Extraction and Quantification of Skin Immune Cells and Skin Lipids.

We have recently shown that the immune system, specifically T cells stimulated by the skin-derived cytokine thymic stromal lymphopoietin, can promote total body adipose loss. This effect is caused by the regulation of lipid metabolism in the skin, whereby T cells induce the release of a lipid-rich substance called sebum. The adoptive transfer of thymic stromal lymphopoietin-stimulated T cells can also induce adipose loss and sebum secretion, making this approach applicable to cellular therapies for metabolic and dermatologic diseases. The skin is the body's largest organ system and provides a critical barrier surface that senses and protects the host from the outside environment. Sebocytes within the skin secrete sebum, a lipid-rich substance that coats the skin and protects it against water, pathogens, and sun damage while also regulating the skin immune landscape and microbiome. Methods to quantify and characterize sebum production are needed to better investigate the role of sebum in skin immunobiology. Here, we describe a protocol that we developed to extract lipids from mouse fur followed by thin layer chromatography analysis of the various lipid classes. We also describe a protocol to maximally extract immune cells from the skin for flow cytometric analysis, which has previously been limited by low cell numbers. These methods will be useful to study skin immunobiology including, but not limited to, its impact on sebum secretion.