Erquan Zhang

Macitentan reverses early obstructive pulmonary vasculopathy in rats: early intervention in overcoming the survivin-mediated resistance to apoptosis

It remains unknown whether current disease-targeting therapy can histologically reverse obstructive pulmonary vasculopathy and how the timing of the therapy influences the antiremodeling effects of the compound. We test the hypothesis that a novel endothelin receptor antagonist macitentan reverses the early and/or late stages of occlusive pulmonary vascular disease (PVD) in rats. Rats with pulmonary arterial hypertension (PAH), which were produced by combined exposure to a vascular endothelial growth factor receptor inhibitor Sugen 5416 and hypobaric hypoxia for 3 wk, were assigned to receive macitentan or vehicle during 3-5 wk (early study) or during 5-8 wk (late study) after Sugen injection. Compared with vehicle-treated PAH rats and PAH rats evaluated before treatment initiation, the macitentan-treated rats showed decreases in the proportion of occlusive lesions in the early study, a finding consistent with the reversal of right ventricular systolic pressure and indexes of right ventricular hypertrophy and medial wall thickness. Macitentan ameliorated but did not reverse the proportion of occlusive lesions in the late study. Although macitentan decreased the proportion of Ki67+ lesions in both studies, macitentan increased the proportion of cleaved caspase 3+ lesions and suppressed an antiapoptotic molecule survivin expression in the early study but not in the late study. In conclusion, macitentan reversed early but not late obstructive PVD in rats. This reversal was associated with the suppression of survivin-related resistance to apoptosis and proliferation of cells in PVD.

Comparative Transcriptome Analysis Identifies CCDC80 as a Novel Gene Associated with Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a heterogeneous disorder associated with a progressive increase in pulmonary artery resistance and pressure. Although various therapies have been developed, the 5-year survival rate of PAH patients remains low. There is thus an important need to identify novel genes that are commonly dysregulated in PAH of various etiologies and could be used as biomarkers and/or therapeutic targets. In this study, we performed comparative transcriptome analysis of five mammalian PAH datasets downloaded from a public database. We identified 228 differentially expressed genes (DEGs) from a rat PAH model caused by inhibition of vascular endothelial growth factor receptor under hypoxic conditions, 379 DEGs from a mouse PAH model associated with systemic sclerosis, 850 DEGs from a mouse PAH model associated with schistosomiasis, 1598 DEGs from one cohort of human PAH patients, and 4260 DEGs from a second cohort of human PAH patients. Gene-by-gene comparison identified four genes that were differentially upregulated or downregulated in parallel in all five sets of DEGs. Expression of coiled-coil domain containing 80 (CCDC80) and anterior gradient two genes was significantly increased in the five datasets, whereas expression of SMAD family member six and granzyme A was significantly decreased. Weighted gene co-expression network analysis revealed a connection between CCDC80 and collagen type I alpha 1 (COL1A1) expression. To validate the function of CCDC80 in vivo, we knocked out ccdc80 in zebrafish using the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system. In vivo imaging of zebrafish expressing a fluorescent protein in endothelial cells showed that ccdc80 deletion significantly increased the diameter of the ventral artery, a vessel supplying blood to the gills. We also demonstrated that expression of col1a1 and endothelin-1 mRNA was significantly decreased in the ccdc80-knockout zebrafish. Finally, we examined Ccdc80 immunoreactivity in a rat PAHmodel and found increased expression in the hypertrophied media and adventitia of the pre-acinar pulmonary arteries (PAs) and in the thickened intima, media, and adventitia of the obstructed intra-acinar PAs. These results suggest that increased expression of CCDC80 may be involved in the pathogenesis of PAH, potentially by modulating the expression of endothelin-1 and COL1A1.

Potential contribution of phenotypically modulated smooth muscle cells and related inflammation in the development of experimental obstructive pulmonary vasculopathy in rats.

We tested the hypothesis that phenotypically modulated smooth muscle cells (SMCs) and related inflammation are associated with the progression of experimental occlusive pulmonary vascular disease (PVD). Occlusive PVD was induced by combined exposure to a vascular endothelial growth factor receptor tyrosine kinase inhibitor Sugen 5416 and hypobaric hypoxia for 3 weeks in rats, which were then returned to ambient air. Hemodynamic, morphometric, and immunohistochemical studies, as well as gene expression analyses, were performed at 3, 5, 8, and 13 weeks after the initial treatment (n = 78). Experimental animals developed pulmonary hypertension and right ventricular hypertrophy, and exhibited a progressive increase in indices of PVD, including cellular intimal thickening and intimal fibrosis. Cellular intimal lesions comprised α smooth muscle actin (α SMA)+, SM1+, SM2+/-, vimentin+ immature SMCs that were covered by endothelial monolayers, while fibrous intimal lesions typically included α SMA+, SM1+, SM2+, vimentin+/- mature SMCs. Plexiform lesions comprised α SMA+, vimentin+, SM1-, SM2- myofibroblasts covered by endothelial monolayers. Immature SMC-rich intimal and plexiform lesions were proliferative and were infiltrated by macrophages, while fibrous intimal lesions were characterized by lower proliferative abilities and were infiltrated by few macrophages. Compared with controls, the number of perivascular macrophages was already higher at 3 weeks and progressively increased during the experimental period; gene expression of pulmonary hypertension-related inflammatory molecules, including IL6, MCP1, MMP9, cathepsin-S, and RANTES, was persistently or progressively up-regulated in lungs of experimental animals. We concluded that phenotypically modulated SMCs and related inflammation are potentially associated with the progression of experimental obstructive PVD.

Thrombomodulin protects against lung damage created by high level of oxygen with large tidal volume mechanical ventilation in rats

BackgroundVentilator-induced lung injury (VILI) is associated with inflammatory responses in the lung. Thrombomodulin (TM), a component of the coagulation system, has anticoagulant and anti-inflammatory effects. We hypothesized that the administration of recombinant human soluble TM (rhsTM) would block the development of lung injury.MethodsLung injury was induced by high tidal volume ventilation for 2 h with 100% oxygen in rats. Rats were ventilated with a tidal volume of 35 ml/kg with pretreatment via a subcutaneous injection of 3 mg/kg rhsTM (HV (high tidal volume)/TM) or saline (HV/SAL) 12 h before mechanical ventilation. Rats ventilated with a tidal volume of 6 ml/kg under 100% oxygen with rhsTM (LV (low tidal volume)/TM) or saline (LV/SAL) were used as controls. Lung protein permeability was determined by Evans blue dye (EBD) extravasation.ResultsLung injury was successfully induced in the HV/SAL group compared with the LV/SAL group, as shown by the significant decrease in arterial oxygen pressure (PaO2), increased protein permeability, and increase in mean pulmonary artery pressure (mPAP) and ratio of mean pulmonary artery pressure to mean artery pressure (Pp/Ps). Treatment of rats with lung injury with rhsTM (HV/TM) significantly attenuated the decrease in PaO2 and the increase in both mPAP and Pp/Ps, which was associated with a decrease in the lung protein permeability. Lung tissue mRNA expressions of interleukin (IL)-1α, IL-1β, IL-6, tumor necrosis factor-α, and macrophage inflammatory protein (MIP)-2 were significantly higher in HV than in LV rats. Rats with VILI treated with rhsTM (HV/TM) had significantly lower mRNA expressions of IL-1α, IL-1β, IL-6, and MIP-2 than those expressions in HV/SAL rats.ConclusionsAdministration of rhsTM may prevent the development of lung injury created by high level of oxygen with large tidal volume mechanical ventilation, which has concomitant decrease in proinflammatory cytokine and chemokine expression in the lung.

Clinical Application of Inhaled Nitric Oxide

Inhaled nitric oxide (NO) is a selective pulmonary vasodilator because it does not reduce systemic blood pressure. Inhaled NO dilates constricted pulmonary vessels by activating guanylate cyclase of pulmonary vascular smooth muscle cells and is inactivated by hemoglobin when it diffuses into the bloodstream. Inhaled NO improves arterial oxygenation in the lungs with increased intrapulmonary shunt by shifting the blood flow to ventilated units accessible to NO from nonventilated units. In the lung with a broad distribution of units with low ventilation perfusion (V/Q) ratios, inhaled NO alone reduces arterial oxygenaton by deteriorating the V/Q mismatch through inhibition of hypoxic pulmonary vasoconstriction, so combined inhalation of oxygen is necessary to achieve NO-induced improvement of oxygenation. Inhaled NO is a registered treatment for full-term infants with persis tent pulmonary hypertension of neonates and might be indicated in pulmonary vasoreactivity testing for cardiac catheterization, patients with cardiac surgery, treatment of acute right-sided heart failure in cardiac transplant recipients, left ventricular assist device patients with elevated pulmonary vascular resistance, and high-altitude pulmonary edema. A meta-analysis of 12 randomized controlled trials does not indicate the routine use of inhaled NO in patients with acute respiratory distress syndrome (ARDS), although it is currently performed as a rescue therapy in patients with severe ARDS who require extracorporeal membrane oxygenation. Inhaled NO might reduce reperfusion injury and inflammation in remote organs other than the lung such as for liver transplantation, which is mediated by NO containing intermediates such as nitrite and nitrosothiol and could become a new indication of inhaled NO.

Effect of lipid emulsion infusion on paliperidone pharmacokinetics in the acute overdose rat model: A potential emergency treatment for paliperidone intoxication

&NA; Paliperidone prolongs cardiac repolarization in a concentration‐dependent manner. Meanwhile, continuous infusion of intravenous lipid emulsion (ILE) has been established as a detoxification therapy for lipophilic drugs. However, this change in pharmacokinetics of various drugs following ILE administration remains to be clarified. Our objective is to clarify the effect of continuous infusion of ILE on the pharmacokinetics of overdosed paliperidone in rats. Paliperidone (20 mg/kg) was administered orally to free‐moving male Wistar rats. Continuous infusion (initial loading dose: 4 ml/kg for 10 min, followed by 4 ml/kg/h for 12 h) of ILE or acetated Ringers solution (AR) was initiated 30 min after paliperidone administration. Plasma concentration profile of paliperidone was monitored for 12 h after administration. The plasma concentration and tissue/plasma concentration ratios of paliperidone were compared between ILE and AR groups. The rat group infused with ILE showed a higher area under the concentration–time curve (mean [S.D.]: 6102 [900.9] vs. 3407 [992.1] ng h ml−1, p = 0.02) and longer elimination half‐time (t1/2) (4.1 [0.9] vs. 2.2 [0.4] h, p = 0.02) compared with the AR group. Tissue/plasma concentration ratios of paliperidone were lower in ILE rats than in AR rats (1.98 [0.70] vs. 3.82 [1.47] in the heart, p = 0.04; 0.28 [0.29] vs. 1.27 [0.58] in the brain, p < 0.001). In conclusion, continuous infusion of ILE would reduce tissue distribution and prolonged the t1/2 of paliperidone in rats. These results suggest that continuous infusion of ILE has potential as an emergency treatment for acute paliperidone intoxication. Graphical abstract Figure. No caption available.

Nitric Oxide in Pathophysiology and Treatment of Pulmonary Hypertension

All conditions causing pulmonary hypertension (PH) are characterized by three major changes in the pulmonary vasculature: vasoconstriction, vascular remodeling, and thrombosis [1,2,3]. Vascular remodeling includes muscularization of normally non-muscular peripheral pulmo‐ nary arteries, increase in medial wall thickness of muscular arteries, and increase in vascular connective tissue such as collagen and elastin [1,2,3]. Imbalance of vasoconstrictive and vasodilatory mediators might explain the increased vascular tone [1,2,3]. Endothelial cells synthesize and release prostacylin and nitric oxide for vasodilation as well as endothelin and thromboxane for vasoconstriction. Approved treatments for pulmonary arterial hypertension (PAH) include prostacyclins, endothelin receptor blockers, and phosphodiesterase-5 inhibitors as well as inhaled NO for persistent pulmonary hypertension of the neonate (PPHN) [2].