title: Acid Sphingomyelinase (ASM) is a Negative Regulator of Regulatory T Cell (Treg) Development.
abstract: OBJECTIVE
  Regulatory T cell (Treg) is required for the maintenance of tolerance to various tissue antigens and to protect the host from autoimmune disorders. However, Treg may, indirectly, support cancer progression and bacterial infections. Therefore, a balance of Treg function is pivotal for adequate immune responses. Acid sphingomyelinase (ASM) is a rate limiting enzyme involved in the production of ceramide by breaking down sphingomyelin. Previous studies in T-cells have suggested that ASM is involved in CD28 signalling, T lymphocyte granule secretion, degranulation, and vesicle shedding similar to the formation of phosphatidylserine-exposing microparticles from glial cells. However, whether ASM affects the development of Treg has not yet been described.
  
  
  METHODS
  Splenocytes, isolated Naive T lymphocytes and cultured T cells were characterized for various immune T cell markers by flow cytometery. Cell proliferation was measured by Carboxyfluorescein succinimidyl ester (CFSE) dye, cell cycle analysis by Propidium Iodide (PI), mRNA transcripts by q-RT PCR and protein expression by Western Blotting respectively.
  
  
  RESULTS
  ASM deficient mice have higher number of Treg compared with littermate control mice. In vitro induction of ASM deficient T cells in the presence of TGF-β and IL-2 lead to a significantly higher number of Foxp3+ induced Treg (iTreg) compared with control T-cells. Further, ASM deficient iTreg has less AKT (serine 473) phosphorylation and Rictor levels compared with control iTreg. Ceramide C6 led to significant reduction of iTreg in both ASM deficient and WT mice. The reduction in iTreg leads to induction of IL-1β, IL-6 and IL-17 but not IFN-γ mRNA levels.
  
  
  CONCLUSIONS
  ASM is a negative regulator of natural and iTreg.
authors: Department of Cardiology, Vascular Medicine and Physiology I, Tuebingen University, Tuebingen, Germany.
authors: Yuetao
authors: Y
authors: Zhou
authors: Madhuri S
authors: MS
authors: Salker
authors: Britta
authors: B
authors: Walker
authors: Patrick
authors: P
authors: Münzer
authors: Oliver
authors: O
authors: Borst
authors: Meinrad
authors: M
authors: Gawaz
authors: Erich
authors: E
authors: Gulbins
authors: Yogesh
authors: Y
authors: Singh
authors: Florian
authors: F
authors: Lang
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology*; D049109:Cell Proliferation; D002469:Cell Separation; D002518:Ceramides / Q000276:immunology / Q000378:metabolism; D005260:Female; D005452:Fluoresceins; D005456:Fluorescent Dyes; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000276:immunology; D015870:Gene Expression; D005786:Gene Expression Regulation; D007113:Immunity, Innate; D007376:Interleukin-2 / Q000494:pharmacology; D007378:Interleukins / Q000235:genetics / Q000276:immunology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D061251:Primary Cell Culture; D011419:Propidium; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics* / Q000276:immunology; D000076226:Rapamycin-Insensitive Companion of mTOR Protein; D015398:Signal Transduction; D013108:Sphingomyelin Phosphodiesterase / Q000172:deficiency / Q000235:genetics* / Q000276:immunology; D013154:Spleen / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D013388:Succinimides; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000494:pharmacology
chemical_list: C087165:5-(6)-carboxyfluorescein diacetate succinimidyl ester; D002352:Carrier Proteins; D002518:Ceramides; D005452:Fluoresceins; D005456:Fluorescent Dyes; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D007376:Interleukin-2; D007378:Interleukins; D012333:RNA, Messenger; D000076226:Rapamycin-Insensitive Companion of mTOR Protein; D013388:Succinimides; D016212:Transforming Growth Factor beta; C525637:rictor protein, mouse; D011419:Propidium; D051057:Proto-Oncogene Proteins c-akt; C112980:acid sphingomyelinase-1; D013108:Sphingomyelin Phosphodiesterase; C504327:N-(alpha-hydroxyoctadecanoyl)phytosphingosine