Abstract
Purpose :
Increasing incidences of multidrug-resistant infections in endophthalmitis threaten our ability to treat and manage this condition. Host immunity is often-overlooked in the clearance of these infections. We aimed to study the differential host immune response observed during Multidrug-resistant- Pseudomonas aeruginosa (MDR-PA) endophthalmitis by studying their gene expression in a murine model.
Methods :
Exogenous P. aeruginosa endophthalmitis was induced in C57BL/6 mice using clinical isolates of MDR-PA and drug-susceptible Pseudomonas aeruginosa (S-PA). Disease progression was monitored by slit-lamp examination and assigning clinical scores at 6hr and 24hr p.i., following which eyes were enucleated and bacterial burden was estimated. The extent of retinal damage was assessed by H&E and GFAP staining. PMN influx was determined by CD45 and Myeloperoxidase (MPO) staining. Microarray analysis was performed using SuperPrint G3 Mouse Gene Expression v2 chip, and data was analysed using Genespring GX 11.5 software.
Results :
Intravitreal injection of MDR-PA and S-PA at 10,000 cfu, resulted in non-resolving ocular inflammation as evidenced by increased corneal haze, diminished vitreous clarity and red reflex. Higher bacterial load was observed in MDR-PA infected mice at 24h Vs S-PA infected eyes (5.6 x 105 CFU/eye vs 4.2 x 105 CFU/eye), correlating with increased clinical severity in MDR-PA infected eyes (p=0.003). Histological analysis revealed higher CD45-positive cells (p= 0.01), GFAP positive cells (p= 0.05), and MPO-positive cells (p= 0.02) in the retinal layers of the MDR-PA infected mice. Temporal microarray analysis identified 5674 genes that were differentially upregulated in MDR-PA mice and included; IL-6, IL-15, IL-7, IL-1β, NCF-1 and 2, Complement factor B and Pyruvate kinase while IL-9, PDGF- β, Anocatmin-6 and ATP-binding cassette were downregulated. Gene ontology and pathway analysis revealed the involvement of immune cells trafficking, apoptosis, tissue destruction markers, production of reactive oxygen species, and regulation of lipid metabolism.
Conclusions :
Our study demonstrates, for the first time a differential host immune response by MDR-PA compared to S-PA in a mice model of endophthalmitis, and this can be used to identify anti-inflammatory targets for MDR-PA endophthalmitis.
This is a 2021 ARVO Annual Meeting abstract.