Tuftsin Combines With Remyelinating Therapy and Improves Outcomes in Models of CNS Demyelinating Disease

Chronic psychosocial stress triggers microglial-/macrophage-induced inflammatory responses leading to neuronal dysfunction and depressive-related behavior

Chronic environmental stress and traumatic social experiences induce maladaptive behavioral changes and is a risk factor for major depressive disorder (MDD) and various anxiety-related psychiatric disorders. Clinical studies and animal models of chronic stress have reported that symptom severity is correlated with innate immune responses and upregulation of neuroinflammatory cytokine signaling in brain areas implicated in mood regulation (mPFC; medial Prefrontal Cortex). Despite increasing evidence implicating impairments of neuroplasticity and synaptic signaling deficits into the pathophysiology of stress-related mental disorders, how microglia may modulate neuronal homeostasis in response to chronic stress has not been defined. Here, using the repeated social defeat stress (RSDS) mouse model we demonstrate that microglial-induced inflammatory responses are regulating neuronal plasticity associated with psychosocial stress. Specifically, we show that chronic stress induces a rapid activation and proliferation of microglia as well as macrophage infiltration in the mPFC, and these processes are spatially related to neuronal activation. Moreover, we report a significant association of microglial inflammatory responses with susceptibility or resilience to chronic stress. In addition, we find that exposure to chronic stress exacerbates phagocytosis of synaptic elements and deficits in neuronal plasticity. Importantly, by utilizing two different CSF1R inhibitors (the brain penetrant PLX5622 and the non-penetrant PLX73086) we highlight a crucial role for microglia (and secondarily macrophages) in catalyzing the pathological manifestations linked to psychosocial stress in the mPFC and the resulting behavioral deficits usually associated with depression.

The Pathological Activation of Microglia Is Modulated by Sexually Dimorphic Pathways

Microglia are the primary immunocompetent cells of the central nervous system (CNS). Their ability to survey, assess and respond to perturbations in their local environment is critical in their role of maintaining CNS homeostasis in health and disease. Microglia also have the capability of functioning in a heterogeneous manner depending on the nature of their local cues, as they can become activated on a spectrum from pro-inflammatory neurotoxic responses to anti-inflammatory protective responses. This review seeks to define the developmental and environmental cues that support microglial polarization towards these phenotypes, as well as discuss sexually dimorphic factors that can influence this process. Further, we describe a variety of CNS disorders including autoimmune disease, infection, and cancer that demonstrate disparities in disease severity or diagnosis rates between males and females, and posit that microglial sexual dimorphism underlies these differences. Understanding the mechanism behind differential CNS disease outcomes between men and women is crucial in the development of more effective targeted therapies.

Therapeutic effect of combination vitamin D3 and siponimod on remyelination and modulate microglia activation in cuprizone mouse model of multiple sclerosis

Stimulation of remyelination is critical for the treatment of multiple sclerosis (MS) to alleviate symptoms and protect the myelin sheath from further damage. The current study aimed to investigate the possible therapeutic effects of combining vitamin D3 (Vit D3) and siponimod (Sipo) on enhancing remyelination and modulating microglia phenotypes in the cuprizone (CPZ) demyelination mouse model. The study was divided into two stages; demyelination (first 5 weeks) and remyelination (last 4 weeks). In the first 5 weeks, 85 mice were randomly divided into two groups, control (n = 20, standard rodent chow) and CPZ (n = 65, 0.3% CPZ mixed with chow for 6 weeks, followed by 3 weeks of standard rodent chow). At week 5, the CPZ group was re-divided into four groups (n = 14) for remyelination stages; untreated CPZ (0.2 ml of CMC orally), CPZ+Vit D3 (800 IU/kg Vit D3 orally), CPZ+Sipo (1.5 mg/kg Sipo orally), and CPZ+Vit D3 (800 IU/kg Vit D3) + Sipo (1.5 mg/kg Sipo orally). Various behavioral tasks were performed to evaluate motor performance. Luxol Fast Blue (LFB) staining, the expression level of myelin basic protein (MBP), and M1/M2 microglia phenotype genes were assessed in the corpus callosum (CC). The results showed that the combination of Vit D3 and Sipo improved behavioral deficits, significantly promoted remyelination, and modulated expression levels of microglia phenotype genes in the CC at early and late remyelination stages. These results demonstrate for the first time that a combination of Vit D3 and Sipo can improve the remyelination process in the cuprizone (CPZ) mouse model by attenuating the M1 microglia phenotype. This may help to improve the treatment of MS patients.

Remyelination in Multiple Sclerosis: Findings in the Cuprizone Model

Remyelination therapies, which are currently under development, have a great potential to delay, prevent or even reverse disability in multiple sclerosis patients. Several models are available to study the effectiveness of novel compounds in vivo, among which is the cuprizone model. This model is characterized by toxin-induced demyelination, followed by endogenous remyelination after cessation of the intoxication. Due to its high reproducibility and ease of use, this model enjoys high popularity among various research and industrial groups. In this review article, we will summarize recent findings using this model and discuss the potential of some of the identified compounds to promote remyelination in multiple sclerosis patients.

Tuftsin: A Natural Molecule Against SARS-CoV-2 Infection

Coronavirus disease 2019 (COVID-19) continuously progresses despite the application of a variety of vaccines. Therefore, it is still imperative to find effective ways for treating COVID-19. Recent studies indicate that NRP1, an important receptor of the natural peptide tuftsin (released from IgG), facilitates SARS-CoV-2 infection. Here, we found 91 overlapping genes between tuftsin targets and COVID-19-associated genes. We have demonstrated that tuftsin could also target ACE2 and exert some immune-related functions. Molecular docking results revealed that tustin could combine with ACE2 and NRP1 in stable structures, and their interacted regions cover the binding surfaces of S1-protein with the two receptors. Using surface plasmon resonance (SPR) analysis, we confirmed that tuftsin can bind ACE2 and NRP1 directly. Importantly, using SPR-based competition assay we have shown here that tuftsin effectively prevented the binding of SARS-CoV-2 S1-protein to ACE2. Collectively, these data suggest that tuftsin is an attractive therapeutic candidate against COVID-19 and can be considered for translational as well as clinical studies.

2Receptor Specific Ligand conjugated Nanocarriers: an Effective Strategy for Targeted Therapy of Tuberculosis

Tuberculosis (TB) is an ancient chronic disease caused by the bacillus Mycobacterium tuberculosis, which has affected mankind for more than 4,000 years. Compliance with the standard conventional treatment can assure recovery from tuberculosis, but emergence of drug resistant strains pose a great challenge for effective management of tuberculosis. The process of discovery and development of new therapeutic entities with better specificity and efficacy is unpredictable and time consuming. Hence, delivery of pre-existing drugs with improved targetability is the need of the hour. Enhanced delivery and targetability can ascertain improved bioavailability, reduced toxicity, decreased frequency of dosing and therefore better patient compliance. Nanoformulations are being explored for effective delivery of therapeutic agents, however optimum specificity is not guaranteed. In order to achieve specificity, ligands specific to receptors or cellular components of macrophage and Mycobacteria can be conjugatedto nanocarriers. This approach can improve localization of existing drug molecules at the intramacrophageal site where the parasites reside, improve targeting to the unique cell wall structure of Mycobacterium or improve adhesion to epithelial surface of intestine or alveolar tissue (lectins). Present review focuses on the investigation of various ligands like Mannose, Mycolic acid, Lectin, Aptamers etc. installed nanocarriers that are being envisaged for targeting antitubercular drugs.

Cannabidiol Displays Proteomic Similarities to Antipsychotics in Cuprizone-Exposed Human Oligodendrocytic Cell Line MO3.13

Cannabidiol, a compound of Cannabis sativa, has been proposed as an alternative treatment of schizophrenia. Preclinical and clinical data have suggested that cannabidiol shares more similarity with atypical antipsychotics than typical, both of which are customarily used to manage schizophrenia symptoms. While oligodendrocytes are known to be relevant targets of antipsychotics, the biochemical knowledge in this regard is still limited. Here we evaluated the molecular pathways modulated by cannabidiol compared to the antipsychotics clozapine (atypical) and haloperidol (typical), additionally evaluating the effects of benztropine, a muscarinic receptor antagonist that displays a protective effect in oligodendrocytes and myelination. For this purpose, we employed nano-chromatography coupled with mass spectrometry to investigate the proteomic response to these drugs both in healthy oligodendrocytic cells and in a cuprizone-based toxicity model, using the human oligodendrocyte precursor cell line MO3.13. Cannabidiol shares similarities of biochemical pathways with clozapine and benztropine, in agreement with other studies that indicated an atypical antipsychotic profile. All drugs tested affected metabolic and gene expression pathways and cannabidiol, benztropine, and clozapine modulated cell proliferation and apoptosis when administered after cuprizone-induced toxicity. These general pathways are associated with cuprizone-induced cytotoxicity in MO3.13 cells, indicating a possible proteomic approach when acting against the toxic effects of cuprizone. In conclusion, although modeling oligodendrocytic cytotoxicity with cuprizone does not represent the entirety of the pathophysiology of oligodendrocyte impairments, these results provide insight into the mechanisms associated with the effects of cannabidiol and antipsychotics against cuprizone toxicity, offering new directions of study for myelin-related processes and deficits.

Small compounds mimicking the adhesion molecule L1 improve recovery in a zebrafish demyelination model

Demyelination leads to a loss of neurons, which results in, among other consequences, a severe reduction in locomotor function, and underlies several diseases in humans including multiple sclerosis and polyneuropathies. Considerable clinical progress has been made in counteracting demyelination. However, there remains a need for novel methods that reduce demyelination while concomitantly achieving remyelination, thus complementing the currently available tools to ameliorate demyelinating diseases. In this study, we used an established zebrafish demyelination model to test selected compounds, following a screening in cell culture experiments and in a mouse model of spinal cord injury that was aimed at identifying beneficial functions of the neural cell adhesion molecule L1. In comparison to mammalian nervous system disease models, the zebrafish allows testing of potentially promotive compounds more easily than what is possible in mammals. We found that our selected compounds tacrine and duloxetine significantly improved remyelination in the peripheral and central nervous system of transgenic zebrafish following pharmacologically induced demyelination. Given that both molecules are known to positively affect functions other than those related to L1 and in other disease contexts, we propose that their combined beneficial function raises hope for the use of these compounds in clinical settings.

Guanabenz modulates microglia and macrophages during demyelination

Multiple sclerosis (MS) is an autoimmune disease characterized by infiltration of peripheral immune cells into the central nervous system, demyelination, and neuronal damage. There is no cure for MS, but available disease-modifying therapies can lessen severity and delay progression. However, current therapies are suboptimal due to adverse effects. Here, we investigate how the FDA-approved antihypertensive drug, guanabenz, which has a favorable safety profile and was recently reported to enhance oligodendrocyte survival, exerts effects on immune cells, specifically microglia and macrophages. We first employed the experimental autoimmune encephalomyelitis (EAE) model and observed pronounced immunomodulation evident by a reduction in pro-inflammatory microglia and macrophages. When guanabenz was administered in the cuprizone model, in which demyelination is less dependent upon immune cells, we did not observe improvements in remyelination, oligodendrocyte numbers, and effects on microglial activation were less dramatic. Thus, guanabenz may be a promising therapeutic to minimize inflammation without exerting severe off-target effects.

Possible Correlation between Cholinergic System Alterations and Neuro/Inflammation in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune and demyelinating disease of the central nervous system. Although the etiology of MS is still unknown, both genetic and environmental factors contribute to the pathogenesis of the disease. Acetylcholine participates in the modulation of central and peripheral inflammation. The cells of the immune system, as well as microglia, astrocytes and oligodendrocytes express cholinergic markers and receptors of muscarinic and nicotinic type. The role played by acetylcholine in MS has been recently investigated. In the present review, we summarize the evidence indicating the cholinergic dysfunction in serum and cerebrospinal fluid of relapsing-remitting (RR)-MS patients and in the brains of the MS animal model experimental autoimmune encephalomyelitis (EAE). The correlation between the increased activity of the cholinergic hydrolyzing enzymes acetylcholinesterase and butyrylcholinesterase, the reduced levels of acetylcholine and the increase of pro-inflammatory cytokines production were recently described in immune cells of MS patients. Moreover, the genetic polymorphisms for both hydrolyzing enzymes and the possible correlation with the altered levels of their enzymatic activity have been also reported. Finally, the changes in cholinergic markers expression in the central nervous system of EAE mice in peak and chronic phases suggest the involvement of the acetylcholine also in neuro-inflammatory processes.

Strategies for Neuroprotection in Multiple Sclerosis and the Role of Calcium

Calcium ions are vital for maintaining the physiological and biochemical processes inside cells. The central nervous system (CNS) is particularly dependent on calcium homeostasis and its dysregulation has been associated with several neurodegenerative disorders including Parkinson’s disease (PD), Alzheimer’s disease (AD) and Huntington’s disease (HD), as well as with multiple sclerosis (MS). Hence, the modulation of calcium influx into the cells and the targeting of calcium-mediated signaling pathways may present a promising therapeutic approach for these diseases. This review provides an overview on calcium channels in neurons and glial cells. Special emphasis is put on MS, a chronic autoimmune disease of the CNS. While the initial relapsing-remitting stage of MS can be treated effectively with immune modulatory and immunosuppressive drugs, the subsequent progressive stage has remained largely untreatable. Here we summarize several approaches that have been and are currently being tested for their neuroprotective capacities in MS and we discuss which role calcium could play in this regard.

Protective effects of pharmacological therapies in animal models of multiple sclerosis: a review of studies 2014-2019

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. The disability caused by inflammatory demyelination clinically dominates the early stages of relapsing-remitting MS and is reversible. Once there is considerable loss of axons, MS patients enter a secondary progressive stage. Disease-modifying drugs currently in use for MS suppress the immune system and reduce relapse rates but are not effective in the progressive stage. Various animal models of MS (mostly mouse and rat) have been established and proved useful in studying the disease process and response to therapy. The experimental autoimmune encephalomyelitis animal studies reviewed here showed that a chronic progressive disease can be induced by immunization with appropriate amounts of myelin oligodendrocyte glycoprotein together with mycobacterium tuberculosis and pertussis toxin in Freund's adjuvant. The clinical manifestations of autoimmune encephalomyelitis disease were prevented or reduced by treatment with certain pharmacological agents given prior to, at, or after peak disease, and the agents had protective effects as shown by inhibiting demyelination and damage to neurons, axons and oligodendrocytes. In the cuprizone-induced toxicity animal studies, the pharmacological agents tested were able to promote remyelination and increase the number of oligodendrocytes when administered therapeutically or prophylactically. A monoclonal IgM antibody protected axons in the spinal cord and preserved motor function in animals inoculated with Theiler's murine encephalomyelitis virus. In all these studies the pharmacological agents were administered singly. A combination therapy may be more effective, especially using agents that target neuroinflammation and neurodegeneration, as they may exert synergistic actions.

MicroRNAs as disease progression biomarkers and therapeutic targets in experimental autoimmune encephalomyelitis model of multiple sclerosis

Multiple sclerosis is an autoimmune neurodegenerative disease of the central nervous system characterized by pronounced inflammatory infiltrates entering the brain, spinal cord and optic nerve leading to demyelination. Focal demyelination is associated with relapsing-remitting multiple sclerosis, while progressive forms of the disease show axonal degeneration and neuronal loss. The tests currently used in the clinical diagnosis and management of multiple sclerosis have limitations due to specificity and sensitivity. MicroRNAs (miRNAs) are dysregulated in many diseases and disorders including demyelinating and neuroinflammatory diseases. A review of recent studies with the experimental autoimmune encephalomyelitis animal model (mostly female mice 6–12 weeks of age) has confirmed miRNAs as biomarkers of experimental autoimmune encephalomyelitis disease and importantly at the pre-onset (asymptomatic) stage when assessed in blood plasma and urine exosomes, and spinal cord tissue. The expression of certain miRNAs was also dysregulated at the onset and peak of disease in blood plasma and urine exosomes, brain and spinal cord tissue, and at the post-peak (chronic) stage of experimental autoimmune encephalomyelitis disease in spinal cord tissue. Therapies using miRNA mimics or inhibitors were found to delay the induction and alleviate the severity of experimental autoimmune encephalomyelitis disease. Interestingly, experimental autoimmune encephalomyelitis disease severity was reduced by overexpression of miR-146a, miR-23b, miR-497, miR-26a, and miR-20b, or by suppression of miR-182, miR-181c, miR-223, miR-155, and miR-873. Further studies are warranted on determining more fully miRNA profiles in blood plasma and urine exosomes of experimental autoimmune encephalomyelitis animals since they could serve as biomarkers of asymptomatic multiple sclerosis and disease course. Additionally, studies should be performed with male mice of a similar age, and with aged male and female mice.

A Convenient Synthetic Method to Improve Immunogenicity of Mycobacterium tuberculosis Related T-Cell Epitope Peptides

Epitopes from different proteins expressed by Mycobacterium tuberculosis (Rv1886c, Rv0341, Rv3873) were selected based on previously reported antigenic properties. Relatively short linear T-cell epitope peptides generally have unordered structure, limited immunogenicity, and low in vivo stability. Therefore, they rely on proper formulation and on the addition of adjuvants. Here we report a convenient synthetic route to induce a more potent immune response by the formation of a trivalent conjugate in spatial arrangement. Chemical and structural characterization of the vaccine conjugates was followed by the study of cellular uptake and localization. Immune response was assayed by the measurement of splenocyte proliferation and cytokine production, while vaccine efficacy was studied in a murine model of tuberculosis. The conjugate showed higher tendency to fold and increased internalization rate into professional antigen presenting cells compared to free epitopes. Cellular uptake was further improved by the incorporation of a palmitoyl group to the conjugate and the resulted pal-A(P)I derivative possessed an internalization rate 10 times higher than the free epitope peptides. Vaccination of CB6F1 mice with free peptides resulted in low T-cell response. In contrast, significantly higher T-cell proliferation with prominent expression of IFN-γ, IL-2, and IL-10 cytokines was measured for the palmitoylated conjugate. Furthermore, the pal-A(P)I conjugate showed relevant vaccine efficacy against Mycobacterium tuberculosis infection.

Glial cells as therapeutic targets in progressive multiple sclerosis

Introduction: Multiple sclerosis is a serious demyelinating disease of the central nervous system (CNS) with treatments generally restricted to immunosuppression to reduce attack rate and for symptom management. Glial cells may be useful targets for future CNS regenerative therapies to reverse disease. Areas covered: In this review, the authors cover currently available multiple sclerosis treatments and examine potential upcoming therapies targeting glial cells. The potential for new therapeutic approaches in the treatment of progressive multiple sclerosis is examined. Expert opinion: Microglia, astrocytes, and oligodendrocytes are each promising targets for the disease-altering treatment of multiple sclerosis. Though challenging, the opportunities presented have great potential for CNS regeneration and further investigation of glial cells in therapy is warranted. Patient-specific combinatorial therapy targeting the three glial cell types is expected to be the future of MS treatment.