Human bone marrow endothelial cells: a new identified source of B-type natriuretic peptide

Valproic Acid Induces Endothelial-to-Mesenchymal Transition-Like Phenotypic Switching

Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, is a widely used anticonvulsant drug that is currently undergoing clinical evaluation for anticancer therapy due to its anti-angiogenic potential. Endothelial cells (ECs) can transition into mesenchymal cells and this form of EC plasticity is called endothelial-to-mesenchymal transition (EndMT), which is widely implicated in several pathologies including cancer and organ fibrosis. However, the effect of VPA on EC plasticity and EndMT remains completely unknown. We report herein that VPA-treatment significantly inhibits tube formation, migration, nitric oxide production, proliferation and migration in ECs. A microscopic evaluation revealed, and qPCR, immunofluorescence and immunoblotting data confirmed EndMT-like phenotypic switching as well as an increased expression of pro-fibrotic genes in VPA-treated ECs. Furthermore, our data confirmed important and regulatory role played by TGFβ-signaling in VPA-induced EndMT. Our qPCR array data performed for 84 endothelial genes further supported our findings and demonstrated 28 significantly and differentially regulated genes mainly implicated in angiogenesis, endothelial function, EndMT and fibrosis. We, for the first time report that VPA-treatment associated EndMT contributes to the VPA-associated loss of endothelial function. Our data also suggest that VPA based therapeutics may exacerbate endothelial dysfunction and EndMT-related phenotype in patients undergoing anticonvulsant or anticancer therapy, warranting further investigation.

Essential roles of the nitric oxide (no)/cGMP/protein kinase G type-Iα (PKG-Iα) signaling pathway and the atrial natriuretic peptide (ANP)/cGMP/PKG-Iα autocrine loop in promoting proliferation and cell survival of OP9 bone marrow stromal cells

Inappropriate signaling conditions within bone marrow stromal cells (BMSCs) can lead to loss of BMSC survival, contributing to the loss of a proper micro-environmental niche for hematopoietic stem cells (HSCs), ultimately causing bone marrow failure. In the present study, we investigated the novel role of endogenous atrial natriuretic peptide (ANP) and the nitric oxide (NO)/cGMP/protein kinase G type-Iα (PKG-Iα) signaling pathway in regulating BMSC survival and proliferation, using the OP9 BMSC cell line commonly used for facilitating the differentiation of HSCs. Using an ANP-receptor blocker, endogenously produced ANP was found to promote cell proliferation and prevent apoptosis. NO donor SNAP (S-nitroso-N-acetylpenicillamine) at low concentrations (10 and 50 µM), which would moderately stimulate PKG activity, protected these BMSCs against spontaneous apoptosis. YC-1, a soluble guanylyl cyclase (sGC) activator, decreased the levels of apoptosis, similar to the cytoprotective effects of low-level NO. ODQ (1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one), which blocks endogenous NO-induced activation of sGC and thus lowers endogenous cGMP/PKG activity, significantly elevated apoptotic levels by 2.5- and three-fold. Pre-incubation with 8-Bromo-cGMP or ANP, which bypass the ODQ block, almost completely prevented the ODQ-induced apoptosis. A highly-specific PKG inhibitor, DT-3, at 20, and 30 µM, caused 1.5- and two-fold increases in apoptosis, respectively. ODQ and DT-3 also decreased BMSCs proliferation and colony formation. Small Interfering RNA gene knockdown of PKG-Iα increased apoptosis and decreased proliferation in BMSCs. The data suggest that basal NO/cGMP/PKG-Iα activity and autocrine ANP/cGMP/PKG-Iα are necessary for preserving OP9 cell survival and promoting cell proliferation and migration.

Diagnostic and prognostic impact of brain natriuretic peptide in cardiac and noncardiac diseases

OBJECTIVE

Cardiac secretion of brain natriuretic peptide (BNP) increases with the progression of congestive heart failure (CHF). The plasma measurement of BNP emerged recently as a useful, cost-effective biomarker for the diagnosis and prognosis of CHF.

METHODS

BNP assay is useful for evaluating patients with acute dyspnea, because a low level can help rule out CHF in primary care settings and reduce the demand for echocardiography. Equally, BNP level can be particularly useful in recognizing heart failure in a patient with acute dyspnea and a history of chronic obstructive pulmonary disease.

RESULTS

However, although the clinical use of BNP as a biomarker in CHF is increasing, the specificity of BNP in CHF is not strong, suggesting that other mechanisms beyond simple ventricular stretch stimulate BNP release. Multiple disorders in the intensive care unit, apart from CHF, cause elevated BNP levels, including cardiovascular disease states such as ischemia, arrhythmias, cardiac hypertrophy, and coronary endothelial dysfunction, as well as disorders of no cardiac origin, such as sepsis, septic shock, and acute respiratory distress syndrome. Moreover, the impact of increased BNP in patients with sepsis is not clear. The relationship between BNP and both left ventricular ejection fraction and left-sided filling pressures is weak, and data on the prognostic impact of high BNP levels in patients with sepsis are conflicting.

CONCLUSION

Nevertheless, this review highlights the potential benefits of BNP in the recognition and management of heart failure, and defines the gray zones of BNP levels; it also identifies conditions influencing BNP levels in relation to a certain heart failure and describes conditions of no cardiac origin with increased BNP.

B-type natriuretic peptide release in the coronary effluent after acute transient ischaemia in humans

BACKGROUND

The association between B-type natriuretic peptide (BNP) and coronary artery disease is not fully understood.

OBJECTIVE

To assess whether ischaemia per se is a stimulus for BNP secretion.

SETTING

University tertiary hospital, Spain (Virgen de la Arrixaca).

DESIGN

Prospective interventional study.

PATIENTS

11 patients (55 (9) years, left ventricular ejection fraction (LVEF) 45% (7%) with a non-complicated anterior myocardial infarction (MI) and isolated stenosis of the left anterior descending (LAD) coronary artery, successfully treated by primary angioplasty.

INTERVENTIONS

11.0 (0.9) days after MI, the LAD was occluded (20 min) for intracoronary infusion of progenitor cells. Blood samples were obtained from the femoral artery (peripheral circulation (PC)) and the coronary sinus (coronary circulation (CC)) immediately before and after coronary occlusion.

MAIN OUTCOME MEASURES

BNP (pg/ml) was measured and ischaemia biomarkers were monitored.

RESULTS

During coronary occlusion, all patients experienced transitory chest pain and ST-segment dynamic changes. After coronary occlusion, lactic acid levels rose in CC (1.42 (0.63) -1.78 (0.68) ng/ml, p = 0.003). Myoglobin and cardiac troponin T did not differ in CC or PC at 24 h. No differences were found in LVEF (+0.18% (2.4)%, p = 0.86) and motion score index (-0.02 (0.06), p = 0.37). Before occlusion, BNP levels did not differ significantly in CC versus PC (253 (56) vs 179 (34), p = 0.093). After occlusion, BNP showed a significant increase in CC (vs 332 (61), p = 0.004), but no change occurred in PC (vs 177 (23), p = 0.93), and circulating BNP levels were higher in CC versus PC (p = 0.008).

CONCLUSIONS

In response to acute ischaemia, BNP levels immediately increase in coronary sinus but not at the peripheral level. BNP release in the coronary effluent may exert local beneficial effects.

Utility of brain natriuretic peptide (BNP) measurement in cardiovascular disease

Cardiac failure is a prevalent and costly condition in Western society. The ageing of the population, together with current medical options which improve, rather than eradicate heart failure, lead to the projection that this problem will increase substantially in the foreseeable future. The availability of a simple test to assist the diagnosis and effective management of heart failure would greatly assist the clinical approach to this problem. This review examines the physiological basis for the measurement of natriuretic peptides as markers of the presence or risk of heart failure. It considers its use in the hospital and non-hospital setting and examines the cost-effectiveness of current assays. It is possible that in future natriuretic peptides may offer a form of treatment for heart failure, but this is beyond the scope of this review. Nevertheless, the review highlights the potential benefits of this group of tests in the management of heart failure.