Gut Microbiota From Sjögren syndrome Patients Causes Decreased T Regulatory Cells in the Lymphoid Organs and Desiccation-Induced Corneal Barrier Disruption in Mice.

Laura Schaefer,Stephen C Pflugfelder,Cintia S De Paiva,Firas S Midani,Claudia M Trujillo-Vargas,Robert A Britton

doi:10.3389/fmed.2022.852918

Abstract

Sjögren syndrome (SS) is an autoimmune inflammatory disorder characterized by secretory dysfunction in the eye and mouth; in the eye, this results in tear film instability, reduced tear production, and corneal barrier disruption. A growing number of studies show that homeostasis of the ocular surface is impacted by the intestinal microbiome, and several 16S sequencing studies have demonstrated dysbiosis of the intestinal microbiota in SS patients. In this study, we utilized metagenomic sequencing to perform a deeper analysis of the intestinal microbiome using stools collected from sex- and age-matched healthy (n = 20), dry eye (n = 4) and SS (n = 7) subjects. The observed Operational Taxonomic Units (OTUs) and Shannon alpha diversity were significantly decreased in SS compared to healthy controls, and there was a significant inverse correlation between observed OTUs and ocular severity score. We also identified specific bacterial strains that are differentially modulated in SS vs. healthy subjects. To investigate if the differential composition of intestinal microbiome would have an impact on the immune and eye phenotype, we performed functional studies using germ-free mice colonized with human intestinal microbiota from SS patients and healthy controls. Flow cytometry analysis demonstrated reduced frequency of CD4+ FOXP3+ cells in ocular draining cervical lymph nodes (CLN) in mice colonized with SS patient intestinal microbiota 4 weeks post-colonization. We also found that offspring of SS-humanized mice also have fewer CD4+FOXP3+ cells in the CLN as well as spleen, demonstrating vertical transmission. SS-humanized mice subjected to desiccating stress exhibited greater corneal barrier disruption as compared to healthy control humanized mice under the same conditions. Taken together, these data support the hypothesis that the intestinal microbiota can modulate ocular surface health, possibly by influencing development of CD4+ FOXP3+ regulatory T cells (Tregs) in the ocular draining lymph nodes.

Highlights

Sjögren syndrome (SS) is an autoimmune disorder affecting the secretory glands and mucosal tissues of the eye and mouth, including the lacrimal glands and salivary glands, and results in dry eye and dry mouth
In agreement with previously published results using 16S sequencing [10, 13], we observed a decrease in the diversity of SS patient gut microbiota relative to healthy controls that correlates with ocular disease severity
We observed that the decrease in diversity is accompanied by shifts in the composition of the community, with depletion of specific microbes that may be protective of the ocular surface, including several Bacteroides species

Summary

Introduction

Sjögren syndrome (SS) is an autoimmune disorder affecting the secretory glands and mucosal tissues of the eye and mouth, including the lacrimal glands and salivary glands, and results in dry eye and dry mouth. A hallmark of this disease is lymphocyte infiltration of the lacrimal gland, salivary gland, and conjunctiva in the eye. Increased cytokine expression including IFNγ and IL-17 by the infiltrating lymphocytes and activated epithelial cells results in corneal barrier disruption and loss of goblet cells in the conjunctiva [1–4]. A significant body of literature has linked the gut microbiome to development of disease and autoimmunity at distant sites, including the eye [5–9]. Germ-free mice lacking all bacteria spontaneously develop a SS-like syndrome that can be ameliorated by restoring the gut bacteria by fecal material transplant (FMT) [2, 8]

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Results

Conclusion