Soluble CD40 ligand contributes to blood–brain barrier breakdown and central nervous system inflammation in multiple sclerosis and neuromyelitis optica spectrum disorder

Development of an immunoassay for quantification of soluble human CD40L (CD154) in plasma and serum samples

When the membrane protein CD40 ligand (CD40L) on activated T cells binds the receptor CD40 on B-cells, it provides a co-stimulatory signal for B cell activation. Dysregulation of the CD40L:CD40 axis is associated with inflammatory and autoimmune diseases. The presence of soluble CD40L (sCD40L) in plasma is implicated in several diseases, from cardiovascular and autoimmune diseases to different types of cancer, and sCD40L has been suggested as a valuable marker of disease. If sCD40L is to be used as a biomarker, being able to precisely measure and quantify the levels of sCD40L in human blood samples is of utmost importance. We demonstrate the development of a sandwich-type time-resolved immunofluorometric assay for quantification of sCD40L in plasma or serum samples. For this, we generate 29 monoclonal anti-CD40L antibodies, and from these, we select the optimal combination of capture antibody and detection antibody. A number of variables were tested: the influence of the type of sample (comparing 3 different blood collection tubes for serum sampling and 4 different types of tubes for plasma sampling), the influence of freeze-thaw cycles, the influence of sampling time during night and day, and the influence of centrifugation of the samples. We found a very similar level of sCD40L in paired EDTA plasma and serum samples. Out of 100 healthy blood donor samples 61 had a level of sCD40L below the detection level of the assay, whereas the remaining 39 samples had ranging levels of sCD40L from 1.14 to 33.14 ng/mL. In summary, we present a time-resolved immunofluorometric assay based on paired monoclonal antibodies, ensuring high specificity, sensitivity, and homogeneity. The Eu3+-based assay additionally provides consistent assay readouts due to the extended decay time not seen in standard enzyme-linked immunosorbent assays. The assay paves the way for specific and consistent quantification of sCD40L in human plasma and serum samples.

Targeting Vascular Impairment, Neuroinflammation, and Oxidative Stress Dynamics with Whole-Body Cryotherapy in Multiple Sclerosis Treatment

Multiple sclerosis (MS), traditionally perceived as a neurodegenerative disease, exhibits significant vascular alternations, including blood-brain barrier (BBB) disruption, which may predispose patients to increased cardiovascular risks. This vascular dysfunction is intricately linked with the infiltration of immune cells into the central nervous system (CNS), which plays a significant role in perpetuating neuroinflammation. Additionally, oxidative stress serves not only as a byproduct of inflammatory processes but also as an active contributor to neural damage. The synthesis of these multifaceted aspects highlights the importance of understanding their cumulative impact on MS progression. This review reveals that the triad of vascular damage, chronic inflammation, and oxidative imbalance may be considered interdependent processes that exacerbate each other, underscoring the need for holistic and multi-targeted therapeutic approaches in MS management. There is a necessity for reevaluating MS treatment strategies to encompass these overlapping pathologies, offering insights for future research and potential therapeutic interventions. Whole-body cryotherapy (WBCT) emerges as one of the potential avenues for holistic MS management approaches which may alleviate the triad of MS progression factors in multiple ways.

Contribution of platelets to disruption of the blood-brain barrier during arterial baroreflex dysfunction

BACKGROUND

Arterial baroreflex dysfunction, like many other central nervous system disorders, involves disruption of the blood-brain barrier, but what causes such disruption in ABR dysfunction is unclear. Here we explored the potential role of platelets in this disruption.

METHODS

ABR dysfunction was induced in rats using sinoaortic denervation, and the effects on integrity of the blood-brain barrier were explored based on leakage of Evans blue or FITC-dextran, while the effects on expression of CD40L in platelets and of key proteins in microvascular endothelial cells were explored using immunohistochemistry, western blotting and enzyme-linked immunosorbent assay. Similar experiments were carried out in rat brain microvascular endothelial cell line, which we exposed to platelets taken from rats with ABR dysfunction.

RESULTS

Sinoaortic denervation permeabilized the blood-brain barrier and downregulated zonula occludens-1 and occludin in rat brain, while upregulating expression of CD40L on the surface of platelets and stimulating platelet aggregation. Similar effects of permeabilization and downregulation were observed in healthy rats that received platelets from animals with ABR dysfunction, and in rat brain microvascular endothelial cells, but only in the presence of lipopolysaccharide. These effects were associated with activation of NF-κB signaling and upregulation of matrix metalloprotease-9. These effects of platelets from animals with ABR dysfunction were partially blocked by neutralizing antibody against CD40L or the platelet inhibitor clopidogrel.

CONCLUSION

During ABR dysfunction, platelets may disrupt the blood-brain barrier when CD40L on their surface activates NF-kB signaling within cerebral microvascular endothelial cells, leading to upregulation of matrix metalloprotease-9. Our findings imply that targeting CD40L may be effective against cerebral diseases involving ABR dysfunction.

Inhibition of CD40L with Frexalimab in Multiple Sclerosis

BACKGROUND

The CD40-CD40L costimulatory pathway regulates adaptive and innate immune responses and has been implicated in the pathogenesis of multiple sclerosis. Frexalimab is a second-generation anti-CD40L monoclonal antibody being evaluated for the treatment of multiple sclerosis.

METHODS

In this phase 2, double-blind, randomized trial, we assigned, in a 4:4:1:1 ratio, participants with relapsing multiple sclerosis to receive 1200 mg of frexalimab administered intravenously every 4 weeks (with an 1800-mg loading dose), 300 mg of frexalimab administered subcutaneously every 2 weeks (with a 600-mg loading dose), or the matching placebos for each active treatment. The primary end point was the number of new gadolinium-enhancing T1-weighted lesions seen on magnetic resonance imaging at week 12 relative to week 8. Secondary end points included the number of new or enlarging T2-weighted lesions at week 12 relative to week 8, the total number of gadolinium-enhancing T1-weighted lesions at week 12, and safety. After 12 weeks, all the participants could receive open-label frexalimab.

RESULTS

Of 166 participants screened, 129 were assigned to a trial group; 125 participants (97%) completed the 12-week double-blind period. The mean age of the participants was 36.6 years, 66% were women, and 30% had gadolinium-enhancing lesions at baseline. At week 12, the adjusted mean number of new gadolinium-enhancing T1-weighted lesions was 0.2 (95% confidence interval [CI], 0.1 to 0.4) in the group that received 1200 mg of frexalimab intravenously and 0.3 (95% CI, 0.1 to 0.6) in the group that received 300 mg of frexalimab subcutaneously, as compared with 1.4 (95% CI, 0.6 to 3.0) in the pooled placebo group. The rate ratios as compared with placebo were 0.11 (95% CI, 0.03 to 0.38) in the 1200-mg group and 0.21 (95% CI, 0.08 to 0.56) in the 300-mg group. Results for the secondary imaging end points were generally in the same direction as those for the primary analysis. The most common adverse events were coronavirus disease 2019 and headaches.

CONCLUSIONS

In a phase 2 trial involving participants with multiple sclerosis, inhibition of CD40L with frexalimab had an effect that generally favored a greater reduction in the number of new gadolinium-enhancing T1-weighted lesions at week 12 as compared with placebo. Larger and longer trials are needed to determine the long-term efficacy and safety of frexalimab in persons with multiple sclerosis. (Funded by Sanofi; ClinicalTrials.gov number, NCT04879628.).

Blood-brain barrier dysfunction in multiple sclerosis: causes, consequences, and potential effects of therapies

Established by brain endothelial cells, the blood-brain barrier (BBB) regulates the trafficking of molecules, restricts immune cell entry into the CNS, and has an active role in neurovascular coupling (the regulation of cerebral blood flow to support neuronal activity). In the early stages of multiple sclerosis, around the time of symptom onset, inflammatory BBB damage is accompanied by pathogenic immune cell infiltration into the CNS. In the later stages of multiple sclerosis, dysregulation of neurovascular coupling is associated with grey matter atrophy. Genetic and environmental factors associated with multiple sclerosis, including dietary habits, the gut microbiome, and vitamin D concentrations, might contribute directly and indirectly to brain endothelial cell dysfunction. Damage to brain endothelial cells leads to an influx of deleterious molecules into the CNS, accelerating leakage across the BBB. Potential future therapeutic approaches might help to prevent BBB damage (eg, monoclonal antibodies targeting cell adhesion molecules and fibrinogen) and help to repair BBB dysfunction (eg, mesenchymal stromal cells) in people with multiple sclerosis.

Targeting the blood-brain barrier to delay aging-accompanied neurological diseases by modulating gut microbiota, circadian rhythms, and their interplays

The blood-brain barrier (BBB) impairment plays a crucial role in the pathological processes of aging-accompanied neurological diseases (AAND). Meanwhile, circadian rhythms disruption and gut microbiota dysbiosis are associated with increased morbidity of neurological diseases in the accelerated aging population. Importantly, circadian rhythms disruption and gut microbiota dysbiosis are also known to induce the generation of toxic metabolites and pro-inflammatory cytokines, resulting in disruption of BBB integrity. Collectively, this provides a new perspective for exploring the relationship among circadian rhythms, gut microbes, and the BBB in aging-accompanied neurological diseases. In this review, we focus on recent advances in the interplay between circadian rhythm disturbances and gut microbiota dysbiosis, and their potential roles in the BBB disruption that occurs in AAND. Based on existing literature, we discuss and propose potential mechanisms underlying BBB damage induced by dysregulated circadian rhythms and gut microbiota, which would serve as the basis for developing potential interventions to protect the BBB in the aging population through targeting the BBB by exploiting its links with gut microbiota and circadian rhythms for treating AAND.

Advances in immune checkpoint-based immunotherapies for multiple sclerosis: rationale and practice

Beyond the encouraging results and broad clinical applicability of immune checkpoint (ICP) inhibitors in cancer therapy, ICP-based immunotherapies in the context of autoimmune disease, particularly multiple sclerosis (MS), have garnered considerable attention and hold great potential for developing effective therapeutic strategies. Given the well-established immunoregulatory role of ICPs in maintaining a balance between stimulatory and inhibitory signaling pathways to promote immune tolerance to self-antigens, a dysregulated expression pattern of ICPs has been observed in a significant proportion of patients with MS and its animal model called experimental autoimmune encephalomyelitis (EAE), which is associated with autoreactivity towards myelin and neurodegeneration. Consequently, there is a rationale for developing immunotherapeutic strategies to induce inhibitory ICPs while suppressing stimulatory ICPs, including engineering immune cells to overexpress ligands for inhibitory ICP receptors, such as program death-1 (PD-1), or designing fusion proteins, namely abatacept, to bind and inhibit the co-stimulatory pathways involved in overactivated T-cell mediated autoimmunity, and other strategies that will be discussed in-depth in the current review. Video Abstract.

Gut microbiota dysbiosis associated with different types of demyelinating optic neuritis in patients

BACKGROUND

Demyelinating optic neuritis (DON) causes rapid vision loss in young and middle-aged people. The limited efficacy of treatment and the toxic side effects of drugs significantly affect the quality of life of patients with DON. Therefore, DON pathogenesis has always been a research hotspot in terms of prevention and treatment. Studies have suggested that gut microbiota imbalances may be involved in autoimmune disease development via the modulation of multiple inflammatory cytokines and anti-inflammatory metabolites. Therefore, this study aims to explore gut microbiota differences between healthy controls (HCs) and patients with DON.

METHODS

A total of 54 patients with DON and 41 HCs were recruited. Fecal and blood samples were collected before and after intravenous methylprednisolone pulse (IVMP) treatment. The Shannon index, gut microbiota structure, and differential bacteria were evaluated and compared.

RESULTS

The Shannon diversity index was decreased in patients with DON (p < 0.001) but was higher after IVMP treatment (p < 0.05). In patients with DON, Blautia, Escherichia-Shigella, and Ruminococcus showed higher abundances, whereas Bacteroides, Faecalibacterium, Roseburia, Parabacteroides, Romboutsia, and Alistipes showed lower abundances compared to that in the HCs. After IVMP treatment, the Shannon index of the myelin oligodendrocyte glycoprotein-immunoglobulin G (+) (MOG-IgG (+)) and both aquaporin-4 (AQP4)-IgG (-) and MOG-IgG (-) groups increased (p < 0.05). Bacteroides was negatively correlated with interleukin (IL)-21, IL-17E, and tumor necrosis factor-α levels (p < 0.05, r = -0.54; p < 0.05, r= -0.50; p < 0.05, r =-0.55, respectively). Escherichia was positively correlated with macrophage inflammatory protein-3α (p < 0.05, r = 0.51). Alistipes was negatively correlated with soluble CD40 ligand (p < 0.05, r = -0.52).

CONCLUSION

The gut microbiota differed significantly between patients with DON and HCs; however, IVMP treatment may restore gut microbiota diversity and structure in patients with DON. Moreover, gut microbiota changes may play a role in DON pathogenesis.

Effects of intermittent hypoxia with thrombin in an in vitro model of human brain endothelial cells and their impact on PAR-1/PAR-3 cleavage

Patients with obstructive sleep apnea/hypopnea (OSA) are at high risk of cerebrovascular diseases leading to cognitive impairment. The oxidative stress generated by intermittent hypoxia (IH) could lead to an increase in blood-brain barrier (BBB) permeability, an essential interface for the protection of the brain. Moreover, in patients with OSA, blood coagulation could be increased leading to cardiovascular complications. Thrombin is a factor found increased in these populations that exerts various cellular effects through activation of protease activated receptors (PARs). Thus, we have evaluated in an in vitro BBB model the association of IH with thrombin at two concentrations. We measured the apparent BBB permeability, expression of tight junctions, ROS production, HIF-1α expression, and cleavage of PAR-1/PAR-3. Pre-treatment with dabigatran was performed. IH and higher thrombin concentrations altered BBB permeability: high levels of HIF-1α expression, ROS and PAR-1 activation compared to PAR-3 in such conditions. Conversely, lower concentration of thrombin associated with IH appear to have a protective effect on BBB with a significant cleavage of PAR-3. Dabigatran reversed the deleterious effect of thrombin at high concentrations but also suppressed the beneficial effect of low dose thrombin. Therefore, thrombin and PARs represent novel attractive targets to prevent BBB opening in OSA.

Emerging therapies to target CNS pathophysiology in multiple sclerosis

The rapidly evolving therapeutic landscape of multiple sclerosis (MS) has contributed to paradigm shifts in our understanding of the biological mechanisms that contribute to CNS injury and in treatment philosophies. Opportunities remain to further improve treatment of relapsing-remitting MS, but two major therapeutic gaps are the limiting of progressive disease mechanisms and the repair of CNS injury. In this Review, we provide an overview of selected emerging therapies that predominantly target processes within the CNS that are thought to be involved in limiting non-relapsing, progressive disease injury or promoting tissue repair. Among these, we consider agents that modulate adaptive and innate CNS-compartmentalized inflammation, which can be mediated by infiltrating immune cells and/or resident CNS cells, including microglia and astrocytes. We also discuss agents that target degenerative disease mechanisms, agents that might confer neuroprotection, and agents that create a more favourable environment for or actively contribute to oligodendrocyte precursor cell differentiation, remyelination and axonal regeneration. We focus on agents that are novel for MS, that are known to or are presumed to penetrate the CNS, and that have already entered early stages of development in MS clinical trials.

CD40-CD40L in Neurological Disease

Immune-inflammatory conditions in the central nervous system (CNS) rely on molecular and cellular interactions which are homeostatically maintained to protect neural tissue from harm. The CD40–CD40L interaction upregulates key proinflammatory molecules, a function best understood in the context of infection, during which B-cells are activated via CD40 signaling to produce antibodies. However, the role of CD40 in neurological disease of non-infectious etiology is unclear. We review the role of CD40–CD40L in traumatic brain injury, Alzheimer’s Disease, Parkinson’s Disease, stroke, epilepsy, nerve injury, multiple sclerosis, ALS, myasthenia gravis and brain tumors. We also highlight therapeutic advancements targeting the CD40 system to either attenuate the neuroinflammatory response or leverage the downstream effects of CD40 signaling for direct tumor cell lysis.

Dysregulated CD40 and CD40 ligand expression in anti-N-methyl-d-aspartate receptor encephalitis

Anti-N-methyl-d-aspartate receptor encephalitis (anti-NMDARE) is a B cell- and antibody-mediated autoimmune disease which may be regulated by CD40/CD40L signaling pathway. we enrolled anti-NMDARE patients and measured the serum CD40 and CD40L concentrations. The serum concentration of CD40 was decreased, while CD40L was increased in anti-NMDARE patients compared with that of healthy controls. The concentrations of CD40 and CD40L were both elevated in the acute stage of anti-NMDARE and were reduced during remission. Serum CD40L levels were positively correlated with serum CD40 levels. These results revealed that the CD40/CD40L signaling pathway might contribute to the pathogenesis of anti-NMDARE.

Dendritic Cell-Targeted Therapies to Treat Neurological Disorders

Dendritic cells (DCs) are the immune system's highly specialized antigen-presenting cells. When DCs are sluggish and mature, self-antigen presentation results in tolerance; however, when pathogen-associated molecular patterns stimulate mature DCs, antigen presentation results in the development of antigen-specific immunity. DCs have been identified in various vital organs of mammals (e.g., the skin, heart, lungs, intestines, and spleen), but the brain has long been thought to be devoid of DCs in the absence of neuroinflammation. However, neuroinflammation is becoming more recognized as a factor in a variety of brain illnesses. DCs are present in the brain parenchyma in trace amounts under healthy circumstances, but their numbers rise during neuroinflammation. New therapeutics are being developed that can reduce dendritic cell immunogenicity by inhibiting pro-inflammatory cytokine production and T cell co-stimulatory pathways. Additionally, innovative ways of regulating dendritic cell growth and differentiation and harnessing their tolerogenic capability are being explored. Herein, we described the function of dendritic cells in neurological disorders and discussed the potential for future therapeutic techniques that target dendritic cells and dendritic cell-related targets in the treatment of neurological disorders.

CD40L protects against mouse hepatitis virus-induced neuroinflammatory demyelination

Neurotropic mouse hepatitis virus (MHV-A59/RSA59) infection in mice induces acute neuroinflammation due to direct neural cell dystrophy, which proceeds with demyelination with or without axonal loss, the pathological hallmarks of human neurological disease, Multiple sclerosis (MS). Recent studies in the RSA59-induced neuroinflammation model of MS showed a protective role of CNS-infiltrating CD4⁺ T cells compared to their pathogenic role in the autoimmune model. The current study further investigated the molecular nexus between CD4⁺ T cell-expressed CD40Ligand and microglia/macrophage-expressed CD40 using CD40L^-/- mice. Results demonstrate CD40L expression in the CNS is modulated upon RSA59 infection. We show evidence that CD40L^-/- mice are more susceptible to RSA59 induced disease due to reduced microglia/macrophage activation and significantly dampened effector CD4⁺ T recruitment to the CNS on day 10 p.i. Additionally, CD40L^-/- mice exhibited severe demyelination mediated by phagocytic microglia/macrophages, axonal loss, and persistent poliomyelitis during chronic infection, indicating CD40-CD40L as host-protective against RSA59-induced demyelination. This suggests a novel target in designing prophylaxis for virus-induced demyelination and axonal degeneration, in contrast to immunosuppression which holds only for autoimmune mechanisms of inflammatory demyelination.

MS is primarily considered an autoimmune CNS disease, but its potential viral etiology cannot be ignored. Myelin-specific CD40L⁺CD4⁺ T cells migration into the CNS and resultant neuroinflammation is considered pathogenic in autoimmune MS. In contrast, CD40L⁺CD4⁺ T infiltration into the MHV-induced inflamed CNS and their interaction with CD40⁺ microglia/macrophages are shown to be protective in our study. Considering differential etiology but comparable demyelination and axonal loss, immunosuppressive treatments may not necessarily ameliorate MS in all patients. MHV-induced demyelination in this study indicates that the interaction between CD40L on CD4⁺T cells and CD40 on microglia/macrophage plays an important protective role against MHV-induced chronic progressive demyelination.

Elevated sCD40L in Secondary Progressive Multiple Sclerosis in Comparison to Non-progressive Benign and Relapsing Remitting Multiple Sclerosis

Background

The long-term prognosis of relapsing-remitting multiple sclerosis (RRMS) is usually unfavorable as most patients transition to secondary progressive multiple sclerosis (SPMS) with accumulative disability. A rare form of non-progressive multiple sclerosis (MS) also exists, known as benign MS (BMS or NPMS), which lacks disease progression defined as Expanded Disability Status Scale (EDSS) ≤3 after 15 years of disease onset without treatment.

Purpose

Our study aims to identify soluble plasma factors predicting disease progression in multiple sclerosis (MS).

Research Design and Study Sample

We utilized Luminex multiplex to analyze plasma levels of 33 soluble factors, comparing 32 SPMS patients to age-, sex-, and disease duration-matched non-progressive BMS patients, as well as to RRMS patients and healthy controls.

Results

Plasma levels of EGF, sCD40L, MCP1/CCL2, fractalkine/CX3CL1, IL-13, Eotaxin, TNFβ/LTα, and IL-12p40 were significantly different between the various types of MS. Plasma sCD40L was significantly elevated in SPMS compared to BMS and RRMS. The combination of MCP1/CCL2 and sCD40L discriminated between RRMS and SPMS. MCP1/CCL2 was found to be the most effective classifier between BMS and RRMS, while BMS was most effectively distinguished from SPMS by the combination of sCD40L and IFNγ levels.

Conclusions

These differences may facilitate personalized precision medicine and aid in the discovery of new therapeutic targets for disease progression through the improvement of patient stratification.

Platelet Inhibition by Low-Dose Acetylsalicylic Acid Reduces Neuroinflammation in an Animal Model of Multiple Sclerosis

Aside from the established immune-mediated etiology of multiple sclerosis (MS), compelling evidence implicates platelets as important players in disease pathogenesis. Specifically, numerous studies have highlighted that activated platelets promote the central nervous system (CNS)-directed adaptive immune response early in the disease course. Platelets, therefore, present a novel opportunity for modulating the neuroinflammatory process that characterizes MS. We hypothesized that the well-known antiplatelet agent acetylsalicylic acid (ASA) could inhibit neuroinflammation by affecting platelets if applied at low-dose and investigated its effect during experimental autoimmune encephalomyelitis (EAE) as a model to study MS. We found that oral administration of low-dose ASA alleviates symptoms of EAE accompanied by reduced inflammatory infiltrates and less extensive demyelination. Remarkably, the percentage of CNS-infiltrated CD4+ T cells, the major drivers of neuroinflammation, was decreased to 40.98 ± 3.28% in ASA-treated mice compared to 56.11 ± 1.46% in control animals at the disease maximum as revealed by flow cytometry. More interestingly, plasma levels of thromboxane A2 were decreased, while concentrations of platelet factor 4 and glycoprotein VI were not affected by low-dose ASA treatment. Overall, we demonstrate that low-dose ASA could ameliorate the platelet-dependent neuroinflammatory response in vivo, thus indicating a potential treatment approach for MS.

Correlation between IL-31 and sCD40L plasma levels in Fingolimod-treated patients with Relapsing-Remitting Multiple Sclerosis (RRMS)

INTRODUCTION

Multiple Sclerosis (MS) is a chronic, autoimmune, demyelinating disease of the central nervous system (CNS). Currently, several protocols are described for the different phases of MS. In this longitudinal study, we aim to quantify the concentration of plasma cytokines of MS patients treated with Fingolimod alone or after Glatiramer Acetate (GA) or Interferon-beta (IFN-β), in order to compeer both treatments and describes if it is possible to use them as biomarkers.

OBJECTIVE

Compare the two different types of drug treatment and describes possible immune biomarkers in RRMS patients treated with Fingolimod alone or after GA or IFN-β.

MATERIALS AND METHODS

This is a controlled, non-randomized clinical trial. Plasma concentrations of IL-31, sCD40L and nine others cytokines were evaluated in two groups of patients with a one-year follow-up. Group 1 (n = 12): RRMS patients treated with GA or IFN-β for at least six months before the study who changed therapy to Fingolimod after six months, and Group 2 (n = 12): naïve RRMS patients who started treatment with Fingolimod. We used ANOVA two-way to analyze the cytokines and Spearman coefficient to evaluate the correlation.

RESULTS

Although Group 2 started with a greater number of relapses per disease duration, Fingolimod treatment was effective in decreasing this parameter, as well as EDSS over 12 months. However, the treatment with GA or IFN-β on Group 1 showed a tendency to increase the number of relapses after 6 months of follow-up, which decrease when the therapy was changed to Fingolimod. After the evaluation of 11 cytokines in one year, we found that IL-31 and sCD40L were the biomarkers that demonstrated a more difference when compared to the classical ones, following the clinical pattern over the treatment period.

CONCLUSIONS

Our study describes the existence of two promising plasmatic biomarkers (IL-31 and sCD40L), which reduced plasmatic levels in RRMS patients followed the treatment time of Fingolimod, despite that more studies are needed to prove their efficiency.

Metabolomic Profiling in Neuromyelitis Optica Spectrum Disorder Biomarker Discovery

There is no specific test for diagnosing neuromyelitis optica spectrum disorder (NMOSD), a disabling autoimmune disease of the central nervous system. Instead, diagnosis relies on ruling out other related disorders with overlapping clinical symptoms. An urgency for NMOSD biomarker discovery is underscored by adverse responses to treatment following misdiagnosis and poor prognosis following the delayed onset of treatment. Pathogenic autoantibiotics that target the water channel aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) contribute to NMOSD pathology. The importance of early diagnosis between AQP4-Ab⁺ NMOSD, MOG-Ab⁺ NMOSD, AQP4-Ab⁻ MOG-Ab⁻ NMOSD, and related disorders cannot be overemphasized. Here, we provide a comprehensive data collection and analysis of the currently known metabolomic perturbations and related proteomic outcomes of NMOSD. We highlight short chain fatty acids, lipoproteins, amino acids, and lactate as candidate diagnostic biomarkers. Although the application of metabolomic profiling to individual NMOSD patient care shows promise, more research is needed.

A profile of multiple circulating tumor necrosis factor receptors associated with early progressive kidney decline in Type 1 Diabetes is similar to profiles in autoimmune disorders

This study comprehensively evaluated the association between known circulating tumor necrosis factor (TNF) superfamily ligands and receptors and the development of early progressive kidney decline (PKD) leading to end-stage kidney disease (ESKD) in Type 1 diabetes. Participants for the study were from the Macro-Albuminuria Study (198 individuals), and the Micro-Albuminuria Study (148 individuals) of the Joslin Kidney Study. All individuals initially had normal kidney function and were followed for seven-fifteen years to determine the slope of the estimate glomerular filtration rate and to ascertain onset of ESKD. Plasma concentrations of 25 TNF superfamily proteins were measured using proximity extension assay applied in the OLINK proteomics platform. In the both studies risk of early PKD, determined as estimated glomerular filtration rate loss greater than or equal to three ml/min/1.73m²/year, was associated with elevated circulating levels of 13 of 19 TNF receptors examined. In the Macro-Albuminuria Study, we obtained similar findings for risk of progression to ESKD. These receptors comprised: TNF-R1A, -R1B, -R3, -R4, -R6, -R6B, -R7, -R10A, -R10B, -R11A, -R14, -R21, and -R27. Serial measurements showed that circulating levels of these TNF receptors had increased before the onset of PKD. In contrast, none of the six measured TNF ligands showed association with risk of early PKD. Of significance, the disease process that underlies PKD leading to ESKD in Type 1 diabetes has a profile also seen in autoimmune disorders. The mechanisms of this enrichment may be causally related to the development of PKD in Type 1 diabetes and must be investigated further. Thus, some of these receptors may be used as new risk predictors of ESKD.

Peroxiredoxins are involved in the pathogenesis of multiple sclerosis and neuromyelitis optica spectrum disorder

Peroxiredoxins (PRXs) are intracellular anti-oxidative enzymes but work as inflammatory amplifiers under the extracellular condition. To date, the function of PRXs in the pathogenesis of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) is not fully understood. The aim of this study was to investigate whether PRXs play a role in the pathogenesis of MS and NMOSD. We analyzed levels of PRXs (PRX1, PRX5 and PRX6) in the cerebrospinal fluid (CSF) and serum of 16 patients with MS, 16 patients with NMOSD and 15 patients with other neurological disorders (ONDs). We identified potential correlations between significantly elevated PRXs levels and the clinical variables in patients with MS and NMOSD. Additionally, pathological analyses of PRXs (PRX1-6) in the central nervous system (CNS) were performed using the experimental autoimmune encephalomyelitis (EAE), animal model of MS. We found that serum levels of PRX5 and PRX6 in patients with MS and NMOSD were higher compared with those in patients with ONDs (P < 0·05). Furthermore, high levels of PRX5 and PRX6 were partly associated with blood-brain barrier dysfunction and disease duration in NMOSD patients. No significant elevation was found in CSF PRXs levels of MS and NMOSD. Spinal cords from EAE mice showed remarkable PRX5 staining, especially in CD45⁺ infiltrating cells. In conclusion, PRX5 and PRX6 may play a role in the pathogeneses of MS and NMOSD.

Different roles of soluble CD40 ligand in central nervous system damage

Backgroud and purpose: Soluble CD40 ligand (sCD40L) plays an important role in inflammation and autoimmune disorders. There is still a controversy regarding sCD40L in neuromyelitis optica spectrum disorders (NMOSD) and multiple sclerosis (MS). Herein the aims of this study were to evaluate the levels of sCD40L in patients with NMOSD, MS, and other noninflammatory neurological diseases; to investigate its potential relationship with laboratory parameters, glial fibrillary acidic protein (GFAP), thrombopoietin (TPO) and IL-6; and to address whether serum sCD40L levels in acute attacks of NMOSD patients were decreased after treatment with immunoglobulins, plasma exchange, or methylprednisolone.Materials and methods: We enrolled 13 patients with NMOSD, 9 patients with MS, and 9 patients with other noninflammatory neurological diseases. The levels of sCD40L, IL-6 were measured by cytokine multiplex assay. GFAP levels were measured by ELISA.Results: Both serum and cerebrospinal fluid (CSF) sCD40L levels were increased in NMOSD and MS. No differences were found in serum and CSF sCD40L levels between NMOSD and MS. The CSF sCD40L levels were positively correlated with the CSF cell counts in NMOSD, whereas serum sCD40L levels were positively correlated with the albumin index in MS. Furthermore, the levels of CSF sCD40L were positively correlated with CSF GFAP levels in NMOSD. Serum sCD40L levels were correlated with serum TPO levels in MS. No correlation was found between levels of sCD40L and IL-6 in NMOSD and MS. No statistically meaningful difference between NMOSD patients with or without immunotherapy. Conclusions: Our study suggests that sCD40L can contribute to the destruction of the blood-brain barrier in MS, whereas it may contribute to CNS inflammation in NMOSD. The serum sCD40L concentrations were not changed after treatment with immunoglobulins, plasma exchange, or methylprednisolone in acute attacks of NMOSD.

Cytokine/chemokine dysregulation in progressive MS patient is apparent and can be modulated by calpain inhibition

This study examines the cytokine/chemokine profile of a 62-year-old African American male with progressive multiple sclerosis (MS). MRI images of the MS patient demonstrated generalized white matter involvement with multiple lesions in the periventricular area. A 42-plex Discovery Assay® (Eve Technologies) of the patient's plasma and peripheral blood mononuclear cells (PBMCs) supernatant or PBMC-derived T cell supernatant samples from two separate clinic visits revealed vastly differing cytokine/chemokine levels. In addition, certain cytokine/chemokine profiles had notable differences when compared to the larger patient group or patients' PBMCs treated with a calpain inhibitor in vitro. Interestingly, large numbers of cytokines/chemokines and growth factors in MS PBMCs are modulated by calpain inhibition, suggesting the clinical significance of these findings in designing better therapeutics against progressive MS.

Decreased mRNA Expressions of CD40L in Patients with Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease that preferentially affects central nerve system. Herein, we evaluated changes of CD40L and CD40 mRNA expressions in NMOSD and controls to explore their potential roles in development of NMOSD. The expressions of CD40L and CD40 mRNA in peripheral blood mononuclear cells (PBMCs) from patients with NMOSD and healthy controls were detected by quantitative real-time PCR (qPCR). Kruskal-Wallis tests were used to compare expression levels of CD40L and CD40 mRNA between groups, and Spearman correlation analysis was performed to evaluate correlation between mRNA expression levels and annual relapse rate (ARR) of NMOSD. A total of 71 patients with NMOSD and 42 gender- and age-matched healthy volunteers were recruited in our study. Compared with healthy controls, expression of CD40L mRNA was significantly decreased in untreated patients with NMOSD, and similar trends were observed also in CD40 mRNA expression although the difference was not significant. Other than that, immunosuppressants not only successfully increased CD40L and CD40 mRNA levels during remission of NMOSD, but also corrected the negative correlation between CD40L mRNA expression and annual relapse rate (ARR) of patients NMOSD. These results favored the long-term prognosis of NMOSD patients. Our results suggest that decreased expressions of CD40L mRNA may be involved in developing of NMOSD and the proper CD40L mRNA levels benefit to prevent attacks of NMOSD. Nevertheless, the relationship between protein and mRNA expressions of CD40L and their underlying roles in the pathogenesis of NMOSD remains to be further studied.

The clinical value of the albumin quotient in patients with neuromyelitis optica spectrum disorder

BACKGROUND

The disruption of the blood-brain barrier (BBB) is common in patients with neuromyelitis optica spectrum disorder (NMOSD), causing pro-inflammatory immune cells to migrate into the central nervous system (CNS) and active demyelinating lesions. Albumin quotient is commonly used as an indicator for BBB permeability or dysfunction, but its potential clinical value in NMOSD treatment has never been explored. The present study investigated the differences in the albumin quotient level among NMOSD patients with different antibodies (AQP4-IgG and MOG-IgG) and the relationship between the albumin quotient and neurological dysfunction.

METHODS

We retrospectively collected data from 141 patients with NMOSD (104 with AQP4-IgG and 37 with MOG-IgG) and reviewed their clinical features and albumin quotient levels.

RESULTS

The percentage of patients with an abnormal albumin quotient was significantly higher in the MOG-IgG group than in the AQP4-IgG group (48.6% vs 27.9%, P = 0.026); albumin quotient levels in the AQP4-IgG-positive group were similar to those in the MOG-IgG groups (5.65 vs 5.8, P = 0.23). Among those with an abnormal quotient, no differences in the proportions of severe neurological disability across treatment were found between patients with AQP4-IgG and those with MOG-IgG (pre-treatment: AQP4-IgG group vs MOG-IgG group: 58.6% vs 38.9%, P = 0.24; post-treatment: AQP4-IgG group vs MOG-IgG group: 31.0% vs 22.2%, P = 0.74).

CONCLUSIONS

The BBB breakdown in NMOSD patients with MOG-IgG may be more common than in those with AQP4-IgG. AQP4-IgG-positive patients and MOG-IgG-positive patients with severe neurological disability tend to exhibit similar disruptions to the BBB.

Role of Blood-Brain Barrier in Alzheimer's Disease

The blood-brain barrier (BBB) is involved in the pathogenesis of Alzheimer's disease (AD). BBB is a highly selective semipermeable structural and chemical barrier which ensures a stable internal environment of the brain and prevents foreign objects invading the brain tissue. BBB dysfunction induces the failure of Aβ transport from brain to the peripheral circulation across the BBB. Especially, decreased levels of LRP-1 (low density lipoprotein receptor-related protein 1) and increased levels of RAGE (receptor for advanced glycation endproducts) at the BBB can cause the failure of Aβ transport. The pathogenesis of AD is related to the BBB structural components, including pericytes, astrocytes, vascular endothelial cells, and tight junctions. BBB dysfunction will trigger neuroinflammation and oxidative stress, then enhance the activity of β-secretase and γ-secretase, and finally promote Aβ generation. A progressive accumulation of Aβ in brain and BBB dysfunction may become a feedback loop that gives rise to cognitive impairment and the onset of dementia. The correlation between BBB dysfunction and tau pathology has been well-reported. Therefore, regulating BBB function may be a new therapeutic target for treating AD.

Targeting the CD40-CD40L pathway in autoimmune diseases: Humoral immunity and beyond

CD40 is a TNF receptor superfamily member expressed on both immune and non-immune cells. Interactions between B cell-expressed CD40 and its binding partner, CD40L, predominantly expressed on activated CD4+ T cells, play a critical role in promoting germinal center formation and the production of class-switched antibodies. Non-hematopoietic cells expressing CD40 can also engage CD40L and trigger a pro-inflammatory response. This article will highlight what is known about the biology of the CD40-CD40L axis in humans and describe the potential contribution of CD40 signaling on both hematopoietic and non-hematopoietic cells to autoimmune disease pathogenesis. Additionally, novel therapeutic approaches to target this pathway, currently being evaluated in clinical trials, are discussed.

Increased expression of the membrane-bound CD40 ligand on peripheral CD4+ T cells in the acute phase of AQP4-IgG-seropositive neuromyelitis optica spectrum disorders

Currently, no data are available regarding the expression levels of CD40L on CD4⁺ T cells in patients with neuromyelitis optica spectrum disorders (NMOSD). The percentage of circulating CD40L⁺CD4⁺ T cells was measured by flow cytometry in 23 NMOSD patients and 10 healthy controls. The ratio of CD40L⁺CD4⁺ to CD4⁺ T cells in patients at acute phase (18.28 ± 15.56%) was significantly higher than that in healthy controls (7.23 ± 5.94%, P = .032) and was positively correlated with disease severity (r = 0.532, P = .041). Thus, our results suggest an important role of this molecule in acute attacks of NMOSD.

Distinct Cytokine and Chemokine Expression in Plasma and Calpeptin-Treated PBMCs of a Relapsing-Remitting Multiple Sclerosis Patient: A Case Report

The cytokine/chemokine expression signature of a 60-year-old African American male with relapsing-remitting multiple sclerosis (RRMS) was analyzed using patient blood samples obtained from two separate visits to the clinic. Thirty-six different cytokines, chemokines, and growth factors were detected in the plasma of the RRMS patient using a multiplexed bead-based immunoassay. Results indicated that at least ten of these factors with a concentration of > 100 pg/mL are identified as pro-inflammatory. Calpain inhibition led to an anti-inflammatory effect, as indicated by a decrease in expression of pro-inflammatory cytokines/chemokines such as GM-CSF, IFNγ, and IL-17A, and a relative increase in two of the anti-inflammatory cytokines (IL-13 and IL-4) in the peripheral blood mononuclear cells activated with anti-CD3/CD28. Overall, these results suggest that the unique cytokine/chemokine pattern observed in the plasma of the RRMS patient can be used as a prognostic marker and calpain inhibition may be used as a novel therapeutic strategy for treating excessive inflammatory response specific to RRMS patients.

Blood Brain Barrier Permeability Could Be a Biomarker to Predict Severity of Neuromyelitis Optica Spectrum Disorders: A Retrospective Analysis

Background: Blood-brain barrier (BBB) pathology exists in neuromyelitis optica spectrum disorders (NMOSD). However, the clinical use of BBB permeability, such as predicting disease severity of NMOSD, has rarely been studied in a large cohort of patients.

Objectives: The current study explored the association between BBB permeability and clinical parameters in order to assess if BBB permeability could be a biomarker to predict disease severity and clinical characteristics of NMOSD.

Methods: Among 69 enrolled NMOSD patients, 47 with albumin index over 5 × 10⁻³ were assigned to the increased BBB permeability group, and the remaining 22 were to the normal BBB permeability group. Disease severity was assessed using the Expanded Disability Status Scale (EDSS).

Results: Patients in the increased BBB permeability group had significantly higher EDSS scores, anti-aquporin-4 immunoglobulin G titers, more dense cerebrospinal fluid protein concentrations, white blood cell counts, myelin basic protein levels and more dense complement 3 concentrations than found in the comparative normal BBB permeability group. The albumin index was positively correlated to the length of lesions in spinal cord.

Conclusions: BBB permeability was associated with clinical features, laboratory results and radiological data of NMOSD patients, and may be a potential biomarker to predict disease severity and clinical characteristics of NMOSD.

DNA damage induced by human CD40 ligand mutant promotes senescence and induces demethylation of GATA4 in lung cancer

The ligand of CD40, known as CD154 or CD40L, is the key to immunostimulatory and anticancer activity, but how CD40L affects cellular senescence is unclear. Thus, we studied a membrane-stable mutant form CD40L (CD40L-M) to explore tumor growth and cellular senescence in CD40-positive NSCLC cells. We found that CD40L-M-expressing cells had senescent characteristics, including reduced cell proliferation and enlargement, increased SA-β-gal staining activity, and overexpression of several cell cycle regulators p53 and p21. In addition, expression of GATA4 was restored, and the NF-κB signaling pathway was activated in the CD40L-M-induced senescent cells. Mechanistic analyses revealed that CD40L-M expression triggered the ATM/Chk2 DNA damage response, which mediated cell senescence and GATA4 activation. Knockdown of GATA4 reversed CD40L-M-induced senescence and decreased NF-κB activity. Thus, CD40L-M contributes to induction of cell senescence in CD40-positive NSCLC cells, and GATA4 is a switch to activate the NF-κB pathway, which is positively regulated by DNA damage response (DDR) signaling kinases. Collectively, CD40L-M-induced senescence may be a barrier to the growth of lung cancer cells.

Soluble CD40 ligand disrupts the blood-brain barrier and exacerbates inflammation in experimental autoimmune encephalomyelitis

Serum soluble CD40 ligand (sCD40L) has been reported to positively correlate with the albumin quotient, a marker of blood-brain barrier (BBB) breakdown, in patients with multiple sclerosis (MS). To clarify the mechanisms of sCD40L in MS pathophysiology, sCD40L was administered to experimental autoimmune encephalomyelitis (EAE) mice and a human brain microvascular endothelial cell (HBMEC)-based BBB model. The high-dose sCD40L group showed a worse EAE score than the low-dose and control groups. BBB permeability was increased by administering sCD40L in a HBMEC-based BBB model. Thus, sCD40L induces more severe inflammation in the central nervous system by disrupting the BBB.

The CD40-CD40L Dyad in Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

The CD40-CD40L dyad is an immune checkpoint regulator that promotes both innate and adaptive immune responses and has therefore an essential role in the development of inflammatory diseases, including multiple sclerosis (MS). In MS, CD40 and CD40L are expressed on immune cells present in blood and lymphoid organs, affected resident central nervous system (CNS) cells, and inflammatory cells that have infiltrated the CNS. CD40-CD40L interactions fuel the inflammatory response underlying MS, and both genetic deficiency and antibody-mediated inhibition of the CD40-CD40L dyad reduce disease severity in experimental autoimmune encephalomyelitis (EAE). Both proteins are therefore attractive therapeutic candidates to modulate aberrant inflammatory responses in MS. Here, we discuss the genetic, experimental and clinical studies on the role of CD40 and CD40L interactions in EAE and MS and we explore novel approaches to therapeutically target this dyad to combat neuroinflammatory diseases.

Gut reactions: How the blood-brain barrier connects the microbiome and the brain

A growing body of evidence indicates that the microbiome interacts with the central nervous system (CNS) and can regulate many of its functions. One mechanism for this interaction is at the level of the blood-brain barriers (BBBs). In this minireview, we examine the several ways the microbiome is known to interact with the CNS barriers. Bacteria can directly release factors into the systemic circulation or can translocate into blood. Once in the blood, the microbiome and its factors can alter peripheral immune cells to promote interactions with the BBB and ultimately with other elements of the neurovascular unit. Bacteria and their factors or cytokines and other immune-active substances released from peripheral sites under the influence of the microbiome can cross the BBB, alter BBB integrity, change BBB transport rates, or induce release of neuroimmune substances from the barrier cells. Metabolic products produced by the microbiome, such as short-chain fatty acids, can cross the BBB to affect brain function. Through these and other mechanisms, microbiome-BBB interactions can influence the course of diseases as illustrated by multiple sclerosis. Impact statement The connection between the gut microbiome and central nervous system (CNS) disease is not fully understood. Host immune systems are influenced by changes to the microbiota and offers new treatment strategies for CNS disease. Preclinical studies provide evidence of changes to the blood-brain barrier when animals are subject to experimental gut infection or when the animals lack a normal gut microbiome. The intestine also contains a barrier, and bacterial factors can translocate to the blood and interact with host immune cells. These metastatic bacterial factors can signal T-cells to become more CNS penetrant, thus providing a novel intervention for treating CNS disease. Studies in humans show the therapeutic effects of T-cell engineering for the treatment of leukemia, so perhaps a similar approach for CNS disease could prove effective. Future research should begin to define the bacterial species that can cause immune cells to differentiate and how these interactions vary amongst CNS disease models.