Oral Presentation 26th Annual Lorne Proteomics Symposium 2021

A novel approach for biomarker discovery: spatial mapping of N-glycans on human knee osteoarthritis cartilage-bone tissue using matrix-assisted laser desorption/ionisation mass spectrometry imaging (#18)

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

Objective:

Knee osteoarthritis (KOA) is the most common form of arthritis, but the biomolecular involvement of its onset and progression is controversial. Several studies have shown that the alterations of N-glycans on proteins contribute to the pathophysiology and progression of various diseases. However, the biomolecular distribution of N-glycans on KOA 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 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). In order to do so, we have developed and applied a novel and cost-effective sample preparation workflow in which commercial conductive ITO slides are pre-coated with gelatin and chromium potassium sulfate dodecahydrate to improve the adherence of tissue sections. 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. 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 (cartilage histological grade 2-2.5) with underlying bone sclerosis, compared to the adjacent region with less damaged cartilage tissue (cartilage histological grade 0-1), associated with non-sclerotic bone.

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. This could also mean that N-glycans are a possible new target for treatment of cartilage degradation in patients with KOA.