PMC7358532_01
Clinical timeline, IQ, and EEG. (A) Clinical timeline representing the evolution of serological values of creatinine kinase, thyroid-stimulating hormone (TSH), TPO autoantibodies and thyroxine levels. Treatment intervention is also illustrated as well as qualitative disease progression. (B) IQ progression by Wechsler intelligence scale for children. Total IQ (TIQ), verbal IQ (VIQ), and performance IQ (PIQ) at the age of 6, 8, and 13. The average score for the test is 100, and any score between 90 and 109 is considered to be in the average intelligence range. (C) EEG showing generalized spike and wave discharge with right frontal dominance during photic stimulation with 50 Hz.
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F1
A scheme of the clinical events of this case report is shown in Figure 1A. A neuropsychological test showed no remarkable differences beside a subtle decline in his performance intelligence quotient (IQ) (Figure 1B). However, repeated EEG tests, including a 24-h registration, only revealed sporadic bilateral frontal and frontotemporal activity with some epileptiform features, without clinical correlation (Figure 1C).
Identification and quantification of a novel neuropil-like hippocampal pattern in rat brain sections. (A-F) Rat brain immunohistochemistry IgG reactivity of serum. (A-D) Brain immunoreactivity of sera of the Hashimoto's encephalopathy patient case at different time points: (A) At first presentation, (B) 1 month after first presentation, (C) 1 year after first presentation, and (D) after IVIG infusion. (E) brain immunoreactivity of serum from a patient with epilepsy and TPO autoantibodies. (F) brain immunoreactivity of serum from a non-disease control. The arrows in panels (C,F) point at areas shown at higher magnification in panel (C1,F1), respectively. Note the predominance of a neuropil-like pattern in panel (C1). (G) Relative optical density quantification in different areas of the hippocampus, outlined in yellow. SO, stratum oriens; SR, stratum radiatum; SML, stratum lacunosum; ML, molecular layer of dentate gyrus; GL, granule cell layer. Scale bars are 100 and 20 mum.
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Pyramidal neurons and GABA-ergic interneurons in the hippocampus were labeled and the hippocampal neuropil-like pattern was present using sera corresponding to different disease time points (Figures 2A-D). TPO-epilepsy control serum, and a non-disease control, was low (Figures 2E,F). To quantify the intensity of the rat brain stainings, we selected different areas of the hippocampus including the stratum oriens, the stratum radiatum, the stratum lacunosum-moleculare, the molecular layer of dentate gyrus, and the granule cell layer. The optical density of the patient's serum immunoreactivity at all investigated time points was consistently high in these hippocampus regions, specially in the molecular layer of the dentage gyrus, the stratum radiatum, and the stratum oriens (Figure 2G).
Patient's autoantibodies recognize an unidentified neuronal surface antigen in cultured primary hippocampal neurons. Immunofluorescent photomicrographs of cultured, live primary hippocampal neurons. Human IgGs are stained in green fluorescence, microtubules (MAP2) in red fluorescence, and cell nuclei (Hoechst DNA stain) in blue fluorescence. Serum immunostaining of (A) a patient with DPPX antibodies, as a control, (B) the Hashimoto's encephalopathy patient case, and (C) a non-disease control. (A1,B1,C1) show the merge of nuclear and dendrite staining, (A2,B2,C2) show the merge of nuclear and human IgG staining, (A3,B3,C3) show the merge of all three fluorescent stainings. (A4,B4,C4) show the immunofluorescence staining of a dendrite at higher magnification. Scale bars are 50 mum.
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Autoantibody reactivity to a surface antigen was confirmed using live rat primary hippocampal neurons (Figure 3).
TPO autoantibodies are not responsible for the neuronal reactivity and TPO immuno-adsorption shows co-existence of autoantibodies. Graph on the left panel: TPO antibody levels (IU/mL) at six consecutive steps of immune-adsorption using wells coated with recombinant human TPO protein. TPO antibody was depleted from the sera of the following patients: a patient with TPO antibody-positive thyroiditis (purple squares), the Hashimoto's encephalopathy patient (green closed circles), a patient with autoimmune encephalitis and dipeptidyl-peptidase-like protein 6 (DPPX) antibodies (magenta inverted triangles), and a non- disease human serum control (NHS) (blue triangles). A positive (open diamond) and a negative (open circle) calibrator control were included without absorption. Right panel: Rat brain immunohistochemistry using non-immuno-adsorbed sera (A1-D1) and immune-adsorbed sera (A2-D2) from panel (A) a patient with DPPX antibodies, (B) the Hashimoto's encephalopathy patient, (C) a patient with TPO positive antibody thyroiditis, and (D) a non-disease control. Scale bar is 100 mum.
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However, the TPO antibody depleted serum retained the same brain IgG immunoreactivity pattern (Figure 4).