Avobenzone is a commonly used organic ultraviolet (UV) filter that protects the skin from UV radiation. In addition to its photoprotective action, studies suggest that it may have broader biological effects, including modulation of cellular signalling pathways, induction of oxidative stress and promotion of inflammatory responses. As avobenzone is intended for dermal application, it first comes into contact with skin cells following application. Fibroblasts, the main stromal cells of the dermis, play a significant role in maintaining skin homeostasis, wound healing and regulation of the inflammatory response. As studies have shown that avobenzone and its metabolites may also be present in the bloodstream, we sought to investigate the effects of avobenzone on fibroblasts and peripheral blood mononuclear cells (PBMCs) and to assess its potential impact on their intercellular communication.
We used PBMCs isolated from healthy donors and the BJ-5ta fibroblast cell line as experimental models. In the first part of the study, we assessed the potential effects of avobenzone on cell viability using the metabolic activity assay. The results showed that, at concentrations ranging from 0.1 to 100 µM, avobenzone did not cause a concentration- or time-dependent reduction in the metabolic activity of BJ-5ta fibroblasts or PBMCs. We then analysed the supernatants of PBMCs and fibroblasts following exposure to avobenzone in the presence or absence of lipopolysaccharide (LPS). Using a multiplex method, we simultaneously determined the concentrations of six cytokines: IL-8, IL-6, IL-10, IL-12p70, IL-1β and TNF-α. As expected, stimulation with LPS induced a characteristic inflammatory response under all experimental conditions. We found that the effects of avobenzone depend on its concentration, cell type, cytokine and the presence of LPS. The effects of avobenzone were observed primarily at the higher concentration of 100 µM. While avobenzone did not induce significant changes in fibroblasts, which basally secrete mainly IL-6 and IL-8, we observed a trend towards increased secretion of IL-6, IL-8 and IL-1β in PBMCs.
We then used a scratch assay to assess the effect of avobenzone on fibroblast migration. The results showed that the presence of avobenzone significantly slowed wound closure. This effect was partially reversed following the addition of PBMC supernatants to the fibroblasts.
Based on the results obtained, we conclude that avobenzone does not exhibit cytotoxic effects under the experimental conditions used but may modulate the inflammatory response and paracrine communication between peripheral blood mononuclear cells and fibroblasts. Its effects depend on concentration, cytokine type and the cellular environment; therefore, avobenzone cannot be unequivocally classified as either anti-inflammatory or pro-inflammatory. Due to the limited number of biological replicates, these findings should be considered primarily observational and require confirmation in further studies.
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