Polarized TCR-Transgenic Th17 Cells Resemble Th1 Cells in Their Capacity to Adoptively Transfer Ocular Inflammation, but Differ in Other Biological Activities

Abstract

Purpose:: The essential role of recently discovered T helper (Th) 17 lymphocytes in immunopathogenic processes has been well established, although little is known about their mode of action and other biological activities. Many features of T-cell populations, including their immunopathogenic capacities, have been defined by using TCR-transgenic (Tg) mice in which the majority of T-cells express an identical antigen receptor. Here we used this approach to prepare polarized populations of Th1 and Th17 cells, then compared these lines for their capacity to adoptively transfer ocular inflammation as well as for other biological activities.

Methods:: Our experimental system comprises Th cells from TCR-Tg mice specific against hen egg lysozyme (HEL), adoptively transferred into recipients that transgenically express HEL in the lens. Polarization and activation of Th1 or Th17 were performed by activation of naive CD4 cells in the presence of HEL, as well as with "cocktails" of both cytokines and antibodies known to drive polarization to Th1 or Th17, generally following the method of Kim et al, IOVS 2002. Polarization was determined by both intracellular expression and release of IFN-g or IL-17 into the culture medium by Th1 or Th17, respectively. Expression of surface markers on each cell population was determined by flow cytometry. Recipient eyes were examined histologically. Polarized cells were also tested for their capacity to induce splenomegaly in recipient mice (Chen et al, J. Imm. 2006).

Results:: Polarized and activated Th1 and Th17 cells were similarly immunopathogenic, transferring ocular inflammation at doses as low as 0.2 million. Histological analysis of the affected eyes revealed some differences between recipients of the two cell lines, particularly depicted by enhanced corneal inflammation and limbal neovascularization in recipients of Th17 cells. In addition, the two cell populations differed in levels of surface marker expression (in particular CD62L and CD49d) and in their capacity to stimulate temporal splenomegaly in recipients.

Conclusions:: TCR-Tg mice made it possible to generate lines of polarized Th17 cells and to compare these cells with polarized Th1 lines. The two cell lines exhibited similar levels of immunopathogenicity, but differed in patterns of pathological change, expression of cell surface markers, and capacity to stimulate splenomegaly in recipient mice.

Keywords: autoimmune disease • uveitis-clinical/animal model • cytokines/chemokines