Citations

ABSTRACT Objective We sought to characterize the sixth most common finding in our neuroimmunological laboratory practice (tissue assay‐observed unclassified neural antibodies [UNAs]), combining protein microarray and phage immunoprecipitation sequencing (PhIP‐Seq). Methods Patient specimens (258; 133 serums; 125 CSF) meeting UNA criteria were profiled; October 2022–September 2023. Top‐ranking candidate antigens were validated in silico, by dual‐staining confocal microscopy, and ≥ 1 protein‐specific assay. Clinical data were reviewed. Results Among 21 patients, 11 autoantibodies were characterized (serum, 19; CSF, all 9 available). Autoantigens were CACNA1I, 1; CAMK2B, 2; CLIP2, 1; FMN2, 2; MAP1A, 2; MAP2, 5; NECAB1, 1; SNAP91, 3; SRCIN1, 1; SYNJ1, 1; SYT3, 2. Analytical validation was by confocal TIIFA (all), western blot (10/10 available), and cell‐based assay (5/5 performed). Clinical accompaniments were: encephalitis, 6; brainstem encephalitis, 2; encephalomyelitis, 2; cerebellar ataxia, 2; longitudinally extensive transverse myelitis (LETM), 2; sensory neuronopathy, 1; peripheral neuropathy, 4, and movement disorders, 2. Inflammatory MRI abnormalities were identified in 5/16 patients (31%) with CNS disorders: T2 signal change (2), LETM (2), leptomeningeal enhancement (1). Seven of 8 (88%) had inflammatory CSF (pleocytosis, 5 [median 25.5 cells, range 7–294]; elevated IgG index/synthesis rate, 4; CSF‐exclusive oligoclonal bands, 4). Six had paraneoplastic causation (lung cancer, 2; other, 4); 3 were postinfectious (1 each of COVID‐19, HSV‐1, and post‐Group A streptococcal infection). Of 9 immunotherapy‐treated patients, 5 improved. Interpretation UNAs are partly accounted for by a repertoire of diverse mostly intracellular synaptic antigens. Their characterization is expedited by protein arrays and PhIPSeq. Further individual studies are needed to assess them as disease biomarkers.

ABSTRACTCavin‐4 was identified as a potential autoantigen for immune‐mediated rippling muscle disease (iRMD). To validate this, we developed and tested various immunoassays, including a cell‐based assay (CBA), cavin‐4 recombinant protein ELISA, and multi‐peptide ELISA. Among 19 iRMD patients, all exhibited muscle rippling, and 13 had percussion‐induced mounding. All immunoassays demonstrated clinical and analytical specificities greater than 95%. The protein ELISA had the highest sensitivity (94.7%) and specificity (99.9%), outperforming CBA (sensitivity 89.5%, specificity 99.6%) and the multi‐peptide ELISA (sensitivity 79.0%, specificity 97.2%). Our results suggest that the cavin‐4 protein ELISA is a promising tool for high‐throughput clinical testing in iRMD.

Abstract We recently reported normalization of CSF cytokine levels following successful treatment of drug-resistant epilepsy (DRE) with recombinant interleukin-1 receptor antagonist (rIL1RA). To further understand the mechanism of this therapeutic outcome, we interrogated the ability of serum and CSF factors that are elevated in drug resistant-seizure disorders to promote inflammatory responses in astrocytes and human brain microvessel endothelial cells (HBMVECs). We report that CCL2, TNFa, IL6, and CXCL8/1 were strongly induced in 1) astrocytes and HBMVECs stimulated with IL1β (blocked by rIL1RA) and 2) astrocytes but not HBMVECs in response to DRE patient serum but not control serum (partially blocked by rIL1RA). This suggested that other serum factors contribute to astrocyte activation in this DRE. HMGB1 and IL18 were also dysregulated in DRE patient serum; however, IL18 failed to stimulate cytokine secretion from astrocytes. In contrast, HMGB1 induced cytokine secretion from astrocytes, which was blocked by the TLR4 inhibitor TAK242. Remarkably, TAK242 also prevented cytokine production by astrocytes in response to serum from some patients with DRE. Finally, IL1β induced the polarized uptake and secretion of HMGB1 across transwell inserts harboring confluent monolayers of HBMVECs suggesting that IL1b signaling may cause endothelial cells to transport serum HMGB1 into the perivascular space—promoting TLR4-dependent cytokine release from astrocytes. This translation of an “outside” inflammatory signal into an “inside” inflammatory response may underlie seizure disorders that are resistant to anti-seizure drugs.