Inflammation-related pathology in the olfactory epithelium: its impact on the olfactory system in psychotic disorders.

Smell deficits and neurobiological changes in the olfactory bulb (OB) and olfactory epithelium (OE) have been observed in schizophrenia and related disorders. The OE is the most peripheral olfactory system located outside the cranium, and is connected with the brain via direct neuronal projections to the OB. Nevertheless, it is unknown whether and how a disturbance of the OE affects the OB in schizophrenia and related disorders. Addressing this gap would be the first step in studying the impact of OE pathology in the disease pathophysiology in the brain. In this cross-species study, we observed that chronic, local OE inflammation with a set of upregulated genes in an inducible olfactory inflammation (IOI) mouse model led to a volume reduction, layer structure changes, and alterations of neuron functionality in the OB. Furthermore, IOI model also displayed behavioral deficits relevant to negative symptoms (avolition) in parallel to smell deficits. In first episode psychosis (FEP) patients, we observed a significant alteration in immune/inflammation-related molecular signatures in olfactory neuronal cells (ONCs) enriched from biopsied OE and a significant reduction in the OB volume, compared with those of healthy controls (HC). The increased expression of immune/inflammation-related molecules in ONCs was significantly correlated to the OB volume reduction in FEP patients, but no correlation was found in HCs. Moreover, the increased expression of human orthologues of the IOI genes in ONCs was significantly correlated with the OB volume reduction in FEP, but not in HCs. Together, our study implies a potential mechanism of the OE-OB pathology in patients with psychotic disorders (schizophrenia and related disorders). We hope that this mechanism may have a cross-disease implication, including COVID-19-elicited mental conditions that include smell deficits.

Inflammation-related pathology in the olfactory epithelium: its impact on the olfactory system in psychotic disorders.

Smell deficits and neurobiological changes in the olfactory bulb (OB) and olfactory epithelium (OE) have been observed in schizophrenia and related disorders. The OE is the most peripheral olfactory system located outside the cranium, and is connected with the brain via direct neuronal projections to the OB. Nevertheless, it is unknown whether and how a disturbance of the OE affects the OB in schizophrenia and related disorders. Addressing this gap would be the first step in studying the impact of OE pathology in the disease pathophysiology in the brain. In this cross-species study, we observed that chronic, local OE inflammation with a set of upregulated genes in an inducible olfactory inflammation (IOI) mouse model led to a volume reduction, layer structure changes, and alterations of neuron functionality in the OB. Furthermore, IOI model also displayed behavioral deficits relevant to negative symptoms (avolition) in parallel to smell deficits. In first episode psychosis (FEP) patients, we observed a significant alteration in immune/inflammation-related molecular signatures in olfactory neuronal cells (ONCs) enriched from biopsied OE and a significant reduction in the OB volume, compared with those of healthy controls (HC). The increased expression of immune/inflammation-related molecules in ONCs was significantly correlated to the OB volume reduction in FEP patients, but no correlation was found in HCs. Moreover, the increased expression of human orthologues of the IOI genes in ONCs was significantly correlated with the OB volume reduction in FEP, but not in HCs. Together, our study implies a potential mechanism of the OE-OB pathology in patients with psychotic disorders (schizophrenia and related disorders). We hope that this mechanism may have a cross-disease implication, including COVID-19-elicited mental conditions that include smell deficits.

Microglial cannabinoid receptor type 1 mediates social memory deficits in mice produced by adolescent THC exposure and 16p11.2 duplication.

Adolescent cannabis use increases the risk for cognitive impairments and psychiatric disorders. Cannabinoid receptor type 1 (Cnr1) is expressed not only in neurons and astrocytes, but also in microglia, which shape synaptic connections during adolescence. However, the role of microglia in mediating the adverse cognitive effects of delta-9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, is not fully understood. Here, we report that in mice, adolescent THC exposure produces microglial apoptosis in the medial prefrontal cortex (mPFC), which was exacerbated in a model of 16p11.2 duplication, a representative copy number variation (CNV) risk factor for psychiatric disorders. These effects are mediated by microglial Cnr1, leading to reduction in the excitability of mPFC pyramidal-tract neurons and deficits in social memory in adulthood. Our findings suggest the microglial Cnr1 may contribute to adverse effect of cannabis exposure in genetically vulnerable individuals.

Microglial cannabinoid receptor type 1 mediates social memory deficits produced by adolescent THC exposure and 16p11.2 duplication.

Adolescent cannabis use increases the risk for cognitive impairments and psychiatric disorders. Cannabinoid receptor type 1 (Cnr1) is expressed not only in neurons and astrocytes, but also in microglia, which shape synaptic connections during adolescence. Nonetheless, until now, the role of microglia in mediating the adverse cognitive effects of delta-9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, has been unexplored. Here, we report that adolescent THC exposure produces microglial apoptosis in the medial prefrontal cortex (mPFC), which was exacerbated in the mouse model of 16p11.2 duplication, a representative copy number variation (CNV) risk factor for psychiatric disorders. These effects are mediated by microglial Cnr1, leading to reduction in the excitability of mPFC pyramidal-tract neurons and deficits in social memory in adulthood. Our findings highlight the importance of microglial Cnr1 to produce the adverse effect of cannabis exposure in genetically vulnerable individuals.

Loss of Astrocytic µ Opioid Receptors Exacerbates Aversion Associated with Morphine Withdrawal in Mice: Role of Mitochondrial Respiration.

Astrocytes express mu/µ opioid receptors, but the function of these receptors remains poorly understood. We evaluated the effects of astrocyte-restricted knockout of µ opioid receptors on reward- and aversion-associated behaviors in mice chronically exposed to morphine. Specifically, one of the floxed alleles of the Oprm1 gene encoding µ opioid receptor 1 was selectively deleted from brain astrocytes in Oprm1 inducible conditional knockout (icKO) mice. These mice did not exhibit changes in locomotor activity, anxiety, or novel object recognition, or in their responses to the acute analgesic effects of morphine. Oprm1 icKO mice displayed increased locomotor activity in response to acute morphine administration but unaltered locomotor sensitization. Oprm1 icKO mice showed normal morphine-induced conditioned place preference but exhibited stronger conditioned place aversion associated with naloxone-precipitated morphine withdrawal. Notably, elevated conditioned place aversion lasted up to 6 weeks in Oprm1 icKO mice. Astrocytes isolated from the brains of Oprm1 icKO mice had unchanged levels of glycolysis but had elevated oxidative phosphorylation. The basal augmentation of oxidative phosphorylation in Oprm1 icKO mice was further exacerbated by naloxone-precipitated withdrawal from morphine and, similar to that for conditioned place aversion, was still present 6 weeks later. Our findings suggest that µ opioid receptors in astrocytes are linked to oxidative phosphorylation and they contribute to long-term changes associated with opioid withdrawal.

R-loop landscapes in the developing human brain are linked to neural differentiation and cell-type specific transcription.

Here, we construct genome-scale maps for R-loops, three-stranded nucleic acid structures comprised of a DNA/RNA hybrid and a displaced single strand of DNA, in the proliferative and differentiated zones of the human prenatal brain. We show that R-loops are abundant in the progenitor-rich germinal matrix, with preferential formation at promoters slated for upregulated expression at later stages of differentiation, including numerous neurodevelopmental risk genes. RNase H1-mediated contraction of the genomic R-loop space in neural progenitors shifted differentiation toward the neuronal lineage and was associated with transcriptomic alterations and defective functional and structural neuronal connectivity in vivo and in vitro. Therefore, R-loops are important for fine-tuning differentiation-sensitive gene expression programs of neural progenitor cells.

Adenosquamous carcinoma coexisting with intraductal papillary mucinous neoplasm of the pancreas: a case report.

BACKGROUND: Adenosquamous carcinoma of the pancreas is a rare variant, with a worse prognosis than pancreatic ductal adenocarcinoma; moreover, it has characteristic clinical and histopathological features. Studies have mentioned the differentiation of intraductal papillary mucinous neoplasms into mucinous/tubular adenocarcinomas; however, their transdifferentiation into adenosquamous carcinoma remains unclear. CASE PRESENTATION: An 80-year-old Japanese woman was referred to our hospital for further examination of multiple pancreatic cysts. Enhanced computed tomography after close follow-up for 6 years revealed a new nodule with poor enhancement on the pancreatic body. Distal pancreatectomy and splenectomy were performed. Histopathological examination revealed an adenosquamous carcinoma with coexisting intraductal papillary mucinous neoplasms; moreover, the intraductal papillary mucinous neoplasms lacked continuity with the adenosquamous carcinoma. Immunohistochemical analysis revealed squamous cell carcinoma and differentiation from adenocarcinoma to squamous cell carcinoma. Gene mutation analysis revealed KRASG12D and KRASG12R mutations in adenosquamous carcinoma components and intraductal papillary mucinous neoplasm lesions, respectively, with none showing the mutation of GNAS codon 201. The final histopathological diagnosis was adenosquamous carcinoma with coexisting intraductal papillary mucinous neoplasms of the pancreas. CONCLUSIONS: This is the rare case of adenosquamous carcinoma with coexisting intraductal papillary mucinous neoplasms of the pancreas. To investigate the underlying transdifferentiation pathway of intraductal papillary mucinous neoplasms into this rare subtype of pancreatic cancer, we explored gene mutation differences as a clinicopathological parameter.

Dectin-1 signaling on colonic γδ T cells promotes psychosocial stress responses.

The intestinal immune system interacts with commensal microbiota to maintain gut homeostasis. Furthermore, stress alters the microbiome composition, leading to impaired brain function; yet how the intestinal immune system mediates these effects remains elusive. Here we report that colonic γδ T cells modulate behavioral vulnerability to chronic social stress via dectin-1 signaling. We show that reduction in specific Lactobacillus species, which are involved in T cell differentiation to protect the host immune system, contributes to stress-induced social-avoidance behavior, consistent with our observations in patients with depression. Stress-susceptible behaviors derive from increased differentiation in colonic interleukin (IL)-17-producing γδ T cells (γδ17 T cells) and their meningeal accumulation. These stress-susceptible cellular and behavioral phenotypes are causally mediated by dectin-1, an innate immune receptor expressed in γδ T cells. Our results highlight the previously unrecognized role of intestinal γδ17 T cells in the modulation of psychological stress responses and the importance of dectin-1 as a potential therapeutic target for the treatment of stress-induced behaviors.

Olfactory impairment in psychiatric disorders: Does nasal inflammation impact disease psychophysiology?

Olfactory impairments contribute to the psychopathology of mental illnesses such as schizophrenia and depression. Recent neuroscience research has shed light on the previously underappreciated olfactory neural circuits involved in regulation of higher brain functions. Although environmental factors such as air pollutants and respiratory viral infections are known to contribute to the risk for psychiatric disorders, the role of nasal inflammation in neurobehavioral outcomes and disease pathophysiology remains poorly understood. Here, we will first provide an overview of published findings on the impact of nasal inflammation in the olfactory system. We will then summarize clinical studies on olfactory impairments in schizophrenia and depression, followed by preclinical evidence on the neurobehavioral outcomes produced by olfactory dysfunction. Lastly, we will discuss the potential impact of nasal inflammation on brain development and function, as well as how we can address the role of nasal inflammation in the pathophysiological mechanisms underlying psychiatric disorders. Considering the current outbreak of Coronavirus Disease 2019 (COVID-19), which often causes nasal inflammation and serious adverse effects for olfactory function that might result in long-lasting neuropsychiatric sequelae, this line of research is particularly critical to understanding of the potential significance of nasal inflammation in the pathophysiology of psychiatric disorders.

Glutamine antagonist JHU083 improves psychosocial behavior and sleep deficits in EcoHIV-infected mice.

Combined antiretroviral therapy ushered an era of survivable HIV infection in which people living with HIV (PLH) conduct normal life activities and enjoy measurably extended lifespans. However, despite viral control, PLH often experience a variety of cognitive, emotional, and physical phenotypes that diminish their quality of life, including cognitive impairment, depression, and sleep disruption. Recently, accumulating evidence has linked persistent CNS immune activation to the overproduction of glutamate and upregulation of glutaminase (GLS) activity, particularly in microglial cells, driving glutamatergic imbalance with neurological consequences. Our lab has developed a brain-penetrant prodrug of the glutamine antagonist 6-diazo-5-oxo-L-norleucine (DON), JHU083, that potently inhibits brain GLS activity in mice following oral administration. To assess the therapeutic potential of JHU083, we infected mice with EcoHIV and characterized their neurobehavioral phenotypes. EcoHIV-infected mice exhibited decreased social interaction, suppressed sucrose preference, disrupted sleep during the early rest period, and increased sleep fragmentation, similar to what has been reported in PLH but not yet observed in murine models. At doses shown to inhibit microglial GLS, JHU083 treatment ameliorated all of the abnormal neurobehavioral phenotypes. To explore potential mechanisms underlying this effect, hippocampal microglia were isolated for RNA sequencing. The dysregulated genes and pathways in EcoHIV-infected hippocampal microglia pointed to disruptions in immune functions of these cells, which were partially restored by JHU083 treatment. These findings suggest that upregulation of microglial GLS may affect immune functions of these cells. Thus, brain-penetrable GLS inhibitors like JHU083 could act as a potential therapeutic modality for both glutamate excitotoxicity and aberrant immune activation in microglia in chronic HIV infection.

Transcranial alternating current stimulation for treating depression: a randomized controlled trial.

Treatment of depression with antidepressants is partly effective. Transcranial alternating current stimulation can provide a non-pharmacological alternative for adult patients with major depressive disorder. However, no study has used the stimulation to treat first-episode and drug-naïve patients with major depressive disorder. We used a randomized, double-blind, sham-controlled design to examine the clinical efficacy and safety of the stimulation in treating first-episode drug-naïve patients in a Chinese Han population. From 4 June 2018 to 30 December 2019, 100 patients were recruited and randomly assigned to receive 20 daily 40-min, 77.5 Hz, 15 mA, one forehead and two mastoid sessions of active or sham stimulation (n = 50 for each group) in four consecutive weeks (Week 4), and were followed for additional 4-week efficacy/safety assessment without stimulation (Week 8). The primary outcome was a remission rate defined as the 17-item Hamilton Depression Rating Scale (HDRS-17) score ≤ 7 at Week 8. Secondary analyses were response rates (defined as a reduction of ≥ 50% in the HDRS-17), changes in depressive symptoms and severity from baseline to Week 4 and Week 8, and rates of adverse events. Data were analysed in an intention-to-treat sample. Forty-nine in the active and 46 in the sham completed the study. Twenty-seven of 50 (54%) in the active treatment group and 9 of 50 (18%) in the sham group achieved remission at the end of Week 8. The remission rate was significantly higher in the active group compared to that in the sham group with a risk ratio of 1.78 (95% confidence interval, 1.29, 2.47). Compared with the sham, the active group had a significantly higher remission rate at Week 4, response rates at Weeks 4 and 8, and a larger reduction in depressive symptoms from baseline to Weeks 4 and 8. Adverse events were similar between the groups. In conclusion, the stimulation on the frontal cortex and two mastoids significantly improved symptoms in first-episode drug-naïve patients with major depressive disorder and may be considered as a non-pharmacological intervention for them in an outpatient setting.

Olfactory modulation of the medial prefrontal cortex circuitry: Implications for social cognition.

Olfactory dysfunction is manifested in a wide range of neurological and psychiatric diseases, and often emerges prior to the onset of more classical symptoms and signs. From a behavioral perspective, olfactory deficits typically arise in conjunction with impairments of cognition, motivation, memory, and emotion. However, a conceptual framework for explaining the impact of olfactory processing on higher brain functions in health and disease remains lacking. Here we aim to provide circuit-level insights into this question by synthesizing recent advances in olfactory network connectivity with other cortical brain regions such as the prefrontal cortex. We will focus on social cognition as a representative model for exploring and critically evaluating the relationship between olfactory cortices and higher-order cortical regions in rodent models. Although rodents do not recapitulate all dimensions of human social cognition, they have experimentally accessible neural circuits and well-established behavioral tests for social motivation, memory/recognition, and hierarchy, which can be extrapolated to other species including humans. In particular, the medial prefrontal cortex (mPFC) has been recognized as a key brain region in mediating social cognition in both rodents and humans. This review will highlight the underappreciated connectivity, both anatomical and functional, between the olfactory system and mPFC circuitry, which together provide a neural substrate for olfactory modulation of social cognition and social behaviors. We will provide future perspectives on the functional investigation of the olfactory-mPFC circuit in rodent models and discuss how to translate such animal research to human studies.

Hyperthermia with Chemotherapy for Unresectable Gastric Cancer in a Patient with a Vagus Nerve Stimulator Implant: A Case Report.

BACKGROUND Radiofrequency (RF) hyperthermia is commonly used as an adjunct to established treatment modalities such as chemotherapy and radiotherapy for the management of cancer patients. This case report aims to introduce the use of hyperthermia, in combination with chemotherapy, for the treatment of unresectable gastric cancer in a patient implanted with a vagus nerve stimulator (VNS). CASE REPORT A 55-year-old man with dermatomyositis, laryngeal squamous cell carcinoma in situ and double synchronous gastric cancer was found to have unresectable gastric disease during surgery despite neoadjuvant chemotherapy. Postoperatively, he received chemotherapy with RF hyperthermia. The patient had a VNS implant to treat epileptic seizures. VNS failure due to RF hyperthermia was an area of significant concern, and the procedures were completed with a full preparation to manage epileptic seizures in the event of its anticipated occurrence. Twenty-one thermotherapies were performed over 21 weeks. After 3 courses of S-1 chemotherapy (12 weeks) with RF hyperthermia without any adverse events, the regimen was changed to S-1+ CDDP combination chemotherapy (SP) and RF hyperthermia. The patient continued to receive treatment with a decrease in the size of the primary gastric tumors as well as lymph node metastases, without major adverse events, until he died due to disseminated disease. CONCLUSIONS We report the first case of unresectable gastric cancer with VNS implants in which chemo-hyperthermal therapy was safe and successful. This case report highlights the importance of providing a multidisciplinary treatment with appropriate measures for patients with intractable cancer who have received special treatments for underlying comorbidities.

Inflamed brain: Targeting immune changes and inflammation for treatment of depression.

Although there are a number of clinically effective treatments for depression, many patients exhibit treatment resistance. Recent clinical and preclinical studies reveal that peripheral and brain immune changes and inflammation are involved in the pathophysiology of depression. This 'Inflamed Brain' research provides critical clues for understanding of disease pathophysiology and many candidate molecules that are potentially useful for identifying novel drug targets for the treatment of depression. In this review, we will present clinical evidence on the role of inflammation in the pathophysiology of depression. We will also summarize current clinical trials which test drugs targeting inflammation for the treatment of patients with depression. Furthermore, we will briefly provide preclinical evidence demonstrating altered immune system function and inflammation in stress-induced animal models and will discuss the future potential of inflammation-related drug targets. Collectively, inflammatory signatures identified in clinical and preclinical studies may allow us to stratify depressive patients based on biotypes, contributing to the development of novel mechanism-based interventions that target specific patient populations.

Alterations in circulating extracellular vesicles underlie social stress-induced behaviors in mice.

Chronic stress induces peripheral and intracerebral immune changes and inflammation, contributing to neuropathology and behavioral abnormalities relevant to psychiatric disorders such as depression. Although the pathological implication of many peripheral factors such as pro-inflammatory cytokines, hormones, and macrophages has been demonstrated, the roles of circulating extracellular vesicles (EVs) for chronic stress mechanisms remain poorly investigated. Here, we report that chronic social defeat stress (CSDS)-induced social avoidance phenotype, assessed by a previously untested three-chamber social approach test, can be distinguished by multiple pro-inflammatory cytokines and EV-associated molecular signatures in the blood. We found that the expression patterns of miRNAs distinguished the CSDS-susceptible mice from the CSDS-resilient mice. Social avoidance behavior scores were also estimated with good accuracy by the expression patterns of multiple EV-associated miRNAs. We also demonstrated that EVs enriched from the CSDS-susceptible mouse sera upregulated the production of pro-inflammatory cytokines in the LPS-stimulated microglia-like cell lines. Our results indicate the role of circulating EVs and associated miRNAs in CSDS susceptibility, which may be related to pro-inflammatory mechanisms underlying stress-induced neurobehavioral outcomes.

Causal impact of local inflammation in the nasal cavity on higher brain function and cognition.

Epidemiological evidence suggests that adverse environmental factors in the nasal cavity may increase the risk for neuropsychiatric diseases. For instance, air pollution and nasal viral infection have been underscored as risk factors for Parkinson's disease, schizophrenia, and mood disorders. These adverse factors can elicit local inflammation in the nasal cavity, which may in turn influence higher brain function. Nevertheless, evidence that directly supports their causal link is missing. To fill this knowledge gap, we used an inducible mouse model for olfactory inflammation and showed the evidence that this local pathological factor can elicit behavioral abnormalities.

Efficacy of Hyperthermia in Treatment of Recurrent Metastatic Breast Cancer After Long-Term Chemotherapy: A Report of 2 Cases.

BACKGROUND Breast cancer has a long-term prognosis with various multimodality treatments. This report introduces the effectiveness of radiofrequency (RF) hyperthermia in the long-term treatment for recurrent/metastatic breast cancer. CASE REPORT In the first case, the patient had bone and liver metastases during the course of chemotherapy, hormone therapy, and radiotherapy for 27 years after curative resection of breast cancer. Finally, she received RF hyperthermia alone for liver metastasis and showed a decrease in tumor markers and reduction in liver metastasis on computed tomography (CT). In the second case, the patient underwent curative resection for multiple occurrences on the left side of the breast. She received postoperative chemotherapy combined with hormone therapy but had metachronous local recurrences. She continued hormone therapy after 2 local recurrence resections; unfortunately, she had bone, liver, and lung metastases and pleural dissemination. Eventually, the patient received RF hyperthermia combined with oral chemotherapy. Her tumor markers decreased, and CT showed disappearance of lung metastasis and improved pleural dissemination. Furthermore, the reduction of chemotherapy adverse events due to hyperthermia allowed the patient to continue chemotherapy and improved her quality of life. CONCLUSIONS We present 2 cases in which RF hyperthermia had a positive effect despite the presence of a recurrent tumor after various types of surgery, chemotherapy, and radiotherapy. This report suggests that the addition of RF hyperthermia to conventional multidisciplinary therapies may enhance the therapeutic effect of these treatments and improve the quality of life in patients with recurrent breast cancer.

Astrocyte DISC1 contributes to cognitive function in a brain region-dependent manner.

Our understanding of the contribution of genetic risk factors to neuropsychiatric diseases is limited to abnormal neurodevelopment and neuronal dysfunction. Much less is known about the mechanisms whereby risk variants could affect the physiology of glial cells. Our prior studies have shown that a mutant (dominant-negative) form of a rare but highly penetrant psychiatric risk factor, Disrupted-In-Schizophrenia-1 (DISC1), impairs metabolic functions of astrocytes and leads to cognitive dysfunction. In order to overcome the limitations of the mutant DISC1 model and understand the putative regional properties of astrocyte DISC1, we assessed whether knockdown of Disc1 (Disc1-KD) in mature mouse astrocytes of the prefrontal cortex (PFC) or the hippocampus would produce behavioral abnormalities that could be attributed to astrocyte bioenergetics. We found that Disc1-KD in the hippocampus but not PFC impaired trace fear conditioning in adult mice. Using the innovative deep learning approach and convolutional deep neural networks (cDNNs), ResNet50 or ResNet18, and single cell-based analysis, we found that Disc1-KD decreased the spatial density of astrocytes associated with abnormal levels and distribution of the mitochondrial markers and the glutamate transporter, GLAST. Disc1-KD in astrocytes also led to decreased expression of the glutamatergic and increased expression of the GABA-ergic synaptic markers, possibly via non-apoptotic activation of caspase 3 in neurons located within the individual territories of Disc1-KD astrocytes. Our results indicate that altered expression of DISC1 in astrocytes could impair astrocyte bioenergetics, leading to abnormalities in synaptic neurotransmission and cognitive function in a region-dependent fashion.

Glutamine Antagonist JHU-083 Normalizes Aberrant Hippocampal Glutaminase Activity and Improves Cognition in APOE4 Mice.

BACKGROUND: Given the emergent aging population, the identification of effective treatments for Alzheimer's disease (AD) is critical. OBJECTIVE: We investigated the therapeutic efficacy of JHU-083, a brain-penetrable glutamine antagonist, in treating AD using the humanized APOE4 knock-in mouse model. METHODS: Cell culture studies were performed using BV2 cells and primary microglia isolated from hippocampi of adult APOE4 knock-in mice to evaluate the effect of JHU-083 treatment on LPS-induced glutaminase (GLS) activity and inflammatory markers. Six-month-old APOE4 knock-in mice were administered JHU-083 or vehicle via oral gavage 3x/week for 4-5 months and cognitive performance was assessed using the Barnes maze. Target engagement in the brain was confirmed using a radiolabeled GLS enzymatic activity assay, and electrophysiology, gastrointestinal histology, blood chemistry, and CBC analyses were conducted to evaluate the tolerability of JHU-083. RESULTS: JHU-083 inhibited the LPS-mediated increases in GLS activity, nitic oxide release, and pro-inflammatory cytokine production in cultured BV2 cells and primary microglia isolated from APOE4 knock-in AD mice. Chronic treatment with JHU-083 in APOE4 mice improved hippocampal-dependent Barnes maze performance. Consistent with the cell culture findings,postmortem analyses of APOE4 mice showed increased GLS activity in hippocampal CD11b+ enriched cells versus age-matched controls, which was completely normalized by JHU-083 treatment. JHU-083 was well-tolerated, showing no weight loss effect or overt behavioral changes. Peripheral nerve function, gastrointestinal histopathology, and CBC/clinical chemistry parameters were all unaffected by chronic JHU-083 treatment. CONCLUSION: These results suggest that the attenuation of upregulated hippocampal glutaminase by JHU-083 represents a new therapeutic strategy for AD.