Interleukin-6 promotes human epidermal keratinocyte proliferation and keratin cytoskeleton reorganization in culture
- 449 Downloads
We have studied the effects of interleukin-6 (IL-6) on human epidermal keratinocytes by using serum-free culture conditions that allow the serial transfer, differentiation, and formation of well-organized multilayered epithelia. IL-6 at 2.5 ng/ml or higher concentrations promoted keratinocyte proliferation, with an ED50 of about 15 ng/ml and a maximum effect at 50 ng/ml. IL-6 was 10-fold less potent than epidermal growth factor (EGF) or transforming growth factor-α (TGF-α) and supported keratinocyte growth for up to eight cumulative cell generations. IL-6-treated keratinocytes formed highly stratified colonies with a narrower proliferative/migratory rim than those keratinocytes stimulated with EGF or TGF-α; confluent epithelial sheets treated with IL-6 also underwent an increase in the number of cell layers. We also examined the effect of IL-6 on the keratin cytoskeleton. Immunostaining with anti-K16 monoclonal antibodies showed that the keratin network was aggregated and reorganized around cell nucleus and that this was not attributable to changes in keratin levels. This is the first report concerning the induction of the reorganization of keratin intermediate filaments by IL-6 in human epidermal keratinocytes.
KeywordsInterleukin-6 EGF/TGF-α Cytokeratin Cell proliferation Cultured epidermal keratinocytes (strain HE-123) Human
We are grateful to Meytha Marsch-Moreno (IBQ) for preparing the human epidermal keratinocyte banks and the mytomycin-C-treated feeder cells, to Mrs. Erika Sánchez Guzmán and Ms. Ana Ruth Cristóbal-Ramos for technical assistance, to Ms. Maria Elena Rojano for secretarial assistance, and to Mr. Alberto Rodriguez and Mrs. Columba Guadarrama for their technical assistance in the preparation of all materials.
- Castell-Rodellas A, Castell JV, Ramirez-Bosca A, Nicolas JF, Valcuende-Cavero F, Thivolet J (1992) Interleukin-6 in normal skin and psoriasis. Acta Derm Venereol 72:165–168Google Scholar
- Grossman RM, Krueger J, Yourish D, Granelli-Piperno A, Murphy DP, May LT, Kupper TS, Sehgal PB, Gottlieb AB (1989) Interleukin 6 is expressed in high levels in psoriatic skin and stimulates proliferation of cultured human keratinocytes. Proc Natl Acad Sci USA 86:6367–6371PubMedCrossRefGoogle Scholar
- Sato M, Sawamura D, Ina S, Yaguchi T, Hanada K, Hashimoto I (1999) In vivo introduction of the interleukin 6 gene into human keratinocytes: induction of epidermal proliferation by the fully spliced form of interleukin 6, but not by the alternatively spliced form. Arch Dermatol Res 291:400–404PubMedCrossRefGoogle Scholar
- Sawamura D, Meng X, Ina S, Sato M, Tamai K, Hanada K, Hashimoto I (1998) Induction of keratinocyte proliferation and lymphocytic infiltration by in vivo introduction of the IL-6 gene into keratinocytes and possibility of keratinocyte gene therapy for inflammatory skin diseases using IL-6 mutant genes. J Immunol 161:5633–5639PubMedGoogle Scholar
- Waelti ER, Sven P, Inaebnit SP, Hans P, Rast HP, Hunziker T, Limat A, Lasse R, Braathen LR, Wiesmann U (1992) Co-culture of human keratinocytes on post-mitotic human dermal fibroblast feeder cells: production of large amounts of interleukin 6. J Invest Dermatol 98:805–808PubMedCrossRefGoogle Scholar
- Yano T, Tokui T, Nishi Y, Nishizawa K, Shibata M, Kikuchi K, Tsuiki S, Yamauchi T, Inagaki M (1991) Phosphorylation of keratin intermediate filaments by protein kinase C, by calmodulin-dependent protein kinase and by cAMP-dependent protein kinase. Eur J Biochem 197:281–290PubMedCrossRefGoogle Scholar