History and current status of polymyxin B-immobilized fiber column for treatment of severe sepsis and septic shock

VASOPRESSOR REDUCTION EFFECT OF POLYMYXIN B HEMOPERFUSION IN PATIENTS WITH PERITONITIS-INDUCED SEPTIC SHOCK: A PROPENSITY SCORE-MATCHED ANALYSIS

ABSTRACT

Background : This study aimed to evaluate the effect of polymyxin B hemoperfusion (PMX-HP) in patients with peritonitis-induced septic shock who still required high-dose vasopressors after surgical source control. Methods : This retrospective study included adult patients admitted to the surgical intensive care unit (ICU) at Seoul National University Hospital between July 2014 and February 2021 who underwent major abdominal surgery to control the source of sepsis. Patients were divided into two groups based on whether PMX-HP was applied after surgery or not. The primary and secondary endpoints were the vasopressor reduction effect, and in-ICU mortality, respectively. Propensity score matching was performed to compare the vasopressor reduction effect. Results : A total of 338 patients met the inclusion criteria, of which 23 patients underwent PMX-HP postoperatively, whereas 315 patients did not during the study period. Serum norepinephrine concentration decreased over time regardless of whether PMX-HP was applied. However, it decreased more rapidly in the PMX-HP(+) group than in the PMX-HP(-) group. There were no significant differences in demographics including age, sex, body mass index, and most underlying comorbidities between the two groups. Risk factors for in-ICU mortality were identified by comparing patient characteristics and perioperative factors between the two groups using multivariate analysis. Conclusion : For patients with peritonitis-induced septic shock, PMX-HP rapidly reduces the requirement of vasopressors immediately after surgery but does not reduce in-ICU mortality. This effect could potentially accelerate recovery from shock, reduce sequelae from vasopressors, and ultimately improve quality of life after discharge.

Kinetics of Different Blood Biomarkers during Polymyxin-B Extracorporeal Hemoperfusion in Abdominal Sepsis

INTRODUCTION

Comparison of the marker kinetics procalcitonin, presepsin, and endotoxin during extracorporeal hemoperfusion with polymyxin-B adsorbing cartridge (PMX-HA) has never been described in abdominal sepsis. We aimed to compare the trend of three biomarkers in septic post-surgical abdominal patients in intensive care unit (ICU) treated with PMX-HA and their prognostic value.

METHODS

Ninety abdominal post-surgical patients were enrolled into different groups according to the evidence of postoperative sepsis or not. Non-septic patients admitted in the surgical ward were included in C group (control group). ICU septic shock patients with endotoxin levels <0.6 EAA receiving conventional therapy were addressed in S group and those with endotoxin levels ≥0.6 EAA receiving treatment with PMX-HA, besides conventional therapy, were included in SPB group. Presepsin, procalcitonin, endotoxin and other clinical data were recorded at 24 h (T0), 72 h (T1) and 7 days (T2) after surgery. Clinical follow-up was performed on day 30.

RESULTS

SPB group showed reduced levels of the three biomarkers on T2 versus T0 (p < 0.001); presepsin, procalcitonin and endotoxin levels decreased, respectively, by 25%, 11%, and 2% on T1 versus T0, and 40%, 41%, and 26% on T2 versus T0. All patients in C group, 73% of patients in SPB group versus 37% of patients in S group survived at follow-up. Moreover, procalcitonin had the highest predictive value for mortality at 30 days, followed by presepsin.

CONCLUSION

The present study showed the reliability of presepsin in monitoring PMX-HA treatment in septic shock patients. Procalcitonin showed better predicting power for the mortality riSsk.

The role of endotoxin in septic shock

Septic shock can be caused by a variety of mechanisms including direct effects of bacterial toxins such as endotoxin. Annually, approximately 5-7 million patients worldwide develop sepsis with very high endotoxin activity in the blood and more than half die. The term endotoxic septic shock has been used for these patients but it is important to emphasize that endotoxin may be a factor in all forms of septic shock including non-bacterial etiologies like COVID-19 since translocation of bacterial products is a common feature of septic shock. A pattern of organ failure including hepatic dysfunction, acute kidney injury and various forms of endothelial dysfunction ranging from disseminated intravascular coagulation to thrombotic microangiopathy characterize endotoxic septic shock. However, while characteristic, the clinical phenotype is not unique to patients with high endotoxin, and the diagnosis relies on the measurement of endotoxin activity in addition to clinical assessment. Therapies for endotoxic septic shock are limited with immune modulating therapies under investigation and extracorporeal blood purification still controversial in many parts of the world.

Targeting circulating high mobility group box-1 and histones by extracorporeal blood purification as an immunomodulation strategy against critical illnesses

Both high mobility group box-1 (HMGB1) and histones are major damage-associated molecular patterns (DAPMs) that mediate lethal systemic inflammation, activation of the complement and coagulation system, endothelial injury and multiple organ dysfunction syndrome in critical illnesses. Although accumulating evidence collectively shows that targeting HMGB1 or histones by their specific antibodies or inhibitors could significantly mitigate aberrant immune responses in multiple critically ill animal models, routine clinical use of such agents is still not recommended by any guideline. In contrast, extracorporeal blood purification, which has been widely used to replace dysfunctional organs and remove exogenous or endogenous toxins in intensive care units, may also exert an immunomodulatory effect by eliminating inflammatory mediators such as cytokines, endotoxin, HMGB1 and histones in patients with critical illnesses. In this review, we summarize the multiple immunopathological roles of HMGB1 and histones in mediating inflammation, immune thrombosis and organ dysfunction and discuss the rationale for the removal of these DAMPs using various hemofilters. The latest preclinical and clinical evidence for the use of extracorporeal blood purification to improve the clinical outcome of critically ill patients by targeting circulating HMGB1 and histones is also gathered.

Rationale for sequential extracorporeal therapy (SET) in sepsis

Sepsis and septic shock remain drivers for morbidity and mortality in critical illness. The clinical picture of patients presenting with these syndromes evolves rapidly and may be characterised by: (a) microbial host invasion, (b) establishment of an infection focus, (c) opsonisation of bacterial products (e.g. lipopolysaccharide), (d) recognition of pathogens resulting in an immune response, (e) cellular and humoral effects of circulating pathogen and pathogen products, (f) immunodysregulation and endocrine effects of cytokines, (g) endothelial and organ damage, and (h) organ crosstalk and multiple organ dysfunction. Each step may be a potential target for a specific therapeutic approach. At various stages, extracorporeal therapies may target circulating molecules for removal. In sequence, we could consider: (a) pathogen removal from the circulation with affinity binders and cartridges (specific), (b) circulating endotoxin removal by haemoperfusion with polymyxin B adsorbers (specific), (c) cytokine removal by haemoperfusion with sorbent cartridges or adsorbing membranes (non-specific), (d) extracorporeal organ support with different techniques for respiratory and cardiac support (CO₂ removal or extracorporeal membrane oxygenation), and renal support (haemofiltration, haemodialysis, or ultrafiltration). The sequence of events and the use of different techniques at different points for specific targets will likely require trials with endpoints other than mortality. Instead, the primary objectives should be to achieve the desired action by using extracorporeal therapy at a specific point.

Hemoperfusion in the intensive care unit

Multiple organ failure following a septic event derives from immune dysregulation. Many of the mediators of this process are humoral factors (cytokines), which could theoretically be cleared by direct adsorption through a process called hemoperfusion. Hemoperfusion through devices, which bind specific molecules like endotoxin or theoretically provide non-specific adsorption of pro-inflammatory mediators has been attempted and studied for several decades with variable results. More recently, technological evolution has led to the increasing application of adsorption due to more biocompatible and possibly more efficient biomaterials. As a result, new indications are developing in this field, and novel tools are available for clinical use. This narrative review will describe current knowledge regarding technical concepts, safety, and clinical results of hemoperfusion. Finally, it will focus on the most recent literature regarding adsorption applied in critically ill patients and their indications, including recent randomized controlled trials and future areas of investigation. Clinical trials for the assessment of efficacy of hemoperfusion in septic patients should apply the explanatory approach. This includes a highly selected homogenous patient population. Enrichment criteria such as applying genetic signature and molecular biomarkers allows the identification of subphenotypes of patients. The intervention must be delivered by a multidisciplinary team of trained personnel. The aim is to maximize the signals for efficacy and safety. In a homogenous cohort, confounding uncontrolled variables are less likely to exist. Trials with highly selected populations have a high internal validity but poor generalizability. The parallel design described in the figure is robust and usually is required by regulatory agencies for the approval of a new treatment. Allocation concealment and randomization are key to minimize bias such as confirmation bias, observer bias. The intervention should be delivered following a strict protocol. Deviations from the protocol might negatively influence the potential effects of the therapies. Surrogates such as cytokine measurement are adequate primary outcomes in phase 3 trials with small sample size because there is a higher likelihood of finding positive results concerning surrogate markers than in respect with clinical outcomes. Once a trial shows positive results concerning surrogate markers, a rationale for another phase 3 trial exploring clinical outcomes is built, justifying the allocation of financial sources to the intended trial.

The Supporting Role of Combined and Sequential Extracorporeal Blood Purification Therapies in COVID-19 Patients in Intensive Care Unit

Critical clinical forms of COVID-19 infection often include Acute Kidney Injury (AKI), requiring kidney replacement therapy (KRT) in up to 20% of patients, further worsening the outcome of the disease. No specific medical therapies are available for the treatment of COVID-19, while supportive care remains the standard treatment with the control of systemic inflammation playing a pivotal role, avoiding the disease progression and improving organ function. Extracorporeal blood purification (EBP) has been proposed for cytokines removal in sepsis and could be beneficial in COVID-19, preventing the cytokines release syndrome (CRS) and providing Extra-corporeal organ support (ECOS) in critical patients. Different EBP procedures for COVID-19 patients have been proposed including hemoperfusion (HP) on sorbent, continuous kidney replacement therapy (CRRT) with adsorbing capacity, or the use of high cut-off (HCO) membranes. Depending on the local experience, the multidisciplinary capabilities, the hardware, and the available devices, EBP can be combined sequentially or in parallel. The purpose of this paper is to illustrate how to perform EBPs, providing practical support to extracorporeal therapies in COVID-19 patients with AKI.

N6-methyladenosine (m6A) methyltransferase METTL3 regulates sepsis-induced myocardial injury through IGF2BP1/HDAC4 dependent manner

Recent studies have identified that N⁶-methyladenosine (m⁶A) extensively participates in the myocardial injury pathophysiological process. However, the role of m⁶A on sepsis-induced myocardial injury is still unclear. Here, we investigated the functions and mechanism of m⁶A methyltransferase METTL3 for septic myocardial injury. Results illustrated that the m⁶A modification level and METTL3 up-regulated in the lipopolysaccharide (LPS)-induced cardiomyocytes (H9C2 cells). Methylated RNA immunoprecipitation sequencing (MeRIP-Seq) revealed the m⁶A profile of the septic myocardial injury cellular model. Functionally, METTL3 knockdown repressed the inflammatory damage of cardiomyocytes induced by LPS. Mechanistically, we found that HDAC4 had remarkable m⁶A modification sites on its 3'-UTR genome, acting as the downstream target of METTL3. Besides, m⁶A reader IGF2BP1 recognized the m⁶A modification sites on HDAC4 mRNA and enhanced its RNA stability. In conclusion, the findings illustrated a role of METTL3/IGF2BP1/m⁶A/HDAC4 axis on sepsis-induced myocardial injury, which might provide novel therapeutic strategy for septic myocardial injury.

Retrospective Analysis of the Clinical Efficacy of Early Goal-Directed Therapy Combined with Meticulous Nursing Intervention in Patients with Posttraumatic Sepsis

Objective

To explore the intervention effect of early goal-directed therapy (EGDT) combined with meticulous nursing on patients with posttraumatic sepsis.

Methods

The data of 50 patients with posttraumatic sepsis undergoing EGDT in the emergency department of our hospital from January 2020 to December 2020 were retrospectively analyzed. According to different nursing methods, they were divided into control group (n = 25) with routine nursing measures and observation group (n = 25) with meticulous nursing measures. The application effect of the two nursing modes was scientifically evaluated.

Results

No statistical differences in general data were found between the two groups (P > 0.05). After 6 h of intervention, the circulatory function, oxygenation function, and renal function of both groups were better than those before intervention, and central venous pressure (CVP), mean arterial pressure (MAP), blood oxygen (PaO₂), oxygenation index (PaO₂/FiO₂), central venous oxygen saturation (ScvO₂), and urine volume in the observation group were notably higher than those in the control group (P < 0.05). The heart rate (HR), serum creatinine (SCr), and blood lactic acid in the observation group were notably lower than those in the control group (P < 0.05). The 28-day survival rate and quality of life after intervention in the observation group were notably higher than those in the control group, with obvious differences between the two groups (P < 0.05).

Conclusion

Meticulous nursing intervention for patients with posttraumatic sepsis undergoing EGDT can effectively improve the body's functional indexes, which is superior to the routine nursing in controlling the patients' condition, improving the survival rate and quality of life after intervention, and ensuring the clinical treatment effect. Therefore, it is worthy of promotion.

Membrane-disruptive peptides/peptidomimetics-based therapeutics: Promising systems to combat bacteria and cancer in the drug-resistant era

Membrane-disruptive peptides/peptidomimetics (MDPs) are antimicrobials or anticarcinogens that present a general killing mechanism through the physical disruption of cell membranes, in contrast to conventional chemotherapeutic drugs, which act on precise targets such as DNA or specific enzymes. Owing to their rapid action, broad-spectrum activity, and mechanisms of action that potentially hinder the development of resistance, MDPs have been increasingly considered as future therapeutics in the drug-resistant era. Recently, growing experimental evidence has demonstrated that MDPs can also be utilized as adjuvants to enhance the therapeutic effects of other agents. In this review, we evaluate the literature around the broad-spectrum antimicrobial properties and anticancer activity of MDPs, and summarize the current development and mechanisms of MDPs alone or in combination with other agents. Notably, this review highlights recent advances in the design of various MDP-based drug delivery systems that can improve the therapeutic effect of MDPs, minimize side effects, and promote the co-delivery of multiple chemotherapeutics, for more efficient antimicrobial and anticancer therapy.

The multifaceted nature of antimicrobial peptides: current synthetic chemistry approaches and future directions

Bacterial infections caused by 'superbugs' are increasing globally, and conventional antibiotics are becoming less effective against these bacteria, such that we risk entering a post-antibiotic era. In recent years, antimicrobial peptides (AMPs) have gained significant attention for their clinical potential as a new class of antibiotics to combat antimicrobial resistance. In this review, we discuss several facets of AMPs including their diversity, physicochemical properties, mechanisms of action, and effects of environmental factors on these features. This review outlines various chemical synthetic strategies that have been applied to develop novel AMPs, including chemical modifications of existing peptides, semi-synthesis, and computer-aided design. We will also highlight novel AMP structures, including hybrids, antimicrobial dendrimers and polypeptides, peptidomimetics, and AMP-drug conjugates and consider recent developments in their chemical synthesis.

Rescuing the Last-Line Polymyxins: Achievements and Challenges

Antibiotic resistance is a major global health challenge and, worryingly, several key Gram negative pathogens can become resistant to most currently available antibiotics. Polymyxins have been revived as a last-line therapeutic option for the treatment of infections caused by multidrug-resistant Gram negative bacteria, in particular Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacterales. Polymyxins were first discovered in the late 1940s but were abandoned soon after their approval in the late 1950s as a result of toxicities (e.g., nephrotoxicity) and the availability of "safer" antibiotics approved at that time. Therefore, knowledge on polymyxins had been scarce until recently, when enormous efforts have been made by several research teams around the world to elucidate the chemical, microbiological, pharmacokinetic/pharmacodynamic, and toxicological properties of polymyxins. One of the major achievements is the development of the first scientifically based dosage regimens for colistin that are crucial to ensure its safe and effective use in patients. Although the guideline has not been developed for polymyxin B, a large clinical trial is currently being conducted to optimize its clinical use. Importantly, several novel, safer polymyxin-like lipopeptides are developed to overcome the nephrotoxicity, poor efficacy against pulmonary infections, and narrow therapeutic windows of the currently used polymyxin B and colistin. This review discusses the latest achievements on polymyxins and highlights the major challenges ahead in optimizing their clinical use and discovering new-generation polymyxins. To save lives from the deadly infections caused by Gram negative "superbugs," every effort must be made to improve the clinical utility of the last-line polymyxins. SIGNIFICANCE STATEMENT: Antimicrobial resistance poses a significant threat to global health. The increasing prevalence of multidrug-resistant (MDR) bacterial infections has been highlighted by leading global health organizations and authorities. Polymyxins are a last-line defense against difficult-to-treat MDR Gram negative pathogens. Unfortunately, the pharmacological information on polymyxins was very limited until recently. This review provides a comprehensive overview on the major achievements and challenges in polymyxin pharmacology and clinical use and how the recent findings have been employed to improve clinical practice worldwide.

Treatment of Pyonephritis Complicated by Septic Shock Using Extracorporeal Device Polymyxin B-Hemoperfusion

Direct hemoperfusion using polymyxin B-immobilized fiber (PMX-DHP) is an established treatment method for septic shock caused by Gram-negative infections. We report one instance in which PMX-DHP therapy has been used successfully in a 33-year-old woman with septic shock from urosepsis. Although there is lack of recommendations in latest Surviving Sepsis Campaign Guidelines, evidence of PMX-DHP efficacy in this subset of patients is growing.

Ex vivo evaluation of the blood compatibility of mixed matrix haemodialysis membranes

The patients with end stage kidney disease need haemodialysis therapies, using an artificial kidney. Nevertheless, the current therapies cannot remove a broad range of uremic toxins compared to the natural kidney. Adsorption therapies, using sorbent-based columns, can improve the clearance of uremic toxins, but the sorbent particles often require polymeric coatings to improve their haemocompatibility leading to mass transfer limitations and to lowering of their performance. Earlier, we have developed a dual layer Mixed Matrix fiber Membrane (MMM) based on polyethersulfone/polyvinylpyrrolidone (PES/PVP) polymer blends. There, the sorbent activated carbon particles are embedded in the outer membrane layer for achieving higher removal whereas the inner blood contacting selective membrane layer should achieve optimal blood compatibility. In this work, we evaluate in detail the haemocompatibility of the MMM following the norm ISO 10993-4. We study two generations of MMM having different dimensions and transport characteristics; one with low flux and no albumin leakage and another with high flux but some albumin leakage. The results are compared to those of home-made PES/PVP single layer hollow fiber and to various control fibers already applied in the clinic. Our results show that the low flux MMM successfully avoids contact of blood with the activated carbon and has good haemocompatibility, comparable to membranes currently used in the clinic. STATEMENT OF SIGNIFICANCE: Haemodialysis is a life-sustaining extracorporeal treatment for renal disease, however a broad range of uremic toxins cannot still be removed. In our previous works we showed that a double layer Mixed Matrix Membrane (MMM) composed of polyethersulfone/polyvinylpyrrolidone and activated carbon can achieve higher removal of uremic toxics compared to commercial haemodialysers. In this work we evaluate the haemocompatibility profile of the MMM in order to facilitate its clinical implementation. The lumen particle-free layer of the MMM successfully avoids the contact of blood with the poorly blood-compatible activated carbon. Moreover, thanks to the high amount of polyvinylpyrrolidone and to the smoothness of the lumen layer, the MMM has very good haemocompatibility, comparable to membranes currently used in the clinic.

Early use of endotoxin absorption by oXiris in abdominal septic shock: A case report

RATIONALE

Septic shock leads to multiple organ failure and increases mortality rate. We reported a critical patient with abdominal septic shock, which was the first case successfully treated with continuous renal replacement therapy (CRRT) and a newly designed endotoxin removal device oXiris in mainland China.

PATIENT CONCERNS

A 51-year-old man developed gastric ulcer perforation after resection of a benign peritoneal tumor and had a second abdominal surgery. His blood pressure decreased to 70/40 mm Hg with oliguria, requiring large doses of noradrenaline and intravenous fluid for resuscitation. The abdominal cavity was not sutured after the second open surgery due to severe abdominal infection and distention. His leukocyte count was over 30109/L, while the blood lactic acid was 12.5 mmol/L and procalcitonin (PCT) was >100 ng/mL.

DIAGNOSIS

Since the bacterial culture of peritoneal exudate showed positive with Enterobacter aerogenes and Pseudomonas aeruginosa after the second surgery, and the patient had severe low blood pressure, hyoxemia and oliguria, combined with the laboratory tests results, he was diagnosed with Gram-negative related septic shock, acute kidney injury, and multiple organ dysfunction.

INTERVENTIONS

CRRT with oXiris membrane was performed for 80hours and followed by AN69 ST membranes during the subsequent 27 days. Antibiotics together with other medical treatment were applied to the patient in the meantime.

OUTCOMES

At the end of 80 hours treatment with oXiris, PCT of the patient had decreased to 14.52 ng/mL and lactic acid decreased to 4.2 mmol/L. The total sequential organ failure assessment (SOFA) score decreased from 15 to 11. Urine output steadily increased to 250 mL/h, and vital signs and blood pressure were stable without noradrenaline. At the end of the 27 days of conventional CRRT, his kidney function had completely recovered with a total sequential organ failure assessment score (SOFA score) of 6.

LESSONS

oXiris, with its enhanced endotoxin adsorption, appeared to accelerate improvement in organ dysfunction and ultimate survival in our patient. In critical patients with abdominal septic shock, oXiris is an important adjunctive consideration to supplement definitive source control and antimicrobial therapy.

A nanotrap improves survival in severe sepsis by attenuating hyperinflammation

Targeting single mediators has failed to reduce the mortality of sepsis. We developed a telodendrimer (TD) nanotrap (NT) to capture various biomolecules via multivalent, hybrid and synergistic interactions. Here, we report that the immobilization of TD-NTs in size-exclusive hydrogel resins simultaneously adsorbs septic molecules, e.g. lipopolysaccharides (LPS), cytokines and damage- or pathogen-associated molecular patterns (DAMPs/PAMPs) from blood with high efficiency (92-99%). Distinct surface charges displayed on the majority of pro-inflammatory cytokines (negative) and anti-inflammatory cytokines (positive) allow for the selective capture via TD NTs with different charge moieties. The efficacy of NT therapies in murine sepsis is both time-dependent and charge-dependent. The combination of the optimized NT therapy with a moderate antibiotic treatment results in a 100% survival in severe septic mice by controlling both infection and hyperinflammation, whereas survival are only 50-60% with the individual therapies. Cytokine analysis, inflammatory gene activation and tissue histopathology strongly support the survival benefits of treatments.

The effect of direct hemoperfusion with polymyxin B immobilized cartridge on meropenem in critically ill patients requiring renal support

PURPOSE

To evaluate the effect of direct hemoperfusion with polymyxin B immobilized cartridge (DHP-PMX) on meropenem pharmacokinetics in critically ill patients with sepsis requiring continuous venovenous hemofiltration (CVVH).

MATERIAL AND METHODS

After intravenous infusion of 1 g meropenem over 3 h repeated every 8 h for at least 3 doses, 2 serial blood and ultrafiltration fluid samples were collected: one over a dose interval of meropenem with DHP-PMX therapy; and the other on the following day over a dose interval of meropenem with no DHP-PMX therapy. Meropenem concentrations were measured by high performance liquid chromatography. Pharmacokinetic parameters of meropenem and extraction ratio of DHP-PMX were calculated.

RESULTS

Mean AUC_0-8 of meropenem on DHP-PMX day was comparable to that of the DHP-PMX free day (285.2 ± 138.2 vs 297.8 ± 130.2 mg ∗ h/L; paired t-test, p = .618). No statistical significance of peak and trough concentrations, volume of distribution, sieving coefficient, or half-life were found. Extraction ratio of DHP-PMX on meropenem was 0 [0-0.03] and clearance by DHP-PMX was 0.04 [0-0.2] L/h which was not considered clinically significant.

CONCLUSIONS

No significant effect of DHP-PMX on meropenem pharmacokinetics was observed among severe sepsis/septic shock patients during CVVH treatment.

TRIAL REGISTRATION

Clinical Trial Registry detail: NCT registry: 02413541 (First registered March 3, 2015, last update October 16, 2017).