Recent insight into potential acute respiratory distress syndrome

Antioxidant mitoquinone ameliorates EtOH-LPS induced lung injury by inhibiting mitophagy and NLRP3 inflammasome activation

Chronic ethanol abuse is a systemic disorder and a risk factor for acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD). However, the mechanisms involved are unknown. One explanation is that ethanol produces damaging reactive oxygen species (ROS) and disturbs the balance of mitochondria within the lungs to promote a pro-injury environment. We hypothesized that targeting an antioxidant to the mitochondria would prevent oxidative damage and attenuate EtOH-LPS-induced lung injury. To test this, we investigated the effects of mitochondria-targeted ubiquinone, Mitoquinone (MitoQ) on ethanol-sensitized lung injury induced by LPS. Lung inflammation, ROS, mitochondria function, and mitophagy were assessed. We demonstrated that chronic ethanol feeding sensitized the lung to LPS-induced lung injury with significantly increased reactive oxygen species ROS level and mitochondrial injury as well as lung cellular NLRP3 inflammasome activation. These deleterious effects were attenuated by MitoQ administration in mice. The protective effects of MitoQ are associated with decreased cellular mitophagy and NLRP3 inflammasome activation in vivo and in vitro. Taken together, our results demonstrated that ethanol aggravated LPS-induced lung injury, and antioxidant MitoQ protects from EtOH-LPS-induced lung injury, probably through reducing mitophagy and protecting mitochondria, followed by NLRP3 inflammasome activation. These results will provide the prevention and treatment of ethanol intake effects with new ideas.

In vitro exposure to complete engine emissions - a mini-review

Outdoor air pollution is classified as carcinogenic to humans and exposure to it contributes to increased incidence of various diseases, including cardiovascular, neurological or pulmonary disorders. Vehicle engine emissions represent a significant part of outdoor air pollutants, particularly in large cities with high population density. Considering the potentially negative health impacts of engine emissions exposure, the application of reliable test systems allowing assessment of the biological effects of these pollutants is crucial. The exposure systems should use relevant, preferably multicellular, cell models that are treated with the complete engine exhaust (i.e. a realistic mixture of particles, chemical compounds bound to them and gaseous phase) at the air-liquid interface. The controlled delivery and characterization of chemical and/or particle composition of the exhaust should be possible. In this mini-review we report on such exposure systems that have been developed to date. We focus on a brief description and technical characterization of the systems, and discuss the biological parameters detected following exposure to a gasoline/diesel exhaust. Finally, we summarize and compare findings from the individual systems, including their advantages/limitations.

Lung Ultrasound and Respiratory Pathophysiology in Mechanically Ventilated COVID-19 Patients-an Observational Trial

The relationship between respiratory system mechanics, lung ultrasound (LUS) abnormalities, and mortality in mechanically ventilated patients with COVID-19-associated respiratory failure is unknown. We assessed the pattern of respiratory mechanics and LUS, their changes over time, and the differences between survivors and non-survivors. We additionally analyzed the relationship between LUS findings and the severity of gas exchange impairment and interleukin 6 (IL-6). This was a two-center retrospective, observational trial carried out in the intensive care units of the hospitals of Bolzano and Merano, Italy, from March 15 to April 20, 2020. We enrolled 41 consecutive patients. Seven patients (17%, 95% CI 8.5–31.3%) died. Mean compliance of the respiratory system on ICU admission was 41.6 (± 18.8) ml/mbar (42.5 (± 19.6) for survivors, 38.0 (± 16.3) for deceased, p = 0.605). Non-survivors had a significantly lower compliance over time, decreasing from day 14 after symptom onset, compared with survivors (p = 0.008). Mean LUS score on admission was 11.2 (± 3.7) and survivors had lower LUS scores on admission than non-survivors (10.5 (± 3.6), 13.9 (2.8), respectively, t test, p = 0.029). LUS score correlated with IL-6 concentrations (r = 0.52, p = 0.001) and arterial pCO₂ (r = 0.30, p = 0.033) and was inversely correlated with oxygenation (r = − 0.34, p = 0.001). No correlation was found between LUS and respiratory system compliance (r = − 0.02, p = 0.299). Non-survivors from COVID-19-associated respiratory failure had a significant decrease in compliance after day 14 of symptom onset. Compliance did not correlate with the degree of abnormalities found in LUS, but LUS score correlated with oxygenation, pCO₂, and IL-6.

The neutrophil chemoattractant peptide proline-glycine-proline is associated with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized by unrelenting polymorphonuclear neutrophil (PMN) inflammation and vascular permeability. The matrikine proline-glycine-proline (PGP) and acetylated PGP (Ac-PGP) have been shown to induce PMN inflammation and endothelial permeability in vitro and in vivo. In this study, we investigated the presence and role of airway PGP peptides in acute lung injury (ALI)/ARDS. Pseudomonas aeruginosa-derived lipopolysaccharide (LPS) was instilled intratracheally in mice to induce ALI, and increased Ac-PGP with neutrophil inflammation was noted. The PGP inhibitory peptide, arginine-threonine-arginine (RTR), was administered (it) 30 min before or 6 h after LPS injection. Lung injury was evaluated by detecting neutrophil infiltration and permeability changes in the lung. Pre- and posttreatment with RTR significantly inhibited LPS-induced ALI by attenuating lung neutrophil infiltration, pulmonary permeability, and parenchymal inflammation. To evaluate the role of PGP levels in ARDS, minibronchoalveolar lavage was collected from nine ARDS, four cardiogenic edema, and five nonlung disease ventilated patients. PGP levels were measured and correlated with Acute Physiology and Chronic Health Evaluation (APACHE) score, P a O 2 to F I O 2 (P/F), and ventilator days. PGP levels in subjects with ARDS were significantly higher than cardiogenic edema and nonlung disease ventilated patients. Preliminary examination in both ARDS and non-ARDS populations demonstrated PGP levels significantly correlated with P/F ratio, APACHE score, and duration on ventilator. These results demonstrate an increased burden of PGP peptides in ARDS and suggest the need for future studies in ARDS cohorts to examine correlation with key clinical parameters.