Readers’ digest: how gut flora affects the eye

July 16, 2021 Staff reporters

A review of studies whose data indicate a gut-eye axis – where the intestine’s microbiome influences eye health – has stated that a specific diet, in some cases including pre- and probiotics, could improve the outcomes of certain eye conditions. 


Led by Professor Pasquale Napolitano, University of Molise, Italy, the review’s authors said that intestinal microbiota appears to be essential in propagating inflammatory diseases of the eye and could represent a potential target for further approaches in the treatment of severe and chronic ocular conditions. Manipulation of the gut microbiome has been shown to influence the course of ocular diseases, they said.  


Among the examples cited was Lactobacillus’ ability to decrease the number of neutrophil extracellular traps, and B. fragilis showing protective effects against autoimmune diseases through its polysaccharide capsule. Further, two variants of bacteria have been reported to be associated with primary open-angle glaucoma and alterations of the intestinal bacterial flora, particularly with respect to the relative abundances of Bacteroides and Prevotella, said researchers. 


Prebiotics (short-chain carbohydrates) have shown a positive influence in restructuring gut immunity and gut barrier function. Their combined use with probiotics (live microbial components) increases the modulation of gut immunity, said the review’s authors. “Oral probiotic supplementation has a favourable influence on the clinical course of one of the most common eye disorders, at least for small lesions, without inducing noteworthy complications. In our previous study we found that supplementation with probiotics is a safe and effective therapy for reducing chalaziosis recurrence,” they said. 


Other studies demonstrated that germ-free CD25 knockout mice improved their dry eye symptoms after a faecal microbiota transplant (FMT), where faeces from a healthy subject is used to ‘seed’ gut flora in an individual with a depleted microbiota. 


The authors concluded by saying that, “Additional consideration should be given to several therapeutic strategies targeting gut microbiota for the treatment of ocular disease. One of the proposed approaches is targeting the causative bacteria, in an effort to use more specific antibiotics or designed immunoglobulins that target individual causative bacteria.”  


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