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Katherine Held, Chris Schaumburg, Jianping Gao, Larry Wheeler, Margarita Calonge, Jerry Niederkorn, Stephen Pflugfelder, Michael Stern; Potential Regulatory T Cell Mechanisms Of Immune Suppression In A Mouse Model Of Dry Eye. Invest. Ophthalmol. Vis. Sci. 2013;54(15):919.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate immunosuppressive properties of inducible and natural T regulatory (Tregs) subsets following induction of experimental dry eye in mice.
Flow cytometry was utilized to characterize Tregs within the periphery during experimental dry eye to determine i) the frequencies of inducible, iTregs, and natural, nTregs, and ii) the level of expression markers indicating activation and the capacity for suppression by metabolic disruption and dendritic cell immune modulation. C57BL/6 wild-type female mice were exposed to desiccating environmental stress (DS; subcutaneous scopolamine injections, humidity <40%, and air flow across wire meshed screened cages) for 3 or 10 days. Draining cervical lymph nodes were collected from control or DS mice, and processed for flow cytometric analysis. nTregs (Foxp3+ Helios+CD25hi) were distinguished from iTregs (Foxp3+ Helios-CD25hi) using the Helios transcription factor as a putative marker for thymus-derived Tregs. The expression of CD44 was used to evaluate effector Tregs, CD73 was used to evaluate the capacity for metabolic disruption, and CD152 (CTLA4) and CD223 (LAG3) were used to evaluate the capacity for dendritic cell targeted immune modulation.
The frequencies of CD4+ or CD8+ iTregs and nTregs were significantly increased at day 3 DS (p<0.01), while these populations decreased at day 10 DS, relative to controls. CD44hi expression increased following DS only in CD4+ iTregs and was significantly higher than controls by day 10 DS (p=0.006). In addition, both CD4+ iTregs and nTregs showed significantly increased expression of CD73 at day 10 DS compared to controls (p<0.01). Furthermore, evaluation of CD4+ nTregs and iTregs at day 3 DS revealed significant increases in CD152 and CD223 expression compared to controls (p<0.001).
These results indicate that both nTregs and iTregs populations within the cervical lymph nodes increase early following dry eye disease and may elicit their immunosuppressive effects via CD73 generation of adenosine, CTLA4 down-modulation of costimulatory molecules on dendritic cells, and LAG3-mediated inhibition of dendritic cell maturation. Collectively, the data suggests the potential for multiple pathways of immune suppression by Tregs in response to dry eye.
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