Association Study of Serotonin Transporter Gene Polymorphisms and Ventricular Septal Defects RelatedPossiblePulmonary Arterial Hypertension in Chinese Population

SLC6A4 gene L/S polymorphism and susceptibility to pulmonary arterial hypertension: a meta-analysis

Objective

To investigate the association between the solute carrier family 6 member 4 (SLC6A4) gene L/S polymorphism and pulmonary arterial hypertension (PAH).

Methods

The relevant literature was retrieved from the PubMed® database and the data were extracted. STATA® version 12.0 software was used to calculate pooled odds ratios (ORs) and 95% confidence intervals (CI).

Results

Eight case–control studies qualified for inclusion in the meta-analysis. These studies included 1215 cases and 936 control subjects. There was no significant association between the SLC6A4 gene L/S polymorphism and PAH risk in the total population (LL versus SS: OR 1.83, 95% CI 0.95, 3.51; LS versus SS: OR 1.37, 95% CI 0.93, 2.02; dominant model: OR 1.38, 95% CI 0.97, 1.97; recessive model: OR 1.54, 95% CI 0.84, 2.83). Subgroup analysis based on study quality scores and Hardy–Weinberg equilibrium also showed no significant association.

Conclusion

The findings of this meta-analysis suggest that the SLC6A4 gene L/S polymorphism is unlikely to be related to PAH risk. Well-designed studies with more participants will be required to validate these results.

Analysis of Angiotensin Converting Enzyme, Endothelial Nitric Oxide Synthase & Serotonin Gene Polymorphisms among Atrial Septal Defect Subjects with and without Pulmonary Arterial Hypertension

Genetic polymorphisms are variations in DNA sequences which can influence either disease susceptibility, severity, or prognosis. Pulmonary arterial hypertension (PAH) is one of the complications that occurs in certain patients who have atrial septal defect (ASD). This study seeks to determine the association of gene polymorphisms with the pathogenesis of PAH in ASD patients. This study was conducted on 30 ASD patients with PAH, and 50 ASD patients who were not diagnosed with PAH. All respondents were Malay. Patients were selected based on stringent inclusion and exclusion criteria. Molecular analyses were done to detect the genetic polymorphisms of angiotensin converting enzyme (ACE I/D), serotonin transporter (5-HTTLPR), endothelial nitric oxide synthase (eNOS) G894T, and eNOS 4b/4a. The genotypes of these genetic polymorphisms were determined using conventional PCR and PCR-RFLP methods. The PCR products were analysed using agarose gel electrophoresis. Statistical analysis was done using SPSS Version 22. Clinical characteristics, such as the diameter of ASD, mean arterial pressure (MAP), and mean pulmonary artery pressure (mPAP) differed significantly (p < 0.05). Based on the statistical analysis, ACE I/D, eNOS G894T, and eNOS 4b/4a do not contribute to the progression of PAH amongst ASD patients (p > 0.05). However, the L allele of the 5-HTTLPR gene polymorphism may have an affect on the development of PAH in ASD patients (p < 0.05).

Relationship of genetic variation in the serotonin transporter gene (SLC6A4) and congenital and acquired cardiovascular diseases

Recent reports have suggested an association between variation in the serotonin transporter and primary pulmonary hypertension and myocardial infarction. We set out to determine whether these associations were present in a population of patients who underwent SLC6A4 genotyping and to explore whether genetic variation in the serotonin transporter might be also associated with other cardiovascular functional and structural abnormalities. Included were 3473 patients who were genotyped for the SLC6A4 5HTTLPR polymorphism and a subset for rs25531 (n=816) and STin2 (n=819). An association was observed between 5HTTLPR and primary pulmonary hypertension (p=0.0130), anomalies of the cerebrovascular system (p<0.0001), and other anomalies of great veins (p=0.0359). The combined 5HTTLPR and rs25531 genotype was associated with tachycardia (p=0.0123). There was an association of the STin2 genotype with abnormal electrocardiogram (ECG) (p=0.0366) and abnormal cardiac study (0.0311). Overall, these results represent a step toward the understanding of the impact of SLC6A4 variation on cardiovascular pathology.

The use of antidepressants and the risk of idiopathic pulmonary arterial hypertension

BACKGROUND

Serotonin has been implicated in the development of idiopathic pulmonary arterial hypertension (IPAH). Drugs modulating serotonin pathways, including antidepressants, have been associated with the incidence of IPAH, with conflicting reports as to the direction of the effect. We aimed to determine whether antidepressant exposure is associated with the incidence of IPAH.

METHODS

A nested case-control study was conducted using the United Kingdom Clinical Practice Research Datalink and the Hospital Episodes Statistics repository between January 1, 1988 and September 30, 2011. Incident cases of IPAH were identified and matched to all controls in the case's risk set on age, sex, general practice, and date of registration with the practice. Rate ratios (RRs) and 95% confidence intervals (CIs) were estimated for the use of antidepressants on the risk of IPAH, with an 18-month lag period before the diagnosis.

RESULTS

One hundred ninety-five IPAH cases were identified (incidence 3.84/million per year). Use of any antidepressant was associated with a 67% increased risk of IPAH (RR, 1.67; 95% CI, 1.17-2.37). The rate of IPAH was similar across antidepressant classes, whether with selective serotonin reuptake inhibitors (SSRIs) (RR, 1.67; 95% CI, 1.09-2.57) or non-SSRI antidepressants (RR, 1.66; 95% CI, 1.07-2.59). In sensitivity and exploratory analyses, no change in risk was observed with different lag times, serotonin transporter affinities, or durations of exposure.

CONCLUSIONS

The use of antidepressants was associated with a significantly increased risk of IPAH. However, the consistency of this risk across all antidepressants and absence of a dose-response relationship suggests a noncausal association.

The inhibitory effects of m-nisoldipine on the 5-hydroxytryptamine-induced proliferation of pulmonary artery smooth muscle cells via Ca2+ antagonism and antioxidant mechanisms

The excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) plays a critical role in the development of pulmonary arterial hypertension. Recent studies indicate that Ca(2+) and reactive oxygen species are critically involved in the process of smooth muscle cell proliferation stimulated by mitogens, such as 5-hydroxytryptamine (5-HT). Because m-nisoldipine, a Ca(2+) channel blocker of the dihydropyridine class, possesses some calcium antagonistic and antioxidant properties, we investigated the effect of m-nisoldipine on PASMC proliferation. The results indicated that m-nisoldipine inhibited 5-HT-induced PASMC proliferation, evaluated by BrdU incorporation and the MTT assay, and this effect was associated with a decreased expression of proliferating cell nuclear antigen (PCNA). Flow cytometry analysis showed that m-nisoldipine blocked 5-HT-induced cell-cycle progression by arresting the cells in the G(0)/G(1) phase. Next, the production of reactive oxygen species and the levels of [Ca(2+)](i) in PASMCs were measured by laser scanning confocal microscopy; m-nisoldipine pretreatment attenuated the [Ca(2+)](i) elevation and the production of reactive oxygen species induced by 5-HT. In addition, m-nisoldipine significantly decreased the 5-HT-induced activation of extracellular signal-regulated kinase (ERK1/2) and c-Jun N-terminal kinase (JNK) and the subsequent c-fos and c-jun mRNA expression. Meanwhile, results also showed that N-acetylcysteine (a reactive oxygen species scavenger) suppressed the proliferation and the ERK1/2 and JNK activation induced by 5-HT. In summary, this study demonstrated that m-nisoldipine effectively suppressed the 5-HT-induced PASMC proliferation, ERK1/2 and JNK activation and subsequent c-fos and c-jun mRNA expression, all of which might be associated with the Ca(2+) antagonistic and antioxidant properties of m-nisoldipine.