S100A8 may govern hyper-inflammation in severe COVID-19

The coronavirus disease 2019 (COVID-19) pandemic threatens human species with mortality rate of roughly 2%. We can hardly predict the time of herd immunity against and end of COVID-19 with or without success of vaccine. One way to overcome the situation is to define what delineates disease severity and serves as a molecular target. The most successful analogy is found in BCR-ABL in chronic myeloid leukemia, which is the golden biomarker, and simultaneously, the most effective molecular target. We hypothesize that S100 calcium-binding protein A8 (S100A8) is one such molecule. The underlying evidence includes accumulating clinical information that S100A8 is upregulated in severe forms of COVID-19, pathological similarities of the affected lungs between COVID-19 and S100A8-induced acute respiratory distress syndrome (ARDS) model, homeostatic inflammation theory in which S100A8 is an endogenous ligand for endotoxin sensor Toll-like receptor 4/Myeloid differentiation protein-2 (TLR4/MD-2) and mediates hyper-inflammation even after elimination of endotoxin-producing extrinsic pathogens, analogous findings between COVID-19-associated ARDS and pre-metastatic lungs such as S100A8 upregulation, pulmonary recruitment of myeloid cells, increased vascular permeability, and activation coagulation cascade. A successful treatment in an animal COVID-19 model is given with a reagent capable of abrogating interaction between S100A8/S100A9 and TLR4. In this paper, we try to verify our hypothesis that S100A8 governs COVID-19-associated ARDS.

Eritoran attenuates tissue damage and inflammation in hemorrhagic shock/trauma

BACKGROUND

Severe injury and associated hemorrhagic shock lead to an inflammatory response and subsequent increased tissue damage. Numerous reports have shown that injury-induced inflammation and the associated end-organ damage is driven by Toll-like receptor 4 (TLR4) activation via damage-associated molecular patterns. We examined the effectiveness of Eritoran tetrasodium (E5564), an inhibitor of TLR4 function, in reducing inflammation induced during hemorrhagic shock with resuscitation (HS/R) or after peripheral tissue injury (bilateral femur fracture, BFF).

MATERIAL AND METHODS

Mice underwent HS/R or BFF with or without injection of Eritoran (5 mg/kg body weight) or vehicle control given before, both before and after, or only after HS/R or BFF. Mice were sacrificed after 6 h and plasma and tissue cytokines, liver damage (histology; aspartate aminotransferase/alanine aminotransferase), and inflammation (NF-κB) and gut permeability were assessed.

RESULTS

In HS/R Eritoran significantly reduced liver damage (values ± SEM: alanine aminotransferase 9910 ± 3680 U/L versus 1239 ± 327 U/L and aspartate aminotransferase 5863 ± 2000 U/L versus 1246 ± 243 U/L, P < 0.01) at 6 h compared with control when given just before HS and again just prior to resuscitation. Eritoran administration also led to lower IL-6 levels in plasma and liver and less NF-κB activation in liver. Increases in gut barrier permeability induced by HS/R were also prevented with Eritoran. Eritoran similarly diminished BFF-mediated systemic inflammatory responses.

CONCLUSION

These data suggest Eritoran can inhibit tissue damage and inflammation induced via TLR4/myeloid differentiation factor 2 signaling from damage-associated molecular patterns released during HS/R or BFF. Eritoran may represent a promising therapeutic for trauma patients to prevent multiple organ failure.

Effect of eritoran, an antagonist of MD2-TLR4, on mortality in patients with severe sepsis: the ACCESS randomized trial

IMPORTANCE

Eritoran is a synthetic lipid A antagonist that blocks lipopolysaccharide (LPS) from binding at the cell surface MD2-TLR4 receptor. LPS is a major component of the outer membrane of gram-negative bacteria and is a potent activator of the acute inflammatory response.

OBJECTIVE

To determine if eritoran, a TLR4 antagonist, would significantly reduce sepsis-induced mortality.

DESIGN, SETTING, AND PARTICIPANTS

We performed a randomized, double-blind, placebo-controlled, multinational phase 3 trial in 197 intensive care units. Patients were enrolled from June 2006 to September 2010 and final follow-up was completed in September 2011.

INTERVENTIONS

Patients with severe sepsis (n = 1961) were randomized and treated within 12 hours of onset of first organ dysfunction in a 2:1 ratio with a 6-day course of either eritoran tetrasodium (105 mg total) or placebo, with n = 1304 and n = 657 patients, respectively.

MAIN OUTCOME MEASURES

The primary end point was 28-day all-cause mortality. The secondary end points were all-cause mortality at 3, 6, and 12 months after beginning treatment.

RESULTS

Baseline characteristics of the 2 study groups were similar. In the modified intent-to-treat analysis (randomized patients who received at least 1 dose) there was no significant difference in the primary end point of 28-day all-cause mortality with 28.1% (366/1304) in the eritoran group vs 26.9% (177/657) in the placebo group (P = .59; hazard ratio, 1.05; 95% CI, 0.88-1.26; difference in mortality rate, -1.1; 95% CI, -5.3 to 3.1) or in the key secondary end point of 1-year all-cause mortality with 44.1% (290/657) in the eritoran group vs 43.3% (565/1304) in the placebo group, Kaplan-Meier analysis of time to death by 1 year, P = .79 (hazard ratio, 0.98; 0.85-1.13). No significant differences were observed in any of the prespecified subgroups. Adverse events, including secondary infection rates, did not differ between study groups.

CONCLUSIONS AND RELEVANCE

Among patients with severe sepsis, the use of eritoran, compared with placebo, did not result in reduced 28-day mortality.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00334828.

Eritoran tetrasodium (E5564) treatment for sepsis: review of preclinical and clinical studies

INTRODUCTION

Sepsis remains a leading cause of death worldwide. Despite years of extensive research, effective drugs that inhibit the pro-inflammatory effects of lipopolysaccharide (LPS) and improve outcome when added to conventional sepsis treatments are lacking. Eritoran tetrasodium (E5564) is a promising candidate therapy for sepsis belonging to a new class of such drugs which inhibit LPS-induced inflammation by blocking toll-like receptor 4.

AREAS COVERED

This review focuses on the rationale for the use of eritoran tetrasodium in sepsis as well as on its pharmacokinetics, pharmacodynamics, efficacy and safety. Preclinical and clinical studies from a MEDLINE/PubMed literature search in August 2010 with the search terms 'eritoran' and 'E5564' are discussed.

EXPERT OPINION

Preclinical in vitro and in vivo studies of eritoran tetrasodium indicate it can limit excessive inflammatory mediator release associated with LPS and improve survival in sepsis models. While early clinical results are promising, its efficacy and safety for treating patients with sepsis are currently under investigation. Even if the ongoing Phase III clinical trial enrolling patients with severe sepsis and increased risk of death shows benefit from eritoran, questions remain and confirmatory studies would be necessary to define its clinical usage.

Antagonism of lipopolysaccharide-induced blood pressure attenuation and vascular contractility

OBJECTIVE

Aim was to assess whether lipopolysaccharide (LPS)-induced decrease of total peripheral resistance depends on Toll-like receptor (TLR)4 signaling and whether it is sensitive to NO-synthase or TLR4 antagonists.

METHODS AND RESULTS

C3H/HeN mice (control), expressing a functional, and C3H/HeJ mice, expressing a nonfunctional TLR4, were compared. LPS (20 mg/kg) was injected i.p. 6 hours before hemodynamic measurements. L-NAME and SMT, inhibitors of NO production, and Eritoran, a TLR4 antagonist, were tested for their impact on vascular contractility. Aortic rings were incubated for 6 hours with or without LPS (1 microg/mL), or with LPS+Eritoran (2 microg/mL) and their phenylephrine-induced contractility was measured using a myograph. The expression of cytokines in aortic tissue was examined by real-time polymerase chain reaction. In control mice LPS induced a significant decrease of blood pressure and an increase of heart rate, whereas C3H/HeJ remained unaffected. LPS induced an increase of cytokine expression and a depression of vascular contractility only in control mice but not in C3H/HeJ. L-NAME and SMT increased contractility in all rings and restored LPS-dependent depression of contractility. Eritoran prevented LPS-induced loss of contractility.

CONCLUSIONS

LPS upregulates cytokine expression via TLR4 and induces attenuation of smooth muscle contractility which can be effectively antagonized.

[Toll-like receptors, a new way of treatment?]

Toll-like receptors (TLRs) comprise a group of recently discovered receptors which are essential molecular structures in the activation of immunity. The discovery of TLRs has provided a substantial increase in the knowledge of immunologic aspects of disease pathology and is presently giving rise to new treatment strategies. This review summarizes the current knowledge on TLRs functioning in infections, their possible roles in inflammatory bowl disease and the pivotal role for TLRs in endotoxic shock, an area which is currently subject to development of a new farmakon.

Inhibition of Toll-like receptor 4 with eritoran attenuates myocardial ischemia-reperfusion injury

BACKGROUND

We previously reported that the functional mutation of Toll-like receptor 4 (TLR4) in C3H/HeJ mice subjected to myocardial ischemia-reperfusion (MI/R) injury resulted in an attenuation of myocardial infarction size. To investigate the ligand-activating TLR4 during MI/R injury, we evaluated the effect of eritoran, a specific TLR4 antagonist, on MI/R injury, with the goal of defining better therapeutic options for MI/R injury.

METHODS AND RESULTS

C57BL/6 mice received eritoran (5 mg/kg) intravenously 10 minutes before 30 minutes of in situ of transient occlusion of the left anterior descending artery, followed by 120 minutes of reperfusion. Infarct size was measured using triphenyltetrazoliumchloride staining. A c-Jun NH(2)-terminal kinase (JNK) activation was determined by Western blotting, nuclear factor (NF)-kappaB activity was detected by gel-shift assay, and cytokine expression was measured by ribonuclease protection assay. Mice treated with eritoran developed significantly smaller infarcts when compared with mice treated with vehicle alone (21.0+/-6.4% versus 30.9+/-13.9%; P=0.041). Eritoran pretreatment resulted in a reduction in JNK phosphorylation (eritoran versus vehicle: 3.98+/-0.81 versus 7.01+/-2.21-fold increase; P=0.020), less nuclear NF-kappaB translocation (2.70+/-0.35 versus 7.75+/-0.60-fold increase; P=0.00007), and a decrease in cytokine expression (P<0.05).

CONCLUSIONS

We conclude that inhibition of TLR4 with eritoran in an in situ murine model significantly reduces MI/R injury and markers of an inflammatory response.

Antihuman epidermal growth factor receptor 2 antibody herceptin inhibits autocrine motility factor (AMF) expression and potentiates antitumor effects of AMF inhibitors

Overexpression of the human epidermal growth factor receptor (HER) 2 has been linked to the development and maintenance of malignant phenotypes in breast tumors. In addition, the growth and dissemination of human cancers are regulated in part by the autocrine motility factor (AMF)/phosphoglucose isomerase shown to be up-regulated by heregulin (HRG) in breast cancer cells. This study was undertaken to explore the effect of anti-HER2 monoclonal antibody 4D5 [Herceptin (HCT)] on AMF expression and the potential of its augmentation by specific simple sugar AMF inhibitors. Here we show that HCT treatment of high HER2-expressing breast cancer SK-BR3, BT-474, and ZR-75R cells resulted in down-regulation of AMF mRNA and protein. HCT inhibited the ability of HRG to induce AMF expression in cells with a normal HER2 level, and HCT-mediated down-regulation could be reversed by HRG treatment in breast cancer cells with a high HER2 level. HCT also inhibited transcription from a chimeric pGL3-Luc vector-based reporter system containing the 1.8-kb promoter region of human AMF. Treatment of breast cancer cells with the combination of HCT and specific AMF inhibitors, erythrose 4-phosphate or D-mannose 6-phosphate, resulted in an additive inhibitory effect on both the growth rate and invasiveness of cells as compared with treatment with each agent alone. Results presented here suggest that HCT can effectively block both ligand-induced and constitutive expression of AMF associated with high HER2 overexpression, implying a role of the AMF pathway in the action of HCT. Accordingly, the combination of AMF inhibitor with HCT can potentiate the growth-inhibitory and anti-invasive action of HCT in breast cancer cells.

Trehalose-6-phosphate-potent anti-onchocerciatic agent

Onchocerciasis is a disease that engages the attention of most researchers. Presently, there is not an ideal onchocerciatic agent, hence the search must continues. Consequently alpha, alpha-trehalose-6-phosphate was synthesised and assessed for onchocerciatic activity against O. volvulus; using diethylcarbamizine citrate as the control drug. Results from this study showed that alpha, alpha-trehalose-6-phosphate is a glucose analogue with effective micro and macro-filaricidal agent, better than that of the control drug. The inhibitory action of this compound on enzyme trehalase is a postulate for the mechanism of action of trehalose-6-phosphate. The structure-activity relationship of this new compound is fully discussed. This study postulates that this compound could be used to eradicate onchocerciasis both in man and animals.

Hypoglycaemic activity of alpha, alpha trehalose-6-phosphate

Alpha-alpha-trehalose-6-phosphate, synthesized by Oke was screened for hypoglycaemic activity. Alloxan-induced diabetic albino rats and fasted-rabbits were used in the study. The inhibitory activity of trehalose-6-phosphate on trehalase was also assayed. The study shows that alpha-alpha-trehalose-6-phosphate is a glucose analogue with potent anti-hyperglcaemic activity as shown by its hypoglycaemic response in fasted rabbits. The ability of alpha-alpha-trehalose-6-phosphate to attenuate the diabetic toxicity in alloxan-induced diabetic rats confirmed its potent anti-diabetic activity. The mechanism of action of this synthesized compound may be linked with its ability to inhibit trehalase, and increase the activity of the superoxidase dimutase present in the beta-cells of the alloxan-diabetic rats and also being a glucose analogue according to Puls principle, alpha-alpha-trehalose-6-phosphate is able to influence the intermediate metabolism of carbohydrate.

Synthesis of glycopyranosylphosphonate analogues of certain natural nucleoside diphosphate sugars as potential inhibitors of glycosyltransferases

The synthesis of alpha-D-glucopyranosyl-, alpha-D-galactopyranosyl-, and alpha-D-mannopyranosylphosphonate is described. Condensation of tris(trimethylsilyl) phosphite with 2,3,4,6-tetrakis-O-(phenylmethyl)-1-O-acetyl-alpha-D-glucopyranose generated 2,3,4,6-tetrakis-O-(phenylmethyl)-alpha-D-glucopyranosylphosphonic acetic anhydride (13). The benzyl blocking groups were removed by catalytic hydrogenation, and the anhydride bond was cleaved by alkaline hydrolysis to obtain alpha-D-glucopyranosylphosphonate (15). alpha-D-Galactopyranosylphosphonate (17) and alpha-D-mannopyranosylphosphonate (19) were also similarly synthesized. The anomeric configuration of 15 was assigned by single-crystal X-ray analysis, and the structural assignments of 17 and 19 were made on the basis of comparative NMR spectral studies. Compound 15 was then coupled with adenosine 5'-phosphoric di-n-butylphosphinothioic anhydride in dry pyridine to give adenosine 5'-phosphoric alpha-D-glucopyranosylphosphonic anhydride (23). Similarly, uridine 5'-phosphoric alpha-D-galactopyranosylphosphonic anhydride (24) and guanosine 5'-phosphoric alpha-D-mannopyranosylphosphonic anhydride (25) were synthesized from 17 and 19, respectively. With ovalbumin as an acceptor for [3H]galactose, provided by UDP-[3H]galactose, only uridine 5'-phosphoric alpha-D-galactopyranosylphosphonic anhydride (24) was shown to inhibit glycoprotein beta-D-galactosyltransferase (EC 2.4.1.38), with an apparent Ki equal to 165 microM. Even though these ionic compounds hardly penetrate the cell membrane, preliminary in vitro antitumor screening shows that compounds 23 and 25 are slightly active against human B-lymphoblastic leukemia and human T-lymphoblastic leukemia. None of these compounds show any antiviral activity.

Protection of kidneys from acute renal failure resulting from normothermic ischemia

Rat kidneys were flushed in situ with selected preservation solutions prior to clamping the renal vessels for 1 hour. Collins and Euro-Collins flushing solutions did not appear to protect the physiologic or morphologic status of rat kidneys when examined 2 days after the ischemic insult. These experimental groups exhibited serum creatinine levels similar to those seen in ischemic controls, correspondingly low urine creatinine levels, anuria, and significant deterioration of the uriniferous tubules as revealed by light and electron microscopy. In situ flushing with hypertonic Sacks or isotonic phosphate-buffered sucrose solutions, however, resulted in significant improvements in serum and urine creatinine levels, prevented anuria, and dramatically improved the morphologic integrity of the uriniferous tubules. Flushing with a phosphate-buffered sucrose solution that contained ATP-MgCl2 further improved the physiologic and morphologic status of ischemic kidneys to the point that they were indistinguishable from the nonischemic controls. The degree of protection obtained by flushing kidneys with the isotonic phosphate-buffered sucrose solution plus ATP-MgCl2 is greater than that provided by any other single pretreatment or posttreatment for ischemia that is currently available. We, therefore, believe that the use of this procedure can provide a valuable approach to surgical situations in which postischemic acute renal failure is a potential problem.

Dentine hypersensitivity

Reports received from 32 dentists on the effect of a complex mixture of calcium sucrose phosphate and calcium orthophosphate used as a gel, toothpaste, or slurry in relieving pain in hypersensitive dentine show, in 137 patients, complete relief in 112. It was found that in 54 patients the prior use of stannous fluoride prophylactic paste was beneficial.

Effect of the interferon inducer, dextran phosphate, on influenza virus infection in mice

Intraperitoneal administration of dextran phosphate (MW 40,000) or DP 40, an interferon inducer, was shown to increase the survival rate of mice infected with 10 LD50 dose of influenza A2 virus (H2N2). In the treated mice, a 1-day delay was evident in the virus growth in lung, and production of HAI antibody, when compared to the nontreated or dextran-treated controls. More significant was the 2-day delay in the development of lung consolidation, which leads to 40% survival of the treated mice. Mediation of the protection by the interferon induced by DP 40 was indicated.