Abstract
Purpose :
AMP-activated protein kinase (AMPK) is a critical regulator of fundamental cellular processes such as growth, proliferation, and survival. Previously, using AMPKα knockout mice, we reported their increased susceptibility to endophthalmitis. To dissect the role of AMPK in residential versus infiltrating cells, in this study, we sought to determine the pathobiology of bacterial endophthalmitis in mice lacking AMPKα in myeloid cells.
Methods :
Endophthalmitis was induced in wild-type (WT), C57BL/6, and myeloid deleted AMPKα (LysM AMPKα-/-) mice by intravitreal (IVT) injection of S. aureus strain RN6390 (500 CFU/eye). Disease progression was evaluated by both non-invasive (ophthalmoscopy exam, ERG analysis), and invasive (histology, bacterial burden) methods. In-vitro studies were performed using mouse bone marrow-derived macrophages (BMDMs). Activation of inflammatory mediators was measured using qPCR and ELISA.
Results :
S. aureus endophthalmitis was resolved in WT mice, in contrast, the LysM AMPKα-/- mice showed a time-dependent increase in endophthalmitis severity. The intraocular bacterial burden was significantly higher in LysM AMPKα-/- vs WT mice at 24, 48, and 72h post-infection. The ERG analysis revealed a transient decline in retinal function in WT mice, whereas LysM AMPKα-/- mice exhibited a rapid decline. Analysis of inflammatory mediators showed significantly higher levels of IL-1β, TNF-α, and IL-6 in the eyes of LysM AMPKα-/- mice as compared with WT mice at all-time points. Mechanistically, LysM AMPKα-/- mouse exhibited the inflammatory, M1 phenotype (Cox2, iNos, and IL12p40), whereas the WT mice retina showed the M2 phenotype (Arg1, Ym1, Fizz1, and IL10) during S. aureus-induced endophthalmitis resolution.
Conclusions :
Our findings demonstrated that myeloid-specific AMPKα deficiency impairs the resolution of inflammation in endophthalmitis by skewing to M1 macrophage phenotype. Therefore, therapies directed to restore or enhance AMPK activity could be used to improve visual outcomes in endophthalmitis.
This is a 2021 ARVO Annual Meeting abstract.