Impact of mineralocorticoid receptor blockade with direct renin inhibition in angiotensin II-dependent hypertensive mice.

It has been suggested that aldosterone breakthrough during treatment with a type 1 angiotensin II receptor (AT1R) blocker (ARB) may be an important risk factor for the progression of renal and cardiovascular disease. We examined whether the direct renin inhibitor, aliskiren caused aldosterone breakthrough in angiotensin II (Ang II)-dependent hypertensive mice. The effect of combination therapy with aliskiren and eplerenone was compared with that of therapy using renin-angiotensin system (RAS) blockade. Tsukuba hypertensive mice were treated for 12 weeks with aliskiren (30 mg/kg/day, i.p), candesartan (5 mg/kg/day, p.o), eplerenone (100 mg/kg/day, p.o) aliskiren and candesartan, aliskiren and eplerenone or candesartan and eplerenone. Blood pressure, urinary aldosterone and angiotensinogen (AGTN) excretion; plasma endothelin-1 concentration; kidney weight; urinary albumin excretion (UAE); glomerular injury; and renal messenger RNA (mRNA) levels for transforming growth factor (TGF)-ß1, plasminogen activator inhibitor (PAI)-1, angiotensin-converting enzyme (ACE) and AT1R were measured. Combination therapy with aliskiren and candesartan caused a further decrease in blood pressure (p < 0.05) compared with either agent alone. Urinary aldosterone excretion was decreased significantly by 4 weeks of treatment with aliskiren or candesartan (p < 0.05). However, it was increased again by treatment with candesartan or aliskiren for 12 weeks. Combination therapy with aliskiren and eplerenone significantly decreased UAE, the glomerulosclerosis index, and PAI-1 and TGF-ß1 mRNA levels compared with all other therapies (p < 0.05). Treatment with aliskiren decreased urinary aldosterone excretion at 4 weeks and increased it at 12 weeks. Combination therapy with a direct renin inhibitor and a mineralocorticoid receptor blocker may be effective for the prevention of renal injury in Ang II-dependent hypertension.

Novel promoter I.8 and promoter usage in the CYP19 (aromatase) gene.

To date, 10 promoters were reported to regulate the expression of the human aromatase (CYP19) gene, giving rise to transcripts with an identical coding region but tissue-specific first exons comprising unique 5'-untranslated regions. We describe the identification and characterization of a new CYP19 exon I, designated exon I.8, in a 5'-rapid amplification of complementary DNA ends-generated library of human THP-1 monocytic cells. A construct containing exon I.8 and its 5'-flanking sequence was sufficient to drive transcription in THP-1 cells. This novel promoter was located approximately 2-kb upstream of promoter I.4 and approximately 75-kb upstream of the common splice junction. We detected several I.8-containing splice variants, 2 of which also contained a sequence from exon I.4. Analysis of human tissues revealed a unique pattern of promoter I.8 usage. The placenta contained the highest level of I.8-specific transcripts. This work underscores the complexity of the mechanisms that regulate normal and pathologic aromatase expression.