Commensal Bacteria Reconstitution Delays Autoimmunity in the Germ-Free CD25KO Model of Sjögren Syndrome

Abstract

Purpose : To investigate the role of the gut microbiota in the appearance and development of dacryoadenitis in a model of Sjögren Syndrome.

Methods : Four-week (W) old germ-free (GF) CD25 knock-out (KO) mice of both sexes received oral gavage (OG) of fecal slurry from normal conventional C57BL/6 mice raised in specific pathogen free conditions and were compared to 8W old GF KO four weeks post-gavage. Corneal barrier function was assessed by fluorescent Oregon-Green Dextran dye staining. Eyes and adnexae were excised and prepared for either histology or frozen sections. Conjunctival goblet cell density was counted in periodic acid Schiff stained sections. CD4⁺T cells were isolated from cervical lymph nodes (CLN) and adoptively transferred into RAG1KO recipients. T helper (Th) phenotype in lacrimal gland and eye draining nodes of recipients was investigated by intracellular staining 5 weeks post-transfer.

Results : Germ-free animals gavaged with mouse fecal slurry (GF+OG) CD25KO have significantly greater number of goblet cells and significantly lower corneal barrier disruption than GF CD25KO mice (P<0.05 for all). GF+OG lacrimal glands showed decreased infiltration score and areas with normal acini, whereas GF CD25KO acini were shrunken and heavily infiltrated by lymphocytes. RAG1KO recipients of adoptively transferred GF+OG CD25KO CD4⁺T cells had significantly lower corneal barrier disruption, greater number of goblet cells, lower total lacrimal gland infiltration score and greater preservation of lacrimal gland architecture than recipients of GF CD25KO CD4⁺T cells (P<0.01 for all parameters). This was accompanied by lower percentage of CD4⁺ IFN-gamma⁺ cells in the lacrimal gland and draining nodes of GF+OG recipients compared to GF recipients (23.07±15% vs. 57.45±4.4% and 23.46±8.74% vs. 57.4±4.38%, respectively, P<0.001 for both).

Conclusions : Reconstitution of germ-free CD25KO mice with normal commensal delays the onset and severity of dacryoadenitis and ocular surface dry eye disease by decreasing the generation of autoreactive CD4⁺T cells.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.