Effect of extracorporeal cytokine removal on vascular barrier function in a septic shock patient

Abstract

Background: Sepsis and septic shock are major healthcare problems, affecting millions of individuals around the world each year. Pathophysiologically, septic multiple organ dysfunction (MOD) is a life-threatening condition caused by an overwhelming systemic inflammatory response of the host's organism to an infection. We experimentally tested if high circulating cytokine levels might increase vascular permeability-a critical hallmark of the disease-and if this phenomenon can be reversed by therapeutic cytokine removal (CytoSorb®) in an exemplary patient.

Case presentation: A 32-year-old Caucasian female presented with septic shock and accompanying acute kidney injury (Sequential Organ Failure Assessment (SOFA) = 18) to our ICU. In spite of a broad anti-infective regimen, adequate fluid resuscitation, and high doses of inotropics and catecholamines, she remained refractory hypotensive. The extraordinary severity of septic shock suggested an immense overwhelming host response assumingly accompanied by a notable cytokine storm such as known from patients with toxic shock syndrome. Thus, a CytoSorb® filter was added to the dialysis circuit to remove excess shock-perpetuating cytokines. To analyze the endothelial phenotype in vitro before and after extracorporeal cytokine removal, we tested the septic shock patient's serum on human umbilical vein endothelial cells (HUVECs). The effect on endothelial integrity was assessed both on the morphological (fluorescent immunocytochemistry for VE-cadherin and F-actin) and functional (transendothelial electrical resistance (TER)) level that was recorded in real time with an "electric cell-substrate impedance sensing" (ECIS) system (ibidi). We found (1) severe alterations of cell-cell contacts and the cytoskeletal architecture and (2) profound functional permeability changes, the putative cellular correlate of the clinical vascular leakage syndrome. However, the endothelial barrier was protected from these profound adverse effects when HUVECs were challenged with septic shock serum that was collected after extracorporeal cytokine removal.

Conclusions: Beneficial observations of extracorporeal cytokine removal in septic shock patients might-at least in part-be promoted via protection of vascular barrier function.

Keywords: Cytokines; Endothelial permeability; Extracorporeal removal; Sepsis; Vascular leakage.

Figures

Fig. 1

Endothelial phenotype with respect to barrier function. Fluorescence immunocytochemistry staining for vascular endothelial (VE)-cadherin (green), F-actin (red), was performed on confluent human umbilical vein endothelial cells (HUVECs) as described before [5]. Cells were treated for 30 min with media supplemented with 5% serum from an individual with septic shock before (2nd row) and after cytokine removal (3rd row); 5% healthy human serum served as a control (1st row). Scale bar 10 μm

Fig. 2

Transendothelial resistance (TER) of HUVECs treated with septic serum. Normalized transendothelial electrical resistance (TER) was longitudinally measured in real time in human umbilical vein endothelial cells (HUVECs) with an electric cell-substrate impedance sensing (ECIS) device. HUVECs were then challenged with either septic serum before cytokine removal (bold line) or with serum from the same patient 24 h after cytokine removal (dotted line). TER normalization refers to the start point of the experiment for each condition (i.e., 5 min before septic serum incubation)