Nafamostat mesilate inhibits high-mobility group box 1 by lipopolysaccharide stimulation in murine macrophage RAW 264.7

Pathophysiological dynamics in the contact, coagulation, and complement systems during sepsis: Potential targets for nafamostat mesilate

Sepsis is a life-threatening syndrome resulting from a dysregulated host response to infection. It is the primary cause of death in the intensive care unit, posing a substantial challenge to human health and medical resource allocation. The pathogenesis and pathophysiology of sepsis are complex. During its onset, pro-inflammatory and anti-inflammatory mechanisms engage in intricate interactions, possibly leading to hyperinflammation, immunosuppression, and long-term immune disease. Of all critical outcomes, hyperinflammation is the main cause of early death among patients with sepsis. Therefore, early suppression of hyperinflammation may improve the prognosis of these patients. Nafamostat mesilate is a serine protease inhibitor, which can inhibit the activation of the complement system, coagulation system, and contact system. In this review, we discuss the pathophysiological changes occurring in these systems during sepsis, and describe the possible targets of the serine protease inhibitor nafamostat mesilate in the treatment of this condition.

High-mobility group box 1 is a driver of inflammation throughout pregnancy

A proinflammatory response driven by high-mobility group box 1 (HMGB1) is important for the success of both the early stages of pregnancy and parturition initiation. However, the tight regulation of HMGB1 within these two stages is critical, as increased HMGB1 can manifest into pregnancy-related pathologies. Although during the early stages of pregnancy HMGB1 is critical for the development and implantation of the embryo, and uterine decidualization, high levels within the uterine cavity have been linked to pregnancy failure. In addition, chronic inflammation, resultant from increased HMGB1 within the maternal circulation and gestational tissues, also increases the risk for preterm labor, preterm birth, or infant mortality. Due to the link between HMGB1 and several pregnancy pathologies, the possibility of leveraging HMGB1 as a biomarker has been assessed. However, data are limited that demonstrate how known HMGB1 inhibitors could reduce inflammation within pregnancy. Thus, further research is warranted to improve our understanding of the potential of HMGB1 as a therapeutic target to reduce inflammation within pregnancy. This review aims to describe what is understood about the role of HMGB1 that drives inflammation throughout pregnancy and highlight its potential as a biomarker and therapeutic target within this context.

Nafamostat mesylate attenuates the pathophysiologic sequelae of neurovascular ischemia

Nafamostat mesylate, an apparent soi-disant panacea of sorts, is widely used to anticoagulate patients undergoing hemodialysis or cardiopulmonary bypass, mitigate the inflammatory response in patients diagnosed with acute pancreatitis, and reverse the coagulopathy of patients experiencing the commonly preterminal disseminated intravascular coagulation in the Far East. The serine protease inhibitor nafamostat mesylate exhibits significant neuroprotective effects in the setting of neurovascular ischemia. Nafamostat mesylate generates neuroprotective effects by attenuating the enzymatic activity of serine proteases, neuroinflammatory signaling cascades, and the endoplasmic reticulum stress responses, downregulating excitotoxic transient receptor membrane channel subfamily 7 cationic currents, modulating the activity of intracellular signal transduction pathways, and supporting neuronal survival (brain-derived neurotrophic factor/TrkB/ERK1/2/CREB, nuclear factor kappa B. The effects collectively reduce neuronal necrosis and apoptosis and prevent ischemia mediated disruption of blood-brain barrier microarchitecture. Investigational clinical applications of these compounds may mitigate ischemic reperfusion injury in patients undergoing cardiac, hepatic, renal, or intestinal transplant, preventing allograft rejection, and treating solid organ malignancies. Neuroprotective effects mediated by nafamostat mesylate support the wise conduct of randomized prospective controlled trials in Western countries to evaluate the clinical utility of this compound.

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

Toraymyxin^® is a medical device developed to adsorb circulating endotoxins in the blood using direct hemoperfusion therapy for patients with septic shock. In 1994, the Japanese National Health Insurance system approved the use of Toraymyxin for the treatment of endotoxemia and septic shock. Since then, Toraymyxin has been safely used in more than 100,000 cases in emergency and intensive care units in Japan. Toraymyxin is currently available for use in the clinical setting in 14 countries worldwide. In this study, we reviewed and introduced the development, clinical use, and efficacy of Toraymyxin and commented on its anticoagulant use and cartridge clotting issue in the treatment of severe sepsis and septic shock. We also highlighted potential new applications of Toraymyxin for longer duration therapy and pulmonary diseases.

Novel insights for high mobility group box 1 protein-mediated cellular immune response in sepsis: A systemic review

BACKGROUND

High mobility group box 1 protein (HMGB1) is a highly conserved, ubiquitous protein in the nuclei and cytoplasm of nearly all cell types. HMGB1 is secreted into the extracellular milieu and acts as a proinfl ammatory cytokine. In this article we reviewed briefl y the cellular immune response mediated by HMGB1 in infl ammation and sepsis.

METHODS

This systemic review is mainly based on our own work and other related reports.

RESULTS

HMGB1 can actively affect the immune functions of many types of cells including T lymphocytes, regulatory T cells (Tregs), dendritic cells (DCs), macrophages, and natural killer cells (NK cells). Various cellular responses can be mediated by HMGB1 which binds to cell-surface receptors [e.g., the receptor for advanced glycation end products (RAGE), Toll-like receptor (TLR)2, and TLR4]. Anti-HMGB1 treatment, such as anti-HMGB1 polyclonal or monoclonal antibodies, inhibitors (e.g., ethyl pyruvate) and antagonists (e.g., A box), can protect against sepsis lethality and give a wider window for the treatment opportunity.

CONCLUSION

HMGB1 is an attractive target for the development of new therapeutic strategies in the treatment of patients with septic complications.

Nafamostat mesylate, a serine protease inhibitor, demonstrates novel antimicrobial properties and effectiveness in Chlamydia-induced arthritis

Introduction

Effective treatment of reactive arthritis would ideally achieve both control of inflammation and eradication of persisting arthritogenic pathogens. We use a model of experimental Chlamydia trachomatis-induced arthritis (CtIA) to evaluate the effectiveness of nafamostat mesilate (NM), a serine protease inhibitor with complement-modifying effects and anticoagulant properties. To date clinical use of NM has largely been in Asia and has been primarily confined to inflammatory states such as pancreatitis.

Methods

In vitro studies examined inhibition of Chlamydia proliferation using fibroblast cell lines as targets and phase contrast microscopy. In vivo studies used an established protocol, experimental CtIA, induced in Lewis rats by injection of synoviocyte-packaged C. trachomatis. NM was dissolved in water and administered by daily intraperitoneal injection at a dose of 10 mg/kg beginning the day prior to the administration of Chlamydia. Readouts in vivo included (i) joint swelling, (ii) histopathology scoring of severity of arthritis, (iii) host clearance of the pathogen (by ELISA, the IDEIA PCE Chlamydia).

Results

NM exerted a dose-dependent inhibition of chlamydial proliferation in vitro. Without NM, the mean number of inclusion bodies (IB) per well was 17,886 (± 1415). At 5 μg/mL NM, there were 8,490 (± 756) IB, at 25 μg/mL NM there were 35 IB and at 50 μg/mL NM no IB was observed. Chlamydial antigens in each well along the concentration gradient were assayed by ELISA, demonstrating that at 25 μg/mL NM inhibition of Chlamydia was almost complete. In the experimental arthritis model, joint swelling was significantly reduced with NM treatment: average joint width for the NM-treated animals was 8.55 mm (s.d. ± 0.6578, n = 10) versus 11.18 mm (s.d. ± 0.5672, n = 10) in controls (P < 0.001). Histopathology scoring indicated that NM resulted in a marked attenuation of the inflammatory infiltration and joint damage: mean pathology score in NM-treated animals was 10.9 (± 2.45, n = 11) versus 15.9 (± 1.45, n = 10) in controls (P < 0.0001). With respect to persistence of Chlamydia within the synovial tissues, NM treatment was accompanied by a reduction in the microbial load in the joint: mean optical density (O.D.) for ELISA with NM treatment was 0.05 (± 0.02, n = 4) versus 0.18 (± 0.05, n = 4) in controls (P < 0.001).

Conclusions

NM is a protease inhibitor not previously recognized to possess antimicrobial properties. The present study demonstrates for the first time that NM exerts significant impact on C. trachomatis-induced arthritis and suggests that such approaches may prove clinically useful in chronic reactive arthritis.

RNA interference inhibits high mobility group box 1 by lipopolysaccharide-activated murine macrophage RAW 264.7 secretion

BACKGROUND

This study aims to evaluate the influence of RNA interference (RNAi) on the high mobility group box 1 (HMGB-1) in the lipopolysaccharide (LPS)-induced murine macrophage cell line RAW 264.7.

MATERIALS AND METHODS

In order to observe the effect of RNAi on HMGB-1, tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and transforming growth factor β (TGF-β) levels, the RAW 264.7 cell line was divided into five treatment groups to measure separately as a function of time of negative control, LPS stimulation only, LPS + HMGB-1 short interfering RNAs (siRNAs), LPS + negative control siRNAs (siNC), and LPS + nafamostat mesilate (NM).

RESULTS

Measurement does show HMGB-1 expression in the LPS-activated macrophages in an explicit time-dependent manner. The HMGB-1 cellular level is consistently knocked down 80%∼85% by the siRNA; TNF-α, IL-6, and TGF-β levels in turn significantly decrease following siRNA delivery to the inflammatory response. HMGB-1 expression is lower in the LPS + NM group than the LPS + HMGB-1 siRNA group at the initial stage, however, a significantly lower level of HMGB-1 in the siRNA group is observed 48 h later. The decrease of TNF-α, IL-6, and TGF-β levels in the LPS-induced inflammatory response is also observed in both groups.

CONCLUSIONS

Our results demonstrate that HMGB-1 RNAi treatment of LPS-stimulated macrophages inhibit HMGB-1 and remarkably reduce the LPS-induced inflammatory responses. Hence, RNAi is highly recommended as a potential candidate for a new therapeutic strategy to minimize or, to a lesser extent, prevent the LPS-induced inflammatory injury.

Human atrial natriuretic peptide ameliorates LPS-induced acute lung injury in rats

Acute lung injury, a common component of systemic inflammatory disease, is a life-threatening condition without many effective treatments. However, recent studies have demonstrated that the multifunctional human atrial natriuretic peptide (hANP) exerts anti-inflammatory effects. Therefore, we tested the hypothesis that hANP could prevent lipopolysaccharide (LPS)-induced acute lung injury in a rodent model. Rats received an LPS injection and continuous intravenous infusion (CIV) of hANP or saline solution. We evaluated the anti-inflammatory effects of hANP by histological examination and determination of serum cytokine levels and lung myeloperoxidase (MPO) activity. Histological examination revealed marked reductions in interstitial congestion, edema, inflammation, and hemorrhage in lung tissue harvested 12 h after hANP treatment compared with tissue from rats that received saline treatment after LPS. LPS injection induced elevated cytokine (IL-1beta and IL-6) secretion and lung MPO activity, which was also attenuated by hANP treatment. Taken together, these data demonstrate that hANP exerts an anti-inflammatory effect and may have potential as a therapeutic agent to treat systemic inflammatory diseases.

Bench-to-bedside review: High-mobility group box 1 and critical illness

High-mobility group box 1 (HMGB1) is a DNA-binding protein that also exhibits proinflammatory cytokine-like activity. HMGB1 is passively released by necrotic cells and also is actively secreted by immunostimulated macrophages, dendritic cells, and enterocytes. Although circulating HMGB1 levels are increased relative to healthy controls in patients with infections and severe sepsis, plasma or serum HMGB1 concentrations do not discriminate reliably between infected and uninfected critically ill patients. Nevertheless, administration of drugs that block HMGB1 secretion or of anti-HMGB1 neutralizing antibodies has been shown to ameliorate organ dysfunction and/or improve survival in numerous animal models of critical illness. Because HMGB1 tends to be released relatively late in the inflammatory response (at least in animal models of endotoxemia or sepsis), this protein is an attractive target for the development of new therapeutic agents for the treatment of patients with various forms of critical illness.