Cerebrospinal fluid sulfatide isoforms lack diagnostic utility in separating progressive from relapsing-remitting multiple sclerosis

Ongoing phase 2 agents for multiple sclerosis: could we break the phase 3 trial deadlock?

INTRODUCTION

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease of the central nervous system. While disease-modifying therapies have significantly improved the management of relapsing MS, progressive MS remains a major clinical challenge.

AREAS COVERED

This review provides a general overview of recent and ongoing phase 2 clinical trials investigating treatments for MS, summarizing emerging results when available. The trials are categorized based on the desired therapeutic effect: immunomodulatory treatments, neuroprotection, and remyelination. A comprehensive literature search was conducted using databases such as PubMed and ClinicalTrials.gov to identify relevant studies, with a focus on promising therapies that address both inflammatory and neurodegenerative processes in MS.

EXPERT OPINION

Despite promising results from phase 2 trials, many phase 3 trials fail to demonstrate significant efficacy. This discrepancy is partly due to limitations in biomarkers, which often lack disease specificity and fail to predict long-term outcomes. Additionally, smaller, narrowly focused phase 2 trials may overestimate efficacy, leading to challenges when transitioning to larger, more inclusive phase 3 trials. Recruitment of patients with less aggressive disease further complicates phase 3 success. Addressing these challenges requires the refinement of biomarkers, adoption of unified definitions for outcomes like progression independent of relapse activity (PIRA), and trial designs that better capture the complexity of MS progression.

CSF sphingolipids are correlated with neuroinflammatory cytokines and differentiate neuromyelitis optica spectrum disorder from multiple sclerosis

BACKGROUND

There is a need for biomarkers of disease progression and therapeutic response in multiple sclerosis (MS). This study aimed to identify cerebrospinal fluid (CSF) lipids that differentiate MS from other neuroinflammatory conditions and correlate with Expanded Disability Status Scale (EDSS) scores, gadolinium-enhancing lesions or inflammatory mediators.

METHODS

Lipids and inflammatory cytokines/chemokines were quantified with liquid chromatography-tandem mass spectrometry and multiplex ELISA, respectively, in CSF from people with untreated MS, neuromyelitis optica spectrum disorder (NMOSD), other inflammatory neurological diseases and non-inflammatory neurological diseases (NIND). Analytes were compared between groups using analysis of variance, and correlations were assessed with Pearson's analysis.

RESULTS

Twenty-five sphingolipids and four lysophosphatidylcholines were significantly higher in NMOSD compared with MS and NIND cases, whereas no lipids differed significantly between MS and NIND. A combination of three sphingolipids differentiated NMOSD from MS with the area under the curve of 0.92 in random forest models. Ninety-four lipids, including those that differentiated NMOSD from MS, were positively correlated with macrophage migration inhibitory factor (MIF) and 37 lipids were positively correlated with CSF protein in two independent MS cohorts. EDSS was inversely correlated with cholesterol ester CE(16:0) in both MS cohorts. In contrast, MIF and soluble triggering receptor expressed on myeloid cells 2 were positively associated with EDSS.

CONCLUSIONS

CSF sphingolipids are positively correlated with markers of neuroinflammation and differentiate NMOSD from MS. The inverse correlation between EDSS and CE(16:0) levels may reflect poor clearance of cholesterol released during myelin break-down and warrants further investigation as a biomarker of therapeutic response.

Anti-sulfatide antibodies in neurological disorders: should we test?

OBJECTIVE

Neurological autoimmune peripheral and central nervous system disorders can be associated with anti-sulfatide antibodies. These antibodies are considered potential diagnostic biomarkers, although their additional diagnostic value in neurological fields has been increasingly questioned. Given the little evidence of anti-sulfatide antibodies' frequency and diagnostic value in neurology, we aimed to fill this knowledge gap by investigating 10 years of data.

METHODS

This retrospective study analyzed the results of the anti-ganglioside dot kits (GA Generic Assays GmbH) from 1318 serum samples and 462 cerebrospinal fluid (CSF) samples for the frequency, sensitivity, and specificity of anti-sulfatide antibodies in neurological disorders.

RESULTS

Although anti-sulfatide antibodies are rarely present in neurological autoimmune disorders (serum IgM 2.5%, IgG 4.6%), they are also present in non-autoimmune diseases (serum IgM 1.2%, IgG 2.5%) and lack sensitivity and specificity towards being a diagnostic marker. Furthermore, anti-sulfatide antibodies are rarely found in CSF (e.g., no positive results for IgM), and including so-called borderline results ((+)) increases sensitivity and the false-positive rate in serum and CSF.

DISCUSSION

While anti-sulfatide antibodies appear more frequently in neurological autoimmune diseases, they are rare overall and provide very limited diagnostic value in determining specific neurological diseases and-more importantly-if a neurological disease has a potential autoimmune etiology.

Perspective: Therapeutic Implications for Sphingolipids in Health and Disease

Long thought to be structural components of cell membranes, sphingolipids (SLs) have emerged as bioactive molecules whose metabolism is tightly regulated. These bioactive lipids and their metabolic enzymes have been implicated in numerous disease states, including lysosomal storage disorders, multiple sclerosis, inflammation, and cancer as well as metabolic syndrome and obesity. In addition, the indications for many of these lipids to potentially serve as biomarkers for disease continue to emerge with increasing metabolomic and lipidomic studies. The implications of these studies have, in turn, led to the examination of SL enzymes and their bioactive lipids as potential therapeutic targets and as markers for therapeutic efficacy. SIGNIFICANCE STATEMENT: Many sphingolipids (SLs) and their metabolizing enzymes have been implicated in disease. This perspective highlights the potential for SLs to serve as therapeutic targets and diagnostic markers and discusses the implications for the studies and reviews highlighted in this Special Section on Therapeutic Implications for Sphingolipids in Health and Disease.