Promoter polymorphism influences the effect of dexamethasone on transcriptional activation of the LTC4 synthase gene

Pharmacogenomics of Leukotriene Modifiers: A Systematic Review and Meta-Analysis

Pharmacogenetics research on leukotriene modifiers (LTMs) for asthma has been developing rapidly, although pharmacogenetic testing for LTMs is not yet used in clinical practice. We performed a systematic review and meta-analysis on the impact of pharmacogenomics on LTMs response. Studies published until May 2022 were searched using PubMed, EMBASE, and Cochrane databases. Pharmacogenomics/genetics studies of patients with asthma using LTMs with or without other anti-asthmatic drugs were included. Statistical tests of the meta-analysis were performed with Review Manager (Revman, version 5.4, The Cochrane Collaboration, Copenhagen, Denmark) and R language and environment for statistical computing (version 4.1.0 for Windows, R Core Team, Vienna, Austria) software. In total, 31 studies with 8084 participants were included in the systematic review and five studies were also used to perform the meta-analysis. Two included studies were genome-wide association studies (GWAS), which showed different results. Furthermore, none of the SNPs investigated in candidate gene studies were identified in GWAS. In candidate gene studies, the most widely studied SNPs were ALOX5 (tandem repeats of the Sp1-binding domain and rs2115819), LTC4S-444A/C (rs730012), and SLCO2B1 (rs12422149), with relatively inconsistent conclusions. LTC4S-444A/C polymorphism did not show a significant effect in our meta-analysis (AA vs. AC (or AC + CC): −0.06, 95%CI: −0.16 to 0.05, p = 0.31). AA homozygotes had smaller improvements in parameters pertaining to lung functions (−0.14, 95%CI: −0.23 to −0.05, p = 0.002) in a subgroup of patients with non-selective CysLT receptor antagonists and patients without inhaled corticosteroids (ICS) (−0.11, 95%CI: −0.14 to −0.08, p < 0.00001), but not in other subgroups. Variability exists in the pharmacogenomics of LTMs treatment response. Our meta-analysis and systematic review found that LTC4S-444A/C may influence the treatment response of patients taking non-selective CysLT receptor antagonists for asthma, and patients taking LTMs not in combination with ICS for asthma. Future studies are needed to validate the pharmacogenomic influence on LTMs response.

Association of the -1072G/A polymorphism in the LTC4S gene with asthma in an Indian population

BACKGROUND

Atopic asthma, the most common chronic disease affecting children and young adults, is a complex disorder with variable phenotypes. Cysteine leukotrienes (Cys-LTs) are powerful bronchoconstrictors and play a critical role in airway inflammation and remodeling that are characteristic of asthma.

OBJECTIVE

To investigate the association of ALOX5, LTC4S and CysLTR2 gene polymorphisms with atopic asthma in an Indian population.

METHODS

A total of 19 single nucleotide polymorphisms (SNPs) within these genes were genotyped in a family-based cohort (n = 239) and a case-control cohort (139 cases and 194 controls) followed by association analyses.

RESULTS

We found a significant association of the -1072G/A (rs3776944) SNP with atopic asthma in the family-based association analysis (p = 0.0004). These results were also replicated in the case-control cohort (p = 0.009). The allele A was negatively associated with atopic asthma. We also noted a significant association in the two-locus (rs3776944G/A and rs730012A/C) haplotypic analysis of this gene both in the family-based (p = 0.03) and the case-control (p = 0.02) analyses.

CONCLUSION

This study supports the role of the LTC4S gene polymorphism in genetic susceptibility to atopic asthma in an Indian population.

The role of ALOX5AP, LTA4H and LTB4R polymorphisms in determining baseline lung function and COPD susceptibility in UK smokers

Background

We have previously shown evidence that polymorphisms within genes controlling leukotriene B₄ (LTB₄) production (ALOX5AP and LTA4H) are associated with asthma susceptibility in children. Evidence also suggests a potential role of LTB₄ in COPD disease mechanisms including recruitment of neutrophils to the lung. The aim of the current study was to see if these SNPs and those spanning the receptor genes for LTB₄ (LTB4R1 and LTB4R2) influence baseline lung function and COPD susceptibility/severity in smokers.

Methods

Eight ALOX5AP, six LTA4H and six LTB4R single nucleotide polymorphisms (SNPs) were genotyped in a UK Smoking Cohort (n = 992). Association with baseline lung function (FEV₁ and FEV₁/FVC ratio) was determined by linear regression. Logistic regression was used to compare smoking controls (n = 176) with spirometry-defined COPD cases (n = 599) and to more severe COPD cases (GOLD stage 3 and 4, n = 389).

Results

No association with ALOX5AP, LTA4H or LTB4R survived correction for multiple testing. However, we showed modest association with LTA4H rs1978331C (intron 11) with increased FEV₁ (p = 0.029) and with increased FEV₁/FVC ratio (p = 0.020).

Conclusions

These data suggest that polymorphisms spanning ALOX5AP, LTA4H and the LTB4R locus are not major determinants of baseline lung function in smokers, but provide tentative evidence for LTA4H rs1978331C (intron 11) in determining baseline FEV₁ and FEV₁/FVC ratio in Caucasian Smokers in addition to our previously identified role in asthma susceptibility.

Leukotriene C4 synthase and ischemic cardiovascular disease and obstructive pulmonary disease in 13,000 individuals

Ischemic cardiovascular disease and obstructive pulmonary disease involve inflammation. Leukotrienes may be important pro-inflammatory mediators. We tested the hypothesis that the (-1072)G > A and (-444)A > C promoter polymorphisms of leukotriene C4 synthase confer risk of transient ischemic attack (TIA), ischemic stroke, ischemic heart disease (IHD), asthma, and chronic obstructive pulmonary disease (COPD). We genotyped individuals from the Danish general population, the Copenhagen City Heart Study, and Danish patients with IHD/coronary atherosclerosis, the Copenhagen Ischemic Heart Disease Study. We used prospective (n = 10,386), cross-sectional (n = 10,386), and case-control (n = 2392 + 5012) designs. Allele frequency was 0.07 for (-1072)A and 0.29 for (-444)C. Cumulative incidence for TIA was higher for (-1072)AA versus GG genotype (log-rank: p < 0.001), and lower for (-444)CC versus AA genotype (log-rank: p = 0.03). Cumulative incidence for ischemic stroke was also lower for (-444)CC versus AA genotype (log-rank: p = 0.04). Multifactorially adjusted hazard ratios for TIA were 5.2(95% CI:1.9-14) for (-1072)AA versus GG genotype, and 0.4(0.2-1.0) for (-444)CC versus AA genotype. Corresponding values were 1.9 (0.7-5.2) and 0.7 (0.5-1.0) for ischemic stroke, and 0.8 (0.4-1.6) and 1.0 (0.9-1.2) for IHD. In the case-control study, corresponding multifactorially adjusted odds ratios for IHD/coronary atherosclerosis were 0.5 (0.2-1.3) and 1.2 (1.0-1.5). These genotypes were not associated with risk of asthma or COPD. Leukotriene C4 synthase promoter genotypes influence risk of TIA and ischemic stroke, but not risk of IHD/coronary atherosclerosis, asthma, or COPD.

Promotor polymorphisms in leukotriene C4 synthase and risk of ischemic cerebrovascular disease

OBJECTIVE

Cysteinyl leukotrienes are involved in inflammation and possibly in early carotid atherosclerosis. We tested the hypothesis that the -444 A/C and -1072 G/A polymorphisms of the leukotriene C(4) synthase associate with risk of ischemic cerebrovascular disease.

METHODS AND RESULTS

We genotyped 10 592 individuals from the Danish general population, the Copenhagen City Heart Study. During 24 years of follow-up, 557 individuals developed ischemic cerebrovascular disease. The allele frequency was 0.07 for -1072 A and 0.29 for -444 C. Cumulative incidence for ischemic cerebrovascular disease was higher for -1072 AA versus GG genotype (log-rank: P=0.002), and lower for -444 CC versus AA genotype (log-rank: P=0.008). Combined genotypes showed corresponding cumulative incidence differences (log-rank: P=0.003). Multifactorially adjusted hazard ratios for ischemic cerebrovascular disease were 2.8(1.4 to 5.7) for -1072 AA versus GG genotype, 0.6(0.4 to 0.9) for -444 CC versus AA genotype, 2.5(1.2 to 5.4) for combined AA-AA versus GG-AA genotype, and 0.6(0.4 to 0.9) for combined GG-CC versus GG-AA genotype. Genotype did not associate with risk of deep venous thrombosis or severe carotid atherosclerosis, or with levels of platelets and coagulation factors.

CONCLUSIONS

Leukotriene C(4) synthase -1072 AA genotype predict increased risk, whereas -444 CC genotype predict decreased risk of ischemic cerebrovascular disease.

Association between polymorphisms in prostanoid receptor genes and aspirin-intolerant asthma

BACKGROUND

Genetic predisposition is linked to the pathogenesis of aspirin-intolerant asthma. Most candidate gene approaches have focused on leukotriene-related pathways, whereas there have been relatively few studies evaluating the effects of polymorphisms in prostanoid receptor genes on the development of aspirin-intolerant asthma. Therefore, we investigated the potential association between prostanoid receptor gene polymorphisms and the aspirin-intolerant asthma phenotype.

METHODS

We screened for genetic variations in the prostanoid receptor genes PTGER1, PTGER2, PTGER3, PTGER4, PTGDR, PTGIR, PTGFR, and TBXA2R using direct sequencing, and selected 32 tagging single nucleotide polymorphisms among the 77 polymorphisms with frequencies >0.02 based on linkage disequilibrium for genotyping. We compared the genotype distributions and allele frequencies of three participant groups (108 patients with aspirin-intolerant asthma, 93 patients with aspirin-tolerant asthma, and 140 normal controls).

RESULTS

Through association analyses studies of the 32 single nucleotide polymorphisms, the following single nucleotide polymorphisms were found to have significant associations with the aspirin-intolerant asthma phenotype: -616C>G (P=0.038) and -166G>A (P=0.023) in PTGER2; -1709T>A (P=0.043) in PTGER3; -1254A>G (P=0.018) in PTGER4; 1915T>C (P=0.015) in PTGIR; and -4684C>T (P=0.027), and 795T>C (P=0.032) in TBXA2R. In the haplotype analysis of each gene, the frequency of PTGIR ht3[G-G-C-C], which includes 1915T>C, differed significantly between the aspirin-intolerant asthma patients and aspirin-tolerant asthma patients (P=0.015).

CONCLUSION

These findings suggest that genetic polymorphisms in PTGER2, PTGER3, PTGER4, PTGIR, and TBXA2R play important roles in the pathogenesis of aspirin-intolerant asthma.

Lack of an association between a newly identified promoter polymorphism (-1702G > A) of the leukotriene C4 synthase gene and aspirin-intolerant asthma in a Korean population

Aspirin-intolerant asthma (AIA) is a distinct clinical syndrome that refers to the development of bronchoconstriction in asthmatic individuals following the ingestion of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs). It is widely recognized that increased cysteinyl leukotriene (cysLT) biosynthesis is associated with the development and progression of AIA. Leukotriene C4 synthase (LTC4S) is the terminal enzyme in cysLT production and is a strong candidate gene in the pathogenesis of aspirin-intolerant asthma (AIA). In this paper, we report a new single nucleotide polymorphism (SNP) of the LTC4S promoter, -1702G>A, in AIA patients and evaluate its genetic role in the association with the LTC4S-444 A>C polymorphism. We enrolled 110 AIA patients, 125 aspirin-tolerant asthma (ATA) patients, and 125 normal controls. SNP genotyping of the LTC4S-1702G>A and -444A>C polymorphisms was performed using SNP-IT assays. Haplotype analyses were performed using Haploview version 2.05, which is based on an estimation-maximization (EM) algorithm. There were no significant differences in the allele or genotype frequencies of the LTC4S-1702G>A and -444A>C polymorphisms among the three groups (p > 0.05), with no significant differences in the observed haplotype frequencies (p > 0.05). Moreover, no significant associations were found between the genotype of each SNP in AIA patients with the clinical characteristics, including a forced expiratory volume in one second (FEV1) %, a provocation concentration of methacholine to induce more than 20% decrease of FEV1 (PC20) to methacholine, and serum total IgE levels (p > 0.05). These results indicate that there is no association between these two promoter polymorphisms of LTC4S and the phenotype of AIA in a Korean population.

Polymorphisms in the 5-lipoxygenase activating protein (ALOX5AP) gene are not associated with asthma in an Australian population

BACKGROUND

The cysteinyl-leukotrienes (cys-LTs) are important pro-inflammatory mediators in asthma, and have been shown to have a role in specific disease subtypes, including asthma severity. Few studies have investigated the role of polymorphisms in the ALOX5AP gene, encoding 5-lipoxygenase activating protein (FLAP), and asthma. We hypothesized that polymorphisms in this gene are associated with asthma and in particular, with asthma severity, in an Australian population.

OBJECTIVE

To screen the coding region of the ALOX5AP gene for polymorphisms and to determine the association between previously described polymorphisms and asthma and asthma severity in an Australian population.

METHODS

We used PCR-SSCP and PCR-RFLP analysis to examine a previously described promoter polyA variable repeat polymorphism and two intronic polymorphisms (IVS2+12C>A, IVS2+105T>C), and to screen all five exons of the gene for new polymorphisms, in a large Australian population of randomly selected, non-asthmatic controls (n=457), mild asthmatics (n=274), moderate asthmatics (n=231) and severe asthmatics (n=79).

RESULTS

We confirmed the presence of two polymorphisms in intron 2 and found no association between these polymorphisms and asthma or asthma severity, nor between a promoter polymorphism in the ALOX5AP gene and asthma or asthma severity. Gene fragment analysis of the promoter polymorphism revealed novel, conserved repeat numbers in our population, and no new polymorphisms were found in the coding region of the gene.

CONCLUSION

These findings in a large, well characterized asthma population, reveal that, while FLAP is an important enzyme in cys-LTs biosynthesis, polymorphisms in the ALOX5AP gene are not likely to be functionally associated with the asthma phenotype.