Dysregulation of the IL-23/IL-17 axis and myeloid factors in secondary progressive MS

As time goes by: Treatment challenges in elderly people with multiple sclerosis

A demographic shift in multiple sclerosis (MS) is leading to an increased number of elderly people with MS (pwMS) and a rise in late-onset MS (LOMS) cases. This shift adds complexity to the treatment management of these patients, due to enhanced treatment-associated risks and the possible interplay between immunosenescence and disease-modifying therapies (DMTs). In the present paper, we performed a systematic review of the current evidence concerning the relationship between aging and treatment management in elderly pwMS. Our literature search identified 35 original studies relevant to this topic. The gathered evidence consistently indicates a diminished efficacy of DMTs in older pwMS, particularly in preventing disability accrual. Against this background, high-efficacy therapies (HETs) appear to show less benefit over moderate-low-efficacy DMTs in older patients. These data mainly derive from observational retrospective studies or meta-analyses conducted on randomized clinical trials (RCTs). RCTs, however, exclude pwMS older than 55 years, limiting our ability to acquire robust evidence regarding this patient group. Regarding treatment discontinuation in elderly pwMS with stable disease, the available data, which mainly focuses on older injectable DMTs, suggests that their suspension appears to be relatively safe in terms of disease activity. Nevertheless, the first RCT specifically targeting treatment discontinuation recently failed to demonstrate the non-inferiority of treatment discontinuation over continuation, in terms of MRI activity. On the other hand, the evidence on the impact of discontinuation on disease progression is more conflicting and less robust. Furthermore, there is an important lack of studies concerning sequestering DMTs and virtually no data on the discontinuation of anti-CD20 monoclonal antibodies. De-escalation strategy is gaining attention as a de-risking approach alternative to complete treatment discontinuation. It may be defined as the decision to shift from HETs to less potent DMTs in elderly pwMS who have a stable disease. This strategy could reduce treatment-related risks, while minimizing the risk of disease activity and progression potentially associated with treatment discontinuation. This approach, however, remains unexplored due to a lack of studies. Given these findings, the present scenario underlines the urgent need for more comprehensive and robust studies to develop optimized, data-driven treatment strategies for elderly pwMS and LOMS, addressing the unique challenges of MS treatment and aging.

Biological aging in multiple sclerosis

Multiple sclerosis (MS) is most likely to adopt a progressive clinical course during middle age or beyond, and the number of older adults with MS is steadily increasing. Developing new strategies to manage progressive forms of MS, which do not respond to currently available disease-modifying therapies (DMTs), will require a deeper understanding of the mechanisms by which biological aging interacts with pathogenic pathways to propel disability accumulation. In experimental autoimmune encephalomyelitis (EAE), a widely used preclinical mouse model of MS, middle-aged animals experience a more severe and protracted clinical course than their younger counterparts. This exacerbated disease course is accompanied by persistent neuroinflammation. Clinical studies of age-related biomarkers, such as telomere length, senescence markers, and DNA methylation, suggest that biological aging is accelerated in people with MS compared with age- and sex-matched healthy controls. Furthermore, distinguishing biological age from chronological may afford more precision in determining aging effects in MS. Here we review the current literature on aging biology and its impact on MS pathogenesis. Future research on this topic may lead to the development of novel biomarkers and senotherapy agents that slow neurological decline in people with progressive MS by targeting relevant aging-related pathways.

New Enhancing MRI Lesions Associate with IL-17, Neutrophil Degranulation and Integrin Microparticles: Multi-Omics Combined with Frequent MRI in Multiple Sclerosis

BACKGROUND

Blood-barrier (BBB) breakdown and active inflammation are hallmarks of relapsing multiple sclerosis (RMS), but the molecular events contributing to the development of new lesions are not well explored. Leaky endothelial junctions are associated with increased production of endothelial-derived extracellular microvesicles (EVs) and result in the entry of circulating immune cells into the brain. MRI with intravenous gadolinium (Gd) can visualize acute blood-barrier disruption as the initial event of the evolution of new lesions.

METHODS

Here, weekly MRI with Gd was combined with proteomics, multiplex immunoassay, and endothelial stress-optimized EV array to identify early markers related to BBB disruption. Five patients with RMS with no disease-modifying treatment were monitored weekly using high-resolution 3T MRI scanning with intravenous gadolinium (Gd) for 8 weeks. Patients were then divided into three groups (low, medium, or high MRI activity) defined by the number of new, total, and maximally enhancing Gd-enhancing lesions and the number of new FLAIR lesions. Plasma samples taken at each MRI were analyzed for protein biomarkers of inflammation by quantitative proteomics, and cytokines using multiplex immunoassays. EVs were characterized with an optimized endothelial stress EV array based on exosome surface protein markers for the detection of soluble secreted EVs.

RESULTS

Proteomics analysis of plasma yielded quantitative information on 208 proteins at each patient time point (n = 40). We observed the highest number of unique dysregulated proteins (DEPs) and the highest functional enrichment in the low vs. high MRI activity comparison. Complement activation and complement/coagulation cascade were also strongly overrepresented in the low vs. high MRI activity comparison. Activation of the alternative complement pathway, pathways of blood coagulation, extracellular matrix organization, and the regulation of TLR and IGF transport were unique for the low vs. high MRI activity comparison as well, with these pathways being overrepresented in the patient with high MRI activity. Principal component analysis indicated the individuality of plasma profiles in patients. IL-17 was upregulated at all time points during 8 weeks in patients with high vs. low MRI activity. Hierarchical clustering of soluble markers in the plasma indicated that all four MRI outcomes clustered together with IL-17, IL-12p70, and IL-1β. MRI outcomes also showed clustering with EV markers CD62E/P, MIC A/B, ICAM-1, and CD42A. The combined cluster of these cytokines, EV markers, and MRI outcomes clustered also with IL-12p40 and IL-7. All four MRI outcomes correlated positively with levels of IL-17 (p < 0.001, respectively), and EV-ICAM-1 (p < 0.0003, respectively). IL-1β levels positively correlated with the number of new Gd-enhancing lesions (p < 0.01), new FLAIR lesions (p < 0.001), and total number of Gd-enhancing lesions (p < 0.05). IL-6 levels positively correlated with the number of new FLAIR lesions (p < 0.05). Random Forests and linear mixed models identified IL-17, CCL17/TARC, CCL3/MIP-1α, and TNF-α as composite biomarkers predicting new lesion evolution.

CONCLUSIONS

Combination of serial frequent MRI with proteome, neuroinflammation markers, and protein array data of EVs enabled assessment of temporal changes in inflammation and endothelial dysfunction in RMS related to the evolution of new and enhancing lesions. Particularly, the Th17 pathway and IL-1β clustered and correlated with new lesions and Gd enhancement, indicating their importance in BBB disruption and initiating acute brain inflammation in MS. In addition to the Th17 pathway, abundant protein changes between MRI activity groups suggested the role of EVs and the coagulation system along with innate immune responses including acute phase proteins, complement components, and neutrophil degranulation.

Iguratimod Ameliorates the Severity of Secondary Progressive Multiple Sclerosis in Model Mice by Directly Inhibiting IL-6 Production and Th17 Cell Migration via Mitigation of Glial Inflammation

We previously reported a novel secondary progressive multiple sclerosis (SPMS) model, progressive experimental autoimmune encephalomyelitis (pEAE), in oligodendroglia-specific Cx47-inducible conditional knockout (Cx47 icKO) mice. Based on our prior study showing the efficacy of iguratimod (IGU), an antirheumatic drug, for acute EAE treatment, we aimed to elucidate the effect of IGU on the SPMS animal model. We induced pEAE by immunizing Cx47 icKO mice with myelin oligodendrocyte glycoprotein peptide 35-55. IGU was orally administered from 17 to 50 days post-immunization. We also prepared a primary mixed glial cell culture and measured cytokine levels in the culture supernatant after stimulation with designated cytokines (IL-1α, C1q, TNF-α) and lipopolysaccharide. A migration assay was performed to evaluate the effect of IGU on the migration ability of T cells toward mixed glial cell cultures. IGU treatment ameliorated the clinical signs of pEAE, decreased the demyelinated area, and attenuated glial inflammation on immunohistochemical analysis. Additionally, IGU decreased the intrathecal IL-6 level and infiltrating Th17 cells. The migration assay revealed reduced Th17 cell migration and IL-6 levels in the culture supernatant after IGU treatment. Collectively, IGU successfully mitigated the clinical signs of pEAE by suppressing Th17 migration through inhibition of IL-6 production by proinflammatory-activated glial cells.

Respiratory tract Moraxella catarrhalis and Klebsiella pneumoniae can promote pathogenicity of myelin-reactive Th17 cells

The respiratory tract is home to a diverse microbial community whose influence on local and systemic immune responses is only beginning to be appreciated. The airways have been linked with the trafficking of myelin-specific T-cells in the preclinical stages of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Th17 cells are important pathogenic effectors in MS and EAE but are innocuous immediately following differentiation. Upregulation of the cytokine GM-CSF appears to be a critical step in their acquisition of pathogenic potential, but little is known about the mechanisms that mediate this process. Here, primed myelin-specific Th17 cells were transferred to congenic recipient mice prior to exposure to various human respiratory tract-associated bacteria and T-cell trafficking, phenotype and the severity of resulting EAE were monitored. Disease was exacerbated in mice exposed to the Proteobacteria Moraxella catarrhalis and Klebsiella pneumoniae, but not the Firmicute Veillonella parvula, and this was associated with significantly increased GM-CSF+ and GM-CSF+IFNγ+ ex-Th17-like donor CD4 T cells in the lungs and central nervous system (CNS) of these mice. These findings support the concept that respiratory bacteria may contribute to the pathophysiology of CNS autoimmunity by modulating pathogenicity in crucial T-cell subsets that orchestrate neuroinflammation.

Emerging role of extracellular vesicles in multiple sclerosis: From cellular surrogates to pathogenic mediators and beyond

Multiple Sclerosis (MS) is a chronic, inflammatory demyelinating disease of the central nervous system (CNS) driven by a complex interplay of genetic and environmental factors. While the therapeutic arsenal has expanded significantly for management of relapsing forms of MS, treatment of individuals with progressive MS is suboptimal. This treatment inequality is in part due to an incomplete understanding of pathomechanisms at different stages of the disease-underscoring the critical need for new biomarkers. Extracellular vesicles (EVs) and their bioactive cargo have emerged as endogenous nanoparticles with great theranostic potential-as diagnostic and prognostic biomarkers and ultimately as therapeutic candidates for precision nanotherapeutics. The goals of this review are to: 1) summarize the current data investigating the role of EVs and their bioactive cargo in MS pathogenesis, 2) provide a high level overview of advances and challenges in EV isolation and characterization for translational studies, and 3) conclude with future perspectives on this evolving field.

Multiple sclerosis: Neuroimmune crosstalk and therapeutic targeting

Multiple sclerosis (MS) is a chronic inflammatory and degenerative disease of the central nervous system afflicting nearly three million individuals worldwide. Neuroimmune interactions between glial, neural, and immune cells play important roles in MS pathology and offer potential targets for therapeutic intervention. Here, we review underlying risk factors, mechanisms of MS pathogenesis, available disease modifying therapies, and examine the value of emerging technologies, which may address unmet clinical needs and identify novel therapeutic targets.

Ageing and multiple sclerosis

The factor that is most relevant and strongly associated with the clinical course of multiple sclerosis is chronological age. Very young patients exclusively have relapsing remitting disease, whereas those with later onset disease face a more rapid development of permanent disability. For people with progressive multiple sclerosis, the poor response to current disease modifying therapies might be related to ageing in the immune system and CNS. Ageing is also associated with increased risks of side-effects caused by some multiple sclerosis therapies. Both somatic and reproductive ageing processes might contribute to development of progressive multiple sclerosis. Understanding the role of ageing in immune and neural cell function in patients with multiple sclerosis might be key to halting non-relapse-related progression. The growing literature on potential therapies that target senescent cells and ageing processes might provide effective strategies for remyelination and neuroprotection.

Chronic traumatic encephalopathy: Diagnostic updates and advances

Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disease that occurs secondary to repetitive mild traumatic brain injury. Current clinical diagnosis relies on symptomatology and structural imaging findings which often vary widely among those with the disease. The gold standard of diagnosis is post-mortem pathological examination. In this review article, we provide a brief introduction to CTE, current diagnostic workup and the promising research on imaging and fluid biomarker diagnostic techniques. For imaging, we discuss quantitative structural analyses, DTI, fMRI, MRS, SWI and PET CT. For fluid biomarkers, we discuss p-tau, TREM2, CCL11, NfL and GFAP.

Prophylactic effects of cucurbitacin B in the EAE Model of multiple sclerosis by adjustment of STAT3/IL-23/IL-17 axis and improvement of neuropsychological symptoms

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system. Although remarkable progress has been made in treating MS, current therapies are less effective in protecting against the progression of the disease. Since cucurbitacins have shown an extreme range of pharmacological properties, in this study, we aimed to investigate the prophylactic effect of cucurbitacin B (CuB) in the experimental MS model. Experimental autoimmune encephalomyelitis (EAE) induced by subcutaneous immunization of MOG35-55 in C57BL/6 mice. CuB interventions (0.5 and 1 mg/kg, i.p.) were performed every other day from the first day of EAE induction. Assessment of clinical scores and motor function, inflammatory responses, and microglial activation were assessed by qRT-PCR, western blotting, and immunohistochemical (IHC) analyses. CuB (1 mg/kg) significantly decreased the population of CD45⁺ (P < 0.01), CD11b⁺ (P < 0.01) and CD45⁺/CD11b⁺ (P < 0.05) cells in cortical lesions of EAE mice. In addition, activation of STAT3 (P < 0.001), expression of IL-17 A and IL-23 A (both mRNA and protein), and transcription of Iba-1 significantly decreased. On the contrary, CuB (1 mg/kg) significantly increased the transcription of MBP and Olig-2. Furthermore, a significant decrease in the severity of EAE (P < 0.05), and an improvement in motor function (P < 0.05) and coordination (P < 0.05) were observed after treatment with a high dose of CuB. Our results suggest that CuB may have a wide-ranging effect on autoimmune responses in MS via a reduction in STAT3 activation, microgliosis, and adaptation of the IL-23/IL-17 axis. Further studies are needed to investigate the exact effect of CuB in glial cells and its efficiency and bioavailability in other neuroinflammatory diseases.

Role of Cytokines, Chemokines and IFN-γ+ IL-17+ Double-Positive CD4+ T Cells in Patients with Multiple Sclerosis

Multiple sclerosis is mediated by self-reactive myelin T and B cells that lead to axonal and myelin damage. The immune response in multiple sclerosis involves the participation of CD4⁺ T cells that produce cytokines and chemokines. This participation is important to find markers for the diagnosis and progression of the disease. In our work, we evaluated the profile of cytokines and chemokines, as well as the production of double positive CD4⁺ T cells for the production of IFNγ IL-17 in patients with multiple sclerosis, at different stages of the disease and undergoing different treatments. We found that relapsing–remitting patients had a significant increase in IL-12 production. About IL-5, its production showed significantly higher levels in secondarily progressive patients when compared to relapsing–remitting patients. IFN-γ production by PBMCs from secondarily progressive patients showed significantly higher levels. This group also had a higher percentage of CD4⁺ IFNγ⁺ IL-17⁺ T cells. The combination of changes in certain cytokines and chemokines together with the presence of IFNγ⁺ IL-17⁺ double positive lymphocytes can be used to better understand the clinical forms of the disease and its progression.

Biological aging of CNS-resident cells alters the clinical course and immunopathology of autoimmune demyelinating disease

Biological aging is the strongest factor associated with the clinical phenotype of multiple sclerosis (MS). Relapsing-remitting MS typically presents in the third or fourth decade, whereas the mean age of presentation of progressive MS (PMS) is 45 years old. Here, we show that experimental autoimmune encephalomyelitis (EAE), induced by the adoptive transfer of encephalitogenic CD4⁺ Th17 cells, was more severe, and less likely to remit, in middle-aged compared with young adult mice. Donor T cells and neutrophils were more abundant, while B cells were relatively sparse, in CNS infiltrates of the older mice. Experiments with reciprocal bone marrow chimeras demonstrated that radio-resistant, nonhematopoietic cells played a dominant role in shaping age-dependent features of the neuroinflammatory response, as well as the clinical course, during EAE. Reminiscent of PMS, EAE in middle-aged adoptive transfer recipients was characterized by widespread microglial activation. Microglia from older mice expressed a distinctive transcriptomic profile suggestive of enhanced chemokine synthesis and antigen presentation. Collectively, our findings suggest that drugs that suppress microglial activation, and acquisition or expression of aging-associated properties, may be beneficial in the treatment of progressive forms of inflammatory demyelinating disease.

Brain Antigens Stimulate Proliferation of T Lymphocytes With a Pathogenic Phenotype in Multiple Sclerosis Patients

A method to stimulate T lymphocytes with a broad range of brain antigens would facilitate identification of the autoantigens for multiple sclerosis and enable definition of the pathogenic mechanisms important for multiple sclerosis. In a previous work, we found that the obvious approach of culturing leukocytes with homogenized brain tissue does not work because the brain homogenate suppresses antigen-specific lymphocyte proliferation. We now report a method that substantially reduces the suppressive activity. We used this non-suppressive brain homogenate to stimulate leukocytes from multiple sclerosis patients and controls. We also stimulated with common viruses for comparison. We measured proliferation, selected the responding CD3+ cells with flow cytometry, and sequenced their transcriptomes for mRNA and T-cell receptor sequences. The mRNA expression suggested that the brain-responding cells from MS patients are potentially pathogenic. The T-cell receptor repertoire of the brain-responding cells was clonal with minimal overlap with virus antigens.

DICAM promotes TH17 lymphocyte trafficking across the blood-brain barrier during autoimmune neuroinflammation

[Figure: see text].

A new and spontaneous animal model for ankylosing spondylitis is found in cynomolgus monkeys

BACKGROUND

Ankylosing spondylitis is a progressive, disabling joint disease that affects millions worldwide. Given its unclear etiology, studies of ankylosing spondylitis relied heavily on drug-induced or transgenic rodent models which retain only partial clinical features. There is obviously a lack of a useful disease model to conduct comprehensive mechanistic studies.

METHODS

We followed a group of cynomolgus monkeys having joint lesions reported of spinal stiffness for 2 years by conducting hematological testing, radiographic examination, family aggregation analysis, pathological analysis, and genetic testing.

RESULTS

The results confirmed that these diseased animals suffered from spontaneous ankylosing spondylitis with clinical features recapitulating human ankylosing spondylitis disease progression, manifested by pathological changes and biochemical indicators similar to that of ankylosing spondylitis patients.

CONCLUSION

The study offers a promising non-human primate model for spontaneous ankylosing spondylitis which may serve as an excellent substitute for its pre-clinical research.

Differential activation of neuroinflammatory pathways in children with seizures: A cross-sectional study

PURPOSE

Inflammation plays a crucial role in epileptogenesis. We analyzed inflammatory cytokines in plasma and saliva from children with seizures and healthy controls and measured their associations with HHV6 and EBV infection.

METHODS

We analyzed plasma from 36 children within 24 h of seizures (cases) and 43 healthy controls and saliva from 44 cases and 44 controls with a multiplex immunoassay. Saliva from all controls and 65 cases and blood from 26 controls and 35 cases were also analyzed by PCR for viral DNA. Primary outcome was cytokine levels in cases vs. controls. Secondary outcomes included detection of HHV-6 and EBV viral DNA in cases vs. controls and viral loads in cases vs. controls. Statistical analysis included the Wilcoxon Rank Sum test, Fisher's exact test, ANOVA, and Spearman correlation.

RESULTS

Compared to controls, patients had higher levels of CCL11 (p = 0.0018), CCL26 (p<0.001), IL10 (p = 0.044), IL6 (p<0.001), IL8 (p = 0.018), and MIP1β (p = 0.0012). CCL11 was higher with 3 or more seizures (p = 0.01), seizures longer than 10 min (p = 0.001), and when EEG showed focal slowing (p = 0.02). In saliva, febrile seizures had higher levels of IL-1β (n = 7, p = 0.04) and new onset seizures had higher IL-6 (n = 15, p = 0.02). Plasma and saliva cytokine levels did not show a correlation. The frequency of HHV-6 and EBV detection was similar across groups and not different than controls. We found no correlation between viral load and cytokine levels.

CONCLUSIONS

We showed differential activation of neuroinflammatory pathways in plasma from different seizure etiologies compared to controls, unrelated to viral infection.

Male sex chromosomal complement exacerbates the pathogenicity of Th17 cells in a chronic model of central nervous system autoimmunity

Sex differences in multiple sclerosis (MS) incidence and severity have long been recognized. However, the underlying cellular and molecular mechanisms for why male sex is associated with more aggressive disease remain poorly defined. Using a T cell adoptive transfer model of chronic experimental autoimmune encephalomyelitis (EAE), we find that male Th17 cells induce disease of increased severity relative to female Th17 cells, irrespective of whether transferred to male or female recipients. Throughout the disease course, a greater frequency of male Th17 cells produce IFNγ, a hallmark of pathogenic Th17 responses. Intriguingly, XY chromosomal complement increases the pathogenicity of male Th17 cells. An X-linked immune regulator, Jarid1c, is downregulated in pathogenic male murine Th17 cells, and functional experiments reveal that it represses the severity of Th17-mediated EAE. Furthermore, Jarid1c expression is downregulated in CD4⁺ T cells from MS-affected individuals. Our data indicate that male sex chromosomal complement critically regulates Th17 cell pathogenicity.

A STAT3 inhibitor ameliorates CNS autoimmunity by restoring Teff:Treg balance

Reestablishing an appropriate balance between T effector cells (Teff) and Tregs is essential for correcting autoimmunity. Multiple sclerosis (MS) is an immune-mediated chronic CNS disease characterized by neuroinflammation, demyelination, and neuronal degeneration, in which the Teff:Treg balance is skewed toward pathogenic Teffs Th1 and Th17 cells. STAT3 is a key regulator of Teff:Treg balance. Using the structure-based design, we have developed a potentially novel small-molecule prodrug LLL12b that specifically inhibits STAT3 and suppresses Th17 differentiation and expansion. Moreover, LLL12b regulates the fate decision between Th17 and Tregs in an inflammatory environment, shifting Th17:Treg balance toward Tregs and favoring the resolution of inflammation. Therapeutic administration of LLL12b after disease onset significantly suppresses disease progression in adoptively transferred, chronic, and relapsing-remitting experimental autoimmune encephalomyelitis. Disease relapses were also significantly suppressed by LLL12b given during the remission phase. Additionally, LLL12b shifts Th17:Treg balance of CD4⁺ T cells from MS patients toward Tregs and increases Teff sensitivity to Treg-mediated suppression. These data suggest that selective inhibition of STAT3 by the small molecule LLL12b recalibrates the effector and regulatory arms of CD4⁺ T responses, representing a potentially clinically translatable therapeutic strategy for MS.

Gut microbiome and multiple sclerosis: New insights and perspective

The human gastrointestinal microbiota, also known as the gut microbiota living in the human gastrointestinal tract, has been shown to have a significant impact on several human disorders including rheumatoid arthritis, diabetes, obesity, and multiple sclerosis (MS). MS is an inflammatory disease characterized by the destruction of the spinal cord and nerve cells in the brain due to an attack of immune cells, causing a wide range of harmful symptoms related to inflammation in the central nervous system (CNS). Despite extensive studies on MS that have shown that many external and genetic factors are involved in its pathogenesis, the exact role of external factors in the pathophysiology of MS is still unclear. Recent studies on MS and experimental autoimmune encephalomyelitis (EAE), an animal model of encephalitis, have shown that intestinal microbiota may play a key role in the pathogenesis of MS. Therefore, modification of the intestinal microbiome could be a promising strategy for the future treatment of MS. In this study, the characteristics of intestinal microbiota, the relationship between intestine and brain despite the blood-brain barrier, various factors involved in intestinal microbiota modification, changes in intestinal microbial composition in MS, intestinal microbiome modification strategies, and possible use of intestinal microbiome and factors affecting it have been discussed.

Pathogenic T cell cytokines in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system that is believed to have an autoimmune etiology. As MS is the most common nontraumatic disease that causes disability in young adults, extensive research has been devoted to identifying therapeutic targets. In this review, we discuss the current understanding derived from studies of patients with MS and animal models of how specific cytokines produced by autoreactive CD4 T cells contribute to the pathogenesis of MS. Defining the roles of these cytokines will lead to a better understanding of the potential of cytokine-based therapies for patients with MS.

Gut microbiota-dependent CCR9+CD4+ T cells are altered in secondary progressive multiple sclerosis

The mechanism underlying the progression of relapsing-remitting multiple sclerosis to secondary progressive multiple sclerosis (SPMS), characterized by accumulating fixed disability, is yet to be fully understood. Although alterations in the gut microbiota have recently been highlighted in multiple sclerosis pathogenesis, the mechanism linking the altered gut environment with the remote CNS pathology remains unclear. Here, we analyse human CD4⁺ memory T cells expressing the gut-homing chemokine receptor CCR9 and found a reduced frequency of CCR9⁺ memory T cells in the peripheral blood of patients with SPMS relative to healthy controls. The reduction in the proportion of CCR9⁺ cells among CD4⁺ memory T cells (%CCR9) in SPMS did not correlate with age, disease duration or expanded disability status scale score, although %CCR9 decreased linearly with age in healthy controls. During the clinical relapse of both, relapsing-remitting multiple sclerosis and neuromyelitis optica, a high proportion of cells expressing the lymphocyte activating 3 gene (LAG3) was detected among CCR9⁺ memory T cells isolated from the CSF, similar to that observed for mouse regulatory intraepithelial lymphocytes. In healthy individuals, CCR9⁺ memory T cells expressed higher levels of CCR6, a CNS-homing chemokine receptor, and exhibited a regulatory profile characterized by both the expression of C-MAF and the production of IL-4 and IL-10. However, in CCR9⁺ memory T cells, the expression of RORγt was specifically upregulated, and the production of IL-17A and IFNγ was high in patients with SPMS, indicating a loss of regulatory function. The evaluation of other cytokines supported the finding that CCR9⁺ memory T cells acquire a more inflammatory profile in SPMS, reporting similar aspects to CCR9⁺ memory T cells of the elderly healthy controls. CCR9⁺ memory T cell frequency decreased in germ-free mice, whereas antibiotic treatment increased their number in specific pathogen-free conditions. Here, we also demonstrate that CCR9⁺ memory T cells preferentially infiltrate into the inflamed CNS resulting from the initial phase and that they express LAG3 in the late phase in the experimental autoimmune encephalomyelitis mouse model of multiple sclerosis. Antibiotic treatment reduced experimental autoimmune encephalomyelitis symptoms and was accompanied by an increase in CCR9⁺ memory T cells in the peripheral blood. Antibodies against mucosal vascular addressin cell adhesion molecule 1 (MADCAM1), which is capable of blocking cell migration to the gut, also ameliorated experimental autoimmune encephalomyelitis. Overall, we postulate that the alterations in CCR9⁺ memory T cells observed, caused by either the gut microbiota changes or ageing, may lead to the development of SPMS.

Cerebrospinal Fluid and Blood Cytokines as Biomarkers for Multiple Sclerosis: A Systematic Review and Meta-Analysis of 226 Studies With 13,526 Multiple Sclerosis Patients

Background: Multiple sclerosis (MS) biomarker identification is important for pathogenesis research and diagnosis in routine clinical practice. Cerebrospinal fluid (CSF) and blood cytokines as potential biomarkers that can inform MS pathogenesis, diagnosis and response to treatment have been assessed in numerous studies. However, there have been no comprehensive meta-analyses to pool cytokine data and to address their diagnostic performance. We systematically reviewed literature with meta-analyses to assess the alteration levels of cytokines and chemokines in MS.

Methods: We searched PubMed and Web of Science for articles published between January 1, 1990 and April 30, 2018 for this systematic review and meta-analysis. Data were extracted from 226 included studies encompassing 13,526 MS patients and 8,428 controls. Biomarker performance was rated by a random-effects meta-analysis based on the standard mean difference between cytokine concentration in patients with MS and controls, or patients before and after treatments.

Results: Of the 26 CSF cytokines and 37 blood cytokines for potential differentiation between MS patients and controls, the random-effects meta-analysis showed that 13 CSF cytokines and 21 blood cytokines were significantly increased in MS patients in comparison to the controls. Interestingly, TNF-α, CXCL8, IL-15, IL-12p40, and CXCL13 were increased in both blood and CSF of MS patients. For those cytokines analyzed in at least 10 studies, differentiation between case and control was strong for CSF CXCL13, blood IL-2R, and blood IL-23; CSF CXCL8, blood IL-2, and blood IL-17 also performed well in differentiating between MS patients and controls, whereas those of CSF TNF-α and blood TNF-α, CXCL8, IL-12, IFN-γ were moderate. Furthermore, CSF IL-15, CCL19, CCL11, CCL-3, and blood CCL20, IL-12p40, IL-21, IL-17F, IL-22 had large effective sizes when differentiating between MS patients and controls but had a relatively small number of studies (three to seven studies).

Conclusion: Our findings clarified the circulating cytokine profile in MS, which provide targets for disease modifying treatments, and suggest that cytokines have the potential to be used as biomarkers for MS.

The Diversity of Encephalitogenic CD4+ T Cells in Multiple Sclerosis and Its Animal Models

Autoreactive CD4+ T cells, which target antigens in central nervous system (CNS) myelin, are widely believed to play a critical role in the pathogenesis of multiple sclerosis (MS) in concert with other immune effectors. This theory is supported by data from animal model experiments, genome-wide association studies, and immune profiles of individuals with MS. Furthermore, disease modifying agents that target lymphocytes significantly reduce the rate of MS clinical exacerbations. However, the properties of myelin-reactive CD4+ T cells that are critical for their pathogenic activities are not understood completely. This article reviews the literature on encephalitogenic CD4+ T cells, with an emphasis on T-helper (Th) lineage and cytokine production. An increased understanding of the spectrum of encephalitogenic T cells and how they differ from protective subsets is necessary for the development of the next generation of more effective and safer immunomodulatory therapies customized for individuals with MS and related disorders.

Innate Immune Responses and Viral-Induced Neurologic Disease

Multiple sclerosis (MS) is a disease of the central nervous system (CNS) characterized by chronic neuroinflammation, axonal damage, and demyelination. Cellular components of the adaptive immune response are viewed as important in initiating formation of demyelinating lesions in MS patients. This notion is supported by preclinical animal models, genome-wide association studies (GWAS), as well as approved disease modifying therapies (DMTs) that suppress clinical relapse and are designed to impede infiltration of activated lymphocytes into the CNS. Nonetheless, emerging evidence demonstrates that the innate immune response e.g., neutrophils can amplify white matter damage through a variety of different mechanisms. Indeed, using a model of coronavirus-induced neurologic disease, we have demonstrated that sustained neutrophil infiltration into the CNS of infected animals correlates with increased demyelination. This brief review highlights recent evidence arguing that targeting the innate immune response may offer new therapeutic avenues for treatment of demyelinating disease including MS.

Plasma cytokines as potential biomarkers of kidney damage in patients with systemic lupus erythematosus

Background

Systemic lupus erythematosus is a heterogeneous chronic inflammatory autoimmune disorder characterized by an exacerbated expression of cytokines and chemokines in different tissues and organs. Renal involvement is a significant contributor to the morbidity and mortality of systemic lupus erythematosus, and its diagnosis is based on renal biopsy, an invasive procedure with a high risk of complications. Therefore, the development of alternative, non-invasive diagnostic tests for kidney disease in patients with systemic lupus erythematosus is a priority.

Aim

To evaluate the plasma levels of a panel of cytokines and chemokines using multiplex xMAP technology in a cohort of Colombian patients with active and inactive systemic lupus erythematosus, and to evaluate their potential as biomarkers of renal involvement.

Results

Plasma from 40 systemic lupus erythematosus non-nephritis patients and 80 lupus nephritis patients with different levels of renal involvement were analyzed for 39 cytokines using Luminex xMAP technology. Lupus nephritis patients had significantly increased plasma eotaxin, TNF-α, interleukin-17-α, interleukin-10, and interleukin-15 as compared to the systemic lupus erythematosus non-nephritis group. Macrophage-derived chemokine, growth regulated oncogene alpha, and epidermal growth factor were significantly elevated in systemic lupus erythematosus non-nephritis patients when compared to lupus nephritis individuals. Plasma eotaxin levels allowed a discrimination between systemic lupus erythematosus non-nephritis and lupus nephritis patients, for which we performed a receiver operating characteristic curve to confirm. We observed a correlation of eotaxin levels with active nephritis (Systemic Lupus Erythematosus Disease Activity Index). Our data indicate that circulating cytokines and chemokines could be considered good predictors of renal involvement in individuals with systemic lupus erythematosus.

CNS-resident classical DCs play a critical role in CNS autoimmune disease

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system (CNS), induced by the adoptive transfer of myelin-reactive CD4+ T cells into naive syngeneic mice. It is widely used as a rodent model of multiple sclerosis (MS). The development of EAE lesions is initiated when transferred CD4+ T cells access the CNS and are reactivated by local antigen-presenting cells (APCs) bearing endogenous myelin peptide/MHC class II complexes. The identity of the CNS-resident, lesion-initiating APCs is widely debated. Here we demonstrate that classical dendritic cells (cDCs) normally reside in the meninges, brain, and spinal cord in the steady state. These cells are unique among candidate CNS APCs in their ability to stimulate naive, as well as effector, myelin-specific T cells to proliferate and produce proinflammatory cytokines directly ex vivo. cDCs expanded in the meninges and CNS parenchyma in association with disease progression. Selective depletion of cDCs led to a decrease in the number of myelin-primed donor T cells in the CNS and reduced the incidence of clinical EAE by half. Based on our findings, we propose that cDCs, and the factors that regulate them, be further investigated as potential therapeutic targets in MS.

Diagnostics of autoimmune neurodegeneration using fluorescent probing

The discovery of antibody-mediated catalysis was a breakthrough that showed antibody function is not limited to specific binding interactions, and that immunoglobulins (Igs) may also chemically transform their target antigens. Recently, so-called “natural catalytic antibodies” have been intimately linked with several pathologies, where they either protect the organism or contribute to the development of autoimmune abnormalities. Previously, we showed that myelin-reactive autoantibodies from patients with multiple sclerosis (MS) and mice with experimental autoimmune encephalomyelitis (EAE) exhibit the ability to recognize and hydrolyse distinct epitopes within myelin basic protein (MBP). Further, the antibody-mediated cleavage of encephalitogenic MBP peptide 81–103, flanked by two fluorescent proteins, can serve as a novel biomarker for MS. Here, we report the next generation of this biomarker, based on the antibody-mediated degradation of a novel chemically synthesized FRET substrate, comprising the fluorophore Cy5 and the quencher QXL680, interconnected by the MBP peptide 81–99: Cy5-MBP_81–99-QXL680. This substrate is degraded upon incubation with either purified antibodies from MS patients but not healthy donors or purified antibodies and splenocytes from EAE but not from non-immunized mice. Data presented herein suggest the elaboration of potential specific, rapid, and sensitive diagnostic criteria of active progressive MS.

The role of T cells in the pathogenesis of Parkinson's disease

Recent evidence has shown that neuroinflammation plays a key role in the pathogenesis of Parkinson's disease (PD). However, different components of the brain's immune system may exert diverse effects on neuroinflammatory events in PD. The adaptive immune response, especially the T cell response, can trigger type 1 pro-inflammatory activities and suppress type 2 anti-inflammatory activities, eventually resulting in deregulated neuroinflammation and subsequent dopaminergic neurodegeneration. Additionally, studies have increasingly shown that therapies targeting T cells can alleviate neurodegeneration and motor behavior impairment in animal models of PD. Therefore, we conclude that abnormal T cell-mediated immunity is a fundamental pathological process that may be a promising translational therapeutic target for Parkinson's disease.

Myeloid cell plasticity in the evolution of central nervous system autoimmunity

OBJECTIVE

Myeloid cells, including macrophages and dendritic cells, are a prominent component of central nervous system (CNS) infiltrates during multiple sclerosis (MS) and the animal model experimental autoimmune encephalomyelitis (EAE). Although myeloid cells are generally thought to be proinflammatory, alternatively polarized subsets can serve noninflammatory and/or reparative functions. Here we investigate the heterogeneity and biological properties of myeloid cells during central nervous system autoimmunity.

METHODS

Myeloid cell phenotypes in chronic active MS lesions were analyzed by immunohistochemistry. In addition, immune cells were isolated from the CNS during exacerbations and remissions of EAE and characterized by flow cytometric, genetic, and functional assays.

RESULTS

Myeloid cells expressing inducible nitric oxide synthase (iNOS), indicative of a proinflammatory phenotype, were detected in the actively demyelinating rim of chronic active MS lesions, whereas macrophages expressing mannose receptor (CD206), a marker of alternatively polarized human myeloid cells, were enriched in the quiescent lesion core. During EAE, CNS-infiltrating myeloid cells, as well as microglia, shifted from expression of proinflammatory markers to expression of noninflammatory markers immediately prior to clinical remissions. Murine CNS myeloid cells expressing the alternative lineage marker arginase-1 (Arg1) were partially derived from iNOS+ precursors and were deficient in activating encephalitogenic T cells compared with their Arg1- counterparts.

INTERPRETATION

These observations demonstrate the heterogeneity of CNS myeloid cells, their evolution during the course of autoimmune demyelinating disease, and their plasticity on the single cell level. Future therapeutic strategies for disease modification in individuals with MS may be focused on accelerating the transition of CNS myeloid cells from a proinflammatory to a noninflammatory phenotype. Ann Neurol 2018;83:131-141.

GM-CSF Promotes Chronic Disability in Experimental Autoimmune Encephalomyelitis by Altering the Composition of Central Nervous System-Infiltrating Cells, but Is Dispensable for Disease Induction

GM-CSF has been portrayed as a critical cytokine in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and, ostensibly, in multiple sclerosis. C57BL/6 mice deficient in GM-CSF are resistant to EAE induced by immunization with myelin oligodendrocyte glycoprotein (MOG)_35-55 The mechanism of action of GM-CSF in EAE is poorly understood. In this study, we show that GM-CSF augments the accumulation of MOG_35-55-specific T cells in the skin draining lymph nodes of primed mice, but it is not required for the development of encephalitogenic T cells. Abrogation of GM-CSF receptor signaling in adoptive transfer recipients of MOG_35-55-specific T cells did not alter the incidence of EAE or the trajectory of its initial clinical course, but it limited the extent of chronic CNS tissue damage and neurologic disability. The attenuated clinical course was associated with a relative dearth of MOG_35-55-specific T cells, myeloid dendritic cells, and neutrophils, as well as an abundance of B cells, within CNS infiltrates. Our data indicate that GM-CSF drives chronic tissue damage and disability in EAE via pleiotropic pathways, but it is dispensable during early lesion formation and the onset of neurologic deficits.

CCL11 is increased in the CNS in chronic traumatic encephalopathy but not in Alzheimer's disease

CCL11, a protein previously associated with age-associated cognitive decline, is observed to be increased in the brain and cerebrospinal fluid (CSF) in chronic traumatic encephalopathy (CTE) compared to Alzheimer's disease (AD). Using a cohort of 23 deceased American football players with neuropathologically verified CTE, 50 subjects with neuropathologically diagnosed AD, and 18 non-athlete controls, CCL11 was measured with ELISA in the dorsolateral frontal cortex (DLFC) and CSF. CCL11 levels were significantly increased in the DLFC in subjects with CTE (fold change = 1.234, p < 0.050) compared to non-athlete controls and AD subjects with out a history of head trauma. This increase was also seen to correlate with years of exposure to American football (β = 0.426, p = 0.048) independent of age (β = -0.046, p = 0.824). Preliminary analyses of a subset of subjects with available post-mortem CSF showed a trend for increased CCL11 among individuals with CTE (p = 0.069) mirroring the increase in the DLFC. Furthermore, an association between CSF CCL11 levels and the number of years exposed to football (β = 0.685, p = 0.040) was observed independent of age (β = -0.103, p = 0.716). Finally, a receiver operating characteristic (ROC) curve analysis demonstrated CSF CCL11 accurately distinguished CTE subjects from non-athlete controls and AD subjects (AUC = 0.839, 95% CI 0.62-1.058, p = 0.028). Overall, the current findings provide preliminary evidence that CCL11 may be a novel target for future CTE biomarker studies.

Th1 and Th17 Cells and Associated Cytokines Discriminate among Clinically Isolated Syndrome and Multiple Sclerosis Phenotypes

Multiple sclerosis (MS) is a chronic, inflammatory, and demyelinating disease of the central nervous system. It is a heterogeneous pathology that can follow different clinical courses, and the mechanisms that underlie the progression of the immune response across MS subtypes remain incompletely understood. Here, we aimed to determine differences in the immunological status among different MS clinical subtypes. Blood samples from untreated patients diagnosed with clinically isolated syndrome (CIS) (n = 21), different clinical forms of MS (n = 62) [relapsing–remitting (RRMS), secondary progressive, and primary progressive], and healthy controls (HCs) (n = 17) were tested for plasma levels of interferon (IFN)-γ, IL-10, TGF-β, IL-17A, and IL-17F by immunoanalysis. Th1 and Th17 lymphocyte frequencies were determined by flow cytometry. Our results showed that IFN-γ levels and the IFN-γ/IL-10 ratio were higher in CIS patients than in RRMS patients and HC. Th1 cell frequencies were higher in CIS and RRMS than in progressive MS, and RRMS had a higher Th17 frequency than CIS. The Th1/Th17 cell ratio was skewed toward Th1 in CIS compared to MS phenotypes and HC. Receiver operating characteristic statistical analysis determined that IFN-γ, the IFN-γ/IL-10 ratio, Th1 cell frequency, and the Th1/Th17 cell ratio discriminated among CIS and MS subtypes. A subanalysis among patients expressing high IL-17F levels showed that IL-17F and the IFN-γ/IL-17F ratio discriminated between disease subtypes. Overall, our data showed that CIS and MS phenotypes displayed distinct Th1- and Th17-related cytokines and cell profiles and that these immune parameters discriminated between clinical forms. Upon validation, these parameters might be useful as biomarkers to predict disease progression.

Galectin-8 as an immunosuppressor in experimental autoimmune encephalomyelitis and a target of human early prognostic antibodies in multiple sclerosis

Galectin-8 (Gal-8) is a member of a glycan-binding protein family that regulates the immune system, among other functions, and is a target of antibodies in autoimmune disorders. However, its role in multiple sclerosis (MS), an autoimmune inflammatory disease of the central nervous system (CNS), remains unknown. We study the consequences of Gal-8 silencing on lymphocyte subpopulations and the development of experimental autoimmune encephalitis (EAE), to then assess the presence and clinical meaning of anti-Gal-8 antibodies in MS patients. Lgals8/Lac-Z knock-in mice lacking Gal-8 expression have higher polarization toward Th17 cells accompanied with decreased CCR6⁺ and higher CXCR3⁺ regulatory T cells (Tregs) frequency. These conditions result in exacerbated MOG_35-55 peptide-induced EAE. Gal-8 eliminates activated Th17 but not Th1 cells by apoptosis and ameliorates EAE in C57BL/6 wild-type mice. β-gal histochemistry reflecting the activity of the Gal-8 promoter revealed Gal-8 expression in a wide range of CNS regions, including high expression in the choroid-plexus. Accordingly, we detected Gal-8 in human cerebrospinal fluid, suggesting a role in the CNS immune-surveillance circuit. In addition, we show that MS patients generate function-blocking anti-Gal-8 antibodies with pathogenic potential. Such antibodies block cell adhesion and Gal-8-induced Th17 apoptosis. Furthermore, circulating anti-Gal-8 antibodies associate with relapsing-remitting MS (RRMS), and not with progressive MS phenotypes, predicting clinical disability at diagnosis within the first year of follow-up. Our results reveal that Gal-8 has an immunosuppressive protective role against autoimmune CNS inflammation, modulating the balance of Th17 and Th1 polarization and their respective Tregs. Such a role can be counteracted during RRMS by anti-Gal-8 antibodies, worsening disease prognosis. Even though anti-Gal-8 antibodies are not specific for MS, our results suggest that they could be a potential early severity biomarker in RRMS.

Characterization of naïve, memory and effector T cells in progressive multiple sclerosis

We characterized naïve, central memory (CM), effector memory (EM) and terminally differentiated effector memory (TEMRA) CD4⁺ and CD8⁺ T cells and their expression of CD49d and CD26 in peripheral blood in patients with multiple sclerosis (MS) and healthy controls. CD26⁺ CD28⁺ CD4⁺ TEMRA T cells were increased in all subtypes of MS, and CD26⁺ CD28⁺ CD8⁺ TEMRA T cells were increased in relapsing-remitting and secondary progressive MS. Conversely, in progressive MS, CD49d⁺ CM T cells were decreased and natalizumab increased the circulating number of all six subsets but reduced the frequency of most subsets expressing CD49d and CD26.

A comparison of HMGB1 concentrations between cerebrospinal fluid and blood in patients with neurological disease

AIMS

To determine whether a correlation exists between paired cerebrospinal fluid (CSF) and serum levels of a novel inflammatory biomarker, high-mobility group box 1 (HMGB1), in different neurological conditions.

METHODS

HMGB1 was measured in the serum and CSF of 46 neurological patients (18 idiopathic intracranial hypertension [IIH], 18 neurological infection/inflammation [NII] and 10 Rasmussen's encephalitis [RE]).

RESULTS

Mean serum (± SD) HMGB1 levels were 1.43 ± 0.54, 25.28 ± 27.9 and 1.89 ± 1.49 ng/ml for the patients with IIH, NII and RE, respectively. Corresponding mean (± SD) CSF levels were 0.35 ± 0.22, 4.48 ± 6.56 and 2.24 ± 2.35 ng/ml. Both CSF and serum HMGB1 was elevated in NII. Elevated CSF HMGB1 was demonstrated in RE. There was no direct correlation between CSF and serum levels of HMGB1.

CONCLUSION

Serum HMGB1 cannot be used as a surrogate measure for CSF levels. CSF HMGB1 was elevated in NII and RE, its role as a prognostic/stratification biomarker needs further study.

iNKT Cells in Secondary Progressive Multiple Sclerosis Patients Display Pro-inflammatory Profiles

BACKGROUND

Multiple sclerosis (MS), an autoimmune disease with neurodegeneration and inflammation is characterized by several alterations of different T cell subsets. However, few data exist on the role of iNKT lymphocytes.

OBJECTIVE

To identify possible changes in the phenotype of iNKT cells in patients with different clinical forms of MS and find alterations in their polyfunctionality [i.e., ability to produce simultaneously up to four cytokines such as IL-17, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and IL-4].

METHODS

We studied a total of 165 patients, 91 with a relapsing-remitting form [RR; 31 were treated with interferon (IFN)1a-β, 25 with natalizumab (NAT), 29 with glatiramer acetate; 17 were newly diagnosed RR without treatment, 19 not-active RR without treatment]. Forty-four patients had a progressive MS: 20 primary progressive (PP) and 24 secondary progressive (SP). A total of 55 age- and sex-matched subjects represented healthy controls (CTR). Among fresh peripheral blood mononuclear cells, iNKT cells were identified by flow cytometry. Moreover, the capability of iNKT cells to produce different cytokines (IL-17, TNF-α, IFN-γ, and IL-4) after in vitro stimulation were evaluated in 18 RR (11 treated with NAT and 7 with IFN), 4 PP, 6 SP, and 16 CTR.

RESULTS

No main differences were found in iNKT cell phenotype among MS patients with different MS forms or during different treatments. However, the polyfunctional response of iNKT cells showed Th1 and Th17 profiles. This was well evident in patients with SP form, who are characterized by high levels of inflammation and neurodegeneration, and exhibited a sustained increase in the production of Th17 cytokines. Patients treated with NAT displayed lower levels of iNKT cells producing IL-17, TNF-α, and IFN-γ.

CONCLUSION

Our data suggest that the progressive phase of the disease is characterized by permanent iNKT activation and a skewing towards an inflammatory phenotype. Compared to other treatments, NAT was able to modulate iNKT cell function.

An emerging role for eotaxins in neurodegenerative disease

Eotaxins are C-C motif chemokines first identified as potent eosinophil chemoattractants. They facilitate eosinophil recruitment to sites of inflammation in response to parasitic infections as well as allergic and autoimmune diseases such as asthma, atopic dermatitis, and inflammatory bowel disease. The eotaxin family currently includes three members: eotaxin-1 (CCL11), eotaxin-2 (CCL24), and eotaxin-3 (CCL26). Despite having only ~30% sequence homology to one another, each was identified based on its ability to bind the chemokine receptor, CCR3. Beyond their role in innate immunity, recent studies have shown that CCL11 and related molecules may directly contribute to degenerative processes in the central nervous system (CNS). CCL11 levels increase in the plasma and cerebrospinal fluid of both mice and humans as part of normal aging. In mice, these increases are associated with declining neurogenesis and impaired cognition and memory. In humans, elevated plasma levels of CCL11 have been observed in Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, and secondary progressive multiple sclerosis when compared to age-matched, healthy controls. Since CCL11 is capable of crossing the blood-brain barrier of normal mice, it is plausible that eotaxins generated in the periphery may exert physiological and pathological actions in the CNS. Here, we briefly review known functions of eotaxin family members during innate immunity, and then focus on whether and how these molecules might participate in the progression of neurodegenerative diseases.

Distinct T cell signatures define subsets of patients with multiple sclerosis

OBJECTIVE

We investigated T cell responses to myelin proteins in the blood of healthy controls and 2 groups of patients with relapsing-remitting multiple sclerosis (RRMS) who exhibited lesions either predominantly in the brain or predominantly in the spinal cord in order to assess whether distinct neuroinflammatory patterns were associated with different myelin protein-specific T cell effector function profiles and whether these profiles differed from healthy controls.

METHODS

Peripheral blood mononuclear cells were obtained from patients with brain-predominant RRMS, patients with spinal cord-predominant RRMS, and age-matched healthy controls and analyzed by enzyme-linked immunosorbent spot assays to quantify interferon gamma-secreting (Th1) and interleukin 17-secreting (Th17) cells responding directly ex vivo to myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG).

RESULTS

Although MBP and MOG elicited different responses, patients with multiple sclerosis (MS) who had spinal cord-predominant lesions exhibited significantly higher Th17:Th1 ratios in response to both MBP and MOG compared to patients with brain-predominant MS. Incorporating the cytokine responses to both antigens into logistic regression models showed that these cytokine responses were able to provide good discrimination between patients with distinct neuroinflammatory patterns.

CONCLUSIONS

Our findings suggest that the localization of lesions within the brain vs the spinal cord in patients with MS is associated with different effector T cell responses to myelin proteins. Further investigation of the relationship between T cell effector function, antigen specificities, and lesion sites may reveal features of pathogenic pathways that are distinct to patients with different neuroinflammatory patterns.

Interleukin 17 alone is not a discriminant biomarker in early demyelinating spectrum disorders

BACKGROUND

Radiologically isolated syndrome (RIS) is a sub clinical demyelinating neurological disorder and to date no biomarker that triggers the seminal event has been identified. As for multiple sclerosis (MS), disease activity and clinical course are unpredictable. In MS, exploratory studies reported increased IL-17 levels in CSF but results in detecting IL-17 in serum at different stage of the disease are controversial.

OBJECTIVES

We investigate levels of IL-17 in serum and CSF in patients diagnosed at different stages of demyelinating diseases (RIS, CIS, relapsing remitting (RR) or active multiple sclerosis patients:AMS) as a marker of inflammatory condition.

METHODS

1417 sera has been tested for IL-17A (1177 from active MS, 80 RRMS, 35 RIS, 35 CIS, 10 IIH: idiopathic intracranial hypertension, and 80 controls) and 240 CSF from RIS, CIS, IIH and controls.

RESULTS

No difference has been found between RIS who early clinically converted and CIS patients who rapidly evolve in McDonald or clinically definite MS, nor active MS. No correlation was found with usual MRI or CSF criteria.

CONCLUSION

Our results do not confirm that IL-17 can be considerate as a reliable marker of inflammation in the demyelinating spectrum disorders, either in blood or CSF.

Autoantibodies to heterogeneous nuclear ribonuclear protein A1 (hnRNPA1) cause altered 'ribostasis' and neurodegeneration; the legacy of HAM/TSP as a model of progressive multiple sclerosis

Several years following its discovery in 1980, infection with human T-lymphotropic virus type 1 (HTLV-1) was shown to cause HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), a disease biologically similar to progressive forms of multiple sclerosis (MS). In this manuscript, we review some of the clinical, pathological, and immunological similarities between HAM/TSP and MS with an emphasis on how autoantibodies to an RNA binding protein, heterogeneous nuclear ribonuclear protein A1 (hnRNP A1), might contribute to neurodegeneration in immune mediated diseases of the central nervous system.

Neutrophils and viral-induced neurologic disease

Infection of the central nervous system (CNS) by neurotropic viruses represents an increasing worldwide problem in terms of morbidity and mortality for people of all ages. Although unique structural features of the blood-brain-barrier (BBB) provide a physical and physiological barrier, a number of neurotropic viruses are able to enter the CNS resulting in a variety of pathological outcomes. Nonetheless, antigen-specific lymphocytes are ultimately able to accumulate within the CNS and contribute to defense by reducing or eliminating the invading viral pathogen. Alternatively, infiltration of activated cells of the immune system may be detrimental, as these cells can contribute to neuropathology that may result in long-term cellular damage or death. More recently, myeloid cells e.g. neutrophils have been implicated in contributing to both host defense and disease in response to viral infection of the CNS. This review highlights recent studies using coronavirus-induced neurologic disease as a model to determine how neutrophils affect effective control of viral replication as well as demyelination.

IL-10-dependent Tr1 cells attenuate astrocyte activation and ameliorate chronic central nervous system inflammation

See Winger and Zamvil (doi: 10.1093/brain/aww121 ) for a scientific commentary on this article.

The innate immune system plays a central role in the chronic central nervous system inflammation that drives neurological disability in progressive forms of multiple sclerosis, for which there are no effective treatments. The mucosal immune system is a unique tolerogenic organ that provides a physiological approach for the induction of regulatory T cells. Here we report that nasal administration of CD3-specific antibody ameliorates disease in a progressive animal model of multiple sclerosis. This effect is IL-10-dependent and is mediated by the induction of regulatory T cells that share a similar transcriptional profile to Tr1 regulatory cells and that suppress the astrocyte inflammatory transcriptional program. Treatment results in an attenuated inflammatory milieu in the central nervous system, decreased microglia activation, reduced recruitment of peripheral monocytes, stabilization of the blood–brain barrier and less neurodegeneration. These findings suggest a new therapeutic approach for the treatment of progressive forms of multiple sclerosis and potentially other types of chronic central nervous system inflammation.

Lipocalin-2 is increased in progressive multiple sclerosis and inhibits remyelination

Objective:

We aimed to examine the regulation of lipocalin-2 (LCN2) in multiple sclerosis (MS) and its potential functional relevance with regard to myelination and neurodegeneration.

Methods:

We determined LCN2 levels in 3 different studies: (1) in CSF and plasma from a case-control study comparing patients with MS (n = 147) with controls (n = 50) and patients with relapsing-remitting MS (n = 75) with patients with progressive MS (n = 72); (2) in CSF and brain tissue microdialysates from a case series of 7 patients with progressive MS; and (3) in CSF at baseline and 60 weeks after natalizumab treatment in a cohort study of 17 patients with progressive MS. Correlation to neurofilament light, a marker of neuroaxonal injury, was tested. The effect of LCN2 on myelination and neurodegeneration was studied in a rat in vitro neuroglial cell coculture model.

Results:

Intrathecal production of LCN2 was increased predominantly in patients with progressive MS (p < 0.005 vs relapsing-remitting MS) and displayed a positive correlation to neurofilament light (p = 0.005). Levels of LCN2 in brain microdialysates were severalfold higher than in the CSF, suggesting local production in progressive MS. Treatment with natalizumab in progressive MS reduced LCN2 levels an average of 13% (p < 0.0001). LCN2 was found to inhibit remyelination in a dose-dependent manner in vitro.

Conclusions:

LCN2 production is predominantly increased in progressive MS. Although this moderate increase does not support the use of LCN2 as a biomarker, the correlation to neurofilament light and the inhibitory effect on remyelination suggest that LCN2 might contribute to neurodegeneration through myelination-dependent pathways.

Th Cell Diversity in Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

Multiple sclerosis (MS) is believed to be initiated by myelin-reactive CD4(+) Th cells. IL-12-polarized Th1 cells, IL-23-polarized Th17 cells, and Th17 cells that acquire Th1 characteristics were each implicated in autoimmune pathogenesis. It is debated whether Th cells that can drive the development of demyelinating lesions are phenotypically diverse or arise from a single lineage. In the current study, we assessed the requirement of IL-12 or IL-23 stimulation, as well as Th plasticity, for the differentiation of T cells capable of inducing CNS axon damage. We found that stable murine Th1 and Th17 cells independently transfer experimental autoimmune encephalomyelitis (widely used as an animal model of MS) in the absence of IL-23 and IL-12, respectively. Plastic Th17 cells are particularly potent mediators of demyelination and axonopathy. In parallel studies, we identified MS patients who consistently mount either IFN-γ- or IL-17-skewed responses to myelin basic protein over the course of a year. Brain magnetic resonance imaging revealed that patients with mixed IFN-γ and IL-17 responses have relatively high T1 lesion burden, a measure of permanent axon damage. Our data challenge the dogma that IL-23 and Th17 plasticity are universally required for the development of experimental autoimmune encephalomyelitis. This study definitively demonstrates that autoimmune demyelinating disease can be driven by distinct Th-polarizing factors and effector subsets, underscoring the importance of a customized approach to the pharmaceutical management of MS.

The conundrum of interferon-β non-responsiveness in relapsing-remitting multiple sclerosis

A series of controlled clinical trials have shown that exogenous interferon-beta (IFN-β) benefits patients with relapsing-remitting multiple sclerosis (RRMS) by reducing relapse rate, disability progression, and the formation of new brain and spinal cord lesions on magnetic resonance imaging (MRI) scans. Unfortunately, however, the effectiveness of IFN-β is limited in this setting by the occurrence of treatment non-responsiveness in nearly 25% of patients. Furthermore, clinicians who care for RRMS patients remain unable to accurately identify IFN-β non-responders prior to the initiation of therapy, causing delays in the use of alternative treatments and sometimes requiring that patients turn to medications with more significant side effects to control their disease. Progress has been made toward understanding how both endogenous and exogenous IFN-β act to slow RRMS as well as the related mouse model, experimental autoimmune encephalomyelitis (EAE). Most studies point to its inhibitory actions on circulating immune cells as being important for suppressing both disorders, but multiple potential target cells and inflammatory pathways have been implicated and those essential to confer its benefits remain undefined. This review focuses on the role of both endogenous and exogenous IFN-β in RRMS, paying particular attention to the issue of why certain individuals appear refractory to its disease-modifying effects. A continued goal in this field remains the identification of a convenient biomarker that accurately predicts IFN-β treatment non-responsiveness in individual RRMS patients. Development of such an assay will allow clinicians to customize therapy for patients with this complex disorder.