Molecular cartography of the human skin surface in 3D

Abstract

The human skin is an organ with a surface area of 1.5-2 m 2 that provides our interface with the environment. The molecular composition of this organ is derived from host cells, microbiota, and external molecules. The chemical makeup of the skin surface is largely undefined. Here we advance the technologies needed to explore the topographical distribution of skin molecules, using 3D mapping of mass spectrometry data and microbial 16S rRNA amplicon sequences. Our 3D maps reveal that the molecular composition of skin has diverse distributions and that the composition is defined not only by skin cells and microbes but also by our daily routines, including the application of hygiene products. The technological development of these maps lays a foundation for studying the spatial relationships of human skin with hygiene, the microbiota, and environment, with potential for developing predictive models of skin phenotypes tailored to individual health.human skin | 3D mapping | mass spectrometry | 16S rRNA T he skin provides the interface between our internal molecular processes and the external environment. The stratum corneum (SC), the outer layer of the epidermis, is the most exposed organ of the human body and is composed of molecules derived from our own skin cells, our microbiota, and the environment (1). In addition, it may be possible that personal hygiene products, the clothing we wear, and the food we eat can affect the chemical composition of the skin (2, 3). The chemical environment of the skin is also critical for the development of microbial communities, yet there are no systematic workflows that can be used to correlate skin chemistry and microbes. Human skin microbiome inventories are changing our views of commensal organisms and their roles in establishing and maintaining the immune system and general epithelial health (4-7), but their role in biotransformation of skin molecules is as yet poorly characterized.Understanding the molecular topography of the surface of the SC will provide insights into the chemical environment in which microbes reside on the skin and how in turn they modify this environment. To understand the relationship between the chemical milieu and the microbial communities, we must develop workflows that map the chemistry and microbiology of the human skin and that determine the associations between them. The composition of the human skin microbiota has been correlated with skin anatomy, dividing into moist, dry, and sebaceous microenvironments, and can be influenced by beauty and hygiene products (2-9). Regions such as the face, chest, and back, areas with a high density of sebaceous glands, promote growth of lipophilic microorganisms such as Propionibacterium and Malassezia. In contrast, less exposed regions, such as the groin, axilla, and toe web, which are higher in temperature and moisture content, are colonized by Staphylococcus and Corynebacterium (7, 10, 11). Previous studies have reported mass spectrometry (MS) methods to identify compounds from human skin (12, 13). However, th...

High-Resolution Liquid Chromatography Tandem Mass Spectrometry Enables Large Scale Molecular Characterization of Dissolved Organic Matter

“…In addition, low annotation rates also result from the low number of available library spectra that match compounds in DOM. Nevertheless, the reported annotation rate is in a similar range as other non-targeted metabolomic datasets (Bouslimani et al, 2015;Petras et al, 2016;Floros et al, 2017) that are typically less complex than DOM.…”

Lifestyle chemistries from phones for individual profiling

“…Additionally, we chemically monitored phones and hands of 10 individuals 4 months after the first sample collection to determine long-term reproducibility and signature stability. A total of 588 metabolomic samples were analyzed using a previously validated ultra-performance liquid chromatography/quadrupole time-of-flight (UPLC-Q-TOF) tandemmass spectrometry (MS/MS) workflow (13), to detect metabolites present on hands and items (Fig. 1B).…”

“…Skin-associated chemicals also arise from personal habits including diet, exercise, clothes, medications, and personal care products. Together, these sources represent the vast majority of identifiable chemical entities on the human skin surface (13). Although no approach has been developed yet to capture such lifestyle-derived skin-associated chemicals from objects, the detection of molecular traces from the skin has been used in the past and involves very sensitive techniques.…”

Mass Spectrometry in Cosmetic Science: Advanced Ionization Techniques for Detecting Trace Molecules in or on Human Skin

“…To the best of our knowledge, only few studies have applied 2D-DESI MSI to the analysis of substances in skin samples, 22) excluding the direct or indirect (o ine) pro ling (non-imaging) of the surface of skin in forensic, 23) security, 24) and healthcare studies. 25) Note that most of the skin samples used in previous MSI studies consist of slice tissues or biopsies, which involve invasive procedures and are thus not suited for the daily evaluation of cosmetic products.…”