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

AIMS: 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. METHODS AND RESULTS: 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. CONCLUSION: 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.

Prognostic Value of Galectin-3 after Left Atrial Appendage Occlusion for Predicting Peri-Device Leakage.

Echocardiographic detection of residual peri-device leakage (PDL) after percutaneous left atrial appendage occlusion (LAAO) is crucial for managing anticoagulation. Galectin-3, a protein involved in tissue-foreign body interactions, may hold significance in understanding PDL and cardiac tissue remodeling after LAAO. This study aimed to analyze galectin-3 serum levels in relation to PDL using a novel echo-morphological classification. LAAO eligible patients were included in the study. Galectin-3 serum levels were measured before LAAO, at 45 days (45D), and at 6 months (6M) after the procedure. Transesophageal echocardiography was used to assess LAAO success. A new echo-morphological classification categorized the degree of LAAO into three different types (A: homogenous echodensity, indicating completely thrombosed device; B: inhomogeneous echolucencies (<50% of device); and C: partially thrombosed device with echolucencies > 50%). Among 47 patients, complete LAAO was achieved in 60% after 45D and in 74% after 6M. We observed a significant increase and distribution of serum levels of galectin-3 [ng/mL] after 45D among the three types (baseline: 13.1 ± 5.8 ng/mL; 45D: 16.3 ± 7.2 ng/mL (Type A) vs. 19.2 ± 8.6 ng/mL (Type B) vs. 25.8 ± 9.4 ng/mL (Type C); p = 0.031), followed by a drop in galectin-3 for Types A and B after 6M toward and below the baseline levels (6M: 8.9 ± 3.1 ng/mL (Type A) vs. 12.4 ± 5.5 ng/mL (Type B)), whereas Type C persisted in showing elevated galectin-3 levels compared to all other types (6M: 17.5 ± 4.5 ng/mL (Type C); p < 0.01). Increased galectin-3 serum levels after LAAO likely reflect the transition from thrombus formation to fibrotic scar development in the LAA lumen. Successful occlusion is associated with a time-restricted decrease in galectin-3 levels after 6 months, while relevant PDL leads to persistently elevated levels, making galectin-3 a potential predictor of occlusion success.

Comparative analysis of oncofetal fibronectin and tenascin-C expression in right atrial auricular and left ventricular human cardiac tissue from patients with coronary artery disease and aortic valve stenosis.

Aortic valve stenosis (AVS) and coronary artery disease (CAD) are accompanied by changes in the cardiac extra cellular matrix (cECM) including the re-expression of oncofetal fibronectin (Fn) and tenascin-C (Tn-C) variants. Human antibodies against these variants are usable for targeted therapy. Aim of the study was the comparative analysis of cECM remodelling in tissue samples from right atrial auricle (RAA) and left ventricular septum (LVS). RAA and LVS specimens from 30 patients (17 × AVS; 13 × AVS+CAD) were analysed with respect to histological changes and ECM remodelling using PCR based ECM gene expression profiling. Re-expression of ED-A(+) Fn and A1(+) Tn-C was investigated on the mRNA and on the protein level. For immunofluorescence, human recombinant small immunoprotein (SIP) format antibodies were used. There was a positive correlation of the grade of histological changes in RAA and corresponding LVS samples (r = 0.695). ECM gene expression levels were higher in LVS compared to RAA. For 24 genes, a corresponding relevant (>2.5-fold) up- or down-regulation in RAA and LVS occurred. Using SIP antibodies, a positive correlation of protein deposition levels in RAA and corresponding LVS (r = 0.818) could be shown for ED-A(+) Fn. Cardiac tissue remodelling is likely a process involving the entire heart reflected by intra-individually comparable histology and cECM changes in RAA and LVS samples. ED-A(+) Fn might be an excellent target for an antibody-mediated delivery of diagnostic or therapeutic agents. The RAA is a valuable and representative tool to evaluate cardiac remodelling and to plan individualized therapy.

Changes in extra cellular matrix remodelling and re-expression of fibronectin and tenascin-C splicing variants in human myocardial tissue of the right atrial auricle: implications for a targeted therapy of cardiovascular diseases using human SIP format antibodies.

Cardiovascular diseases are accompanied by changes in the extracellular matrix (ECM) including the re-expression of fibronectin and tenascin-C splicing variants. Using human recombinant small immunoprotein (SIP) format antibodies, a molecular targeting of these proteins is of therapeutic interest. Tissue samples of the right atrial auricle from patients with coronary artery disease and valvular heart disease were analysed by PCR based ECM gene expression profiling. Moreover, the re-expression of fibronectin and tenascin-C splicing variants was investigated by immunofluoerescence labelling. We demonstrated changes in ECM gene expression depending on histological damage or underlying cardiac disease. An increased expression of fibronectin and tenascin-C mRNA in association to histological damage and in valvular heart disease compared to coronary artery disease could be shown. There was a distinct re-expression of ED-A containing fibronectin and A1 domain containing tenascin-C detectable with human recombinant SIP format antibodies in diseased myocardium. ED-A containing fibronectin showed a clear vessel positivity. For A1 domain containing tenascin-C, there was a particular positivity in areas of interstitial and perivascular fibrosis. Right atrial myocardial tissue is a valuable model to investigate cardiac ECM remodelling. Human recombinant SIP format antibodies usable for an antibody-mediated targeted delivery of drugs might offer completely new therapeutic options in cardiac diseases.