Stimulation of Piezo1 mechanosensitive channels inhibits adipogenesis in thyroid eye disease

Context: Increased orbital tissue volume due to matrix expansion, orbital fibroblast (OF) proliferation and adipocyte differentiation are the hallmarks of thyroid eye disease (TED). Their combination with the presence of hyaluronan-bound excess water in the constrains of the bony orbit results in increased intraorbital pressure. High intraorbital pressure, along with changes in the mechanical properties of orbital tissues, may lead to the activation of mechanosensitive receptors. The expression and role of the Piezo1 mechanoreceptor has not been investigated in TED.

Objective: We aimed to verify the expression of Piezo1 in OFs, and to study the effect of in vitro Piezo1 activation by its synthetic agonist Yoda1 on adipocyte differentiation.

Design/setting/participants: OF cultures were established using orbital connective tissues from patients with TED and controls in the presence or absence of adipogenic stimuli.

Main outcome measures: Piezo1 expression was confirmed by Western Blot and immunofluorescent imaging, and its function was verified by intracellular Ca2+ measurement. Adipogenic differentiation was characterized using Oil Red O staining for lipid accumulation, real-time PCR for gene and Western blot for protein expressions analysis indicative in adipogenesis.

Results: OFs express functional Piezo1 channels. Differentiation into adipocytes is inherent to TED OFs. Piezo1 activation by Yoda1 inhibits the expressions of early (CEBPβ, CEBPδ) and main (PPARγ, CEBPα) transcription factors, and the terminal marker FABP4 during adipogenesis, resulting in markedly lower intracytoplasmic lipid accumulation.

Conclusion: Piezo1 channels are expressed and functional in OFs. Modelling orbital pressure by in vitro Piezo1 activation reduces de novo adipogenesis of OFs derived from TED orbits.