Oral Presentation ESA-SRB-APEG-NZSE 2022

Primary aldosteronism (PA), the most common endocrine cause of hypertension, is associated with increased cardiovascular risk compared with essential hypertension. The diagnosis of PA currently relies on measurements of plasma aldosterone and renin levels which can be compromised by patient- or assay-related issues and relies on arbitrary thresholds. A cellular marker that reflects excess endogenous aldosterone activity could enhance the diagnostic process. Mineralocorticoid receptor (MR) activation in macrophages has previously been shown to play a key role in mediating cardiovascular injury¹. Macrophage precursors, the monocytes, also express MR and can be easily isolated from circulation. We therefore sought to identify unique transcriptomic markers of aldosterone excess in peripheral blood monocytes.

Monocytes were isolated from nine male patients with unilateral PA before and 3 months after curative adrenalectomy. Each patient’s post-adrenalectomy samples served as the control for comparison with the pre-adrenalectomy samples. RNA sequencing (RNA-seq) was performed on monocyte RNA samples to identify differentially expressed genes (DEGs), followed by evaluation using a second method by real-time quantitative PCR (RT-qPCR).

Distinct clustering of gene expression was observed between the “before” and “after-surgery” samples (Figure) with 1679 significantly differentially expressed (false discovery rate <0.05). The top 26 DEGs were selected for evaluation by RT-qPCR. Differences were observed in the relative expression of phosphoglycerate mutase 1 (PGAM1), ferrochelatase (FECH), and nuclear enriched abundant transcript 1 (NEAT1) genes pre- and post-surgery. The ratios of the relative expression of these genes accentuated the difference between the before- and after-surgery samples.

In conclusion, differential gene expression was found between monocytes of patients with unilateral PA before and after adrenalectomy. Further validation studies are needed in female patients and those with bilateral PA and essential hypertension. These transcriptomic markers or their ratios have the potential to serve as novel biomarkers of aldosterone excess.