ROME—Italian researchers compared effects of plant polyphenols (PPs) on the constitutive, UVA-, LPS- or TNF-alpha-induced inflammatory responses in cultured normal human epidermal keratinocytes (NHEK) and immortalized HaCaT cells in a recent study (J Dermatolog Sci. 2011;63(2):104-12). Environmental and endogenous stresses to skin are considered causative reasons for skin cancers, premature ageing and chronic inflammation. Screening of substances with preventive and/or curative properties is currently based on mechanistic studies of their effects toward stress-induced responses in skin cell cultures.
Representatives of three classes of PPs—flavonoids, stilbenoids and phenylpropanoids—were studied. PPs or their combination with UVA or LPS induced strong up-regulation of stress responses in HaCaT, but not in NHEK. In addition, compared to NHEK, HaCaT responded to TNF-alpha with higher synthesis of MCP-1, IP-10 and IL-8, concomitant with stronger NFkappaB activation. PPs down-regulated the chemokine release from both cell types, although with distinct effects on NFkappaB, Akt1, ERK and EGFR activation.