Methods: Endophthalmitis was induced in wild type (WT) C57BL/6 and TLR2 KO mice by intravitreal injections of C. albicans. Disease progression was monitored by assessing clinical score, fungal burden, electroretinography (ERG), and retinal tissue damage (H&E staining). Levels of inflammatory cytokines/chemokines were determined using quantitative RT-PCR (qRT-PCR) and ELISA. Flow cytometry was used to assess neutrophil infiltration. TLR2 expression was determined by qRT-PCR and Western blot.
Results: Our dose-response study revealed that 6,500 CFU of C. albicans caused endophthalmitis in WT mice, as evidenced by increased levels of pro-inflammatory cytokines (IL-6, TNF-α, IL-1β) and chemokines (KC and MIP-2) in infected eyes. The time-course studies showed increased fungal burden at 24 and 48 hours post-infection, followed by a decrease at 72 and 96 hours. This coincided with increased PMN infiltration, and retinal tissue damage. Retinal function was reduced in a time-dependent manner, as determined by ERG analysis. qRT-PCR and Western blot analysis of infected eyes showed increased expression of TLR2. A deficiency of TLR2 (TLR2 KO mice) rendered the mice with increased susceptibility towards C. albicans endophthalmitis.
Conclusion: These results indicate that the retina/retinal cells possess the ability to recognize and respond to the fungal pathogens and that TLR2-signaling mediates innate responses to C. albicans.
S. Revankar, Astellas: Investigator , Research grant
Merck: Investigator , Research grant
Gilead: Investigator , Research grant
P. Chandrasekar, Astellas: Speaker's Bureau , Speaker honorarium