The Benefits of Olive Oil for Skin Health: Study on the Effect of Hydroxytyrosol, Tyrosol, and Oleocanthal on Human Fibroblasts

Abstract

Fibroblasts contribute to maintaining tissue integrity and homeostasis and are a key cell population in wound healing. This cell population can be stimulated by some bioactive compounds such as extra virgin olive oil (EVOO) polyphenols. The aim of this study was to determine the effects of hydroxytyrosol (htyr), tyrosol (tyr), and oleocanthal (ole) phenolic compounds present in EVOO on the proliferation, migration, cell cycle, and antigenic profile of cultured human fibroblasts. CCD-1064Sk human fibroblast cells were treated for 24 h with each polyphenol at doses ranging 10^-5 to 10^-9 M. Cell proliferation was evaluated using the MTT spectrophotometric technique, migration capacity by culture insert assay, and cell cycle and antigenic profile with flow cytometry. Cell proliferation was significantly increased by treatment with all compounds. The highest increases followed treatments with htyr or tyr at doses of 10^-5 or 10^-6 M and with ole at 10^-6 and 10^-7 M, and these compounds and doses were used for assays of antigenic profile, cell cycle, and migration. During the first few hours after treatment, increased fibronectin and α-actin expressions and greater cell migration were observed, with no cell cycle changes. In conclusion, these in vitro results suggest that phenolic compounds in EVOO might contribute to wound healing through action on fibroblasts related to tissue regeneration.

Keywords: extra virgin olive oil; fibroblasts; phenolic compounds; tissue regeneration; wound healing.

Figure 1

Effects of htyr (a), tyr (b), and ole (c) on the proliferative capacity of fibroblasts after 24 h of treatment and EC50 value for each treatment. Data are expressed in percentages with respect to results for control cells. * p < 0.05.

Figure 2

(A) Effect of htyr (a), tyr (b), and ole (c) on the migratory capacity of fibroblasts after 4, 8, 12, and 24 h of treatment. Closure of the space generated by the insert is expressed as a percentage. * p < 0.05. (B). Fibroblast migration assay: images of each treatment group after 24 h of incubation with the different polyphenols studied.

Figure 3

Fluorescence profile of cultured human epithelial fibroblast cell cycle at 24 h after treatment showing the percentage distribution of cells among G0/G1, S, and G2/M phases, as determined by flow cytometry.

Figure 4

(A) Effect of htyr, tyr, and ole on the antigenic profile of cultured human fibroblasts. Data are presented in percentages relative to controls. * p < 0.05. (a) Effect of htyr, tyr, and ole on the expression of fibronectin in cultured human fibroblasts. (b) Effect of htyr, tyr, and ole on the expression of α-actin in cultured human fibroblasts. (B) Immunostaining with fibronectin-fluorescein and α-actin–phycoerythrin of human fibroblast cells after 24 h of treatment.

Figure 4

(A) Effect of htyr, tyr, and ole on the antigenic profile of cultured human fibroblasts. Data are presented in percentages relative to controls. * p < 0.05. (a) Effect of htyr, tyr, and ole on the expression of fibronectin in cultured human fibroblasts. (b) Effect of htyr, tyr, and ole on the expression of α-actin in cultured human fibroblasts. (B) Immunostaining with fibronectin-fluorescein and α-actin–phycoerythrin of human fibroblast cells after 24 h of treatment.