No abstract

Background: Cardiac surgery often represents the only treatment option in patients with infective endocarditis (IE). However, IE surgery may lead to a sudden release of inflammatory mediators, which is associated with the severity of postoperative organ dysfunction. We investigated the impact of hemoadsorption during IE surgery on postoperative organ dysfunction. Methods: This multi-center, randomized, non-blinded, controlled trial assigned patients undergoing cardiac surgery for IE to hemoadsorption [integration of CytoSorb® to cardiopulmonary bypass (CPB)] or control. The Primary outcome (ΔSOFA) was defined as the difference between the mean total postoperative sequential organ failure assessment score (SOFA), calculated maximally to the 9th postoperative day, and the basal SOFA score. The analysis was by modified intention-to-treat. A predefined inter-group comparison was done using a linear mixed model for ΔSOFA including surgeon and baseline SOFA as fixed effect covariates and with the surgical center as random effect. The SOFA score assesses dysfunction in six organ systems, each scored from zero to four. Higher scores indicate worsening dysfunction. Secondary outcomes were 30-day mortality, durations of mechanical ventilation, vasopressor and renal replacement therapy. Cytokines were measured in the first 50 patients. Results: Between January 17, 2018 and January 31, 2020, A total of 288 patients were randomly assigned to hemoadsorption (n=142) or control (n=146). Four patients in the hemoadsorption and two in the control group were excluded as they did not undergo surgery. The primary outcome ΔSOFA did not differ between the hemoadsorption and the control group (1.79 ± 3.75 and 1.93 ± 3.53, respectively, 95% CI: −1.30 to 0.83, p=0.6766). Mortality at 30 days (21% hemoadsorption vs 22% control, p=0.782), the durations of mechanical ventilation, vasopressor and renal replacement therapy did not differ between groups. Levels of IL-1β and IL-18 at the end of CPB were significantly lower in the hemoadsorption than in the control group. Conclusions: This randomized trial failed to demonstrate a reduction in postoperative organ dysfunction through intraoperative hemoadsorption in patients undergoing cardiac surgery for IE. Although hemoadsorption reduced plasma cytokines at the end of CPB, there was no difference in any of the clinically relevant outcome points.

Innate immune responses and rapid recruitment of leukocytes, which regulate inflammation and subsequent healing, play a key role in acute myocardial infarction (MI). Peptidylarginine deiminase 4 (PAD4) is critically involved in chromatin decondensation during the release of Neutrophil Extracellular Traps (NETs) by activated neutrophils. Alternatively, activated macrophages (M2) and accurate collagen deposition determine the repair of the infarcted heart. In this study, we investigated the impact of NETs on macrophage polarization and their role for acute cardiac inflammation and subsequent cardiac healing in a mouse model of acute MI. NETs were found to promote in vitro macrophage polarization toward a reparative phenotype. NETs suppressed pro-inflammatory macrophages (M1) under hypoxia and diminished IL-6 and TNF-α expression. Further on, NETs strongly supported M2b polarization and IL-10 expression. In cardiac fibroblasts, NETs increased TGF-ß expression under hypoxic culture conditions. PAD4−/− mice subjected to permanent ligation of the left anterior descending artery suffered from overwhelming inflammation in the acute phase of MI. Noteworthy, PAD4−/− neutrophils were unable to release NETs upon ex vivo stimulation with ionomycin or PMA, but produced significantly higher amounts of reactive oxygen species (ROS). Increased levels of circulating cell-free DNA, mitochondrial DNA and cardiac troponin were found in PAD4−/− mice in the acute phase of MI when compared to WT mice. Reduced cardiac expression of IL-6, IL-10, and M2 marker genes, as well as increased TNF-α expression, suggested a pro-inflammatory state. PAD4−/− mice displayed significantly increased cardiac MMP-2 expression under baseline conditions. At day 1, post-MI, PAD4−/− mice showed increased end-diastolic volume and increased thinning of the left ventricular wall. Interestingly, improved cardiac function, as demonstrated by significantly increased ejection fraction, was found at day 21. Altogether, our results indicate that NETs support macrophage polarization toward an M2 phenotype, thus displaying anti-inflammatory properties. PAD4 deficiency aggravates acute inflammation and increases tissue damage post-MI, partially due to the lack of NETs.