Tertiary Lymphoid Structures Sustain Cutaneous B cell Activity in Hidradenitis Suppurativa

Abstract

Hidradenitis suppurativa (HS) skin lesions are highly inflammatory and characterized by a large immune infiltrate. While B cells and plasma cells comprise a major component of this immune milieu the biology and contribution of these cells in HS pathogenesis is unclear. Here, we aimed to investigate the dynamics and microenvironmental interactions of B cells within cutaneous HS lesions. We combined histological analysis, single-cell RNA-sequencing (scRNAseq), and spatial transcriptomic profiling of HS lesions to define the tissue microenvironment relative to B cell activity within this disease. Our findings identify tertiary lymphoid structures (TLS) within HS lesions and describe organized interactions between T cells, B cells, antigen presenting cells and skin stroma. We find evidence that B cells within HS TLS actively undergo maturation, including participation in germinal center reactions and class switch recombination. Moreover, skin stroma and accumulating T cells are primed to support the formation of TLS and facilitate B cell recruitment during HS. Our data definitively demonstrate the presence of TLS in lesional HS skin and point to ongoing cutaneous B cell maturation through class switch recombination and affinity maturation during disease progression in this inflamed non-lymphoid tissue.

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“…Consistent with prior reports, tissue sections from both patients exhibited high levels of immune infiltrate and canonical lineage genes marked with the presence of T cells ( CD3E ), regulatory T cells ( FOXP3 ), B cells ( MS4A1 ), dendritic cells ( LAMP3 ), and granulocytes ( CD33 ) (Figure 2D) (12). In both patients, the spatial patterning of immune cells strongly coincided with the location of a tertiary lymphoid structure (TLS) gene signature (Figure 2E) (20). We further explored the enrichment of genes associated with class switched B cells and plasma cells and found high levels of IGHM, IGHA1, IGHG1 , and IGHG3 especially enriched in inflammation cluster 2 and 3 (Figure 2F).…”

“…C) Pathway enrichment analysis of differentially expressed genes in inflammation clusters. D) Pseudobulk analysis of genes in all 12 clusters from both patients comparing pre and post treatment groups E ) Spatial feature plot of TLS addmodule score in patient 1 (top) and patient 2 (bottom) derived from the top 50 TLS associated genes (20). F ) Violin plots of immunoglobin genes expression per cluster comparing pre and post treatment.…”

“…D ) Spatial feature plots of select leukocyte lineage genes. E ) Spatial feature plot of TLS score in patient 1 (top) and patient 2 (bottom) derived from the top 50 TLS associated genes (20). F ) Violin plots of immunoglobin genes expression per cluster of harmonized data from both patients.…”

“…We utilized their publicly available Seurat object “HEALTHY_ST_MARKERS.rds” and matched published annotations to analogous clusters in our harmonized object. TLS scores were calculated using the AddModuleScore function using gene sets described for TLSs (20). Enrichment analysis was derived using the package ‘clusterprofiler’ in R studio, using the function enrichGO (gene ontology) (25, 26).…”

“…Violin plots were generated using the 'dittoSeq' package in R studio (27). (20). F) Violin plots of immunoglobin genes expression per cluster comparing pre and post treatment.…”