125 Extended (epi-)lidomic analysis of senescent dermal fibroblasts

Abstract

Skin as a barrier separates and protects organism from its surrounding. A wide range of stressors from the environment (UV radiation, pollution) challenges skin homeostasis and prolonged imbalance accelerates skin aging. Aged skin is characterized by presence of senescent cells, which have changed appearance and phenotype, accumulate damaged biomolecules (DNA, proteome, lipidome) and simultaneously produce a mixture of danger signaling molecules – so called senescent associated secretory phenotype (SASP). This concoction of biomolecules – including lipids - influences cell microenvironment and the immune system towards a low grade chronic inflammatory phenotype. We previously described increased levels of lysophosphatidylcholines, in both replicative senescent fibroblast and in in vitro stress-induced premature senescent (SIPS) fibroblasts. Using UHPLC triple quadrupole MS/MS method we identified additional lysophospholipid species regulated upon hydrogen peroxide or doxorubicin SIPS protocols. Upon both treatments lipid categories of lysophosphatidylcholines and lysophosphatidylethanolamines were significantly elevated in comparison to corresponding controls, however the effect was more striking in doxorubicin-induced senescent fibroblasts. Moreover, a broader spectrum of analyzed lipid classes revealed that phospholipids are not only lipids which are senescence regulated. There were apparent changes between above mentioned SIPS protocols, suggesting a different involvement of enzymatically or reactive oxygen species mediated lipids metabolism. Recognition of structure and function of (epi-)lipidome could contribute to better understanding of mechanism of SAPS driven continuous activation of immune system and therefore to help find approaches how to mitigate/ prevent development of associated skin pathologies.