Background Manganese (Mn) is one of the environmental factors of Parkinson's disease (PD), and long-term exposure to Mn can cause nerve damage. It is important to explore the common mechanism of neurotoxic effects of Mn and neurodegenerative diseases (NDD), especially PD, for early diagnosis of the disease.

Objective To comprehensively analyze the core messenger RNA (mRNA)-microRNAs (miRNAs) co-expressed in frontal cortex of NDD patients and neuronal cells exposed to Mn via bioinformatics, and to reveal the potential common mechanism between Mn-induced neurotoxicity and NDD, especially PD.

Methods Difference of the mRNAs from frontal cortex of NDD patients (GSE150696) and human neuroblastoma (SH-SY5Y) cells exposed to Mn were analyzed by R software; Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was performed on the overlapping differentially expressed genes (DEGs). The miRNAs were predicted using the miRNet database, mRNA-miRNA interactions were identified by the starBase and miRTarBase databases, and mRNA-miRNA regulatory networks were constructed with Cytoscape software. The core miRNAs associated with PD (GSE77667) were incorporated into Weighted Gene Co-Expression Network Analysis (WGCNA) and the mRNA-miRNA regulatory network was comparatively analyzed.

Results A total of 34 overlapping DEGs were identified in the frontal cortical of NDD patients and the neuronal cells exposed to Mn, mainly enriched in interleukin-17 (IL-17) signaling pathway, cyclic adenosine monophosphate (cAMP) signaling pathway, and primary immunodeficiency. Based on the results of database prediction, 52 miRNAs with 71 pairs of interaction relationships were finally included to construct the miRNA-mRNA regulatory network. Six core miRNAs were screened by WGCNA: hsa-let-7i-5p, hsa-mir-155-5p, hsa-mir-219-2-3p, hsa-mir-221-3p, hsa-mir-485-3p, and hsa-mir-509-3-5p, among which hsa-let-7i-5p interacted with the target gene FBXW2 and hsa-mir-155-5p interacted with the target gene CCL2. The results of the KEGG analysis indicated that CCL2 was closely related to the IL-17 signaling pathway.

Conclusion There are similar molecular regulatory mechanisms involved in the neurotoxicity of Mn and NDD, and the IL-17 signaling pathway may play a role in Mn-related NDD through CCL2 and hsa-mir-155-5p.