Homocysteine-induced oxidative stress upregulates chymase in mouse mastocytoma cells

Plasma Homocysteine and Cardiovascular Organ Damage in a Population with a High Prevalence of Risk Factors

PURPOSE

It is unclear whether plasma homocysteine (Hcy) has a direct noxious impact on the cardiovascular (CV) system or whether its association with cardiovascular events (CVEs) is mediated by established risk factors. To explore the role of Hcy in CV impairment, the study evaluated cross-sectional relationships between plasma Hcy and indices of CV organ damage together with the associations of these indices with the history of CVEs.

METHODS

In 269 patients with a high prevalence of diabetes, dyslipidemia, and hypertension, the carotid intima-media thickness, ankle-brachial index (ABI), reactive hyperemic index, carotid-femoral pulse wave velocity (cfPWV), left ventricular (LV) mass, and cardiac index were measured.

RESULTS

132 patients had carotid plaque, 31 ABI < 0.90, 126 endothelial dysfunction, 66 increased cfPWV, 125 LV hypertrophy (LVH), 153 decreased cardiac index, and 115 a history of CVEs. Plasma Hcy levels were related to LV mass and ABI, after adjustment for covariates and creatinine. Significantly higher Hcy levels were found in patients with LVH (8.5 [4.4] vs 7.6 [2.8] μmol/L; adjusted P = .001) and ABI < 0.9 (10.4 [3.8] vs 7.9 [3.4] μmol/L; adjusted P = .001) than in those with LV mass and ABI within limits. Hcy levels were comparable between patients with and without carotid plaques, increased arterial stiffness, impaired endothelial, and LV pump function. Within markers of CV organ damage, only LVH was associated with a history of CVEs.

CONCLUSION

This study demonstrated an independent association between Hcy and LV mass as well as between LVH and a history of CVEs and suggests that LVH may represent 1 of the pathophysiologic links between Hcy and CV risk.

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.

Detection of chymase activity using a specific peptide probe conjugated onto gold nanoparticles

The gold nanoparticles (AuNPs) peptide probe functionalized with specific peptide sequences was developed for the sensitive and efficient detection of chymase activity.

Interactions of homocysteine and conventional predisposing factors on hypertension in Chinese adults

This study aimed to investigate whether conventional predisposing factors modify the associations of homocysteine with blood pressure levels and hypertension. A total of 2615 adults were recruited from Liaoning province. An elevated homocysteine level was significantly associated with increased hypertension risk and blood pressure (all P<.05). Interaction analyses showed that homocysteine acted synergistically with age, overweight/obesity, dyslipidemia, and family history of hypertension to affect hypertension risk, and the relative excess risk due to interaction was 1.21 (95% confidence interval, 0.07-2.35), 0.72 (95% confidence interval, 0.07-1.36), 0.45 (95% confidence interval, 0.06-0.85), and 1.87 (95% confidence interval, 0.77-2.97), respectively. Increases in blood pressure were higher in patients who were overweight/obese or had a family history of hypertension than in their counterparts (all Pinteraction <.05). This study provides some strong evidence for interactions of homocysteine with conventional predisposing factors on hypertension.

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

The aim of the present study was to establish a convenient clinically applicable assay method for chymase-dependent angiotensin II forming activity of circulating mononuclear leukocytes (CML), which was potentially a marker of tissue chymase activity. Using this method, association between CML chymase activity and clinical parameters was determined. Cardiovascular outpatients (n = 170) without taking antihypertensive medication were recruited. An ELISA for chymase-dependent angiotensin II-forming activity in CML was established using Nma /Dnp-modified angiotensin I. Logistic regression analysis revealed that age and male gender were significant independent determinants of the increased CML chymase activity. After adjustment by age and gender, the CML chymase activity was positively correlated with systolic blood pressure, pulse rate, and the brain natriuretic peptide level. The relation between blood pressure and CML chymase activity suggests that it might reflect that increased tissue chymase activity contributes to systemic high blood pressure and heart rate because plasma chymase is inactive due to inhibitory plasma inhibitors.

From hypertension to stroke: mechanisms and potential prevention strategies

Stroke is a major cause of disability and death worldwide. Prevention aimed at risk factors of stroke is the most effective strategy to curb the stroke pandemic. Hypertension is one of the most important risk factors for stroke. Despite the substantial evidence of the benefits of lowering blood pressure, conventional treatment does not normalize the burden of major cardiovascular events in patients with hypertension. Fully understanding the factors involved in the hypertension-induced stroke helps to develop new strategies for stroke prevention. Antihypertensive therapies selected should have positive blood pressure-independent effects on stroke risk. This review summarizes the factors involved in the hypertension-induced stroke, such as oxidative stress, inflammation, and arterial baroreflex dysfunction, and potential strategies for its prevention, therefore, provides clues for clinicians.

Emerging role of mast cells and macrophages in cardiovascular and metabolic diseases

Mast cells are essential in allergic immune responses. Recent discoveries have revealed their direct participation in cardiovascular diseases and metabolic disorders. Although more sophisticated mechanisms are still unknown, data from animal studies suggest that mast cells act similarly to macrophages and other inflammatory cells and contribute to human diseases through cell-cell interactions and the release of proinflammatory cytokines, chemokines, and proteases to induce inflammatory cell recruitment, cell apoptosis, angiogenesis, and matrix protein remodeling. Reduced cardiovascular complications and improved metabolic symptoms in animals receiving over-the-counter antiallergy medications that stabilize mast cells open another era of mast cell biology and bring new hope to human patients suffering from these conditions.