Cystatin C and cardiac hypertrophy in primary hypertension

Human cystatin C in fibrotic diseases

Human cystatin C (hCC), which has a pervasive distribution within body fluids and is ubiquitously expressed by numerous cells and tissues, is a highly potent extracellular inhibitor of cysteine proteases. Besides measurement of serum creatinine, which is the most widely used technique for appraising glomerular filtration rate (GFR), hCC has emerged as a relevant GFR biomarker, because its quantification in serum is less sensitive to interferences with factors such as age, muscle mass or diet. Moreover, there are growing body of evidence that hCC overexpression and/or oversecretion, which is primarily driven by TGF-β1, occur during fibrogenesis (cardiac, liver, oral, and lung fibrosis). Even though molecular mechanisms and signaling pathways governing the regulation of hCC remain to be deciphered more acutely, current data sustain that hCC expression relates to myofibrogenesis and that hCC could be a specific and valuable biomarker of fibrotic disease.

CD14 and CD26 from serum exosomes are associated with type 2 diabetes, exosomal Cystatin C and CD14 are associated with metabolic syndrome and atherogenic index of plasma

Background

Exosomes are microvesicles that actively participate in signaling mechanisms and depending on their content can contribute to the development of different pathologies, such as diabetes and cardiovascular disease.

Objective

The aim of this study was to evaluate the association of cystatin C, CD26, and CD14 proteins in serum exosomes from patients with Type 2 Diabetes (T2D), metabolic syndrome (MetS), and atherogenic index of plasma (AIP).

Methods

Serum exosomes were isolated by ultracentrifugation from 147 individuals with and without diabetes. Both anthropometric and metabolic parameters were registered from everyone. The levels of exosomal proteins cystatin C, CD26, and CD14 were quantified by ELISA. The association between protein levels and T2D or atherogenic risk factors was analyzed by linear regression and generalized regression models.

Results

We observed a significant correlation of increased glucose with elevated levels of Cystatin C, and an effect of T2D on the levels of CD26 (β = 45.8 pg/µg; p = 0.001) and CD14 (β = 168 pg/µg; p < 0.001) compared to subjects without T2D. CD14 was significantly related to T2D, metabolic syndrome, glucose, and the Atherogenic Index of Plasma (AIP). Additionally, we observed a significant effect of metabolic syndrome MetS on the increase of exosomal Cystatin C and CD14.

Conclusions

T2D may contribute to the increase of CD14 protein contained in exosomes, as well as to the predisposition of atherogenic events development due to its relationship with the increase in serum triglyceride concentrations and the AIP score. Finally, the increased levels of CD14 and Cystatin C in exosomes are related to MetS. The analysis of exosome contents of diabetic patients remains an incipient field, so extensive characterization is crucial for their use as biomarkers or to analyze their possible contribution to diabetic complications.

Expression and clinical significance of serum cystatin C in patients with hypertension and coronary heart disease

The aim of this study is to explore the potential association between cystatin C (Cys-c) and coronary heart disease (CHD) in hypertensive patients.In this study, circulating levels of Cys-c in 62 essential hypertension (EH) patients, 147 hypertension with coronary heart disease (EH + CHD) patients, and 60 healthy volunteers were investigated using immunoturbidimetry. Then, we analyzed the correlations between Cys-C and other clinical parameters.Serum Cys-C level was significantly higher in the EH and EH + CHD groups than in the control group, and higher in the EH + CHD group than in the EH group. Receiver operating characteristic curve (ROC) analysis showed that the diagnostic value of Cys-C for patients with hypertension combined CHD was 0.871(95% CI: 0.818-0.913). Serum Cys-C level was significantly higher in the double-vessel disease group and multi-vessel disease group than in the single-vessel disease group, and higher in the multi-vessel disease group than in the double-vessel disease group. Urinary albumin and CRP correlated positively with Cys-C, and HDL correlated negatively with Cys-C. Cys-C was an independent risk factor for CHD in hypertensive patients.Our results suggested that circulating Cys-C levels was up-regulated in patients with hypertension and CHD, and had correlation with the severity of coronary artery disease. As one of the important risk factors for CHD, Cys-C can predict the occurrence of CHD in patients with hypertension.

Association between 24-hour diastolic blood pressure and renal function in patients receiving treatment for essential hypertension

Objectives

To evaluate the association between diastolic blood pressure (BP), measured by 24-hour ambulatory blood pressure monitoring (ABPM) and renal function in patients receiving treatment for essential hypertension.

Methods

In this cross-sectional study, ABPM, transthoracic echocardiography, estimated glomerular filtration rate (eGFR) on the basis of serum cystatin C (eGFRcyst) and the renal resistive index (RRI) were measured in patients with essential hypertension.

Results

The cohort consisted of 105 patients (39 men, 66 women), with a mean ± SD age of 58 ± 12 years who had been receiving treatment for 11 ± 8 years. 24-hour diastolic BP significantly positively correlated with eGFRcyst and negatively correlated with RRI. No correlation was observed with 24-hour systolic BP values. 24-hour diastolic BP values ≤70 mmHg were associated with eGFRcyst ≤60 ml/min/1.73 m2 (i.e., decreased GFR).

Conclusion

24-hour diastolic BP values were significantly associated with markers of kidney function in patients receiving treatment for essential hypertension and values ≤70 mmHg may be associated with subnormal eGFRcyst.

Serum cystatin C is an independent biomarker associated with the renal resistive index in patients with chronic kidney disease

Cystatin C is a cysteine protease inhibitor that is produced by nearly all human cells. The serum level of cystatin C is a stronger predictor of the renal outcome and the risk of cardiovascular events than the creatinine level. The resistive index (RI) on renal Doppler ultrasonography is a good indicator of vascular resistance as well as the renal outcomes in patients with chronic kidney disease (CKD). However, it is unclear whether serum cystatin C is associated with signs of vascular dysfunction, such as the renal RI. We measured the serum cystatin C levels in 101 CKD patients and investigated the relationships between cystatin C and markers of vascular dysfunction, including the renal RI, ankle-brachial pulse wave velocity (baPWV), intima-media thickness (IMT), and cardiac function. The renal RI was significantly correlated with the serum cystatin C level (p < 0.0001, r = 0.6920). The serum cystatin C level was found to be a significant determinant of the renal RI (p < 0.0001), but not the baPWV, in a multivariate regression analysis. The multivariate odds ratio of the serum cystatin C level for a renal RI of more than 0.66 was statistically significant (2.92, p = 0.0106). The area under the receiver-operating characteristic curve comparing the sensitivity and specificity of cystatin C for predicting an RI of more than 0.66 was 0.882 (cutoff value: 2.04 mg/L). In conclusion, the serum cystatin C level is an independent biomarker associated with the renal RI in patients with CKD.

Renal effects of the angiotensin receptor neprilysin inhibitor LCZ696 in patients with heart failure and preserved ejection fraction

BACKGROUND

Increases in serum creatinine with renin-angiotensin-aldosterone system (RAAS) inhibitors can lead to unnecessary discontinuation of these agents. The dual-acting angiotensin receptor neprilysin inhibitor LCZ696 improves clinical outcome patients with heart failure with reduced ejection fraction, and pilot data suggest potential benefit in heart failure with preserved ejection fraction (HFpEF). The effects of LCZ696 on renal function have not been assessed.

METHODS AND RESULTS

A total of 301 HFpEF patients were randomly assigned to LCZ696 or valsartan in the PARAMOUNT trial. We studied renal function [creatinine, estimated glomerular filtration rate (eGFR), cystatin C, and urinary albumin to creatinine ratio (UACR)] at baseline, 12 weeks, and after 36 weeks of treatment. Worsening renal function (WRF) was determined as an serum creatinine increase of >0.3 mg/dL and/or >25% between two time-points. Mean eGFR at baseline was 65.4 ± 20.4 mL/min per 1.73 m(2) . The eGFR declined less in the LCZ696 group than in the valsartan group (-1.5 vs. -5.2 mL/min per 1.73 m(2) ; P = 0.002). The incidence of WRF was lower in the LCZ696 group (12%) than in the valsartan group (18%) at any time-point, but this difference was not statistically significant (P = 0.18). Over 36 weeks, the geometric mean of UACR increased in the LCZ696 group (2.4-2.9 mg/mmol), whereas it remained stable in the valsartan group (2.1-2.0 mg/mmol; P for difference between groups = 0.016).

CONCLUSION

In patients with HFpEF, therapy with LCZ696 for 36 weeks was associated with preservation of eGFR compared with valsartan therapy, but an increase in UACR.

Serum cystatin C concentration as an independent marker for hypertensive left ventricular hypertrophy

Background

Serum cystatin C levels can be used to predict morbidity and mortality in patients with cardiovascular disease. However, the clinical relevance of serum cystatin C levels in patients with hypertensive left ventricular hypertrophy (LVH) has rarely been investigated. We designed the present study to investigate whether serum cystatin C levels are associated with cardiac structural and functional alterations in hypertensive patients.

Methods

We enrolled 823 hypertensive patients and classified them into two groups: those with LVH (n = 287) and those without LVH (n = 536). All patients underwent echocardiography and serum cystatin C testing. We analyzed the relationship between serum cystatin C levels and LVH.

Results

Serum cystatin C levels were higher in hypertensive patients with LVH than in those without LVH (P < 0.05). Using linear correlation analysis, we found a positive correlation between serum cystatin C levels and interventricular septal thickness (r = 0.247, P < 0.01), posterior wall thickness (r = 0.216, P < 0.01), and left ventricular weight index (r = 0.347, P < 0.01). When analyzed by multiple linear regression, the positive correlations remained between serum cystatin C and interventricular septal thickness (β = 0.167, P < 0.05), posterior wall thickness (β = 0.187, P < 0.05), and left ventricular weight index (β = 0.245, P < 0.01).

Conclusion

Serum cystatin C concentration is an independent marker for hypertensive LVH.

Genetic predisposition to left ventricular hypertrophy and the potential involvement of cystatin-C in untreated hypertension

BACKGROUND

The angiotensinogen M235T and aldosterone synthase C-344T gene polymorphisms have been associated with cardiac and structure function. However, these associations in untreated hypertension remain unknown. We examined whether these variants determined both echocardiography indices and the potential associated underlying mechanisms, including cystatin-C and vascular inflammation.

METHODS

The study population consisted of 319 untreated patients and 191 healthy individuals. Polymorphisms were determined by polymerase chain reaction technique. Left cardiac indices of geometry and function were assessed by echocardiography. Cystatin-C, intracellular cell adhesion molecule 1, and vascular cell adhesion molecule 1 levels were measured by enzyme-linked immunosorbent assay, whereas high sensitivity C-reactive protein levels were measured by immunonephelometry.

RESULTS

There was no significant interaction between the angiotensinogen genotypes on left ventricular mass index (LVMI) and diastolic function indices in all study groups. Regarding C-344T polymorphism, TT homozygous hypertensive subjects exhibited higher values of LVMI compared with C allele carriers (P = 0.02) and higher prevalence of concentric hypertrophy (P < 0.001). However, this polymorphism was not associated with variations in left atrial volume and diastolic dysfunction. Cystatin-C levels were correlated with LVMI values (r = 0.22; P = 0.002) and mean E/A ratio (r = -0.24; P < 0.001). Interestingly, a linear increase of LVMI with cyctatin-C quartiles has been revealed (F = 5.01; P < 0.001). Moreover, post hoc tests showed that increased levels of cystatin-C (above 75th percentile) were significantly different between both the first (P = 0.009) and the second quartile (P = 0.02).

CONCLUSIONS

We have shown that C-344T potentially predicts higher values of LVMI and concentric hypertrophy in untreated hypertension, independently of renal function and subclinical inflammation. Increased levels of cystatin-C were correlated with higher LVMI values.

The effect of amlodipine besylate, losartan potassium, olmesartan medoxomil, and other antihypertensives on central aortic blood pressure and biomarkers of vascular function

Biomarkers are being increasingly used in the study of cardiovascular disease because they provide readily quantifiable surrogate endpoints and allow accurate assessment of the effects of therapy on particular pathological processes. However, in order to be useful, biomarkers must be relevant, predictable, accurate, and reproducible. There is compelling evidence from large-scale clinical trials that inhibitors of the renin-angiotensin system [angiotensin-converting enzyme inhibitors and angiotensin type II receptor blockers (ARBs)] and calcium channel blockers (CCBs) may have beneficial effects beyond blood pressure control in the treatment of hypertension. Biomarkers are expected to provide further insight into these beneficial effects and allow for quantitative assessment. This review summarizes the published clinical evidence on the effects of various antihypertensive drugs, particularly ARBs (e.g. losartan and olmesartan medoxomil) and CCBs (e.g. amlodipine), alone and in combination with other agents (e.g. hydrochlorothiazide), on central aortic pressure and the biomarkers high-sensitivity C-reactive protein (hsCRP), adiponectin, cystatin C, homeostasis model assessment of insulin resistance (HOMA-IR), procollagen, tumor necrosis factor-α, and interleukin-6. Of these biomarkers, the benefits of antihypertensive therapy on hsCRP, adiponectin, and HOMA-IR reflect a potential for quantifiable long-term vascular benefits.