ABSTRACT
Familial amyloidotic polyneuropathy (FAP) is a systemic amyloidosis mainly caused by amyloidogenic transthyretin (ATTR). This incurable disease causes death â¼10 years after onset. Although it has been widely accepted that conformational change of the monomeric form of transthyretin (TTR) is very important for amyloid formation and deposition in the organs, no effective therapy targeting this step is available. In this study, we generated a mouse monoclonal antibody, T24, that recognized the cryptic epitope of conformationally changed TTR. T24 inhibited TTR accumulation in FAP model rats, which expressed human ATTR V30M in various tissues and exhibited non-fibrillar deposits of ATTR in the gastrointestinal tracts. Additionally, humanized T24 (RT24) inhibited TTR fibrillation and promoted macrophage phagocytosis of aggregated TTR. This antibody did not recognize normal serum TTR functioning properly in the blood. These results demonstrate that RT24 would be an effective novel therapeutic antibody for FAP.
Subject(s)
Amyloid Neuropathies, Familial/drug therapy , Amyloid Neuropathies, Familial/immunology , Antibodies, Monoclonal, Murine-Derived/immunology , Macrophages/immunology , Phagocytosis/drug effects , Prealbumin/immunology , Amyloid Neuropathies, Familial/pathology , Animals , Antibodies, Monoclonal, Murine-Derived/therapeutic use , Female , Humans , Macrophages/pathology , Male , Mice , RatsABSTRACT
Although it is believed that altered conformations exposing cryptic regions are intermediary and critical steps in the mechanism of transthyretin (TTR) amyloid formation, no effective therapy targeting this step is available. In this study, to establish the antibody therapy for familial amyloidotic polyneuropathy (FAP), we generated a monoclonal anti-TTR antibody, which specifically reacts with surface epitopes of TTR (MAb ATTR) and evaluated its binding affinity and specificity for TTR amyloid fibrils. MAb ATTR showed specific binding affinity for TTR amyloid fibrils, but not for native form of TTR. Moreover, MAb ATTR indeed showed the high consistency with Congo red positive areas in tissue specimens from FAP ATTR V30M patients, indicating that MAb ATTR showed binding affinity and specificity for TTR amyloid fibrils in vitro and in vivo. MAb ATTR may have a potential to suppress TTR amyloid deposition and become a candidate for the antibody therapy for FAP.