Gene-Gene Interactions Among PRKCA, NOS3 and BDKRB2 Polymorphisms Affect the Antihypertensive Effects of Enalapril.

Protein kinase C (PKC) signalling is critically involved in the control of blood pressure. Angiotensin-converting enzyme inhibitors (ACEi) affect PKC expression and activity, which are partially associated with the responses to ACEi. We examined whether PRKCA (protein kinase C, alpha) polymorphisms (rs887797 C>T, rs1010544 T>C and rs16960228 G>A), or haplotypes, and gene-gene interactions within the ACEi pathway affect the antihypertensive responses in 104 hypertensive patients treated with enalapril as monotherapy. Patients were classified as poor responders (PR) or good responders (GR) to enalapril if their changes in mean arterial pressure were lower or higher than the median value, respectively. Multi-factor dimensionality reduction was used to characterize interactions among PRKCA, NOS3 (nitric oxide synthase 3) and BDKRB2 (bradykinin receptor B2) polymorphisms. The TC+CC genotypes for the rs1010544 polymorphism were more frequent in GR than in PR (p = 0.037). Conversely, the GA+AA genotypes for the rs16960228 polymorphism, and the CTA haplotype, were more frequent in PR than in GR (p = 0.040 and p = 0.008, respectively). Moreover, the GG genotype for the PRKCA rs16960228 polymorphism was associated with PR or GR depending on the genotypes for the rs2070744 (NOS3) and rs1799722 (BDKRB2) polymorphisms (p = 0.012). Our results suggest that PRKCA polymorphisms and gene-gene interactions within the ACEi pathway affect the antihypertensive responses to enalapril.

Endothelial nitric oxide synthase tagSNPs influence the effects of enalapril in essential hypertension.

The antihypertensive effects of angiotensin-converting enzyme inhibitors (ACEi) are associated with up-regulation of endothelial nitric oxide synthase (NOS3) activity. This mechanism may explain how polymorphisms in NOS3 gene affect the antihypertensive responses to ACEi. While clinically relevant NOS3 polymorphisms were previously shown to affect the antihypertensive responses to enalapril, no study has tested the hypothesis that NOS3 tagSNPs influence the antihypertensive effects of this drug. We examined whether the NOS3 tagSNPs rs3918226, rs3918188, and rs743506, and their haplotypes, affect the antihypertensive responses to enalapril in 101 patients with essential hypertension. Subjects were prospectively treated only with enalapril for 8 weeks. Genotypes were determined by Taqman(®) allele discrimination assay and real-time polymerase chain reaction (PCR) and haplotype frequencies were estimated. We compared the effects of NOS3 tagSNPs on changes in blood pressure after enalapril treatment. To confirm our findings, multiple linear regression analysis was performed adjusting for age, gender, ethnicity, and alcohol consumption. We found that hypertensive patients carrying the AA genotype for the tagSNP rs3918188 showed lower decreases in blood pressure in response to enalapril. Moreover, the TCA haplotype was associated with improved decreases in blood pressure in response to enalapril compared with the CAG haplotype. Adjustment for covariates in multiple linear regression analysis did not change these effects. In addition, when patients were stratified according to the dose of enalapril used, we found that the carries of the T allele for the functional tagSNP rs3918226 showed more intense decreases in blood pressure in response to enalapril 20 mg/day. Our findings suggest that NOS3 tagSNPs influence the effects of enalapril in essential hypertension.

Association of Mineralocorticoid Receptor Polymorphism I180V With Left Ventricular Hypertrophy in Resistant Hypertension.

OBJECTIVES: Genetic polymorphisms on mineralocorticoid receptor gene (NC3C2) are associated with variability of mineralocorticoid receptor (MR) function and cardiovascular implications. We sought to investigate whether I180V (rs5522) and MRc.-2G_C (rs2070951) polymorphisms in NR3C2 gene are associated with resistance to antihypertensive treatment and target-organ damage in resistant hypertensive (RHTN) patients. METHODS: One hundred and eighty-one RHTN and 122 mild to moderate hypertensive (HTN) patients were enrolled in this study. Genotypes were obtained by allelic discrimination assay using real-time polymerase chain reaction. We determined pulse wave velocity (PWV), microalbuminuria, and left ventricular mass index to assess target-organ damage. We compared clinical and laboratorial characteristics of AA vs. G carriers for rs5522 and AC vs. GG vs. CG for rs2070951. RESULTS: We did not found differences in allele, genotype, and haplotype frequencies for both polymorphisms between HTN and RHTN subjects. We found increased levels of aldosterone and ambulatory blood pressure (BP) in G carriers only for rs5522. Left ventricular hypertrophy (LVH) was more prevalent in G carriers than AA homozygous for rs5522 but not for rs2070951 in RHTN. On the other hand, microalbuminuria and PWV were similar among genotypes for both polymorphisms. No differences were observed between the haplotypes, except for higher aldosterone concentration in GG compared to AG and AC haplotypes. CONCLUSION: Our study suggests that rs5522 polymorphism might affect cardiac remodeling and aldosterone levels in RHTN subjects.

Effects of angiotensin-converting enzyme inhibition on leptin and adiponectin levels in essential hypertension.

Activation of the renin-angiotensin-aldosterone system (RAAS) and abnormal adipokine levels are biological alterations that affect blood pressure regulation and interact to link hypertension, obesity and metabolic diseases. While imbalanced levels of hormones produced by adipocytes including hypo-adiponectinaemia and hyperleptinaemia were reported in hypertension, little is known about how antihypertensive therapy affects these alterations. This study aimed to evaluate the effects of enalapril on plasma adiponectin and leptin levels in hypertensive individuals. Thirty-seven untreated hypertensive patients were prospectively treated with enalapril for 8 weeks. Blood samples were collected at baseline and after the treatment with enalapril. Plasma adiponectin and leptin levels were measured by enzyme-linked immunoassay. We found significant increases in adiponectin levels after enalapril treatment (5.4 ± 3.7 versus 6.0 ± 4.5 µg/mL, mean ± S.D., p = 0.04). Conversely, leptin levels were unchanged (18.0 ± 14.7 versus 18.4 ± 14.8 ng/mL, mean ± S.D., p = 0.31). Multiple linear regression revealed that baseline leptin is a significant predictor of systolic blood pressure reduction (ß=0.269, p = 0.01) in hypertensive individuals treated with enalapril. While enalapril increases adiponectin levels in hypertensive individuals, baseline leptin levels predict blood pressure reduction in response to this therapy. These findings support the idea of an important relationship between RAAS and adipose tissue in hypertension and suggest that enalapril improves the adipokine profile, possibly allowing beneficial effects to overweight or obese hypertensive individuals.

Comprehensive evaluation of the effects of enalapril on matrix metalloproteinases levels in hypertension.

PURPOSE: Angiotensin-converting enzyme inhibitors (ACEi) may downregulate matrix metalloproteinases (MMPs). We examined whether enalapril affects MMP-2, MMP-8, and MMP-9 levels and activity, and their endogenous inhibitors (tissue inhibitors of MMPs, TIMP-1 and TIMP-2) levels in hypertensive patients. Moreover, we assessed the effects of enalaprilat on MMP-9 and TIMP-1 secretion by human endothelial cells (HUVECs). METHODS: Thirty-eight hypertensive patients received enalapril for 8 weeks and were compared with thirty-eight normotensive controls. Blood samples were collected at baseline and after treatment. Plasma ACE activity was determined by a fluorimetric assay. Plasma MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 were measured by ELISA and gelatin zymography. A fluorogenic peptide cleavage assay was used to measure MMP activity. HUVECs cells were stimulated by phorbol-12-myristate-13-acetate (PMA) and the effects of enalaprilat (10(-10) to 10(-6) M) on MMP-9 and TIMP-1 levels were determined. RESULTS: Enalapril decreased blood pressure and ACE activity in hypertensive patients (P < 0.05), but had no effects on plasma MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 levels, or MMP activity. Enalaprilat had no effects on PMA-induced increases in MMP-9 and TIMP-1 secretion by HUVECs or on MMP activity. CONCLUSIONS: We show consistent evidence, both in vivo and in vitro, that enalapril does not affect MMPs and TIMPs levels in hypertensive patients.

Consistent alterations of circulating matrix metalloproteinases levels in untreated hypertensives and in spontaneously hypertensive rats: a relevant pharmacological target.

Inconsistent matrix metalloproteinases (MMPs) levels have been reported in hypertension, with higher, similar and lower MMPs levels reported in hypertensives compared with normotensives. Differences between studies may reflect lack of control of drug effects, accompanying diseases and pre-analytical issues. We compared MMP-2, MMP-8 and MMP-9 levels in 38 untreated hypertensive patients (with no other diseases) with those found in 33 normotensive controls. We also studied endogenous MMPs inhibitors (TIMP-1, TIMP-2 and alpha-2-macroglobulin-A2M). Additionally, we assessed MMPs and A2M levels in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. We hypothesized that similar MMPs/endogenous inhibitors' profiles would be found in this animal model of hypertension and in clinical hypertension. MMPs, TIMPs and A2M were measured in plasma samples with commercially available ELISA and gelatin zymography. We found unaltered MMP-2, MMP-8, TIMP-1, TIMP-2 and A2M levels in hypertension. However, hypertensives had higher MMP-9 levels and MMP-9/A2M ratios than normotensives. Moreover, while we found similar MMP-2 and A2M levels in SHR and WKY rats, we found higher MMP-9 levels and MMP-9/A2M ratios in SHR versus WKY rats. These findings show consistent abnormal net plasma MMP-9 (but not MMP-2) activity in clinical and experimental hypertension. These parallel alterations in clinical hypertension and in SHR suggest an important role for MMPs in hypertension. While MMPs may be a relevant pharmacological target, antihypertensive drugs that down-regulate MMPs may offer advantages in the management of this disease.

Antihypertensive effects exerted by enalapril in mild to moderate hypertension are not associated with changes in the circulating levels of nitric oxide-related markers.

PURPOSE: The antihypertensive effects of angiotensin-converting enzyme inhibitors (ACEi) are explained, at least in part, by enhanced bradykinin-dependent nitric oxide (NO) formation and decreased angiotensin II-induced oxidative stress and vasoconstriction. We examined for the first time whether treatment with enalapril increases the plasma levels of markers of NO formation and decreases oxidative stress in mild to moderate hypertensive patients. METHODS: Eighteen untreated hypertensive patients were treated with enalapril 10 mg/day (n=10) or 20 mg/day (n=8) for 60 days. Eighteen normotensive healthy controls were followed for the same period. Venous blood samples were collected at baseline and after 30/60 days of treatment with enalapril. Plasma NOx (nitrites + nitrates) concentrations were determined by using the Griess reaction. Plasma nitrite and whole blood nitrite concentrations were determined by using an ozone-based chemiluminescence assay. Plasma thiobarbituric acid-reactive species (TBARS) and 8-isoprostane concentrations were determined by a fluorimetric method and by ELISA, respectively. RESULTS: Treatment with enalapril decreased blood pressure in hypertensive patients. However, we found no significant changes in plasma NOx, nitrite, whole blood nitrite, and in the levels of markers of oxidative stress in both normotensive controls and hypertensive patients treated with enalapril. CONCLUSIONS: Our data show that enalapril 10-20 mg/day does not affect the concentrations of relevant markers of NO formation or markers of oxidative stress in mild to moderately hypertensive subjects, despite satisfactory blood pressure control. Our findings do not rule out the possibility that ACEi may produce such effects in more severely hypertensive patients treated with higher doses of ACEi.