Figure 1.

Tregs Express FABP5 during In Vitro Differentiation, and Blockade Affects Differentiation and Metabolism

Naive CD4⁺ T cells were cultured for 4 days under Treg cell-differentiation conditions.

(A) Mean relative expression (±SEM) of Fabp5 mRNA in in vitro-differentiated Tregs compared to naive CD4⁺ T cells (n = 3). FABP5 protein expression was assessed on D4. Results represent two independent experiments.

(B) Representative flow plots and quantification of Foxp3 expression and CTV dilution (±SEM) in Tregs cultured in the presence or absence of the FABP5 inhibitor BMS309403 (n = 4). Results represent three independent experiments. Gating controls are depicted in red.

(C) Naive CD4⁺ T cells were cultured for 3 days under Treg differentiation conditions before overnight BMS309403 treatment, and mean viability, relative cell number, and Foxp3 expression (±SEM) were measured (n = 4). Results represent >6 independent experiments. Gating controls are depicted in red.

(D–F) Mean (±SEM) basal OCR, basal ECAR, OCR/ECAR ratio and maximal respiration (after FCCP) of in vitro-differentiated mouse Tregs (n = 5). Results represent >6 independent experiments. (D) In vitro-differentiated human Tregs (n = 6). Results represent three independent experiments (E) or in vitro-differentiated mouse Tregs expressing Fabp5 shRNA (n = 5). Results represent two independent experiments. (F) cultured in the presence or absence of BMS309403 overnight at baseline, and in response to oligomycin (Oligo), FCCP, and rotenone and antimycin A (R + A).

(G) qPCR and protein expression of FABP5 following shRNA knockdown. Results represent two independent experiments. ^∗p < 0.05, ^∗∗∗p < 0.005, ^∗∗∗∗p < 0.001. P values were calculated using a two-tailed, unpaired t test.