Human embryonic lung fibroblasts treated with artesunate exhibit reduced rates of proliferation and human cytomegalovirus infection in vitro

Background: Cytomegalovirus (CMV) pneumonia is a major cause of death in immunosuppressed patients. Despite the effective treatment with ganciclovir (GCV) and other antiviral agents, the mortality rate remains between 30% to 50%. Recently, the anti-malarial drug artesunate (ART) was found to exhibit significant anti-viral activity. Here, we examined the effects of ART on human cytomegalovirus (HCMV) infection and human embryonic lung fibroblast (HELF) proliferation in vitro. Methods: HELFs infected with the GFP-expressing Towne-BAC strain of HCMV were divided into three treatment groups: Group I, cells treated with ART for 1.5 h before HCMV inoculation; Group II, cells infected with HCMV that was pre-treated with ART for 1.5 h before HCMV inoculation; Group III, cells that were treated with ART at 1.5 h post-HCMV inoculation. GFP expression was observed daily by fluorescence microscopy, and the number of GFP-positive cells in each experimental group was recorded at 4-5 days post-infection. At 10 days post-infection, the viability of cells in each group was recorded. GCV treatment was used as a control. Results: While no significant effects on cytotoxicity, cell viability, viral infection rates, or antiviral activity were observed upon treatment of Group I or II cells with GCV or low levels of ART, the ART-treated Group III population exhibited significantly reduced rates of infection at drug concentrations higher than 12.5 mu M. Similarly, we observed a GCV concentration-dependent reduction in the viral infection rate in Group III cells. Notably, ART-treated, but not GCV-treated, cells also exhibited decreased proliferation. The 50% cytostatic concentrations (CC50) and the half maximal inhibitory concentrations (IC50) of ART and GCV were 54.382 mu M and 12.679 mu M, and 3.76 M and 14.479 mu M, respectively. Conclusions: In addition to its robust antiviral activity, ART inhibits proliferation of HCMV-infected lung fibroblasts, making it a potential next-generation drug for CMV pneumonia treatment and for reducing fibroproliferation and fibrosis in these patients.