Development and validation of a novel molecular biomarker diagnostic test for the early detection of sepsis

Abstract

IntroductionSepsis is a complex immunological response to infection characterized by early hyper-inflammation followed by severe and protracted immunosuppression, suggesting that a multi-marker approach has the greatest clinical utility for early detection, within a clinical environment focused on Systemic Inflammatory Response Syndrome (SIRS) differentiation. Pre-clinical research using an equine sepsis model identified a panel of gene expression biomarkers that define the early aberrant immune activation. Thus, the primary objective was to apply these gene expression biomarkers to distinguish patients with sepsis from those who had undergone major open surgery and had clinical outcomes consistent with systemic inflammation due to physical trauma and wound healing.MethodsThis was a multi-centre, prospective clinical trial conducted across four tertiary critical care settings in Australia. Sepsis patients were recruited if they met the 1992 Consensus Statement criteria and had clinical evidence of systemic infection based on microbiology diagnoses (n = 27). Participants in the post-surgical (PS) group were recruited pre-operatively and blood samples collected within 24 hours following surgery (n = 38). Healthy controls (HC) included hospital staff with no known concurrent illnesses (n = 20). Each participant had minimally 5 ml of PAXgene blood collected for leucocyte RNA isolation and gene expression analyses. Affymetrix array and multiplex tandem (MT)-PCR studies were conducted to evaluate transcriptional profiles in circulating white blood cells applying a set of 42 molecular markers that had been identified a priori. A LogitBoost algorithm was used to create a machine learning diagnostic rule to predict sepsis outcomes.ResultsBased on preliminary microarray analyses comparing HC and sepsis groups, a panel of 42-gene expression markers were identified that represented key innate and adaptive immune function, cell cycling, WBC differentiation, extracellular remodelling and immune modulation pathways. Comparisons against GEO data confirmed the definitive separation of the sepsis cohort. Quantitative PCR results suggest the capacity for this test to differentiate severe systemic inflammation from HC is 92%. The area under the curve (AUC) receiver operator characteristics (ROC) curve findings demonstrated sepsis prediction within a mixed inflammatory population, was between 86 and 92%.ConclusionsThis novel molecular biomarker test has a clinically relevant sensitivity and specificity profile, and has the capacity for early detection of sepsis via the monitoring of critical care patients.

Acute Respiratory Distress Syndrome Neutrophils Have a Distinct Phenotype and Are Resistant to Phosphoinositide 3-Kinase Inhibition

“…These were also within the top five pathways identified in the previous burns and sepsis cohorts using mixed leukocytes (38,39). This suggests that, despite their heterogeneity, there is a strong commonality in a range of acute severe inflammatory disorders.…”

“…Using the NextBio analysis platform (which recognized 1,282 of the 1,319 differentially expressed genes), we compared these changes with publicly available datasets, finding a striking similarity to data in leukocytes from patients with severe burns or sepsis (38,39); not only was there a strong overlap in gene changes, but also the direction of change correlated almost completely ( Figure 5B). Ingenuity Pathway Analysis revealed a significant increase in pathways associated with the immune response, cytoskeletal remodeling, and mucin production, as well as significant decreases in cell death and/or apoptosis pathways, consistent with the neutrophil phenotype observed ( Figure E3).…”

Targeted metabolomics for discrimination of systemic inflammatory disorders in critically ill patients

“…Most of those studies addressed the transcriptome or proteome for biomarker identifi cation (7)(8)(9). Even though 178 different biomarkers for sepsis have been proposed ( 7 ), most of them have only prognostic and not discriminative value.…”

Antibiotic prescription for respiratory tract infections in ventilated patients: where are we heading?

“…Biomarkers, required for pre-emptive therapy, are not often good enough to help us in this dilemma [3], and whilst PCT may be currently the forerunner in this respect [4,5], there is an ongoing search for one with better sensitivity and specificity [5,6]. It may be that genomics will provide a better answer for us [6,7], although there still needs to be more research on any gene expression before such a marker (or markers) have widespread clinical applicability.…”

“…It may be that genomics will provide a better answer for us [6,7], although there still needs to be more research on any gene expression before such a marker (or markers) have widespread clinical applicability.…”