TNF receptor I on human keratinocytes is a binding partner for staphylococcal protein A resulting in the activation of NF kappa B, AP-1, and downstream gene transcription.
Primary human keratinocytes and immortalized HaCaT cells were analysed for their capacity to bind purified staphylococcal protein A (SpA). Co-incubation with FITC-labelled SpA led to a dose-depending attachment. Pull-down experiments with cellular extracts revealed the TNFα receptor I (TNF RI) as binding partner on keratinocytes. Thus, we next looked for expression of this receptor in human epidermis and cultured keratinocytes. TNF RI is strongly expressed on all keratinocytes analysed, both at the mRNA and protein level and activation by SpA at optimal doses of 50-100 μg/ml resulted in the phosphorylation of the TNF RI downstream kinases MEK1/2, JNK1/2, and p38 subsequently leading to translocation of the p65 NF kappa B subunit and AP-1 into the nucleus. This translocation was then followed by increased expression of IL-8 and COX-2, two known NF kappa B-induced pro-inflammatory genes. To further test the relevance of our findings, we analysed in vitro production of over 100 strains isolated from atopic eczema showing that more than 85% of the tested strains produced extracellular SpA in substantial amounts. Thus, besides superantigens, haemolysins, and other cell wall components, Staphylococcus aureus exerts pro-inflammatory stimuli on human keratinocytes through the production of SpA signalling through TNF RI.
Classen
Anna
A
Department of Dermatology and Allergy, Biederstein, Technische Universität München, München, Germany.
Kalali
Behnam N
BN
Schnopp
Christina
C
Andres
Christian
C
Aguilar-Pimentel
Juan A
JA
Ring
Johannes
J
Ollert
Markus
M
Mempel
Martin
M
D021581:Active Transport, Cell Nucleus; D001483:Base Sequence; D002460:Cell Line; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000235:genetics; D003876:Dermatitis, Atopic / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D006801:Humans; D066298:In Vitro Techniques; D018836:Inflammation Mediators / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics; D015603:Keratinocytes / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000235:genetics / Q000378:metabolism*; D013205:Staphylococcal Protein A / Q000096:biosynthesis / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000276:immunology / Q000302:isolation & purification / Q000472:pathogenicity; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000378:metabolism*; D014158:Transcription, Genetic
C508606:CXCL8 protein, human; D018836:Inflammation Mediators; D016209:Interleukin-8; C498143:RELA protein, human; D012333:RNA, Messenger; D047888:Receptors, Tumor Necrosis Factor, Type I; D013205:Staphylococcal Protein A; D018808:Transcription Factor AP-1; D051996:Transcription Factor RelA; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human