Acute ketamine induces neuronal hyperexcitability and deficits in prepulse inhibition by upregulating IL-6.

Acute ketamine administration results in psychotic symptoms similar to those observed in schizophrenia and is regarded as a pharmacological model of schizophrenia. Accumulating evidence suggests that patients with schizophrenia show increased IL-6 levels in the blood and cerebrospinal fluid and that IL-6 levels are associated with the severity of psychotic symptoms. In the present study, we found that a single ketamine exposure led to increased expression of IL-6 and IL-6Rα, decreased dendritic spine density, increased expression and currents of T-type calcium channels, and increased neuron excitability in the hippocampal CA1 area 12 h after exposure. Acute ketamine administration also led to impaired prepulse inhibition (PPI) 12 h after administration. Additionally, we found that the expression of signaling molecules IKKα/ß, NF-κB, JAK2, and STAT3 was upregulated 12 h after a single ketamine injection. The decreases in dendritic spine density, the increases in calcium currents and neuron excitability, and the impairments in PPI were ameliorated by blocking IL-6 or IL-6Rα. Our findings show that blocking IL-6 or its receptor may protect hippocampal neurons from hyperexcitability, thereby ameliorating ketamine-induced psychotic effects. Our study provides additional evidence that targeting IL-6 and its receptor is a potential strategy for treating psychotic symptoms in acute ketamine-induced psychosis and schizophrenia.

GluN1 antibody causes behavioral deficits in prepulse inhibition and memory through CaMKIIß signaling.

Accumulating evidence suggests that some patients with schizophrenia have high production of autoantibodies against the N-methyl-d-aspartate receptor (NMDAR) subunit GluN1 and that these antibodies lead to cognitive impairment. However, the molecular mechanisms of the deficits seen in these patients are largely unknown. In the present study, we found that passive infusion of GluN1 antibody into the hippocampus of mice for 7 days led to decreased expression of GluN1, phosphor-Ser897-GluN1, and EphrinB2 receptor (EphB2R); deficits in long-term potentiation (LTP) and synaptic transmission in the hippocampal CA1 area; impairment in prepulse inhibition (PPI); and deterioration of recognition memory in novel object recognition test. We also found decreased expression of CaMKIIß, ERK1/2, CREB, and NF-κB after 7 days of GluN1 antibody exposure, as was the phosphorylation of these signaling molecules. The decrease in GluN1 and phosphor-Ser897-GluN1 expression and the deficits in LTP, PPI, and recognition memory were ameliorated by CaMKIIß overexpression. These results suggest that downregulation of CaMKIIß-ERK1/2-CREB-NF-κB signaling is responsiable for GluN1 antibody-associated impairment in PPI and memory and that GluN1 antibody-induced NMDAR hypofunction is the underlying mechanism of this impairment. Our findings indicate possible strategies to ameliorate NMDAR antibody-associated cognitive impairment in neuropsychiatric disease. They also provide evidence that NMDAR hypofunction is an underlying mechanism for cognitive impairment in schizophrenia.

Elevated serum levels of TNF-α, IL-6, and IL-18 in chronic methamphetamine users.

OBJECTIVE: Chronic methamphetamine use causes aberrant changes in cytokines. Our aim was to analyze the serum levels of tumor necrosis factor α (TNF-α), interleukin (IL)-6, and IL-18 in chronic methamphetamine users. Associations between cytokines levels with the demographic properties, methamphetamine use properties, and psychiatric symptoms in chronic methamphetamine users were also evaluated. METHODS: Seventy-eight chronic methamphetamine users who did not continue methamphetamine exposure since hospitalization and 64 healthy controls were enrolled. Serum levels of TNF-α, IL-6, and IL-18 were detected using an enzyme-linked immunosorbent assay. Psychopathological symptoms of chronic methamphetamine users were evaluated by the Positive and Negative Syndrome Scale, Beck Depression Inventory (BDI), and Beck Anxiety Inventory. RESULTS: Serum levels of TNF-α, IL-6, and IL-18 were significantly increased in methamphetamine users who did not continue methamphetamine exposure since hospital admission (average days since last methamphetamine use = 39.06 ± 7.48) when compared to those in controls. Serum IL-6 levels showed significant positive associations with BDI score and current frequency of methamphetamine use in chronic methamphetamine users. CONCLUSIONS: Our results suggest that increased TNF-α, IL-6, and IL-18 levels may have an important role in chronic methamphetamine use-associated psychopathological symptoms.

Comprehensive Bibliometric Analysis of the Kynurenine Pathway in Mood Disorders: Focus on Gut Microbiota Research.

Background: Emerging evidence implicates the dysregulated kynurenine pathway (KP), an immune-inflammatory pathway, in the pathophysiology of mood disorders (MD), including depression and bipolar disorder characterized by a low-grade chronic pro-inflammatory state. The metabolites of the KP, an important part of the microbiota-gut-brain axis, serve as immune system modulators linking the gut microbiota (GM) with the host central nervous system. Aim: This bibliometric analysis aimed to provide a first glimpse into the KP in MD, with a focus on GM research in this field, to guide future research and promote the development of this field. Methods: Publications relating to the KP in MD between the years 2000 and 2020 were retrieved from the Scopus and Web of Science Core Collection (WoSCC), and analyzed in CiteSpace (5.7 R5W), biblioshiny (using R-Studio), and VOSviewer (1.6.16). Results: In total, 1,064 and 948 documents were extracted from the Scopus and WoSCC databases, respectively. The publications have shown rapid growth since 2006, partly owing to the largest research hotspot appearing since then, "quinolinic acid." All the top five most relevant journals were in the neuropsychiatry field, such as Brain Behavior and Immunity. The United States and Innsbruck Medical University were the most influential country and institute, respectively. Journal co-citation analysis showed a strong tendency toward co-citation of research in the psychiatry field. Reference co-citation analysis revealed that the top four most important research focuses were "kynurenine pathway," "psychoneuroimmunology," "indoleamine 2,3-dioxygenase," and "proinflammatory cytokines," and the most recent focus was "gut-brain axis," thus indicating the role of the KP in bridging the GM and the host immune system, and together reflecting the field's research foundations. Overlap analysis between the thematic map of keywords and the keyword burst analysis revealed that the topics "Alzheimer's disease," "prefrontal cortex," and "acid," were research frontiers. Conclusion: This comprehensive bibliometric study provides an updated perspective on research associated with the KP in MD, with a focus on the current status of GM research in this field. This perspective may benefit researchers in choosing suitable journals and collaborators, and aid in the further understanding of the field's hotspots and frontiers, thus facilitating future research.

A machine learning approach to personalized dose adjustment of lamotrigine using noninvasive clinical parameters.

The pharmacokinetic variability of lamotrigine (LTG) plays a significant role in its dosing requirements. Our goal here was to use noninvasive clinical parameters to predict the dose-adjusted concentrations (C/D ratio) of LTG based on machine learning (ML) algorithms. A total of 1141 therapeutic drug-monitoring measurements were used, 80% of which were randomly selected as the "derivation cohort" to develop the prediction algorithm, and the remaining 20% constituted the "validation cohort" to test the finally selected model. Fifteen ML models were optimized and evaluated by tenfold cross-validation on the "derivation cohort," and were filtered by the mean absolute error (MAE). On the whole, the nonlinear models outperformed the linear models. The extra-trees' regression algorithm delivered good performance, and was chosen to establish the predictive model. The important features were then analyzed and parameters of the model adjusted to develop the best prediction model, which accurately described the C/D ratio of LTG, especially in the intermediate-to-high range (≥ 22.1 µg mL-1 g-1 day), as illustrated by a minimal bias (mean relative error (%) = + 3%), good precision (MAE = 8.7 µg mL-1 g-1 day), and a high percentage of predictions within ± 20% of the empirical values (60.47%). This is the first study, to the best of our knowledge, to use ML algorithms to predict the C/D ratio of LTG. The results here can help clinicians adjust doses of LTG administered to patients to minimize adverse reactions.

Chronic administration of ketamine induces cognitive deterioration by restraining synaptic signaling.

The discovery of the rapid antidepressant effects of ketamine has arguably been the most important advance in depression treatment. Recently, it was reported that repeated long-term ketamine administration is effective in preventing relapse of depression, which may broaden the clinical use of ketamine. However, long-term treatment with ketamine produces cognitive impairments, and the underlying molecular mechanisms for these impairments are largely unknown. Here, we found that chronic in vivo exposure to ketamine for 28 days led to decreased expression of the glutamate receptor subunits GluA1, GluA2, GluN2A, and GluN2B; decreased expression of the synaptic proteins Syn and PSD-95; decreased dendrite spine density; impairments in long-term potentiation (LTP) and synaptic transmission in the hippocampal CA1 area; and deterioration of learning and memory in mice. Furthermore, the reduced glutamate receptor subunit and synaptic protein expression and the LTP deficits were still observed on day 28 after the last injection of ketamine. We found that the expression and phosphorylation of CaMKIIß, ERK1/2, CREB, and NF-κB were inhibited by ketamine. The reductions in glutamate receptor subunit expression and dendritic spine density and the deficits in LTP, synaptic transmission, and cognition were alleviated by overexpression of CaMKIIß. Our study indicates that inhibition of CaMKIIß-ERK1/2-CREB/NF-κB signaling may mediate chronic ketamine use-associated cognitive impairments by restraining synaptic signaling. Hypofunction of the glutamatergic system might be the underlying mechanism accounting for chronic ketamine use-associated cognitive impairments. Our findings may suggest possible strategies to alleviate ketamine use-associated cognitive deficits and broaden the clinical use of ketamine in depression treatment.

Preliminary comparative analysis of kynurenine pathway metabolites in chronic ketamine users, schizophrenic patients, and healthy controls.

OBJECTIVE: The serum kynurenine pathway metabolites kynurenic acid (KYNA), kynurenine (KYN), and tryptophan (TRP) were examined in chronic ketamine users and in schizophrenic patients. The correlations of the metabolites with sociodemographic data, clinical characteristics, and drug use status were analyzed. METHODS: Seventy-nine healthy controls, 78 ketamine users, and 80 schizophrenic patients were recruited. Serum TRP, KYN, and KYNA levels were measured by high-performance liquid chromatography following tandem mass spectrometry (MS/MS). Psychotic symptoms were evaluated using the positive and negative syndrome scale (PANSS), the Beck Depression Inventory (BDI), and the Beck Anxiety Inventory (BAI). RESULTS: Serum levels of TRP, KYNA, and KYN (in ketamine users only) were lower in ketamine users and schizophrenic patients than in controls (p < .05). TRP and KYN were lower in ketamine users than in schizophrenic patients (p < .01). KYNA levels were positively correlated with the current frequency of ketamine use in ketamine users (p = .031), and serum KYNA levels were negatively correlated with the duration of schizophrenia (p = .015). CONCLUSION: TRP, KYNA, and KYN were lower in chronic ketamine users than in controls, and the alterations were in the same direction as those observed in schizophrenic patients.

Changes in serum TNF-α, IL-18, and IL-6 concentrations in patients with chronic schizophrenia at admission and at discharge.

OBJECTIVE: Schizophrenia is correlated with aberrant cytokine concentrations. The goal of our study was to detect the serum concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-18, and IL-6 concentrations in patients with chronic schizophrenia in the acute relapse state at admission and at discharge and to analyze the correlations between the three cytokine concentrations with psychosis symptoms. METHODS: Enzyme-linked immunosorbent assay (ELISA) was used to analyze serum concentrations of TNF-α, IL-18, and IL-6 in 68 patients with chronic schizophrenia at admission and at discharge and in 80 controls. The Positive and Negative Syndrome Scale (PANSS) was used to analyze psychosis symptoms of the patients. RESULTS: Serum concentrations of TNF-α, IL-18, and IL-6 in patients at admission were significantly elevated compared to those in controls. After treatment, IL-6 concentrations in patients at discharge were significantly reduced compared to those in patients at admission, and IL-6 concentrations showed no significant difference between patients at discharge and controls. In contrast, TNF-α and IL-18 concentrations showed no significant difference between patients at discharge and patients at admission, and TNF-α and IL-18 concentrations in patients at discharge were still significantly elevated compared to those in controls. IL-6 concentrations in patients at admission showed a positive correlation with negative scores, and IL-6 concentrations in patients at discharge showed positive correlations with positive, negative, and total scores. Reduction in IL-6 concentrations showed positive correlations with reduction in positive, negative, and total scores in patients at discharge. CONCLUSION: Serum concentrations of TNF-α, IL-18, and IL-6 were significantly elevated in patients with chronic schizophrenia in the acute relapse state. After treatment, IL-6 concentrations in patients at discharge were significantly reduced compared to these in patients at admission.

Altered serum levels of TNF-α, IL-6, and IL-18 in depressive disorder patients.

OBJECTIVE: Depressive disorder is associated with abnormal changes in cytokines levels. This study aimed to assess serum concentrations of tumor necrosis factor (TNF) α, interleukin (IL) 6, and IL-18 in depressive patients. The correlations between these three cytokine concentrations and the patients' clinical characteristics were also assessed. METHODS: Serum TNF-α, IL-6, and IL-18 concentrations were assessed using enzyme-linked immunosorbent assay from 64 depressive patients and 80 healthy control subjects. Depressive symptoms of patients were assessed using Hamilton Depression Scale-17. RESULTS: Depressive patients had increased serum TNF-α and IL-6 concentrations but decreased IL-18 concentrations than controls. TNF-α and IL-6 concentrations were significantly positively associated with Hamilton Depression Scale-17 scores in depressive patients. CONCLUSION: These findings provided additional evidence that altered TNF-α, IL-6, and IL-18 activities may contribute to the pathophysiology of depressive disorder.

Altered serum levels of TNF-α, IL-6 and IL-18 in manic, depressive, mixed state of bipolar disorder patients.

Bipolar disorder (BD) is associated with alterations of cytokines in the immune system. The aim of this study was to assess the serum levels of TNF-α, IL-6 and IL-18 in manic, depressive, mixed state patients of BD. The correlations between the serum cytokines levels with the demographic characteristics and the psychiatric symptoms were also assessed. We measured serum TNF-α, IL-6 and IL-18 levels using an enzyme-linked immunosorbent assay (ELISA) from 59 BD patients (37 in manic state, 12 in depressive state, 10 in mixed state) and 80 healthy control subjects. The psychotic symptoms of BD were assessed using the Hamilton Depression Scale (HAMD) and the Young Mania Rating Scale (YMRS). The results showed that serum TNF-α and IL-6 levels in manic, depressive and mixed state BD patients were significantly higher than that in controls, while serum IL-18 level was only significantly higher in depressive patients. Serum IL-6 level was significantly positively correlated with YMRS scores in manic episode as well as in mixed episode. When gender and age were added as potentially confounding covariate terms, the differences between controls and each mood state patients were still significant. Our findings provided additional evidence that elevated TNF-α, IL-6 and IL-18 pathway activities may be involved in the psychopathology of BD. Due to the lack of controlling important confounding factors, such as BMI, smoking status and alcohol use, further studies are required to confirm the roles of TNF-α, IL-6 and IL-18.

Relationship of serum levels of TNF-α, IL-6 and IL-18 and schizophrenia-like symptoms in chronic ketamine abusers.

OBJECTIVE: Exposing to NMDAR receptor antagonists, such as ketamine, produces schizophrenia-like symptoms in humans and deteriorates symptoms in schizophrenia patients. Meanwhile, schizophrenia is associated with alterations of cytokines in the immune system. This study aims to examine the serum TNF-α, IL-6 and IL-18 levels in chronic human ketamine users as compared to healthy subjects. The correlations between the serum cytokines levels with the demographic, ketamine use characteristics and psychiatric symptoms were also assessed. METHODS: 155 subjects who fulfilled the criteria of ketamine dependence and 80 healthy control subjects were recruited. Serum TNF-α, IL-6 and IL-18 levels were measured using an enzyme-linked immunosorbent assay (ELISA). The psychiatric symptoms of the ketamine abusers were assessed using the Positive and Negative Syndrome Scale (PANSS). RESULTS: Serum IL-6 and IL-18 levels were significantly higher, while serum TNF-α level was significantly lower among ketamine users than among healthy controls (p<0.05). Serum TNF-α levels showed a significant negative association with PANSS total score (r=-0.210, p<0.01) and negative subscore (r=-0.300, p<0.01). No significant association was found between PANSS score and serum levels of IL-6 and IL-18. CONCLUSIONS: Serum levels of TNF-α, IL-6 and IL-18 were altered in chronic ketamine abusers which may play a role in schizophrenia-like symptoms in chronic ketamine abusers.

Replacement of pr gene with Japanese encephalitis virus pr using reverse genetics reduces antibody-dependent enhancement of dengue virus 2 infection.

Severe dengue is more likely found during secondary heterologous dengue virus (DENV) infection or primary infection of infants born to dengue-immune mothers and led to the hypothesis of antibody-dependent enhancement (ADE). It has been reported that pre-membrane (prM)-reactive antibodies do not efficiently neutralize DENV infection but instead potently promote ADE infection. Meanwhile, these enhancing anti-prM antibodies mainly react with the precursor (pr) peptide. To evaluate the effect of pr gene substitution on neutralization and ADE of DENV infection, a novel chimeric dengue virus (JEVpr/DENV2) was rationally constructed by replacing the DENV pr gene with Japanese encephalitis virus (JEV) pr gene, based on the full-length infectious complementary DNA (cDNA) clone of DENV2 ZS01/01. We found that chimeric JEVpr/DENV2 showed reduced virulence and good immunogenicity. In addition, anti-JEVpr/DENV2 sera showed broad cross-reactivity and efficient neutralizing activity with all four DENV serotypes and immature DENV2 (ImDENV2). Most importantly, compared with anti-DENV2 sera, anti-JEVpr/DENV2 sera showed significantly reduced enhancing activity of DENV infection in K562 cells. These results suggest that the ADE activities could be reduced by replacing the DENV pr gene with JEV pr gene. These findings may help us better understand the pathogenesis of DENV infection and provide a reference for the development of a vaccine against DENV.

Comprehensive mapping infection-enhancing epitopes of dengue pr protein using polyclonal antibody against prM.

Dengue vaccine development is considered a global public health priority, but the antibody-dependent enhancement (ADE) issues have critically restricted vaccine development. Recent findings have demonstrated that pre-membrane (prM) protein was involved in dengue virus (DENV) infection enhancement. Although the importance of prM antibodies have been well characterized, only a few epitopes in DENV prM protein have ever been identified. In this study, we screened five potential linear epitopes located at positions pr1 (1-16aa), pr3 (13-28aa), pr4 (19-34aa), pr9 (49-64aa), and pr10 (55-70aa) in pr protein using peptide scanning and comprehensive bioinformatics analysis. Then, we found that only pr4 (19-34aa) could elicit high-titer antibodies in Balb/c mice, and this epitope could react with sera from DENV2-infected patients, suggesting that specific antibodies against epitope peptide pr4 were elicited in both DENV-infected mice and human. In addition, our data demonstrated that anti-pr4 sera showed limited neutralizing activity but significant ADE activity toward standard DENV serotypes and imDENV. Hence, it seems responsible to hypothesize that anti-pr4 serum was infection-enhancing antibody and pr4 was infection-enhancing epitope. In conclusion, we characterized a novel infection-enhancing epitope on dengue pr protein, a finding that may provide new insight into the pathogenesis of DENV infection and contribute to dengue vaccine design.

Identification of a novel infection-enhancing epitope on dengue prM using a dengue cross-reacting monoclonal antibody.

BACKGROUND: Dengue virus (DENV) infection is the most important arthropod- borne viral disease in human, but antiviral therapy and approved vaccines remain unavailable due to antibody-dependent enhancement (ADE) phenomenon. Many studies showed that pre-membrane (prM)-specific antibodies do not efficiently neutralize DENV infection but potently promote ADE infection. However, most of the binding epitopes of these antibodies remain unknown. RESULTS: In the present study, we characterized a DENV cross-reactive monoclonal antibody (mAb), 4D10, that neutralized poorly but potently enhanced infection of four standard DENV serotypes and immature DENV (imDENV) over a broad range of concentration. In addition, the epitope of 4D10 was successfully mapped to amino acid residues 14 to18 of DENV1-4 prM protein using a phage-displayed peptide library and comprehensive bioinformatics analysis. We found that the epitope was DENV serocomplex cross-reactive and showed to be highly immunogenic in Balb/c mice. Furthermore, antibody against epitope peptide PL10, like 4D10, showed broad cross-reactivity and weak neutralizing activtity with four standard DENV serotypes and imDENV but significantly promoted ADE infection. These results suggested 4D10 and anti-PL10 sera were infection-enhancing antibodies and PL10 was infection-enhancing epitope. CONCLUSIONS: We mapped the epitope of 4D10 to amino acid residues 14 to18 of DENV1-4 prM and found that this epitope was infection-enhancing. These findings may provide significant implications for future vaccine design and facilitate understanding the pathogenesis of DENV infection.

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 August 2009-30 September 2009.

This article documents the addition of 238 microsatellite marker loci and 72 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Adelges tsugae, Artemisia tridentata, Astroides calycularis, Azorella selago, Botryllus schlosseri, Botrylloides violaceus, Cardiocrinum cordatum var. glehnii, Campylopterus curvipennis, Colocasia esculenta, Cynomys ludovicianus, Cynomys leucurus, Cynomys gunnisoni, Epinephelus coioides, Eunicella singularis, Gammarus pulex, Homoeosoma nebulella, Hyla squirella, Lateolabrax japonicus, Mastomys erythroleucus, Pararge aegeria, Pardosa sierra, Phoenicopterus ruber ruber and Silene latifolia. These loci were cross-tested on the following species: Adelges abietis, Adelges cooleyi, Adelges piceae, Pineus pini, Pineus strobi, Tubastrea micrantha, three other Tubastrea species, Botrylloides fuscus, Botrylloides simodensis, Campylopterus hemileucurus, Campylopterus rufus, Campylopterus largipennis, Campylopterus villaviscensio, Phaethornis longuemareus, Florisuga mellivora, Lampornis amethystinus, Amazilia cyanocephala, Archilochus colubris, Epinephelus lanceolatus, Epinephelus fuscoguttatus, Symbiodinium temperate-A clade, Gammarus fossarum, Gammarus roeselii, Dikerogammarus villosus and Limnomysis benedeni. This article also documents the addition of 72 sequencing primer pairs and 52 allele specific primers for Neophocaena phocaenoides.