Mechanisms of the anti-inflammatory effects of hydroxyethyl starch demonstrated in a flow-based model of neutrophil recruitment by endothelial cells*:

Comparison of Treatment Effects of Different Iron Chelators in Experimental Models of Sepsis

Growing evidence indicates that dysregulated iron metabolism with altered and excess iron availability in some body compartments plays a significant role in the course of infection and sepsis in humans. Given that all bacterial pathogens require iron for growth, that iron withdrawal is a normal component of innate host defenses and that bacterial pathogens have acquired increasing levels of antibiotic resistance, targeting infection and sepsis through use of appropriate iron chelators has potential to provide new therapeutics. We have directly compared the effects of three Food and Drug Administration (FDA)-approved chelators (deferoxamine—DFO; deferiprone—DFP; and deferasirox—DFX), as were developed for treating hematological iron overload conditions, to DIBI, a novel purpose-designed, anti-infective and anti-inflammatory water-soluble hydroxypyridinone containing iron-selective copolymers. Two murine sepsis models, endotoxemia and polymicrobial abdominal sepsis, were utilized to help differentiate anti-inflammatory versus anti-infective activities of the chelators. Leukocyte adhesion, as measured by intravital microscopy, was observed in both models, with DIBI providing the most effective reduction and DFX the poorest. Inflammation in the abdominal sepsis model, assessed by cytokine measurements, indicated exacerbation by DFX and DFO for plasma Interleukin (IL)-6 and reductions to near-control levels for DIBI and DFP. Peritoneal infection burden was reduced 10-fold by DIBI while DFX and DFP provided no reductions. Overall, the results, together with those from other studies, revealed serious limitations for each of the three hematological chelators, i.e., as potentially repurposed for treating infection/sepsis. In contrast, DIBI provided therapeutic benefits, consistent with various in vitro and in vivo results from other studies, supporting the potential for its use in treating sepsis.

Granulozytentransfusion: Update 2020

Die therapeutische Anwendung von Granulozytenkonzentraten erfolgt im klinischen Alltag im Gegensatz zu der anderer Blutprodukte nur selten und unregelmäßig. Der zurückhaltende Einsatz beruht unter anderem auf dem Fehlen einer breiten Evidenz, logistischen und wirtschaftlichen Problemen und dem Vorhandensein anderer potenter Therapieoptionen neutropener Infektionen. Dennoch gab es in den letzten Jahren neue wissenschaftliche Erkenntnisse nicht nur zu Physiologie und Pathophysiologie der Granulozyten, wie neu charakterisierten zellulären Verteidigungsstrategien oder deren Mitwirkung bei thrombotischen oder malignen Ereignissen, sondern auch zu deren therapeutischem Effekt. Dieser wird von einer Vielzahl an Parametern, wie der Art der Infektion, dem Transfusionszeitpunkt und der Dosis, beeinflusst. Das macht die Indikationsstellung zu einer komplexen Einzelfallentscheidung und es gilt, die heterogene Datenlage systematisch zusammenzufassen. Außerdem wurden die etablierten Indikationen neutropener bzw. neutropathischer Infektionen um experimentelle, mögliche neue Anwendungsgebiete wie die Mukositis oder Leukämiebehandlung erweitert. Die erfolgreiche Anwendung setzt eine geeignete, moderne Herstellungsweise voraus. Neben der Apherese, bei der eine relativ hohe Spenderbelastung unter anderem durch Nebenwirkungen von Mobilisationsregime und Sedimentationsbeschleunigern berücksichtigt werden muss, existieren weitere Verfahren wie die Gewinnung von Granulozyten aus Buffy Coats von Vollblutspenden. Diese versprechen eine Reduktion logistischer Probleme und unerwünschter Wirkungen auf den Spender. Unerwünschte Wirkungen bei Empfängern von Granulozytentransfusionen sollten nach wie vor berücksichtigt und gegen einen erhofften therapeutischen Effekt abgewogen werden.

Immune response in fluid therapy with crystalloids of different ratios or colloid for rats in haemorrhagic shock

This study investigated the association between different ratios of balanced salt based-crystalloid (PLASMA SOLUTION-A [CJ HealthCare, Seoul, Korea]) (the ratios of crystalloid for blood loss, 1:1, 1:2 and 1:3) or balanced salt-based colloid (VOLULYTE 6% [Fresenius Kabi, Germany]) (the ratio of colloid for blood loss, 1:1) to restore blood loss and immune response in rats with haemorrhagic shock. About 50% of total estimated blood volume was removed after anaesthesia. The fluid was administered for resuscitation after exsanguination, according to the type of fluid and the ratios of exsanguinated volume and fluid volume for resuscitation. After sacrifice, expression of immune cells in blood and tissues was evaluated. Histological analyses and syndecan-1 immunohistochemistry assays were performed on tissues. Endothelial damage according to syndecan-1 and cytokine levels in blood was also assessed. Fluid resuscitation with same, two-fold, or three-fold volumes of crystalloid, or same volume of colloid, to treat haemorrhagic shock in rats resulted in a similar increase in blood pressure. The expression of neutrophils in blood decreased significantly after colloid administration, compared to before exsanguination. Syndecan-1 expression increased after exsanguination and fluid resuscitation in all groups, without any significant difference. In conclusion, same volume of balanced salt-based crystalloid for blood loss was enough to restore BP at the choice of fluid for the management of haemorrhagic shock in the rats, compared with different ratios of crystalloid or same volume of colloid, on the aspect of immune response.

Effects of hydroxyethyl starch (HES 130/0.42) on endothelial and epithelial permeability in vitro

Hydroxyethyl starch (HES) is employed to sustain normovolemia in patients. Using a perfused organ model, we recently showed that HES impairs the intestinal barrier which is constituted of endothelial and epithelial cell layers. However, the target cells and molecular actions of HES in the intestine are mainly unknown. Employing a model of human endothelial (HUVEC) and intestinal epithelial cells (Caco-2), we investigated the impact of HES, albumin and HES/albumin on cellular integrity/permeability and evaluated underlying molecular mechanisms. Monolayers of HUVEC and Caco-2 were cultured with HES (3%), albumin (3%) or HES/albumin (1.5%/1.5%). Integrity and permeability of the cell layers were evaluated by FITC-dextran transfer, measurements of cell detachment, vitality, cell volume, LDH release and caspase-3/7 activity. Cellular mechanisms were analyzed by Westernblotting for P-akt, P-erk, claudin-3 and I-FABP. HES application resulted in higher numbers of non-adherent/floating HUVEC cells (P<0.05) but did not change vitality or cell volume. Both, HES and HES/albumin increased the permeability of HUVEC monolayers (P<0.001), while LDH release, caspase-3/7 activity, akt/erk phosphorylation and claudin-3 expression were not affected. HES and HES/albumin did not change any of the parameters in cultures of Caco-2 cells. HES is able to disturb the integrity of the endothelial but not the epithelial barrier in vitro. HES effects are unrelated to cell damage and apoptosis but may involve reduced cell-cell or cell-matrix adhesion.

Impact of hydroxyethyl starch and modified fluid gelatin on granulocyte phenotype and function

BACKGROUND

Patients with neutropenia or granulocyte dysfunction may require granulocyte transfusions for adequate immune restoration. High-molecular-weight hydroxyethyl starch (HES) is the most commonly used sedimentation agent to enhance granulocyte collection efficiency. However, authorities recently restricted the use of HES due to its unfavorable risk-benefit profile. As modified fluid gelatin (MFG) is already used as an alternative sedimentation agent, we tested the hypothesis that MFG is not inferior to HES in terms of the functionality and viability of granulocytes.

STUDY DESIGN AND METHODS

Granulocytes from ten healthy donors were isolated, aliquoted and incubated in parallel for 2 hours with either 0% (control), 7.5%, 15%, or 30% MFG (Gelafundin) or HES (Hespan), respectively, and granulocyte migration, chemotaxis, reactive oxygen species (ROS) production, neutrophil extracellular trap formation (NETosis), antigen expression, and viability were subsequently investigated in vitro.

RESULTS

Relative to the controls, all three concentrations of HES compared to only 15% and 30% MFG lowered migration distances, and the 15% and 30% concentrations of both sedimentation agents reduced track straightness. HES resulted in lower CD11b expression and higher CD62L expression compared to MFG and the controls, whereas the differences for CD66b did not reach statistical significance. No significant differences in the timing of ROS production or NETosis, or in neutrophil viability or respiratory burst were observed.

CONCLUSION

These results indicate that MFG is not inferior to HES in terms of granulocyte function in vitro when used at equal concentrations, and that potential impairment of granulocyte function can occur with HES.

Hydroxyethyl Starch 130/0.4 Binds to Neutrophils Impairing Their Chemotaxis through a Mac-1 Dependent Interaction

Several studies showed that hydroxyethyl starch (HES), a synthetic colloid used in volume replacement therapies, interferes with leukocyte-endothelium interactions. Although still unclear, the mechanism seems to involve the inhibition of neutrophils' integrin. With the aim to provide direct evidence of the binding of HES to neutrophils and to investigate the influence of HES on neutrophil chemotaxis, we isolated and treated the cells with different concentrations of fluorescein-conjugated HES (HES-FITC), with or without different stimuli (N-Formylmethionine-leucyl-phenylalanine, fMLP, or IL-8). HES internalization was evaluated by trypan blue quenching and ammonium chloride treatment. Chemotaxis was evaluated by under-agarose assay after pretreatment of the cells with HES or a balanced saline solution. The integrin interacting with HES was identified by using specific blocking antibodies. Our results showed that HES-FITC binds to the plasma membrane of neutrophils without being internalized. Additionally, the cell-associated fluorescence increased after stimulation of neutrophils with fMLP (p < 0.01) but not IL-8. HES treatment impaired the chemotaxis only towards fMLP, event mainly ascribed to the inhibition of CD-11b (Mac-1 integrin) activity. Therefore, the observed effect mediated by HES should be taken into account during volume replacement therapies. Thus, HES treatment could be advantageous in clinical conditions where a low activation/recruitment of neutrophils may be beneficial, but may be harmful when unimpaired immune functions are mandatory.

The effects of crystalloid versus synthetic colloid in vitro on immune cells, co-cultured with mouse splenocytes

This study assessed the effects of crystalloid versus synthetic colloid in vitro on immune cells co-cultured with mouse splenocytes. Mouse splenocytes were co-cultured with three different types of fluid: Plasma solution-A^® (CJ HealthCare, Seoul, Korea; the crystalloid group); Tetraspan 6%^® (B. Braun Medical, Melsungen, Germany; the Colloid-T group); and Volulyte 6%^® (Fresenius Kabi, Bad Homburg vor dér-Höhe, Germany; Colloid-V group). To evaluate the acquired immune response, cluster of differentiation (CD) 4⁺ T cells and CD8⁺ T cells were measured. To evaluate the innate immune response, neutrophils were measured. The frequencies of CD4⁺ and CD8⁺ T cells did not differ significantly among the three groups on day 1 or 3. However, the frequencies of CD4⁺ and CD8⁺ T cells in the two synthetic colloid groups were significantly higher than those in the crystalloid group on day 7. On day 1, the frequency of neutrophils was significantly lower in the two synthetic colloid groups, compared with the crystalloid group. However, the values on the other days were similar among all three groups. In conclusion, crystalloid had a limited effect on the immune response; on the other hand, synthetic colloid increased the acquired immune response, although it temporarily inhibited the innate immune response.

Physical plugging does not account for attenuation of capillary leakage by hydroxyethyl starch 130/0.4: a synthetic gel layer model

Hydroxyethyl starch (HES) solutions, widely used plasma substitutes, reportedly attenuate capillary leakage via physical plugging of capillary defects. We investigated how 2% HES solutions of different molecular weights (HES(70): 70 kDa, HES(130): 130 kDa, HES(200): 200 kDa, and HES(670): 670 kDa) affect dye release from polyacrylamide gels (PAGs) as a model of endothelial glycocalyx. We assessed dye release from 4% PAG with varying concentrations of albumin [0, 1, 2, 4, and 8% (w/v)] by measuring the change in dye absorbance (ΔAbs) at 5 h for each HES solution. For PAG containing no albumin, ΔAbs for HES(130) was 30% lower than that for HES(70) and HES(200), and 50% lower than that for HES(670). At concentrations of 1-8% albumin, ΔAbs at 5 h with HES(70), HES(130), and HES(200) solutions were almost half that with the HES(670) solution, but no significant differences were noted in ΔAbs at 5 h among HES(70), HES(130), and HES(200) solutions. The inhibition of dye release by HES(670) is likely due to the hindering effect of HES molecules partitioned into gel pores. However, a unique property of HES(130) , including the heavy hydroxyethylation at the C(2) position, may promote specific interactions with PAG and thereby inhibit solute release.

Application of the multisolute osmotic virial equation to solutions containing electrolytes

The prediction of multisolute solution behavior of solutions containing electrolytes is important in many areas of research, including cryopreservation. In this study, the use of a novel form of the osmotic virial equation for multisolute solutions containing an electrolyte is investigated and compared to a rigorous electrolyte solution theory, the Pitzer-Debye-Huckel equation. For aqueous solutions containing a small molecule (either dimethyl sulfoxide or glycerol) and sodium chloride, the multisolute osmotic virial equation, which utilizes only two parameters to capture the electrolyte solution behavior, is shown to be as accurate as the Pitzer-Debye-Huckel equation, which utilizes six empirical parameters and multiple functions to capture the electrolyte solution behavior. In addition, an approach based on the multisolute osmotic virial equation to investigate the effect of electrolyte concentration on macromolecule solution behavior is presented and applied to aqueous solutions of hydroxyethyl starch and sodium chloride. The multisolute osmotic virial equation is shown to be an accurate, straightforward predictive solution theory for important multisolute solutions containing electrolytes.

Hydroxyethylstarch supplementation in burn resuscitation--a prospective randomised controlled trial

INTRODUCTION

Hydroxyethylstarches (HES) are thought to be beneficial in trauma and major surgery management, due to their volume expansion and anti-inflammatory properties. This study examined the use of 6% (HES) in burn resuscitation.

METHODS

26 adult patients with burns exceeding 15% total body surface area (TBSA) were randomised to either crystalloid (Hartmann's solution) or a colloid-supplemented resuscitation regime, where 1/3 of the crystalloid-predicted requirement was replaced by 6% HES.

RESULTS

There was no difference in age, gender or TBSA between the two groups. The median (95% CI) fluid volume/%TBSA received in the first 24 h was 307 ml and 263 ml for the crystalloid only and HES-supplemented group respectively (p=0.0234, Mann-Whitney). Body weight gain within the first 24 h after injury was significantly lower in the HES-supplemented group 2.5 kg versus 1.4 kg respectively (p=0.0039). The median (95% CI) serum C-reactive protein at 48 h after injury was 210 (167-257) and 128 (74-145) mg/L for the crystalloid only and HES-supplemented group respectively (p=0.0001). Albumin-creatinine ratio per % burn (ACR, a marker of capillary leak) was lower in the HES-supplemented group at 12h after burn (p=0.0310).

CONCLUSIONS

Patients treated with HES-supplemented resuscitation required less fluid, showed less interstitial oedema and a dampened inflammatory response compared to patients receiving isotonic crystalloid alone.

The impact of fluid therapy on microcirculation and tissue oxygenation in hypovolemic patients: a review

PURPOSE

An optimal volume replacement strategy aims to restore systemic hemodynamics with the ultimate goals of improving organ perfusion and microcirculation for sustaining adequate tissue oxygenation. This review presents the (patho)physiological basis of hypovolemia, microcirculation, and tissue oxygenation and presents a literature review on the effects of plasma substitutes on microperfusion and oxygenation in the clinical setting.

METHODS

Literature review of the effects of fluid therapy on microcirculation and tissue oxygenation using PubMed search including original papers in English from 1988 to 2009.

RESULTS

We identified a total of 14 articles dealing with the effects of different crystalloids and colloids on organ perfusion, microcirculation, and tissue oxygenation in patients. The results are divergent, but there is a general trend that colloids are superior to crystalloids in improving organ perfusion, microcirculation, and tissue oxygenation. Due to the limited number of studies and different study conditions, a meta-analysis on the effects of the volume replacement strategies on microcirculation is not possible.

CONCLUSIONS

Improving the microcirculation by volume replacement appears to be a promising issue when treating the critically ill. The growing insights from animal experiments have to be translated into the clinical setting to identify the optimal fluid regimen for correcting hypovolemia. New techniques for monitoring microcirculation at the bedside might provide such endpoints, although these have to be validated also in the clinical setting. Whether improved microperfusion and tissue oxygenation by fluid therapy will also improve patient outcomes will have to be proven by future studies.

Fluids in septic shock: too much of a good thing?

In a recent issue of Critical Care, Brandt and colleagues report the effects of a 'liberal' fluid loading protocol compared to a more 'restrictive' protocol on hemodynamics and mortality in pigs in which septic shock had been induced. It appears that the former protocol was associated with higher mortality in spite of improved hemodynamics compared to the latter. The results of the paper are discussed here in view of the scope and mechanisms of these findings. With regard to fluid resuscitation, they indicate that too much of an otherwise good thing is harmful, even if overhydration and edema formation seem to have been prevented. They also do not exclude a specific toxic effect of the larger volumes of hydroxyethyl starch in the 'liberal' strategy. The precise nature of a toxic effect remains obscure, however, but may involve the kidneys.

HES 130/0.4 impairs haemostasis and stimulates pro-inflammatory blood platelet function

Introduction

Hydroxyethyl starch (HES) solutions are widely used for volume replacement therapy but are also known to compromise coagulation, impair renal function and increase long-term mortality. To test the hypotheses that HES 130/0.4 has fewer adverse effects than HES 200/0.5 and exerts anti-inflammatory properties, we compared the effects of HES 130/0.4, HES 200/0.5 and saline on in vitro haemostasis and pro-inflammatory platelet function.

Methods

Whole blood samples from healthy volunteers were mixed with 6% HES 130/0.4, 10% HES 200/0.5, or normal saline to achieve a final haemodilution rate of 10% or 40%. Haemostatic capacity was characterised by thromboelastography (ROTEM) and measurement for FXIIIa activity. Platelet activation and pro-inflammatory platelet functions were characterised by flow cytometry measuring the platelet activation marker CD62P and binding of fibrinogen to platelets as well as the formation of heterotypic platelet-leukocyte conjugates.

Results

Compared with saline, HES 130/0.4 dose-dependently impaired formation and firmness of the fibrin clot but did not affect the fibrin crosslinking activity of FXIIIa. At 40% but not at 10% haemodilution rate, HES 200/0.5 also increased platelet fibrinogen binding and both HES solutions increased expression of CD62P, the main receptor for platelet-leukocyte adhesion. HES 130/0.4 but not HES 200/0.5 increased formation of platelet-neutrophil conjugates and, to a lesser degree, platelet-monocyte conjugates.

Conclusions

Our data demonstrate that HES 130/0.4 has similar adverse effects as HES 200/0.5. In particular, both types of HES impair coagulation capacity and stimulate, rather than attenuate, pro-inflammatory platelet function.