The purpose of this study is to identify and visualize the spatial distribution of proteins present in amyloid corneal deposits of TGFBI-CD patients using Mass Spectrometry Imaging (MSI) and compare i Show more
The purpose of this study is to identify and visualize the spatial distribution of proteins present in amyloid corneal deposits of TGFBI-CD patients using Mass Spectrometry Imaging (MSI) and compare it with healthy control cornea. Corneal Dystrophies (CD) constitute a group of genetically inherited protein aggregation disorders that affects different layers of the cornea. With accumulated protein deposition, the cornea becomes opaque with decreased visual acuity. CD affecting the stroma and Bowman's membrane, is associated with mutations in transforming growth factor β-induced (TGFBI) gene. MALDI-Mass Spectrometry Imaging (MSI) is performed on 2 patient corneas and is compared with 1 healthy control cornea using a 7T-MALDI-FTICR. Molecular images obtained are overlaid with congo-red stained sections to visualize the proteins associated with the corneal amyloid aggregates. MALDI-MSI provides a relative abundance and two dimensional spatial protein signature of key proteins (TGFBIp, Apolipoprotein A-I, Apolipoprotein A-IV, Apolipoprotein E, Kaliocin-1, Pyruvate Kinase and Ras related protein Rab-10) in the patient deposits compared to the control. This is the first report of the anatomical localization of key proteins on corneal tissue section from CD patients. This may provide insight in understanding the mechanism of amyloid fibril formation in TGFBI-corneal dystrophy. Show less
TGFBI-associated corneal dystrophies are inherited disorders caused by TGFBI gene variants that promote deposition of mutant protein (TGFBIp) as insoluble aggregates in the cornea. Depending on the ty Show more
TGFBI-associated corneal dystrophies are inherited disorders caused by TGFBI gene variants that promote deposition of mutant protein (TGFBIp) as insoluble aggregates in the cornea. Depending on the type and position of amino acid substitution, the aggregates may be amyloid fibrillar, amorphous globular or both, but the molecular mechanisms that drive these different patterns of aggregation are not fully understood. In the current study, we report the protein composition of amyloid corneal aggregates from lattice corneal dystrophy patients of Asian origin with H626R and R124C mutation and compared it with healthy corneal tissues via LC-MS/MS. We identified several amyloidogenic, nonfibrillar amyloid associated proteins and TGFBIp as the major components of the deposits. Our data indicates that apolipoprotein A-IV, apolipoprotein E, and serine protease HTRA1 were significantly enriched in patient deposits compared to healthy controls. HTRA1 was also found to be 7-fold enriched in the amyloid deposits of patients compared to the controls. Peptides sequences (G Show less