Differential modulation of IL-8 and TNF-alpha expression in human keratinocytes by buflomedil chlorhydrate and pentoxifylline.

Pentoxifylline (PTX) is a methylxanthine derivative used in a wide range of dermatoses. As well as its hemorrheologic activity, PTX has anti-inflammatory properties. Buflomedil chlorhydrate (BC) is another hemorrheological drug with peripheral vasodilatory action, whose clinical uses are similar to those of PTX. Both drugs increase intracellular levels of cAMP, either secondary to phosphodiesterase inhibition (PTX) or adenyl-cyclase stimulation (BC). Long-term cultures of normal human keratinocytes were prepared in a free-serum medium, and stimulated with 1 mg/ml of phorbol 12-myristate 13-acetate (TPA) and PTX or BC (100-1000 micrograms/ml). Levels of TNF-alpha, IL-1 alpha, IL-1 beta, IL-8 and TGF-beta 1 using ELISA and Northern blot or RT-PCR techniques were measured. TPA-induced TNF-alpha and IL-8 release from keratinocytes. TPA did not induce IL-1 alpha or IL-1 beta release of keratinocytes. TPA increased RNA expression of the TNF-alpha, IL-1 alpha, IL-1 beta, IL-8 and TGF-beta 1. BC diminished TPA-induced TNF-alpha and IL-8 release from keratinocytes; in the case of IL-8 it is possible that this inhibition occur to transcriptional level. Moreover PTX was unable to inhibit TNF-alpha and IL-8 synthesis and expression. PTX and BC reduced TPA-induced IL-1 alpha and beta expression. It is possible that BC action is specifically exerted on keratinocytes, because we did not find similar results with TNF-alpha and IL-8 synthesis in mononuclear peripheral blood cells.