Background: Recently, sequential liver transplantation has been performed with an explanted liver from a patient with familial amyloidotic polyneuropathy (FAP) because of the shortage of donors. However, metabolism of amyloidogenic transthyretin (ATTR), the pathogenic protein of FAP, has not been well studied in patients who have undergone sequential liver transplantation. The purpose of this study was to examine the changes in serum ATTR levels and to investigate the presence of an autoantibody in patients who underwent sequential liver transplantation with an explanted organ from a patient with heterozygotic FAP (FAP ATTR Val30Met).
Methods: This was a case study performed at the Kumamoto University School of Medicine, Kumamoto, Japan, and Kyoto University School of Medicine, Kyoto, Japan. Intervention occurred by sequential liver transplantation with an explanted FAP patient's liver. Levels of normal TTR and ATTR in the two patients who received the transplanted liver were analyzed by means of an enzyme-linked immunosorbent assay (ELISA) and a matrix-assisted laser desorption/time-of-flight mass spectrometry. In addition, the presence of an autoantibody against ATTR Val30Met was evaluated via ELISA using purified ATTR Val30Met from homozygotic FAP patients' sera.
Results: After the operation, the variant TTR levels were unexpectedly lower than levels of normal TTR in serum samples from patients with a transplanted liver from the FAP patient. An autoantibody against the variant TTR was detected on day 3 after the operation in the serum of those patients and continued to be present for at least 2 months after the operation.
Conclusions: An autoantibody against the variant TTR may reduce the serum levels of variant TTR. Although the antibody may play a beneficial role in reducing the pathogenic protein, the long-term effect of the antibody must be investigated further.