To remove and replace-a role for plasma exchange in counterbalancing the host response in sepsis

Effect of therapeutic plasma exchange on tissue factor and tissue factor pathway inhibitor in septic shock

BACKGROUND

Coagulopathy is part of the pathological host response to infection in sepsis. Higher plasma concentrations of both tissue factor (TF) and tissue factor pathway inhibitor (TFPI) are associated with occurrence of disseminated intravascular coagulation (DIC), multi-organ dysfunction and increased mortality in patients with sepsis. Currently no treatment approaches specifically targeting this axis are available. We hypothesize that therapeutic plasma exchange (TPE) might limit this coagulopathy by restoring the balance of plasma proteins.

METHODS

This was a pooled post-hoc biobank analysis including 51 patients with early (shock onset < 24 h) and severe (norepinephrine dose > 0.4 μg/kg/min) septic shock, who were either receiving standard of care treatment (SOC, n = 14) or SOC + one single TPE (n = 37). Plasma concentrations of TF and TFPI were measured both at- and 6 h after study inclusion. The effect of TPE on concentrations of TF and TFPI was investigated and compared to SOC patients. Further, baseline TF and TFPI concentrations were used to modulate and predict clinical response to adjunctive TPE, indicated by longitudinal reduction of lactate concentrations over the first 24 h following study inclusion.

RESULTS

TPE led to a significant reduction in circulating concentrations of both TF and TFPI while no difference was observed in the SOC group. Relative change of TF within 6 h was + 14 (-0.8 to + 30.4) % (p = 0.089) in the SOC and -18.3 (-32.6 to -2.2) % (p < 0.001) in the TPE group (between group p < 0.001). Similarly, relative change of TFPI was + 14.4 (-2.3 to + 30.9) % (p = 0.076) in the SOC and -20 (-32.8 to -7.9) % (p < 0.001) in the TPE group (between group p = 0.022). The ratio of TF to TFPI remained unchanged in both SOC and TPE groups. SOC patients exhibited an increase in lactate over the initial 24 h when TF and TFPI concentrations were higher at baseline. In contrast, patients undergoing TPE experienced a sustained longitudinal reduction of lactate concentrations across all levels of baseline TF and TFPI elevations. In a multivariate mixed-effects model, higher baseline TF (p = 0.003) and TFPI (p = 0.053) levels led to greater longitudinal lactate concentration reduction effects in the TPE group.

CONCLUSIONS

Adjunctive TPE in septic shock is associated with a significant removal of both TF and TFPI, which may contribute to the early hemodynamic improvement observed in septic shock patients receiving TPE. Higher baseline TF (and TFPI) plasma concentrations were identified as a putative predictor of treatment response that could be useful for predictive enrichment strategies in future clinical trials.

[Extracorporeal procedures in sepsis]

Sepsis and septic shock are frequent and severe clinical pictures in intensive care medicine that result from a dysregulated immune response to an infection and cause a high mortality rate. This article provides an overview of the various extracorporeal procedures used to treat sepsis. Various procedures are used to treat sepsis and septic shock. These include high-volume hemofiltration (HVHF), very high-volume hemofiltration (VHVHF), high cut-off filter (HCO), polymyxin B hemoperfusion and cytokine adsorption filters. The HVHF and VHVHF remove inflammatory mediators but show no significant benefit in terms of stabilization and survival in sepsis patients. The HCO filters effectively eliminate cytokines but so far there is no evidence of a survival benefit. Polymyxin B hemoperfusion shows promising results in initial studies in certain patient groups, while evidence for cytokine adsorption filters is limited. Combined plasma filtration and adsorption (CPFA) and therapeutic plasma exchange (TPE) have so far shown promising results in small studies. Although CPFA shows no survival benefit, TPE may have protective effects on the vascular glycocalyx. Extracorporeal procedures carry risks such as thrombosis and loss of proteins and clotting factors. The therapeutic benefit of these procedures in the treatment of sepsis remains unclear and further prospective randomized multicenter studies are needed to evaluate their efficacy and safety. There are currently no guideline recommendations for the routine use of these procedures in sepsis.

EXCHANGE-2: investigating the efficacy of add-on plasma exchange as an adjunctive strategy against septic shock-a study protocol for a randomized, prospective, multicenter, open-label, controlled, parallel-group trial

BACKGROUND

Sepsis is as a life-threatening organ dysfunction caused by a dysregulated host response to an infection. The mortality of sepsis and particular of septic shock is very high. Treatment mostly focuses on infection control but a specific intervention that targets the underlying pathological host response is lacking to the present time. The investigators hypothesize that early therapeutic plasma exchange (TPE) will dampen the maladaptive host response by removing injurious mediators thereby limiting organ dysfunction and improving survival in patients with septic shock. Although small prospective studies demonstrated rapid hemodynamic stabilization under TPE, no adequately powered randomized clinical trial has investigated hard outcomes.

METHODS

This is a randomized, prospective, multicenter, open-label, controlled, parallel-group interventional trial to test the adjunctive effect of TPE in patients with early septic shock. Patients with a refractory (defined as norepinephrine (NE) ≥ 0.4 μg/kg/min ≥ 30 min OR NE 0.3 μg/kg/min + vasopressin) and early (shock onset < 24 h) septic shock will be included. The intervention is a standard TPE with donor fresh frozen plasma (1.2 × individual plasma volume) performed within 6 h after randomization and will be compared to a standard of care (SOC) control arm. The primary endpoint is 28 days mortality for which the power analysis revealed a group size of 137 / arm (n = 274) to demonstrate a benefit of 15%. The key secondary objective will be to compare the extent of organ failure indicated by mean SOFA over the first 7 days as well as organ support-free days until day 28 following randomization. Besides numerous biological secondary, safety endpoints such as incidence of bleeding, allergic reactions, transfusion associated lung injury, severe thrombocytopenia, and other severe adverse events will be assessed during the first 7 days. For exploratory scientific analyses, biomaterial will be acquired longitudinally and multiple predefined scientific subprojects are planned. This study is an investigator-initiated trial supported by the German Research Foundation (DFG, DA 1209/7-1), in which 26 different centers in Germany, Switzerland, and Austria will participate over a duration of 33 months.

DISCUSSION

This trial has substantial clinical relevance as it evaluates a promising adjunctive treatment option in refractory septic shock patients suffering from an extraordinary high mortality. A positive trial result could change the current standard of care for this septic subgroup. The results of this study will be disseminated through presentations at international congresses, workshops, and peer-reviewed publications.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05726825 , Registered on 14 February 2023.

Therapeutic apheresis in sepsis

Sepsis is a leading cause of morbidity and mortality worldwide. Dysregulated immune response to infection is a hallmark of sepsis, leading to life-threatening organ dysfunction or even death. Advancing knowledge of the complex pathophysiological mechanisms has been a strong impetus for the development of therapeutic strategies aimed at rebalancing the immune response by modulating the excess of both pro- and anti-inflammatory mediators. There is a wealth of preclinical data suggesting clinical benefits of various extracorporeal techniques in an attempt to modulate the exaggerated host inflammatory response. However, the evidence base is often weak. Owing to both an advancing comprehension of the pathophysiology and the increased quality of clinical trials, progress has been made in establishing extracorporeal therapies as part of the general therapeutic canon in sepsis. We aim for a comprehensive overview of the technical aspects and clinical applications in the context of the latest evidence concerning these techniques.

Clinical and biochemical endpoints and predictors of response to plasma exchange in septic shock: results from a randomized controlled trial

Background

Recently, a randomized controlled trial (RCT) demonstrated rapid but individually variable hemodynamic improvement with therapeutic plasma exchange (TPE) in patients with septic shock. Prediction of clinical efficacy in specific sepsis treatments is fundamental for individualized sepsis therapy.

Methods

In the original RCT, patients with septic shock of < 24 h duration and norepinephrine (NE) requirement ≥ 0.4 μg/kg/min received standard of care (SOC) or SOC + one single TPE. Here, we report all clinical and biological endpoints of this study. Multivariate mixed-effects modeling of NE reduction was performed to investigate characteristics that could be associated with clinical response to TPE.

Results

A continuous effect of TPE on the reduction in NE doses over the initial 24 h was observed (SOC group: estimated NE dose reduction of 0.005 µg/kg/min per hour; TPE group: 0.018 µg/kg/min per hour, p = 0.004). Similarly, under TPE, serum lactate levels, continuously decreased over the initial 24 h in the TPE group, whereas lactate levels increased under SOC (p = 0.001). A reduction in biomarkers and disease mediators (such as PCT (p = 0.037), vWF:Ag (p < 0.001), Angpt-2 (p = 0.009), sTie-2 (p = 0.005)) along with a repletion of exhausted protective factors (such as AT-III (p = 0.026), Protein C (p = 0.012), ADAMTS-13 (p = 0.008)) could be observed in the TPE but not in the SOC group. In a multivariate mixed effects model, increasing baseline lactate levels led to greater NE dose reduction effects with TPE as opposed to SOC (p = 0.004).

Conclusions

Adjunctive TPE is associated with the removal of injurious mediators and repletion of consumed protective factors altogether leading to preserved hemodynamic stabilization in refractory septic shock. We identified that baseline lactate concentration as a potential response predictor might guide future designing of large RCTs that will further evaluate TPE with regard to hard endpoints.

Trial registration Retrospectively registered 18th January 2020 at clinicaltrials.gov (Identifier: NCT04231994).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04003-2.

Extrakorporale Behandlungsstrategien der Sepsis

Hintergrund Die Mortalität der Sepsis bleibt auch im 21. Jahrhundert sehr hoch. Verschiedene adjuvante Strategien zur extrakorporalen Zytokinelimination wurden als zusätzliche therapeutische Maßnahmen bei Sepsis und septischem Schock untersucht.

Ziele Zusammenfassung einer Auswahl extrakorporaler Blutreinigungstechniken und der aktuellen Erkenntnisse in der klinischen Anwendung mit besonderem Schwerpunkt auf dem therapeutischen Plasmaaustausch.

Methoden Nicht systematische Literaturrecherche.

Ergebnisse Verschiedene extrakorporale Blutreinigungstechniken mit unterschiedlichen Evidenzniveaus hinsichtlich Zytokinelimination, Verbesserung der Hämodynamik und Verringerung der Mortalität werden derzeit klinisch eingesetzt. Die am ausführlichsten untersuchten Modalitäten umfassen die hochvolumige Hämofiltration/Dialyse mit und ohne High-Cut-off-Filter sowie Hämoadsorptionstechniken (einschließlich CytoSorb- und Polymyxin-B-Filter). Trotz teilweise ermutigender Beobachtungen bezüglich der Entfernung proinflammatorischer Zytokine und verbesserten Hämodynamik zeigten randomisierte Outcome-Studien bislang keinen positiven Einfluss auf das Überleben. Aufgrund der Verwendung von Spenderplasma als Substitutionsflüssigkeit stellt der therapeutische Plasmaaustausch das einzige Verfahren dar, das neben einer reinen Elimination zusätzlich verbrauchte protektive Faktoren ersetzen kann.

Schlussfolgerungen Die Anwendung extrakorporaler Blutreinigungsmethoden kann für Sepsispatienten außerhalb klinischer Studien bisher nicht empfohlen werden, da derzeit keine Beweise für ihre Wirksamkeit vorliegen. Zukünftige Untersuchungen sollten darauf abzielen, das Patientenkollektiv hinsichtlich des klinischen Schweregrads, des Zeitpunkts der Intervention und verschiedener inflammatorischer (Sub-)Phänotypen zu homogenisieren.

Targeting the "sweet spot" in septic shock - A perspective on the endothelial glycocalyx regulating proteins Heparanase-1 and -2

Sepsis is a life-threatening syndrome caused by a pathological host response to an infection that eventually, if uncontrolled, leads to septic shock and ultimately, death. In sepsis, a massive aggregation of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) cause a cytokine storm. The endothelial glycocalyx (eGC) is a gel like layer on the luminal side of the endothelium that consists of proteoglycans, glycosaminoglycans (GAG) and plasma proteins. It is synthesized by endothelial cells and plays an active role in the regulation of inflammation, permeability, and coagulation. In sepsis, early and profound injury of the eGC is observed and circulating eGC components correlate directly with clinical severity and outcome. The activity of the heparan sulfate (HS) specific glucuronidase Heparanase-1 (Hpa-1) is elevated in sepsis, resulting in shedding of heparan sulfate (HS), a main GAG of the eGC. HS induces endothelial barrier breakdown and accelerates systemic inflammation. Lipopolysaccharide (LPS), a PAMP mainly found on the surface of gram-negative bacteria, activates TLR-4, which results in cytokine production and further activation of Hpa-1. Hpa-1 shed HS fragments act as DAMPs themselves, leading to a vicious cycle of inflammation and end-organ dysfunction such as septic cardiomyopathy and encephalopathy. Recently, Hpa-1's natural antagonist, Heparanase-2 (Hpa-2) has been identified. It has no intrinsic enzymatic activity but instead acts by reducing inflammation. Hpa-2 levels are reduced in septic mice and patients, leading to an acquired imbalance of Hpa-1 and Hpa-2 paving the road towards a therapeutic intervention. Recently, the synthetic antimicrobial peptide 19-2.5 was described as a promising therapy protecting the eGC by inhibition of Hpa-1 activity and HS shed fragments in animal studies. However, a recombinant Hpa-2 therapy does not exist to the present time. Therapeutic plasma exchange (TPE), a modality already tested in clinical practice, effectively removes injurious mediators, e.g., Hpa-1, while replacing depleted protective molecules, e.g., Hpa-2. In critically ill patients with septic shock, TPE restores the physiological Hpa-1/Hpa-2 ratio and attenuates eGC breakdown. TPE results in a significant improvement in hemodynamic instability including reduced vasopressor requirement. Although promising, further studies are needed to determine the therapeutic impact of TPE in septic shock.

Effects of therapeutic plasma exchange on the endothelial glycocalyx in septic shock

Background

Disruption of the endothelial glycocalyx (eGC) is observed in septic patients and its injury is associated with multiple-organ failure and inferior outcomes. Besides this biomarker function, increased blood concentrations of shedded eGC constituents might play a mechanistic role in septic organ failure. We hypothesized that therapeutic plasma exchange (TPE) using fresh frozen plasma might influence eGC-related pathology by removing injurious mediators of eGC breakdown while at the time replacing eGC protective factors.

Methods

We enrolled 20 norepinephrine-dependent (NE > 0.4 μg/kg/min) patients with early septic shock (onset < 12 h). Sublingual assessment of the eGC via sublingual sidestream darkfield (SDF) imaging was performed. Plasma eGC degradation products, such as heparan sulfate (HS) and the eGC-regulating enzymes, heparanase (Hpa)-1 and Hpa-2, were obtained before and after TPE. A 3D microfluidic flow assay was performed to examine the effect of TPE on eGC ex vivo. Results were compared to healthy controls.

Results

SDF demonstrated a decrease in eGC thickness in septic patients compared to healthy individuals (p = 0.001). Circulating HS levels were increased more than sixfold compared to controls and decreased significantly following TPE [controls: 16.9 (8–18.6) vs. septic patients before TPE: 105.8 (30.8–143.4) μg/ml, p < 0.001; vs. after TPE: 70.7 (36.9–109.5) μg/ml, p < 0.001]. The Hpa-2 /Hpa-1 ratio was reduced in septic patients before TPE but normalized after TPE [controls: 13.6 (6.2–21.2) vs. septic patients at inclusion: 2.9 (2.1–5.7), p = 0.001; vs. septic patients after TPE: 13.2 (11.2–31.8), p < 0.001]. Ex vivo stimulation of endothelial cells with serum from a septic patient induced eGC damage that could be attenuated with serum from the same patient following TPE.

Conclusions

Septic shock results in profound degradation of the eGC and an acquired deficiency of the protective regulator Hpa-2. TPE removed potentially injurious eGC degradation products and partially attenuated Hpa-2 deficiency.

Trial registration clinicaltrials.gov NCT04231994, retrospectively registered 18 January 2020

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-021-00417-4.

[Extracorporeal Strategies in Sepsis Treatment: Role of Therapeutic Plasma Exchange]

BACKGROUND

 Mortality in sepsis remains high. Various techniques for extracorporeal cytokine removal have been investigated as additional therapeutic measures in sepsis and septic shock.

OBJECTIVES

 To summarize a selection of extracorporeal blood purification techniques, with a special focus on therapeutic plasma exchange, and their current evidence in clinical use.

METHODS

 Non-systematic literature review.

RESULTS

 Various extracorporeal blood purification techniques with different levels of evidence regarding cytokine removal, vasopressor sparing effects and reduction of mortality are currently in clinical use. Most extensively studied modalities include high-volume hemofiltration/dialysis with and without high cut-off filters a well as hemoadsorption techniques (including CytoSorb, and polymyxin-B filters). Despite partly encouraging observations regarding removal of inflammatory cytokines and hemodynamic stabilization, results from randomized studies did not show an effect on survival. Due to use of donor plasma as substitution fluid, therapeutic plasma exchange represents the only modality able to additionally replace protective and consumed factors.

CONCLUSIONS

 The use of extracorporeal blood purification methods cannot be recommended for sepsis patients outside of clinical trials given the current lack of evidence of their efficacy. Future investigations should aim to homogenize the studied patient collective in respect to clinical sepsis severity, time point of intervention and different inflammatory (sub-)phenotypes.

[What is evidence-based in the treatment of sepsis?]

BACKGROUND

The term sepsis was redefined in 2016 as a life-threatening organ dysfunction caused by an inadequate host response to an infection. The German S3 guidelines for the treatment of sepsis were published in 2018.

OBJECTIVE

What is evidence-based in the treatment of patients with sepsis?

MATERIAL AND METHODS

Discussion of the S3 guidelines and inclusion of study results after 2018.

RESULTS

The cornerstones for the treatment of sepsis continue to consist of early hemodynamic stabilization, anti-infection treatment and organ support procedures. Supportive and extracorporeal treatments are controversially discussed and continue to be intensively investigated.

CONCLUSION

Despite an improved understanding of the pathophysiology, there is still no effective causal sepsis treatment, i.e. directed against the pathological host reaction. The treatment of patients with sepsis is therefore still based on the basic principles of correction of volume deficits, anti-infective agents, source control and organ support, including the symptomatic treatment of vasoplegia with catecholamines.

Effect of Therapeutic Plasma Exchange on Immunoglobulin Deficiency in Early and Severe Septic Shock

BACKGROUND

Deficiency of immunoglobulins of the classes IgG, IgG1, IgA and IgM is associated with severity of disease and mortality in sepsis and septic shock. Therapeutic plasma exchange (TPE) with fresh frozen plasma (FFP) has recently gained attention as an adjunctive therapeutic option in early septic shock. We hypothesized that TPE might modulate immunoglobulin deficiencies besides sole elimination of circulating injurious molecules.

METHODS

We conducted a prospective single center study with TPE in 33 patients with early septic shock (onset < 12 h) requiring high doses of norepinephrine (NE > 0.4μg/kg/min). Clinical and biochemical data, including measurement of immunoglobulin subgroups IgG, IgG1, IgM and IgA were obtained before and after TPE. The following immunoglobulin cut-off values were used to analyze subgroups with low immunoglobulin concentrations at baseline (IgG ≤ 6.5, IgG1 ≤ 3, IgM ≤ 1.5 and IgA ≤ 0.35 g/L).

RESULTS

At inclusion, median (IQR) SOFA score was 18 (15-20) and NE dose was 0.8 (0.6-1.2) μg/kg/min. The majority of patients demonstrated profound reductions in immunoglobulins levels of all classes. Globally, immunoglobulin levels were not significantly changed after a single TPE session. However, in patients with low baseline immunoglobulin levels a significant increase in all classes was observed (IgG 1.92 (0.96-3) g/L (+41%), IgG1 2.1 (1.46-2.32) g/L (+96%), IgA 0.44 (0.12-0.62) g/L (59%) and IgM 0.18 (0.14-0.34) g/L (+55%), p < 0.001 for comparison to patients above cut-off).

CONCLUSIONS

The majority of early and severe septic shock patients had reduced immunoglobulin levels and a single TPE could attenuate immunoglobulin deficiencies of all classes. The clinical relevance of this observation has to be investigated in a proper designed trial.

[Extracorporeal techniques for blood purification in sepsis: an update]

BACKGROUND

Despite ongoing development, mortality in sepsis remains considerable. Various techniques for extracorporeal cytokine removal have been described, but evidence remains conflicting.

OBJECTIVES

The aim of this article is to summarize currently used extracorporeal blood purification techniques and their evidence.

METHODS

Non-systematic literature review RESULTS: There are currently various blood purification techniques used with different levels of evidence regarding cytokine removal, vasopressor sparing effects and reduction of mortality, including high-volume dialysis with and without high cut-off filters, special adsorption filters (including CytoSorb®, CytoSorbents Europe, Berlin, Germany, and polymyxin‑B filters). There is development regarding therapeutic plasma exchange. For some blood purification techniques such as combined plasma filtration and adsorption, multicentric randomized studies found a negative effect on survival.

CONCLUSIONS

Despite a theoretical rationale, the use of blood purification methods cannot be recommended for sepsis patients due to the lack of evidence of their efficacy. Heterogeneous inflammatory responses in sepsis render conduction of larger trials difficult. Thus, future studies should cautiously identify appropriate sepsis subtypes to be included. Available techniques should be chosen as individualized complementary treatments and not as competing systems.

Therapeutic plasma exchange in acute on chronic liver failure

BACKGROUND

Acute on chronic liver failure (ACLF) has been identified as a distinct syndrome due to acute decompensation of liver cirrhosis accompanied by extra-hepatic organ failure, primarily caused by an overwhelming systemic immune response. Therapeutic plasma exchange (TPE) has been demonstrated in a randomized controlled trial to improve transplant free survival in acute liver failure. Here we investigated if TPE might have comparable beneficial effects in patients with ACLF.

METHODS

Thirty-one patients with ACLF that were treated with TPE were enrolled into this retrospective analysis and 1:1 matched to an ACLF cohort treated with standard medical therapy (SMT) only.

RESULTS

Patients considered for a bridge to recovery (n = 21 each group) approach had a 30-day mortality >90% that was not improved by TPE (P = .185). Deaths occurred in the SMT group at significant earlier time points compared to the patients treated with TPE (mortality at 5 days: 33.3% for TPE and 66.7% for SMT, P = .048). However, patients who received TPE as a bridge to transplant strategy (n = 10) survived in 60% of cases and demonstrated 24 hours after study inclusion a stabilization of organ dysfunction (organ failures at inclusion: 4 (3-5) vs 24 hours after inclusion: 3 (2-4), P = .031 and CLIF-C-ACLF score: 64 (49-76) vs 54 (49-66), P = .043) not seen in SMT patients.

CONCLUSIONS

Although these retrospective data need to be interpreted with caution, they suggest that TPE in ACLF patients is feasible but not suitable as a bridge to recovery strategy. In selected patients TPE might assist as bridge to transplant.