Chronic infection by atypical Toxoplasma gondii strain induces disturbance in microglia population and altered behaviour in mice.

Toxoplasma gondii chronic infection is characterized by the establishment of tissue cysts in the brain and increased levels of IFN-γ, which can lead to brain circuitry interference and consequently abnormal behaviour in mice. In this sense, the study presented here sought to investigate the impact of chronic infection by two T. gondii strains in the brain of infection-resistant mice, as a model for studying the involvement of chronic neuroinflammation with the development of behavioural alterations. For that, male BALB/c mice were divided into three groups: non-infected (Ni), infected with T. gondii ME49 clonal strain (ME49), and infected with TgCkBrRN2 atypical strain (CK2). Mice were monitored for 60 days to establish the chronic infection and then submitted to behavioural assessment. The enzyme-linked immunosorbent assay was used for measurement of specific IgG in the blood and levels of inflammatory cytokines and neurotrophic factors in the brain, and the cell's immunophenotype was determined by multiparametric flow cytometry. Mice infected with ME49 clonal strain displayed hyperlocomotor activity and memory deficit, although no signs of depressive- and/or anxiety-like behaviour were detected; on the other hand, chronic infection with CK2 atypical strain induced anxiety- and depressive-like behaviour. During chronic infection by CK2 atypical strain, mice displayed a higher number of T. gondii brain tissue cysts and inflammatory infiltrate, composed mainly of CD3+ T lymphocytes and Ly6Chi inflammatory monocytes, compared to mice infected with the ME49 clonal strain. Infected mice presented a marked decrease of microglia population compared to non-infected group. Chronic infection with CK2 strain produced elevated levels of IFN-γ and TNF-ɑ in the brain, decreased NGF levels in the prefrontal cortex and striatum, and altered levels of fractalkine (CX3CL1) in the prefrontal cortex and hippocampus. The persistent inflammation and the disturbance in the cerebral homeostasis may contribute to altered behaviour in mice, as the levels of IFN-γ were shown to be correlated with the behavioural parameters assessed here. Considering the high incidence and life-long persistence of T. gondii infection, this approach can be considered a suitable model for studying the impact of chronic infections in the brain and how it impacts in behavioural responses.

Modified Levels of Renin Angiotensin Related Components in the Frontal Cortex and Hippocampus were Associated with Neuroinflammation and Lower Neuroprotective Effects of NGF During Acute Hepatic Encephalopathy in Mice.

BACKGROUND: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome that involves cognitive and motor dysfunctions due to hepatic failure. The clinical and experimental studies suggest that the angiotensin (Ang) converting enzyme (ACE), Ang II, and angiotensin type 1 receptor (AT1R), which compose the classical pathway of the renin-angiotensin system (RAS), exacerbate neuroinflammation in different neurologic diseases. Conversely, Ang-(1-7), ACE2, and Mas receptor, which integrate the alternative RAS axis, have been shown as promising therapeutic targets in neuropsychiatric disorders, leading to neuroprotection. OBJECTIVE: This study aimed to investigate the potential participation of the RAS components in thioacetamide (TAA)-induced HE in mice. METHODS: We also evaluated the levels of neurotrophic factors, pro-inflammatory cytokines, and chemokine in the central nervous system of TAA-induced HE in mice. Mice were submitted to acute liver failure induced by TAA administration by intraperitoneal route. Measurements of RAS components (ACE, Ang II, ACE2 and Ang1-7) and neurotrophic factors (BDNF, GDNF and NGF) were obtained by ELISA assay. Pro-inflammatory cytokines (TNF, IFN-γ, IL-6, IL-12p70) and the chemokine (CCL2) were quantified by cytometric bead array. The student's t-test was applied for statistical analysis. RESULTS: Mice presented increased cortical levels of ACE, while Ang-(1-7) levels were decreased in cortical and hippocampal samples compared to controls. Moreover, HE mice had an increase in the Ang II/Ang-(1-7) ratio along with reduced levels of neural growth factor (NGF) in the prefrontal cortex. They also showed elevated levels of IFN-γ and CCL2 in the prefrontal cortex and of TNF, IL-6, IL-12, and CCL2 in the hippocampus compared with controls. CONCLUSION: This study suggested that the reduction of components of the alternative RAS axis was associated with the deleterious effects of neuroinflammation and lower neuroprotective effects of NGF during TAA-induced HE.

Role of cytokine and neurotrophic factors in nicotine addiction in the conditioned place preference paradigm.

The mechanisms involved in the maintenance of cigarette smoking and nicotine reward remain unclear. Immune response might play an important role in this context. Nicotine may induce both central and systemic inflammatory responses as well as changes in the regulation of brain-derived neurotrophic factor (BDNF). The conditioned place preference (CPP) is a method used for the evaluation of nicotine-induced reward, reproducing nicotine-seeking behavior in humans. So far, there are no studies investigating the relationship between neuroinflammation and nicotine-induced CPP. This study aimed to evaluate the levels of inflammatory mediators and neurotrophic factors in key areas of the central nervous system (CNS) of mice subject to nicotine-induced CPP. CPP was induced with an intraperitoneal administration of 0.5 mg/kg of nicotine in male Swiss mice, using an unbiased protocol. Control group received vehicle by the same route. The levels of cytokines, chemokines, and neurotrophic factors were measured using Enzyme-Linked Immunosorbent Assay (ELISA) in the brain after CPP test. As expected, nicotine induced place preference behavior. In parallel, we observed increased peripheral levels of IL-6 and IL-10 alongside increased hippocampal levels of NGF but decreased GDNF in mice treated with nicotine compared to controls. In the striatum, nicotine promoted decrease of IL-1ß, IL-10 and GDNF levels, while the levels of all the mediators were similar between groups in the pre-frontal cortex. Our results provide evidence on the role of cytokines and neurotrophic factors in nicotine-induced CPP in mice.

Tumor necrosis factor superfamily molecules are increased in behavioral variant frontotemporal dementia and correlate with cortical atrophy: An exploratory investigation.

Frontotemporal dementia (FTD) is the second most frequent cause of young-onset dementia. Even though immune-mediated and neuroinflammatory factors have been recognized as potential pathophysiological mechanisms, the role of specific immune molecules, such as the tumor necrosis factor (TNF) superfamily, remains elusive. The aim of this study was to investigate TNF Superfamily Molecules (TNF, TNF-related weak inducer of apoptosis [TWEAK], soluble TNF receptor type 1 [sTNFRI] and soluble TNF receptor type 2 [sTNFRII]) in patients with behavioral variant FTD (bvFTD) and controls, and to explore potential associations with clinical parameters and brain atrophy. This study included two groups of participants matched for age, sex and schooling years: patients with probable bvFTD (n = 17, mean age = 64.9 years, 6 women/11 men) and healthy controls (HC, n = 17; mean age = 63.9 years, 10 women/7 men). All participants underwent comprehensive cognitive assessment and structural brain imaging with 3 T magnetic resonance imaging. Plasma levels of TNF, TWEAK, sTNFRI and sTNFRII were determined by ELISA. We conducted voxel-based morphometry analyses to investigate correlations between grey matter (GM) atrophy and plasma levels of TNF, TWEAK, sTNFRI and sTNFRII within bvFTD group. Compared to HC, bvFTD patients had lower cognitive scores and marked frontotemporal atrophy. Patients with bvFTD had significantly higher plasma levels of TNF (p < 0.0001), sTNFRI (p < 0.001), and sTNFRII (p < 0.0001), and similar levels of TWEAK in comparison with controls. The levels of sTNFRII were positively correlated with GM atrophy involving temporal poles, precuneus and cerebellum in bvFTD patients, while the levels of TWEAK positively correlated with right superior temporal gyrus. Our results implicate TNF superfamily in the pathophysiology of FTD.

Neuroinflammation is associated with reduced SOCS2 and SOCS3 expression during intracranial HSV-1 infection.

Herpes simplex virus type 1 (HSV-1) is the main etiological agent of acute and sporadic encephalitis. Proteins of the suppressor of cytokine signaling (SOCS) family have shown to regulate the inflammation during HSV-1 infection in the brain. However, the effects of SOCS2 and SOCS3 in viral encephalitis remain unclear. The aim of the current study is to investigate the potential association between SOCS2, SOCS3, cytokines, and hippocampal damage, especially neuronal apoptosis, during acute intracranial HSV-1 infection in mice. Male C57BL/6 mice were infected by intracranial route with 102 plaque-forming units (PFU) inoculum of purified HSV-1. At three days post-infection (3 d.p.i.), mice were euthanized and their hippocampi were collected for histopathological analysis, immunohistochemical reaction against active caspase-3 and quantification of SOCS2, SOCS3 and cytokines (tumoral necrosis factor (TNF), interleukin (IL) 1ß, IL-6, IL-10; interferon (IFN) -α, IFN-ß, IFN-γ) mRNA expression. Infected mice exhibited neuronal loss and hemorrhagic focus in Cornu Ammonis (CA) region. The apoptotic index was higher in infected mice compared to controls. HSV-1 infection was associated with increased hippocampal expression of TNF, IL1-ß, IL-6 and IFNα/IFNß and decreased expression of IL-10, IFN-γ, SOCS2 and SOCS3. Our results suggest that down regulation of SOCS2 and SOCS3 contributes to a pro-inflammatory environment associated with hippocampal damage and neuronal apoptosis during acute HSV-1 infection in mice.

Up-regulation of brain cytokines and metalloproteinases 1 and 2 contributes to neurological deficit and brain damage in transient ischemic stroke.

Ischemic stroke represents a major cause of adult death and severe neurological disability worldwide. Reperfusion following brain ischemia produces an inflammatory cascade that increases brain damage. In this context, matrix metalloproteinases (MMPs) play an important role as pro-inflammatory mediators. The MMP 2 up-regulation seems to promote matrix degradation, blood-brain barrier (BBB) disruption and facilitates the influx of peripheral inflammatory cells to the brain after stroke. However, there are not studies about MMP-1 in this condition. The aim of this study is to evaluate the association of brain damage, inflammatory response and the immunostaining profile of matrix metalloproteinases 1 and 2 after transient global cerebral ischemia. Mice were submitted to bilateral common carotid arterial occlusion (BCCAo) during 25 min. After three days of reperfusion, the neurological deficit score was evaluated and the animals were euthanized. Brain samples were collected in order to analyze the histopathological damage, MMPs 1 and 2 immunostaining and cytokines and chemokines levels. Ischemic group showed neurological deficits associated with brain lesions, characterized by necrotic core and penumbra zone three days after reperfusion. Higher brain immunostaining of MMP-1 and MMP-2 was observed in BCCAo samples than in sham samples. Ischemic group also exhibited increased brain levels of the cytokines tumoral necrosis factor (TNF) and interleukin 1ß (IL-1ß), chemokine (C-X-C motif) ligand 1 (CXCL1), and chemokine (C-C motif) ligand 5 (CCL5) in comparison to sham group. Our results suggest that the MMP-1 and MMP-2 raise, associated with the up-regulation of inflammatory mediators, contributes to brain damage and neurological deficits after global brain ischemia followed by three days of reperfusion in mice.

Effects of Vaccination Against the H1N1 Virus on BDNF and TNF-α Plasma Levels in Pregnant Women.

BACKGROUND: Vaccination is a widespread strategy to protect women and their children during fetal development. However, there is a lack of knowledge about potential effects of H1N1 vaccination on concentration of cytokines that are important to mother's central nervous system functions and fetal neurodevelopment. OBJECTIVE: The main purpose of the present study was to evaluate such interaction. The specific goals were to study the effects of vaccination against the H1N1 virus on plasma levels of the Brain Derived Neurotrophic Factor(BDNF), Tumor Necrosis Factor-α (TNF-α) and TNF-α Receptors 1 and 2 (sTNFR1; sTNFR2), in different periods of gestation. METHODS: Data were obtained during the period of 6 months in 2010, from a sample of 94 pregnant women who were using the health care service of Conceição do Mato Dentro, a rural area in the state of Minas Gerais, Brazil. Seventeen women were in the first trimester of pregnancy, forty were in the second trimester and 37 were in the third trimester. Each of these groups was divided into two subgroups as follows: immunized against the H1N1 virus (I) and non-immunized (NI). Plasma concentrations of BDNF, TNF-α, sTNFR1 and sTNFR2 were measured using the sandwich ELISA. RESULTS: There was no difference in cytokine or neurotrophic factor levels evaluated between groups I and NI in any trimesters. CONCLUSION: These results show that the recommendation of vaccination against the H1N1 virus for all pregnant women as a public health measure could be considered safe, regarding aspects related to the role played by neurotrophin and cytokine, such as those of CNS development and immunological functions.

The 5-lipoxygenase (5-LOX) Inhibitor Zileuton Reduces Inflammation and Infarct Size with Improvement in Neurological Outcome Following Cerebral Ischemia.

Stroke is one of the most frequent causes of death and disability worldwide causing a major clinical and socioeconomic impact. Although the pathophysiology of brain ischemia and reperfusion is complex, the inflammatory process plays an important role in pathogenesis, contributing to the expansion of brain injury. The 5-lipoxygenase (5-LOX) is a key enzyme in the biosynthesis of the leukotrienes and has been implicated and in the central nervous system (CNS) disorders such as Alzheimer's disease and acute ischemic stroke. Zileuton, a selective 5-LOX inhibitor, has antiinflammatory properties and exerts an inhibitory effect on inflammatory diseases. The objective of this study was to evaluate the effects of blocking 5-LOX activity in a murine model of transient and global brain ischemia. Zileuton improved neurological deficits and significantly decrease volume and density of lesion, compared to vehicle-ischemic animals measured by magnetic resonance imaging (MRI). In addition, the blockage of 5-LOX reduced infarct area and histopathological changes. Furthermore, by enzyme immunoassay (ELISA) increased brain levels of tumor necrosis factor-alpha (TNFalpha), interferon-gamma (IFN-gamma), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), chemokine (C-X-C motif) ligand 1 (CXCL1), chemokine (C-C motif) ligand 3 (CCL3) and chemokine (C-C motif) ligand 5 (CCL5) were detected in the vehicle-ischemic group, whereas in Zileuton-ischemic group presented reduction of these mediators. The concentration of the antiinflammatory cytokine interleukin-10 (IL-10) was increased after 5-LOX inhibition. Our results suggest that Zileuton decreases brain damage and reduces inflammatory cytokines expression in the CNS which contributes, at least in part, to improve the neurological outcome of brain ischemia.

Effects of an exercise therapy protocol on inflammatory markers, perception of pain, and physical performance in individuals with knee osteoarthritis.

Establishing prevention and therapeutic strategies for osteoarthritis (OA) is necessary to minimize functional disability and the impact of the disease on society. The aim of this study was to determine the effects of an exercise therapy protocol on inflammatory markers, perception of pain, and physical performance in individuals with OA of the knee. The protocol consisted of flexibility training and muscle strengthening over 12 weeks with three 80-min sessions per week. Peripheral blood was collected to determine serum levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and soluble forms of the TNF-α receptor (sTNFR1 and sTNFR2). A clinical assessment of the musculoskeletal system and Western Ontario and McMaster Universities (WOMAC) questionnaire were applied to evaluate the specific symptoms of knee OA. Pain intensity was evaluated using a visual analog scale (VAS). All measurements were taken before and after the intervention. Twenty-two individuals (mean age 58.8 ± 6.4 years) completed the protocol. A decrease in the perception of pain was evident on VAS (p < 0.001) and pain subscale of the WOMAC (p < 0.001). In addition, there was a reduction in serum levels of IL-6 (p < 0.001). However, changes in the levels of the TNF-α and its soluble receptors were not statistically significant. Physical function subscale score and the WOMAC global score improved significantly (p < 0.001). The training also promoted an increase in the progression load for all muscles groups analyzed (p < 0.001). Our data suggest that the exercise therapy protocol could be a strategy for reducing IL-6 levels, managing pain, and improving function in individuals with OA of the knee. However, more studies are necessary to investigate the issue.

Circulating levels of sTNFR1 as a marker of severe clinical course in schizophrenia.

BACKGROUND: Schizophrenia (SZ) has been associated with an imbalance in the inflammatory cytokine TNF-α. The objectives of this study were to compare TNF-α and its soluble receptors' serum levels in individuals with SZ with the levels found in a group of healthy volunteers and to investigate the possible association between these biomarkers and the dimensions and severity of symptoms, clinical outcomes and response to treatment in patients with SZ. METHODS: Fifty-four chronically medicated SZ outpatients and 118 healthy controls were included in the study. TNF-α levels were measured by Cytometric Bead Assay (CBA), and serum levels of soluble tumor necrosis factor receptor 1 (sTNFR1) and soluble tumor necrosis factor receptor 2 (sTNFR2) were measured by ELISA. RESULTS: sTNFR1 and sTNFR2 were significantly elevated in patients with SZ as compared to the healthy control group. In the group of individuals with SZ, the levels of both types of soluble TNF receptors showed a negative correlation with global functioning. sTNFR1 levels were higher in the treatment-resistant patients as compared to the non-treatment-resistant patients and the controls. sTNFR1 levels were also heightened in patients with SZ and concomitant depression. CONCLUSION: Our findings reinforce that SZ is associated with an inflammatory profile and suggest that sTNFR1 is a marker of a treatment-resistance and severe clinical course in SZ.

Dengue-3 encephalitis promotes anxiety-like behavior in mice.

Dengue virus is a human pathogen that may cause meningoencephalitis and other neurological syndromes. The current study investigated anxiety-like behavior and expression of proinflammatory cytokines and pro-apoptotic caspase-3 in the hippocampus of C57BL/6 mice infected with non-adapted Dengue virus 3 genotype I (DENV-3) inoculated intracranially with 4×10(3) (plaque-forming unit) PFU. Anxiety-like behavior was assessed in control and DENV-3 infected mice using the elevated plus maze. The open field test was performed to evaluate locomotor activity. Histopathological changes in CA regions of the hippocampus were assessed by haematoxylin and eosin staining. Immunoreactive and protein levels of cleaved caspase-3 were also analyzed in the hippocampus. The mRNA expression of IL-6 and TNF-α in the hippocampus were estimated by quantitative real time (polymerase chain reaction) PCR. All procedures were conducted on day 5 post-infection. We found that DENV-3 infected mice presented higher levels of anxiety in comparison with controls (p≤0.05). No difference in motor activity was found between groups (p=0.77). The infection was followed by a significant increase of TNF-α and IL-6 mRNA expression in the hippocampus (p≤0.05). Histological analysis demonstrated meningoencephalitis with formation of perivascular cuffs, infiltration of immune cells and loss of neurons at CA regions of hippocampus. Numerous caspase-3 positive neurons were visualized at CA areas in DENV-3 infected mice. Marked increase of cleaved caspase-3 levels were observed after infection. This study described anxiety-like behavior, hippocampal inflammation and neuronal apoptosis associated with DENV-3 infection in the central nervous system.

Increased levels of adipokines in bipolar disorder.

Bipolar disorder (BD) is associated with considerable higher chronic medical comorbidities, overweight and obesity. Adipokines are adipocyte-derived secretory factors which have functions in immune response and seem to be associated with both BD and overweight. The aim of this study was to evaluate the plasma levels of adipokines (adiponectin, resistin and leptin) and TNF-α and its receptors (sTNFR1 and sTNFR2) in BD overweight patients in comparison with overweight controls. Thirty euthymic BD type-I patients and thirty controls matched by age, gender and body-mass index (BMI) were assessed by Mini-International Neuropsychiatric Interview, Young Mania and Hamilton Depression rating scales (YMRS and HDRS, respectively). Plasma levels of adiponectin, resistin, leptin, TNF-α and its soluble receptors were measured by ELISA. BD patients presented increased plasma levels of adiponectin (p < 0.001), leptin (p < 0.001) and sTNFR1 (p = 0.01). Plasma levels of adipokines were not correlated neither with clinical parameters nor TNF-α, sTNFR1 and sTNFR2 plasma levels. This study provides further support to the hypothesis of the immune/inflammatory imbalance in BD.

TNFR1 plays a critical role in the control of severe HSV-1 encephalitis.

Herpes simplex virus-1 (HSV-1) is a pathogen for humans that may cause severe encephalitis. Tumor necrosis factor alpha (TNF-alpha) plays a role in several viral diseases of the central nervous system (CNS). The classic proinflammatory activities of TNF-alpha are mediated mainly through activation of the receptor 1 for TNF-alpha (TNFR1). However, when HSV-1 is inoculated in the periphery, TNF-alpha seems to protect C57Bl/6 mice against encephalitis by a mechanism independent of TNFR1. This study aims to investigate the role of TNFR1 in HSV-1 encephalitis induced by the inoculation of the virus into the brain. Wild-type C57BL/6 (WT) and TNFR1(-/-) were inoculated with 10(2) plaque-forming units of HSV-1 by the intracranial route. Infection with HSV-1 was lethal in TNFR1(-/-) mice in early times after infection. TNFR1(-/-) mice had reduced expression of the chemokines CCL3 and CCL5, and decreased leukocyte adhesion in the brain vasculature compared to WT mice 4 days post-infection (dpi). At this time point TNFR1(-/-) infected mice also had higher HSV-1 viral replication and more injuries in the brain, especially in the hippocampus. In conclusion, TNFR1 seems to play a relevant role in the control of viral replication in the CNS when HSV-1 is inoculated by intracranial route.