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ENeuro Jun 2024Elevated intraocular pressure (IOP) triggers glaucoma by damaging the output neurons of the retina called retinal ganglion cells (RGCs). This leads to the loss of RGC...
Elevated intraocular pressure (IOP) triggers glaucoma by damaging the output neurons of the retina called retinal ganglion cells (RGCs). This leads to the loss of RGC signaling to visual centers of the brain such as the dorsolateral geniculate nucleus (dLGN), which is critical for processing and relaying information to the cortex for conscious vision. In response to altered levels of activity or synaptic input, neurons can homeostatically modulate postsynaptic neurotransmitter receptor numbers, allowing them to scale their synaptic responses to stabilize spike output. While prior work has indicated unaltered glutamate receptor properties in the glaucomatous dLGN, it is unknown whether glaucoma impacts dLGN inhibition. Here, using DBA/2J mice, which develop elevated IOP beginning at 6-7 months of age, we tested whether the strength of inhibitory synapses on dLGN thalamocortical relay neurons is altered in response to the disease state. We found an enhancement of feed-forward disynaptic inhibition arising from local interneurons along with increased amplitude of quantal inhibitory synaptic currents. A combination of immunofluorescence staining for the GABA-α1 receptor subunit, peak-scaled nonstationary fluctuation analysis, and measures of homeostatic synaptic scaling pointed to an approximately 1.4-fold increase in GABA receptors at post-synaptic inhibitory synapses, although several pieces of evidence indicate a non-uniform scaling across inhibitory synapses within individual relay neurons. Together, these results indicate an increase in inhibitory synaptic strength in the glaucomatous dLGN, potentially pointing toward homeostatic compensation for disruptions in network and neuronal function triggered by increased IOP. Elevated eye pressure in glaucoma leads to loss of retinal outputs to the dorsolateral geniculate nucleus (dLGN), which is critical for relaying information to the cortex for conscious vision. Alterations in neuronal activity, as could arise from excitatory synapse loss, can trigger homeostatic adaptations to synaptic function that attempt to maintain activity within a meaningful dynamic range, although whether this occurs uniformly at all synapses within a given neuron or is a non-uniform process is debated. Here, using a mouse model of glaucoma, we show that dLGN inhibitory synapses undergo non-uniform upregulation due to addition of post-synaptic GABA receptors. This is likely to be a neuronal adaptation to glaucomatous pathology in an important sub-cortical visual center.
PubMed: 38937109
DOI: 10.1523/ENEURO.0263-24.2024 -
ENeuro Jun 2024γ-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the adult brain which mediates its rapid effects on neuronal excitability via ionotropic GABA...
γ-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the adult brain which mediates its rapid effects on neuronal excitability via ionotropic GABA receptors. GABA levels in the brain are critically dependent upon GABA-aminotransferase (GABA-AT) which promotes its degradation. Vigabatrin, a low affinity GABA-AT inhibitor, exhibits anticonvulsant efficacy but its use is limited due to cumulative ocular toxicity. OV329 is a rationally designed, next-generation GABA-AT inhibitor with enhanced potency. We demonstrate that sustained exposure to OV329 in mice reduces GABA-AT activity and subsequently elevates GABA levels in the brain. Parallel increases in the efficacy of GABAergic inhibition were evident, together with elevations in EEG delta power. Consistent with this, OV329 exposure reduced the severity of status epilepticus and the development of benzodiazepine refractory seizures. Thus, OV329 may be of utility in treating seizure disorders and associated pathologies that result from neuronal hyperexcitability. Enhancing inhibitory control over neurons to reduce excitability is a common strategy in treating seizure disorders. Here, we describe a novel compound, OV329, which acts on a common pathway to vigabatrin to increase inhibitory signaling following a low repeated dose paradigm. In vivo application of OV329 exhibited enhanced tonic GABA signaling in mice at the synaptic level in the hippocampus, and at the network level reduced seizure severity and the development of benzodiazepine refractory seizures. This suggests OV329 may be of clinical use in the treatment of seizure disorders.
PubMed: 38937107
DOI: 10.1523/ENEURO.0137-24.2024 -
The Journal of Pharmacology and... Jun 2024Through its pathological and genetic association to Parkinson's Disease (PD), α-synuclein (α-syn) remains a favorable therapeutic target that is being investigated...
Through its pathological and genetic association to Parkinson's Disease (PD), α-synuclein (α-syn) remains a favorable therapeutic target that is being investigated using various modalities, including many passive immunotherapy approaches clinically targeting different forms of α-syn and epitopes. Whereas published studies from some immunotherapy trials have demonstrated engagement in plasma, none have shown direct drug-antigen interactions in the disease-relevant compartment, the central nervous system (CNS). Cinpanemab (BIIB054) selectively targets pathological aggregated α-syn with low affinity binding to monomeric forms. The avidity-driven binding, low drug concentration, and the very low α-syn levels plus its heterogeneous nature in cerebrospinal fluid (CSF) made it not possible to measure drug-target interactions by conventional assays. Here we overcame these challenges by using zero-length crosslinking to stabilize the BIIB054-α-syn complexes and then quantified the crosslinked complexes using a Meso Scale Discovery (MSD) electrochemiluminescence assay. CSF samples from healthy volunteers (HV, n=46) and individuals with PD (PD, n=18) from study 228HV101 (Phase I clinical trial of BIIB054), demonstrated dose- and time- dependent binding of cinpanemab to α-syn with measurable complexes detected at doses {greater than or equal to}15 mg/kg. Complex formation displayed a direct positive correlation to drug concentration (Spearman rank correlation = 0.8295 (HV), 0.8032 (PD) p < 0.0001 (HV, PD)). The observed binding of cinpanemab to α-syn in CSF is consistent with its low intrinsic affinity for α-syn monomer and provides evidence that the drug is behaving with expected binding dynamics in the central nervous system compartment. A zero-length cross-linking method with MSD detection was developed to enable quantification of cinpanemab-α-syn complexes in Phase 1 clinical CSF samples by preventing signal loss caused by their rapid dissociation. Observed dose- and time-dependent binding were consistent with cinpanemab's affinity for α-syn and provided confidence that the drug had engaged its target at the desired site of action. This is the first demonstration of α-syn binding by an antibody in clinical samples from the CNS.
PubMed: 38936981
DOI: 10.1124/jpet.124.002199 -
The Journal of Pharmacology and... Jun 2024Estrogen receptors are essential pharmacological targets for treating hormonal disorders and estrogen-dependent malignancies. Selective activation of estrogen receptor...
Estrogen receptors are essential pharmacological targets for treating hormonal disorders and estrogen-dependent malignancies. Selective activation of estrogen receptor (ER) β is hypothesized to provide therapeutic benefit with reduced risk of unwanted estrogenic side-effects associated with ERα activity. However, activating ERβ without activating α is challenging due to the high sequence and structural homology between the receptor subtypes. We assessed the impact of structural modifications to the parent compound OSU-ERβ-12 on receptor subtype binding selectivity using cell-free binding assays. Functional selectivity was evaluated by transactivation in HEK-293 cells overexpressing human or murine estrogen receptors. selectivity was examined through the uterotrophic effects of the analogs after oral administration in estrogen-naïve female mice. Furthermore, we evaluated the pharmacokinetics of the analogs following single dose IV and oral administration. Regarding selectivity, a single compound exhibited greater functional selectivity than OSU-ERβ-12 for human ERβ. However, like others in the -carborane series, its poor pharmacokinetics limit its suitability for further development. Surprisingly, and at odds with their pharmacokinetic and human activity data, most analogs potently induced uterotrophic effects in estrogen-naïve female mice. Further investigation of activity in HEK293 cells expressing murine estrogen receptors revealed species-specific differences in the ER-subtype selectivity of these analogs. Our findings highlight species-specific receptor pharmacology and the challenges it poses to characterizing developmental therapeutics in preclinical species. This study investigates - and -substituted carborane analogs targeting estrogen receptors, revealing the greater selectivity of carborane analogs for human ERβ compared to the mouse homolog. These findings shed light on the intricacies of using preclinical species in drug development to predict human pharmacology. The report also provides insights for the refinement and optimization of carborane analogs as potential therapeutic agents for estrogen-related disease states.
PubMed: 38936980
DOI: 10.1124/jpet.123.001874 -
The Journal of Pharmacology and... Jun 2024Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of chemotherapy treatment, routinely manifesting as increased pain sensitivity (allodynia) in...
Chronic administration of cannabinoid agonists ACEA (CB1), AM1241 (CB2), and CP55,940 (mixed CB1/CB2) induce sex-specific differences in tolerance and sex hormone changes in a chemotherapy-induced peripheral neuropathy.
Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of chemotherapy treatment, routinely manifesting as increased pain sensitivity (allodynia) in distal extremities. Despite its prevalence, effective treatment options are limited. Cannabinoids are increasingly being evaluated for their ability to treat chronic pain conditions, including CIPN. While previous studies have revealed sex differences in cannabinoid-mediated antinociception in acute and chronic pain models, there is a paucity of studies addressing potential sex differences in the response of CIPN to cannabinoid treatment. Therefore, we evaluated the long-term anti-allodynic efficacy of CB-selective (ACEA), CB-selective (AM1241), and CB/CB mixed (CP55,940) agonists in the cisplatin CIPN model, using both male and female mice. CB selective agonism was observed to have sex differences in the development of tolerance to anti-allodynic effects, with females developing tolerance more rapidly than males, while the anti-allodynic effects of selective CB agonism lacked tolerance development. Compound-specific changes to the female estrous cycle and female plasma estradiol levels were noted, with CB selective agonism decreasing plasma estradiol while CB selective agonism increased plasma estradiol. Chronic administration of a mixed CB/CB agonist resulted in increased mRNA expression of proinflammatory cytokines and endocannabinoid regulatory enzymes in female spinal cord tissue. Ovarian tissue was noted to have proinflammatory cytokine mRNA expression following administration of a CB acting compound while selective CB agonism resulted in decreased proinflammatory cytokines and endocannabinoid regulatory enzymes in testes. These results support the need for further investigation into the role of sex and sex hormones signaling in pain and cannabinoid-mediated antinociceptive effects. CIPN is a common side effect of chemotherapy. We have found that both CB1 and CB2 receptor agonism produce antinociceptive effects in a cisplatin CIPN model. We observed that tolerance to CB1-mediated antinociception developed faster in females and did not develop for CB¬2-mediated antinociception. Additionally, we found contrasting roles for CB1/CB¬2 receptors in the regulation of plasma estradiol in females, with CB1 agonism attenuating estradiol and CB¬2 agonism enhancing estradiol. These findings support the exploration of cannabinoid agonists for CIPN.
PubMed: 38936979
DOI: 10.1124/jpet.124.002165 -
The Journal of Dermatological Treatment Dec 2024Cutaneous infection in epidermolysis bullosa (EB) can cause significant morbidity, mortality, and dangerous sequelae. This review article aims to delve into the known... (Review)
Review
Cutaneous infection in epidermolysis bullosa (EB) can cause significant morbidity, mortality, and dangerous sequelae. This review article aims to delve into the known epidemiology of EB, highlight the disease's primary causative agents and their antimicrobial resistance spectrum. A thorough literature search was conducted using Medline, EMBASE, JBI and PubMed to gather data on the microbial landscape of EB wounds. The focus was on identifying the most common bacteria associated with EB infections and assessing their antimicrobial resistance profiles. The analysis revealed that is the most frequently identified bacterium in EB wounds, with a notable prevalence of methicillin-resistant strains (MRSA). Specific studies on mupirocin resistance further indicated rising rates of mupirocin-resistant , with one study reporting rates as high as 16.07%. Additionally, high resistance to other antibiotics, such as levofloxacin and trimethoprim/sulfamethoxazole, was observed in MRSA isolates. The findings highlight the critical need for regular resistance surveillance and the prudent use of mupirocin to manage infections effectively in EB. The multi-drug resistant nature of pathogens in EB presents a significant challenge in treatment, highlighting the importance of antimicrobial stewardship. Ultimately, given the sparse literature and the rarity of large-scale studies, further longitudinal research on the antimicrobial resistance profile of bacteria isolated from EB wounds is essential.
Topics: Humans; Epidermolysis Bullosa; Anti-Bacterial Agents; Methicillin-Resistant Staphylococcus aureus; Drug Resistance, Multiple, Bacterial; Microbial Sensitivity Tests; Wound Infection; Mupirocin; Drug Resistance, Bacterial
PubMed: 38936964
DOI: 10.1080/09546634.2024.2370424 -
Molecular & Cellular Proteomics : MCP Jun 2024Microglia are resident immune cells of the brain and regulate its inflammatory state. In neurodegenerative diseases, microglia transition from a homeostatic state to a...
Microglia are resident immune cells of the brain and regulate its inflammatory state. In neurodegenerative diseases, microglia transition from a homeostatic state to a state referred to as disease associated microglia (DAM). DAM express higher levels of proinflammatory signaling molecules, like STAT1 and TLR2, and show transitions in mitochondrial activity toward a more glycolytic response. Inhibition of Kv1.3 decreases the proinflammatory signature of DAM, though how Kv1.3 influences the response is unknown. Our goal was to identify the potential proteins interacting with Kv1.3 during transition to DAM. We utilized TurboID, a biotin ligase, fused to Kv1.3 to evaluate potential interacting proteins with Kv1.3 via mass spectrometry in BV-2 microglia following TLR4-mediated activation. Electrophysiology, western blotting, and flow cytometry were used to evaluate Kv1.3 channel presence and TurboID biotinylation activity. We hypothesized that Kv1.3 contains domain-specific interactors that vary during a TLR4-induced inflammatory response, some of which are dependent on the PDZ-binding domain on the C-terminus. We determined that the N-terminus of Kv1.3 is responsible for trafficking Kv1.3 to the cell surface and mitochondria (e.g. NUDC, TIMM50). Whereas, the C-terminus interacts with immune signaling proteins in an LPS-induced inflammatory response (e.g. STAT1, TLR2, and C3). There are 70 proteins that rely on the C-terminal PDZ-binding domain to interact with Kv1.3 (e.g. ND3, Snx3, and Sun1). Furthermore, we used Kv1.3 blockade to verify functional coupling between Kv1.3 and interferon-mediated STAT1 activation. Overall, we highlight that the Kv1.3 potassium channel functions beyond conducting the outward flux of potassium ions in an inflammatory context and that Kv1.3 modulates the activity of key immune signaling proteins, such as STAT1 and C3.
PubMed: 38936775
DOI: 10.1016/j.mcpro.2024.100809 -
Cell Reports. Medicine Jun 2024In rodents with unilateral ablation of neurons supplying dopamine to the striatum, chronic treatment with the dopamine precursor L-DOPA induces a progressive increase of...
In rodents with unilateral ablation of neurons supplying dopamine to the striatum, chronic treatment with the dopamine precursor L-DOPA induces a progressive increase of behavioral responses, a process known as behavioral sensitization. This sensitization is blunted in arrestin-3 knockout mice. Using virus-mediated gene delivery to the dopamine-depleted striatum of these mice, we find that the restoration of arrestin-3 fully rescues behavioral sensitization, whereas its mutant defective in c-Jun N-terminal kinase (JNK) activation does not. A 25-residue arrestin-3-derived peptide that facilitates JNK3 activation in cells, expressed ubiquitously or selectively in direct pathway striatal neurons, also fully rescues sensitization, whereas an inactive homologous arrestin-2-derived peptide does not. Behavioral rescue is accompanied by the restoration of JNK3 activity, as reflected by JNK-dependent phosphorylation of the transcription factor c-Jun in the dopamine-depleted striatum. Thus, arrestin-3-assisted JNK3 activation in direct pathway neurons is a critical element of the molecular mechanism underlying sensitization upon dopamine depletion and chronic L-DOPA treatment.
PubMed: 38936368
DOI: 10.1016/j.xcrm.2024.101623 -
American Society of Clinical Oncology... Jun 2024This article endeavors to navigate the clinical journey of bispecific antibodies (BsAbs), from elucidating common toxicities and management strategies to examining novel... (Review)
Review
This article endeavors to navigate the clinical journey of bispecific antibodies (BsAbs), from elucidating common toxicities and management strategies to examining novel agents and broadening access in community health care. These drugs, commonly through T-cell activation, result in shared adverse events such as cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome. Variations in target antigens and designs, however, might introduce unique toxicities for different BsAbs, warranting specific management approaches. Recent US Food and Drug Administration approvals of BsAbs targeting CD3 T cells linked to CD20 for non-Hodgkin lymphoma and to B-cell maturation antigen or GPRC5D for multiple myeloma have transformed the treatment landscape for hematologic malignancies. Emerging new agents promise further enhancement and safety, exploring novel antigen targets, innovative structures such as trispecific antibodies, and the engagement of diverse immune cells. Simultaneously, the expansion of BsAbs into community practices is underway, demanding a multifaceted strategy that encompasses educational initiatives, operational adaptations, and collaborative frameworks. This ensures comprehensive treatment access, allowing every patient, irrespective of geographical or socioeconomic status, to benefit from these advancements in cancer therapy.
Topics: Humans; Antibodies, Bispecific; Multiple Myeloma; Lymphoma; Antineoplastic Agents, Immunological
PubMed: 38935881
DOI: 10.1200/EDBK_433516 -
PloS One 2024The economic impact of gastrointestinal (GI) nematode infections on livestock production is well documented worldwide. Increasing evidence supports the hypothesis that...
The economic impact of gastrointestinal (GI) nematode infections on livestock production is well documented worldwide. Increasing evidence supports the hypothesis that parasite colonization induces significant changes in the GI tract environment and, therefore, in the landscape where the microbiota and parasites occur. Understanding the interactions between bacterial and parasite populations in the digestive tract of livestock may be useful to design parasite control strategies based on microbiota modification. The aims of this work were to investigate the impact of the oxytetracycline-mediated manipulation of the gut microbial community on the composition of GI nematode populations in naturally infected sheep and to explore changes in the GI microbial communities after nematode population treatment with the anthelmintic compound monepantel. Extensive manipulation of the GI microbiota with a therapeutic dose of the long-acting oxytetracycline formulation did not induce significant changes in the GI nematode burden. The gut microbiota of treated animals returned to control levels 17 days after treatment, suggesting strong resilience of the sheep microbial community to antibiotic-mediated microbiota perturbation. A significant decrease of the bacterial Mycoplasmataceae family (Log2FC = -4, Padj = 0.001) and a marked increase of the Methanobacteriaceae family (Log2FC = 2.9, Padj = 0.018) were observed in the abomasum of sheep receiving the monepantel treatment. While a comprehensive evaluation of the interactions among GI mycoplasma, methanobacteria and nematode populations deserves further assessment, the bacteria-nematode population interactions should be included in future control programs in livestock production. Understanding how bacteria and parasites may influence each other in the GI tract environment may substantially contribute to the knowledge of the role of microbiota composition in nematode parasite establishment and the role of the parasites in the microbiota composition.
Topics: Animals; Sheep; Gastrointestinal Microbiome; Sheep Diseases; Nematode Infections; Nematoda; Oxytetracycline; Gastrointestinal Tract; Aminoacetonitrile; Bacteria
PubMed: 38935803
DOI: 10.1371/journal.pone.0306390