Adrenomedullin and adrenotensin regulate collagen synthesis and proliferation in pulmonary arterial smooth muscle cells

Plasma mid-regional proadrenomedullin level in children with pulmonary hypertension associated with CHD

Adrenomedullin has been shown to inhibit proliferation in pulmonary artery smooth muscle cells and to alleviate pulmonary artery collagen accumulation in pulmonary hypertension. We aimed to assess mid-regional proadrenomedullin level in children with pulmonary hypertension due to CHDs. The current study was conducted in the Pediatric Cardiology Unit, Tanta University Hospital, on 50 children with CHDs: twenty-five patients had a complication of pulmonary hypertension and the other 25 patients without pulmonary hypertension. Another 25 children without CHDs were concluded as a control group. We performed complete history taking, full clinical assessment, chest X-ray, electrocardiogram, and echocardiographic assessment. Plasma level of mid-regional proadrenomedullin was assessed using a sandwich enzyme-linked immunosorbent assay test. Our results showed that the mean plasma level of mid-regional proadrenomedullin was significantly increased in patients with pulmonary hypertension. Significant positive correlation was found between mid-regional proadrenomedullin and mean pulmonary artery pressure. The best cut-off point of mid-regional proadrenomedullin as a diagnostic biomarker to discriminate patients with CHDs complicated with pulmonary hypertension was 199.22 nmol/l. Mid-regional proadrenomedullin significantly increased in patients with pulmonary hypertension who died as compared to patients who survived, with the best cut-off point was 428,8 nmol/l. We concluded that plasma levels of mid-regional proadrenomedullin were significantly elevated in children with pulmonary hypertension complicated by the CHDs. It could be used as a cardiac biomarker in these patients, with good diagnostic and prognostic value.

Plasma adrenomedullin peptides and precursor levels in pulmonary arterial hypertension disease severity and risk stratification

Adrenomedullin is a potent vasodilatory peptide, linked to pulmonary arterial hypertension pathology. Proximity extension assays were utilized to study plasma biomarkers related to vasoregulation, with focus on adrenomedullin peptides and precursor levels, collectively referred to as ADM. ADM was measured in 48 treatment-naïve pulmonary arterial hypertension patients at diagnosis, and in 31 of them at an early treatment follow-up. Plasma ADM was additionally assessed in patients with chronic thromboembolic pulmonary hypertension (n = 20) and pulmonary hypertension due to heart failure with preserved (HFpEF_(PH)) (n = 33) or reduced (HFrEF_(PH)) (n = 36) ejection fraction, as well as healthy controls (n = 16). ADM was studied in relation to pulmonary arterial hypertension hemodynamics, risk assessment, prognosis, treatment response, and differentiation. Plasma ADM levels in pulmonary arterial hypertension patients at diagnosis were higher than in healthy controls (p < 0.001), similar as in chronic thromboembolic pulmonary hypertension patients (p = ns), but lower compared to HFpEF_(PH) (p < 0.03) and HFrEF_(PH) (p < 0.001). In pulmonary arterial hypertension, specifically, plasma ADM at diagnosis correlated mainly to mean right atrial pressure (r = 0.73, p < 0.001), N-terminal prohormone of brain natriuretic peptide (r = 0.75, p < 0.001), six-minute walking distance (r = -0.57, p < 0.001), and venous oxygen saturation (r = -0.57, p < 0.001). ADM also correlated to the ECS/ERS- (r = 0.74, p < 0.001) and REVEAL risk scores (r = 0.54, p < 0.001) at pulmonary arterial hypertension diagnosis. Plasma ADM in pulmonary arterial hypertension patients was unaltered at early treatment follow-up compared to baseline (p = ns). Pulmonary arterial hypertension patients with supra-median ADM at diagnosis showed worse overall survival than those with infra-median levels (median survival 34 versus 66 months, p = 0.0077). In conclusion, the present results suggest that baseline plasma ADM levels mirror disease severity, correlating to both ECS/ERS- and the REVEAL risk scores.

Ion channels and transporters as therapeutic targets in the pulmonary circulation

Pulmonary circulation is a low pressure, low resistance, high flow system. The low resting vascular tone is maintained by the concerted action of ion channels, exchangers and pumps. Under physiological as well as pathophysiological conditions, they are targets of locally secreted or circulating vasodilators and/or vasoconstrictors, leading to changes in expression or to posttranslational modifications. Both structural changes in the pulmonary arteries and a sustained increase in pulmonary vascular tone result in pulmonary vascular remodeling contributing to morbidity and mortality in pediatric and adult patients. There is increasing evidence demonstrating the pivotal role of ion channels such as K(+) and Cl(-) or transient receptor potential channels in different cell types which are thought to play a key role in vasoconstrictive remodeling. This review focuses on ion channels, exchangers and pumps in the pulmonary circulation and summarizes their putative pathophysiological as well as therapeutic role in pulmonary vascular remodeling. A better understanding of the mechanisms of their actions may allow for the development of new options for attenuating acute and chronic pulmonary vasoconstriction and remodeling treating the devastating disease pulmonary hypertension.