Hematopoietic response in BM of Il6^−/− and LeprCre;Il6^fl/fl mice upon chronic repetitive LPS treatment. (A) Graphical scheme depicting experimental outline for modeling chronic inflammation by repetitive LPS injections over a 3-week period followed by analysis of different hematopoietic cell types as well as measurement of IL-6 levels in plasma and BM lysates. This schedule is applicable to the experimental data depicted in panels C to H. (B) Representative FACS profile showing gating strategy for the identification of LT-HSC and HPC, myeloerythroid progenitors (common myeloid progenitor [CMP]; GMP; and megakaryocyte-erythrocyte progenitor [MEP]) (left panel) as well as immature (CD11b⁺Gr1^low) and mature (CD11b⁺Gr1^high) granulocytic cells (right panel) in PBS-treated (upper panel) and LPS-treated (lower panel) Il6^−/−, LeprCre;Il6^fl/fl, and respective control mice. BM cellularity (C) and absolute numbers per hind leg of immunophenotypically defined LT-HSCs, HPCs, GMPs, CD11b⁺Gr1^high, and CD11b⁺Gr1^low cells (D) in LPS-treated (red bars) or PBS-treated (blue bars) WT and Il6^−/− mice according to the treatment schedule depicted under panel A. BM cellularity (E) and absolute numbers of immunophenotypically defined LT-HSCs, HPCs, GMPs, CD11b⁺Gr1^high, and CD11b⁺Gr1^low cells (F) in LPS-treated (red bars) or PBS-treated (blue bars) control and LeprCre;Il6^fl/fl mice according to the treatment schedule depicted under panel A. (G) IL-6 protein levels as measured by ELISA in plasma and BM lysates of Il6^−/− BM reciprocal chimeric mice after PBS (blue bars) or LPS (red bars) injection according to the experimental scheme shown in panel A. (H) IL-6 protein levels as measured by ELISA in plasma and BM lysates of LeprCre;Il6^fl/fl mice after PBS (blue bars) or LPS (red bars) injection according to the experimental scheme shown in panel A. *P < .05, **P < .01, ***P < .001, ****P < .0001. i.p., intraperitoneal; ns, nonsignificant.