High glucose stimulates hyaluronan production by renal interstitial fibroblasts through the protein kinase C and transforming growth factor-beta cascade.
Deposition of hyaluronan has been implicated in the pathogenesis of diabetic glomerulosclerosis. We hypothesized the involvement of hyaluronan in diabetic tubulointerstitial fibrosis. We investigated high-glucose effect on hyaluronan production by rat renal interstitial fibroblasts (normal rat kidney [NRK] cells) and examined the role of hyaluronan in NRK cell proliferation. The involvement of protein kinase C (PKC) and transforming growth factor-beta (TGF-beta) in this response was also examined. After 24 hours of incubation in medium containing 25.6 mmol/L glucose, production of hyaluronan by NRK cells was significantly increased compared with medium containing 5.6 mmol/L glucose (P <.01). L-glucose and mannitol had no effect on hyaluronan production. High glucose enhanced basal in situ PKC activity (P <.01), and both an activator of PKC (phorbol 12-myristate 13-acetate; [PMA]) and TGF-beta 1 were able to increase hyaluronan production by NRK cells (P <.01). The effect of high glucose on hyaluronan production was diminished by coincubating cells with PKC inhibitors (staurosporine [Stp] or calphostin C [CpC]) or with an anti-TGF-beta neutralizing antibody. Stimulation of hyaluronan production by PMA was also normalized by anti TGFbeta neutralizing antibody, but the effect of TGF-beta1 was not affected by inhibition of PKC. Finally, incubating quiescent NRK cells with 50 or 100 ng/mL hyaluronan for 24 hours significantly increased NRK cell number (P <.01). In conclusion, high glucose stimulates hyaluronan production through the PKC/TGF-beta cascade. Increased hyaluronan promotes NRK cell proliferation. These results suggest that hyaluronan may play a role in the pathogenesis of interstitial fibrosis in diabetic kidney disease.
Takeda
M
M
Third Department of Medicine, Diabetes Center, Tokyo Women's Medical University School of Medicine, Tokyo, Japan.
Babazono
T
T
Nitta
K
K
Iwamoto
Y
Y
D000818:Animals; D002455:Cell Division; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005355:Fibrosis / Q000209:etiology; D005947:Glucose / Q000494:pharmacology*; D006820:Hyaluronic Acid / Q000096:biosynthesis* / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008353:Mannitol / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*
D004791:Enzyme Inhibitors; D016212:Transforming Growth Factor beta; D008353:Mannitol; D006820:Hyaluronic Acid; D011493:Protein Kinase C; D005947:Glucose; D013755:Tetradecanoylphorbol Acetate