An early symptom of Alzheimer’s disease (AD) is an impaired sense of smell, for which the molecular basis remains elusive. Here, we generated human olfactory neurosphere-derived (ONS) cells from people with AD and mild cognitive impairment (MCI), and performed global RNA sequencing to determine gene expression changes. ONS cells expressed markers of neuroglial differentiation, providing a unique cellular model to explore changes of early AD-associated pathways. Our transcriptomics data from ONS cells revealed differentially expressed genes (DEGs) associated with cognitive processes in AD cells compared to MCI, or matched healthy controls (HC). A-Kinase Anchoring Protein 6 (AKAP6) was the most significantly altered gene in AD compared to both MCI and HC, and has been linked to cognitive function. The greatest change in gene expression of all DEGs occurred between AD and MCI. Gene pathway analysis revealed defects in multiple cellular processes with aging, intellectual deficiency and alternative splicing being the most significantly dysregulated in AD ONS cells. Our results demonstrate that ONS cells can provide a cellular model for AD that recapitulates disease-associated differences. We have revealed potential novel genes, including AKAP6 that may have a role in AD, particularly MCI to AD transition, and should be further examined.

An early symptom of Alzheimer’s disease (AD) is an impaired sense of smell, for which the molecular basis remains elusive. Here, we generated human olfactory neurosphere-derived (ONS) cells from people with AD and mild cognitive impairment (MCI), and performed global RNA sequencing to determine gene expression changes. ONS cells expressed markers of neuroglial differentiation, providing a unique cellular model to explore early AD-associated disease pathways. Our transcriptomics data from ONS cells revealed differentially expressed genes (DEGs) associated with cognitive processes in AD cells compared to MCI, or matched healthy controls (HC). A-Kinase Anchoring Protein 6 ( AKAP6) was the most significantly altered gene in AD compared to both MCI and HC, and has been linked to cognitive function. The greatest change in gene expression of all DEGs occurred between AD and MCI. Gene pathway analysis revealed defects in multiple cellular processes with aging, intellectual deficiency and alternative splicing being the most significantly dysregulated in AD ONS cells. Our results demonstrate that ONS cells can provide a cellular model for AD that recapitulates disease-associated differences. We have revealed potential novel genes, including AKAP6 that may have a role in AD, particularly MCI to AD transition, and should be further examined.

Alzheimer’s disease (AD) is a progressive, neurodegenerative disorder and the leading cause of dementia worldwide. Although recent therapeutic advances have provided some disease-modifying potential, there is currently no curative treatment for AD, highlighting the need for improved disease models and early biomarkers. Olfactory mucosal stem cells, which can be expanded in vitro as olfactory neurosphere-derived (ONS) cells, represent a promising source for biomarker discovery because olfactory tissue is more accessible than central nervous system tissue and has been reported to exhibit AD-related pathological changes. In this study, we used subcellular fractionation-based proteomics, reconstructed bulk proteomics and integrated transcriptomic-proteomic analyses to characterise alterations in ONS cells derived from healthy control, mild cognitive impairment (MCI) and AD individuals. Fraction-specific proteomics identified cytoplasmic and nuclear-enriched protein abundance changes, including alterations in proteins and pathways associated with cytoskeletal organisation, RNA processing, intracellular trafficking, autophagy and mitochondrial/metabolic processes. Reduced LC3B abundance in cytoplasmic AD ONS cells was supported by western blot analysis, although LC3B abundance alone does not indicate altered autophagic flux. Reconstructed bulk proteomics identified 40 FDR-significant proteins in AD compared with HC, defining an AD-associated protein signature enriched for extracellular matrix, cytoskeletal, organelle-associated and RNA-processing pathways. Despite proteomic enrichment of mitochondrial and metabolic pathways, Seahorse Mito Stress Test analysis did not identify significant group-level differences in mitochondrial respiration. Integrated transcriptomic-proteomic analysis revealed partial RNA-protein concordance and pathway-level overlap across disease-associated processes. Together, these findings support the use of patient-derived ONS cells as a model for investigating AD- and MCI-associated molecular changes and highlight protein signatures for further validation.