CD40 is functionally expressed on human keratinocytes.
The CD40/gp39 pathway is known to be an important feature of B/T cell collaboration leading to T cell-dependent activation, proliferation or differentiation of B cells. Additionally, CD40 is involved in the regulation of B cell survival and apoptosis. Recently, CD40 has been shown to be expressed functionally on non-hematopoietic cells, i.e. endothelial cells. Here, we demonstrate that human keratinocytes (KC) cultured in vitro express CD40 constitutively. The surface expression of CD40 is markedly up-regulated following stimulation with interferon (IFN)-gamma, but not with tumor necrosis factor-alpha or interleukin (IL)-1 beta. This process is regulated at the CD40 mRNA level as demonstrated by Northern blot analysis. Furthermore, ligation of CD40 via soluble gp39, the CD40 ligand, enhances intercellular adhesion molecule (ICAM)-1 and Bcl-x up-regulation on IFN-gamma-stimulated KC, but not lymphocyte function-associated antigen (LFA)-3, B7-2, HLA-DR, or Fas expression. The release of IL-8 is also induced following CD40 ligation on KC. In psoriasis, a T cell-mediated inflammatory skin disease, KC have a markedly enhanced expression of CD40. This expression co-localizes with the expression of ICAM-1, Bcl-x, and an influx of CD3+ T cells. These findings suggest a functional role of CD40 on KC in inflammatory skin disorders such as psoriasis and could make a therapeutic intervention by disrupting the CD40/gp39 pathway an approach to consider in these inflammatory skin diseases.
Department of Dermatology, Albert-Ludwigs-Universität, Freiburg, Germany.
R W
RW
Denfeld
D
D
Hollenbaugh
A
A
Fehrenbach
J M
JM
Weiss
A
A
von Leoprechting
B
B
Mai
U
U
Voith
E
E
Schöpf
A
A
Aruffo
J C
JC
Simon
D000328:Adult; D017252:CD3 Complex / Q000378:metabolism; D019013:CD40 Antigens / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D015870:Gene Expression; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D015603:Keratinocytes / Q000276:immunology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D011565:Psoriasis / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D015398:Signal Transduction; D012871:Skin Diseases / Q000276:immunology; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; D017252:CD3 Complex; D019013:CD40 Antigens; D016209:Interleukin-8; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051020:bcl-X Protein; D018799:Intercellular Adhesion Molecule-1