Chromogranin A demonstrates higher expression in preeclamptic placentas than in normal pregnancy

Abstract

Background: Although preeclampsia has long been recognized as a condition affecting late pregnancy, little is known of its pathogenesis or treatment. The placenta releases a number of hormones and molecules that influence the course of pregnancy, one of which is chromogranin A, a soluble protein secreted mainly from the chromaffin cells of the adrenal medulla. Its role in pregnancy and pregnancy-related disorders remains unclear. Therefore, the main aim of the proposed study is to determine whether chromogranin A is related with the occurrence of preeclampsia.

Methods: Placental samples were collected from 102 preeclamptic patients and 103 healthy controls, and Chromogranin A gene (CHGA) expression was measured using real-time RT-PCR, The RT-PCR results were verified on the protein level using ELISA. The normal distribution of the data was tested using the Shapiro-Wilk test. The clinical and personal characteristics of the groups were compared using the Student's t-test for normally-distributed data, and the χ² test for categorical variables. The Mann-Whitney U test was used for non-normally distributed data. As the log- transformation was not suitable for the given outcomes, the Box- Cox Transformation was used to normalize data from ELISA tests and CHGA expression. Values of P < .05 were considered statistically significant.

Results: Chromogranin A gene expression was found to be significantly higher in the study group than in controls. Protein analyses showed that although the CgA concentration in placental samples did not differ significantly, the catestatin (CST) level was significantly lower in samples obtained from women with preeclampsia, according to the controls.

Conclusions for practice: This study for the first time reveals that chromogranin A gene expression level is associated with preeclampsia. Moreover, the depletion in catestatin level, which plays a protective role in hypertension development, might be a marker of developing preeclampsia. Further studies may unravel role of Chromogranin A in the discussed disease.

Keywords: Catestatin; Chromogranin a; Placenta; Preeclampsia; Pregnancy; Pregnancy hypertension.

Fig. 1

Comparison of relative CHGA gene expression level between study and control group. The values are presented as mean ± SD after Box-Cox Transformation. p-vaule was calculated using the Student’s t-test

Fig. 2

Comparison of relative CHGA gene expression level between study groups divided to early and late PE, and control group. The values are presented as mean ± SD after Box-Cox Transformation. p- value was calculated using One-way ANOVA with Turkey’s post hoc test for various number of cases in each group * Denotes statistical significance

Fig. 3

Comparison of the CST level (a, c) and CHGA expression level (b, d) between the study and control groups in pregnancies with female (a, b) and male foetuses (c,d). The values are presented as mean ± SD after Box-Cox Transformation. p-value was calculated using the Student’s t-test