Extra-domain A containing fibronectin in pulmonary hypertension and treatment effects of a function-blocking antibody.

Abstract

Pulmonary vascular and right ventricular remodelling processes are important for development and progression of pulmonary hypertension (PH). The current study analyzed the functional role of the extra domain A containing fibronectin (ED-A+ Fn) for the development of PH by comparing ED-A+ Fn knockout (KO) and wild-type (WT) mice as well as the effects of an antibody-based therapeutical approach in a model of monocrotaline (MCT)-induced PH, which will be validated in a model of Sugen 5416/Hypoxia induced PH. PH was induced using monocrotaline (MCT) (PH mice). 69 mice were divided into the following groups: sham-treated controls (WT: n=7; KO: n=7), PH mice without specific treatment (WT: n=12; KO: n=10), PH mice treated with a dual endothelin receptor antagonist (MAC; WT: n=6; KO: n=11), WT PH mice treated with the F8 antibody, specifically recognizing ED-A+ Fn, (n=8) and WT PH mice treated with an antibody of irrelevant antigen specificity (KSF, n=8). Compared to controls, WT_PH mice showed a significant elevation of the right ventricular systolic pressure (RVPsys, p=0.04) and RV functional impairment including increased basal right ventricular (RVbasal, p=0.016) diameter or tricuspid annular plane systolic excursion (TAPSE, p=0.008). In contrast, KO PH did not show such effects compared to controls (p=n.s.). In WT_PH mice treated with F8, hemodynamic and echocardiographic parameters were significantly improved compared to untreated WT_PH mice or those treated with the KSF antibody (p<0.05). On the microscopic level, KO_PH mice showed significantly less tissue damage compared to the WT_PH mice (p=0.008). Furthermore, lung tissue damage could significantly be reduced after F8 treatment (p=0.04). Additionally, these findings could be verified in the Sugen 5416/Hypoxia mouse model, in which F8 significantly improved echocardiographic, hemodynamic and histologic parameters. ED-A+ Fn is of crucial importance for PH pathogenesis representing a promising therapeutic target in PH. We here show a novel therapeutic approach using antibody-mediated functional blockade of ED-A+ Fn capable to attenuate and partially reverse PH-associated tissue remodelling.