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Benvenga S, Antonelli A, Fallahi P, Bonanno C, Rodolico C, Guarneri F. Amino acid sequence homology between thyroid autoantigens and central nervous system proteins: Implications for the steroid-responsive encephalopathy associated with autoimmune thyroiditis. J Clin Transl Endocrinol 2021; 26:100274. [PMID: 34849350 PMCID: PMC8609095 DOI: 10.1016/j.jcte.2021.100274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 10/15/2021] [Accepted: 10/27/2021] [Indexed: 11/13/2022] Open
Abstract
Alpha-enolase, aldehyde reductase-I and dimethylargininase-I are SREAT autoantigens. Molecular mimicry between thyroid and CNS autoantigens is hypothesized in SREAT. Homology with TSH-R, Tg and TPO exists for 6, 27 and 47 of 46,809 CNS-proteins. The above homologies are often in epitope-containing parts of thyroid autoantigens. Most of the above proteins are expressed in CNS regions which are altered in SREAT.
A few patients with Hashimoto’s thyroiditis or Graves’ disease develop a multiform syndrome of the central nervous system (CNS) termed Hashimoto’s encephalopathy or steroid-responsive encephalopathy associated with autoimmune thyroid disease (HE/SREAT). They have high levels of thyroid autoantibodies (TgAb, TPOAb and/or TSH-R-Ab) in blood and cerebrospinal fluid. Autoantibodies against alpha-enolase, aldehyde reductase-I (AKRIA) and/or dimethylargininase-I (DDAHI), proteins expressed in the CNS among other tissues, were detected in the blood and, when searched, in the cerebrospinal fluid of HE/SREAT patients. Recently, we reported that alpha-enolase, AKRIA and DDAHI share local sequence homology with each of the three autoantigens (TgAb, TPOAb, TSH-R-Ab), often in epitope-containing segments of the thyroid autoantigens. We hypothesized that there might be additional CNS-expressed proteins homologous to thyroid autoantigens, possibly overlapping known epitopes of the thyroid autoantigens. We used bioinformatic methods to address this hypothesis. Six, 27 and 47 of 46,809 CNS-expressed proteins share homology with TSH-R, Tg and TPO, respectively. The homologous regions often contain epitopes, and some match regions of thyroid autoantigens which have homology with alpha-enolase, AKRIA and/or DDAHI. Several of the aforementioned proteins are present in CNS areas that show abnormalities at neuroimaging in HE/SREAT patients. Furthermore, autoantibodies against some of the said six, 27 and 47 proteins were reported to be associated with a number of autoimmune diseases. Not only we validated our hypothesis, but we think that such a variety of potential CNS targets for thyroid Ab against epitopes contained in regions that have local homology with CNS proteins may explain the polymorphic phenotypes of HE/SREAT. Only when elevated amounts of these Ab are synthesized and trespass the blood-brain barrier, HE/SREAT appears. This might explain why HE/SREAT is so relatively rare.
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Yu Z, Zhang M, Jing H, Chen P, Cao R, Pan J, Luo B, Yu Y, Quarles BM, Xiong W, Rivner MH, Mei L. Characterization of LRP4/Agrin Antibodies From a Patient With Myasthenia Gravis. Neurology 2021; 97:e975-e987. [PMID: 34233932 PMCID: PMC8448554 DOI: 10.1212/wnl.0000000000012463] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 06/22/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVE To determine whether human anti-LRP4/agrin antibodies are pathogenic in mice and to investigate underpinning pathogenic mechanisms. METHODS Immunoglobulin (Ig) was purified from a patient with myasthenia gravis (MG) with anti-LRP4/agrin antibodies and transferred to mice. Mice were characterized for body weight, muscle strength, twitch and tetanic force, neuromuscular junction (NMJ) functions including compound muscle action potential (CMAP) and endplate potentials, and NMJ structure. Effects of the antibodies on agrin-elicited muscle-specific tyrosine kinase (MuSK) activation and AChR clustering were studied and the epitopes of these antibodies were identified. RESULTS Patient Ig-injected mice had MG symptoms, including weight loss and muscle weakness. Decreased CMAPs, reduced twitch and tetanus force, compromised neuromuscular transmission, and NMJ fragmentation and distortion were detected in patient Ig-injected mice. Patient Ig inhibited agrin-elicited MuSK activation and AChR clustering. The patient Ig recognized the β3 domain of LRP4 and the C-terminus of agrin and reduced agrin-enhanced LRP4-MuSK interaction. DISCUSSION Anti-LRP4/agrin antibodies in the patient with MG is pathogenic. It impairs the NMJ by interrupting agrin-dependent LRP4-MuSK interaction.
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Affiliation(s)
- Zheng Yu
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Meiying Zhang
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Hongyang Jing
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Peng Chen
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Rangjuan Cao
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Jinxiu Pan
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Bin Luo
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Yue Yu
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Brandy M Quarles
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Wencheng Xiong
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Michael H Rivner
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH.
| | - Lin Mei
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH.
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