Oral Presentation 23rd Annual Lorne Proteomics Symposium 2018

Detailed glycomics and glycoenzyme transcriptomics of amyotrophic lateral sclerosis blood-derived monocytes (#53)

Hannes Hinneburg 1 , Rebeca Sakuma 1 , Ayad Anwer 1 , Weihua Zhao 2 , Stanley H. Appel 2 , Nicolle Packer 1 , Dominic Rowe 3 , Morten Thaysen-Andersen 1
  1. Macquarie University, NSW, Australia
  2. Department of Neurology, Houston Methodist Neurological Institute, Houston, Texas, USA
  3. Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia

Brain tissue-resident macrophage-like cells, microglia, are innate immune cells of the brain. Monocyte-derived macrophages (MDM) from peripheral blood are known to benefit the resolution of local brain inflammation involving hyper-activated microglia in neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Altered protein glycosylation is known to contribute to or arise from many immune-related diseases, but it still remains unknown if aberrant glycosylation features of monocytes and MDMs are associated with ALS. Herein we explore these important immune aspects of ALS.

We obtained detailed N- and O-glycan profiles of extracted proteins of peripheral pan-CD14+ monocytes and corresponding MDMs from a cohort of ALS patients and healthy individuals using porous graphitised carbon liquid chromatography ion trap tandem mass spectrometry. Glycan isomer characterisation and determination of their relative abundances were determined and statistically compared between ALS and healthy individuals. Gene expression levels of enzymes relevant for N- and O-glycosylation were obtained using RNA sequencing to assess any regulation of the glycosylation machinery of ALS monocytes.

More than 100 glycans were characterised from the investigated monocytes and MDMs. The N-glycan structures were mainly of the diantennary, complex type carrying various glyco-epitopes such as a2,3-/a2,6-linked neuraminic acids and core and Lewis-type fucosylation. Furthermore, high mannosylation was also an abundant monocytic feature. Only minor qualitative and quantitative differences were detected between the glycan profiles of monocytes derived from ALS patients and healthy individuals, which were supported by relatively constant mRNA expression of the biosynthetic N- and O-glycosylation enzymes between these two patient groups.

This is the first study to explore the exact glycosylation signatures in the peripheral immune cells central to ALS. Our findings are part of our aim to advance the understanding of the cellular features and disease mechanisms underpinning ALS and associated neurodegenerative diseases.