Inhibition of nuclear factor-kappaB activation reduces cortical tubulointerstitial injury in proteinuric rats.
BACKGROUND
Protein-induced chemokine expression in proximal tubular cells is mediated by the transcription factor nuclear factor-kappa B (NF-kappaB). We hypothesized that in vivo inhibition of renal NF-kappaB activation would reduce interstitial monocyte infiltration in a rat model of nonimmune proteinuric tubulointerstitial inflammation.


METHODS
Male Wistar rats received a single intravenous injection of doxorubicin hydrochloride [adriamycin (ADR), 7.5 mg/kg] and were studied 7, 14, 21, and 28 days later. In a second study, inhibitors of NF-kappaB [N-acetylcysteine (NAC; 150 mg/kg, b.i.d., i.p.), pyrrolidine dithiocarbamate (PDTC, 50 mg/kg, b. i.d., i.p.)] or vehicle were commenced on day 14 after the onset of proteinuria and were continued until day 30.


RESULTS
Rats injected with ADR had increased proteinuria (UpV, day 28, 474 +/- 57; control, 18 +/- 2 mg/day; P < 0.01) and cortical tubulointerstitial injury [tubule cell atrophy, interstitial volume, and monocyte/macrophage (ED-1) infiltration]. Electrophoretic mobility shift assay of nuclear extracts from whole cortex of ADR rats demonstrated that NF-kappaB activation (p50/65, p50/c-Rel) increased from day 7 (4.7 +/- 0.2 fold-increase above control; P < 0.01) was maximal at day 28 (6.2 +/- 0.7; P < 0.01) and correlated with UpV (r = 0.63; P < 0.05) and interstitial ED-1 infiltration (r = 0.67; P < 0.01). Chronic treatment of ADR rats with PDTC suppressed NF-kappaB activation (by 73%; P < 0.05) without any effect on UpV. NF-kappaB inhibition with PDTC was accompanied by a reduction in tubule cell atrophy (59%; P < 0.01), interstitial volume (49%; P < 0.05) and ED-1 infiltration (48%; P < 0.01), and cortical lipid peroxidation (41%; P < 0.05) compared with vehicle-treated ADR rats. In contrast NAC had no effect on NF-kappaB activation, tubulointerstitial injury, or UpV in ADR rats.


CONCLUSIONS
The activation of NF-kappaB may have an important role in mediating cortical interstitial monocyte infiltration and tubular injury in nonimmune proteinuric tubulointerstitial inflammation.
Department of Renal Medicine, University of Sydney at Westmead Hospital, Australia.
G K
GK
Rangan
Y
Y
Wang
Y C
YC
Tay
D C
DC
Harris
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D004317:Doxorubicin; D007668:Kidney / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D007672:Kidney Cortex / Q000473:pathology*; D007684:Kidney Tubules / Q000473:pathology*; D008054:Lipid Peroxides / Q000378:metabolism; D008264:Macrophages / Q000502:physiology; D008297:Male; D009000:Monocytes / Q000502:physiology; D016328:NF-kappa B / Q000187:drug effects / Q000502:physiology*; D009401:Nephrosis / Q000139:chemically induced / Q000503:physiopathology; D011507:Proteinuria / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology; D011759:Pyrrolidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013859:Thiocarbamates / Q000494:pharmacology; D013997:Time Factors
D008054:Lipid Peroxides; D016328:NF-kappa B; D011759:Pyrrolidines; D013859:Thiocarbamates; C020972:pyrrolidine dithiocarbamic acid; D004317:Doxorubicin; D000111:Acetylcysteine