Evaluating the role of tissue microRNA-27b as a diagnostic marker for oral lichen planus and possible correlation with CD8

The Functional Mechanism of MicroRNA in Oral Lichen Planus

Non-coding RNAs (ncRNAs) are transcribed from the genomes of mammals and other complex organisms, and many of them are alternately spliced and processed into smaller products. Types of ncRNAs include microRNAs (miRNAs), circular RNAs, and long ncRNAs. miRNAs are about 21 nucleotides long and form a broad class of post-transcriptional regulators of gene expression that affect numerous developmental and physiological processes in eukaryotes. They usually act as negative regulators of mRNA expression through complementary binding sequences in the 3’-UTR of the target mRNA, leading to translation inhibition and target degradation. In recent years, the importance of ncRNA in oral lichen planus (OLP), particularly miRNA, has attracted extensive attention. However, the biological functions of miRNAs and their mechanisms in OLP are still unclear. In this review, we discuss the role and function of miRNAs in OLP, and we also describe their potential functional roles as biomarkers for the diagnosis of OLP. MiRNAs are promising new therapeutic targets, but more work is needed to understand their biological functions.

Extracellular vesicles from the inflammatory microenvironment regulate the osteogenic and odontogenic differentiation of periodontal ligament stem cells by miR-758-5p/LMBR1/BMP2/4 axis

Background

Extracellular vesicles (EVs) play a key role in constructing a microenvironment that favors the differentiation of stem cells. The present work aimed to determine the molecular mechanisms by which EV derived from inflammatory dental pulp stem cell (iDPSC-EV) influence periodontal ligament stem cells (PDLSCs) and provide a potential strategy for bone and dental pulp regeneration.

Methods

The osteogenic and odontogenic differentiation was assessed by quantitative real-time polymerase chain reaction (qRT-PCR), western blot, alkaline phosphatase (ALP) activity assay, ALP staining, alizarin red S (ARS) staining, and immunofluorescence staining. To detect proliferation, the Cell Counting Kit-8 (CCK-8) assay, and flow cytometry analysis were used. EVs were isolated by the Exoperfect kit and ultrafiltration and characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blot. The expression profile of miRNAs in EVs was studied using miRNA sequence and bioinformatics, and one of the upregulated miRNAs was evaluated on PDLSCs.

Results

The inflammatory microenvironment stimulated osteogenic and odontogenic differentiation of DPSCs and iDPSC-EV behaved alike on PDLSCs. MiR-758-5p was upregulated in iDPSC-EV and was demonstrated to play a significant role in the osteogenic and odontogenic commitment of PDLSCs. A dual-luciferase reporter assay confirmed the binding site between miR-758-5p and limb development membrane protein 1 (LMBR1). The knockdown of LMBR1 also enhanced the above potential. Mechanically, bone morphogenetic protein (BMP) signaling was activated.

Conclusions

EVs from the inflammatory microenvironment enhanced the osteogenic and odontogenic differentiation of PDLSCs partly by shuttering LMBR1-targeting miR-758-5p via BMP signaling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03412-9.

Vitamin D/VDR signaling induces miR-27a/b expression in oral lichen planus

MicroRNA-27a/b are small non-coding RNAs which are reported to regulate inflammatory response and cell proliferation. Although some studies have demonstrated that miR-27b is down-regulated in the oral specimens of patients suffering with oral lichen planus (OLP), the molecular mechanism of miR-27b decrease remains a large mystery, and the expression of miR-27a in OLP is not well explored. Here, we demonstrated both miR-27a and miR-27b, compared with healthy controls, were reduced in the oral biopsies, serum and saliva samples derived from OLP patients. The reductions of miR-27a/b were also confirmed in the lipopolysaccharide (LPS)- or activated CD4⁺ T cell-treated human oral keratinocytes (HOKs). Furthermore, we found vitamin D receptor (VDR) binding sites in the promoters of miR-27a/b genes and verified this finding. We also tested miR-27a/b levels in the oral epithelium from paricalcitol-treated, vitamin D deficient or VDR knockout mice. In the rescue experiments, we confirmed vitamin D and VDR inhibited LPS- or activated CD4⁺ T cell-induced miR-27a/b reductions in HOKs. In sum, our results show that vitamin D/VDR signaling induces miR-27a/b in oral lichen planus.

Association of MAPK and its regulatory miRNAs (603, 4301, 8485, and 4731) with the malignant transformation of oral lichen planus

Oral lichen planus (OLP) is a potentially malignant oral lesion that may transform into oral squamous cell carcinoma (OSCC). The purpose of this study was to assess the level of expression of MAPK/ERK1/2 gene, and microRNA (miR)-603, 4301, 8485, and 4731 in the MAPK signaling pathway in OLP and OSCC lesions. This case-control study evaluated 26 OSCC, 20 OLP and 20 healthy control tissue specimens. After RNA extraction, the respective miRNA and MAPK/ERK1/2 mRNA levels were assessed by quantitative reverse transcription polymerase chain reaction (RT-PCR). Significant upregulation of MAPK/ERK1/2 gene was noted in the OLP and OSCC specimens compared with healthy controls (p < 0.001). The expression level of miR-4731 was significantly lower in the OLP and OSCC specimens than in the healthy specimens (p < 0.001). The expression of MiR-603 was the lowest in OLP, followed by OSCC and then the control group (p < 0.001). No significant difference was found in miR-4801 levels between OSCC and OLP specimens compared with healthy controls (p = 0.43 and p = 0.86, respectively). In addition, a non-significant decrease in miR-8485 levels was noted in the OSCC and OLP specimens compared with healthy controls (p = 0.98 and p = 0.61, respectively). A significant decrease in level of miR-603 was noted in OLP compared with OSCC group (p < 0.001). The miR-4801 and miR-8485 expression levels were directly correlated with MAPK/ERK1/2 mRNA expression (p = 0.01). Higher expression level of MAPK/ERK1/2, miR-603, miR-4801, and miR-4731, and lower expression level of miR-8485 were correlated with significantly lower overall survival rate in OSCC patients. The increased expression of MAPK/ERK1/2 and decreased expression of miR-603 and miR-4731 are associated with greater risk of OLP malignant transformation and poor histopathological characteristics of OSCC.