Engagement of S1P1-degradative mechanisms leads to vascular leak in mice

Abstract

GPCR inhibitors are highly prevalent in modern therapeutics. However, interference with complex GPCR regulatory mechanisms leads to both therapeutic efficacy and adverse effects. Recently, the sphingosine-1-phosphate (S1P) receptor inhibitor FTY720 (also known as Fingolimod), which induces lymphopenia and prevents neuroinflammation, was adopted as a disease-modifying therapeutic in multiple sclerosis. Although highly efficacious, dose-dependent increases in adverse events have tempered its utility. We show here that FTY720P induces phosphorylation of the C-terminal domain of S1P receptor 1 (S1P 1 ) at multiple sites, resulting in GPCR internalization, polyubiquitinylation, and degradation. We also identified the ubiquitin E3 ligase WWP2 in the GPCR complex and demonstrated its requirement in FTY720-induced receptor degradation. GPCR degradation was not essential for the induction of lymphopenia, but was critical for pulmonary vascular leak in vivo. Prevention of receptor phosphorylation, internalization, and degradation inhibited vascular leak, which suggests that discrete mechanisms of S1P receptor regulation are responsible for the efficacy and adverse events associated with this class of therapeutics.

Sphingosine-1-phosphate receptor 2 protects against anaphylactic shock through suppression of endothelial nitric oxide synthase in mice

“…16 Furthermore, administration of synthetic S1P 1 agonists, which powerfully induce downregulation of S1P 1 , but also that of S1P 1 antagonists induced pulmonary edema. 15,17,39 Therefore, S1P 1 seems to maintain vascular integrity in a tonic manner. 16 S1P 1 and S1P 2 activate distinct signaling pathways: S1P 1 mediates G i -dependent Rac activation, which is implicated in the vascular barrier integrity-maintaining action of S1P 1 , 8, 14 whereas S1P 2 mediates inhibition of Rac via G 12/13 .…”

“…22,23 Different from S1P 2 , S1P 1 maintains not only constitutive barrier integrity but protects against barrier disruption caused by anaphylaxis and inflammation. 15,16,39 It is likely that S1P 1 protects the integrity of AJ through a mechanism different from eNOS-NO regulation. Thus, these observations together with the previous Cui 21 observations 27 suggest that receptor signaling mediated by G q/11 , G i and G 12/13 play distinct critical roles in triggering, preventing and limiting vascular leakage.…”

Fingolimod: therapeutic mechanisms and ocular adverse effects

“…The use of fingolimod is thought to downregulate this receptor, thus leading to downregulation of adhesion complexes and subsequent increased retinal vascular permeability resulting in oedema. 25,26 Incidence of FAME Macular oedema has been a well-documented side effect of fingolimod since it was originally evaluated as an anti-rejection agent for renal transplantation. 27,28 Fingolimodassociated macular oedema was therefore monitored for and reported in the initial clinical trials investigating the efficacy of fingolimod for RRMS.…”

Identification and Preclinical Pharmacology of BMS-986104: A Differentiated S1P1 Receptor Modulator in Clinical Trials

“…In addition, the partial agonist profile in the internalization assay may reflect the improved pulmonary safety in preclinical studies (BAL protein elevation) since maintaining some level of S1P/S1P 1 signaling may be crucial for controlling vascular tone. 13 In order to confirm that the differentiated profile of 3d does not compromise its in vivo efficacy, we tested the compound in the CD45RB hi CD4 + T-cell transfer colitis model of inflammatory bowel disease (IBD). We chose to test 3d in this model since leukocyte infiltration into the inflamed intestine is fundamental to disease development and perpetuation in IBD.…”