Abstract
Purpose: :
CD46 is a complement regulatory protein located on the basal surface of the retinal pigment epithelium, and the complement system, which is part of innate immunity, has been implicated in the pathogenesis of age-related macular degeneration (AMD). Several infectious pathogens are known to use CD46 as receptor to infect cells, including measles virus and adenoviruses (Group B, serotype 3, 5, 11 and 35). The purpose of this study is to determine whether infection of the RPE with a CD-46 specific pathogen in tissue culture can lead to cell death, which is seen in advanced AMD.
Methods: :
Human ARPE19 cells were cultured to 70% confluence. Full length open reading frame CD46 (CD46ORF) and CD46 shRNAmir in pLOC and pGIPZ vectors were packaged into lentivirus respectively. Lentiviral-CD46ORF or Lentiviral CD46-shRNAmir was used to over express or knock down the expression level of CD46 in ARPE19 for 72 hours. Non-silencing lentiviral shRNAmir served as a transduction control. HAdV3 (dilution from 1:106.2 to 1013.2 from the viral stock with an original titer 10(5.5)TCID[50]/0.2ml were then introduced into culture dishes. Cell morphology, immunocytochemistry and Western blots were used to monitor HAdV3 infection, CD46 over expression or knockdown effects. Promega’s Cell Titer 96 Aqueous Cell Proliferation Assay was used for monitor ARPE19 viability.
Results: :
95% ARPE19 were shown positive tracking turboGFP at 72 hours after lentiviral CD46ORF or CD46-shRNAmir transduction. CD46 protein over expression or knockdown in ARPE19 was confirmed through immunocytochemistry and Western blot using a commercially available anti-CD46 antibody. ARPE19 cells appeared swollen after 96 hour HAdV3 infection and caused cell death in a dose dependent fashion. At day 4 the TCID[50] (median tissue culture infective dosage) for ARPE19 without CD46ORF was 1:107.5; over-expression of CD46 increased the TCID[50] dilution titer to 1:108.3. The same viral load caused 29.8+/-1.3 % more RPE cell death in CD46-overexpressed ARPE19 versus controls. Phase contrast microscope shows CD46-shRNAmir knockdown protects ARPE19 from HAdV3 induced cell death; CD46-overexpression increases cell death.
Conclusions: :
The results suggest that adenovirus-3 infection is capable of inducing RPE cell death in tissue culture, and that CD46 may play an important role in modulating infection/death of RPE. To our knowledge this is the first report that adenovirus infection causes RPE cell death mediated by CD46. The potential role of adenoviruses and other infectious pathogens in the death of RPE remains to be elucidated.
Keywords: adenovirus • retinal pigment epithelium • cell survival