Nuclear deformation mediates liver cell mechanosensing in cirrhosis

Abstract Background aims Liver stiffness is increased in advanced chronic liver disease (ACLD) and accurately predicts prognosis in this population. Recent data suggest that extracellular matrix stiffness per se may modulate liver cells’ phenotype. We aimed at investigating the effect of matrix stiffness on the phenotype of cirrhotic liver cells, assessing its influence on their response to anti-fibrotic strategies and evaluating associated molecular mechanisms. Methods Hepatocytes, hepatic stellate cells and liver sinusoidal endothelial cells were isolated from healthy or cirrhotic rats (CCl4 or thioacetamide) and cultured on polyacrylamide gels with different physiologically-relevant stiffness for 72h. Results All cirrhotic cell types cultured at low stiffness showed a significant phenotype amelioration vs rigid matrix (assessed by quantitative morphology, mRNA expression, protein synthesis and electron microscopy imaging). Additionally, stiffness modified the antifibrotic effects of liraglutide in cirrhotic stellate cells. Finally, evaluation of nuclear morphology revealed that high stiffness induced nuclei deformation in all cell types, observation confirmed in cells from human livers. Disconnecting the nucleus from the cytoskeleton by cytoskeleton disruption or a defective form of nesprin1 significantly recovered spherical nuclear shape and cells’ quiescent phenotype. Conclusions: The environment’s stiffness per se modulates the phenotype of healthy and cirrhotic liver cells by altering the nuclear morphology through cytoskeleton-derived mechanical forces. The reversibility of this mechanism suggests that targeting the stiffness-mediated intracellular mechanical tensions may represent a novel therapeutic strategy for ACLD.