Biology subjects

Frost, E.

Publications and source records attributed to Frost, E..

4 recordsLinked to original sources

bioRxiv2025

THC Reverses SIV-Induced Senescence in Astrocytes: Possible Compensatory Mechanism Against HIV Associated Brain Injury?

Despite effective combination antiretroviral therapy (cART), chronic neuroinflammation and glial dysfunction continues to be an important yet understudied issue with people living with HIV (PLWH). The endocannabinoid system is increasingly recognized as a potential therapeutic target for modulating neuroimmune environments, given its role in regulating synaptic plasticity, immune responses, and neuroinflammatory cascades. However, the extent to which cannabinoids influence HIV-associated neuroinflammation remains unclear. This study investigates the impact of {Delta}9-tetrahydrocannabinol (THC) on astrocyte growth characteristics, viability, and senescence-associated cytokine release following exposure to HIV Tat protein using primary mixed glial cultures derived from rhesus macaques. Real-time impedance-based cellular integrity assessments were conducted using the xCELLigence system, while morphological analyses and cytokine quantification were performed using phase-contrast microscopy and multiplex immunoassays. Treatment of macaques with THC protected the astrocytes from virus-induced senescence. Further, THC facilitated a rapid recovery from Tat-induced decline in astrocyte adhesion, suggesting a compensatory effect. THC promoted glial process elongation and morphological complexity, indicative of a shift toward a neuroprotective phenotype. Furthermore, THC significantly reduced inflammatory cytokine secretion, including TNF-, IL-6, and IL-1{beta}, in an apparently dose-dependent manner. These findings suggest that THC may modulate neuroinflammation in PLWH by promoting astrocytic survival, suppressing inflammatory cytokine secretion, and enhancing neurotrophic signaling. However, prolonged exposure to high-dose THC may negatively impact glial survival. The results underscore the complexity of cannabinoid signaling in the CNS and highlight the potential of cannabinoid-based interventions to mitigate HIV-associated neuroinflammation.

neuroscience↗

bioRxiv2025

Bi-directional relationship between the biofilm of Porphyromonas gingivalis and the amyloid-beta peptide.

Periodontitis and Porphyromonas gingivalis infections are significant risk factors for the onset of Alzheimers disease (AD). Despite P. gingivalis relying on biofilm for its survival and virulence, the impact of the extracellular matrix on ADs neuropathological hallmarks was never examined. In this study, we report a bidirectional relationship between the amyloid beta (A{beta}) peptide, which plays a central role in AD, and the biofilm of P. gingivalis. Using multiple fluorescent markers for biofilm components, we observed that A{beta}1-40 inhibited biofilm formation while A{beta}1-42 increased extracellular matrix production. Also, using thioflavin T staining and atomic force microscopy, we observed co-aggregation between the biofilm and monomeric A{beta}1-40, resulting in a quicker aggregation and significant changes in aggregate structures. Our findings propose mechanistic explanations for the role of P. gingivalis as a risk factor for AD and offer potential mechanisms for the microbial involvement in AD etiology. ImportanceWhile the etiology of Alzheimers disease has been studied extensively for the past 50 years, its exact causes remain unknown. Our current understanding is that the accumulation of multiple genetic and environmental risk factors would lead to the onset of the disease. Porphyromonas gingivalis is a bacterium that produces biofilm and elicits periodontitis, a chronic infection of the gums that constitutes a risk factor for Alzheimers disease. While studies have looked at the effects of P. gingivalis in triggering Alzheimers symptoms in animal models, none have explored the impact of the biofilm, which is ubiquitous to this bacterium. Our study seeks to bridge that gap by demonstrating a bi-directional relationship between the biofilm of P. gingivalis and amyloid beta, one of the brain lesions involved in Alzheimers. By understanding risk factors involved in Alzheimers and their impact, we hope to provide valuable knowledge on prevention and treatment.

microbiology↗

bioRxiv2020

Maladaptive myelination promotes epileptogenesis in absence epilepsy

Neuronal activity can influence the generation of new oligodendrocytes (oligodendrogenesis) and myelination. In health, this is an adaptive process that can increase synchrony within distributed neuronal networks and contribute to cognitive function. We hypothesized that in seizure disorders, aberrant neuronal activity may promote maladaptive myelination that contributes to pathogenesis. Absence epilepsy is a disease defined by increasingly frequent behavioral arrest seizures over time, thought to be due to thalamocortical network hypersynchrony. We tested the hypothesis that activity-dependent myelination resulting from absence seizures promotes epileptogenesis. Using two distinct models of absence epilepsy, Wag/Rij rats and Scn8a+/mut mice, we found increased oligodendrogenesis and myelination specifically within the absence seizure network. These changes are evident only after seizure onset in both models and are prevented with pharmacological inhibition of seizures. Genetic blockade of activity-dependent myelination during epileptogenesis markedly decreased seizure frequency in the Scn8a+/mut mouse model of absence epilepsy. Taken together, these findings indicate that activity-dependent myelination driven by absence seizures contributes to seizure kindling during epileptogenesis.

neuroscience↗

bioRxiv2017

C11orf70 mutations causing primary ciliary dyskinesia disrupt a conserved step in the intraflagellar transport-dependent assembly of multiple axonemal dyneins

Primary ciliary dyskinesia (PCD) is a genetically and phenotypically heterogeneous disorder characterized by destructive respiratory disease and laterality abnormalities due to randomised left-right body asymmetry. PCD is mostly caused by mutations affecting components of the core axoneme structure of motile cilia that are essential for cilia movement. In addition, there is a growing group of PCD genes that encode proteins essential for the assembly of the ciliary dynein motors and the active transport process that delivers them from their cytoplasmic assembly site into the axoneme. We screened a cohort of affected individuals for disease-causing mutations using a targeted next generation sequencing panel and identified 2 unrelated families (3 affected children) with mutations in the uncharacterized C11orf70 gene. The affected children share a consistent PCD phenotype from early life with laterality defects and immotile respiratory cilia displaying combined loss of inner and outer dynein arms (IDA+ODA). Phylogenetic analysis shows C11orf70 is highly conserved, distributed across species similarly to proteins involved in the intraflagellar transport (IFT)-dependant assembly of axonemal dyneins. Paramecium C11orf70 RNAi knockdown led to combined loss of ciliary IDA+ODA with reduced cilia beating and swim velocity. Fluorescently tagged C11orf70 in Paramecium and Chlamydomonas localises mainly in the cytoplasm with a small amount in the ciliary component, its abundance in the axoneme being IFT-dependant. During ciliogenesis, C11orf70 accumulates at the ciliary tips in a similar distribution to the IFT-B protein IFT46. In summary, C11orf70 is essential for IFT-dependant assembly of dynein arms and C11orf70 mutations cause defective cilia motility and PCD.

genetics↗