Bronchopulmonary dysplasia is a common pathology of premature newborns caused by oxidative stress and mechanical ventilation, resulting in hypoalveolization and impaired angiogenesis. It can be complicated by pulmonary hypertension (HTP-DBP) with excess mortality. Celastrol has anti-inflammatory and antioxidant properties and we addressed its potential therapeutic interest in HTP-DBP.

Different concentrations of celastrol were used in a murine model of hyperoxic HTP-DBP (14 days with 90% O2) and we evaluated hemodynamic parameters with echocardiography and lung remodeling with histological methods. Pulmonary arterial (PA) reactivity was addressed with myograph. Cytoplasmic calcium (Ca2+i) response to endothelin-1 (ET-1) was evaluated in human fetal PA smooth muscle cells (fPASMC) with spectrophotometry in normoxic (21% O2) and hyperoxic conditions (48h with 60% O2). Inflammation was addressed with IL6 ELISA assay in fPASMC.

Celastrol reduces mortality at doses of 1 and 0.5mg/kg/d compared to the hyperoxic control group. At 1mg/kg/d, it normalizes PAAT (PA acceleration time) (P<0.001) and reduces vascular hyperreactivity to phenylephrine (P<0.001) with no effect on the alteration of the response to acetylcholine induced by hyperoxia. At doses of 0.1, 0.5 and 1mg/kg/d, it decreases right heart hypertrophy and vascular remodeling (wall thickness) but has no effect on alveolization and vascular density (vWF staining). Finally, although celastrol (0.1 and 0.3μM) decreases the increased Ca2+i response to ET-1 in hyperoxia in fPASMC, expression of ET-1 receptors (Western blotting and qPCR for ET-A and ET-B) was unchanged. However, celastrol 0.5μM decreases ET-1 concentration measured with an ELISA assay in human umbilical arterial endothelial cells. An increased concentration of IL6 was also observed in fPASMC in hyperoxia and was decreased by celastrol 0.5μM.

Celastrol has a preventive dose-dependent effect on some hallmarks of HTP induced by hyperoxia and could thus be considered as an interesting new potential therapeutic option for HTP-DBP.