title: Prevalence of newly generated naive regulatory T cells (Treg) is critical for Treg suppressive function and determines Treg dysfunction in multiple sclerosis.
abstract: The suppressive function of regulatory T cells (T(reg)) is impaired in multiple sclerosis (MS) patients. The mechanism underlying the T(reg) functional defect is unknown. T(reg) mature in the thymus and the majority of cells circulating in the periphery rapidly adopt a memory phenotype. Because our own previous findings suggest that the thymic output of T cells is impaired in MS, we hypothesized that an altered T(reg) generation may contribute to the suppressive deficiency. We therefore determined the role of T(reg) that enter the circulation as recent thymic emigrants (RTE) and, unlike their CD45RO(+) memory counterparts, express CD31 as typical surface marker. We show that the numbers of CD31(+)-coexpressing CD4(+)CD25(+)CD45RA(+)CD45RO(-)FOXP3(+) T(reg) (RTE-T(reg)) within peripheral blood decline with age and are significantly reduced in MS patients. The reduced de novo generation of RTE-T(reg) is compensated by higher proportions of memory T(reg), resulting in a stable cell count of the total T(reg) population. Depletion of CD31(+) cells from T(reg) diminishes the suppressive capacity of donor but not patient T(reg) and neutralizes the difference in inhibitory potencies between the two groups. Overall, there was a clear correlation between T(reg)-mediated suppression and the prevalence of RTE-T(reg), indicating that CD31-expressing naive T(reg) contribute to the functional properties of the entire T(reg) population. Furthermore, patient-derived T(reg), but not healthy T(reg), exhibit a contracted TCR Vbeta repertoire. These observations suggest that a shift in the homeostatic composition of T(reg) subsets related to a reduced thymic-dependent de novo generation of RTE-T(reg) with a compensatory expansion of memory T(reg) may contribute to the T(reg) defect associated with MS.
authors.affiliation: Division of Molecular Neuroimmunology, Department of Neurology, University of Heidelberg, Heidelberg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Haas
authors.forename: Benedikt
authors.initials: B
authors.lastname: Fritzsching
authors.forename: Petra
authors.initials: P
authors.lastname: Trübswetter
authors.forename: Mirjam
authors.initials: M
authors.lastname: Korporal
authors.forename: Linda
authors.initials: L
authors.lastname: Milkova
authors.forename: Brigitte
authors.initials: B
authors.lastname: Fritz
authors.forename: Diana
authors.initials: D
authors.lastname: Vobis
authors.forename: Peter H
authors.initials: PH
authors.lastname: Krammer
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Suri-Payer
authors.forename: Brigitte
authors.initials: B
authors.lastname: Wildemann
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002454:Cell Differentiation / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000276:immunology*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*
chemical_list: D019408:Platelet Endothelial Cell Adhesion Molecule-1