Affiliations: Molecular Neurobiology Unit, IBMC-Instituto de
Biologia Molecular e Celular, University of Porto, Porto, Portugal | ICBAS, University of Porto, Porto, Portugal
Note: [] Corresponding author: Maria João Saraiva, Molecular
Neurobiology, IBMC, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal. Tel.:
+351 22 6074900; Fax: +351 22 6099157; E-mail: [email protected]
Abstract: Familial Amyloidotic Polyneuropathy (FAP) is a disorder
characterized by the extracellular deposition of fibrillar Transthyretin (TTR)
amyloid, with a special involvement of the peripheral nerve. Several
extracellular matrix proteins have been found elevated in tissues from FAP
patients, namely metalloproteinase-9 (MMP-9), neutrophil gelatinase associated
lipocalin (NGAL) and biglycan. In this work we assessed the levels of MMP-9,
tissue inhibitor of metalloproteinase 1 (TIMP-1), NGAL, biglycan and
chondroitin sulphate (CSPG) in an FAP {V30M TTR-related} transgenic mouse model
at different stages of TTR deposition and after two different treatment
approaches to remove fibrillar deposits. Immunohistochemistry or RT-PCR
analysis showed that biglycan was already increased in animals presenting TTR
deposited in a non-fibrillar state, whereas MMP-9, TIMP-1, NGAL and CSPG were
elevated only in mice with TTR amyloid deposits. Mice treated with doxycycline,
a TTR fibril disrupter, presented lower levels of MMP-9, TIMP-1 and NGAL,
suggestive of matrix recovery. Mice immunized with TTR Y78F to remove TTR
deposition showed significantly lower levels of all the five tested markers,
suggesting removal of fibrillar and non-fibrillar deposits. Cellular studies
using oligomeric TTR showed induction of MMP-9 when compared to soluble TTR,
large aggregates or fibrils. Furthermore, this induction was neutralized by an
anti-receptor for advanced glycation end products (RAGE) antibody, indicating
RAGE engagement in this process. Further studies in a larger number of tissue
samples will indicate the application of these ECM markers in parallel with
Congo Red staining in tissue characterization of pre-clinical and clinical
stages in FAP and other amyloidoses.
