Journal Article

Macrophages in streptozotocin-induced diabetic nephropathy: potential role in renal fibrosis

Fiona Y. Chow, David J. Nikolic-Paterson, Robert C. Atkins and Gregory H. Tesch

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 19, issue 12, pages 2987-2996
Published in print December 2004 | ISSN: 0931-0509
Published online December 2004 | e-ISSN: 1460-2385 | DOI: http://dx.doi.org/10.1093/ndt/gfh441
Macrophages in streptozotocin-induced diabetic nephropathy: potential role in renal fibrosis

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Background. Renal fibrosis is central to the progression of diabetic nephropathy; however, the mechanisms responsible for fibroblast and matrix accumulation in this disease are only partially understood. Macrophages accumulate in diabetic kidneys, but it is unknown whether macrophages contribute to renal fibrosis. Therefore, we examined whether macrophage accumulation is associated with the progression of renal injury and fibrosis in type 1 diabetic nephropathy and whether macrophages exposed to the diabetic milieu could promote fibroblast proliferation.

Methods. Kidney macrophages, renal injury and fibrosis were analysed in diabetic C57BL/6J mice at 2, 8, 12 and 18 weeks after streptozotocin injection. Isolated rat bone marrow macrophages were stimulated with diabetic rat serum or carboxymethyllysine (CML)-bovine serum albumin (BSA) to determine whether macrophage-conditioned medium could promote the proliferation of rat renal (NRK-49F) fibroblasts.

Results. Progressive injury and fibrosis in diabetic nephropathy was associated with increased numbers of kidney macrophages. Macrophage accumulation in diabetic mice correlated with hyperglycaemia (blood glucose, HbA1c levels), renal injury (albuminuria, plasma creatinine), histological damage and renal fibrosis (myofibroblasts, collagen IV). Culture supernatant derived from bone marrow macrophages incubated with diabetic rat serum or CML-BSA induced proliferation of fibroblasts, which was inhibited by pre-treating fibroblasts with interleukin-1 (IL-1) receptor antagonist or the platelet-derived growth factor (PDGF) receptor kinase inhibitor, STI-571.

Conclusion. Kidney macrophage accumulation is associated with the progression of renal injury and fibrosis in streptozotocin-induced mouse diabetic nephropathy. Elements of the diabetic milieu can stimulate macrophages to promote fibroblast proliferation via IL-1- and PDGF-dependent pathways which may enhance renal fibrosis.

Keywords: interleukin-1; macrophage; platelet-derived growth factor; streptozotocin-induced diabetic nephropathy; renal fibrosis

Journal Article.  5464 words.  Illustrated.

Subjects: Nephrology

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