Prenatal diagnosis and treatment for fetal angiotensin converting enzyme deficiency.

OBJECTIVE: To elucidate an etiology in a case with persistent oligohydramnios by prenatal diagnosis and actively treat the case to achieve good prognosis. METHODS: We performed whole exome sequencing (WES) of DNA from the fetus and parents. Serial amnioinfusions were conducted until birth. Pressors were required to maintain normal blood pressure. The infant angiotensin-converting enzyme (ACE) activity, angiotensin II (Ang II, a downstream product of ACE), and compensatory enzymes (CEs) activities were measured. Compensatory enzyme activities in plasma from age-matched healthy controls were also detected. RESULTS: We identified a fetus with a severe ACE mutation prenatally. The infant was born prematurely without pulmonary dysplasia. Hypotension and anuria resolved spontaneously. He had almost no ACE activity, but his Ang II level and CE activity exceeded the upper limit of the normal range and the upper limit of the 95% confidence interval of controls, respectively. His renal function also largely recovered. CONCLUSION: Fetuses with ACE mutations can be diagnosed prenatally through WES. Serial amnioinfusion permits the continuation of pregnancy in fetal ACE deficiency. Compensatory enzymes for defective ACE appeared postnatally. Renal function may be spared by preterm delivery; furthermore, for postnatal vasopressor therapy to begin, improving renal perfusion pressure before nephrogenesis has been completed.

Intracellular Angiotensin II Stimulation of Sodium Transporter Expression in Proximal Tubule Cells via AT1 (AT1a) Receptor-Mediated, MAP Kinases ERK1/2- and NF-кB-Dependent Signaling Pathways.

The current prevailing paradigm in the renin-angiotensin system dictates that most, if not all, biological, physiological, and pathological responses to its most potent peptide, angiotensin II (Ang II), are mediated by extracellular Ang II activating its cell surface receptors. Whether intracellular (or intracrine) Ang II and its receptors are involved remains incompletely understood. The present study tested the hypothesis that extracellular Ang II is taken up by the proximal tubules of the kidney by an AT1 (AT1a) receptor-dependent mechanism and that overexpression of an intracellular Ang II fusion protein (ECFP/Ang II) in mouse proximal tubule cells (mPTC) stimulates the expression of Na+/H+ exchanger 3 (NHE3), Na+/HCO3- cotransporter, and sodium and glucose cotransporter 2 (Sglt2) by AT1a/MAPK/ERK1/2/NF-kB signaling pathways. mPCT cells derived from male wild-type and type 1a Ang II receptor-deficient mice (Agtr1a-/-) were transfected with an intracellular enhanced cyan fluorescent protein-tagged Ang II fusion protein, ECFP/Ang II, and treated without or with AT1 receptor blocker losartan, AT2 receptor blocker PD123319, MEK1/MEK2 inhibitor U0126, NF-кB inhibitor RO 106-9920, or p38 MAP kinase inhibitor SB202196, respectively. In wild-type mPCT cells, the expression of ECFP/Ang II significantly increased NHE3, Na+/HCO3-, and Sglt2 expression (p < 0.01). These responses were accompanied by >3-fold increases in the expression of phospho-ERK1/2 and the p65 subunit of NF-кB (p < 0.01). Losartan, U0126, or RO 106-9920 all significantly attenuated ECFP/Ang II-induced NHE3 and Na+/HCO3- expression (p < 0.01). Deletion of AT1 (AT1a) receptors in mPCT cells attenuated ECFP/Ang II-induced NHE3 and Na+/HCO3- expression (p < 0.01). Interestingly, the AT2 receptor blocker PD123319 also attenuated ECFP/Ang II-induced NHE3 and Na+/HCO3- expression (p < 0.01). These results suggest that, similar to extracellular Ang II, intracellular Ang II may also play an important role in Ang II receptor-mediated proximal tubule NHE3, Na+/HCO3-, and Sglt2 expression by activation of AT1a/MAPK/ERK1/2/NF-kB signaling pathways.

20-Hydroxyeicosatetraenoic acid contributes to the inhibition of K+ channel activity and vasoconstrictor response to angiotensin II in rat renal microvessels.

The present study examined whether 20-hydroxyeicosatetraenoic acid (HETE) contributes to the vasoconstrictor effect of angiotensin II (ANG II) in renal microvessels by preventing activation of the large conductance Ca(2+)-activated K(+) channel (KCa) in vascular smooth muscle (VSM) cells. ANG II increased the production of 20-HETE in rat renal microvessels. This response was attenuated by the 20-HETE synthesis inhibitors, 17-ODYA and HET0016, a phospholipase A2 inhibitor AACOF3, and the AT1 receptor blocker, Losartan, but not by the AT2 receptor blocker, PD123319. ANG II (10(-11) to 10(-6) M) dose-dependently decreased the diameter of renal microvessels by 41 ± 5%. This effect was blocked by 17-ODYA. ANG II (10(-7) M) did not alter KCa channel activity recorded from cell-attached patches on renal VSM cells under control conditions. However, it did reduce the NPo of the KCa channel by 93.4 ± 3.1% after the channels were activated by increasing intracellular calcium levels with ionomycin. The inhibitory effect of ANG II on KCa channel activity in the presence of ionomycin was attenuated by 17-ODYA, AACOF3, and the phospholipase C (PLC) inhibitor U-73122. ANG II induced a peak followed by a steady-state increase in intracellular calcium concentration in renal VSM cells. 17-ODYA (10(-5) M) had no effect on the peak response, but it blocked the steady-state increase. These results indicate that ANG II stimulates the formation of 20-HETE in rat renal microvessels via the AT1 receptor activation and that 20-HETE contributes to the vasoconstrictor response to ANG II by blocking activation of KCa channel and facilitating calcium entry.

Antifibrotic effect of Ac-SDKP and angiotensin-converting enzyme inhibition in hypertension.

OBJECTIVE: N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a potent natural inhibitor of hematopoietic stem cell proliferation which is degraded mainly by angiotensin-converting enzyme (ACE). In vitro, Ac-SDKP inhibits collagen production by cardiac fibroblasts; while in vivo it blocks collagen deposition in the left ventricle (LV) of rats with hypertension or myocardial infarction (MI). In addition, it reportedly prevents and reverses macrophage infiltration in the LV of rats with MI. We tested the hypothesis that when Ac-SDKP is infused at doses that cause plasma concentrations similar to those observed after ACE inhibition, it mimics the anti-inflammatory and antifibrotic effects of ACE inhibitors (ACEi) in the heart, and, further, that these effects are independent of changes in blood pressure. DESIGN AND METHODS: Rats were divided into five groups: (1) controls, (2) Ang II (750 microg/kg per day, s.c.), (3) Ang II + captopril (100 mg/kg per day in drinking water), (4) Ang II + Ac-SDKP (400 microg/kg per day, s.c.), and (5) Ang II + Ac-SDKP (800 microg/kg per day, s.c.). We measured LV cell proliferation, inflammatory cell infiltration, cytokine expression, hypertrophy and fibrosis. RESULTS: Plasma Ac-SDKP was five-fold higher in rats given ACEi and four- and ten-fold higher in rats given 400 and 800 microg/kg per day Ac-SDKP, respectively. ACEi significantly decreased Ang II-induced cell proliferation (Ki-67), LV macrophage/mast cell infiltration, transforming growth factor-beta, connective tissue growth factor and collagen deposition without affecting hypertension, LV hypertrophy or myocyte cross-sectional area, and these effects were mimicked by exogenous Ac-SDKP (400 microg/kg per day) which raised plasma Ac-SDKP to levels similar to ACEi. BP was not decreased by either ACEi or Ac-SDKP. CONCLUSIONS: We concluded that Ac-SDKP may be an important mediator of the anti-inflammatory and antifibrotic effects of ACEi in hypertension independent of its hemodynamic effects.

Intrarenal AT(1) receptor and ACE binding in ANG II-induced hypertensive rats.

The intrarenal expression of angiotensin II (ANG II) type 1 (AT(1)) receptors and angiotensin-converting enzyme (ACE) was determined in ANG II-induced hypertensive rats (80 ng/min; 2 wk). Systolic blood pressure averaged 184 +/- 3 and 125 +/- 1 mmHg in ANG II-infused compared with Sham rats on day 12. Total kidney AT(1) receptor protein levels were not altered significantly. AT(1) receptor binding mapped by quantitative in vitro autoradiography was significantly decreased in glomeruli (172 +/- 25 vs. 275 +/- 34 disintegrations. min(-1). mm(-2)) and the inner stripe of the outer medulla (121 +/- 17 vs. 178 +/- 19 disintegrations. min(-1). mm(-2)), but not proximal convoluted tubules (48 +/- 9 vs. 58 +/- 6 disintegrations. min(-1). mm(-2)) of ANG II-infused compared with Sham rats. Proximal tubule ACE binding was significantly augmented (132 +/- 4 vs. 97 +/- 3 disintegrations. min(-1). mm(-2)) in ANG II-infused rats. In summary, during ANG II-induced hypertension, glomeruli and inner stripe of the outer medulla have reduced AT(1) receptor binding. Proximal convoluted tubules exhibit maintained AT(1) receptor density and increased ACE binding, which together with the elevated ANG II levels suggest that ANG II exerts a sustained influence on tubular reabsorption and consequently contributes to the development and maintenance of ANG II-dependent hypertension.