The matrix protein Fibulin-5 is at the interface of tissue stiffness and inflammation in fibrosis

Fibrosis is a pervasive disease in which the excessive deposition of extracellular matrix (ECM) compromises tissue function. Although the underlying mechanisms are mostly unknown, matrix stiffness is increasingly appreciated as a contributor to fibrosis rather than merely a manifestation of the disease. Here we show that the loss of Fibulin-5, an elastic fibre component, not only decreases tissue stiffness, but also diminishes the inflammatory response and abrogates the fibrotic phenotype in a mouse model of cutaneous fibrosis. Increasing matrix stiffness raises the inflammatory response above a threshold level, independent of TGF-β, to stimulate further ECM secretion from fibroblasts and advance the progression of fibrosis. These results suggest that Fibulin-5 may be a therapeutic target to short-circuit this profibrotic feedback loop. Stiffness in the extracellular matrix is thought to contribute to pathological cutaneous fibrosis. Here, the authors identify the elastic fibre protein Fibulin-5 as a link and potential therapeutic target mediating the transition of cutaneous stiffening to fibrosis.