Autophagy protects against retinal cell death in mouse model of cytomegalovirus retinitis

Juan Mo; Sally S Atherton; Liya Wang; Susu Liu

doi:10.1186/s12886-019-1141-y

Autophagy protects against retinal cell death in mouse model of cytomegalovirus retinitis

BMC Ophthalmol. 2019 Jul 10;19(1):146. doi: 10.1186/s12886-019-1141-y.

Authors

Juan Mo^{1

2}, Sally S Atherton³, Liya Wang⁴, Susu Liu⁴

Affiliations

¹ Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450003, People's Republic of China. mojuan52@gmail.com.
² Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA. mojuan52@gmail.com.
³ Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.
⁴ Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450003, People's Republic of China.

Abstract

Background: Extensive death of uninfected bystander neuronal cells is an important component of the pathogenesis of cytomegalovirus retinitis (CMV). Our previous results have shown that there is a functional relationship between autophagy and apoptosis during MCMV infection of retinal pigment epithelium (RPE). The purpose of this study was to determine whether autophagy plays a significant role in the death of retinal cells during MCMV retinitis.

Methods: The retinas of adult BALB/c mice were infected with MCMV via supraciliary injection. Rapamycin, a mTOR inhibitor, was injected to MCMV-infected BALB/c mice intraperitoneally. Immunohistochemistry and western blot were performed to observe the spread pattern of virus in retinas and the levels of targeted proteins. Plaque assay was performed to determine the virus titer in different groups. Since Atg5 is a key gene regulating autophagy, we bred Atg5^flox/flox; Nestin-Cre mice to deeply elucidate the role of autophagy during MCMV retinitis. Atg5^flox/flox; Nestin-Cre mice were genotyped and infected with MCMV. Immunohistochemistry was performed to observe the type of virus-infected cells and apoptosis in retinas during MCMV retinitis.

Results: In MCMV mouse model, MCMV infection in outer nuclear layer (ONL) and inner nuclear layer (INL) in the retinas caused cleaved caspase 3 positive apoptosis, which is not co-localized with early antigen (EA) positive virus infected cells in rapamycin treated group. Rapamycin treatment increased the levels of LC3B-II by inhibiting mTOR and decreased the levels of cleaved caspase-3 during MCMV retinitis. However, virus propagation was not affected by rapamycin. In Atg5^flox/flox; Nestin-Cre mice, RPE and glial cells were the main targets of viral infection, and number of EA positive retinal cells and TUNEL positive retinal cells was significantly increased compared to Atg5^flox/+; Nestin-Cre mice though there was no difference of virus propagation between Atg5^flox/flox; Nestin-Cre mice and Atg5^flox/+; Nestin-Cre mice.

Conclusions: Autophagy protects retinal cells from MCMV infection induced apoptosis through mTOR-mediated signaling pathway.

Keywords: Autophagy; Murine cytomegalovirus; Retinal cell death; Retinitis.

MeSH terms

Animals
Apoptosis*
Autophagy
Blotting, Western
Cell Death
Cytomegalovirus Retinitis / pathology*
Disease Models, Animal
Eye Infections, Viral / pathology*
Female
Immunohistochemistry
In Situ Nick-End Labeling
Mice
Mice, Inbred BALB C
Retinal Pigment Epithelium / pathology*

Grants and funding

U1504812/National Natural Science Foundation of China