Mice Expressing A53T/A30P Mutant Alpha-Synuclein in Dopamine Neurons Do Not Display Behavioral Deficits.

Alpha-synuclein has been implicated in neurodegenerative diseases such as Parkinson's disease and dementia with Lewy bodies, with A53T and A30P mutations shown to be disease causing. It has been reported that hemizygous transgenic mice with tyrosine hydroxylase promotor-driven expression of A53T/A30P mutant alpha-synuclein in dopamine neurons provide a useful preclinical model of these conditions by virtue of developing behavioral deficits. Here, we report a lack of replication of this finding. Despite detecting robust overexpression of A53T/A30P mutant alpha-synuclein in dopamine neurons, we did not observe decreased tyrosine hydroxylase immunofluorescence or behavioral deficits in these mice. Our results demonstrate that preclinical models of synucleinopathy need careful validation in the field.

Alpha-Synuclein Pre-Formed Fibrils Injected into Prefrontal Cortex Primarily Spread to Cortical and Subcortical Structures.

BACKGROUND: Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are characterized by diffuse spread of alpha-synuclein (α-syn) throughout the brain. Patients with PDD and DLB have a neuropsychological pattern of deficits that include executive dysfunction, such as abnormalities in planning, timing, working memory, and behavioral flexibility. The prefrontal cortex (PFC) plays a major role in normal executive function and often develops α-syn aggregates in DLB and PDD. OBJECTIVE: To investigate the long-term behavioral and cognitive consequences of α-syn pathology in the cortex and characterize pathological spread of α-syn. METHODS: We injected human α-syn pre-formed fibrils into the PFC of wild-type male mice. We then assessed the behavioral and cognitive effects between 12- and 21-months post-injection and characterized the spread of pathological α-syn in cortical, subcortical, and brainstem regions. RESULTS: We report that PFC PFFs: 1) induced α-syn aggregation in multiple cortical and subcortical regions with sparse aggregation in midbrain and brainstem nuclei; 2) did not affect interval timing or spatial learning acquisition but did mildly alter behavioral flexibility as measured by intraday reversal learning; and 3) increased open field exploration. CONCLUSIONS: This model of cortical-dominant pathology aids in our understanding of how local α-syn aggregation might impact some symptoms in PDD and DLB.

Parkinson's Disease Dementia Patients: Expression of Glia Maturation Factor in the Brain.

Parkinson's disease (PD) is the second most common progressive neurodegenerative disease characterized by the presence of dopaminergic neuronal loss and motor disorders. PD dementia (PDD) is a cognitive disorder that affects many PD patients. We have previously demonstrated the proinflammatory role of the glia maturation factor (GMF) in neuroinflammation and neurodegeneration in AD, PD, traumatic brain injury (TBI), and experimental autoimmune encephalomyelitis (EAE) in human brains and animal models. The purpose of this study was to investigate the expression of the GMF in the human PDD brain. We analyzed the expression pattern of the GMF protein in conjunction with amyloid plaques (APs) and neurofibrillary tangles (NFTs) in the substantia nigra (SN) and striatum of PDD brains using immunostaining. We detected a large number of GMF-positive glial fibrillary acidic protein (GFAP) reactive astrocytes, especially abundant in areas with degenerating dopaminergic neurons within the SN and striatum in PDD. Additionally, we observed excess levels of GMF in glial cells in the vicinity of APs, and NFTs in the SN and striatum of PDD and non-PDD patients. We found that the majority of GMF-positive immunoreactive glial cells were co-localized with GFAP-reactive astrocytes. Our findings suggest that the GMF may be involved in the pathogenesis of PDD.

Alpha-synuclein pre-formed fibrils injected into prefrontal cortex primarily spread to cortical and subcortical structures and lead to isolated behavioral symptoms.

Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are characterized by diffuse spread of alpha-synuclein (α-syn) throughout the brain. Patients with PDD and DLB have a neuropsychological pattern of deficits that include executive dysfunction, such as abnormalities in planning, timing, working memory, and behavioral flexibility. The prefrontal cortex (PFC) plays a major role in normal executive function and often develops α-syn aggregates in DLB and PDD. To investigate the consequences of α-syn pathology in the cortex, we injected human α-syn pre-formed fibrils into the PFC of wildtype mice. We report that PFC PFFs: 1) induced α-syn aggregation in multiple cortical and subcortical regions with sparse aggregation in midbrain and brainstem nuclei; 2) did not affect interval timing or spatial learning acquisition but did mildly alter behavioral flexibility as measured by intraday reversal learning; 3) increased open field exploration; and 4) did not affect susceptibility to an inflammatory challenge. This model of cortical-dominant pathology aids in our understanding of how local α-syn aggregation might impact some symptoms in PDD and DLB.

Immune Suppression of Glia Maturation Factor Reverses Behavioral Impairment, Attenuates Amyloid Plaque Pathology and Neuroinflammation in an Alzheimer's Disease Mouse Model.

Alzheimer's disease (AD) is an irreversible progressive neurodegenerative disorder recognized by accumulation of amyloid-plaques (APs) and neurofibrillary tangles (NFTs) and eventually loss of memory. Glia maturation factor (GMF), a neuroinflammatory protein first time isolated and cloned in our laboratory plays an important role in the pathogenesis of AD. However, no studies have been reported on whether anti-GMF antibody administration could downregulate neuroinflammation and attenuate amyloid pathology in AD brain. We investigated the potential effect of single dose of (2 mg/kg b.wt/mouse) intravenously (iv) injected with anti-GMF antibodyon cognitive function, neuroprotection, neuroinflammation and Aß load in the brain of 9-month-old 5XFAD mice. Following 4 weeks of anti-GMF antibody delivery in mice, we found reduced expression of GMF, astrocytic glial fibrillary acidic protein (GFAP) and microglial ionizing calcium binding adaptor molecule 1 (Iba1) as well as improvement inneuroinflammatory response via inhibition of pro-inflammatory cytokines (TNF-α, IL-1ß and IL-6) production and amyloid pathology in the cerebral cortex and hippocampal CA1 region of 5XFAD mice. Correspondingly, blockade of GMF function with anti-GMF antibody improved spatial learning, memory, and long-term recognition memory in 5XFAD mice. The present study demonstrates that the immune checkpoint blockade of GMF function with anti-GMF antibody coordinates anti-inflammatory effects to attenuate neurodegeneration in the cortex and hippocampal CA1 region of 5XFAD mouse brain. Further, our data suggest, that pharmacological immune neutralization of GMF is a promising neuroprotective strategy totherapeutically target neuroinflammation and neurodegeneration in AD. Graphical Abstract 5XFAD mice Polyclonal anti-GMF antibody.

Real-Time Noninvasive Bioluminescence, Ultrasound and Photoacoustic Imaging in NFκB-RE-Luc Transgenic Mice Reveal Glia Maturation Factor-Mediated Immediate and Sustained Spatio-Temporal Activation of NFκB Signaling Post-Traumatic Brain Injury in a Gender-Specific Manner.

Neurotrauma especially traumatic brain injury (TBI) is the leading cause of death and disability worldwide. To improve upon the early diagnosis and develop precision-targeted therapies for TBI, it is critical to understand the underlying molecular mechanisms and signaling pathways. The transcription factor, nuclear factor kappa B (NFκB), which is ubiquitously expressed, plays a crucial role in the normal cell survival, proliferation, differentiation, function, as well as in disease states like neuroinflammation and neurodegeneration. Here, we hypothesized that real-time noninvasive bioluminescence molecular imaging allows rapid and precise monitoring of TBI-induced immediate and rapid spatio-temporal activation of NFκB signaling pathway in response to Glia maturation factor (GMF) upregulation which in turn leads to neuroinflammation and neurodegeneration post-TBI. To test and validate our hypothesis and to gain novel mechanistic insights, we subjected NFκB-RE-Luc transgenic male and female mice to TBI and performed real-time noninvasive bioluminescence imaging (BLI) as well as photoacoustic and ultrasound imaging (PAI). Our BLI data revealed that TBI leads to an immediate and sustained activation of NFκB signaling. Further, our BLI data suggest that especially in male NFκB-RE-Luc transgenic mice subjected to TBI, in addition to brain, there is widespread activation of NFκB signaling in multiple organs. However, in the case of the female NFκB-RE-Luc transgenic mice, TBI induces a very specific and localized activation of NFκB signaling in the brain. Further, our microRNA data suggest that TBI induces significant upregulation of mir-9-5p, mir-21a-5p, mir-34a-5p, mir-16-3p, as well as mir-155-5p within 24 h and these microRNAs can be successfully used as TBI-specific biomarkers. To the best of our knowledge, this is one of the first and unique study of its kind to report immediate and sustained activation of NFκB signaling post-TBI in a gender-specific manner by utilizing real-time non-invasive BLI and PAI in NFκB-RE-Luc transgenic mice. Our study will prove immensely beneficial to gain novel mechanistic insights underlying TBI, unravel novel therapeutic targets, as well as enable us to monitor in real-time the response to innovative TBI-specific precision-targeted gene and stem cell-based precision medicine.

Acute Traumatic Brain Injury-Induced Neuroinflammatory Response and Neurovascular Disorders in the Brain.

Acute traumatic brain injury (TBI) leads to neuroinflammation, neurodegeneration, cognitive decline, psychological disorders, increased blood-brain barrier (BBB) permeability, and microvascular damage in the brain. Inflammatory mediators secreted from activated glial cells, neurons, and mast cells are implicated in the pathogenesis of TBI through secondary brain damage. Abnormalities or damage to the neurovascular unit is the indication of secondary injuries in the brain after TBI. However, the precise mechanisms of molecular and ultrastructural neurovascular alterations involved in the pathogenesis of acute TBI are not yet clearly understood. Moreover, currently, there are no precision-targeted effective treatment options to prevent the sequelae of TBI. In this study, mice were subjected to closed head weight-drop-induced acute TBI and evaluated neuroinflammatory and neurovascular alterations in the brain by immunofluorescence staining or quantitation by enzyme-linked immunosorbent assay (ELISA) procedure. Mast cell stabilizer drug cromolyn was administered to inhibit the neuroinflammatory response of TBI. Results indicate decreased level of pericyte marker platelet-derived growth factor receptor-beta (PDGFR-ß) and BBB-associated tight junction proteins junctional adhesion molecule-A (JAM-A) and zonula occludens-1 (ZO-1) in the brains 7 days after weight-drop-induced acute TBI as compared with the brains from sham control mice indicating acute TBI-associated BBB/tight junction protein disruption. Further, the administration of cromolyn drug significantly inhibited acute TBI-associated decrease of PDGFR-ß, JAM-A, and ZO-1 in the brain. These findings suggest that acute TBI causes BBB/tight junction damage and that cromolyn administration could protect this acute TBI-induced brain damage as well as its long-time consequences.

Neuroprotective effects of flavone luteolin in neuroinflammation and neurotrauma.

Neuroinflammation leads to neurodegeneration, cognitive defects, and neurodegenerative disorders. Neurotrauma/traumatic brain injury (TBI) can cause activation of glial cells, neurons, and neuroimmune cells in the brain to release neuroinflammatory mediators. Neurotrauma leads to immediate primary brain damage (direct damage), neuroinflammatory responses, neuroinflammation, and late secondary brain damage (indirect) through neuroinflammatory mechanism. Secondary brain damage leads to chronic inflammation and the onset and progression of neurodegenerative diseases. Currently, there are no effective and specific therapeutic options to treat these brain damages or neurodegenerative diseases. Flavone luteolin is an important natural polyphenol present in several plants that show anti-inflammatory, antioxidant, anticancer, cytoprotective, and macrophage polarization effects. In this short review article, we have reviewed the neuroprotective effects of luteolin in neurotrauma and neurodegenerative disorders and pathways involved in this mechanism. We have collected data for this study from publications in the PubMed using the keywords luteolin and mast cells, neuroinflammation, neurodegenerative diseases, and TBI. Recent reports suggest that luteolin suppresses systemic and neuroinflammatory responses in Coronavirus disease 2019 (COVID-19). Studies have shown that luteolin exhibits neuroprotective effects through various mechanisms, including suppressing immune cell activation, such as mast cells, and inflammatory mediators released from these cells. In addition, luteolin can suppress neuroinflammatory response, activation of microglia and astrocytes, oxidative stress, neuroinflammation, and the severity of neuroinflammatory diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, and TBI pathogenesis. In conclusion, luteolin can improve cognitive decline and enhance neuroprotection in neurodegenerative diseases, TBI, and stroke.

Current Trends in Biomarkers for Traumatic Brain Injury.

Neurotrauma, especially Traumatic Brain Injury (TBI) is a major health concern not only for the civilian population but also for the military personnel. Currently there are no precision and regenerative therapies available for the successful treatment of TBI patients. Hence, early detection and treatment options may prevent the severity and untoward harmful effects of TBI. However, currently there are no effective biomarkers available for the rapid and robust diagnosis as well as prognosis of TBI. Several biomarkers in blood, cerebrospinal fluid (CSF), saliva and urine have been explored to assess the onset, progression, severity and prognosis of TBI recently. Present knowledge on the blood biomarkers including cytokines and chemokines and in vivo imaging modalities are useful to some extent to detect and treat TBI patients. Here, we review S100B, Glial Fibrillary Acidic Protein (GFAP), Neuron Specific Enolase (NSE), Myelin Basic Protein (MBP), Ubiquitin C-terminal Hydrolase L1 (UCHL1), tau protein, and alpha spectrin II break down products regarding their usefulness as a set of reliable biomarkers for the robust diagnosis of TBI. We suggest that these biomarkers may prove very useful for the diagnosis and prognosis of TBI.

Glia Maturation Factor (GMF) Regulates Microglial Expression Phenotypes and the Associated Neurological Deficits in a Mouse Model of Traumatic Brain Injury.

Traumatic brain injury (TBI) induces inflammatory responses through microglial activation and polarization towards a more inflammatory state that contributes to the deleterious secondary brain injury. Glia maturation factor (GMF) is a pro-inflammatory protein that is responsible for neuroinflammation following insult to the brain, such as in TBI. We hypothesized that the absence of GMF in GMF-knockout (GMF-KO) mice would regulate microglial activation state and the M1/M2 phenotypes following TBI. We used the weight drop model of TBI in C57BL/6 mice wild-type (WT) and GMF-KO mice. Immunofluorescence staining, Western blot, and ELISA assays were performed to confirm TBI-induced histopathological and neuroinflammatory changes. Behavioral analysis was done to check motor coordination ability and cognitive function. We demonstrated that the deletion of GMF in GMF-KO mice significantly limited lesion volume, attenuated neuronal loss, inhibited gliosis, and activated microglia adopted predominantly anti-inflammatory (M2) phenotypes. Using an ELISA method, we found a gradual decrease in pro-inflammatory cytokines (TNF-α and IL-6) and upregulation of anti-inflammatory cytokines (IL-4 and IL-10) in GMF-KO mice compared with WT mice, thus, promoting the transition of microglia towards a more predominantly anti-inflammatory (M2) phenotype. GMF-KO mice showed significant improvement in motor ability, memory, and cognition. Overall, our results demonstrate that GMF deficiency regulates microglial polarization, which ameliorates neuronal injury and behavioral impairments following TBI in mice and concludes that GMF is a regulator of neuroinflammation and an ideal therapeutic target for the treatment of TBI.

Mast Cell Activation, Neuroinflammation, and Tight Junction Protein Derangement in Acute Traumatic Brain Injury.

Traumatic brain injury (TBI) is one of the major health problems worldwide that causes death or permanent disability through primary and secondary damages in the brain. TBI causes primary brain damage and activates glial cells and immune and inflammatory cells, including mast cells in the brain associated with neuroinflammatory responses that cause secondary brain damage. Though the survival rate and the neurological deficiencies have shown significant improvement in many TBI patients with newer therapeutic options, the underlying pathophysiology of TBI-mediated neuroinflammation, neurodegeneration, and cognitive dysfunctions is understudied. In this study, we analyzed mast cells and neuroinflammation in weight drop-induced TBI. We analyzed mast cell activation by toluidine blue staining, serum chemokine C-C motif ligand 2 (CCL2) level by enzyme-linked immunosorbent assay (ELISA), and proteinase-activated receptor-2 (PAR-2), a mast cell and inflammation-associated protein, vascular endothelial growth factor receptor 2 (VEGFR2), and blood-brain barrier tight junction-associated claudin 5 and Zonula occludens-1 (ZO-1) protein expression in the brains of TBI mice. Mast cell activation and its numbers increased in the brains of 24 h and 72 h TBI when compared with sham control brains without TBI. Mouse brains after TBI show increased CCL2, PAR-2, and VEGFR2 expression and derangement of claudin 5 and ZO-1 expression as compared with sham control brains. TBI can cause mast cell activation, neuroinflammation, and derangement of tight junction proteins associated with increased BBB permeability. We suggest that inhibition of mast cell activation can suppress neuroimmune responses and glial cell activation-associated neuroinflammation and neurodegeneration in TBI.

COVID-19, Mast Cells, Cytokine Storm, Psychological Stress, and Neuroinflammation.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new pandemic infectious disease that originated in China. COVID-19 is a global public health emergency of international concern. COVID-19 causes mild to severe illness with high morbidity and mortality, especially in preexisting risk groups. Therapeutic options are now limited to COVID-19. The hallmark of COVID-19 pathogenesis is the cytokine storm with elevated levels of interleukin-6 (IL-6), IL-1ß, tumor necrosis factor-alpha (TNF-α), chemokine (C-C-motif) ligand 2 (CCL2), and granulocyte-macrophage colony-stimulating factor (GM-CSF). COVID-19 can cause severe pneumonia, and neurological disorders, including stroke, the damage to the neurovascular unit, blood-brain barrier disruption, high intracranial proinflammatory cytokines, and endothelial cell damage in the brain. Mast cells are innate immune cells and also implicated in adaptive immune response, systemic inflammatory diseases, neuroinflammatory diseases, traumatic brain injury and stroke, and stress disorders. SARS-CoV-2 can activate monocytes/macrophages, dendritic cells, T cells, mast cells, neutrophils, and induce cytokine storm in the lung. COVID-19 can activate mast cells, neurons, glial cells, and endothelial cells. SARS-CoV-2 infection can cause psychological stress and neuroinflammation. In conclusion, COVID-19 can induce mast cell activation, psychological stress, cytokine storm, and neuroinflammation.

Absence of Glia Maturation Factor Protects from Axonal Injury and Motor Behavioral Impairments after Traumatic Brain Injury.

Traumatic brain injury (TBI) causes disability and death, accelerating the progression towards Alzheimer's disease and Parkinson's disease (PD). TBI causes serious motor and cognitive impairments, as seen in PD that arise during the period of the initial insult. However, this has been understudied relative to TBI induced neuroinflammation, motor and cognitive decline that progress towards PD. Neuronal ubiquitin-C-terminal hydrolase- L1 (UCHL1) is a thiol protease that breaks down ubiquitinated proteins and its level represents the severity of TBI. Previously, we demonstrated the molecular action of glia maturation factor (GMF); a proinflammatory protein in mediating neuroinflammation and neuronal loss. Here, we show that the weight drop method induced TBI neuropathology using behavioral tests, western blotting, and immunofluorescence techniques on sections from wild type (WT) and GMF-deficient (GMF-KO) mice. Results reveal a significant improvement in substantia nigral tyrosine hydroxylase and dopamine transporter expression with motor behavioral performance in GMF-KO mice following TBI. In addition, a significant reduction in neuroinflammation was manifested, as shown by activation of nuclear factor-kB, reduced levels of inducible nitric oxide synthase, and cyclooxygenase- 2 expressions. Likewise, neurotrophins including brain-derived neurotrophic factor and glial-derived neurotrophic factor were significantly improved in GMF-KO mice than WT 72 h post-TBI. Consistently, we found that TBI enhances GFAP and UCHL-1 expression and reduces the number of dopaminergic TH-positive neurons in WT compared to GMF-KO mice 72 h post-TBI. Interestingly, we observed a reduction of THpositive tanycytes in the median eminence of WT than GMF-KO mice. Overall, we found that absence of GMF significantly reversed these neuropathological events and improved behavioral outcome. This study provides evidence that PD-associated pathology progression can be initiated upon induction of TBI.

NLRP3 inflammasome and glia maturation factor coordinately regulate neuroinflammation and neuronal loss in MPTP mouse model of Parkinson's disease.

Neuroinflammation plays an active role in the pathogenesis of several neurodegenerative diseases, including Parkinson's disease (PD). Earlier studies from this laboratory showed that glia maturation factor (GMF), a proinflammatory mediator; is up-regulated in the brain in neurodegenerative diseases and that deficiency of GMF showed decreased production of IL-1ß and improved behavioral abnormalities in mouse model of PD. However, the mechanisms linking GMF and dopaminergic neuronal death have not been completely explored. In the present study, we have investigated the expression of NLRP3 inflammasome and caspase-1 in the substantia nigra (SN) of human PD and non-PD brains by immunohistochemistry. Wild-type (WT) and GMF-/- (GMF knock-out) mice were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydro pyridine (MPTP) and the brains were isolated for neurochemical and morphological examinations. NLRP3 and caspase-1 positive cells were found significantly increased in PD when compared to non-PD control brains. Moreover, GMF co-localized with α-Synuclein within reactive astrocytes in the midbrain of PD. Mice treated with MPTP exhibit glial activation-induced inflammation, and nigrostriatal dopaminergic neurodegeneration. Interestingly, increased expression of the inflammasome components in astrocytes and microglia observed in the SN of MPTP-treated WT mice were significantly reduced in GMF-/- mice. Additionally, we show that NLRP3 activation in microglia leads to translocation of GMF and NLRP3 to the mitochondria. We conclude that downregulation of GMF may have beneficial effects in prevention of PD by modulating the cytotoxic functions of microglia and astrocytes through reduced activation of the NLRP3 inflammasome; a major contributor of neuroinflammation in the CNS.

Neuroinflammation Mediated by Glia Maturation Factor Exacerbates Neuronal Injury in an in vitro Model of Traumatic Brain Injury.

Traumatic brain injury (TBI) is the primary cause of death and disability affecting over 10 million people in the industrialized world. TBI causes a wide spectrum of secondary molecular and cellular complications in the brain. However, the pathological events are still not yet fully understood. Previously, we have shown that the glia maturation factor (GMF) is a mediator of neuroinflammation in neurodegenerative diseases. To identify the potential molecular pathways accompanying TBI, we used an in vitro cell culture model of TBI. A standardized injury was induced by scalpel cut through a mixed primary cell culture of astrocytes, microglia and neurons obtained from both wild type (WT) and GMF-deficient (GMF-KO) mice. Cell culture medium and whole-cell lysates were collected at 24, 48, and 72 h after the scalpel cuts injury and probed for oxidative stress using immunofluorescence analysis. Results showed that oxidative stress markers such as glutathione and glutathione peroxidase were significantly reduced, while release of cytosolic enzyme lactate dehydrogenase along with nitric oxide and prostaglandin E2 were significantly increased in injured WT cells compared with injured GMF-KO cells. In addition, injured WT cells showed increased levels of oxidation product 4-hydroxynonenal and 8-oxo-2'-deoxyguanosine compared with injured GMF-KO cells. Further, we found that injured WT cells showed a significantly increased expression of glial fibrillary acidic protein, ionized calcium binding adaptor molecule 1, and phosphorylated ezrin/radixin/moesin proteins, and reduced microtubule associated protein expression compared with injured GMF-KO cells after injury. Collectively, our results demonstrate that GMF exacerbates the oxidative stress-mediated neuroinflammation that could be brought about by TBI-induced astroglial activation.

Psychological Stress-Induced Immune Response and Risk of Alzheimer's Disease in Veterans from Operation Enduring Freedom and Operation Iraqi Freedom.

PURPOSE: Psychological stress is a significant health problem in veterans and their family members. Traumatic brain injury (TBI) and stress lead to the onset, progression, and worsening of several inflammatory and neurodegenerative diseases in veterans and civilians. Alzheimer's disease (AD) is a progressive, irreversible neuroinflammatory disease that causes problems with memory, thinking, and behavior. TBIs and chronic psychological stress cause and accelerate the pathology of neuroinflammatory diseases such as AD. However, the precise molecular and cellular mechanisms governing neuroinflammation and neurodegeneration are currently unknown, especially in veterans. The purpose of this review article was to advance the hypothesis that stress and TBI-mediated immune response substantially contribute and accelerate the pathogenesis of AD in veterans and their close family members and civilians. METHODS: The information in this article was collected and interpreted from published articles in PubMed between 1985 and 2020 using the key words stress, psychological stress, Afghanistan war, Operation Enduring Freedom (OEF), Iraq War, Operation Iraqi Freedom (OIF), Operation New Dawn (OND), traumatic brain injury, mast cell and stress, stress and neuroimmune response, stress and Alzheimer's disease, traumatic brain injury, and Alzheimer's disease. FINDINGS: Chronic psychological stress and brain injury induce the generation and accumulation of beta-amyloid peptide, amyloid plaques, neurofibrillary tangles, and phosphorylation of tau in the brain, thereby contributing to AD pathogenesis. Active military personnel and veterans are under enormous psychological stress due to various war-related activities, including TBIs, disabilities, fear, new environmental conditions, lack of normal life activities, insufficient communications, explosions, military-related noise, and health hazards. Brain injury, stress, mast cell, and other immune cell activation can induce headache, migraine, dementia, and upregulate neuroinflammation and neurodegeneration in veterans of Operation Enduring Freedom, Operation Iraqi Freedom, and Operation New Dawn. TBIs, posttraumatic stress disorder, psychological stress, pain, glial activation, and dementia in active military personnel, veterans, or their family members can cause AD several years later in their lives. We suggest that there are increasing numbers of veterans with TBIs and stress and that these veterans may develop AD late in life if no appropriate therapeutic intervention is available. IMPLICATIONS: Per these published reports, the fact that TBIs and psychological stress can accelerate the pathogenesis of AD should be recognized. Active military personnel, veterans, and their close family members should be evaluated regularly for stress symptoms to prevent the pathogenesis of neurodegenerative diseases, including AD.

A role for glia maturation factor dependent activation of mast cells and microglia in MPTP induced dopamine loss and behavioural deficits in mice.

The molecular mechanism mediating degeneration of nigrostriatal dopaminergic neurons in Parkinson's disease (PD) is not yet fully understood. Previously, we have shown the contribution of glia maturation factor (GMF), a proinflammatory protein in dopaminergic neurodegeneration mediated by activation of mast cells (MCs). In this study, methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigrostriatal neurodegeneration and astro-glial activations were determined by western blot and immunofluorescence techniques in wild type (WT) mice, MC-deficient (MC-KO) mice and GMF-deficient (GMF-KO) mice, with or without MC reconstitution before MPTP administration. We show that GMF-KO in the MCs reduces the synergistic effects of MC and Calpain1 (calcium-activated cysteine protease enzyme)-dependent dopaminergic neuronal loss that reduces motor behavioral impairments in MPTP-treated mouse. Administration of MPTP increase in calpain-mediated proteolysis in nigral dopaminergic neurons further resulting in motor decline in mice. We found that MPTP administered WT mice exhibits oxidative stress due to significant increases in the levels of malondialdehyde, superoxide dismutase and reduction in the levels of reduced glutathione and glutathione peroxidase activity as compared with both MC-KO and GMF-KO mice. The number of TH-positive neurons in the ventral tegmental area, substantia nigra and the fibers in the striatum were significantly reduced while granulocyte macrophage colony-stimulating factor (GM-CSF), MC-Tryptase, GFAP, IBA1, Calpain1 and intracellular adhesion molecule 1 expression were significantly increased in WT mice. Similarly, tyrosine hydroxylase, dopamine transporters and vesicular monoamine transporters 2 proteins expression were significantly reduced in the SN of MPTP treated WT mice. The motor behavior as analyzed by rotarod and hang test was significantly reduced in WT mice as compared with both the MC-KO and GMF-KO mice. We conclude that GMF-dependent MC activation enhances the detrimental effect of astro-glial activation-mediated oxidative stress and neuroinflammation in the midbrain, and its inhibition may slowdown the progression of PD.

Brain Injury-Mediated Neuroinflammatory Response and Alzheimer's Disease.

Traumatic brain injury (TBI) is a major health problem in the United States, which affects about 1.7 million people each year. Glial cells, T-cells, and mast cells perform specific protective functions in different regions of the brain for the recovery of cognitive and motor functions after central nervous system (CNS) injuries including TBI. Chronic neuroinflammatory responses resulting in neuronal death and the accompanying stress following brain injury predisposes or accelerates the onset and progression of Alzheimer's disease (AD) in high-risk individuals. About 5.7 million Americans are currently living with AD. Immediately following brain injury, mast cells respond by releasing prestored and preactivated mediators and recruit immune cells to the CNS. Blood-brain barrier (BBB), tight junction and adherens junction proteins, neurovascular and gliovascular microstructural rearrangements, and dysfunction associated with increased trafficking of inflammatory mediators and inflammatory cells from the periphery across the BBB leads to increase in the chronic neuroinflammatory reactions following brain injury. In this review, we advance the hypothesis that neuroinflammatory responses resulting from mast cell activation along with the accompanying risk factors such as age, gender, food habits, emotional status, stress, allergic tendency, chronic inflammatory diseases, and certain drugs can accelerate brain injury-associated neuroinflammation, neurodegeneration, and AD pathogenesis.

Loss of tau and Fyn reduces compensatory effects of MAP2 for tau and reveals a Fyn-independent effect of tau on calcium.

Microtubule-associated protein tau associates with Src family tyrosine kinase Fyn and is tyrosine phosphorylated by Fyn. The presence of tyrosine phosphorylated tau in AD and the involvement of Fyn in AD has drawn attention to the tau-Fyn complex. In this study, a tau-Fyn double knockout (DKO) mouse was generated to investigate the role of the complex. DKO mice resembled Fyn KO in novel object recognition and contextual fear conditioning tasks and resembled tau KO mice in the pole test and protection from pentylenetetrazole-induced seizures. In glutamate-induced Ca2+ response, Fyn KO was decreased relative to WT and DKO had a greater reduction relative to Fyn KO, suggesting that tau may have a Fyn-independent role. Since tau KO resembled WT in its Ca2+ response, we investigated whether microtubule-associated protein 2 (MAP2) served to compensate for tau, since the MAP2 level was increased in tau KO but decreased in DKO mice. We found that like tau, MAP2 increased Fyn activity. Moreover, tau KO neurons had increased density of dendritic MAP2-Fyn complexes relative to WT neurons. Therefore, we hypothesize that in the tau KO, the absence of tau would be compensated by MAP2, especially in the dendrites, where tau-Fyn complexes are of critical importance. In the DKO, decreased levels of MAP2 made compensation more difficult, thus revealing the effect of tau in the Ca2+ response.

Synergy in Disruption of Mitochondrial Dynamics by Aß (1-42) and Glia Maturation Factor (GMF) in SH-SY5Y Cells Is Mediated Through Alterations in Fission and Fusion Proteins.

The pathological form of amyloid beta (Aß) peptide is shown to be toxic to the mitochondria and implicates this organelle in the progression and pathogenesis of Alzheimer's disease (AD). Mitochondria are dynamic structures constantly undergoing fission and fusion, and altering their shape and size while traveling through neurons. Mitochondrial fission (Drp1, Fis1) and fusion (OPA1, Mfn1, and Mfn2) proteins are balanced in healthy neuronal cells. Glia maturation factor (GMF), a neuroinflammatory protein isolated and cloned in our laboratory plays an important role in the pathogenesis of AD. We hypothesized that GMF, a brain-localized inflammatory protein, promotes oxidative stress-mediated disruption of mitochondrial dynamics by alterations in mitochondrial fission and fusion proteins which eventually leads to apoptosis in the Aß (1-42)-treated human neuroblastoma (SH-SY5Y) cells. The SH-SY5Y cells were incubated with GMF and Aß (1-42) peptide, and mitochondrial fission and fusion proteins were analyzed by immunofluorescence, western blotting, and co-immunoprecipitation. We report that SH-SY5Y cells incubated with GMF and Aß (1-42) promote mitochondrial fragmentation, by potentiating oxidative stress, mitophagy and shifts in the Bax/Bcl2 expression and release of cytochrome-c, and eventual apoptosis. In the present study, we show that GMF and Aß treatments significantly upregulate fission proteins and downregulate fusion proteins. The study shows that extracellular GMF is an important inflammatory mediator that mediates mitochondrial dynamics by altering the balance in fission and fusion proteins and amplifies similar effects promoted by Aß. Upregulated GMF in the presence of Aß could be an additional risk factor for AD, and their synergistic actions need to be explored as a potential therapeutic target to suppress the progression of AD.