T Cell Receptor-Regulated TGF-ß Type I Receptor Expression Determines T Cell Quiescence and Activation.

It is unclear how quiescence is enforced in naive T cells, but activation by foreign antigens and self-antigens is allowed, despite the presence of inhibitory signals. We showed that active transforming growth factor ß (TGF-ß) signaling was present in naive T cells, and T cell receptor (TCR) engagement reduced TGF-ß signaling during T cell activation by downregulating TGF-ß type 1 receptor (TßRI) through activation of caspase recruitment domain-containing protein 11 (CARD11) and nuclear factor κB (NF-κB). TGF-ß prevented TCR-mediated TßRI downregulation, but this was abrogated by interleukin-6 (IL-6). Mitigation of TCR-mediated TßRI downregulation through overexpression of TßRI in naive and activated T cells rendered T cells less responsive and suppressed autoimmunity. Naive T cells in autoimmune patients exhibited reduced TßRI expression and increased TCR-driven proliferation compared to healthy subjects. Thus, TCR-mediated regulation of TßRI-TGF-ß signaling acts as a crucial criterion to determine T cell quiescence and activation.

Tracking protein aggregation and mislocalization in cells with flow cytometry.

We applied pulse-shape analysis (PulSA) to monitor protein localization changes in mammalian cells by flow cytometry. PulSA enabled high-throughput tracking of protein aggregation, translocation from the cytoplasm to the nucleus and trafficking from the plasma membrane to the Golgi as well as stress-granule formation. Combining PulSA with tetracysteine-based oligomer sensors in a cell model of Huntington's disease enabled further separation of cells enriched with monomers, oligomers and inclusion bodies.

A convenient model of severe, high incidence autoimmune gastritis caused by polyclonal effector T cells and without perturbation of regulatory T cells.

Autoimmune gastritis results from the breakdown of T cell tolerance to the gastric H(+)/K(+) ATPase. The gastric H(+)/K(+) ATPase is responsible for the acidification of gastric juice and consists of an α subunit (H/Kα) and a ß subunit (H/Kß). Here we show that CD4(+) T cells from H/Kα-deficient mice (H/Kα(-/-)) are highly pathogenic and autoimmune gastritis can be induced in sublethally irradiated wildtype mice by adoptive transfer of unfractionated CD4(+) T cells from H/Kα(-/-) mice. All recipient mice consistently developed the most severe form of autoimmune gastritis 8 weeks after the transfer, featuring hypertrophy of the gastric mucosa, complete depletion of the parietal and zymogenic cells, and presence of autoantibodies to H(+)/K(+) ATPase in the serum. Furthermore, we demonstrated that the disease significantly affected stomach weight and stomach pH of recipient mice. Depletion of parietal cells in this disease model required the presence of both H/Kα and H/Kß since transfer of H/Kα(-/-) CD4(+) T cells did not result in depletion of parietal cells in H/Kα(-/-) or H/Kß(-/-) recipient mice. The consistency of disease severity, the use of polyclonal T cells and a specific T cell response to the gastric autoantigen make this an ideal disease model for the study of many aspects of organ-specific autoimmunity including prevention and treatment of the disease.