E-Poster Presentation 30th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2020

Spatial mapping of N-glycans on human osteoarthritis cartilage-bone tissue using mass spectrometry imaging (#68)

Yea Rin Olivia Lee 1 2 3 , Matthew Briggs 2 , Julia Kuliwaba 3 , Peter Hoffmann 2 , Dzenita Muratovic 3 , Paul Anderson 1
  1. Clinical and Health Sciences, Health and Biomedical Innovation, University of South Australia, Adelaide, SA, Australia
  2. Future Industries Institute, University of South Australia, Mawson Lakes, South Australia, Australia
  3. Discipline of Orthopaedics and Trauma, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia

Objective:

The alterations of N-glycans on proteins contribute to the pathophysiology and progression of various diseases. However, the biomolecular distribution of N-glycans on osteoarthritis cartilage-bone tissue is poorly understood. Thus, the aim of this study was to spatially compare N-glycans from formalin-fixed paraffin-embedded (FFPE) cartilage-bone tissue of knee osteoarthritis (KOA) patients and cadaveric controls (CTL).

Methods:                      

Human FFPE cartilage-bone tissue from end-stage KOA patients (2-Female; aged 58 and 79 years) and CTL individuals (2-Female; 44 and 54 years) was analysed by matrix‐assisted laser desorption/ionisation mass spectrometry imaging (MALDI‐MSI). Based on the theoretical masses, N-glycan peaks were manually selected, and ion intensity maps were generated using FlexImaging and SCiLS Lab software. Putative N-glycan structures were annotated using the following tools: GlycoMod, which calculates the theoretical monosaccharide composition, and Glycoworkbench to create individual N-glycan structures.

Results:

MALDI-MSI revealed differential N-glycan profiles between KOA patients and CTL individuals within the cartilage region only. Overall, 13 N-glycans were identified in KOA cartilage compared to 9 N-glycans in CTL cartilage, with approximately a 3-fold increase in the signal intensity (Figure 1-A). Interestingly, ion intensity maps of KOA cartilage-specific hybrid/complex-type N-glycans, m/z 1501.7 ±0.5 Da, m/z 1647.2 ±0.5 Da, and m/z 1663.4 ±0.5 Da, showed higher intensity localisation to the superficial fibrillated area of degraded cartilage (OARSI grade 2-2.5) with underlying bone sclerosis, compared to the adjacent region with less damaged cartilage tissue (OARSI grade 0-1), associated with non-sclerotic bone (Figure 1-B).

Conclusion:

Our preliminary results demonstrate the novel application of MALDI-MSI to identify and localise KOA cartilage‐specific N-glycans. The alterations of these hybrid/complex-type N-glycans could evolve into a potential cartilage degradation marker and may play an important role in the development of underlying bone sclerosis. Future work will identify which specific proteins the N-glycans are attached to using liquid chromatography/tandem mass spectrometry (LC-MS/MS). 

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