The endothelial glycocalyx (eGC), a carbohydrate-rich layer lining the luminal surface of the endothelium, provides a first vasoprotective barrier against vascular leakage and adhesion in sepsis and vessel inflammation. Angiopoietin-2 (Angpt-2), an antagonist of the endothelium-stabilizing receptor Tie2 secreted by endothelial cells, promotes vascular permeability through cellular contraction and junctional disintegration. We hypothesized that Angpt-2 might also mediate the breakdown of the eGC. Using confocal and atomic force microscopy, we show that exogenous Angpt-2 induces a rapid loss of the eGC in endothelial cells in vitro. Glycocalyx deterioration involves the specific loss of its main constituent heparan sulphate, paralleled by the secretion of the heparan sulphate-specific heparanase from late endosomal/lysosomal stores. Corresponding in vivo experiments revealed that exogenous Angpt-2 leads to heparanase-dependent eGC breakdown, which contributes to plasma leakage and leukocyte recruitment in vivo. Our data indicate that eGC breakdown is mediated by Angpt-2 in a non-redundant manner.

Deterioration of the endothelial glycocalyx (eGC), a protective carbohydrate-rich layer lining the luminal surface of the endothelium, plays a key role in vascular barrier dysfunction and eventually organ-failure in systemic inflammatory response syndrome and sepsis. Early detection of glycocalyx damage could thus become an important goal in critical care. This study was designed to determine the feasibility and reproducibility of quantitative, real-time glycocalyx measurements performed at bedside in the emergency room (ER) and intensive care unit (ICU). The observational study included 70 patients admitted to the ER or ICU of a university hospital. A physician and the nurse in charge of the patient performed sublingual microcirculatory measurements using sidestream dark field (SDF) imaging. A novel data acquisition and analysis software (GlycoCheck™) was used to analyze the perfused boundary region (PBR), an inverse parameter of endothelial glycocalyx dimensions in vessels with diameters of between 5 and 25 μm. The method showed a good intra-observer reproducibility. Specifically, intraclass correlation coefficient analysis showed an excellent reproducibility between the physician’s measurements (0.77 [CI 95%: 0.52–0.89]). The bias between the two PBRs was − 0.077 ± 0.24 μm. Moreover, there were no significant differences in the PBR values obtained by the nurses when compared to those reported by the physician (regarded as the “gold standard” measurement). Intraclass correlation coefficient analysis showed excellent reproducibility between the nurses’ and physician’s PBRs (0.75 [95% CI: 0.52–0.87]). The mean difference between the two PBRs (i.e., the bias) was 0.007 ± 0.25 μm. The nurses’ PBR assessment had a 90% sensitivity (95% CI: 60–99%) and 90% specificity (95% CI: 80–93%) to identify a severely impaired glycocalyx. Glycocalyx dimensions can be measured at patients’ bedside precisely by non-invasive assessment of the PBR. This assessment could become part of standard monitoring and contribute to clinical decision-making and resuscitation protocols in clinical trials and daily practice.

Appropriate and timely recognition of sepsis is a prerequisite for starting goal-directed therapy bundles. We analyzed the appropriateness of sepsis recognition and documentation with regard to adequacy of therapy and outcome in an internal medicine emergency department (ED). This study included 487 consecutive patients ≥18 years of age who presented to a university hospital ED during a 4-week period. Clinical, laboratory, and follow-up data were acquired independently from documentation by ED physicians. The study team independently rated quality of sepsis classification (American College of Chest Physicians/Society of Critical Care Medicine definitions), diagnostic workup, and guideline-adherent therapy in the ED. Of 487 included patients, 110 presented because of infection. Of those, 54 patients matched sepsis criteria, including 20 with organ damage and thus severe sepsis, as rated by the study team. Sepsis was not recognized in 32 of these 54 cases (59%). Multivariate binary logistic regression analysis revealed that higher systolic blood pressure (p <0.05), the ability to stand (p <0.01) and a low number of documented vital signs in the ED discharge letter (p < 0.05) were independent predictors of missed sepsis. Surprisingly, adequate detection of the septic focus (81 vs. 93%, p = 0.17), appropriate fluid administration (86 vs. 87%, p = 0.39), and guideline-adherent antibiotic regimen (95 vs. 100%, p = 0.42) did not differ between cases of recognized and unrecognized sepsis, respectively. Non-recognition affected neither death-censored length of hospital stay (median 7.63 d vs. 7.13 d, p = 0.42) nor a combined endpoint of death or ICU admission to (9 vs. 12%, p = 0.55). Non-recognition of sepsis in ED patients with serious infections who formally meet organizational sepsis definitions seems to have no deleterious impact on initial therapy adequacy.

Aims: Although coronavirus disease 2019 (COVID-19) and bacterial sepsis are distinct conditions, both are known to trigger endothelial dysfunction with corresponding microcirculatory impairment. The purpose of this study was to compare microvascular injury patterns and proteomic signatures in COVID-19 and bacterial sepsis patients. Methods and results: This multi-center, observational study included 22 hospitalized adult COVID-19 patients, 43 hospitalized bacterial sepsis patients, and 10 healthy controls from 4 hospitals. Microcirculation and glycocalyx dimensions were quantified via intravital sublingual microscopy. Plasma proteins were measured using targeted proteomics (Olink). Coregulation and cluster analysis of plasma proteins was performed using a training-set and confirmed in a test-set. An independent external cohort of 219 COVID-19 patients was used for validation and outcome analysis. Microcirculation and plasma proteome analysis found substantial overlap between COVID-19 and bacterial sepsis. Severity, but not disease entity explained most data variation. Unsupervised correlation analysis identified two main coregulated plasma protein signatures in both diseases that strictly counteract each other. They were associated with microvascular dysfunction and several established markers of clinical severity. The signatures were used to derive new composite biomarkers of microvascular injury that allow to predict 28-day mortality or/and intubation (area under the curve 0.90, p < 0.0001) in COVID-19. Conclusion: Our data imply a common biological host response of microvascular injury in both bacterial sepsis and COVID-19. A distinct plasma signature correlates with endothelial health and improved outcomes, while a counteracting response is associated with glycocalyx breakdown and high mortality. Microvascular health biomarkers are powerful predictors of clinical outcomes. Graphical

(1) Damage to the endothelial glycocalyx (eGC), a protective layer lining the endothelial luminal surface, is associated with chronic kidney disease (CKD), which leads to a worsening of cardiovascular outcomes in these patients. Currently, there are no targeted therapeutic approaches. Whether the dietary supplement Endocalyx^TM (ECX) protects against endothelial damage caused by uremic toxins is unknown. (2) We addressed this question by performing atomic force microscopy measurements on living endothelial cells. We examined the effect of ECX on eGC thickness at baseline and with pooled serum from hemodialysis patients. ECX was also successfully administered in vivo in mice, in which eGC was assessed using perfused boundary region measurements by intravital microscopy of cremasteric vessels. (3) Both ECX and fucoidan significantly improved baseline eGC thickness. Our data indicate that these effects are dependent on ERK/MAPK and PI3K signaling. After incubation with eGC damaging serum from dialysis patients, ECX increased eGC height. Intravital microscopy in mice revealed a relevant increase in baseline eGC dimensions after feeding with ECX. (4) We identified a dietary supplement containing glycocalyx substrates and fucoidan as potential mediators of eGC preservation in vitro and in vivo. Our findings suggest that fucoidan may be an essential component responsible for protecting the eGC in acute settings. Moreover, ECX might contribute to both protection and rebuilding of the eGC in the context of CKD.