Interaction between GZMK + CD8 + T cells and fibroblasts contributes to neutrophilic inflammation in nasal polyps. a Representative immunofluorescence staining of collagen I (COL1A1, green), CD8 (red), and GZMK (yellow) in NPs. The right image shows a greater magnification of the outlined area. b Spatial distribution analysis of GZMK + CD8 + T and COL1A1 + cells in the same tissue field demonstrated in ( a ) using HALO software. c–d The number of COL1A1 + fibroblasts within a radius of 25 μm from the nuclear center of GZMK + CD8 + T, GZMB + CD8 + T, CD4 + T, or CD19 + B cells in CIT group (left, n = 10 samples) and NP group (right, n = 10 samples) ( c ). Average distance from the indicated cell types to the closest COL1A1 + fibroblasts in CIT group (left, n = 10 samples) and NP group (right, n = 10 samples) ( d ). e DEGs between NP-derived primary fibroblasts (NPDF) treated with and without recombinant human GZMK ( n = 4). Two-sided Wald test (default for DESeq2 r-package) was used for differential expression analysis utilizing standard cutoffs of