Advanced glycation end-product induces fractalkine gene upregulation in normal rat glomeruli.
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)-alpha 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-alpha 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 microg/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-kappaB 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.
Kikuchi
Yuichi
Y
Second Department of Internal Medicine, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513 Japan. grd1615@ndmc.ac.jp
Imakiire
Toshihiko
T
Hyodo
Toshitake
T
Kushiyama
Taketoshi
T
Higashi
Keishi
K
Hyodo
Naomi
N
Suzuki
Shigenobu
S
Miura
Soichiro
S
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D054428:Chemokine CX3CL1; D020523:Chemokines, CX3C / Q000235:genetics* / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D017127:Glycation End Products, Advanced / Q000494:pharmacology*; D066298:In Vitro Techniques; D007678:Kidney Glomerulus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007976:Leupeptins / Q000494:pharmacology; D008297:Male; D008353:Mannitol / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012710:Serum Albumin, Bovine / Q000494:pharmacology*; D013549:Sweetening Agents / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D054428:Chemokine CX3CL1; D020523:Chemokines, CX3C; C515540:Cx3cl1 protein, rat; D015853:Cysteine Proteinase Inhibitors; D017127:Glycation End Products, Advanced; D007976:Leupeptins; D008565:Membrane Proteins; D012333:RNA, Messenger; D013549:Sweetening Agents; D014409:Tumor Necrosis Factor-alpha; D014662:Vasoconstrictor Agents; C081628:advanced glycation end products-bovine serum albumin; D000804:Angiotensin II; D012710:Serum Albumin, Bovine; D008353:Mannitol; D005947:Glucose; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde