Myofibroblasts are the major source of extracellular matrix components that accumulate during tissue
fibrosis, and hepatic stellate cells (HSCs) are believed to be the major source of myofibroblasts in the liver. To date, robust systems to genetically manipulate these cells have not been developed. We report that Cre under control of the promoter of
Pdgfrb (
Pdgfrb-Cre) inactivates loxP-flanked genes in mouse HSCs with high efficiency. We used this system to delete the gene encoding α(v)
integrin subunit because various α(v)-containing
integrins have been suggested as central mediators of
fibrosis in multiple organs. Such depletion protected mice from
carbon tetrachloride-induced hepatic
fibrosis, whereas global loss of β₃, β₅ or β₆
integrins or conditional loss of β₈
integrins in HSCs did not. We also found that
Pdgfrb-Cre effectively targeted myofibroblasts in multiple organs, and depletion of the α(v)
integrin subunit using this system was protective in other models of organ
fibrosis, including pulmonary and renal
fibrosis. Pharmacological blockade of α(v)-containing
integrins by a small molecule (CWHM 12) attenuated both liver and lung
fibrosis, including in a therapeutic manner. These data identify a core pathway that regulates
fibrosis and suggest that pharmacological targeting of all α(v)
integrins may have clinical utility in the treatment of patients with a broad range of fibrotic diseases.