Comprehensive spatial profiling of the spleen in murine myelofibrosis identifies targetable immune-stromal interactions

We perferomed spatial transcriptomics of murine spleens to map extramedullary hematopoiesis niches. Activated red pulp reticular cells localize near hematopoietic stem and progenitor cells, and early disease shows marginal zone disruption with lymphoid depletion preceding stromal remodeling.

Trajectory analyses reveal a shift of reticular cells from hematopoiesis-supportive to inflammatory and pro-fibrotic states driven by macrophage- and megakaryocyte-derived signals that activate complement and induce TNFα, TGF-β, extracellular matrix, and Thbs1 programs. Stromal deletion or pharmacological inhibition of complement component C3 suppresses these pathways, restores splenic architecture, and reduces splenomegaly and bone marrow fibrosis.