Role of healthy skin molecular phenotype in the switch to specific skin diseases

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The risk of atopic dermatitis (AD), hidradenitis suppurativa, and lupus erythematosus is significantly higher in African American (AA) population, while White Non-Hispanic (WNH) subjects have a greater risk of psoriasis. The mechanisms that underlie disparity in susceptibility to different inflammatory skin diseases are poorly understood. In our pilot experiments, using extensively validated RNA-seq analysis we revealed striking differences in gene expression in healthy AA versus WNH skin, enriched for proinflammatory signaling. In addition, 3D human skin equivalent cultures (HSE) made from human primary keratinocytes seeded on collagen matrix, appeared to have a much more robust response to the pro-inflammatory effects of TNFa, a prototype cytokine involved in multiple inflammatory skin diseases. These results suggested that intrinsic pro-inflammatory circuits in AA skin/keratinocytes may contribute to the increased development of certain inflammatory skin diseases in the AA population including AD. However, the molecular mechanisms that trigger the shift of this “ambivalent” pre-disease inflammatory signaling towards specific inflammatory skin diseases remain to be investigated. 3D HSE made from primary human keratinocytes and immune cells as well as skin explant cultures treated with Th1/Th17 cytokines (TNFa, IL17, IL22) or Th2 cytokines (IL4, IL13) have been successfully used to induce in vitro morphological and molecular changes typical for psoriasis and AD. Thus, we hypothesized that different molecular phenotypes of AA and WNH healthy skin define molecular switch towards either pro-AD or pro-psoriasis signaling and that we could delineate the initial significant stages in this process using AA and WNH 3D HSE and skin explant cultures treated with Th1/Th17 (TNFa+IL17+IL22) or Th2 (IL3+IL14) cytokines. We propose to use in vitro skin models: 3D HSE made from AA and WNH adult skin cells (keratinocytes, fibroblasts and T cells from the same donor) and explant cultures of AA and WNH human skin provided by STEM Core at Northwestern SBDRC for cytokine treatment. We propose to use comprehensive approach including RNA-seq, Q-PCR, proximity extension immuno-PCR assay (Olink proteomics), confirmed by immunostaining with Vectra Multispectral Imager to identify onset of changes in 3D HSEs/skin explants gene/protein expression during the treatment with AD- or psoriasis-related cytokines. We will compare these changes to already identified/published molecular signatures of non-lesional and lesional skin in AD and psoriasis patients. We will also determine changes in epidermal barrier that are an integral part of psoriasis and AD pathophysiology. We expect that the obtained results will reveal whether and potentially how the molecular phenotype of healthy skin defines the switch to specific skin diseases and will set the stage for the development of personalized prevention approaches for different minority populations,