Macrophage promotes fibroblast activation and kidney fibrosis by assembling a vitronectin-enriched microenvironment

Abstract

Background : Renal infiltration of inflammatory cells including macrophages is a crucial event in kidney fibrogenesis. However, how macrophage regulates fibroblast activation in the fibrotic kidney remains elusive. In this study, we show that macrophages promoted fibroblast activation by assembling a vitronectin (Vtn)-enriched, extracellular microenvironment. Methods : We prepared decellularized kidney tissue scaffold (KTS) from normal and fibrotic kidney after unilateral ischemia-reperfusion injury (UIRI) and carried out an unbiased quantitative proteomics analysis. NRK-49F cells were seeded on macrophage-derived extracellular matrix (ECM) scaffold. Genetic Vtn knockout (Vtn-/-) mice and chronic kidney disease (CKD) model with overexpression of Vtn were used to corroborate a role of Vtn/integrin αvβ5/Src in kidney fibrosis. Results : Vtn was identified as one of the most upregulated proteins in the decellularized kidney tissue scaffold from fibrotic kidney by mass spectrometry. Furthermore, Vtn was upregulated in the kidney of mouse models of CKD and primarily expressed and secreted by activated macrophages. Urinary Vtn levels were elevated in CKD patients and inversely correlated with kidney function. Genetic ablation or knockdown of Vtn protected mice from developing kidney fibrosis after injury. Conversely, overexpression of Vtn exacerbated renal fibrotic lesions and aggravated renal insufficiency. We found that macrophage-derived, Vtn-enriched extracellular matrix scaffold promoted fibroblast activation and proliferation. In vitro, Vtn triggered fibroblast activation by stimulating integrin αvβ5 and Src kinase signaling. Either blockade of αvβ5 with neutralizing antibody or pharmacological inhibition of Src by Saracatinib abolished Vtn-induced fibroblast activation. Moreover, Saracatinib dose-dependently ameliorated Vtn-induced kidney fibrosis in vivo. These results demonstrate that macrophage induces fibroblast activation by assembling a Vtn-enriched extracellular microenvironment, which triggers integrin αvβ5 and Src kinase signaling. Conclusion : Our findings uncover a novel mechanism by which macrophages contribute to kidney fibrosis via assembling a Vtn-enriched extracellular niche and suggest that disrupting fibrogenic microenvironment could be a therapeutic strategy for fibrotic CKD.

Effect of RNA interference with HIF-1α on the growth of pulmonary artery endothelial cells in broiler chickens

“…This further confirms that HIF-1α has the potential to regulate collagen expression to modulate the growth of PAECs and influence the development of ascites syndrome in broilers. It has been reported that cells promote fibrosis by assembling vitronectin-rich extracellular ecological niches ( Peng et al, 2023 ). The development of fibrosis is closely related to the development of BAS.…”

Crosstalk between fibroblasts and immunocytes in fibrosis: From molecular mechanisms to clinical trials

“… 168 A macrophage‐derived, Vtn‐enriched extracellular matrix scaffold was found to promote fibroblast activation and proliferation by stimulating integrin αvβ5 and Src kinase signalling. 169 Inhibition of (MMP‐9 produced by macrophages in late‐stage UUO reduced tubular cell EMT. Interestingly, MMP‐9 can also be expressed by myofibroblasts and further recruit macrophages.…”

The extracellular matrix glycoprotein fibrillin-1 in health and disease

“…We recently found that FBN1 exhibits significant upregulation in the decellularized kidney tissue scaffold (KTS) in CKD ( Li et al, 2021 ; Li et al, 2022 ; Li et al, 2023 ; Peng et al, 2023 ). Furthermore, FBN1 expression is elevated across many animal models of CKD as well as in individuals diagnosed with CKD.…”