Abstract
Purpose :
We are investigating the effects of the gut microbiota on immune homeostasis at the ocular surface and on ocular pathophysiology in Sjogren Syndrome.
Methods :
4-week-old female germ-free C57BL/6 mice were individually humanized with stools from either healthy donors or SS patients (n = 5 donors per group). Flow cytometry analysis investigated the frequency of CD4+FoxP3+ cells in ocular draining nodes, spleens, intestinal lamina propria and mesenteric lymph nodes 4 weeks post-humanization. A separate group of germ-free mice after humanization with SS and healthy donors were mated to established humanized colonies. Humanized mice (n = 3 different donors per group) were subjected to the standard desiccating stress for 5 days. Uptake of Oregon-Green-Dextran (OGD) dye was used to evaluate corneal barrier function after desiccating stress. Data analysis was performed after combining the results from individual subjects.
Results :
We observed a consistent decrease in the percentages of CD4+FoxP3+ lymphocytes in the eye draining lymph nodes in the SS humanized mice compared to healthy donors (11.6±5 vs 15.8±4.6% of the total leukocytes, n=19 mice/group, p=0.01 unpaired t test). This finding was recapitulated in the offspring of the humanized colonies, in which we also observed the same phenomenon in the spleen and mediastinal lymph nodes, indicating that this effect has vertical transmission. Following exposure to desiccating stress for 5 days, we observed significant disruption of corneal barrier function in SS-humanized mice compared to healthy donors.
Conclusions :
These findings suggest that the gut microbiota influences the proper development of T regulatory cells in draining lymph nodes of mucosal surfaces, such as the eye. They also suggest that the bacterial communities from Sjogren Syndrome patients are less protective of the ocular surface against desiccating environmental stress, as SS-humanized mice had worse corneal barrier function.
This is a 2021 ARVO Annual Meeting abstract.