IgM ganglioside GM1 antibodies in patients with autoimmune disease or neuropathy, and controls

Identification of the Lipid Antigens Recognized by rHIgM22, a Remyelination-Promoting Antibody

Failure of the immune system to discriminate myelin components from foreign antigens plays a critical role in the pathophysiology of multiple sclerosis. In fact, the appearance of anti-myelin autoantibodies, targeting both proteins and glycolipids, is often responsible for functional alterations in myelin-producing cells in this disease. Nevertheless, some of these antibodies were reported to be beneficial for remyelination. Recombinant human IgM22 (rHIgM22) binds to myelin and to the surface of O4-positive oligodendrocytes, and promotes remyelination in mouse models of chronic demyelination. Interestingly, the identity of the antigen recognized by this antibody remains to be elucidated. The preferential binding of rHIgM22 to sulfatide-positive cells or tissues suggests that sulfatide might be part of the antigen pattern recognized by the antibody, however, cell populations lacking sulfatide expression are also responsive to rHIgM22. Thus, we assessed the binding of rHIgM22 in vitro to purified lipids and lipid extracts from various sources to identify the antigen(s) recognized by this antibody. Our results show that rHIgM22 is indeed able to bind both sulfatide and its deacylated form, whereas no significant binding for other myelin sphingolipids has been detected. Remarkably, binding of rHIgM22 to sulfatide in lipid monolayers can be positively or negatively regulated by the presence of other lipids. Moreover, rHIgM22 also binds to phosphatidylinositol, phosphatidylserine and phosphatidic acid, suggesting that not only sulfatide, but also other membrane lipids might play a role in the binding of rHIgM22 to oligodendrocytes and to other cell types not expressing sulfatide.

Sialoglyco-Conjugate Abnormalities, IL-6 Trans-Signaling and Anti-Ganglioside Immune Response-Potential Interferences in Lupus Nephritis Pathogenesis

We have investigated glycoconjugates sialization profile, endogen synthesis rate of antiganglioside antibodies (AGA), IL-6 signaling pathways correlated with activity disease in systemic lupus erythematous (SLE) and lupus nephritis (LN). Material and methods. A case-control study was developed and included 109 patients with SLE with or without renal impairment, 32 patients with IgA nephropathy and 60 healthy volunteers, clinically and paraclinically monitored. The following parameters were evaluated in volunteers serum: total sialic acid (TSA), orosomucoids, lipid bound sialic acid (LSA), interleukin-6 (IL-6), soluble factors IL-6R, gp130, anti –GM1, -GM2, -GM3, -GD1a, -GD1b, -GT1b, -GQ1b antigangliosides antibodies of IgG and IgM type. Results. Experimental data analysis showed: increase in synthesis rhythm of sialoglyco-conjugated in SLE (TSA increased in SLE and LN compared to control), accelerated catabolism of LSA in LN (LSA/TSA ratio was higher in SLE and LN than in control group), overexpression of IL-6 mediated trans-signaling (sIL-6R/sgp 130 ratio was subunit in SLE and IgA nephropathy and superunit in LN), large AGA profile synthesis of IgM isotype (over 45.1% in SLE and over 20.7% in LN). Conclusions. Hypersialization, accelerated glycosphingolipids degradation, IL-6 trans-signaling amplify and AGA pattern could represent essential mechanisms in LN pathogenesis.

Concomitant development of neurologic and cardiac immune-related adverse effects in patients treated with immune checkpoint inhibitors for melanoma

Immune checkpoint inhibitors (ICI) have altered the prognosis of patients with melanoma over the past few years, with immune-related adverse effects (irAEs) being the only factor limiting their use. Neurologic and cardiac irAEs are rare, but usually severe. We reviewed the files of patients with melanoma treated with ICIs in one center to retrieve data from patients with neurologic irAEs. Patients with a combination of neurologic and cardiac manifestations were further analyzed. We also reviewed the literature for similar syndromes. Five out of 482 (1.01%) patients developed a neurologic syndrome and we present three patients with a constellation of neurologic and cardiac irAEs. A 66-year-old woman and a 68-year-old man presented with a constellation of findings after being treated with ipilimumab and nivolumab, respectively, for melanoma in the adjuvant setting and were eventually diagnosed with myasthenia gravis with cardiac involvement. An 80-year-old woman developed diffuse asymmetric muscle weakness, bilateral ptosis and asymptomatic high serum troponin levels after adjuvant treatment with nivolumab and ipilimumab for a stage IIIB melanoma. After excluding ischemic heart disease, she was diagnosed with axonal polyradiculoneuropathy and myocarditis. Neurologic or cardiac irAEs in patients treated with ICIs are uncommon (<1%), but usually severe, with high rates of morbidity and fatality. The co-development of neurologic and cardiac irAEs is even more rare and can arise soon after exposure to ICIs and escalate rapidly. Since more and more patients are now treated with ICIs in the adjuvant setting, prompt identification and management are essential to avoid serious complications or death.

Antigenic Targets of Patient and Maternal Autoantibodies in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder whose behavioral symptoms become apparent in early childhood. The underlying pathophysiological mechanisms are only partially understood and the clinical manifestations are heterogeneous in nature, which poses a major challenge for diagnosis, prognosis and intervention. In the last years, an important role of a dysregulated immune system in ASD has emerged, but the mechanisms connecting this to a disruption of brain development are still largely unknown. Although ASD is not considered as a typical autoimmune disease, self-reactive antibodies or autoantibodies against a wide variety of targets have been found in a subset of ASD patients. In addition, autoantibodies reactive to fetal brain proteins have also been described in the prenatal stage of neurodevelopment, where they can be transferred from the mother to the fetus by transplacental transport. In this review, we give an extensive overview of the antibodies described in ASD according to their target antigens, their different origins, and timing of exposure during neurodevelopment.

Platelets: Peripheral Biomarkers of Dementia?

Dementia continues to be the most burdening neurocognitive disorder, having a negative impact on the lives of millions. The search for biomarkers to improve the clinical diagnosis of dementia is ongoing, with the focus on effective use of readily accessible peripheral markers. In this review, we concentrate on platelets as biomarkers of dementia and analyze their potential as easily-accessible clinical biomarkers for various subtypes of dementia. Current platelet protein biomarkers that have been investigated for their clinical utility in the diagnosis of dementia, in particular Alzheimer's disease, include amyloid-β protein precursor (AβPP), the AβPP secretases (BACE1 and ADAM10), α-synuclein, tau protein, serotonin, cholesterol, phospholipases, clusterin, IgG, surface receptors, MAO-B, and coated platelets. Few of them, i.e., platelet tau, AβPP (particularly with regards to coated platelets) and secreted ADAM10 and BACE1 show the most promise to be taken forward into clinical setting to diagnose dementia. Aside from protein biomarkers, changes in factors such as mean platelet volume have the potential to play a very specific role in both the dementia diagnosis and prognosis. This review raises a number of research questions for consideration before application of the above biomarkers to routine clinical setting. It is without doubt that there is a need for more clarification on the effects of dementia on platelet morphology and protein content before these changes can be clinically applied as dementia biomarkers and explored further in differentiating distinct dementia subtypes.

Dissecting the Role of Anti-ganglioside Antibodies in Guillain-Barré Syndrome: an Animal Model Approach

Guillain-Barré syndrome (GBS) is an autoimmune polyneuropathy disease affecting the peripheral nervous system (PNS). Most of the GBS patients experienced neurological symptoms such as paresthesia, weakness, pain, and areflexia. There are also combinations of non-neurological symptoms which include upper respiratory tract infection and diarrhea. One of the major causes of GBS is due largely to the autoantibodies against gangliosides located on the peripheral nerves. Gangliosides are sialic acid-bearing glycosphingolipids consisting of a ceramide lipid anchor with one or more sialic acids attached to a neutral sugar backbone. Molecular mimicry between the outer components of oligosaccharide of gangliosides on nerve membrane and lipo-oligosaccharide of microbes is thought to trigger the autoimmunity. Intra-peritoneal implantation of monoclonal ganglioside antibodies secreting hybridoma into animals induced peripheral neuropathy. Recent studies demonstrated that injection of synthesized anti-ganglioside antibodies raised by hybridoma cells into mice initiates immune response against peripheral nerves, and eventually failure in peripheral nerve regeneration. Accumulating evidences indicate that the conjugation of anti-ganglioside monoclonal antibodies to activating FcγRIII present on the circulating macrophages inhibits axonal regeneration. The activation of RhoA signaling pathways is also involved in neurite outgrowth inhibition. However, the link between these two molecular events remains unresolved and requires further investigation. Development of anti-ganglioside antagonists can serve as targeted therapy for the treatment of GBS and will open a new approach of drug development with maximum efficacy and specificity.

Dry eye as a mucosal autoimmune disease

Dry eye is a common ocular surface inflammatory disease that significantly affects quality of life. Dysfunction of the lacrimal function unit (LFU) alters tear composition and breaks ocular surface homeostasis, facilitating chronic inflammation and tissue damage. Accordingly, the most effective treatments to date are geared towards reducing inflammation and restoring normal tear film. The pathogenic role of CD4+ T cells is well known, and the field is rapidly realizing the complexity of other innate and adaptive immune factors involved in the development and progression of disease. The data support the hypothesis that dry eye is a localized autoimmune disease originating from an imbalance in the protective immunoregulatory and proinflammatory pathways of the ocular surface.

Caveolins: targeting pro-survival signaling in the heart and brain

The present review discusses intracellular signaling moieties specific to membrane lipid rafts (MLRs) and the scaffolding proteins caveolin and introduces current data promoting their potential role in the treatment of pathologies of the heart and brain. MLRs are discreet microdomains of the plasma membrane enriched in gylcosphingolipids and cholesterol that concentrate and localize signaling molecules. Caveolin proteins are necessary for the formation of MLRs, and are responsible for coordinating signaling events by scaffolding and enriching numerous signaling moieties in close proximity. Specifically in the heart and brain, caveolins are necessary for the cytoprotective phenomenon termed ischemic and anesthetic preconditioning. Targeted overexpression of caveolin in the heart and brain leads to induction of multiple pro-survival and pro-growth signaling pathways; thus, caveolins represent a potential novel therapeutic target for cardiac and neurological pathologies.

Alteration of CD1 expression in multiple sclerosis

Studies of multiple sclerosis (MS) have concentrated mainly on antigen presentation of peptides derived from the myelin sheath, while the implication of lipid antigen has been less explored in this pathology. As the extracellular environment regulates expression of the lipid antigen-presenting molecule CD1, we have examined whether sera from patients alters CD1 surface expression in monocyte-derived dendritic cells. We have shown that: (i) CD1 group 1 proteins were highly expressed in the presence of MS sera; (ii) sera from MS patients differentially regulated CD1 group 1 versus CD1 group 2 molecular expression; and (iii) CD1 was expressed strongly in monocytes from MS patients under immunosuppressive treatment. Overall, these results reveal that CD1 expression is modified in MS and provide novel information on the regulation of lipid antigen presentation in myeloid cells.

NGcGM3 ganglioside: a privileged target for cancer vaccines

Active specific immunotherapy is a promising field in cancer research. N-glycolyl (NGc) gangliosides, and particularly NGcGM3, have received attention as a privileged target for cancer therapy. Many clinical trials have been performed with the anti-NGc-containing gangliosides anti-idiotype monoclonal antibody racotumomab (formerly known as 1E10) and the conjugated NGcGM3/VSSP vaccine for immunotherapy of melanoma, breast, and lung cancer. The present paper examines the role of NGc-gangliosides in tumor biology as well as the available preclinical and clinical data on these vaccine products. A brief discussion on the relevance of prioritization of cancer antigens in vaccine development is also included.

Peripheral nerves are progressively involved in multiple sclerosis--a hypothesis from a pilot study of temperature sensitized electroneurographic screening

Multiple sclerosis (MS) is primarily a disease of the central nervous system. Although the involvement of the peripheral nervous system in MS was suggested over 100 years ago, the issue is still controversial, and it is generally accepted that except for the optic nerve the peripheral nerves are left unaffected by the disease. We hypothesize, that an electroneurographical study if thorough enough, may reveal differences in some nerve conduction parameters between MS patients and healthy subjects. Second, we assume that the sensitivity of nerve conduction measurements might be increased if performed at a range of temperatures, reflecting a differential effect of cooling and warming on the peripheral nerve conduction parameters in MS patients and controls. Finally, we expect that the differences in these parameters between controls and MS patients will increase with the progression of the disease. To test these hypotheses in a pilot study, we performed a detailed analysis of the motor and sensory nerve conduction features of the right median nerve in 13 MS patients and 13 controls at 5 degrees C increments between 20 and 40 degrees C, and repeated these measurements after 3 years. The motor latencies were 0.3-0.6 ms longer in MS patients compared to the controls both initially and 3 years later (0.058<p<0.09). The durations and areas of the compound motor action potential (CMAP) appeared more sensitive to changes in temperature in the MS group (0.057<p<0.1). The change in both distal motor latency and sensory latency per unit change in temperature decreased significantly in 3 years within the MS but not in the control group. These results suggest a mild and progressive involvement of the PNS in MS. Most differences in this pilot study were on the border of statistical significance therefore our hypotheses should be confirmed in studies with larger sample size.

Koinzidenz von Guillain-Barré-Syndrom und Myelitis

A 28-year-old male patient developed Guillain-Barré syndrome after a pulmonary infection with typical CSF findings. Five days after the onset, pyramidal signs and spastic increase of muscle tonus in the legs were found. The MRI showed increased signals in the whole spinal cord which were identified as myelitis after review of clinical and neurophysiologic findings. There was a remarkable difference between the dramatic pathologic signals on MRI and the mild clinical symptoms. Four months after onset the patient had no more complaints and presented basically recovered in the clinical examination. The existence of Guillain-Barré syndrome together with myelitis is very rare. A patient with such a good outcome in spite of an extended myelitis is extraordinary.

Mini review: immune response to myelin-derived sulfatide and CNS-demyelination

Here we briefly review our understanding of the immune response to myelin-derived glycolipids during an inflammatory autoimmune response in the central nervous system (CNS). We focus primarily on the recognition of the self-glycolipid sulfatide by a distinct population of non-invariant NK T cells. The results of studies we have obtained so far in investigating the presentation of sulfatide by CNS-resident cells including microglia and their interactions with T cells indicate that this pathway might be successfully targeted for the treatment of autoimmune demyelination in multiple sclerosis.

Structural basis for CD1d presentation of a sulfatide derived from myelin and its implications for autoimmunity

Sulfatide derived from the myelin stimulates a distinct population of CD1d-restricted natural killer T (NKT) cells. Cis-tetracosenoyl sulfatide is one of the immunodominant species in myelin as identified by proliferation, cytokine secretion, and CD1d tetramer staining. The crystal structure of mouse CD1d in complex with cis-tetracosenoyl sulfatide at 1.9 Å resolution reveals that the longer cis-tetracosenoyl fatty acid chain fully occupies the A′ pocket of the CD1d binding groove, whereas the sphingosine chain fills up the F′ pocket. A precise hydrogen bond network in the center of the binding groove orients and positions the ceramide backbone for insertion of the lipid tails in their respective pockets. The 3′-sulfated galactose headgroup is highly exposed for presentation to the T cell receptor and projects up and away from the binding pocket due to its β linkage, compared with the more intimate binding of the α-glactosyl ceramide headgroup to CD1d. These structure and binding data on sulfatide presentation by CD1d have important implications for the design of therapeutics that target T cells reactive for myelin glycolipids in autoimmune diseases of the central nervous system.

Immunoserological changes in the cerebro-spinal fluid and serum in systemic lupus erythematosus patients with demyelinating syndrome and multiple sclerosis

The aim of the present study was to investigate the role of antinuclear and antiphospholipid antibodies in the pathogenesis of systemic lupus erythematosus (SLE) with demyelinating syndrome and several forms of multiple sclerosis (MS). Paired samples of serum and cerebrospinal fluid (CSF) were investigated using laser nephalometric and enzyme linked immunosorbant assay (ELISA) methods, and the parameters of intrathecal synthesis were calculated. Elevation of the concentrations of antiribosomal P protein antibodies in the CSF and serum, and intrathecal synthesis anticardiolipin (aCL) antibodies were characteristic in all patient groups. The immunoserological changes were more pronounced in the SLE patients. A similar pathogenetic role of antiphospholipid antibodies in central nervous system (CNS) damage in SLE patients with demyelinating syndrome and of MS patients can be assumed.

Pure trigeminal motor neuropathy: a case report

Pure trigeminal motor neuropathy is a trigeminal motor paralysis unaccompanied by signs of trigeminal sensory or other cranial nerve involvement. We present a case of a 38-year-old man complaining of progressive weakness and wasting of the right masticatory muscles after a bout of mild cold symptoms. No sensory symptoms were present. History, neurologic examination, electrophysiologic studies, and magnetic resonance imaging of the brain led to the diagnosis of pure trigeminal motor neuropathy. The cause may have been an autoimmune reaction to a viral infection.

Antibodies to squalene in Gulf War syndrome

Gulf War Syndrome (GWS) is a multisystemic illness afflicting many Gulf War-era veterans. The molecular pathological basis for GWS has not been established. We sought to determine whether the presence of antibodies to squalene correlates with the presence of signs and symptoms of GWS. Participants in this blinded cohort study were individuals immunized for service in Desert Shield/Desert Storm during 1990-1991. They included 144 Gulf War-era veterans or military employees (58 in the blinded study), 48 blood donors, 40 systemic lupus erythematosus patients, 34 silicone breast implant recipients, and 30 chronic fatigue syndrome patients. Serum antibodies to squalene were measured. In our small cohort, the substantial majority (95%) of overtly ill deployed GWS patients had antibodies to squalene. All (100%) GWS patients immunized for service in Desert Shield/Desert Storm who did not deploy, but had the same signs and symptoms as those who did deploy, had antibodies to squalene. In contrast, none (0%) of the deployed Persian Gulf veterans not showing signs and symptoms of GWS have antibodies to squalene. Neither patients with idiopathic autoimmune disease nor healthy controls had detectable serum antibodies to squalene. The majority of symptomatic GWS patients had serum antibodies to squalene.

Self glycolipids as T-cell autoantigens

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by discrete areas of demyelination. An autoimmune response against components of myelin is thought to contribute to disease pathogenesis. Here we identify glycolipids as new targets recognized by T cells in multiple sclerosis patients. Circulating T cells reactive with glycolipids are more frequent in MS patients than in control donors as shown by enzyme-linked immunospot assay. They specifically recognize different types of glycolipids, such as gangliosides, sulfatide and galactosylceramide and release IFN-gamma and TNF-alpha. T cells specific for gangliosides were found to be CD8+, TCR alphabeta+, restricted by the MHC-like CD1b molecule and specific for epitopes residing in the carbohydrate moiety of gangliosides. Our findings suggest that in addition to self proteins, self glycolipids may represent potential source of autoantigens recognized by T cells in autoimmune diseases.

Inter-laboratory validation of an ELISA for the determination of serum anti-ganglioside antibodies

Anti-ganglioside antibodies are frequently sought in the sera of patients with autoimmune peripheral neuropathy, using an enzyme-linked immunosorbent assay (ELISA) as the principal method for antibody detection. Wide variations in assay performance between laboratories have been reported. In this study, we established a standardized ELISA method between laboratories within the European Inflammatory Neuropathy Cause and Treatment (INCAT) group and determined the inter-laboratory variance in assay performance using both the standardized INCAT method and in-house local methods. As expected, the inter-laboratory variances were greater using local methods than using the standardized method, producing titre estimates which could be 24.8 or 7.6 times larger or smaller, respectively, than the true means for these laboratories. Using the standardized method, the within laboratory measurement error accounted for 41% of the inter-laboratory variation, providing a theoretical upper limit to which technical improvements within laboratories could reduce inter-laboratory variation. These data describe the intrinsic weaknesses within the widely used ganglioside antibody ELISA methods and reinforce the importance of inter-laboratory cooperation within this area. Standardized serological reagents used in this study are available from INCAT members.

Anti-GM1 antibodies in polyneuropathies of unknown origin

This study was undertaken to determine whether anti-GM1 titres are raised in polyneuropathies of unknown origin and whether determination of these titres is useful for diagnosing these conditions. The study population comprised 20 controls (aged 36-88 years), 12 patients with polyneuropathies of known origin (aged 31-81 years) and 15 patients with polyneuropathies of unknown origin (aged 40-77 years). Antibody levels were measured using a commercial GM1 enzyme linked immunosorbent assay kit (Buehlmann Laboratories). Mean anti-GM1 IgG and IgM antibody titres were not raised in patients with polyneuropathies of unknown origin. Anti-GM1 IgG antibody titres were raised in one and GM1 IgM antibody titres in none of the patients with polyneuropathies of unknown origin. In conclusion, GM1 antibody levels are rarely raised in polyneuropathies of unknown origin and probably play a minor role in the pathogenesis of these conditions.

Pathological findings in a patient with amyotrophic lateral sclerosis and multifocal motor neuropathy with conduction block

We studied a 53-year-old woman with progressive weakness of the left arm, gradually spreading to the other limbs. Neurological examination revealed a motor neuron syndrome with paresis, fasciculations and atrophy. Electrophysiological studies showed multiple motor conduction blocks. The anti-GM1 IgM titer was elevated. The patient was thought to have a multifocal motor neuropathy. Despite intravenous cyclophosphamide treatment, however, she died with respiratory insufficiency. On postmortem examination, the brachial plexus showed patches of demyelination underlying different areas of motor conduction block. The spinal cord, however, revealed severe neuronal loss in the ventral horn and axonal loss in the corticospinal tract, indicative of amyotrophic lateral sclerosis. Demyelination of peripheral nerves could have been responsible for the other conduction blocks in this patient. The prominent degeneration of motor neurons, however, must also have played a role in the clinical picture. Some patients with the syndrome of a multifocal motor neuropathy may have MND rather than, or in addition to, a demyelinating peripheral motor neuropathy.