Progressive Renal Disease: Fibroblasts, Extracellular Matrix, and Integrins

Publisher Website
Google Scholar
Abstract
Progressive renal disease is characterized by expansion of the tubulo-interstitium and accumulation of extracellular matrix within this tissue compartment. Interstitial fibroblasts are the primary producers of the interstitial matrix, and in the evolution of tubulo-interstitial fibrosis these cells undergo changes, namely increased proliferation, differentiation to myofibroblasts, and altered extracellular matrix metabolism, all of which, in other cell types, have been shown to be regulated by the major family of extracellular matrix receptors, the integrins. In the normal kidney, interstitial fibroblasts express α1, α4, α5, and β1 integrins, and fibrosis is associated with increased expression of α1, α2, α5, αv, and β1 integrins. In particular, α5, β1, and αv are suggested to be linked with the fibrotic process. In vitro, renal fibroblasts express a similar range of integrins, and ligation of selected receptors is associated with specific functions. Ligation of α6 stimulates proliferation, while α5 promotes expression of myofibroblastic phenotype, and β1 integrin has been implicated in cell contraction. Recent studies suggest that renal fibroblasts also express the non-integrin matrix receptors, discoidin domain receptors, and that changes in activation of these receptors may be associated with fibrogenic events. Thus the current, albeit limited, data suggest an important role for receptors for extracellular matrix molecules in the pathogenesis of progressive renal fibrosis.