Institutional creator:

Instytut Biologii Doświadczalnej im. Marcelego Nenckiego PAN

Contributor:

Bandorowicz-Pikuła, Joanna (1965- ) : Supervisor

Publisher:

Instytut Biologii Doświadczalnej im. Marcelego Nenckiego PAN

Place of publishing:

Warszawa

Description:

[1], 132 pages : illustrations ; 30 cm ; Bibliography ; Summary in English

Degree name:

PhD in Biological Sciences

Degree discipline :

biological sciences

Degree grantor:

Nencki Institute of Experimental Biology PAS ; degree obtained in 2024

Type of object:

Thesis

Abstract:

Endothelial dysfunction is the earliest symptom of the cardiovascular system dysfunction observed in obesity. Increased concentration of fatty acids associated with obesity, including the most abundant palmitic acid (PA), may contribute to the development of endothelial dysfunction. Von Willebrand factor (vWF), produced and secreted mainly by endothelial cells, plays an important role in the regulation of coagulation. Increased vWF concentration in the plasma of obese patients is associated with an increased risk of developing cardiovascular diseases caused by increased thrombosis. The aim of this thesis was to investigate the effect of PA on the vWF secretion by HUVEC cells. The experiments were carried out under mild fatty acid stress conditions that were sufficient to increase the amount of ICAM-1 and VCAM-1 adhesion molecules, which is a marker of the pro-inflammatory response of the endothelium, without affecting cell survival. The cells were incubated in the presence of PA at a concentration not exceeding 200 μM for no longer than 48 h. This approach enables the study of adaptive changes in response to a stimulus. It has been shown that under relatively mild conditions vWF secretion is increased after incubation in the presence of PA, as a result of the increased VWF gene expression and stimulated maturation of this protein. Attempts have been made to identify the mechanisms of PA's regulatory influence on vWF maturation and secretion, but no conclusive results have been obtained. The results presented in this study confirmed that PA activates NF-κB, a transcription factor involved in the regulation of the inflammatory response. Moreover, it has been shown that PA affects the content of TLR2, TLR4 and TLR6 receptor proteins. To identify the signaling pathway activated by PA, inhibitors of NF-κB and TLR2 and TLR4 receptors were used, that is cardamonin, C29 and TAK-242, respectively. It has been shown that VWF gene expression increased by PA is the result of NF-κB activation. Moreover, the involvement of the TLR4 receptor in the PA-activated endothelial cells response was confirmed. Additionally, in the presence of a TLR4 inhibitor and PA, which is its ligand, the expression of CD36, TIRAP, TLR6 genes, encoding proteins involved in TLR receptor signal transduction, was increased. In the presence of a TLR2 inhibitor, TLR4 activity was increased. Moreover, TLR2 gene silencing increased TLR4 protein level. TLR4 gene silencing increased TLR2 level, which was observed even when only mRNA level of TLR4 was decreased. This suggests a compensatory effect between TLR2 and TLR4 receptors. To conclude, this thesis shows that PA regulates the vWF secretion from endothelial cells by increased expression of the VWF gene and maturation of this protein. The involvement of the TLR4 receptor and the NF-κB signaling pathway in the cell response to PA was identified. Moreover, it has been shown that there is a compensatory effect between TLR2 and TLR4 receptors, observed at the receptor activity as well as mRNA and protein level. The obtained results suggest that a relatively small increase in the concentration of fatty acids to a level that activates the pro-inflammatory response may be sufficient to increase concentration of the extracellular vWF, potentially resulting in thrombotic complications. The involvement of PA in the regulation of the vWF secretion partially explains the increased vWF concentration observed in the plasma of obese patients.

Detailed Resource Type:

PhD Dissertations

Resource Identifier:

oai:rcin.org.pl:242441

Source:

IBD PAN, call no. 20521

Language:

pol

Language of abstract:

eng

Rights:

Rights Reserved - Free Access

Terms of use:

Copyright-protected material. May be used within the limits of statutory user freedoms

Copyright holder:

Publication made available with the written permission of the author

Digitizing institution:

Nencki Institute of Experimental Biology of the Polish Academy of Sciences

Original in:

Library of the Nencki Institute of Experimental Biology PAS

Access:

Open