Identification of low circulatory transforming growth factor beta-1 in patients with degenerative heart valve disease

Arrhythmogenic Hearts in PKD2 Mutant Mice Are Characterized by Cardiac Fibrosis, Systolic, and Diastolic Dysfunctions

Autosomal dominant polycystic kidney disease (PKD) is a hereditary disorder affecting multiple organs, including the heart. PKD has been associated with many cardiac abnormalities including the arrhythmogenic remodeling in clinical evaluations. In our current study, we hypothesized that Pkd2 gene mutation results in structural and functional defects in the myocardium. The structural and functional changes of Pkd2 mutant hearts were analyzed in the myocardial-specific Pkd2 knockout (KO) mouse. We further assessed a potential role of TGF-b₁ signaling in the pathology of Pkd2-KO hearts. Hearts from age-matched 6-month-old MyH6•Pkd2 ^wt/wt (control or wild-type) and MyH6•Pkd2 ^flox/flox (mutant or Pkd2-KO) mice were used to study differential heart structure and function. Cardiac histology was used to study structure, and the "isolated working heart" system was adapted to mount and perfuse mouse heart to measure different cardiac parameters. We found that macrophage1 (M1) and macrophage 2 (M2) infiltration, transforming growth factor (TGF-b₁) and TGF-b₁ receptor expressions were significantly higher in Pkd2-KO, compared to wild-type hearts. The increase in the extracellular matrix in Pkd2-KO myocardium led to cardiac hypertrophy, interstitial and conduction system fibrosis, causing cardiac dysfunction with a predisposition to arrhythmia. Left ventricular (LV) expansion or compliance and LV filling were impaired in fibrotic Pkd2-KO hearts, resulted in diastolic dysfunction. LV systolic contractility and elastance decreased in fibrotic Pkd2-KO hearts, resulted in systolic dysfunction. Compared to wild-type hearts, Pkd2-KO hearts were less responsive to the pharmacological stress-test and changes in preload. In conclusion, Pkd2-KO mice had systolic and diastolic dysfunction with arrhythmogenic hearts.

SERUM OSTEOPONTIN LEVEL IS ASSOCIATED WITH PRESENCE OF ATRIAL FIBRILLATION IN CALCIFIC AORTIC VALVE STENOSIS

Identification of risk factors associated with presence of atrial fibrillation (AF) in patients with aortic valve stenosis (AS) remains to be unraveled.The aim of the study was to investigate relationship between profibrotic biomarkers and presence of AF in AS patientsMethods. 191 patients (29,8% male, 77,7±0,59 years) with AS (defined as aortic valve area (AVA) ≤ 2,0 sm2) were enrolled in the study. Clinical, echocardiographic and biochemical variables, including serum TGFβ1 and osteopontin levels were compared between 2 groups of patients: with and without AF. Results. 83(36,5%) of AS patients had AF. In logistic regression models independent associations between AVA index (p=0,040), left atrial volume (p=0,021), OPN (р=0,009) and presence of AF were found. Patients with serum OPN level > 10,05 ng/ml had twice more higher AF incidence comparedto patients with serum OPN level ≤ 10,05 ng/ml (53,8% and 29,2%, respectively, p=0,020).Conclusion. Serum OPN level was independently associated with presence of AF in AS patients, thus we speculate on it’s predominant profibrotic role in the left atrium.

Transforming growth factor β1 is not a reliable biomarker for valvular fibrosis but could be a potential serum marker for invasiveness of prolactinomas (pilot study)

BACKGROUND

Transforming growth factor β1 (TGFβ1) signaling pathway is crucial for both human fibrogenesis and tumorigenesis.

OBJECTIVE

This study aimed to investigate the usefulness of TGFβ1 and matrix metalloproteinase 2 (MMP2) as potential circulating markers for fibrotic valvular heart disease (FVHD) and invasiveness as well as of Fetuin A as a marker for calcification in patients with prolactinomas.

DESIGN

The study population consisted of 147 subjects divided into four groups: 30 dopamine agonist (DA)-treated prolactinoma patients with proven FVHD and three control groups with normal echocardiograms: 43 DA-treated patients, 26 naïve patients, and 48 healthy subjects.

RESULTS

We observed significantly higher serum TGFβ1 levels in all three patient groups than in the healthy subjects (21.4 ± 8.86 vs 19.1 ± 9.03 vs 20.7±11.5 vs 15.8 ± 7.2 ng/ml; P=0.032). Moreover, TGFβ1 levels were significantly higher in patients with macroprolactinomas and invasive prolactinomas than in those with microprolactinomas and noninvasive tumors respectively. In addition, a strong positive linear relationship between TGFβ1 levels and invasiveness score (ρ=0.924; P<0.001) and a moderate correlation between TGFβ1 levels and tumor volume (r=0.546; P<0.002) were observed in patients with invasive prolactinomas. By contrast, prolactin (PRL) levels exhibited a better correlation with tumor volume (r=0.721; P<0.001) than with invasiveness score (ρ=0.436; P<0.020). No significant difference was observed in Fetuin A levels between patients with FVHD and healthy controls. Results concerning MMP2 were unclear.

CONCLUSIONS

TGFβ1, MMP2, and Fetuin A are not reliable biomarkers for valvular fibrosis and calcification in DA-treated patients with prolactinomas, but TGFβ1 may represent a useful serum marker for tumor invasiveness. The simultaneous determination of TGFβ1 and PRL levels could improve the noninvasive assessment of prolactinoma behavior.

Co-ordinating Notch, BMP, and TGF-β signaling during heart valve development

Congenital heart defects affect approximately 1-5 % of human newborns each year, and of these cardiac defects 20-30 % are due to heart valve abnormalities. Recent literature indicates that the key factors and pathways that regulate valve development are also implicated in congenital heart defects and valve disease. Currently, there are limited options for treatment of valve disease, and therefore having a better understanding of valve development can contribute critical insight into congenital valve defects and disease. There are three major signaling pathways required for early specification and initiation of endothelial-to-mesenchymal transformation (EMT) in the cardiac cushions: BMP, TGF-β, and Notch signaling. BMPs secreted from the myocardium set up the environment for the overlying endocardium to become activated; Notch signaling initiates EMT; and both BMP and TGF-β signaling synergize with Notch to promote the transition of endothelia to mesenchyme and the mesenchymal cell invasiveness. Together, these three essential signaling pathways help form the cardiac cushions and populate them with mesenchyme and, consequently, set off the cascade of events required to develop mature heart valves. Furthermore, integration and cross-talk between these pathways generate highly stratified and delicate valve leaflets and septa of the heart. Here, we discuss BMP, TGF-β, and Notch signaling pathways during mouse cardiac cushion formation and how they together produce a coordinated EMT response in the developing mouse valves.