STAT1 signaling is required in non-myeloid hematopoietic cells for microbiota-mediated hematopoiesis. (A) LSK populations were quantified from mice with or without STAT1 signaling in Vav-iCre;Stat1^fl/fl mice after 2 weeks with or without VNAM according to flow cytometry. (B) Then, 2 × 10⁶ whole bone marrow (WBM) cells from CD45.2⁺Stat1^−/− or WBM cells from WT mice were injected retro-orbitally into lethally irradiated CD45.1⁺ WT recipient mice. Twelve weeks after engraftment, the chimeric mice received 2 weeks of either VNAM treatment or mock treatment. (C) LSK populations were quantified from CD45.1⁺ recipient mice that received either WT or Stat1^−/− bone marrow (BM) and were treated with 2 weeks of VNAM after 12 weeks of engraftment according to flow cytometry. (D) Then, 2 × 10⁶ WBM cells from either CD45.1⁺ WT or CD45.2⁺Stat1^−/− mice were injected retro-orbitally into lethally irradiated CD45.2⁺Stat1^−/− recipient mice. Twelve weeks after engraftment, the chimeric mice received 2 weeks of either VNAM treatment or mock treatment. (E) BM progenitor populations were quantified from CD45.2⁺ recipient mice that received either CD45.1⁺ WT or CD45.2⁺Stat1^−/− BM and were treated with 2 weeks of VNAM after 12 weeks of engraftment according to flow cytometry. (F) LSK populations were quantified from mice with or without STAT1 signaling in LysM-Cre;Stat1^fl/fl mice after 2 weeks with or without VNAM according to flow cytometry. Results are compiled from 2 or 4 independent experiments (n = 4-10 per group) (panels A and F) or representative of 2 independent experiments (n = 7-10 [panel C] or n = 6-8 per group [panel E]). Graphs show mean ± SEM, with statistical significance determined by two-way analysis of variance with Šidák’s multiple comparisons test. *P < .05, **P < .01, ***P < .001, ****P < .0001. n.s., not significant.