Fig. 3: Vβ5⁺ Treg cells protect from virus-induced colitis.

Tcrb^−/−Tcrd^−/− mice were reconstituted with wild-type CD8⁺ T cells together with either total CD4⁺ T cells (CD4 all) or Vβ5⁻CD4⁺ T cells (ΔVβ5) and infected with 10⁶ f.f.u. LCMV clone 13 or left naïve (n = 3–13). a Where indicated ΔVβ5 mice additionally received Vβ5⁺CD4⁺ T cells from DEREG mice and were treated with diphtheria toxin (ΔVβ5 + DEREG Vβ5⁺ with DTx), Vβ5⁺CD4⁺ T cells from Ifnar1^−/− mice (ΔVβ5 + IFNaR^−/− Vβ5⁺), no CD8⁺ T cells (ΔVβ5,no CD8⁺ T cells), adoptively transferred CD4⁺Foxp3⁺Vβ5⁺ or CD4⁺Foxp3⁺Vβ8⁺ Tregs cells isolated from LCMV clone 13 infected Foxp3-GFP.KI mice 7 days after infection (ΔVβ5 + Vβ5+ Treg AT or ΔVβ5 + Vβ8+ Treg AT, respectively), or received antibiotics-supplemented drinking water 4 wks prior reconstitution and throughout the experiment (ΔVβ5 + ABX). On day 17 post infection, gastrointestinal pathology was assessed and representative pictures of the lower gastrointestinal tract (GI: cecum and colon), H&E-stained cecal tissue sections (left) as well as combined pathology scores based on loss of epithelial cells, infiltration of PMN cells, number of goblet cells and the magnitude of submucosal edema (right) are shown. Arrows indicate tissue pathology. Scale bar 100 μm. b Mesenteric lymph-node cells isolated on day 17 post-infection were restimulated with PMA/ionomycin for 4 h and frequencies of CD44⁺CD62L⁻ as well as IFN-γ⁺ CD4⁺ and CD8⁺ T cells were determined by flow cytometry (n = 2–7). c Naïve or LCMV-infected (10⁶ f.f.u. clone 13) WT or reconstituted Tcrb^−/−Tcrd^−/− mice were fed with 15 mg FITC-dextran for 4 hrs on day 10 post-infection before FITC fluorescence was measured in serum (n = 3–6). d Splenocytes isolated on day 10 p.i. were restimulated with gut content for 6 h. Brefeldin A was added for the last 4 h and frequencies of IFN-γ⁺ CD4⁺ and CD8⁺ T cells were determined by flow cytometry (n = 4). Data are shown as mean ± SD; summary graphs display data of 2–4 independent experiments. For statistics, Mann–Whitney U was used.