Oxidative stress (OS) and reduced nitric oxide (NO) bioavailability contribute to the pathogenesis of pulmonary hypertension (PH). Whether there are associations between OS and NO signaling biomarkers and whether these biomarkers are associated with the severity of PH remain unclear. Blood samples were collected from 35 healthy controls and 35 patients with pulmonary arterial hypertension (PAH, n = 12) or chronic thromboembolic pulmonary hypertension (CTEPH, n = 23). The mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance index (PVRI) were measured by right heart catheterization. We measured the derivative of reactive oxygen molecules (d-ROMs), biological antioxidant potential (BAP) and superoxide dismutase (SOD) by automatic biochemical analyzer, malondialdehyde (MDA) and asymmetric dimethylarginine (ADMA) by enzyme-linked immunosorbent assay. The relationship between oxidative-antioxidative biomarkers and ADMA, as well as their association with pulmonary hemodynamics, were analyzed. Compared with age- and gender-matched controls, there was no significant difference of d-ROMs in PAH and CTEPH patients; MDA was increased in CTEPH patients (P = 0.034); BAP and SOD were decreased in PAH (P = 0.014, P < 0.001) and CTEPH patients (P = 0.015, P < 0.001); ADMA level was significantly higher in PAH (P = 0.007) and CTEPH patients (P < 0.001). No association between oxidative-antioxidative biomarkers and ADMA was found. Serum ADMA concentration was correlated with mPAP (r = 0.762, P = 0.006) and PVRI (r = 0.603, P = 0.038) in PAH patients. The antioxidative potential and NO signaling are impaired in PAH and CTEPH. Increased serum ADMA level is associated with unfavorable pulmonary hemodynamics in PAH patients. Thus, ADMA may be useful in the severity evaluation and risk stratification of PAH.

Objective We aimed to investigate the risk factors for acute kidney injury (AKI) after normotensive pulmonary embolism (PE) and the impact of anticoagulation on renal recovery. Design Multicentred, retrospective cohort study. Setting Data from four tertiary hospitals in China were captured. All available measurements of serum creatinine (SCr) during hospitalisation and follow-up were collected. Participants Patients with acute PE and those without haemodynamic instability were enrolled. All recruited patients were followed up for up to 2 years. Primary and secondary outcome measures The primary outcome was the occurrence of AKI, defined by the Kidney Disease Improving Global Outcomes criteria. The secondary outcome was the recovery of renal function. The time interval between PE onset and the initiation of anticoagulation was analysed to obtain its influence on the recovery of renal function. Results A total of 461 patients with acute normotensive PE were enrolled. A transient elevation of SCr during hospitalisation was observed. The incidence of AKI among normotensive patients was 18.9%. Brain natriuretic peptide (BNP) NT-proBNP elevation (adjusted HR (aHR) 2.27, 95% CI 1.33 to 3.86) and history of chronic kidney disease (aHR 4.81, 95% CI 2.44 to 9.48) were associated with the development of AKI during hospitalisation. Earlier initiation of anticoagulation therapy (within 5 days after PE onset, compared with over 6 days) promoted an early recovery of renal function (adjusted OR 0.26, 95% CI 0.08 to 0.84, p=0.025). Conclusions Renal impairment and AKI were highly prevalent among patients with normotensive patients. The occurrence of AKI was associated with right heart function. Patients who developed AKI after PE would benefit from earlier anticoagulation therapy for an early recovery of renal function.

The nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate (NO-sGC-cGMP) signaling pathway, plays a critical role in the pathogenesis of pulmonary arterial hypertension (PAH); however, its exact molecular mechanism remains undefined. Biotin-cGMP pull-down assay was performed to search for proteins regulated by cGMP. The interaction between cGMP and tropomyosin was analyzed with antibody dependent pull-down in vivo. Tropomyosin fragments were constructed to explore the tropomyosin-cGMP binding sites. The expression level and subcellular localization of tropomyosin were detected with Real-time PCR, Western blot and immunofluorescence assay after the 8-Br-cGMP treatment. Finally, isothermal titration calorimetry (ITC) was utilized to detect the binding affinity of actin-tropomyosin-myosin in the existence of cGMP-tropomyosin interaction. cGMP interacted with tropomyosin. Isoform 4 of TPM1 gene was identified as the only isoform expressed in the human pulmonary artery smooth muscle cells (HPASMCs). The region of 68-208aa of tropomyosin was necessary for the interaction between tropomyosin and cGMP. The expression level and subcellular localization of tropomyosin showed no change after the stimulation of NO-sGC-cGMP pathway. However, cGMP-tropomyosin interaction decreased the affinity of tropomyosin to actin. We elucidate the downstream signal pathway of NO-sGC-cGMP. This work will contribute to the detection of innovative targeted agents and provide novel insights into the development of new therapies for PAH.