Expression of the neuroprotective protein aryl hydrocarbon receptor nuclear translocator 2 correlates with neuronal stress and disability in models of multiple sclerosis

Oxidative stress involvement in the molecular pathogenesis and progression of multiple sclerosis: a literature review

Multiple sclerosis (MS) is an autoimmune debilitating disease of the central nervous system caused by a mosaic of interactions between genetic predisposition and environmental factors. The pathological hallmarks of MS are chronic inflammation, demyelination, and neurodegeneration. Oxidative stress, a state of imbalance between the production of reactive species and antioxidant defense mechanisms, is considered one of the key contributors in the pathophysiology of MS. This review is a comprehensive overview of the cellular and molecular mechanisms by which oxidant species contribute to the initiation and progression of MS including mitochondrial dysfunction, disruption of various signaling pathways, and autoimmune response activation. The detrimental effects of oxidative stress on neurons, oligodendrocytes, and astrocytes, as well as the role of oxidants in promoting and perpetuating inflammation, demyelination, and axonal damage, are discussed. Finally, this review also points out the therapeutic potential of various synthetic antioxidants that must be evaluated in clinical trials in patients with MS.

Nose to brain delivery of Astragaloside IV by β-Asarone modified chitosan nanoparticles for multiple sclerosis therapy

Multiple sclerosis (MS), an autoimmune disease, has been considered an inflammatory disorder of the central nervous system (CNS) with demyelination and axonal damage. Although there are certain first-line therapies to treat MS, their unsatisfactory efficacy is partly due to the limited CNS access after systemic administration. Besides, there is an urgent need to treat MS by enhancing remyelination or neuroprotection, or dampen the activity of microglia. Astragaloside IV (ASI) bears anti-inflammatory, antioxidant, remyelination and neuroprotective activity. While its poor permeability, relatively high molecular weight and low lipophilicity restrict it to reach the brain. Therefore, β-asarone modified ASI loaded chitosan nanoparticles (ASI-βCS-NP) were prepared to enhance the nose-to-brain delivery and therapeutic effects of ASI on EAE mice. The prepared ASI-βCS-NP showed mean size of about 120 nm, and zeta potential from +19 to +25 mV. DiR-βCS-NP was confirmed with good nose-to-brain targeting ability. After intranasal administration, the ASI-βCS-NP significantly reduced behavioral scores, decreased weight loss, suppressed inflammatory infiltration and astrocyte/microglial activation, reduced demyelination and increased remyelination on a mice EAE model. Our findings indicate that ASI-βCS-NP may be a potent treatment for MS after nose-to-brain drug delivery.

Potential Molecular Mechanism of Upregulated Aryl Hydrocarbon Receptor Nuclear Translocator 2 in Nasopharyngeal Carcinoma

Background. Currently, the benefits of nasopharyngeal carcinoma (NPC) therapy are limited, and it is necessary to further explore possible therapeutic targets. Aryl hydrocarbon receptor nuclear translocator 2 (ARNT2) has been extensively studied in other cancer species, but little has been explored in NPC. The aim of this study was to verify the expression level of ARNT2 and its underlying mechanism in NPC. Methods. Datasets containing ARNT2 mRNA expression levels were retrieved and collected from various databases to explore the expression status of ARNT2 in NPC. ARNT2-related coexpressed genes, differential expressed genes, and target genes were obtained for functional enrichment analysis. The potential target gene of ARNT2 and their regulatory relationship were studied through ChIP-seq data. CIBERSORTx was used to assess the immune infiltration of NPC, and the association with ARNT2 expression was calculated through correlation analysis. Results. ARNT2 was upregulated and possessed an excellent discriminatory capability in NPC samples. ARNT2 positively correlated target genes were clustered in pathways in cancer, while negatively correlated target genes were enriched in immune-related pathway. The ChIP-seq information of ARNT2 and histone showed that prostaglandin-endoperoxide synthase 2 (PTGS2) was a potential target gene of ARNT2. CIBERSORTx revealed the immunity status in NPC, and ARNT2 expression was correlated with infiltration of five immune cells. Conclusions. ARNT2 is overexpressed in NPC and may regulate PTGS2 to participate in the cancer process. ARNT2 serves as a key oncogenic target in NPC patients.

Diffusion basis spectrum imaging measures anti-inflammatory and neuroprotective effects of fingolimod on murine optic neuritis

OBJECTIVE

To prospectively determine whether diffusion basis spectrum imaging (DBSI) detects, differentiates and quantitates coexisting inflammation, demyelination, axonal injury and axon loss in mice with optic neuritis (ON) due to experimental autoimmune encephalomyelitis (EAE), and to determine if DBSI accurately measures effects of fingolimod on underlying pathology.

METHODS

EAE was induced in 7-week-old C57BL/6 female mice. Visual acuity (VA) was assessed daily to detect onset of ON after which daily oral-treatment with either fingolimod (1 mg/kg) or saline was given for ten weeks. In vivo DBSI scans of optic nerves were performed at baseline, 2-, 6- and 10-weeks post treatment. DBSI-derived metrics including restricted isotropic diffusion tensor fraction (putatively reflecting cellularity), non-restricted isotropic diffusion tensor fraction (putatively reflecting vasogenic edema), DBSI-derived axonal volume, axial diffusivity, λ_∥ (putatively reflecting axonal integrity), and increased radial diffusivity, λ_⊥ (putatively reflecting demyelination). Mice were killed immediately after the last DBSI scan for immunohistochemical assessment.

RESULTS

Optic nerves of fingolimod-treated mice exhibited significantly better (p < 0.05) VA than saline-treated group at each time point. During ten-week of treatment, DBSI-derived non-restricted and restricted-isotropic-diffusion-tensor fractions, and axonal volumes were not significantly different (p > 0.05) from the baseline values in fingolimod-treated mice. Transient DBSI-λ_∥ decrease and DBSI-λ_⊥ increase were detected during Fingolimod treatment. DBSI-derived metrics assessed in vivo significantly correlated (p < 0.05) with the corresponding histological markers.

CONCLUSION

DBSI was used to assess changes of the underlying optic nerve pathologies in EAE mice with ON, exhibiting great potential as a noninvasive outcome measure for monitoring disease progression and therapeutic efficacy for MS.

Post-stroke depression: Chaos to exposition

Cerebral ischemia contributes to significant disabilities worldwide, impairing cognitive function and motor coordination in affected individuals. Stroke has severe neuropsychological outcomes, the major one being a stroke. Stroke survivors begin to show symptoms of depression within a few months of the incidence that overtime progresses to become a long-term ailment. As the pathophysiology for the progression of the disease is multifactorial and complex, it limits the understanding of the disease mechanism completely. Meta-analyses and randomized clinical trials have shown that intervening early with tricyclic antidepressants and selective serotonin receptor inhibitors can be effective. However, these pharmacotherapies possess several limitations that have given rise to newer approaches such as brain stimulation, psychotherapy and rehabilitation therapy, which in today's time are gaining attention for their beneficial results in post-stroke depression (PSD). The present review highlights numerous factors like lesion location, inflammatory mediators and genetic abnormalities that play a crucial role in the development of depression in stroke patients. Further, we have also discussed various mechanisms involved in post-stroke depression (PSD) and strategies for early detection and diagnosis using biomarkers that may revolutionize treatment for the affected population. Towards the end, along with the preclinical scenario, we have also discussed the various treatment approaches like pharmacotherapy, traditional medicines, psychotherapy, electrical stimulation and microRNAs being utilized for effectively managing PSD.

Essential Functions of the Transcription Factor Npas4 in Neural Circuit Development, Plasticity, and Diseases

Signaling from the synapse to nucleus is mediated by the integration and propagation of both membrane potential changes (postsynaptic potentials) and intracellular second messenger cascades. The electrical propagation of postsynaptic potentials allows for rapid neural information processing, while propagating second messenger pathways link synaptic activity to the transcription of genes required for neuronal survival and adaptive changes (plasticity) underlying circuit formation and learning. The propagation of activity-induced calcium signals to the cell nucleus is a major synapse-to-nucleus communication pathway. Neuronal PAS domain protein 4 (Npas4) is a recently discovered calcium-dependent transcription factor that regulates the activation of genes involved in the homeostatic regulation of excitatory–inhibitory balance, which is critical for neural circuit formation, function, and ongoing plasticity, as well as for defense against diseases such as epilepsy. Here, we summarize recent findings on the neuroprotective functions of Npas4 and the potential of Npas4 as a therapeutic target for the treatment of acute and chronic diseases of the central nervous system.

Oligodendrocyte ARNT2 expression is altered in models of MS

Objective

We examined expression of aryl hydrocarbon receptor nuclear translocator 2 (ARNT2), a basic-loop-helix transcription factor implicated in neuronal development and axonal health, in oligodendrocyte (OL) cultures and over the course of chronic experimental autoimmune encephalomyelitis (EAE), the murine model of multiple sclerosis (MS).

Methods

We assessed OL ARNT2 expression in EAE compared with sham-immunized controls and also in OL primary cultures and over the course of dibutyryl cyclic adenosine monophosphate (dbcAMP)-mediated maturation of the immortalized Oli-neu cell line. We also tested the functional role of ARNT2 in influencing OL characteristics using small interfering RNA (siRNA).

Results

ARNT2 is localized to Olig2⁺ cells in healthy spinal cord gray and white matter. Despite a significant expansion of Olig2⁺ cells in the white matter at peak disease, ARNT2 is reduced by almost half in OLs, along with a reduction in the percentage of ARNT2⁺/Olig2⁺ cells. Mature OLs in mixed cortical cultures or OLs matured from embryonic progenitors express negligible ARNT2. Similarly, Oli-neu cells express high levels of ARNT2, which are reduced following dbcAMP maturation. siRNA-mediated knockdown of ARNT2 affected OL viability, which led to an enrichment of myelin-producing OLs.

Conclusion

The analysis of ARNT2 expression in OLs demonstrates that OL ARNT2 expression is altered in EAE and during OL maturation. Findings point to ARNT2 as an important mediator of OL viability and differentiation and warrant further characterization as a target for intervention in demyelinating disorders such as MS.

Neuroprotective effects of anthocyanins and its major component cyanidin-3-O-glucoside (C3G) in the central nervous system: An outlined review

Anthocyanins, a class of water soluble flavonoids extracted from plants like berries and soybean seed, have been shown to display obvious anti-oxidative, anti-inflammatory, and anti-apoptotic activities. They are recommended as a supplementation for prevention and/or treatment of disorders ranging from cardiovascular disease, metabolic syndrome, and cancer. In the central nervous system (CNS), anthocyanins and its major component cyanidin-3-O-glucoside (C3G) have been reported to produce preventive and/or therapeutic activities in a wide range of disorders, such as cerebral ischemia, Alzheimer's disease, Parkinson's disease, multiple sclerosis, and glioblastoma. Both anthocyanins and C3G can also affect some important processes in aging, including neuronal apoptosis and death as well as learning and memory impairment. Further, the anthocyanins and C3G have been shown to prevent neuro-toxicities induced by different toxic factors, such as lipopolysaccharide, hydrogen peroxide, ethanol, kainic acid, acrolein, glutamate, and scopolamine. Mechanistic studies have shown that inhibition of oxidative stress and neuroinflammation are two critical mechanisms by which anthocyanins and C3G produce protective effects in CNS disorder prevention and/or treatment. Other mechanisms, including suppression of c-Jun N-terminal kinase (JNK) activation, amelioration of cellular degeneration, activation of the brain-derived neurotrophic factor (BDNF) signaling, and restoration of Ca²⁺ and Zn²⁺ homeostasis, may also mediate the neuroprotective effects of anthocyanins and C3G. In this review, we summarize the pharmacological effects of anthocyanins and C3G in CNS disorders as well as their possible mechanisms, aiming to get a clear insight into the role of anthocyanins in the CNS.

Dysregulation of miR-142 results in anxiety-like behaviors following single prolonged stress

Posttraumatic stress disorder (PTSD) is a prevalent mental disorder that is classified as a trauma- and stressor-related disorder. While numerous epigenetic factors are related to the risk for PTSD, the precise mechanisms underlying this disorder remain unclear. However, accumulating evidence has demonstrated that dysregulation of microRNAs is involved in stress-related psychiatric disorders, resulting in anxiety-like behavior, memory-related deficits and aberrant neuronal plasticity. Here, rats exposed to single prolonged stress showed increased microRNA-142-5p levels in the amygdala and a concurrent reduction in the levels of its predicted target Npas4, an activity-regulated transcription factor, which was implicated in stress-related psychopathologies. In addition, the inhibition of microRNA-142 following exposure to single prolonged stress exhibited decreased anxiety-like behaviors and memory deficits, as well as increased expression of Npas4 and BDNF. Furthermore, a dual-luciferase reporter assay indicated that Npas4 was a direct downstream target of miR-142. Taken together, these data suggest that miR-142 may play a key role in the pathogenesis of stress-related psychiatric disorders.