The Rationale and Current Status of Endotoxin Adsorption in the Treatment of Septic Shock

Recombinant T7 RNA polymerase production using ClearColi BL21(DE3) and animal-free media for in vitro transcription

In vitro transcription (IVT) using T7 RNA polymerase (RNAP) is integral to RNA research, yet producing this enzyme in E. coli presents challenges regarding endotoxins and animal-sourced toxins. This study demonstrates the viable production and characterization of T7 RNAP using ClearColi BL21(DE3) (an endotoxin-free E. coli strain) and animal-free media. Compared to BL21(DE3) with animal-free medium, soluble T7 RNAP expression is ~50% lower in ClearColi BL21(DE3). Optimal soluble T7 RNAP expression in flask fermentation is achieved through the design of experiments (DoE). Specification and functional testing showed that the endotoxin-free T7 RNAP has comparable activity to conventional T7 RNAP. After Ni-NTA purification, endotoxin levels were approximately 109-fold lower than T7 RNAP from BL21(DE3) with animal-free medium. Furthermore, a full factorial DoE created an optimal IVT system that maximized mRNA yield from the endotoxin-free and animal-free T7 RNAP. This work addresses critical challenges in recombinant T7 RNAP production through innovative host and medium combinations, avoided endotoxin risks and animal-derived toxins. Together with an optimized IVT reaction system, this study represents a significant advance for safe and reliable reagent manufacturing and RNA therapeutics. KEY POINTS: • Optimized IVT system maximizes mRNA yields, enabling the synthesis of long RNAs. • Novel production method yields endotoxin-free and animal-free T7 RNAP. • The T7 RNAP has equivalent specifications and function to conventional T7 RNAP.

Nanoemulsion is an effective antimicrobial for methicillin-resistant Staphylococcus aureus in infected swine skin burn wounds

Burns are one of the most common injuries in both civilian and combat settings and are difficult to treat. This is particularly true when the wounds are infected with antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). A new generation of safe, broadly effective, and easily applied anti-infection agents is needed to successfully prevent and treat infections. Nanoemulsions (NEs) are nanometer-sized particles with a positively charged surfactant at their oil-water interface. In the current study, we further investigated antimicrobial NEs as a treatment to address burn wounds infected by MRSA. Specifically, using a porcine skin model, we infected partial thickness thermal burn wounds with MRSA and then treated it with the nanoemulsion formulation (NB-201) or placebo controls. Bacterial viability after treatment was determined, and inflammation indexes in wounds were scored by histopathology. Topical treatment of infected wounds with NB-201 resulted in reduced colony-forming units (CFUs) compared to placebo treatment. In addition, NB-201 was effective in significantly alleviating inflammation in the treated wounds and promoting wound healing. These results indicate that NB-201 is a promising new agent to treat skin burn wounds infected with MRSA.

IMPORTANCE

The findings of this study are focused on therapeutic applications of nanotechnology. In the current study, we demonstrated that a nanoemulsion formulation could effectively kill methicillin-resistant Staphylococcus aureus (MRSA) infection in porcine skin burn wounds. Infection of MRSA in burn wound is a common threat to public health and is usually difficult to treat due to limited therapies available. NB-201 was effective in significantly alleviating inflammation in the treated wounds and promoting wound healing. Therefore, the finding of this study has a great potential to make this formulation a novel antimicrobial agent against MRSA.

Factors Promoting Lipopolysaccharide Uptake by Synthetic Lipid Droplets

Lipoproteins are essential in removing lipopolysaccharide (LPS) from blood during bacterial inflammation. The physicochemical properties of lipoproteins and environmental factors can impact LPS uptake. In this work, synthetic lipid droplets containing triglycerides, cholesterols, and phospholipids, were prepared to mimic lipoproteins. The physicochemical properties of these lipid droplets, such as charges, sizes, and lipid compositions, were altered to understand the underlying factors affecting LPS uptake. The amphiphilic LPS could spontaneously adsorb on the surface of lipid droplets without lipopolysaccharide binding protein (LBP); however, the presence of LBP can increase LPS uptake. The positively charged lipid droplets also enhance the uptake of negatively charged LPS. Most interestingly, the LPS uptake highly depends on the concentrations of Ca2+ near the physiological conditions, but the impact of Mg2+ ions was not significant. The increase of Ca2+ ions can improve LPS uptake by lipid droplets; this result suggested that Ca2+ may play an essential role in LPS clearance. Since septic shock patients typically suffer from hypocalcemia and low levels of lipoproteins, the supplementation of Ca2+ ions along with synthetic lipoproteins may be a potential treatment for severe sepsis.

Flavonoids in mitigating the adverse effects of canine endotoxemia

In dogs, chronic enteropathies, and impaired gut integrity, as well as microbiome imbalances, are a major problem. These conditions may represent a continuous low endotoxin load, which may result in the development of diseases that are attributable to chronic inflammation. Flavonoids are polyphenolic plant compounds with numerous beneficial properties such as antioxidant, anti-inflammatory and antimicrobial effects. For our experiments, we isolated primary white blood cells (peripheral blood mononuclear cells and polymorphonuclear leukocytes) from healthy dogs and induced inflammation and oxidative stress with Escherichia coli and Salmonella enterica serovar Enteritidis lipopolysaccharide (LPS). In parallel, we treated the cell cultures with various flavonoids luteolin, quercetin and grape seed extract oligomeric proanthocyanidins (GSOP) alone and also in combination with LPS treatments. Then, changes in viability, reactive oxygen species (ROS) and tumor necrosis factor alpha (TNF-α) levels were measured in response to treatment with quercetin, luteolin and GSOP at 25 and 50 μg/mL concentrations. We found that ROS levels were significantly lower in groups which were treated by flavonoid and LPS at the same time compared to LPS-treated groups, whereas TNF-α levels were significantly reduced only by luteolin and quercetin treatment. In contrast, treatment with lower concentrations of GSOP caused an increase in TNF-α levels, while higher concentrations caused a significant decrease. These results suggest that the use of quercetin, luteolin and GSOP may be helpful in the management of chronic intestinal diseases in dogs with reduced intestinal barrier integrity or altered microbiome composition, or in the mitigation of chronic inflammatory processes maintained by endotoxemia. Further in vitro and in vivo studies are needed before clinical use.

Melatonin: A potential protective multifaceted force for sepsis-induced cardiomyopathy

Sepsis is a life-threatening condition manifested by organ dysfunction caused by a dysregulated host response to infection. Lung, brain, liver, kidney, and heart are among the affected organs. Sepsis-induced cardiomyopathy is a common cause of death among septic patients. Sepsis-induced cardiomyopathy is characterized by an acute and reversible significant decline in biventricular both systolic and diastolic function. This is accompanied by left ventricular dilatation. The pathogenesis underlying sepsis-induced cardiomyopathy is multifactorial. Hence, targeting an individual pathway may not be effective in halting the extensive dysregulated immune response. Despite major advances in sepsis management strategies, no effective pharmacological strategies have been shown to treat or even reverse sepsis-induced cardiomyopathy. Melatonin, namely, N-acetyl-5-methoxytryptamine, is synthesized in the pineal gland of mammals and can also be produced in many cells and tissues. Melatonin has cardioprotective, neuroprotective, and anti-tumor activity. Several literature reviews have explored the role of melatonin in preventing sepsis-induced organ failure. Melatonin was found to act on different pathways that are involved in the pathogenesis of sepsis-induced cardiomyopathy. Through its antimicrobial, anti-inflammatory, and antioxidant activity, it offers a potential role in sepsis-induced cardiomyopathy. Its antioxidant activity is through free radical scavenging against reactive oxygen and nitrogen species and modulating the expression and activity of antioxidant enzymes. Melatonin anti-inflammatory activities control the overactive immune system and mitigate cytokine storm. Also, it mitigates mitochondrial dysfunction, a major mechanism involved in sepsis-induced cardiomyopathy, and thus controls apoptosis. Therefore, this review discusses melatonin as a promising drug for the management of sepsis-induced cardiomyopathy.

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.

Detection of endotoxins from selected drinking water microbiota using an LAL-based assay and its implications for human health

Endotoxins are pyrogenic lipopolysaccharides from Gram-negative bacteria that are known to induce fever, septic shock, and multiple organ failure, posing a substantial risk to human health. Drinking water systems are especially prone to home microbiomes containing a large variety of Gram-negative bacteria. Consumption of water from these systems in developed countries is generally regarded as non-hazardous to humans due to the low number of non-pathogenic bacterial cells per milliliter and oral admission. To assess potential risks posed by endotoxins in drinking water systems, we conducted a conventional microbiological investigation on a local community water system in the north of Germany and mined the resulting data to investigate the endotoxin contents of some of the most abundant microbiota found during these analyses. Using a Limulus amoebocyte lysate (LAL) -based endotoxin detection method, average normalized endotoxin content was determined. Although the average culturable amounts of microbiota in the drinking water system were insufficient to exert endotoxin levels critical to human health, peaks and acute contaminations may pose substantial health risks.

Advances in endotoxin analysis

The outer membrane of gram-negative bacteria is primarily composed of lipopolysaccharide (LPS). In addition to protection, LPS defines the distinct serogroups used to identify bacteria specifically. Furthermore, LPS also act as highly potent stimulators of innate immune cells, a phenomenon essential to understanding pathogen invasion in the body. The complex multi-step process of LPS binding to cells involves several binding partners, including LPS binding protein (LBP), CD14 in both membrane-bound and soluble forms, membrane protein MD-2, and toll-like receptor 4 (TLR4). Once these pathways are activated, pro-inflammatory cytokines are eventually expressed. These binding events are also affected by the presence of monomeric or aggregated LPS. Traditional techniques to detect LPS include the rabbit pyrogen test, the monocyte activation test and Limulus-based tests. Modern approaches are based on protein, antibodies or aptamer binding. Recently, novel techniques including electrochemical methods, HPLC, quartz crystal microbalance (QCM), and molecular imprinting have been developed. These approaches often use nanomaterials such as gold nanoparticles, quantum dots, nanotubes, and magnetic nanoparticles. This chapter reviews current developments in endotoxin detection with a focus on modern novel techniques that use various sensing components, ranging from natural biomolecules to synthetic materials. Highly integrated and miniaturized commercial endotoxin detection devices offer a variety of options as the scientific and technologic revolution proceeds.

The non-canonical inflammasome activators Caspase-4 and Caspase-5 are differentially regulated during immunosuppression-associated organ damage

The non-canonical inflammasome, which includes caspase-11 in mice and caspase-4 and caspase-5 in humans, is upregulated during inflammatory processes and activated in response to bacterial infections to carry out pyroptosis. Inadequate activity of the inflammasome has been associated with states of immunosuppression and immunopathological organ damage. However, the regulation of the receptors caspase-4 and caspase-5 during severe states of immunosuppression is largely not understood. We report that CASP4 and CASP5 are differentially regulated during acute-on-chronic liver failure and sepsis-associated immunosuppression, suggesting non-redundant functions in the inflammasome response to infection. While CASP5 remained upregulated and cleaved p20-GSDMD could be detected in sera from critically ill patients, CASP4 was downregulated in critically ill patients who exhibited features of immunosuppression and organ failure. Mechanistically, downregulation of CASP4 correlated with decreased gasdermin D levels and impaired interferon signaling, as reflected by decreased activity of the CASP4 transcriptional activators IRF1 and IRF2. Caspase-4 gene and protein expression inversely correlated with markers of organ dysfunction, including MELD and SOFA scores, and with GSDMD activity, illustrating the association of CASP4 levels with disease severity. Our results document the selective downregulation of the non-canonical inflammasome activator caspase-4 in the context of sepsis-associated immunosuppression and organ damage and provide new insights for the development of biomarkers or novel immunomodulatory therapies for the treatment of severe infections.

[Hemoperfusion in anesthesia and intensive care medicine: benefits, risks, and evidence for different systems]

BACKGROUND

Hemoperfusion is a technique for the extracorporeal elimination of endogenous and exogenous toxins and harmful mediators by adsorption. It can be used as a stand-alone device, as part of a heart-lung machine or extracorporeal membrane oxygenation (ECMO) or, as is currently the case, integrated into a kidney replacement procedure. In the meantime, various suppliers offer devices with different technologies.

OBJECTIVE

The aim of this work was to evaluate the benefits, risks and evidence of the different systems, how they work and for which indications they are approved in Germany.

METHOD

To achieve this goal, a narrative assessment of the existing literature and guidelines for different indications was performed. The focus was on in vivo studies.

RESULTS

In principle, a distinction must be made in adsorption techniques between pure adsorption and the combination as adsorption and kidney replacement therapy. The adsorbers available in Germany include Cytosorb®, HA-330, Seraph®-100 and Toraymyxin. Combined procedures (adsorption and kidney replacement) are offered with coupled plasma filtration and adsorption (CPFA) and oXiris®. Most adsorbers have been developed for cytokine and endotoxin removal in patients with sepsis; however, to date, no randomized controlled trial (RCT) has demonstrated a survival benefit when using hemoperfusion. Therefore, the S3 guidelines for treatment of sepsis and the surviving sepsis campaign guidelines advise against its routine use. When the corona pandemic began, hemoperfusion was considered as a promising therapeutic approach. Cytosorb®, Seraph®-100, and oXiris® received emergency approval by the FDA to be used in critically ill patients with COVID-19, so questions arose about the appropriateness and importance of its use; however, the data generated did not show positive results, so its use cannot be recommended routinely either. In addition, they are not mentioned as a treatment option in the current guidelines. The use of adsorption procedures in patients with liver failure and rhabdomyolysis has only been rudimentarily studied, so any evidence is currently lacking. The only adsorber that has CE approval in Germany for both applications is Cytosorb®. In the next few years, studies will have to follow that investigate the efficacy and thus either justify or refute the use in clinical routine. Hemoperfusion procedures are used in the heart-lung machine as part of cardiac surgery for either cytokine or anticoagulant adsorption. No congruent data are available to support the use for the elimination of cytokines. If emergency cardiac surgery is required in a patient with pre-existing anticoagulation, hemoperfusion procedures can be used to prevent bleeding complications. Cytosorb® has CE approval for this indication. All available techniques are nonselective adsorption processes, so that adsorption of known and unknown substances can occur. Unintentional adsorption of drugs, such as various anti-infective agents is a relevant risk, especially when used in patients with sepsis.

DISCUSSION

Various adsorption systems can eliminate different known and unknown substances. Currently, there is a lack of evidence for all indications and systems to justify their routine use except in clinical trials. Future clinical trials should evaluate the potential benefits but also dangers, so that in the meantime the routine use can be justified or a recommendation against the use can be given.

Bacterial lipopolysaccharide-induced endothelial activation and dysfunction: a new predictive and therapeutic paradigm for sepsis

BACKGROUND

Lipopolysaccharide, a highly potent endotoxin responsible for severe sepsis, is the major constituent of the outer membrane of gram-negative bacteria. Endothelial cells participate in both innate and adaptive immune responses as the first cell types to detect lipopolysaccharide or other foreign debris in the bloodstream. Endothelial cells are able to recognize the presence of LPS and recruit specific adaptor proteins to the membrane domains of TLR4, thereby initiating an intracellular signaling cascade. However, lipopolysaccharide binding to endothelial cells induces endothelial activation and even damage, manifested by the expression of proinflammatory cytokines and adhesion molecules that lead to sepsis.

MAIN FINDINGS

LPS is involved in both local and systemic inflammation, activating both innate and adaptive immunity. Translocation of lipopolysaccharide into the circulation causes endotoxemia. Endothelial dysfunction, including exaggerated inflammation, coagulopathy and vascular leakage, may play a central role in the dysregulated host response and pathogenesis of sepsis. By discussing the many strategies used to treat sepsis, this review attempts to provide an overview of how lipopolysaccharide induces the ever more complex syndrome of sepsis and the potential for the development of novel sepsis therapeutics.

CONCLUSIONS

To reduce patient morbidity and mortality, preservation of endothelial function would be central to the management of sepsis.

Dual Functioned Hexapeptide-Coated Lipid-Core Nanomicelles Suppress Toll-Like Receptor-Mediated Inflammatory Responses through Endotoxin Scavenging and Endosomal pH Modulation

Excessive activation of Toll-like receptor (TLR) signaling pathways and the circulating endotoxin are key players in the pathogenesis of many acute and chronic inflammatory diseases. Regulation of TLR-mediated inflammatory responses by bioactive nanodevices represents a promising strategy for treating these diseases. In searching for novel, clinically applicable nanodevices with potent TLR inhibitory activities, three types of hexapeptide-modified nano-hybrids with different cores of phospholipid nanomicelles, liposomes, and poly(lactic-co-glycolic acid) nanoparticles are constructed. Interestingly, only the peptide-modified lipid-core nanomicelles (M-P12) display potent TLR inhibitory activities. Further mechanistic studies disclose that lipid-core nanomicelles have a generic property to bind to and scavenge lipophilic TLR ligands including lipopolysaccharide to block the ligand-receptor interaction and down-regulate the TLR signaling extracellularly. In addition, the peptide modification enables M-P12 a unique capability to modulate endosomal acidification upon being endocytosed into macrophages, which subsequently regulates the endosomal TLR signal transduction. In an acute lung injury mouse model, intratracheal administration of M-P12 can effectively target lung macrophages and reduce lung inflammation and injuries. This work defines a dual mechanism of action of the peptide-modified lipid-core nanomicelles in regulating TLR signaling, and provides new strategies for the development of therapeutic nanodevices for treating inflammatory diseases.

COVID-19 and Therapeutic Apheresis

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, is an unprecedented challenge for the global community. The pathogenesis of COVID-19, its complications and long term sequelae (so called Long/Post-COVID) include, in addition to the direct virus-induced tissues injury, multiple secondary processes, such as autoimmune response, impairment of microcirculation, and hyperinflammation. Similar pathological processes, but in the settings of neurological, cardiovascular, rheumatological, nephrological, and dermatological diseases can be successfully treated by powerful methods of Therapeutic Apheresis (TA). We describe here the rationale and the initial attempts of TA treatment in severe cases of acute COVID-19. We next review the evidence for the role of autoimmunity, microcirculatory changes and inflammation in pathogenesis of Long/Post COVID and the rationale for targeting those pathogenic processes by different methods of TA. Finally, we discuss the impact of COVID-19 pandemic on patients, who undergo regular TA treatments due to their underlying chronic conditions, with the specific focus on the patients with inherited lipid diseases being treated at the Dresden University Apheresis Center.

Secondary Dysfunction of the Intestinal Barrier in the Pathogenesis of Complications of Acute Poisoning

The last decade has been marked by an exponential increase in the number of publications on the physiological role of the normal human gut microbiota. The idea of a symbiotic relationship between the human organism and normal microbiota of its gastrointestinal tract has been firmly established as an integral part of the current biomedical paradigm. However, the type of this symbiosis varies from mutualism to parasitism and depends on the functional state of the host organism. Damage caused to the organism by external agents can lead to the emergence of conditionally pathogenic properties in the normal gut microbiota, mediated by humoral factors and affecting the outcome of exogenous exposure. Among the substances produced by symbiotic microbiota, there are an indefinite number of compounds with systemic toxicity. Some occur in the intestinal chyme in potentially lethal amounts in the case they enter the bloodstream quickly. The quick entry of potential toxicants is prevented by the intestinal barrier (IB), a set of structural elements separating the intestinal chyme from the blood. Hypothetically, severe damage to the IB caused by exogenous toxicants can trigger a leakage and subsequent systemic redistribution of toxic substances of bacterial origin. Until recently, the impact of such a redistribution on the outcome of acute exogenous poisoning remained outside the view of toxicology. The present review addresses causal relationships between the secondary dysfunction of the IB and complications of acute poisoning. We characterize acute systemic toxicity of such waste products of the normal gut microflora as ammonia and endotoxins, and demonstrate their involvement in the formation of such complications of acute poisoning as shock, sepsis, cerebral insufficiency and secondary lung injuries. The principles of assessing the functional state of the IB and the approaches to its protection in acute poisoning are briefly considered.