Gastric Juice miR-106a-5p as a Non-Invasive Biomarker of Neuroinflammation and Neurodegeneration: A Prospective...

Neuroinflammation is a key contributor to the progression of several neurodegenerative disorders, including Alzheimer's disease, stroke, and small vessel disease. Emerging evidence highlights the role of circulating microRNAs (miRNAs) as non-invasive biomarkers of neuroinflammation and neuronal injury. miR-106a-5p, a member of the miR-17~92 cluster, is known to regulate inflammation, apoptosis, and vascular function. While typically studied in plasma or cerebrospinal fluid, gastric juice miRNAs represent a novel and underexplored source for biomarker discovery within the gut-brain axis. This exploratory study aimed to investigate the association between gastric juice miR-106a-5p expression and markers of neuroinflammation, including C-reactive protein (CRP), lactate dehydrogenase (LDH), and imaging-based evidence of neurodegeneration.

A prospective, observational study was conducted on 38 participants (22 with neurodegenerative pathology and 16 healthy controls). Gastric juice samples were analyzed for miR-106a-5p using RT-qPCR, normalized to U6 snRNA. ΔCt values were used to determine relative expression. Statistical analyses included t-tests/Wilcoxon tests, ROC curve analysis, and correlation testing, with significance set at p < 0.05.

Patients with neurodegenerative changes exhibited significantly lower gastric miR-106a-5p expression compared to controls (p = 0.044). Elevated CRP and LDH levels were associated with higher ΔCt values (indicating lower expression), with p-values of 0.019 and 0.023, respectively. ROC analysis showed moderate diagnostic accuracy (AUC = 0.701) for miR-106a in identifying neurodegenerative status. miR-106a levels also correlated inversely with carotid intima-media thickness and brain MRI abnormalities, also reduced gastric miR-106a-5p expression is associated with systemic inflammation and neuroimaging evidence of neurodegeneration.

While causality cannot be inferred, these findings suggest that gastric miR-106a may serve as a promising non-invasive biomarker within the gut-brain axis framework. Further longitudinal and mechanistic studies are warranted to validate its clinical utility and explore its potential role in monitoring neuroinflammatory conditions.