Using metagenomics, continuing evidence has elicited how intestinal microbiota trigger distant autoimmunity. Sjögren’s syndrome (SS) is an autoimmune disease that affects the ocular surface, with frequently unmet therapeutic needs requiring new interventions for dry eye management. Current studies also suggest the possible relation of autoimmune dry eye with gut microbiota. Herein, we review the current knowledge of how the gut microbiota interact with the immune system in homeostasis as well as its influence on rheumatic and ocular autoimmune diseases, and compare their characteristics with SS. Both rodent and human studies regarding gut microbiota in SS and environmental dry eye are explored, and the effects of prebiotics and probiotics on dry eye are discussed. Recent clinical studies have commonly observed a correlation between gut dysbiosis and clinical manifestations of SS, while environmental dry eye portrays characteristics in between normal and autoimmune. Moreover, a decrease in both the Firmicutes/Bacteroidetes ratio and genus Faecalibacterium have most commonly been observed in SS subjects. The presumable pathways forming the “gut dysbiosis–ocular surface–lacrimal gland axis” are introduced. This review may provide perspectives into the link between the gut microbiome and dry eye, enhance our understanding of the pathogenesis in autoimmune dry eye, and be useful in the development of future interventions.

Background: This study aimed to investigate the outcome of therapeutic penetrating keratoplasty (TPK) for medically-uncontrolled infectious keratitis, and to determine the factors associated with the recurrence of infection after TPK. Methods: A 10-year retrospective study of medically-uncontrolled infectious keratitis with positive culture results, who received TPK at a tertiary referral center in Korea was performed. Data collection included patient demographics, medical history, pre- and post-operative findings, surgical procedures, causative microorganisms, and visual acuities (VA). The primary outcome measure was the recurrence of infection after TPK, and the factors were compared between patients with and without recurrence. Results: A total of 19 patients (19 eyes) were analyzed, of which 6 eyes (31.6%) had infection recurrence at 21.6 ± 22.84 months after TPK. Recurrence occurred more frequently in the female sex (vs. male, p = 0.013) and in longer duration (>30 days) from infection onset to TPK (vs. ≤30 days, p = 0.025). Final best-corrected-VA was poorer in patients with recurrence than those without (LogMAR 1.60 ± 0.97 vs. 2.40 ± 0.46, p = 0.026). Evisceration was performed in 2 out of 6 patients with recurrence (33.3%), while none was performed in those without recurrence (p = 0.028). Conclusion: Infection recurrence after TPK was 31.6%. Given the poor outcome of TPK in eyes with recurrence, close monitoring and intensive treatment are required post-TPK.

Purpose: The aim of this study was to investigate the efficacy of RCI001 (RCI) in a mouse model of primary Sjögren syndrome. Methods: Eight 12-week-old NOD.B10-H2b mice were used in this study. All experimental animals were randomly divided into phosphate-buffered saline (PBS) and RCI groups in NOD.B10-H2b mice. The eyes of mice were topically treated with PBS or RCI twice a day for a week. Ocular surface staining (OSS) and tear secretion were compared between before and after treatment. The transcript levels of inflammatory cytokines and nicotinamide adenine dinucleotide phosphate oxidase (NOX) in the conjunctiva and cornea (CC) and lacrimal gland were assayed. In addition, immunofluorescence staining of the conjunctiva was assessed. Results: The RCI group showed significant clinical improvement in OSS and tear secretion after 1 week of treatment compared with the baseline (both P < 0.001) and showed better improvement in OSS and tear secretion than the PBS group after 1 week of treatment (both P < 0.05). The levels of IL-1β and IL-17 in CC and IL-6 in the lacrimal gland were also significantly reduced in the RCI group compared with the PBS group (each P < 0.05). Transcript levels of NOX2 and NOX4 were also significantly reduced in CC of the RCI group compared with those of the PBS group (P < 0.05). The RCI group also resulted in lower conjunctival expression of oxidative stress markers (4-hydroxy-2-nonenal, hexanoyl-lysine, and NOX4) than the PBS group. Conclusions: Topical RCI001 demonstrated excellent therapeutic efficacy in a mouse model of primary Sjögren syndrome by inhibiting inflammation and oxidative stress.