Identification of plasma microRNAs as a biomarker of sporadic Amyotrophic Lateral Sclerosis

Abstract

BackgroundAmyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease, which leads to the loss of upper and lower motor neurons, with a currently unknown etiology. Specific biomarkers could help in early detection and diagnosis, and could also act as indicators of disease progression and therapy effectiveness. MicroRNAs (miRNAs) are small (18–25 nucleotides), single-stranded non-coding RNA molecules that play important regulatory roles in animals and plants by targeting mRNAs for cleavage or translational repression, and are essential for nervous system development. Many of the genes associated with genetic ALS have pathological biological pathways related to RNA metabolism, and their pathogenesis may be affecting the maturing processes of miRNA.ResultsWe compared miRNA from the plasma of sALS patients and healthy controls using two cohorts; a discovery cohort analyzed with microarray (16 sALS patients and ten healthy controls) and a validation cohort confirmed with qPCR (48 sALS patients, 47 healthy controls and 30 disease controls). We measured the total amount of extracted RNA along with a spike-in control that ensured the quality of our quantification. A percentage of the 10–40 nt RNAs extracted from the total RNA showed a significant increase in ALS patients. There was a negative correlation between total RNA concentration and disease duration from onset to end point. Three of the miRNAs were up-regulated and six were down-regulated significantly in the discovery cohort. Since an internal control is required as a sample stability indicator of both the patients and controls in microarray analysis, we selected the miRNA showing the smallest dispersion and equivalency between the two groups’ mean value, and decided to use hsa-miR-4516. We found hsa-miR-4649-5p to be up-regulated, and hsa-miR-4299 to be down-regulated, where each was not influenced by clinical characteristics. EPHA4, a target gene linked to the nervous system which has also been reported to be a disease modifier of ALS, is the common and most notable target gene of hsa-miR-4649-5p and hsa-miR-4299.ConclusionWe have shown the relationship circulating plasma miRNA has with both healthy controls and diseased patients. Hsa-miR-4649-5p and hsa-miR-4299 have the potential to be ALS diagnosis biomarkers.Electronic supplementary materialThe online version of this article (doi:10.1186/s13041-015-0161-7) contains supplementary material, which is available to authorized users.

Fluid-Based Biomarkers for Amyotrophic Lateral Sclerosis

“…This suggests that miRNA-1234-3p may allow for specific diagnosis of sALS. Plasma miRNA-4649-5p has been shown to increase in patients with sALS and was shown to be negatively correlated with disease duration [120]. miRNA-424 and miRNA-206 had significantly higher expression in ALS plasma compared with healthy controls [133].…”

“…In addition to miRNAs in the CSF, investigations in the serum and plasma have also been performed (Table 2) [119,120,133]. Significant decreases in miRNA-1234-3p were only observed in sera from patients with sALS compared with healthy controls, but no significant difference was observed in sera from patients with fALS as compared with healthy controls [119].…”

Neuron-Microglia Interactions in Motor Neuron Degeneration. The Inflammatory Hypothesis in Amyotrophic Lateral Sclerosis Revisited

“…There is growing evidence of the involvement of miRNA deregulation in ALS pathogenesis [207][208][209][210][211]. Changes in miRNA expression have been found in patients and the SOD1 G93A mouse [176,212,213] reflecting a dysfunction of the expressed RNA binding proteins involved in ALS.…”

Evaluating the levels of CSF and serum factors in ALS

“…There have been various ALS biomarker studies published with more ongoing, with special attention focused on identifying biomarkers in CSF or serum. Most of these studies have examined changes of individual biomarkers that might distinguish patients with ALS from healthy control subjects (Lu et al., 2015; Takahashi et al., 2015), but it is likely more appropriate to identify panels of biomarkers rather than focusing on a single factor to increase their specificity to ALS. Some studies were limited by the number of samples in the analysis (Turner et al., 2013), and some chose a different control population into the study (Tateishi et al., 2010).…”