Biology subjects

Joers, V.

Publications and source records attributed to Joers, V..

4 recordsLinked to original sources

bioRxiv2024

MHCII deletion in mouse myeloid cells alters T-cell subset frequencies and inflammatory responses to alpha-synuclein pathology and epigenetic analysis of human monocytes reveals genotype- as well as disease-dependent differentially accessible chromatin regions in the HLA locus

Major histocompatibility complex class II (MHCII) molecules are antigen presentation proteins and increased in post-mortem Parkinsons disease (PD) brain. Attempts to decrease MHCII expression have led to neuroprotection in PD mouse models. Our group reported that a SNP at rs3129882 in the MHCII gene Human leukocyte Antigen (HLA) DRA is associated with increased MHCII transcripts and surface protein and increased risk for late-onset idiopathic PD. We therefore hypothesized that decreased MHCII may mitigate dopaminergic degeneration. During an ongoing -synuclein lesion, mice with MHCII reduction in systemic and brain innate immune cells (LysMCre+I-Abfl/fl or CRE+) displayed brain T cell repertoire shifts and greater preservation of the dopaminergic phenotype in nigrostriatal terminals. Next, we investigated a human cohort to characterize the immunophenotype of subjects with and without the high-risk GG genotype at the rs3129882 SNP. We confirmed that the high-risk GG genotype is associated with peripheral changes in MHCII inducibility, frequency of CD4+ T cells, and differentially accessible chromatin regions within the MHCII locus. Although our mouse studies indicate that myeloid MHCII reduction coinciding with an intact adaptive immune system is insufficient to fully protect dopamine neurons from -synuclein-induced degeneration, our data are consistent with the overwhelming evidence implicating antigen presentation in PD pathophysiology.

immunology↗

bioRxiv2024

Biochemical fractionation of human α-Synuclein in a Drosophila model of synucleinopathies

Synucleinopathies are a group of central nervous system pathologies that are characterized by neuronal accumulation of misfolded and aggregated -synuclein in proteinaceous depositions known as Lewy Bodies (LBs). The transition of -synuclein from its physiological to pathological form has been associated with several post-translational modifications such as phosphorylation and an increasing degree of insolubility, which also correlate with disease progression in post-mortem specimens from human patients. Neuronal expression of -synuclein in model organisms, including Drosophila melanogaster, has been a typical approach employed to study its physiological effects. Biochemical analysis of -synuclein solubility via high-speed ultracentrifugation with buffers of increasing detergent strength offers a potent method for identification of -synuclein biochemical properties and the associated pathology stage. Unfortunately, the development of a robust and reproducible method for evaluation of human -synuclein solubility isolated from Drosophila tissues has remained elusive. Here, we tested different detergents for their ability to solubilize human -synuclein carrying the pathological mutation A53T from brains of aged flies. We also assessed the effect of sonication on solubility of human -synuclein and optimized a protocol to discriminate relative amounts of soluble/insoluble human -synuclein from dopaminergic neurons of the Drosophila brain. Our data established that, using a 5% SDS buffer, the 3-step protocol distinguishes between cytosolic soluble proteins in fraction 1, detergent-soluble proteins in fraction 2 and insoluble proteins in fraction 3. This protocol shows that sonication breaks down -synuclein insoluble complexes from the fly brain, making them soluble in the SDS buffer and enriching fraction 2 of the protocol.

biochemistry↗

bioRxiv2023

Modulation of cannabinoid receptor 2 alters neuroinflammation and reduces formation of alpha-synuclein aggregates in a rat model of nigral synucleinopathy

Research into the disequilibrium of microglial phenotypes has become an area of intense focus in neurodegenerative disease as a potential mechanism that contributes to chronic neuroinflammation and neuronal loss in Parkinsons disease (PD). There is growing evidence that neuroinflammation accompanies and may promote progression of alpha-synuclein (Asyn)-induced nigral dopaminergic (DA) degeneration. From a therapeutic perspective, development of immunomodulatory strategies that dampen overproduction of pro-inflammatory cytokines from chronically activated immune cells and induce a pro-phagocytic phenotype is expected to promote Asyn removal and protect vulnerable neurons. Cannabinoid receptor-2 (CB2) is highly expressed on activated microglia and peripheral immune cells, is upregulated in the substantia nigra of individuals with PD and in mouse models of nigral degeneration. Furthermore, modulation of CB2 protects against rotenone-induced nigral degeneration; however, CB2 has not been pharmacologically and selectively targeted in an Asyn model of PD. Here, we report that 7 weeks of peripheral administration of CB2 inverse agonist SMM-189 reduced phosphorylated (pSer129) alpha-synuclein in the substantia nigra compared to vehicle treatment. Additionally, SMM-189 delayed Asyn-induced immune cell infiltration into the brain as determined by flow cytometry, increased CD68 protein expression, and elevated wound-healing-immune-mediator gene expression. Additionally, peripheral immune cells increased wound-healing non-classical monocytes and decreased pro-inflammatory classical monocytes. In vitro analysis of RAW264.7 macrophages treated with lipopolysaccharide (LPS) and SMM-189 revealed increased phagocytosis as measured by the uptake of fluorescence of pHrodo E. coli bioparticles. Together, results suggest that targeting CB2 with SMM-189 skews immune cell function toward a phagocytic phenotype and reduces toxic aggregated species of Asyn. Our novel findings demonstrate that CB2 may be a target to modulate inflammatory and immune responses in proteinopathies.

immunology↗

bioRxiv2020

Sexually dimorphic responses to MPTP found in microglia, inflammation and gut microbiota in a progressive monkey model of Parkinson's disease

Inflammation has been linked to the development of nonmotor symptoms in Parkinsons disease (PD), which greatly impact patients quality of life and can often precede motor symptoms. Suitable animal models are critical for our understanding of the mechanisms underlying disease and the associated prodromal disturbances. The neurotoxin 1- methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkey model is commonly seen as a "gold standard" model that closely mimics the clinical motor symptoms and the nigrostriatal dopaminergic loss of PD, however MPTP toxicity extends to other nondopaminergic regions. Yet, there are limited reports monitoring the MPTP-induced progressive central and peripheral inflammation as well as other nonmotor symptoms such as gastrointestinal function and microbiota. The main objective of this study is to gain a broader understanding of central and peripheral inflammatory dysfunction triggered by exposure to a neurotoxicant known to degenerate nigral dopaminergic neurons in order to understand the potential role of inflammation in prodromal/pre-motor features of PD-like degeneration in a progressive non-human primate model of the disease. We measured inflammatory proteins in plasma and CSF and performed [18F]FEPPA PET scans to evaluate translocator proteins (TSPO) or microglial activation in a small cohort of rhesus monkeys (n=5) given weekly low doses of MPTP (0.2-0.8 mg/kg, im). Additionally, monkeys were evaluated for working memory and executive function using various behavior tasks and for gastrointestinal hyperpermeability and microbiota composition. Monkeys were also treated with novel TNF inhibitor XPro1595 (10mg/kg, n=3) or vehicle (n=2) every three days starting 11 weeks after the initiation of MPTP to determine whether nonmotor symptoms are tied to TNF signaling and whether XPro1595 would alter inflammation and microglial behavior in a progressive model of PD. Our analyses revealed sex-dependent sensitivity to MPTP that resulted in early microglial activation by PET, acute plasma IL-6 and CSF TNF, and earlier parkinsonism as measured by motor deficits in males compared to female monkeys. Sex differences were also identified in microbiota and their metabolites and targeted short chain fatty acids at both basal levels and in response to MPTP. Both sexes displayed cognitive impairment prior to a significant motor phenotype. Importantly, XPro1595 shifted peripheral and central inflammation, and significantly reduced CD68-immunoreactivity in the colon. As such, our findings revealed a sexually dimorphic inflammatory response to chronic MPTP treatment and suggest that males may have higher vulnerability than females to inflammation-induced degeneration. If these findings reflect potential differences in humans, these sex differences have significant implications for therapeutic development of inflammatory targets in the clinic.

neuroscience↗