RETRACTED ARTICLE: Nafamostat mesilate inhibits the expression of HMGB1 in lipopolysaccharide-induced acute lung injury

Prognostic value of the lactate/albumin ratio for predicting mortality in patients with pneumosepsis in intensive care units

The lactate/albumin (L/A) ratio correlates with Acute Physiology and Chronic Health Evaluation 2 (APACHE-2) and Sequential Organ Failure Assessment (SOFA) scores. This study examined whether the L/A ratio has prognostic value in a larger group of critically ill (adult) patients admitted to an intensive care unit (ICU) due to pneumosepsis.This retrospective study analyzed the data of 273 patients with pneumosepsis admitted to the Internal Medicine ICU of Adana City Training and Research Hospital between 2018 and 2020. Patients diagnosed with pneumosepsis were included in the study. The data were obtained from the hospital system. Patients who had cancer, who were pregnant, and patients whose necessary data could not obtain for the study were excluded from the study.The L/A ratio was superior to lactate or albumin alone as a predictor of mortality. Furthermore, this result was valid for patients with kidney and hepatic dysfunction. A correlation occurred between the L/A ratio and APACHE-2 and SOFA scores in patients with pneumosepsis.The L/A ratio can be an independent predictor of mortality in patients with pneumosepsis and patients with pneumosepsis with renal and hepatic dysfunction. The L/A ratio correlated positively with lactate levels and APACHE-2 and SOFA scores but negatively with albumin levels.

Agonist of PPAR-γ Reduced Epithelial-Mesenchymal Transition in Eosinophilic Chronic Rhinosinusitis with Nasal Polyps via Inhibition of High Mobility Group Box1

Epithelial-mesenchymal transition (EMT) has been reported to occur in eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP). Among the cytokines that cause EMT, high mobility group box 1 (HMGB1) has been shown to give rise to EMT in airway epithelial cells. However, the mechanism of HMGB1-induced EMT in ECRSwNP is unknown. We explored the mechanism and possible inhibitor. Immunohistochemistry (IHC), immunofluorescence (IF), and western blot assay were used to detect the expression and location of HMGB1, peroxisome proliferator-activated receptor-γ (PPAR-γ), and EMT markers in eighteen ECRSwNP and twelve normal nasal mucosa tissues. Epithelial cells isolated from ECRSwNP were cultured with various doses of recombinant human HMGB1 (rhHMGB1) to study the expression of PPAR-γ, and EMT markers. Additionally, the ligand of PPAR-γ was incubated with epithelial cells to interfere with the effects of lipopolysaccharide (LPS) or rhHMGB1 to explore the effect on expression of HMGB1 and EMT markers. These results suggest that HMGB1 was highly expressed in ECRSwNP compared with its expression in control tissues, and EMT was also found highly in ECRSwNP compared with control tissues. Moreover, the cytoplasmic accumulation of HMGB1 in ECRSwNP was obvious compared with normal tissues. We also found dose-dependent induction by rhHMGB1 of up-regulation of N-cadherin and vimentin and down-regulation of ZO-1 and E-cadherin in epithelial cells isolated from ECRSwNP. The agonist of PPAR-γ not only reduced release of HMGB1 induced by LPS, but also reversed the EMT. The protective role of PPAR-γ also appeared in cells that had been incubated with rhHMGB1. In the current study, we discovered that the agonist of PPAR-γ has a potential role in inhibited HMGB1-induced EMT in ECRSwNP. The agonist of PPAR-γ may contribute to inhabit epithelial cells to become mesenchymal-like cells which play an important role in the pathogenesis of ECRSwNP.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

Profiling drug-induced cell death pathways in the zebrafish lateral line

Programmed cell death (PCD) is an important process in development and disease, as it allows the body to rid itself of unwanted or damaged cells. However, PCD pathways can also be activated in otherwise healthy cells. One such case occurs in sensory hair cells of the inner ear following exposure to ototoxic drugs, resulting in hearing loss and/or balance disorders. The intracellular pathways that determine if hair cells die or survive following this or other ototoxic challenges are incompletely understood. We use the larval zebrafish lateral line, an external hair cell-bearing sensory system, as a platform for profiling cell death pathways activated in response to ototoxic stimuli. In this report the importance of each pathway was assessed by screening a custom cell death inhibitor library for instances when pathway inhibition protected hair cells from the aminoglycosides neomycin or gentamicin, or the chemotherapy agent cisplatin. This screen revealed that each ototoxin likely activated a distinct subset of possible cell death pathways. For example, the proteasome inhibitor Z-LLF-CHO protected hair cells from either aminoglycoside or from cisplatin, while D-methionine, an antioxidant, protected hair cells from gentamicin or cisplatin but not from neomycin toxicity. The calpain inhibitor leupeptin primarily protected hair cells from neomycin, as did a Bax channel blocker. Neither caspase inhibition nor protein synthesis inhibition altered the progression of hair cell death. Taken together, these results suggest that ototoxin-treated hair cells die via multiple processes that form an interactive network of cell death signaling cascades.

An overview on HMGB1 inhibitors as potential therapeutic agents in HMGB1-related pathologies

HMGB1 (High-Mobility Group Box-1) is a nuclear protein that acts as an architectural chromatin-binding factor involved in the maintenance of nucleosome structure and regulation of gene transcription. It can be released into the extracellular milieu from immune and non-immune cells in response to various stimuli. Extracellular HMGB1 contributes to the pathogenesis of numerous chronic inflammatory and autoimmune diseases, including sepsis, rheumatoid arthritis, atherosclerosis, chronic kidney disease, systemic lupus erythematosus (SLE), as well as cancer pathogenesis. Interaction of released HMGB1 with the cell-surface receptor for advanced glycation end products (RAGE) is one of the main signaling pathways triggering these diseases. It has been also demonstrated that the inhibition of the HMGB1-RAGE interaction represents a promising approach for the modulation of the inflammatory and tumor-facilitating activity of HMGB1. In this review we describe various approaches recently proposed in the literature to inhibit HMGB1 and the related inflammatory processes, especially focusing on the block of RAGE-HMGB1 signaling. Several strategies are based on molecules which mainly interact with RAGE as competitive antagonists of HMGB1. As an alternative, encouraging results have been obtained with HMGB1-targeting, leading to the identification of compounds that directly bind to HMGB1, ranging from small natural or synthetic molecules, such as glycyrrhizin and gabexate mesilate, to HMGB1-specific antibodies, peptides, proteins as well as bent DNA-based duplexes. Future perspectives are discussed in the light of the overall body of knowledge acquired by a large number of research groups operating in different but related fields.

Gene expression analysis of clams Ruditapes philippinarum and Ruditapes decussatus following bacterial infection yields molecular insights into pathogen resistance and immunity

The carpet shell clam (Ruditapes decussatus) and Manila clam (Ruditapes philippinarum), which are cultured bivalve species with important commercial value, are affected by diseases that result in large economic losses. Because the molecular mechanism of the immune response of bivalves, especially clams, is scarce and fragmentary, we have examined all Expressed Sequence Tags (EST) resources available in public databases for these two species in order to increase our knowledge on genes related with the immune function in these animals. After automatic annotation and classification of the 3784 not-annotated ESTs of R. decussatus and 4607 of R. philippinarum found in GenBank, 424 ESTs of R. decussatus and 464 of R. philippinarum were found to be putatively involved in immune response. These were carefully reviewed and reannotated. As a result, 13 immune-related ESTs were selected and studied to compare the immune response of R. decussatus and R. philippinarum following a Vibrio alginolyticus challenge. Quantitative PCR was performed, and the expression of each EST was determined. The results showed that, in R. philippinarum, the immune response seems to be faster than that in R. decussatus. Additionally, expression of NF-κB activating genes in R. decussatus did not seem to be sufficient to promote an immune response after Vibrio infection. R. philippinarum, however, was able to trigger and efficiently regulate the transcriptional activity of NF-κB, even when low expression values were reported.

Low-molecular-weight heparin reduces hyperoxia-augmented ventilator-induced lung injury via serine/threonine kinase-protein kinase B

Background

High-tidal-volume mechanical ventilation and hyperoxia used in patients with acute lung injury (ALI) can induce the release of cytokines, including high-mobility group box-1 (HMGB1), oxygen radicals, neutrophil infiltration, and the disruption of epithelial and endothelial barriers. Hyperoxia has been shown to increase ventilator-induced lung injury, but the mechanisms regulating interaction between high tidal volume and hyperoxia are unclear. We hypothesized that subcutaneous injections of enoxaparin would decrease the effects of hyperoxia on high-tidal-volume ventilation-induced HMGB1 production and neutrophil infiltration via the serine/threonine kinase/protein kinase B (Akt) pathway.

Methods

Male C57BL/6, either wild type or Akt^+/-, aged between 6 and 8 weeks, weighing between 20 and 25 g, were exposed to high-tidal-volume (30 ml/kg) mechanical ventilation with room air or hyperoxia for 2 to 8 hours with or without 4 mg/kg enoxaparin administration. Nonventilated mice served as a control group. Evan blue dye, lung wet-to-dry weight ratio, free radicals, myeloperoxidase, Western blot of Akt, and gene expression of HMGB1 were measured. The expression of HMGB1 was studied by immunohistochemistry.

Results

High-tidal-volume ventilation using hyperoxia induced microvascular permeability, Akt activation, HMGB1 mRNA expression, neutrophil infiltration, oxygen radicals, HMGB1 production, and positive staining of Akt in bronchial epithelium. Hyperoxia-induced augmentation of ventilator-induced lung injury was attenuated with Akt deficient mice and pharmacological inhibition of Akt activity by enoxaparin.

Conclusion

These data suggest that enoxaparin attenuates hyperoxia-augmented high-tidal-volume ventilation-induced neutrophil influx and HMGB1 production through inhibition of the Akt pathway. Understanding the protective mechanism of enoxaparin related with the reduction of HMGB1 may help further knowledge of the effects of mechanical forces in the lung and development of possible therapeutic strategies involved in acute lung injury.

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.

Biphasic regulation of tissue plasminogen activator activity in ischemic rat brain and in cultured neural cells: essential role of astrocyte-derived plasminogen activator inhibitor-1

In brain, the serine protease tissue plasminogen activator (tPA) and its endogenous inhibitor plasminogen activator inhibitor-1 (PAI-1) have been implicated in the regulation of various neurophysiological and pathological responses. In this study, we investigated the differential role of neurons and astrocytes in the regulation of tPA/PAI-1 activity in ischemic brain. The activity of tPA peaked transiently and then decreased in cortex and striatum along with delayed induction of PAI-1 in the inflammatory stage after MCAO/reperfusion injury. In cultured primary cells, glutamate stimulation increased tPA activity in neurons but not in other cells such as microglia and astrocytes. With LPS stimulation, a model of neuroinflammatory insults, robust PAI-1 induction was observed in astrocytes but not in neurons and microglia. The upregulation of PAI-1 by LPS in astrocytes was also verified by RT-PCR analysis as well as PAI-1 promoter reporter assay. Lastly, we checked the effects of hypoxia on tPA/PAI-1 activity. Hypoxia increased tPA release from neurons without effects on microglia, while the activity of tPA in astrocyte was decreased consistent with increased PAI-1 activity in astrocyte. Taken together, the results from the present study suggest that neurons are the major source of tPA and that the glutamate-induced stimulated release is mainly governed by neurons in the acute phase. In contrast, the massive up-regulation of PAI-1 in astrocytes during subchronic and chronic inflammatory conditions, leads to decreased tPA activity in the later stages of MCAO. Differential regulation of tPA and PAI-1 in neurons, astrocytes and microglia suggest more attention is required to understand the role of local tPA activity in the vicinity of individual cell types.

Association of high mobility group box-1 protein levels with sepsis and outcome of severely burned patients

BACKGROUND

The study was performed to observe the systemic release and kinetics of high mobility group box-1 protein (HMGB1) in burned patients.

METHODS

106 patients were included, and they were divided into three groups with different burn sizes: group I, group II and group III. Healthy volunteers served as normal controls (n=25). The peripheral blood samples were collected on postburn days (PBD) 1, 3, 7, 14, and 21. The blood samples were used to detect levels of HMGB1 in plasma by ELISA kits for human. Gene expression of HMGB1 in peripheral blood mononuclear cells was assessed by real-time quantitative PCR taking GAPDH as the internal standard.

RESULTS

The levels of HMGB1 were significantly elevated on PBD 1-21 in patients with various burn sizes compared with normal controls, and there were obvious differences between group I and group III. The HMGB1 levels were significantly higher in septic patients than those without sepsis on PBD 7-21. Among septic patients, the HMGB1 levels in the survival group were markedly lower than those with fatal outcome on PBD 3-21.

CONCLUSIONS

Extensive burn injury could result in significantly increased HMGB1 levels, which appears to be associated with the development of sepsis and fatal outcome of major burns.

Role of Apoptosis in Amplifying Inflammatory Responses in Lung Diseases

Apoptosis is an important contributor to the pathophysiology of lung diseases such as acute lung injury (ALI) and chronic obstructive pulmonary disease (COPD). Furthermore, the cellular environment of these acute and chronic lung diseases favors the delayed clearance of apoptotic cells. This dysfunctional efferocytosis predisposes to the release of endogenous ligands from dying cells. These so-called damage-associated molecular patterns (DAMPs) play an important role in the stimulation of innate immunity as well as in the induction of adaptive immunity, potentially against autoantigens. In this review, we explore the role of apoptosis in ALI and COPD, with particular attention to the contribution of DAMP release in augmenting the inflammatory response in these disease states.

High-mobility-group box chromosomal protein 1 as a new target for modulating stress response

Major surgical procedures induce a systemic inflammatory response syndrome (SIRS) characterized by the overproduction of proinflammatory cytokines, which induces excessive stress and may trigger postoperative complications. This has prompted the hypothesis that drugs which relieve SIRS might improve the postoperative course of major surgery. One of the most promising targets for these drugs is high-mobility-group box chromosomal protein 1 (HMGB1). In 1999, HMGB1 was found to be a key late mediator of sepsis. It is now known to be associated with various kinds of acute and chronic inflammation, and is recognized as one of the most important danger signals in stress response. In this article, we present the latest information about HMGB1 and discuss its promise as a novel target for modulating stress response.