Association Between Angiopoietin-2 and Enterovirus 71 Induced Pulmonary Edema

Efficacy and Safety of LY3127804, an Anti-Angiopoietin-2 Antibody, in a Randomized, Double-Blind, Placebo-Controlled Clinical Trial in Patients Hospitalized with Pneumonia and Presumed or Confirmed COVID-19

BACKGROUND

Severe cases of coronavirus disease 2019 (COVID-19) are characterized by progressive respiratory failure and the development of acute respiratory distress syndrome (ARDS), with high mortality rates for patients requiring mechanical ventilation. Levels of the vascular growth factor Angiopoietin 2 (Ang2) in plasma have been strongly correlated with increased ARDS risk in patients with pneumonia or sepsis. The intent of this study was to determine whether LY3127804, an anti-Ang2 monoclonal antibody, could reduce the need for mechanical ventilation among patients admitted to the hospital with pneumonia and presumed or confirmed COVID-19.

METHODS

Patients admitted to hospital with confirmed pneumonia, presumed or confirmed COVID-19, and infiltrates on chest imaging and/or oxygen saturation of ≤ 95% on room air were stratified by age group (< 65 years and ≥ 65 years), sex, and site and randomly assigned 1:1 within each stratum to receive either LY3127804 (20 mg/kg) or placebo on Day 1 and possibly on Day 15. The primary end point for this study was number of days in which a patient did not require a ventilator over the 28-day study period.

RESULTS

Interim analysis assessed study futility after 95 randomized patients had 28-day data available and showed no benefit of LY3127804 in reducing the number of ventilator days over placebo. The study was subsequently terminated.

CONCLUSION

LY3127804 treatment did not decrease the need for ventilator usage in patients hospitalized with pneumonia and presumed or confirmed COVID-19.

ClinicalTrials.gov identifier

NCT04342897

Delayed angiopoietin-2 blockade reduces influenza-induced lung injury and improves survival in mice

Influenza remains a major cause of death and disability with limited treatment options. Studies of acute lung injury have identified angiopoietin-2 (Ang-2) as a key prognostic marker and a potential mediator of Acute respiratory distress syndrome. However, the role of Ang-2 in viral pneumonia remains poorly defined. This study characterized the time course of lung Ang-2 expression in severe influenza pneumonia and tested the therapeutic potential of Ang-2 inhibition. We inoculated adult mice with influenza A (PR8 strain) and measured angiopoietin-1 (Ang-1), Ang-2, and Tie2 expressions during the evolution of inflammatory lung injury over the first 7 days post-infection (dpi). We tested a peptide-antibody inhibitor of Ang-2, L1-7, administered at 2, 4, and 6 dpi and measured arterial oxygen saturation, survival, pulmonary edema, inflammatory cytokines, and viral load. Finally, we infected primary human alveolar type II epithelial (AT2) cells grown in air-liquid interface culture with influenza and measured Ang-2 RNA expression. Influenza caused severe lung injury between 5 and 7 dpi in association with increased Ang-2 lung RNA and a dramatic increase in Ang-2 protein in bronchoalveolar lavage. Inhibition of Ang-2 improved oxygenation and survival and reduced pulmonary edema and alveolar-capillary barrier permeability to protein without major effects on inflammation or viral load. Finally, influenza increased the expression of Ang-2 RNA in human AT2 cells. The increased Ang-2 levels in the airspaces during severe influenza pneumonia and the improvement in clinically relevant outcomes after Ang-2 antagonism suggest that the Ang-1/Ang-2 Tie-2 signaling axis is a promising therapeutic target in influenza and potentially other causes of viral pneumonia.

Angiotensin II inhibits the protein expression of ZO‑1 in vascular endothelial cells by downregulating VE‑cadherin

Angiotensin II (Ang II) is reported to be involved in the development of various cardiovascular diseases by disrupting microvessel permeability, however, the underlying mechanism remains to be elucidated. The present study aimed to investigate the mechanism by which Ang II disrupts microvascular permeability. Rat endothelial cells were subjected to primary culture and identification. Cells in passages 4‑7 were then used for the following experiments. The cells were divided into control, Ang II, and Ang II + valsartan groups, and reverse transcription‑quantitative polymerase chain reaction and western blot analyses were perform to evaluate the expression of zonula occludens‑1 (ZO‑1) and vascular endothelial (VE)‑cadherin in the cells. The distribution of ZO‑1 protein was also detected using immunofluorescence assays. It was found that, compared with the control group, lower expression levels of ZO‑1 and VE‑cadherin were present in the Ang II group (P<0.01). ZO‑1 was also irregularly distributed at the periphery of the cells. In addition, the overexpression of VE‑cadherin reversed the effect of Ang II on the expression and distribution of ZO‑1 in endothelial cells. Together, these results suggested that Ang II inhibited the protein expression of ZO‑1 in vascular endothelial cells by downregulating VE‑cadherin, thus destroying the tight junctions between endothelial cells, which may also be the mechanism by which Ang II is involved in the development of cardiovascular diseases.