Leopardi V, Chang YM, Pham A, Luo J, Garden OA. A Systematic Review of the Potential Implication of Infectious Agents in Myasthenia Gravis.
Front Neurol 2021;
12:618021. [PMID:
34194378 PMCID:
PMC8236805 DOI:
10.3389/fneur.2021.618021]
[Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 05/04/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Myasthenia gravis (MG) is an autoimmune disorder of unknown etiology in most patients, in which autoantibodies target components of neuromuscular junctions and impair nerve to muscle transmission.
Objective: To provide a synthesis of the evidence examining infectious agents associated with the onset of MG.
Hypothesis: We hypothesized that microbes play a pathogenic role in the initiation of MG. For clinical cases, the onset of clinical signs is used as a proxy for the true onset of autoimmunity.
Methods: We searched PubMed and Web of Science. Papers captured through database searching (n = 827) were assessed, yielding a total of 42 publications meeting the inclusion and exclusion criteria. An additional 6 papers were retrieved from the reference lists of relevant articles. For each pathogen, an integrated metric of evidence (IME) value, from minus 8 to plus 8, was computed based on study design, quality of data, confidence of infectious disease diagnosis, likelihood of a causal link between the pathogen and MG, confidence of MG diagnosis, and the number of infected patients. Negative IME values corresponded to studies providing evidence against a role for microbes as triggers of MG.
Results: One hundred and sixty-nine myasthenic patients infected with 21 different pathogens were documented. Epstein-Barr virus (median = 4.71), human papillomavirus (median = 4.35), and poliovirus (median = 4.29) demonstrated the highest IME values. The total median IME was 2.63 (mean = 2.53; range −3.79–5.25), suggesting a general lack of evidence for a causal link.
Conclusions: There was a notable absence of mechanistic studies designed to answer this question directly. The question of the pathogenic contribution of microbes to MG remains open.
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