CD8 T cells induce destruction of bone marrow stromal niches and hematopoietic stem cell dysfunction in chronic viral infections

Chronic viral infections are associated with hematopoietic suppression and bone marrow (BM) failure, which have been linked to hematopoietic stem cell (HSC) exhaustion. However, how persistent viral infectious challenge and ensuing inflammatory responses target BM tissues and perturb hematopoietic homeostasis remains poorly understood. Here, we combine extensive functional analyses with advanced 3D microscopy to demonstrate that chronic infection with lymphocytic choriomeningitis virus clone 13 results in the long-term impairment of HSC function, concomitant with a persistent destruction of the HSC-supportive stromal networks of mesenchymal CXCL12-abundant reticular cells. During infections, long lasting injuries and aberrant transcriptional programs of the stromal infrastructure diminish the capacity of the BM microenvironment to adequately support HSC maintenance. Mechanistically, BM immunopathology is elicited by virus-specific, activated CD8 T cells, which accumulate in the BM via interferon-dependent mechanisms. Combined inhibition of type I and II IFN pathways completely preempts viral-mediated degeneration of CARc networks and protects HSCs from persistent dysfunction. Hence, viral infections and ensuing immune reactions chronically interfere with BM function by disrupting essential stromal-derived, hematopoietic-supporting cues.