An autoantibody signature predictive for multiple sclerosis.

Although B cells are implicated in multiple sclerosis (MS) pathophysiology, a predictive or diagnostic autoantibody remains elusive. In this study, the Department of Defense Serum Repository (DoDSR), a cohort of over 10 million individuals, was used to generate whole-proteome autoantibody profiles of hundreds of patients with MS (PwMS) years before and subsequently after MS onset. This analysis defines a unique cluster in approximately 10% of PwMS who share an autoantibody signature against a common motif that has similarity with many human pathogens. These patients exhibit antibody reactivity years before developing MS symptoms and have higher levels of serum neurofilament light (sNfL) compared to other PwMS. Furthermore, this profile is preserved over time, providing molecular evidence for an immunologically active preclinical period years before clinical onset. This autoantibody reactivity was validated in samples from a separate incident MS cohort in both cerebrospinal fluid and serum, where it is highly specific for patients eventually diagnosed with MS. This signature is a starting point for further immunological characterization of this MS patient subset and may be clinically useful as an antigen-specific biomarker for high-risk patients with clinically or radiologically isolated neuroinflammatory syndromes.

New knowledge on anti-IgLON5 disease.

PURPOSE OF REVIEW: Anti-IgLON5 disease is characterized by a distinctive sleep disorder, associated with a heterogeneous spectrum of neurological symptoms. Initial autopsies showed a novel neuronal tauopathy predominantly located in the tegmentum of the brainstem. Recently, new diagnostic red flags, biomarkers predictors of response to immunotherapy, and novel insights into the autoimmune pathogenesis of the disease have been reported. RECENT FINDINGS: Patients with diagnosis of neurodegenerative dementia, progressive supranuclear palsy (PSP) or with motor-neuron disease (MND)-like syndrome have been reported to have IgLON5 antibodies, which are the hallmark of anti-IgLON5 disease. Second, low levels of neurofilament light chain in serum and cerebrospinal fluid of patients at disease onset could be a predictor of immunotherapy response. Recent neuropathological studies indicate that the neuronal tau deposits occur late in the course of the disease. Moreover, IgLON5 antibodies induce cytoskeletal changes in cultured hippocampal neurons suggesting that the tauopathy could be secondary of the IgLON5 antibody effects. SUMMARY: Anti-IgLON5 disease can mimic and should be considered in atypical presentations of MND, neurodegenerative dementia and PSP. Neurofilament light chain levels seem promising biomarker for disease prognosis. Finally, the neuropathological and in vitro experimental studies strengthen the autoimmune hypothesis of the disease.

Humoral response to neurofilaments and dipeptide repeats in ALS progression.

OBJECTIVE: To appraise the utility as biomarkers of blood antibodies and immune complexes to neurofilaments and dipeptide repeat proteins, the products of translation of the most common genetic mutation in amyotrophic lateral sclerosis (ALS). METHODS: Antibodies and immune complexes against neurofilament light, medium, heavy chains as well as poly-(GP)-(GR) dipeptide repeats were measured in blood samples from the ALS Biomarkers (n = 107) and the phenotype-genotype biomarker (n = 129) studies and in 140 healthy controls. Target analyte levels were studied longitudinally in 37 ALS cases. Participants were stratified according to the rate of disease progression estimated before and after baseline and C9orf72 genetic status. Survival and longitudinal analyses were undertaken with reference to matched neurofilament protein expression. RESULTS: Compared to healthy controls, total neurofilament proteins and antibodies, neurofilament light immune complexes (p < 0.0001), and neurofilament heavy antibodies (p = 0.0061) were significantly elevated in ALS, patients with faster progressing disease (p < 0.0001) and in ALS cases with a C9orf72 mutation (p < 0.0003). Blood neurofilament light protein discriminated better ALS from healthy controls (AUC: 0.92; p < 0.0001) and faster from slower progressing ALS (AUC: 0.86; p < 0.0001) compared to heavy-chain antibodies and light-chain immune complexes (AUC: 0.79; p < 0.0001 and AUC: 0.74; p < 0.0001). Lower neurofilament heavy antibodies were associated with longer survival (Log-rank Chi-square: 7.39; p = 0.0065). Increasing levels of antibodies and immune complexes between time points were observed in faster progressing ALS. CONCLUSIONS: We report a distinctive humoral response characterized by raising antibodies against neurofilaments and dipeptide repeats in faster progressing and C9orf72 genetic mutation carriers ALS patients. We confirm the significance of plasma neurofilament proteins in the clinical stratification of ALS.

Neuronal intermediate filament IgGs in CSF: Autoimmune Axonopathy Biomarkers.

OBJECTIVES: To describe CSF-defined neuronal intermediate filament (NIF) autoimmunity. METHODS: NIF-IgG CSF-positive patients (41, 0.03% of 118599 tested, 1996-2019) were included (serum was neither sensitive nor specific). Criteria-based patient NIF-IgG staining of brain and myenteric NIFs was detected by indirect immunofluorescence assay (IFA); NIF-specificity was confirmed by cell-based assays (CBAs, alpha internexin, neurofilament light [NF-L]), heavy-[NF-H] chain). RESULTS: Sixty-one percent of 41 patients were men, median age, 61 years (range, 21-88). Syndromes were encephalopathy predominant (23), cerebellar ataxia predominant (11), or myeloradiculoneuropathies (7). MRI abnormalities (T2 hyperintensities of brain, spinal cord white matter tracts. and peripheral nerve axons) and neurophysiologic testing (EEG, EMG, evoked potentials) co-localized with clinical neurological phenotypes (multifocal in 29%). Thirty patients (73%) had ≥ 1 immunological perturbation: cancer (paraneoplastic), 22; systemic infection (parainfectious [including ehrlichosis, 3] or HIV), 7; checkpoint-inhibitor cancer immunotherapy, 4; other, 5. Cancers were as follows: neuroendocrine-lineage carcinomas, 12 (small cell, 6; Merkel cell, 5; pancreatic, 1 [11/12 had NF-L-IgG detected, versus 8/29 others, P = 0.0005]) and other, 11. Onset was predominantly subacute (92%) and accompanied by inflammatory CSF (75%), and immunotherapy response (77%). In contrast, CSF controls (15684 total) demonstrated NIF-IgG negativity (100% of test validation controls), and low frequencies of autoimmune diagnoses (20% of consecutively referred clinical specimens) and neuroendocrine-lineage carcinoma diagnosis (3.1% vs. 30% of NIF cases), P < 0.0001. Median NF-L protein concentration was higher in 8 NF-L-IgG-positive patients (median, 6718 ng/L) than 16 controls. INTERPRETATION: Neurological autoimmunity, defined by CSF-detected NIF-IgGs, represents a continuum of treatable axonopathies, sometimes paraneoplastic or parainfectious.

Increased frequency of proinflammatory CD4 T cells and pathological levels of serum neurofilament light chain in adult drug-resistant epilepsy.

OBJECTIVE: Adult drug-resistant epilepsy (DRE) is associated with significant morbidity. Infiltration of immune cells is observed in DRE epileptic foci; however, the relation between DRE and the peripheral immune cell compartment remains only partially understood. We aimed to investigate differences in immune cell populations, cytokines, and neurodegenerative biomarkers in the peripheral blood of subjects with epilepsy versus healthy controls, and in DRE compared to well-controlled epilepsy (WCE). METHODS: Peripheral blood mononuclear cells and serum from >120 age- and sex-matched adults suffering from focal onset epilepsy and controls were analyzed by multipanel flow cytometry, multiplex immunoassays, and ultrasensitive single molecule array. RESULTS: Using a data-driven analytical approach, we identified that CD4 T cells in the peripheral blood are present in a higher proportion in DRE patients. Moreover, we observed that the frequency of CD4 T cells expressing proinflammatory cytokines interleukin (IL)-17A, IL-22, tumor necrosis factor, interferon-γ, and granulocyte-macrophage colony-stimulating factor, but not anti-inflammatory cytokines IL-10 and IL-4, is elevated in the peripheral blood of DRE subjects compared to WCE. In parallel, we found that Th17-related circulating proinflammatory cytokines are elevated, but Th2-related cytokine IL-4 is reduced, in the serum of epilepsy and DRE subjects. As Th17 cells can exert neurotoxicity, we measured levels of serum neurofilament light chain (sNfL), a marker of neuronal injury. We found significantly elevated levels of sNfL in DRE compared to controls, especially among older individuals. SIGNIFICANCE: Our data support that DRE is associated with an expansion of the CD4 Tcell subset in the peripheral blood and with a shift toward a proinflammatory Th17/Th1 CD4 Tcell immune profile. Our results further show that pathological levels of sNfL are more frequent in DRE, supporting a potential neurodegenerative component in adult DRE. With this work, we provide evidence for novel potential inflammatory and degenerative biomarkers in DRE.

Anti-neurofilament antibodies and neurodegeneration: Markers and generators.

Neuroaxonal injury and loss result in the release of cytoskeleton components, including neurofilaments, into the cerebrospinal fluid and peripheral blood. Once released, neurofilaments are highly immunogenic, inducing a specific antibody response. Anti-neurofilament antibody levels correlate with the progression of diverse neurological diseases; however, their role both in the pathogenesis of disease and as a tool for monitoring disease progression is not well understood. This study reviews the current literature on anti-neurofilament antibodies. We suggest the testing of anti-neurofilament antibodies be further developed for diagnosis and targeted for treatment.

TRIM2, a novel member of the antiviral family, limits New World arenavirus entry.

Tripartite motif (TRIM) proteins belong to a large family with many roles in host biology, including restricting virus infection. Here, we found that TRIM2, which has been implicated in cases of Charcot-Marie-Tooth disease (CMTD) in humans, acts by blocking hemorrhagic fever New World arenavirus (NWA) entry into cells. We show that Trim2-knockout mice, as well as primary fibroblasts from a CMTD patient with mutations in TRIM2, are more highly infected by the NWAs Junín and Tacaribe virus than wild-type mice or cells are. Using mice with different Trim2 gene deletions and TRIM2 mutant constructs, we demonstrate that its antiviral activity is uniquely independent of the RING domain encoding ubiquitin ligase activity. Finally, we show that one member of the TRIM2 interactome, signal regulatory protein α (SIRPA), a known inhibitor of phagocytosis, also restricts NWA infection and conversely that TRIM2 limits phagocytosis of apoptotic cells. In addition to demonstrating a novel antiviral mechanism for TRIM proteins, these studies suggest that the NWA entry and phagocytosis pathways overlap.

Lower Serum Antibodies Against Tau Protein and Heavy Neurofilament in Alzheimer's Disease.

BACKGROUND: Unlike antibodies against amyloid-ß, little is known about serum antibodies to neuron-specific cytoskeletal proteins in patients with Alzheimer's disease (AD). OBJECTIVE: We aimed to study IgG autoantibodies against tau protein, light (NFL) and heavy subunits (NFH) of neurofilaments in serum of AD patients and elderly controls and to explore the evolution of antineurocytoskeletal antibody levels over time. METHODS: Antibodies against three targets (tau, NFL, and NFH) were measured using ELISA in 100 serum samples from 51 cognitively normal elderly controls and 49 patients with AD. Our primary cross-sectional design was further extended to monitor fluctuations over 1-2 years in a subset of individuals. RESULTS: The AD patients had lower levels of anti-tau antibodies (p = 0.03) and even lower anti-NFH antibodies (p = 0.005) than those in the control group at baseline. On the contrary, anti-NFL antibodies or total IgG concentrations in serum did not differ. All three antibodies remained stable in both groups except for a selective and significant anti-tau decline in AD patients (p = 0.03). CONCLUSIONS: The different responses to these antigens suggest some antibody selectivity in AD. The significant decline was observed for only serum anti-tau antibodies in AD patients over time and it corresponds to lower anti-tau levels in these patients. Our findings indicate a special feature of disease-relevant antigens and humoral autoimmunity in AD.

Behçet Disease serum is immunoreactive to neurofilament medium which share common epitopes to bacterial HSP-65, a putative trigger.

Autoimmune and dysimmune inflammatory mechanisms on a genetically susceptible background are implicated in the etiology of Behçet's Disease (BD). Heat-shock protein-65 (HSP-65) derived from Streptococcus sanguinis was proposed as a triggering factor based on its homology with human HSP-60. However, none of the autoantigens identified so far in sera from BD share common epitopes with bacterial HSP-65 or has a high prevalence. Here, we report that sera from BD patients are immunoreactive against filamentous neuronal processes in the mouse brain, retina and scrotal skin in great majority of patients. By using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and peptide mass fingerprinting, Western blotting and peptide blocking experiments, we have identified neurofilament medium (NF-M) as the probable antigen for the serologic response observed. Clustal Omega analyses detected significant structural homology between the human NF-M and bacterial HSP-65 corresponding to amino acids 111-126, 213-232 and 304-363 of mycobacterial HSP-65, which were previously identified to induce proliferation of lymphocytes obtained from BD patients. We also found that sera immunoreactive against NF-M cross-reacted with bacterial HSP-65. These findings suggest that NF-M may be involved in autoimmunity in BD due to its molecular mimicry with bacterial HSP-65.

Characterisation of Immune and Neuroinflammatory Changes Associated with Chemotherapy-Induced Peripheral Neuropathy.

Chemotherapy-induced peripheral neuropathy (CIPN) and associated neuropathic pain is a debilitating adverse effect of cancer treatment. Current understanding of the mechanisms underpinning CIPN is limited and there are no effective treatment strategies. In this study, we treated male C57BL/6J mice with 4 cycles of either Paclitaxel (PTX) or Oxaliplatin (OXA) over a week and tested pain hypersensitivity and changes in peripheral immune responses and neuroinflammation on days 7 and 13 post 1st injection. We found that both PTX and OXA caused significant mechanical allodynia. In the periphery, PTX and OXA significantly increased circulating CD4+ and CD8+ T-cell populations. OXA caused a significant increase in the percentage of interleukin-4+ lymphocytes in the spleen and significant down-regulation of regulatory T (T-reg) cells in the inguinal lymph nodes. However, conditional depletion of T-reg cells in OXA-treated transgenic DEREG mice had no additional effect on pain sensitivity. Furthermore, there was no leukocyte infiltration into the nervous system of OXA- or PTX-treated mice. In the peripheral nervous system, PTX induced expression of the neuronal injury marker activating transcription factor-3 in IB4+ and NF200+ sensory neurons as well as an increase in the chemokines CCL2 and CCL3 in the lumbar dorsal root ganglion. In the central nervous system, PTX induced significant astrocyte activation in the spinal cord dorsal horn, and both PTX and OXA caused reduction of P2ry12+ homeostatic microglia, with no measurable changes in IBA-1+ microglia/macrophages in the dorsal and ventral horns. We also found that PTX induced up-regulation of several inflammatory cytokines and chemokines (TNF-α, IFN-γ, CCL11, CCL4, CCL3, IL-12p70 and GM-CSF) in the spinal cord. Overall, these findings suggest that PTX and OXA cause distinct pathological changes in the periphery and nervous system, which may contribute to chemotherapy-induced neuropathic pain.

Monoclonal antibody Py recognizes neurofilament heavy chain and is a selective marker for large diameter neurons in the brain.

Almost 30 years ago, the monoclonal antibody Py was developed to detect pyramidal neurons in the CA3 region of the rat hippocampus. The utility of this antibody quickly expanded when several groups discovered that it could be used to identify very specific populations of neurons in the normal, developing, and diseased or injured central nervous system. Despite this body of literature, the identity of the antigen that the Py antibody recognizes remained elusive. Here, immunoprecipitation experiments from the adult rat cortex identified the Py antigen as neurofilament heavy chain (NF-H). Double immunolabeling of sections through the rat brain using Py and NF-H antibodies confirmed the identity of the Py antigen, and reveal that Py/NF-H+ neurons appear to share the feature of being particularly large in diameter. These include the neurons of the gigantocellular reticular formation, pyramidal neurons of layers II/III and V of the cortex, cerebellar Purkinje neurons as well as CA3 pyramidal neurons. Taken together, this finding gives clarity to past work using the monoclonal Py antibody, and immediately expands our understanding of the importance of NF-H in neural development, functioning, and disease.

Cerebrospinal fluid interferon alpha levels correlate with neurocognitive impairment in ambulatory HIV-Infected individuals.

HIV-associated neurocognitive disorders (HANDs) continue to be common and are associated with increased morbidity and mortality. However, the underlying mechanisms in the combination antiretroviral therapy (cART) era are not fully understood. Interferon alpha (IFNα) is an antiviral cytokine found to be elevated in the cerebrospinal fluid (CSF) of individuals with advanced HIV-associated dementia in the pre-cART era. In this cross-sectional study, we investigated the association between IFNα and neurocognitive performance in ambulatory HIV-infected individuals with milder impairment. An eight-test neuropsychological battery representing six cognitive domains was administered. Individual scores were adjusted for demographic characteristics, and a composite neuropsychological score (NPT-8) was calculated. IFNα and CSF neurofilament light chain (NFL) levels were measured using enzyme-linked immunosorbent assay (ELISA). There were 15 chronically infected participants with a history of significant immunocompromise (median nadir CD4+ of 49 cells/µl). Most participants were neurocognitively impaired (mean global deficit score of 0.86). CSF IFNα negatively correlated with three individual tests (Trailmaking A, Trailmaking B, and Stroop Color-Word) as well as the composite NPT-8 score (r = -0.67, p = 0.006). These negative correlations persisted in multivariable analyses adjusting for chronic hepatitis B and C. Additionally, CSF IFNα correlated strongly with CSF NFL, a marker of neuronal damage (rho = 0.748, p = 0.0013). These results extend findings from individuals with severe HIV-associated dementia in the pre-cART era and suggest that IFNα may continue to play a role in HAND pathogenesis during the cART era. Further investigation into the role of IFNα is indicated.

Novel antibodies to phosphorylated α-synuclein serine 129 and NFL serine 473 demonstrate the close molecular homology of these epitopes.

Pathological inclusions containing aggregated, highly phosphorylated (at serine129) α-synuclein (αS pSer129) are characteristic of a group of neurodegenerative diseases termed synucleinopathies. Antibodies to the pSer129 epitope can be highly sensitive in detecting αS inclusions in human tissue and experimental models of synucleinopathies. However, the generation of extensively specific pSer129 antibodies has been problematic, in some cases leading to the misinterpretation of αS inclusion pathology. One common issue is cross-reactivity to the low molecular mass neurofilament subunit (NFL) phosphorylated at Ser473. Here, we generated a series of monoclonal antibodies to the pSer129 αS and pSer473 NFL epitopes. We determined the relative abilities of the known αS kinases, polo-like kinases (PLK) 1, 2 and 3 and casein kinase (CK) II in phosphorylating NFL and αS, while using this information to characterize the specificity of the new antibodies. NFL can be phosphorylated by PLK1, 2 and 3 at Ser473; however CKII shows the highest phosphorylation efficiency and specificity for this site. Conversely, PLK3 is the most efficient kinase at phosphorylating αS at Ser129, but there is overlay in the ability of these kinases to phosphorylate both epitopes. Antibody 4F8, generated to the pSer473 NFL epitope, was relatively specific for phosphorylated NFL, however it could uniquely cross-react with pSer129 αS when highly phosphorylated, further showing the structural similarity between these phospho-epitopes. All of the new pSer129 antibodies detected pathological αS inclusions in human brains and mouse and cultured cell experimental models of induced synucleinopathies. Several of these pSer129 αS antibodies reacted with the pSer473 NFL epitope, but 2 clones (LS3-2C2 and LS4-2G12) did not. However, LS3-2C2 demonstrated cross-reactivity with other proteins. Our findings further demonstrate the difficulties in generating specific pSer129 αS antibodies, but highlights that the use of multiple antibodies, such as those generated here, can provide a sensitive and accurate assessment of αS pathology.

Increased Intrathecal Immune Activation in Virally Suppressed HIV-1 Infected Patients with Neurocognitive Impairment.

OBJECTIVE: Although milder forms of HIV-associated neurocognitive disorder (HAND) remain prevalent, a correlation to neuronal injury has not been established in patients on antiretroviral therapy (ART). We examined the relationship between mild HAND and CSF neurofilament light protein (NFL), a biomarker of neuronal injury; and CSF neopterin, a biomarker of CNS immunoactivation, in virally suppressed patients on antiretroviral therapy (ART). DESIGN AND METHODS: We selected 99 subjects on suppressive ART followed longitudinally from the CNS HIV Anti-Retroviral Therapy Effects Research (CHARTER) study. Based on standardized comprehensive neurocognitive performance (NP) testing, subjects were classified as neurocognitively normal (NCN; n = 29) or impaired (NCI; n = 70). The NCI group included subjects with asymptomatic (ANI; n = 37) or mild (MND; n = 33) HAND. CSF biomarkers were analyzed on two occasions. RESULTS: Geometric mean CSF neopterin was 25% higher in the NCI group (p = 0.04) and NFL and neopterin were significantly correlated within the NCI group (r = 0.30; p<0.001) but not in the NCN group (r = -0.13; p = 0.3). Additionally, a trend towards higher NFL was seen in the NCI group (p = 0.06). CONCLUSIONS: Mild HAND was associated with increased intrathecal immune activation, and the correlation between neopterin and NFL found in NCI subjects indicates an association between neurocognitive impairment, CNS inflammation and neuronal damage. Together these findings suggest that NCI despite ART may represent an active pathological process within the CNS that needs further characterization in prospective studies.

Health effects following subacute exposure to geogenic dusts from arsenic-rich sediment at the Nellis Dunes Recreation Area, Las Vegas, NV.

Geogenic dust from arid environments is a possible inhalation hazard for humans, especially when using off-road vehicles that generate significant dust. This study focused on immunotoxicological and neurotoxicological effects following subacute exposure to geogenic dust generated from sediments in the Nellis Dunes Recreation Area near Las Vegas, Nevada that are particularly high in arsenic; the naturally-occurring arsenic concentrations in these surficial sediments ranged from 4.8 to 346µg/g. Dust samples from sediments used in this study had a median diameter of 4.5µm and also were a complex mixture of naturally-occurring metals, including aluminum, vanadium, chromium, manganese, iron, cobalt, copper, zinc, strontium, cesium, lead, uranium, and arsenic. Adult female B6C3F1 mice exposed via oropharyngeal aspiration to 0.01 to 100mg dust/kg body weight, four times, a week apart, for 28days, were evaluated 24h after the last exposure. Peripheral eosinophils were increased at all concentrations, serum creatinine was dose responsively increased beginning at 1.0mg/kg/day, and blood urea nitrogen was decreased at 10 and 100mg/kg/day. Antigen-specific IgM responses and natural killer cell activity were dose-responsively suppressed at 0.1mg/kg/day and above. Splenic CD4+CD25+ T cells were decreased at 0.01, 0.1, 10, and 100mg/kg/day. Antibodies against MBP, NF-68, and GFAP were selectively reduced. A no observed adverse effect level of 0.01mg/kg/day and a lowest observed adverse effect level of 0.1mg/kg/day were determined from IgM responses and natural killer cell activity, indicating that exposure to this dust, under conditions similar to our design, could affect these responses.

Cell-free mitochondrial DNA in CSF is associated with early viral rebound, inflammation, and severity of neurocognitive deficits in HIV infection.

Cell-free mitochondiral DNA (mtDNA) is an immunogenic molecule associated with many inflammatory conditions. We evaluated the relationship between cell-free mtDNA in cerebrospinal fluid (CSF) and neurocognitive performance and inflammation during HIV infection. In a cross-sectional analysis, we evaluated the association of mtDNA levels with clinical assessments, inflammatory markers, and neurocognitive performance in 28 HIV-infected individuals. In CSF, we measured mtDNA levels by droplet digital PCR, and soluble CD14 and CD163, neurofilament light, and neopterin by ELISA. In blood and CSF, we measured soluble IP-10, MCP-1, TNF-α, and IL-6 by ELISA, and intracellular expression of IL-2, IFN-γ, and TNF-α in CD4(+) and CD8(+) T cells by flow cytometry. We also evaluated the relationship between CSF pleocytosis and mtDNA longitudinally in another set of five individuals participating in an antiretroviral treatment (ART) interruption study. Cell-free CSF mtDNA levels strongly correlated with neurocognitive performance among individuals with neurocognitive impairment (NCI) (r = 0.77, p = 0.001). CSF mtDNA also correlated with levels of IP-10 in CSF (r = 0.70, p = 0.007) and MCP-1 in blood plasma (r = 0.66, p = 0.01) in individuals with NCI. There were no significant associations between inflammatory markers and mtDNA in subjects without NCI, and levels of mtDNA did not differ between subjects with and without NCI. MtDNA levels preceded pleocytosis and HIV RNA following ART interruption. Cell-free mtDNA in CSF was strongly associated with the severity of neurocognitive dysfunction and inflammation only in individuals with NCI. Our findings suggest that within a subset of subjects cell-free CSF mtDNA is associated with inflammation and degree of NCI.

Bispecificity for myelin and neuronal self-antigens is a common feature of CD4 T cells in C57BL/6 mice.

The recognition of multiple ligands by a single TCR is an intrinsic feature of T cell biology, with important consequences for physiological and pathological processes. Polyspecific T cells targeting distinct self-antigens have been identified in healthy individuals as well as in the context of autoimmunity. We have previously shown that the 2D2 TCR recognizes the myelin oligodendrocyte glycoprotein epitope (MOG)35-55 as well as an epitope within the axonal protein neurofilament medium (NF-M15-35) in H-2(b) mice. In this study, we assess whether this cross-reactivity is a common feature of the MOG35-55-specific T cell response. To this end, we analyzed the CD4 T cell response of MOG35-55-immunized C57BL/6 mice for cross-reactivity with NF-M15-35. Using Ag recall responses, we established that an important proportion of MOG35-55-specific CD4 T cells also responded to NF-M15-35 in all mice tested. To study the clonality of this response, we analyzed 22 MOG35-55-specific T cell hybridomas expressing distinct TCR. Seven hybridomas were found to cross-react with NF-M15-35. Using an alanine scan of NF-M18-30 and an in silico predictive model, we dissected the molecular basis of cross-reactivity between MOG35-55 and NF-M15-35. We established that NF-M F24, R26, and V27 proved important TCR contacts. Strikingly, the identified TCR contacts are conserved within MOG38-50. Our data indicate that due to linear sequence homology, part of the MOG35-55-specific T cell repertoire of all C57BL/6 mice also recognizes NF-M15-35, with potential implications for CNS autoimmunity.

Neurofilament light antibodies in serum reflect response to natalizumab treatment in multiple sclerosis.

BACKGROUND: Increased levels of antibodies to neurofilament light protein (NF-L) in biological fluids have been found to reflect neuroinflammatory responses and neurodegeneration in multiple sclerosis (MS). OBJECTIVE: To evaluate whether levels of serum antibodies against NF-L correlate with clinical variants and treatment response in MS. METHODS: The autoantibody reactivity to NF-L protein was tested in serum samples from patients with relapsing-remitting MS (RRMS) (n=22) and secondary progressive MS (SPMS) (n=26). Two other cohorts of RRMS patients under treatment with natalizumab were analysed cross-sectionally (n=16) and longitudinally (n=24). The follow-up samples were taken at 6, 12, 18 and 24 months after treatment, and the NF-L antibody levels were compared against baseline levels. RESULTS: NF-L antibodies were higher in MS clinical groups than healthy controls and in RRMS compared to SPMS patients (p<0.001). NF-L antibody levels were lower in natalizumab treated than in untreated patients (p<0.001). In the longitudinal series, NF-L antibody levels decreased over time and a significant difference was found following 24 months of treatment compared with baseline measurements (p=0.001). CONCLUSIONS: Drug efficacy in MS treatment indicates the potential use of monitoring the content of antibodies against the NF-L chain as a predictive biomarker of treatment response in MS.

Immune reactivity to neurofilament proteins in the clinical staging of amyotrophic lateral sclerosis.

BACKGROUND: Neurofilament (NF) proteins detection in biological fluids as a by-product of axonal loss is technically challenging and to date relies mostly on cerebrospinal fluid (CSF) measurements. Plasma antibodies against NF proteins and particularly to their soluble light chain (NF-L) could be a more practical surrogate marker for disease staging in amyotrophic lateral sclerosis (ALS), an invariably fatal and clinically heterogeneous neuromuscular disorder. METHODOLOGY: We have used a recombinant neurofilament light chain (NF-L) protein for the ELISA detection of antibodies against NF proteins in plasma samples from a well-characterised cohort of ALS individuals (n:73). The use of an established functional rating scale and of a recently proposed staging of disease progression allowed stratification of the ALS cohort based on disease stage, site of onset, survival and speed of disease progression. RESULTS: Antibody levels to NF proteins in plasma were significantly higher in ALS individuals compared to healthy controls (p<0.001). Higher NF plasma immunoreactivity was seen in advanced ALS cases (stage IVA-B) compared to earlier phases of the disease (p<0.05). There was no difference in anti-NF plasma antibodies between ALS individuals treated with riluzole and untreated patients; although riluzole-treated ALS cases with an earlier age of onset and with a shorter diagnostic delay displayed higher anti-NFL antibody levels compared to untreated ALS patients with similar features. CONCLUSIONS: Immunoreactivity to plasma NF-L and homologous NF proteins is informative of the stage of disease progression in ALS. The determination of NF antibody levels in plasma could be added to the growing panel of disease-monitoring biomarkers in ALS targeting cytoskeletal antigens.