Small RNAs encoded by human endogenous retrovirus K overexpressed in PBMCs may contribute to the diagnosis and evaluation of systemic lupus erythematosus as novel biomarkers.

This study aimed to identify the genes and small RNAs (sRNAs) expressed by the human endogenous retrovirus K (HERV-K) HML2 and their associations with the immune process of systemic lupus erythematosus (SLE). RNA-Seq data including 99 SLE patients and 18 controls (GSE72420) was obtained from the Gene Expression Omnibus. Differentially expressed genes (DEGs) as well as HML2-DEGs between SLE patients and normal controls were identified. Five HML2-DEGs involved in immune-regulating function were identified using weighted gene co-expression network analysis. The associations between these genes and the proportions of immune cells were determined by CIBERSORT. Ten candidate HML2-encoded sRNAs were identified based on specific criteria, and three of them were further validated in SLE patients by qRT-PCR. The diagnostic values of these three sRNAs were evaluated in SLE and lupus nephritis (LN). This study suggested that HML2 genes and their encoded sRNAs might be involved in the immune regulation and progress of SLE. These potential sRNAs might function as regulatory molecules and diagnostic biomarkers of SLE and LN.

Modulation of miR-548m encoded by X chromosome on the PTEN pathway in systemic lupus erythematosus.

OBJECTIVES: Systemic lupus erythematosus (SLE) is a typical autoimmune disease, which is associated with many factors, such as miRNAs. The effect of miRNAs encoded by X chromosome (X-linked miRNAs) plays a crucial role in autoimmune disease. This study aims to identify X-linked miRNAs and validate the pathway influenced by miRNAs in SLE. METHODS: Differentially expressed miRNAs (DEMs) encoded by X chromosome from PBMCs of SLE patients compared to healthy controls (HCs) and differentially expressed genes (DEGs) acquired from GSE50772 were analysed. The function and pathway enrichment analysis of the overlapping genes of target genes of X-linked miRNA and DEGs were performed, followed by investigating the hub genes. The expression of the identified miRNA (miR-548m) was verified in SLE patients. The relationship between miR-548m and PTEN was detected by increasing/decreasing miR-548m expression. The target of miR-548m on PTEN was confirmed by luciferase reporter assays. RESULTS: 104 DEMs (9 X-linked miRNAs) and 3071 DEGs were identified. The target genes of X-linked miRNAs and DEGs were intersected to obtain 114 consensus genes. Then the top 5 hub genes (FOS, PTEN, STAT1, GRB2, ITGA6) were screened and PTEN expression might have negative correlation with X-linked miR-548m in SLE patients. Upregulation of miR-548m significantly inhibited PTEN expression, while knocking down miR-548m increased PTEN expression. There was a miR-548m target in the nt219-nt225 region of PTEN 3́UTR. CONCLUSIONS: X-linked miR-548m might target PTEN and play a role in SLE, which revealed a new molecular mechanism of X-linked miRNA in the development of SLE.

The contribution of miR-122 to the innate immunity by regulating toll-like receptor 4 in hepatoma cells.

BACKGROUND: Hepatocellular carcinoma (HCC) is a kind of malignancies to impact human health. It has been reported that aberrant toll-like receptor (TLR) signaling may contribute to the development and progression of HCC, especially TLR4. MiR-122, which extensively involved in hepatitis virus infection and the apoptosis of hepatoma cells, might be decreased in HCC patients livers. The hypothesis of this study was whether miR-122 plays a role in inflammatory pathways through regulating TLR4 expression in hepatoma cells. METHODS: The expression of miR-122 in the tissues of HCC patients compared to controls in TCGA datasets was analyzed. The relationship between miR-122 and TLR4 was detected in HCC cell lines by increasing/decreasing miR-122 expression. The target of miR-122 on TLR4 was confirmed by luciferase reporter assays. The proliferation of HCC cells and production of proinflammatory cytokines were measured with miR-122 upregulation and inhibition. RESULTS: We found that the expression of miR-122 was decreased in HCC tissues and showed the diagnostic capacity for HCC in TCGA datasets. MiR-122 and TLR4 expression have negative correlation in normal liver cells and HCC cells. Upregulation of miR-122 significantly inhibited TLR4 expression in hepatoma cells, including in hepatoma cells with the induction of LPS, while knocking down miR-122 increased TLR4 expression. By screening potential miR-122 targets among TLR4, we found that there was a putative miR-122 target in TLR4 3'UTR. Mutations in the nt1603-nt1609 region of TLR4 3'UTR abandoned the impact of miR-122 on TLR4 expression. Over-expression/down-expression of miR-122 could influence the proliferation and the expression of natural immune factors. CONCLUSIONS: MiR-122 might target TLR4 and regulate host innate immunity in hepatoma cells, which revealed a new molecular mechanism of miR-122 on the regulation of innate immunity.