P21 | EARLY BIOLOGICAL EFFECTS ON CELL PROLIFERATION AND DIFFERENTIATION INDUCED BY EXTRACELLULAR MICROVESICLES (EVS) DERIVED FROM HUMAN KERATINOCYTES IN PSORIATIC MICROENVIRONMENT

D. Daluiso¹, B. Barco¹, C. Porro², E. Donetti³, F. Riva¹ | ¹Department of Publich Health, Experimental and Forensic Medicine, Histology and Embryology Unit, University of Pavia, Pavia, Italy; ²Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy; ³Department of Biomedical Sciences for Health, University of Milan, Milan, Italy

Extracellular vesicles (EVs), a small bound-membrane particles involved in cell communication, influence skin processes like wound healing and proliferation, even in psoriasis. Spontaneously immortalized keratinocytes (HaCaT cell line) were differentiated for 4 days with CaCl2 1.8 mM and exposed for 24 h and 48 h to a proinflammatory psoriatic microenvironment, a cytokine combination (MIX) of interleukin (IL)-17A (10 ng/mL), IL-22 (20 ng/ mL), IL-23 (10 ng/mL) and Tumor Necrosis Factor α (20 ng/mL). Untreated HaCaT cells differentiated for 6 days as controls (CTR). At each time, the culture medium was collected from CTR and MIX samples, to isolate EVs by standard centrifugation steps. After determination of total EV-associated proteins, differentiated HaCaT cells were incubated for 24 h and 48 h with medium containing 10 g/mL of EVs. Proliferation and differentiation, in terms of tight junctions proteins (CLDN-1, ZO-1) and keratins (CK10, CK14) were evaluated by immunofluorescence and Western blot. MIX-EVstreated vs CTR cells showed an increased proliferation and higher expression of CK14 and CLDN-1. Results suggest a role in crosstalk between epithelial cells, cytokines and EVs causing the modification of cell differentiation, so future studies will apply to clarify their early biological effects on psoriatic lesion formation, playing a promising diagnostic and therapeutic role.