No extra-adrenal aldosterone production in various human cell lines

Abstract

Extra-adrenal de-novo aldosterone (Aldo) production has been described inconsistently. Systematic data based upon state-of-the-art technology including validated controls are sparse. We hypothesized that aldosterone synthase (CYP11B2) expression and de-novo Aldo production are absent in non-adrenal human cell lines, either immortalized cell lines or commercially available primary cell lines, including peripheral blood mononuclear cells (PBMCs) of individuals without and with primary hyperaldosteronism (PA). CYP11B2-transfected COS-7 and endogenous CYP11B2 expressing adrenal H295R cells served as positive controls. Various well-characterized, purchased, immortalized (BeWo, HEK293, HTR-8/SVneo, JEG-3) and primary (HAEC, HLEC, HRGEC, HRMC, HUAEC, HUVEC, PBMC) cell lines as well as self-isolated PBMCs from PA patients (n=5) were incubated with the steroid hormone substrates progesterone, deoxycorticosterone, corticosterone or 18-OH-corticosterone with and without Ang II for 24h to assess CYP11B2 enzymatic activity. CYP11B2 expression was analyzed by Real-time PCR and liquid chromatography-mass spectrometry (LC-MS) was used to quantify Aldo production. Pronounced CYP11B2 mRNA expression and Aldo production were observed in both positive controls, which followed an incremental time course. Neither substrates alone nor co-incubation with Ang II significantly stimulated CYP11B2 expression or Aldo production in various immortalized and primary cell lines and PBMCs of PA patients. These results strongly support the absence of a relevant de-novo extra-adrenal Aldo production in non-adrenal cells including, blood mononuclear cells irrespective of the absence or presence of autonomous adrenal Aldo production.