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Extracellular vesicles (EV) have emerged as a less-invasive nano-tool for discovering biomarkers of Alzheimer’s disease and related dementia. Here, we analyzed different neuron-enriched EV from plasma to predict response and molecular mechanisms of ketogenic diet’s efficacy in mild cognitive impairment participants. The study was a randomized crossover design in which cognitively normal and mild cognitive impairment participants consumed a modified Mediterranean-ketogenic diet (MMKD) or American Heart Association diet (AHAD) for six weeks, followed by other diet after washout. L1 cell adhesion molecule (L1CAM), synaptophysin, and neural cell adhesion molecule (NCAM) surface markers were used to enrich for neuron-secreted small EV (sEVL1CAM, sEVSYP, and sEVNCAM). For the first time, we have presented multiple evidences, including immunogold labeling/Transmission electron microscopy, CD63 (clusters of differentiation 63)-ELISA based assay, confocal microscopy fluorescent images, and flow cytometry data confirming the presence of L1CAM on the surface of sEVL1CAM, validating purity and relative abundance of sEVL1CAM in the plasma. Cargo analysis of sEVL1CAM showed that MMKD intervention reduces amyloid beta 1-42 (50.3%, p = 0.011), p181-tau (34.9%, p = 0.033) and neurofilament light (54.2%, p = 0.020) in mild cognitive impairment participants. Moreover, sEVL1CAM showed better sensitivity compared to CSF in analyzing increased glutamate (6 folds, p < 0.0001) from mild cognitive impairment participants following MMKD intervention. sEVL1CAM characterization also suggested that MMKD differentially targets the expression of various glutamate receptors - glutamate receptor ionotropic NMDA1 (GRIN1), glutamate receptor ionotropic NMDA2A (GRIN2A), glutamate receptor ionotropic NMDA2B (GRIN2B) and glutamate receptor ionotropic AMPA type subunit 1 (GRIA1). Importantly, these sEVL1CAM measures strongly correlated with corresponding clinical CSF biomarkers (neurogranin, amyloid beta 1-42, neurofilament light, and tau). Furthermore, sEVL1CAM were loaded with less advanced-glycation endproducts and exhibited anti-inflammatory activity following MMKD intervention. Most importantly, the expression of monocarboxylate transporter 2 on the surface of sEVL1CAM predicted the amyloid beta 1-42 response to MMKD intervention (Area under the curve = 0.87, p = 0.0044) and offered a novel screening tool to identify participants responsive to this dietary intervention. Finally, sEVL1CAM, sEVSYP, and sEVNCAM showed significantly high concordance in analyzing amyloid beta 1-42 (Pearson correlation coefficient ≥ 0.63, p < 0.01) and neurofilament light (Pearson correlation coefficient ≥ 0.49, p < 0.05). Together, sEV in plasma offers promise in assessing the efficacy of dietary/therapeutic intervention against mild cognitive impairment/Alzheimer’s disease.

INTRODUCTIONBrain cell–derived small extracellular vesicles (sEVs) in blood offer unique cellular and molecular information related to the onset and progression of Alzheimer's disease (AD). We simultaneously enriched six specific sEV subtypes from the plasma and analyzed a selected panel of microRNAs (miRNAs) in older adults with/without cognitive impairment.METHODSTotal sEVs were isolated from the plasma of participants with normal cognition (CN; n = 11), mild cognitive impairment (MCI; n = 11), MCI conversion to AD dementia (MCI‐AD; n = 6), and AD dementia (n = 11). Various brain cell–derived sEVs (from neurons, astrocytes, microglia, oligodendrocytes, pericytes, and endothelial cells) were enriched and analyzed for specific miRNAs.RESULTSmiRNAs in sEV subtypes differentially expressed in MCI, MCI‐AD, and AD dementia compared to the CN group clearly distinguished dementia status, with an area under the curve (AUC) > 0.90 and correlated with the temporal cortical region thickness on magnetic resonance imaging (MRI).DISCUSSIONmiRNA analyses in specific sEVs could serve as a novel blood‐based molecular biomarker for AD.Highlights Multiple brain cell–derived small extracellular vesicles (sEVs) could be isolated simultaneously from blood. MicroRNA (miRNA) expression in sEVs could detect Alzheimer's disease (AD) with high specificity and sensitivity. miRNA expression in sEVs correlated with cortical region thickness on magnetic resonance imaging (MRI). Altered expression of miRNAs in sEVCD31 and sEVPDGFRβ suggested vascular dysfunction. miRNA expression in sEVs could predict the activation state of specific brain cell types.

Hypoxia and hypoxia-related biomarkers are the major determinants of prostate cancer (PCa) aggressiveness. Therefore, a better understanding of molecular players involved in PCa cell survival under hypoxia could offer novel therapeutic targets. We previously reported a central role of mitochondrial protein carnitine palmitoyltransferase (CPT1A) in PCa progression, but its role in regulating PCa survival under hypoxia remains unknown. Here, we employed PCa cells (22Rv1 and MDA-PCa-2b) with knockdown or overexpression of CPT1A and assessed their survival under hypoxia, both in cell culture and in vivo models. The results showed that CPT1A knockdown in PCa cells significantly reduced their viability, clonogenicity, and sphere formation under hypoxia, while its overexpression increased their proliferation, clonogenicity, and sphere formation. In nude mice, 22Rv1 xenografts with CPT1A knockdown grew significantly slower compared to vector control cells (~59% reduction in tumor volume at day 29). On the contrary, CPT1A-overexpressing 22Rv1 xenografts showed higher tumor growth compared to vector control cells (~58% higher tumor volume at day 40). Pathological analyses revealed lesser necrotic areas in CPT1A knockdown tumors and higher necrotic areas in CPT1A overexpressing tumors. Immunofluorescence analysis of tumors showed that CPT1A knockdown strongly compromised the hypoxic areas (pimonidazole+), while CPT1A overexpression resulted in more hypoxia areas with strong expression of proliferation biomarkers (Ki67 and cyclin D1). Finally, IHC analysis of tumors revealed a significant decrease in VEGF or VEGF-D expression but without significant changes in biomarkers associated with microvessel density. These results suggest that CPT1A regulates PCa survival in hypoxic conditions and might contribute to their aggressiveness.

Diabetic kidney disease is one of the most serious microvascular complications and among the leading causes of end stage renal disease. Persistently increasing albuminuria has been considered to be the central hallmark of nephropathy. However, albuminuria can indicate kidney damage for clinicians; it is not a specific biomarker for prediction of diabetic kidney disease prior to the onset of this devastating complication, and in fact all individuals with microalbuminuria do not progress to overt nephropathy. Controlled glycemia is unable to prevent nephropathy in all diabetic individuals indicating the role of other factors in progression of diabetic kidney disease.