Effects of PDGFRa-lineage leukocyte extravasation to skin in atopic dermatitis

The circulating leukocyte population contains a fraction of cells derived from progenitors that had transient PDGFRa expression during embryonic development (PDGFRa-lineage). During inflammation, extravasated leukocytes in inflamed tissue modify the tissue-resident leukocyte population and crosstalk with the stromal cells. The current study investigates the effects of extravasated leukocytes derived from PDGFRa-lineage origin on the skin in atopic dermatitis (AD). Lineage- bone marrow progenitors were isolated from PDGFRa-lineage labeling mice which labels cells derived from PDGFRa-lineage with tdTomato. Progenitors derived from PDGFRa-lineage or non-PDGFRa-lineage were transplanted to irradiated EGFP-transgenic mice and allowed for bone marrow reconstitution (BMT). AD was then induced by repeated topical application of MC903 for six times. On day 14, RNA was isolated from inflamed skin to construct library for bulk RNA sequencing. AD skin transcriptomes of PDGFRa-lineage and non-PDGFRa-lineage BMTs were compared. In addition, the obtained dataset were paired with flow cytometric measurement of leukocyte extravasation to compare samples with similar extravasation loads. We found via functional enrichment analyses that extravasated PDGFRa-lineage leukocytes possess intrinsic properties that differ from non-PDGFRa-lineage, coordinate stronger inflammatory responses and modulate the extracellular matrix. Transcriptomic profiling of AD skin derived from EGFP-transgenic mice receiving bone marrow progenitor transplantation of controlled PDGFRa-lineage origin