Gene expression and synthesis of natriuretic peptides by cultured human glomerular cells

Background. Atrial natriuretic peptide, brain natriuretic peptide and C-type natriuretic peptide belong to a family of hormones that have natriuretic and vasodepressor activity and may play a pathophysiologic role in hypertension, heart failure and renal failure. Whereas immunoreactive human forms of these three natriuretic peptides are found in renal tubules, it is not clear whether they are derived from the systemic circulation or from local production. Objective. To examine the gene expression of natriuretic peptides in cultured human glomerular cells. Materials and methods. We sought to determine the presence of messenger RNA encoding for these natriuretic peptides using polymerase chain reaction following reverse transcription. The polymerase chain reaction products were confirmed by direct sequencing. Atrial natriuretic peptide, brain natriuretic peptide and C-type natriuretic peptide in cell-culture supernatants were measured by radioimmunoassays (with detection limits of 2.1, 2.1 and 0.21 pmol/l, respectively). Results. Atrial natriuretic peptide messenger RNA was not found in mesangial or glomerular epithelial cells (despite stimulation with tumor necrosis factor-α) except when the cells were cultured with a high concentration of fetal bovine serum (> 10%). Similarly, this peptide was not detected in supernatant unless the cells were cultured with fetal bovine serum at concentrations of > 10%. Brain natriuretic peptide messenger RNA was readily detected in cultured mesangial and glomerular epithelial cells with a lower concentration in the former. Brain natriuretic peptide was not found in the supernatant of resting mesangial cells but became detectable when incubated with tumor necrosis factor-α or fetal bovine serum. C-type natriuretic peptide messenger RNA was detected in mesangial and glomerular epithelial cells with a higher concentration in the latter. C-type natriuretic peptide was detected in the supernatant of resting glomerular epithelial cells and levels rose when incubated with increasing concentrations of tumor necrosis factor-α or fetal bovine serum. However, C-type natriuretic peptide was not detected in the supernatant of resting mesangial cells and remained undetectable following incubation with tumor necrosis factor-α or fetal bovine serum. Conclusion. Our results suggest differences in the synthesis of natriuretic peptides between glomerular mesangial and epithelial cells.link_to_subscribed_fulltex

Protease corin expression and activity in failing hearts

Atrial and brain natriuretic peptides (ANP and BNP) regulate blood pressure and cardiac function. In patients with heart failure (HF), plasma levels of pro-ANP and pro-BNP, the precursor forms of ANP and BNP, are highly elevated, but the mechanism underlying the apparent deficiency in natriuretic peptide processing is unclear. Corin is a cardiac protease that activates natriuretic peptides. In this study, we examined corin protein expression and activity in mouse and human failing hearts. Tissue samples were obtained from a mouse model of HF induced by myotrophin overexpression and from human nonfailing, hypertrophic, and failing hearts. Corin protein levels in the membrane fraction and tissue lysate were measured by Western blotting and ELISA. Corin catalytic and biological activities were measured by fluorescent substrate and pro-ANP processing assays. In mice, corin protein levels did not change with age in normal hearts but increased significantly in failing hearts. In humans, corin protein levels were similar in the atrium from nonfailing and failing hearts but were increased in the ventricle in failing hearts compared with those in nonfailing or hypertrophic hearts. Unlike the protein level, however, corin activity did not increase in failing hearts, as measured by fluorogenic substrate and pro-ANP processing assays. Our results indicate that corin activation is a rate-limiting step in failing hearts. Insufficient corin activation is expected to prevent natriuretic peptide processing and may contribute to body fluid retention and impaired cardiac function in patients with HF

Plasma levels of soluble VEGF receptor isoforms, circulating pterins and VEGF system SNPs as prognostic biomarkers in patients with acute coronary syndromes

© 2018 The Author(s). Background: Development of collateral circulation in coronary artery disease is cardio-protective. A key process in forming new blood vessels is attraction to occluded arteries of monocytes with their subsequent activation as macrophages. In patients from a prospectively recruited post-acute coronary syndromes cohort we investigated the prognostic performance of three products of activated macrophages, soluble vascular endothelial growth factor (VEGF) receptors (sFlt-1 and sKDR) and pterins, alongside genetic variants in VEGF receptor genes, VEGFR-1 and VEGFR-2. Methods: Baseline levels of sFlt-1 (VEGFR1), sKDR (VEGFR2) and pterins were measured in plasma samples from subgroups (n = 513; 211; 144, respectively) of the Coronary Disease Cohort Study (CDCS, n = 2067). DNA samples from the cohort were genotyped for polymorphisms from the VEGFR-1 gene SNPs (rs748252 n = 2027, rs9513070 n = 2048) and VEGFR-2 gene SNPs (rs2071559 n = 2050, rs2305948 n = 2066, rs1870377 n = 2042). Results: At baseline, levels of sFlt-1 were significantly correlated with age, alcohol consumption, NTproBNP, BNP and other covariates relevant to cardiovascular pathophysiology. Total neopterin levels were associated with alcohol consumption at baseline. 7,8 dihydroneopterin was associated with BMI. The A allele of VEGFR-2 variant rs1870377 was associated with higher plasma sFlt-1 and lower levels of sKDR at baseline. Baseline plasma sFlt-1 was univariately associated with all cause mortality with (p < 0.001) and in a Cox's proportional hazards regression model sFlt-1 and pterins were both associated with mortality independent of established predictors (p < 0.027). Conclusions: sFlt-1 and pterins may have potential as prognostic biomarkers in acute coronary syndromes patients. Genetic markers from VEGF system genes warrant further investigation as markers of levels of VEGF system components in these patients

Genetic variation in the renin–angiotensin–aldosterone system is associated with cardiovascular risk factors and early mortality in established coronary heart disease

This study examined renin–angiotensin–aldosterone (RAAS) system gene variants for associations with cardiovascular risk factors and outcomes in coronary heart disease. Coronary disease patients (n¼1186) were genotyped for 21 single-nucleotide polymorphisms (SNPs) within angiotensinogen (AGT), angiotensin-converting enzyme (ACE), angiotensin-II type-1 receptor (AGTR1) and aldosterone synthase (CYP11B2). Associations with all-cause mortality and cardiovascular readmissions were assessed over a median of 3.0 years. The AGT M235T ‘T’ allele was associated with a younger age of clinical coronary disease onset (P¼0.006), and the AGT rs2478545 minor allele was associated with lower circulating natriuretic peptides (P¼0.0001–P¼0.001) and E/E1 (P¼0.018). Minor alleles of AGT SNPs rs1926723 and rs11122576 were associated with more frequent history of renal disease (Pp0.04) and type-2 diabetes (Pp0.02), higher body mass index (Pp0.02) and greater mortality (Pp0.007). AGT rs11568054 minor allele carriers had more frequent history of renal disease (P¼0.04) and higher plasma creatinine (P¼0.033). AGT rs6687360 minor allele carriers exhibited worse survival (P¼0.02). ACE rs4267385 was associated with older clinical coronary disease onset (P¼0.008) and hypertension (P¼0.013) onset, increased plasma creatinine (P¼0.01), yet greater mortality (P¼0.044). Less history of hypertension was observed with the AGTR1 rs12685977 minor allele (P¼0.039). Genetic variation within the RAAS was associated with cardiovascular risk factors and accordingly poorer survival