Basophils and pro-inflammatory-fibroblast crosstalk modulates type 2 cutaneous inflammation

Summary: Abstract Body: Type 2 skin inflammation is pivotal in pathogen defense and tissue repair but can become aberrantly sustained, leading to inflammatory skin diseases like atopic dermatitis (AD). To identify key cellular interactions and transcriptional profiles driving inflammatory responses, we employed single-cell spatial transcriptomics (MERFISH) and matched scRNA-seq to analyze MC903 and oxazolone murine models, which is reported separately. Basophils crosstalk with pro-inflammatory fibroblasts by producing IL-4 and oncostatin M (OSM), confirmed through re-analysis of scRNA-seq studies. The combination of recombinant IL-4 and OSM synergistically upregulated phosphorylated STAT3 and STAT6 proteins (pSTAT3 and pSTAT6) as well as Cxcl12 and Tnc in primary mouse fibroblasts in vitro (p < 0.01), while human fibroblasts showed a similar response to recombinant OSM and IL-13. To assess basophil-fibroblast crosstalk in vivo, we depleted basophils in the MC903 model using neutralizing antibodies. Basophil depletion reduced type 2 inflammation, skin thickness (~30%, p < 0.0001), and pro-inflammatory fibroblast induction, as immunofluorescence revealed a 4-fold decrease in PDGFRA+/pSTAT3+ fibroblasts in basophil-depleted tissues (p < 0.01). Bulk RNA-seq and qPCR of fibroblast targets showed downregulation of genes such as Il4ra, Cxcl1, and Tnc. Furthermore, fibroblast-specific conditional Il4ra knockout mice exhibited reduced type 2 inflammation, a ~40% reduction in skin thickness (p < 0.0001), and diminished basophil infiltration (~75% reduction, p < 0.001), confirming the essential role of IL4RA+ pro-inflammatory fibroblasts in sustaining inflammation. Finally, combined OSM pathway blockade in fibroblast-specific Il4ra knockout mice further reduced inflammation, highlighting a novel therapeutic avenue. These findings demonstrate that basophil crosstalk with IL4RA+ pro-inflammatory fibroblasts is critical for regulating type 2 skin inflammation and offers therapeutic potential. Ichiro Imanishi¹, Raman Gill¹, Alexis Wilder¹, Inchul Cho¹, Paula Restrepo¹, Arjun Nair¹, Emma Guttman-Yassky¹, James Krueger², Brian Kim¹, Andrew Ji¹ 1. Icahn School of Medicine at Mount Sinai, New York, NY, United States. 2. The Rockefeller University Hospital, New York, NY, United States. Cell Communication Networks and Stromal Biology