A Three-Protein Panel to Support the Diagnosis of Sepsis in Children

Significance of Serum Leucine-rich Alpha-2 Glycoprotein as a Diagnostic Marker in Pediatric Inflammatory Bowel Disease

Serum leucine-rich alpha-2 glycoprotein (LRG) has been utilized for adult inflammatory bowel disease (IBD); however, its efficacy in pediatric IBD remains unknown. The aim of this study was to compare the diagnostic accuracy of serum LRG for pediatric IBD with that of current inflammatory markers, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). This retrospective case-control study included pediatric patients, aged <16 years, who underwent colonoscopy and/or esophagogastroduodenoscopy between April 2017 and March 2022. All eligible patients were divided into two groups: patients with IBD, diagnosed with ulcerative colitis and Crohn's disease, and non-IBD controls. The optimal cut-off value of serum LRG for IBD diagnosis was determined from receiver operating characteristic analysis, and diagnostic accuracy of serum LRG was compared to serum ESR and CRP. A total of 53 patients (24 with IBD and 29 non-IBD controls) met the inclusion criteria. The cut-off value of serum LRG for IBD diagnosis was determined to be 19.5 μg/ml. At this cut-off value, serum LRG had a positive predictive value (PPV) of 0.80 and negative predictive value (NPV) of 0.88. In contrast, PPV and NPV were 0.78 and 0.70 for serum ESR and 0.82 and 0.72 for serum CRP, respectively. Serum LRG can be a potential diagnostic marker for pediatric IBD, with higher diagnostic accuracy than that of the conventional serum markers ESR and CRP.

Multilevel omics for the discovery of biomarkers in pediatric sepsis

Severe sepsis causes organ dysfunction and continues to be the leading reason for pediatric death worldwide. Early recognition of sepsis could substantially promote precision treatment and reduce the risk of pediatric death. The host cellular response to infection during sepsis between adults and pediatrics could be significantly different. A growing body of studies focused on finding markers in pediatric sepsis in recent years using multi-omics approaches. This narrative review summarized the progress in studying pediatric sepsis biomarkers from genome, transcript, protein, and metabolite levels according to the omics technique that has been applied for biomarker screening. It is most likely not a single biomarker could work for precision diagnosis of sepsis, but a panel of markers and probably a combination of markers detected at multi-levels. Importantly, we emphasize the importance of group distinction of infectious agents in sepsis patients for biomarker identification, because the host response to infection of bacteria, virus, or fungus could be substantially different and thus the results of biomarker screening. Further studies on the investigation of sepsis biomarkers that were caused by a specific group of infectious agents should be encouraged in the future, which will better improve the clinical execution of personalized medicine for pediatric sepsis.

Proteomic Profiling of Early Secreted Proteins in Response to Lipopolysaccharide-Induced Vascular Endothelial Cell EA.hy926 Injury

Sepsis is a crucial public health problem with a high mortality rate caused by a dysregulated host immune response to infection. Vascular endothelial cell injury is an important hallmark of sepsis, which leads to multiple organ failure and death. Early biomarkers to diagnose sepsis may provide early intervention and reduce risk of death. Damage-associated molecular patterns (DAMPs) are host nuclear or cytoplasmic molecules released from cells following tissue damage. We postulated that DAMPs could potentially be a novel sepsis biomarker. We used an in vitro model to determine suitable protein-DAMPs biomarkers for early sepsis diagnosis. Low and high lipopolysaccharide (LPS) doses were used to stimulate the human umbilical vein endothelial cell line EA.hy926 for 24, 48, and 72 h. Results showed that cell viability was reduced in both dose-dependent and time-dependent manners. Cell injury was corroborated by a significant increase in lactate dehydrogenase (LDH) activity within 24 h in cell-conditioned medium. Secreted protein-DAMPs in the supernatant, collected at different time points within 24 h, were characterized using shotgun proteomics LC-MS/MS analysis. Results showed that there were 2233 proteins. Among these, 181 proteins from the LPS-stimulated EA.hy926 at 1, 12, and 24 h were significantly different from those of the control. Twelve proteins were up-regulated at all three time points. Furthermore, a potential interaction analysis of predominant DAMPs-related proteins using STITCH 5.0 revealed the following associations with pathways: response to stress; bacterium; and LPS (GO:0080134; 0009617; 0032496). Markedly, alpha-2-HS-glycoprotein (AHSG or fetuin-A) and lactotransferrin (LTF) potentially presented since the first hour of LPS stimulation, and were highly up-regulated at 24 h. Taken together, we reported proteomic profiling of vascular endothelial cell-specific DAMPs in response to early an in vitro LPS stimulation, suggesting that these early damage-response protein candidates could be novel early biomarkers associated with sepsis.

The Role of Coagulase-Negative Staphylococci Biofilms on Late-Onset Sepsis: Current Challenges and Emerging Diagnostics and Therapies

Infections are one of the most significant complications of neonates, especially those born preterm, with sepsis as one of the principal causes of mortality. Coagulase-negative staphylococci (CoNS), a group of staphylococcal species that naturally inhabit healthy human skin and mucosa, are the most common cause of late-onset sepsis, especially in preterms. One of the risk factors for the development of CoNS infections is the presence of implanted biomedical devices, which are frequently used for medications and/or nutrient delivery, as they serve as a scaffold for biofilm formation. The major concerns related to CoNS infections have to do with the increasing resistance to multiple antibiotics observed among this bacterial group and biofilm cells’ increased tolerance to antibiotics. As such, the treatment of CoNS biofilm-associated infections with antibiotics is increasingly challenging and considering that antibiotics remain the primary form of treatment, this issue will likely persist in upcoming years. For that reason, the development of innovative and efficient therapeutic measures is of utmost importance. This narrative review assesses the current challenges and emerging diagnostic tools and therapies for the treatment of CoNS biofilm-associated infections, with a special focus on late-onset sepsis.

Mouse Bone Marrow Mesenchymal Stem Cells Inhibit Sepsis-Induced Lung Injury in Mice via Exosomal SAA1

Sepsis is a global disease burden, and approximately 40% of cases develop acute lung injury (ALI). Bone marrow mesenchymal stromal cells (BMSCs) and their exosomes are widely used in treating a variety of diseases including sepsis. As an acute phase protein, serum amyloid A1 (SAA1) regulates inflammation and immunity. However, the role of SAA1 in BMSCs-exosomes in septic lung injury remains to be elucidated. Exosomes derived from serum and BMSCs were isolated by ultracentrifugation. SAA1 was silenced or overexpressed in mouse BMSCs using lentiviral plasmids, containing either SAA1-targeting short interfering RNAs or SAA1 cDNA. Sepsis was induced by cecal ligation and puncture (CLP). LPS was used to induce ALI in mice. Mouse alveolar macrophages were isolated by flow cytometry. Levels of SAA1, endotoxin, TNF-α, and IL-6 were measured using commercial kits. LPS internalization was monitored by immunostaining. RT-qPCR or immunoblots were performed to test gene and protein expressions. Serum exosomes of patients with sepsis-induced lung injury had significantly higher levels of SAA1, endotoxin, TNF-α, and IL-6. Overexpression of SAA1 in BMSCs inhibited CLP- or LPS-induced lung injury and decreased CLP- or LPS-induced endotoxin, TNF-α, and IL-6 levels. Administration of the SAA1 blocking peptide was found to partially inhibit SAA1-induced LPS internalization by mouse alveolar macrophages and reverse the protective effect of SAA1. In conclusion, BMSCs inhibit sepsis-induced lung injury through exosomal SAA1. These results highlight the importance of BMSCs, exosomes, and SAA1, which may provide novel directions for the treatment of septic lung injury.