Biology subjects

Woulfe, J. M.

Publications and source records attributed to Woulfe, J. M..

5 recordsLinked to original sources

bioRxiv2026

ASC specks and α-synuclein amplify microglial NLRP3 inflammasome activation and co-localize with Lewy body pathology

Neuroinflammation is a hallmark of several chronic neurodegenerative disorders, including Parkinson's disease (PD) and other synucleinopathies, and is closely associated with microglial activation. The inflammasome adaptor protein apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC) undergoes oligomerization upon inflammasome activation, resulting in the formation of ASC specks. These structures are recognized by microglia as damage-associated molecular patterns (DAMPs), thereby promoting inflammatory signaling. Recent studies have demonstrated that extracellular ASC specks associate with amyloid-{beta} (A{beta}), and that uptake of ASC-A{beta} composites by microglia amplifies pro-inflammatory responses. Although ASC specks have also been shown to potentiate -synuclein (Syn) preformed fibril-induced pathology, their interaction with monomeric Syn and their effects on inflammasome activation remain poorly understood. Here, we co-stimulated murine SIM-A9 microglia with ASC-Syn assemblies and evaluated their effects on NLRP3 inflammasome activation. Electron microscopy revealed a close association between ASC fibrils and Syn monomers. Exposure of microglia to ASC-Syn enhanced NLRP3 inflammasome activation, as evidenced by increased ASC speck formation, caspase-1 activation, and secretion of IL-1{beta} and IL-18, when compared to ASC or Syn alone. In addition, immunohistochemical analyses of post mortem brain tissue from patients with dementia with Lewy bodies demonstrated ASC expression in regions exhibiting Syn pathology and showed ASC co-localization with Syn within Lewy bodies. Collectively, these findings identify ASC-Syn assemblies as potent amplifiers of NLRP3 inflammasome signaling and suggest a mechanism through which they may contribute to sustained neuroinflammation in synucleinopathies.

neuroscience↗

bioRxiv2024

A Protocol for Neuralized Murine Olfactory Organoids

Chronic olfactory dysfunction can be associated with parkinsonism, dementia, demyelinating disorders and schizophrenia. The olfactory epithelium (OE) represents an interface between the environment and the central nervous system. Mounting evidence implicates environmental factors in neurodegenerative disease processes, necessitating investigations into their interactions with the hosts genome. In Parkinson disease, hyposmia often precedes motor symptoms, raising the possibility that the OE could be involved in disease initiation. We previously demonstrated abundant -synuclein expression in mammalian OE as well as aggregate formation in the olfactory nerve. Current in vitro models of OE are limited, relying primarily on post-mitotic cultures established from biopsies. To address this gap, we present a method for generating olfactory organoids of OE from adult mice. These organoids comprise neuronal and non-neuronal cell types, including sustentacular cells, thus encompassing structural elements of OE in situ. Expression of the olfactory sensory neuron marker OMP and Parkinsons-linked -synuclein was also detected in olfactory organoids, highlighting their potential usefulness to mechanistic research. We established OE organoids that were kept in culture for up to 3 weeks. In addition, we inoculated organoids with the neurotropic vesicular stomatitis virus to model infections. We conclude that this olfactory organoid model system offers a new platform for studying airborne environmental factors in their interactions with a genetically defined host; this, to study OE biology and enable the exploration of disease processes within olfactory tissue.

neuroscience↗

bioRxiv2024

A stress-dependent TDP-43 SUMOylation program preserves neuronal function

Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD) are overwhelmingly linked to TDP-43 dysfunction. Mutations in TDP-43 are rare, indicating that the progressive accumulation of exogenous factors - such as cellular stressors - converge on TDP-43 to play a key role in disease pathogenesis. Post translational modifications such as SUMOylation play essential roles in response to such exogenous stressors. We therefore set out to understand how SUMOylation may regulate TDP-43 in health and disease. We find that TDP-43 is regulated dynamically via SUMOylation in response to cellular stressors. When this process is blocked in vivo, we note age-dependent TDP-43 pathology and sex-specific behavioral deficits linking TDP-43 SUMOylation with aging and disease. We further find that SUMOylation is correlated with human aging and disease states. Collectively, this work presents TDP-43 SUMOylation as an early physiological response to cellular stress, disruption of which may confer a risk for TDP-43 proteinopathy.

neuroscience↗

bioRxiv2023

Neuropathological assessment of the olfactory bulb and tract in individuals with COVID-19

The majority of patients with Parkinson disease (PD) experience a loss in their sense of smell and accumulate insoluble -synuclein aggregates in their olfactory bulbs (OB). Subjects affected by a SARS-CoV-2-linked illness (COVID-19) frequently experience hyposmia. We previously hypothesized that -synuclein and tau misprocessing could occur following host responses to microbial triggers. Using semiquantitative measurements of immunohistochemical signals, we examined OB and olfactory tract specimens collected serially at autopsies between 2020 and 2023. Deceased subjects comprised 50 adults, which included COVID19+ patients (n=22), individuals with Lewy body disease (e.g., PD and dementia with Lewy bodies (DLB; n=6)), Alzheimer disease (AD; n=3), other non-synucleinopathy-linked degenerative diseases (e.g., progressive supranuclear palsy (PSP; n=2) and multisystem atrophy (MSA; n=1)). Further, we included neurologically healthy controls (HCO; n=9) and those with an inflammation-rich brain disorder as neurological controls (NCO; n=7). When probing for inflammatory changes focusing on anterior olfactory nuclei (AON) using anti-CD68 immunostaining, scores were consistently elevated in NCO and AD cases. In contrast, inflammation on average was not significantly altered in COVID19+ patients relative to controls, although anti-CD68 reactivity in their OB and tracts declined with progression in age. Mild-to-moderate increases in phospho-Syn and phospho-tau signals were detected in the AON of tauopathy-and synucleinopathy-afflicted brains, respectively, consistent with mixed pathology, as described by others. Lastly, when both sides were available for comparison in our case series, we saw no asymmetry in the degree of pathology of the left versus right OB and tracts. We concluded from our autopsy series that after a fatal course of COVID-19, microscopic changes -when present-in the rostral, intracranial portion of the olfactory circuitry generally reflected neurodegenerative processes seen elsewhere in the brain. In general, inflammation correlated best with the degree of Alzheimers-linked tauopathy and declined with progression of age in COVID19+ patients.

pathology↗

bioRxiv2020

Oxidative Modifications of Parkin Underlie its Selective Neuroprotection in Adult Human Brain

The mechanisms by which Parkinson disease-linked parkin confers neuroprotection of human dopamine cells remain elusive. We hypothesized that its cysteines mediate multiple anti-oxidant effects in the midbrain. By studying >60 control specimens, we found that in adult human brain - but not in skeletal muscle- parkin is mostly aggregated and insoluble due to oxidative modifications, such as at C253. In vitro, parkins oxidation directly reduces hydrogen peroxide (H2O2) to water. In parkin-deficient human brain, H2O2 concentrations are elevated. In dopamine toxicity studies, wild-type parkin -but not disease-associated mutants-prevents neural death by lowering H2O2 and sequestering radicals within insoluble aggregates. Parkin conjugates dopamine metabolites at the human-specific residue C95 and augments melanin formation in vitro. Using epitope-mapped antibodies, we found that in adult Substantia nigra neurons parkin localizes to neuromelanin within LAMP-3/CD63-positive lysosomes. We conclude that parkins own oxidation, previously considered a loss-of-function event, underlies three neuroprotective effects in adult midbrain: its cysteines participate in H2O2 reduction, dopamine radical conjugation and the formation of neuromelanin.

neuroscience↗