Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biolog... more Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biological structures. Correct preparation of SEM samples can provide an unprecedented understanding of the nexus between cellular morphology and topography. This comparative study critically examines two coating methods for preparing biological samples for scanning electron microscopy, while also providing novel advice on how to prepare in vitro epithelial or endothelial samples for highresolution scanning-electron microscopy (HR-SEM). Two obstacles often confront
Alcohol abuse is a growing crisis within South Africa, with severe health and socioeconomic impli... more Alcohol abuse is a growing crisis within South Africa, with severe health and socioeconomic implications. Alcohol compromises the function of the blood-brain barrier (BBB), and thus its ability to regulate the homeostatic environment of the CNS is interrupted. In this study, an in vitro model of the BBB was utilized to study the effects of selected concentrations of alcohol (25mM-200mM) and the ameliorating effects of fermented rooibos (Aspalathus linearis) (0.003125%-1%), in an attempt to reverse the harmful oxidative effects of alcohol. The literature clearly states that alcohol (ethanol) compromises the BBB by reactive oxygen species (ROS) production and, therefore, rooibos, a shrub high in antioxidants and widely utilized nationally, was added to alcohol-exposed mouse brain endothelial (bEnd5) cells with the view to reverse the alcohol-induced effects on the BBB model. Alcohol-treated (25mM-400mM) bEnd5 monolayers expressed no toxicity, however, cell numbers were significantly suppressed (P<0.0274). To validate this finding, the activity of the mitochondria was investigated in order to understand if the cell's metabolism was related to the decrease in cell division. Results showed that for both acute and chronic exposure there was a decrease in mitochondrial activity (MA) for a period of 24-48 hours, thereafter, the MA of the bEnd5 cells returned to normality. However, in experiments which chronically (600mM and 800mM) exposed cells to alcohol over a period of 96 hours, MA was suppressed and did not return to normal. ABSTRACT iv Fermented rooibos caused a biphasic response to cellular proliferation at 24-72 hours, where the lower concentrations (0.0625-0.125 %) caused an increase in cellular proliferation and the higher concentrations (0.5-1%) resulted in a relative decrease in cellular proliferation. The long-term effect, after acute exposure, however, resulted in cell suppression at 96 hours (P<0.0073). With respect to the MA, bEnd5 cells exposed to fermented rooibos showed that lower concentrations (0.003125-0.0125%) were suppressed at 24 hours and was elevated at 48 hours and 96 hours for all concentrations. The exception being the highest concentration (0.1%), which showed a depression in MA (P<0.05). Treating cells with both alcohol and rooibos, resulted in exacerbated suppressing of the MA. The physiological function of the BBB model was investigated by monitoring the permeability using transendothelial electrical resistance (TEER) studies and the in vitro model used in this study was endorsed for the first time using high resolution scanning electron microscopy. TEER indicated incidental changes in the permeability, only at 24 hours, for both acute and chronic exposure to alcohol and rooibos. A novel finding, within this study, was the increase in electrical resistance across the formation of the cell monolayer, after treatment with alcohol. The data lead to the hypothesis for the effect of ROS on resistivity and provides a rationale to explain the effects of combinatory treatments that were expected to ameliorate the negative effect of alcohol, however, this study showed synergistically negative effects on the bEnd5 cells.
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that is mainly prevalent in ... more Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that is mainly prevalent in the older population. Approximately fifty million people are diagnosed with dementia, with AD accounting for 60–70% of these cases. Amyloid beta (Aβ) is considered a pathological hallmark of AD. The shorter Aβ 25 – 35 peptide fragments, formed from the amyloidogenic Aβ 1–40 peptide, plays a crucial role in the peptide’s neurotoxic activity (Pike et al., 2002). Acetylcholinesterase (AChE) as well as oxidative stress have shown to trigger Aβ formation and aggregation (Belluti et al., 2011; Cheignon et al., 2018). Previously, we synthesized multifunctional edaravone‐N‐benzyl pyridinium compounds that exhibited potent AChE inhibition and antioxidant activity as well as predicted to cross the blood‐brain barrier (BBB) using in silico models (Zondagh et al., 2020).
The pathological form of amyloid beta (Aβ) peptide is shown to be toxic to the mitochondria and i... more The pathological form of amyloid beta (Aβ) 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 Aβ (1-42)-treated human neuroblastoma (SH-SY5Y) cells. The SH-SY5Y cells were incubated with GMF and Aβ (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 Aβ (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 Aβ 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 Aβ. Upregulated GMF in the presence of Aβ 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.
Despite significant advancements in the field of molecular neurobiology especially neuroinflammat... more Despite significant advancements in the field of molecular neurobiology especially neuroinflammation and neurodegeneration, the highly complex molecular mechanisms underlying neurodegenerative diseases remain elusive. As a result, the development of the next generation neurotherapeutics has experienced a considerable lag phase. Recent advancements in the field of genome editing offer a new template for dissecting the precise molecular pathways underlying the complex neurodegenerative disorders. We believe that the innovative genome and transcriptome editing strategies offer an excellent opportunity to decipher novel therapeutic targets, develop novel neurodegenerative disease models, develop neuroimaging modalities, develop next-generation diagnostics as well as develop patient-specific precision-targeted personalized therapies to effectively treat neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, Frontotemporal dementia etc. Here, we review the latest developments in the field of CRISPR-mediated genome editing and provide unbiased futuristic insights regarding its translational potential to improve the treatment outcomes and minimize financial burden. However, despite significant advancements, we would caution the scientific community that since the CRISPR field is still evolving, currently we do not know the full spectrum of CRISPR-mediated side effects. In the wake of the recent news regarding CRISPR-edited human babies being born in China, we urge the scientific community to maintain high scientific and ethical standards and utilize CRISPR for developing in vitro disease in a dish model, in vivo testing in nonhuman primates and lower vertebrates and for the development of neurotherapeutics for the currently incurable neurodegenerative disorders.
Oxidative stress in the brain microvasculature is a common characteristic in models of cerebrovas... more Oxidative stress in the brain microvasculature is a common characteristic in models of cerebrovascular disease. It is, therefore, naturally prudent to hypothesize how antioxidant (AO) supplementation in brain vasculature, may be beneficial for combating cerebrovascular disease. Hyper doses of AOs in supplements and food, are commonly used as an ongoing remedial, 'over the counter,' treatment for most seasonal ailments. For the first time, this study reports the adverse effects of excess AOs on angiogenic properties of the blood-brain barrier (BBB) which have clinical implications. A medicinal tea, known as rooibos (Aspalathus linearis), commonly used in South Africa and marketed globally, for its prominent AO profile, demonstrated its effects on brain endothelial cellular (BEC) proliferation, toxicology, mitochondrial activity and permeability. In the current study, mouse BECs were seeded at passage numbers 30 to 40, at cell densities ranging from 10 3-10 6 cells/ml and were incubated at predetermined time intervals. Daily exposure to a selected concentration range of fermented A. linearis caused exacerbated effects with dose-related decreases in cellular proliferation, and unequivocally increased impermeability across an in vitro BBB model. No toxicity was observed for all selected concentrations of A. linearis. The data conclusively show that the use of excess AOs perturb BBB functionality and angiogenic properties, adversely implicating brain homeostasis. This suggests that excess AOs will lead to an impaired response to mechanical-induced injury and pathogenic infection of the BBB, resulting in compromised patient recovery.
(2022) Exosomes form tunneling nanotubes (TUNTs) in the blood-brain barrier: a nano-anatomical pe... more (2022) Exosomes form tunneling nanotubes (TUNTs) in the blood-brain barrier: a nano-anatomical perspective of barrier genesis.
The blood-brain barrier (BBB) is a robust interface between the blood and the central nervous sys... more The blood-brain barrier (BBB) is a robust interface between the blood and the central nervous system. Barrier type endothelium is able to limit paracellular (PC) movement, relegating molecular flux to the transendothelial pathways of brain endothelial cells (BECs). It is, therefore, apparent that any leakage via the PC shunts would effectively nullify the regulation of molecular flux across the transcellular pathways. The application of higher-resolution scanning electron microscopy (HR-SEM) illuminates the heterogenous, morphological profile that exists on the surface of BEC membranes and the relationship between these ultrastructures during the molecular construction of the PC space between adjacent BECs. In this study developing BEC monolayers were grown on mixed, cellulose esters insert membranes in a bicameral system. BEC monolayers were fixed in 2.5% glutaraldehyde, hydrated, critically dried, and sputter-coated, for imaging utilizing HR-SEM. This study, for the first time, sh...
Traumatic brain injury (TBI) is a major health problem in the United States, which affects about ... more 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 inflammat...
Mast cell activation plays an important role in stress-mediated disease pathogenesis. Chronic str... more Mast cell activation plays an important role in stress-mediated disease pathogenesis. Chronic stress cause or exacerbate aging and age-dependent neurodegenerative diseases. The severity of inflammatory diseases is worsened by the stress. Mast cell activation-dependent inflammatory mediators augment stress associated pain and neuroinflammation. Stress is the second most common trigger of headache due to mast cell activation. Alzheimer's disease (AD) is a progressive irreversible neurodegenerative disease that affects more women than men and woman's increased susceptibility to chronic stress could increase the risk for AD. Modern life-related stress, social stress, isolation stress, restraint stress, early life stress are associated with an increased level of neurotoxic beta amyloid (Aβ) peptide. Stress increases cognitive dysfunction, generates amyloid precursor protein (APP), hyperphosphorylated tau, neurofibrillary tangles (NFTs), and amyloid plaques (APs) in the brain. Stress-induced Aβ persists for years and generates APs even several years after the stress exposure. Stress activates hypothalamic-pituitary adrenal (HPA) axis and releases corticotropin-releasing hormone (CRH) from hypothalamus and in peripheral system, which increases the formation of Aβ, tau hyperphosphorylation, and blood-brain barrier (BBB) disruption in the brain. Mast cells are implicated in nociception and pain. Mast cells are the source and target of CRH and other neuropeptides that mediate neuroinflammation. Microglia express receptor for CRH that mediate neurodegeneration in AD. However, the exact mechanisms of how stress-mediated mast cell activation contribute to the pathogenesis of AD remains elusive. This mini-review highlights the possible role of stress and mast cell activation in neuroinflammation, BBB, and tight junction disruption and AD pathogenesis.
Probiotics in the Prevention and Management of Human Diseases, 2022
The immune system is a complex architecture of a collective and coordinated network regulated by ... more The immune system is a complex architecture of a collective and coordinated network regulated by various pathways to thermodynamically maintain immune homeostasis. The gut microbiota plays a pivotal role that offers significant stimuli (i.e., gut-brain, gut-lung, and gut-liver axis) for both innate and adaptive immunity, mediating immune and metabolic homeostasis. An intricate correlation between changes in the gut microbiota (dysbiosis) and common diseases/disorders have been attributed to the invasion of pathogens, constant use of antibiotics, and hypercytokinemia—a hallmark of immune homeostasis imbalance. These factors contribute to the severity of inflammatory diseases such as cardiovascular diseases, neurological disorders, and of late the coronavirus disease, Covid-19. Probiotics (Lactobacillus spp. and Bifidobacterium spp.) have been considered as alternative and/or adjuvant therapeutic in restoring the balance of gut microbiota for maintaining immune homeostasis and integrity. The probiotics catalyze dietary fibers and proteins to generate short-chain fatty acids and tryptophan to promote antiinflammatory cytokines, reduce epithelium permeability, reinforcing immunity in the gut mucosa, and regulating the systemic immune response. Herein, we review our overarching understanding of current applications of probiotics in amelioration of gut microbiome, and the improvement of gut barrier function and maintaining immune homeostasis. We also highlight clinical trials on probiotics with reported results for the treatment of inflammatory diseases. Additionally, the looming global Covid-19 pandemic makes it prudent to highlight the role of probiotics in both the innate and adaptive human immune responses, especially amid the Covid-19 vaccination paradigm.
Alcohol abuse is a growing crisis within South Africa, with severe health and socioeconomic impli... more Alcohol abuse is a growing crisis within South Africa, with severe health and socioeconomic implications. Alcohol compromises the function of the blood-brain barrier (BBB), and thus its ability to regulate the homeostatic environment of the CNS is interrupted. In this study, an in vitro model of the BBB was utilized to study the effects of selected concentrations of alcohol (25mM-200mM) and the ameliorating effects of fermented rooibos (Aspalathus linearis) (0.003125%-1%), in an attempt to reverse the harmful oxidative effects of alcohol. The literature clearly states that alcohol (ethanol) compromises the BBB by reactive oxygen species (ROS) production and, therefore, rooibos, a shrub high in antioxidants and widely utilized nationally, was added to alcohol-exposed mouse brain endothelial (bEnd5) cells with the view to reverse the alcohol-induced effects on the BBB model. Alcohol-treated (25mM-400mM) bEnd5 monolayers expressed no toxicity, however, cell numbers were significantly suppressed (P<0.0274). To validate this finding, the activity of the mitochondria was investigated in order to understand if the cell's metabolism was related to the decrease in cell division. Results showed that for both acute and chronic exposure there was a decrease in mitochondrial activity (MA) for a period of 24-48 hours, thereafter, the MA of the bEnd5 cells returned to normality. However, in experiments which chronically (600mM and 800mM) exposed cells to alcohol over a period of 96 hours, MA was suppressed and did not return to normal. ABSTRACT iv Fermented rooibos caused a biphasic response to cellular proliferation at 24-72 hours, where the lower concentrations (0.0625-0.125 %) caused an increase in cellular proliferation and the higher concentrations (0.5-1%) resulted in a relative decrease in cellular proliferation. The long-term effect, after acute exposure, however, resulted in cell suppression at 96 hours (P<0.0073). With respect to the MA, bEnd5 cells exposed to fermented rooibos showed that lower concentrations (0.003125-0.0125%) were suppressed at 24 hours and was elevated at 48 hours and 96 hours for all concentrations. The exception being the highest concentration (0.1%), which showed a depression in MA (P<0.05). Treating cells with both alcohol and rooibos, resulted in exacerbated suppressing of the MA. The physiological function of the BBB model was investigated by monitoring the permeability using transendothelial electrical resistance (TEER) studies and the in vitro model used in this study was endorsed for the first time using high resolution scanning electron microscopy. TEER indicated incidental changes in the permeability, only at 24 hours, for both acute and chronic exposure to alcohol and rooibos. A novel finding, within this study, was the increase in electrical resistance across the formation of the cell monolayer, after treatment with alcohol. The data lead to the hypothesis for the effect of ROS on resistivity and provides a rationale to explain the effects of combinatory treatments that were expected to ameliorate the negative effect of alcohol, however, this study showed synergistically negative effects on the bEnd5 cells.
Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biolog... more Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biological structures. Correct preparation of SEM samples can provide an unprecedented understanding of the nexus between cellular morphology and topography. This comparative study critically examines two coating methods for preparing biological samples for scanning electron microscopy, while also providing novel advice on how to prepare in vitro epithelial or endothelial samples for high-resolution scanning-electron microscopy (HR-SEM). Two obstacles often confront the biologist when investigating cellular structures grown under tissue culture conditions, namely., how to prepare and present the biological samples to the HR-SEM microscope without affecting topographical membrane and cellular structural alterations. Firstly, our use of the Millicell cellulose inserts on which to grow our cellular samples in preparation for HR-SEM is both novel and advantageous to comparing the permeability func...
The blood–brain barrier (BBB) is fundamental in maintaining central nervous system (CNS) homeosta... more The blood–brain barrier (BBB) is fundamental in maintaining central nervous system (CNS) homeostasis by regulating the chemical environment of the underlying brain parenchyma. Brain endothelial cells (BECs) constitute the anatomical and functional basis of the BBB. Communication between adjacent BECs is critical for establishing BBB integrity, and knowledge of its nanoscopic landscape will contribute to our understanding of how juxtaposed zones of tight-junction protein interactions between BECs are aligned. The review discusses and critiques types of nanostructures contributing to the process of BBB genesis. We further critically evaluate earlier findings in light of novel high-resolution electron microscopy descriptions of nanoscopic tubules. One such phenotypic structure is BEC cytoplasmic projections, which, early in the literature, is postulated as brain capillary endothelial cilia, and is evaluated and compared to the recently discovered nanotubules (NTs) formed in the paracel...
Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biolog... more Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biological structures. Correct preparation of SEM samples can provide an unprecedented understanding of the nexus between cellular morphology and topography. This comparative study critically analyses two coating methods for investigating biological samples utilizing scanning electron microscopy. Biological material is often non-conducting, thermally sensitive and fragile and, therefore, needs to be fixed correctly and coated with thin conducting metal. This study aimed to compare biological sample coating modalities employed in the visualizing and analysis of texturized, membranous ultrastructures. The experimental model employed immortalized mouse brain endothelial cells (b.End5). The topographical structures of developing endothelial cells (ECs) were explored at high definition utilizing SEM as a tool to investigate the ultrastructural dynamics of membrane differentiation during monolayer development. Cell monolayers were prepared using two coating modalities, namely: carbon and gold:palladium (Au:Pd) sputter coating. SEM produced three-dimensional micrographs from which useful topographical cellular data could be extrapolated. We report on the novel ultrastructural membranous features of b.End5 cells. Furthermore, nanostructures were observably secreted on the BEC plasma membrane and are the nexus between direct cell-to-cell communication and cell monolayer development. The two coating methods display distinct differences in the topographical profile of developing BEC cytoarchitecture. SEM provides a glimpse of the ultrastructural behaviour of a differentiating cell surface topography. This study illuminates the relationship between generating highly definitive images and the appropriate coating method. The micrographical data suggests that Au:Pd sputter-coated samples generate descript imagery, providing useful information for profiling membrane nanostructures.
The brain capillary endothelium is highly regulatory, maintaining the chemical stability of the b... more The brain capillary endothelium is highly regulatory, maintaining the chemical stability of the brain’s microenvironment. The role of cytoskeletal proteins in tethering nanotubules (TENTs) during barrier-genesis was investigated using the established immortalized mouse brain endothelial cell line (bEnd5) as an in vitro blood-brain barrier (BBB) model. The morphology of bEnd5 cells was evaluated using both high-resolution scanning electron microscopy and immunofluorescence to evaluate treatment with depolymerizing agents Cytochalasin D for F-actin filaments and Nocodazole for α-tubulin microtubules. The effects of the depolymerizing agents were investigated on bEnd5 monolayer permeability by measuring the transendothelial electrical resistance (TEER). The data endorsed that during barrier-genesis, F-actin and α-tubulin play a cytoarchitectural role in providing both cell shape dynamics and cytoskeletal structure to TENTs forming across the paracellular space to provide cell-cell enga...
High-resolution electron microscopy (HREM) imaging of the in vitro blood-brain barrier (BBB), is ... more High-resolution electron microscopy (HREM) imaging of the in vitro blood-brain barrier (BBB), is a promising modality for investigating the dynamic morphological interplay underpinning BBB development. The successful establishment of BBB integrity is grounded in the brain endothelial cells (BEC’s) ability to occlude its paracellular spaces of brain capillaries through the expression of the intercellular tight junction (TJ) proteins. The impermeability of these paracellular spaces are crucial in the regulation of transcellular transport systems to achieve homeostasis of the central nervous system. To-date research describing morphologically, the dynamics by which TJ interaction is orchestrated to successfully construct a specialized barrier remains undescribed. In this study, the application of HREM illuminates the novel, dynamic and highly restrictive BEC paracellular pathway which is founded based on lateral membrane alignment which is the functional imperative for the mechanical j...
Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biolog... more Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biological structures. Correct preparation of SEM samples can provide an unprecedented understanding of the nexus between cellular morphology and topography. This comparative study critically examines two coating methods for preparing biological samples for scanning electron microscopy, while also providing novel advice on how to prepare in vitro epithelial or endothelial samples for highresolution scanning-electron microscopy (HR-SEM). Two obstacles often confront
Alcohol abuse is a growing crisis within South Africa, with severe health and socioeconomic impli... more Alcohol abuse is a growing crisis within South Africa, with severe health and socioeconomic implications. Alcohol compromises the function of the blood-brain barrier (BBB), and thus its ability to regulate the homeostatic environment of the CNS is interrupted. In this study, an in vitro model of the BBB was utilized to study the effects of selected concentrations of alcohol (25mM-200mM) and the ameliorating effects of fermented rooibos (Aspalathus linearis) (0.003125%-1%), in an attempt to reverse the harmful oxidative effects of alcohol. The literature clearly states that alcohol (ethanol) compromises the BBB by reactive oxygen species (ROS) production and, therefore, rooibos, a shrub high in antioxidants and widely utilized nationally, was added to alcohol-exposed mouse brain endothelial (bEnd5) cells with the view to reverse the alcohol-induced effects on the BBB model. Alcohol-treated (25mM-400mM) bEnd5 monolayers expressed no toxicity, however, cell numbers were significantly suppressed (P<0.0274). To validate this finding, the activity of the mitochondria was investigated in order to understand if the cell's metabolism was related to the decrease in cell division. Results showed that for both acute and chronic exposure there was a decrease in mitochondrial activity (MA) for a period of 24-48 hours, thereafter, the MA of the bEnd5 cells returned to normality. However, in experiments which chronically (600mM and 800mM) exposed cells to alcohol over a period of 96 hours, MA was suppressed and did not return to normal. ABSTRACT iv Fermented rooibos caused a biphasic response to cellular proliferation at 24-72 hours, where the lower concentrations (0.0625-0.125 %) caused an increase in cellular proliferation and the higher concentrations (0.5-1%) resulted in a relative decrease in cellular proliferation. The long-term effect, after acute exposure, however, resulted in cell suppression at 96 hours (P<0.0073). With respect to the MA, bEnd5 cells exposed to fermented rooibos showed that lower concentrations (0.003125-0.0125%) were suppressed at 24 hours and was elevated at 48 hours and 96 hours for all concentrations. The exception being the highest concentration (0.1%), which showed a depression in MA (P<0.05). Treating cells with both alcohol and rooibos, resulted in exacerbated suppressing of the MA. The physiological function of the BBB model was investigated by monitoring the permeability using transendothelial electrical resistance (TEER) studies and the in vitro model used in this study was endorsed for the first time using high resolution scanning electron microscopy. TEER indicated incidental changes in the permeability, only at 24 hours, for both acute and chronic exposure to alcohol and rooibos. A novel finding, within this study, was the increase in electrical resistance across the formation of the cell monolayer, after treatment with alcohol. The data lead to the hypothesis for the effect of ROS on resistivity and provides a rationale to explain the effects of combinatory treatments that were expected to ameliorate the negative effect of alcohol, however, this study showed synergistically negative effects on the bEnd5 cells.
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that is mainly prevalent in ... more Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that is mainly prevalent in the older population. Approximately fifty million people are diagnosed with dementia, with AD accounting for 60–70% of these cases. Amyloid beta (Aβ) is considered a pathological hallmark of AD. The shorter Aβ 25 – 35 peptide fragments, formed from the amyloidogenic Aβ 1–40 peptide, plays a crucial role in the peptide’s neurotoxic activity (Pike et al., 2002). Acetylcholinesterase (AChE) as well as oxidative stress have shown to trigger Aβ formation and aggregation (Belluti et al., 2011; Cheignon et al., 2018). Previously, we synthesized multifunctional edaravone‐N‐benzyl pyridinium compounds that exhibited potent AChE inhibition and antioxidant activity as well as predicted to cross the blood‐brain barrier (BBB) using in silico models (Zondagh et al., 2020).
The pathological form of amyloid beta (Aβ) peptide is shown to be toxic to the mitochondria and i... more The pathological form of amyloid beta (Aβ) 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 Aβ (1-42)-treated human neuroblastoma (SH-SY5Y) cells. The SH-SY5Y cells were incubated with GMF and Aβ (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 Aβ (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 Aβ 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 Aβ. Upregulated GMF in the presence of Aβ 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.
Despite significant advancements in the field of molecular neurobiology especially neuroinflammat... more Despite significant advancements in the field of molecular neurobiology especially neuroinflammation and neurodegeneration, the highly complex molecular mechanisms underlying neurodegenerative diseases remain elusive. As a result, the development of the next generation neurotherapeutics has experienced a considerable lag phase. Recent advancements in the field of genome editing offer a new template for dissecting the precise molecular pathways underlying the complex neurodegenerative disorders. We believe that the innovative genome and transcriptome editing strategies offer an excellent opportunity to decipher novel therapeutic targets, develop novel neurodegenerative disease models, develop neuroimaging modalities, develop next-generation diagnostics as well as develop patient-specific precision-targeted personalized therapies to effectively treat neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, Frontotemporal dementia etc. Here, we review the latest developments in the field of CRISPR-mediated genome editing and provide unbiased futuristic insights regarding its translational potential to improve the treatment outcomes and minimize financial burden. However, despite significant advancements, we would caution the scientific community that since the CRISPR field is still evolving, currently we do not know the full spectrum of CRISPR-mediated side effects. In the wake of the recent news regarding CRISPR-edited human babies being born in China, we urge the scientific community to maintain high scientific and ethical standards and utilize CRISPR for developing in vitro disease in a dish model, in vivo testing in nonhuman primates and lower vertebrates and for the development of neurotherapeutics for the currently incurable neurodegenerative disorders.
Oxidative stress in the brain microvasculature is a common characteristic in models of cerebrovas... more Oxidative stress in the brain microvasculature is a common characteristic in models of cerebrovascular disease. It is, therefore, naturally prudent to hypothesize how antioxidant (AO) supplementation in brain vasculature, may be beneficial for combating cerebrovascular disease. Hyper doses of AOs in supplements and food, are commonly used as an ongoing remedial, 'over the counter,' treatment for most seasonal ailments. For the first time, this study reports the adverse effects of excess AOs on angiogenic properties of the blood-brain barrier (BBB) which have clinical implications. A medicinal tea, known as rooibos (Aspalathus linearis), commonly used in South Africa and marketed globally, for its prominent AO profile, demonstrated its effects on brain endothelial cellular (BEC) proliferation, toxicology, mitochondrial activity and permeability. In the current study, mouse BECs were seeded at passage numbers 30 to 40, at cell densities ranging from 10 3-10 6 cells/ml and were incubated at predetermined time intervals. Daily exposure to a selected concentration range of fermented A. linearis caused exacerbated effects with dose-related decreases in cellular proliferation, and unequivocally increased impermeability across an in vitro BBB model. No toxicity was observed for all selected concentrations of A. linearis. The data conclusively show that the use of excess AOs perturb BBB functionality and angiogenic properties, adversely implicating brain homeostasis. This suggests that excess AOs will lead to an impaired response to mechanical-induced injury and pathogenic infection of the BBB, resulting in compromised patient recovery.
(2022) Exosomes form tunneling nanotubes (TUNTs) in the blood-brain barrier: a nano-anatomical pe... more (2022) Exosomes form tunneling nanotubes (TUNTs) in the blood-brain barrier: a nano-anatomical perspective of barrier genesis.
The blood-brain barrier (BBB) is a robust interface between the blood and the central nervous sys... more The blood-brain barrier (BBB) is a robust interface between the blood and the central nervous system. Barrier type endothelium is able to limit paracellular (PC) movement, relegating molecular flux to the transendothelial pathways of brain endothelial cells (BECs). It is, therefore, apparent that any leakage via the PC shunts would effectively nullify the regulation of molecular flux across the transcellular pathways. The application of higher-resolution scanning electron microscopy (HR-SEM) illuminates the heterogenous, morphological profile that exists on the surface of BEC membranes and the relationship between these ultrastructures during the molecular construction of the PC space between adjacent BECs. In this study developing BEC monolayers were grown on mixed, cellulose esters insert membranes in a bicameral system. BEC monolayers were fixed in 2.5% glutaraldehyde, hydrated, critically dried, and sputter-coated, for imaging utilizing HR-SEM. This study, for the first time, sh...
Traumatic brain injury (TBI) is a major health problem in the United States, which affects about ... more 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 inflammat...
Mast cell activation plays an important role in stress-mediated disease pathogenesis. Chronic str... more Mast cell activation plays an important role in stress-mediated disease pathogenesis. Chronic stress cause or exacerbate aging and age-dependent neurodegenerative diseases. The severity of inflammatory diseases is worsened by the stress. Mast cell activation-dependent inflammatory mediators augment stress associated pain and neuroinflammation. Stress is the second most common trigger of headache due to mast cell activation. Alzheimer's disease (AD) is a progressive irreversible neurodegenerative disease that affects more women than men and woman's increased susceptibility to chronic stress could increase the risk for AD. Modern life-related stress, social stress, isolation stress, restraint stress, early life stress are associated with an increased level of neurotoxic beta amyloid (Aβ) peptide. Stress increases cognitive dysfunction, generates amyloid precursor protein (APP), hyperphosphorylated tau, neurofibrillary tangles (NFTs), and amyloid plaques (APs) in the brain. Stress-induced Aβ persists for years and generates APs even several years after the stress exposure. Stress activates hypothalamic-pituitary adrenal (HPA) axis and releases corticotropin-releasing hormone (CRH) from hypothalamus and in peripheral system, which increases the formation of Aβ, tau hyperphosphorylation, and blood-brain barrier (BBB) disruption in the brain. Mast cells are implicated in nociception and pain. Mast cells are the source and target of CRH and other neuropeptides that mediate neuroinflammation. Microglia express receptor for CRH that mediate neurodegeneration in AD. However, the exact mechanisms of how stress-mediated mast cell activation contribute to the pathogenesis of AD remains elusive. This mini-review highlights the possible role of stress and mast cell activation in neuroinflammation, BBB, and tight junction disruption and AD pathogenesis.
Probiotics in the Prevention and Management of Human Diseases, 2022
The immune system is a complex architecture of a collective and coordinated network regulated by ... more The immune system is a complex architecture of a collective and coordinated network regulated by various pathways to thermodynamically maintain immune homeostasis. The gut microbiota plays a pivotal role that offers significant stimuli (i.e., gut-brain, gut-lung, and gut-liver axis) for both innate and adaptive immunity, mediating immune and metabolic homeostasis. An intricate correlation between changes in the gut microbiota (dysbiosis) and common diseases/disorders have been attributed to the invasion of pathogens, constant use of antibiotics, and hypercytokinemia—a hallmark of immune homeostasis imbalance. These factors contribute to the severity of inflammatory diseases such as cardiovascular diseases, neurological disorders, and of late the coronavirus disease, Covid-19. Probiotics (Lactobacillus spp. and Bifidobacterium spp.) have been considered as alternative and/or adjuvant therapeutic in restoring the balance of gut microbiota for maintaining immune homeostasis and integrity. The probiotics catalyze dietary fibers and proteins to generate short-chain fatty acids and tryptophan to promote antiinflammatory cytokines, reduce epithelium permeability, reinforcing immunity in the gut mucosa, and regulating the systemic immune response. Herein, we review our overarching understanding of current applications of probiotics in amelioration of gut microbiome, and the improvement of gut barrier function and maintaining immune homeostasis. We also highlight clinical trials on probiotics with reported results for the treatment of inflammatory diseases. Additionally, the looming global Covid-19 pandemic makes it prudent to highlight the role of probiotics in both the innate and adaptive human immune responses, especially amid the Covid-19 vaccination paradigm.
Alcohol abuse is a growing crisis within South Africa, with severe health and socioeconomic impli... more Alcohol abuse is a growing crisis within South Africa, with severe health and socioeconomic implications. Alcohol compromises the function of the blood-brain barrier (BBB), and thus its ability to regulate the homeostatic environment of the CNS is interrupted. In this study, an in vitro model of the BBB was utilized to study the effects of selected concentrations of alcohol (25mM-200mM) and the ameliorating effects of fermented rooibos (Aspalathus linearis) (0.003125%-1%), in an attempt to reverse the harmful oxidative effects of alcohol. The literature clearly states that alcohol (ethanol) compromises the BBB by reactive oxygen species (ROS) production and, therefore, rooibos, a shrub high in antioxidants and widely utilized nationally, was added to alcohol-exposed mouse brain endothelial (bEnd5) cells with the view to reverse the alcohol-induced effects on the BBB model. Alcohol-treated (25mM-400mM) bEnd5 monolayers expressed no toxicity, however, cell numbers were significantly suppressed (P<0.0274). To validate this finding, the activity of the mitochondria was investigated in order to understand if the cell's metabolism was related to the decrease in cell division. Results showed that for both acute and chronic exposure there was a decrease in mitochondrial activity (MA) for a period of 24-48 hours, thereafter, the MA of the bEnd5 cells returned to normality. However, in experiments which chronically (600mM and 800mM) exposed cells to alcohol over a period of 96 hours, MA was suppressed and did not return to normal. ABSTRACT iv Fermented rooibos caused a biphasic response to cellular proliferation at 24-72 hours, where the lower concentrations (0.0625-0.125 %) caused an increase in cellular proliferation and the higher concentrations (0.5-1%) resulted in a relative decrease in cellular proliferation. The long-term effect, after acute exposure, however, resulted in cell suppression at 96 hours (P<0.0073). With respect to the MA, bEnd5 cells exposed to fermented rooibos showed that lower concentrations (0.003125-0.0125%) were suppressed at 24 hours and was elevated at 48 hours and 96 hours for all concentrations. The exception being the highest concentration (0.1%), which showed a depression in MA (P<0.05). Treating cells with both alcohol and rooibos, resulted in exacerbated suppressing of the MA. The physiological function of the BBB model was investigated by monitoring the permeability using transendothelial electrical resistance (TEER) studies and the in vitro model used in this study was endorsed for the first time using high resolution scanning electron microscopy. TEER indicated incidental changes in the permeability, only at 24 hours, for both acute and chronic exposure to alcohol and rooibos. A novel finding, within this study, was the increase in electrical resistance across the formation of the cell monolayer, after treatment with alcohol. The data lead to the hypothesis for the effect of ROS on resistivity and provides a rationale to explain the effects of combinatory treatments that were expected to ameliorate the negative effect of alcohol, however, this study showed synergistically negative effects on the bEnd5 cells.
Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biolog... more Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biological structures. Correct preparation of SEM samples can provide an unprecedented understanding of the nexus between cellular morphology and topography. This comparative study critically examines two coating methods for preparing biological samples for scanning electron microscopy, while also providing novel advice on how to prepare in vitro epithelial or endothelial samples for high-resolution scanning-electron microscopy (HR-SEM). Two obstacles often confront the biologist when investigating cellular structures grown under tissue culture conditions, namely., how to prepare and present the biological samples to the HR-SEM microscope without affecting topographical membrane and cellular structural alterations. Firstly, our use of the Millicell cellulose inserts on which to grow our cellular samples in preparation for HR-SEM is both novel and advantageous to comparing the permeability func...
The blood–brain barrier (BBB) is fundamental in maintaining central nervous system (CNS) homeosta... more The blood–brain barrier (BBB) is fundamental in maintaining central nervous system (CNS) homeostasis by regulating the chemical environment of the underlying brain parenchyma. Brain endothelial cells (BECs) constitute the anatomical and functional basis of the BBB. Communication between adjacent BECs is critical for establishing BBB integrity, and knowledge of its nanoscopic landscape will contribute to our understanding of how juxtaposed zones of tight-junction protein interactions between BECs are aligned. The review discusses and critiques types of nanostructures contributing to the process of BBB genesis. We further critically evaluate earlier findings in light of novel high-resolution electron microscopy descriptions of nanoscopic tubules. One such phenotypic structure is BEC cytoplasmic projections, which, early in the literature, is postulated as brain capillary endothelial cilia, and is evaluated and compared to the recently discovered nanotubules (NTs) formed in the paracel...
Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biolog... more Scanning electron microscopy (SEM) provides a technical platform for nanoscopic mapping of biological structures. Correct preparation of SEM samples can provide an unprecedented understanding of the nexus between cellular morphology and topography. This comparative study critically analyses two coating methods for investigating biological samples utilizing scanning electron microscopy. Biological material is often non-conducting, thermally sensitive and fragile and, therefore, needs to be fixed correctly and coated with thin conducting metal. This study aimed to compare biological sample coating modalities employed in the visualizing and analysis of texturized, membranous ultrastructures. The experimental model employed immortalized mouse brain endothelial cells (b.End5). The topographical structures of developing endothelial cells (ECs) were explored at high definition utilizing SEM as a tool to investigate the ultrastructural dynamics of membrane differentiation during monolayer development. Cell monolayers were prepared using two coating modalities, namely: carbon and gold:palladium (Au:Pd) sputter coating. SEM produced three-dimensional micrographs from which useful topographical cellular data could be extrapolated. We report on the novel ultrastructural membranous features of b.End5 cells. Furthermore, nanostructures were observably secreted on the BEC plasma membrane and are the nexus between direct cell-to-cell communication and cell monolayer development. The two coating methods display distinct differences in the topographical profile of developing BEC cytoarchitecture. SEM provides a glimpse of the ultrastructural behaviour of a differentiating cell surface topography. This study illuminates the relationship between generating highly definitive images and the appropriate coating method. The micrographical data suggests that Au:Pd sputter-coated samples generate descript imagery, providing useful information for profiling membrane nanostructures.
The brain capillary endothelium is highly regulatory, maintaining the chemical stability of the b... more The brain capillary endothelium is highly regulatory, maintaining the chemical stability of the brain’s microenvironment. The role of cytoskeletal proteins in tethering nanotubules (TENTs) during barrier-genesis was investigated using the established immortalized mouse brain endothelial cell line (bEnd5) as an in vitro blood-brain barrier (BBB) model. The morphology of bEnd5 cells was evaluated using both high-resolution scanning electron microscopy and immunofluorescence to evaluate treatment with depolymerizing agents Cytochalasin D for F-actin filaments and Nocodazole for α-tubulin microtubules. The effects of the depolymerizing agents were investigated on bEnd5 monolayer permeability by measuring the transendothelial electrical resistance (TEER). The data endorsed that during barrier-genesis, F-actin and α-tubulin play a cytoarchitectural role in providing both cell shape dynamics and cytoskeletal structure to TENTs forming across the paracellular space to provide cell-cell enga...
High-resolution electron microscopy (HREM) imaging of the in vitro blood-brain barrier (BBB), is ... more High-resolution electron microscopy (HREM) imaging of the in vitro blood-brain barrier (BBB), is a promising modality for investigating the dynamic morphological interplay underpinning BBB development. The successful establishment of BBB integrity is grounded in the brain endothelial cells (BEC’s) ability to occlude its paracellular spaces of brain capillaries through the expression of the intercellular tight junction (TJ) proteins. The impermeability of these paracellular spaces are crucial in the regulation of transcellular transport systems to achieve homeostasis of the central nervous system. To-date research describing morphologically, the dynamics by which TJ interaction is orchestrated to successfully construct a specialized barrier remains undescribed. In this study, the application of HREM illuminates the novel, dynamic and highly restrictive BEC paracellular pathway which is founded based on lateral membrane alignment which is the functional imperative for the mechanical j...
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