Differential regulation of innate immune system in frontal cortex and hippocampus in a "double-hit" neurodevelopmental model in rats.

Neurodevelopmental disorders (NDs) are neuropsychiatric conditions affecting central nervous system development, characterized by cognitive and behavioural alterations. Inflammation has been recently linked to NDs. Animal models are essential for understanding their pathophysiology and identifying therapeutic targets. Double-hit models can reproduce neurodevelopmental and neuroinflammatory impairments. Sixty-seven newborn rats were assigned to four groups: Control, Maternal deprivation (MD, 24-h-deprivation), Isolation (Iso, 5 weeks), and Maternal deprivation â€‹+ â€‹Isolation (MD â€‹+ â€‹Iso, also known as double-hit). Cognitive dysfunction was assessed using behavioural tests. Inflammasome, MAPKs, and TLRs inflammatory elements expression in the frontal cortex (FC) and hippocampus (HP) was analysed through western blot and qRT-PCR. Oxidative/nitrosative (O/N) evaluation and corticosterone levels were measured in plasma samples. Double-hit group was affected in executive and working memory. Most inflammasomes and TLRs inflammatory responses were increased in FC compared to the control group, whilst MAPKs were downregulated. Conversely, hippocampal inflammasome and inflammatory components were reduced after the double-hit exposure, while MAPKs were elevated. Our findings reveal differential regulation of innate immune system components in FC and HP in the double-hit group. Further investigations on MAPKs are necessary to understand their role in regulating HP neuroinflammatory status, potentially linking our MAPKs results to cognitive impairments through their proliferative and anti-inflammatory activity.

Neighborhood Vulnerability and Disability in First Episode of Psychosis: A Multilevel Study.

Objective: Neighborhood socioeconomic status seems to be related to functioning in patients with first episode of psychosis (FEP). The present study aimed to assess if neighborhood vulnerability and risk of social exclusion could predict functional outcomes in people with FEP after controlling for other key variables identified in previous literature.Methods: A total of 137 patients with FEP (DSM-IV-TR criteria) and 90 controls comprised the study sample from February 2013 to May 2019. Functioning was assessed with the WHO Disability Assessment Schedule. Neighborhood vulnerability was measured using a multidimensional socioeconomic deprivation index; data for the index were collected by the Madrid City Council and based on the participant's home address. Multilevel mixed-effects regression analyses were conducted to estimate the effects of neighborhood vulnerability on functioning.Results: Our results show that FEP patients could be more vulnerable to the effects of neighborhood-level characteristics than healthy controls (B = 1,570.173; z = 3.91; P < .001). In addition, our findings suggest that higher neighborhood vulnerability is related to greater functional disability in people with FEP, after controlling for other relevant confounders (B = 1,230.332; z = 2.59; P = .010).Conclusions: These results highlight the importance of incorporating contextual factors into assessment of patients with FEP, since psychosocial difficulties observed in these patients could be partially related to the quality of neighborhood social-related resources.

Challenging functional connectivity data: machine learning application on essential tremor recognition.

BACKGROUND AND AIMS: This paper aimed to investigate the usefulness of applying machine learning on resting-state fMRI connectivity data to recognize the pattern of functional changes in essential tremor (ET), a disease characterized by slight brain abnormalities, often difficult to detect using univariate analysis. METHODS: We trained a support vector machine with a radial kernel on the mean signals extracted by 14 brain networks obtained from resting-state fMRI scans of 18 ET and 19 healthy control (CTRL) subjects. Classification performance between pathological and control subjects was evaluated using a tenfold cross-validation. Recursive feature elimination was performed to rank the importance of the extracted features. Moreover, univariate analysis using Mann-Whitney U test was also performed. RESULTS: The machine learning algorithm achieved an AUC of 0.75, with four networks (language, primary visual, cerebellum, and attention), which have an essential role in ET pathophysiology, being selected as the most important features for classification. By contrast, the univariate analysis was not able to find significant results among these two conditions. CONCLUSION: The machine learning approach identifies the changes in functional connectivity of ET patients, representing a promising instrument to discriminate specific pathological conditions and find novel functional biomarkers in resting-state fMRI studies.

Models of microglia depletion and replenishment elicit protective effects to alleviate vascular and neuronal damage in the diabetic murine retina.

Microglia, the resident phagocytes of the retina, are believed to influence the development of retinopathy, but their exact contributions to vascular integrity and neuronal loss are unknown. Therefore, utilizing two models of microglia depletion, we aimed to deplete and repopulate microglia to clarify the contribution of microglia to neuronal loss and vascular damage in the diabetic retina in an STZ-induced model of hyperglycemia. Here, we report that 2 weeks exposure to diphtheria toxin (DTx) in diabetic CX3CR1CreER:R26iDTR transgenic mice induced a 62% increase in Iba1+ microglia associated with an increase in TUJ1+ axonal density and prevention of NeuN+RBPMS+ neuronal loss. Conversely, diabetic PBS controls exhibited robust TUJ1+ axonal and NeuN+RBPMS+ neuronal loss compared to non-diabetic controls. A 2-week recovery period from DTx was associated with a 40% reduction in angiogenesis and an 85% reduction in fibrinogen deposition into the diabetic retina in comparison to diabetic PBS-treated controls. Analysis of microglia morphology and marker expression revealed that following a 2-week recovery period microglia displayed a P2RY12+Ly6C- phenotype and high transformation index (TI) values complimented by a ramified-surveillant morphology closely resembling non-diabetic controls. In contrast, diabetic PBS-treated control mice displayed P2RY12+Ly6C+ microglia, with a 50% reduction in TI values with an amoeboid morphology. To validate these observations were due to microglia depletion, we used PLX-5622 to assess vascular and neuronal damage in the retinas of diabetic mice. Confocal microscopy revealed that PLX-5622 also induced an increase in TUJ1+ axonal density and prevented fibrinogen extravasation into the diabetic retina. mRNAseq gene expression analysis in retinal isolates revealed that PLX-5622-induced microglia depletion and repopulation induced a downregulation in genes associated with microglial activation and phagocytosis, B2m, Cx3cr1, and Trem2, and complement-associated synaptic pruning, C1qa, C1qb, and C1qc. Although the levels of microglia depletion induced with DTx in the CX3CR1CreER:R26iDTR model and those induced with the CSF-1R antagonists are distinct, our results suggest that microglia depletion and replenishment is neuroprotective by inducing the proliferation of a homeostatic microglia pool that supports neuronal and vascular integrity.

Noradrenaline in Alzheimer's Disease: A New Potential Therapeutic Target.

A growing body of evidence demonstrates the important role of the noradrenergic system in the pathogenesis of many neurodegenerative processes, especially Alzheimer's disease, due to its ability to control glial activation and chemokine production resulting in anti-inflammatory and neuroprotective effects. Noradrenaline involvement in this disease was first proposed after finding deficits of noradrenergic neurons in the locus coeruleus from Alzheimer's disease patients. Based on this, it has been hypothesized that the early loss of noradrenergic projections and the subsequent reduction of noradrenaline brain levels contribute to cognitive dysfunctions and the progression of neurodegeneration. Several studies have focused on analyzing the role of noradrenaline in the development and progression of Alzheimer's disease. In this review we summarize some of the most relevant data describing the alterations of the noradrenergic system normally occurring in Alzheimer's disease as well as experimental studies in which noradrenaline concentration was modified in order to further analyze how these alterations affect the behavior and viability of different nervous cells. The combination of the different studies here presented suggests that the maintenance of adequate noradrenaline levels in the central nervous system constitutes a key factor of the endogenous defense systems that help prevent or delay the development of Alzheimer's disease. For this reason, the use of noradrenaline modulating drugs is proposed as an interesting alternative therapeutic option for Alzheimer's disease.

Cognitive functioning in essential tremor without dementia: a clinical and imaging study.

BACKGROUND AND AIMS: To explore the cognitive functioning of ET patients without dementia and delineate its imaging counterpart. METHODS: We enrolled 99 subjects (49 non-demented ET patients and 50 education-matched healthy controls) that underwent neuropsychological and MRI evaluation. In order to identify the cognitive parameters that better reflect the profile of ET patients, we used a double statistical approach: (i) direct comparison between groups and (ii) machine learning approach with feature selection. Then, to evaluate the correlation between cognitive performances and the degree of brain atrophy in the ET group, we included the results derived from the uni- and multivariate analysis in whole-brain voxel-based morphometry (VBM) model. RESULTS: In ET patients, the univariate analysis showed differences in cognitive tests evaluating executive functions (FAB, MCST-CA), verbal memory-delayed recall (RAVLT-DR), and working memory (Digit Span B). The relative scores were significantly worse compared to controls, although within the normal range (subclinical dysfunctions). The machine learning approach also provided similar findings: tests exploring the executive functions, verbal memory, and language (RAVLT-DR, FAB, COWAT, RAVLT-IR, TOKEN) showed the highest importance rank in classification's task. Regardless of the explored test, the MRI analysis revealed a correlation (p < 0.005 uncorrected, whole brain) between test scores and widespread areas including cerebellum, inferior and middle frontal cortices, cingulate cortices, and temporal cortex. CONCLUSION: This study improves the knowledge on cognitive impairment in ET, as our findings demonstrate a heterogeneous pattern of cognitive dysfunction involving memory, executive function, and language domains in the ET group. This clinical profile relates with the deep involvement of the cerebellum and its connections with large-scale brain structures, suggesting that changes spreading in wide-ranging brain pathways may contribute to the physiopathology of cognitive dysfunction in ET.

CCL2 Inhibition of Pro-Resolving Mediators Potentiates Neuroinflammation in Astrocytes.

The chemokine CCL2 participates in multiple neuroinflammatory processes, mainly through the recruitment of glial cells. However, CCL2 has also been proven to exert different types of actions on these cells, including the modification of their response to inflammatory stimuli. In the present study we analyzed the effect of CCL2 on the resolution of inflammation in astrocytes. We observed that genetic removal of CCL2 increases the expression of the enzymes responsible for the synthesis of specialized pro-resolving mediators arachidonate 15-lipoxygenase and arachidonate 5-lipoxygenase in the brain cortex of 5xFAD mice. The expression of FPR2 receptor, known to mediate the activity of pro-resolving mediators was also increased in mice lacking CCL2.The downregulation of these proteins by CCL2 was also observed in cultured astrocytes. This suggests that CCL2 inhibition of the resolution of inflammation could facilitate the progression of neuroinflammatory processes. The production of the pro-inflammatory cytokine IL-1beta by astrocytes was analyzed, and allowed us to confirm that CCL2 potentiates the activation of astrocytes trough the inhibition of pro-resolving pathways mediated by Resolvin D1. In addition, the analysis of the expression of TNFalpha, MIP1alpha and NOS2 further confirmed CCL2 inhibition of inflammation resolution in astrocytes.

Neuroplasticity and inflammatory alterations in the nucleus accumbens are corrected after risperidone treatment in a schizophrenia-related developmental model in rats.

Increased dopaminergic activity in the striatum underlies the neurobiology of psychotic symptoms in schizophrenia (SZ). Beyond the impaired connectivity among the limbic system, the excess of dopamine could lead to inflammation and oxidative/nitrosative stress. It has been suggested that atypical antipsychotic drugs attenuate psychosis not only due to their modulatory activity on the dopaminergic/serotonergic neurotransmission but also due to their anti-inflammatory/antioxidant effects. In such a manner, we assessed the effects of the atypical antipsychotic risperidone (RISP) on the structural neuroplasticity and biochemistry of the striatum in adult rats with neonatal ventral hippocampus lesion (NVHL), which is a developmental SZ-related model. RISP administration (0.25 mg/kg, i.p.) ameliorated the neuronal atrophy and the impairments in the morphology of the dendritic spines in the spiny projection neurons (SPNs) of the ventral striatum (nucleus accumbens: NAcc) in the NVHL rats. Also, RISP treatment normalized the pro-inflammatory pathways and induced the antioxidant activity of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in this model. Our results point to the neurotrophic, anti-inflammatory, and antioxidant effects of RISP, together with its canonical antipsychotic mechanism, to enhance striatum function in animals with NVHL.

How does neighbourhood socio-economic status affect the interrelationships between functioning dimensions in first episode of psychosis? A network analysis approach.

The links between psychosis and socio-economic disadvantage have been widely studied. No previous study has analysed the interrelationships and mutual influences between functioning dimensions in first episode of psychosis (FEP) according to their neighbourhood household income, using a multidimensional and transdiagnostic perspective. 170 patients and 129 controls, participants in an observational study (AGES-CM), comprised the study sample. The WHO Disability Assessment Schedule (WHODAS 2.0) was used to assess functioning, whereas participants' postcodes were used to obtain the average household income for each neighbourhood, collected by the Spanish National Statistics Institute (INE). Network analyses were conducted with the aim of defining the interrelationships between the different dimensions of functioning according to the neighbourhood household income. Our results show that lower neighbourhood socioeconomic level is associated with lower functioning in patients with FEP. Moreover, our findings suggest that "household responsibilities" plays a central role in the disability of patients who live in low-income neighbourhoods, whereas "dealing with strangers" is the most important node in the network of patients who live in high-income neighbourhoods. These results could help to personalize treatments, by allowing the identification of potential functioning areas to be prioritized in the treatment of FEP according to the patient's neighbourhood characteristics.

Microglial CX3CR1 production increases in Alzheimer's disease and is regulated by noradrenaline.

The loss of noradrenergic neurons and subsequent reduction of brain noradrenaline (NA) levels are associated with the progression of Alzheimer's disease (AD). This seems to be due mainly to the ability of NA to reduce the activation of microglial cells. We previously observed that NA induces the production of the chemokine Fractalkine/CX3CL1 in neurons. The activation of microglial CX3CR1, sole receptor for CX3CL1, reduces the activation of microglia, which is known to largely contribute to the neuronal damage characteristic of AD. Therefore, alterations of CX3CR1 production in microglia could translate into the enhancement or inhibition of CX3CL1 anti-inflammatory effects. In order to determine if microglial CX3CR1 production is altered in AD and if NA can control it, CX3CR1 expression and synthesis were analyzed in 5xFAD mice and human AD brain samples. In addition, the effects of NA and its reuptake inhibitor reboxetine were analyzed in microglial cultures and mice respectively. Our results indicate that in AD CX3CR1 production is increased in the brain cortex and that reboxetine administration further increases it and enhances microglial reactivity toward amyloid beta plaques. However, direct administration of NA to primary rat microglia or human HMC3 cells inhibits CX3CR1 production, suggesting that microglia responses to NA may be altered in the absence of CX3CL1-producing neurons or other nonmicroglial external factors.

Paliperidone attenuates chronic stress-induced changes in the expression of inflammasomes-related protein in the frontal cortex of male rats.

Several stress-related neuropsychiatric diseases are related to inflammatory phenomena. Thus, a better understanding of stress-induced immune responses could lead to enhanced treatment alternatives. Little is known about the possible involvement of inflammasomes in the stress-induced proinflammatory response. Antipsychotics have anti-inflammatory effects, but the possible antipsychotic treatment actions on inflammasomes remain unexplored. Our aim was to study whether inflammasomes are involved in the neuroinflammation induced by a paradigmatic model of chronic stress and whether the monoamine receptor antagonist paliperidone can modulate the possible stress-induced inflammasomes activation in the frontal cortex (FC). Thus, the effects of paliperidone (1 mg/Kg, oral gavage) administered during a chronic restraint stress protocol (6 h/day for 21 days) on the possible stress-related inflammasomes protein induction were evaluated through Western blot in the FC of male Wistar rats. Stress increased protein expression levels of the inflammasome complexes NALP1, NLRP3 and AIM2 and augmented caspase-1 and mature interleukin (IL)-1ß protein levels. Paliperidone pre-treatment normalized the protein expression of the inflammasome pathway. In conclusion, our data indicate an induction of inflammasome complexes by chronic restraint stress in the FC of rats. The antipsychotic paliperidone has an inhibitory action on some of the stress-induced inflammasomes stimulation trying to normalize the neuroinflammatory scenario caused by stress. Considering the emerging role of inflammation in neuropsychiatric diseases, the development of new drugs targeting inflammasome pathways is a promising approach for future therapeutic interventions.

Depletion of brain perivascular macrophages regulates acute restraint stress-induced neuroinflammation and oxidative/nitrosative stress in rat frontal cortex.

The central nervous system can respond to peripheral immune stimuli through the activation of the neurovascular unit. One of the cellular types implicated are perivascular macrophages (PVMs), hematopoietic-derived brain-resident cells located in the perivascular space. PVMs have been implicated in the immune surveillance and in the regulation of the accumulation/trafficking of macromolecules in brain-blood interfaces. Recent studies suggested that the role of PVMs could vary depending on the nature and duration of the immune challenge applied. Here, we investigate the role of PVMs in stress-induced neuroinflammation and oxidative/nitrosative consequences. The basal phagocytic activity of PVMs was exploited to selectively deplete them by ICV injection of liposomes encapsulating the pro-apoptotic drug clodronate. Acute restraint stress-induced neuroinflammation and oxidative/nitrosative stress in rat brain frontal cortex samples were assessed by western blot and RT-PCR analyses. The depletion of PVMs: (1) decreased tumor necrosis-α levels (2) prevented the Janus kinase/signal transducers and activators of transcription pathway and increased interleukin-6 receptor protein-expression in stress conditions; (3) prevented the stress-induced Toll-like receptor 4/Myeloid differentiation primary response 88 protein signaling pathway; (4) down-regulated the pro-inflammatory nuclear factor κB/cyclooxygenase-2 pathway; (5) prevented stress-induced lipid peroxidation and the concomitant increase of the endogenous antioxidant mediators nuclear factor (erythroid-derived 2)-like 2, glutathione reductase 1 and Parkinsonism-associated deglycase mRNA expression. Our results point to PVMs as regulators of stress-induced neuroinflammation and oxidative/nitrosative stress. Much more scientific effort is still needed to evaluate whether their selective manipulation is promising as a therapeutic strategy for the treatment of stress-related neuropsychopathologies.

Toll-like receptor 4 agonist and antagonist lipopolysaccharides modify innate immune response in rat brain circumventricular organs.

BACKGROUND: The circumventricular organs (CVOs) are blood-brain-barrier missing structures whose activation through lipopolysaccharide (LPS) is a starting point for TLR-driven (Toll-like receptors) neuroinflammation. The aim of this study was to evaluate in the CVO area postrema (AP), subfornical organ (SFO), and median eminence (ME), the inflammatory response to two TLR4 agonists: LPS from Escherichia coli (EC-LPS), the strongest endotoxin molecule described, and LPS from Porphyromonas gingivalis (PG-LPS), a pathogenic bacteria present in the periodontium related to neuroinflammation in neurodegenerative/psychiatric diseases. The response to LPS from the cyanobacteria Rhodobacter sphaeroides (RS-LPS), a TLR4 antagonist with an interesting anti-inflammatory potential, was also assessed. METHODS: LPSs were intraperitoneally administered to Wistar rats and, as indicatives of neuroinflammation in CVOs, the cellular localization of the nuclear factor NF-κB was studied by immunofluorescence, and microglia morphology was quantified by fractal and skeleton analysis. RESULTS: Data showed that EC-LPS increased NF-κB nuclear translocation in the three CVOs studied and PG-LPS only induced NF-κB nuclear translocation in the ME. RS-LPS showed no difference in NF-κB nuclear translocation compared to control. Microglia in the three CVOs showed an ameboid-shape after EC-LPS exposure, whereas PG-LPS only elicited a mild tendency to induce an ameboid shape. On the other hand, RS-LPS produced a markedly elongated morphology described as "rod" microglia in the three CVOs. CONCLUSIONS: In conclusion, at the doses tested, EC-LPS induces a stronger neuroinflammatory response than PG-LPS in CVOs, which might be related to their different potency as TLR4 agonists. The non-reduction of basal NF-κB activation and induction of rod microglia by RS-LPS, a cell morphology only present in severe brain injury and infections, suggests that this molecule must be carefully studied before being proposed as an anti-inflammatory treatment for neuroinflammation related to neurodegenerative/psychiatric diseases.

Reboxetine Treatment Reduces Neuroinflammation and Neurodegeneration in the 5xFAD Mouse Model of Alzheimer's Disease: Role of CCL2.

The reduction of brain noradrenaline levels is associated to the initiation of Alzheimer's disease and contributes to its progression. This seems to be due mainly to the anti-neuroinflammatory actions of noradrenaline. The analysis of noradrenaline effects on brain cells demonstrates that it also regulates the production of the chemokine CCL2. In the present study, we analyzed the effect of the selective noradrenaline reuptake inhibitor, reboxetine, on the inflammatory and neurodegenerative alterations present in 5xFAD mice, and how the genetic removal of CCL2 affects reboxetine actions. We observed that the removal of CCL2 reduced the memory impairments in 5xFAD mice as well as the neuroinflammatory response, the accumulation of amyloid beta plaques, and the degeneration of neurons in the brain cortex. The administration of reboxetine with osmotic pumps for 28 days also resulted in anti-inflammatory and neuroprotective changes in 5xFAD mice, even in the absence of CCL2. Yet, 6-month-old CCL2KO mice presented a significant degree of neuroinflammation and neuronal damage. These findings indicate that reboxetine treatment prevents the brain alterations caused by prolonged overproduction of amyloid beta, being these effects independent of CCL2, which is a mediator of the damage caused by amyloid beta in the brain cortex, but necessary for the prevention of the development of neurodegeneration in normal healthy conditions.

Modulation of Monoaminergic Systems by Antidepressants in the Frontal Cortex of Rats After Chronic Mild Stress Exposure.

The standard pharmacological treatment of the major depressive disorder (MDD) is still grounded in a monoaminergic approach. Consequently, antidepressant treatments pursue to heighten serotonergic and noradrenergic neurotransmissions. Thus, the aim of this study was to assess the impact of exposure to a well-characterized animal model, the chronic mild stress (CMS) on serotonin (5-HT) and noradrenaline (NE) levels, and reuptake transporters and receptors in the frontal cortex (FC) of CMS-exposed rats. Moreover, considering the diverse pharmacological profiles of existing antidepressants and the large number of patients not responding to treatments, we have investigated whether generally utilized antidepressants can modulate their expression. Male Wistar rats were exposed to CMS and some of them treated with desipramine, escitalopram, or duloxetine. Possible changes in the described monoaminergic neurotransmission elements were evaluated. CMS induced differences in the expression of reuptake transporters and receptors involved in the monoaminergic neurotransmission pointing towards the weakening of their signaling. CMS antidepressant-treated rats showed an improvement of the monoaminergic tone, being desipramine and duloxetine more influential than escitalopram over noradrenergic elements and having the three antidepressant-tested effects on serotonergic transmission. In summary, there are molecular alterations on the monoaminergic neurotransmission in FC induced by CMS exposure. Besides, antidepressant treatments modulate the elements of these neurotransmission systems differentially.

Chronic Mild Stress Alters Kynurenine Pathways Changing the Glutamate Neurotransmission in Frontal Cortex of Rats.

Immune stimulation might be involved in the pathophysiology of major depressive disorder (MDD). This stimulation induces indoleamine 2,3-dioxygenase (IDO), an enzyme that reduces the tryptophan bioavailability to synthesize serotonin. IDO products, kynurenine metabolites, exert neurotoxic/neuroprotective actions through glutamate receptors. Thus, we study elements of these pathways linked to kynurenine metabolite activity examining whether antidepressants (ADs) can modulate them. Male Wistar rats were exposed to chronic mild stress (CMS), and some of them were treated with ADs. The expression of elements of the IDO pathway, including kynurenine metabolites, and their possible modulation by ADs was studied in the frontal cortex (FC). CMS increased IDO expression in FC compared to control group, and ADs restored the IDO expression levels to control values. CMS-induced IDO expression led to increased levels of the excitotoxic quinolinic acid (QUINA) compared to control, and ADs prevented the rise in such levels. Neither CMS nor ADs changed significantly the antiexcitotoxic kynurenic acid (KYNA) levels. The QUINA/KYNA ratio, calculated as excitotoxicity risk indicator, increased after CMS and ADs prevented this increase. CMS lowered excitatory amino acid transporter (EAAT)-1 and EAAT-4 expression, and some ADs restored their expression levels. Furthermore, CMS decreased N-methyl-D-aspartate receptor (NMDAR)-2A and 2B protein expression, and ADs mitigated this decrease. Our research examines the link between CMS-induced pro-inflammatory cytokines and the kynurenine pathway; it shows that CMS alters the kynurenine pathway in rat FC. Importantly, it also reveals the ability of classic ADs to prevent potentially harmful situations related to the brain scenario caused by CMS.

Intracellular inflammatory and antioxidant pathways in postmortem frontal cortex of subjects with major depression: effect of antidepressants.

BACKGROUND: Studies show that Toll-like receptors (TLRs), members of the innate immune system, might participate in the pathogenesis of the major depressive disorder (MDD). However, evidence of this participation in the brain of patients with MDD has been elusive. METHODS: This work explores whether the protein expression by immunodetection assays (Western blot) of elements of TLR-4 pathways controlling inflammation and the oxidative/nitrosative stress are altered in postmortem dorsolateral prefrontal cortex of subjects with MDD. The potential modulation induced by the antidepressant treatment on these parameters was also assessed. Thirty MDD subjects (15 antidepressant-free and 15 under antidepressant treatment) were matched for gender and age to 30 controls in a paired design. RESULTS: No significant changes in TLR-4 expression were detected. An increased expression of the TLR-4 endogenous ligand Hsp70 (+ 33%), but not of Hsp60, and the activated forms of mitogen-activated protein kinases (MAPKs) p38 (+ 47%) and JNK (+ 56%) was observed in MDD. Concomitantly, MDD subjects present a 45% decreased expression of DUSP2 (a regulator of MAPKs) and reduced (- 21%) expression of the antioxidant nuclear factor Nrf2. Antidepressant treatment did not modify the changes detected in the group with MDD and actually increased (+ 25%) the expression of p11, a protein linked with the transport of neurotransmitters and depression. CONCLUSION: Data indicate an altered TLR-4 immune response in the brain of subjects with MDD. Additional research focused on the mechanisms contributing to the antidepressant-induced TLR-4 pathway modulation is warranted and could help to develop new treatment strategies for MDD.

Alternative Method to Detect Neuronal Degeneration and Amyloid ß Accumulation in Free-Floating Brain Sections With Fluoro-Jade.

Fluoro-Jade is a fluorescein-derived fluorochrome which specifically binds to damaged neurons. Due to this characteristic, it is commonly used for the histochemical detection and quantification of neurodegeneration in mounted brain sections. Here, we describe an alternative and simpler histochemistry protocol based on the use of free-floating brain sections. For this purpose, we have used brain slices from wild-type and 5xFAD mice as well as from mice that received an intracerebral injection of oligomeric amyloid beta peptides. We observed that our histochemistry staining procedure allows for a well-defined labeling of degenerating neurons providing a better signal-to-noise ratio staining than the commonly used one. In addition, our modified protocol demonstrates the ability of Fluoro-Jade C to also fluorescently label amyloid beta plaques.

Transcriptome analysis of alcohol-treated microglia reveals downregulation of beta amyloid phagocytosis.

BACKGROUND: Microglial activation contributes to the neuropathology associated with chronic alcohol exposure and withdrawal, including the expression of inflammatory and anti-inflammatory genes. In the current study, we examined the transcriptome of primary rat microglial cells following incubation with alcohol alone, or alcohol together with a robust inflammatory stimulus. METHODS: Primary microglia were prepared from mixed rat glial cultures. Cells were incubated with 75 mM ethanol alone or with proinflammatory cytokines ("TII": IL1ß, IFNγ, and TNFα). Isolated mRNA was used for RNAseq analysis and qPCR. Effects of alcohol on phagocytosis were determined by uptake of oligomeric amyloid beta. RESULTS: Alcohol induced nitrite production in control cells and increased nitrite production in cells co-treated with TII. RNAseq analysis of microglia exposed for 24 h to alcohol identified 312 differentially expressed mRNAs ("Alc-DEs"), with changes confirmed by qPCR analysis. Gene ontology analysis identified phagosome as one of the highest-ranking KEGG pathways including transcripts regulating phagocytosis. Alcohol also increased several complement-related mRNAs that have roles in phagocytosis, including C1qa, b, and c; C3; and C3aR1. RNAseq analysis identified over 3000 differentially expressed mRNAs in microglia following overnight incubation with TII; and comparison to the group of Alc-DEs revealed 87 mRNAs modulated by alcohol but not by TII, including C1qa, b, and c. Consistent with observed changes in phagocytosis-related mRNAs, the uptake of amyloid beta1-42, by primary microglia, was reduced by alcohol. CONCLUSIONS: Our results define alterations that occur to microglial gene expression following alcohol exposure and suggest that alcohol effects on phagocytosis could contribute to the development of Alzheimer's disease.

CCL2 Induces the Production of ß2 Adrenergic Receptors and Modifies Astrocytic Responses to Noradrenaline.

The decline in brain noradrenaline levels is associated with the progression of certain neurodegenerative diseases. This seems to be due, at least in part, to the ability of noradrenaline to limit glial activation and to reduce the damage associated with it. Our previous studies of the mechanisms involved in this process indicate that noradrenaline induces the production of the chemokine CCL2 in astrocytes. While CCL2 can protect neurons against certain injuries, its overproduction has also proven to be harmful and to prevent noradrenaline neuroprotective effects. Therefore, in this study, we analyze if the modifications caused to astrocytes by an excessive production of CCL2 may alter their response to noradrenaline. Using primary cultures of rat cortical astrocytes, we observed that CCL2 enhances the production of beta 2 adrenergic receptors in these cells. While this potentiates noradrenaline signaling through cAMP, the activation of the transcription factor CREB is inhibited by CCL2. Furthermore, although CCL2 potentiates noradrenaline induction of glycogenolysis, this does not translate into an augmented release of lactate, one of the processes through which astrocytes help support neurons. Additionally, other neuroprotective actions of noradrenaline, such as the production of brain derived neurotrophic factor and the inhibition of the inducible nitric oxide synthase in astrocytes were modified by CCL2. These data suggest that some of the central nervous system alterations related to CCL2 could be due to its effects on adrenergic receptors and its interference with noradrenaline signaling.