Rice bran derivatives alleviate microglia activation: possible involvement of MAPK pathway

Myeloid-derived growth factor ameliorates dextran sodium sulfate-induced colitis by regulating macrophage polarization

Inflammatory bowel disease (IBD) is characterized by inflammatory conditions in the gastrointestinal tract. According to reports, IBD prevalence is increasing globally, with heavy economic and physical burdens. Current IBD clinical treatment is limited to pharmacological methods; therefore, new strategies are needed. Myeloid-derived growth factor (MYDGF) secreted by bone marrow-derived mononuclear macrophages has beneficial effects in multiple inflammatory diseases. To this end, the present study aimed to establish an experimental IBD mouse model using dextran sulfate sodium in drinking water. MYDGF significantly alleviated DSS-induced colitis, suppressed lymphocyte infiltration, restored epithelial integrity in mice, and decreased apoptosis in the colon tissue. Moreover, the number of M1 macrophages was decreased and that of M2 macrophages was increased by the action of MYDGF. In MYDGF-treated mice, the NF-κB and MAPK pathways were partially inhibited. Our findings indicate that MYDGF could mitigate DSS-induced mice IBD by reducing inflammation and restoring epithelial integrity through regulation of intestinal macrophage polarization via NF-κB and MAPK pathway inhibition. KEY MESSAGES: MYDGF alleviated DSS-induced acute colitis. MYDGF maintains colon epithelial barrier integrity and relieves inflammation. MYDGF regulates colon macrophage polarization. MYDGF partially inhibited the activation of NF-κB and MAPK pathway.

Peak Edema Extension Distance: An Edema Measure Independent from Hematoma Volume Associated with Functional Outcome in Intracerebral Hemorrhage

BACKGROUND

Our objective was to test the association between hematoma volume and long-term (> 72 h) edema extension distance (EED) evolution and the association between peak EED and early EED increase with functional outcome at 3 months in patients with intracerebral hemorrhage (ICH).

METHODS

This retrospective cohort study included patients with spontaneous supratentorial ICH between January 2006 and January 2014. EED, an edema measure defined as the distance between the hematoma border and the outer edema border, was calculated by using absolute hematoma and edema volumes. We used multivariable logistic regression accounting for age, ICH volume, and location and receiver operating characteristic analysis for assessing measures associated with functional outcome and EED evolution. Functional outcome after 3 months was assessed by using the modified Rankin Scale (0-3 = favorable, 4-6 = unfavorable). To identify properties associated with peak EED multivariable linear and logistic regression analyses were conducted.

RESULTS

A total of 292 patients were included. Median age was 70 years (interquartile range [IQR] 62-78), median ICH volume on admission 17.7 mL (IQR 7.9-40.2), median peak perihemorrhagic edema (PHE) volume was 37.5 mL (IQR 19.1-60.6), median peak EED was 0.67 cm (IQR 0.51-0.84) with an early EED increase up to 72 h (EED72-0) of 0.06 cm (- 0.02 to 0.15). Peak EED was found to be independent of ICH volume (R2 = 0.001, p = 0.6). In multivariable analyses, peak EED (odds ratio 0.224, 95% confidence interval [CI] [0.071-0.705]) and peak PHE volume (odds ratio 0.984 [95% CI 0.973-0.994]) were inversely associated with favorable functional outcome at 3 months. Receiver operating characteristic analysis identified a peak PHE volume of 26.8 mL (area under the curve 0.695 [95% CI 0.632-0.759]; p ≤ 0.001) and a peak EED of 0.58 cm (area under the curve 0.608 [95% CI 0.540-0.676]; p = 0.002) as best predictive values for outcome discrimination.

CONCLUSIONS

Compared with absolute peak PHE volume, peak EED represents a promising edema measure in patients with ICH that is largely hematoma volume-independent and nevertheless associated with functional outcome.

Colony Stimulating Factor-1 Receptor: An emerging target for neuroinflammation PET imaging and AD therapy

Although neuroinflammation is a significant pathogenic feature of many neurologic disorders, its precise function in-vivo is still not completely known. PET imaging enables the longitudinal examination, quantification, and tracking of different neuroinflammation biomarkers in living subjects. Particularly, PET imaging of Microglia, specialised dynamic immune cells crucial for maintaining brain homeostasis in central nervous system (CNS), is crucial for staging the neuroinflammation. Colony Stimulating Factor- 1 Receptor (CSF-1R) PET imaging is a novel method for the quantification of neuroinflammation. CSF-1R is mainly expressed on microglia, and neurodegenerative disorders greatly up-regulate its expression. The present review primarily focuses on the development, pros and cons of all the CSF-1R PET tracers reported for neuroinflammation imaging. Apart from neuroinflammation imaging, CSF-1R inhibitors are also reported for the therapy of neurodegenerative diseases such as Alzheimer's disease (AD). AD is a prevalent, advancing, and fatal neurodegenerative condition that have the characteristic feature of persistent neuroinflammation and primarily affects the elderly. The aetiology of AD is profoundly influenced by amyloid-beta (Aβ) plaques, intracellular neurofibrillary tangles, and microglial dysfunction. Increasing evidence suggests that CSF-1R inhibitors (CSF-1Ri) can be helpful in preclinical models of neurodegenerative diseases. This review article also summarises the most recent developments of CSF-1Ri-based therapy for AD.

Rice bran extract mitigates depressive-like behavior in dextran sulfate sodium-induced colitis: Involvement of the gut-brain axis and Sirt1 signaling pathway

Inflammatory bowel disease (IBD) patients frequently suffer from depressive disorders as well. The present study was carried out to explore whether treatment with a standardized rice bran extract (RBE) could affect depression-like behavior in rats with dextran sulfate sodium (DSS)-induced colitis. Male Wistar rats were treated with RBE (100 mg/kg/day; p.o.) for 2 weeks. During the second week, colitis was induced by feeding the rats with 5 % (w/v) DSS in drinking water. RBE protected against DSS-induced body weight loss as well as against the macro- and microscopic inflammatory changes of the colon. Additionally, RBE mitigated DSS-induced dysregulation in blood-brain barrier tight junctional proteins, preserved the hippocampal histopathological architecture and improved the animal behavior in the forced swimming test. This was associated with modulation of hippocampal oxidative stress marker; GSH as well as hippocampal pro-inflammatory mediators; NF-ĸB and IL-1β. Treatment with RBE also led to a profound increase in the hippocampal levels of Sirt1, PGC-1α, Nrf2, and HO-1, which were drastically dropped by DSS. In conclusion, the study revealed the protective effect of RBE against DSS-induced depressive-like behavior through modulation of different parameters along the gut-brain axis and up-regulated the Sirt1/PGC-1α/Nrf2/HO-1 signaling pathway.

Licochalcone A Inhibits Prostaglandin E2 by Targeting the MAPK Pathway in LPS Activated Primary Microglia

Neuroinflammation and oxidative stress are conditions leading to neurological and neuropsychiatric disorders. Natural compounds exerting anti-inflammatory and anti-oxidative effects, such as Licochalcone A, a bioactive flavonoid present in a traditional Chinese herb (licorice), might be beneficial for the treatment of those disorders. Therefore, this study aimed to investigate the anti-inflammatory and anti-oxidative effects of Licochalcone A in LPS-activated primary rat microglia. Licochalcone A dose-dependently prevented LPS-induced PGE₂ release by inhibiting the arachidonic acid (AA)/cylcooxygenase (COX) pathway decreasing phospholipase A2, COX-1, and COX-2 protein levels. Furthermore, LPS-induced levels of the cytokines IL-6 and TNFα were reduced by Licochalcone A, which also inhibited the phosphorylation and, thus, activation of the mitogen-activated protein kinases (MAPK) p38 MAPK and Erk 1/2. With the reduction of 8-iso-PGF_2α, a sensitive marker for oxidative stress, anti-oxidative effects of Licochalcone A were demonstrated. Our data demonstrate that Licochalcone A can affect microglial activation by interfering in important inflammatory pathways. These in vitro findings further demonstrate the potential value of Licochalcone A as a therapeutic option for the prevention of microglial dysfunction related to neuroinflammatory diseases. Future research should continue to investigate the effects of Licochalcone A in different disease models with a focus on its anti-oxidative and anti-neuroinflammatory properties.

The Neuroprotective Effects and Therapeutic Potential of the Chalcone Cardamonin for Alzheimer's Disease

Neurodegenerative diseases (ND) include a wide range of conditions that result from progressive damage to the neurons. Alzheimer's disease (AD) is one of the most common NDs, and neuroinflammation and oxidative stress (OS) are the major factors in the development and progression of the disease. Many naturally occurring phytochemical compounds exhibit antioxidant and anti-inflammatory activities with potential neuroprotective effects. Several plant species, including Alpinia katsumadai and Alpinia conchigera, contain cardamonin (CD). CD (2',4'-dihydroxy-6'methoxychalcone) has many therapeutic properties, including anticancer, anti-inflammatory, antioxidant, antiviral, and antibiotic activities. CD is a potent compound that can reduce OS and modulate the inflammatory processes that play a significant part in developing neurodegenerative diseases. CD has been shown to modulate a variety of signaling molecules involved in the development and progression of ND, including transcription factors (NF-kB and STAT3), cytokines (TNF-α, IL-1, and IL-6), enzymes (COX-2, MMP-9, and ALDH1), and other proteins and genes (Bcl-2, XIAP, and cyclin D1). Additionally, CD effectively modulates miRNA levels and autophagy-related CD-protective mechanisms against neurodegeneration. In summary, this review provides mechanistic insights into CD's ability to modify multiple oxidative stress-antioxidant system pathways, Nrf2, and neuroinflammation. Additionally, it points to the possible therapeutic potential and preventive utilization of CD in neurodegenerative diseases, most specifically AD.

Tryptamine, a Microbial Metabolite in Fermented Rice Bran Suppressed Lipopolysaccharide-Induced Inflammation in a Murine Macrophage Model

Fermentation is thought to alter the composition and bioavailability of bioactive compounds in rice bran. However, how this process affects the anti-inflammatory effects of rice bran and the bioactive compounds that might participate in this function is yet to be elucidated. This study aimed to isolate bioactive compounds in fermented rice bran that play a key role in its anti-inflammatory function. The fermented rice bran was fractionated using a succession of solvent and solid-phase extractions. The fermented rice bran fractions were then applied to lipopolysaccharide (LPS)-activated murine macrophages to evaluate their anti-inflammatory activity. The hot water fractions (FRBA), 50% ethanol fractions (FRBB), and n-hexane fractions (FRBC) were all shown to be able to suppress the pro-inflammatory cytokine expression from LPS-stimulated RAW 264.7 cells. Subsequent fractions from the hot water fraction (FRBF and FRBE) were also able to reduce the inflammatory response of these cells to LPS. Further investigation revealed that tryptamine, a bacterial metabolite of tryptophan, was abundantly present in these extracts. These results indicate that tryptamine may play an important role in the anti-inflammatory effects of fermented rice bran. Furthermore, the anti-inflammatory effects of FRBE and tryptamine may depend on the activity of the aryl hydrocarbon receptor.

Role of p53 methylation in manganese-induced cyclooxygenase-2 expression in BV2 microglial cells

Manganese (Mn) is an essential cofactor for many enzymes and plays an important role in normal growth and development. However, excess exposure to manganese (Mn) may be an important environmental factor leading to neurodegeneration. The overexpression of microglial cyclooxygenase-2 (COX-2) plays a key role in neuroinflammation in neurodegenerative diseases. The existing data suggest that Mn can induce neuroinflammation by up-regulating COX-2 expression. However, the mechanisms involved in Mn-induced microglial COX-2 up-regulation remain to be determined. The aim of this study was to investigate the role of p53 in Mn-induced COX-2 expression in microglial cells. The results showed that Mn exposure induced the up-regulation of COX-2 and inhibited the expression of p53 in BV2 microglial cells. The addition of p53 activator and the over-expression of p53 blocked the expression of COX-2 and prostaglandin E2 (PGE2), a COX-2 downstream effector, induced by Mn. Further, Mn increased the methylation of p53 DNA in microglia, while the addition of demethylation reagent 5-Aza-dC enhanced the expression of p53 but decreased the expression of COX-2. These results suggested that Mn may inhibit p53 expression through induction of DNA methylation, which can further induce the expression of COX-2 in microglial cells.

Microglia and HPA axis in depression: An overview of participation and relationship

Objectives: This narrative review article provides an overview on the involvement of microglia and the hypothalamic-pituitary-adrenal (HPA) axis in the pathophysiology of depression, as well investigates the mutual relationship between these two entities: how microglial activation can contribute to the dysregulation of the HPA axis, and vice versa.Methods: Relevant studies and reviews already published in the Pubmed electronic database involving the themes microglia, HPA axis and depression were used to meet the objectives.Results: Exposition to stressful events is considered a common factor in the mechanisms proposed to explain the depressive disorder. Stress can activate microglial cells, important immune components of the central nervous system (CNS). Moreover, another system involved in the physiological response to stressors is the hypothalamic-pituitary-adrenal (HPA) axis, the main stress response system responsible for the production of the glucocorticoid hormone (GC). Also, mediators released after microglial activation can stimulate the HPA axis, inducing production of GC. Likewise, high levels of GCs are also capable of activating microglia, generating a vicious cycle.Conclusion: Immune and neuroendocrine systems seems to work in a coordinated manner and that their dysregulation may be involved in the pathophysiology of depression since neuroinflammation and hypercortisolism are often observed in this disorder.

Iron toxicity in intracerebral hemorrhage: Physiopathological and therapeutic implications

Intracerebral hemorrhage (ICH)-induced brain injury is a continuous pathological process that involves the deterioration of neurological functions, such as sensory, cognitive or motor functions. Cytotoxic byproducts of red blood cell lysis, especially free iron, appear to be a significant pathophysiologic mechanism leading to ICH-induced injury. Free iron has a crucial role in secondary brain injury after ICH. Chelating iron may attenuate iron-induced neurotoxicity and may be developed as a therapeutic candidate for ICH treatment. In this review, we focused on the potential role of iron toxicity in ICH-induced injury and iron chelation therapy in the management of ICH. It will hopefully advance our understanding of the pathogenesis of ICH and lead to new approaches for treatment.

Functional Profiling and Future Research Direction of Rice Bran Oil in Bangladesh

Rice bran oil (RBO) has been demonstrated to affect complex malfunctioned conditions such as oxidative stress, hyperlipidemia, hyperglycemia, hypertension, inflammation, abnormal cell growth (cancer), ulceration, immune and cognitive modulation. This unique effect of RBO is due to the presence of well-balanced fatty acid composition and several bioactive compounds, γ- oryzanol (cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, campesterol ferulate, and β-sitosteryl ferulate), vitamin E (tocopherol and tocotrienol), phytosterols (β-sitosterol, campesterol and stigmasterol) and other nutrients. The RBO composition of bioactive compounds varied geographically, thus the clear-cut mechanisms of action on complex disease cascades are still required. This review article summarized the RBO compositional profiling and compared it with other edible oils. This article also summarized Bangladesh RBO profiling and their proposed mechanism of action as well as the first line of defense in the prevention, management, and control of complex disease conditions. This review indicates how Bangladesh RBO increase their opportunity to be functional food for 21st century's ailment.

Phytoconstituents from ten natural herbs as potent inhibitors of main protease enzyme of SARS-COV-2: In silico study

BACKGROUND

Lack of treatment of novel Coronavirus disease led to the search of specific antivirals that are capable to inhibit the replication of the virus. The plant kingdom has demonstrated to be an important source of new molecules with antiviral potential.

PURPOSE

The present study aims to utilize various computational tools to identify the most eligible drug candidate that have capabilities to halt the replication of SARS-COV-2 virus by inhibiting Main protease (Mpro) enzyme.

METHODS

We have selected plants whose extracts have inhibitory potential against previously discovered coronaviruses. Their phytoconstituents were surveyed and a library of 100 molecules was prepared. Then, computational tools such as molecular docking, ADMET and molecular dynamic simulations were utilized to screen the compounds and evaluate them against Mpro enzyme.

RESULTS

All the phytoconstituents showed good binding affinities towards Mpro enzyme. Among them laurolitsine possesses the highest binding affinity i.e. -294.1533 kcal/mol. On ADMET analysis of best three ligands were simulated for 1.2 ns, then the stable ligand among them was further simulated for 20 ns. Results revealed that no conformational changes were observed in the laurolitsine w.r.t. protein residues and low RMSD value suggested that the Laurolitsine-protein complex was stable for 20 ns.

CONCLUSION

Laurolitsine, an active constituent of roots of Lindera aggregata, was found to be having good ADMET profile and have capabilities to halt the activity of the enzyme. Therefore, this makes laurolitsine a good drug candidate for the treatment of COVID-19.

Possible role of rice bran extract in microglial modulation through PPAR-gamma receptors in alzheimer's disease mice model

Alzheimer's Disease (AD), the most prevalent neurodegenerative disorder among elderly people, is ordinarily associated with progressive cognitive decline. Peroxisome proliferator-activated receptors-gamma (PPAR-γ) agonists can be targeted as a beneficial therapeutic strategy against AD. In the present study, we aimed to investigate the preventive and therapeutic effects of rice bran extract (RBE) as a possible PPAR-γ agonist on the microglial phenotype modulation in AD in mice compared to the effects of pioglitazone. This study included 64 adult male Swiss Albino mice divided into 8 groups, each group comprised 8 mice; control group, RBE group, lipopolysaccharide-induced neurodegeneration (a) (LPSa) group, (LPSb) group, RBE-preventive group (RBE + LPSa), pioglitazone-preventive group (PG + LPSa), RBE-treated group (RBE + LPSb), and pioglitazone-treated group (PG + LPSb). Cognitive functions were assessed by Y-maze and Morris water maze tests. The expression of PPAR-γ, CD45, arginase1, CD36, and CD163 genes was assessed by real time qPCR and the estimation of NF-kβ protein level was done by Western blot technique. Moreover, the assessment of Aβ42 and P-tau levels was performed by ELISA. Histopathological examination of brain tissues was performed for all the studied groups. Our results showed that RBE and pioglitazone could modulate microglial phenotype from M1 to M2 where they significantly decreased the expression of NF-κβ and the pro-inflammatory microglial marker (CD45) in parallel with increasing the expression of the anti-inflammatory microglial and phagocytic markers (arginase1, CD163, and CD36). In addition, RBE and pioglitazone significantly increased PPAR-γ expression and reduced Aβ42 deposition as well as p-tau protein levels. In conclusion, our study identified the possible role of PPAR-γ agonistic activity of RBE as a preventive and therapeutic agent in the treatment of the neuro-inflammation associated with AD.

The Role of Distinct Subsets of Macrophages in the Pathogenesis of MS and the Impact of Different Therapeutic Agents on These Populations

Multiple sclerosis (MS) is a demyelinating inflammatory disorder of the central nervous system (CNS). Besides the vital role of T cells, other immune cells, including B cells, innate immune cells, and macrophages (MФs), also play a critical role in MS pathogenesis. Tissue-resident MФs in the brain’s parenchyma, known as microglia and monocyte-derived MФs, enter into the CNS following alterations in CNS homeostasis that induce inflammatory responses in MS. Although the neuroprotective and anti-inflammatory actions of monocyte-derived MФs and resident MФs are required to maintain CNS tolerance, they can release inflammatory cytokines and reactivate primed T cells during neuroinflammation. In the CNS of MS patients, elevated myeloid cells and activated MФs have been found and associated with demyelination and axonal loss. Thus, according to the role of MФs in neuroinflammation, they have attracted attention as a therapeutic target. Also, due to their different origin, location, and turnover, other strategies may require to target the various myeloid cell populations. Here we review the role of distinct subsets of MФs in the pathogenesis of MS and different therapeutic agents that target these cells.

PLXNA2 knockdown promotes M2 microglia polarization through mTOR/STAT3 signaling to improve functional recovery in rats after cerebral ischemia/reperfusion injury

Ischemic stroke is an acute cerebrovascular disease characterized by high mortality, morbidity and disability rates. Ischemia/reperfusion is a critical pathophysiological basis of motor and cognitive dysfunction caused by ischemic stroke. Microglia, innate immune cells of the central nervous system, mediate the neuroinflammatory response to ischemia/reperfusion. PlexinA2 (PLXNA2) plays an important role in the regulation of neuronal axon guidance, the immune response and angiogenesis. However, it is not clear whether PLXNA2 regulates microglia polarization in ischemic stroke or the underlying mechanism. In the present study, we investigated the role of PLXNA2 in rats with middle cerebral artery occlusion/reperfusion (MCAO/R) and BV2 microglia cells with oxygen and glucose deprivation/reoxygenation (OGD/R). A battery of behavioral tests, including the beam balance test, forelimb placement test, foot fault test, cylinder test, CatWalk gait analysis and Morris water maze test were performed to evaluate sensorimotor function, locomotor activity and cognitive ability. The expression of M1/M2-specific markers in the ischemic penumbra and BV2 microglia cells was detected using immunofluorescence staining, quantitative real-time PCR analysis and Western blot analysis. Our study showed that PLXNA2 knockdown accelerated the recovery of motor function and cognitive ability after MCAO/R. In addition, PLXNA2 knockdown restrained proinflammatory cytokine release and promoted anti-inflammatory cytokine release, and the mammalian target of rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3) pathway was involved in PLXNA2 regulated microglia polarization. Taken together, our results indicate that PLXNA2 knockdown reduces neuroinflammation by switching the microglia phenotype from M1 to M2 in the ischemic penumbra of MCAO/R-injured rats, which may be due to the inhibition of mTOR/STAT3 signaling. Treatments targeting PLXNA2 may be a promising therapeutic strategy for ischemic stroke.

The impact of early life stress and immune challenge on behavior and glia cells alteration in late adolescent rats

Maternal deprivation (MD) is known to be related to long-term changes that could influence the onset of psychiatric disorders. Studies have demonstrated that early life stress makes the cells in the brain more susceptible to subsequent stressors. To test it, we used an animal model of MD conducted from postnatal day (PND) 1 to 10. Deprived and non-deprived rats (control) were randomized to receive or not lipopolysaccharide (LPS) at 5 mg/kg on PND 50. The behavior and glial cells activation were evaluated in all groups from 51 to 53 PND. There was an increase in the immobility time in the MD and MD+LPS groups. The spontaneous locomotor activity was not changed between groups. We found elevated ionized calcium-binding adapter molecule 1 (Iba-1)-positive cells levels in the control+LPS and MD+LPS groups. In the MD+LPS group, it was found an increase in Iba-positive cells compared to the MD+sal group. The glial fibrillary acidic protein (GFAP)-positive cells were also increased in the MD+LPS, compared to control+sal, control+LPS, and MD+sal groups. Immune challenge by LPS in late adolescence, which was subjected to MD, did not influence the depressive-like behavior but exerted a pronounced effect in the microglial activation and astrocyte atrophy.

Rice bran, an off-shoot to newer therapeutics in neurological disorders

Normal brain functioning involves the interaction of interconnected molecular and cellular activities, which appear to alter normal to abnormal brain functioning when worsened, contributing to the emergence of neurological disorders. There are currently millions of people who are living with brain disorders globally and this will rise if suitable prevention strategies are not explored. Nutraceutical intended to treat numerous health goals with little adverse effect possible together can be more beneficial than pharmaceutical monotherapy for fostering balanced brain functioning. Nutraceutical provides a specific composition of effective macronutrients and micronutrients that are difficult to synthesize in the laboratory. Numerous elements of rice fibers in rice bran are characterized as natural anti-oxidant and having potential anti-inflammatory activity. The rice bran captures interest among the researchers as it is widespread, affordable, and rich in nutrients including protein, fat, carbohydrates, bioactive components, and dietary fiber. This review covers the neuroprotective multiplicity of rice bran and its constituents to deter pathological conditions of the brain and to facilitate balanced brain functioning at the same time.

Blood-brain barrier dysfunction in hemorrhagic transformation: a therapeutic opportunity for nanoparticles and melatonin

Stroke is the second leading cause of death worldwide, estimated that one-sixth of the world population will suffer it once in their life. The most common type of this medical condition is the ischemic stroke (IS), produced by a thrombotic or embolic occlusion of a major cerebral artery or its branches, leading to the formation of a complex infarct region caused by oxidative stress, excitotoxicity, and endothelial dysfunction. Nowadays, the immediate treatment for IS involves thrombolytic agents or mechanical thrombectomy, depending on the integrity of the blood-brain barrier (BBB). A common stroke complication is the hemorrhagic transformation (HT), which consists of bleeding into the ischemic brain area. Currently, better treatments for IS are urgently needed. As such, the neurohormone melatonin has been proposed as a good candidate due to its antioxidant, anti-inflammatory, and neuroprotective effects, particularly against lipid peroxidation and oxidative stress during brain ischemia. Here, we proposed to develop intravenous or intranasal melatonin nanoformulation to specifically target the brain in patients with stroke. Nowadays, the challenge is to find a formulation able to cross the barriers and reach the target organ in an effective dose to generate the pharmacological effect. In this review, we discuss the current literature about stroke pathophysiology, melatonin properties, and its potential use in nanoformulations as a novel therapeutic approach for ischemic stroke.

Effects of a Novel GPR55 Antagonist on the Arachidonic Acid Cascade in LPS-Activated Primary Microglial Cells

Neuroinflammation is a crucial process to maintain homeostasis in the central nervous system (CNS). However, chronic neuroinflammation is detrimental, and it is described in the pathogenesis of CNS disorders, including Alzheimer’s disease (AD) and depression. This process is characterized by the activation of immune cells, mainly microglia. The role of the orphan G-protein-coupled receptor 55 (GPR55) in inflammation has been reported in different models. However, its role in neuroinflammation in respect to the arachidonic acid (AA) cascade in activated microglia is still lacking of comprehension. Therefore, we synthesized a novel GPR55 antagonist (KIT 10, 0.1–25 µM) and tested its effects on the AA cascade in lipopolysaccharide (LPS, 10 ng / mL)-treated primary rat microglia using Western blot and EIAs. We show here that KIT 10 potently prevented the release of prostaglandin E₂ (PGE₂), reduced microsomal PGE₂ synthase (mPGES-1) and cyclooxygenase-2 (COX-2) synthesis, and inhibited the phosphorylation of Ikappa B-alpha (IκB-α), a crucial upstream step of the inflammation-related nuclear factor-kappaB (NF-κB) signaling pathway. However, no effects were observed on COX-1 and -2 activities and mitogen-activated kinases (MAPK). In summary, the novel GPR55 receptor antagonist KIT 10 reduces neuroinflammatory parameters in microglia by inhibiting the COX-2/PGE₂ pathway. Further experiments are necessary to better elucidate its effects and mechanisms. Nevertheless, the modulation of inflammation by GPR55 might be a new therapeutic option to treat CNS disorders with a neuroinflammatory background such as AD or depression.

Intrauterine inflammation induced white matter injury protection by fibrinogen-like protein 2 deficiency in perinatal mice

BACKGROUND

White matter injury (WMI) induced by intrauterine inflammation can cause adverse neurological outcomes. Fibrinogen-like protein 2 (FGL2)/fibroleukin is an important trigger of inflammatory responses and is involved in some cerebral diseases. However, the role of FGL2 in intrauterine inflammation-induced WMI remains unclear.

METHODS

Lipopolysaccharide (LPS) was intraperitoneally injected into wild-type and FGL2 knockout mice to induce intrauterine inflammation. Body weight and brain weight of offspring were monitored. Major basic protein (MBP) expression was evaluated to demonstrate the myelination of offspring. To investigate the regulatory mechanism of FGL2, cytokine expression, microglial polarization, and the activation of mitogen-activated protein kinase (MAPK) signaling pathway in the offspring were analyzed.

RESULTS

Upon LPS exposure, FGL2 knockout offspring showed a significant increase in body weight loss. MBP reduction induced by LPS was prevented in FGL2 knockout offspring. Expression levels of proinflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α, and M1 marker CD86 were suppressed, while the expression levels of anti-inflammatory cytokines IL-10 and M2 marker CD206 were increased. FGL2 deficiency significantly inhibited the phosphorylation of p38MAPK and c-Jun N-terminal kinase (JNK) protein.

CONCLUSIONS

FGL2 deficiency can ameliorate WMI induced by intrauterine inflammation, reducing inflammatory cascade and improving hypomyelination, through the regulation of microglial polarization and MAPK signaling pathways.

IMPACT

Intrauterine inflammation induces WMI leading to severe neurological sequelae. FGL2 plays an important role in the progression of WMI induced by intrauterine inflammation. FGL2 deficiency can protect against WMI by inhibiting p38 MAPK and JNK phosphorylation, regulating microglia polarization, and reducing inflammation response. FGL2 could be a novel molecular target for protecting against WMI induced by intrauterine inflammation.

NOD1/RIP2 signalling enhances the microglia-driven inflammatory response and undergoes crosstalk with inflammatory cytokines to exacerbate brain damage following intracerebral haemorrhage in mice

BACKGROUND

Secondary brain damage caused by the innate immune response and subsequent proinflammatory factor production is a major factor contributing to the high mortality of intracerebral haemorrhage (ICH). Nucleotide-binding oligomerization domain 1 (NOD1)/receptor-interacting protein 2 (RIP2) signalling has been reported to participate in the innate immune response and inflammatory response. Therefore, we investigated the role of NOD1/RIP2 signalling in mice with collagenase-induced ICH and in cultured primary microglia challenged with hemin.

METHODS

Adult male C57BL/6 mice were subjected to collagenase for induction of ICH model in vivo. Cultured primary microglia and BV2 microglial cells (microglial cell line) challenged with hemin aimed to simulate the ICH model in vitro. We first defined the expression of NOD1 and RIP2 in vivo and in vitro using an ICH model by western blotting. The effect of NOD1/RIP2 signalling on ICH-induced brain injury volume, neurological deficits, brain oedema, and microglial activation were assessed following intraventricular injection of either ML130 (a NOD1 inhibitor) or GSK583 (a RIP2 inhibitor). In addition, levels of JNK/P38 MAPK, IκBα, and inflammatory factors, including tumour necrosis factor-α (TNF-α), interleukin (IL)-1β, and inducible nitric oxide synthase (iNOS) expression, were analysed in ICH-challenged brain and hemin-exposed cultured primary microglia by western blotting. Finally, we investigated whether the inflammatory factors could undergo crosstalk with NOD1 and RIP2.

RESULTS

The levels of NOD1 and its adaptor RIP2 were significantly elevated in the brains of mice in response to ICH and in cultured primary microglia, BV2 cells challenged with hemin. Administration of either a NOD1 or RIP2 inhibitor in mice with ICH prevented microglial activation and neuroinflammation, followed by alleviation of ICH-induced brain damage. Interestingly, the inflammatory factors interleukin (IL)-1β and tumour necrosis factor-α (TNF-α), which were enhanced by NOD1/RIP2 signalling, were found to contribute to the NOD1 and RIP2 upregulation in our study.

CONCLUSION

NOD1/RIP2 signalling played an important role in the regulation of the inflammatory response during ICH. In addition, a vicious feedback cycle was observed between NOD1/RIP2 and IL-1β/TNF-α, which could to some extent result in sustained brain damage during ICH. Hence, our study highlights NOD1/RIP2 signalling as a potential therapeutic target to protect the brain against secondary brain damage during ICH.

Rice Bran Extract Protected against LPS-Induced Neuroinflammation in Mice through Targeting PPAR-γ Nuclear Receptor

PPAR-γ anti-inflammatory functions have received significant attention since its agonists have been shown to exert a wide range of protective effects in many experimental models of neurologic diseases. Rice bran is very rich in polyunsaturated fatty acids, which are reported to act as PPAR-γ partial agonists. Herein, the anti-inflammatory effect of rice bran extract (RBE) through PPAR-γ activation was evaluated in LPS-induced neuroinflammatory mouse model in comparison to pioglitazone (PG) using 80 Swiss albino mice. RBE (100 mg/kg) and PG (30 mg/kg) were given orally for 21 days and LPS (0.25 mg/kg) was injected intraperitoneally for the last 7 days. TNF-α and COX-2 brain contents were evaluated by real-time PCR and immunohistochemical analysis. In addition, NFκB binding to its response element was evaluated alongside with the effect of treatments on IκB gene expression. Furthermore, PPAR-γ sumoylation was also studied. Finally, histopathological examination was performed for different brain areas. RBE administration was found to protect against the LPS-induced inflammatory effects by decreasing the inflammatory mediator expression in mice brains. It also decreased PPAR-γ sumoylation without significant effect on IκB expression or NFκB binding to its response element. The majority of the effects were attenuated in presence of PPAR-γ antagonist (GW9662). Level of significance was set to P < 0.05. Such findings highlight the agonistic effect of RBE component(s) on PPAR-γ and support the hypothesis of involvement of PPAR-γ activation in its neuroprotective effect.

Stroke treatment: Is exosome therapy superior to stem cell therapy?

Stroke is one of the most common causes of disability and death, and currently, ideal clinical treatment is lacking. Stem cell transplantation is a widely-used treatment approach for stroke. When compared with other types of stem cells, bone marrow mesenchymal stem cells (BMSCs) have been widely studied because of their many advantages. The paracrine effect is the primary mechanism for stem cells to play their role, and exosomes play an essential role in the paracrine effect. When compared with cell therapy, cell-free exosome therapy can prevent many risks and difficulties, and therefore, represents a promising and novel approach for treatment. In this study, we reviewed the research progress in the application of BMSCs-derived exosomes (BMSCs-exos) and BMSCs in the treatment of stroke. In addition, the advantages and disadvantages of cell therapy and cell-free exosome therapy were described, and the possible factors that hinder the introduction of these two treatments into the clinic were analyzed. Furthermore, we reviewed the current optimization methods of cell therapy and cell-free exosome therapy. Taken together, we hypothesize that cell-free exosome therapy will have excellent research prospects in the future, and therefore, it is worth further exploring. There are still some issues that need to be further addressed. For example, differences between the in vivo microenvironment and in vitro culture conditions will affect the paracrine effect of stem cells. Most importantly, we believe that more preclinical and clinical design studies are required to compare the efficacy of stem cells and exosomes.

Cellular uptake and anti-inflammatory effects of palm oil-derived delta (δ)-tocotrienol in microglia

Tocopherols long dominated studies on vitamin E, although interest has shifted to tocotrienols. It was previously shown that δ-tocotrienol derived from palm oil reduced nitric oxide released by BV2 microglia as early as 18 h after lipopolysaccharide stimulation. The current study measured δ-tocotrienol uptake by BV2 over a 24 h incubation period and its anti-inflammatory effects on primary microglia. Uptake of 17.5 μg/mL δ-tocotrienol by BV2 microglia began as early as 5 min and rose steeply to 21 ± 3% of the amount administered at 24 h. The amount of δ-tocotrienol retained in the lipopolysaccharide-stimulated microglia at 24 h was 14 ± 2%, with no substantial difference seen in unstimulated microglia. The same δ-tocotrienol regimen reduced nitric oxide levels by 82% at 24 h after lipopolysaccharide stimulation (p < 0.05). This was accompanied by decreased inducible nitric oxide synthase protein expression by 67 ± 5% compared to untreated controls (p < 0.05). In primary microglia, δ-tocotrienol downregulated IL-1β production, but TNF-α and IL-6 were not affected. δ-Tocotrienol also reduced prostaglandin E2 production by ~78%% and decreased transcription of COX-2 and 5-LOX, but not COX-1. This study showed the anti-inflammatory effects of δ-tocotrienol derived from palm oil and opens up interest for tocotrienol supplementation to reduce the effects of inflammatory conditions.

Discovery of a novel small molecule PT109 with multi-targeted effects against Alzheimer's disease in vitro and in vivo

Alzheimer's disease (AD), which is characterized by impairment of cognitive functions, is a chronic neurodegenerative disease that mainly affects the elderly. Currently available anti-AD drugs can only offer limited symptom-relieving effects. "One-compound-Multitargeted Strategy" have been recognized as the promising way to win the war against AD. Herein we report a potential anti-AD agent PT109 with multi-functions. First, an 81-kinase screening was carried out and results showed that PT109 potently inhibited c-Jun N-terminal kinases and Serum and glucocorticoid-inducible kinase 1, which are the important signaling molecules involved in neurogenesis, neuroprotection and neuroinflammation and mildly inhibit glycogen synthase kinase-3β as well as protein kinase C gamma, both are involved in AD pathological processes. In addition, invitro studies of immunofluorescent staining and Western blot showed that PT109 might promote the neurogenesis of C17.2 cells and induce synaptogenesis in primary cultured rat hippocampal neurons. We detected and confirmed the neuroprotective effect of PT109 in cultured HT22 cells by MTT assay, dehydrogenase assay, glutathione assay and reactive oxygen species assay. Furthermore, the results of Western blot, ELISA assay and immunofluorescent staining indicated that PT109 attenuated lipopolysaccharide-induced inflammation in BV2 cells and primary astrocytes. The results of Morris water maze and Step-through test indicated that PT109 improved the spatial learning ability in APP/PS1 mice. More importantly, the invivo pharmacokinetic parameters indicated that PT109 had better medicinal properties. Taken together, our findings suggest that PT109 may be a promising candidate for treating AD through multiple targets although further studies are ought to be conducted.

Hibiscus sabdariffa L.: A potent natural neuroprotective agent for the prevention of streptozotocin-induced Alzheimer's disease in mice

Hibiscus sabdariffa L. (Malvaceae) is one of the well-known traditionally used remedy worldwide. It exhibited numerous pharmacological properties including antioxidant, antidepressant, sedative, anti-inflammatory, antiproliferative, antimicrobial and neuroprotective activities. The aim of this study is to highlight the mechanisms underlying the neuroprotective effects of anthocyanin-enriched extracts of two Hibiscus varieties (white and red calyces) in the management of Alzheimer's disease (AD) in addition to their metabolic profiling. The anthocyanin contents were determined quantitatively using the pH-differential technique and qualitatively by LC/MS/MS. The extracts were tested in vitro for their antioxidant potential as well as acetylcholinesterase inhibition activity and both showed promising activities. The LC/MS/MS analysis allowed the tentative identification of 26 and 24 metabolites in red and white calyces, respectively, represented by anthocyanins, flavonoids, aliphatic and phenolic acids. In vivo, streptozotocin induced AD in mice model was established and Hibiscus extracts were tested at a dose of 200 mg kg^-1 compared to celecoxib (30 mg/kg). Histopathology of cerebral cortex and hippocampus, immunohistochemistry for tau- protein and caspase-3 with behavioral tests and measurement of several biochemical parameters were done. Hibiscus prevented memory impairment, and this could be attributed to the amelioration of STZ-induced neuroinflammation and amyloidogenesis. Consequently, Hibiscus represents a promising safe agent that can be repurposed for AD through exerting anti-inflammatory, anti-acetylcholinesterase, antioxidant, and anti-amyloidogenic activities.

MsrA Suppresses Inflammatory Activation of Microglia and Oxidative Stress to Prevent Demyelination via Inhibition of the NOX2-MAPKs/NF-κB Signaling Pathway

Introduction

Demyelination causes neurological deficits involving visual, motor, sensory symptoms. Deregulation of several enzymes has been identified in demyelination, which holds potential for the development of treatment strategies for demyelination. However, the specific effect of methionine sulfoxide reductase A (MsrA) on demyelination remains unclear. Hence, this study aims to explore the effect of MsrA on oxidative stress and inflammatory response of microglia in demyelination.

Methods

Initially, we established a mouse model with demyelination induced by cuprizone and a cell model provoked by lipopolysaccharide (LPS). The expression of MsrA in wild-type (WT) and MsrA-knockout (MsrA^-/-) mice were determined by RT-qPCR and Western blot analysis. In order to further explore the function of MsrA on inflammatory response, and oxidative stress in demyelination, we detected the expression of microglia marker Iba1, inflammatory factors TNF-α and IL-1β and intracellular reactive oxygen species (ROS), superoxide dismutase (SOD) activity, as well as expression of the NOX2-MAPKs/NF-κB signaling pathway-related genes in MsrA^-/- mice and LPS-induced microglia following different treatments.

Results

MsrA expression was downregulated in MsrA^-/- mice. MsrA silencing was shown to produce severely injured motor coordination, increased expressions of Iba1, TNF-α, IL-1β, ROS and NOX2, and extent of ERK, p38, IκBα, and p65 phosphorylation, but reduced SOD activity. Conjointly, our study suggests that Tat-MsrA fusion protein can prevent the cellular inflammatory response and subsequent demyelination through negative regulation of the NOX2-MAPKs/NF-κB signaling pathway.

Conclusion

Our data provide a profound insight on the role of endogenous antioxidative defense systems such as MsrA in controlling microglial function.

Dectin-1/Syk signaling triggers neuroinflammation after ischemic stroke in mice

Background

Dendritic cell-associated C-type lectin-1 (Dectin-1) receptor has been reported to be involved in neuroinflammation in Alzheimer’s disease and traumatic brain injury. The present study was designed to investigate the role of Dectin-1 and its downstream target spleen tyrosine kinase (Syk) in early brain injury after ischemic stroke using a focal cortex ischemic stroke model.

Methods

Adult male C57BL/6 J mice were subjected to a cerebral focal ischemia model of ischemic stroke. The neurological score, adhesive removal test, and foot-fault test were evaluated on days 1, 3, 5, and 7 after ischemic stroke. Dectin-1, Syk, phosphorylated (p)-Syk, tumor necrosis factor-α (TNF-α), and inducible nitric oxide synthase (iNOS) expression was analyzed via western blotting in ischemic brain tissue after ischemic stroke and in BV2 microglial cells subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) injury in vitro. The brain infarct volume and Iba1-positive cells were evaluated using Nissl’s and immunofluorescence staining, respectively. The Dectin-1 antagonist laminarin (LAM) and a selective inhibitor of Syk phosphorylation (piceatannol; PIC) were used for the intervention.

Results

Dectin-1, Syk, and p-Syk expression was significantly enhanced on days 3, 5, and 7 and peaked on day 3 after ischemic stroke. The Dectin-1 antagonist LAM or Syk inhibitor PIC decreased the number of Iba1-positive cells and TNF-α and iNOS expression, decreased the brain infarct volume, and improved neurological functions on day 3 after ischemic stroke. In addition, the in vitro data revealed that Dectin-1, Syk, and p-Syk expression was increased following the 3-h OGD and 0, 3, and 6 h of reperfusion in BV2 microglial cells. LAM and PIC also decreased TNF-α and iNOS expression 3 h after OGD/R induction.

Conclusion

Dectin-1/Syk signaling plays a crucial role in inflammatory activation after ischemic stroke, and further investigation of Dectin-1/Syk signaling in stroke is warranted.

Efficacy of continuous ingestion of dewaxed brown rice on the cognitive functions of the residents of elderly welfare facilities: A pilot test using crossover trial

Compared with regular brown rice, dewaxed brown rice (DBR), prepared by excluding only the wax layer in the outermost layer of brown rice using a new rice milling technique, has improved water absorbency, digestibility, and taste. Dewaxed brown rice has a nutritional value close to that of brown rice and contains a large amount of lipopolysaccharides (LPS), which are known to improve the cognitive function of mice. In this study, we examined the effect of continuous DBR ingestion on the cognitive function of elderly people. A crossover comparison test was performed, in which elderly people who moved into an elderly welfare facility were divided into two groups and ingested DBR or polished white rice for three meals a day for 6 months, followed by a change in test meals for the next 6 months. Cognitive function was assessed using Revised Hasegawa's Dementia Scale (HDS-R) before starting the test and 6 months after ingesting each test meal. No subjects withdrew or discontinued DBR intake during the study period, and all subjects continued the test for 6 months. In subjects with low cognitive function (defined as subjects with HDS-R total score of ≥1 but <10 at the start of the study), there was a significant association between continuous DBR ingestion and cognitive function improvement (increase in total HDS-R score). Our findings suggest that the long-term DBR ingestion as a staple food could be useful for preventing cognitive decline in elderly; it offers an easily implemented option as a daily diet for preventing cognitive decline.

Pathophysiological Mechanisms and Potential Therapeutic Targets in Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a subtype of hemorrhagic stroke with high mortality and morbidity. The resulting hematoma within brain parenchyma induces a series of adverse events causing primary and secondary brain injury. The mechanism of injury after ICH is very complicated and has not yet been illuminated. This review discusses some key pathophysiology mechanisms in ICH such as oxidative stress (OS), inflammation, iron toxicity, and thrombin formation. The corresponding therapeutic targets and therapeutic strategies are also reviewed.

Huoluo Yinao decoction mitigates cognitive impairments after chronic cerebral hypoperfusion in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Huoluo Yinao decoction (HLYND) has been used to ameliorate cognitive impairment induced by chronic cerebral hypoperfusion in clinical for years. However, the exact mechanisms remain unknown.

AIM OF THE STUDY

To investigate the effects and mechanisms underlying HLYND-mediated improvement in cognitive deficits associated with chronic cerebral hypoperfusion.

MATERIALS AND METHODS

Thirty-six Sprague-Dawley rats were randomly allocated to three groups: sham, model, and HLYND. Daily administration of HLYND or volume-matched vehicle by gavage was initiated 1 day after bilateral carotid artery stenosis (BCAS) and continued for 42 days. The Morris water maze (MWM) test was used to assess cognitive functions from days 36-42. Via western blot and immunofluorescent staining, restoration of neuronal plasticity and remyelination of white matter were evaluated by analyzing the expression profiles of MAP-2, synaptophysin and MBP. In addition, macrophage/microglial activation was assessed by quantifying changes in Iba1, and macrophage/microglial polarization was assessed by changes in iNOS and CD16 (M1 markers), as well as Arg1 and CD206 (M2 markers).

RESULTS

In the MWM test, BCAS rats showed significantly extended escape latency and reduced platform crossing times, while those in the HLYND group had shortened escape latency and increased frequency of platform crossing. In addition, rats in the model group showed decreased levels and abnormal morphological changes of MAP-2, synaptophysin and MBP, whereas HLYND administration reversed these effects. As expected, Iba1 levels were elevated in both the model and HLYND groups but rats in the model group showed increased levels of the M1 markers, iNOS and CD16, and a correspondent decrease in the M2 marker, Arg1. In contrast, in the HLYND group, iNOS and CD16 levels were suppressed, while Arg1 levels were elevated.

CONCLUSIONS

Our findings demonstrate that HLYND mitigates cognitive impairment after chronic cerebral hypoperfusion in rats through mechanisms involving increased neuronal plasticity and white matter remyelination, with a subtile modulation of macrophage/microglial polarization toward the M2 phenotype.

Polysaccharide of Schisandra Chinensis Fructus ameliorates cognitive decline in a mouse model of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Polysaccharides is an important ingredient of Schisandra Chinensis Fructus which often appears in ancient prescriptions for forgetfulness or dementia.

AIM OF THE STUDY

The purpose of our study is to investigate the effects of polysaccharides of Schisandra Chinensis Fructus (SCP) on animal model of Alzheimer's disease (AD), which is a common disease of dementia, to elucidate the traditional medical theories with modern pharmacological methods and provide a reference for further clarifying its active mechanisms.

MATERIALS AND METHODS

Hydrolysates of SCP were analyzed by HPLC. Y-maze, Morris water maze (MWM) were used for evaluating cognition processes of mice. Immunohistochemistry (IHC) was used to detect the deposition of Aβ. The levels of cytokine expression including Tumor Necrosis Factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in the hippocampus were detected by ELISA kits. Activation of astrocytes and microglia was assessed by immunofluorescence labeling GFAP and Iba-1. The phosphorylated state of various mitogen-activated protein kinase (MAPKs) signaling molecules (p38 MAPK, ERK 1/2, and JNK) and activation of nuclear factor κB (NF-κB) was studied by western blot. Histopathological changes were observed by H.E. straining.

RESULTS

SCP could significantly improve the cognition and histopathological changes of AD mice, reduce the deposition of Aβ, downregulate the expression of pro-inflammatory cytokines and the activation of glial cells in the hippocampus. Further, SCP decreased nuclear displacement of NF-κB and MAPKs phosphorylation.

CONCLUSIONS

SCP could improve the cognition of mice, and it may play an anti-AD role by activating the NF-κB/MAPK pathway to alleviate neuroinflammation.

Long-term exposure to fluoride as a factor promoting changes in the expression and activity of cyclooxygenases (COX1 and COX2) in various rat brain structures

BACKGROUND

Sixty percent of the mammalian brain is composed of lipids including arachidonic acid (AA). AA released from cell membranes is metabolised in the cyclooxygenase (COX) pathway to prostanoids - biologically active substances involved in the regulation of many processes including inflammation. It has been shown that long-term exposure to fluoride in pre and neonatal period is dangerous because this element is able to penetrate through the placenta and to cross the blood-brain barrier. Exposure to fluoride during the development affects metabolism and physiology of neurons and glia which results in the impairment of cognitive functions but the exact mechanisms of fluoride neurotoxicity are not clearly defined.

OBJECTIVE

The aim of this study was to determine whether exposure to fluoride during the development affects COXes activity and the synthesis of prostanoids.

MATERIAL AND METHODS

Pre- and postnatal toxicity model in Wistar rats was used. Experimental animals received 50 mg/L of NaF in drinking water ad libitum, while control animals received tap water. In cerebral cortex, hippocampus, cerebellum and striatum were measured fluoride concentration, COX1 and COX2 genes expression, immunolocalization of the enzymatic proteins and concentration of PGE2 and TXB2.

RESULTS

of this study showed statistically significant changes in the concentration of fluoride in brain structures between study group and control animals. Moreover, significant changes in the expression level of COX1 and COX2, and in the concentration of PGE2 and TXB2 were observed.

CONCLUSION

Exposure to fluoride in the prenatal and neonatal period result in the increase in COX2 activity and increase in PGE2 concentration in rats brain, which may lead to disturbances in central nervous system homeostasis.‬‬.

Dl-3-n-Butylphthalide Exerts Dopaminergic Neuroprotection Through Inhibition of Neuroinflammation

Microglia-mediated neuroinflammation contributes to multiple neurodegenerative disorders, including PD. Therefore, the regulation of microglial activation probably has the therapeutic potential. This study is aimed to determine whether NBP could suppress microglial activation and protect dopaminergic neurons from excessive neuroinflammation. In the present study, MPTP-induced PD model was established to explore the neuroprotective and anti-inflammatory effect of NBP. We assessed motor deficits, dopaminergic neurodegeneration and microglial activation in PD mice. In vitro, the anti-inflammatory activity of NBP was confirmed by cell viability assay of SH-SY5Y cells after being treated with conditioned medium from LPS-stimulated BV-2 cells and from 1-Methyl-4-phenylpyridinium iodide (MPP⁺)-stimulated BV-2 cells. The expression of pro-inflammatory molecules was determined by RT-PCR, Western Blot and ELISA assay. The generation of NO and ROS were also assessed. The involvement of signaling pathways such as MAPK, NF-κB, and PI3k/Akt were further investigated by Western Blot and immunofluorescence assay. The neuroprotective effect of NBP was demonstrated in vivo as shown by the improvement of dopaminergic neurodegeneration, motor deficits and microglial activation in MPTP-induced mouse model of PD. The expression of pro-inflammatory mediators was also reduced by NBP administration. In vitro, NBP also protected dopaminergic neurons from neurotoxicity induced by activated microglia. NBP pretreatment not only reduced pro-inflammatory molecules, but also suppressed NO release and ROS generation in BV-2 cells. Further mechanism research suggested that the inactivation of MAPK, NF-κB and PI3K/Akt may involve in anti-neuroinflammation role of NBP. In conclusion, our results revealed that NBP exerted dopaminergic neuroprotection through inhibition of microglia-mediated neuroinflammation, suggesting the promising therapeutic effect of NBP for PD.

Tanshinone IIA inhibits lipopolysaccharide‑induced inflammatory responses through the TLR4/TAK1/NF‑κB signaling pathway in vascular smooth muscle cells

To aim of the present study was to determine whether Tanshinone IIA (Tan IIA) inhibits lipopolysaccharide (LPS)‑induced inflammation in vascular smooth muscle cells (VSMCs) from rats and elucidate the underlying molecular mechanism. VSMCs were primarily cultured and then treated with LPS (1 µg/l) and Tan IIA (25, 50 and 100 µmol/l) for 24 h. Monocyte chemoattractant protein (MCP)‑1, interleukin (IL)‑6 and tumor necrosis factor (TNF)‑α levels were detected by ELISA and reverse transcription‑quantitative polymerase chain reaction. Nitric oxide (NO) production was measured using the Griess reaction. The expression of Toll‑like receptor 4 (TLR4), nuclear factor (NF)‑κB (p65), and inducible NO synthase (iNOS), and the phosphorylation of transforming growth factor‑β‑activated kinase 1 (TAK1) were detected by western blot analysis. Tan IIA inhibited the LPS‑induced expression of MCP‑1, IL‑6, and TNF‑α in a concentration‑dependent manner and inhibited iNOS‑mediated NO production. In addition, Tan IIA suppressed the expression of TLR4, the phosphorylation of TAK1, and the nuclear translocation of NF‑κB (p65). The anti‑TLR4 antibody and TAK1 inhibitor 5Z‑7‑oxozeaenol partially attenuated the LPS‑induced expression of proinflammatory cytokines. In conclusion, Tan IIA inhibits LPS‑induced inflammatory responses in VSMCs in vitro through the partial suppression of the TLR4/TAK1/NF‑κB signaling pathway.

Targeting MAPK Pathways by Naringenin Modulates Microglia M1/M2 Polarization in Lipopolysaccharide-Stimulated Cultures

Neuroinflammation is considered to be an important and inevitable pathological process associated with all types of damages to, and disorders of, the central nervous system. The hallmark of neuroinflammation is the microglia activation. In response to different micro-environmental disturbances, microglia could polarize into either an M1 pro-inflammatory phenotype, exacerbating neurotoxicity, or an M2 anti-inflammatory phenotype, exerting neuroprotection. Therefore, shifting the polarization of microglia toward the M2 phenotype could possess a more viable strategy for the neuroinflammatory disorders treatment. Naringenin (NAR) is naturally a grapefruit flavonoid and possesses various kinds of pharmacological activities, such as anti-inflammatory and neuroprotective activities. In the present study, we aimed to investigate the potential effects of NAR on microglial M1/M2 polarization and further reveal the underlying mechanisms of actions. First, NAR inhibited lipopolysaccharide (LPS)-induced microglial activation. Then, NAR shifted the M1 pro-inflammatory microglia phenotype to the M2 anti-inflammatory M2 microglia state as demonstrated by the decreased expression of M1 markers (i.e., inducible TNF-α and IL-1β) and the elevated expression of M2 markers (i.e., arginase 1, IL-4, and IL-10). In addition, the effects of NAR on microglial polarization were dependent on MAPK signaling, particularly JNK inactivation, as evidenced by the fact that the selective activator of JNK abolished NAR-promoted M2 polarization and further NAR-inhibited microglial activation. Together, this study demonstrated that NAR promoted microglia M1/M2 polarization, thus conferring anti-neuroinflammatory effects via the inhibition of MAPK signaling activation. These findings might provide new alternative avenues for neuroinflammation-related disorders treatment.

Anti-neuroinflammatory effects of GPR55 antagonists in LPS-activated primary microglial cells

BACKGROUND

Neuroinflammation plays a vital role in Alzheimer's disease and other neurodegenerative conditions. Microglia are the resident mononuclear immune cells of the central nervous system, and they play essential roles in the maintenance of homeostasis and responses to neuroinflammation. The orphan G-protein-coupled receptor 55 (GPR55) has been reported to modulate inflammation and is expressed in immune cells such as monocytes and microglia. However, its effects on neuroinflammation, mainly on the production of members of the arachidonic acid pathway in activated microglia, have not been elucidated in detail.

METHODS

In this present study, a series of coumarin derivatives, that exhibit GPR55 antagonism properties, were designed. The effects of these compounds on members of the arachidonic acid cascade were studied in lipopolysaccharide (LPS)-treated primary rat microglia using Western blot, qPCR, and ELISA.

RESULTS

We demonstrate here that the various compounds with GPR55 antagonistic activities significantly inhibited the release of PGE₂ in primary microglia. The inhibition of LPS-induced PGE₂ release by the most potent candidate KIT 17 was partially dependent on reduced protein synthesis of mPGES-1 and COX-2. KIT 17 did not affect any key enzyme involved on the endocannabinoid system. We furthermore show that microglia expressed GPR55 and that a synthetic antagonist of the GPR receptor (ML193) demonstrated the same effect of the KIT 17 on the inhibition of PGE₂.

CONCLUSIONS

Our results suggest that KIT 17 is acting as an inverse agonist on GPR55 independent of the endocannabinoid system. Targeting GPR55 might be a new therapeutic option to treat neurodegenerative diseases with a neuroinflammatory background such as Alzheimer's disease, Parkinson, and multiple sclerosis (MS).

Regulation of mPGES-1 composition and cell growth via the MAPK signaling pathway in jurkat cells

Previous studies have suggested that microsomal prostaglandin E synthase-1 (mPGES-1) is highly expressed and closely associated with mitogen-activated protein kinase (MAPK) signaling pathways in various types of malignant cells. However, their expression patterns and function with respect to T-cell acute lymphoblastic leukemia (T-ALL) remain largely unknown. The present study investigated whether mPGES-1 served a crucial role in T-ALL and aimed to identify interactions between mPGES-1 and the MAPK signaling pathway in T-ALL. The results indicated that mPGES-1 overexpression in T-ALL jurkat cells was significantly decreased by RNA silencing. Decreasing mPGES-1 on a consistent basis may inhibit cell proliferation, induce apoptosis and arrest the cell cycle in T-ALL jurkat cells. Microarray and western blot analyses revealed that c-Jun N-terminal kinase served a role in the mPGES-1/prostaglandin E2/EP4/MAPK positive feedback loops. In addition, P38 and extracellular signal-regulated kinase 1/2 exhibited negative feedback effects on mPGES-1. In conclusion, the results suggested that cross-talk between mPGES-1 and the MAPK signaling pathway was very complex. Therefore, the combined regulation of mPGES-1 and the MAPK signaling pathway may be developed into a new candidate therapy for T-ALL in the future.

Essential Dietary Bioactive Lipids in Neuroinflammatory Diseases

SIGNIFICANCE

Under physiological conditions, neurons and glia are in a healthy, redox-balanced environment; when injury perturbs this equilibrium, a neuroinflammatory state is established by activated microglia that triggers pro-inflammatory responses and alters the oxidant/antioxidant balance, thus leading to neuronal loss and neurodegeneration. In neurodegenerative diseases (such as Alzheimer's disease, Parkinson's disease, amyothrophic lateral sclerosis, and multiple sclerosis), the brain is in a constitutively self-sustaining cycle of inflammation and oxidative stress that prompts and amplifies brain damage. Recent Advances: Recently, an increasing amount of scientific data highlight the ability of specific nutrients to cross the blood-brain barrier, and to modulate inflammatory and oxidative pathways. Therefore, nutritional approaches may contribute to restore the lost equilibrium among factors accounting for neurodegeneration.

CRITICAL ISSUES

Herein, we critically examine how essential lipids (including fatty acids, liposoluble vitamins and phytosterols) might contribute to accelerate or prevent the onset and progression of such pathologies. In particular, we highlight that experimental and clinical findings, although promising, are still inadequate to draw definitive conclusions.

FUTURE DIRECTIONS

More research is warranted in order to establish the real impact of lipid intake on brain health, especially when redox balance and inflammatory responses have been already compromised. In the future, it would be hoped to gain a detailed knowledge of chemical modifications and dynamic properties of such nutrients, before planning to exploit them as potential therapeutics. Antioxid. Redox Signal. 29, 37-60.

Dual modulation on glial cells by tetrahydroxystilbene glucoside protects against dopamine neuronal loss

Background

Microglia-mediated neuroinflammation is recognized to mainly contribute to the pathogenesis of Parkinson’s disease (PD). Tetrahydroxystilbene glucoside (TSG) has been proved to be beneficial for health with a great number of pharmacological properties. We examined the effects of TSG against dopamine (DA) neuronal loss towards development of a PD treatment strategy.

Methods

Substantia nigral stereotaxic single injection of lipopolysaccharide (LPS)-induced rat DA neuronal damage was employed to investigate TSG-produced neuroprotection. In addition, primary rat midbrain neuron-glia co-cultures were performed to explore the underlying mechanisms.

Results

Daily intraperitoneal injection of TSG for seven consecutive days significantly attenuated LPS-induced loss of DA neurons in the substantia nigra. In addition, glia-dependent mechanisms were responsible for TSG-mediated neuroprotection. First, TSG ameliorated microglia-mediated neuroinflammation and the subsequent production of various pro-inflammatory and neurotoxic factors. Second, astroglial neurotrophic factor neutralization weakened TSG-mediated neuroprotection, showing that TSG was protective in part via increasing astroglia-derived neurotrophic factor secretion.

Conclusions

TSG protects DA neurons against LPS-induced neurotoxicity through dual modulation on glial cells by attenuating microglia-mediated neuroinflammation and enhancing astroglia-derived neurotrophic effects. These findings might open new alternative avenues for PD treatment.

Inflammatory and cytotoxic effects of bifenthrin in primary microglia and organotypic hippocampal slice cultures

BACKGROUND

Pyrethroids, such as bifenthrin (BF), are among the most widely used class of insecticides that pose serious risks to human and wildlife health. Pyrethroids are proposed to affect astrocytic functions and to cause neuron injury in the central nervous system (CNS). Microglia are key cells involved in innate immune responses in the CNS, and microglia activation has been linked to inflammation and neurotoxicity. However, little information is known about the effects of BF-induced toxicity in primary microglial cells as well as in organotypic hippocampal slice cultures (OHSCs).

METHODS

Oxidative stress and inflammatory responses induced by BF were evaluated in primary microglial cells and OHSCs incubated with different concentrations of BF (1-20 μM) for 4 and 24 h. mRNA and protein synthesis of cyclooxygenase-2 (COX-2), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), nuclear erythroid-2 like factor-2 (Nrf-2), and microsomal prostaglandin synthase-1 (mPGES-1) was also studied by qPCR and Western blot. Cell viability was analyzed by MTT-tetrazolio (MTT) and lactate dehydrogenase (LDH) assays. Neurotoxicity in OHSCs was analyzed by propidium iodide (PI) staining and confocal microscopy.

RESULTS

Exposure of microglial cells to BF for 24 h resulted in a dose-dependent reduction in the number of viable cells. At sub-cytotoxic concentrations, BF increased reactive oxygen species (ROS), TNF-alpha synthesis, and prostaglandin E2 (PGE2) production, at both 4- and 24-h time points, respectively. Furthermore, BF incubation decreased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities and increased lipid peroxidation, protein oxidation, and H2O2 formation. In addition, BF significantly induced protein synthesis and mRNA expression of oxidative and inflammatory mediators after 4 and 24 h, including Nrf-2, COX-2, mPGES-1, and nuclear factor kappaB (NF-kappaB). A 24-h exposure of OHSCs to BF also increased neuronal death compared to untreated controls. Furthermore, depletion of microglia from OHSCs potently enhanced neuronal death induced by BF.

CONCLUSIONS

Overall, BF exhibited cytotoxic effects in primary microglial cells, accompanied by the induction of various inflammatory and oxidative stress markers including the Nrf-2/COX-2/mPGES-1/NF-kappaB pathways. Moreover, the study provided evidence that BF induced neuronal death in OHSCs and suggests that microglia exert a protective function against BF toxicity.

Anti-neuroinflammatory effects of Ginkgo biloba extract EGb761 in LPS-activated primary microglial cells

BACKGROUND

Neuroinflammation is a key factor of Alzheimer's disease (AD) and other neurodegenerative conditions. Microglia are the resident mononuclear immune cells of the central nervous system (CNS). They play an essential role in the maintenance of homeostasis and responses to neuroinflammation. Ginkgo biloba extract EGb 761 is one of the most commonly used natural medicines owing to its established efficacy and remarkable biological activities especially in respect to CNS diseases. However, only few studies have addressed the effects and mechanisms of Ginkgo biloba extract in microglia activation.

METHODS

We measured the production of pro-inflammatory mediators and cytokines by ELISA and analyzed gene expressions by qRT-PCR and Western Blot in LPS treated cultured primary rat microglia.

RESULTS

The Ginkgo biloba extract EGb 761 significantly inhibited the release of prostaglandin E₂ (PGE₂) and differentially regulated the levels of pro-inflammatory cytokines. The inhibition of LPS-induced PGE₂ release in primary microglia was partially dependent on reduced protein synthesis of mPGES-1 and the reduction in the activation of cytosolic phospholipase A2 (cPLA2) without altering COX-2 enzymatic activity, inhibitor of kappa B alpha (IkappaBalpha) degradation, and the activation of multiple mitogen activated protein kinases (MAPKs). Altogether, we showed that EGb 761 reduces neuro-inflammatory activation in primary microglial cells by targeting PGE₂ release and cytokines.

CONCLUSION

Ginkgo biloba extract EGb 761 displayed anti-neuroinflammatory activity in LPS-activated primary microglia cells. EGb 761 was able to reduce neuroinflammatory activation by targeting the COX/PGE₂ pathway. This effect might contribute to the established clinical cognitive efficacy in Alzheimer's disease, vascular and mixed dementia.

Reactive oxygen species induce injury of the intestinal epithelium during hyperoxia

Long-term therapeutic hyperoxia may exert serious toxic effects on intestinal epithelial cells in vitro and in vivo. The aim of the present study was to investigate the cause of this intestinal injury under conditions of hyperoxia. Caco-2 cells were treated with different concentrations of hydrogen peroxide (H2O2) and 85% hyperoxia for 24 h. higher rates of injury of Caco-2 cells were observed in the hyperoxia and H2O2 groups compared with the control group. The reactive oxygen species (ROS) level of the hyperoxia group was significantly higher compared with that of the 400 µM H2O2 group. The protein and gene levels of RelA, RelB, hypoxia‑inducible factor-1α, tumor necrosis factor-α and apoptosis signal‑regulating kinase 1 were significantly higher in the hyperoxia and H2O2 groups compared with those in the control group. In conclusion, during hyperoxia, intestinal epithelial cells were destroyed and the levels of ROS were increased. Therefore, ROS may play an important role in intestinal injury in a hyperoxic environment.

TLR4 interaction with LPS in glioma CD133+ cancer stem cells induces cell proliferation, resistance to chemotherapy and evasion from cytotoxic T lymphocyte-induced cytolysis

Despite advances in treatment modalities, 5-year survival among glioma patients remains poor. Glioma cancer stem cells (CSCs) exhibit high tumorigenic activity and are associated with resistance to treatment and tumor recurrence. Because overexpression of toll-like receptor 4 (TLR4) correlated with cancer development, we investigated LPS-induced TLR4 signaling in glioma CD133-positive (CD133+) CSCs. The proliferation of CD133+ CSCs isolated from CSCs derived from the U251 and SF295 glioma cell lines and from human glioma samples was upregulated on a time- and concentration-dependent basis by LPS stimulation, with increases in CD133, NANOG, and NESTIN mRNA and protein levels. Also elevated was cytokine expression, which was coupled to phosphorylation of mitogen-activated protein kinase, and activation of cyclins and cyclin-dependent kinase complexes. TLR4 knockdown reduced LPS-induced CD133+ CSC proliferation, whereas Adriamycin-induced CD133+ CSC apoptosis was moderately inhibited by treatment with LPS, implying a protective effect of LPS. The capacity of glioma CD133+ CSC-reactive cytotoxic T lymphocyte to selectively kill CD133+ CSCs was reduced by LPS, and this effect was not apparent after TLR4 knockdown in CD133+ CSCs. These data suggest TLR4 signaling is a factor in CD133+ CSC immune evasion, and thus disruption of TLR4 signaling is a potential therapeutic strategy in glioma.

Microglia: Housekeeper of the Central Nervous System

Microglia, of myeloid origin, play fundamental roles in the control of immune responses and the maintenance of central nervous system homeostasis. These cells, just like peripheral macrophages, may be activated into M1 pro-inflammatory or M2 anti-inflammatory phenotypes by appropriate stimuli. Microglia do not respond in isolation, but form part of complex networks of cells influencing each other. This review addresses the complex interaction of microglia with each cell type in the brain: neurons, astrocytes, cerebrovascular endothelial cells, and oligodendrocytes. We also highlight the participation of microglia in the maintenance of homeostasis in the brain, and their roles in the development and progression of age-related neurodegenerative disorders.