Effect of pseudorabies virus infection on NMDA receptor expression in mice and its role in immunosuppression.

Pseudorabies virus (PRV), an α-herpesvirus, induces immunosuppression and can lead to severe neurological diseases. N-methyl-D-aspartate receptor (NMDAR), an important excitatory nerve receptor in the central nervous system, is linked to various nervous system pathologies. The link between NMDAR and PRV-induced neurological diseases has not been studied. In vivo studies revealed that PRV infection triggers a reduction in hippocampal NMDAR expression, mediated by inflammatory processes. Extensive hippocampal neuronal degeneration was found in mice on the 6th day by hematoxylin-eosin staining, which was strongly correlated with increased NMDAR protein expression. In vitro studies utilizing the CCK-8 assay demonstrated that treatment with an NMDAR antagonist significantly heightened the cytotoxic effects of PRV on T lymphocytes. Notably, NMDAR inhibition did not affect the replication ability of PRV. However, it facilitated the accumulation of pro-inflammatory cytokines in PRV-infected T cells and enhanced the transcription of the CD25 gene through the secretion of interleukin-2 (IL-2), consequently exacerbating immunosuppression. In this study, we found that NMDAR has functional activity in T lymphocytes and is crucial for the inflammatory and immune responses triggered by PRV infection. These discoveries highlight the significant role of NMDAR in PRV-induced neurological disease pathogenesis.

Anti-CRMP2 antibody induces anxiety-like behavior and increases pyramidal neuron excitability in mice.

BACKGROUND: We have previously identified auto-antibody (Ab) to collapsin response mediator protein 2 (CRMP2) in patients with encephalitis. The present study aims to evaluate the pathogenic effects of anti-CRMP2 Ab. METHODS: Recombinant CRMP2 protein was injected subcutaneously into mice to establish an active immune mouse model with anti-CRMP2 Ab. Behavioral assessments, histopathological staining, and electrophysiological testing were performed to identify any pathogenic changes. RESULTS: The mice exhibited signs of impaired motor coordination four weeks post-immunization of CRMP2 protein. Moreover, CRMP2 immunized mice for eight weeks showed anxiety-like behaviors indicating by tests of open field and the elevated plus maze. After incubating the CA1 region of hippocampal brain section with the sera from CRMP2 immunized mice, the whole-cell path-clamp recordings showed increased excitability of pyramidal neurons. However, no obvious inflammation and infiltration of immune cells were observed by histopathological analysis. Western blot showed that the phosphorylation levels of CRMP2-Thr514 and -Ser522 were not affected. CONCLUSION: In an active immunization model with CRMP2 protein, impaired coordination and anxiety-like behaviors were observed. Also, anti-CRMP2 Abs containing sera heightened the excitability of hippocampal pyramidal neurons in vitro, which imply the pathogenic effects of anti-CRMP2 Ab.

A mouse model of schizophrenia induced by autoantibodies against SFT2D2.

Schizophrenia (SCZ) is a highly heterogeneous, severe neuropsychiatric disorder of unknown etiopathology. Increasing data indicate an overlap between schizophrenia and pathological processes related to immunological dysregulation as well as inflammation, such as high levels of pro-inflammatory substances in patients' blood and cerebrospinal fluid and autoantibodies against synaptic and nerve cell membrane proteins. Autoantibodies against SFT2D2 have been reported in patients with SCZ. However, their roles in inflammation have not yet been established. We performed a continuous intracerebroventricular infusion of polyclonal rabbit anti-SFT2D2-IgG in male C57BL/6 mice. Behavioral tests were conducted after 2 weeks of treatment. Our results showed an increased density of microglia and activated astrocytes in the primary somatosensory cortex of the anti-SFT2D2-IgG-infused mice. Quantitative reverse transcription-polymerase chain reactions showed that the expression of pro-inflammatory genes was upregulated in the primary somatosensory cortex and hippocampus of the anti-SFT2D2-IgG-infused mice. Additionally, the mice exhibited defective sensorimotor gating, memory deficits, motor impairment, and anxiety-related behaviors without signs of depression. These findings indicate that anti-SFT2D2 autoantibodies can induce encephalitis, cause a series of behavioral changes associated with schizophrenia, and offer a model for testing novel therapies to improve treatment strategies for a subgroup of patients with SCZ.

Repetitive Administration of Low-Dose Lipopolysaccharide Improves Repeated Social Defeat Stress-Induced Behavioral Abnormalities and Aberrant Immune Response.

Repetitive exposure of innate immune cells to a subthreshold dosage of endotoxin components may modulate inflammatory responses. However, the regulatory mechanisms in the interactions between the central nervous system (CNS) and the immune system remain unclear. This study aimed to investigate the effects of lipopolysaccharide (LPS) preconditioning in repeated social defeat stress (RSDS)-induced abnormal immune responses and behavioral impairments. This study aimed to elucidate the mechanisms that underlie the protective effects of repeated administration of a subthreshold dose LPS on behavioral impairments using the RSDS paradigm. LPS preconditioning improved abnormal behaviors in RSDS-defeated mice, accompanied by decreased monoamine oxidases and increased glucocorticoid receptor expression in the hippocampus. In addition, pre-treated with LPS significantly decreased the recruited peripheral myeloid cells (CD11b+CD45hi), mainly circulating inflammatory monocytes (CD11b+CD45hiLy6ChiCCR2+) into the brain in response to RSDS challenge. Importantly, we found that LPS preconditioning exerts its protective properties by regulating lipocalin-2 (LCN2) expression in microglia, which subsequently induces expressions of chemokine CCL2 and pro-inflammatory cytokine. Subsequently, LPS-preconditioning lessened the resident microglia population (CD11b+CD45intCCL2+) in the brains of the RSDS-defeated mice. Moreover, RSDS-associated expressions of leukocytes (CD11b+CD45+CCR2+) and neutrophils (CD11b+CD45+Ly6G+) in the bone marrow, spleen, and blood were also attenuated by LPS-preconditioning. In particular, LPS preconditioning also promoted the expression of endogenous antioxidants and anti-inflammatory proteins in the hippocampus. Our results demonstrate that LPS preconditioning ameliorates lipocalin 2-associated microglial activation and aberrant immune response and promotes the expression of endogenous antioxidants and anti-inflammatory protein, thereby maintaining the homeostasis of pro-inflammation/anti-inflammation in both the brain and immune system, ultimately protecting the mice from RSDS-induced aberrant immune response and behavioral changes.

Vaccination reduces central nervous system IL-1ß and memory deficits after COVID-19 in mice.

Up to 25% of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exhibit postacute cognitive sequelae. Although millions of cases of coronavirus disease 2019 (COVID-19)-mediated memory dysfunction are accumulating worldwide, the underlying mechanisms and how vaccination lowers risk are unknown. Interleukin-1 (IL-1), a key component of innate immune defense against SARS-CoV-2 infection, is elevated in the hippocampi of individuals with COVID-19. Here we show that intranasal infection of C57BL/6J mice with SARS-CoV-2 Beta variant leads to central nervous system infiltration of Ly6Chi monocytes and microglial activation. Accordingly, SARS-CoV-2, but not H1N1 influenza virus, increases levels of brain IL-1ß and induces persistent IL-1R1-mediated loss of hippocampal neurogenesis, which promotes postacute cognitive deficits. Vaccination with a low dose of adenoviral-vectored spike protein prevents hippocampal production of IL-1ß during breakthrough SARS-CoV-2 infection, loss of neurogenesis and subsequent memory deficits. Our study identifies IL-1ß as one potential mechanism driving SARS-CoV-2-induced cognitive impairment in a new mouse model that is prevented by vaccination.

Inhibition of NLRP3 inflammasome alleviates cognitive deficits in a mouse model of anti-NMDAR encephalitis induced by active immunization.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a neurological disorder, characterized by cognitive deficits as one of its vital features. The nucleotide-binding oligomerization domain-like receptor (NLRP3) inflammasome is a key contributor to neuroinflammation and cognitive deficits in neurological diseases. However, the underlying mechanism of anti-NMDAR encephalitis remains unclear, and the biological function of the NLRP3 inflammasome in this condition has not been elucidated. In this study, a mouse model of anti-NMDAR encephalitis was induced by active immunization with the GluN1356-385 peptide (NEA model). The NLRP3 inflammasome in the hippocampus and temporal cortex was investigated using real-time quantitative PCR (RT-qPCR), western blotting, and immunofluorescence staining. The impact of MCC950 on cognitive function and NLRP3 inflammation was assessed. Confocal immunofluorescence staining and Sholl analysis were employed to examine the function and morphology of microglia. In the current study, we discovered overactivation of the NLRP3 inflammasome and an enhanced inflammatory response in the NEA model, particularly in the hippocampus and temporal cortex. Furthermore, significant cognitive dysfunction was observed in the NEA model. While, MCC950, a selective inhibitor of the NLRP3 inflammasome, sharply attenuated the inflammatory response in mice, leading to mitigated cognitive deficits of mice and more regular arrangements of neurons and reduced number of hyperchromatic cells were also observed in the hippocampus area. In addition, we found that the excess elevation of NLRP3 inflammasome was mainly expressed in microglia accompanied with the overactivation of microglia, while MCC950 treatment significantly inhibited the increased number and activated morphological changes of microglia in the NEA model. Altogether, our study reveals the vital role of overactivated NLRP3 signaling pathway in aggravating the inflammatory response and cognitive deficits and the potential protective effect of MCC950 in anti-NMDAR encephalitis. Thus, MCC950 represents a promising strategy for anti-inflammation in anti-NMDAR encephalitis and our study lays a theoretical foundation for it to become a clinically targeted drug.

Priming of hippocampal microglia by IFN-γ/STAT1 pathway impairs social memory in mice.

Social behavior is inextricably linked to the immune system. Although IFN-γ is known to be involved in social behavior, yet whether and how it encodes social memory remains unclear. In the current study, we injected with IFN-γ into the lateral ventricle of male C57BL/6J mice, and three-chamber social test was used to examine the effects of IFN-γ on their social preference and social memory. The morphology of microglia in the hippocampus, prelimbic cortex and amygdala was examined using immunohistochemistry, and the phenotype of microglia were examined using immunohistochemistry and enzyme-linked immunosorbent assays. The IFN-γ-injected mice were treated with lipopolysaccharide, and effects of IFN-γ on behavior and microglial responses were evaluated. STAT1 pathway and microglia-neuron interactions were examined in vivo or in vitro using western blotting and immunohistochemistry. Finally, we use STAT1 inhibitor or minocycline to evaluated the role of STAT1 in mediating the microglial priming and effects of primed microglia in IFN-γ-induced social dysfunction. We demonstrated that 500 ng of IFN-γ injection results in significant decrease in social index and social novelty recognition index, and induces microglial priming in hippocampus, characterized by enlarged cell bodies, shortened branches, increased expression of CD68, CD86, CD74, CD11b, CD11c, CD47, IL-33, IL-1ß, IL-6 and iNOS, and decreased expression of MCR1, Arg-1, IGF-1 and BDNF. This microglia subpopulation is more sensitive to LPS challenge, which characterized by more significant morphological changes and inflammatory responses, as well as induced increased sickness behaviors in mice. IFN-γ upregulated pSTAT1 and STAT1 and promoted the nuclear translocation of STAT1 in the hippocampal microglia and in the primary microglia. Giving minocycline or STAT1 inhibitor fludarabin blocked the priming of hippocampal microglia induced by IFN-γ, ameliorated the dysfunction in hippocampal microglia-neuron interactions and synapse pruning by microglia, thereby improving social memory deficits in IFN-γ injected mice. IFN-γ initiates STAT1 pathway to induce priming of hippocampal microglia, thereby disrupts hippocampal microglia-neuron interactions and neural circuit link to social memory. Blocking STAT1 pathway or inhibiting microglial priming may be strategies to reduce the effects of IFN-γ on social behavior.

Interaction between maternal immune activation and postpartum immune stress in neuropsychiatric phenotypes.

Epidemiological evidence has shown that maternal infection is a notable risk factor for developmental psychiatric disorders. Animal models have corroborated this link and demonstrated that maternal immune activation (MIA) induces long-term behavioural deficits and neuroimmunological responses to subsequent immune stress in offspring. However, it is unclear whether MIA offspring are more sensitive or more tolerant to immunological challenges from postnatal infections. Pregnant mice were weighed and injected with a single dose of polyinosinic-polycytidylic acid (poly I:C) or saline at gestational day 9.5, and their male offspring were exposed to poly I:C or saline again during adolescence, adulthood, and middle life. After a two-week recovery from the last exposure to poly I:C, the mice underwent behavioural and neuroendophenotypic evaluations. Finally, the mice were sacrificed, and the expression levels of inflammatory factors and the activation levels of glial cells in the cerebral cortex and hippocampus were evaluated. We found MIA mice have lifelong behavioural deficits and glial activation abnormalities. Postpartum infection exposure at different ages has different consequences. Adolescent and middle life exposure prevents sensorimotor gating deficiency, but adult exposure leads to increased sensitivity to MK-801. Moreover, MIA imposed a lasting impact on the neuroimmune profile, resulting in an enhanced cytokine-associated response and diminished microglial reactivity to postnatal infection. Our results reveal an intricate interplay between prenatal and postpartum infection in neuropsychiatric phenotypes, which identify potential windows where preventive or mitigating measures could be applied.

Mitochondrial dysfunction and type I interferon signaling induce anxiodepressive-like behaviors in mice with neuropathic pain.

Clinical evidence indicates that major depression is a common comorbidity of chronic pain, including neuropathic pain; however, the cellular basis for chronic pain-mediated major depression remains unclear. Mitochondrial dysfunction induces neuroinflammation and has been implicated in various neurological diseases, including depression. Nevertheless, the relationship between mitochondrial dysfunction and anxiodepressive-like behaviors in the neuropathic pain state remains unclear. The current study examined whether hippocampal mitochondrial dysfunction and downstream neuroinflammation are involved in anxiodepressive-like behaviors in mice with neuropathic pain, which was induced by partial sciatic nerve ligation (PSNL). At 8 weeks after surgery, there was decreased levels of mitochondrial damage-associated molecular patterns, such as cytochrome c and mitochondrial transcription factor A, and increased level of cytosolic mitochondrial DNA in the contralateral hippocampus, suggesting the development of mitochondrial dysfunction. Type I interferon (IFN) mRNA expression in the hippocampus was also increased at 8 weeks after PSNL surgery. The restoration of mitochondrial function by curcumin blocked the increased cytosolic mitochondrial DNA and type I IFN expression in PSNL mice and improved anxiodepressive-like behaviors. Blockade of type I IFN signaling by anti-IFN alpha/beta receptor 1 antibody also improved anxiodepressive-like behaviors in PSNL mice. Together, these findings suggest that neuropathic pain induces hippocampal mitochondrial dysfunction followed by neuroinflammation, which may contribute to anxiodepressive-behaviors in the neuropathic pain state. Improving mitochondrial dysfunction and inhibiting type I IFN signaling in the hippocampus might be a novel approach to reducing comorbidities associated with neuropathic pain, such as depression and anxiety.

Maternal stress induced autophagy dysfunction and immune activation in the hippocampus of adolescence rat pups.

Maternal stress (MS) has long-term effects on fetal brain development and consequently increases the risk of neuropsychiatric diseases in the offspring, however, the mechanism that links between early life stress and subsequent neuropsychiatric diseases is still not clear. It is well known that both neuroinflammation and autophagy dysfunction contributes to the pathology of psychiatric disorders. We hypothesized that MS might alter autophagy function and activate the neuroimmune response in the pup's brain. To test this hypothesis, we investigated the effects of MS on the expression of the autophagy biomarker and neuroimmune response in the hippocampus of rat pups. Results revealed that MS-induced a long-term decrease of LC3B-II throughout the postnatal periods, together with an increase of IL-6 and IL-10 in the hippocampus of rat pups during adolescence. These changes lasted at least until adulthood. Results from the In vitro studies showed that a partially toxic dose of corticosterone (CORT) induced a significant decrease of LC3B-II, together with an increase of IL-6 and IL-10, in the SH-SY5Y cells. Moreover, suppression of autophagy by mycophenolic acid (MPA) leads to an increased IL-6 and IL-10 expression in the CORT-treated SH-SY5Y cells. Findings suggested that CORT decreased autophagy dysfunction could activate neuroimmune response in the SH-SY5Y cells. Results from this study provides initial evidence for the relationship between stress hormone, autophagy dysfunction, and neuroimmune activation, which may be the linking mechanism between early-life stress and subsequent neuropsychiatric disorders.

Mycobacterium vaccae immunization in rats ameliorates features of age-associated microglia activation in the amygdala and hippocampus.

Aging and reduced exposure to environmental microbes can both potentiate neuroinflammatory responses. Prior studies indicate that immunization with the immunoregulatory and anti-inflammatory bacterium, Mycobacterium vaccae (M. vaccae), in aged rats limits neuroimmune activation and cognitive impairments. However, the mechanisms by which M. vaccae immunization ameliorates age-associated neuroinflammatory "priming" and whether microglia are a primary target remain unclear. Here, we investigated whether M. vaccae immunization protects against microglia morphological changes in response to aging. Adult (3 mos) and aged (24 mos) Fisher 344 × Brown Norway rats were immunized with either M. vaccae or vehicle once every week for 3 weeks. Aging led to elevated Iba1 immunoreactivity, microglial density, and deramification of microglia processes in the hippocampus and amygdala but not other brain regions. Additionally, aged rats exhibited larger microglial somas in the dorsal hippocampus, suggestive of a more activated phenotype. Notably, M. vaccae treatment ameliorated indicators of microglia activation in both the amygdala and hippocampus. While changes in morphology appeared to be region-specific, gene markers indicative of microglia activation were upregulated by age and lowered in response to M. vaccae in all brain regions evaluated. Taken together, these data suggest that peripheral immunization with M. vaccae quells markers of age-associated microglia activation.

Effects of Stevia rebaudiana Bertoni extracts in the rat model of epilepsy induced by pentylenetetrazol: Sirt-1, at the crossroads between inflammation and apoptosis.

The current study investigated the effects of stevia extracts on a PTZ-induced epileptic rat model and its potential mechanism. Thirty male Sprague-Dawley rats were equally subdivided into 3 groups; (1) normal control (NC) group, (2) PTZ-group: received PTZ (50 mg/kg, i.p. every other day) for 2 weeks, and (3) PTZ+ Stevia group: received PTZ and stevia (200 mg/kg orally daily) for 4 weeks (2 weeks before the start of PTZ treatment and 2 weeks with PTZ administration). The first jerk latency and the seizure score were assessed in rats. Also, brain tissue samples were collected by the end of the experiment, and oxidative stress markers (catalase, MDA, and total antioxidant capacity (TAC)) were measured by biochemical analysis in hippocampal brain homogenates. Also, in the hippocampus, the expression of IL6 and Bcl-2 at the mRNA level and expression of Sirt-1, P53, caspase-3, GFAP, and NF-kB in CA3 hippocampal region by immunohistochemistry was investigated. PTZ substantially increased the seizure score and decreased the seizure latency. Also, PTZ significantly increased MDA, GFAP, IL-6, NF-kB, caspase-3, and p53 and significantly reduced Sirt-1, TAC, and Bcl-2 in hippocampal tissues compared to the control group (p < 0.01). However, Stevia Rebaudiana Bertoni (Stevia R.) significantly attenuated the PTZ-induced seizures, improved oxidative stress markers, downregulated GFAP, IL-6, NF-kB, caspase-3, and p53, and upregulated Sirt-1 and Bcl-2 in the CA3 hippocampal region (p < 0.01). In conclusion, Stevia R. exhibits neuroprotective and antiepileptic actions in PTZ-induced epilepsy due to its antioxidant, anti-apoptotic, and anti-inflammatory effects. Additionally, the Sirt-1 pathway might be involved in the antiepileptic and neuroprotective effects of stevia in PTZ-kindled epileptic rat model.

Postnatal exposure to lipopolysaccharide combined with high-fat diet consumption induces immune tolerance without prevention in spatial working memory impairment.

High-fat diet (HFD) consumption has been related to metabolic alterations, such as obesity and cardiovascular problems, and has pronounced effects on brain plasticity and memory impairment. HFD exposure has a pro-inflammatory effect associated with microglial cell modifications in the hippocampus, a region involved in the working memory process. Immune tolerance can protect from inflammation in periphery induced by HFD consumption, when the immune response is desensitized in development period with lipopolysaccharide (LPS) exposure, maybe this previously state can change the course of the diseases associated to HFDs but is not known if can protect the hippocampus's inflammatory response. In the present study, male mice were injected with LPS (100 µg.kg-1 body weight) on postnatal day 3 and fed with HFD for 16 weeks after weaning. Ours results indicated that postnatal exposure to LPS in the early postnatal developmental stage combined with HFD consumption prevented glycemia, insulin, HOMA-IR, microglial process, and increased pro-inflammatory cytokines mRNA expression, without changes in body weight gain and spatial working memory with respect vehicle + HFD group. These findings suggest that HFD consumption after postnatal LPS exposure induces hippocampal immune tolerance, without prevention in spatial working memory impairment on male mice.

Phytoestrogen genistein modulates neuron-microglia signaling in a mouse model of chronic social defeat stress.

Microglia, resident immune cells in the brain, are shown to mediate the crosstalk between psychological stress and depression. Interestingly, increasing evidence indicates that sex hormones, particularly estrogen, are involved in the regulation of immune system. In this study, we aimed to understand the potential effects of chronic social defeat stress (CSDS) and genistein (GEN), an estrogenic compound of the plant origin, on neuron-microglia interactions in the mouse hippocampus. The time spent in the avoidance zone in the social interaction test was increased by CSDS 1 day after the exposure, while the avoidance behavior returned to control levels 14 days after the CSDS exposure. Similar results were obtained from the elevated plus-maze test. However, the immobility time in the forced swim test was increased by CSDS 14 days after the exposure, and the depression-related behavior was in part alleviated by GEN. The numerical densities of microglia in the hippocampus were increased by CSDS, and they were decreased by GEN. The voxel densities of synaptic structures and synaptic puncta colocalized with microglia were decreased by CSDS, and they were increased by GEN. Neither CSDS nor GEN affected the gene expressions of major pro-inflammatory cytokines. Conversely, the expression levels of genes related to neurotrophic factors were decreased by CSDS, and they were partially reversed by GEN. These findings show that GEN may in part alleviate stress-related symptoms, and the effects of GEN may be associated with the modulation of neuron-microglia signaling via chemokines and neurotrophic factors in the hippocampus.

Innate immune stimulation prevents the development of anxiety-like behaviors in chronically stressed mice.

Anxiety is a common psychological disease which can induce severe social burdens. Searching methods that prevent the onset of anxiety is of great significance for ameliorating the social and individual problems induced by this type of disease. In this study, we investigated how innate immune pre-stimulation influences the anxiety-like behaviors in chronically stressed mice. Our results showed that a single injection of an innate immune stimulant lipopolysaccharide (LPS) at the dose of 50, 100, and 500 µg/kg 1 day before stress exposure prevented chronic social defeat stress (CSDS)-induced anxiety-like behaviors in mice. A single injection of LPS (100 µg/kg) 5 days before stress exposure produced similar preventive effects on CSDS-induced anxiety-like behaviors, while similar effects were not observed at the condition of 10-days interval between LPS injection and stress exposure. A second LPS injection 10 days after the first LPS injection or a 4 × LPS injection 10 days before stress exposure also prevented CSDS-induced anxiety-like behaviors. Moreover, a single injection of LPS (100 µg/kg) 1 day before stress exposure prevented the production of pro-inflammatory cytokines in the hippocampus and prefrontal cortex of CSDS mice. Suppression of innate immune stimulation by minocycline pretreatment simultaneously abrogated the preventive effect of LPS pre-injection (100 µg/kg) on CSDS-induced anxiety-like behaviors and pro-inflammatory cytokine production in the brain. Our results demonstrated that the pre-stimulation of the innate immune system can prevent the development of anxiety-like behaviors and the progression of the neuroinflammatory responses in the brain in chronically stressed mice.

Early Toll-like receptor 4 inhibition improves immune dysfunction in the hippocampus after hypoxic-ischemic brain damage.

Background: Toll-like receptor 4 (TLR4) is implicated in neonatal hypoxic-ischemic brain damage (HIBD), but the underlying mechanism is unclear. Hypothesis: We hypothesized that TLR4 mediates brain damage after hypoxic ischemia (HI) by inducing abnormal neuroimmune responses, including activation of immune cells and expression disorder of immune factors, while early inhibition of TLR4 can alleviate the neuroimmune dysfunction. Method: Postnatal day 7 rats were randomized into control, HI, and HI+TAK-242 (TAK-242) groups. The HIBD model was developed using the Rice-Vannucci method (the left side was the ipsilateral side of HI). TAK-242 (0.5 mg/kg) was given to rat pups in the TAK-242 group at 30 min before modeling. Immunofluorescence, immunohistochemistry, and western blotting were used to determine the TLR4 expression; the number of Iba-1+, GFAP+, CD161+, MPO+, and CD3+ cells; ICAM-1 and C3a expression; and interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, and IL-10 expression in the hippocampal CA1 region. Result: Significantly increased TLR4 expression was observed in the left hippocampus, and was alleviated by TAK-242. The significant increases in Iba-1+, MPO+, and CD161+ cells at 24 h and 7 days after HI and in GFAP+ and CD3+ T cells at 7 days after HI were also counteracted by TAK-242, but no significant differences were observed among groups at 24 h after HI. ICAM-1 expression increased 24 h after HI, while C3a expression decreased; TAK-242 also alleviated these changes. TNF-α and IL-1ß expression increased, while IL-10 expression decreased at 24 h and 7 days after HI; TAK-242 counteracted the increased TNF-α and IL-1ß expression at 24 h and the changes in IL-1ß and IL-10 at 7 days, but induced no significant differences in IL-10 expression at 24 h and TNF-α expression at 7 days. Conclusion: Early TLR4 inhibition can alleviate hippocampal immune dysfunction after neonatal HIBD.

Fermented rice bran supplementation attenuates chronic colitis-associated extraintestinal manifestations in female C57BL/6N mice.

Patients with inflammatory bowel disease (IBD) have higher incidence of extraintestinal manifestations (EIM), including liver disorders, sarcopenia, and neuroinflammation. Fermented rice bran (FRB), generated from rice bran (RB), is rich in bioactive compounds, and exhibits anti-colitis activity. However, its role in EIM prevention is still unclear. Here, for the first time, we investigated whether EIM in female C57Bl/6N mice is attenuated by FRB supplementation. EIM was induced by repeated administration of 1.5% dextran sulfate sodium (DSS) in drinking water (4 d) followed by drinking water (12 d). Mice were divided into 3 groups-control (AIN93M), 10% RB, and 10% FRB. FRB ameliorated relapsing colitis and inflammation in muscle by significantly lowering proinflammatory cytokines Tnf-α and Il-6 in serum and advanced glycation end product-specific receptor (Ager) in serum and muscle when compared with the RB and control groups. As FRB reduced aspartate aminotransferase levels and oxidative stress, it might prevent liver disorders. FRB downregulated proinflammatory cytokine and chemokine transcripts responsible for neuroinflammation in the hippocampus and upregulated mRNA expression of G protein coupled receptors (GPRs), Gpr41 and Gpr43, in small and large intestines, which may explain the FRB-mediated protective mechanism. Hence, FRB can be used as a supplement to prevent IBD-associated EIM.

Visceral adiposity, inflammation, and hippocampal function in obesity.

The 'apple-shaped' anatomical pattern that accompanies visceral adiposity increases risk for multiple chronic diseases, including conditions that impact the brain, such as diabetes and hypertension. However, distinguishing between the consequences of visceral obesity, as opposed to visceral adiposity-associated metabolic and cardiovascular pathologies, presents certain challenges. This review summarizes current literature on relationships between adipose tissue distribution and cognition in preclinical models and highlights unanswered questions surrounding the potential role of tissue- and cell type-specific insulin resistance in these effects. While gaps in knowledge persist related to insulin insensitivity and cognitive impairment in obesity, several recent studies suggest that cells of the neurovascular unit contribute to hippocampal synaptic dysfunction, and this review interprets those findings in the context of progressive metabolic dysfunction in the CNS. Signalling between cerebrovascular endothelial cells, astrocytes, microglia, and neurons has been linked with memory deficits in visceral obesity, and this article describes the cellular changes in each of these populations with respect to their role in amplification or diminution of peripheral signals. The picture emerging from these studies, while incomplete, implicates pro-inflammatory cytokines, insulin resistance, and hyperglycemia in various stages of obesity-induced hippocampal dysfunction. As in the parable of the five blind wanderers holding different parts of an elephant, considerable work remains in order to assemble a model for the underlying mechanisms linking visceral adiposity with age-related cognitive decline.

A role of Na+, K+ -ATPase in spatial memory deficits and inflammatory/oxidative stress after recurrent concussion in adolescent rats.

Sports-related concussions are particularly common during adolescence, and there is insufficient knowledge about how recurrent concussions in this phase of life alter the metabolism of essential structures for memory in adulthood. In this sense, our experimental data revealed that seven recurrent concussions (RC) in 35-day-old rats decreased short-term and long-term memory in the object recognition test (ORT) 30 days after injury. The RC protocol did not alter motor and anxious behavior and the immunoreactivity of brain-derived neurotrophic factor (BDNF) in the cerebral cortex. Recurrent concussions induced the inflammatory/oxidative stress characterized here by increased glial fibrillary acidic protein (GFAP), interleukin 1ß (IL 1ß), 4-hydroxynonenal (4 HNE), protein carbonyl immunoreactivity, and 2',7'-dichlorofluorescein diacetate oxidation (DCFH) levels and lower total antioxidant capacity (TAC). Inhibited Na+,K+-ATPase activity (specifically isoform α2/3) followed by Km (Michaelis-Menten constant) for increased ATP levels and decreased immunodetection of alpha subunit of this enzyme, suggesting that cognitive impairment after RC is caused by the inability of surviving neurons to maintain ionic gradients in selected targets to inflammatory/oxidative damage, such as Na,K-ATPase activity.

Mesenchymal stem cells regulate activation of microglia cells to improve hippocampal injury of heat stroke rats.

Heat stroke is a severe systemic inflammatory response disease caused by high fever, mainly with nervous system damage. Mesenchymal stem cells (MSCs) are currently believed to have anti-inflammation and immunomodulatory effects. Therefore, we aimed to explore the protective effect and mechanism of MSCs on heat stroke-induced excessive inflammation and neurological dysfunction. We established a heat stroke model in rats under conditions of continuous high temperature and high humidity. After modeling, rats were randomly divided into heat stroke model group, MSCs treatment group and normal temperature control group without any treatment. We performed survival analysis, neurological deficit score, histological staining of hippocampus and cerebellum, immunofluorescence staining of microglia, detection of inflammatory and chemokine levels in the hippocampus and cerebellum in each group. We found that MSCs treatment not only significantly reduced early (day 3) and late (day 28) mortality, but also prominently reduced nerve injury in heat stroke rats, and improved pathology and neuronal cell damage in the hippocampus and cerebellum. In addition, MSCs treatment can significantly inhibit the over-activation of hippocampal microglia in heat stroke rats and the levels of pro-inflammatory factors and chemokines in the hippocampus. Early treatment of MSCs can greatly promote the activation of cerebellar microglia in heat stroke rats. Meanwhile, MSCs treatment has an inhibitory effect on the level of chemokine in the cerebellum of rats in the early stage of heat stroke. In conclusion, the application of MSCs in the treatment of heat stroke in rats can significantly reduce mortality and neurological deficits and improve hippocampal damage, possibly by inhibiting the excessive activation of hippocampal microglia in heat stroke rats.