Viral miRNAs Alter Host Cell miRNA Profiles and Modulate Innate Immune Responses

Abstract

Prevalence of the members of herpesvirus family in oral inflammatory diseases is increasingly acknowledged suggesting their likely role as an etiological factor. However, the underlying mechanisms remain obscure. In our recent miRNA profiling of healthy and diseased human tooth pulps, elevated expression of human herpesvirus encoded viral microRNAs (v-miRs) were identified. Based on the fold induction and significance values, we selected three v-miRs namely miR-K12-3-3p [Kaposi sarcoma-associated virus (KSHV)], miR-H1 [herpes simplex virus 1 (HSV1)], and miR-UL-70-3p [human cytomegalovirus (HCMV)] to further examine their impact on host cellular functions. We examined their impact on cellular miRNA profiles of primary human oral keratinocytes (HOK). Our results show differential expression of several host miRNAs in v-miR-transfected HOK. High levels of v-miRs were detected in exosomes derived from v-miR transfected HOK as well as the KSHV-infected cell lines. We show that HOK-derived exosomes release their contents into macrophages (Mφ) and alter expression of endogenous miRNAs. Concurrent expression analysis of precursor (pre)-miRNA and mature miRNA suggest transcriptional or posttranscriptional impact of v-miRs on the cellular miRNAs. Employing bioinformatics, we predicted several pathways targeted by deregulated cellular miRNAs that include cytoskeletal organization, endocytosis, and cellular signaling. We validated three novel targets of miR-K12-3-3p and miR-H1 that are involved in endocytic and intracellular trafficking pathways. To evaluate the functional consequence of this regulation, we performed phagocytic uptake of labeled bacteria and noticed significant attenuation in miR-H1 and miR-K12-3-3p but not miR-UL70-3p transfected primary human Mφ. Multiple cytokine analysis of E. coli challenged Mφ revealed marked reduction of secreted cytokine levels with important roles in innate and adaptive immune responses suggesting a role of v-miRs in immune subversion. Our findings reveal that oral disease associated v-miRs can dysregulate functions of key host cells that shape oral mucosal immunity thus exacerbating disease severity and progression.

Altered human cytomegalovirus-encoded miRNAs in host circulation: novel disease biomarkers and potential aetiological agents

“…Interestingly, another contemporaneous study confirmed that exosomes released from NPC cells can enter into many types of host cells including epithelial, endothelial, and fibroblast cells, and modulating the tumor microenvironment to influence the cells growth by activating the ERK and AKT signaling pathways [97]. Besides EBV miRNAs, other herpesvirus miRNAs such as KSHV-encoded miRNAs were also observed in exosomes which were derived from KSHV positive cell lines and malignancies [19,98,99]. Moreover, following mechanism study revealed that KSHV-positive cells specifically deliver the KSHV-encoded miRNAs to neighboring cells through exosomes.…”

Dysregulation of human miRNAs and increased prevalence of HHV miRNAs in obese periodontitis subjects

“…Additionally, similar to cellular miRNAs, viral miRNAs can also posttranscriptionally regulate numerous host genes. We recently showed that viral miRNAs can alter expression of both host mRNAs and miR-NAs in v-miR expressing oral keratinocytes and myeloid cells (macrophages) (Naqvi, Seal, Shango, Brambila, et al, 2018;Naqvi, Seal, Shango, Shukla, et al, 2018;Naqvi, Shango, Seal, Shukla, & Nares, 2018a). These widespread v-miR-mediated transcriptome changes can affect numerous cellular functions including immune responses, phagocytosis and cell migration.…”

MicroRNAs expressed by human cytomegalovirus

“…According to a recent report, HCMV expresses miR-UL70-3p and miR-UL148D to target the apoptotic genes MOAP1, ERN1, and PHAP1 and to inhibit mitochondriainduced apoptosis aa well as the antiviral mechanism [29]. Besides, miR-UL70-3p may regulate focal adhesions, gap junctions, MAPK signaling, and the Erb pathway, thus affecting epithelial cell migration and adhesion [70]. Another recent report has discovered 14 mature HCMV miRNAs in infected human lung fibroblasts, including miR-UL70-5p, indicating that HCMV virions and dense bodies carry miRNAs (such as miR-UL70-5p) which can be delivered to cells to affect cellular processes [71].…”