Fcγ Receptor Deficiency Attenuates Diabetic Nephropathy

Abstract

Among patients with diabetes, increased production of immunoglobulins against proteins modified by diabetes is associated with proteinuria and cardiovascular risk, suggesting that immune mechanisms may contribute to the development of diabetes complications, such as nephropathy. We investigated the contribution of IgG Fcg receptors to diabetic renal injury in hyperglycemic, hypercholesterolemic mice. Weused streptozotocin to induce diabetes in apolipoprotein E–deficientmice and in mice deficient in both apolipoprotein E and g-chain, the common subunit of activating Fcg receptors. After 15 weeks, the mice lacking Fcg receptors had significantly less albuminuria and renal hypertrophy, despite similar degrees of hyperglycemia and hypercholesterolemia, immunoglobulin production, and glomerular immune deposits. Moreover, diabetic Fcg receptor–deficient mice had less mesangial matrix expansion, inflammatory cell infiltration, and collagen and a-smooth muscle actin content in their kidneys. Accordingly, expression of genes involved in leukocyte infiltration, fibrosis, and oxidative stress was significantly reduced in diabetic kidneys and in mesangial cells cultured from Fcg receptor–deficient mice. In summary, preventing the activation of Fcg receptors alleviates renal hypertrophy, inflammation, and fibrosis in hypercholesterolemic mice with diabetes, suggesting that modulating Fcg receptor signaling may be renoprotective in diabetic nephropathy.