associated with higher IL-8 production, more severe inflammation, mucosal atrophy, and intestinal metaplasia than IL-8-251 T/T genotype in H. pylori-infected hosts. The IL-8-251 A allele may also increase the risk of gastric adenocarcinoma through an enhanced inflammatory process in H. pylori-infected Koreans.

Genetic polymorphism of MCP-1-2518, IL-8-251 and susceptibility to acute pancreatitis: a pilot study in population of Suzhou, China

AIM

To study the relationship between MCP-1-2518A/G, IL-8-251A/T polymorphism and acute pancreatitis (AP) in the Han population of Suzhou, China.

METHODS

A case-control study was conducted to compare the distribution of genotype and genetic frequency of MCP-1-2518A/G, IL-8-251A/T gene polymorphism among AP (n = 101), including mild AP (n = 78) and severe AP (n = 23) and control healthy individuals (n = 120) with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing, and analyze the relationship between the MCP-1-2518A/G, IL-8-251A/T gene polymorphism and the susceptibility to AP.

RESULTS

Significant differences were found in the distribution of genotype of MCP-1-2518A/G between the healthy control group and mild AP group (chi2 = 32.015, P < 0.001), the same was evident between the healthy control group and severe AP group (chi2 = 12.932, P < 0.05) in Suzhou. However, no difference of genotypic distribution was noted between MAP and SAP (chi2 = 0.006, P = 0.997). The genetic frequencies of G allele in mild AP were 72.4% (113/156) and 76.1% (35/46) in severe AP, both were higher than the controls, 47.1% (113/240) (chi2 = 24.804; P < 0.001, and chi2 = 13.005; P < 0.001), but no difference was found between severe AP and mild AP (chi2 = 0.242; P = 0.623). No difference was found in the distribution of genotype of IL-8-251A/T between the healthy control group and AP group neither in the frequency of A and T allele.

CONCLUSION

The MCP-1-2518 AA genotype of the population in Suzhou may be a protective genotype of AP, while one with higher frequency of G allele is more likely to suffer from pancreatitis. But the genotype of AA and the frequency of G allele could not predict the risk of severe AP. No correlation is found between the IL-8-251 polymorphism and the liability of AP.

Ozone enhances diesel exhaust particles (DEP)-induced interleukin-8 (IL-8) gene expression in human airway epithelial cells through activation of nuclear factors- kappaB (NF-kappaB) and IL-6 (NF-IL6)

Ozone, a highly reactive oxidant gas is a major component of photochemical smog. As an inhaled toxicant, ozone induces its adverse effects mainly on the lung. Inhalation of particulate matter has been reported to cause airway inflammation in humans and animals. Furthermore, epidemiological evidence has indicated that exposure to particulate matter (PM[2.5-10]), including diesel exhaust particles (DEP) has been correlated with increased acute and chronic respiratory morbidity and exacerbation of asthma. Previously, exposure to ozone or particulate matter and their effect on the lung have been addressed as separate environmental problems. Ozone and particulate matter may be chemically coupled in the ambient air. In the present study we determined whether ozone exposure enhances DEP effect on interleukin-8 (IL-8) gene expression in human airway epithelial cells. We report that ozone exposure (0.5 ppm x 1 hr) significantly increased DEP-induced IL-8 gene expression in A549 cells (117 +/- 19 pg/ml, n = 6, p < 0.05) as compared to cultures treated with DEP (100 microg/ml x 4 hr) alone (31 +/- 3 pg/ml, n = 6), or cultures exposed to purified air (24 +/- 6 pg/ml, n = 6). The increased DEP-induced IL-8 gene expression following ozone exposure was attributed to ozone-induced increase in the activity of the transcription factors NF-kappaB and NF-IL6. The results of the present study indicate that ozone exposure enhances the toxicity of DEP in human airway epithelial cells by augmenting IL-8 gene expression, a potent chemoattractant of neutrophils in the lung.

PCR-SSCP: a method for the molecular analysis of genetic diseases

Single strand conformation polymorphism (SSCP) is a reproducible, rapid and quite simple method for the detection of deletions/insertions/rearrangements in polymerase chain reaction amplified DNA. All the details for the use of PCR-SSCP are presented in the direction of genetic diseases (beta-thalassaemia, cystic fibrosis), optimum gel conditions, sensitivity and the latest modifications of the method, which are applied in most laboratories. This non-radioactive PCR-SSCP method can be reliably used to identify mutations in patients (beta-globin, CFTR), provided suitable controls are available. Moreover, it is widely used for mutation identification in carriers (beta-thalassaemia, cystic fibrosis), making it particularly useful in population screening.

Gene–environment interactions in the development of chronic obstructive pulmonary disease

PURPOSE OF REVIEW

Genetic factors influence the variable development of chronic obstructive pulmonary disease in response to smoking and are likely to vary between populations. Recent studies have begun to shed some light on these gene-environment interactions.

RECENT FINDINGS

A variety of approaches has been used to identify novel susceptibility genes for chronic obstructive pulmonary disease. These studies have provided evidence for the possible role of many inflammatory mediators and their receptors, proteases, antiproteases, and antioxidant and xenobiotic genes in chronic obstructive pulmonary disease pathophysiology. However, ethnic differences and subtle phenotype differences often make replication of these studies difficult.

SUMMARY

The completion of the Human Genome Project, the HapMap project, technological advances in single-nucleotide-polymorphism genotyping and the potential of genome-wide association analysis will allow the identification of susceptibility genes for chronic obstructive pulmonary disease. The challenge is to understand the influence of multiple genetic factors and multiple environmental factors as well as gene-gene and gene-environment interactions. Careful clinical characterization of phenotypes for chronic obstructive pulmonary disease is essential and this will include comparison of biomarkers of distinct pathologies including radiological assessment to separate the components of pulmonary emphysema and small-airway disease.

Association of IL8, CXCR2 and TNF-alpha polymorphisms and airway disease

Chronic obstructive pulmonary disease (COPD) is a disease characterised by inflammation of the peripheral airways involving many inflammatory cells and mediators. IL8 is an important inflammatory mediator that is responsible for the migration and activation of neutrophils. Cellular activity of IL8 is mediated by the receptor CXCR2, and transcription of IL8 is controlled by the cytokine tumour necrosis factor (TNFalpha). The aim of our study was to investigate the influence of single nucleotide polymorphisms in IL8, CXCR2 and TNF-alpha on lung function and respiratory symptoms in subjects from Melbourne, Australia. A total of 1,232 participants completed a detailed respiratory questionnaire, spirometry and measurement of gas transfer. Genotyping for the IL8 -251 T-->A, CXCR2 +785C-->T and TNF-alpha -308G-->A polymorphisms was performed using the tetra-primer ARMS-PCR method. The TNF-alpha A allele was associated with a reduced FEF(25-75) (P = 0.03). Inheritance of the CXCR2 T allele was associated with significantly higher diffusing capacity (P = 0.03) and FEF(25-75) (P = 0.02). No association with the IL8 -251 polymorphism was found. Our results suggest that TNF-alpha is associated with COPD-related phenotypes and the CXCR2 +785 SNP may be important in protecting against pulmonary inflammation. These genes may be important candidates in the modulation of the inflammatory response in the airways.