Regulatory T cells are essential for controlling autoimmune lacrimal gland pathogenic cells

Purpose: CD25KO mice have severe autoimmune disease and are used as a model of Sjögren disease, 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 it to wild-type (WT) mice. Methods: 8-week-old WT and CD25KO mice were used. LGs (n=5) were submitted for RNA bulk sequencing. Tears washes were collected from mice and analyzed for protein expression using a luminex assay. A time course of adoptive transfer of CD25KO CD4+T cells was performed and LGs were evaluated by histology and qPCR. Co-adoptive transfer of CD25KO CD4+T cells with either 2M or 20M B6 CD25+GITR+T regulatory cells (Tregs) was performed in RAG1KO mice. LGs were evaluated in H&E-stained sections and by qPCR. Results: 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. CD25KO mice produced the same volume of tears as wild-type littermate controls, but had elevated protein expression of TNF, IFN-γ, and CCL5 and decreased protein expression of IL-12p40 and VEGF-A. Adoptive transfer recipients begin to develop inflammation and disease three weeks after adoptive transfer. In mice that received adoptive transfer of CD25KO CD4+ T cells, LGs had inflammation scores significantly higher than naive mice. They had increased expression of transcripts for inflammatory cytokines and chemokines. However, in recipient mice that received CD25KO CD4+T cells + 2M B6 Tregs, LGs had significantly reduced inflammatory scores and reduced expression of some inflammatory cytokines. Recipients of CD25KO CD4+T cells + 20M B6 Tregs had more inflamed lacrimal glands by both histology and qPCR, suggesting aged Tregs have less suppressive capacity.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 tear film and LG. However, this autoimmunity can be controlled by addition of Tregs from healthy young mice, suggesting a possible avenue for therapeutic research.