Abstract
Myocarditis can be caused by viral infection, drug reaction or general inflammatory condition. To provide understanding on inflammatory myocarditis, we describe clinical, genetic, and immunological properties of a young male patient who suffered from recurrent myocarditis episodes since the age of four years. Electrocardiography, troponin I/T, echocardiography, myocardial magnetic resonance imaging and histological findings were consistent with recurrent myocarditis episodes. Homozygous c.245 A > G p.Tyr82Cys pathogenic variant in Hepatitis A Virus Cellular Receptor 2 (HAVCR2) gene encoding T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) receptor was found. Peripheral blood mononuclear cells were collected when the patient was asymptomatic; CD4+ and CD8+ T lymphoblasts, CD56+ natural killer cells and CD14+ monocytes were negative for surface TIM-3 expression. In vitro, TLR4 mediated interleukin-1β (IL-1β) response was high after LPS/ATP stimulation. Clinical symptoms responded to IL-1 receptor antagonist anakinra. TIM-3 p.Tyr82Cys CD4+ and CD8+ T cell proliferation in vitro was unrestrained. Findings on IL-2, interferon gamma, regulatory T cells, signal transducer and activator of transcription (STAT) 1, 3 and 4 phosphorylation, and PD-1 and LAG-3 checkpoint inhibitor receptor analyses were comparable to controls. We conclude that TIM-3 deficiency due to homozygous HAVCR2 c.245 A > G p.Tyr82Cys pathogenic variant in the patient described here is associated with autoinflammatory symptoms limited to early onset recurrent febrile myocarditis. Excessive IL-1β production and defective regulation of T cell proliferation may contribute to this clinical condition responsive to anakinra treatment.