Keratinocytes, a key cellular component both for homeostasis and pathophysiologic processes of the skin, secrete a number of cytokines and are stimulated by several growth factors. Nerve growth factor (NGF) is synthesized in the skin and basal keratinocytes express the low-affinity nerve growth factor receptor (NGF-R). We present evidence that normal human keratinocytes in culture express the low- and the high-affinity NGF-R both at the mRNA level, as determined by reverse-transcription polymerase chain reaction and at the protein level, as shown by cytofluorimetric analysis. NGF significantly stimulates the proliferation of normal human keratinocytes in culture in a dose-dependent manner. This effect can be prevented by the addition of both an anti-NGF neutralizing antibody and a high-affinity NGF-R (trk) specific inhibitor, the natural alkaloid K252a. By contrast, keratinocyte proliferation is not inhibited by an anti - low-affinity NGF-R monoclonal antibody, thus suggesting that NGF effect on human keratinocytes is mediated by the high-affinity NGF-R. Moreover, NGF mRNA is expressed in normal human keratinocytes and NGF is secreted by keratinocytes in increasing amounts during growth, as detected by enzyme-linked immunosorbent assay. These results suggest that NGF could act as a cytokine in human skin and take part in disorders of keratinocyte proliferation.
Expression And Function Of Nerve Growth-Factor And Nerve Growth-Factor Receptor On Cultured Keratinocytes / Pincelli, Carlo; C., Sevignani; Manfredini, Rossella; Grande, Alexis; F., Fantini; L., Bracci Laudiero; L., Aloe; Ferrari, Sergio; Cossarizza, Andrea; Giannetti, Alberto. - In: JOURNAL OF INVESTIGATIVE DERMATOLOGY. - ISSN 0022-202X. - STAMPA. - 103:(1994), pp. 13-18.