The immune modulator FTY720 inhibits sphingosine-1-phosphate lyase activity

Area of Science:

• Immunology
• Pharmacology
• Biochemistry

Background:

• FTY720 is a novel immunomodulatory agent that inhibits lymphocyte trafficking and prevents allograft rejection.
• FTY720 is phosphorylated in vivo to FTY720-phosphate, an agonist for sphingosine 1-phosphate receptors, primarily S1P1.
• FTY720 was designed by modifying myriocin, an immunosuppressive sphingoid base analog.

Purpose of the Study:

• To investigate the interactions between FTY720, FTY720-phosphate, and sphingosine-1-phosphate lyase (S1PL).
• To determine if S1PL contributes to FTY720 catabolism.
• To explore the potential of S1PL as a therapeutic target for immunomodulation.

Main Methods:

• In vitro assays to assess FTY720-phosphate stability with active S1PL.
• In vitro enzyme inhibition assays using FTY720 and S1PL.
• In vivo studies in mice treated with FTY720 to measure tissue S1PL activity, gene/protein expression, and sphingosine 1-phosphate levels.

Main Results:

• FTY720-phosphate is stable in the presence of active S1PL, indicating S1PL does not catabolize FTY720.
• FTY720 demonstrated potent inhibition of S1PL activity in vitro.
• FTY720 treatment in mice rapidly inhibited tissue S1PL activity without affecting lyase expression, while tissue sphingosine 1-phosphate levels remained stable or increased.

Conclusions:

• Sphingosine-1-phosphate lyase does not contribute to FTY720 catabolism.
• FTY720 inhibits sphingosine-1-phosphate lyase activity, suggesting a potential mechanism for its immunomodulatory effects.
• Disruption of sphingosine 1-phosphate metabolism by FTY720 may contribute to its effects on immune function, positioning S1PL as a potential therapeutic target.