TNF-alpha and IL-1beta-mediated regulation of MMP-9 and TIMP-1 in renal proximal tubular cells.
BACKGROUND
Tubulointerstitial fibrosis is a morphologic hallmark of chronic kidney disease and is a key factor in the prediction of progression to end-stage renal failure. Disruption of tubular basement membrane and interstitial extracellular matrix (ECM) via cytokine-induced alterations in matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) may be an important mechanism in this process. The presence of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) and their effects on proximal tubular cells may be critical in this process.


METHODS
Human proximal tubular cells were cultured in hormonally defined medium. Cells at 80% confluency were exposed to TNF-alpha (0.1 to 100 ng/mL) or IL-1beta (0.1 to 100 ng/mL) or a combination of both for 48 hours. Activity and expression of MMP-9 was examined by gelatin zymography and Western blot analysis. TIMP-1 expression was analyzed by Western blotting. Signaling through cytokine receptors, protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) pathways was investigated.


RESULTS
TNF-alpha but not IL-1beta resulted in a dose-dependent increase in the latent form of MMP-9. TIMP-1 was decreased by treatment with either TNF-alpha or IL-1beta. Cotreatment with IL-1beta abolished the induction of MMP-9 but augmented the inhibition of TIMP-1 in the presence of TNF-alpha. Inhibition of PKC provided evidence of the importance of this pathway in mediating the cytokine-induced suppression of TIMP-1 in human kidney (HK-2) cells. Activation of the extracellular signal-regulated protein kinase (ERK1/2) MAPK mediated the up-regulation of MMP-9 by TNF-alpha whereas p38 was found to be involved in the IL-1beta-mediated inhibition of TNF-alpha-stimulated MMP-9.


CONCLUSIONS
The differential effects of TNF-alpha and IL-1beta on proximal tubular MMP-9 and TIMP-1 expression are mediated through the TNF-RI, the IL-1-RI and the different signaling pathways of PKC, ERK1/2, and p38 MAPK. These findings may provide new insights into the role of proinflammatory cytokines TNF-alpha and IL-1beta in the development and possible therapeutic intervention in tubulointerstitial fibrosis.
Department of Pharmacology, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
Larine E
LE
Nee
Tara
T
McMorrow
Eric
E
Campbell
Craig
C
Slattery
Michael P
MP
Ryan
D002461:Cell Line, Transformed; D004347:Drug Interactions; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000494:pharmacology*; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D012795:Sialoglycoproteins / Q000494:pharmacology; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D047888:Receptors, Tumor Necrosis Factor, Type I; D012795:Sialoglycoproteins; D019715:Tissue Inhibitor of Metalloproteinase-1; D014409:Tumor Necrosis Factor-alpha; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020780:Matrix Metalloproteinase 9