Evaluation of phytosomal curcumin as an anti-inflammatory agent for chronic glial activation in the GFAP-IL6 mouse model

Chronic glial activation is characterized by an increased number of activated microglia and astroglia; these secrete free radicals and cytotoxic cytokines, subsequently causing neuronal damage. This study investigated the hypothesis that a soy-lecithin based phytosomal curcumin formulation can decrease glial activation in the brains of GFAP-IL6 mice, a model of chronic glial activation, which exhibits gliosis in various regions of the brain. Three doses of Meriva curcumin (MC) (874, 436, and 218 PPM) were fed to 3-month-old GFAP-IL6 and wild-type (WT) mice for 4 weeks. As markers of glial activation, the total numbers of Iba-1+ and TSPO+ microglia and macrophages, and GFAP+ astrocytes, were determined in the cerebellum and hippocampus by immunohistochemistry and unbiased stereology. Furthermore, the morphology of the glial cells was assessed by confocal microscopy and Sholl analysis. Administration of phytosomal curcumin led to a dose-dependent reduction in neuroinflammatory markers. Phytosomal curcumin (874 PPM) decreased the number of microglia by 26.2% in the hippocampus and by 48% in the cerebellum of the GFAP-IL6 mice compared with the GFAP-IL6 mice on normal food. Additionally, GFAP+ astrocyte numbers in the hippocampus of the GFAP-IL6 mice were decreased by 42%. The GFAP-IL6 mice exhibited a different microglial morphology to the WT mice, showing an increased soma size and perimeter. This difference was significantly reduced by the 874 PPM phytosomal curcumin dose. Our findings demonstrate that phytosomal curcumin is able to attenuate the inflammatory pathology, and potentially reverse the detrimental effects of chronic glial activation

Chronic Microglial Activation in the GFAP-IL6 Mouse Contributes to Age-Dependent Cerebellar Volume Loss and Impairment in Motor Function

Chronic microglial activation is a prominent feature of many chronic neurodegenerative diseases, including Parkinson’s and Alzheimer’s disease. To investigate the effects of chronic microglial activation on cerebellar structure and motor function throughout the lifespan, the transgenic GFAP-IL6 mouse model was used. The aim of the study was to examine inflammatory markers and neuronal degeneration while simultaneously characterizing the motor performance of GFAP-IL6 mice at 3, 6, 14, and 24 months of age in comparison to WT (C57BL/6) mice. In respect to markers of neuroinflammation in the cerebellum, increased numbers of Iba1+ microglia were observed as early as at 3 months of age. In addition, TNF-α levels proved to be significantly higher in the GFAP-IL6 compared to WT mice at all time points. A difference in cerebellar volume between the GFAP-IL6 and WT mice was observed later in life, starting at 6 months and increasing to a loss of about 50% in aged (24 months old) GFAP-IL6 mice. Synaptic deficits were also assessed by using pre- (synaptophysin) and post-synaptic (PSD95) markers. While synaptophysin levels remained unchanged, PSD95 levels decreased in the aging GFAP-IL6 mice compared to their WT littermates from 14 months onward. To assess the effect of microglia activation and neurodegeneration on behavior, a variety of motor function tests, semi-quantitative cerebellar ataxia score, accelerod, beam walking, and open field tests were performed. An age-dependent difference between the genotypes was observed in many of the motor function tests. For example, reduced performance on the accelerod and higher ataxia scores were observed at 6 months of age, followed by the beam walking test showing differences at 14 months of age. In summary, this study constitutes a comprehensive, age-dependent examination of inflammatory, synaptic and neurodegenerative changes in the brains of GFAP-IL6 mice leading to a deterioration in motor performance. The results also indicate that early chronic microglia activation in the GFAP-IL6 mouse leads to observable cerebellar volume loss and motor deficits later in life

Effects of a solid lipid curcumin particle formulation on chronic activation of microglia and astroglia in the GFAP-IL6 mouse model

Chronic glial activation is characterized by increased numbers of activated glial cells, secreting free radicals and cytotoxic cytokines, subsequently causing neuronal damage. In order to investigate the anti-inflammatory activity of Longvida® Optimised Curcumin (LC), we fed 500 ppm of LC to 2-month-old wild type and GFAP-IL6 mice for 6 months. LC feeding led to a significant reduction in the number of Iba-1+ microglia by 26% in the hippocampus and by 48% in the cerebellum, GFAP+ astrocytes by 30%, and TSPO+ cells by 24% in the hippocampus and by 31% in the cerebellum of the GFAP-IL6 mice. The morphology of the cells was assessed and LC significantly decreased the dendritic length of microglia and the convex area, convex perimeter, dendritic length, nodes and number of processes of astrocytes in the hippocampus while decreasing the soma area and perimeter in the cerebellum, in LC-fed GFAP-IL6 mice. In addition, LC feeding increased pre- and postsynaptic protein levels and improved balance measured by Rotarod. Together, these data suggest that LC is able to attenuate the inflammatory pathology and ameliorate neurodegeneration and motor deficits in GFAP-IL6 mice. For patients with neuro-inflammatory disorders, LC might potentially reverse the detrimental effects of chronic glial activation

Therapeutic Opportunities for Food Supplements in Neurodegenerative Disease and Depression

Emerging evidence is showing nutrition as a crucial factor in the high prevalence and incidence of neurodegenerative mental disorders. Preventive interventions on neuroinflammation seem to be able to interfere with neurodegeneration. Supplementation of essential nutrients, such as long-chain-polyunsaturated fatty acids, vitamin E and mineral elements, may minimize inflammation, enhancing antioxidative defense, and lowering the risk and incidence of age-related diseases, such as cardiovascular diseases and neurodegenerative diseases. This manuscript reviews the current evidence on the role of neuroinflammation in the pathophysiology of neurodegenerative and mental disorders, and preventive strategies for food supplementation in these neuropsychiatric diseases. Dietary supplementation-based strategies have been demonstrated to be effective in subjects with mild cognitive impairment, while weaker results have been obtained in patients with advance neurodegenerative disease. Adjunctive supplementation has also been demonstrated to improve depression, this being of marked benefit considering the comorbidity between cognitive impairment/dementia and depression. Further research is needed to improve the prescriptive precision of supplementation in patients, and to better understand potential interactions with clinical and pharmacokinetic factors

Suppression of the peripheral immune system limits the central immune response following cuprizone-feeding : relevance to modelling Multiple Sclerosis

Cuprizone (CPZ) preferentially affects oligodendrocytes (OLG), resulting in demyelination. To investigate whether central oligodendrocytosis and gliosis triggered an adaptive immune response, the impact of combining a standard (0.2%) or low (0.1%) dose of ingested CPZ with disruption of the blood brain barrier (BBB), using pertussis toxin (PT), was assessed in mice. 0.2% CPZ(±PT) for 5 weeks produced oligodendrocytosis, demyelination and gliosis plus marked splenic atrophy (37%) and reduced levels of CD4 (44%) and CD8 (61%). Conversely, 0.1% CPZ(±PT) produced a similar oligodendrocytosis, demyelination and gliosis but a smaller reduction in splenic CD4 (11%) and CD8 (14%) levels and no splenic atrophy. Long-term feeding of 0.1% CPZ(±PT) for 12 weeks produced similar reductions in CD4 (27%) and CD8 (43%), as well as splenic atrophy (33%), as seen with 0.2% CPZ(±PT) for 5 weeks. Collectively, these results suggest that 0.1% CPZ for 5 weeks may be a more promising model to study the ‘insideout’ theory of Multiple Sclerosis (MS). However, neither CD4 nor CD8 were detected in the brain in CPZ±PT groups, indicating that CPZ-mediated suppression of peripheral immune organs is a major impediment to studying the ‘inside-out’ role of the adaptive immune system in this model over long time periods. Notably, CPZ(±PT)-feeding induced changes in the brain proteome related to the suppression of immune function, cellular metabolism, synaptic function and cellular structure/organization, indicating that demyelinating conditions, such as MS, can be initiated in the absence of adaptive immune system involvement

The effects of a highly bioavailable curcumin PhytosomeTM preparation on the retinal architecture and glial reactivity in the GFAP-IL6 mice

Uncontrolled, chronic inflammation in the retina can disturb retinal structure and function leading to impaired visual function. For the first time, in a mouse model of chronic neuroinflammation (GFAP-IL6), we investigated the impact of chronic glial activation on the retinal microglia population and structure. In addition, we tested a curcumin PhytosomeTM preparation with enhanced bioavailability to investigate the effects of a cytokine-suppressing anti-inflammatory drug on retinal architecture. Curcumin PhytosomeTM was fed to 3-month old GFAP-IL6 mice for 4 weeks and compared to their untreated GFAP-IL6 counterparts as well as wild type mice on control diet. Microglial numbers and morphology together with neuronal numbers were characterized using immunohistochemistry and cell reconstruction in the retina, using retinal wholemount and slices. GFAP-IL6 mice showed a significant increase in Iba1-labelled mononuclear phagocytes, including microglia, and displayed altered glial morphology. This resulted in a reduction in cone density and a thinning of the retinal layers compared to wild type mice. Curcumin PhytosomeTM treatment contributed to decreased microglial density, significantly decreasing both soma and cell size compared to control diet, as well as preventing the thinning of the retinal layers. This study is the first to characterize the impact of chronic retinal inflammation in the GFAP-IL6 mouse and the therapeutic benefit of enhanced bioavailable curcumin PhytosomeTM to significantly reduce microglia density and prevent neuronal loss. These data suggest that curcumin could be used as a complementary therapy alongside traditional treatments to reduce associated retinal inflammation in a variety of retinal diseases

Chronic interleukin-6 mediated neuroinflammation decreases anxiety, and impaires spatial memory in aged female mice

IntroductionNeuroinflammation is a common feature of many psychiatric disorders as well as a common underlying mechanism of neurodegenerative diseases. Sex has been shown to strongly influence the development as well as the clinical expression of these pathologies. However, there is still a neglect regarding the consideration of sex effects in rodent experiments, and a substantial underrepresentation of females in studies. This work set out to expand our knowledge of neuroinflammatory mechanisms in female mice, at both a behavioral and molecular level.MethodsThis study used GFAP-IL6 mice, a model of chronic neuroinflammation, in which interleukin-6 (IL6) is overexpressed in the central nervous system under the control of the glial fibrillary acidic protein (GFAP) promoter. We evaluated aged (11-15-month-old) wild type-like (WT) and GFAP-IL6 female mice in behavioral tests assessing anxiety (elevated plus-maze, EPM, Light/dark box), and spatial learning and memory (Y-maze, YM and Barnes Maze, BM) and associative learning (fear conditioning, FC). We also examined gene expression of markers linked to neuroinflammation, neurodegeneration and neurotransmission via RT-qPCR in brain regions involved in motor control, anxiety, learning and memory.ResultsFemale GFAP-IL6 mice exhibited reduced anxiety-like behavior in the EPM, and hypolocomotion in the light-dark test and EPM. Short-term memory impairment was evident in the YM but associative learning in FC was intact in GFAP-IL6 mice, suggesting domain-specific cognitive deficits in female GFAP-IL6 mice. In the BM, all mice showed intact learning and memory, but GFAP-IL6 mice exhibited higher latencies to enter the escape hole than WT mice. We analyzed the search strategy and found differences in the way GFAP-IL6 mice searched for the escape hole compared to WTs. RT-qPCR showed increased mRNA levels for molecules involved in pro-inflammatory pathways in the cerebellum, motor cortex, hippocampus, and amygdala in GFAP-IL6 mice. Of the regions examined, the cerebellum and the hippocampus showed upregulation of neuroinflammatory makers as well as dysregulation of glutamatergic and GABAergic neurotransmission gene expression in GFAP-IL6 mice compared to WTs.ConclusionIn conclusion, we showed that chronic neuroinflammation via IL6 overexpression in aged female mice led to a less anxious-like phenotype, hypolocomotion and impaired intermediate-term spatial learning and memory in the YM

From the bush to the brain : preclinical stages of ethnobotanical anti-inflammatory and neuroprotective drug discovery : an Australian example

The Australian rainforest is a rich source of medicinal plants that have evolved in the face of dramatic environmental challenges over a million years due to its prolonged geographical isolation from other continents. The rainforest consists of an inherent richness of plant secondary metabolites that are the most intense in the rainforest. The search for more potent and more bioavailable compounds from other plant sources is ongoing, and our short review will outline the pathways from the discovery of bioactive plants to the structural identification of active compounds, testing for potency, and then neuroprotection in a triculture system, and finally, the validation in an appropriate neuro-inflammatory mouse model, using some examples from our current research. We will focus on neuroinflammation as a potential treatment target for neurodegenerative diseases including multiple sclerosis (MS), Parkinson’s (PD), and Alzheimer’s disease (AD) for these plant-derived, anti-inflammatory molecules and highlight cytokine suppressive anti-inflammatory drugs (CSAIDs) as a better alternative to conventional nonsteroidal anti-inflammatory drugs (NSAIDs) to treat neuroinflammatory disorders

Spatial memory and microglia activation in a mouse model of chronic neuroinflammation and the anti-inflammatory effects of apigenin

Chronic neuroinflammation characterized by microglia reactivity is one of the main underlying processes in the initiation and progression of neurodegenerative diseases such as Alzheimer’s disease. This project characterized spatial memory during healthy aging and prolonged neuroinflammation in the chronic neuroinflammatory model, glial fibrillary acidic protein-interleukin 6 (GFAP-IL6). We investigated whether chronic treatment with the natural flavonoid, apigenin, could reduce microglia activation in the hippocampus and improve spatial memory. GFAP-IL6 transgenic and wild-type-like mice were fed with apigenin-enriched or control chow from 4 months of age and tested for spatial memory function at 6 and 22 months using the Barnes maze. Brain tissue was collected at 22 months to assess microgliosis and morphology using immunohistochemistry, stereology, and 3D single cell reconstruction. GFAP-IL6 mice showed age-dependent loss of spatial memory recall compared with wild-type-like mice. Chronic apigenin treatment decreased the number of Iba-1+ microglia in the hippocampus of GFAP-IL6 mice and changed microglial morphology. Apigenin did not reverse spatial memory recall impairment in GFAP-IL6 mice at 22 months of age. GFAP-IL6 mice may represent a suitable model for age-related neurodegenerative disease. Chronic apigenin supplementation significantly reduced microglia activation, but this did not correspond with spatial memory improvement in the Barnes Maze