Human CD4+CD25+ regulatory T cells: proteome analysis identifies galectin-10 as a novel marker essential for their anergy and suppressive function.

CD4(+)CD25(+)Foxp3(+) regulatory T cells (CD25(+) Treg cells) direct the maintenance of immunological self-tolerance by active suppression of autoaggressive T-cell populations. However, the molecules mediating the anergic state and regulatory function of CD25(+) Treg cells are still elusive. Using differential proteomics, we identified galectin-10, a member of the lectin family, as constitutively expressed in human CD25(+) Treg cells, while they are nearly absent in resting and activated CD4(+) T cells. These data were confirmed on the mRNA and protein levels. Single-cell staining and flow cytometry showed a strictly intracellular expression of galectin-10 in CD25(+) Treg cells. Specific inhibition of galectin-10 restored the proliferative capacity of CD25(+) Treg cells and abrogated their suppressive function. Notably, first identified here as expressed in human T lymphocytes, galectin-10 is essential for the functional properties of CD25(+) Treg cells.

An enzyme module system for the synthesis of dTDP-activated deoxysugars from dTMP and sucrose.

A flexible enzyme module system is presented that allows preparative access to important dTDP-activated deoxyhexoses from dTMP and sucrose. The strategic combination of the recombinant enzymes dTMP-kinase and sucrose synthase (SuSy), and the enzymes RmlB (4,6-dehydratase), RmlC (3,5-epimerase) and RmlD (4-ketoreductase) from the biosynthetic pathway of dTDP-beta-L-rhamnose was optimized. The SuSy module (dTMP-kinase, SuSy, +/-RmlB) yielded the precursor dTDP-alpha-D-glucose (2) or the biosynthetic intermediate dTDP-6-deoxy-4-keto-alpha-D-glucose (3) on a 0.2-0.6 g scale with overall yields of 62 % and 72 %, respectively. A two-step strategy in which the SuSy module was followed by the deoxysugar module (RmlC and RmlD) resulted in the synthesis of dTDP-beta-L-rhamnose (4; 24.1 micromol, overall yield: 35.9 %). Substitution of RmlC by DnmU from the dTDP-beta-L-daunosamine pathway of Streptomyces peucetius in this module demonstrated that DnmU acts in vitro as a 3,5-epimerase with 3 as substrate to yield 4 (32.2 mumol, overall yield: 44.7 %). Chemical reduction of 3 with NaBH4 gave a mixture of the C-4 epimers dTDP-alpha-D-quinovose (6) and dTDP-alpha-D-fucose (7) in a ratio of 2:1. In summary, the modular character of the presented enzyme system provides valuable compounds for the biochemical characterization of deoxysugar pathways playing a major role in microbial producers of antibiotic and antitumour agents.

Application of proteomics and protein analysis for biomarker and target finding for immunotherapy.

Regulatory T-cells play a central role in the maintenance of the immunological balance and are powerful inhibitors of T-cell activation both in vivo and in vitro. The enhancement of suppressor-cell function might be a target for immunotherapeutic approaches for the treatment of immune-mediated diseases like multiple sclerosis and Crohn's disease.The method of choice to elucidate the still unclear effector functions of regulatory T-cells is the differential proteome analyses performed with human and murine T-cell populations. To this end, whole-protein extracts of conventional and regulatory T-cells are separated by high-resolution two-dimensional gel electrophoresis according to Klose. The proteomes are analyzed by a 2DE gel image analysis software, ProteomWeaver. The protein spots that are found differentially expressed are picked from the gels and prepared for matrix-assisted laser desorption/ionization (MALDI) mass spectrometrical analysis automatically. The high-resolution 2DE-PAGE and the automated spot handling and protein identification allows one to rapidly find new potential candidate proteins that are of functional relevance for regulatory T-cells, to be used as targets for drug development or as biomarkers for research and diagnostic purposes.