Modulation of Oral Immunity by Viral MicroRNA: Impact on Macrophage & Epithelial Cell MicroRNA Expression

MicroRNAs (miRNAs) are small, 18-25 nucleotide non-coding RNAs. They They bind to 3’UTRs of target mRNA to regulate gene expression to causing translational silencing and destabilization of mRNA. miRNAs are required for normal immune development and function. When there is aberrant expression of miRNAs, there dysregulated innate and adaptive immune responses. Viral miRNAs (v-miRs) have been identified in a number of human viruses. This study focused on vmiRs from herpes simplex virus-1 (HSV-1), human cytomegalovirus (HCMV), and Kapsosi Sarcoma humanvirus (KSHV). This is an in-vitro study to investigate the relationship between vmiRs derived from HCMV, KSHV, and HSV-1 and host miRNA from human macrophages (Mφ) and human gingival epithelial cells (HGEC). We hypothesize these vmiRs will target host miRNAs directly related to inflammation and pathogenesis. We would like to identify host and vmiRs that are expressed or repressed by this interaction. We isolated and differentiated Mφ and HGECs. We preformed transfections with three viral mimics: K12-3-3p (KSHV), miR-H1 (HSV-1), and UL-70-3p (HCMV). The total RNA was isolated and miRNA profiling was preformed using Exiqon Services using 7th generation microarrays. We found that there is altered expression of several cellular miRNAs in both HGEC and Mφ transfected with miR-H1 and miR-K12-3-3p. However, for miR-UL70-3p, very few miRNAs were impacted significantly. We found that the overexpression of vmiRs alter the expression of cellular miRNAs. These cellular miRNAs were predicted to regulate numerous cellular pathways related, but not limited to cell movement, signaling pathways, endocytosis, cell survival and proliferation, etc. We found the expression of miR-K12-3-3p can interfere with the cell migration in HGECs. We also found that phagocytosis and cytokine secretion was monitored in Mφ transfected vmiRs miR-H1- and miR-K12-3-3p-mediated inhibition the both processes. Finally, we identified and confirmed two novel target of vmiRs showing miR-UL-70-3p and miR-K12-3-3p directly bind to the 3′UTR of MMP-24 and FOS, respectively. Our findings show that vmiRs can subvert the hosts’ innate imune responses.