Spatially decoding genotype-associated epigenetic landscapes in human lymphoma FFPE tissues via epi-Patho-DBiT

While formalin-fixed paraffin-embedded (FFPE) samples are invaluable for human non-Hodgkin B-cell lymphoma translational research, effective methods for spatial profiling of chromatin accessibility and histone modifications in these tissues remain limited. Here, we introduce epi-Patho-DBiT, a platform that combines reverse crosslinking of FFPE tissues with spatially resolved assays for transposase-accessible chromatin using sequencing (spatial-FFPE-ATAC) or cleavage under targets and tagmentation (spatial-FFPE-CUT&Tag). Using spatial-FFPE-ATAC, we map epigenetic landscapes in mucosa-associated lymphoid tissue and follicular lymphoma, identifying chromatin variants linked to B-cell malignancy and resolving tumor karyotypes. Mitotic age inference reveals spatial tumor dynamics and uncovers cholesterol-mediated cell proliferation. Furthermore, spatial-FFPE-CUT&Tag elucidates genomic alterations during transformation of follicular lymphoma into diffuse large B-cell lymphoma and identifies DIP2C with dysregulated H3K4me3 and H3K27me3 levels. Unexpectedly, we observe elevated H3K27me3 occupancy at a chromosome 2 locus containing tumor-promoting genes, attributed to copy number amplification and thereby upregulation in transformed diffuse large B-cell lymphoma.