Endotoxin adsorption: Direct hemoperfusion with the polymyxin B-immobilized fiber column (PMX)

Repurposing clinically available drugs and therapies for pathogenic targets to combat SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic has affected a large portion of the global population, both physically and mentally. Current evidence suggests that the rapidly evolving coronavirus subvariants risk rendering vaccines and antibodies ineffective due to their potential to evade existing immunity, with enhanced transmission activity and higher reinfection rates that could lead to new outbreaks across the globe. The goal of viral management is to disrupt the viral life cycle as well as to relieve severe symptoms such as lung damage, cytokine storm, and organ failure. In the fight against viruses, the combination of viral genome sequencing, elucidation of the structure of viral proteins, and identifying proteins that are highly conserved across multiple coronaviruses has revealed many potential molecular targets. In addition, the time- and cost-effective repurposing of preexisting antiviral drugs or approved/clinical drugs for these targets offers considerable clinical advantages for COVID-19 patients. This review provides a comprehensive overview of various identified pathogenic targets and pathways as well as corresponding repurposed approved/clinical drugs and their potential against COVID-19. These findings provide new insight into the discovery of novel therapeutic strategies that could be applied to the control of disease symptoms emanating from evolving SARS-CoV-2 variants.

The Characteristics of Patients with Severe COVID-19 Pneumonia Treated with Direct Hemoperfusion Using Polymyxin B-Immobilized Fiber Column (PMX-DHP)

Purpose

The characteristics of patients with severe COVID-19 pneumonia who underwent direct hemoperfusion using polymyxin B-immobilized fiber column (PMX-DHP), in addition to steroids and immunomodulators, remain unclear.

Patients and Methods

We conducted a retrospective observational study on 31 patients with severe COVID-19 pneumonia treated with PMX-DHP in an intensive care unit (ICU) from December 2020 to September 2021.

Results

Outcomes 28 days after admission to the ICU were 20 in the survival group and 11 in the death group. Parameters significantly different between the survival and death group before PMX-DHP were percentage of invasive mechanical ventilation (25% vs 72.7%, P = 0.0209), PaO₂/F_IO₂ (P/F) ratio (104.5 vs 75, P = 0.0317), and sequential organ failure assessment (SOFA) score (2 vs 3, P = 0.0356). Invasive mechanical ventilation avoidance rate was significantly different between the survival (100%) and death group (0%) (P = 0.0012). P/F ratio, respiratory ratio (RR), and lymphocyte counts improved significantly after PMX-DHP for all patients. The lymphocyte counts changed significantly in the survival (P < 0.0001), but not the death group (P = 0.7927).

Conclusion

PMX-DHP, in addition to steroids and immunomodulators, may improve oxygenation and alleviate tachypnea by modulating the lymphocyte numbers and levels of various mediator against severe COVID-19 pneumonia. It may be better to perform PMX-DHP before multi organ dysfunction and lung injury has progressed. Furthermore, the early increase in lymphocyte counts after PMX-DHP might be an indicate a positive outcome.

Application of Adsorptive Blood Purification Techniques during Cardiopulmonary Bypass in Cardiac Surgery

By reason of surgical demand, the majority of cardiovascular procedures still depend on the use of cardiopulmonary bypass (CPB). Due to the nonphysiological state of CPB, it can cause complex and unpredictable inflammatory response, which may lead to significant morbidity and mortality. Unfortunately, the pharmacological and mechanical strategies that currently exist do not offer significant advantages in controlling inflammatory response and improving patient outcomes. The best strategy to reduce inflammation in CPB is still uncertain. In recent years, adsorptive blood purification techniques (BPTs) have emerged, among which CytoSorb is the latest representative device. Currently, the primary application area of adsorptive BPTs is in the control and treatment of systemic hyperinflammatory states, such as refractory septic shock patients. However, the evidences on efficacy and safety of adsorptive BPTs application during CPB surgery are still inconclusive, so we summarize the relevant evidences here and suggest future potential research areas.

Dialysis Membranes for Acute Kidney Injury

Mortality and morbidity rates among critically ill septic patients having acute kidney injury (AKI) are very high, considering the total number of deaths after their admission. Inappropriate selection of the type of continuous renal replacement therapy and inadequate therapy become the immediate causes of these issues. Dialysis is a commonly used treatment intended to prolong the life of AKI patients. Dialysis membranes, which are the core of dialysis treatment, must be properly selected to ensure fair treatment to the patients. The accumulation of certain types of molecules must be dealt with using the right membrane. Whether it is low-flux, high-flux, or adsorptive type, the dialysis membrane should be chosen depending on the condition of the patients. The selection of dialysis membranes should also be based on their effect on the treatment outcomes and well-being. All these options are needed to serve the patients of different clinical settings. The use of dialysis membranes is not restricted to conventional haemodialysis, but rather they can be employed in haemoperfusion, haemofiltration, haemodiafiltration, or a combination of any two of them. This review focuses in-depth on different types of dialysis membranes, their characteristics, and approaches in addressing the issues encountered in patients having AKI with sepsis and/or multiorgan failure in intensive care units.

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

Lipopolysaccharide, the main component of the outer membrane of Gram-negative bacteria is a highly potent endotoxin responsible for organ dysfunction in sepsis. It is present in the blood stream not only in Gram-negative infections, but also in Gram-positive and fungal infections, presumably due to sepsis-related disruption of the intestinal barrier. Various pathways, both extra- and intracellular, are involved in sensing endotoxin and non-canonical activation of caspase-mediated pyroptosis is considered to have a major role in sepsis pathophysiology. Endotoxin induces specific pathological alterations in several organs, which contributes to poor outcomes. The adverse consequences of endotoxin in the circulation support the use of anti-endotoxin therapies, yet more than 30 years of experience with endotoxin adsorption therapies have not provided clear evidence in favor of this treatment modality. The results of small studies support timely endotoxin removal guided by measuring the levels of endotoxin; unfortunately, this has not been proven in large, randomized studies. The presence of endotoxemia can be demonstrated in the majority of patients with COVID-19, yet only case reports and case series describing the effects of endotoxin removal in these patients have been published to date. The place of blood purification therapies in the treatment of septic shock has not yet been determined.

Blood purification could tackle COVID-19?

Coronavirus disease 2019 (COVID-19) threatened human lives worldwide since first reported. The current challenge for global intensivists is to establish an effective treatment for severe COVID-19. Blood purification has been applied to the treatment of various critical illnesses. Theoretically, its technique also has an enormous possibility of treating severe COVID-19 in managing inflammatory cytokines and coagulopathy. Recent clinical studies have revealed the positive clinical effect of therapeutic plasma exchange. Other studies have also indicated the considerable potential of other blood purification techniques, such as Cytosorb, AN69 surface-treated membrane, and polymyxin b hemoperfusion. Further research is needed to elucidate the actual effects of these applications.

Biomaterial Wettability Affects Fibrin Clot Structure and Fibrinolysis

Thrombosis on blood-contacting medical devices can cause patient fatalities through device failure and unstable thrombi causing embolism. The effect of material wettability on fibrin network formation, structure, and stability is poorly understood. Under static conditions, fibrin fiber network volume and density increase in clots formed on hydrophilic compared to hydrophobic polystyrene surfaces. This correlates with reduced plasma clotting time and increased factor XIIa (FXIIa) activity. These structural differences are consistent up to 50 µm away from the material surface and are FXIIa dependent. Fibrin forms fibers immediately at the material interface on hydrophilic surfaces but are incompletely formed in the first 5 µm above hydrophobic surfaces. Additionally, fibrin clots on hydrophobic surfaces have increased susceptibility to fibrinolysis compared to clots formed on hydrophilic surfaces. Under low-flow conditions, clots are still denser on hydrophilic surfaces, but only 5 µm above the surface, showing the combined effect of the surface wettability and coagulation factor dilution with low flow. Overall, wettability affects fibrin fiber formation at material interfaces, which leads to differences in bulk fibrin clot density and susceptibility to fibrinolysis. These findings have implications for thrombus formed in stagnant or low-flow regions of medical devices and the design of nonthrombogenic materials.

Surface Modification of Reduced Graphene Oxide Beads: Integrating Efficient Endotoxin Adsorption and Improved Blood Compatibility

As a pathogenic toxin, endotoxins are the culprit for endotoxemia and can be generally removed from the blood by hemoperfusion. Reduced graphene oxide (rGO) is a promising endotoxin sorbent for hemoperfusion owing to its excellent adsorption capacity, but it has the side effect of nonspecific adsorption and low blood compatibility. Polymyxin B (PMB) acts as an organic affinity ligand that can specifically bind endotoxins. As a natural anticoagulant, heparin (Hep) can reduce the risk of coagulation and improve the blood compatibility of materials. Herein, an rGO bead adsorbent was prepared by coupling with PMB and Hep and used for endotoxin adsorption; in this, polydopamine (pDA) served as an active coating for immobilization of PMB and further coupling with Hep. The physicochemical characteristics indicated that PMB and Hep were successfully immobilized on rGO beads with a hierarchical pore structure. PMB endowed rGO beads with higher adsorption capacity (143.84 ± 3.28 EU/mg) and good adsorption selectivity for endotoxins. Hep significantly improved the blood compatibility of rGO beads. These modified rGO beads also achieved good adsorption capacity and adsorption selectivity for endotoxins in plasma, serum, or blood. Therefore, rGO/pDA/PMB/Hep beads are potential adsorbents for endotoxins in hemoperfusion.

PMX-DHP Therapy for Dyspnea and Deoxygenation in Severe COVID-19 Pneumonia: A Case Series

Hypercytokinemia induced by coronavirus disease-19 (COVID-19) is associated with severe pulmonary involvement, which may lead to respiratory failure. These conditions play an important role in the worsening of clinical symptoms in patients with severe COVID-19. There is no established treatment for hypercytokinemia. We report on two patients whose clinical symptoms improved after direct hemoperfusion using polymyxin B-immobilized fiber column (PMX-DHP), following the administration of the anti-inflammatory agent tocilizumab. Case A was a 70-year-old man diagnosed with COVID-19 pneumonia. Despite treatment with ciclesonide and favipiravir, supplemental oxygen was administered due to the worsening of dyspnea with tachypnea. Although tocilizumab was started on day 6, the patient deteriorated into deoxygenation, presenting with the PaO₂/F_IO₂ (P/F) ratio of 92. On days 8 and 10, the patient received PMX-DHP therapy. On day 11, his dyspnea improved. On day 13, his P/F ratio began to improve, and oxygen therapy was discontinued on day 18. The patient recovered without requiring mechanical ventilation. Case B was a 70-year-old man diagnosed with COVID-19 pneumonia and treated with favipiravir, starting on day 0. Despite starting ciclesonide inhalation and tocilizumab on day 2, his P/F ratio was 53. On day 5, he received PMX-DHP therapy. On day 6, his dyspnea improved, as did his P/F ratio, reaching 81 on day 8. Finally, his clinical symptoms resolved, and he was discharged from the intensive care unit without requiring mechanical ventilation. These cases indicate that PMX-DHP therapy might be a suitable treatment option for dyspnea and deoxygenation in COVID-19 pneumonia, especially in cases where an anti-inflammatory agent, such as tocilizumab, has failed to achieve the desired effect.

Direct hemoperfusion with polymyxin B-immobilized fiber column in a patient with acute exacerbation of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrosing interstitial lung disease characterized by dyspnea and a worsening of the lung function. Acute exacerbations of idiopathic pulmonary fibrosis (AE-IPF) are defined by a clinically significant respiratory deterioration, that typically develops in less than 1 month, accompanied by new radiologic abnormalities on high-resolution computed tomography, including diffused and bilateral ground-glass opacification, along with an absence of other obvious clinical etiologies. Recently, AE-IPF has gained significant importance as a major cause of mortality and morbidity. However, despite the extremely poor prognosis of the condition, no well-validated therapeutic interventions are currently available. Therefore, novel treatment modalities are being investigated and applied in addition to conventional treatments. Among them, several studies have reported that a direct hemoperfusion with a polymyxin B-immobilized fiber column (PMX-DHP), developed for endotoxin removal in septic shock, has an effect on AE-IPF. We describe two cases of PMX-DHP treatment with conflicting results. One patient successfully recovered via a PMX-DHP in severe AE-IPF that required extracorporeal membrane oxygenation (ECMO). PMX-DHP subsequently improved oxygenation (PaO2/FiO2 ratio) and decreased the levels of inflammatory markers (interleukin-6, C-reactive protein, and white blood cells). The patient dramatically recovered without the need for ECMO. PMX-DHP may be considered an alternative therapy in AE-IPF patients requiring mechanical ventilation or ECMO.

Successful Recovery from COVID-19-associated Acute Respiratory Failure with Polymyxin B-immobilized Fiber Column-direct Hemoperfusion

An 83-year-old man was hospitalized for coronavirus disease 2019 (COVID-19) after a 10-day history of a persistent fever. Chest computed tomography showed extensive non-segmental ground glass opacity. Despite the initiation of lopinavir and ritonavir, respiratory failure progressed. Two days of polymyxin B-immobilized fiber column-direct hemoperfusion (PMX-DHP) with adjunctive corticosteroid prevented his respiratory condition from worsening. For rapidly progressive COVID-19 cases, the early use of PMX-DHP may avoid the need for mechanical ventilation by suppressing local inflammation of the lung.

Therapeutic plasma exchange for clinically amyopathic dermatomyositis (CADM) associated with rapidly progressive interstitial pneumonia

BACKGROUND

Patients with clinically amyopathic dermatomyositis (CADM) with anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5 Ab) frequently develop rapidly progressive interstitial pneumonia (RPIP), often with fatal outcomes. Therapeutic plasma exchange (TPE) has been reported as effective against CADM-RPIP refractory to conventional immunosuppressive therapy. However, the detailed mechanisms by which TPE improves disease activity of CADM-RPIP remain unclear.

AIM

To elucidate the clinical and demographic characteristics of patients with anti-MDA5 Ab-positive CADM-RPIP treated with TPE and to analyze changes in laboratory findings before, during, and after TPE.

MATERIALS & METHODS

Patients hospitalized for CADM-RPIP and treated with TPE in 2017 and 2018 were analyzed retrospectively.

RESULTS

Three patients were successfully treated with TPE, with good tolerance. Anti-MDA5 Ab titers decreased significantly over the course of TPE.

CONCLUSION

We emphasize that TPE could represent an effective treatment option for CADM-RPIP refractory to traditional therapy. Removal of anti-MDA5 Ab and other pathogenic factors may facilitate favorable outcomes.

Clinical Effects and Outcomes After Polymyxin B-Immobilized Fiber Column Direct Hemoperfusion Treatment for Septic Shock in Preterm Neonates

OBJECTIVES

To compare the effectiveness and mortality of early-onset sepsis or late-onset sepsis treatments with polymyxin B-immobilized fiber column direct hemoperfusion in terms of effectiveness and mortality in preterm infants with septic shock.

DESIGN

Retrospective cohort study.

SETTING

Neonatal ICU within a tertiary care hospital.

PATIENTS

Of 1,115 patients, 49 had blood culture-proven sepsis between January 2013 and December 2018; six and five patients with septic shock had undergone polymyxin B-immobilized fiber column direct hemoperfusion treatment for early-onset sepsis (early-onset sepsis group) and late-onset sepsis (late-onset sepsis group), respectively.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Baseline demographic characteristics of both groups were similar. The time from decision to treatment induction was significantly shorter in the early-onset sepsis group than that in the late-onset sepsis group (p = 0.008). The mortality rate after 28 days of treatment and the hospital mortality were significantly lower in the early-onset sepsis group than in the late-onset sepsis group (p = 0.026 and 0.015, respectively). The PaO2/FIO2 ratio was significantly higher in the early-onset sepsis group than in the late-onset sepsis group at the end of the treatment (p = 0.035). In addition, median arterial-to-alveolar oxygen tension ratio significantly improved from 0.19 to 0.55, and median blood pressure also significantly improved from 32.5 to 40.0 mm Hg after the treatment in the early-onset sepsis group. Interleukin-6 levels significantly decreased after treatment in the early-onset sepsis group (p = 0.037). The Pediatric Risk of Mortality III score was similar between the early-onset sepsis and late-onset sepsis groups before and after the treatment. Intraventricular hemorrhage events occurred in both groups, but with no significant differences (p = 0.175).

CONCLUSIONS

Polymyxin B-immobilized fiber column direct hemoperfusion treatment for preterm infants with septic shock due to early-onset sepsis is associated with earlier hemodynamic and respiratory status improvements and with lower mortality than that due to late-onset sepsis. Early neonatal septic shock detection and polymyxin B-immobilized fiber column direct hemoperfusion induction may improve the prognosis of affected infants.

Acute Colchicine Poisoning Causes Endotoxemia via the Destruction of Intestinal Barrier Function: The Curative Effect of Endotoxin Prevention in a Murine Model

BACKGROUND

Colchicine binds to intracellular tubulin and prevents mitosis. Colchicine is also used as an anti-inflammatory drug. Meanwhile, excess administration of medication or accidental ingestion of colchicine-containing plants can cause acute colchicine poisoning, which initially results in gastrointestinal effects that may be followed by multiorgan dysfunction. However, the mechanism of colchicine poisoning remains unclear, and there are no standard therapeutic strategies.

AIMS

We focused on intestinal barrier function and attempted to reveal the underlying mechanism of colchicine poisoning using an animal model.

METHODS

Colchicine was orally administered to C57Bl/6 mice. Then, we performed histopathological analysis, serum endotoxin assays, and intestinal permeability testing. Additionally, the LPS-TLR4 signaling inhibitor TAK-242 was intraperitoneally injected after colchicine administration to analyze the therapeutic effect.

RESULTS

We observed villus height reduction and increased numbers of apoptotic cells in the gastrointestinal epithelium of colchicine-treated mice. Both intestinal permeability and serum endotoxin levels were higher in colchicine-treated mice than in control mice. Although colchicine-poisoned mice died within 25 h, those that also received TAK-242 treatment survived for more than 48 h.

CONCLUSION

Colchicine disrupted intestinal barrier function and caused endotoxin shock. Therapeutic inhibition of LPS-TLR4 signaling might be beneficial for treating acute colchicine poisoning.

Changes of inflammatory mediators and oxidative stress indicators in children with Henoch-Schönlein purpura and clinical effects of hemoperfusion in the treatment of severe Henoch-Schönlein purpura with gastrointestinal involvement in children

BACKGROUND

To explore the changes of inflammatory and oxidative stress responses in Henoch-Schönlein purpura (HSP) children, and further analyzed the therapeutic effects and mechanisms of hemoperfusion (HP) on HSP with severe gastrointestinal (GI) involvement.

METHODS

There were 200 children with HSP were divided into three groups according to their clinical manifestations: 60 in HSP without GI and renal involvement group, 60 in HSP with GI involvement group, and 80 in HSPN group. The HSP with GI involvement group was subdivided into conventional treatment (n = 30) and HP (n = 30) groups. Thirty children who visited the department of children healthcare for healthy physical examinations from January to December 2017 were set as healthy control group. The IL-6 and TNF-α levels were detected by chemoluminescence method. The MDA, SOD and T-AOC levels were determined by thiobarbituric acid colorimetric method, hydroxylamine method and chemical colorimetry.

RESULTS

Compared with healthy group, IL-6, TNF-α and MDA levels in HSP were increased in each group, while SOD and T-AOC were decreased (P = 0.000). IL-6, TNF-α and MDA levels in the HSPN group were the highest, SOD and T-AOC levels were the lowest (P = 0.000). Compared with those before treatment, IL-6, TNF-α and MDA levels in the conventional and HP groups were decreased and SOD and T-AOC levels were increased (P = 0.000). The changes in HP group were more significant than those in conventional group (P < 0.047). Compared with conventional group, glucocorticoid dosage and the occurrence rate of hematuria and/or proteinuria within 3 months were lower in HP group. (P = 0.000, 0.004).

CONCLUSIONS

Inflammatory and oxidative stress may be involved in the acute phase of HSP children. The intensity of inflammatory and oxidative stress responses were related to the degree of renal involvement. HP can reduce glucocorticoid dosage and the rate of renal involvement in children with severe HSP with GI involvement. The mechanism may be related to the fact that HP can effectively remove IL-6, TNF-α, MDA in HSP children.

A systematic review of the efficacy of direct hemoperfusion with a polymyxin B-immobilized fibre column to treat rapidly progressive interstitial pneumonia

Objectives

Rapidly progressive interstitial pneumonia is a fatal disease with no established therapeutic options. The aim of this systematic review is to clarify the efficacy of interstitial pneumonia treatment utilizing direct hemoperfusion with a polymyxin B-immobilized fibre column.

Methods

All patients with adult-onset rapidly progressive interstitial pneumonia including acute exacerbation of underlying chronic interstitial pneumonia were eligible. Primary studies of any design, which compared outcomes of direct hemoperfusion with a polymyxin B-immobilized fibre column treatment such as oxygenation and all-cause mortality with those of conventional therapy, were included. Electronic databases such as Medline and EMBASE were searched through October 7, 2018, and ICHUSHI, the largest database for medical articles in Japan, was also searched. Two reviewers independently extracted the relevant data and assessed the risk of bias in individual studies. The results were reported qualitatively due to substantial heterogeneity between studies.

Results

Out of 775 records retrieved, 10 reports were eligible and 8 of them were included for further analysis. They were all retrospective studies including a total of 327 patients and contained some risk of bias. There was variation in the administration method of direct hemoperfusion with a polymyxin B-immobilized fibre column treatment such as the timing, frequency, duration and interval. Multivariate analyses of only two studies with historical controls demonstrated beneficial effects of direct hemoperfusion with a polymyxin B-immobilized fibre column treatment over conventional therapy with all-cause mortality hazard ratios of 0.345 (95% confidence interval: 0.127-0.936) and 0.505 (95% confidence interval: 0.270-0.904), respectively. A significant difference of an improvement in the ratio of partial arterial oxygen pressure to the fraction of inspired oxygen in-between two treatment groups was also reported in two studies utilizing historical controls with mean differences of 56.8 and 57.5 mmHg, respectively.

Conclusions

There is currently insufficient data to support the use of direct hemoperfusion with a polymyxin B-immobilized fibre column treatment for rapidly progressive interstitial pneumonia. It should be instituted for research purposes only until new evidence is available.