Efficacy of Disease Modifying Therapies in Progressive MS and How Immune Senescence May Explain Their Failure

Association between peripheral blood immunological status and intrathecal inflammatory markers differentiate multiple sclerosis clinical phenotypes

BACKGROUND

The difference in the clinical course, response to therapy, and distribution of CNS inflammation in primary-progressive (PPMS) and relapsing-remitting multiple sclerosis (RRMS) suggests differences in the underlying immunological characteristics of the disease. We aimed to investigate differences in immunological profiles in relation to intrathecal inflammation in different MS forms.

METHODS

The peripheral blood (PB) proportions of CD4 + and CD8 + T-cells and CD19 + B-cells were retrospectively compared with the markers of intrathecal immunoglobulin G (IgG) synthesis at diagnosis: IgG index, percentage of intrathecal IgG synthesis (IF IgG), the number of oligoclonal bands (OCB), depending on the blood-brain barrier (BBB) function, and antibody specific index to neurotrophic viruses (MRZH reaction).

RESULTS

Thirty-six controls, 71 RRMS and 25 PPMS were enrolled. PPMS had higher percentage of CD4 + T-cells compared to RRMS (P = 0.043) and controls (P = 0.003). The percentage of CD8 + T-cells and CD19 + B-cells, and respective absolute cell counts did not differ according to the MS phenotype. In RRMS with the dysfunctional BBB, the IgG index (r = 0.642, P = 0.012) correlated significantly with the CD19 + B-cells while the CD4 + T-cells inversely correlated with IF IgG (r=-0.574, P = 0.039). Interestingly, in PPMS the number of OCB was positively associated with CD4+ (r = 0.603, P = 0.015) and negatively associated with CD8 + T-cells (r=-0.554, P = 0.033), while IF IgG negatively correlated with CD8 + T-cells (r=-0.689, P = 0.003), but only in the preserved BBB function.

CONCLUSIONS

The PB CD4 + T-cells and B-cells were associated with the intrathecal inflammation in RRMS with BBB dysfunction while CD8 + T-cells were involved in PPMS with CNS-compartmentalized inflammation.

Macrophages and HLA-Class II Alleles in Multiple Sclerosis: Insights in Therapeutic Dynamics

Antigen presentation is a crucial mechanism that drives the T cell-mediated immune response and the development of Multiple Sclerosis (MS). Genetic alterations within the highly variable Major Histocompatibility Complex Class II (MHC II) have been proven to result in significant changes in the molecular basis of antigen presentation and the clinical course of patients with both Adult-Onset MS (AOMS) and Pediatric-Onset MS (POMS). Among the numerous polymorphisms of the Human Leucocyte Antigens (HLA), within MHC II complex, HLA-DRB1*15:01 has been labeled, in Caucasian ethnic groups, as a high-risk allele for MS due to the ability of its structure to increase affinity to Myelin Basic Protein (MBP) epitopes. This characteristic, among others, in the context of the trimolecular complex or immunological synapsis, provides the foundation for autoimmunity triggered by environmental or endogenous factors. As with all professional antigen presenting cells, macrophages are characterized by the expression of MHC II and are often implicated in the formation of MS lesions. Increased presence of M1 macrophages in MS patients has been associated both with progression and onset of the disease, each involving separate but similar mechanisms. In this critical narrative review, we focus on macrophages, discussing how HLA genetic alterations can promote dysregulation of this population's homeostasis in the periphery and the Central Nervous System (CNS). We also explore the potential interconnection in observed pathological macrophage mechanisms and the function of the diverse structure of HLA alleles in neurodegenerative CNS, seen in MS, by comparing available clinical with molecular data through the prism of HLA-immunogenetics. Finally, we discuss available and experimental pharmacological approaches for MS targeting the trimolecular complex that are based on cell phenotype modulation and HLA genotype involvement and try to reveal fertile ground for the potential development of novel drugs.

Immunopathogenesis of multiple sclerosis: molecular and cellular mechanisms and new immunotherapeutic approaches

BACKGROUND

Multiple sclerosis (MS) is a central nervous system (CNS) demyelinating autoimmune disease with increasing global prevalence. It predominantly affects females, especially those of European descent. The interplay between environmental factors and genetic predisposition plays a crucial role in MS etiopathogenesis.

METHODS

We searched recent relevant literature on reputable databases, which include, PubMed, Embase, Web of Science, Scopus, and ScienceDirect using the following keywords: multiple sclerosis, pathogenesis, autoimmunity, demyelination, therapy, and immunotherapy.

RESULTS

Various animal models have been employed to investigate the MS etiopathogenesis and therapeutics. Autoreactive T cells within the CNS recruit myeloid cells through chemokine expression, leading to the secretion of inflammatory cytokines driving the MS pathogenesis, resulting in demyelination, gliosis, and axonal loss. Key players include T cell lymphocytes (CD4+ and CD8+), B cells, and neutrophils. Signaling dysregulation in inflammatory pathways and the immunogenetic basis of MS are essential considerations for any successful therapy to MS. Data indicates that B cells and neutrophils also have significant roles in MS, despite the common belief that T cells are essential. High neutrophil-to-lymphocyte ratios correlate with MS severity, indicating their contribution to disease progression. Dysregulated signaling pathways further exacerbate MS progression.

CONCLUSION

MS remains incurable, but disease-modifying therapies, monoclonal antibodies, and immunomodulatory drugs offer hope for patients. Research on the immunogenetics and immunoregulatory functions of gut microbiota is continuing to provide light on possible treatment avenues. Understanding the complex interplay between genetic predisposition, environmental factors, and immune dysregulation is critical for developing effective treatments for MS.

Role of B Cells in Relapsing-Remitting and Progressive Multiple Sclerosis and Long-Term Effects of B Cell Depletion

Depletion of circulating B lymphocytes using anti-CD20 monoclonal antibodies (mAbs) greatly reduces inflammatory activity in relapsing multiple sclerosis (RMS); it reduces progression to a lesser extent in nonrelapsing progressive MS. Mechanisms whereby anti-CD20 mAbs reduce MRI and clinical relapse activity in people with RMS are still being elucidated. Anti-CD20 agents do not fully protect from nonrelapsing disease progression, possibly due to their inability to cross the blood-brain barrier and inability to ameliorate the full extent of biology of MS progression. Anti-CD20 mAbs have a relatively favorable safety profile, at least in the short-term. Long-term safety studies are still needed.

Current knowledge on multiple sclerosis pathophysiology, disability progression assessment and treatment options, and the role of autologous hematopoietic stem cell transplantation

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) that affects nearly 2.8 million people each year. MS distinguishes three main types: relapsing-remitting MS (RRMS), secondary progressive MS (SPMS) and primary progressive MS (PPMS). RRMS is the most common type, with the majority of patients eventually progressing to SPMS, in which neurological development is constant, whereas PPMS is characterized by a progressive course from disease onset. New or additional insights into the role of effector and regulatory cells of the immune and CNS systems, Epstein-Barr virus (EBV) infection, and the microbiome in the pathophysiology of MS have emerged, which may lead to the development of more targeted therapies that can halt or reverse neurodegeneration. Depending on the type and severity of the disease, various disease-modifying therapies (DMTs) are currently used for RRMS/SPMS and PPMS. As a last resort, and especially in highly active RRMS that does not respond to DMTs, autologous hematopoietic stem cell transplantation (AHSCT) is performed and has shown good results in reducing neuroinflammation. Nevertheless, the question of its potential role in preventing disability progression remains open. The aim of this review is to provide a comprehensive update on MS pathophysiology, assessment of MS disability progression and current treatments, and to examine the potential role of AHSCT in preventing disability progression.

From Animal Models to Clinical Trials: The Potential of Antimicrobials in Multiple Sclerosis Treatment

Multiple sclerosis (MS) is a chronic, autoimmune, demyelinating disease of the central nervous system (CNS). Microbes, including bacteria and certain viruses, particularly Epstein-Barr virus (EBV), have been linked to the pathogenesis of MS. While there is currently no cure for MS, antibiotics and antivirals have been studied as potential treatment options due to their immunomodulatory ability that results in the regulation of the immune process. The current issue addressed in this systematic review is the effect of antimicrobials, including antibiotics, antivirals, and antiparasitic agents in animals and humans. We performed a comprehensive search of PubMed, Google Scholar, and Scopus for articles on antimicrobials in experimental autoimmune encephalomyelitis animal models of MS, as well as in people with MS (pwMS). In animal models, antibiotics tested included beta-lactams, minocycline, rapamycin, macrolides, and doxycycline. Antivirals included acyclovir, valacyclovir, and ganciclovir. Hydroxychloroquine was the only antiparasitic that was tested. In pwMS, we identified a total of 24 studies, 17 of them relevant to antibiotics, 6 to antivirals, and 1 relevant to antiparasitic hydroxychloroquine. While the effect of antimicrobials in animal models was promising, only minocycline and hydroxychloroquine improved outcome measures in pwMS. No favorable effect of the antivirals in humans has been observed yet. The number and size of clinical trials testing antimicrobials have been limited. Large, multicenter, well-designed studies are needed to further evaluate the effect of antimicrobials in MS.

Safety and efficacy of cladribine in multiple sclerosis: a systematic review and meta-analysis

BACKGROUND

Previously, several studies investigated the effect of cladribine among patients with multiple sclerosis (MS) as a treatment option. Due to the contradictory results of previous studies regarding the efficacy and safety of cladribine in the MS population, we aimed to conduct a systematic review and meta-analysis by including clinical trials and observational studies in terms of having more confirmative results to make a general decision.

METHODS

The three databases including PubMed, Scopus, and Web of Science were comprehensively searched in May 2022. We included the studies that investigated the efficacy and safety of cladribine in patients with MS. Eligible studies have to provide sufficient details on MS diagnosis and appropriate follow-up duration. We investigated the efficacy of cladribine with several outcomes including Expanded Disability Status Scale (EDSS) change, progression-free survival (PFS), relapse-free survival (RFS), and MRI-free activity survival (MFAS).

RESULTS

After two-step reviewing, 23 studies were included in our qualitative and quantitative synthesis. The pooled SMD for EDSS before and after treatment was - 0.54 (95%CI: - 1.46, 0.39). Our analysis showed that the PFS after cladribine use is 79% (95%CI 71%, 86%). Also, 58% of patients with MS who received cladribine remained relapse-free (95%CI 31%, 83%). Furthermore, the MFAS after treatment was 60% (95%CI 36%, 81%). Our analysis showed that infection is the most common adverse event after cladribine treatment with a pooled prevalence of 10% (95%CI 4%, 18%). Moreover, the pooled prevalence of infusion-related adverse events was 9% (95%CI 4%, 15%). Also, the malignancies after cladribine were present in 0.4% of patients (95%CI 0.25%, 0.75%).

CONCLUSION

Our results showed acceptable safety and efficacy for cladribine for the treatment of MS except in terms of reducing EDSS. Combination of our findings with the results of previous studies which compared cladribine to other disease-modifying therapies (DMTs), cladribine seems to be a safe and effective drug in achieving better treatment for relapsing-remitting MS (RRMS) patients.

Treatment of older patients with multiple sclerosis: Results of an International Delphi Survey

Background

People over age 50-55 have historically been excluded from randomized clinical trials for multiple sclerosis (MS). However, more than half of those living with an MS diagnosis are over 55.

Objective

Explore the unique considerations of treating older people with MS (PwMS) using an iterative and structured Delphi-based assessment to gather expert opinions.

Methods

Eight MS neurologists with an interest in older PwMS developed a 2-round survey. Survey respondents were qualified neurologists with ≥3 years' experience, personally responsible for treatment decisions, and treating ≥20 patients per month, of whom ≥10% were ≥50 years old. Consensus was defined as ≥75% agreement on questions with categorical responses or as a mean score ≥4 on questions with numerical responses.

Results

In Survey 1, 224 neurologists responded; 180 of these completed Survey 2. Limited consensus was reached with varying levels of agreement on several topics including identification and assessment of older patients; factors relating to treatment decisions including immunosenescence and comorbidities; considerations for high-efficacy treatments; de-escalation or discontinuation of treatment; effects of COVID-19; and unmet needs for treating this population.

Conclusion

The results of this Delphi process highlight the need for targeted studies to create guidance for the care of older PwMS.

Specific alterations in NKG2D+ T lymphocytes in relapsing-remitting and progressive multiple sclerosis patients

BACKGROUND

T lymphocytes exhibit numerous alterations in relapsing-remitting (RRMS), secondary progressive (SPMS), and primary progressive multiple sclerosis (PPMS). The NKG2D pathway has been involved in MS pathology. NKG2D is a co-activating receptor on subsets of CD4⁺ and most CD8⁺ T lymphocytes. The ligands of NKG2D are expressed at low levels in normal tissues but are elevated in MS postmortem brain tissues compared with controls. Whether the NKG2D pathway shows specific changes in different forms of MS remains unclear.

METHODS

We performed unsupervised and supervised flow cytometry analysis to characterize peripheral blood T lymphocytes from RRMS, SPMS, and PPMS patients and healthy controls (HC). We used an in vitro microscopy approach to assess the role of NKG2D in the interactions between human CD8⁺T lymphocytes and human astrocytes.

RESULTS

Specific CD8⁺, CD4⁺, and CD4^-CD8^- T cell populations exhibited altered frequency in MS patients' subgroups. The proportion of NKG2D⁺ T lymphocytes declined with age in PPMS patients but not in RRMS and HC. This reduced percentage of NKG2D⁺ cells was due to lower abundance of γδ and αβ CD4^-CD8^- T lymphocytes in PPMS patients. NKG2D⁺ T lymphocytes were significantly less abundant in RRMS than in HC; this was caused by a decreased frequency of CD4^-CD8^- and CD8⁺ T lymphocytes and was not linked to age. Blocking NKG2D increased the motility of CD8⁺ T lymphocytes co-cultured with astrocytes expressing NKG2D ligand. Moreover, preventing NKG2D from interacting with its ligands increased the proportion of CD8⁺ T lymphocytes exhibiting a kinapse-like behavior characterized by short-term interaction while reducing those displaying a long-lasting synapse-like behavior. These results support that NKG2D participates in the establishment of long-term interactions between activated CD8⁺ T lymphocytes and astrocytes.

CONCLUSION

Our data demonstrate specific alterations in NKG2D⁺ T lymphocytes in MS patients' subgroups and suggest that NKG2D contributes to the interactions between human CD8⁺ T lymphocytes and human astrocytes.

Motor Behavioral Deficits in the Cuprizone Model: Validity of the Rotarod Test Paradigm

Multiple Sclerosis (MS) is a neuroinflammatory disorder, which is histopathologically characterized by multifocal inflammatory demyelinating lesions affecting both the central nervous system’s white and grey matter. Especially during the progressive phases of the disease, immunomodulatory treatment strategies lose their effectiveness. To develop novel progressive MS treatment options, pre-clinical animal models are indispensable. Among the various different models, the cuprizone de- and remyelination model is frequently used. While most studies determine tissue damage and repair at the histological and ultrastructural level, functional readouts are less commonly applied. Among the various overt functional deficits, gait and coordination abnormalities are commonly observed in MS patients. Motor behavior is mediated by a complex neural network that originates in the cortex and terminates in the skeletal muscles. Several methods exist to determine gait abnormalities in small rodents, including the rotarod testing paradigm. In this review article, we provide an overview of the validity and characteristics of the rotarod test in cuprizone-intoxicated mice.

The role of the complement system in Multiple Sclerosis: A review

The complement system has been involved in the pathogenesis of multiple neuroinflammatory and neurodegenerative conditions. In this review, we evaluated the possible role of complement activation in multiple sclerosis (MS) with a focus in progressive MS, where the disease pathogenesis remains to be fully elucidated and treatment options are limited. The evidence for the involvement of the complement system in the white matter plaques and gray matter lesions of MS stems from immunohistochemical analysis of post-mortem MS brains, in vivo serum and cerebrospinal fluid biomarker studies, and animal models of Experimental Autoimmune Encephalomyelitis (EAE). Complement knock-out studies in these animal models have revealed that this system may have a “double-edge sword” effect in MS. On the one hand, complement proteins may aid in promoting the clearance of myelin degradation products and other debris through myeloid cell-mediated phagocytosis. On the other, its aberrant activation may lead to demyelination at the rim of progressive MS white matter lesions as well as synapse loss in the gray matter. The complement system may also interact with known risk factors of MS, including as Epstein Barr Virus (EBV) infection, and perpetuate the activation of CNS self-reactive B cell populations. With the mounting evidence for the involvement of complement in MS, the development of complement modulating therapies for this condition is appealing. Herein, we also reviewed the pharmacological complement inhibitors that have been tested in MS animal models as well as in clinical trials for other neurologic diseases. The potential use of these agents, such as the C5-binding antibody eculizumab in MS will require a detailed understanding of the role of the different complement effectors in this disease and the development of better CNS delivery strategies for these compounds.