CXCL1 regulation of oligodendrocyte progenitor cell migration is independent of calcium signaling

Ursolic acid derivative UAOS-Na treats experimental autoimmune encephalomyelitis by immunoregulation and protecting myelin

Introduction

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Ursolic acid (UA) can be used in the MS treatment with anti-inflammatory and neuroprotective activities. However, UA is insoluble in water, which may affect its medication effectiveness. In our previous study, UAOS-Na, a water-soluble derivative of UA was obtained. In this study, we evaluated the pharmacological effects and explored its underlying mechanism of UAOS-Na on experimental autoimmune encephalomyelitis (EAE).

Methods

Firstly, the pharmacodynamics of UAOS-Na was investigated in EAE and Cuprizone-induced mice. And then the possible mechanisms were investigated by TMT proteomics and verified by in vitro and in vivo experiments.

Results

UAOS-Na (30 mg/kg/d) delayed the onset time of EAE from 11.78 days post immunization (dpi) to 14.33 dpi, reduced the incidence from 90.0% to 42.9%. UAOS-Na (60 mg/kg/d) reduced the serum levels of IFN-γ, IL-17A, TNF-α and IL-6, reduced the mononuclear cell infiltration of spinal cord, and inhibited the overexpression of key transcription factors T-bet and ROR-γt of EAE mouse spinal cord. In addition, UAOS-Na attenuated demyelination and astrogliosis in the CNS of EAE and cuprizone-induced mice. Mechanistically, proteomics showed that 96 differential expression proteins (DEPs) were enriched and 94 were upregulated in EAE mice compared with normal group. After UAOS-Na treatment, 16 DEPs were enriched and 15 were downregulated, and these DEPs were markedly enriched in antigen processing and presentation (APP) signaling pathway. Moreover, UAOS-Na downregulated the protein levels of Tapbp and H2-T23 in MHC-I antigen presentation pathway and reduced the proliferation of splenic CD8 T cells, thereby inhibiting the CNS infiltration of CD8 T cells.

Conclusion

Our findings demonstrated that UAOS-Na has both myelin protective and anti-inflammatory effects. And it could reduce the inflammation of MS by downregulating the expression of Tapbp and H2-T23 in the MHC-I antigen presentation pathway.

Prophylactic Zinc Administration Combined with Swimming Exercise Prevents Cognitive-Emotional Disturbances and Tissue Injury following a Transient Hypoxic-Ischemic Insult in the Rat

Exercise performance and zinc administration individually yield a protective effect on various neurodegenerative models, including ischemic brain injury. Therefore, this work was aimed at evaluating the combined effect of subacute prophylactic zinc administration and swimming exercise in a transient cerebral ischemia model. The prophylactic zinc administration (2.5 mg/kg of body weight) was provided every 24 h for four days before a 30 min common carotid artery occlusion (CCAO), and 24 h after reperfusion, the rats were subjected to swimming exercise in the Morris Water Maze (MWM). Learning was evaluated daily for five days, and memory on day 12 postreperfusion; anxiety or depression-like behavior was measured by the elevated plus maze and the motor activity by open-field test. Nitrites, lipid peroxidation, and the activity of superoxide dismutase (SOD) and catalase (CAT) were assessed in the temporoparietal cortex and hippocampus. The three nitric oxide (NO) synthase isoforms, chemokines, and their receptor levels were measured by ELISA. Nissl staining evaluated hippocampus cytoarchitecture and Iba-1 immunohistochemistry activated the microglia. Swimming exercise alone could not prevent ischemic damage but, combined with prophylactic zinc administration, reversed the cognitive deficit, decreased NOS and chemokine levels, prevented tissue damage, and increased Iba-1 (+) cell number. These results suggest that the subacute prophylactic zinc administration combined with swimming exercise, but not the individual treatment, prevents the ischemic damage on day 12 postreperfusion in the transient ischemia model.

The Importance of CXCL1 in Physiology and Noncancerous Diseases of Bone, Bone Marrow, Muscle and the Nervous System

This review describes the role of CXCL1, a chemokine crucial in inflammation as a chemoattractant for neutrophils, in physiology and in selected major non-cancer diseases. Due to the vast amount of available information, we focus on the role CXCL1 plays in the physiology of bones, bone marrow, muscle and the nervous system. For this reason, we describe its effects on hematopoietic stem cells, myoblasts, oligodendrocyte progenitors and osteoclast precursors. We also present the involvement of CXCL1 in diseases of selected tissues and organs including Alzheimer’s disease, epilepsy, herpes simplex virus type 1 (HSV-1) encephalitis, ischemic stroke, major depression, multiple sclerosis, neuromyelitis optica, neuropathic pain, osteoporosis, prion diseases, rheumatoid arthritis, tick-borne encephalitis (TBE), traumatic spinal cord injury and West Nile fever.

Mechanisms of oligodendrocyte progenitor developmental migration

Oligodendrocytes, the myelinating cells of the central nervous system (CNS), develop from oligodendrocyte progenitor cells (OPCs) that must first migrate extensively throughout the developing brain and spinal cord. Specified at particular times from discrete regions in the developing CNS, OPCs are one of the most migratory of cell types and disperse rapidly. A variety of factors act on OPCs to trigger intracellular changes that regulate their migration. We will discuss factors that act as long-range guidance cues, those that act to regulate cellular motility, and those that are critical in determining the final positioning of OPCs. In addition, recent evidence has identified the vasculature as the physical substrate used by OPCs for their migration. Several new findings relating to this oligodendroglial-vascular signaling axis reveal new insight on the relationship between OPCs and blood vessels in the developing and adult brain.

Oligodendrocytes and Microglia: Key Players in Myelin Development, Damage and Repair

Oligodendrocytes, the myelin-making cells of the CNS, regulate the complex process of myelination under physiological and pathological conditions, significantly aided by other glial cell types such as microglia, the brain-resident, macrophage-like innate immune cells. In this review, we summarize how oligodendrocytes orchestrate myelination, and especially myelin repair after damage, and present novel aspects of oligodendroglial functions. We emphasize the contribution of microglia in the generation and regeneration of myelin by discussing their beneficial and detrimental roles, especially in remyelination, underlining the cellular and molecular components involved. Finally, we present recent findings towards human stem cell-derived preclinical models for the study of microglia in human pathologies and on the role of microbiome on glial cell functions.

Long-term taurine administration improves motor skills in a tubulinopathy rat model by decreasing oxidative stress and promoting myelination

The taiep rat undergoes hypomyelination and progressive demyelination caused by an abnormal microtubule accumulation in oligodendrocytes, which elicits neuroinflammation and motor behavior dysfunction. Based on taurine antioxidant and proliferative actions, this work explored whether its sustained administration from the embryonic age to adulthood could prevent neuroinflammation, stimulate cell proliferation, promote myelination, and relieve motor impairment. Taurine (50 mg/L of drinking water = 50 ppm) was given to taiep pregnant rats on gestational day 15 and afterward to the male offspring until eight months of age. We measured the levels of nitric oxide (NO), malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA), CXCL1, CXCR2 receptor, growth factors (BNDF and FGF2), cell proliferation, and myelin content over time. Integral motor behavior was also evaluated. Our results showed that taurine administration significantly decreased NO and MDA + 4-HDA levels, increased cell proliferation, and promoted myelination in an age- and brain region-dependent fashion compared with untreated taiep rats. Taurine effect on chemokines and growth factors was also variable. Taurine improved vestibular reflexes and limb muscular strength in perinatal rats and fine movements and immobility episodes in adult rats. These results show that chronic taurine administration partially alleviates the taiep neuropathology.

Assessment of proliferation, migration and differentiation potentials of bone marrow mesenchymal stem cells labeling with silica-coated and amine-modified superparamagnetic iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles have been widely used for cell labeling in preclinical and clinical studies, to improve labeling efficiency, particle conjugation and surface modifications are developed, but some modified SPIONs exert side-effect on physiological activity of cells, which cannot be served as ideal cell tracker. In this study, amine-modified silica-coated SPIO (SPIO@SiO₂-NH₂, SPIO@S-N) nanoparticles were used to label bone marrow derived mesenchymal stem cells (BM-MSCs), then the stem cell potentials were evaluated. It was found BM-MSCs could be efficiently labeled by SPIO@S-N nanoparticles. After labeling, the BM-MSCs viability kept well and the migration ability increased, but the osteogenesis and adipogenesis potentials were not impaired. In steroid associated osteonecrosis (SAON) bone defect model, stem cell implantation was performed by injection of SPIO@S-N labeled BM-MSCs into marrow cavity locally, it was found the SPIO positive cells homed to the periphery of defect region in control group, but were recruited to the defect region in poly lactic-coglycolic acid/tricalcium phosphate (PLGA/TCP) scaffold implantation group. In conclusion, SPIO@S-N nanoparticles promoted migration while retained proliferation and differentiation ability of BM-MSCs, implying this kind of nanoparticles could be served not only an ideal tracking marker but also an accelerator for stem cell homing during tissue repair.

Astrocytes in multiple sclerosis and experimental autoimmune encephalomyelitis: Star-shaped cells illuminating the darkness of CNS autoimmunity

Neuropathology in the human autoimmune disease multiple sclerosis (MS) is considered to be mediated by autoreactive leukocytes, such as T cells, B cells, and macrophages. However, the inflammation and tissue damage in MS and its animal model experimental autoimmune encephalomyelitis (EAE) is also critically regulated by astrocytes, the most abundant cell population in the central nervous system (CNS). Under physiological conditions, astrocytes are integral to the development and function of the CNS, whereas in CNS autoimmunity, astrocytes influence the pathogenesis, progression, and recovery of the diseases. In this review, we summarize recent advances in astrocytic functions in the context of MS and EAE, which are categorized into two opposite aspects, one being detrimental and the other beneficial. Inhibition of the detrimental functions and/or enhancement of the beneficial functions of astrocytes might be favorable for the treatment of MS.

A Window on the Study of Aversive Instrumental Learning: Strains, Performance, Neuroendocrine, and Immunologic Systems

The avoidance response is present in pathological anxiety and interferes with normal daily functions. The aim of this article is to shed light on performance markers of active avoidance (AA) using two different rat strains, Sprague-Dawley (SD) and Wistar. Specifically, good and poor performers were evaluated regarding anxiety traits exhibited in the elevated plus maze (EPM) and corticosterone levels and motor activity in the open field test. In addition, the plasma levels of Interleukin-6 (IL-6), Interleukin-1Beta (IL-1beta), Nerve Growth Factor Beta (NGF-beta), Tumor Necrosis Factor-Alpha (TNF-alpha) and cytokine-induced neutrophil chemoattractant 1 (CINC-1) were compared in the good and poor performers to better understand the role of the immunologic system in aversive learning. Behavioral criteria were employed to identify subpopulations of SD and Wistar rats based on their behavioral scores during a two-way AA test. The animals were tested for anxiety-like behavior in the EPM and motor activity in the open-field test. Plasma corticosterone levels were measured at the end of the avoidance test. Cytokine levels of IL-6, IL-1beta, NGF-beta, TNF-alpha, and CINC-1 were measured in the plasma of the Wistar rats. Sixty-six percent of the Wistar rats and 35% of the SD rats exhibited a poor performance. This feature was associated with a decrease in anxiety-like behavior in the EPM. The poor and good performers exhibited lower levels of corticosterone compared with the control animals, which suggests that training alters corticosterone levels, thereby leading to hypocortisolism, independent of the performance. The CINC-1 levels were increased in the poor performers, which reinforces the role of immunologic system activation in learning deficits. Our study provides a better understanding of the complex interactions that underlie neuroimmune consequences and their implications for performance.

A silver lining of neuroinflammation: Beneficial effects on myelination

Myelin accelerates action potential conduction velocity and provides essential energy support for axons. Unfortunately, myelin and myelinating cells are often vulnerable to injury or disease, resulting in myelin damage, which in turn can lead to axon dysfunction, overt pathology and neurological impairment. Inflammation is a common component of trauma and disease in both the CNS and PNS and therefore an active inflammatory response is often considered deleterious to myelin health. While inflammation can certainly damage myelin, inflammatory processes also can positively affect oligodendrocyte lineage progression, myelin debris clearance, oligodendrocyte metabolism and myelin repair. In the periphery, inflammatory cascades can also augment myelin repair, including processes initiated by infiltrating immune cells as well as by local Schwann cells. In this review, various aspects of inflammation beneficial to myelin repair are discussed and should be considered when designing or implementing anti-inflammatory therapies for CNS and PNS injury involving myelinating cells.

Taking a bite out of spinal cord injury: do dental stem cells have the teeth for it?

Dental stem cells are an emerging star on a stage that is already quite populated. Recently, there has been a lot of hype concerning these cells in dental therapies, especially in regenerative endodontics. It is fitting that most research is concentrated on dental regeneration, although other uses for these cells need to be explored in more detail. Being a true mesenchymal stem cell, their capacities could also prove beneficial in areas outside their natural environment. One such field is the central nervous system, and in particular, repairing the injured spinal cord. One of the most formidable challenges in regenerative medicine is to restore function to the injured spinal cord, and as yet, a cure for paralysis remains to be discovered. A variety of approaches have already been tested, with graft-based strategies utilising cells harbouring appropriate properties for neural regeneration showing encouraging results. Here we present a review focusing on properties of dental stem cells that endorse their use in regenerative medicine, with particular emphasis on repairing the damaged spinal cord.

Lipopolysaccharide Upregulates the Expression of CINC-3 and LIX in Primary NG2 Cells

Numerous NG2 cells, also called oligodendrocyte progenitor cells (OPCs), exist ubiquitously in the gray and white matter in the adult central nervous system (CNS). Although NG2 cells could become active by upregulation of NG2 expression and hypertrophy or extension of their processes under various neuropathological conditions, their actual role in the brain remains to be illustrated. In view of the fact that the synergy of cytokine and chemokine networks plays an important role in CNS inflammation and immunity, we have assumed that the NG2 cells might take part in brain inflammation and immunity by making a contribution to the pool of cytokines or chemokines. In the current study, NG2-expressing OPCs were prepared from cerebral hemispheres of postnatal day 0 or 1 Sprague-Dawley rats. Our results showed that NG2-expressing OPCs, verified by immunohistological staining of anti-NG2 antibody and anti-platelet-derived growth factor receptor alpha (PDGFRα) antibody, presented binding affinity to lipopolysaccharide (LPS), a commonly used stimulator in a neuroinflammatory model. Using cytokine antibody array, QPCR and ELISA, we have further shown that LPS could upregulate the expression of cytokine induced neutrophil chemoattractant-3 (CINC-3) and LPS induced CXC chemokine (LIX) in primary NG2-expressing OPCs, without the alteration in cell number of NG2-expressing OPCs. In addition, the cells bearing the receptor for these two cytokines included microglia and OPCs. Taken together, our results suggest that NG2-expressing OPCs could response to LPS and may take part in neuroinflammatory process, through secreting cytokines and chemokines to exert an effect on target cells (OPCs and microglia).

CXCL1 inhibits airway smooth muscle cell migration through the decoy receptor Duffy antigen receptor for chemokines

Airway smooth muscle cell (ASMC) migration is an important mechanism postulated to play a role in airway remodeling in asthma. CXCL1 chemokine has been linked to tissue growth and metastasis. In this study, we present a detailed examination of the inhibitory effect of CXCL1 on human primary ASMC migration and the role of the decoy receptor, Duffy AgR for chemokines (DARC), in this inhibition. Western blots and pathway inhibitors showed that this phenomenon was mediated by activation of the ERK-1/2 MAPK pathway, but not p38 MAPK or PI3K, suggesting a biased selection in the signaling mechanism. Despite being known as a nonsignaling receptor, small interference RNA knockdown of DARC showed that ERK-1/2 MAPK activation was significantly dependent on DARC functionality, which, in turn, was dependent on the presence of heat shock protein 90 subunit α. Interestingly, DARC- or heat shock protein 90 subunit α-deficient ASMCs responded to CXCL1 stimulation by enhancing p38 MAPK activation and ASMC migration through the CXCR2 receptor. In conclusion, we demonstrated DARC's ability to facilitate CXCL1 inhibition of ASMC migration through modulation of the ERK-1/2 MAPK-signaling pathway.

Insufficient OPC migration into demyelinated lesions is a cause of poor remyelination in MS and mouse models

Failure of remyelination of multiple sclerosis (MS) lesions contributes to neurodegeneration that correlates with chronic disability in patients. Currently, there are no available treatments to reduce neurodegeneration, but one therapeutic approach to fill this unmet need is to promote remyelination. As many demyelinated MS lesions contain plentiful oligodendrocyte precursor cells (OPCs), but no mature myelinating oligodendrocytes, research has previously concentrated on promoting OPC maturation. However, some MS lesions contain few OPCs, and therefore, remyelination failure may also be secondary to OPC recruitment failure. Here, in a series of MS samples, we determined how many lesions contained few OPCs, and correlated this to pathological subtype and expression of the chemotactic molecules Semaphorin (Sema) 3A and 3F. 37 % of MS lesions contained low numbers of OPCs, and these were mostly chronic active lesions, in which cells expressed Sema3A (chemorepellent). To test the hypothesis that differential Sema3 expression in demyelinated lesions alters OPC recruitment and the efficiency of subsequent remyelination, we used a focal myelinotoxic mouse model of demyelination. Adding recombinant (r)Sema3A (chemorepellent) to demyelinated lesions reduced OPC recruitment and remyelination, whereas the addition of rSema3F (chemoattractant), or use of transgenic mice with reduced Sema3A expression increased OPC recruitment and remyelination. We conclude that some MS lesions fail to remyelinate secondary to reduced OPC recruitment, and that chemotactic molecules are involved in the mechanism, providing a new group of drug targets to improve remyelination, with a specific target in the Sema3A receptor neuropilin-1.