Nanosponges used to combat eye infection

Consisting of a polymeric nanoparticle core surrounded by a natural red blood cell mbrane, the engineered nanosponges have been used in animal models to protect eyes from infections caused by Enterococcus faecalis. E. faecalis contain a toxin called cytolysin, which is found in roughly 50% of isolates that cause post-operative intraocular infections seen in the US.The nanosponges work by irreversibly binding to pore-forming toxins, preventing th from acting on their normal target cell. Lead investigator and ophthalmologist Dr Michelle Callegan said current therapeutic strategies don’t really address the issue, which is why new methods are needed.“We use antibiotics that can kill the organisms, and we use anti-inflammatory agents like corticosteroids, which may or may not help with inflammation, but we don’t really have a good strategy for targeting toxins,” she explained.{{quote-A:R-W:450-I:2-Q: The nanosponges provided some protection for the retina, and that was very exciting. If this all pans out, you could conceivably see this as a therapeutic for patients -WHO:Dr Michelle Callegan, Lead investigator and ophthalmologist}}After successful in vitro experiments, Callegan’s team injected nanosponge pre-treated supernatant that contained the cytolysin into mouse eyes and showed that the engineered nanosponges were able to neutralise cytolysin and prevent damage to the eye.Further experiments donstrated that injecting the nanosponges into the vitreous six hours following infection with a wild type cytolysin-producing strain also protected the retina from damage.“When we treated the infected mouse eyes with the nanosponges, the retinal function in these eyes was actually preserved to a significant degree. When we didn’t treat, the retinal function was completely lost,” Callegan said.“The nanosponges provided some protection for the retina, and that was very exciting. If this all pans out, you could conceivably see this as a therapeutic for patients as they are treated with antibiotics before and during ocular surgery, or immediately after ocular trauma.”However, Callegan also cautioned that there was still work to be done before that eventuates.“We have many more experiments to do. We are in the process of testing the ability of these nanosponges to treat infections with other Gram-positive ocular pathogens that produce pore-forming toxins,” she said, adding they will also test adjunct therapy with nanosponges and antibiotics in eye infection models.The research was published in mSphere, an open-access journal of the American Society for Microbiology.