title: Ganglioside GM1 deficiency in effector T cells from NOD mice induces resistance to regulatory T-cell suppression.
abstract: OBJECTIVE
  To detect GM1 deficiency and determine its role in effector T cells (Teffs) from NOD mice in establishing resistance to regulatory T-cell (Treg) suppression.
  
  
  METHODS
  CD4(+) and CD8(+) Teffs were isolated from spleens of prediabetic NOD mice for comparison with similar cells from Balb/c, C57BL/6, and NOR mice. GM1 was quantified with thin-layer chromatography for total cellular GM1 and flow cytometry for cell-surface GM1. Suppression of Teff proliferation was determined by application of GM1 cross-linking agents or coculturing with Tregs. Calcium influx in Teffs was quantified using fura-2.
  
  
  RESULTS
  Resting and activated CD4(+) and CD8(+) Teffs of NOD mice contained significantly less GM1 than Teffs from the other three mouse strains tested. After activation, NOD Teffs resisted suppression by Tregs or GM1 cross-linking agents in contrast to robust suppression of Balb/c Teffs; this was reversed by preincubation of NOD Teffs with GM1. NOD Teffs also showed attenuated Ca(2+) influx via transient receptor potential channel 5 (TRPC5) channels induced by GM1 cross-linking, and this, too, was reversed by elevation of Teff GM1.
  
  
  CONCLUSIONS
  GM1 deficiency occurs in NOD Teffs and contributes importantly to failed suppression, which is rectified by increasing Teff GM1. Such elevation also reverses subthreshold Ca(2+) influx via TRPC5 channels, an essential aspect of suppression. Our results also support a critical role for galectin-1 as a GM1 cross-linking counter-receptor that fittingly is upregulated and released by Tregs during activation. These findings suggest a novel mechanism by which pathogenic Teffs evade regulatory suppression, thereby leading to autoimmune β-cell destruction and type 1 diabetes.
authors.affiliation: Department of Neurology and Neurosciences, New Jersey Medical School–University of Medicine and Dentistry of New Jersey, Newark, New Jersey, USA.
authors.forename: Gusheng
authors.initials: G
authors.lastname: Wu
authors.forename: Zi-Hua
authors.initials: ZH
authors.lastname: Lu
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Gabius
authors.forename: Robert W
authors.initials: RW
authors.lastname: Ledeen
authors.forename: David
authors.initials: D
authors.lastname: Bleich
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D005260:Female; D005677:G(M1) Ganglioside / Q000031:analogs & derivatives* / Q000276:immunology / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D016688:Mice, Inbred NOD; D013154:Spleen / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D050052:TRPC Cation Channels / Q000378:metabolism
chemical_list: D050052:TRPC Cation Channels; C112021:Trpc5 protein, mouse; C502266:ganglioside GM1alpha; D005677:G(M1) Ganglioside; D002118:Calcium