Downregulation of exosomal miR-192-5p and miR-204-5p in subjects with nonclassic apparent mineralocorticoid excess.

BACKGROUND: The "nonclassic" apparent mineralocorticoid excess (NC-AME) has been identified in approximately 7% of general population. This phenotype is characterized by low plasma renin activity (PRA), high serum cortisol (F) to cortisone (E) ratio, low cortisone, high Fractional Excretion of potassium (FEK) and normal-elevated systolic blood pressure (SBP). An early detection and/or identification of novel biomarkers of this phenotype could avoid the progression or future complications leading to arterial hypertension. Isolation of extracellular vesicles, such as exosomes, in specific biofluids support the identification of tissue-specific RNA and miRNA, which may be useful as novel biomarkers. Our aim was to identify miRNAs within urinary exosomes associated to the NC-AME phenotype. METHODS: We perform a cross-sectional study in a primary care cohort of 127 Chilean subjects. We measured BP, serum cortisol, cortisone, aldosterone, PRA. According to the previous reported, a subgroup of subjects was classified as NC-AME (n = 10). Urinary exosomes were isolated and miRNA cargo was sequenced by Illumina-NextSeq-500. RESULTS: We found that NC-AME subjects had lower cortisone (p < 0.0001), higher F/E ratio (p < 0.0001), lower serum potassium (p = 0.009) and higher FEK 24 h (p = 0.03) than controls. We found miR-204-5p (fold-change = 0.115; p 0.001) and miR-192-5p (fold-change = 0.246; p 0.03) are both significantly downregulated in NC-AME. miR-192-5p expression was correlated with PRA (r = 0.45; p 0.028) and miR-204-5p expression with SBP (r = - 0.48, p 0.027) and F/E ratio (r = - 0.48; p 0.026). CONCLUSIONS: These findings could support a potential role of these miRNAs as regulators and novel biomarkers of the NC-AME phenotype.

11ß-Hydroxysteroid dehydrogenase type-2 and type-1 (11ß-HSD2 and 11ß-HSD1) and 5ß-reductase activities in the pathogenia of essential hypertension.

Cortisol availability is modulated by several enzymes: 11ß-HSD2, which transforms cortisol (F) to cortisone (E) and 11ß-HSD1 which predominantly converts inactive E to active F. Additionally, the A-ring reductases (5α- and 5ß-reductase) inactivate cortisol (together with 3α-HSD) to tetrahydrometabolites: 5αTHF, 5ßTHF, and THE. The aim was to assess 11ß-HSD2, 11ß-HSD1, and 5ß-reductase activity in hypertensive patients. Free urinary F, E, THF, and THE were measured by HPLC-MS/MS in 102 essential hypertensive patients and 18 normotensive controls. 11ß-HSD2 enzyme activity was estimated by the F/E ratio, the activity of 11ß-HSD1 in compare to 11ß-HSD2 was inferred by the (5αTHF + 5ßTHF)/THE ratio and 5ß-reductase activity assessed using the E/THE ratio. Activity was considered altered when respective ratios exceeded the maximum value observed in the normotensive controls. A 15.7% of patients presented high F/E ratio suggesting a deficit of 11ß-HSD2 activity. Of the remaining 86 hypertensive patients, two possessed high (5αTHF + 5ßTHF)/THE ratios and 12.8% had high E/THE ratios. We observed a high percentage of alterations in cortisol metabolism at pre-receptor level in hypertensive patients, previously misclassified as essential. 11ß-HSD2 and 5ß-reductase decreased activity and imbalance of 11ß-HSDs should be considered in the future management of hypertensive patients.

Two elderly patients with mineralocorticoid excess due to 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2) impairment.

A 75-year-old woman had a low circulating level of aldosterone, despite the mineralocorticoid excess state. These abnormalities were improved by spironolactone administration. The distinct elevation of urinary cortisol/cortisone ratio revealed 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) impairment. Moreover, slight but distinct elevation of the ratio was found in a 95-year-old woman with normotension and normopotassemia. The mineralocorticoid excess state with reduced aldosterone level appeared following with vomiting and diarrhea, exaggerating asymptomatic impairment of 11beta-HSD2 to induce apparent mineralocorticoid excess (AME)-like condition.