A nonsynonymous variant I248L of the adenosine A3 receptor is associated with coronary heart disease in a Latvian population

A3 Adenosine Receptors as Modulators of Inflammation: From Medicinal Chemistry to Therapy

The A3 adenosine receptor (A3 AR) subtype is a novel, promising therapeutic target for inflammatory diseases, such as rheumatoid arthritis (RA) and psoriasis, as well as liver cancer. A3 AR is coupled to inhibition of adenylyl cyclase and regulation of mitogen-activated protein kinase (MAPK) pathways, leading to modulation of transcription. Furthermore, A3 AR affects functions of almost all immune cells and the proliferation of cancer cells. Numerous A3 AR agonists, partial agonists, antagonists, and allosteric modulators have been reported, and their structure-activity relationships (SARs) have been studied culminating in the development of potent and selective molecules with drug-like characteristics. The efficacy of nucleoside agonists may be suppressed to produce antagonists, by structural modification of the ribose moiety. Diverse classes of heterocycles have been discovered as selective A3 AR blockers, although with large species differences. Thus, as a result of intense basic research efforts, the outlook for development of A3 AR modulators for human therapeutics is encouraging. Two prototypical selective agonists, N6-(3-Iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA; CF101) and 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Cl-IB-MECA; CF102), have progressed to advanced clinical trials. They were found safe and well tolerated in all preclinical and human clinical studies and showed promising results, particularly in psoriasis and RA, where the A3 AR is both a promising therapeutic target and a biologically predictive marker, suggesting a personalized medicine approach. Targeting the A3 AR may pave the way for safe and efficacious treatments for patient populations affected by inflammatory diseases, cancer, and other conditions.

The Polymorphism in ADORA3 Decreases Transcriptional Activity and Influences the Chronic Heart Failure Risk in the Chinese

Aim

To investigate the genetic contribution of adenosine A3 receptor (ADORA3) gene polymorphisms in the pathogenesis of chronic heart failure (CHF).

Methods

Firstly, a case-control study was performed to investigate the association of ADORA3 polymorphisms with CHF risk. Three hundred northern Chinese Han CHF patients and 400 ethnicity-matched healthy controls were included. Four polymorphisms were genotyped. This case-control study was also replicated in 304 CHF patients and 402 controls from southern China. Finally, the functional variability of positive polymorphism was analyzed using luciferase reporter assay and real-time PCR.

Results

Overall, the rs1544223 was significantly associated with CHF risk under the dominant model (P = 0.046, OR = 1.662, 95% CI = 1.009-2.738). But it did not affect disease severity. These results were also consistent in replicated population. In addition, the transcriptional activity for promoter with the A allele was lower than that with the G allele (n = 3, 4.501 ± 0.308 versus 0.571 ± 0.114, P < 0.01) and ADORA3 mRNA levels were significantly higher in GG homozygotes than subjects carrying GA (n = 6, 0.058 ± 0.01 versus 0.143 ± 0.068, P = 0.004) or AA genotypes (n = 6, 0.065 ± 0.01 versus 0.143 ± 0.068, P = 0.008).

Conclusions

Should the findings be validated by further studies with larger patient samples and in different ethnicities, they may provide novel insight into the pathogenesis of CHF.

The association of ADORA2A and ADORA2B polymorphisms with the risk and severity of chronic heart failure: a case-control study of a northern Chinese population

The causes of chronic heart failure (CHF) and its progression are likely to be due to complex genetic factors. Adenosine receptors A2A and A2B (ADORA2A and ADORA2B, respectively) play an important role in cardio-protection. Therefore, polymorphisms in the genes encoding those receptors may affect the risk and severity of CHF. This study was a case-control comparative investigation of 300 northern Chinese Han CHF patients and 400 ethnicity-matched healthy controls. Four common single-nucleotide polymorphisms (SNPs) of ADORA2A (rs2236625, rs2236624, rs4822489, and rs5751876) and one SNP of ADORA2B (rs7208480) were genotyped and an association between SNPs and clinical outcomes was evaluated. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association. The rs4822489 was significantly associated with the severity of CHF after adjustment for traditional cardiovascular risk factors (p = 0.040, OR = 1.912, 95% CI = 1.029–3.550). However, the five SNPs as well as the haplotypes were not found to be associated with CHF susceptibility. The findings of this study suggest that rs4822489 may contribute to the severity of CHF in the northern Chinese. However, further studies performed in larger populations and aimed at better defining the role of this gene are required.

The adenosine deaminase gene polymorphism is associated with chronic heart failure risk in Chinese

Adenosine (Ado) is an important cardioprotective agent. Since endogenous Ado levels are affected by the enzyme Ado deaminase (ADA), polymorphisms within the ADA gene may exert some effect on chronic heart failure (CHF). This study applied a case-control investigation to 300 northern Chinese Han CHF patients and 400 ethnicity-matched healthy controls in which nine single-nucleotide polymorphisms (SNPs) of ADA were genotyped and association analyses were performed. Odds ratios (ORs) with 95% confidence intervals (CI) were used to assess the association. Overall, rs452159 polymorphism in ADA gene was significantly associated with susceptibility to CHF under the dominant model (p = 0.013, OR = 1.537, 95% CI = 1.10–2.16), after adjustment for age, sex, and traditional cardiovascular risk factors. No difference in genotype distribution and allele frequency for the rs452159 according to the functional New York Heart Association class was found. Furthermore, the values of left ventricular ejection fraction, left-ventricle end-diastolic diameter or left-ventricle end-systolic diameter did not differ significantly among the different rs452159 genotype CHF patients. Although further studies with larger cohorts and other ethnicities are required to validate the conclusions, the findings of this study potentially provide novel insight into the pathogenesis of CHF.

Role of genetic factors on the effect of additional loading doses and two maintenance doses used to overcome clopidogrel hyporesponsiveness

BACKGROUND AND OBJECTIVE

Additional loading doses and higher maintenance doses (MDs) have been used to overcome hyporesponsiveness of clopidogrel. We aimed to investigate whether genetic polymorphisms of two cytochromes (CYP2C19 and CYP2C9) and ABCB1 modify effect of such dose-adjustment strategy.

MATERIALS AND METHODS

We enrolled 118 patients undergoing elective or acute percutaneous coronary intervention (PCI) with drug eluting stent (DES). Platelet reactivity index (PRI) was measured using the vasodilator-stimulated phosphoprotein (VASP) index and a cut-off value of ≥ 60% was defined as hyporesponsiveness. Polymorphism of two cytochromes (CYP2C19, CYP2C9) and gene ABCB1 were determined. In patients hyporesponsive to the initial LD the dose-adjustment was performed using up to 3 additional 600 mg LDs in order to achieve PRI <60%, and both 150 mg and 75 mg MD were tested at the follow-up.

RESULTS

Patients with at least one CYP2C19*2 allele had higher baseline PRI after the initial LD (78.2 ± 13.1 vs. 65.3 ± 19.5, P=0.005). The PRI reduction with additional LD was significantly smaller in carriers of the CYP2C19*2 (25.2 ± 15.6 vs. 35.5 ± 16.8, P=0.025) and similar trend was observed with subsequent additional LDs. Both MDs were less effective in presence of CYP2C19*2. Target PRI was, however, more frequently achieved with higher MD even in presence of CYP2C19*2 (in 70.6% vs. 23.5% of hyporesponders, P=0.008). No such differences were observed for other polymorphisms.

CONCLUSIONS

In patients hyporesponsive to a routine clopidogrel doses the potency of additional LD and higher MD of clopidogrel is compromised by presence of CYP2C19*2 allele. The dose-adjustment strategy is not affected by ABCB1 C3435T or CYP2C9 genotypes.

Association of F11 polymorphism rs2289252 with deep vein thrombosis and related phenotypes in population of Latvia

INTRODUCTION

Deep vein thrombosis (DVT) has a strong inherited predisposition that is partly explained by the strong genetic risk factors such as mutations in factor V, prothrombin, antithrombin III, protein C and S genes. Only recently the first GWAS have been performed on DVT resulting in discovery of novel genetic variants, however, the information on the common polymorphisms predisposing to the risk of DVT is still scarce.

MATERIALS AND METHODS

Here we selected six SNPs (rs5361 in SELE, rs2066865 in FGG, rs2227589 in SERPINC1, rs1613662 in GP6, rs13146272 in CYP4V2, rs2289252 in F11) reported to be associated with venous thrombosis conditions and studied the association of these common variants in selected case (n=177) and control (n=235) groups from population of Latvia. Genotyping was performed using TaqMan hybridization probe SNP genotyping assay.

RESULTS

Patients with DVT had a significantly higher frequency of F11 rs2289252 polymorphism (p=0.001; OR [95%CI]=1.61 [1.20-2.14]). When stratified by recurrence of DVT the tendency was observed that the same SNP had higher OR value in group of DVT patients with repeated episodes of DVT compared to patients with single DVT episode (p=0.009; OR [95%CI]=2.27[1.22-4.21] and p=0.009; OR [95%CI]=1.52[1.11-2.08] respectively), but due to limited group of cases this finding should be replicated.

CONCLUSION

We conclude that F11 gene variant rs2289252 contribute to inherited forms of DVT incidence and correlation of other analysed SNPs should be explored in populations with greater sample size and associated with various thrombosis related traits.

The role of common and rare MC4R variants and FTO polymorphisms in extreme form of obesity

Melanocortin 4 receptor (MC4R) is an important regulator of food intake and number of studies report genetic variations influencing the risk of obesity. Here we explored the role of common genetic variation from MC4R locus comparing with SNPs from gene FTO locus, as well as the frequency and functionality of rare MC4R mutations in cohort of 380 severely obese individuals (BMI > 39 kg/m(2)) and 380 lean subjects from the Genome Database of Latvian Population (LGDB). We found correlation for two SNPs--rs11642015 and rs62048402 in the fat mass and obesity-associated protein (FTO) with obesity but no association was detected for rs17782313 located in the MC4R locus in these severely obese individuals. We sequenced the whole gene MC4R coding region in all study subjects and found five previously known heterozygous non-synonymous substitutions V103I, I121T, S127L, V166I and I251L. Expression in mammalian cells showed that the S127L, V166I and double V103I/S127L mutant receptors had significantly decreased quantity at the cell surface compared to the wild type MC4R. We carried out detailed functional analysis of V166I that demonstrated that, despite low abundance in plasma membrane, the V166I variant has lower EC50 value upon αMSH activation than the wild type receptor, while the level of AGRP inhibition was decreased, implying that V166I cause hyperactive satiety signalling. Overall, this study suggest that S127L may be the most frequent functional MC4R mutation leading to the severe obesity in general population and provides new insight into the functionality of population based variants of the MC4R.