751 A comparative analysis of skin aging-associated secreted proteins (SAASP) produced by dermal fibroblasts from intrinsically versus extrinsically aged human skin

Abstract

Skin aging results to a large extent from the accumulation of senescent dermal fibroblasts. In a previous systematic molecular analysis of normal human dermal fibroblasts (NHDF) isolated from intrinsically aged human skin of donors aged 18-25 versus 35-49 versus ≥ 60 years we observed that intrinsic aging of NHDF is associated with the development of a protein secretion pattern referred to as SAASP. In the present study we asked if and how this secretory phenotype might differ between NHDF isolated from intrinsically versus extrinsically aged human skin. We again obtained NHDF from young versus middle aged versus old donors. In this study, however, for each donor NHDF were isolated not only from intrinsically aged, i.e. buttock skin, but also from extrinsically aged, i.e. neck skin. Quantitative, label-free mass spectrometry analysis of the proteome of these cells revealed an age-dependent progressive loss of protein diversity, which was significantly more pronounced in extrinsically aged NHDF. This was not reflected by changes in the secretome of the same cells. Accordingly, quantitative analysis of the entire secretome present in conditioned cell culture supernatants derived from these cells showed that the diversity of proteins in the secretome was not reduced if compared between the three age groups for intrinsic and extrinsic aging, respectively. In fact, secretome diversity even increased for intrinsically versus extrinsically aged NHDF of old donors. Subsequent network and enrichment analysis revealed that the secretomes of extrinsically versus intrinsically aged NHDF differ from each other also at a functional level. As an example, in old donors, secreted proteins relevant for extracellular matrix organization were significantly less abundant in extrinsically aged NHDF. These results demonstrate that the SAASP produced by NHDF profoundly differs between intrinsically versus extrinsically aged human skin, indicating that the relationship between intrinsic and extrinsic skin aging is highly complex in nature.