Sphingosine-1-phosphate (S1P) and S1P receptors (S1PR) are bioactive lipid molecules that are ubiquitously expressed in the human body and play an important role in the immune system. S1P-S1PR signaling has been well characterized in immune trafficking and activation in both innate and adaptive immune systems. Despite this knowledge, the full scope in the pathogenesis of autoimmune disorders is not well characterized yet. From the discovery of fingolimod, the first S1P modulator, until siponimod, the new molecule recently approved for the treatment of secondary progressive multiple sclerosis (SPMS), there has been a great advance in understanding the S1P functions and their involvement in immune diseases, including multiple sclerosis (MS). Modulation on S1P is an interesting target for the treatment of various autoimmune disorders. Improved understanding of the mechanism of action of fingolimod has allowed the development of the more selective second-generation S1PR modulators. Subtype 1 of the S1PR (S1PR1) is expressed on the cell surface of lymphocytes, which are known to play a major role in MS pathogenesis. The understanding of S1PR1’s role facilitated the development of pharmacological strategies directed to this target, and theoretically reduced the safety concerns derived from the use of fingolimod. A great advance in the MS treatment was achieved in March 2019 when the Food and Drug Association (FDA) approved Siponimod, for both active secondary progressive MS and relapsing–remitting MS. Siponimod became the first oral disease modifying therapy (DMT) specifically approved for active forms of secondary progressive MS. Additionally, for the treatment of relapsing forms of MS, ozanimod was approved by FDA in March 2020. Currently, there are ongoing trials focused on other new-generation S1PR1 modulators. This review approaches the fundamental aspects of the sphingosine phosphate modulators and their main similarities and differences.

Background: The effect of disease-modifying therapies on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine response is unclear. Objectives: We aim to determine the immunological responses to SARS-CoV-2 in multiple sclerosis (MS) and anti-CD20-treated patients with other autoimmune diseases (AID). Methods: Humoral and cellular responses we determined before and 30-90 days after vaccination in patients with MS and anti-CD20-treated patients with other AID in two Catalan centers. Results: 457 patients were enrolled. Findings showed that humoral response decreased under anti-CD20s or sphingosine 1-phosphate receptor modulators (S1PRM) and with longer treatment duration and increased after 4.5 months from the last anti-CD20 infusion. Cellular response decreased in S1PRM-treated. Patients on anti-CD20 can present cellular responses even in the absence of antibodies. Conclusion: Anti-CD20s and S1PRM modify the immunological responses to SARS-CoV-2 vaccines.

The role of the complement system in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is not completely understood, and studies exploring its potential utility for diagnosis and prognosis are lacking. We aimed to investigate the value of complement factors (CFs) as diagnostic and prognostic biomarkers in patients with MOGAD. Multicentric retrospective cohort study including patients with MOGAD, multiple sclerosis (MS) and aquaporin-4 seropositive neuromyelitis optica spectrum disorder (AQP4-NMOSD) with available paired serum and CSF samples. A panel of CFs were measured by multiplex ELISA, and the levels were compared between the 3 conditions. Univariable and multivariable analyses were performed to evaluate the association between levels of CFs and relapse and disability outcomes in MOGAD patients. Ninety-four patients (MOGAD, n = 60; MS, n = 18; AQP4-NMOSD, n = 16) were included. Mean (SD) age at sampling was 39.4 (16.7), 40.7 (7.0), and 43.3 (21.0), respectively. Female were predominant, especially in AQP4-NMOSD (88%). Combination of the serum levels of C3a, C4a, and C3a/C3 ratio showed excellent potential to discriminate MOGAD from patients with MS (area under the curve [AUC] [95% CI] 0.95 [0.90-0.99]) and from AQP4-NMOSD (AUC 0.88 [0.76-1.00]). In patients with MOGAD, CSF levels of CFs of the classical/lectin pathway influenced relapse-related outcomes, and lower C4 levels were associated with higher number of relapses during follow-up (incidence rate ratio [95% CI] 0.88 [0.78-0.99]; p = 0.04 in multivariable analysis), and a high C4a/C4 ratio was associated with increased risk of second relapse during the first year (hazard ratio [95% CI] 3.68 [1.26-10.78]; p = 0.02 in multivariable analysis). Time to second relapse was shorter in patients with MOGAD with a high CSF C4a/C4 ratio (log-rank p = 0.01). CSF levels of the membrane attack complex SC5b9 influenced disability-related outcomes, and baseline CSF SC5b9 levels were higher in patients who reached the final Expanded Disability Status Scale (EDSS) ≥ 3.0 (p = 0.002), and elevated SC5b9 levels were associated with increased risk of reaching EDSS ≥ 3.0 (odds ratio [95% CI] 1.79 [1.16-3.67]; p = 0.04 in multivariable analyses). Our results suggest that serum and CSF levels of CFs have diagnostic and prognostic value respectively in patients with MOGAD. These findings support the use of complement inhibitors as a therapeutic approach in these patients.

Background: Serum neurofilament light chain (sNfL) and serum glial fibrillary acidic protein (sGFAP) have emerged as important biomarkers in multiple sclerosis (MS) and aquaporin-4 seropositive neuromyelitis optica spectrum disorder (AQP4-NMOSD). However, their interest in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) remains unclear. Our aim was to characterise sNfL and sGFAP profile and analyse their usefulness in predicting relapses and disability in MOGAD. Methods: Retrospective study of adult MOGAD patients with serum samples collected at baseline (=3 months from disease onset) and follow-up (>6 months from baseline sample). sNfL and sGFAP were analysed using Simoa HD-1, and values were compared across time-points. The association between biomarkers and clinical variables and their predictive value for disability and relapses were analysed. Results: Eighty-nine MOGAD patients were included. Baseline sNfL and sGFAP values were high at baseline and decreased over time (p<0.001, p=0.027, respectively). sNfL and sGFAP values were associated with Expanded Disability Status Scale (EDSS) at attacks (ß 0.15 (0.06; 0.25), p=0.002; ß 0.14 (0.07; 0.21), p<0.001, respectively) and were lower in optic neuritis presentations (ß -0.69 (-1.18; -0.19), p=0.007; ß -0.42 (-0.76; -0.08), p=0.016). Biomarker deltas[?] (baseline values – second samples values) were associated with ?EDSS (initial EDSS - final EDSS) (?sNfL ß 0.52 (0.01; 1.04), p=0.046; ?sGFAP ß 1.07 (0.38; 1.75), p=0.003). Finally, sNfL values independently predicted the risk of relapses (HR 2.06 (1.41; 3.01), p<0.001). Conclusions: Our results on sNfL and sGFAP suggest initial neuro-axonal and astrocytic damage in MOGAD and the utility of these biomarkers at onset and follow-up in predicting clinical recovery and relapses.