Abstract
Purpose :
The purpose of the study was to identify and visualize the spatial distribution of proteins present in amyloid corneal deposits of TGFBI-corneal dystrophic patients using Mass Spectrometry Imaging (MSI). Corneal Dystrophies (CDs) are genetically inherited, bilateral disorders that can affect corneal clarity with deposition of aggregated mutant protein. Stromal and Bowman’s membrane CDs are most commonly associated with mutations in the TGFBI gene.
Methods :
MALDI Mass Spectrometry Imaging (MSI) of three human corneas (2 patient samples and 1 healthy control) was performed at high spatial resolution (20µm) using a 7T-MALDI-FTICR (SolariX, Bruker Daltonics, Bremen, Germany) with a Smartbeam II laser in the minimum mode with a repetition rate of 2,000 Hz. Full Scan positive mode within 300-2000 Da mass range was selected for imaging with online calibration using matrix peaks (mass accuracy < 1ppm). The mass spectrum obtained for each position of the images corresponded to the averaged mass spectra of 300 consecutive laser shots on the same location. FTMS Control 2.0 and FlexImaging 4.1 software packages (Bruker Daltonics, Bremen, Germany) were used to set and control imaging and mass spectrometer parameters. Standard t-test (SCiLS) and Welch t-tests (Multimaging) between different regions were carried out using imaging data sets. Molecular images were overlaid with Congo red images and Regions of Interest (ROI) were selected.
Results :
MALDI-MSI identified the presence of the proteins (TGFBIp, Apolipoprotein A-I, Apolipoprotein A-IV, Apolipoprotein E, Kaliocin-1, Pyruvate Kinase PKM, Ras-related protein Rab-10) in the amyloid corneal deposits.
Conclusions :
The spatial molecular abundance and distribution of key proteins obtained from the patient cornea may provide insight in understanding the mechanism of amyloid fibril formation in TGFBI-corneal dystrophy.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.