Impaired integrin α₅/β₁‐mediated hepatocyte growth factor release by stellate cells of the aged liver

Abstract

horseradish peroxidase; HSC, hepatic stellate cells; IL6, interleukin-6; IMDM, Iscove's Modified Dulbecco's Medium; ITGA5, integrin α 5 ; ITGB1, integrin β 1 ; ITS, insulin-selenitetransferrin; LAMA2, laminin α2; LAMA4, laminin α4; LAMA5, laminin α5; LAMB1, laminin β1; LAMB2, laminin β2; LAMC1, laminin γ1; LN-211, laminin-211; LN-521, laminin-521; LRAT, lecithin-retinol acyltransferase; MMP13, metalloproteinase 13; NGF, nerve growth factor; NID, nidogen; PBS, phosphate buffered saline; PCA, principal component analysis; PEG, polyethylene glycol; PPARγ, peroxisome proliferator-activated receptor γ; qPCR, quantitative polymerase chain reaction; SASP, senescence-associated secretory phenotype; SEC, sinusoidal endothelial cells; SEM, standard error of the mean; SPARCL1, secreted protein acidic and rich in cysteines-like 1; TGFb, transforming growth factor β; TLN, talin; TNFR, tumor necrosis factor receptor; VCL, vinculin; α-SMA, α-smooth muscle actin. AbstractHepatic blood flow and sinusoidal endothelial fenestration decrease during aging.Consequently, fluid mechanical forces are reduced in the space of Disse where hepatic stellate cells (HSC) have their niche. We provide evidence that integrin α 5 /β 1 is an important mechanosensor in HSC involved in shear stress-induced release of hepatocyte growth factor (HGF), an essential inductor of liver regeneration which is impaired during aging. The expression of the integrin subunits α 5 and β 1 decreases in liver and HSC from aged rats. CRISPR/Cas9-mediated integrin α 5 and β 1 knockouts in isolated HSC lead to lowered HGF release and impaired cellular adhesion. Fluid mechanical forces increase integrin α 5 and laminin gene expression whereas integrin β 1 remains unaffected. In the aged liver, laminin β2 and γ1 protein chains as components of laminin-521 are lowered. The integrin α 5 knockout in HSC reduces laminin expression via mechanosensory mechanisms. Culture of HSC on nanostructured surfaces functionalized with laminin-521 enhances Hgf expression in HSC, demonstrating that these ECM proteins are critically involved in HSC function. During aging, HSC acquire a senescence-associated secretory phenotype and lower their growth factor expression essential for tissue repair. Our findings suggest that impaired mechanosensing via integrin α 5 /β 1 in HSC contributes to age-related reduction of ECM and HGF release that could affect liver regeneration. K E Y W O R D S aging, hepatic stellate cells, integrins, laminins, mechanobiology S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section.

Non-alcoholic Fatty Liver Disease and Liver Fibrosis during Aging

“…Senescent HSC as mentioned earlier may play various roles in NASH: they could be protective against fibrosis while exacerbating inflammation [ 27 , 28 ] and could be linked to an increased risk of tumorigenesis [ 29 ]. Recently it was shown that in the aging liver, mechanosensing via integrin α 5 /β 1 by HSC was dysregulated and HSC acquiring a senescent phenotype had reduced hepatocyte growth factor release impacting regenerative responses [ 121 ]. This highlights the multifaceted role of HSC that should be further explored in the context of aging.…”

Senescence of donor cells impairs fat graft regeneration by suppressing adipogenesis and increasing expression of senescence-associated secretory phenotype factors

“…Senescent cells are characterized by upregulation of proinflammatory cytokines, chemokines, and proteases, which are termed SASP factors [ 33 ]. Given the complex nature of the SASP, senescent cells impact various biological processes that involve paracrine signaling including inflammation [ 34 ], wound healing [ 35 ], and other types of tissue repair [ 36 ]. In this study, several SASP factors, including IL-6, IL-1β, and TNF-α, were highly expressed during the beginning and later phases of regeneration in fat grafts from old donors.…”

Understanding the Unique Microenvironment in the Aging Liver

“…Telomere attrition, a hallmark of the aging liver, also occurs in HSCs ( 64 ). In addition, integrin α5/β1 decreases in HSCs and thereby reduces the levels of hepatocyte growth factor in the aged liver, thus impairs liver regeneration ( 81 ). Moreover, production of ECM components by HSCs, such as laminin, is impaired in aged mice ( 81 , 82 ).…”

“…In addition, integrin α5/β1 decreases in HSCs and thereby reduces the levels of hepatocyte growth factor in the aged liver, thus impairs liver regeneration ( 81 ). Moreover, production of ECM components by HSCs, such as laminin, is impaired in aged mice ( 81 , 82 ). Thus, aging-related HSCs alterations have a vital influence on ECM remodeling.…”