Protection or susceptibility to devastating childhood epilepsy: Nodding Syndrome associates with immunogenetic fingerprints in the HLA binding groove.

Nodding syndrome (NS) is a devastating and enigmatic childhood epilepsy. NS is accompanied by multiple neurological impairments and neuroinflammation, and associated with the parasite Onchocerca volvulus (Ov) and other environmental factors. Moreover, NS seems to be an 'Autoimmune Epilepsy' since: 1. ~50% of NS patients have neurotoxic cross-reactive Ov/Leimodin-I autoimmune antibodies. 2. Our recently published findings: Most (~86%) of NS patients have glutamate-receptor AMPA-GluR3B peptide autoimmune antibodies that bind, induce Reactive Oxygen Species, and kill both neural cells and T cells. Furthermore, NS patient's IgG induce seizures, brain multiple damage alike occurring in brains of NS patients, and elevation of T cells and activated microglia and astrocytes, in brains of normal mice. Human Leukocyte antigen (HLA) class I and II molecules are critical for initiating effective beneficial immunity against foreign microorganisms and contributing to proper brain function, but also predispose to detrimental autoimmunity against self-peptides. We analyzed seven HLA loci, either by next-generation-sequencing or Sequence-Specific-Oligonucleotide-Probe, in 48 NS patients and 51 healthy controls from South Sudan. We discovered that NS associates significantly with both protective HLA haplotype: HLA-B*42:01, C*17:01, DRB1*03:02, DQB1*04:02 and DQA1*04:01, and susceptible motif: Ala24, Glu63 and Phe67, in the HLA-B peptide-binding groove. These amino acids create a hydrophobic and sterically closed peptide-binding HLA pocket, favoring proline residue. Our findings suggest that immunogenetic fingerprints in HLA peptide-binding grooves tentatively associate with protection or susceptibility to NS. Accordingly, different HLA molecules may explain why under similar environmental factors, only some children, within the same families, tribes and districts, develop NS, while others do not.

Dual-Targeted Autoimmune Sword in Fatal Epilepsy: Patient's glutamate receptor AMPA GluR3B peptide autoimmune antibodies bind, induce Reactive Oxygen Species (ROS) in, and kill both human neural cells and T cells.

Nodding Syndrome (NS) is a fatal pediatric epilepsy of unknown etiology, accompanied by multiple neurological impairments, and associated with Onchocerca volvulus (Ov), malnutrition, war-induced trauma, and other insults. NS patients have neuroinflammation, and ~50% have cross-reactive Ov/Leiomodin-1 neurotoxic autoimmune antibodies. RESULTS: Studying 30 South Sudanese NS patients and a similar number of healthy subjects from the same geographical region, revealed autoimmune antibodies to 3 extracellular peptides of ionotropic glutamate receptors in NS patients: AMPA-GluR3B peptide antibodies (86%), NMDA-NR1 peptide antibodies (77%) and NMDA-NR2 peptide antibodies (87%) (in either 1:10, 1:100 or 1:1000 serum dilution). In contrast, NS patients did not have 26 other well-known autoantibodies that target the nervous system in several autoimmune-mediated neurological diseases. We demonstrated high expression of both AMPA-GluR3 and NMDA-NR1 in human neural cells, and also in normal human CD3+ T cells of both helper CD4+ and cytotoxic CD8+ types. Patient's GluR3B peptide antibodies were affinity-purified, and by themselves precipitated short 70 kDa neuronal GluR3. NS patient's affinity-purified GluR3B peptide antibodies also bound to, induced Reactive Oxygen Species (ROS) in, and killed both human neural cells and T cells within 1-2 hours only. NS patient's purified IgGs, or serum (1:10 or 1:30), induced similar effects. In vivo video EEG experiments in normal mice, revealed that when NS patient's purified IgGs were released continuously (24/7 for 1 week) in normal mouse brain, they induced all the following: 1.Seizures, 2. Cerebellar Purkinje cell loss, 3. Degeneration in the hippocampus and cerebral cortex, and 4. Elevation of CD3+ T cells, and of activated Mac-2+microglia and GFAP+astrocytes in both the gray and white matter of the cerebral cortex, hippocampus, corpus calossum and cerebellum of mice. NS patient's serum cytokines: IL-1ß, IL-2, IL-6, IL-8, TNFα, IFNγ, are reduced by 85-99% compared to healthy subjects, suggesting severe immunodeficiency in NS patients. This suspected immunodeficiency could be caused by combined effects of the: 1. Chronic Ov infection, 2. Malnutrition, 3. Killing of NS patient's T cells by patient's own GluR3B peptide autoimmune antibodies (alike the killing of normal human T cells by the NS patient's GluR3B peptide antibodies found herein in vitro). CONCLUSIONS: Regardless of NS etiology, NS patients suffer from 'Dual-targeted Autoimmune Sword': autoimmune AMPA GluR3B peptide antibodies that bind, induce ROS in, and kill both neural cells and T cells. These neurotoxic and immunotoxic GluR3B peptide autoimmune antibodies, and also NS patient's NMDA-NR1/NR2A and Ov/Leiomodin-1 autoimmune antibodies, must be silenced or removed. Moreover, the findings of this study are relevant not only to NS, but also to many more patients with other types of epilepsy, which have GluR3B peptide antibodies in serum and/or CSF. This claim is based on the following facts: 1. The GluR3 subunit is expressed in neural cells in crucial brains regions, in motor neurons in the spinal cord, and also in other cells in the body, among them T cells of the immune system, 2. The GluR3 subunit has diverse neurophysiological role, and its deletion or abnormal function can: disrupt oscillatory networks of both sleep and breathing, impair motor coordination and exploratory activity, and increase the susceptibility to generate seizures, 3. GluR3B peptide antibodies were found so far in ~27% of >300 epilepsy patients worldwide, which suffer from various other types of severe, intractable and enigmatic epilepsy, and which turned out to be 'Autoimmune Epilepsy'. Furthermore, the findings of this study could be relevant to different neurological diseases besides epilepsy, since other neurotransmitter-receptors autoantibodies are present in other neurological and psychiatric diseases, e.g. autoimmune antibodies against other GluRs, Dopamine receptors, GABA receptors, Acetylcholine receptors and others. These neurotransmitter-receptors autoimmune autoantibodies might also act as 'Dual-targeted Autoimmune Sword' and damage both neural cells and T cells (as the AMPA-GluR3B peptide antibodies induced in the present study), since T cells, alike neural cells, express most if not all these neurotransmitter receptors, and respond functionally to the respective neurotransmitters - a scientific and clinical topic we coined 'Nerve-Driven Immunity'.

Nodding Syndrome in the Spotlight - Placing Recent Findings in Perspective.

Nodding syndrome (NS) is a debated scientific topic. A recently published study suggests that NS is an autoimmune disorder based on findings of cross-reacting antibodies between neuronal structures and a protein present in Onchocerca volvulus (OV). In our opinion, the proposed causal relationship between OV infection and NS has yet to be demonstrated and, instead, OV infection in NS may be opportunistic.

Nodding syndrome may be an autoimmune reaction to the parasitic worm Onchocerca volvulus.

Nodding syndrome is an epileptic disorder of unknown etiology that occurs in children in East Africa. There is an epidemiological association with Onchocerca volvulus, the parasitic worm that causes onchocerciasis (river blindness), but there is limited evidence that the parasite itself is neuroinvasive. We hypothesized that nodding syndrome may be an autoimmune-mediated disease. Using protein chip methodology, we detected autoantibodies to leiomodin-1 more abundantly in patients with nodding syndrome compared to unaffected controls from the same village. Leiomodin-1 autoantibodies were found in both the sera and cerebrospinal fluid of patients with nodding syndrome. Leiomodin-1 was found to be expressed in mature and developing human neurons in vitro and was localized in mouse brain to the CA3 region of the hippocampus, Purkinje cells in the cerebellum, and cortical neurons, structures that also appear to be affected in patients with nodding syndrome. Antibodies targeting leiomodin-1 were neurotoxic in vitro, and leiomodin-1 antibodies purified from patients with nodding syndrome were cross-reactive with O. volvulus antigens. This study provides initial evidence supporting the hypothesis that nodding syndrome is an autoimmune epileptic disorder caused by molecular mimicry with O. volvulus antigens and suggests that patients may benefit from immunomodulatory therapies.