Anna L. Travelstead

B- and T-cell markers in opsoclonus–myoclonus syndrome Immunophenotyping of CSF lymphocytes

Background: Although many lines of evidence suggest an autoimmune etiology, the pathophysiology of opsoclonus–myoclonus syndrome (OMS) remains poorly understood and no immunologic abnormalities have correlated with neurologic severity. Conventional immunotherapies often do not prevent relapse or permanent sequelae. Objective: To test the cellular immune hypothesis of OMS in a cross-sectional study and determine if CSF lymphocyte subset analysis provides biomarkers of disease activity. Methods: The expression of lymphocyte surface antigens was investigated in CSF and blood of 36 children with OMS and 18 control subjects, using a comprehensive panel of monoclonal antibodies to adhesion and activation proteins in combination with anti-CD3 and anti-CD45 antibodies in four-color fluorescence-activated cell sorting. Results: Although most children with OMS had normal CSF cell counts, they exhibited expansion of CD19+ B-cell (up to 29%) and γδ T-cell (up to 26%) subsets and a lower percentage of CD4+ T-cells and CD4/CD8 ratio, which persisted even years after disease onset and conventional treatments. The percentage of activated CSF T-cells was also higher. Abnormalities correlated with neurologic severity, as scored blinded from videotapes using a 12-item motor scale, and disease duration. No significant differences were found between tumor and no-tumor groups. In children with neuroblastoma, tumor resection or cancer chemotherapy did not alter immunologic abnormalities. Conclusions: CSF B- and T-cell recruitment is linked to neurologic signs in pediatric OMS, which may relate to relapses and disease progression.

Rituximab (anti-CD20) adjunctive therapy for opsoclonus-myoclonus syndrome.

Purpose To determine if rituximab, an anti-CD20 monoclonal antibody, reduces cerebrospinal fluid (CSF) B-cell expansion in opsoclonus-myoclonus syndrome (OMS) and results in clinical improvement. Methods Sixteen children with OMS and increased % CD20+ B-cells in CSF received 4 rituximab infusions (375 mg/m2 IV) as add-on therapy to corticotropin (ACTH), intravenous immunoglobulins, or both, and were reevaluated 6 months later. Outcome measures were clinical (motor function, behavior, sleep) and immunologic (CSF and blood immunophenotype and Ig levels). Controls were 16 age-matched and sex-matched children, who did not have OMS. Results After rituximab, 81% of OMS had a lower motor severity score, and 44% improved one severity category. Mean total score decreased by 44% (P=0.0005). Rituximab reduced rage score, nighttime awakenings, and the number of children with opsoclonus, action myoclonus, drooling, gait ataxia, and rage. Despite a 51% reduction in ACTH dose, 9 of 11 children on ACTH did not relapse. The percentage of CSF CD19+ (and CD20+) B-cells was lowered in all children (undetectable in 6), with a 90% reduction in the group mean (P=0.00003). CSF B-cells were no longer expanded compared with controls. In blood, CD19+ B-cells decreased (−90%, P=0.0003), as did the CSF:blood CD19+ B-cell ratio (P=0.00003). Serum IgM fell by 69% (below reference range), with no statistically significant change in IgG or IgA. Conclusions Rituximab seems efficacious and safe as adjunctive therapy for OMS. Selective targeting of CSF B lymphocytes represents a novel and valuable paradigm shift in the therapy for centrally mediated paraneoplastic disorders.

CSF B-Cell Expansion in Opsoclonus-Myoclonus Syndrome: A Biomarker of Disease Activity

Lack of a biomarker of disease activity has hindered the therapy of childhood opsoclonus‐myoclonus syndrome (OMS), which is purported to be mediated humorally. To determine if the cerebrospinal fluid (CSF) B lymphocyte, which may traffic into the central nervous system (CNS) to produce antibody locally, is one such biomarker, B lymphocytes were immunophenotyped in the CSF and blood of 56 children with OMS and 26 pediatric controls by dual‐laser flow cytometry. Neurological severity was rated blindly from videotapes using a validated 12‐item motor evaluation scale. Children with OMS manifested a 4‐ to 7‐fold higher percentage of total B‐cells in CSF (P < 0.0001), including CD5+ (P = 0.001) and CD5− (P = 0.0004) B‐cell subsets, compared with controls, in whom the percentages were negligible and unchanging with age. CSF expansion of both B‐cell subsets increased with disease severity and decreased with disease duration (P ≤ 0.0001, ANOVA). Previous treatment with conventional immunotherapies, chemotherapy, or tumor resection had not normalized B‐cell percentages in those with lingering symptoms. These studies reveal that CSF B‐cell expansion in OMS is characteristic and often persistent. Presence of the autoreactive CD5+ B‐cell subset and correlations with neurological severity and disease duration suggest CSF B‐cell expansion is a biomarker of disease activity and possible target for B‐cell–specific therapy. Immunophenotyping of CSF lymphocytes by flow cytometry yields valuable clinical information missed by routine studies and allows crucial treatment decisions to be made rapidly.

Immunologic and Clinical Responses to Rituximab in a Child With Opsoclonus-Myoclonus Syndrome

Opsoclonus-myoclonus syndrome (OMS) is an autoimmune disorder with serious neurodevelopmental morbidity and limited treatment options. We treated a toddler with moderately severe OMS with rituximab, a monoclonal anti-B cell antibody. The patients clinical response was documented on videotape and scored with the OMS Evaluation Scale. Cerebrospinal fluid lymphocyte subsets were evaluated by flow-cytometric immunophenotyping, with a comprehensive panel of monoclonal antibodies. Eradication of cerebrospinal fluid B cells, which previously were expanded, was associated with dramatic clinical improvement. There also were secondary changes in other lymphocyte subsets that might be relevant to the clinical response and lack of serious infections. In addition to clarifying the immune response to B-cell depletion, these data reveal a promising new therapy for OMS that warrants a phase I clinical trial.

B Cell Depletion Therapy for New-Onset Opsoclonus-Myoclonus

Twelve immunotherapy‐naïve children with opsoclonus‐myoclonus syndrome and CSF B cell expansion received rituximab, adrenocorticotropic hormone (ACTH), and IVIg. Motor severity lessened 73% by 6 mo and 81% at 1 yr (P < 0.0001). Opsoclonus and action myoclonus disappeared rapidly, whereas gait ataxia and some other motor components improved more slowly. ACTH dose was tapered by 87%. Reduction in total CSF B cells was profound at 6 mo (‐93%). By study end, peripheral B cells returned to 53% of baseline and serum IgM levels to 63%. Overall clinical response trailed peripheral B cell and IgM depletion, but improvement continued after their levels recovered. All but one non‐ambulatory subject became ambulatory without additional chemotherapy; two relapsed and remitted; four had rituximab‐related or possibly related adverse events; and two had low‐titer human anti‐chimeric antibody. Combination of rituximab with conventional agents as initial therapy was effective and safe. A controlled trial with long‐term safety monitoring is indicated.

Key role of CXCL13/CXCR5 axis for cerebrospinal fluid B cell recruitment in pediatric OMS

To study aberrant B cell trafficking into the CSF in opsoclonus-myoclonus syndrome (OMS), chemoattractants CXCL13 and CXCL12, and B cell frequency and CXCR5 expression, were evaluated. CSF CXCL13 concentration and the CSF/serum ratio were higher in untreated OMS than controls, related directly to OMS severity and inversely to OMS duration, and correlated with CSF B cell frequency and oligoclonal bands. CXCL12 showed the opposite pattern. Selective accumulation of CXCR5+ memory B cells in CSF was found. In ACTH-treated OMS, CXCL13, but not CXCL12, was lower. These data implicate the chemokine/chemoreceptor pair CXCL13/CXR5 in B cell recruitment to the CNS in OMS. CXCL13 and CXCL12 may serve as reciprocal biomarkers of disease activity, but CXCL13 also had utility as a treatment biomarker.

BAFF/APRIL system in pediatric OMS: relation to severity, neuroinflammation, and immunotherapy

BackgroundB-cell dysregulation has been implicated but not fully characterized in pediatric opsoclonus-myoclonus syndrome (OMS), a neuroblastoma-associated neuroinflammatory disorder.ObjectiveTo assess the role of B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL), two critical B cell-modulating cytokines, as potential biomarkers of disease activity and treatment biomarkers in OMS.MethodsSoluble BAFF and APRIL were measured in cerebrospinal fluid (CSF) and serum by ELISA in 433 children (296 OMS, 109 controls, 28 other inflammatory neurological disorders (OIND)). BAFF-R receptors on circulating CD19+ B cells were measured by flow cytometry. A blinded scorer rated motor severity on the OMS Evaluation Scale. Immunotherapies were evaluated cross-sectionally and longitudinally.ResultsThe mean CSF BAFF concentration, which was elevated in untreated OMS and OIND, correlated with OMS severity category (P = 0.006), and reduction by adrenocorticotropic hormone or corticotropin (ACTH) (−61%) or corticosteroids (−38%) was seen at each level of severity. In contrast, CSF APRIL was normal in OMS and OIND and unaffected by immunotherapy. When the entire OMS dataset was dichotomized into ‘high’ versus ‘normal’ CSF BAFF concentration, the phenotype of the high group included greater motor severity and number of CSF oligoclonal bands, and a higher concentration of inflammatory chemokines CXCL13 and CXCL10 in CSF and CXCL9 and CCL21 in serum. Serum APRIL was 6.7-fold higher in the intravenous immunoglobulins (IVIg) group, whereas serum BAFF was 2.6-fold higher in the rituximab group. The frequency of B cell BAFF-R expression was similar in untreated and treated OMS. Longitudinal studies of CSF BAFF revealed a significant decline in ACTH-treated patients (with or without rituximab) (P < 0.0001). Longitudinal studies of serum APRIL showed a 2.9-fold increase after 1 to 2 g/kg IVIg monotherapy (P = 0.0003).ConclusionsStriking distinctions in BAFF/APRIL signaling were found. OMS displayed heterogeneity in CSF BAFF expression, which met many but not all criteria as a potential biomarker of disease activity. We speculate that CSF BAFF may have more utility in a biomarker panel than as a stand-alone biomarker, and that the selective upregulation of both serum APRIL by IVIg and BAFF by rituximab, as well as downregulation of CSF BAFF by ACTH/steroids, may have utility as treatment biomarkers.

Long-Term Cerebrospinal Fluid and Blood Lymphocyte Dynamics After Rituximab for Pediatric Opsoclonus-Myoclonus

IntroductionOpsoclonus-myoclonus syndrome (OMS) is an autoimmune paraneoplastic disorder characterized by B and T cell abnormalities in cerebrospinal fluid (CSF) and propensity for relapse. The study aim was to assess whether rituximab-induced B cell ablation in CSF outlasts repopulation in blood and if there are changes in other lymphocyte subsets.Materials and MethodsIn 25 children with OMS, the expression of CSF and blood lymphocyte surface antigens was evaluated by flow cytometry before and at intervals after rituximab therapy.ResultsThe reduction in CSF CD27+ memory, CD38+ activated, CD5+, and other B cell subsets was profound (p < 0.0001), comparable across groups (−94%), and sustained over 12–18 months despite repopulation in blood. The observed lag in memory B cell pool recovery in the CSF compared to peripheral blood may be clinically relevant. T cell phenotypic changes involved frequency, not absolute counts, and were transient. Co-treatment with IVIg or ACTH did not significantly alter B cell depletion or repletion.DiscussionThese data indicate that rituximab affords long-term protection against CSF B cell expansion in OMS (ClinicalTrials.gov NCT00244361).

Evidence for an interferon-related inflammatory reaction in the trisomy 16 mouse brain leading to caspase-1-mediated neuronal apoptosis

The trisomy of human chromosome 21 (Down syndrome) is the leading genetic cause of learning difficulties in children, and predisposes this population to the early onset of the neurodegeneration of Alzheimers disease. Down syndrome is associated with increased interferon (IFN) sensitivity resulting in unexpectedly high levels of IFN inducible gene products including Fas, complement factor C3, and neuronal HLA I which could result in a damaging inflammatory reaction in the brain. Consistent with this possibility, we report here that the trisomy 16 mouse fetus has significantly increased whole brain IFN-gamma and Fas receptor immunoreactivity and that cultured whole brain trisomy 16 mouse neurons have increased basal levels of caspase 1 activity and altered homeostasis of intracellular calcium and pH. The trisomic neurons also showed a heightened sensitivity to the increase in both Fas receptor levels and caspase 1 activity we observed when IFN-gamma was added to the neuron culture media. Because of the autoregulatory nature of IFN activity, and the IFN inducing capability of caspase-1-activated cytokine activity, our data argue in favor of the possibility of an interferon-mediated, self-perpetuating, inflammatory response in the trisomy brain that could subserve the loss of neuron viability seen in this trisomy 16 mouse model for Down syndrome.

Insights on chronic-relapsing opsoclonus-myoclonus from a pilot study of mycophenolate mofetil.

Opsoclonus-myoclonus syndrome is characterized by abnormal lymphocyte trafficking into brain. The authors hypothesized that mycophenolate mofetil, a lymphocyte proliferation inhibitor, might be therapeutic. The cerebrospinal fluid and blood immunophenotypes of 15 children with predominantly chronic-relapsing opsoclonus-myoclonus syndrome were compared before and after treatment by flow cytometry. Mycophenolate mofetil reduced the cerebrospinal fluid expansion of HLA-DR+ activated T cells (—40%); the frequency of other T-cell or natural killer cell subsets remained unchanged, but cerebrospinal fluid B cells increased significantly. Adrenocorticotropic hormone dose was lowered by 64% over an average of 1.5 years, yet 73% eventually relapsed despite therapeutic drug levels. Prior treatment with rituximab prevented relapse-associated increase in cerebrospinal fluid B cells, without hindering mycophenolate mofetil—induced reduction in T-cell activation. These data demonstrate resistant immunologic problems in chronic-relapsing opsoclonus-myoclonus syndrome. Mycophenolate mofetil did not prevent relapse. The novel effect of mycophenolate mofetil on chronically activated T cells may contribute to its efficacy in T-cell mediated neurological disorders.