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Browsing by Subject "Transforming growth factor β1"

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  • Lahtinen, Katja (2024)
    Cardiac fibrosis (CF) is a physiological response to various stress factors encountered by the heart, with the aim of maintaining proper functioning of this vital pump in an altered situation such as increased mechanical stress or sudden injury in heart muscle. CF is characterized by excessive production of extracellular matrix (ECM) components and stress fibers in cardiac tissue, accompanied by morphological changes of the heart muscle. The responsible cells behind these changes are fibroblasts (FBs) that undergo phenotypic change by transdifferentiating into myofibroblasts (myoFBs). Although being initially a supportive response, CF can lead to deterioration of the heart performance and even heart failure, if prolonged. Given the lack of effective enough therapies against CF, and the strong involvement of CF in cardiovascular diseases (CVDs) that are associated with high mortality rate, the need for new effective therapies is urgent. Indeed, a diversity of approaches to fight CF have been proposed, among them protein kinase C (PKC) and its signaling cascades. PKC has been shown to play a role in fibrosis and many studies suggest antifibrotic properties of PKC, yet the results are challenged by the opposite findings. Despite the dichotomous results, new small molecules that function as partial agonist of PKC seemed to be a promising strategy for the treatment of fibrosis. To further explore the role of PKC activation in CF, the aim of this study was to first develop and characterize a human cardiac fibroblast (HCF)-based CF model, in which the effects of seven new PKC modulators on HCFs could then be evaluated. To create the CF model and provoke a fibrotic response, HCFs were treated with either transforming growth factor β1 (TGF-β1), Angiotensin II (Ang-II), endothelin-1 (ET-1), or combination of treatments, followed by determination of HCF proliferation activity and α-smooth muscle actin expression (α-SMA), a marker of myoFBs. After the treatments, the original goal was to continue in compound testing phase by exposing the HCFs to the PKC-modulators to see whether any differences could be determined in α-SMA expression or proliferation activity. However, no considerable effects of fibrosis-inducing treatments on the activation of HCFs were observed, thus preventing this progression. Nevertheless, toxicity tests were performed on the compounds and the results indicated relatively low overall toxicity for the lower concentration: six out of seven compounds yielded over 70% HCF viability at 3 μM concentration with three of them reaching even over 80% viability, while the corresponding value for the previously published PKC agonist HMI-1a3 was 54%. Although these results are promising for the lower concentrations of PKC-modulators, it is obvious that more in-depth studies are required prior to drawing any unambiguous conclusions.