Fig. 7.

Pharmacological inhibition of S1P/S1PR1 signaling impacts GVH and GVL responses. Lethally irradiated BALB/c mice (700 cGy) underwent transplantation with 5 × 10⁶ TCD-BMCs alone and with or without 0.75 × 10⁶ total T cells isolated from C57BL/6 donors. Recipient mice were injected i.p. with Sphk1 inhibitor (PF543) at 0.5 mg/kg or S1PR1 inhibitor (W146) at 1 mg/kg every other day from Day 0 to Day 14. Recipients were monitored for A body weight loss, B clinical score, and C survival over time (n = 10 mice/group). NSG-HLA-A2⁺ mice were irradiated (250 cGy) and transfused with HLA-A2⁻ human PBMCs (10 × 10⁶/mouse). Recipient (D) body weight loss and E survival were monitored for 60 days (n = 10 mice/group). Recipients were treated with PF543 or W146 as shown in A–C. Lethally irradiated B6D2F1 recipients (1100 cGy) were transplanted with 5 × 10⁶ TCD-BMCs alone or with 3 × 10⁶ total CD25-depleted T cells isolated from C57BL/6 donors with or without 5000 β-actin luciferase-transduced P815 mastocytoma. Recipients were treated with PF543 or W146 as in A–C. G Body weight loss, H clinical score, I survival, and J tumor mortality of recipients were monitored over time. F BLI images taken throughout the experiment were used to reflect tumor growth. In a separate experiment, spleens were collected from recipients on14 days after allo-BMT. K, L Representative histograms and summary graphs of CD107a, granzyme B, and perforin level on gated donor CD8⁺ T cells are shown (n = 6-7 mice/group). “BMA” in the summary graph indicates BM alone. The experiments were repeated 2 independent times, and combined data are presented. Log-rank (Mantel‒Cox) test (C, E, I, and J) and nonparametric Mann‒Whitney U test (A, B, D, G, and H) were performed to compare groups. Statistical data are presented as the mean ± 1 SD, and significance was determined by Student’s t-test. *P < 0.05, **P < 0.01 and ***P < 0.001