Differential expression of miRNA-769-5p and Smad2 in patients with or without oral cGVHD.

Background: Oral chronic graft-versus-host disease (cGVHD) impacts quality of life of patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, its precise pathogenesis remains unknown, with potential associations with differential microRNA (miRNA) expression and the TGF-â/Smad signaling pathway.

Objectives: This study aims to explore miRNA expression profiles in the peripheral blood of oral cGVHD patients, focusing on miRNA-769-5p and its relationship with Smad2.

Material And Methods: Peripheral venous blood samples were collected for RNA extraction from 8 patients with oral cGVHD, 8 patients without cGVHD and 8 participants from the healthy control group. The miRNA library was constructed using the Illumina Hiseq 2500 platform. We focused on identifying miRNAs associated with the TGF-â/Smad signaling pathway and subsequently conducted validation experiments. The oral cGVHD and without cGVHD groups were each expanded to include 15 individuals. Peripheral blood samples were subjected to polymerase chain reaction (PCR) analysis to assess miRNA levels and to evaluate Smad2 mRNA levels in peripheral blood mononuclear cells (PBMC). Additionally, enzyme-linked immunosorbent assay (ELISA) was conducted to determine the Smad2 protein levels in peripheral blood.

Results: The most significantly differentially expressed miRNAs among the 3 groups were miRNA-505-5p and miRNA-769-5p. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated an enrichment of the target genes of miRNA-769-5p in the TGF-â signaling pathway. It was observed that miRNA-769-5p expression was higher in patients without oral cGVHD in comparison to those with oral cGVHD. Receiver operating characteristic (ROC) analysis demonstrated that miRNA-769-5p holds diagnostic value for oral cGVHD. As a target of miRNA-769-5p, Smad2 mRNA exhibited a negative correlation with it. Moreover, both Smad2 mRNA and protein levels were higher in patients with oral cGVHD as opposed to those without cGVHD.

Conclusions: Differential expression of miRNAs, particularly the downregulation of miRNA-769-5p, may influence the development of oral cGVHD by diminishing its inhibitory effect on the TGF-â/Smad signaling pathway through its interaction with Smad2.