Fig 2: Bach2 restrains Treg cell suppressive function in colitis.Bach2fl/flFoxp3Cre and Foxp3Cre control mice were administered 1.5% (w/v) dextran sodium sulfate (DSS) in drinking water for 5 days and regular drinking water for another two days. a Mouse weight over time normalized to starting weight. b Representative colons from DSS-treated Foxp3Cre and Bach2fl/flFoxp3Cre mice (left) and quantification of colon length (right). c Flow cytometry plots quantifying monocytes in the colonic lamina propria. d Histological staining of the distal colon of DSS-treated mice. Arrowhead indicates submucosal inflammatory infiltrate, solid arrow, transmural inflammatory infiltrate, dashed arrow, mucosal inflammatory infiltrate and erosion of the crypt-villus architecture. Scale bar = 200 µm. e Quantification of disease scores between genotypes. f Frequencies of Treg cells in the colonic lamina propria of DSS-treated Foxp3Cre and Bach2fl/flFoxp3Cre mice. g Flow cytometry plots showing IL-10 and KLRG1 expression by Treg cells from the lamina propria (left), and quantification of expression (right). Flow cytometry plots are representative, data are pooled from (a and b) or representative of (c–g) two independent experiments with seven control and nine conditional knockout mice. Significance tested using two-way ANOVA with Šidák correction for multiple comparisons (a). Otherwise, statistical significance was tested using the unpaired Student’s t-test. Error bars denote mean ± S.D.; ns–not significant. Source data are provided as a Source Data file.

Fig 3: Bach2 limits activation and effector differentiation of mature Treg cells.a Flow cytometry plots showing Bach2-RFP reporter expression by splenic Treg cells with naïve (CD62L+) and activated (CD62L-) phenotypes, or wildtype cells (dashed line). b Co-expression of Bach2-RFP with indicated activation-associated molecules. c Proportions and numbers and of Treg cells in the spleens and pooled brachial, axial and inguinal lymph nodes of 6 to 8-week-old Foxp3Cre and Bach2fl/flFoxp3Cre mice. d Histograms showing expression of indicated molecules (upper) and quantification of their expression (lower), as measured by flow cytometry of splenic Treg cells from 6 to 8-week-old Foxp3Cre and Bach2fl/flFoxp3Cre mice. e, f Splenic Treg cells from Foxp3Cre and Bach2fl/flFoxp3Cre mice were isolated by flow cytometry and subjected to RNA-seq. e Heatmap shows expression of the top 200-most differentially expressed genes, with genes of interest indicated. f Gene set enrichment plot for a gene signature of eTreg cells32 in the comparison between Bach2fl/flFoxp3Cre and control Foxp3Cre Treg cells. g Flow cytometry plots showing expression of KLRG1 and ST2 by Treg cells isolated from the colonic lamina proprium, liver and lung tissue of Foxp3Cre and Bach2fl/flFoxp3Cre mice (left). Frequencies of KLRG1-expressing Treg cells in indicated organs from Bach2fl/flFoxp3Cre mice and controls (right). Flow cytometry plots and data in (a, b, and d) are representative of 2–3 independent experiments with at least 6 mice. Data in c and g are pooled from two independent experiments. Statistical significance was tested using the unpaired Student’s t-test. Error bars denote mean ±S.D.; ns – not significant. Source data are provided as a Source Data file.