Do circulating cytokines really matter in sepsis?

Angiotensin AT2 Receptor is Anti-inflammatory and Reno-Protective in Lipopolysaccharide Mice Model: Role of IL-10

Acute kidney injury (AKI) due to endotoxemic insult is predicted by the infiltration of neutrophils, monocytes and macrophages, and the release of pro-and anti-inflammatory cytokines to the site of injury. Earlier, we have demonstrated the role of angiotensin-II type 2 receptor (AT2R) stimulation in reno-protection in lipopolysaccharide (LPS)-induced inflammation and AKI in C57BL6/NHsd mice. Moreover, AT2R activation has been shown to increase the anti-inflammatory cytokine interleukin-10 (IL-10), its role in AT2R-mediated anti-inflammation and reno-protection is unknown. To address this question, in the present study mice were treated with the AT2R agonist C21 (0.3 mg/kg, intraperitoneally), LPS (5 mg/kg, intraperitoneally), or LPS with C21 pre-treatment with or without neutralizing IL-10 antibody. Treatment with C21 alone caused an increase in the plasma and kidney IL-10 levels, which peaks at 2-h, and returned to baseline at 6-h. The C21-induced IL-10 increase was blocked by the AT2R antagonist PD123319 suggesting AT2R's involvement. LPS treatment caused a profound increase in tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) and the LPS-induced increase in these cytokines was attenuated by the C21 pre-treatment (1-h prior LPS) both in the plasma and kidney. Neutralizing IL-10 antibody treatment abrogated the C21-lowering of TNF-α and IL-6 in the kidney but not in the plasma. Similar results as related to the cytokines profiles in all the groups were also observed in the heart and spleen. The alteration in early cytokine profile prompted us to measure the markers of renal function (blood urea nitogen and urinary creatinine) in order to analyze the effect of IL-10 neutralization. However, it was too early to observe changes in renal function. Therefore, the renal function and injury markers were again measured at 24 h. Treatment with neutralizing IL-10 antibody attenuated the C21-mediated improvement in indices of the kidney function, but not the biomarkers of renal injury (kidney injury molecule-1 and neutrophil-gelatinase associated lipocalin). Collectively, our data suggest that the involvement of IL-10 in AT2R-mediated anti-inflammation and reno-protection against LPS is complex, mediating the renal cytokine profile and kidney filtration function, but not the plasma cytokine profile and renal injury markers.

The Big Bang of Hemofiltration: The Beginning of a New Era in the Third Millennium for Extra-Corporeal Blood Purification!

Since the last decade, hemofiltration and especially high volume hemofiltration has rapidly evolved from a somewhat experimental treatment towards a potentially effective “adjunctive” therapy in severe septic shock and especially refractory or catecholamine resistant hypodynamic septic shock. Nevertheless, this approach lacks prospective randomized studies (PRT'S) evaluating the critical role of early hemofiltration in sepsis. An important step forward which could be called the “big bang” in term of hemofiltration was the publication of a PRT in patients with acute renal failure (ARF) (1). Before this study (2), nobody believed that hemofiltration could change the survival rate in intensive care. Since that big bang, many physicians consider that hemofiltration at a certain dose can change the survival rate in intensive care. So the world of hemofiltration in ICU is not a definitive world, it is still in expansion. Indeed, we now have to try to define what will be the exact dose we need in septic acute renal failure. This dose might well be “higher” than 35 ml/kg/hour in the septic acute renal failure “group” as suggested by many studies (2–5). At present, it is the issue of continuous dose of high volume hemofiltration that has to be tested in future randomized studies. Since the Vicenza study (2) has shown that 35 ml/kg/h is the best dose in terms of survival, dealing with non septic acute renal failure in ICU, several studies from different groups have shown that, in septic acute renal failure, a higher dose might correlate with better survival. This has also been shown in some way by the study of the “Vicenza group” but not with a statistically significant value (2). New PRT'S have just started in Europe like the IVOIRE study (hIgh VOlume in Intensive caRE) (6) and the RENAL study. Another large study is looking more basically at dose in non septic acute renal failure in Australasia and is led by the group of Rinaldo Bellomo in Melbourne (7) as well as the ATN study (8) led by Palevsky and colleagues in the USA, also testing the importance of dose in the treatment for ARF. Nevertheless, “early goal-directed hemofiltration therapy” like early goal directed therapy (9) has to be studied in our critical ill patients. Regarding this issue, fewer studies, mainly retrospective exist, but again the IVOIRE study (6) will address this issue by studying septic patients with acute renal injury according to the Rifle classification (10). So, this review focuses on the early application and on the adequate dose of continuous high volume hemofiltration in septic shock in order to improve not only hemodynamics, but survival in this very severely ill cohort of patients. This could well be called the “big bang of hemofiltration” as one could never have anticipated that an adequate dose of hemofiltration could markedly influence the survival rate of ICU-septic acute renal failure patients. On top of the use of early and adequate dose of hemofiltration in sepsis, a higher dose could also provide better renal recovery rate and reduce the risk of associate chronic dialysis in these patients. Furthermore, this paper also reviews “brand” new theories regarding the rationale for hemofiltration in sepsis. Finally, this paper also addresses the so-called negative studies as well anticipated side effects.

Screening cytokine/chemokine profiles in serum and organs from an endotoxic shock mouse model by LiquiChip

Studying the cytokine profiles in animal models or patients with sepsis provides an experimental basis for the identification of diagnostic biomarkers and therapeutic targets. In this study, we used a liquid protein chip (LiquiChip), also known as flexible multi-analyte profiling technology, to perform quantitative analyses of several cytokines and chemokines (e.g., IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, TNF-α, IFN-γ, granulocyte-macrophage colony-stimulating factor, keratinocyte chemoattractant, monocyte chemoattractant protein, monokine induced by gamma interferon, IFN-γ-inducible protein 10, and macrophage inflammatory protein 1 alpha). The levels of these cytokines and chemokines were determined both in the blood and in tissues, including the lung, liver, heart, kidney, spleen, brain, stomach, intestine and muscle, of mice challenged with LPS. Our data showed variable production levels of LPS-induced cytokines in different mouse organs, and the cytokine in the blood did not correlate with those in the organs. We also showed that the levels of most cytokines peaked within 1 to 6 h and decreased rapidly afterward. A variety of inflammatory cytokines might be related to the damage in different organs during septic shock. Our data also suggest that the spleen might be an important target organ in the development of systemic inflammatory response syndrome and sepsis.

[Online hemodiafiltration: Practical aspects, safety and efficacy]

Purification of high molecular uremic toxins by conventional hemodialysis is limited. It remains associated with a high morbidity and excessively high mortality. Online hemodiafiltration using a high permeability hemodiafilter, an ultrapure dialysate, and which tends to maximize substitution volumes, provides a high efficiency and low bio-incompatibility renal supplementation. Regular use of online hemodiafiltration is associated with reduced morbidity (reduction of intradialytic hypotension episodes, improved blood pressure control, reduced inflammatory profile, better anemia correction and prevention of β₂-microglobulin-associated amyloidosis). Recently, several cohort studies have shown that hemodiafiltration with high substitution volume was associated with a significant reduction in mortality. Randomized studies have been conducted in Europe to confirm these facts. The high safety of online hemodiafiltration has been confirmed in clinical practice by prospective studies. Online hemodiafiltration has reached its full maturity phase and is expected to represent the new standard of renal replacement therapy.

Hemodiafiltration: Technical and Clinical Issues

Hemodiafiltration (HDF) seems to represent the gold standard in the field of replacement of renal function by dialysis. High convective fluxes have been correlated with better clinical outcomes. Sometimes, however, there are technical barriers to the achievement of high blood flows adequate to perform effective convective therapies. In spite of optimized procedures, the progressive increase in transmembrane pressure (TMP), the blood viscosity due to hemoconcentration and blood path resistance sometimes becomes inevitable. We propose two possible solutions that can be operated automatically via specific software in the dialysis machine: predilution on demand and backflush on demand. Predilution on demand consists in an automatic feedback of the machine, diverting part of the filtered dialysate into a predilution mode with an infusion of 200 ml in 30 s while the ultrafiltration pump stops. This produces a sudden hemodilution with a return of the parameters to acceptable values. The performance of the filter improves, and the pressure alterations are mitigated. Backflush on demand consists in an automatic feedback of the machine triggered by the TMP control, producing a positive pressure in the dialysate compartment due to a stop of filtration and rapid infusion of at least 100 ml of ultrapure dialysate into the hollow fiber. This not only produces a significant hemodilution, but also backflushes the membrane pores detaching protein layers and improving membrane permeability. These are two examples of how technology will permit to overcome technical barriers to a widespread diffusion of HDF and adequate convective dose delivery.

Clinical review: Optimal dose of continuous renal replacement therapy in acute kidney injury

Continuous renal replacement therapy (CRRT) is the preferred treatment for acute kidney injury in intensive care units (ICUs) throughout much of the world. Despite the widespread use of CRRT, controversy and center-specific practice variation in the clinical application of CRRT continue. In particular, whereas two single-center studies have suggested survival benefit from delivery of higher-intensity CRRT to patients with acute kidney injury in the ICU, other studies have been inconsistent in their results. Now, however, two large multi-center randomized controlled trials - the Veterans Affairs/National Institutes of Health Acute Renal Failure Trial Network (ATN) study and the Randomized Evaluation of Normal versus Augmented Level (RENAL) Replacement Therapy Study - have provided level 1 evidence that effluent flow rates above 25 mL/kg per hour do not improve outcomes in patients in the ICU. In this review, we discuss the concept of dose of CRRT, its relationship with clinical outcomes, and what target optimal dose of CRRT should be pursued in light of the high-quality evidence now available.

Device for continuous extracorporeal blood purification using target-specific metal nanomagnets

BACKGROUND

The present work illustrates how magnetic separation-based blood purification using ultra-strong iron nanomagnets can be implemented into an extracorporeal blood purification circuit. By this promising technique, today's blood purification may be extended to specifically filter high-molecular compounds without being limited by filter cut-offs or column surface saturation.

METHODS

Blood spiked with digoxin (small molecule drug) and interleukin-1β (inflammatory protein) was circulated ex vivo through a device composed of approved blood transfusion lines. Target-specific nanomagnets were continuously injected and subsequently recovered with the aid of a magnetic separator before recirculating the blood.

RESULTS

Magnetic blood purification was successfully carried out under flow conditions: already in single-pass experiments, removal efficiencies reached values of 75 and 40% for digoxin and interleukin-1β, respectively. Circulating 0.5 L of digoxin-intoxicated blood in a closed loop, digoxin concentration was decreased from initially toxic to therapeutic concentrations within 30 min and purification extents of 90% were achieved after 1.5 h.

CONCLUSIONS

Magnetic separation can be successfully implemented into an extracorporeal blood purification device. Simultaneous and specific filtering of high-molecular compounds may offer promising new therapeutic tools for the future treatment of complex diseases, such as sepsis and autoimmune disorders.

[Coupled plasma filtration adsorption: rationale and perspectives in septic shock]

PURPOSE

Septic shock is the leading cause of multiple organ failure and mortality in intensive care units. This condition seems to be related to an overproduction of both pro- and anti-inflammatory mediators, leading to an immunological dysfunction. Therapeutic strategies aimed at reducing blood and tissue concentrations of these mediators have been developed. One of these techniques, based on extra-renal filtration, is called "coupled plasma filtration and adsorption".

SOURCE

English and French language articles published between 1984 and 2008 were identified through a computerized Medline search. Keywords and MeSH terms used were: "coupled plasmafiltration", "coupled plasma filtration", "adsorption", "blood purification", "cytokines", "hemofiltration", "sepsis". Relevant publications were retrieved and scanned for additional sources. Nine publications were found.

PRINCIPAL FINDINGS

Coupled plasma filtration adsorption is an extra-corporeal treatment, based on non-specific cytokine adsorption on a specially designed resin cartridge, coupled with hemofiltration. Experimental studies and the first clinical trials have shown interesting results regarding hemodynamics and respiratory parameters. However, these trials failed to demonstrate any improvement in outcome.

CONCLUSION

Additional evidence is needed to clarify the role of this blood purification technique for the treatment of septic shock.

Biomarker and drug-target discovery using proteomics in a new rat model of sepsis-induced acute renal failure

Sepsis is one of the common causes of acute renal failure (ARF). The objective of this study was to identify new biomarkers and therapeutic targets. We present a new rat model of sepsis-induced ARF based on cecal ligation and puncture (CLP). We used this model to find urinary proteins which may be potential biomarkers and/or drug targets. Aged rats were treated with fluids and antibiotics after CLP. Urinary proteins from septic rats without ARF and urinary proteins from septic rats with ARF were compared by difference in-gel electrophoresis (DIGE). CLP surgery elevated interleukin (IL)-6 and IL-10 serum cytokines and blood nitrite compared with sham-operated rats. However, there was a range of serum creatinine values at 24 h (0.4-2.3 mg/dl) and only 24% developed ARF. Histology confirmed renal injury in these rats. Forty-nine percent of rats did not develop ARF. Rats without ARF also had less liver injury. The mortality rate at 24 h was 27% but was increased by housing the post-surgery rats in metabolic cages. Creatinine clearance and urine output 2-8 h after CLP was significantly reduced in rats which died within 24 h. Using DIGE we identified changes in a number of urinary proteins including albumin, brush-border enzymes (e.g., meprin-1-alpha) and serine protease inhibitors. The meprin-1-alpha inhibitor actinonin prevented ARF in aged mice. In summary, we describe a new rat model of sepsis-induced ARF which has a heterogeneous response similar to humans. This model allowed us to use DIGE to find changes in urinary proteins and this approach identified a potential biomarker and drug target - meprin-1-alpha.

Overview of clinical studies in hemodiafiltration: what do we need now ?

Despite several technical advances in dialysis treatment modalities and a better patient care management including correction of anemia, suppression of secondary hyperparathyroidism, lipid and oxidative stress profiles improvement, the morbidity and the mortality of dialysis patients still remain still elevated. Recent prospective interventional trials in hemodialysis (HEMO study and 4D study) were not very conclusive in showing any significant improvement in dialysis patient outcomes. High-efficiency convective therapies, such as online hemodiafiltration (HDF), are claimed to be superior to conventional diffusive hemodialysis (HD) in improving the dialysis efficacy and in reducing intradialytic morbidity and all-cause and cardiovascular mortality in dialysis patients. The aim of this report was, first, to review the evidence-based facts tending to prove the superiority of HDF vs. HD in terms of efficacy and tolerance, and, second, to analyze the needs to prove the clinical superiority of HDF in terms of reducing morbidity and all-cause mortality of dialysis patients. A systematic review of studies comparing HDF and HD has been performed in the microbiological safety of online production, the solute removal capacity of small and medium-size uremic toxins, and its implication in the reduction of the bioactive dialysis system vs. patient interaction. Major planned randomized international studies comparing HDF and HD in terms of morbidity and mortality have been reviewed. To conclude, it is thought that these long-term prospective randomized trials will clarify on a scientific evidence-based level the putative beneficial role of high-efficiency HDF modalities on dialysis patient outcomes.

Quo vadis haemapheresis. Current developments in haemapheresis

The techniques of haemapheresis originated in the development of centrifugal devices separating cells from plasma and later on plasma from cells. Subsequently membrane filtration was developed allowing for plasma-cell separation. The unspecificity of therapeutic plasma exchange led to the development of secondary plasma separation technologies being specific, semi-selective or selective such as adsorption, filtration or precipitation. In contrast on-line differential separation of cells is still under development. Whereas erythrocytapheresis, granulocytapheresis, lymphocytapheresis and stem cell apheresis are technically advanced, monocytapheresis may need further improvement. Also, indications such as erythrocytapheresis for the treatment of polycythaemia vera or photopheresis though being clinically effective and of considerable importance for an appropriate disease control are to some extent under debate as being either too costly or without sufficient understanding of the mechanism. Other forms of cell therapy are under development. Rheohaemapheresis as the most advanced technology of extracorporeal haemorheotherapy is a rapidly developing approach contributing to the treatment of microcirculatory diseases and tissue repair. Whereas the control of a considerable number of (auto-) antibody mediated diseases is beyond discussion, the indication of apheresis therapy for immune complex mediated diseases is quite often still under debate. Detoxification for artificial liver support advanced considerably during the last years, whereas conclusions on the efficacy of septicaemia treatment are debatable indeed. LDL-apheresis initiated in 1981 as immune apheresis is well established since 24 years, other semi-selective or unspecific procedures, allowing for the elimination of LDL-cholesterol among other plasma components are also being used. Correspondingly Lp(a) apheresis is available as a specific, highly efficient elimination procedure superior to techniques which also eliminate Lp(a). Quality control systems, more economical technologies as for instance by increasing automation, influencing the over-interpretation of evidence based medicine especially in patients with rare diseases without treatment alternative, more insight into the need of controlled clinical trials or alternatively improved diagnostic procedures are among others tools ways to expand the application of haemapheresis so far applied in cardiology, dermatology, haematology, immunology, nephrology, neurology, ophthalmology, otology, paediatrics, rheumatology, surgery and transfusion medicine.

High volume hemofiltration (HVHF) in sepsis: a comprehensive review of rationale, clinical applicability, potential indications and recommendations for future research

HVHF can be still seen as a potent powerful immunomodulatory treatment in sepsis. Pleiotropical properties of HVHF give this treatment the possibility to affect not only SIRS but also cardiovascular compounds, clotting and post septic-insult immunoparalysis. By this multimodal approach, HVHF can alter the sepsis network through many targets. The crucial relationship between immunological changes, hemodynamics and survival must be found in future prospective randomised studies. Circulatory cytokines are no longer valuable players except for catecholamine-resistant septic shock. Definitions are of upmost value as ultrafiltrate volume has been correlated in terms of response and survival with the type of disease (sepsis or not) and severity (catecholamine-resistant shock or not). This latter condition can be seen as the best indication for HVHF and probably even more for very high volume hemofiltration (VHVHF). More studies are needed to clarify the role of HVHF in hyperdynamic septic shock (with or without acute renal failure), sepsis and SIRS. They can be seen as potential indications up to now. Possible interferences with activated protein C deserve more attention as both treatments can be given sequentially in the same septic patient or even concomitantly.

Cytometric bead assay of cytokines in sepsis: A clinical evaluation

BACKGROUND

The clinical relevancy of an attractive new multiparametric method, cytometric beads assay (CBA), was evaluated for the monitoring of cytokines in sepsis.

METHODS

A total of 52 samples (26 patients) were simultaneously tested by CBA and chemiluminescence (IL-6, IL-8, IL-1beta, and TNFalpha) or ELISA (IL-10, IL-12 p40, IL-12 p70, and soluble TNFalpha-RI).

RESULTS

CBA standard curves were linear from 20-5,000 ng/L except for IL-1beta (40-5,000 ng/L). IL-6 and IL-8 were detected in 41 and 48 samples (44-5,000 ng/L and 22-5,000 ng/L), respectively, and out of range in six samples. IL-10 and IL-1beta were detected in 14 and 15 samples (21-1,548 ng/L and 29-582 ng/L), respectively. TNFalpha was rarely detected, and IL-12 p70 was never detected. Accuracy and repeatability were good (CV for IL-6 was 2.1-8.7%; for IL-8 3.7-5.3%; for IL-10 2.5-9.1%; for IL-12 5.2-6.5%; for IL-1 beta 4-12%; and for TNFalpha 3-19.3%). Reproducibility of four standard curves and 20 samples (-1.1 to +1.03%) was excellent between tests done at two- to six-week intervals. CBA values were correlated (r2 > 0.89; P < 0.001) with our reference methods, but were lower on CBA (TNFalpha 45% +/- 8; IL-6 49% +/- 7), probably due to interactions with patients' serum, as confirmed by spiking diluted standards in one patient's serum with end stage renal failure and high levels of TNF soluble receptor (i.e., TNFalpha levels 34 and 21%).

CONCLUSIONS

Finally, these results suggest that IL-6, IL-8, IL-1beta, and Il-10 are clinically promising for sepsis evaluation. However, sensitivity of TNFalpha has to be improved and IL-12 p70 should be replaced with more relevant parameters such as TNF-R, procalcitonin, or neopterin.

Higher renal replacement therapy dose delivery influences on drug therapy

Higher doses of renal replacement therapy have profound effects on pharmacotherapy, yet little research has been conducted in this area. High-volume renal replacement therapies influence both the pharmacokinetic and the pharmacodynamic profiles of all drugs administered to these critically ill patients. Intermittent high-dose "hybrid" hemodialysis therapies remove drugs to a much different degree than standard thrice-weekly hemodialysis, yet pharmacokinetic studies have not been performed in patients receiving these therapies. High-volume continuous renal replacement therapies offer dosing challenges not seen with standard low-dose therapies. This article describes the pharmacokinetic and pharmacodynamic issues presented by high-volume renal replacement therapies. Given the importance that pharmacotherapy has on optimal patient outcomes, a better understanding of the influence that high-volume renal replacement therapy has on drugs is essential if these high volume therapies are to be used successfully in the intensive care unit.