Biology subjects

Ribeiro, C. T.

Publications and source records attributed to Ribeiro, C. T..

4 recordsLinked to original sources

bioRxiv2026

Sex- and age-dependent control of dopamine function by LRRK2, and rapid reversal of dopamine release deficits in the LRRK2-G2019S knock-in mouse model of Parkinson's Disease.

No disease-modifying therapy exists for Parkinson's disease (PD). At diagnosis (~65y), ~70% of nigrostriatal dopamine (DA) axons may have degenerated, so identifying when and how striatal axon function declines is critical. LRRK2 hyperactivity is observed in LRRK2 and VPS35 familial cases, and also idiopathic PD. Thus suggests LRRK2 hyperfunction is a common pathophysiological feature of PD. LRRK2 inhibitors are currently in human trials, yet their effects on brain circuit function are poorly characterized. By optical imaging of iGluSnFR and dLight we measured striatal glutamate and DA release in WT, LRRK2 G2019S (LKI) and VPS35 D620N (VKI) knock-in mice, across adult ages and sexes, with and without LRRK2 inhibition. In WT mice, ongoing LRRK2 activity regulated DA release in an age- and sex-dependent manner. Acute inhibition reversed basal sex differences in striatal glutamate and DA release in aged mice, and potentiated DA release more in middle-aged females than males. In LKI mice, DA release declined progressively, first in males, then females, after maturation to full adulthood, and remained impaired in very old LKI and VKI mice. Release deficits in aged LKI and VKI mice were resistant to acute LRRK2 inhibition, but 2h inhibition rapidly reversed deficits in middle-aged LKI males and females. We conclude that LRRK2 activity, and inhibition effects, depend on age, sex, and genotype, with direct implications for the design and timing of current LRRK2 inhibitor clinical trials for PD.

neuroscience↗

bioRxiv2024

LRRK2 G2019S mutation incites increased cell-intrinsic neutrophil effector functions and intestinal inflammation in a model of infectious colitis

Parkinsons Disease (PD) is a progressive, neurodegenerative disorder characterised by motor and non-motor symptoms. Emerging evidence suggests a link between PD and gastrointestinal dysfunction. Constipation is frequently observed years prior to development of motor dysfunction in PD, and people with inflammatory bowel disease (IBD) are more likely to develop PD. Mutations in the leucine-rich repeat kinase 2 gene (LRRK2) account for approximately 1% of all PD cases and are associated with increased risk for IBD. Among them, LRRK2 Gly2019Ser (G2019S), located within the kinase domain, is the most common PD-associated mutation and increases kinase activity. It is unknown how LRRK2 mutation affects susceptibility to intestinal inflammation or pathogenesis of PD. Using single cell RNA sequencing (scRNAseq), we demonstrate that LRRK2 G2019S mutation promotes a dysregulated gene profile, especially within neutrophil, monocyte and {gamma}{delta} T cell populations, following Citrobacter rodentium infection in mice. Transcriptionally, LRRK2 G2019S neutrophils have a greater pro- inflammatory type I and II IFN response compared to those of WT mice. This is accompanied by an increase in neutrophil numbers in the lamina propria in LRRK2 G2019S mice. We also uncover cell-intrinsic functional defects in LRRK2 G2019S neutrophils, including increased chemotaxis, degranulation and neutrophil extracellular traps (NETosis) formation. Increased neutrophil infiltration is associated with an upregulation in Th17 immune responses, which may together contribute to the observed increase in colon pathology during infection. These findings increase our understanding of the role of PD-associated genes in immune cells and their contribution to immune dysregulation. Understanding the early perturbations driven by the LRRK2 G2019S mutation in gastrointestinal pathology may facilitate the development of biomarkers for early diagnosis and intervention in PD.

immunology↗

bioRxiv2022

Induced pluripotent stem cell-derived astrocytes from patients with schizophrenia exhibit an inflammatory phenotype that affects vascularization

Molecular and functional abnormalities of astrocytes have been implicated in the etiology and pathogenesis of schizophrenia (SCZ). In this study, we examined the proteome, inflammatory responses, and secretome effects on vascularization of human induced pluripotent stem cell (hiPSC)-derived astrocytes from patients with SCZ. Proteomic analysis revealed alterations in proteins related to immune function and vascularization. Reduced expression of the nuclear factor kappa B (NF-{kappa}B) p65 subunit was observed in these astrocytes, with no incremental secretion of cytokines after tumor necrosis factor alpha (TNF-) stimulation. Among inflammatory cytokines, secretion of interleukin (IL)-8 was found particularly elevated in SCZ-patient-derived- astrocyte conditioned medium (ASCZCM). In a chicken chorioallantoic membrane (CAM) assay, ASCZCM reduced the diameter of newly grown vessels, and this effect could be mimicked with exogenous addition of IL-8. Taken together, our results suggest that SCZ astrocytes are immunologically dysfunctional and may consequently affect vascularization through secreted factors.

neuroscience↗

bioRxiv2019

Short and long TNF-alpha exposure recapitulates canonical astrogliosis events in human induced pluripotent stem cells-derived astrocytes

Astrogliosis comprises a variety of changes in astrocytes that occur in a context-specific manner, triggered by temporally diverse signaling events that vary with the nature and severity of brain insults. However, most mechanisms underlying astrogliosis were described using animal models, which fail to reproduce some aspects of human astroglial signaling. Here, we report an in vitro model to study astrogliosis using human induced pluripotent stem cells (iPSC)-derived astrocytes which replicates aspects temporally intertwined of reactive astrocytes in vivo. We analyzed the time course of astrogliosis by measuring nuclear translocation of NF-kB, secretion of cytokines and changes in morphological phenotypes of human iPSC-derived astrocytes exposed to TNF-. It was observed the NF-kB nuclear translocation, increases either in the inflammation-related cytokines secretion and gene expression for IL-1{beta}, IL-6 and TNF- following 24 h TNF- stimulation. After 5 days, human iPSC-derived astrocytes exposed to TNF- exhibited increases in vimentin and GFAP immunolabeling, elongated shape and shrinkage of nuclei, which is typical phenotypes of astrogliosis. Moreover, about a 50% decrease in D-[3H] aspartate uptake was observed over the astrogliosis course with no evident cell damage, which suggests astrocytic dysfunction. Taken together, our results indicate that cultured human iPSC-derived astrocytes reproduce canonical events associated to astrogliosis in a time dependent fashion. Our findings may contribute to a better understanding of mechanisms governing human astrogliosis. Furthermore, the approach described here presents a potential applicability as a platform to uncover novel biomarkers and new drug targets to refrain astrogliosis associated to human brain disorders.

neuroscience↗