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Inclusion‐body myositis and primary Sjögren syndrome: mechanisms for shared etiologies
Author(s) -
Limaye Vidya S.,
Cash Kathy,
Smith Caroline,
Koszyca Barbara,
Patel Sandy,
Greenberg Steven A.,
Hissaria Pravin
Publication year - 2020
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.26830
Subject(s) - inclusion body myositis , immunology , myositis , etiology , medicine , cd8 , rituximab , cd20 , immune system , monoclonal antibody , disease , antibody , pathology
Herein we report a case of sporadic inclusion‐body myositis (sIBM) occurring at an unusually young age in a patient with primary Sjögren syndrome, and use the case to explore possible shared mechanisms for disease susceptibility. Possible factors may include the association of both conditions with the 8.1 ancestral haplotype; the presence of anti‐cN1A antibodies, which, although considered specific for sIBM, are also seen in pSS; and the shared association with T‐cell large granular lymphocyte leukemia (T‐LGLL). Further evaluation of this patient did in fact reveal underlying T‐LGLL and mechanisms by which T cells in sIBM may escape immune regulation and contribute to disease phenotype are explored. Despite myofiber infiltration with CD8‐positive T cells in sIBM, and, although sIBM is traditionally considered treatment‐refractory, we report a significant response to the anti‐CD20 monoclonal antibody, rituximab, and discuss possible mechanisms by which this response may be mediated.