Amyloid-β and caspase-1 are indicators of sepsis and organ injury

Abstract

BackgroundSepsis is a life-threatening condition that results from a dysregulated host response to infection, leading to organ dysfunction. Despite the prevalence and associated socioeconomic costs, treatment of sepsis remains limited to antibiotics and supportive care, and a majority of intensive care unit (ICU) survivors develop long-term cognitive complications post- discharge. The present study identifies a novel regulatory relationship between amyloid-β (Aβ) and the inflammasome-caspase-1 axis as key innate immune mediators that define sepsis outcomes.MethodsMedical ICU patients and healthy individuals were consented for blood and clinical data collection. Plasma cytokine, caspase-1, and Aβ levels were measured. Data were compared against indices of multi-organ injury and other clinical parameters. Additionally, recombinant proteins were testedin vitroto examine the effect of caspase-1 on a functional hallmark of Aβ, namely aggregation.ResultsPlasma caspase-1 levels displayed the best predictive value in discriminating ICU patients with sepsis from non-infected ICU patients (AUROC=0.7080). Plasma caspase-1 and the 40 amino acid Aβ isoform (Aβx−40) showed a significant positive correlation and Aβx-40associated with organ injury. Additionally, Aβ plasma levels continued to rise from time of ICU admission to 7-days post-admission.In silico, Aβ harbors a predicted caspase-1 cleavage site, andin vitrostudies demonstrated that caspase-1 cleaved Aβ to inhibit its auto-aggregation, suggesting a novel regulatory relationship.ConclusionsAβx-40and caspase-1 are potentially useful early indicators of sepsis and its attendant organ injury. Additionally, Aβx-40has emerged as a potential culprit in the ensuing development of post-ICU-syndrome.