CSF Findings in Acute NMDAR and LGI1 Antibody–Associated Autoimmune Encephalitis

Background and ObjectivesCSF in antibody-defined autoimmune encephalitis (AE) subtypes shows subtype-dependent degrees of inflammation ranging from rare and often mild to frequent and often robust. AEs with NMDA receptor antibodies (NMDAR-E) and leucine-rich glioma-inactivated protein 1 antibodies (LGI1-E) represent opposite ends of this spectrum: NMDAR-E with typically frequent/robust and LGI1-E with rare/mild CSF inflammation. For a more in-depth analysis, we characterized CSF findings in acute, therapy-naive NMDAR-E and LGI1-E in a multicentric, retrospective, cross-sectional setting.MethodsEighty-two patients with NMDAR-E and 36 patients with LGI1-E from the GErman NEtwork for Research of AuToimmune Encephalitis (GENERATE) with lumbar puncture within 90 days of onset and before immunotherapy were included. CSF parameters comprised leukocytes, oligoclonal bands (OCBs), and CSF/serum ratios for albumin, immunoglobulin G (IgG), A (IgA), and M (IgM), the latter 3 converted to Z scores according to Reiber formulas. The MRZ reaction was tested in 14 patients with NMDAR-E and 6 patients with LGI1-E, respectively.ResultsCSF was abnormal in 94% of NMDAR-E but only in 36% of LGI1-E patients. Robust quantitative intrathecal immunoglobulin synthesis (IIS, IgG > IgM >> IgA) was characteristic for NMDAR-E, but absent in LGI-E. In NMDAR-E, CSF leukocytes were higher when IIS was present or more pronounced. In addition, in NMDAR-E, CSF leukocytes were lower and IIS occurred less often and if so to a lesser degree at older age. Patients with NMDAR-E with severe functional impairment more often had positive OCBs. In CSF obtained later than 3 weeks of onset, leukocytes were lower. In parallel, the correlation of leukocytes with IIS disappeared as IIS was partially independent of disease duration. The MRZ reaction was positive in 5 (36%) patients with NMDAR-E. All these associations were completely absent in LGI1-E. Here, younger patients showed more blood-CSF barrier dysfunction. In LGI1-E, but not in NMDAR-E, the blood-CSF barrier was more dysfunctional when CSF leukocytes were higher.DiscussionNMDAR-E and LGI-E differ in their typical extent of CSF inflammation. In addition, the patterns formed by the different inflammatory CSF parameters and their relationship with disease severity, age, and disease duration are subtype-characteristic. Moreover, signs for multiple sclerosis-like chronic inflammation are present in a subgroup of patients with NMDAR-E. These CSF patterns might be markers for the different immunopathogeneses of LGI1-E and NMDAR-E.

Effects of Natalizumab Therapy on Intrathecal Immunoglobulin G Production Indicate Targeting of Plasmablasts

ObjectivesTo evaluate the long-term effects of natalizumab (NTZ) on different features of intrathecal immunoglobulin (Ig) synthesis in patients with multiple sclerosis (MS) and to quantify the expression of α4-integrin in stages of B-cell maturation.MethodsWe combined a cross-sectional (49 NTZ-treated MS patients, mean treatment duration 5.1 years, and 47 untreated MS patients) and a longitudinal study (33 patients with MS before and during NTZ, mean treatment duration: 4.8 years), analyzing paired serum and CSF samples for IgG, IgA, and IgM levels, reactivity against selected viruses (measles virus, rubella virus, and varicella zoster virus [MRZ] reaction), and oligoclonal bands (OCBs). Banding patterns before and after therapy were directly compared by isoelectric focusing in 1 patient. In addition, we determined the expression of α4-integrin by FACS analysis on blood-derived B-cell subsets (plasmablasts, memory B cells, and naive B cells) of healthy controls.ResultsIn serum, NTZ decreased IgM and IgG, but not IgA, levels. IgM hypogammaglobulinemia occurred in 28% of NTZ-treated patients. In CSF, NTZ treatment resulted in a strong reduction of intrathecally produced IgG and, to a lesser extent, IgA, whereas IgM indices [(Ig CSF/Serum)/(Albumin CSF/Serum)] remained largely unchanged. Reduction of the IgG index correlated with NTZ treatment duration, as did serum IgM and IgA levels. MRZ reaction was unchanged and OCB persisted. Direct comparison of OCB pattern before and after NTZ revealed the persistence of individual bands. α4-Integrin expression was highest on plasmablasts (CD19+CD38+CD27+).ConclusionOur data indicate that NTZ reduces short-lived plasmablasts in the CNS compartment but has little effect on locally persisting long-lived plasma cells.

Parvovirus B19 and mumps virus antibodies are major constituents of the intrathecal immune response in European patients with MS and increase the diagnostic sensitivity and discriminatory power of the MRZ reaction

Background A positive MRZ reaction, as defined by intrathecal IgG production against at least two of its constituents, measles virus (M), rubella virus (R) and varicella zoster virus (Z), is detectable in ~ 63% of patients with multiple sclerosis (MS) and is currently considered the laboratory marker with the highest specificity and positive likelihood ratio for MS. However, M, R and Z are only the most well-established constituents of a broader intrathecal humoral immune response in MS. Objective To identify additional anti-microbial antibodies inclusion of which in the classical MRZ panel may result in increased sensitivity without compromising the marker’s high specificity for MS. Methods We determined the antibody indices (AIs) for 11 viral and bacterial agents (M, R, Z, herpes simplex virus, Epstein–Barr virus, mumps virus, cytomegalovirus, parvovirus B19, Bordetella pertussis, Corynebacterium diphtheriae, and Clostridium tetani) in paired cerebrospinal fluid and serum samples from patients with MS and disease controls. Results A positive ‘classical’ MRZ reaction was found in 17/26 (65.4%) MS patients. The five most frequently positive AIs among patients with MS were M (76.9%), Z (61.5%), R (57.7%), parvovirus B19 (42.3%), and mumps (28%). Addition of parvovirus B19 and mumps virus to the MRZ panel resulted in an increase in sensitivity in the MS group from 65.4% to 73.1%, with 22% of the initially MRZ-negative patients exhibiting a de novo-positive response. The extended MRZ panel (‘MRZplus’) distinguished sharply between MS (≥ 3 AIs in 90% of all positives) and controls (varying diagnoses, from migraine to vasculitis; 0-1 AIs; p < 0.000001). The highest median AI in the MS group was found for parvovirus B19 (3.97), followed by measles virus (2.79). Conclusion Inclusion of parvovirus B19 and mumps virus in the test panel resulted in an increase in the sensitivity and discriminatory power of MRZ. Our results provide a strong rational for prospective studies investigating the role of extended MRZ panels in the differential diagnosis of MS.

Cerebrospinal Fluid Biomarkers in Relation to MRZ Reaction Status in Primary Progressive Multiple Sclerosis

The MRZ reaction (MRZR) comprises the three antibody indices (AIs) against measles, rubella, and varicella zoster virus, reflecting an intrathecal polyspecific B cell response highly specific for multiple sclerosis (MS). Thus, MRZR can be used to confirm a diagnosis of primary progressive MS (PPMS) but its pathophysiological and wider clinical relevance is unclear. This study aimed to investigate whether PPMS patients with a positive MRZR (MRZR+) differ from those with a negative MRZR (MRZR-) according to cerebrospinal fluid (CSF) biomarkers of B cell activity, neuroaxonal damage or glial activity, and clinical features. (1) Methods: In a multicenter PPMS cohort (n = 81) with known MRZR status, we measured B cell-activating factor (BAFF), chemokine CXC ligand 13 (CXCL-13), soluble B cell maturation antigen (sBCMA), soluble transmembrane activator and CAML interactor (sTACI), and chitinase-3-like protein 1 (CHI3L1) in the CSF with enzyme-linked immunosorbent assays (ELISAs). Glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) were detected in serum and CSF using single molecule array (SIMOA) technology. (2) Results: MRZR+ patients (45.7% of all PPMS patients) revealed higher levels of NfL in CSF compared to MRZR- patients (54.3%). There were positive correlations between each of sBCMA, sTACI, and intrathecal immunoglobin G (IgG) synthesis. Additionally, NfL concentrations in serum positively correlated with those in CSF and those of GFAP in serum. However, MRZR+ and MRZR- patients did not differ concerning clinical features (e.g., age, disease duration, Expanded Disability Status Scale (EDSS) at diagnosis and follow-up); CSF routine parameters; CSF concentrations of BAFF, CXCL-13, sBCMA, sTACI, CHI3L1, and GFAP; or serum concentrations of GFAP and NfL. (3) Conclusions: In PPMS patients, MRZR positivity might indicate a more pronounced axonal damage. Higher levels of the soluble B cell receptors BCMA and transmembrane activator and CAML interactor (TACI) in CSF are associated with a stronger intrathecal IgG synthesis in PPMS.

Diagnostic significance of intrathecally synthesized immunoglobulins against neurotropic viruses (MRZ-reaction) in diagnosis of multiple sclerosis

Multiple sclerosis is chronic demyelinating disease of the central nervous system with autoimmune inflammation and accretive neurodegeneration. One of the characteristics of autoimmune inflammation in multiple sclerosis is a polyspecific intrathecal humoral immune response against neurotropic viruses (Measles, Rubella and varicella Zoster) called MRZ-reaction. This immune response is based on polyclonal activation of mature B lymphocytes in the central nervous system and intrathecal synthesis of antibodies to anamnestic antigens unrelated to viral replication in the central nervous system as well as serum antibody release. Immunoglobulins produced against neurotropic viruses are an integral part of the oligoclonal antibody pool in the cerebrospinal fluid. Because immunoglobulins can penetrate the blood brain barrier, not only serum and cerebrospinal fluid specific antibody indices are calculated, but also blood-brain barrier antibody permeability (Qalbumin, QIgG) are taken into account to assess their intrathecal synthesis. The aim of the study was to assess the informative value of the intrathecal antibodies against neurotropic viruses (MRZ-reaction) in multiple sclerosis. There were enrolled 60 patients divided into 2 groups: group 1 — 35 patients diagnosed with multiple sclerosis, group 2 — 25 patients with inflammatory and non-inflammatory disоrders of the central nervous system. Paired cerebrospinal fluid and serum samples were collected from all patients to measure level of oligoclonal IgG, immunoglobulin free kappa and lambda light chains, IgG index and specific antibodies indices, followed by assessing magnitude of MRZ-reaction. We found that the MRZ-reaction was the most specific test to diagnose multiple sclerosis. Intrathecally produced antibodies against neurotropic viruses were detected in 3 of 35 multiple sclerosis patients with lacking oligoclonal IgG antibodies. In addition, a relationship between MRZ-reaction and degree of EDSS disability was found in MS patients: peak EDSS score was reported in patients with intrathecally synthesized antibodies against 3 viral agents, whereas the minimum EDSS score — among MRZ-negative patients. Thus, assessing MRZ-reaction seems rational for confirming MS diagnosis in case of other negative laboratory tests (oligoclonal immunoglobulins and free kappa/lambda light chains in cerebrospinal fluid) allowing to improves diagnostic accuracy and evaluation of MS severity.

Effects of natalizumab therapy on intrathecal antiviral antibody responses in MS

ObjectiveTo investigate the effects of natalizumab (NAT) treatment on intrathecally produced antiviral antibodies in MS.MethodsWe performed a longitudinal, observational study analyzing both serum and CSF samples collected before and during NAT treatment for antibodies against measles, rubella, mumps, influenza, entero, herpes, and polyoma viruses, including JC polyomavirus (JCV) and its nearest homologue BK polyomavirus (BKV), and bacterial control antigens by ELISA to determine the antigen-specific CSF antibody index (CAI). CAI ≥1.5 indicated intrathecal synthesis of antigen-specific antibodies. Oligoclonal bands (OCBs) by isoelectric focusing and total IgG, IgM, and IgA by immunonephelometry were analyzed additionally.ResultsIntrathecal synthesis of JCV- and BKV-specific IgG was detected in 20% of patients with MS at baseline and was lost significantly more frequently during NAT treatment compared with other intrathecal antiviral and antibacterial antibody reactivities. Peripheral JCV- and BKV-specific antibody responses persisted, and no cross-reactivity between JCV- and BKV-specific CSF antibodies was found. Intrathecal production of antibodies against measles, rubella, and zoster antigens (MRZ reaction) was most prevalent and persisted (73.3% before vs 66.7% after 1 year of NAT therapy). CSF OCBs also persisted (93.3% vs 80.0%), but total CSF IgG and IgM levels declined significantly.ConclusionsThese data indicate that JCV-specific antibodies are produced intrathecally in a minority of patients with MS, and NAT treatment affects the intrathecal humoral immune response against JCV relatively specifically compared with other neurotropic viruses. Further studies are needed to determine whether this effect translates to higher risk of progressive multifocal leukoencephalopathy development.

DIAGNOSTIC VALUE OF SPECIFIC ANTIBODY SYNTHESIS IN BRAIN OF PATIENTS WITH NEUROINFECTIONS

Introduction: Viral encephalitis accounts for 40-70% of all cases worldwide, central nervous system infections pose a diagnostic challenge because clinical manifestations are not typically pathognomonic for specific pathogens, and a wide range of agents can be causative. The aim: To assess the diagnostic value of intrathecal synthesis of specific antibodies in patients with inflammatory lesions of the central nervous system. Materials and methods: Within the framework of the study, two groups of 90 people in each were formed from the patients with neuroinfections admitted to our Center. Intrathecal synthesis (ITS) of total (unspecific) IgG in members of one of group (group of compare) was determined. Brain synthesis of specific antibodies (Ab) to some neurotropic pathogens (herpes simplex virus 1/2, cytomegalovirus, Epstein-Barr virus, varicella zoster virus, rubella virus, Borrelies) was studied in the second group of patients (group of interest). There were no statistically significant differences between groups by gender and age. Encephalitis and encephalomyelitis prevailed among patients of both groups Results: ITS of total IgG was established in 30 (33.3 ± 6.1 %) patients of the first group with IgG index more than 0.6 indicating on inflammatory process in CNS and no marked changes of CSF. ITS of specific Ab was determined in 23 of 90 (25.6 ± 4.6 %) patients included into group of interest. In more than half of cases Ab to several infectious agents were detected simultaneously. ITS of various specificity, in particular, to measles and rubella viruses, and VZV, known as MRZ-reaction, is characteristic of some autoimmune lesions of CNS, multiple sclerosis first of all. In fact, further research of 5 patients with MRZ-reaction confirmed their autoimmune failure of CNS. Detection of ITS in the CSF samples didn’t depend on concentration of specific Ab in serum and CSF and wasn’t followed by HEB dysfunctions which were observed with the same frequency in patients with or without ITS (13.0 % and 13.6 % respectively). Conclusion: Specific Ab synthesis to several neurotropic pathogens in the CSF of significant part of examined patients was established. Thus, diagnostic value of ITS of specific immunoglobulins seems to be limited to cases in which autoimmune damage of the CNS is suspected.