Renal effects of angiotensin converting enzyme inhibitors: Nondiabetic chronic renal disease

Summary Based on studies in the rat remnant kidney model, it has been proposed that glomerular hypertension is responsible for the progressive nature of chronic renal disease. In that model, therapy with angiotensin converting enzyme (ACE) inhibitors reduced glomerular pressures. As a result, glomerular injury was reduced and the rate of progression of renal disease was slowed. Thus, alterations in hemodynamics may play an important role in glomerular injury. However, it is now evident that a variety of metabolic and other factors affect the progression of renal disease. Moreover, recent studies suggest that ACE inhibitors may also have beneficial effects that are independent of alterations in glomerular pressure. In humans, the glomerular hemodynamic response to renal disease cannot be measured, and it is not known whether or under which conditions glomerular capillary pressure might be elevated. Treatment with ACE inhibitors safely lowers blood pressure without adversely affecting renal function in mots patients with nondiabetic chronic renal failure. Although proteinuria and the rate of progression of renal disease may decrease in some patients, these effects are inconsistently seen. Identification of the factors that modulate this variability in response to ACE inhibition may provide new insight into the pathogenesis and treatment of progressive renal disease in humans.     

Angiotensin converting enzyme inhibition and vascular hypertrophy in hypertension

Summary The pathogenesis of hypertension is associated with a remodeling of vascular structure. Folkow has postulated that the decreased luminal area and thickened medial layer in hypertensive vessels enhances the vasoconstrictive response to vasoactive agents. It is hypothesized that this increase in vascular reactivity may serve to perpetuate hypertension. A growing body of evidence suggests that autocrineparacrine vasoactive substances and growth factors modulate vascular structure in hypertension. We speculate that therapeutic interventions that normalize blood pressure as well as reverse the vascular remodeling process may have special clinical value. The role of the paracrine renin-angiotensin system and angiotensin converting enzyme inhibitors in hypertension is discussed in this context.     

Polymorphisms of the angiotensin converting enzyme gene in early-onset and late-onset pre-eclampsia

Objective.?The aim of this study was to investigate differences in maternal and infant ACE genotypes in early-onset and later-onset pre-eclampsia/toxemia (PET).

Methods.?We conducted a case–control study of 22 cases of early-onset pre-eclampsia (before 34 weeks gestation), 38 cases of later-onset pre-eclampsia (after 34 weeks gestation), and 108 healthy controls delivered at term (38–40 weeks gestation) within a stable Caucasian population. Maternal venous blood and cord bloods were obtained for serum angiotensin converting enzyme (ACE) activity, ACE genotype, and acid–base status.

Results.?Mothers who developed early-onset PET were more likely to be homozygous for the deletion allele of the ACE genotype (DD) than mothers with late-onset PET or uncomplicated pregnancies (12/22 (55%) vs. 7/38 (18%) vs. 22/105 (21%), respectively; OR 2.96 [95% confidence intervals (CI) 1.37–6.31]. Infants of mothers with early-onset PET were more likely to be homozygous for the DD genotype than infants of mothers with late-onset PET or controls (7/19 (37%) vs. 9/36 (25%) vs. 11/78 (14%); OR 2.51 (95% CI 1.12–5.61). There were no differences in maternal or infant ACE activities in relation to onset of pre-eclampsia.

Conclusions.?Our findings suggest an association between the DD genotype of the ACE gene and early-onset but not later-onset pre-eclampsia which may give a partial explanation for the higher recurrence risk with early-onset pre-eclampsia.     

Polymorphisms of plasminogen activator inhibitor-1, angiotensin converting enzyme and coagulation factor XIII genes in patients with recurrent spontaneous abortion

We investigated polymorphisms of plasminogen activator inhibitor-1 (PAI-1), angiotensin converting enzyme (ACE ) and coagulation factor XIII (FXIII) genes and their association with recurrent spontaneous abortion (RSA) in Iranian patients and normal healthy controls. Ten (18.5%) patients were homozygote (4G/4G) for PAI-1 polymorphism, in contrast with two (2%) controls (p = 0.001). Patients with homozygote 4G mutation were significantly more prone to RSA in contrast to others (odds ratio: 11.0, 95% CI: 2.3–52.4). Nineteen (30.2%) patients and 25 (26.6%) controls were homozygote (DD) for ACE polymorphism. We observed only two patients and one control with homozygosity (34leu) for FXIII polymorphism. 4G/4G polymorphism for PAI-1 gene could be a thrombophilic mutation leading to abortion in Iranian population.     

Evidence of the involvement of caspase-1 under physiologic and pathologic cellular stress during human pregnancy: A link between the inflammasome and parturition

Objective. Caspase-1 is a component of the NALP3 inflammasome, a cytosolic multiprotein complex that mediates the processing of pro-inflammatory caspases and cytokines. The inflammasome represents the first line of defense against cellular stress and is a crucial component of innate immunity. Caspase-1 is the enzyme responsible for the cleavage and activation of interleukin (IL)-1β, which is a potent pro-inflammatory cytokine, and plays a central role in the mechanisms leading to labor (preterm and term) particularly in the context of intrauterine infection/inflammation. In addition, caspase-1 cleaves IL-18 and IL-33. The objectives of this study were to determine whether there is a relationship between amniotic fluid concentrations of caspase-1 and gestational age, parturition (term and preterm), and intra-amniotic infection/inflammation (IAI).

Study design. A cross-sectional study was conducted including 143 pregnant women in the following groups: (1) mid-trimester of pregnancy (n = 18); (2) term not in labor (n = 25); (3) term in labor (n = 28); (4) preterm labor (PTL) who delivered at term (n = 23); (5) PTL without IAI who delivered preterm (n = 32); (6) PTL with IAI who delivered preterm neonates (n = 17). Caspase-1 concentrations in amniotic fluid were determined by a specific and sensitive immunoassay. Non-parametric statistics were used for analysis.

Results. (1) Caspase-1 was detected in amniotic fluid of women at term, but in none of the mid-trimester samples. (2) Patients in labor at term had a significantly higher median amniotic fluid concentration of caspase-1 than women at term not in labor (term in labor: 10.5 pg/mL, range 0.0–666.0 vs. term not in labor: 5.99 pg/mL, range 0.0–237.4; p < 0.05). (3) Among patients with spontaneous PTL, those with IAI (median 41.4 pg/mL, range 0.0–515.0) had a significantly higher median amniotic fluid caspase-1 concentration than those without IAI who delivered preterm (median 0.0 pg/mL, range 0.0–78.4) and than those who delivered at term (median 0.0 pg/mL, range 0.0–199.5); p < 0.001 for both comparisons.

Conclusions. (1) The presence and concentration of caspase-1 in the amniotic fluid varies as a function of gestational age. (2) Women with spontaneous labor at term had a higher median caspase-1 amniotic fluid concentration than women at term without labor. This suggests that the inflammasome may be activated in spontaneous parturition at term. Since most women with labor do not have intra-amniotic infection, we propose that cellular stress during labor accounts for activation of the inflammasome. (3) Preterm labor associated with infection/inflammation was also associated with a high concentration of caspase-1, suggesting that infection may induce caspase-1 production and activation of the inflammasome. (4) The sequential activation of the inflammasome and caspase-1, leading to interleukin-1β processing and secretion, is a candidate pathway leading to the activation of the common pathway of parturition.     

ACE基因I/D和ACE2基因A9570G多态性与心房颤动的相关性研究

目的研究血管紧张素转换酶(ACE)基因I/D和血管紧张素转换酶2(ACE2)基因A9570G多态性与心房颤动(简称房颤)的相关性。方法按入院先后顺序入选305例患者,其中房颤患者148例(房颤组),基础疾病与房颤患者匹配的非房颤患者157例(对照组),通过聚合酶链反应-限制性片段长度多态性(PCR-RFLP)和基因测序方法检测两组患者的ACE基因I/Dey ACE2基因A9570G多态性的基因型。结果房颤组ACE基因I/D基因型及等位基因分布与对照组无统计学差异(P=0.841;OR=0.948,95%CI 0.680~1.322,P=0.755),且不同I/D基因型患者的左房前后径和右房横径大小均无统计学差异(P=0.887,P=0.664)。在男性人群中,ACE2基因A9570G基因型分布与对照组比较无统计学差异(OR=1.631,95%CI 0.880~3.023,P=0.119),但在男性房颤患者中,G基因型的左房前后径及右房横径(分别为40.1±6.4、40.1±5.7mm)明显大于A基因型患者(分别为37.0±4.4、36.5±4.4mm),差异有统计学意义(P=0.028,P=0.010);在女性人群中,ACE2基因A9570G基因型及等位基因分布与对照组比较均无统计学差异(P=0.286;OR=1.415,95%CI 0.885~2.264,P=0.146),在女性房颤患者中,ACE2基因A9570G不同基因型的左房前后径和右房横径大小均无统计学差异(P=0.924,P=0.432)。结论 ACE基因I/D和ACE2基因A9570G多态性与房颤的相关性均不明显。但在男性房颤患者中,ACE2基因A9570G多态性中G基因型可能是预测心房增大的一个危险因子。     

Angiotensin converting enzyme inhibitor-induced angioedema: a report of two cases

Angioedema is a rare but potentially fatal side effect of angiotensin converting enzyme (ACE) inhibitors. We report for the first time, two children with systemic lupus erythematosus who developed acute angioedema after the long-term use of enalapril. Prompt recognition and appropriate management of ACE-induced angioedema prevented life-threatening complications. This report highlights the potential risks of angioedema associated with the use of ACE inhibitors in children. Patients should be advised to seek medical treatment immediately if they experience swelling of the face, neck, or tongue, and especially if they have trouble breathing, speaking, or swallowing. Received: 12 March 1999 / Revised: 8 June 1999 / Accepted: 8 June 1999     

Interplay between RAS and opioids: Opening the Pandora of complexities

Angiotensin and endogenous opioids are important bioactive neuropeptides, which are widely distributed in the brain and peripheral regions to produce diverse biological and neurobiological activities. An endogenous opioid system includes proopiomelanocortin-derived enkephalin, dynorphin and endorphin that act on their specific receptors such as delta (δ), kappa (κ) and mu (μ) receptors. Research evidence demonstrates significant positive as well as negative interactions between renin angiotensin system (RAS) and endogenous opioids in the brain and periphery. The diverse actions of Ang II are possibly mediated indirectly through endogenous opioids, while opioids are also shown to activate RAS components suggesting the up-regulation of each system in concern with each other. On the contrary, there are reports suggesting a negative correlation between RAS and opioid system. Research evidence also supports the notion that Ang II acts as anti-opioid peptide to decrease the actions of opioids. Moreover, opioids-induced decline in angiotensin release and functioning has also been reported. Co-administration of ACE inhibitors with opioids exhibits significant interactions possibly due to decreased metabolism of opioids leading to potentiation of their actions. The present review describes the complexities of positive and negative interactions between RAS and opioids along with possible mechanisms responsible for these interactions.     

The Effects of Angiotensin Converting Enzyme Inhibitors on Potassium Homeostasis in Dialysis Patients With and Without Residual Renal Function

Hyperkalemia is exacerbated by angiotensin converting enzyme inhibitors (ACE‐I). Distal potassium (K⁺) secretion is negligible in anuric patients. ACE‐I therapy may reduce renal, peritoneal, and colonic K⁺ losses. We examined the effect of ACE‐I therapy on serum, urinary, and dialysate K⁺ in a cross‐section of peritoneal and hemodialysis patients. Serum, 24‐h urine K⁺, and peritoneal dialysate excretion K⁺ levels were measured and the results were compared in the various dialysis and treatment groups. Eighty‐one hemodialysis (HD) and 32 peritoneal dialysis (PD) patients were included. Serum K⁺ in HD patients with no residual renal function (RRF) was higher in those receiving ACE‐I therapy (P = 0.02). Serum K⁺ levels in HD patients receiving ACE‐I treatments with RRF was similar to that in oligoanuric HD patients not receiving an ACE‐I. Urinary K⁺ excretion was significantly reduced in those on ACE‐I therapy versus those not on an ACE‐I (P < 0.05). Mean serum K⁺ was lower in PD versus HD patients (P < 0.05). PD patients with no RRF on ACE‐I therapy had higher serum K⁺ concentrations (P = 0.002) and dialysate K⁺ excretion was lower (P = 0.05), in comparison with PD patients not on an ACE‐I. PD patients with RRF on ACE‐I therapy had higher serum K⁺ concentrations compared with those not on ACE‐I therapy (P = 0.03). Both urinary and dialysate K⁺ excretion were reduced (P = 0.001 and P = 0.002, respectively). ACE‐I therapy increases serum K⁺ concentration in dialysis patients. PD patients have relatively lower serum K⁺ levels compared with HD patients. In PD patients, ACE‐I therapy reduces dialysate K⁺. These changes may result from reduced peritoneal movement of K⁺.