Spontaneous lacrimal keratoconjunctivitis in aged NOD.B10.H2^b mice is accompanied by dysfunctional T regulatory cells

Abstract

Purpose: Dry eye occurrence increases with age, however the mechanism is not fully understood. To determine the mechanism of spontaneous lacrimal keratoconjunctivitis in aged NOD.B10.H2^b mice.

Methods: NOD.B10.H2^b is a congenic strain that fails to develop insulinitis, but develops minimal Sjogren’s syndrome-like disease at a young age. Ten week (young mice), 50 wk or 100 wk (aged) male mice were evaluated for parameters of ocular surface disease: corneal permeability by Oregon green dextran uptake, quantification of lymphocyte infiltration in the lacrimal gland (LG) and conjunctiva (CJ) by immunohistochemistry or flow cytometry (FC), goblet cell (GC) loss, increased production of inflammatory cytokines in serum (IFN-g, IL-17, and IL-13) by Luminex, and production of serum IgGs by ELISA. T regulatory cells (Tregs) were quantified by FC and function was determined by proliferation assays and cytokine quantification by Luminex.

Results: Both 50 wk and 100 wk old mice were examined and exhibited a similar phenotype. Corneal permeability significantly increased (p<0.001) in NOD.B10-H2^b aged mice compared to young mice. Aged mice had a significant increase of CD4⁺ T cells (p<0.001), and a significant loss of GCs was observed in the CJ. A significant increase (p<0.05) of B220⁺ B cells, CD8⁺ T cells, CD4⁺ T cells and CD25⁺ Tregs was observed in the LG of aged mice by FC. Systemically a significant increase of IFN-g, IL-17 (p<0.05) and serum antibodies (IgAk, IgG1k, IgG2ak, IgG2bk chains) (p<0.01) was determined. CD4⁺ T cells from aged mice produced significantly more IFN-g, IL-17, and IL-13 (p<0.005) than young mice. CD4⁺ T cells from aged mice proliferated at a higher rate than those from young mice, and Tregs from aged mice were unable to suppress the production of inflammatory cytokines, such as IFN-g, compared to Tregs from young mice.

Conclusions: Aged NOD.B10-H2^b mice spontaneously develop lacrimal keratoconjuntivitis. In spite of increased numbers, Tregs from aged mice are not able to suppress the production of inflammatory cytokines and ultimately control the autoimmunity that causes this disease.