Modeling Sepsis-Associated ARDS Using a Lung Endothelial Microphysiological System.

Acute respiratory distress syndrome due to non-pulmonary causes exhibits prominent endothelial activation which is challenging to assess in critically ill patients. Preclinical in vivo models of sepsis and ARDS have failed to yield useful therapies in humans, perhaps due to interspecies differences in inflammatory responses. Use of microphysiological systems (MPS) offer improved fidelity to human biological responses and better predict pharmacological responses than traditional culture. We adapted a lung endothelial MPS based on the LumeNEXT platform to evaluate the effect of plasma from critically ill sepsis patients on endothelial permeability, adhesion molecule expression and inflammatory cytokine production. Lumens incubated with sepsis plasma exhibited areas of contraction, loss of cellular coverage, and luminal defects. Sepsis plasma-incubated lumens had significantly increased permeability compared to lumens incubated with healthy donor plasma. ICAM-1 expression increased significantly in lumens incubated with sepsis plasma compared with those incubated with healthy control plasma, while concentrations of IL-6, IL-18, and soluble VEGF-R1 increased in sepsis plasma before and after incubation in the MPS compared with healthy control plasma. Use of the lung endothelial MPS may enable interrogation of specific mechanisms of endothelial dysfunction that promote ARDS in sepsis patients.

Early Plasma Nuclear DNA, Mitochondrial DNA, and Nucleosome Concentrations Are Associated With Acute Kidney Injury in Critically Ill Trauma Patients.

Circulating nucleic acids, alone and in complex with histones as nucleosomes, have been proposed to link systemic inflammation and coagulation after trauma to acute kidney injury (AKI). We sought to determine the association of circulating nucleic acids measured at multiple time points after trauma with AKI risk. DESIGN: We conducted a prospective cohort study of trauma patients, collecting plasma on presentation and at 6, 12, 24, and 48 hours, defining AKI over the first 6 days by Kidney Disease Improving Global Outcomes serum creatinine and dialysis criteria. We determined kinetics of plasma mitochondrial DNA (mtDNA), nuclear DNA (nDNA), and nucleosome levels across time points and associations with AKI using multivariable linear mixed-effects models, adjusted for injury characteristics and blood transfusions. We evaluated the association of presentation nucleic acid damage-associated molecular patterns (DAMP) concentrations with subsequent AKI, adjusting for injury severity using multivariable logistic regression. SETTING: Academic level I trauma center. PATIENTS: Trauma patients (n = 55) requiring intensive care for greater than or equal to 24 hours after presentation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: AKI developed in 17 patients (31%), a median of 12.0 hours (interquartile range, 6.2-24.1 hr) after presentation. mtDNA demonstrated a time-varying association with AKI (p = 0.022, interaction with time point), with differences by AKI status not emerging until 24 hours (ß = 0.97 [95% CI, 0.03-1.90] log copies/uL; p = 0.043). Patients who developed AKI had higher nDNA across all time points (overall ß = 1.41 log copies/uL [0.86-1.95 log copies/uL]; p < 0.001), and presentation levels were significantly associated with subsequent AKI (odds ratio [OR], 2.55 [1.36-4.78] per log copy/uL; p = 0.003). Patients with AKI had higher nucleosome levels at presentation (ß = 0.32 [0.00-0.63] arbitrary unit; p = 0.048), a difference that was more pronounced at 24 hours (ß = 0.41 [0.06-0.76]; p = 0.021) and 48 hours (ß = 0.71 [0.35-1.08]; p < 0.001) (p = 0.075, interaction with time point). CONCLUSIONS: Plasma nucleic acid DAMPs have distinct kinetics and associations with AKI in critically ill trauma patients. nDNA at presentation predicts subsequent AKI and may be amenable to targeted therapies in this population.

Plasma Mitochondrial DNA Levels Are Associated With ARDS in Trauma and Sepsis Patients.

BACKGROUND: Critically ill patients who develop ARDS have substantial associated morbidity and mortality. Circulating mitochondrial DNA (mtDNA) released during critical illness causes endothelial dysfunction and lung injury in experimental models. This study hypothesized that elevated plasma mtDNA is associated with ARDS in critically ill patients with trauma and sepsis. METHODS: Plasma mtDNA concentrations were measured at ED presentation and approximately 48 h later in separate prospective cohorts of critically ill patients with trauma and sepsis. ARDS was classified according to the Berlin definition. The association of mtDNA with ARDS was tested by using multivariable logistic regression, adjusted for covariates previously shown to contribute to ARDS risk in each population. RESULTS: ARDS developed in 41 of 224 (18%) trauma patients and in 45 of 120 (38%) patients with sepsis. Forty-eight-hour mtDNA levels were significantly associated with ARDS (trauma: OR, 1.58/log copies/µL; 95% CI, 1.14-2.19 [P = .006]; sepsis: OR, 1.52/log copies/µL; 95% CI, 1.12-2.06 [P = .007]). Plasma mtDNA on presentation was not significantly associated with ARDS in either cohort. In patients with sepsis, 48-h mtDNA was more strongly associated with ARDS among those with a nonpulmonary infectious source (OR, 2.20/log copies/µL; 95% CI, 1.36-3.55 [P = .001], n = 69) than those with a pulmonary source (OR, 1.04/log copies/µL; 95% CI, 0.68-1.59 [P = .84], n = 51; P = .014 for interaction). CONCLUSIONS: Plasma mtDNA levels were associated with incident ARDS in two critical illness populations. Given supportive preclinical data, our findings suggest a potential link between circulating mtDNA and lung injury and merit further investigation as a potentially targetable mediator of ARDS.

Plasma receptor interacting protein kinase-3 levels are associated with acute respiratory distress syndrome in sepsis and trauma: a cohort study.

BACKGROUND: Necroptosis, a form of programmed cell death mediated by receptor interacting serine/threonine-protein kinase-3 (RIPK3), is implicated in murine models of acute respiratory distress syndrome (ARDS). We hypothesized that plasma RIPK3 concentrations in sepsis and trauma would be associated with ARDS development and that plasma RIPK3 would reflect changes in lung tissue RIPK3 in a murine model of systemic inflammation. METHODS: We utilized prospective cohort studies of critically ill sepsis (n = 120) and trauma (n = 180) patients and measured plasma RIPK3 at presentation and 48 h. Patients were followed for 6 days for ARDS by the Berlin definition. We used multivariable logistic regression to determine the association of plasma RIPK3 with ARDS in each cohort, adjusting for confounders. In mice, we determined whether plasma and lung tissue RIPK3 levels rise concomitantly 4 h after injection with lipopolysaccharide and ZVAD-FMK, an apoptosis inhibitor. RESULTS: The change in plasma RIPK3 from presentation to 48 h (ΔRIPK3) was associated with ARDS in sepsis (OR 1.30, 95% CI 1.03-1.63, per ½ standard deviation) and trauma (OR 1.79, 95% CI 1.33-2.40). This association was not evident for presentation RIPK3 levels. Secondary analyses showed similar findings for the association of ΔRIPK3 with acute kidney injury and 30-day mortality. Mice injected with lipopolysaccharide and ZVAD-FMK had significantly higher plasma (p < 0.001) and lung (p = 0.005) RIPK3 than control mice. CONCLUSIONS: The change in plasma RIPK3 from presentation to 48 h in both sepsis and trauma patients is independently associated with ARDS, and plasma RIPK3 may reflect RIPK3 activity in lung tissue.

Short lung transplant donor telomere length is associated with decreased CLAD-free survival.

Telomere length (TL) decreases with cellular ageing and biological stressors. As advanced donor and recipient ages are risk factors for chronic lung allograft dysfunction (CLAD), we hypothesised that decreased age-adjusted donor TL would predict earlier onset of CLAD. Shorter donor TL was associated with increased risk of CLAD or death (HR 1.26 per 1 kb TL decrease, 95% CI 1.03 to 1.54), particularly for young donors. Recipient TL was associated with cytopenias but not CLAD. Shorter TL was also seen in airway epithelium for subjects progressing to CLAD (p=0.02). Allograft TL may contribute to CLAD pathogenesis and facilitate risk stratification.