Biology subjects

Grimsey, N. L.

Publications and source records attributed to Grimsey, N. L..

3 recordsLinked to original sources

bioRxiv2019

Blood-spinal cord barrier leakage is not caused by neurodegeneration in amyotrophic lateral sclerosis

BackgroundAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease involving progressive degeneration of upper and lower motor neurons. Both lower motor neuron loss and the deposition of phosphorylated TDP-43 inclusions display regional patterning along the spinal cord. The blood-spinal cord barrier (BSCB) ordinarily restricts entry into the spinal cord parenchyma of blood components that are neurotoxic, but in ALS there is evidence for barrier breakdown. Here we sought to examine whether BSCB breakdown, motor neuron loss, and TDP-43 proteinopathy display the same regional patterning across and along the spinal cord.\n\nMethodsWe measured cerebrospinal fluid (CSF) hemoglobin in living ALS patients (n=87 controls, n=236 ALS) as a potential biomarker of BSCB and blood-brain barrier leakage. We then immunostained cervical, thoracic, and lumbar post mortem spinal cord tissue (n=5 controls, n=13 ALS) and employed semi-automated imaging and analysis to quantify and map lower motor neuron loss and phosphorylated TDP-43 inclusion load against hemoglobin leakage.\n\nResultsMotor neuron loss and TDP-43 proteinopathy were seen at all three levels of the ALS spinal cord, with most abundant TDP-43 deposition in the ventral grey (lamina IX) of the cervical and lumbar cord. In contrast, hemoglobin leakage was observed along the ALS spinal cord axis but was most severe in the dorsal grey and white matter in the thoracic spinal cord.\n\nConclusionsOur data show that leakage of the blood-spinal cord barrier occurs during life but at end-stage its distribution is independent from the major motor neuron pathology and is unlikely to be a major contributor to pathogenesis in ALS.

neuroscience↗

bioRxiv2019

Cannabinoid Receptor 2 (CB2) Signals via G-alpha-s and Induces IL-6 and IL-10 Cytokine Secretion in Primary Human Leukocytes

Cannabinoid receptor 2 (CB2) is a promising therapeutic target for immunological modulation. There is, however, a deficit of knowledge regarding CB2 signaling and function in human primary immunocompetent cells. We applied an experimental paradigm which closely models the in situ state of human primary leukocytes (PBMC; peripheral blood mononuclear cells) to characterize activation of a number of signaling pathways in response to a CB2-selective ligand (HU308). We observed a \"lag\" phase of unchanged cAMP concentration prior to development of classically-expected Gi-mediated inhibition of cAMP synthesis. Application of G protein inhibitors revealed that this apparent lag was a result of counteraction of Gi effects by concurrent Gs activation. Monitoring downstream signaling events, activation of p38 was mediated by Gi whereas ERK1/2 and Akt phosphorylation were mediated by Gi-coupled {beta}{gamma}. Activation of CREB integrated multiple components; Gs and {beta}{gamma} mediated [~]85% of the response, while [~]15% was attributed to Gi. Responses to HU308 had an important functional outcome - secretion of interleukins 6 (IL-6) and 10 (IL-10). IL-2, IL-4, IL-12, IL-13, IL-17A, MIP-1, and TNF- were unaffected. IL-6/IL-10 induction had a similar G protein coupling profile to CREB activation. All response potencies were consistent with that expected for HU308 acting via CB2. Additionally, signaling and functional effects were completely blocked by a CB2-selective inverse agonist, giving additional evidence for CB2 involvement. This work expands the current paradigm regarding cannabinoid immunomodulation and reinforces the potential utility of CB2 ligands as immunomodulatory therapeutics.\n\nSignificance statementCannabinoid receptor 2 (CB2) is a G protein-coupled receptor which plays a complex role in immunomodulation and is a promising target in a range of disorders with immune system involvement. However, to date the majority of the studies in this field have been performed on cell lines, rodent models, or stimulated primary cells. Here we provide a detailed account of CB2-mediated signaling in primary human immune cells under conditions which closely mimic their in vivo state. We reveal a complex signaling system involving an unprecedented CB2 signaling pathway and leading to immunomodulatory functional outcomes. This work provides not only a critical foundation impacting CB2-targeted drug discovery, but reveals important wider considerations for GPCR signaling studies and model validity.\n\nTable of Contents Summary Figure\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC=\"FIGDIR/small/663831v2_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (22K):\norg.highwire.dtl.DTLVardef@599095org.highwire.dtl.DTLVardef@2331a9org.highwire.dtl.DTLVardef@917860org.highwire.dtl.DTLVardef@75e8f7_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2019

Brodifacoum does not modulate human cannabinoid receptor-mediated hyperpolarization of AtT20 cells or inhibition of adenylyl cyclase in HEK 293 cells

BackgroundSynthetic cannabinoids are a commonly used class of recreational drugs that can have significant adverse effects. There have been sporadic reports of co-consumption of illicit drugs with rodenticides such as warfarin and brodifacoum (BFC) over the past 20 years but recently, hundreds of people have been reported to have been poisoned with a mixture of synthetic cannabinoids and BFC. We have sought to establish whether BFC directly affects cannabinoid receptors, or their activation by the synthetic cannabinoid CP55940 or the phytocannabinoid {Delta}9-tetrahydrocannabinol ({Delta}9-THC).\n\nMethodsThe effects of BFC on the hyperpolarization of wild type AtT20 cells, or AtT20 cells stably expressing human CB1- and CB2-mediated receptors, were studied using a fluorescent assay of membrane potential. The effects of BFC on CB1 and CB2 mediated inhibition of forskolin-stimulated adenylyl cyclase (AC) activation was measured using a BRET assay of cAMP levels in HEK 293 cells stably expressing human CB1 and CB2.\n\nResultsBFC did not activate CB1 or CB2 receptors, or affect the hyperpolarization of wild type AtT20 cells produced by somatostatin. BFC (10 {micro}M) did not affect the hyperpolarization of AtT20-CB1 or AtT20-CB2 cells produced by CP55940 or {Delta}9-THC. BFC (1 {micro}M) did not affect the inhibition of forskolin-stimulated AC activity by CP55940 in HEK 293 cells expressing CB1 or CB2. BFC (1 {micro}M) also failed to affect the desensitization of CB1 and CB2 signalling produced by prolonged (30 min) application of CP55940 or {Delta}9-THC to AtT20 cells.\n\nDiscussionBFC is not a cannabinoid receptor agonist, and appeared not to affect cannabinoid receptor activation. Our data suggests there is no pharmacodynamic rationale for mixing BFC with synthetic cannabinoids, however, it does not speak to whether BFC may affect synthetic cannabinoid metabolism or biodistribution. The reasons underlying the mixing of BFC with synthetic cannabinoids are unknown, and it remains to be established whether the \"contamination\" was deliberate or accidental. However, the consequences for people who ingested the mixture were often serious, and sometimes fatal, but this seems unlikely to be due to BFC action at cannabinoid receptors.

pharmacology and toxicology↗