Figure 5.

Propionate Facilitates the Recirculation of cLP-Tregs Through Colonic dLNs and Blood to the Aneurysm

(A) Study overview: AAA was induced with elastase in sodium chloride–treated or propionate-treated KikGR mice, and 12 days later, the colons of the mice were exposed to UV light. Kik-red⁺ Tregs from the indicated tissues were examined by flow cytometry 36 hours after phC. (B) Representative contour plots of Kik-red⁺ Tregs in the cLP, colonic dLNs, blood, and aneurysms of mice treated as described in A. (C) The percentage of Kik-red⁺ Tregs among CD4⁺CD25⁺ Tregs in the cLP and the percentage of Kik-red⁺ Tregs in the cLP normalized to the initial phC Treg pool (n = 8-9). (D) The percentages of Kik-red⁺ Tregs among CD4⁺CD25⁺ Tregs in colonic dLNs (n = 7), blood (n = 6-7), and aneurysms (n = 6-7) 36 hours after the phC of mice treated as described in A. (E and F) C57BL/6J mice were administered sodium chloride (control mice), or propionate via their drinking water for 14 days before the induction of AAA by elastase. The mice were sacrificed 14 days after AAA induction for the analysis of cLP-Tregs by flow cytometry. (E) Mean fluorescence intensity of CCR7 on cLP-Tregs (n = 6-8). (F) The percentage of CD69⁺ Tregs among Foxp3⁺ Tregs in the cLP (n = 7-8). Each symbol represents a value acquired from an individual mouse. ∗P < 0.05, ∗∗P < 0.01. Error bars represent the mean ± SEM. Unpaired Student’s t-test (C to F). Data shown are representative of 2 to 4 independent experiments. MFI = mean fluorescence intensity; phC = photoconversion; other abbreviations as in Figures 1 and 3.