Abstract

B cells play a central role in multiple sclerosis (MS) pathology. B and plasma cells, and their antibody products, are found at elevated levels in MS patient cerebrospinal fluid and demyelinating lesions, and B cell-predominant germinal center-like aggregates are observed in relapsing and secondary progressive patients MS patients. In Phase 3 clinical trials, relapsing MS patients treated with anti-CD20 monoclonal antibodies demonstrate reduced MRI lesion activity, clinical relapses, and disability progression; and early Phase 2 clinical studies of Bruton’s tyrosine kinase inhibitors show reduction in active MRI lesions. B and plasma cells may modulate MS disease activity through multiple mechanisms including antigen presentation, pro- and anti-inflammatory cytokine secretion, and auto-antibody production. Molecular and functional analyses of B cell populations have indicated that B cell subpopulations and mature antibody producing cells (plasmablasts and plasma cells) display complex interactions with other immune cell populations to modulate MS disease activity in the periphery and within the central nervous system. These effects are further modified by secreted immunoglobulins acting independently or in concert with other cellular immune responses. Sophisticated translational investigations and experimental models are primed to expand our understanding of MS B cell pathophysiology and advance the development of new B cell therapeutics.

Background

Multiple Sclerosis (MS) is an immune-mediated disease of the central nervous system (CNS) characterized by cortical demyelinating lesions containing activated microglia and phagocytic macrophages. The complex dynamics between microglia and oligodendrocytes during demyelination remain to be established. Bruton’s Tyrosine Kinase (BTK) is a key regulator of microglial phagocytosis; however, it is unclear whether modulation of BTK directly affects immune-mediated demyelination.

Objectives

To visualize and manipulate in vivo microglia-oligodendrocyte interactions during cortical myelin loss and repair.

Methods

We developed a novel in vivo model of immune-mediated cortical demyelination through the application of recombinant antibodies derived from MS patients and human complement (MSrAb+huC’) onto the cortical surface. We characterized cellular interactions in real-time via longitudinal in vivo two-photon microscopy of myelinating oligodendrocytes and microglia in transgenic mice.

Results

We found that MSrAb+huC’ application resulted in robust demyelination that recapitulated MS pathology. Microglia rapidly engulfed myelin sheaths following the application of MSrAb+huC’, and subsequently increased their density, accumulating around heavily affected oligodendrocytes. Oral administration of a brain-penetrant BTK-inhibitor prior to the application of MSrAb+huC’ drastically altered microglia dynamics in the 72 hours post-surgery, notably by diminishing engulfment morphology and density changes. Moreover, BTK-inhibition prevented the loss of oligodendrocytes.

Conclusions

Inhibition of BTK signaling alters microglia-oligodendrocyte interactions and limits complement-dependent antibody-mediated demyelination. These findings provide a novel context to define glial interactions during immune-regulated demyelination and outline a crucial role for microglia in driving myelin loss.

Abstract

B cells play a central role in multiple sclerosis (MS) pathology. B and plasma cells, and their antibody products, are found at elevated levels in MS patient cerebrospinal fluid and demyelinating lesions, and B cell-predominant germinal center-like aggregates are observed in relapsing and secondary progressive patients MS patients. In Phase 3 clinical trials, relapsing MS patients treated with anti-CD20 monoclonal antibodies demonstrate reduced MRI lesion activity, clinical relapses, and disability progression; and early Phase 2 clinical studies of Bruton’s tyrosine kinase inhibitors show reduction in active MRI lesions. B and plasma cells may modulate MS disease activity through multiple mechanisms including antigen presentation, pro- and anti-inflammatory cytokine secretion, and auto-antibody production. Molecular and functional analyses of B cell populations have indicated that B cell subpopulations and mature antibody producing cells (plasmablasts and plasma cells) display complex interactions with other immune cell populations to modulate MS disease activity in the periphery and within the central nervous system. These effects are further modified by secreted immunoglobulins acting independently or in concert with other cellular immune responses. Sophisticated translational investigations and experimental models are primed to expand our understanding of MS B cell pathophysiology and advance the development of new B cell therapeutics.

Abstract

B cells play a central role in multiple sclerosis (MS) pathology. B and plasma cells, and their antibody products, are found at elevated levels in MS patient cerebrospinal fluid and demyelinating lesions, and B cell-predominant germinal center-like aggregates are observed in relapsing and secondary progressive patients MS patients. In Phase 3 clinical trials, relapsing MS patients treated with anti-CD20 monoclonal antibodies demonstrate reduced MRI lesion activity, clinical relapses, and disability progression; and early Phase 2 clinical studies of Bruton’s tyrosine kinase inhibitors show reduction in active MRI lesions. B and plasma cells may modulate MS disease activity through multiple mechanisms including antigen presentation, pro- and anti-inflammatory cytokine secretion, and auto-antibody production. Molecular and functional analyses of B cell populations have indicated that B cell subpopulations and mature antibody producing cells (plasmablasts and plasma cells) display complex interactions with other immune cell populations to modulate MS disease activity in the periphery and within the central nervous system. These effects are further modified by secreted immunoglobulins acting independently or in concert with other cellular immune responses. Sophisticated translational investigations and experimental models are primed to expand our understanding of MS B cell pathophysiology and advance the development of new B cell therapeutics.

Background

Plasma neurofilament light(pNFL) levels account for 30-60% of the variance in CSF neurofilament light(cNFL) levels depending on the study. Age, disability, relapses, and the presence of contrast enhancing MRI lesions can increase both pNFL and cNFL. Additional nervous system biomarkers can now be studied in plasma. Understanding the factors that increase their variability in blood may be helpful in normalizing levels to better understand what levels are concerning for ongoing disease activity.

Objectives

To evaluate factors contributing to blood and cerebrospinal fluid(CSF) discordance and determine if a correction of blood levels can better estimate what is happening in the CSF compartment.

Methods

Matched plasma and CSF samples were identified in the Rocky Mountain Multiple Sclerosis Center Biorepository at the University of Colorado. Neurofilament Light(NFL), Glial Fibrillary Acidic Protein(GFAP), tau, and Ubiquitin carboxy-terminal hydrolase L1(UCHL1) levels were assessed using Single Molecule Array(SIMOA) in a Quanterix SR-X machine. Analyses were done on log transformed NFL concentrations.

Results

Fifty-seven patients had matched plasma and cerebrospinal fluid samples evaluated for neurofilament light which included 24 patients with multiple sclerosis(MS), 7 with neuromyelitis optica spectrum disorder(NMOSD), and 18 patients with headache whose opening pressures were <20cmH₂O. These patients had a mean age of 46.5(+/-11.2) years, 75% female, mean albumin index of 6.3(+/-5.5), and BMI of 27.4(+/-5.8). The CSF and plasma concentrations in pg/ml were for NFL 1059.3(+/-3052.4) and 12.2(+/-32.4), GFAP 7621.5(+/-9713.4) and 52.9(+/-39.7), tau 41.5(+/-41.3) and 1.3(+/-0.8), UCHL1 1356.0(+/-1677.1) and 23.6(+/-32.8). Respectively the CSF vs plasma Spearman correlations (95% confidence intervals, p values) were: 0.79(0.67-0.87,<0.0001), 0.67(0.50-0.79,<0.0001), 0.75(0.61-0.85,<0.0001), and 0.70(0.54-0.81,<0.0001). Adjusting individually for age, BMI, or albumin index did not affect the correlation for NFL.

Conclusions

Blood and CSF levels of NFL, GFAP, tau, and UCHL1 correlated well. Models will be created that explore the relationship between Blood and CSF levels of these biomarkers.

Background

Pathogenic autoantibodies against aquaporin 4 (AQP4) in neuromyelitis optica spectrum disorder (NMOSD) cause central nervous system injury, with subsequent release of astroglial and neuronal proteins such as glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL), ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) and Tau into the circulation. N-MOmentum is a randomized, placebo-controlled, double-masked trial of inebilizumab, a B-cell-depleting monoclonal antibody (NCT02200770).

Objectives

Investigate relationships of NfL, UCH-L1, Tau and serum (s)GFAP to disease activity and Expanded Disability Status Scale (EDSS) disability in N-MOmentum trial participants with either AQP4-immunoglobulin G (IgG) seropositive or seronegative NMOSD.

Methods

Serum biomarkers NfL, UCH-L1, Tau and sGFAP were measured using the single molecular array (SIMOA; Quanterix) in 1260 serial and attack-related samples from N-MOmentum participants (n=215) and healthy controls (HC; n=25).

Results

At baseline, biomarkers were elevated in subsets of patients with NMOSD (NfL, 16%; UCH-L1, 6%; Tau, 12%; sGFAP, 29%); NfL and UCH-L1 levels correlated with sGFAP (r=0.53 [p<0.001] and 0.18 [p=0.007]). Baseline elevations were significantly associated with increased attack risk (NfL, hazard ratio [HR] 2.5, p=0.01; UCH-L1, HR 2.8, p=0.039; Tau, HR 2.6, p=0.01; sGFAP, HR 3.03, p<0.001). After controlling for baseline sGFAP in Cox regressions, the other markers were not independently associated with attack risk (all HR <2; p>0.05). In the total cohort, a greater proportion of patients had an attack with placebo than inebilizumab (39% vs 12%). All biomarker levels increased after attacks and median-fold increases from baseline (95% confidence interval) trended higher with placebo than inebilizumab, reaching significance with sGFAP (NfL, 1.49 [0.93–3.37] vs 1.30 [0.84–2.14], p=0.4; UCH-L1, 6.70 [1.59–52.4] vs 1.85 [0.89–23], p=0.12; Tau, 2.19 [0.96–9.46] vs 1.09 [0.40–3.7], p=0.23; sGFAP, 20.2 [4.4–98] vs 1.11 [0.75–24.6], p=0.037). Following attacks, NfL correlated with EDSS score at attack assessments (R=0.55; p<0.001); other biomarkers did not correlate with EDSS score after controlling for NfL levels.

Conclusions

In NMOSD, serum NfL, UCH-L1 and Tau levels were higher than in HC; increased baseline sGFAP levels were associated with greater attack risk. Although sGFAP levels showed the greatest increase following attacks, NfL correlated with attack-related disability.

Background

The N-MOmentum trial of inebilizumab included patients with aquaporin 4-IgG seropositive (AQP4+) or seronegative (AQP4−) neuromyelitis optica spectrum disorder (NMOSD).

Objectives

To report AQP4− participant outcomes in N-MOmentum. .......................................................

Methods

Medical histories and screening data for AQP4− patients were assessed independently by 3 clinical experts before enrollment. Majority decision confirmed diagnoses using the 2006 criteria. Myelin oligodendrocyte glycoprotein-IgG (MOG) serology and annualized attack rates (AARs) were tested post hoc. These observations do not account for bias in estimates of effects on the AAR caused by regression to the mean, introduced by inclusion criteria requiring attacks during the 1 to 2 years before study entry.

Results

Only 18/50 AQP4− patients (36%) were eligible for randomization; 17 were randomized, 4 to placebo (1 MOG+) and 13 to inebilizumab (6 MOG+). Reasons for not enrolling prospective AQP4− NMOSD participants were mainly related to lack of fulfillment of MRI findings required by the 2006 criteria.

Owing to limited patient numbers, we compared the on-study to the pre-study AAR for treated participants to assess treatment effects.

For AQP4− participants (n=17), 40 attacks occurred in 23 patient-years of pre-study follow-up with mean AAR (95% confidence interval) of 1.72 (1.23–2.33). For MOG+ participants (n=7), 16 attacks occurred in 8.3 patient-years of pre-study follow-up with an AAR of 1.93 (1.11–3.14). For double-seronegative participants (n=10), 24 attacks occurred in 15 patient-years of pre-study follow-up with an AAR of 1.60 (1.02–2.38).

After receiving inebilizumab, AARs declined in all groups by the end of the randomized controlled period: AQP4− participants (n=13), 0.09 (0.02–0.26), or 3 attacks in 34.2 patient-years; MOG+ participants (n=6), 0.08 (0.002–0.464), or 1 attack in 12 patient-years; double-seronegative participants (n=7), 0.09 (0.011–0.326), or 2 attacks in 22 patient-years.

The benefit was sustained with longer-term inebilizumab exposure. At 120 days into the open-label period (OLP), during which all participants received inebilizumab, the AAR in AQP4− participants (n=17) remained low (0.069 [0.014–0.202]). No attacks were seen in any AQP4−, MOG+ or double seronegative patient during the OLP.

Conclusions

The N-MOmentum trial provides clinically important insight on the difficulty of correctly diagnosing AQP4− NMOSD and suggests that inebilizumab may have a benefit on AAR in these patients.

Background

Magnetic resonance imaging (MRI) findings in patients with neuromyelitis optica spectrum disorder (NMOSD) have not previously been studied with data from a prospective, randomized controlled study. During N-MOmentum, longitudinal MRIs were performed systematically.

Objectives

To characterize MRI findings in patients with NMOSD in the N-MOmentum study of inebilizumab. .....................

Methods

MRIs of the spinal cord, optic nerve and brain were performed at baseline, within 8 days of an NMOSD attack and at the end of the randomized controlled period (RCP; month 6.5). MRIs were read centrally by two independent, blinded-to-treatment neuroradiologists for new gadolinium-enhancing (Gd)-T1 enhancement events. Attacks were adjudicated by an expert committee.

Results

Complete MRI data were available for 192 (83%) of 230 participants, 42 of whom had an adjudicated attack (22 myelitis, 14 optic neuritis, 6 multi-domain). The remaining 38 patients did not have valid post-baseline MRI scans available for analysis. Inter-rater agreement between the two neuroradiologists for gadolinium-enhancing lesions was 98% for brain, 95% for spinal cord and 90% for optic nerve.

At the time of acute adjudicated NMOSD attacks, new Gd-T1 MRI enhancement corresponding to the affected clinical domain was present in 19/22 myelitis attacks (86%) and 11/14 optic neuritis attacks (79%). At the time of acute optic neuritis attacks, asymptomatic, new Gd-T1 enhancement was simultaneously observed in 4/14 spinal cord MRIs (29%) and 1/14 brain MRIs (7%). At the time of acute myelitis attacks, asymptomatic, new Gd-T1 enhancement was simultaneously observed in 6/22 optic nerve MRIs (27%) and 3/22 brain MRIs (14%).

In the 150 participants without an adjudicated attack, new Gd-T1 MRI enhancements compared with baseline readings were observed in the brain, spinal cord and optic nerve in 3%, 18% and 51% of patients at the end of the RCP, respectively.

Conclusions

At the time of attack, MRI enhancements were highly correlated to the clinical presentations. However, asymptomatic Gd-T1 enhancements were detected outside the symptomatic attack domain in about one-third of cases. Furthermore, subclinical Gd-T1 enhancements were observed in many patients who did not experience clinically overt attacks. Subclinical blood–brain barrier breakdown, particularly in the optic nerve, may be a frequent phenomenon in patients with active NMOSD.

Abstract

Neuromyelitis optica (NMO) was historically defined by the concurrent or sequential presentation of optic neuritis and transverse myelitis. Serum autoantibodies against aquaporin-4 (AQP4-IgG) and myelin oligodendrocyte glycoprotein (MOG-IgG) have been identified in patients meeting clinical criteria for NMO and neuromyelitis optica spectrum disorders (NMOSD). Despite their clinical overlap, these two autoantibody-defined inflammatory disorders present with diverse neurologic findings across the pediatric and adult populations, distinct lesion histopathology, and disparate pathophysiology in experimental animal models. Therefore, it is important to be able to rapidly distinguish these conditions based on clinical, radiologic, and laboratory data due to differences in both their prognosis as well as their acute and chronic treatments. This lecture will focus on distinguishing these disorders based on their clinical phenotypes, MRI imaging, serologic assays, mechanisms of antibody-mediated pathogenesis, and histopathology.

Abstract

Neuromyelitis optica (NMO) was historically defined by the concurrent or sequential presentation of optic neuritis and transverse myelitis. Serum autoantibodies against aquaporin-4 (AQP4-IgG) and myelin oligodendrocyte glycoprotein (MOG-IgG) have been identified in patients meeting clinical criteria for NMO and neuromyelitis optica spectrum disorders (NMOSD). Despite their clinical overlap, these two autoantibody-defined inflammatory disorders present with diverse neurologic findings across the pediatric and adult populations, distinct lesion histopathology, and disparate pathophysiology in experimental animal models. Therefore, it is important to be able to rapidly distinguish these conditions based on clinical, radiologic, and laboratory data due to differences in both their prognosis as well as their acute and chronic treatments. This lecture will focus on distinguishing these disorders based on their clinical phenotypes, MRI imaging, serologic assays, mechanisms of antibody-mediated pathogenesis, and histopathology.

Abstract

Neuromyelitis optica (NMO) was historically defined by the concurrent or sequential presentation of optic neuritis and transverse myelitis. Serum autoantibodies against aquaporin-4 (AQP4-IgG) and myelin oligodendrocyte glycoprotein (MOG-IgG) have been identified in patients meeting clinical criteria for NMO and neuromyelitis optica spectrum disorders (NMOSD). Despite their clinical overlap, these two autoantibody-defined inflammatory disorders present with diverse neurologic findings across the pediatric and adult populations, distinct lesion histopathology, and disparate pathophysiology in experimental animal models. Therefore, it is important to be able to rapidly distinguish these conditions based on clinical, radiologic, and laboratory data due to differences in both their prognosis as well as their acute and chronic treatments. This lecture will focus on distinguishing these disorders based on their clinical phenotypes, MRI imaging, serologic assays, mechanisms of antibody-mediated pathogenesis, and histopathology.