The glaucoma is a severe ocular pathology which causes the degeneration of retinal ganglion cells, particular nerve cells whose axons form the optic nerve, and afflicts around 70 million people worldwide. The primary open-angle glaucoma (POAG, primary open-angle glaucoma) is the most common form of glaucomaand unfortunately, to date, we do not have much information about the risk factors that may facilitate its occurrence. The traditional approach has identified as the main risk factor the presence of intraocular pressure (IOP, Intraocular pressure) particularly high. However, glaucoma can also occur in individuals who show near-normal IOP levelssuggesting that there are alternative mechanisms that can lead to the onset of this disorder.
Glaucoma and gut microbiota
Our intestine is normally colonised by a multitude of bacteria belonging to different specieswhich form a real 'community' that goes by the name of gut microbiotawhose composition can change considerably from one person to another and throughout our lives. The bacteria that make up the gut microbiota actively participate in numerous processes of fundamental importance for the functioning of our organismsuch as digestion and regulation of immune system function. The dysbiosisi.e. the presence of alterations in the composition of the gut microbiotahas already been shown to be associated with the appearance of numerous inflammatory and autoimmune diseasesas well as to some of the most widespread neurodegenerative diseasesincluding Parkinson's disease, and may also be involved in theonset of POAG. In a recent study, a group of researchers compared the composition of the gut microbiota of 30 healthy subjects with that of 30 POAG patients and found significant differences. In particular, the microbiota of subjects with POAG has a significantly higher amount of Prevotella and E. colitwo bacteria that tend to triggering the inflammatory response by the immune system. In addition, subjects with POAG also show a lack of Megamonas, a 'good' bacterium that in other diseases, such as chronic kidney disease, has been shown to have a protective role towards the organism.
Dysbiosis of the gut microbiota would lead to a imbalance in the balance between pro-inflammatory and anti-inflammatory mechanisms put in place by the immune system, leading to aretinal inflammation resulting in the ganglion cell degeneration retinaland therefore in the glaucoma. In addition, each species of bacterium present within the gut microbiota is characterised by a different metabolismwhich entails the production of specific molecules, called metabolitesinto the bloodstream. DysbiosisTherefore, also changes the type and amount of metabolites circulating in the bloodand some of these molecules, such as citrate, have been shown to play an important role in the onset of glaucoma.
Possible innovations in the treatment of glaucoma
The numerous studies conducted in recent years on the gut microbiota have shown that it plays a crucial role in maintaining the body's health. The bacterial flora that make up the microbiota generate a delicate metabolic balance, the disruption of which could be an important risk factor for the onset of glaucoma. Further studies will be needed to further investigate the association between gut microbiota and glaucoma, but the new information in our possession may open up new and promising avenues for the prevention and treatment of this serious eye disease, which also involve maintaining or possibly restoring a healthy gut bacterial flora.
Source
Gong H. et al., Gut microbiota compositional profile and serum metabolic phenotype in patients with primary open-angle glaucoma. Exp Eye Res. 2020; 107921
Dr. Carmelo Chines
Direttore responsabile
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