Abstract
Purpose :
CD25KO mice have severe autoimmune disease and are used as a model of Sjögren Syndrome, a prototype autoimmune dry eye. CD25KO mice have severe inflammation and infiltrating lymphocytes to multiple self-tissues, including the exocrine glands. We investigated the immunological profile of CD25KO mice and compared to wild-type (WT) mice.
Methods :
8-week-old WT and CD25KO mice were used. Total inflammation score was investigated in H&E-stained lacrimal gland (LG) sections (n=5). LGs (n=4) were submitted for RNA bulk sequencing. Flow cytometry was performed on single cell suspension of conjunctiva or cornea for markers of CD45, CD11b, CD3, CD4, CD64 and Ly6C. Corneal sensitivity was assessed using the Cochet-Bonnet test. Corneal nerves were fixed and nerve density assessed using Sholl analysis. Adoptive transfer of CD25KO CD4+ T cells or CD25KO CD4+ T cells + B6 CD25+GITR+ T regulatory cells (Tregs) was performed in RAG1KO mice. LGs were evaluated in H&E-stained sections and eyes were evaluated for corneal nerve density.
Results :
There was a significant increase in inflammatory score in CD25KO mice compared to WT. Investigation by RNA bulk sequencing found 3481 genes differentially expressed in CD25KO mice compared to B6, including upregulation of genes involved in T cell activation and Type I interferon signaling. Flow cytometry results showed an increased proportion of CD4+CD3+ T cells, CD11b+CD3-Ly6C+CD64+ monocytes and CD11b+CD3-Ly6C-CD64+ macrophages in CD25KO cornea and conjunctiva than WT. CD25KO mice had significantly decreased cornea sensitivity and decreased nerve density than WT mice. In mice that received adoptive transfer of CD25KO CD4+ T cells, LGs had inflammation scores significantly higher than naive mice and significantly less nerve density than naive mice. However, in recipient mice that received CD25KO CD4+ T cells + B6 Tregs, LGs had significantly reduced inflammatory scores and corneal nerve density was comparable to WT.
Conclusions :
CD25KO mice have phenotypic and genetic changes resulting in increased inflammation, systemic autoimmunity and severe lymphocytic infiltration to the exocrine glands. These results are prominent in the eye and LG. However, this autoimmunity can be controlled by addition of Tregs from healthy mice, suggesting a possible avenue for therapeutic research.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.