Heparin-binding protein (HBP/CAP37) - a link to endothelin-1 in endotoxemia-induced pulmonary oedema?

The value of heparin-binding protein in bronchoalveolar lavage fluid in acute respiratory distress syndrome

Background

Heparin-binding protein (HBP) is recognized as a significant factor in the development of Acute Respiratory Distress Syndrome (ARDS). Although plasma levels of HBP have been identified as a predictive biomarker for ARDS, the role and value of HBP in bronchoalveolar lavage fluid (BALF) remain unexplored.

Methods

Our study utilized a cecum ligation and puncture (CLP) method to induce an ARDS model in mice, examining the correlations between plasma and BALF HBP levels, lung injury severity, lung wet-to-dry (WD) ratio, and BALF total protein levels. Additionally, we conducted a comparative analysis of BALF and plasma HBP levels in 44 ARDS patients and 38 patients with cardiogenic pulmonary edema (CPE), investigating their correlations.

Results

In the animal study, CLP-induced mice demonstrated significantly higher lung WD ratios, BALF protein, BALF HBP, and plasma HBP levels compared to the control group. Notably, both BALF and plasma HBP levels were significantly correlated with lung injury severity. In human subjects, significant differences in BALF HBP, BALF protein, and plasma HBP levels were observed between ARDS and CPE patients, along with notable correlations between these markers and the severity of lung injury. Particularly, BALF HBP levels exhibited a stronger correlation with lung injury compared to plasma HBP levels.

Conclusion

The study indicates that both BALF and plasma HBP levels are significantly elevated in the context of lung injury in both animal models and human ARDS patients. More importantly, BALF HBP levels show a stronger correlation with the severity of lung injury, suggesting that BALF HBP could serve as a valuable biomarker for diagnosing and guiding the treatment of ARDS.

Transforming growth factor-β receptor type 2 is required for heparin-binding protein-induced acute lung injury and vascular leakage for transforming growth factor-β/Smad/Rho signaling pathway activation

Heparin-binding protein (HBP), as a granule protein secreted by polymorphonuclear neutrophils, participates in the pathophysiological process of sepsis. It has been reported that HBP is a biomarker of sepsis related to the severity of septic shock and organ dysfunction. HBP binds to vascular endothelial cells as a primary target site. However, it is still unclear whether HBP-binding protein receptors exist on the surface of endothelial cells. The effect of HBP on vascular permeability in sepsis and its mechanism needs to be explored. We conducted in vivo and in vitro studies and demonstrated that HBP binds to transforming growth factor-β receptor type 2 (TGF-β-R2) as a ligand. Glutathione S-transferase pull-down analysis revealed that HBP mainly interacts with the extracellular domain of TGF-β-R2. HBP induces acute lung injury and vascular leakage via activation of the TGF-β/SMAD2/3 signaling pathway. A permeability assay suggested that TGF-β-R2 is necessary for HBP-induced increased permeability. We also defined the role of HBP and its potential membrane receptor TGF-β-R2 in the blood-gas barrier in the pathogenesis of HBP-related acute lung injury.

Neutrophil-derived heparin binding protein triggers vascular leakage and synergizes with myeloperoxidase at the early stage of severe burns (With video)

Background

Burn shock caused by vascular leakage is one of the main causes of high mortality in severe burn injury. However, the pathophysiological mechanism of vascular leakage is still unclear. The purpose of this study was to explore the molecular mechanism of vascular leakage in the early stage of severe burn and provide a new target for the treatment of severe burns.

Methods

Neutrophils were isolated from human peripheral blood by magnetic beads sorting. ELISA was used to detect neutrophil-derived granule proteins and glycocalyx injury products in plasma. The vascular leakage and neutrophil movement were assessed by in vivo laser confocal imaging in mice, and high-quality video were provided.. Adhesion-related molecules were investigated by qRT-PCR. The damage to glycocalyx of mice vascular endothelial cells was observed by transmission electron microscope and scanning electron microscope. Proteomic analysis, flow cytometry and immunofluorescence were used to further study the relationship between human peripheral blood neutrophil-derived hypochlorite (HOCl) and CD44 of human vascular endothelial cells.

Results

In this study, we found that rapidly increasing activated neutrophils secrete heparin binding protein (HBP) and myeloperoxidase (MPO) after severe burn injury. Increased HBP triggers vascular leakage with synergy of MPO, results in systemic edema and burn shock. Furthermore, we found that the MPO catalytic product HOCl but not MPO triggers CD44 extracellular domain shedding from vascular endothelial cells to damage the glycocalyx. Damage to the glycocalyx results in firm adhesion of neutrophils and increases vascular leakage. However, MPO inhibitors partially protect the glycocalyx of vascular endothelial cells. The combination of HBP and MPO inhibitors markedly reduces vascular leakage and systemic edema in the early stage of severe burns.

Conclusions

Taken together, these data reveal that neutrophil-derived HBP and MPO play an important synergies role in triggering vascular leakage at the early stage of severe burns. Targeted intervention in these two biomolecules may introduce new strategies for helping to reduce large amount of fluid loss and subsequent burn shock.

Endothelin receptor antagonist improves donor lung function in an ex vivo perfusion system

BACKGROUND

A lung transplant is the last resort treatment for many patients with advanced lung disease. The majority of donated lungs come from donors following brain death (BD). The endothelin axis is upregulated in the blood and lung of the donor after BD resulting in systemic inflammation, lung damage and poor lung graft outcomes in the recipient. Tezosentan (endothelin receptor blocker) improves the pulmonary haemodynamic profile; however, it induces adverse effects on other organs at high doses. Application of ex vivo lung perfusion (EVLP) allows the development of organ-specific hormone resuscitation, to maximise and optimise the donor pool. Therefore, we investigate whether the combination of EVLP and tezosentan administration could improve the quality of donor lungs in a clinically relevant 6-h ovine model of brain stem death (BSD).

METHODS

After 6 h of BSD, lungs obtained from 12 sheep were divided into two groups, control and tezosentan-treated group, and cannulated for EVLP. The lungs were monitored for 6 h and lung perfusate and tissue samples were processed and analysed. Blood gas variables were measured in perfusate samples as well as total proteins and pro-inflammatory biomarkers, IL-6 and IL-8. Lung tissues were collected at the end of EVLP experiments for histology analysis and wet-dry weight ratio (a measure of oedema).

RESULTS

Our results showed a significant improvement in gas exchange [elevated partial pressure of oxygen (P = 0.02) and reduced partial pressure of carbon dioxide (P = 0.03)] in tezosentan-treated lungs compared to controls. However, the lungs hematoxylin-eosin staining histology results showed minimum lung injuries and there was no difference between both control and tezosentan-treated lungs. Similarly, IL-6 and IL-8 levels in lung perfusate showed no difference between control and tezosentan-treated lungs throughout the EVLP. Histological and tissue analysis showed a non-significant reduction in wet/dry weight ratio in tezosentan-treated lung tissues (P = 0.09) when compared to control.

CONCLUSIONS

These data indicate that administration of tezosentan could improve pulmonary gas exchange during EVLP.

A Promising Candidate: Heparin-Binding Protein Steps onto the Stage of Sepsis Prediction

Sepsis is a systemic inflammatory response syndrome caused by infection. With high morbidity and mortality of this disease, there is a need to find early effective diagnosis and assessment methods to improve the prognosis of patients. Heparin-binding protein (HBP) is a granular protein derived from polynuclear neutrophils. The biosynthetic HBP in neutrophils is rapidly released under the stimulation of bacteria, resulting in increased vascular permeability and edema. It is reasonable to speculate that the HBP in plasma may serve as a novel diagnostic marker for sepsis, bacterial skin infection, acute bacterial meningitis, leptospirosis, protozoan parasites, and even some noncommunicable diseases. It implies that in the detection and diagnosis of sepsis, it will be possible to make relevant diagnosis through this new indicator in the future. In this review, we summarize the typical biological function of HBP and its latest research progress to provide theoretical basis for clinical prediction and diagnosis of sepsis.

Usefulness of the heparin-binding protein level to diagnose sepsis and septic shock according to Sepsis-3 compared with procalcitonin and C reactive protein: a prospective cohort study in China

OBJECTIVES

Our aim was to assess the release level of heparin-binding protein (HBP) in sepsis and septic shock under the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3).

DESIGN

Prospective cohort study.

SETTING

A general teaching hospital in China.

PARTICIPANTS

Adult infected patients with suspected sepsis and people who underwent physical examination were included. According to the health status and severity of illness, the research subjects were divided into healthy, local infection, sepsis non-shock and septic shock under Sepsis-3 definitions.

MAIN OUTCOME MEASURES

Plasma levels of HBP, procalcitonin (PCT), C reactive protein (CRP) and complete blood count were detected in all subjects. Single-factor analysis of variance was used to compare the biomarker levels of multiple groups. A receiver operating characteristic (ROC) curve was used to assess the diagnostic capacity of each marker.

RESULTS

HBP levels were significantly higher in patients with sepsis non-shock than in those with local infections (median 49.7ng/mL vs 11.8 ng/mL, p<0.01) at enrolment. Moreover, HBP levels in patients with septic shock were significantly higher than in patients with sepsis without shock (median 153.8ng/mL vs 49.7 ng/mL, p<0.01). The area under the ROC curve (AUC) of HBP (cut-off ≥28.1 ng/mL) was 0.893 for sepsis which was higher than those of PCT (0.856) for a cut-off ≥2.05 ng/mL and of CRP (0.699) for a cut-off ≥151.9 mg/L. Moreover, AUC of HBP (cut-off ≥103.5 ng/mL) was 0.760 for septic shock which was higher than the ROC curve of sequential [sepsis-related] organ failure assessment (SOFA) Score (0.656) for a cut-off ≥5.5. However, there was no significant difference between 28-d survivors (n=56) and 28-d non-survivors (n=37) with sepsis in terms of HBP value (p=0.182).

CONCLUSIONS

A high level of HBP in plasma is associated with sepsis, which might be a useful diagnostic marker in patients with suspected sepsis.

Heparin-binding protein as a biomarker of post-injury sepsis in trauma patients

BACKGROUND

Heparin-binding protein (HBP) is a neutrophil-derived protein advocated as a biomarker in sepsis. We evaluated plasma HBP as a predictor of post-injury sepsis in trauma patients.

METHODS

Ninety-seven trauma patients were studied during the first week of intensive care. Injury-related data were collected and clinical parameters registered daily. Plasma HBP was sampled on day 1, 3 and 5 after trauma and evaluated for associations with injury-related parameters and sepsis. The predictive properties of HBP were compared to C-reactive protein (CRP) and white blood cell count (WBC).

RESULTS

Median Injury Severity Score was 33, one-third of the trauma patients received massive transfusion and a quarter was in shock on arrival. Overall 30-day mortality was 8%. Plasma HBP was significantly higher in severely injured patients and associated with shock on arrival, massive transfusions and organ failure. Septic patients had higher levels of HBP only on day 5. When evaluated for prediction of onset of sepsis during the two following days after plasma sampling by receiver operating characteristic (ROC) analyses, areas under the curves were non-significant for all time points. Similar patterns were seen for CRP and WBC.

CONCLUSION

In trauma patients, HBP levels are related to severity of injury and organ dysfunction. Heparin-binding protein was weakly associated with sepsis and only at the later stage of the observation period of 1 week. Moreover, HBP showed poor discriminatory properties as an early biomarker of post-injury sepsis. Trauma-induced inflammation during the post-injury phase may blunt the sepsis-predictive performance of HBP.

The role of β2 integrin associated heparin-binding protein release in ARDS

AIMS

PMNs (polymorphonuclear neutrophil) play important roles in early stage of inflammation induced ARDS (Acute Respiratory Distress Syndrome). Both HBP (Heparin-Binding Protein) released from active PMNs and β2 integrins on the surface of PMNs are involved in vascular leakage. The role and relationship of HBP and β2 integrins on ARDS still requires study.

MATERIALS AND METHODS

We established ARDS model using C57BL/6 mice with cecal ligation and puncture and eliminating HBP and β2 integrin with respective antibodies. The mice were also challenged with HBP endotracheal instillation. Histopathology score, lung wet/dry ratio, bronchoalveolar lavage fluid protein, plasma HBP and β2 integrin on PMNs from all groups were measured. β2 integrin and HBP were analyzed after incubated PMNs with streptococcal and pretreat with anti-CD18, anti-HBP, 1-phosphatidylinositol 3-kinase (PI3K) inhibitor and p38 mitogen-activated protein kinase (MAPK) inhibitor.

KEY FINDINGS

All lung injury indicatrix accompanied with HBP and β2 integrin elevated in CLP group, and HBP and β2 integrin were in correlation with each other and both were in correlation with the severity of lung injury. Endotracheal instillation HBP induced lung injury in CLP mice. Inhibiting both HBP and integrin ameliorated lung injury. HBP release was suppressed by inhibiting integrin and PI3K pathway, while integrin level did not decrease after eliminating HBP.

SIGNIFICANCE

Both HBP and β2 integrin play important roles in ARDS. HBP released from PMNs is β2 integrin-PI3K signaling pathway dependent process revealing potential novel therapeutic targets for ARDS treatment.

Cardiovascular dysfunction in sepsis at the dawn of emerging mediators

Subcellular dysfunction and impaired metabolism derived from the complex interaction of cytokines and mediators with cellular involvement are on the basis of the cardiovascular response to sepsis. The lethal consequences of an infection are intimately related to its ability to spread to other organ sites and the immune system of the host. About one century ago, William Osler (1849-1919), a Canadian physician, remarkably defined the sequelae of the host response in sepsis: "except on few occasions, the patient appears to die from the body's response to infection rather than from it." Cardiac dysfunction has received considerable attention to explain the heart failure in patients progressing from infection to sepsis, but our understanding of the processes remains limited. In fact, most concepts are linked to a mechanical concept of the sarcomeric structure, and physiological data seems to be often disconnected. Cytokines, prostanoids, and nitric oxide release are high direct impact factors, but coronary circulation and cardiomyocyte physiology also play a prominent role in modulating the effects of monocyte adhesion and infiltration. Damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs) are involved in the host response. The identification of microRNAs, as well as the cyclic activation of the inflammatory cascade, has further added complexity to the scene. In this review, we delineate the current concepts of cellular dysfunction of the cardiomyocyte in the setting of sepsis and consider potential therapeutic strategies.

Heparin-binding protein: a key player in the pathophysiology of organ dysfunction in sepsis

Infectious diseases remain a major health problem, and sepsis and other severe infectious diseases are common causes of morbidity and mortality. There is a need for clinical and laboratory tools to identify patients with severe infections early and to distinguish between bacterial and nonbacterial conditions. Heparin-binding protein (HBP), also known as azurocidin or cationic antimicrobial protein of 37 KDa, is a promising biomarker to distinguish between patients with these conditions. It is biologically plausible that HBP is an early and predictive biomarker because it is prefabricated and rapidly mobilized from migrating neutrophils in response to bacterial infections. HBP induces vascular leakage and oedema formation and has a pro-inflammatory effect on a variety of white blood cells and epithelial cells. The dysregulation of vascular barrier function and cellular inflammatory responses can then lead to organ dysfunction. Indeed, it has been shown that patients with sepsis express elevated levels of HBP in plasma several hours before they develop hypotension or organ dysfunction. HBP has a major role in the pathophysiology of severe bacterial infections and thus represents a potential diagnostic marker and a target for the treatment of sepsis.

Increased Plasma Levels of Heparin-Binding Protein on Admission to Intensive Care Are Associated with Respiratory and Circulatory Failure

Purpose

Heparin-binding protein (HBP) is released by granulocytes and has been shown to increase vascular permeability in experimental investigations. Increased vascular permeability in the lungs can lead to fluid accumulation in alveoli and respiratory failure. A generalized increase in vascular permeability leads to loss of circulating blood volume and circulatory failure. We hypothesized that plasma concentrations of HBP on admission to the intensive care unit (ICU) would be associated with decreased oxygenation or circulatory failure.

Methods

This is a prospective, observational study in a mixed 8-bed ICU. We investigated concentrations of HBP in plasma at admission to the ICU from 278 patients. Simplified acute physiology score (SAPS) 3 was recorded on admission. Sequential organ failure assessment (SOFA) scores were recorded daily for three days.

Results

Median SAPS 3 was 58.8 (48–70) and 30-day mortality 64/278 (23%). There was an association between high plasma concentrations of HBP on admission with decreased oxygenation (p<0.001) as well as with circulatory failure (p<0.001), after 48–72 hours in the ICU. There was an association between concentrations of HBP on admission and 30-day mortality (p = 0.002). ROC curves showed areas under the curve of 0,62 for decreased oxygenation, 0,65 for circulatory failure and 0,64 for mortality.

Conclusions

A high concentration of HBP in plasma on admission to the ICU is associated with respiratory and circulatory failure later during the ICU care period. It is also associated with increased 30-day mortality. Despite being an interesting biomarker for the composite ICU population it´s predictive value at the individual patient level is low.

The role of endothelin-1 and endothelin receptor antagonists in inflammatory response and sepsis

Endothelin-1 (ET-1) is a potent endogenous vasoconstrictor, mainly secreted by endothelial cells. It acts through two types of receptors: ETA and ETB. Apart from a vasoconstrictive action, ET-1 causes fibrosis of the vascular cells and stimulates production of reactive oxygen species. It is claimed that ET-1 induces proinflammatory mechanisms, increasing superoxide anion production and cytokine secretion. A recent study has shown that ET-1 is involved in the activation of transcription factors such as NF-κB and expression of proinflammatory cytokines including TNF-α, IL-1, and IL-6. It has been also indicated that during endotoxaemia, the plasma level of ET-1 is increased in various animal species. Some authors indicate a clear correlation between endothelin plasma level and morbidity/mortality rate in septic patients. These pathological effects of ET-1 may be abrogated at least partly by endothelin receptor blockade. ET-1 receptor antagonists may be useful for prevention of various vascular diseases. This review summarises the current knowledge regarding endothelin receptor antagonists and the role of ET-1 in sepsis and inflammation.