title: Circulating monocytes are reduced by sphingosine-1-phosphate receptor modulators independently of S1P3.
abstract: Sphingosine-1-phosphate (S1P) receptors are critical for lymphocyte egress from secondary lymphoid organs, and S1P receptor modulators suppress lymphocyte circulation. However, the role of S1P receptors on monocytes is less clear. To elucidate this, we systematically evaluated monocytes in rats and mice, both in naive and inflammatory conditions, with S1P receptor modulators FTY720 and BAF312. We demonstrate that S1P receptor modulators reduce circulating monocytes in a similar time course as lymphocytes. Furthermore, total monocyte numbers were increased in the spleen and bone marrow, suggesting that S1P receptor modulation restricts egress from hematopoietic organs. Monocytes treated ex vivo with FTY720 had reduced CD40 expression and TNF-α production, suggesting a direct effect on monocyte activation. Similar reductions in protein expression and cytokine production were also found in vivo. Suppression of experimental autoimmune encephalomyelitis in mice and rats by FTY720 correlated with reduced numbers of lymphocytes and monocytes. These effects on monocytes were independent of S1P3, as treatment with BAF312, a S1P1,4,5 modulator, led to similar results. These data reveal a novel role for S1P receptors on monocytes and offer additional insights on the mechanism of action of S1P receptor modulators in disease.
authors: Department of Immunology and Inflammation, Boehringer Ingelheim Pharmaceuticals, Ridgefield, CT 06877, USA.
authors: Nuruddeen D
authors: ND
authors: Lewis
authors: Sokol A
authors: SA
authors: Haxhinasto
authors: Shawn M
authors: SM
authors: Anderson
authors: Dimitria E
authors: DE
authors: Stefanopoulos
authors: Steven E
authors: SE
authors: Fogal
authors: Prathima
authors: P
authors: Adusumalli
authors: Sudha N
authors: SN
authors: Desai
authors: Lori A
authors: LA
authors: Patnaude
authors: Susan M
authors: SM
authors: Lukas
authors: Kelli R
authors: KR
authors: Ryan
authors: Anthony J
authors: AJ
authors: Slavin
authors: Maryanne L
authors: ML
authors: Brown
authors: Louise K
authors: LK
authors: Modis
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000187:drug effects / Q000378:metabolism; D002465:Cell Movement / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000276:immunology / Q000378:metabolism; D005260:Female; D000068876:Fingolimod Hydrochloride; D007694:Killer Cells, Natural / Q000378:metabolism; D007958:Leukocyte Count; D051379:Mice; D009000:Monocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism; D011409:Propylene Glycols / Q000494:pharmacology*; D051381:Rats; D049349:Receptors, Lysosphingolipid / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013154:Spleen / Q000187:drug effects / Q000378:metabolism
chemical_list: D016207:Cytokines; D011409:Propylene Glycols; D049349:Receptors, Lysosphingolipid; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine