Abstract
Purpose :
Previous studies from our lab have implicated the oral microbiome in glaucoma pathophysiology. We have also previously detected bacterial DNA in the retina and optic nerve of toll like receptor 2 and 4 knockout animals subjected to oral lavage with human periodontal pathogens Porphyromonas gingivalis and Fusobacterium nucleatum every two weeks. We wanted to determine whether periodontal bacterial DNA can be detected in the retina and optic nerve of immune-competent mice in this animal model of periodontal disease.
Methods :
C57BL/6 mice 13 weeks of age were subjected to oral lavage with periodontal pathogens P. gingivalis and F. nucleatum together (N=40 animals) after the animals were subjected to 3 days of antibiotic treatment to suppress the existing oral microflora. Infection was achieved by oral lavage after the oral cavities were swabbed with chlorhexidine gluconate rinse (4 days in a row every other week). Animals were sacrificed at either 8 or 16 weeks from the initial infection. Controls included sham infected animals (oral lavage with no periodontal pathogens) and naïve animals (N=30 animals). Upon sacrifice, eyes were enucleated under aseptic conditions and one eye per animal was flash frozen in liquid nitrogen. Upon thawing, eyes were dissected under aseptic conditions and retina, optic nerve head, and a retroocular portion of the optic nerve were isolated and used for DNA extraction. DNA from each of the three tissues was subjected to PCR using primers specific for P. gingivalis and F. nucleatum to determine bacterial DNA presence. Positive controls included serially diluted P. gingivalis and F. nucleatum DNA.
Results :
No P. gingivalis and F. nucleatum DNA was detected in eye tissues of naïve, sham-treated or mice subjected to periodontal pathogen treatments for either 8 or 16 weeks. P. gingivalis and F. nucleatum DNA was detected at a minimum concentration of 4.79e-4 ng/μL and 1.14e-3 ng/μL respectively.
Conclusions :
Immune-competent animals readily clear periodontal pathogen DNA from retina and optic nerve even if such pathogens can gain access to the systemic circulation, although the presence of DNA that is below the threshold of detection cannot be excluded. Whether eyes subjected to glaucomatous IOP elevation may not clear such pathogen DNA as efficiently would require further investigation.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.