Interleukin-1 induces tubular epithelial-myofibroblast transdifferentiation through a transforming growth factor-beta1-dependent mechanism in vitro.
Interleukin-1 (IL-1) has been shown to exert profibrotic activity in a number of disease models, including crescentic glomerulonephritis and pulmonary fibrosis, but the mechanisms by which this operates are poorly understood. Recent studies have identified a novel mechanism promoting renal fibrosis: tubular epithelial-myofibroblast transdifferentiation (TEMT). The present study examined whether IL-1 can stimulate TEMT in vitro. Cells of the normal rat kidney tubular epithelial cell line (NRK52E) were grown to confluence on collagen-coated plates and cultured for 5 days in the presence 1 to 20 ng/mL of IL-1alpha. Doses of 10 to 20 ng/mL of IL-1 caused transdifferentiation of NRK52E cells into myofibroblast-like cells. Scanning electron microscopy identified IL-1-induced morphological changes as a loss of apical-basal polarity and microvilli, cell hypertrophy, and the development of an elongated and invasive appearance. Phenotypically, IL-1-induced TEMT was characterized by de novo messenger RNA and protein expression of the mesenchymal marker alpha-smooth muscle actin, shown by Northern blotting, immunohistochemistry, and Western blotting. This was accompanied by loss of the epithelial marker E-cadherin. The addition of an excess of IL-1-receptor antagonist completely inhibited IL-1-induced TEMT. IL-1 was shown to stimulate the secretion of active transforming growth factor-beta1 (TGF-beta1) by NRK52E cells. Furthermore, the addition of a neutralizing anti-TGF-beta1 antibody inhibited IL-1-induced TEMT. In conclusion, IL-1 is a profibrogenic cytokine capable of inducing TEMT through a TGF-beta1-dependent mechanism. This may represent a novel mechanism by which IL-1 induces renal fibrosis in vivo.
Fan
J M
JM
Department of Nephrology, Western China University Hospital, Chengdu, China.
Huang
X R
XR
Ng
Y Y
YY
Nikolic-Paterson
D J
DJ
Mu
W
W
Atkins
R C
RC
Lan
H Y
HY
D000199:Actins / Q000096:biosynthesis / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D015820:Cadherins / Q000096:biosynthesis / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D005355:Fibrosis / Q000209:etiology / Q000503:physiopathology*; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000494:pharmacology / Q000502:physiology*; D007674:Kidney Diseases / Q000209:etiology / Q000503:physiopathology*; D007676:Kidney Failure, Chronic / Q000209:etiology / Q000503:physiopathology; D007684:Kidney Tubules / Q000166:cytology / Q000502:physiology*; D008854:Microscopy, Electron; D009130:Muscle, Smooth / Q000737:chemistry; D051381:Rats
D000199:Actins; D015820:Cadherins; D007375:Interleukin-1