Journal: bioRxiv
Article Title: Interleukin-6 restricts pre-thymic T cell lineage commitment of progenitors driving loss of SIV control
doi: 10.64898/2026.01.29.702123
Figure Lengend Snippet: a, Schematic illustrating thymus-seeding progenitors (TSPs) arising from double-negative (DN; CD4⁻CD8⁻) CD34⁺CD7⁺ hematopoietic stem and progenitor cells (HSPCs) in the bone marrow and their migration to the thymus, where they undergo stepwise differentiation through CD4⁺CD3 − immature single-positive (ISP), CD4⁺CD8⁺ double-positive (DP), and single-positive (SP) CD4⁺ or CD8⁺ T-cell stages. b-c, Representative flow-cytometry plots showing (DN)CD34⁺CD7⁺ HSPCs in bone marrow (b) and thymus (c), with corresponding fluorescence-minus-one (FMO) controls. d, Frequency of (DN)CD34⁺CD7⁺ TSPs among bone-marrow and thymic HSPCs. e, Absolute numbers of (DN)CD34⁺CD7⁺ HSPCs per 10 6 total bone marrow mononuclear cells and thymocytes analyzed. f–i, Pearson correlation analyses between matched (N=8) bone-marrow and thymus derived CD4 − CD8 − double negative CD34 + progenitor populations, comparing frequencies of CD7 expressing (f), and non-expressing (g) DN CD34⁺ HSPCs. h, Pearson correlation between bone marrow derived CD34⁺CD38 − CD7⁺ (DN1) TSPs and thymus derived (DN)CD34+ (h), and (DN)CD34+CD7+TCF1+ (i) progenitors. Pearson correlation coefficients (r) and P values are shown. j, Schematic of the previously described Rhesus-specific nonanimal model of thymopoiesis known as Rhesus-artificial thymic organoid (RhATO) system , seeded with CD3 − (DN)CD34⁺CD7⁺ TSPs. k, Representative flow-cytometry plots illustrating T cell lineage committed differentiation intermediates representing frequencies of ISPs, and DPs early thymocyte intermediates, mature CD3⁺ T cells, as well as CD4⁺ and CD8⁺ single positive T cells, analyzed at week 4 of organoid establishment as previously described (k). l, Bar graph showing quantification of the frequencies of indicated thymocyte subsets generated in the RhATO-system (N=6 RhATOs). m, Schematic depicting uninfected (SIV⁻; N=15) and SIV-infected (SIV⁺; N=12) rhesus macaques (RMs) used to analyze bone marrow derived progenitors. n, Representative flow-cytometry plots showing (DN)CD34⁺CD7⁺ T cell committed progenitors in bone marrow of SIV⁻ and SIV⁺ RMs. o, Bar graph showing quantitation of the frequency of (DN)CD34⁺CD7⁺ TSPs among bone-marrow HSPCs in SIV⁻ and SIV⁺ RMs. p, Absolute numbers of (DN)CD34⁺CD7⁺ T-cell committed progenitors per 10⁶ bone-marrow mononuclear cells (BMMCs) analyzed. q, Absolute numbers of (DN)CD34⁺ HSPCs per 10⁶ BMMCs analyzed. r, Frequency of CD34⁺CD38 − CD7⁺ (DN1) TSPs among bone-marrow (DN)CD34+CD7+ progenitors in SIV⁻ and SIV⁺ animals. s, Experimental design showing RMs (N=6) infected with 300 TCID 50 SIVmac239M via intravenous route. Bone marrow aspirates (red dots) and blood (black dots) collected at the indicated timepoints starting with week 0 of infection. t, Line graph showing longitudinal plasma viral load (PVL) at the indicated timepoints. Geomean PVL indicated in black and individual data indicated in grey. u-v, Line graphs showing longitudinal frequencies of (DN)CD34⁺CD7⁺ (u) and CD34⁺CD38 − CD7⁺ (DN1) TSPs (v) TSPs at baseline (week 0) and at week 2, 4, 12, and 16 following SIV infection. w, Representative flow-cytometry plots and bar graph showing frequencies of T cells generated in RhATO cultures using 5000 CD3 − CD34 + HSPCs per RhATO isolated from bone marrow of RMs at week 16 of infection. x, Pearson correlation analysis between fold decrease of CD34 + CD38 − CD7 + (DN1) TSP population at week 2 of infection and frequency of T cells generated by CD3 − CD34 + HSPCs in RhATO culture. y–z, Pearson correlation analyses between total plasma viral burden until week 16 post infection represented as area under curve and fold decrease of CD34 + CD38 − CD7 + (DN1) TSP (y), and frequency of T cells generated in RhATO (z). Each symbol represents one animal. Statistical significance was determined using Mann Whitney unpaired two-tailed t-tests for unrelated data sets, Pearson correlation, or paired Wilcoxon test for related data sets; (*P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001).
Article Snippet: Isolation of human CD3-CD34+ HSPC: Total CD34+ HSPCs (Cat#BM34C-5) purchased from Charles River Laboratory Inc, Wilmington, MA, USA, were thawed and directly stained with live/dead stain, anti-CD3, and anti-CD34 antibodies.
Techniques: Migration, Flow Cytometry, Fluorescence, Derivative Assay, Expressing, Generated, Infection, Quantitation Assay, Clinical Proteomics, Isolation, MANN-WHITNEY, Two Tailed Test