Fig 1: Inosine inhibited the poly ADP-ribose polymerase 14/Stat6 signaling pathway. (A) The expression of inosine-related transporters in healthy human CD19+ B cells (data sourced from GSE215936). (B) MFI quantification of ENT1 expression in activated and naïve B cells. (C) Representative confocal images of ENT1, IgD, and DAPI in the liver tissue of patients with AIH. (D) Representative flow cytometry plots (left) and quantification of the percentage of ENT1+IgD+ naïve B cells from patients with AIH (n = 8) and HCs (n = 5). (E) Fold change in mRNA expression of SLC29A1 assessed by RT-qPCR in human CD19+ B cells treated with or without inosine (250 μM) for 24 hours (n = 3 biological replicates). (F) Expression levels of ENT1 in B cells treated with varying doses of inosine (100, 250 μM) for 3 days. (G) Structure diagram illustrated the pharmacological inhibition of ENT1 by dipyridamole (DIP). (H) Representative flow cytometry plots (left) and quantification of the percentage of BNDs and CNBs in naïve B cells treated with dipyridamole (1 μM) or vehicle, in the presence and absence of inosine (250 μM) for 3 days (n = 3 biological replicates). (I) Quantification of the percentage of ASCs treated with dipyridamole (1 μM) or vehicle, in the presence and absence of inosine (250 μM) for 3 days (n = 3 biological replicates). (J) Fold change in mRNA expression of PARP1 and PARP14 assessed by RT-qPCR in human CD19+ B cells treated with dipyridamole (1 μM) or vehicle, in the presence and absence of inosine (250 μM) for 24 hours (n = 3 biological replicates). (K) Quantification of the percentages of BNDs in naïve B cells and ASCs, in the presence and absence of the PARP14 inhibitor RBN012759 (1 μM) for 3 days. (L) Expression levels of PARP14, JAK1, and Stat6 in CD19+ B cells treated with dipyridamole (1 μM) or vehicle, in the presence and absence of inosine (250 μM) for 3 days. (M) Representative histograms and statistical analyses of Stat6 phosphorylation in different B cell subsets for 30 minutes were measured. (N) Representative histograms (left) and statistical analyses of Stat6 phosphorylation in CD19+ B cells treated with dipyridamole (1 μM) or vehicle, in the presence and absence of inosine (250 μM) for 30 minutes. (O) Expression level of MZB1 in human CD19+ B cells treated with dipyridamole (1 μM) or vehicle, in the presence and absence of inosine (250 μM) for 24 hours. (P) Expression levels of PARP14, PARP1, and MZB1 in CD19+ B cells from patients with AIH (n = 3) in the presence and absence of inosine (250 μM) for 3 days. (Q) Quantification of the percentages of BNDs in naïve B cells and ASCs in the presence and absence of the PARP14 inhibitor RBN012759 (1 μM) for 3 days from patients with AIH (n = 3). Results are expressed as mean ± SEM. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; and ∗∗∗∗P < .0001.