tricin and Cytomegalovirus-Infections

Treatment of human embryonic lung fibroblast (HEL) cells with tricin (4', 5, 7-trihydroxy-3', 5'-dimethoxyflavone) following infection with human cytomegalovirus (HCMV) reportedly significantly suppresses HCMV replication. In the present work, the mechanisms for the anti-HCMV effects of tricin in HEL cells were examined. It was found that exposure of HEL cells to tricin inhibited HCMV replication, with concomitant decreases in amounts of transcripts of the CC chemokine RANTES (CCL5)-encoding gene and in expression of the CCL5 protein. It was also found that transcripts of HCMV immediate early 1 (IE1), and HCMV UL54 (encoding DNA polymerase) and replication of HCMV was significantly lower in CCL5 gene-knockdown cells. These results suggest that the anti-HCMV activity of tricin differs from that of ganciclovir and that CCL5 is one of the chemokines involved in HCMV replication. In addition, it is possible that chemokine CCL5 is one of the targets of tricin.

Topics: Antiviral Agents; Cell Line; Chemokine CCL5; Cytomegalovirus; Cytomegalovirus Infections; DNA Replication; DNA-Directed DNA Polymerase; Fibroblasts; Flavonoids; Ganciclovir; Gene Expression; Gene Knockdown Techniques; Gene Silencing; Humans; Immediate-Early Proteins; RNA, Small Interfering; Transfection; Viral Proteins; Virus Replication

We previously reported that treatment with tricin (4',5,7-trihydroxy-3',5'-dimethoxyflavone) after human cytomegalovirus (HCMV) infection significantly suppressed both infectious virion production and HCMV replication in human embryonic lung fibroblast (HEL) cells. Moreover, we recently demonstrated that HCMV infection can increase the expression of CC-motif ligand 2 (CCL2/MCP-1) and of CCR2, a CCL2-specific receptor, effects that can in turn enhance HCMV infection and replication. Hence, we here examined whether the CCL2-CCR2 axis is involved in the anti-HCMV effects of tricin in HEL cells. Tricin exposure yielded dose-dependent decreases in the accumulation of transcripts for the HCMV immediate early gene and the DNA polymerase gene in HCMV-infected cells, along with decreased production of infectious HCMV. Concomitantly, tricin caused dose-dependent attenuation of HCMV infection-induced up-regulation of expression of CCL2 and CCR2 mRNAs and of CCL2 protein. Moreover, CCL2 reversed tricin-mediated inhibition of HCMV virion production in a dose-dependent manner. Thus, tricin appears to exert anti-HCMV activity by depressing CCL2 expression.

Topics: Antiviral Agents; Cell Line; Chemokine CCL2; Cytomegalovirus; Cytomegalovirus Infections; DNA-Directed DNA Polymerase; Fibroblasts; Flavonoids; Gene Expression Regulation, Viral; Host-Pathogen Interactions; Humans; Immediate-Early Proteins; Receptors, CCR2; Viral Proteins; Virus Replication

It has been demonstrated as the first report that combination treatment with ganciclovir (GCV) and tricin (4',5,7-trihydroxy-3',5' -dimethoxyflavone), a derivative of Sasa albo-marginata, after human cytomegalovirus (HCMV) infection has synergistic effects on both infectious virus production and HCMV DNA synthesis in the human embryonic fibroblast cell line MRC-5. In this paper, we examined the anti-HCMV effects of GCV plus various concentrations of tricin, and tricin plus various concentrations of GCV in MRC-5 cells. We found that expression of the HCMV UL54 gene was significantly inhibited by combination of GCV with tricin when compared with GCV mono-treatment. These results suggest that tricin is a novel compound for combination therapy with GCV against HCMV replication. In addition, reduced-dose combination therapy may provide a direction for treatment in patients with HCMV infection while reducing drug toxicity.

Topics: Antiviral Agents; Cell Line; Cytomegalovirus; Cytomegalovirus Infections; DNA Replication; DNA-Directed DNA Polymerase; Drug Synergism; Drug Therapy, Combination; Fibroblasts; Flavonoids; Ganciclovir; Gene Expression; Humans; Male; Sasa; Viral Proteins; Virus Replication

The anti-human cytomegalovirus (HCMV) activity of tricin (4',5,7-trihydroxy-3',5'-dimethoxyflavone), a derivative from Sasa albo-marginata, was studied in the human embryonic fibroblast cell line MRC-5. In a plaque assay, tricin and ganciclovir (GCV) showed concentration-dependent inhibitory properties from 0.05 to 3.6 μM and 0.01 to 1.0 μM, respectively. Tricin had no virucidal effects on cell-free HCMV. Treatment with tricin 1h before, or 1h or 3h after viral infection significantly suppressed HCMV replication. Moreover, tricin inhibited the expression of immediate early (IE) 2 mRNA and DNA polymerase (UL54) mRNA in HCMV-infected cells. Western blot analysis also demonstrated that tricin decreased the expression of IE antigen (especially IE2) and cyclooxygenase 2 (COX-2) expression in HCMV-infected cells. In the presence of tricin, prostaglandin E2 (PGE2) accumulation by HCMV infection was completely inhibited. These results suggest that tricin is a novel compound with potential COX inhibitor-dependent anti-HCMV activity.

Topics: Antiviral Agents; Blotting, Western; Cell Line; Cyclooxygenase 2; Cytomegalovirus; Cytomegalovirus Infections; Dinoprostone; DNA-Directed DNA Polymerase; DNA, Viral; Fibroblasts; Flavonoids; Ganciclovir; Humans; Immediate-Early Proteins; Nucleic Acid Synthesis Inhibitors; Reverse Transcriptase Polymerase Chain Reaction; Sasa; Virus Replication