[Novel immunomodulatory therapies in myasthenia gravis]. / Myasthénie grave : nouvelles thérapies immunosuppressives.

Myasthenia gravis (MG) is an autoimmune disease characterized by fluctuating weakness of skeletal muscles. Despite current treatments, a significant percentage of patients remain symptomatic. This review explores new immunosuppressive therapies and ongoing clinical trials in MG, including depletion of B lymphocytes with agents such as rituximab and inebilizumab, as well as the use of eculizumab, efgartigimod, satralizumab, tocilizumab, and CAR-T (Chimeric Antigen Receptor-T) cell therapy. These advancements aim to improve disease control and patients' quality of life.

La myasthénie grave (MG) est une maladie auto-immune caractérisée par une faiblesse fluctuante des muscles squelettiques. Malgré les traitements classiques, un pourcentage significatif de patients reste symptomatique. Cet article explore les nouvelles thérapies immunosuppressives et les essais cliniques en cours pour la MG, notamment la déplétion des lymphocytes B avec des agents tels que le rituximab et l'inébilizumab, ainsi que l'utilisation de l'éculizumab, de l'efgartigimod, du satralizumab, du tocilizumab et de la thérapie par cellules CAR-T (Chimeric Antigen Receptor-T). Ces avancées visent à améliorer le contrôle de la maladie et la qualité de vie des patients.

c-Met+ Cytotoxic T Lymphocytes Exhibit Enhanced Cytotoxicity in Mice and Humans In Vitro Tumor Models.

CD8+ cytotoxic T lymphocytes (CTLs) play a crucial role in anti-tumor immunity. In a previous study, we identified a subset of murine effector CTLs expressing the hepatocyte growth factor (HGF) receptor, c-Met (c-Met+ CTLs), that are endowed with enhanced cytolytic capacity. HGF directly inhibited the cytolytic function of c-Met+ CTLs, both in 2D in vitro assays and in vivo, leading to reduced T cell responses against metastatic melanoma. To further investigate the role of c-Met+ CTLs in a three-dimensional (3D) setting, we studied their function within B16 melanoma spheroids and examined the impact of cell-cell contact on the modulation of inhibitory checkpoint molecules' expression, such as KLRG1, PD-1, and CTLA-4. Additionally, we evaluated the cytolytic capacity of human CTL clones expressing c-Met (c-Met+) and compared it to c-Met- CTL clones. Our results indicated that, similar to their murine counterparts, c-Met+ human CTL clones exhibited increased cytolytic activity compared to c-Met- CTL clones, and this enhanced function was negatively regulated by the presence of HGF. Taken together, our findings highlight the potential of targeting the HGF/c-Met pathway to modulate CTL-mediated anti-tumor immunity. This research holds promise for developing strategies to enhance the effectiveness of CTL-based immunotherapies against cancer.

Functional connectivity underlying cognitive and psychiatric symptoms in post-COVID-19 syndrome: is anosognosia a key determinant?

Lack of awareness of cognitive impairment (i.e. anosognosia) could be a key factor for distinguishing between neuropsychological post-COVID-19 condition phenotypes. In this context, the 2-fold aim of the present study was to (i) establish the prevalence of anosognosia for memory impairment, according to the severity of the infection in the acute phase and (ii) determine whether anosognosic patients with post-COVID syndrome have a different cognitive and psychiatric profile from nosognosic patients, with associated differences in brain functional connectivity. A battery of neuropsychological, psychiatric, olfactory, dyspnoea, fatigue and quality-of-life tests was administered 227.07 ± 42.69 days post-SARS-CoV-2 infection to 102 patients (mean age: 56.35 years, 65 men, no history of neurological, psychiatric, neuro-oncological or neurodevelopmental disorder prior to infection) who had experienced either a mild (not hospitalized; n = 45), moderate (conventional hospitalization; n = 34) or severe (hospitalization with intensive care unit stay and mechanical ventilation; n = 23) presentation in the acute phase. Patients were first divided into two groups according to the presence or absence of anosognosia for memory deficits (26 anosognosic patients and 76 nosognosic patients). Of these, 49 patients underwent an MRI. Structural images were visually analysed, and statistical intergroup analyses were then performed on behavioural and functional connectivity measures. Only 15.6% of patients who presented mild disease displayed anosognosia for memory dysfunction, compared with 32.4% of patients with moderate presentation and 34.8% of patients with severe disease. Compared with nosognosic patients, those with anosognosia for memory dysfunction performed significantly more poorly on objective cognitive and olfactory measures. By contrast, they gave significantly more positive subjective assessments of their quality of life, psychiatric status and fatigue. Interestingly, the proportion of patients exhibiting a lack of consciousness of olfactory deficits was significantly higher in the anosognosic group. Functional connectivity analyses revealed a significant decrease in connectivity, in the anosognosic group as compared with the nosognosic group, within and between the following networks: the left default mode, the bilateral somatosensory motor, the right executive control, the right salient ventral attention and the bilateral dorsal attention networks, as well as the right Lobules IV and V of the cerebellum. Lack of awareness of cognitive disorders and, to a broader extent, impairment of the self-monitoring brain system, may be a key factor for distinguishing between the clinical phenotypes of post-COVID syndrome with neuropsychological deficits.

Update in immunosuppressive therapy of myasthenia gravis.

Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction. Immunosuppressive treatments are part of the therapeutic armamentarium in MG. Long-term systemic steroid administration carry considerable risks and adverse events. Consequently, steroid-free immunosuppressive therapy is necessary to reduce the dose or discontinue steroids. First immunosuppressive drug trials in MG were performed in the mid-60s using standard and nonspecific immunosuppression. Since then, only few randomized controlled clinical trials were conducted in MG and assesed drug efficacy in terms of its steroid-sparing capacity and the ability to reduce myasthenic signs and symptoms. Treatment strategy in MG is quite challenging, mainly due to the disease heterogeneity in terms of clinical presentation, immunopathogenesis and drug response. To solve this dilemma, emerging treatment are based on biological drugs and use new targets of the immune pathway.

Brainstem progressive multifocal leukoencephalopathy.

BACKGROUND AND PURPOSE: Progressive multifocal leukoencephalopathy (PML) is a severe infection caused by the polyomavirus JC that develops in the central nervous system (CNS) of immunosuppressed patients. The infection frequently starts in the brain hemispheres and can spread into other CNS regions such as the brainstem. Initial isolated PML brainstem lesions are exceptional. We aimed to describe the challenging diagnosis of PML with isolated brainstem lesions at the time of disease onset. METHODS: We describe a case of PML starting with an isolated brainstem lesion and reviewed clinical, radiological, and biological features of all the reported cases of isolated brainstem PML. RESULTS: Isolated brainstem PML at disease onset is extremely rare. In addition to our case, only nine PML cases presenting with strictly isolated radioanatomical brainstem location at the time of disease onset were retrieved through the literature. All patients share similar brain magnetic resonance imaging features, without contrast enhancement. Eight patients presented with initial clinical worsening, but full recovery occurred in three patients, partial recovery in two, and death in three. Even if prognosis is reserved because of the surrounding vital structures in the brainstem, clinical recovery may occur. CONCLUSIONS: This case report and literature review emphasize that isolated brainstem lesion is an atypical presentation of PML at disease onset.

c-Met is expressed by highly autoreactive encephalitogenic CD8+ cells.

BACKGROUND: CD8+ T lymphocytes are critical mediators of neuroinflammatory diseases. Understanding the mechanisms that govern the function of this T cell population is crucial to better understanding central nervous system autoimmune disease pathology. We recently identified a novel population of highly cytotoxic c-Met-expressing CD8+ T lymphocytes and found that hepatocyte growth factor (HGF) limits effective murine cytotoxic T cell responses in cancer models. Here, we examined the role of c-Met-expressing CD8+ T cells by using a MOG35-55 T cell-mediated EAE model. METHODS: Mice were subcutaneously immunized with myelin oligodendrocyte glycoprotein peptide (MOG)35-55 in complete Freund's adjuvant (CFA). Peripheral and CNS inflammation was evaluated at peak disease and chronic phase, and c-Met expression by CD8 was evaluated by flow cytometry and immunofluorescence. Molecular, cellular, and killing function analysis were performed by real-time PCR, ELISA, flow cytometry, and killing assay. RESULTS: In the present study, we observed that a fraction of murine effector CD8+ T cells expressed c-Met receptor (c-Met+CD8+) in an experimental autoimmune encephalitis (EAE) model. Phenotypic and functional analysis of c-Met+CD8+ T cells revealed that they recognize the encephalitogenic epitope myelin oligodendrocyte glycoprotein37-50. We demonstrated that this T cell population produces higher levels of interferon-γ and granzyme B ex vivo and that HGF directly restrains the cytolytic function of c-Met+CD8+ T cells in cell-mediated cytotoxicity reactions CONCLUSIONS: Altogether, our findings suggest that the HGF/c-Met pathway could be exploited to modulate CD8+ T cell-mediated neuroinflammation.

A proliferation-inducing ligand-mediated anti-inflammatory response of astrocytes in multiple sclerosis.

OBJECTIVE: The two related tumor necrosis factor members a proliferation-inducing ligand (APRIL) and B-cell activation factor (BAFF) are currently targeted in autoimmune diseases as B-cell regulators. In multiple sclerosis (MS), combined APRIL/BAFF blockade led to unexpected exacerbated inflammation in the central nervous system (CNS) of patients. Here, we investigate the role of the APRIL/BAFF axis in the CNS. METHODS: APRIL expression was analyzed in MS lesions by immunohistochemistry. The in vivo role of APRIL was assessed in the murine MS model, experimental autoimmune encephalitis (EAE). Functional in vitro studies were performed with human and mouse astrocytes. RESULTS: APRIL was expressed in lesions from EAE. In its absence, the disease was worst. Lesions from MS patients also showed APRIL expression upon infiltration of macrophages. Notably, all the APRIL secreted by these macrophages specifically targeted astrocytes. The upregulation of chondroitin sulfate proteoglycan, sometimes bearing chondroitin sulfate of type E sugar moieties, binding APRIL, in reactive astrocytes explained the latter selectivity. Astrocytes responded to APRIL by producing a sufficient amount of IL-10 to dampen antigen-specific T-cell proliferation and pathogenic cytokine secretion. Finally, an intraspinal delivery of recombinant APRIL before disease onset, shortly reduced EAE symptoms. Repeated intravenous injections of recombinant APRIL before and even at disease onset also had an effect. INTERPRETATION: Our data show that APRIL mediates an anti-inflammatory response from astrocytes in MS lesions. This protective activity is not shared with BAFF. ANN NEUROL 2019;85:406-420.

IL-8 as a potential biomarker in Guillain-Barre Syndrome.

This pilot study was designed to compare the levels of interleukin-8 (IL-8), a pro-inflammatory chemokine, in the cerebrospinal fluid (CSF) of patients with Guillain-Barre syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), non-inflammatory polyneuropathy (PNP), and other non-inflammatory neurological diseases (functional syndrome or migraine). The results show elevated CSF IL-8 levels in GBS compared to the other groups (p < 0.05). IL-8 could be considered a potential biomarker to differentiate GBS from CIDP. This distinction could be relevant in terms of therapeutic decisions and functional prognosis.

Limbic encephalitis associated with systemic sclerosis.

We report the case of a patient affected by systemic sclerosis (SSc) who developed autoimmune limbic encephalitis, which improved under immunosuppressant agents and high-dose intravenous immunoglobulins. In our patient the autoimmune encephalitis occurred during apparently quiescent SSc, though concomitantly with novel arthritis. Moreover, our patient showed auto-antibodies directed against SSA antigen but the panel of auto-antibodies associated with autoimmune encephalitis was negative. We discuss the potential for immunopathogenic inflammatory events affecting the central nervous system in SSc then favoring the occurrence of autoimmune encephalitic disorders. The possibility of a "neuro-scleroderma" may have important consequences in terms of therapeutic approaches.

In-vivo gp100-specific Cytotoxic CD8+ T Cell Killing Assay.

Cytotoxic CD8+ T lymphocytes (CTLs) represent a crucial component of the adaptive immune system and play a prominent role in the anti-tumor immune responses of both mice and humans. Cytotoxic CD8+ T cells are responsible for the lysis of cells expressing peptides associated with MHC class I molecules and derived from infection with a pathogen or from mutated antigens. In order to quantify in vivo this antigen-specific CD8+ T cell killing activity, we use the in vivo killing assay (IVKA). Here, we describe the protocol for the lysis of cells expressing a CD8+ T cell melanoma epitope of the hgp10025-33 protein (KVPRNQDWL). C57BL/6 recipient mice, receive first target cells, prepared from naive congenic (CD45.1) C57BL/6 spleen cells pulsed with the hgp10025-33 peptide and labeled with CFSE and of non-pulsed control cells labeled with Brilliant violet. One day later, the spleen cells of recipient mice are isolated and analyzed by FACS to measure the amount of CFSE cells and Brillant Violet (BV) cells. The percentage of lysis is calculated by the difference between CFSE versus BV. Measuring the ability of antigen-specific CD8+ T cells to lyse their antigen in vivo is very important to evaluate the adaptive cytotoxic response induced against a pathogen or a tumor antigen.

Identification of a novel population of highly cytotoxic c-Met-expressing CD8+ T lymphocytes.

CD8+ cytotoxic T lymphocytes (CTLs) are critical mediators of anti-tumor immunity, and controlling the mechanisms that govern CTL functions could be crucial for enhancing patient outcome. Previously, we reported that hepatocyte growth factor (HGF) limits effective murine CTL responses via antigen-presenting cells. Here, we show that a fraction of murine effector CTLs expresses the HGF receptor c-Met (c-Met+ CTLs). Phenotypic and functional analysis of c-Met+ CTLs reveals that they display enhanced cytolytic capacities compared to their c-Met- CTL counterparts. Furthermore, HGF directly restrains the cytolytic function of c-Met+ CTLs in cell-mediated cytotoxicity reactions in vitro and in vivo and abrogates T-cell responses against metastatic melanoma in vivo Finally, we establish in three murine tumor settings and in human melanoma tissues that c-Met+ CTLs are a naturally occurring CD8+ T-cell population. Together, our findings suggest that the HGF/c-Met pathway could be exploited to control CD8+ T-cell-mediated anti-tumor immunity.

Activation of human B cells negatively regulates TGF-ß1 production.

BACKGROUND: Accumulating evidence indicate that B cells can exhibit pro- or anti-inflammatory activities. Similar to interleukin (IL)-10-competent B cells, we recently showed that transforming growth factor (TGF)-ß1-producing regulatory B cells limit the induction of autoimmune neuroinflammation in mice, making them potentially important in maintaining peripheral immune tolerance in central nervous system inflammatory demyelinating disorders such as multiple sclerosis. METHODS: In this study, we compared B cell production of TGF-ß1 and IL-10, the two most studied regulatory cytokines, and the pro-inflammatory B cell-derived IL-6 and tumor necrosis factor cytokines under basal conditions and following polyclonal stimulation with dual B cell receptor (BCR) cross-linking and Toll-like receptor (TLR)9 engagement. RESULTS: We showed that resting TGF-ß1-producing B cells fall within both the naïve (CD27-) and memory (CD27+) B cell compartments. We found no spontaneous B cell-derived IL-10, IL-6 or tumor necrosis factor (TNF) production. Human B cell activation with anti-Ig antibodies plus CPG-B leads to only modest IL-10 production by memory CD19+CD27+ B cells while expression levels of IL-6 and TNF by both naive and memory B cells were strongly induced. Remarkably, stimulated B cells showed significantly reduced capacity to produce TGF-ß1. CONCLUSIONS: These findings indicate that B cell activation may facilitate the development of excessive immune responses and autoimmunity by restricting B cell-derived TGF-ß1 production by resting B cells and favoring in turns the proinflammatory actions of activated cytokine-producing B cells.

Anti-ApoA-1 IgG serum levels predict worse poststroke outcomes.

BACKGROUND: Autoantibodies to apolipoprotein A-1 (anti-ApoA-1 IgG) were shown to predict major adverse cardiovascular events and promote atherogenesis. However, their potential relationship with clinical disability and ischaemic lesion volume after acute ischaemic stroke (AIS) remains unexplored. MATERIALS AND METHODS: We included n = 76 patients admitted for AIS and we investigated whether baseline serum anti-ApoA-1 IgG levels could predict (i) AIS-induced clinical disability [assessed by the modified Rankin Scale (mRS)], and (ii) AIS-related ischaemic lesion volume [assessed by Computed Tomography (CT)]. We also evaluated the possible pro-apoptotic and pro-necrotic effects of anti-ApoA-1 IgG on human astrocytoma cell line (U251) using flow cytometry. RESULTS: High levels of anti-ApoA-1 IgG were retrieved in 15·8% (12/76) of patients. Increased baseline levels of anti-ApoA-1 IgG were independently correlated with worse mRS [ß = 0·364; P = 0·002; adjusted odds ratio (OR): 1·05 (95% CI 1·01-1·09); P = 0·017] and CT-assessed ischaemic lesion volume [ß = 0·333; P < 0·001; adjusted OR: 1·06 (95% CI 1·01-1·12); P = 0·048] at 3 months. No difference in baseline clinical, biochemical and radiological characteristics was observed between patients with high vs. low levels of anti-ApoA-1 IgG. Incubating human astrocytoma cells with anti-ApoA-1 IgG dose dependently induced necrosis and apoptosis of U251 cells in vitro. CONCLUSION: Anti-ApoA-1 IgG serum levels at AIS onset are associated with poorer clinical recovery and worse brain lesion volume 3 months after AIS. These observations could be partly explained by the deleterious effect of anti-ApoA-1 IgG on human brain cell survival in vitro and may have clinical implication in the prediction of poor outcome in AIS.

[Paraneoplastic neurological syndromes: an update]. / Syndromes neurologiques paranéoplasiques: mise à jour.

Paraneoplastic neurological syndromes are a group of neurological syndromes secondary to an underlying malignancy. Associated autoantibodies can be classified according to the cellular localization of the antigen target. Onconeuronal autoantibodies (targeting intracellular antigens) strongly associate with cancer and the response to immunotherapy is often disappointing. Identifying and treating the underlying malignancy is a high priority. However, immunomodulation can provide a favourable outcome for neurological symptoms associated with autoantibodies specific for cell membrane antigens. An early recognition of these disorders following the triad "clinical neurological syndrome--specific autoantibodies--tumour research" is important so that patients can benefit from appropriate targeted treatments.

Hematologic modifications in natalizumab-treated multiple sclerosis patients: An 18-month longitudinal study.

OBJECTIVE: To monitor the hematologic modifications in the peripheral blood of patients with relapsing-remitting multiple sclerosis treated with natalizumab. METHODS: The cohort included 44 patients with relapsing-remitting multiple sclerosis treated monthly with natalizumab for 18 months. Peripheral blood was collected before treatment initiation and on a monthly basis during the treatment course. Complete blood cell count was performed using automated hematology systems. Blood smears were prepared and analyzed when abnormal values were detected. RESULTS: Mean total white blood cell, lymphocyte, and eosinophil counts were significantly higher 1 month after treatment initiation and remained stable during the 18 months of follow-up. Monocyte counts increased progressively during the 18-month treatment with natalizumab. Erythroblasts and neutrophil precursors were absent before treatment initiation but were present in 16% and 6.8% of patients, respectively, 1 month after the first natalizumab infusion. The proportion of patients with erythroblasts and neutrophil precursors remained stable throughout the 18-month follow-up period. On an individual patient basis, a fluctuating level of erythroblasts and neutrophil precursors was observed. No difference in mean erythrocyte, hemoglobin, hematocrit, thrombocyte, and neutrophil levels was observed before and after 18 months of natalizumab treatment. No cases of myelodysplastic syndrome or acute leukemia were observed. CONCLUSION: Chronic treatment with natalizumab is associated with significant modifications in complete blood cell count, including emergence of hematopoietic precursors that are not present in peripheral blood under normal conditions. None of these modifications were associated with malignancy.

Cerebrospinal fluid angiotensin-converting enzyme for diagnosis of neurosarcoidosis.

BACKGROUND: Neurosarcoidosis (NS) is a rare condition that may mimic central nervous system (CNS) infection, neoplasia and other inflammatory disorders of the CNS such as multiple sclerosis, encephalitis and vasculitis. Diagnosis is challenging in cases with minimal or absent systemic involvement. Cerebrospinal fluid (CSF) angiotensin-converting enzyme (c-ACE) has been claimed as a valuable diagnostic tool for NS. However, there is little data evaluating its performance in routine clinical practice. FINDINGS: We performed a monocentric, retrospective, chart-based study including all patients investigated with a lumbar puncture and c-ACE dosage for suspected NS between 01/01/2006 and 31/12/2012 at the Geneva University Hospital. Receiver-operating characteristic (ROC) curve and area under the curve (AUC) were performed to calculate the optimal cut-off value of c-ACE and to determine the discriminative ability of c-ACE. Of the 440 patients included in the study, 9 were diagnosed with NS on the basis of tissue biopsy. Mean c-ACE was not significantly different between NS and non-NS patients. With a cut-off value of 2 (0-2 vs ≥3), sensitivity and specificity of c-ACE were 66.7% and 67.3%, respectively. CONCLUSIONS: In our clinical setting, the sensitivity and specificity of c-ACE for NS diagnosis were relatively poor and of little clinical utility.

A phase IIa randomized clinical study testing GNbAC1, a humanized monoclonal antibody against the envelope protein of multiple sclerosis associated endogenous retrovirus in multiple sclerosis patients - a twelve month follow-up.

GNbAC1 is a humanized monoclonal antibody targeting MSRV-Env, an endogenous retroviral protein, which is expressed in multiple sclerosis (MS) lesions, is pro-inflammatory and inhibits oligodendrocyte precursor cell differentiation. This paper describes the open-label extension up to 12months of a trial testing GNbAC1 in 10 MS patients at 2 and 6mg/kg. The primary objective was to assess GNbAC1 safety, and other objectives were pharmacokinetic and pharmacodynamic assessments. During the extended study, no safety issues occurred in the 8 remaining patients. No anti-GNbAC1 antibodies were detected. GNbAC1 appears well tolerated.

A phase IIa randomised clinical study of GNbAC1, a humanised monoclonal antibody against the envelope protein of multiple sclerosis-associated endogenous retrovirus in multiple sclerosis patients.

BACKGROUND: GNbAC1 is an immunoglobulin (IgG4) humanised monoclonal antibody against multiple sclerosis-associated retrovirus (MSRV)-Env, a protein of endogenous retroviral origin, expressed in multiple sclerosis (MS) lesions, which is pro-inflammatory and inhibits oligodendrocyte precursor cell differentiation. OBJECTIVE: This is a randomised, double-blind placebo-controlled dose-escalation study followed by a six-month open-label phase to test GNbAC1 in MS patients. The primary objective was to assess GNbAC1 safety in MS patients, and the other objectives were pharmacokinetic and pharmacodynamic assessments. METHODS: Ten MS patients were randomised into two cohorts to receive a single intravenous infusion of GNbAC1/placebo at doses of 2 or 6 mg/kg. Then all patients received five infusions of GNbAC1 at 2 or 6 mg/kg at four-week intervals in an open-label setting. Safety, brain magnetic resonance imaging (MRI), pharmacokinetics, immunogenicity, cytokines and MSRV RNA expression were studied. RESULTS: All patients completed the study. GNbAC1 was well tolerated in all patients. GNbAC1 pharmacokinetics is dose-linear with mean elimination half-life of 27-37 d. Anti-GNbAC1 antibodies were not detected. Cytokine analysis did not indicate an adverse effect. MSRV-transcripts showed a decline after the start of treatment. Nine patients had stable brain lesions at MRI. CONCLUSION: The safety, pharmacokinetic profile, and pharmacodynamic responses to GNbAC1 are favourable in MS patients over a six-month treatment period.