Single nucleotide polymorphisms in AGTR1, TFAP2B, and TRAF1 are not associated with the incidence of patent ductus arteriosus in Japanese preterm infants

Interactions between PDA-associated polymorphisms and genetic ancestry alter ductus arteriosus gene expression

BACKGROUND

DNA polymorphisms in PTGIS and TFAP2B have been identified as risk factors for patent ductus arteriosus (PDA) in a population composed of preterm infants with European genetic ancestry but not in more genetically diverse populations.

GOAL

To determine if the effects of TFAP2B and PTGIS polymorphisms on ductus arteriosus (DA) gene expression differ based on genetic ancestry.

METHODS

DA from 273 human second trimester fetuses were genotyped for TFAP2B and PTGIS polymorphisms and for polymorphisms distributing along genetic ancestry lines. RT-PCR was used to measure the RNA expression of 49 candidate genes involved with DA closure.

RESULTS

Seventeen percent of the DA analyzed were of European ancestry. In multivariable regression analyses we found consistent associations between four PDA-related TFAP2B polymorphisms (rs2817399(A), rs987237(G), rs760900(C), and rs2817416(C)) and expression of the following genes: EPAS1, CACNB2, ECE1, KCNA2, ATP2A3, EDNRA, EDNRB, BMP9, and BMP10, and between the PTGIS haplotype rs493694(G)/rs693649(A) and PTGIS and NOS3. These changes only occurred in DA with European ancestry. No consistent positive or negative associations were found among DA samples unless an interaction between the polymorphisms and genetic ancestry was taken into account.

CONCLUSION

PTGIS and TFAP2B polymorphisms were associated with consistent changes in DA gene expression when present in fetuses with European ancestry.

IMPACT

DNA polymorphisms in PTGIS and TFAP2B have been identified as risk factors for patent ductus arteriosus (PDA) in a population composed primarily of preterm infants with European genetic ancestry but not in more genetically diverse populations. The same PTGIS and TFAP2B polymorphisms are associated with changes in ductus gene expression when present in ductus from fetuses with European genetic ancestry. No consistent associations with gene expression can be found unless an interaction between the polymorphisms and genetic ancestry is taken into account.

Novel drug targets for ductus arteriosus manipulation: Looking beyond prostaglandins

Forty years ago, non-steroidal anti-inflammatory drugs were first reported to decrease systemic prostaglandin levels and promote ductus arteriosus (DA) closure. And yet, prolonged patency of the DA (PDA) remains a significant clinical problem, complicated by imperfect therapies and wide variations in treatment strategy. There are few pharmacology-based tools available for treating PDA (indomethacin, ibuprofen, and acetaminophen), or for maintaining DA patency (PGE₁) as is needed to facilitate corrective surgery for ductus-dependent congenital heart defects. Unfortunately, all of these treatments are inefficient and are associated with concerning adverse effects. This review highlights novel potential DA drug targets that may expand our therapeutic repertoire beyond the prostaglandin pathway.

Identification of differentially regulated genes in human patent ductus arteriosus

In order to identify differentially expressed genes that are specific to the ductus arteriosus, 18 candidate genes were evaluated in matched ductus arteriosus and aortic samples from infants with coarctation of the aorta. The cell specificity of the gene's promoters was assessed by performing transient transfection studies in primary cells derived from several patients. Segments of ductus arteriosus and aorta were isolated from infants requiring repair for coarctation of the aorta and used for mRNA quantitation and culturing of cells. Differences in expression were determined by quantitative PCR using the ΔΔCt method. Promoter regions of six of these genes were cloned into luciferase reporter plasmids for transient transfection studies in matched human ductus arteriosus and aorta cells. Transcription factor AP-2b and phospholipase A2 were significantly up-regulated in ductus arteriosus compared to aorta in whole tissues and cultured cells, respectively. In transient transfection experiments, Angiotensin II type 1 receptor and Prostaglandin E receptor 4 promoters consistently gave higher expression in matched ductus arteriosus versus aorta cells from multiple patients. Taken together, these results demonstrate that several genes are differentially expressed in ductus arteriosus and that their promoters may be used to drive ductus arteriosus-enriched transgene expression.