title: Sphingosine kinase 1 activation enhances epidermal innate immunity through sphingosine-1-phosphate stimulation of cathelicidin production.
abstract: BACKGROUND
  The ceramide metabolite, sphingosine-1-phosphate (S1P), regulates multiple cellular functions in keratinocytes (KC). We recently discovered that production of a key innate immune element, cathelicidin antimicrobial peptide (CAMP), is stimulated via a NF-κB-dependent mechanism that is activated by S1P when S1P is generated by sphingosine kinase (SPHK) 1.
  
  
  OBJECTIVE
  We investigated whether pharmacological modulation of SPHK1 activity, using a novel synthetic SPHK1 activator, (S)-methyl 2-(hexanamide)-3-(4-hydroxyphenyl) propanoate (MHP), stimulates CAMP expression.
  
  
  METHODS
  MHP-mediated changes in both S1P and CAMP downstream mediators were analyzed in normal cultured human KC by qRT-PCR, Western immunoblot, ELISA, confocal microscopy for immunohistochemistry, HPLC and ESI-LC/MS/MS, and microbial pathogen invasion/colonization in a human epidermal organotypic model.
  
  
  RESULTS
  Treatment with MHP directly activated SPHK1 and increased cellular S1P content in normal cultured human KC. Because MHP did not inhibit S1P lyase activity, which hydrolyses S1P, augumented S1P levels could be attributed to increased synthesis rather than blockade of S1P degradation. Next, we found that exogenous MHP significantly stimulated CAMP mRNA and protein production in KC, increases that were significantly suppressed by siRNA directed against SPHK1, but not by a scrambled control siRNA. NF-κB activation, assessed by nuclear translocation of NF-κB, occurred in cells following incubation with MHP. Conversely, pretreatment with a specific inhibitor of SPHK1 decreased MHP-induced nuclear translocation of NF-κB, and significantly attenuated the MHP-mediated increase in CAMP production. Finally, topical MHP significantly suppressed invasion of the virulent Staphylococcus aureus into murine skin explants.
  
  
  CONCLUSIONS
  MHP activation of SPHK1, a target enzyme of CAMP production, can stimulate innate immunity.
authors.affiliation: CRID center, NeoPharm Co., Ltd., Daejeon 305-510, South Korea; College of Pharmacy, Chungbuk National University, Cheongju 361-763, South Korea.
authors.forename: Se Kyoo
authors.initials: SK
authors.lastname: Jeong
authors.affiliation: Department of Dermatology, School of Medicine, University of California, San Francisco, CA 94158, USA; Department of Veterans Affairs Medical Center, San Francisco, CA 94121, USA; Northern California Institute for Research and Education, San Francisco, CA 94121, USA.
authors.forename: Young Il
authors.initials: YI
authors.lastname: Kim
authors.affiliation: College of Pharmacy, Chungbuk National University, Cheongju 361-763, South Korea.
authors.forename: Kyong-Oh
authors.initials: KO
authors.lastname: Shin
authors.affiliation: CRID center, NeoPharm Co., Ltd., Daejeon 305-510, South Korea.
authors.forename: Bong-Woo
authors.initials: BW
authors.lastname: Kim
authors.affiliation: CRID center, NeoPharm Co., Ltd., Daejeon 305-510, South Korea.
authors.forename: Sin Hee
authors.initials: SH
authors.lastname: Lee
authors.affiliation: CRID center, NeoPharm Co., Ltd., Daejeon 305-510, South Korea.
authors.forename: Jeong Eun
authors.initials: JE
authors.lastname: Jeon
authors.affiliation: Department of Dermatology and Atopy Clinic, Seoul Medical Center, Seoul 131-865, South Korea.
authors.forename: Hyun Jong
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: College of Pharmacy, Chungbuk National University, Cheongju 361-763, South Korea.
authors.forename: Yong-Moon
authors.initials: YM
authors.lastname: Lee
authors.affiliation: Department of Dermatology, School of Medicine, University of California, San Francisco, CA 94158, USA; Department of Veterans Affairs Medical Center, San Francisco, CA 94121, USA; Northern California Institute for Research and Education, San Francisco, CA 94121, USA.
authors.forename: Theodora M
authors.initials: TM
authors.lastname: Mauro
authors.affiliation: Department of Dermatology, School of Medicine, University of California, San Francisco, CA 94158, USA; Department of Veterans Affairs Medical Center, San Francisco, CA 94121, USA; Northern California Institute for Research and Education, San Francisco, CA 94121, USA.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Elias
authors.affiliation: Department of Dermatology, School of Medicine, University of California, San Francisco, CA 94158, USA; Department of Veterans Affairs Medical Center, San Francisco, CA 94121, USA; Northern California Institute for Research and Education, San Francisco, CA 94121, USA. Electronic address: uchiday@derm.ucsf.edu.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Uchida
authors.affiliation: Department of Dermatology, School of Medicine, University of California, San Francisco, CA 94158, USA; Department of Veterans Affairs Medical Center, San Francisco, CA 94121, USA; Northern California Institute for Research and Education, San Francisco, CA 94121, USA. Electronic address: parkk@derm.ucsf.edu.
authors.forename: Kyungho
authors.initials: K
authors.lastname: Park
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis* / Q000235:genetics; D018407:Bacterial Physiological Phenomena / Q000187:drug effects; D002478:Cells, Cultured; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004817:Epidermis / Q000201:enzymology / Q000276:immunology*; D006801:Humans; D007113:Immunity, Innate; D015603:Keratinocytes / Q000737:chemistry / Q000201:enzymology* / Q000276:immunology; D008246:Lysophospholipids / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000187:drug effects / Q000502:physiology; D014443:Tyrosine / Q000031:analogs & derivatives / Q000494:pharmacology; D054804:Cathelicidins; D000099157:Sphingosine Kinase
chemical_list: D023181:Antimicrobial Cationic Peptides; D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D008246:Lysophospholipids; D016328:NF-kappa B; D017853:Phosphotransferases (Alcohol Group Acceptor); D012333:RNA, Messenger; D034741:RNA, Small Interfering; D013110:Sphingosine; D014443:Tyrosine; D054804:Cathelicidins; D000099157:Sphingosine Kinase; C000609873:methyl 2-(hexanamide)-3-(4-hydroxyphenyl)propanoate; C060506:sphingosine 1-phosphate
keywords: Antimicrobial defense; Cathelicidin antimicrobial peptide; Small molecule; Sphingosine kinase 1