Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disease with various clinical manifestations. MicroRNAs (miRNAs) and immunometabolism are recognized as key elements in SLE pathogenesis; However, the relationship between miRNAs and peripheral blood mononuclear cells (PBMCs) and metabolism in SLE remains unclear.

In this study, we first evaluated mRNA and miRNA expression profiles in PBMCs from Chinese SLE patients using next-generation sequencing (NGS). Secondly, integrating the results of our bioinformatic analysis of immunometabolism, we sought to identify potential miRNAs associated with the regulation of SLE progression and experimentally validated their differential expression between SLE patients and healthy controls (HCs).

Lastly, through dual-luciferase reporter assays and western blotting, we identified the potential metabolism-associated targets that are regulated by miRNAs. The purpose of this study was to elucidate the mechanisms underlying SLE progression and to investigate the potential applications of miRNAs in the treatment of this disease. 

They detected PBMC miRNA and mRNA profiles from 3 pooled SLE patients and healthy controls (HCs) using next-generation sequencing, predicted miRNA targets in dysregulated mRNAs, predicted functions and interactions of differentially expressed genes using bioinformatics analysis, validated candidate miRNAs using qRT- PCR, and investigated the association between the expression of candidate miRNAs and SLE clinical characteristics.

Moreover, they validated the direct and transcriptional regulatory effect of NovelmiRNA-25 on adenosine monophosphate deaminase 2 ( AMPD2 ) using a dual-luciferase reporter assay and western blot and confirmed  AMPD2  mRNA and protein expression in PBMCs using qRT-PCR and western blot, respectively . 

mRNA Regulation

Multilayer integrative analysis of microRNA and mRNA regulation showed that 10 miRNAs were down-regulated and 19 miRNAs were up-regulated in SLE patient PBMCs compared with HCs. Bioinformatics analysis of regulatory networks between miRNAs and mRNAs showed that 19 miRNAs were related to metabolic processes.

Two candidate miRNAs, NovelmiRNA-25 and miR-1273h-5p, which were significantly increased in the PBMCs of SLE patients (P < 0.05), represented diagnostic biomarkers with sensitivities of 94.74% and 89.47%, respectively (area under the curve = 0.574 and 0.788, respectively).

NovelmiRNA-25 expression in PBMCs was associated with disease activity in SLE patients, in both active and stable groups (P < 0.05). NovelmiRNA-25 overexpression downregulated AMPD2expression in HEK293T cells through direct targeting of the AMPD2 3?UTR (P < 0.01), while inhibition of NovelmiRNA-25 activity led to increased AMPD2expression (P < 0.01).

NovelmiRNA-25 overexpression also downregulated AMPD2 protein expression in HEK293T cells; AMPD2 protein expression in SLE patient PBMCs was decreased. The results show that differentially expressed miRNAs play an important role in SLE.

The data demonstrate a novel mechanism in SLE development that involves the targeting of AMPD2 expression by NovelmiRNA-25. miRNAs may serve as novel biomarkers for the diagnosis and evaluation of SLE activity and represent potential therapeutic targets for this disease.