Mass spectrometric detection of neutrophil elastase cleaved corticosteroid binding globulin and its association with Asn347 site glycosylation, in septic shock patients

Jessica H Lee; Zeynep Sumer-Bayraktar; Parul Mittal; Leigh Donnellan; Clifford Young; R Louise Rushworth; John G Lewis; Marni Nenke; Wayne Rankin; Manuela Kingler-Hoffmann; Peter Hoffmann; Morten Thaysen-Andersen; David J Torpy; Emily J Meyer

doi:10.1016/j.cca.2024.120108

Mass spectrometric detection of neutrophil elastase cleaved corticosteroid binding globulin and its association with Asn347 site glycosylation, in septic shock patients

Clin Chim Acta. 2024 Dec 20:567:120108. doi: 10.1016/j.cca.2024.120108. Online ahead of print.

Affiliations

¹ Department of Medicine, University of Adelaide, Australia; Endocrine and Metabolic Unit, Royal Adelaide Hospital, Australia. Electronic address: Jessica.Lee@adelaide.edu.au.
² School of Natural Sciences, Macquarie University, Australia.
³ Clinical and Health Sciences Unit, University of South Australia, Australia.
⁴ School of Medicine, Sydney, The University of Notre Dame, Australia.
⁵ Canterbury Health Laboratories and Department of Pathology, University of Otago, Christchurch.
⁶ Department of Medicine, University of Adelaide, Australia; Endocrine and Metabolic Unit, Royal Adelaide Hospital, Australia; Endocrine and Diabetes Services, The Queen Elizabeth Hospital, Australia.
⁷ Department of Medicine, University of Adelaide, Australia; Endocrine and Metabolic Unit, Royal Adelaide Hospital, Australia.
⁸ School of Natural Sciences, Macquarie University, Australia; Institute for Glyco-core Research, Nagoya University, Japan.

PMID: 39710247
DOI: 10.1016/j.cca.2024.120108

Abstract

Background: Corticosteroid-binding globulin (CBG) modulates tissue cortisol availability via modification of cortisol:CBG binding affinity in response to multiple factors, including neutrophil elastase (NE) cleavage of the reactive centre loop (RCL), converting high affinity CBG (haCBG) to low affinity CBG (laCBG). In vitro, glycosylation of the RCL at Asn347 affects NE cleavage susceptibility. To date, no direct measurement of laCBG, which would verify NE cleavage, has been reported.

Objective: To measure serum laCBG in septic shock patients by mass spectrometry to confirm NE cleavage in vivo, with Asn347 site glycosylation profiling to determine its impact on NE cleavage, and determine effect of %laCBG on septic shock clinical outcome.

Methods: Serum from septic shock patients from a tertiary hospital intensive care unit was analysed by mass spectrometry for CBG affinity forms and Asn347 glycosylation profile, following CBG immunoprecipitation. Data was correlated with septic shock clinical outcome.

Results: N-terminal peptide of NE cleaved RCL (AVLQLNEEGVDTAGSTGV) was consistently detected in patient serum, although at low concentrations. Mean %laCBG/total CBG was 0.23 % in septic shock (range = 0.07-0.74 %, SD = 0.12 %); in comparison healthy controls mean %laCBG was 0.04 % (range 0.02-0.08 %, SD = 0.03 %). There was a negative correlation between %laCBG and serum concentrations of CBG with triantennary Asn347 glycans; TS3 (r = -0.190, p = 0.040) and TS3F (r = -0.252, p = 0.006).

Conclusions: NE cleaved CBG (laCBG) is present in septic shock patient serum, and %laCBG correlates with Asn347 glycosylation occupancy and composition. However, serum %laCBG did not correlate with septic shock clinical outcome.

Keywords: CBG; Corticosteroid binding globulin; Cortisol; N-glycosylation; Neutrophil elastase; Septic shock; low affinity CBG.