Rise in antifibrotic and decrease in profibrotic microRNA protect the heart against fibrosis during pregnancy: A preliminary study

Background: Physiological pregnancy is associated with volume overload. Unlike cardiac pathologies linked with volume overload, such as mitral or aortic regurgitation, pregnancy is thought to be unrelated to fibrosis of the heart. However, changes in the cardiac extracellular matrix during pregnancy remain poorly understood.

Objectives: The aim of the study was to examine the expression of 11 microRNAs associated with cardiac fibrosis (miR-21, miR-26a, miR-26b-5p, miR-29b-3p, miR-29c-3p, miR-101a, miR-146a, miR-208a, miR-223 and miR-328) during pregnancy and to compare them with a healthy control group.

Material and methods: Six women in singleton pregnancy (30-36 weeks) and 6 non-pregnant women as a control group were included in the study. Each woman underwent an echocardiographic examination, and had blood pressure on both arms measured and a blood sample taken. MicroRNAs expression was analyzed using Custom TaqMan® Array MicroRNA Cards (Applied Biosystems, Foster City, USA).

Results: Median age of the pregnant women was 34 years (range 25-39 years) and of the control group 32 years (range 29-43 years). Median week of pregnancy was 34 years (range 31-36 years). Most of the examined microRNAs had a lower expression in the pregnancy group (fold change 1.0).

Conclusions: In the 3rd trimester of physiological pregnancy, there is a 244% increase in expression of miR-101a and a decrease by 73% in expression of miR-328. Both of these changes can protect against fibrosis during volume overload occurring in physiological pregnancy.