Infiltration by monocytes of the central nervous system and its role in multiple sclerosis: reflections on therapeutic strategies

Mononuclear macrophage infiltration in the central nervous system is a prominent feature of neuroinflammation. Recent studies on the pathogenesis and progression of multiple sclerosis have highlighted the multiple roles of mononuclear macrophages in the neuroinflammatory process. Monocytes play a significant role in neuroinflammation, and managing neuroinflammation by manipulating peripheral monocytes stands out as an effective strategy for the treatment of multiple sclerosis, leading to improved patient outcomes. This review outlines the steps involved in the entry of myeloid monocytes into the central nervous system that are targets for effective intervention: the activation of bone marrow hematopoiesis, migration of monocytes in the blood, and penetration of the blood–brain barrier by monocytes. Finally, we summarize the different monocyte subpopulations and their effects on the central nervous system based on phenotypic differences. As activated microglia resemble monocyte-derived macrophages, it is important to accurately identify the role of monocyte-derived macrophages in disease. Depending on the roles played by monocyte-derived macrophages at different stages of the disease, several of these processes can be interrupted to limit neuroinflammation and improve patient prognosis. Here, we discuss possible strategies to target monocytes in neurological diseases, focusing on three key aspects of monocyte infiltration into the central nervous system, to provide new ideas for the treatment of neurodegenerative diseases.

Gut flora in multiple sclerosis:implications for pathogenesis and treatment

Multiple sclerosis is an inflammatory disorder chara cterized by inflammation,demyelination,and neurodegeneration in the central nervous system.Although current first-line therapies can help manage symptoms and slow down disease progression,there is no cure for multiple sclerosis.The gut-brain axis refers to complex communications between the gut flo ra and the immune,nervous,and endocrine systems,which bridges the functions of the gut and the brain.Disruptions in the gut flora,termed dys biosis,can lead to systemic inflammation,leaky gut syndrome,and increased susceptibility to infections.The pathogenesis of multiple sclerosis involves a combination of genetic and environmental factors,and gut flora may play a pivotal role in regulating immune responses related to multiple scle rosis.To develop more effective therapies for multiple scle rosis,we should further uncover the disease processes involved in multiple sclerosis and gain a better understanding of the gut-brain axis.This review provides an overview of the role of the gut flora in multiple scle rosis.

Physical exercise and synaptic protection in human and pre-clinical models of multiple sclerosis

In multiple sclerosis,only immunomodulato ry and immunosuppressive drugs are recognized as disease-modifying therapies.Howeve r,in recent years,several data from pre-clinical and clinical studies suggested a possible role of physical exe rcise as disease-modifying therapy in multiple sclerosis.Current evidence is sparse and often conflicting,and the mechanisms underlying the neuroprotective and antinflammatory role of exercise in multiple sclerosis have not been fully elucidated.Data,mainly derived from pre-clinical studies,suggest that exe rcise could enhance longterm potentiation and thus neuroplasticity,could reduce neuroinflammation and synaptopathy,and dampen astrogliosis and microgliosis.In humans,most trials focused on direct clinical and MRI outcomes,as investigating synaptic,neuroinflammato ry,and pathological changes is not straightfo rward compared to animal models.The present review analyzed current evidence and limitations in research concerning the potential disease-modifying therapy effects of exercise in multiple sclerosis in animal models and human studies.

Examination of the Effective Factors on the Multiple Sclerosis Diseases

This study was an attempt to examine the effective factors of the Multiple Sclerosis diseases. The participants of the study were selected from among a total number of 45 men and women who were treated in a health center in Azarbayegan and Damavand in Iran. In order to study, the researchers applied various procedures to collect the data of the study. The participants were interviewed and filled out the questionnaires. After categorizing and classifying the collected information and data, it was processed and analyzed and the results are found. To test the research questions, a one-sample T-test was used to analyze the data. The role of hypo vitamin D as a possible risk factor for multiple sclerosis was reviewed. First, it was emphasized that hypo vitamin could be only one of the risk factors for multiple sclerosis and that numerous other environmental and genetic risk factors appear to interact and combine to trigger the disease. The main aim of this study was to examine the effective factors of Multiple Sclerosis diseases. The methodology of this research was to test the research questions;one-sample T-test was used to analyze the data. The findings of this study revealed that the factors of gender, cold weather, vitamin D deficiency, and age (between 30 - 59) were effective on the Multiple Sclerosis diseases.

Immunologic pathogenesis of multiple sclerosis

Multiple sclerosis （MS） is an autoimmune disease. The etiology and pathogenesis of MS remain unclear. At present, there are substantial evidences to support the hypothesis that genetics plays a crucial role. The people who have genetic predisposing genes easily develop immune-mediated disorder, probably in conjunction with environmental factors. The aim of this review is to describe recent observations regarding the immunologic pathogenesis of MS.

Neurogenic bowel dysfunction in patients with spinal cord injury, myelomeningocele, multiple sclerosis and Parkinson’s disease

Exciting new features have been described concerning neurogenic bowel dysfunction,including interactions between the central nervous system,the enteric nervous system,axonal injury,neuronal loss,neurotransmission of noxious and non-noxious stimuli,and the fields of gastroenterology and neurology.Patients with spinal cord injury,myelomeningocele,multiple sclerosis and Parkinson's disease present with serious upper and lower bowel dysfunctions characterized by constipation,incontinence,gastrointestinal motor dysfunction and altered visceral sensitivity.Spinal cord injury is associated with severe autonomic dysfunction,and bowel dysfunction is a major physical and psychological burden for these patients.An adult myelomeningocele patient commonly has multiple problems reflecting the multisystemic nature of the disease.Multiple sclerosis is a neurodegenerative disorder in which axonal injury,neuronal loss,and atrophy of the central nervous system can lead to permanent neurological damage and clinical disability.Parkinson's disease is a multisystem disorder involving dopaminergic,noradrenergic,serotoninergic and cholinergic systems,characterizedby motor and non-motor symptoms.Parkinson's disease affects several neuronal structures outside the substantia nigra,among which is the enteric nervous system.Recent reports have shown that the lesions in the enteric nervous system occur in very early stages of the disease,even before the involvement of the central nervous system.This has led to the postulation that the enteric nervous system could be critical in the pathophysiology of Parkinson's disease,as it could represent the point of entry for a putative environmental factor to initiate the pathological process.This review covers the data related to the etiology,epidemiology,clinical expression,pathophysiology,genetic aspects,gastrointestinal motor dysfunction,visceral sensitivity,management,prevention and prognosis of neurogenic bowel dysfunction patients with these neurological diseases.Embryological,morphological and experimental studies on animal models and humans are also taken into account.

Role of nuclear factor κB in multiple sclerosis and experimental autoimmune encephalomyelitis

The transcription factor nuclear factor κB（NF-κB） plays major roles in inflammatory diseases through regulation of inflammation and cell viability.Multiple sclerosis（MS） is a chronic inflammatory demyelinating and neurodegenerative disease of the central nervous system（CNS）.It has been shown that NF-κB is activated in multiple cell types in the CNS of MS patients,including T cells,microglia/macrophages,astrocytes,oligodendrocytes,and neurons.Interestingly,data from animal model studies,particularly studies of experimental autoimmune encephalomyelitis,have suggested that NF-κB activation in these individual cell types has distinct effects on the development of MS.In this review,we will cover the current literature on NF-κB and the evidence for its role in the development of MS and its animal model experimental autoimmune encephalomyelitis.

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.

The contribution of oligodendrocytes and oligodendrocyte progenitor cells to central nervous system repair in multiple sclerosis： perspectives for remyelination therapeutic strategies

Oligodencrocytes（OLs） are the main glial cells of the central nervous system involved in myelination of axons. In multiple sclerosis（MS）, there is an imbalance between demyelination and remyelination processes, the last one performed by oligodendrocyte progenitor cells（OPCs） and OLs, resulting into a permanent demyelination, axonal damage and neuronal loss. In MS lesions, astrocytes and microglias play an important part in permeabilization of blood-brain barrier and initiation of OPCs proliferation. Migration and differentiation of OPCs are influenced by various factors and the process is finalized by insufficient acummulation of OLs into the MS lesion. In relation to all these processes, the author will discuss the potential targets for remyelination strategies.

Microglia depletion as a therapeutic strategy:friend or foe in multiple sclerosis models?

M ultiple sclerosis is a chro nic central nervous system demyelinating disease whose onset and progression are driven by a combination of immune dysregulation,genetic predisposition,and environmental fa ctors.The activation of microglia and astrocytes is a key player in multiple sclerosis immunopathology,playing specific roles associated with anatomical location and phase of the disease and controlling demyelination and neurodegeneration.Even though reactive mic roglia can damage tissue and heighten deleterious effects and neurodegeneration,activated microglia also perform neuroprotective functions such as debris phagocytosis and growth fa ctor secretion.Astrocytes can be activated into pro-inflammato ry phenotype A1 through a mechanism mediated by activated neuroinflammatory microglia,which could also mediate neurodegeneration.This A1 phenotype inhibits oligodendrocyte prolife ration and differe ntiation and is toxic to both oligodendrocytes and neurons.Howeve r,astroglial activation into phenotype A2 may also take place in response to neurodegeneration and as a protective mechanism.A variety of animal models mimicking specific multiple sclerosis features and the associated pathophysiological processes have helped establish the cascades of events that lead to the initiation,progression,and resolution of the disease.The colonystimulating facto r-1 receptor is expressed by myeloid lineage cells such as peripheral monocytes and macrophages and central nervous system microglia.Importantly,as microglia development and survival critically rely on colony-stimulating factor-1 receptor signaling,colony-stimulating factor-1 receptor inhibition can almost completely eliminate microglia from the brain.In this context,the present review discusses the impact of microglial depletion through colo ny-stimulating factor-1 receptor inhibition on demyelination,neurodegeneration,astroglial activation,and behavior in different multiple sclerosis models,highlighting the diversity of microglial effects on the progression of demyelinating diseases and the strengths and weaknesses of microglial modulation in therapy design.

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.

Cognitive impairment in multiple sclerosis: lessons from cerebrospinal fluid biomarkers

Cognitive impairment is a common clinical manifestation of multiple sclerosis,but its pathophysiology is not completely understood.White and grey matter injury together with synaptic dysfunction do play a role.The measurement of biomarkers in the cerebrospinal fluid and the study of their association with cognitive impairment may provide interesting in vivo evidence of the biological mechanisms underlying multiple sclerosis-related cognitive impairment.So far,only a few studies on this topic have been published,giving interesting results that deserve further investigation.Cerebrospinal fluid biomarkers of different pathophysiological mechanisms seem to reflect different neuropsychological patterns of cognitive deficits in multiple sclerosis.The aim of this review is to discuss the studies that have correlated cerebrospinal fluid markers of immune,glial and neuronal pathology with cognitive impairment in multiple sclerosis.Although preliminary,these findings suggest that cerebrospinal fluid biomarkers show some correlation with cognitive performance in multiple sclerosis,thus providing interesting insights into the mechanisms underlying the involvement of specific cognitive domains.

The role of fibronectin in multiple sclerosis and the effect of drug delivery across the blood-brain barrier

Remyelination failure is one of the main characteristics of multiple sclerosis and is potentially correlated with disease progression.Previous research has shown that the extracellular matrix is associated with remyelination failure because remodeling of the matrix often fails in both chronic and progressive multiple sclerosis.Fibronectin aggregates are assembled and persistently exist in chronic multiple sclerosis,thus inhibiting remyelination.Although many advances have been made in the mechanisms and treatment of multiple sclerosis,it remains very difficult for drugs to reach pathological brain tissues;this is due to the complexity of brain structure and function,especially the existence of the blood-brain barrier.Therefore,herein,we review the effects of fibronectin aggregates on multiple sclerosis and the efficacy of different forms of drug delivery across the blood-brain barrier in the treatment of this disease.

CDP-choline to promote remyelination in multiple sclerosis:the need for a clinical trial

Multiple sclerosis is a multifactorial chronic inflammatory disease of the central nervous system that leads to demyelination and neuronal cell death,resulting in functional disability.Remyelination is the natural repair process of demyelination,but it is often incomplete or fails in multiple sclerosis.Available therapies reduce the inflammatory state and prevent clinical relapses.However,therapeutic approaches to increase myelin repair in humans are not yet available.The substance cytidine-5′-diphosphocholine,CDP-choline,is ubiquitously present in eukaryotic cells and plays a crucial role in the synthesis of cellular phospholipids.Regenerative properties have been shown in various animal models of diseases of the central nervous system.We have already shown that the compound CDPcholine improves myelin regeneration in two animal models of multiple sclerosis.However,the results from the animal models have not yet been studied in patients with multiple sclerosis.In this review,we summarise the beneficial effects of CDP-choline on biolipid metabolism and turnover with regard to inflammatory and regenerative processes.We also explain changes in phospholipid and sphingolipid homeostasis in multiple sclerosis and suggest a possible therapeutic link to CDP-choline.

Mechanism of Erhuang capsule for treatment of multiple sclerosis

Erhuang capsule, a typical formula based on traditional Chinese medicine theory, is widely used to ameliorate multiple sclerosis, inflammation and side effects of glucocortJcoid treatment. Oligodendrocyte precursor cells are neural stem cells that are important for myelin repair and regeneration. In the present study, Erhuang capsule effectively improved clinical symptoms and neurological function scores, reduced mortality and promoted recovery of neurological functions of mice with experimental autoimmune encephalomyelitis. The mechanism of action involved significant increases in oligodendrocyte precursor cell proliferation in specific regions of the brain and spinal cord, increased oligodendrocyte lineage gene 2 expression and enhanced oligodendrocyte precursor cell differentiation.

Correlations Between Serum Uric Acid Level and Disease Activity,Intrathecal Inflammation Reactivity in Patients with Multiple Sclerosis

Objective To explore the correlations between serum uric acid （HA） levels and the clinical and cerebrospinal fluid （CSF） parameters of multiple sclerosis （MS）. Methods The medical reports of 47 MS patients admitted to Peking Union Medical College Hospi- tal during 2008 and 2010 were reviewed. And 49 age- and gender-matched cerebral infarction patients were enrolled as control. The mean serum HA level of the MS patients was compared with that of the control group. The correlations between the HA levels and the clinical parameters including gender, disease duration, relapse rate, and disease disabilities as assessed by the Expanded Disability Status Scale score, were explored. Forty-one patients had CSF examinations. The correlations between the IdA levels and the CSF parameters reflecting inflammation and tissue damage, including CSF protein, white blood cell count, oligoclonal band, 24-hour IgG index, and myelin basic protein, were also investigated. Results The mean serum HA level in the MS patients was lower than that in the control group （247.75 ± 52.59 jamol/L vs. 277.94 ± 74.33 pmol/L, P=0.025） and inversely correlated with the relapse rate （P=0.049）. MS patients with lower serum UA levels tended to have higher white blood cell counts and myelin basic protein level. But there was no correlation between CSF protein levels （r=0.165, P=0.273）, white blood cell counts （r=-0.051, P=0.732）, IgG index （r =0. 045, P=0.802）, or myelin basic protein level （r =-0.248, P=0.145） and the serum UA level, respectively. Conclusion In MS patients, UA levels might partly reflect the extent of disability and inflammation.

Correlation between white matter damage and gray matter lesions in multiple sclerosis patients

We observed the characteristics of white matter fibers and gray matter in multiple sclerosis patients, to identify changes in diffusion tensor imaging fractional anisotropy values following white matter fiber injury. We analyzed the correlation between fractional anisotropy values and changes in whole-brain gray matter volume. The participants included 20 patients with relapsing-remitting multiple sclerosis and 20 healthy volunteers as controls. All subjects underwent head magnetic resonance imaging and diffusion tensor imaging. Our results revealed that fractional anisotropy values decreased and gray matter volumes were reduced in the genu and splenium of corpus callosum, left anterior thalamic radiation, hippocampus, uncinate fasciculus, right corticospinal tract, bilateral cingulate gyri, and inferior longitudinal fasciculus in multiple sclerosis patients. Gray matter volumes were significantly different between the two groups in the right frontal lobe（superior frontal, middle frontal, precentral, and orbital gyri）, right parietal lobe（postcentral and inferior parietal gyri）, right temporal lobe（caudate nucleus）, right occipital lobe（middle occipital gyrus）, right insula, right parahippocampal gyrus, and left cingulate gyrus. The voxel sizes of atrophic gray matter positively correlated with fractional anisotropy values in white matter association fibers in the patient group. These findings suggest that white matter fiber bundles are extensively injured in multiple sclerosis patients. The main areas of gray matter atrophy in multiple sclerosis are the frontal lobe, parietal lobe, caudate nucleus, parahippocampal gyrus, and cingulate gyrus. Gray matter atrophy is strongly associated with white matter injury in multiple sclerosis patients, particularly with injury to association fibers.

Chemotactic signaling and beyond: link between interleukin-16 and axonal degeneration in multiple sclerosis

Multiple sclerosis（MS）is a progressive inflammatory,and chronic demyelinating,neurodegenerative disease of central nervous system（CNS）.Autoimmune responses to myelin and other CNS antigens mediated by cluster of differentiation 4（CD4＋）T cells are critical for initiation and progression of disease.Migration of autoimmune T cells from the peripheral lymph organs into CNS parenchyma leads to inflammation,demyelination and damage of axonal cytoskeleton, which manifest in decreased impulse conduction velocity of motor and sensory nerves. Myelin and axonal pathology causes motor, sensory and autonomic nerve dysfunction, including optic nerve damage leading to double or distorted vision; paresis and paralysis of extremities, painful sensations, and bladder sphincter dysfunction, manifested as bladder incontinence. Gray matter pa- thology in cortical and subcortical regions, including cerebellum and hippocampus underlies cognitive and behavioral dysfunction consisting of memory deficits, depression, and ataxic gait and tremor.

Hyperperfusion of Multiple Sclerosis Plaques Characterized by 3D FSE Arterial Spin Labelling

MULTIPLE sclerosis （MS） is a common inflammatory demyelinating disorder of central nervous system, and the disease burder could be well evaluated by conven-tional magnetic resonance imaging （MRI）,1 including T2-weighted, fluid-attenuatd inversion recovery, and postcontrast Tl-weighted sequences. 2 We investigated the perfusion state of MS plaques using brain perfusion imaging in a 12-year-old boy with MS.

Perspectives on neuroreparative therapies for treating multiple sclerosis

A need to develop neuroreparative therapies for multiple sclerosis（MS）：MS is the most common neurological disease of young Caucasian adults.This disease is characterized by inflammatory demyelination of the central nervous system（CNS）and involves activation of key inflammatory cells of both the adaptive and innate immune systems,which target and destroy both myelin and oligodendrocytes （the my- elin-forming glial cells in the CNS）. Key pathological features of the disease include autoimmune inflammation, axonal degeneration and demyelination （myelin loss）, latter of which can occur in both white matter and gray matter. The key cell type damaged in MS is oligodendrocytes, which produce the insulating myelin sheath surrounding many axons in the CNS. Myelin and oligodendrocytes have critical roles.