S1PR1 inhibition induces proapoptotic signaling in T cells and limits humoral responses within lymph nodes
Dhaval Dixit, Victoria M. Hallisey, Ethan Y.S. Zhu, Martyna Okuniewska, Ken Cadwell, Jerry E. Chipuk, Jordan E. Axelrad, Susan R. Schwab
Dhaval Dixit, Victoria M. Hallisey, Ethan Y.S. Zhu, Martyna Okuniewska, Ken Cadwell, Jerry E. Chipuk, Jordan E. Axelrad, Susan R. Schwab
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Research Article Immunology

S1PR1 inhibition induces proapoptotic signaling in T cells and limits humoral responses within lymph nodes

Abstract

Effective immunity requires a large, diverse naive T cell repertoire circulating among lymphoid organs in search of antigen. Sphingosine 1-phosphate (S1P) and its receptor S1PR1 contribute by both directing T cell migration and supporting T cell survival. Here, we addressed how S1P enables T cell survival and the implications for patients treated with S1PR1 antagonists. We found that S1PR1 limited apoptosis by maintaining the appropriate balance of BCL2 family members via restraint of JNK activity. Interestingly, the same residues of S1PR1 that enable receptor internalization were required to prevent this proapoptotic cascade. Findings in mice were recapitulated in ulcerative colitis patients treated with the S1PR1 antagonist ozanimod, and the loss of naive T cells limited B cell responses. Our findings highlighted an effect of S1PR1 antagonists on the ability to mount immune responses within lymph nodes, beyond their effect on lymph node egress, and suggested both limitations and additional uses of this important class of drugs.

Authors

Dhaval Dixit, Victoria M. Hallisey, Ethan Y.S. Zhu, Martyna Okuniewska, Ken Cadwell, Jerry E. Chipuk, Jordan E. Axelrad, Susan R. Schwab

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Figure 5

JNK signaling regulates S1P-dependent naive T cell survival.

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JNK signaling regulates S1P-dependent naive T cell survival. (A) Represe...
(A) Representative histogram from a Spns2fl/fl Lyve1-Cre mouse and littermate control, and compilation of p-JNK expression. Each point represents the ratio of p-JNK MFI between a Spns2Δ or S1pr1Δ mouse and its littermate control (or mean of littermate controls, if more than one). Compilation of 4–5 experiments, 5–6 per group. (B) As in A, for p-cJun. Compilation of 4–5 experiments, 5–6 per group. (C) As in A, for p-MKK7. Compilation of 4 experiments, 4–5 per group. (D–G) Starting on day 0, S1pr1fl/fl UBC-CreERT2 and littermate control mice were treated daily with 15 mg/kg SP600125 (filled circles) or 20 mg/kg JNK-IN-8 (open circles) or vehicle. On days 1 and 2, the mice were treated with tamoxifen. On day 12, naive CD4+ T cells in LNs were analyzed. Relative values represent expression in 1 mouse divided by the mean for vehicle-treated controls in that experiment. (E) Relative p-cJun expression. (F) Frequency of ActCasp+ annexin V+ among naive CD4+ T cells. (G) Relative BCL2, PUMA, and BAX expression. Compilation of 6 experiments (4: SP600125; 2: JNK-IN-8), 6–7 per group. (H) Spns2fl/fl UBC-CreERT2 mice and littermate controls were treated with tamoxifen. Three weeks later, mice were treated with 30 mg/L DOP and 10 mg/L sucrose, or sucrose alone, in drinking water. After 3 weeks of treatment, naive CD4+ T cells in LNs were stained for p-JNK. Relative values as in A. Compilation of 3 experiments, 3–5 per group. (I) CellTraceViolet-labeled Bax–/– lymphocytes were transferred i.v. into Spns2fl/fl Lyve1-Cre mice or littermate controls; 21 days later, dye-labeled naive CD4+ T cells in LNs were analyzed by flow cytometry. Compilation of relative p-JNK and p-MKK7 expression by Bax–/– naive T cells. Relative values represent the MFI in 1 mouse divided by the mean MFI for controls in that experiment. Compilation of 2 experiments, 4–5 per group. A–C and I, Student’s t test; E–H, 1-way ANOVA with multiple comparisons. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001, ****P ≤ 0.0001.