Discussion
We encountered a case of TAFRO syndrome that developed immediately following the first COVID-19 mRNA vaccination. To the best of our knowledge, this is the first reported case of TAFRO syndrome following a COVID-19 mRNA vaccination. Various side effects of the COVID-19 vaccination have been reported worldwide. Braun et al . reported a case of cerebral venous thrombosis and thrombotic thrombocytopenia syndrome [2]. Lim et al . reported myocarditis after mRNA COVID-19 vaccination [3]. Cases of kidney injury, such as IgA nephropathy [4], minimal change disease [5-7], and IgG4-related disease [8], following mRNA vaccination have accumulated in current research.
Ubara et al . reported the renal histology of TAFRO syndrome as glomerular endotheliopathy that is representative of endothelial cell swelling, mesangiolysis, mesangial loosening (loss of mesangial matrix staining), and GBM double contour and thickening. Electron microscopy shows loss of mesangial architecture and endothelial space as well as loss of endothelial cell fenestrations [6]. In the present case, these findings, except for endothelial cell fenestrations, were detected, confirming the diagnosis of TAFRO syndrome.
Previous reports have suggested that vaccination may trigger an autoimmune response due to antigenic mimicry, as well as activation of quiescent auto-reactive T and B cells [10]. These reports suggest that the COVID-19 mRNA vaccine stimulates the immune system and causes autoimmune reactions.
TAFRO syndrome is a systemic inflammatory disorder and a subtype of HHV-8 negative MCD [11]. Although the etiology has not been revealed, it has been demonstrated that hypercytokinemia related to IL-6 and stimulation of VEGF contributes to the pathophysiological mechanisms of TAFRO syndrome [12,13]. It is suggested that the abnormal autoimmune response induced by COVID-19 mRNA vaccination caused the overproduction of cytokines, such as IL-6 and VEGF, in the present case.
The pathophysiology of TAFRO syndrome has not yet been clarified; however, it often presents with progressive clinical symptoms and can be fatal. We should be considered as one of the rare side reactions of the COVID-19 vaccine and should be diagnosed earlier. Further studies are needed to reveal the mechanisms of the immune response in developing severe side effects following COVID-19 mRNA vaccination.
Conclusion Universal vaccination against COVID-19 is important for lowering the risk of spreading COVID-19 infection. Several complications, such as renal, hematological, and heart diseases, have been reported; however, its pathogenesis is unclear. The possibility of various complications after COVID-19 vaccination, including TAFRO syndrome, should be considered.