The effect of topical PPARG inhibitor (GW9662) treatment on the transcriptome of old dermal fibroblasts

During aging, stromal functions are thought to be impaired, yet little is known whether this stems from molecular and cellular changes of fibroblasts, a major component of stroma. Using population- and single-cell whole transcriptomics, and long-term lineage tracing, we studied alterations in murine dermal fibroblasts during physiological aging under different dietary regimes known to affect longevity. We show that the identity of aged fibroblasts becomes undefined, with the distinct fibroblast states present in young skin no longer clearly demarcated. In addition, old fibroblasts not only reduce the expression of genes involved in the formation of the extracellular matrix, but intriguingly, also gain adipogenic traits, paradoxically becoming similar to neonatal pro-adipogenic fibroblasts. These age-related alterations are sensitive to systemic changes in metabolism: long-term caloric restriction prevents them in old fibroblasts in a reversible manner, whereas a high-fat diet potentiates them in young fibroblasts. Finally, inhibition of the master regulator of adipogenesis, PPARgamma, attenuates fibroblast aging in vivo, providing potential anti-aging therapeutic alternatives to caloric restriction. The backskin of four 12-months-old mice was treated topically 3 times per week with 300ul Acetone containing 150nmoles GW9662 or with 300ul Acetone alone (as a control) for 6 months. For sample collection one animal from each group was sacrificed the same day. n=4