Lung tissue remodelling in MCT-induced pulmonary hypertension: a proposal for a novel scoring system and changes in extracellular matrix and fibrosis associated gene expression

Abstract

Pulmonary hypertension (PH) is associated with vasoconstriction and remodelling. We studied lung tissue remodelling in a rat model of PH with special focus on histology and extracellular matrix (ECM) remodelling. After induction of PH by monocrotaline, lung tissue was analysed histologically, by gene expression analysis and immunofluorescence labelling of ED-A domain containing fibronectin (ED-A + Fn), B domain containing tenascin-C (B + Tn-C) as well as alpha-smooth muscle actin (α-SMA). Serum concentrations of ED-A + Fn were determined by ELISA. Systolic right ventricular pressure (RVPsys) values were significantly elevated in PH ( n = 18; 75 ± 26.4 mmHg) compared to controls ( n = 10; 29 ± 19.3 mmHg; p = 0.015). The histological sum-score was significantly increased in PH (8.0 ± 2.2) compared to controls (2.5 ± 1.6; p < 0.001). Gene expression analysis revealed relevant induction of several key genes of extracellular matrix remodelling. Increased protein deposition of ED-A + Fn but not of B + Tn-C and α-SMA in lung tissue was found in PH (2.88 ± 3.19 area%) compared to controls (1.32 ± 0.16 area%; p = 0.030). Serum levels of ED-A + Fn were significantly higher in PH ( p = 0.007) positively correlating with RVPsys (r = 0.618, p = 0.019). We here present a novel histological scoring system to assess lung tissue remodelling in PH. Gene expression analysis revealed induction of candidate genes involved in collagen matrix turnover, fibrosis and vascular remodelling. The stable increased tissue deposition of ED-A + Fn in PH as well as its dynamics in serum suggests a role as a promising novel biomarker and potential therapeutic target.

Therapeutic Evaluation of Antibody-Based Targeted Delivery of Interleukin 9 in Experimental Pulmonary Hypertension

“…The concept of F8 based targeted delivery of IL9 to pulmonary vascular as well as right ventricular cardiac tissue remodeling occurring in PH presumes the strong expression of EDA(+) fibronectin, which is the epitope specifically recognized by F8. As proven recently by our group in the rat model of MCT-induced PH [ 5 ], we could also demonstrate its strong re-occurrence in PH associated tissue damage in the corresponding mouse model used in this study. As compared to sham-treated controls, in MCT-induced PH, EDA(+) fibronectin is strongly expressed, and its tissue distribution shows, in particular, clear spatial associations to vessel structures in the lung and to cardiac interstitial fibrosis in the RV ( Figure 9 ).…”

“…Recently, our group has identified extra domain A (EDA) (+)-fibronectin as a remodeling marker of PH in rats [ 5 ]. Interestingly, EDA overexpression has been reported in a variety of inflammatory conditions characterized by substantial tissue remodeling (e.g., endometriosis, arthritis, psoriasis, atherosclerosis, vasculopathy, and certain inflammatory bowel conditions) [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

Arginase Inhibition Reverses Monocrotaline-Induced Pulmonary Hypertension

“…We used a sum-score system comprising all relevant features of PH associated lung alterations on the histological level including pulmonary vascular remodelling. This scoring system has been recently developed by our group [ 44 ]. As described above, nor-NOHA treatment (MCT/nor-NOHA group) resulted in a significant reduction of the sum-score levels compared to the MCT group.…”

“…In detail, the semi-quantitative score was assessed as follows: parameter 1 = atelectasis area (area in % of atelectasis related to total area of tissue section): not detectable = 0 points, <30% = 1 point, ≥30% = 2 points; parameter 2 = emphysema area (area in % of emphysema related to total area of tissue section): not detectable = 0 points, <30% = 1 point, ≥30% = 2 points; parameter 3 = media hypertrophy of peribronchial arteries (cellular hypertrophy of the tunica media of arteries spatially associated to bronchial structures): not detectable = 0 points, weak = 1 point, moderate = 2 points, severe = 3 points; parameter 4 = perivascular cellular edema of peribronchial arteries (cellular edema locates in the perivascular region around peribronchial arteries): not detectable = 0 points, detectable = 2 points; parameter = media hypertrophy of small arteries (cellular hypertrophy of the tunica media of small arteries showing no spatial association to bronchial structures): not detectable = 0 points, weak = 1 point, moderate = 2 points, severe = 3 points. The maximum sum-score value is 12 points [ 44 ].…”

DDCI‐01, a novel long acting phospdiesterase‐5 inhibitor, attenuated monocrotaline‐induced pulmonary hypertension in rats

“…Immunohistochemical staining was performed as previously described. [23][24][25] The developed tissue sections were imaged under a microscope (DFC550; Leica Microsystems, Wetzlar, Germany). The wall thickness (WT) and external diameter (ED) of the pulmonary arteries were measured using IPP 6.0 image analysis software (Media Cybernetics, Rockville, MD, USA).…”