A Review of the Impact of Alterations in Gut Microbiome on the Immunopathogenesis of Ocular Diseases

Abstract

Recent studies have highlighted the association between ocular diseases and microbiota profiles of the host intestinal tract and oral cavity. There is mounting evidence supporting the existence of a ‘gut–eye axis’, whereby changes in gut microbiome alter host immunity, with consequential implications for ocular health and disease. In this review, we examined recent published findings on the association between gut microbiome and ocular morbidity, based on 25 original articles published between 2011 to 2020. The review included both clinical and in vivo animal studies, with particular focus on the influence of the microbiome on host immunity and metabolism. Significant associations between altered intestinal microbiome and specific ocular diseases and pathological processes, including Behçet’s syndrome, autoimmune uveitis, age-related macular degeneration, choroidal neovascularization, bacterial keratitis, and Sjögren-like lacrimal keratoconjunctivitis have been demonstrated. Furthermore, alterations in the gut microbiome resulted in quantifiable changes in the host immune response, suggesting immunopathogenesis as the basis for the link between intestinal dysbiosis and ocular disease. We also examined and compared different techniques used in the identification and quantification of gut microorganisms. With our enhanced understanding of the potential role of gut commensals in ophthalmic disease, the stage is set for further studies on the underlying mechanisms linking the gut microbiome, the host immune response, and the pathogenesis of ophthalmic disease.

New Understanding of Diagnosis, Treatment and Prevention of Endometriosis

“…The mechanism of the association of endometriosis with a wide range of other symptoms, such as depression, lower BMI, autoimmune diseases, allergies, etc., are not clear. However, considering the recently observed associations between the intestinal microbiome and a whole range of effects on the brain, immunology, and rheumatoid arthritis it is attractive to speculate that many of these associations with endometriosis might also find their origin in hereditary factors increasing the risk of endometriosis and changing the bowel microbiota as reviewed in 42 articles in 2021 only [ 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]). The association with sexual dysfunction seems to be caused by the pain, which is a strong inhibitor of sexuality [ 61 , 62 , 63 , 64 ].…”

The Gut–Eye Axis: Correlation Between the Gut Microbiota and Autoimmune Dry Eye in Individuals With Sjögren Syndrome

“…43 Probiotics are living microorganisms that confer beneficial effects on the host organism by competing with potential pathogens or gut commensals and can be used as biotherapy to induce tolerance or modification of the immune system, 44,45 in particular, which are crucial to maintain ocular immune homeostasis and regulate autoimmune dry eye. 46 Recent animal studies of dry eye and probiotics have generally observed that antibiotic treatment increases the risk of dry eye, whereas probiotics can provide clinical benefits to dry eye by reducing inflammatory cell production. Kawashima et al 47 indicated that Enterococcus faecium WB2000 mixed with fish oil increased tear secretion and decreased reactive oxygen species production in lacrimal glands of desiccating-stressed rats.…”

Consumption of Limosilactobacillus fermentum Inhibits Corneal Damage and Inflammation in Dry Eye Disease Mouse Model through Regulating the Gut Microbiome

“…For instance, certain symbiotic bacteria, such as Bifidobacterium, can prevent colonization of pathogenic bacteria by reducing the intestinal pH [ 23 ]. Also, with the recent enhanced understanding of the important role of the gut microbiome, there are researches on the relationship of host inflammation response and the pathogenesis of ocular diseases [ 24 ]. Recent studies have reported an association between ocular diseases and the microbiota profile of the host intestine.…”