Abstract
Purpose:
Previously, we found that IL-17 and IFN-γ double-positive T helper (Th17/1) cells can induce dry eye disease (DED). In this study, we aimed to determine the cytokines that promote conversion of Th17 cells to Th17/1 cells.
Methods:
Dry eye disease (DED) was induced in wild-type (WT) C57BL/6 mice using the controlled environmental chamber (CEC) for 14 days. The draining lymph nodes (DLN) of DED mice were harvested, and Th17 (IL-17+IFN-γ-) cells were sorted using cytokine secretion assay kits. Subsequently, sorted Th17 cells were injected intravenously into naïve Rag-/- mice (no B or T cells), which were then placed in the CEC for 5 days. These Rag-/- mice were injected with anti-IL12p40, anti-IL12, anti-IL23R antibodies, or isotype IgG one day before and one day after the transfer of Th17 cells. Disease severity was evaluated using corneal fluorescein staining (CFS). T cell cytokine secretion was analyzed using real-time PCR and flow cytometry.
Results:
On day 2 and day 5 after the transfer of Th17 cells, mice treated with anti-IL12p40, anti-IL12, or anti-IL23R antibodies showed significantly milder disease severity than those treated with isotype IgG (CFS scores on day 2: 2.5±1.0, 3.5±0.5, 1.3±0.8, vs. 6.3±0.8, p < 0.05; day 5: 3.5±0.3, 4.0±1.0, 2.5±0.9, vs. 7.5±1.0, p < 0.05). The disease severity among the different antibody-treated groups was similar. On day 5 after transfer, 36% of the purified Th17 cells converted to Th17/1 cells in the DLNs of mice treated with isotype IgG. In contrast, only 12%, 23%, and 20% of the transferred Th17 cells became double positive (IL-17/IFN-γ) in mice treated with anti-IL12p40, anti-IL12, or anti-IL23R antibodies, respectively. The mRNA expression of IFN-γ was significantly reduced on the conjunctivae in all three antibody treated groups compared to isotype IgG treated mice (mRNA copy numbers per 106 GAPDH copies: 22.1±2.3, 26.4±0.2, 20.0±4.3, vs. 40.0±4.6 in anti-IL12p40, anti-IL12, anti-IL23R, vs. isotype IgG treatments).
Conclusions:
These data demonstrated that blockade of IL-12 or IL-23 ameliorates DED by preventing the conversion of Th17 to double-positive Th17/1 cells and diminishing IFN-γ production in the conjunctiva.