Konur, A. and Schulz, U. and Eissner, G. and Andreesen, Reinhard and Holler, E. (2005) Interferon (IFN)-gamma is a main mediator of keratinocyte (HaCaT) apoptosis and contributes to autocrine IFN-gamma and tumour necrosis factor-alpha production. The British journal of dermatology 152 (6), pp. 1134-42.
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BACKGROUND: Apoptosis of keratinocytes or intestinal epithelial cells is an important pathophysiological mechanism of organ damage during acute graft-versus-host disease. OBJECTIVES: To analyse in detail the mediators and their mutual interaction leading to keratinocyte apoptosis. METHODS: Experiments were performed using a keratinocyte cell line (HaCaT) and human skin explant cultures. RESULTS: Supernatants (SN) of major histocompatibility complex nonmatched mixed lymphocyte cultures (MLCs) induced apoptosis in HaCaT cells and also in keratinocytes from skin biopsies. Although both interferon (IFN)-gamma and Fas ligand (FasL) were detected in MLC-SN by enzyme-linked immunosorbent assay, the apoptosis-inducing capacity could be fully abrogated by neutralization of IFN-gamma, but not by neutralization of FasL. Recombinant (r) IFN-gamma induced HaCaT keratinocyte apoptosis in a dose- and time-dependent manner. Induction of HaCaT apoptosis by rFasL alone was induced only at higher doses than present in MLC-SN, but apoptosis was dramatically enhanced in the presence of rIFN-gamma. Further synergistic effects with IFN-gamma in the induction of apoptosis were also observed with agonistic antitumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptor 2 antibody, soluble TRAIL and TNF-alpha. However, in contrast to FasL and TRAIL, TNF-alpha alone did not induce HaCaT apoptosis. Interleukin-1beta and lipopolysaccharide did not enhance the apoptosis-inducing effect of IFN-gamma. Beside its apoptosis-inducing capacity in HaCaT cells, rIFN-gamma also induced autocrine IFN-gamma production, and combined treatment with IFN-gamma and TNF-alpha induced autocrine TNF-alpha production. Neutralization of autocrine IFN-gamma protected HaCaT cells from apoptosis. CONCLUSIONS: Taken together, our data suggest a central role for IFN-gamma in HaCaT keratinocyte apoptosis but also show the importance of co-acting mediators such as TNF-alpha, TRAIL and FasL, which potentiate the effect of paracrine and autocrine IFN-gamma and TNF-alpha release.
|Institutions:||Medicine > Abteilung für Hämatologie und Internistische Onkologie|
|Subjects:||600 Technology > 610 Medical sciences Medicine|
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Deposited On:||20 Apr 2010 05:19|
|Last Modified:||20 Apr 2010 05:19|