The increasing prevalence of antibacterial resistance globally underscores the urgent need to the update of antibiotics. Here, we describe a strategy for inducing the self-assembly of a host-defense antimicrobial peptide (AMP) into nanoparticle antibiotics (termed nanobiotics) with significantly improved pharmacological properties. Our strategy involves the myristoylation of human alpha-defensin 5 (HD5) as a therapeutic target and subsequent self-assembly in aqueous media in the absence of exogenous excipients. Compared with its parent HD5, the C-terminally myristoylated HD5 (HD5-myr)-assembled nanobiotic exhibited significantly enhanced broad-spectrum bactericidal activity in vitro. Mechanistically, it selectively killed Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) through disruption of the cell wall and/or membrane structure. The in vivo results further demonstrated that the HD5-myr nanobiotic protected against skin infection by MRSA and rescued mice from E. coli-induced sepsis by lowering the systemic bacterial burden and alleviating organ damage. The self-assembled HD5-myr nanobiotic also showed negligible hemolytic activity and substantially low toxicity in animals. Our findings validate this design rationale as a simple yet versatile strategy for generating AMP-derived nanobiotics with excellent in vivo tolerability. This advancement will likely have a broad impact on antibiotic discovery and development efforts aimed at combating antibacterial resistance.

TREM-2 plays an important role in the host defense response to sepsis by enhancing bacterial clearance.

The level of circulating nucleosomes in the serum has a predictive value for sepsis and organ dysfunction and may serve as a candidate biomarker for the diagnosis/prognosis of sepsis. Further studies are warranted to confirm the present findings.

BackgroundThe role of increased body mass index (BMI) in sepsis is controversial. We aimed to evaluate the associations between overweight (25 kg/m2 < BMI ≤ 29.9 kg/m2), obese (30 kg/m2 < BMI ≤ 39.9 kg/m2) and morbidly obese (BMI > 40 kg/m2) BMIs and outcomes in septic patients.MethodsWe searched the PubMed, Embase, Web of Science, Cochrane Library and ClinicalTrials.gov databases for studies published by December 1, 2016. Electronic database searches yielded 3713 articles, eight of which were included in this meta-analysis. Data were independently extracted by two reviewers, and a third reviewer participated in making decisions as needed. We used Review Manager to conduct the analysis, and the outcomes were reported with odds ratios (ORs) or mean differences (MDs). The primary outcome was mortality, and the secondary outcome was length of stay (LOS) in the intensive care unit (ICU) or the hospital.ResultsData from eight studies involving a total of 9696 patients were pooled in our final analysis. Compared with patients with normal BMI (18.5 kg/m2 < BMI ≤ 24.9 kg/m2), patients with BMI ≥ 25 kg/m2 exhibited decreased mortality (OR 0.81; 95% confidence interval (CI), 0.74–0.89, P < 0.0001). In subgroup analysis, compared with normal-weight patients, overweight patients had lower mortality (OR 0.87; 95% CI 0.77–0.97, P = 0.02), whereas obese (OR 0.89, 95% CI 0.72–1.10, P = 0.29) and morbidly obese (OR 0.64, 95% CI 0.38–1.08, P = 0.09) patients did not exhibit significantly reduced mortality.ConclusionsIn sepsis cases, overweight, but not obesity or morbid obesity, was associated with lower mortality. Further prospective studies are needed to clarify this relationship.Electronic supplementary materialThe online version of this article (doi:10.1186/s12871-017-0405-4) contains supplementary material, which is available to authorized users.

IntroductionGelsolin is an actin-binding plasma protein that is part of an 'actin-scavenging' system. Studies suggest that plasma gelsolin may play a crucial role in the pathophysiology of sepsis. Little is known about the course of plasma gelsolin levels over time in patients with severe sepsis. The aim of the study was to investigate plasma gelsolin levels in severe septic patients and to determine whether these levels predict the severity or clinical outcome of severe sepsis.MethodsNinety-one patients who were diagnosed with severe sepsis at admission to a surgical intensive care unit were enrolled, and admission plasma gelsolin levels were recorded. Plasma gelsolin levels were recorded daily in 23 of these patients. Daily plasma gelsolin levels were recorded in an additional 15 nonseptic critically ill patients. Fifteen volunteers served as healthy control individuals. Plasma gelsolin levels were measured using an enzyme-linked immunosorbent assay. Concentrations of IL-6, IL-10 and tumour necrosis factor (TNF)-α were also measured on intensive care unit admission.ResultsThe admission gelsolin levels were significantly decreased in severe sepsis (20.6 ± 11.7 mg/l) compared with nonseptic critically ill patients (52.3 ± 20.3 mg/l; P < 0.001) and healthy control individuals (126.8 ± 32.0 mg/l; P < 0.001). Severe septic patients had increased IL-6 levels compared with nonseptic critically ill patients (20.0 ± 10.7 pg/ml versus 11.4 ± 13.9 pg/ml; P = 0.048), whereas no significant difference in IL-10 or TNF-α levels was observed (IL-10: 97.9 ± 181.5 pg/ml versus 47.4 ± 91.5 pg/ml, respectively [P = 0.425]; TNF-α: 14.2 ± 13.9 pg/ml versus 6.9 ± 5.3 pg/ml, respectively; P = 0.132). Survivors of severe sepsis exhibited substantial recovery of their depressed plasma gelsolin levels, whereas gelsolin levels in nonsurvivors remained at or below their depleted admission levels.ConclusionPlasma gelsolin may be a valuable marker for severe sepsis. Recovery of depleted plasma gelsolin levels correlated with clinical improvement. The prognostic role of plasma gelsolin in critical illness requires further investigation in a large cohort.