NDT Advance Access originally published online on October 18, 2005
Nephrology Dialysis Transplantation 2005 20(12):2690-2696; doi:10.1093/ndt/gfi232
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Advanced glycation end-product induces fractalkine gene upregulation in normal rat glomeruli
Second Department of Internal Medicine, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513 Japan
Correspondence and offprint requests to: Yuichi Kikuchi, MD, Second Department of Internal Medicine, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513 Japan. Email: grd1615{at}ndmc.ac.jp
Background. We previously reported that fractalkine was upregulated in streptozotocin-induced diabetic kidneys. Fractalkine in diabetic kidneys was detected on glomerular capillaries and the mesangium. This upregulation was suppressed by treatment with angiotensin-converting enzyme inhibitor (ACE-I) or aminoiguanidine. We examined what factors induce fractalkine upregulation in normal rat glomeruli.
Methods. Glomeruli were collected from the kidneys of normal Sprague–Dawley rats by a microdissection method. Ten glomeruli were incubated in a solution with glucose, mannitol, angiotensin II, tumour necrosis factor (TNF)-
and advanced glycation end-product (AGE)–bovine serum albumin (BSA) for 1, 2 and 4 h. Fractalkine mRNA expression in glomeruli was examined by reverse transcription–polymerase chain reaction.
Results. Fractalkine mRNA levels in the 30 mM glucose solution significantly increased (121%) compared with those in the control or 30 mM mannitol solution at 1 h. Fractalkine mRNA levels in the 15 mM glucose solution showed no significant differences at 1 or 2 h, but significantly increased (106%) after 4 h incubation. Fractalkine mRNA levels in 10–6–10–8 M angiotensin II solution showed no significant differences. Fractalkine mRNA levels in the 5 or 10 ng/ml TNF- solution significantly increased compared with those in the control in a time- and dose-dependent manner (by 94 to 253%). Fractalkine mRNA levels in the 50–200 µg/ml AGE–BSA solution also increased compared with those in BSA solution in a time- and dose-dependent manner (by 119 to 261%). By pre-incubation with MG132, a nuclear factor-
B inhibitor, fractalkine upregulation by AGE–BSA or 30 mM glucose was completely suppressed.
Conclusions. High glucose levels, AGE formation and cytokine activation in diabetes may induce fractalkine upregulation in the kidneys and lead to progression of diabetic nephropathy.
Keywords: angiotensin II; diabetic nephropathy; glucose; nuclear factor-B; tumour necrosis factor-