Fig 2: Capping protein (CP) complex promotes stress progenitor activity.(A) Experimental layout of ex vivo spleen retroviral infection and cultures. (B) Relative mRNA expression of sterile alpha motif domain 14 (Samd14), Capzb, Capza1, and Capza2 in control vs phenylhydrazine (PHZ)-treated CD71+Kit+Ter119- spleen cultures. (C) Quantitation of Capzb mRNA in fluorescence-activated cell sorting (FACS)-purified GFP+Kit+CD71+ cells from wild type (WT) mice following retroviral infection with shControl, shCapzb2 after 2-day culture (left); Western blot of primary spleen cultures following Capzß knockdown (shCapzb2) or shControl stained with anti-Capzß and ß-actin antibodies (right). (D) Quantitation of Samd14 mRNA in FACS-purified GFP+Kit+CD71+ cells from WT mice following retroviral infection with shControl, shCapzb2 after 2-day culture. (E) Quantitation of infected R1–R5 cells in WT PHZ-treated cells following Capzb knockdown. (F) Representative images from Wright-Giemsa stained cells following Capzb knockdown (40 × magnification)(G) Retrovirally-infected spleen progenitors were GFP-purified by FACS and grown for 2 days colony forming unit-erythroid (CFU-E) or 5 days burst forming unit-erythroid (BFU-E) and quantitated (N=9). (H) Representative flow cytometry scatter plot of membrane-impermeable DNA dye (Draq7) and anti-annexin V pacific blue (AnnV). Cells were first segregated on GFP+ and Kit+ gating. Live = Draq7- AnnV-; Early apoptotic (EA)=Draq7-AnnV+; Late apoptotic (LA)=Draq7+AnnV+. (I) Quantitation of percent dead, LA and EA cells in the GFP+Kit+ cells (left) and GFP+CD71+Ter119+ (right). Error bars represent SD. *p<0.05; **p<0.01; ***p<0.001; ****p<0.0001 (two-tailed unpaired Student’s t test). Figure 3—source data 1.Source Western blot images for Figure 3.

Fig 3: Pharmacological inhibition of IL-1ß decreased myelofibrosis in MPN mice.a Experimental setup of the drug treatment. b Grade of reticulin fibrosis was determined before therapy in groups of n = 6 mice killed at 12-, 16-, and 20-weeks after transplantation. c Time course of body weights (n = 12 mice per treatment group). Two-way ANOVA followed by uncorrected Fisher’s LSD test was performed. d Blood counts and mutant cell (% GFP) chimerism in the peripheral blood of vehicle (n = 12); ruxolitinib (n = 11); anti-IL-1ß (n = 12); combo (n = 12) treated mice in erythroid (Ter119), megakaryocytic (CD61), granulocytic (Gr1), and monocytic (CD11b) lineages. Two-way ANOVA followed by uncorrected Fisher’s LSD test was performed. Two-way ANOVA followed by Dunnett’s multiple comparisons test was performed for GFP chimerism. e Spleen weights of vehicle (n = 12); ruxolitinib (n = 11); anti-IL-1ß (n = 12); combo (n = 12) treated mice after 8 weeks of drug treatment. Two-tailed unpaired t-test was performed. Grey area represents normal range. f Representative images of reticulin fibrosis and H&E staining is shown and histological grade of reticulin fibrosis in the BM is illustrated in the bar graph. Similar results were obtained with other mice in each condition. Stacking bar graph showing the percentage of mice with osteosclerosis in the BM of vehicle (n = 12); Ruxolitinib (n = 11); anti-IL-1ß (n = 12); and combo (n = 12). Two-tailed unpaired t test was performed for comparisons of fibrosis grades between different groups. p value is computed using Fisher’s exact test for presence or absence of osteosclerosis in bone marrow. g Heatmap plot showing the inflammatory cytokine levels in the BM lavage and plasma of mice after 8 weeks of drug treatment. Vehicle (n = 12); Ruxolitinib (n = 11); anti-IL-1ß (n = 12); combo (n = 12). The color bars indicate treatment groups. Heatmap shows Z scores. Two-tailed unpaired t-tests without correction for multiple comparisons was performed. Green-colored asterisk is used for comparison of vehicle vs. anti-IL-1ß; salmon for vehicle vs. ruxolitinib; plum for vehicle vs. combo. All data are presented as mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. See also Supplementary Figs. 9–11. Source data and exact p values are provided as a Source Data file.

Fig 4: Liprox-1 alleviated accelerated atherosclerosis progression in Jak2VFMx-Cre clonal hematopoiesis.20% of Jak2VFMX-Cre (VFMX) mice were fed with Western diet together with Liprox-1 (10mg/kg, 3 times per week) or vehicle injection for 12 weeks. (A) Experiment timeline. (B) H&E-stained images of aortic root sections. Necrotic core regions indicated by broken lines, and quantification of total lesion area and necrotic core area are shown. Scale bar: 200 µm. (C) Iron (Perl’s blue) and redox-active iron deposition (Perl’s blue + DAB); IHC staining of RBCs (anti-Ter119) and macrophages (anti-Mac2) in aortic roots. (D) Bar graph shows quantification of iron (II + III)–positive and erythrophagocytosis (Ter119+Mac2+) cell counts per section. Scale bar: 100 µm. (E) Aortic root sections were stained with Masson’s trichrome staining for fibrous cap (red, outlined by broken lines) and collagen (blue) content area, and then (F) quantified as the ratio of total lesion area. Scale bar: 100 µm. (G) Lipid peroxidation product 4-HNE staining, quantified as the percentage of total lesion area. Scale bar: 100 µm. Unpaired 2-tailed t test. *P < 0.05, **P < 0.01, ***P < 0.001.

Fig 5: LRP6 Mediates the Uptake of oxPLs by MSCs. a–d Fluorescence imaging of the binding and uptake of DiI-nLDL and DiI-oxLDL (dissolved in PBS) by MSCs. Bone marrow MSCs isolated from GFP transgenic mice were transfected with either irrelevant control siRNA (siControl) (a, c) or LRP6 siRNA (siLRP6) (b, d). 2 days later, the cells were incubated with DiI-nLDL (a, b) or DiI-oxLDL (c, d) for 2 h at 4 ?, and were then incubated at 37 ? for 0 min, 10 min, or 30 min. Cells were washed, fixed, and analyzed by fluorescence microscopy. (Scale bar: 10 µm). e Mice were injected with DiI-nLDL or DiI-oxLDL (dissolved in PBS) via tail vein at a dose of 20 µg per mouse. 4 h after injection, Mice were killed at 4 h after injection, and the bone marrow cells were subjected to flow cytometry analysis. The percentages of the DiI-nLDL or DiI-oxLDL uptake by LepR+CD45–CD31–Ter119- MSCs are shown in the lower panel. f, g LRP6+/+::LepR-Cre and LRP6f/+::LepR-Cre mice were injected with DiI-oxLDL via tail vein at a dose of 20 µg per mouse. 4 h after injection, mice were killed, and bone marrow cells were subjected to flow cytometry analysis. Representative images of the percentage of LRP6+ cells are shown in f. The percentages of the DiI-oxLDL uptake by LepR+CD45–CD31–Ter119- cells are shown in g. n = 5, data are represented as mean ± s.e.m