Abstract
Purpose :
Our previous studies have shown that MCMV disseminates to and remains latent in the choroid and RPE following systemic infection of neonatal BALB/c mice. Latent ocular infection combined with ocular MCMV gene expression induces in situ inflammation and development of retinal degeneration. Caspase-12 plays various roles in innate immune responses and inflammation as well as ER stress-induced cell death. Since caspase-12 is activated during MCMV ocular infection, the purpose of this study was to determine if caspase-12 plays a role in retinal degeneration in aged BALB/c mice following systemic neonatal infection.
Methods :
MCMV (50 pfu per mouse), or medium as control, were injected intraperitoneally (i.p.) into caspase-12−/− (in BALB/c background) and caspase 12+/+ control mice at <3 days after birth. At 8- and 12-months post infection (p.i.), eyes were analyzed by SD-OCT prior to harvest. Eyes and extraocular tissues were collected and analyzed by plaque assay, H & E staining, TUNEL assay, western blot and real time-RT-PCR, as well as immunohistochemical staining.
Results :
No replicating virus was detected in eyes, salivary glands or lungs, although virus DNA was detected in eyes and extraocular tissues of both caspase-12−/− and control mice at both 8 and 12 months p.i. Several MCMV genes were expressed in eyes of some MCMV infected caspase-12−/− and caspase-12+/+ mice, whereas mean retinal thickness was significantly higher in MCMV latently infected aged caspase-12−/− mice compared to eyes of age matched infected caspase-12+/+ mice. Although similar levels of cleaved caspase 1 was detected in eyes of both infected caspase-12−/− and control mice, significantly higher levels of activated NFκB, cleaved caspase 8, MLKL, p-RIP3 and p53 were observed in eyes of infected caspase-12+/+ mice compared to eyes of infected caspase-12-/- mice.
Conclusions :
MCMV disseminates to and remains latent in eyes of caspase-12−/− and caspase-12+/+ control mice following systemic neonatal infection. However, a less severe retinal degeneration was observed in aged, infected caspase-12-/- mice, compared to age-matched infected control mice. Our results suggest that caspase 12 contributes to retinal degeneration during MCMV ocular latency via multiple pathways including apoptosis and necroptosis.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.