Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5

The mechanosensitive ion channel Piezo1 acts as an anti-inflammatory mediator in the vascular endothelium
B. Fels1, C. Vahldieck1, E. Hertel1, K. Schweim1, K. Kusche-Vihrog1
1Universtität zu Lübeck - Institut für Physiologie, Lübeck;

Vascular tone needs to be continuously monitored and regulated by endothelial cells (ECs) to ensure sufficient blood flow. To resist, sense and transduce extra- and intracellular signals, the surface of ECs, namely the endothelial glycocalyx (eGC) and the underlying cell cortex serves as vaso-protective nanobarrier and interface. ECs are highly flexible and can adjust the mechanical properties of their surface by alternation between ‘soft’ and ‘stiff’ conditions which correlates with a proper endothelial function. To sense and transduce the continuously altering mechanical input, ECs exert a wide variety of mechanosensors, including the mechanosensitive ion channel Piezo1. Here we seek to elucidate the role of Piezo1 in the regulation of endothelial nanomechanics and vascular inflammation.

To test this hypothesis, we analyzed the effects of physiological relevant shear stress on primary human ECs, using the Ibidi pump system and subsequent AFM-based nanoindentation for the quantification of endothelial nanomechanics. eGC was stained with wheat germ agglutinin (WGA) and cortical actin was visualized with Phalloidin-TRITC. Piezo1 expression/membrane abundance was analyzed with qPCR and/or IF stainings. To elucidate the impact of Piezo1 in vascular inflammation, we quantified the monocyte adhesion on ECs after stimulations with TNFα with and without the chemical Piezo1 agonist Yoda1 (5 µM, 24h).

Chronic laminar shear stress (LSS, 8 dyn/cm2) leads to increased cortical stiffness (LSS Δ+19.3 ± 0.1 % vs. control) and polymerization of cortical actin (control 44.9 ± 1. 8 a.u. vs. LSS 57.7 ± 4.1 a.u.) compared to controls (no shear stress). In mechanically stiff ECs, the Piezo1 mRNA expression was induced (1.5x compared to control), confirming Piezo1 function in shear stress sensing. These data were validated by Piezo1 stainings and Δ+43.8 ± 1.9 % increased membrane abundance of the channel in stiff ECs compared to controls. Piezo1 activation by its agonist Yoda1 (5 µM) led to a softening of the endothelial cortex (control 1.09 ± 0.02 pN/nm vs. Yoda1 0.91 ± 0.02 pN/nm). Neither mRNA expression nor number of Piezo1 channels within the membrane was changed after Yoda 1 application, indicating increased open probability. Stimulation of Piezo1 also led to an improved eGC, characterized by a soft (Δ-23.3 %) and upright (Δ+3.0 %) eGC layer. Incubation with the pro-inflammatory cytokine TNFα decreased eGC height (control 116.1 ± 3.9 nm vs. TNFα 83.8 ± 2.6 nm), whereas a parallel activation of Piezo1 by Yoda1 attenuated this effect (TNFα+Yoda1 122.8 ± 3.6 nm). Of note, Piezo1 activation also reduced the number of adherent monocytes on the EC surface (control vs. Yoda1 Δ-63.3 ± 2.0 %).

It can be concluded that the EC surface including integrated mechanosensitive Piezo1 channels builds a highly dynamic regulatory hub to transmit and process mechanical signals of the streaming blood. Piezo1 is involved in the regulation of endothelial nanomechanics and function. Changes in Piezo1 channels function impact on immune cell adhesion, an important step within the inflammatory cascade. Since disturbed mechanosignaling is linked to vascular dysfunction, Piezo1 channels could serve as both predictors and anti-inflammatory pharmaceutical targets in cardiovascular pathologies.


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