Central Nervous System and Peripheral Expression of CCL19, CCL21 and Their Receptor CCR7 in Experimental Model of Multiple Sclerosis

Chemokines in neurodegenerative diseases

Neurodegeneration and neuroinflammation disorders are mainly the result of the deposition of various proteins, such as α-synuclein, amyloid-β and prions, which lead to the initiation and activation of inflammatory responses. Different chemokines are involved in the infiltration and movement of inflammatory leukocytes into the central nervous system (CNS) that express chemokine receptors. Dysregulation of several members of chemokines has been shown in the CNS, cerebrospinal fluid and peripheral blood of patients who have neurodegenerative disorders. Upon infiltration of various cells, they produce many inflammatory mediators such as cytokines. Besides them, some CNS-resident cells, such as neurons and astrocytes, are also involved in the pathogenesis of neurodegeneration by producing chemokines. In this review, we summarize the role of chemokines and their related receptors in the pathogenesis of neurodegeneration and neuroinflammation disorders, including multiple sclerosis, Parkinson's disease and Alzheimer's disease. Therapeutic strategies targeting chemokines or their related receptors are also discussed in this article.

Enhancing Th17 cells drainage through meningeal lymphatic vessels alleviate neuroinflammation after subarachnoid hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is a severe cerebrovascular disorder primarily caused by the rupture of aneurysm, which results in a high mortality rate and consequently imposes a significant burden on society. The occurrence of SAH initiates an immune response that further exacerbates brain damage. The acute inflammatory reaction subsequent to SAH plays a crucial role in determining the prognosis. Th17 cells, a subset of T cells, are related to the brain injury following SAH, and it is unclear how Th17 cells are cleared in the brain. Meningeal lymphatic vessels are a newly discovered intracranial fluid transport system that has been shown to drain large molecules and immune cells to deep cervical lymph nodes. There is limited understanding of the role of the meningeal lymphatic system in SAH. The objective of this research is to explore the impact and underlying mechanism of drainage Th17 cells by meningeal lymphatics on SAH.

METHODS

Treatments to manipulate meningeal lymphatic function and the CCR7-CCL21 pathway were administered, including laser ablation, injection of VEGF-C geneknockout, and protein injection. Mouse behavior was assessed using the balance beam experiment and the modified Garcia scoring system. Flow cytometry, enzyme-linked immunosorbent assays (ELISA), and immunofluorescence staining were used to study the impact of meningeal lymphatic on SAH drainage. Select patients with unruptured and ruptured aneurysms in our hospital as the control group and the SAH group, with 7 cases in each group. Peripheral blood and cerebrospinal fluid (CSF) samples were assessed by ELISA and flow cytometry.

RESULTS

Mice with SAH showed substantial behavioral abnormalities and brain damage in which immune cells accumulated in the brain. Laser ablation of the meningeal lymphatic system or knockout of the CCR7 gene leads to Th17 cell aggregation in the meninges, resulting in a decreased neurological function score and increased levels of inflammatory factors. Injection of VEGF-C or CCL21 protein promotes Th17 cell drainage to lymph nodes, an increased neurological function score, and decreased levels of inflammatory factors. Clinical blood and CSF results showed that inflammatory factors in SAH group were significantly increased. The number of Th17 cells in the SAH group was significantly higher than the control group. Clinical results confirmed Th17 cells aggravated the level of neuroinflammation after SAH.

CONCLUSION

This study shows that improving the drainage of Th17 cells by meningeal lymphatics via the CCR7-CCL21 pathway can reduce brain damage and improve behavior in the SAH mouse model. This could lead to new treatment options for SAH.

Aflatoxin B1 exposure exacerbates chemokine receptor expression in the BTBR T+ Itpr3tf/J Mouse Model, unveiling insights into autism spectrum disorder: A focus on brain and spleen

OBJECTIVE

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by significant difficulties in social interaction, communication, and repeated stereotypic behaviour. Aflatoxin B1 (AFB1) is the most potent and well-known mycotoxin in various food sources. Despite its propensity to generate significant biochemical and structural changes in human and animal tissues, the influence of AFB1 on ASD has yet to be thoroughly studied. Mounting evidence indicates that chemokine receptors play a crucial function in the central nervous system and are implicated in developing several neuroinflammatory disorders. Chemokine receptors in individuals with ASD were elevated in the anterior cingulate gyrus astrocytes, cerebellum, and brain.

METHODS

The BTBR T+Itpr3tf/J (BTBR) mice are inbred strains that exhibit strong and consistently observed deficits in social interactions, characterized by excessive self-grooming and limited vocalization in social contexts. We examined the impact of AFB1 on CCR3-, CCR7-, CCR9-, CXCR3-, CXCR4-, and CXCR6-expressing I-A/I-E+ cells in the spleen of the BTBR mouse model of autism. We evaluated the mRNA levels of CCR3, CCR7, CCR9, CXCR3, CXCR4, and CXCR6 chemokine receptors in the brain.

RESULTS

The exposure to AFB1 in BTBR mice resulted in a significant rise in the number of I-A/I-E+CCR3+, I-A/I-E+CCR7+, I-A/I-E+CCR9+, I-A/I-E+CXCR3+, I-A/I-E+CXCR4+, and I-A/I-E+CXCR6+ cells. Furthermore, exposure to AFB1 increased mRNA expression levels of CCR3, CCR7, CCR9, CXCR3, CXCR4, and CXCR6 in the brain.

CONCLUSIONS

These findings highlight that AFB1 exposure increases the expression of chemokine receptors in BTBR mice, indicating the necessity for further research into AFB1's role in the development of ASD.

Emerging Cerebrospinal Fluid Biomarkers of Disease Activity and Progression in Multiple Sclerosis

Importance

Biomarkers distinguishing nonrelapsing progressive disease biology from relapsing biology in multiple sclerosis (MS) are lacking. Cerebrospinal fluid (CSF) is an accessible fluid that most closely reflects central nervous system biology.

Objective

To identify CSF biological measures associated with progressive MS pathobiology.

Design, Setting, and Participants

This cohort study assessed data from 2 prospective MS cohorts: a test cohort provided serial CSF, clinical, and imaging assessments in a multicenter study of patients with relapsing MS (RMS) or primary progressive MS (PPMS) who were initiating anti-CD20 treatment (recruitment: 2016-2018; analysis: 2020-2023). A single-site confirmation cohort was used to assess CSF at baseline and long-term (>10 year) clinical follow-up (analysis: 2022-2023).

Exposures

Test-cohort participants initiated standard-of-care ocrelizumab treatment. Confirmation-cohort participants were untreated or received standard-of-care disease-modifying MS therapies.

Main Outcomes and Measures

Twenty-five CSF markers, including neurofilament light chain, neurofilament heavy chain, and glial fibrillary acid protein (GFAP); 24-week confirmed disability progression (CDP24); and brain magnetic resonance imaging measures reflecting focal injury, tissue loss, and progressive biology (slowly expanding lesions [SELs]).

Results

The test cohort (n = 131) included 100 patients with RMS (mean [SD] age, 36.6 [10.4] years; 68 [68%] female and 32 [32%] male; Expanded Disability Status Scale [EDSS] score, 0-5.5), and 31 patients with PPMS (mean [SD] age, 44.9 [7.4] years; 15 [48%] female and 16 [52%] male; EDSS score, 3.0-6.5). The confirmation cohort (n = 68) included 41 patients with RMS and 27 with PPMS enrolled at diagnosis (age, 40 years [range, 20-61 years]; 47 [69%] female and 21 [31%] male). In the test cohort, GFAP was correlated with SEL count (r = 0.33), greater proportion of T2 lesion volume from SELs (r = 0.24), and lower T1-weighted intensity within SELs (r = -0.33) but not with acute inflammatory measures. Neurofilament heavy chain was correlated with SEL count (r = 0.25) and lower T1-weighted intensity within SELs (r = -0.28). Immune markers correlated with measures of acute inflammation and, unlike GFAP, were impacted by anti-CD20. In the confirmation cohort, higher baseline CSF GFAP levels were associated with long-term CDP24 (hazard ratio, 2.1; 95% CI, 1.3-3.4; P = .002).

Conclusions and Relevance

In this study, activated glial markers (in particular GFAP) and neurofilament heavy chain were associated specifically with nonrelapsing progressive disease outcomes (independent of acute inflammatory activity). Elevated CSF GFAP was associated with long-term MS disease progression.

CCL21/CCR7 axis regulates demyelination and vascular cognitive impairment in a mouse model for chronic cerebral hypoperfusion

OBJECTIVES

White matter lesions (WML) are usually accompanied by cognitive decline, which consist of axonal loss and demyelination. CC chemokine ligand 21 (CCL21) and its receptor C-C chemokine receptor 7 (CCR7) belong to the chemokine family, which are involved in many diseases. However, their function in the central nervous system (CNS) is still unexplored. This study aimed to explore the role of CCL21/CCR7 axis in the pathological process of chronic ischemia-induced WML.

METHODS

Bilateral common carotid artery stenosis (BCAS) was employed in C57BL/6 mice as the in vivo WML model. Microarray analysis was performed to detect the overall molecular changes induced in the endothelial cells by BCAS. Q-PCR, Western blotting, and immunofluorescence staining were performed to evaluate expression levels of the related molecules. The mice were injected with LV-CCL21-GFP virus in the corpus callosum to overexpress CCL21. WML degree was determined via MRI, and cognitive ability was assessed by Y-maze and novel object recognition tests. Myelin sheath integrity was evaluated via immunofluorescence staining.

RESULTS

CCL21 was significantly downregulated in endothelial cells after BCAS and CCL21 overexpression alleviated BCAS-induced cognitive deficits and demyelination. Furthermore, CCR7 was found to be mainly expressed in oligodendrocytes (OLs) after exposed to hypoxia and CCR7 silencing blocked the protective effects induced by CCL21 overexpression. Conclusions CCL21/CCR7 axis may play a key role in demyelination induced by BCAS. This might provide a novel therapeutic target for WML.

CCR6 blockade on regulatory T cells ameliorates experimental model of multiple sclerosis

Regulatory T cells (Tregs) play a significant role in limiting damage of tissue affected by autoimmune process, which has been demonstrated in various experimental models for multiple sclerosis (MS) (mostly experimental autoimmune encephalomyelitis – EAE), rheumatoid arthritis, and type 1 diabetes. In this study, we demonstrated that Tregs increasingly migrate to central nervous system (CNS) during subsequent phases of EAE (preclinical, initial attack, and remission). In contrast, in peripheral tissues (blood, lymph nodes, and spleen), a significant accumulation of Tregs is mostly present during EAE remission. Moreover, an increased expression of CCR6 on Tregs in the CNS, blood, lymph nodes, and spleen in all phases of EAE was observed. The highest expression of CCR6 on Tregs from the CNS, lymph nodes, and spleen was noted during the initial attack of EAE, whereas in the blood, the peak expression of CCR6 was detected during the preclinical phase. The presence of Tregs in the CNS during EAE was confirmed by immunohistochemistry. To analyze additional functional significance of CCR6 expression on Tregs for EAE pathology, we modulated the clinical course of this MS model using Tregs with blocked CCR6. EAE mice, which received CCR6-deficient Tregs showed significant amelioration of disease severity. This observation suggests that CCR6 on Tregs may be a potential target for future therapeutic interventions in MS.

Zika Virus Inhibits IFN-α Response by Human Plasmacytoid Dendritic Cells and Induces NS1-Dependent Triggering of CD303 (BDCA-2) Signaling

Zika virus (ZIKV) dramatically emerged in French Polynesia and subsequently in the Americas where it has been associated with severe neurological complications in adults and newborns, respectively. Although plasmacytoid dendritic cells (pDCs) are a key sensor of viral infection and are critical for initiating an antiviral response, little is known about the impact of ZIKV infection on pDCs. Here, we investigated the susceptibility of human pDCs to infection with multiple strains of ZIKV and further investigated the impact of infection on pDCs functions. We observed that pDCs were refractory to cell-free ZIKV virions but were effectively infected when co-cultured with ZIKV-infected cells. However, exposure of pDCs to ZIKV-infected cells resulted in limited maturation/activation with significant down regulation of CD303 expression, a severe impairment of inflammatory cytokine production, and an inability to mount an IFN-α response. We show that ZIKV developed a strategy to inhibit the IFN-α response in primary human pDCs likely mediated through NS1-dependent CD303 signaling, thus suggesting a new mechanism of immune evasion.

Targeting Chemokines and Chemokine Receptors in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is an immune-mediated and neurodegenerative disorder that results in inflammation and demyelination of the central nervous system (CNS). MS symptoms include walking difficulties, visual weakening, as well as learning and memory impairment, thus affecting the quality of the patient's life. Chemokines and chemokine receptors are expressed on the immune cells as well as the CNS resident cells. Several sets of chemokine receptors and their ligands tend to be pathogenic players in MS, including CCL2, CCL3, CCL4, CCL5, CCL7, CCL8, CCL11, CCL17, CCL19, CCL21, CCL22, CXCL1, CXCL8, CXCL9, CXCL10, CXCL11, and CXCL16. Furthermore, current modulatory drugs that are used in the treatment of MS and its animal model, the experimental autoimmune encephalomyelitis (EAE), affect the expression of several chemokine and chemokine receptors. In this review, we highlight the pathogenic roles of chemokines and their receptors as well as utilizing them as potential therapeutic targets through selective agents, such as specific antibodies and receptor blockers, or indirectly through MS or EAE immunomodulatory drugs.

Screening of genes associated with inflammatory responses in the endolymphatic sac reveals underlying mechanisms for autoimmune inner ear diseases

The current study analyzed gene expression profiles of the endolymphatic sac (ES) in rats and identified expressed genes, present in the human and rat ES, to reveal key hubs for inflammatory responses. Microarray data (accession no. E-MEXP-3022) were obtained from the European Bioinformatics Institute database, including three biological replicates of ES plus dura tissues and three replicates of pure dura tissues form rats. Differentially expressed genes (DEGs) were screened using the Linear Model for Microarray data method and a protein-protein interaction (PPI) network was constructed using data from the Search Tool for the Retrieval of Interacting Genes/Proteins database followed by a module analysis via Clustering with Overlapping Neighborhood Expansion. Function enrichment analysis was performed using the Database for Annotation, Visualization and Integrated Discovery online tool. A total of 612 DEGs were identified, including 396 upregulated and 216 downregulated genes. Gene ontology term enrichment analysis indicated DEGs were associated with cell adhesion, including α5-integrin (Itga1) and secreted phosphoprotein 1 (Spp1); T cell co-stimulation, including C-C chemokine ligand (Ccl)21 and Ccl19; and the toll-like receptor signaling pathway, including toll-like receptor (Tlr)2, Tlr7 and Tlr8. These conclusions were supported by Kyoto Encyclopedia of Genes and Genomes pathway analyses revealing extracellular matrix-receptor interaction, including Itga1 and Spp1; leukocyte transendothelial migration, includingclaudin-4 (Cldn4); and malaria, including Tlr2. The hub roles of Itga1, Cd24 and Spp1 were revealed by calculating three topological properties of the PPI network. Ccl21, Ccl19 and Cldn4 were demonstrated to be crucial following significant module analysis according to the corresponding threshold, which revealed they were enriched in inflammation pathways. Tlr7, Tlr2, granzyme m and Tlr8 were common genes associated with inflammatory responses in rat and human ES. In conclusion, abnormal expression of the aforementioned inflammation-associated genes may be associated with the development of autoimmune inner ear diseases.

Transcriptome profiling analysis of grouper during nervous necrosis virus persistent infection

Nervous necrosis virus (NNV) infection has been considered a serious disease in farmed grouper. Particularly, the persistent infection model conducts the grouper into a carrier state that continues to spread the virus through spawning. This particular model makes disease control more difficult in the aquaculture industry. In the present study, we used RNA-Seq, a high-throughput method based on next-generation sequencing, to profile the expression of genes during the period of NNV persistent infection. We evaluated the transcriptomic changes in the brain tissue of grouper. The inactivated-NNV vaccine was used as a comparison group. Based on the differentially expressed genes, highly immune cell active signaling and surface receptor expression were triggered during persistent infection. The interferon-induced response was also highly expressed in the infected brain tissue. However, critical negative regulatory factors of T-cells, such as PD-L1 and LAG3, were up-regulated. The present transcriptome study revealed a comprehensive view of the state of NNV persistent infection and provided insights into the state of impaired NNV clearance in the grouper.

CCR7 on CD4+ T Cells Plays a Crucial Role in the Induction of Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is the most common chronic inflammatory demyelinating disease of the CNS. Myelin-specific CD4⁺ Th lymphocytes are known to play a major role in both MS and its animal model experimental autoimmune encephalomyelitis (EAE). CCR7 is a critical element for immune cell trafficking and recirculation, that is, lymph node homing, under homeostatic conditions; blocking CCR7⁺ central memory cells from egress of lymph nodes is a therapeutic approach in MS. To define the effect of CD4⁺ T cell-specific constitutive deletion of CCR7 in the priming and effector phase in EAE, we used an active EAE approach in T cell reconstituted Rag1^-/- mice, as well as adoptive transfer EAE, in which mice received in vitro-primed CCR7^-/- or CCR7^+/+ myelin Ag TCR-transgenic 2d2 Th17 cells. Two-photon laser scanning microscopy was applied in living anesthetized mice to monitor the trafficking of CCR7-deficient and wild-type CD4⁺ T cells in inflammatory lesions within the CNS. We demonstrate that CD4⁺ T cell-specific constitutive deletion of CCR7 led to impaired induction of active EAE. In adoptive transfer EAE, mice receiving in vitro-primed CCR7^-/- 2d2 Th17 cells showed similar disease onset as mice adoptively transferred with CCR7^+/+ 2d2 Th17 cells. Using two-photon laser scanning microscopy CCR7^-/- and CCR7^+/+ CD4⁺ T cells did not reveal differences in motility in either animal model of MS. These findings indicate a crucial role of CCR7 in neuroinflammation during the priming of autoimmune CD4⁺ T cells but not in the CNS.

Chemokine CCL17 is expressed by dendritic cells in the CNS during experimental autoimmune encephalomyelitis and promotes pathogenesis of disease

The CC chemokine ligand 17 (CCL17) and its cognate CC chemokine receptor 4 (CCR4) are known to control leukocyte migration, maintenance of T_H17 cells, and regulatory T cell (T_reg) expansion in vivo. In this study we characterized the expression and functional role of CCL17 in the pathogenesis of experimental autoimmune encephalomyelitis (EAE). Using a CCL17/EGFP reporter mouse model, we could show that CCL17 expression in the CNS can be found in a subset of classical dendritic cells (DCs) that immigrate into the CNS during the effector phase of MOG-induced EAE. CCL17 deficient (CCL17^-/-) mice exhibited an ameliorated disease course upon MOG-immunization, associated with reduced immigration of IL-17 producing CD4⁺ T cells and peripheral DCs into the CNS. CCL17^-/- DCs further showed equivalent MHC class II and costimulatory molecule expression and an equivalent capacity to secrete IL-23 and induce myelin-reactive T_H17 cells when compared to wildtype DCs. In contrast, their transmigration in an in vitro model of the blood-brain barrier was markedly impaired. In addition, peripheral T_reg cells were enhanced in CCL17^-/- mice at peak of disease pointing towards an immunoregulatory function of CCL17 in EAE. Our study identifies CCL17 as a unique modulator of EAE pathogenesis regulating DC trafficking as well as peripheral T_reg cell expansion in EAE. Thus, CCL17 operates at distinct levels and on different cell subsets during immune response in EAE, a property harboring therapeutic potential for the treatment of CNS autoimmunity.

Ischemic stroke damages the intestinal mucosa and induces alteration of the intestinal lymphocytes and CCL19 mRNA in rats

The immunoreaction has a pivotal effect on ischemic stroke. It has been demonstrated that intestinal lymphocytes infiltrate into the brain and aggravate tissue injury after stroke. However, less attention has been paid to the influence on the intestinal immunology as well as morphology. Here, we utilized a rat permanent middle cerebral artery occlusion (MCAO) model to investigate the influences on intestinal mucosa, lymphocytes of the gut-associated lymphoid tissue (GALT), and the intestinal expression of CCL25 mRNA and CCL19 mRNA of stroke. Rats were randomly divided into stroke, sham, and control groups. Stroke and sham groups were further divided into interval groups of 6h, 12h, and 24h after surgery. Intestinal pathophysiological changes were observed by hematoxylin-eosin (H&E) staining. The lymphocyte numbers were detected by flow cytometry. The expression of CCL25 mRNA and CCL19 mRNA was tested with the PCR technique. We found significant necrosis and shedding of the epithelium after stroke. Moreover, the lesion aggravated with time. In addition, there was a significant increase of T lymphocytes in Peyer's patches (PPs), especially at 12h and 24h after stroke, while no differences in the number of B lymphocytes and the intraepithelial lymphocytes (IELs) were found. The data displayed no alteration of CCL25 mRNA expression. In contrast, an upregulation of CCL19 mRNA expression was detected at 6h after stroke. This study showed that ischemic stroke significantly damaged the intestinal epithelium and activated intestinal immunity.

T cell acute lymphoblastic leukemia (T-ALL): New insights into the cellular origins and infiltration mechanisms common and unique among hematologic malignancies

T-cell acute lymphoblastic leukemia (T-ALL) accounts for 15% and 25% of total childhood and adult ALL cases, respectively. During T-ALL, patients are at risk of organ infiltration by leukemic T-cells. Infiltration is a major consequence of disease relapse and correlates with poor prognosis. Transendothelial migration of leukemic cells is required to exit the blood stream into target organs. While mechanisms of normal T-cell transmigration are well known, the mechanisms of leukemic T-cell extravasation remain elusive; but involvement of chemokines, integrins and Notch signaling play critical roles. Here, we summarize current knowledge about molecular mechanisms of leukemic T-cell infiltration with special emphasis on the newly identified subtype early T-cell-progenitor (ETP)-ALL. Furthermore, we compare the extravasation potential of T-ALL cells with that of other hematologic malignancies such as B-ALL and acute myeloid leukemia (AML).

Evolving Identification of Blood Cells Associated with Clinically Isolated Syndrome: Importance of Time since Clinical Presentation and Diagnostic MRI

It is not clear how the profile of immune cells in peripheral blood differs between patients with clinically isolated syndrome (CIS) and healthy controls (HC). This study aimed to identify a CIS peripheral blood signature that may provide clues for potential immunomodulatory approaches early in disease. Peripheral blood mononuclear cells (PBMCs) were collected from 18 people with CIS, 19 HC and 13 individuals with other demyelinating conditions (ODC) including multiple sclerosis (MS). Individuals with CIS separated into two groups, namely those with early (≤14 days post-diagnostic magnetic resonance imaging (MRI); n = 6) and late (≥27 days; n = 12) blood sampling. Transitional B cells were increased in the blood of CIS patients independently of when blood was taken. However, there were two time-dependent effects found in the late CIS group relative to HC, including decreased CD56bright NK cells, which correlated significantly with time since MRI, and increased CD141+ myeloid dendritic cell (mDC2) frequencies. Higher CD1c+ B cells and lower non-classical monocyte frequencies were characteristic of more recent demyelinating disease activity (ODC and early CIS). Analysing cell populations by time since symptoms (subjective) and diagnostic MRI (objective) may contribute to understanding CIS.

Exercise attenuates neurological deficits by stimulating a critical HSP70/NF-κB/IL-6/synapsin I axis in traumatic brain injury rats

Background

Despite previous evidence for a potent inflammatory response after a traumatic brain injury (TBI), it is unknown whether exercise preconditioning (EP) improves outcomes after a TBI by modulating inflammatory responses.

Methods

We performed quantitative real-time PCR (qPCR) to quantify the genes encoding 84 cytokines and chemokines in the peripheral blood and used ELISA to determine both the cerebral and blood levels of interleukin-6 (IL-6). We also performed the chromatin immunoprecipitation (ChIP) assay to evaluate the extent of nuclear factor kappa-B (NF-κB) binding to the DNA elements in the IL-6 promoter regions. Also, we adopted the Western blotting assay to measure the cerebral levels of heat shock protein (HSP) 70, synapsin I, and β-actin. Finally, we performed both histoimmunological and behavioral assessment to measure brain injury and neurological deficits, respectively.

Results

We first demonstrated that TBI upregulated nine pro-inflammatory and/or neurodegenerative messenger RNAs (mRNAs) in the peripheral blood such as CXCL10, IL-18, IL-16, Cd-70, Mif, Ppbp, Ltd, Tnfrsf 11b, and Faslg. In addition to causing neurological injuries, TBI also upregulated the following 14 anti-inflammatory and/or neuroregenerative mRNAs in the peripheral blood such as Ccl19, Ccl3, Cxcl19, IL-10, IL-22, IL-6, Bmp6, Ccl22, IL-7, Bmp7, Ccl2, Ccl17, IL-1rn, and Gpi. Second, we observed that EP inhibited both neurological injuries and six pro-inflammatory and/or neurodegenerative genes (Cxcl10, IL-18, IL-16, Cd70, Mif, and Faslg) but potentiated four anti-inflammatory and/or neuroregenerative genes (Bmp6, IL-10, IL-22, and IL-6). Prior depletion of cerebral HSP70 with gene silence significantly reversed the beneficial effects of EP in reducing neurological injuries and altered gene profiles after a TBI. A positive Pearson correlation exists between IL-6 and HSP70 in the peripheral blood or in the cerebral levels. In addition, gene silence of cerebral HSP70 significantly reduced the overexpression of NF-κB, IL-6, and synapsin I in the ipsilateral brain regions after an EP in rats.

Conclusions

TBI causes neurological deficits associated with stimulating several pro-inflammatory gene profiles but inhibiting several anti-inflammatory gene profiles of cytokines and chemokines. Exercise protects against neurological injuries via stimulating an anti-inflammatory HSP70/NF-κB/IL-6/synapsin I axis in the injured brains.

Differential CCR7 Targeting in Dendritic Cells by Three Naturally Occurring CC-Chemokines

The CCR7 ligands CCL19 and CCL21 are increasingly recognized as functionally different (biased). Using mature human dendritic cells (DCs), we show that CCL19 is more potent than CCL21 in inducing 3D chemotaxis. Intriguingly, CCL21 induces prolonged and more efficient ERK1/2 activation compared with CCL19 and a C-terminal truncated (tailless) CCL21 in DCs. In contrast, tailless-CCL21 displays increased potency in DC chemotaxis compared with native CCL21. Using a CCL21-specific antibody, we show that CCL21, but not tailless-CCL21, accumulates at the cell surface. In addition, removal of sialic acid from the cell surface by neuraminidase treatment impairs ERK1/2 activation by CCL21, but not by CCL19 or tailless-CCL21. Using standard laboratory cell lines, we observe low potency of both CCL21 and tailless-CCL21 in G protein activation and β-arrestin recruitment compared with CCL19, indicating that the tail itself does not improve receptor interaction. Chemokines interact with their receptors in a stepwise manner with ultimate docking of their N-terminus into the main binding pocket. Employing site-directed mutagenesis we identify residues in this pocket of selective CCL21 importance. We also identify a molecular switch in the top of TM7 important for keeping CCR7 in an inactive conformation (Tyr312), as introduction of the chemokine receptor-conserved Glu (or Ala) induces high constitutive activity. Summarized, we show that the interaction of the tail of CCL21 with polysialic acid is needed for strong ERK signaling, whereas it impairs CCL21-mediated chemotaxis and has no impact on receptor docking consistent with the current model of chemokine:receptor interaction. This indicates that future selective pharmacological targeting of CCL19 versus CCL21 should focus on a differential targeting of the main receptor pocket, while selective targeting of tailless-CCL21 versus CCL21 and CCL19 requires targeting of the glycosaminoglycan (GAG) interaction.

Tertiary Lymphoid Organs in Central Nervous System Autoimmunity

Multiple sclerosis (MS) is an autoimmune disease characterized by chronic inflammation in the central nervous system (CNS), which results in permanent neuronal damage and substantial disability in patients. Autoreactive T cells are important drivers of the disease; however, the efficacy of B cell depleting therapies uncovered an essential role for B cells in disease pathogenesis. They can contribute to inflammatory processes via presentation of autoantigen, secretion of pro-inflammatory cytokines, and production of pathogenic antibodies. Recently, B cell aggregates reminiscent of tertiary lymphoid organs (TLOs) were discovered in the meninges of MS patients, leading to the hypothesis that differentiation and maturation of autopathogenic B and T cells may partly occur inside the CNS. Since these structures were associated with a more severe disease course, it is extremely important to gain insight into the mechanism of induction, their precise function, and clinical significance. Mechanistic studies in patients are limited. However, a few studies in the MS animal model experimental autoimmune encephalomyelitis (EAE) recapitulate TLO formation in the CNS and provide new insight into CNS TLO features, formation, and function. This review summarizes what we know so far about CNS TLOs in MS and what we have learned about them from EAE models. It also highlights the areas that are in need of further experimental work, as we are just beginning to understand and evaluate the phenomenon of CNS TLOs.

Meningeal Tertiary Lymphoid Tissues and Multiple Sclerosis: A Gathering Place for Diverse Types of Immune Cells during CNS Autoimmunity

Collections of leukocytes in the meningeal space have been documented in Multiple Sclerosis (MS). These meningeal aggregates, which in the context of other autoimmune diseases have often been termed tertiary lymphoid tissues (TLT), have been associated with sub-pial cortical damage and disease progression. However, the key molecular and cellular signals required for their formation and maintenance remain unclear. Herein, we review TLT structures in other disease states in order to provide a framework for understanding these structures in the MS meninges. We then assess the evidence that the meningeal compartment serves as an important nexus for immune cells as well as a location for drainage of antigen into cervical lymph nodes. Extrapolating what is known about the molecular and cellular cues that initiate the formation of leukocyte aggregates in non-lymphoid tissues, we speculate on what signals lead to the formation and maintenance of meningeal TLT structures. Referring to the animal model of MS [experimental autoimmune encephalomyelitis (EAE)], we also explore what is known about these structures in supporting B cell and T cell responses during neuroinflammation. Last, we examine the evidence that connects these structures to ongoing neuropathology. Collectively, our review points to the meningeal compartment as an important player in neuroinflammatory processes. Moreover, we hypothesize that in order to gain insights into pro- and anti-inflammatory properties of lymphocytes in MS, one must understand the cellular scaffolds that support lymphocyte retention within the meninges, thus highlighting the importance of non-immune cells (stromal cells) in the neuroinflammatory process.

Cytokine and Chemokine Profiles in Patients with Neuromyelitis Optica Spectrum Disorder

OBJECTIVE

To screen cytokines and chemokines and determine their dynamic changes in the serum and cerebrospinal fluid (CSF) of patients with neuromyelitis optica spectrum disorder (NMOSD).

METHODS

Eight NMOSD with seropositive aquaporin-4 antibody (AQP4-IgG) were enrolled, as well as 8 matched patients with multiple sclerosis (MS) and 8 with noninflammatory neurological diseases, who were included as controls. In total, 102 cytokines and 34 chemokines were detected in the CSF and serum of NMOSD patients and controls.

RESULTS

CSF interleukin (IL)-17A levels were significantly higher in NMOSD patients in the relapsing phase (27.15 ± 11.33) than in those in the remitting phase (10.04 ± 3.11, p = 0.0017), and patients with MS (14.72 ± 3.20, p = 0.0283) and other controls (10.39 ± 11.38, p = 0.0021). CSF IL-6 levels were higher in the NMOSD patients in the relapsing phase (12.23 ± 3.47) than in those in the remitting phase (5.87 ± 2.78, p = 0.0001), and MS patients (7.38 ± 2.35, p = 0.0033) and other controls (7.50 ± 0.37, p = 0.0043). CSF CCL19 levels were also significantly higher in NMOSD patients in the relapsing phase (35.87 ± 27.07) than in those in the remitting phase (10.71 ± 3.62, p = 0.0215). Serum IL-19 levels were lower in NMOSD patients in the relapsing phase (6.23 ± 1.95) than in those in the remitting phase (10.72 ± 4.46, p = 0.0092). Further, there was a positive, significant correlation between serum IL-9 concentration and the Expanded Disability Status Scale score in the NMOSD patients in the relapsing phase (p = 0.04).

CONCLUSION

In addition to IL-6 and IL-17A, IL-16 and CCL19 act as proinflammatory cytokines/chemokines, while IL-19 plays a protective role in NMOSD pathogenesis.