Impact of aging on endophthalmitis

Endophthalmitis is a serious complication of cataract surgery, for the aging population, and is associated with irreversible vision loss and its effect in endophthalmitis has not been fully elucidated. This study aimed to understand the pathobiology of bacterial endophthalmitis in association with age in a murine model as well as in patients with bacterial-endophthalmitis. Bacterial endophthalmitis was induced in aged and young (18-24 months and 6-8 weeks old) C57BL/6 mice, by intravitreal injection of Pseudomonas aeruginosa, followed by assessment of disease progression and enucleation at 24 h post-infection. Eyes were subjected to histopathological analysis along with assessment of inflammatory mediator levels by qPCR. Additionally, these cytokines were further validated in 10 patients with bacterial endophthalmitis, by MILLIPLEX assay, and correlated with their age. Both young and old mice were equally susceptible to P. aeruginosa infection, older mice exhibited higher clinical scores along with increased bacterial burden and inflammation, indicating enhanced disease severity. These findings were confirmed in human vitreous. Immune exacerbation was seen in older mice possibly due to inflammaging, during infection. Identification of pathways underlying altered innate immunity in aging eyes could provide new understandings into the pathology of bacterial endophthalmitis in older patients.