Positive correlation between blood pressure or heart rate and chymase-dependent angiotensin II-forming activity in circulating mononuclear leukocytes measured by new ELISA

Evaluation of Alacepril Administration in Canine Patent Ductus Arteriosus According to Plasma Chymase Activity

Chymase in the renin-angiotensin system (RAS) actively contributes to cardiac disease progression. Chymase is activated to produce angiotensin II during tissue injury and is involved in hemodynamics. A recent study demonstrated that plasma chymase activity reflects hemodynamic changes and aids in understanding patent ductus arteriosus (PDA) pathophysiology. The present study examined the relationship between plasma chymase activity and the administration of angiotensin-converting enzyme (ACE) inhibitor. Alacepril was administered to 13 puppies with PDA. Conventional echocardiographic parameters and non-invasive blood pressure were measured before and after medication. Plasma chymase activity was calculated using the colorimetric absorbance method. Plasma chymase activity significantly increased, but blood pressure significantly decreased. We detected an increase in plasma chymase activity due to ACE inhibition in PDA cases treated with alacepril. Plasma chymase activity was affected and altered by alacepril. In veterinary medicine, plasma chymase activity may be a novel method for assessing the pathology of and therapy for cardiac diseases.

Is chymase 1 a therapeutic target in cardiovascular disease?

INTRODUCTION

Non-angiotensin converting enzyme mechanisms of angiotensin II production remain underappreciated in part due to the success of current therapies to ameliorate the impact of primary hypertension and atherosclerotic diseases of the heart and the blood vessels. This review scrutinize the current literature to highlight chymase role as a critical participant in the pathogenesis of cardiovascular disease and heart failure.

AREAS COVERED

We review the contemporaneous understanding of circulating and tissue biotransformation mechanisms of the angiotensins focusing on the role of chymase as an alternate tissue generating pathway for angiotensin II pathological mechanisms of action.

EXPERT OPINION

While robust literature documents the singularity of chymase as an angiotensin II-forming enzyme, particularly when angiotensin converting enzyme is inhibited, this knowledge has not been fully recognized to clinical medicine. This review discusses the limitations of clinical trials' that explored the benefits of chymase inhibition in accounting for the failure to duplicate in humans what has been demonstrated in experimental animals.

Plasma Chymase Activity Reflects the Change in Hemodynamics Observed after the Surgical Treatment of Patent Ductus Arteriosus in Dogs

Chymase is a protease stored in mast cell granules that produces angiotensin II (ANG II) from angiotensin I (ANG I) and is associated with tissue injury, inflammation, and remodeling, especially involving the cardiovascular system. As cardiovascular events occur, chymase is activated by degranulation to the extracellular matrix. Although chymase has been suggested to be associated with cardiovascular disease progression, there are not enough reports in veterinary medicine. Patent ductus arteriosus (PDA) is a common congenital cardiac disease in veterinary medicine. Almost all cases of PDA can be treated surgically to prevent the development of congestive heart disease and/or pulmonary hypertension. The aims of the present study were to measure chymase activity before and after PDA occlusions, and to investigate the relationships between the congestive and hemodynamic states of PDA and chymase activity. In the present study, 17 puppies diagnosed with PDA were included and all puppies completely recovered to the level of healthy dogs. Chymase activity significantly decreased at 2 months after the operation, along with the echocardiography parameters of congestion. Therefore, plasma chymase activity may be useful as a novel predictor for understanding the hemodynamics of PDA in veterinary medicine.

Elevated chymase-dependent angiotensin II-forming activity in circulating mononuclear leukocytes was observed in the patient of atrial fibrillation

Chymase is an angiotensin II-forming serine proteinase and elevation of its tissue activity occurs in various cardiovascular diseases. Several authors have suggested that there is an association between the renin-angiotensin system and atrial fibrillation (AF). Chymase-dependent angiotensin II-forming activity in circulating mononuclear leukocytes (CML chymase dAIIFA) was investigated in patients with AF and patients in sinus rhythm. Consecutive outpatients were recruited at our hospital. CML chymase dAIIFA was measured using a Nma/Dnp-type fluorescence-quenching substrate of modified angiotensin I in the presence or absence of a specific serine proteinase inhibitor. To search the independent contributing factor of existence of AF, the analysis between groups was carried out using multivariate analysis after univariate analysis. The patients were classified into a sinus rhythm (SR) group (n = 459) or an AF group (n = 48). CML chymase dAIIFA was significantly higher in the AF group (622 pmol/min/mg) compared with the SR group (488 pmol/min/mg) (p < 0.001). Logistic regression analysis revealed that high CML chymase dAIIFA was an independent determinant of the existence of AF (p < 0.001). Elevation of CML chymase dAIIFA was associated with AF. Activation of chymase might be linked to atrial structural and electrical remodeling.

High Fib4 index in patients with suspected NASH is associated with elevation of chymase-dependent angiotensin II-forming activity in circulating mononuclear leucocytes

Fatal hepatic disease is closely related to non-alcoholic fatty liver disease, especially non-alcoholic steatohepatitis (NASH). NASH is associated with cardiovascular events because it develops on the background of lifestyle-related diseases. Chymase-dependent angiotensin II-forming activity (dAIIFA) in circulating mononuclear leucocytes (CML) is a marker of local angiotensin II production and inflammation. This study investigated the association between CML chymase dAIIFA and NASH. Cardiovascular outpatients were recruited and the Fib4 index (F4I) was calculated. Patients with an F4I > 2.67 were classified into the high F4I group and these patients were strongly suspected to have NASH, while patients with an F4I < 1.30 were classified into the low F4I group. Patient background factors were compared between these groups. CML chymase dAIIFA was measured by ELISA using Nma/Dnp-modified angiotensin I. Among 499 patients, 16% were classified into the high F4I group. Compared with the low F4I group, the high F4I group had a significantly higher age, pancytopenia, more frequent diabetes mellitus, lower diastolic blood pressure, lower estimated glomerular filtration rate, higher brain natriuretic peptide, lower plasma aldosterone concentration, higher total AIIFA, higher CML chymase dAIIFA, and higher pulse wave velocity. Contrary to expectations, the body mass index, triglycerides, and low-density lipoprotein cholesterol were relatively low in the high F4I group. Many cardiovascular outpatients have a high F4I and can probably be categorized as NASH. The high F4I patients had few features of metabolic syndrome and were suspected to have elevated tissue chymase dAIIFA contributing to inflammation in the liver as well as in cardiovascular organs.

Increase of chymase-dependent angiotensin II-forming activity in circulating mononuclear leukocytes after acute myocardial infarction chymase activity after acute myocardial infarction

A previous clinical study revealed elevation of chymase- and cathepsin G-dependent angiotensin II-forming activity (AIIFA) in the myocardium after acute myocardial infarction (AMI). This study examined the time course of chymase- and cathepsin G-dependent AIIFA in circulating mononuclear leukocytes (CML) after AMI. Consecutive patients with AMI were recruited. Chymase- and cathepsin G-dependent AIIFA in CML were assayed using a modified angiotensin I substrate with Nma/Dnp fluorescence quenching. The changes of CML AIIFA were monitored over time in the patients. Fifteen consecutive AMI patients admitted to our hospital were recruited. At 1 day after the admission, CML chymase- and cathepsin G-dependent AIIFA were 2.9- and 1.7-fold higher than at discharge, respectively. The ratio of chymase-dependent AIIFA to total AIIFA was significantly increased. AIIFA gradually decreased over time after the admission. The peak value of chymase- and cathepsin G-dependent AIIFA was significantly correlated with the maximum levels of aspartate aminotransferase (r = 0.53, 0.64), lactate dehydrogenase (r = 0.57, 0.62), and creatine kinase (r = 0.60, 0.65). This is the first evidence that chymase- and cathepsin G-dependent AIIFA is elevated in CML after AMI. Our data suggested that chymase-dependent AIIFA is increased in CML as well as in the myocardium after AMI, and that the level of chymase-dependent AIIFA might reflect the severity of infarction.

Prospective single-arm observational study of human chymase inhibitor Polygonum hydropiper L in subjects with hypertension

Background and Purpose: Human chymase (h-chymase) is a serine protease that forms local angiotensin II and has been proven to be related to onset of hypertension, arteriosclerosis, and post myocardial infarction cardiac remodeling. Since no chymase inhibitor was clinically available, an extensive screening for inhibition of h-chymase in three different extracts (water, hot water,  and ethanol) of approximately 800 food ingredients had been performed and we identified Polygonum hydropiper L (Polygonum). Using a dried and powdered Polygonum, we conducted a prospective, single-arm, pilot study to investigate its safety and antihypertensive effect in subjects with normal high blood pressure to moderate hypertension.Methods: First, a single oral dose of Polygonum powder (4000 mg) was administered to assess acute toxicity. Then, a pilot study was conducted in 11 subjects using the sequence of placebo and Polygonum for 2 weeks each. The dose of Polygonum was increased sequentially (200-2000 mg/day). Home blood pressure and pulse rate were monitored.Results: Oral administration of Polygonum (4000 mg) did not cause any adverse events. In the dose-escalation phase, evening systolic blood pressure was significantly decreased at 800 mg, 2000 mg doses post-treatment (p < 0.05, and p < 0.05, respectively). Depressor responders to Polygonum intake had significantly higher salt intake in spot urine (p < 0.05). No adverse events or reactions occurred.Conclusion: This was the first investigation that an h-chymase inhibitory Polygonum intake for safety and tolerability was proven and, in addition, chymase inhibitory Polygonum appeared to have depressor effect especially in a hypertensive subject with excessive salt intake.

Serum concentration of renin-angiotensin system components in association with ACE I/D polymorphism among hypertensive subjects in response to ACE inhibitor therapy

Background: Renin-angiotensin system (RAS) is a complex network of enzymes and peptides with the essential role in blood pressure control. The relationships between RAS components, RAS-related genetic polymorphisms and therapy response in essential hypertension (EH) were widely explored but the results were inconclusive. Aim: The aim of this study was to explore the functional role of ACE insertion/deletion (I/D) polymorphism on the systemic quantity of angiotensin-converting enzyme (ACE), its homolog - ACE2, chymase and angiotensin II in EH patients with respect to achieved therapeutic blood pressure control. Results: Genotyping of ACE I/D polymorphism was performed among 140 patients with EH from Bulgaria. The serological analyses reveal the significant elevation of the serum quantity of all investigated enzymes in EH than normotensive controls. In addition, serum ACE2 (183.57 pg/ml; vs. 151.78 pg/ml; p = 0.02) and chymase (68.5 pg/ml; vs. 23.66 pg/ml; p = 0.034) were significantly higher in patients with uncontrolled EH than controlled EH in response to ACE-inhibitory therapy. Also, ACE I/D polymorphism showed a significant impact on the serum ACE and chymase levels. ACE quantity was the highest among carriers of DD-genotype, followed by ID and II-genotype. Contrary, chymase was in the highest quantity in II-genotype compared to ID-genotype (p = 0.025) and DD-genotype (p = 0.044). Conclusions: Our results suggest that insufficient blood pressure control by ACE-inhibitory therapy could be associated with elevation of serum ACE2 and chymase levels. Also, it appears that ACE I/D polymorphism may influence the circulating quantity of chymase in addition to ACE.