Epigenetic Alterations in Alzheimer's Disease: Impact on Insulin Signaling and Advanced Drug Delivery Systems.

Alzheimer's disease (AD) is a neurodegenerative condition that predominantly affects the hippocampus and the entorhinal complex, leading to memory lapse and cognitive impairment. This can have a negative impact on an individual's behavior, speech, and ability to navigate their surroundings. AD is one of the principal causes of dementia. One of the most accepted theories in AD, the amyloid ß (Aß) hypothesis, assumes that the buildup of the peptide Aß is the root cause of AD. Impaired insulin signaling in the periphery and central nervous system has been considered to have an effect on the pathophysiology of AD. Further, researchers have shifted their focus to epigenetic mechanisms that are responsible for dysregulating major biochemical pathways and intracellular signaling processes responsible for directly or indirectly causing AD. The prime epigenetic mechanisms encompass DNA methylation, histone modifications, and non-coding RNA, and are majorly responsible for impairing insulin signaling both centrally and peripherally, thus leading to AD. In this review, we provide insights into the major epigenetic mechanisms involved in causing AD, such as DNA methylation and histone deacetylation. We decipher how the mechanisms alter peripheral insulin signaling and brain insulin signaling, leading to AD pathophysiology. In addition, this review also discusses the need for newer drug delivery systems for the targeted delivery of epigenetic drugs and explores targeted drug delivery systems such as nanoparticles, vesicular systems, networks, and other nano formulations in AD. Further, this review also sheds light on the future approaches used for epigenetic drug delivery.

In-silico lead identification of the pan-mutant IDH1 and IDH2 inhibitors to target glioblastoma.

Glioblastoma (GBM) is an aggressive malignant type of brain tumor. Targeting one single intracellular pathway might not alleviate the disease, rather it activates the other molecular pathways that lead to the worsening of the disease condition. Therefore, in this study, we attempted to target both isocitrate dehydrogenase 1 (IDH1) and IDH2, which are one of the most commonly mutated proteins in GBM and other cancer types. Here, standard precision and extra precision docking, IFD, MM-GBSA, QikProp, and molecular dynamics (MD) simulation were performed to identify the potential dual inhibitor for IDH1 and IDH2 from the enamine database containing 59,161 ligands. Upon docking the ligands with IDH1 (PDB: 6VEI) and IDH2 (PDB: 6VFZ), the top eight ligands were selected, based on the XP Glide score. These ligands produced favourable MMGBSA scores and ADME characteristics. Finally, the top four ligands 12953, 44825, 51295, and 53210 were subjected to MD analysis. Interestingly, 53210 showed maximum interaction with Gln 277 for 99% in IDH1 and Gln 316 for 100% in IDH2, which are the crucial amino acids for the inhibitory function of IDH1 and IDH2 to target GBM. Therefore, the present study attempts to identify the novel molecules which could possess a pan-inhibitory action on both IDH1 and IDH that could be crucial in the management of GBM. Yet further evaluation involving in vitro and in vivo studies is warranted to support the data in our current study.Communicated by Ramaswamy H. Sarma.

Evaluating the Role of N-Acetyl-L-Tryptophan in the Aß 1-42-Induced Neuroinflammation and Cognitive Decline in Alzheimer's Disease.

Alzheimer's disease (AD), a neurodegenerative condition previously known to affect the older population, is also now seen in younger individuals. AD is often associated with cognitive decline and neuroinflammation elevation primarily due to amyloid ß (Aß) accumulation. Multiple pathological complications in AD call for therapies with a wide range of neuroprotection. Our study aims to evaluate the effect of N-acetyl-L-tryptophan (NAT) in ameliorating the cognitive decline and neuroinflammation induced by Aß 1-42 oligomers and to determine the therapeutic concentration of NAT in the brain. We administered Aß 1-42 oligomers in rats via intracerebroventricular (i.c.v.) injection to induce AD-like conditions. The NAT-treated animals lowered the cognitive decline in the Morris water maze characterized by shorter escape latency and increased path efficiency and platform entries. Interestingly, the hippocampus and frontal cortex showed downregulation of tumor necrosis factor, interleukin-6, and substance P levels. NAT treatment also reduced acetylcholinesterase activity and total and phosphorylated nuclear factor kappa B and Tau levels. Lastly, we observed upregulation of cAMP response element-binding protein 1 (CREB1) signaling. Surprisingly, our HPLC method was not sensitive enough to detect the therapeutic levels of NAT in the brain, possibly due to NAT concentrations being below the lowest limit of quantification of our validated method. To summarize, the administration of NAT significantly lowered cognitive decline, neuroinflammatory pathways, and Tau protein and triggered the upregulation of CREB1 signaling, suggesting its neuroprotective role in AD-like conditions.

Repressor Element-1 Binding Transcription Factor (REST) as a Possible Epigenetic Regulator of Neurodegeneration and MicroRNA-Based Therapeutic Strategies.

Neurodegenerative disorders (NDD) have grabbed significant scientific consideration due to their fast increase in prevalence worldwide. The specific pathophysiology of the disease and the amazing changes in the brain that take place as it advances are still the top issues of contemporary research. Transcription factors play a decisive role in integrating various signal transduction pathways to ensure homeostasis. Disruptions in the regulation of transcription can result in various pathologies, including NDD. Numerous microRNAs and epigenetic transcription factors have emerged as candidates for determining the precise etiology of NDD. Consequently, understanding by what means transcription factors are regulated and how the deregulation of transcription factors contributes to neurological dysfunction is important to the therapeutic targeting of pathways that they modulate. RE1-silencing transcription factor (REST) also named neuron-restrictive silencer factor (NRSF) has been studied in the pathophysiology of NDD. REST was realized to be a part of a neuroprotective element with the ability to be tuned and influenced by numerous microRNAs, such as microRNAs 124, 132, and 9 implicated in NDD. This article looks at the role of REST and the influence of various microRNAs in controlling REST function in the progression of Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD) disease. Furthermore, to therapeutically exploit the possibility of targeting various microRNAs, we bring forth an overview of drug-delivery systems to modulate the microRNAs regulating REST in NDD.

Rodent models for dry eye syndrome: Standardization using benzalkonium chloride and scopolamine hydrobromide.

Dry eye disease is a highly prevalent ocular condition that significantly affects the quality of life and presents a major challenge in ophthalmology. Animal models play a crucial role in investigating the pathophysiology and developing effective treatments. The goal of this study was to compare and standardize two dry eye disease rodent models and explore their recovery aspects. We have standardized benzalkonium chloride and scopolamine-induced dry eye disease models which represents two different classes of the dry eye i.e., evaporative dry eye and aqueous deficient dry eye, respectively. After the development of dry eye conditions, a self-recovery period of seven days was granted to assess the reversal of the induced changes. The dry eye condition was assessed by measuring tear volume, corneal slit lamp imaging, and histological examination of the cornea, the lacrimal and the harderian gland. The study indicated the development of chronic inflammation of the cornea and lacrimal gland in the case of benzalkonium after five days of the treatment, while the scopolamine treated group showed chronic inflammation of the lacrimal gland after five days and corneal inflammation after seven days of administration. The recovery study suggested that after discontinuation of inducing agent, the dry eye symptoms were still persistent suggesting the utility of the model in evaluating dry eye treatments. The study highlights the comparative changes in both models along with recovery which can serve as a base for drug discovery and development against dry eye disease.

Dopaminergic Signaling as a Plausible Modulator of Astrocytic Toll-Like Receptor 4: A Crosstalk between Neuroinflammation and Cognition.

Neuroinflammation is one of the major pathological factors leading to Alzheimer's disease (AD). The role of microglial cells in neuroinflammation associated with AD has been known for a long time. Recently, astrocytic inflammatory responses have been linked to the neuronal degeneration and pathological development of AD. Lipopolysaccharide (LPS) and Amyloid Beta (Aß) activate astrocytes and microglial cells via toll-like 4 (TLR4) receptors leading to neuroinflammation. Reactive (activated) astrocytes mainly comprising of A1 astrocytes (A1s) are involved in neuroinflammation, while A2 astrocytes (A2s) possess neuroprotective activity. Studies link low dopamine (DA) levels during the early stages of neurodegenerative disorders with its anti-inflammatory and immuoregulatory properties. DA mediates neuroprotection via inhibition of the A1 astrocytic pathway through blockade of NF-kB and nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 3 (NLRP3); and promotion of A2 astrocytic pathways leading to the formation of neurotrophic factors like BDNF and GDNF. In this current review, we have discussed the crosstalk between the dopaminergic system in astrocytic TLR4 and NF-kB in addition to NLRP3 inflammasome in the modulation of neuroinflammatory pathologies in cognitive deficits.

Avanafil mediated dual inhibition of IKKß and TNFR1 in an experimental paradigm of Alzheimer's disease: in silico and in vivo approach.

In Alzheimer's disease pathology, inhibitors of nuclear factor kappa-ß kinase subunit ß (IKKB) and Tumor necrosis factor receptor 1 (TNFR1) signaling are linked to neuroinflammation-mediated cognitive decline. We explored the role of a phosphodiesterase 5 inhibitor (PDE5I) with dual antagonistic action on IKKB and TNFR1 to inhibit nuclear factor kappa B (NF-kB) and curb neuroinflammation. In the in silico approach, the FDA-approved Zinc 15 library was docked with IKKB and TNFR1. The top compound with dual antagonistic action on IKKB and TNFR1 was selected based on bonding and non-bonding interactions. Further, induced fit docking (IFD), molecular mechanics-generalized Born and surface area (MMGBSA), and molecular dynamic studies were carried out and evaluated. Lipopolysaccharide (LPS) administration caused a neuroinflammation-mediated cognitive decline in mice. Two doses of avanafil were administered for 28 days while LPS was administered for 10 days. Morris water maze (MWM) along with the passive avoidance test (PAT) were carried out. Concurrently brain levels of inflammatory markers, oxidative parameters, amyloid beta (Aß), IKKB and NF-kB levels were estimated. Avanafil produced good IKKB and TNFR1 binding ability. It interacted with crucial inhibitory amino acids of IKKB and TNFR1. MD analysis predicted good stability of avanafil with TNFR1 and IKKB. Avanafil 6 mg/kg could significantly improve performance in MWM, PAT and oxidative parameters and reduce Aß levels and inflammatory markers. As compared to avanafil 3 mg/kg, 6 mg/kg dose was found to exert better efficacy against elevated Aß , neuroinflammatory cytokines and oxidative markers while improving behavioural parameters.Communicated by Ramaswamy H. Sarma.

Expediting Molecular Translational Approach of Mesenchymal Stem Cells in COVID-19 Treatment.

Coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in late 2019 with severe respiratory failure and organ damage that later appeared as a pandemic disease. Worldwide, people's mental and physical health and socioeconomic have been affected. Currently, with no promising treatment for COVID-19, the existing anti-viral drugs and vaccines are the only hope to boost the host immune system to reduce morbidity and mortality rate. Unfortunately, several reports show that people who are partially or fully vaccinated are still susceptible to COVID-19 infection. Evidence suggests that COVID-19 immunopathology may include dysregulation of macrophages and monocytes, reduced type 1 interferons (IFN-1), and enhanced cytokine storm that results in hypersecretion of proinflammatory cytokines, capillary leak syndrome, intravascular coagulation, and acute respiratory distress syndrome (ARDS) ultimately leading to the worsening of patient's condition and death in most cases. The recent use of cell-based therapies such as mesenchymal stem cells (MSCs) for critically ill COVID-19 patients has been authorized by the Food and Drug Administration (FDA) to alleviate cytokine release syndrome. It protects the alveolar epithelial cells by promoting immunomodulatory action and secreting therapeutic exosomes to improve lung function and attenuate respiratory failure. As a result, multiple clinical trials have been registered using MSCs that aim to use various cell sources, and dosages to promote safety and efficacy against COVID-19 infection. In this review, the possibility of using MSCs in COVID-19 treatment and its associated challenges in their use have been briefly discussed.

Astrocytic MicroRNAs and Transcription Factors in Alzheimer's Disease and Therapeutic Interventions.

Astrocytes are important for maintaining cholesterol metabolism, glutamate uptake, and neurotransmission. Indeed, inflammatory processes and neurodegeneration contribute to the altered morphology, gene expression, and function of astrocytes. Astrocytes, in collaboration with numerous microRNAs, regulate brain cholesterol levels as well as glutamatergic and inflammatory signaling, all of which contribute to general brain homeostasis. Neural electrical activity, synaptic plasticity processes, learning, and memory are dependent on the astrocyte-neuron crosstalk. Here, we review the involvement of astrocytic microRNAs that potentially regulate cholesterol metabolism, glutamate uptake, and inflammation in Alzheimer's disease (AD). The interaction between astrocytic microRNAs and long non-coding RNA and transcription factors specific to astrocytes also contributes to the pathogenesis of AD. Thus, astrocytic microRNAs arise as a promising target, as AD conditions are a worldwide public health problem. This review examines novel therapeutic strategies to target astrocyte dysfunction in AD, such as lipid nanodiscs, engineered G protein-coupled receptors, extracellular vesicles, and nanoparticles.

Astrocytic Glutamatergic Transmission and Its Implications in Neurodegenerative Disorders.

Several neurodegenerative disorders involve impaired neurotransmission, and glutamatergic neurotransmission sets a prototypical example. Glutamate is a predominant excitatory neurotransmitter where the astrocytes play a pivotal role in maintaining the extracellular levels through release and uptake mechanisms. Astrocytes modulate calcium-mediated excitability and release several neurotransmitters and neuromodulators, including glutamate, and significantly modulate neurotransmission. Accumulating evidence supports the concept of excitotoxicity caused by astrocytic glutamatergic release in pathological conditions. Thus, the current review highlights different vesicular and non-vesicular mechanisms of astrocytic glutamate release and their implication in neurodegenerative diseases. As in presynaptic neurons, the vesicular release of astrocytic glutamate is also primarily meditated by calcium-mediated exocytosis. V-ATPase is crucial in the acidification and maintenance of the gradient that facilitates the vesicular storage of glutamate. Along with these, several other components, such as cystine/glutamate antiporter, hemichannels, BEST-1, TREK-1, purinergic receptors and so forth, also contribute to glutamate release under physiological and pathological conditions. Events of hampered glutamate uptake could promote inflamed astrocytes to trigger repetitive release of glutamate. This could be favorable towards the development and worsening of neurodegenerative diseases. Therefore, across neurodegenerative diseases, we review the relations between defective glutamatergic signaling and astrocytic vesicular and non-vesicular events in glutamate homeostasis. The optimum regulation of astrocytic glutamatergic transmission could pave the way for the management of these diseases and add to their therapeutic value.

In silico screening of neurokinin receptor antagonists as a therapeutic strategy for neuroinflammation in Alzheimer's disease.

Neuroinflammation is one of the detrimental factors leading to neurodegeneration in Alzheimer's disease (AD) and other neurodegenerative disorders. The activation of microglial neurokinin 1 receptor (NK1R) by substance P (SP) enhances neuroinflammation which is mediated through pro-inflammatory pathways involving NFkB, ERK1/2, and P38 and thus projects the scope and importance of NK1R inhibitors. Emphasizing the inhibitory role of N Acetyl L Tryptophan (L-NAT) on NK1R, this is the first in silico screening of L-NAT mediated NK1R antagonism. In addition, FDA- approved ligands were screened for their potential NK1R antagonism. The L-NAT was docked in XP (Extra Precision) mode while FDA-approved ligands were screened in HTVS (High Throughput Virtual Screening), SP (Standard Precision), and XP mode onto NK1R (PDB:6HLO). The L-NAT and top 3 compounds FDA-approved ligands were subjected to molecular dynamics (MD) studies of 100 ns simulation time. The XP docking of L-NAT, indacaterol, modafinil and alosetron showed good docking scores. Their 100 ns MD showed brief protein-ligand interactions with an acceptable root mean square deviation. The protein-ligand contacts depicted pi-pi stacking, pi-cation, hydrogen bonds, and water bridges with the amino acids necessary for NK1R inhibition. The variable colour band intensities on the protein-ligand contact map indicated their binding strength with amino acids. The molecular mechanics/generalized born surface area (MM-GBSA) scores suggested favourable binding free energy of the complexes. Thus, our study predicted the ability of L-NAT, indacaterol, modafinil, and alosetron as capable NK1R inhibitors that can aid to curb neuroinflammation in conditions of AD which could be further ascertained in subsequent studies.

Dialogue between Neuroinflammation and Neurodegenerative Diseases in COVID-19.

It has now been almost a year since the emergence of the deadly SARS-CoV-2 with millions of people losing their lives due to resultant COVID-19. Apart from the well-known consequences of respiratory illnesses, it has even effortlessly mapped itself into the nervous system through routes like blood, CSF, neurons, and olfactory cells. Interestingly, the interaction of SARS-CoV-2 with the nervous system cells like neurons, microglia, and astrocytes has been a factor to worsen COVID-19 through its neuroinflammatory actions. The release of cytokines due to astrocyte and microglial activation could progress towards the most anticipated cytokine storm proving to be detrimental in the management of COVID-19. Such hyper-inflammatory conditions could make the BBB vulnerable, encouraging excessive viral particles into the CNS, leading to further neurodegenerative pathologies like Alzheimer's disease, Parkinson's disease, Creutzfeldt-Jakob disease, and Multiple Sclerosis. Excessive neuroinflammation and neurodegeneration being the anticipated root causes of these multiple conditions, it is also essential to look into other factors that synergistically enhance the worsening of these diseases in COVID-19 patients for which additional studies are essential.

JAK-STAT Pathway Inhibition and their Implications in COVID-19 Therapy.

As the incidence of COVID-19 increases with time, more and more efforts are made to pave a way out for the therapeutic strategies to deal with the disease progression. Inflammation being a significant influencer in COVID-19 patients, it drives our focus onto the signaling cascades of the JAK/STAT pathway. JAK phosphorylation mediated by cytokine receptor activation leads to phosphorylation of STATs that translocate into the nucleus to translate for inflammatory mediators. The SARS-CoV-2 structural proteins like spike, nucleocapsid, membrane and envelope proteins along with the non- structural proteins 1-16 including proteases like 3CL pro and PLpro promote its entry and survival in hosts. The SARS-CoV-2 infection triggers inflammation via the JAK/STAT pathway leading to recruitment of pneumocytes, endothelial cells, macrophages, monocytes, lymphocytes, natural killer cells and dendritic cells progressing towards cytokine storm. This produces various inflammatory markers in the host that determine the disease severity. The JAK/STAT signaling also mediates immune responses via B cell and T cell differentiation.With an attempt to reduce excessive inflammation, JAK/STAT inhibitors like Ruxolitinib, Baricitinib, Tofacitinib have been employed that mediate its actions via suppressors of cytokine signaling, cytokine inducible SH2 containing protein, Protein inhibitor of activated STAT and protein tyrosine phosphatases. Even though they are implicated with multiple adverse effects, the regulatory authorities have supported its use, and numerous clinical trials are in progress to prove their safety and efficacy. On the contrary, the exact mechanism of JAK/STAT inhibition at molecular levels remains speculative for which further investigations are required.

Involvement of the nervous system in COVID-19: The bell should toll in the brain.

The world is fuming at SARS-CoV-2 for being the culprit for causing the devastating COVID-19, claiming millions of lives across the globe in the form of respiratory disorders. But lesser known are its effects on the CNS that are slowly surfacing in the worldwide population. Our review illustrates findings that claim SARS-CoV-2's arrival onto the ACE2 receptors of neuronal and glial cells mainly via CSF, olfactory nerve, trigeminal nerve, neuronal dissemination, and hematogenous pathways. The role of SARS-CoV-2 structural proteins in its smooth viral infectivity of the host cannot be ignored, especially the spike proteins that mediate spike attachment and host membrane fusion. Worth mentioning the nucleocapsid, envelope, and membrane proteins make the proliferation of SARS-CoV-2 much simpler than expected in spreading infection. This has led to catastrophic conditions like seizures, Guillain-Barré syndrome, viral encephalitis, meningoencephalitis, acute cerebrovascular disease, and respiratory failures. Placing a magnifying lens on the lesser-explored CNS consequences of COVID-19, we attempt to shift the focus of our readers onto the new supporting threats to which further studies are needed.

Hydroxychloroquine in COVID-19: Potential Mechanism of Action Against SARS-CoV-2.

PURPOSE OF REVIEW: The rapid spread of virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has turned out to be a global emergency. Symptoms of this viral infection, coronavirus disease 2019 (COVID-19), include mild infections of the upper respiratory tract, viral pneumonia, respiratory failure, multiple organ failure and death. Till date, no drugs have been discovered to treat COVID-19 patients, and therefore, a considerable amount of interest has been shown in repurposing the existing drugs. RECENT FINDINGS: Out of these drugs, chloroquine (CQ) and hydroxychloroquine (HCQ) have demonstrated positive results indicating a potential antiviral role against SARS-CoV-2. Its mechanism of action (MOA) includes the interference in the endocytic pathway, blockade of sialic acid receptors, restriction of pH mediated spike (S) protein cleavage at the angiotensin-converting enzyme 2 (ACE2) binding site and prevention of cytokine storm. Unfortunately, its adverse effects like gastrointestinal complications, retinopathy and QT interval prolongation are evident in treated COVID-19 patients. Yet, multiple clinical trials have been employed in several countries to evaluate its ability in turning into a needed drug in this pandemic. SUMMARY: This review attempts to summarize the MOA of CQ/HCQ and its side effects. The existing literature hints that till date, the role of CQ/HCQ in COVID-19 may be sceptical, and further studies are warranted for obtaining a therapeutic option that could be effectively used across the world to rise out from this pandemic.

Zinc as a plausible epigenetic modulator of glioblastoma multiforme.

Glioblastoma Multiforme (GBM) is an aggressive brain tumor (WHO grade 4 astrocytoma) with unknown causes and is associated with a reduced life expectancy. The available treatment options namely radiotherapy, surgery and chemotherapy have failed to improve life expectancy. Out of the various therapeutic approaches, epigenetic therapy is one of the most studied. Epigenetic therapy is involved in the effective treatment of GBM by inhibiting DNA methyltransferase, histone deacetylation and non-coding RNA. It also promotes the expression of the tumor suppressor gene and is involved in the suppression of the oncogene. Various targets are being studied to implement proper epigenetic regulation to control GBM effectively. Zinc is one of the micronutrients which is considered to maintain epigenetic regulation by promoting the proper DNA folding, protecting genetic material from the oxidative damage and controlling the enzyme activation involved in the epigenetic regulation. Here, we are discussing the importance of zinc in regulating the epigenetic modifications and assessing its role in glioblastoma research. The discussion also highlights the importance of artificial intelligence using epigenetics for envisaging the glioma progression, diagnosis and its management.

Structural Proteins in Severe Acute Respiratory Syndrome Coronavirus-2.

What began with a sign of pneumonia-related respiratory disorders in China has now become a pandemic named by WHO as Covid-19 known to be caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). The SARS-CoV-2 are newly emerged ß coronaviruses belonging to the Coronaviridae family. SARS-CoV-2 has a positive viral RNA genome expressing open reading frames that code for structural and non-structural proteins. The structural proteins include spike (S), nucleocapsid (N), membrane (M), and envelope (E) proteins. The S1 subunit of S protein facilitates ACE2 mediated virus attachment while S2 subunit promotes membrane fusion. The presence of glutamine, asparagine, leucine, phenylalanine and serine amino acids in SARS-CoV-2 enhances ACE2 binding. The N protein is composed of a serine-rich linker region sandwiched between N Terminal Domain (NTD) and C Terminal Domain (CTD). These terminals play a role in viral entry and its processing post entry. The NTD forms orthorhombic crystals and binds to the viral genome. The linker region contains phosphorylation sites that regulate its functioning. The CTD promotes nucleocapsid formation. The E protein contains a NTD, hydrophobic domain and CTD which form viroporins needed for viral assembly. The M protein possesses hydrophilic C terminal and amphipathic N terminal. Its long-form promotes spike incorporations and the interaction with E facilitates virion production. As each protein is essential in viral functioning, this review describes the insights of SARS-CoV-2 structural proteins that would help in developing therapeutic strategies by targeting each protein to curb the rapidly growing pandemic.