Inflammatory exposure drives permanent impairment of hematopoietic stem cell self-renewal activity and accelerated aging

Hematopoietic stem cells (HSCs) mediate regeneration of the hematopoietic system following injury, as exemplified by the transient activation of HSCs out of dormancy upon exposure to infection or inflammation. Such challenges have been documented to impair HSC function. However, whether this functional impairment extends beyond the duration of inflammatory exposure is unknown. To assess the effects of repeated inflammatory challenge, wild-type C57BL/6J mice were subjected to a dose escalation regimen of polyinosinic:polycytidylic acid (pI:pC) treatment mimicking viral infection. Unexpectedly, we observed an irreversible depletion of functional HSCs and hallmarks of accelerated aging in LT-HSCs. In an effort to conclusively assess whether there was molecular evidence of accelerated aging of LT-HSC after sterile inflammation, we performed whole genome bisulfite sequencing and calculated the biological age by applying a multi-tissue DNA methylome clock. LT-HSCs from mice subject to inflammation demonstrated multiple cellular and molecular features of accelerated aging, including increased biological age. Overall design: Tagmentation-based whole-genome bisulfite sequencing (TWGBS) of purified LT-HSCs [Lin(-) c-kit(+) sca-1(+) CD150(+) CD48(-) CD34(-)] isolated from the bone marrow of pooled untreated (8- to 12-week-old), PBS or pI:pC treated (32- to 36-week-old) C57BL/6J mice, and individual (111- to 130-week old) aged C57BL/6J mice. Lineage markers (Lin): CD5, CD8a, CD11b, B220, Gr1, Ter119). For each replicate, two to four separate TWGBS libraries were prepared and pools of four libraries were sequenced on one to three separate HiSeq2000 lanes using the 125bp paired-end mode.