Emerging nonmetabolic functions of skin fat

Abstract

Although the major white adipose depots evolved primarily to store energy, secrete hormones and thermo-insulate the body, multiple secondary depots developed additional specialized and unconventional functions. Unlike any other fat tissue, dermal white adipose tissue (dWAT) evolved a large repertoire of novel features that are central to skin physiology, which we discuss in this Review. dWAT exists in close proximity to hair follicles, the principal appendages of the skin that periodically grow new hairs. Responding to multiple hair-derived signals, dWAT becomes closely connected to cycling hair follicles and periodically cycles itself. At the onset of new hair growth, hair follicles secrete activators of adipogenesis, while at the end of hair growth, a reduction in the secretion of activators or potentially, an increase in the secretion of inhibitors of adipogenesis, results in fat lipolysis. Hair-driven cycles of dWAT remodelling are uncoupled from size changes in other adipose depots that are controlled instead by systemic metabolic demands. Rich in growth factors, dWAT reciprocally signals to hair follicles, altering the activation state of their stem cells and modulating the pace of hair regrowth. dWAT cells also facilitate skin repair following injury and infection. In response to wounding, adipose progenitors secrete repair-inducing activators, while bacteria-sensing adipocytes produce antimicrobial peptides, thus aiding innate immune responses in the skin.

Comparative regenerative biology of spiny (Acomys cahirinus) and laboratory (Mus musculus) mouse skin

“…We will need to characterize intradermal adipose tissue in the spiny mouse to see if they also express cyclic BMP4 expression. [12] It is intriguing that, compared to Mus dermal white adipose tissue (dWAT) in telogen, which reduces in size by ~50%, [15] there is no obvious thinning of the thick adipose layer in Acomys skin. In this review article, Guerrero-Juarez and Plikus [15] report evidence that dermal adipocytes are heterogeneous in development, in sensitivity to catagen and spatial arrangement.…”

Caveolin‐1 as a possible target in the treatment for acne

“…This special fat depot located in the superficial hypodermis and around the distal parts of PSUs demonstrates significant volume oscillations during HF cycle. [12,26,27] As we discovered very recently, this effect is connected with repeated de-and re-differentiation processes, which affect 90%-95% of the adipose cells from dWAT ( Figure 1). [13] The dedifferentiation of mature dermal adipocytes in adipocyte-derived preadipocytes (ADPs) is connected to a dramatic reduction in the cell volumes.…”

Do human dermal adipocytes switch from lipogenesis in anagen to lipophagy and lipolysis during catagen in the human hair cycle?

“…Moreover, if HF‐DWAT communication is clinically as important in the regulation of human hair growth as in murine hair growth, therapeutically targeting lipophagy and/or lipolysis in human DWAT by injected or topically applied agents may be clinically relevant not only for controlling DWAT volume and functional activities but also for hair growth modulation. We hypothesize that lipophagy within human DAs is a crucial mechanism used to achieve faster and larger turnover of resident triglyceride stores within LDs, as an intrinsic mechanism for maintaining a healthy metabolic status and healthy skin homoeostasis.…”