Biology subjects

Groh, A. M. R.

Publications and source records attributed to Groh, A. M. R..

4 recordsLinked to original sources

bioRxiv2025

Cerebrospinal fluid-driven ependymal motile cilia defects are implicated in multiple sclerosis pathophysiology

BackgroundMultiple sclerosis is a neurodegenerative autoimmune disorder of the central nervous system (CNS) in which autoreactive immune cells migrate through a damaged blood brain barrier, resulting in focal demyelinating lesions of both the white and grey matter. Of increasing interest is the repeated observation that beyond focal lesions, there are also diffuse, surface-in gradients of pathology in MS, wherein damage is most severe directly adjacent to cerebrospinal fluid (CSF)-contacting surfaces, such as the subpial and periventricular areas. This observation suggests that toxic factors within MS CSF may be contributing to the emergence and/or evolution of surface-in gradients. Directly separating the CSF from the periventricular parenchyma are ependymal cells - a glial epithelium that are equipped with tufts of motile cilia which are critical for circulating CSF solutes and regulating local fluid flow. While damage to ependymal cilia has the potential to drastically modify CSF homeostasis and thus contribute to the damage of CSF exposed regions, these motile cellular structures have yet to be investigated in the context of MS. MethodsWe first conducted single cell RNA sequencing of fresh human periventricular brain tissue containing ependymal cells from MS patients and non-MS disease controls. We subsequently collected CSF from MS patients and exposed cultured rodent ependymal cells to this CSF in order to evaluate impact on ependymal ciliary function. To complement our direct evaluation of cilia in the context of MS, we also confirmed whether cilia were altered in a classic animal model of MS, experimental autoimmune encephalomyelitis (EAE), and also designed a novel transgenic animal model to evaluate the cellular and behavioural effect(s) of adult ependymal ciliary disruption. ResultsSingle cell RNA sequencing analysis of human ependymal cells in MS demonstrated largescale dysregulation of ciliary genes and in situ stains of MS brain tissue confirmed a loss of ependymal cilia. Exposure of ependymal cells to MS CSF led to transcriptional modification of ciliary gene and protein expression and reduced ciliary beating frequency. Likewise, analysis of ependymal cells in EAE also demonstrated altered cilia gene and protein expression. Conditional knockout in adult mice, of the critical cilia-associated gene Ccdc39 in ependymal cells led to transient ventricular enlargement, increased periventricular microglial density, and alterations in nesting behaviour. ConclusionThese data suggest that motile cilia in ependymal cells are dysregulated in CNS autoimmunity. More importantly, however, they provide evidence to suggest that ependymal cilia disruption could play an active role in the development of periventricular pathology in MS and can lead to behavioural deficits that may underlie aspects non-motor MS symptomatology.

neuroscience↗

bioRxiv2024

Age-Related Cerebral Ventriculomegaly occurs in Patients with Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is a genetic disorder causing motile ciliary dysfunction primarily affecting the respiratory and reproductive systems. However, the impact of PCD on the central nervous system, through dysfunction of motile cilia in multiciliated ependymal cells, remains poorly understood. We hypothesized that patients with PCD exhibit sub-clinical ventriculomegaly due to ependymal ciliary dysfunction, which may influence neuropsychiatric diagnoses. We demonstrated highly specific expression levels of known PCD-related genes in human brain ependymal cells (p<0.0001), supporting their potential role in regulating ependymal ciliary function. Computed tomography sinus images from patients with PCD (n=33) and age/sex-matched controls (n=64) were analysed. Patients with PCD displayed significantly larger ventricular areas (p<0.0001) and Evans index (p<0.01), indicating ventriculomegaly that was consistent across all genetic subgroups. Ventricular enlargement correlated positively with increasing age in patients with PCD compared to controls (p<0.001). Chart review demonstrated a high prevalence (39%) of neuropsychiatric/neurological disorders in adult PCD patients that did not correlate with degree of ventriculomegaly. Our findings suggest that patients with PCD may have unrecognized, mild ventriculomegaly potentially due to ependymal ciliary dysfunction which correlates with ageing. Further study is required to determine if ventricular enlargement contributes to neuropsychiatric/neurological or other morbidity in PCD.

neuroscience↗

bioRxiv2024

The functional and pathogenic consequences of fibrinogen on human oligodendroglia

Fibrinogen is a blood-derived protein involved in coagulation, and can make its way into the central nervous system (CNS) following breakdown of the blood-brain barrier. This molecule has been implicated in multiple sclerosis (MS), a disease marked by inflammation and demyelination in the CNS, as well as other neurological disorders. However, the effect of this molecule has not been studied on human myelinating cells. This study examines how fibrinogen influences human oligodendrocyte (OL) lineage cells at various stages of development. Using induced pluripotent stem cell-derived (iPSC) OL precursors and human primary OLs, we examined the effects of fibrinogen on cell differentiation, viability and myelination-related function. Here we show that fibrinogen induces an aberrant differentiation of early lineage OLs, by inhibiting their maturation and inducing an astrocytic phenotype, as seen in previous studies. On mature OLs, fibrinogen was found to promote myelination capacity as shown by ensheathment assays as well as on the RNA level. These effects were associated with the activation of BMP signalling, both in early and mature OLs. Transcriptomic analysis of human MS brain tissue shows similar pro-myelination changes in a subset of OLs, suggesting in vivo relevance. These findings indicate that fibrinogen has a lineage-dependent effect, where it may be inhibitory earlier in the lineage while promoting OL function in later stages. Understanding this dual role will provide insight into remyelination failure in MS and highlights the importance of timing and target in future therapeutic strategies. Significance StatementIn multiple sclerosis (MS), the blood protein fibrinogen leaks into the brain and has been shown to interfere with myelin repair. This study demonstrates that fibrinogen has opposite effects on human oligodendrocyte-lineage cells depending on their stage of maturation. While it blocks the differentiation of early-stage cells, it enhances the functional capacity of mature oligodendrocytes. These findings help explain why remyelination may fail in MS and suggest that fibrinogen could both hinder and support repair, depending on the cell context. This dual role has important implications for developing stage-specific therapies for MS.

neuroscience↗

bioRxiv2023

Cellular rejuvenation protects neurons from inflammation mediated cell death.

In multiple sclerosis (MS), the invasion of the central nervous system by peripheral immune cells is followed by the activation of resident microglia and astrocytes. This cascade of events results in demyelination, which triggers neuronal damage and death. The molecular signals in neurons responsible for this damage are not yet fully characterized. In MS, retinal ganglion cell neurons (RGCs) of the central nervous system (CNS) undergo axonal injury and cell death. This phenomenon is mirrored in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. To understand the molecular landscape, we isolated RGCs from mice subjected to the EAE protocol. RNA-sequencing and ATAC-sequencing analyses were performed. Pathway analysis of the RNA-sequencing data revealed that RGCs displayed a molecular signature, similar to aged neurons, showcasing features of senescence. Single-nucleus RNA-sequencing analysis of neurons from human MS patients revealed a comparable senescence-like phenotype., which was supported by immunostaining RGCs in EAE mice. These changes include alterations to the nuclear envelope, modifications in chromatin marks, and accumulation of DNA damage. Transduction of RGCs with an Oct4-Sox2-Klf4 transgene to convert neurons in the EAE model to a more youthful epigenetic and transcriptomic state enhanced the survival of RGCs. Collectively, this research uncovers a previously unidentified senescent-like phenotype in neurons under pathological inflammation and neurons from MS patients. The rejuvenation of this aged transcriptome improved visual acuity and neuronal survival in the EAE model supporting the idea that age rejuvenation therapies and senotherapeutic agents could offer a direct means of neuroprotection in autoimmune disorders.

neuroscience↗