Glycoproteoform Profiles of Individual Patients’ Plasma Alpha-1-Antichymotrypsin are Unique and Extensively Remodeled Following a Septic Episode

Abstract

Sepsis and septic shock remain the leading causes of death in intensive care units (ICUs), yet the pathogenesis originating from the inflammatory response during sepsis remains ambiguous. Acute-phase proteins are typically highly glycosylated, and the nature of the glycans have been linked to the incidence and severity of such inflammatory responses. To further build upon these findings we here monitored, the longitudinal changes in the plasma proteome and, in molecular detail, glycoproteoform profiles of alpha-1-antichymotrypsin (AACT) extracted from plasma of ten individual septic patients. For each patient we included four different time-points, including post-operative (before sepsis) and following discharge from the ICU. We isolated AACT from plasma depleted for albumin, IgG and serotransferrin and used high-resolution native mass spectrometry to qualitatively and quantitatively monitor the multifaceted glycan microheterogeneity of desialylated AACT, which allowed us to monitor how changes in the glycoproteoform profiles reflected the patient’s physiological state. Although we observed a general trend in the remodeling of the AACT glycoproteoform profiles, e.g. increased fucosylation and branching/LacNAc elongation, each patient exhibited unique features and responses, providing a resilient proof-of-concept for the importance of personalized longitudinal glycoproteoform profiling. Importantly, we observed that the AACT glycoproteoform changes induced by sepsis did not readily subside after discharge from ICU.

Differential Peripheral Blood Glycoprotein Profiles in Symptomatic and Asymptomatic COVID-19

“…While overall decreases of serum proteins have been reported in cancer in the past [31], a search of more recent literature to confirm this failed to yield additional evidence for this, and also not for inflammatory conditions. In a previous plasma proteomic analysis of ten sepsis patients, expression of APOC3 was statistically significantly downregulated the day after the suspected septic episode began compared with immediately after an elective surgical procedure [12]. While in our analysis the APOC3 peptide, GWVTDGFSSLK, was likewise somewhat decreased in septic patients compared to healthy controls, this difference did not reach statistical significance (fold change=0.956, FDR=0.903).…”

“…In sepsis, similar to COVID-19, pro-inflammatory and anti-inflammatory mediators such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and monocyte chemoattractant protein 1 (MCP-1) [10] are released, followed by a rise in the levels of acute phase proteins such as procalcitonin, calprotectin, proadrenomedullin, pentraxin-3, and C-reactive protein (CRP) [11]. While a number of studies interrogating plasma glycoprotein isoforms in severe systemic inflammatory states have been published in the context of bacterial sepsis, describing among others, changes of alpha-1-antichymotypsin and IgG [12][13][14][15][16][17] glycosylation following a septic episode, distinguishing survivors from patients who died, or differentiating febrile individuals with and without bacteremia, no such studies have so far been published in the context of COVID-19.…”

Transient response of serpinA3 during cellular stress

“…We noticed that the molecular weight of intracellular and secreted serpinA3 c / k under stressful conditions was higher than the core protein (~40 kDa), suggesting that a post‐translational modification may be required for its secretion. Indeed, it has been previously described that serpinA3 is glycosylated 34–36 …”

“…Likewise, it is known that the plasma half‐life of proteins is often prolonged when they are glycosylated compared to insufficiently glycosylated or non‐glycosylated peptides 44 . For these reasons, the detailed study of the glycome in various diseases that describes the complete repertoire of glycoconjugates has been gaining increasing relevance 45 because it has been proposed that glycosylation may be specific and highly dependent on the pathophysiological context that occurs in a particular tissue 36 …”

“…Therefore, the glycosylation patterns of proteins in body fluids could become an important source of information to describe abnormalities in cellular processes. In this regard, it has been described that some proteins are highly glycosylated in the acute phase of sepsis, and it has been suggested that the nature of glycans is related to the incidence and severity of inflammatory responses 36 46 .…”