Plasma angiopoietin 2 concentrations are related to impaired lung function and organ failure in a clinical cohort receiving high-dose interleukin 2 therapy

Circulating angiopoietin-2 and the risk of mortality in patients with acute respiratory distress syndrome: a systematic review and meta-analysis of 10 prospective cohort studies

BACKGROUND

Angiopoietin-2 (Ang-2), as one of the ligands of endothelial receptor Tie2, is known to be significant for vessel maturation and stabilization after birth. Previous studies showed the relationship between Ang-2 level and the risk of mortality in patients with acute respiratory distress syndrome (ARDS). However, the link between circulating Ang-2 and the risk of mortality in patients with ARDS varied in different investigations.

RESULTS

We performed a systematic review and meta-analysis of all available cohort studies regarding the association between baseline circulating Ang-2 and mortality in patients with ARDS. Among the 10 eligible studies, pooled odds ratio (OR) showed that high Ang-2 level contributed to ARDS mortality [OR = 1.56, 95% confidence interval (CI): 1.30-1.89, I² = 76.2%]. Stratified analysis revealed that higher circulating Ang-2 was related to a 30% higher risk in the high-quality scores group (OR = 1.68, 95% CI: 1.33-2.68, I² = 62.4%). The I² of the bad compliance group decreased from 76.2% to 8.5%, which suggested that compliance is a significant source of heterogeneity. This association may be blunted by potential bias, although the results was not meaningfully changed by omitting only one study at a time. Further subgroup analysis and meta-regression support that compliance of patients also affects the results significantly, compared with the publication year, follow-up duration, the samples, or population characteristics.

CONCLUSION

Participants with higher baseline Ang-2 were at a higher risk for future risk of mortality in patients with ARDS. Higher circulating Ang-2 levels could independently predict the risk of mortality in patients with ARDS. However, further large scale prospective cohorts or even interventional studies are warranted to evaluate the diagnostic power of Ang-2 and its causative role on ARDS outcome. The reviews of this paper are available via the supplemental material section.

The VE-PTP Inhibitor AKB-9778 Improves Antitumor Activity and Diminishes the Toxicity of Interleukin 2 (IL-2) Administration

Administration of interleukin (IL)-2 has led to a durable response in patients with advanced renal cancer and melanoma but is restricted for clinical application because of adverse effects, including the vascular leak syndrome (VLS). VLS is associated with increased circulating levels of the Tie2 antagonist ligand, angiopoietin 2, and decreased Tie2 receptor phosphorylation and downstream signaling in endothelial cells (ECs). Given that vascular endothelial protein tyrosine phosphatase (VE-PTP) is a specific membrane phosphatase in ECs that dephosphorylates Tie2, the effects of targeting VE-PTP by a selective inhibitor AKB-9778 (AKB) in terms of VLS and antitumor efficacy were examined in this study. The authors found, by targeting VE-PTP, that the antitumor effects induced by IL-2 were augmented [tumor-free 44% (IL-2 alone) vs. 87.5% (IL-2+AKB)], associated with enhanced immune cell infiltrate (90% increase for CD8 T cells and natural killer cells). In addition, the side effects of IL-2 therapy were lessened, as demonstrated by diminished lung weight (less vascular leakage) as well as reduced cytokine levels (serum HMGB1 from 137.04±2.69 to 43.86±3.65 pg/mL; interferon-γ from 590.52±90.52 to 31.37±1.14 pg/mL). The authors further sought to determine the potential mechanism of the action of AKB-9778. The findings suggest that AKB-9778 may function through reducing serum angiopoietin 2 level and regulating EC viability. These findings provide insights into the targeting VE-PTP to improve tolerance and efficacy of IL-2 therapy and highlight the clinical potential of AKB-9778 for treating patients with VLS and cancer.

T cell-directed IL-17 production by lung granular γδ T cells is coordinated by a novel IL-2 and IL-1β circuit

Immune-mediated lung is considered the result of an exacerbated innate injury immune response, although a role for adaptive lymphocytes is emerging. αβ T cells specific for S. aureus enterotoxin A orchestrate a Tγδ17 response during lung injury. However, the mechanism driving IL-17 production is unclear. Here, we show a role for IL-2 triggering IL-17 production by lung granular γδ T cells as IL-17 synthesis and neutrophil recruitment was reduced by IL-2 blocking mAbs in vitro and in vivo. Mass cytometry analysis revealed that lung γδ T cells responded directly to IL-2 as evident from STAT5 phosphorylation and RoRγt expression. IL-2 receptor blocking mAbs and JAK inhibition impaired STAT5 phosphorylation and IL-17 release. Moreover, inhalation of S. aureus enterotoxin A induced IL-2 secretion and caspase-1-dependent IL-1β activation to drive IL-17 production. This T-cell-mediated inflammasome-dependent IL-17 response is maximum when lung Tγδ17 cells were sequentially stimulated first with IL-2 then IL-1β. Interestingly, when IL-2 is given therapeutically to cancer patients it carries a known risk of lung injury that is largely indistinguishable from that seen in sepsis. Hence, this novel mechanism reveals therapeutic targets treating both acute lung injury and high-dose IL-2 toxicity in cancer.

Acute Respiratory Distress Syndrome: Bench-to-Bedside Approaches to Improve Drug Development

Despite 50 years of extensive research, no definite drug is currently available to treat acute respiratory distress syndrome (ARDS), and the supportive therapies remain the mainstay of treatment. To improve drug development for ARDS, researchers need to deeply analyze the “omics” approaches, reevaluate the suitable therapeutic targets, resolve the problems of inadequate animal modeling, develop the strategies to reduce the heterogeneity, and reconsider new therapeutic and analytical approaches for better designs of clinical trials.

Novel translational approaches to the search for precision therapies for acute respiratory distress syndrome

In the 50 years since acute respiratory distress syndrome (ARDS) was first described, substantial progress has been made in identifying the risk factors for and the pathogenic contributors to the syndrome and in characterising the protein expression patterns in plasma and bronchoalveolar lavage fluid from patients with ARDS. Despite this effort, however, pharmacological options for ARDS remain scarce. Frequently cited reasons for this absence of specific drug therapies include the heterogeneity of patients with ARDS, the potential for a differential response to drugs, and the possibility that the wrong targets have been studied. Advances in applied biomolecular technology and bioinformatics have enabled breakthroughs for other complex traits, such as cardiovascular disease or asthma, particularly when a precision medicine paradigm, wherein a biomarker or gene expression pattern indicates a patient's likelihood of responding to a treatment, has been pursued. In this Review, we consider the biological and analytical techniques that could facilitate a precision medicine approach for ARDS.

The Role of Angiopoietine-2 in the Diagnosis and Prognosis of Sepsis

Introduction

Angiopoietin-2 (ANG-2) is a new biomarker whose blood-serum values increase in sepsis and its expression is elevated in line with the severity of the degree of inflammation. The aim of this study was to identify the diagnostic role of ANG-2 in patients with non-surgical sepsis addmitted to an intensive care unit.

Material and methods

This was a prospective randomized study including 74 patients admitted in the Clinic of Intensive Care of the County Clinical Emergency Hospital Tirgu Mureș, divided into two groups: Group S: patients with sepsis (n=40, 54%) and Group C:control, without sepsis (n=34, 46%). ANG-2 levels were determined in both groups.

Results

From the Group S, 14 patients (35%) had positive haemocultures. ANG-2 values varied between 1 and 43 ng/mL, with an average of 6.0 ng/mL in patients without sepsis and 10.38 ng/mL in patients with sepsis (p=0.021). A positive correlation between ANG-2 and SAPS II, SOFA and APACHE II severity scores was demonstrated, as was a positive correlation between serum levels of ANG-2 and procalcitonine. ANG-2 had a 5.71% specificity and 74.36% sensitivity for diagnosis of sepsis.

Conclusions

ANG-2 serum levels were elevated in sepsis, being well correlated with PCT values and prognostic scores. ANG-2 should be considered as a useful biomarker for the diagnosis and the prognosis of this pathology.