Biology subjects

Ploumakis, A.

Publications and source records attributed to Ploumakis, A..

3 recordsLinked to original sources

bioRxiv2025

Spatial transcriptomic profiling identifies lacrimal gland epithelial cell-driven mechanisms underlying autoimmunity in Sjogrens disease.

Sjogrens disease (SjD) is a second most prevalent rheumatic disease involving autoimmune pathology of tear-producing lacrimal glands that leads to a common clinical manifestation of chronic ocular surface disease. Despite advances in understanding of SjD, lacrimal gland pathology remains incompletely understood limiting diagnosis and treatment. Here we analyze spatial transcriptomic profile of lacrimal glands from wild-type (C57Bl/6) mice and Thrombospondin (TSP)-1-/- mice, a spontaneous mouse model of SjD. We uncover molecular mechanisms underlying functional loss of major epithelial cell subtypes - acinar, duct and myoepithelial cells. We identify potential early mechanisms and markers of glandular damage. By integrating spatial and cellular profiles, we uncover the presence of antigen presenting cells in the proximity of duct epithelial cells that were not described previously in lacrimal glands. We further identify role of epithelial cells as active participants in promoting or sustaining inflammation. Our findings help reveal potential molecular and cellular cues that drive periductal infiltrates containing B cells and Tfh cells that form germinal centers to facilitate local autoantibody production. Overall, our study can provide a framework for therapeutic targeting of epithelial cell types and multicellular interactions underlying autoimmune pathology. Significance StatementTears produced by lacrimal glands are critical for protecting the eye surface by preventing tissue dryness and maintaining normal vision. Disruption of this function due to autoimmune inflammation in Sjogrens Disease compromises the protection of the eye surface causing dryness, a condition with a potential for sight-threatening complications like infections and ulcers. Understanding cellular and molecular interactions that lead to functional loss and autoimmune inflammation of the lacrimal gland is critical for developing effective therapies. We have analyzed transcriptional profile of glandular cells in a tissue section where their morphology and interactions with surrounding cells is preserved. By comparing glands from normal and mice with Sjogrens disease we identify molecular mechanisms that can form the basis for new therapies.

immunology↗

bioRxiv2025

Sex differences in progressive multiple sclerosis brain gene expression in oligodendrocytes and OPCs

Multiple sclerosis is a neurological autoimmune disease with sex-imbalanced incidence; in the USA, the disease is more likely to effect females at a ratio of 3:1. In addition, males are more likely to have a more severe disease course at time of diagnosis. Questions about both causes and downstream effects of this disparity remain. We aim to investigate gene expression differences at a cellular level while considering sex to discover fine-scale sex disparities. These investigations could provide new avenues for treatment targeting, or treatment planning based on sex. Public single-nuclei RNA-sequencing data from three publications of progressive MS including control brains were analysed using the Seurat R package. Differential gene and pathway expression was looked at both within a specific data set which has sub-lesion level sample dissection and across all studies to provide a broader lens. This allowed for the consideration of cell types and spatial positioning in relation to the interrogated lesion in some of the calculations. Our analysis showed expression changes in the female MS oligodendrocytes and oligodendrocyte progenitor cells compared to healthy controls, which were not observed in the corresponding male affected cells. Differentially up-regulated genes in females include increased HLA-A in the oligodendrocytes, and increased clusterin in the oligodendrocyte progenitor cells. There are also several mitochondrial genes in both the oligodendrocytes and oligodendrocyte progenitors which are up-regulated in females, including several directly involved in electron transport and which have previously been associated with neurodegenerative diseases. These results point to altered states in oligodendrocyte progenitors and oligodendrocytes that in combination with known physiological dissimilarities between sexes may denote different programming in males and females in response to the onset of demyelinating lesions. The potential for increased debris clearance mediated by clusterin and availability of oligodendrocyte progenitors in females may indicate an environment more primed for repair, potentially including remyelination. This could contribute to the disparity in etiology in females versus males.

neuroscience↗

bioRxiv2025

Molecular hallmarks of excitatory and inhibitory neuronal resilience and resistance to Alzheimer's disease

BackgroundA significant proportion of individuals maintain healthy cognitive function despite having extensive Alzheimers disease (AD) pathology, known as cognitive resilience. Understanding the molecular mechanisms that protect these individuals can identify therapeutic targets for AD dementia. This study aims to define molecular and cellular signatures of cognitive resilience, protection and resistance, by integrating genetics, bulk RNA, and single-nucleus RNA sequencing data across multiple brain regions from AD, resilient, and control individuals. MethodsWe analyzed data from the Religious Order Study and the Rush Memory and Aging Project (ROSMAP), including bulk (n=631) and multi-regional single nucleus (n=48) RNA sequencing. Subjects were categorized into AD, resilient, and control based on {beta}-amyloid and tau pathology, and cognitive status. We identified and prioritized protected cell populations using whole genome sequencing-derived genetic variants, transcriptomic profiling, and cellular composition distribution. ResultsTranscriptomic results, supported by GWAS-derived polygenic risk scores, place cognitive resilience as an intermediate state in the AD continuum. Tissue-level analysis revealed 43 genes enriched in nucleic acid metabolism and signaling that were differentially expressed between AD and resilience. Only GFAP (upregulated) and KLF4 (downregulated) showed differential expression in resilience compared to controls. Cellular resilience involved reorganization of protein folding and degradation pathways, with downregulation of Hsp90 and selective upregulation of Hsp40, Hsp70, and Hsp110 families in excitatory neurons. Excitatory neuronal subpopulations in the entorhinal cortex (ATP8B1+ and MEF2Chigh) exhibited unique resilience signaling through neurotrophin (modulated by LINGO1) and angiopoietin (ANGPT2/TEK) pathways. We identified MEF2C, ATP8B1, and RELN as key markers of resilient excitatory neuronal populations, characterized by selective vulnerability in AD. Protective rare variant enrichment highlighted vulnerable populations, including somatostatin (SST) inhibitory interneurons, validated through immunofluorescence showing co-expression of rare variant associated RBFOX1 and KIF26B in SST+ neurons in the dorsolateral prefrontal cortex. The maintenance of excitatory-inhibitory balance emerges as a key characteristic of resilience. ConclusionsWe identified molecular and cellular hallmarks of cognitive resilience, an intermediate state in the AD continuum. Resilience mechanisms include preservation of neuronal function, maintenance of excitatory/inhibitory balance, and activation of protective signaling pathways. Specific excitatory neuronal populations appear to play a central role in mediating cognitive resilience, while a subset of vulnerable SST interneurons likely provide compensation against AD-associated dysregulation. This study offers a framework to leverage natural protective mechanisms to mitigate neurodegeneration and preserve cognition in AD.

neuroscience↗