Validation of Messenger Ribonucleic Acid Markers Differentiating Among Human Acute Respiratory Distress Syndrome Subgroups in an Ovine Model of Acute Respiratory Distress Syndrome Phenotypes

Biological basis of critical illness subclasses: from the bedside to the bench and back again

Critical illness syndromes including sepsis, acute respiratory distress syndrome, and acute kidney injury (AKI) are associated with high in-hospital mortality and long-term adverse health outcomes among survivors. Despite advancements in care, clinical and biological heterogeneity among patients continues to hamper identification of efficacious therapies. Precision medicine offers hope by identifying patient subclasses based on clinical, laboratory, biomarker and 'omic' data and potentially facilitating better alignment of interventions. Within the previous two decades, numerous studies have made strides in identifying gene-expression based endotypes and clinico-biomarker based phenotypes among critically ill patients associated with differential outcomes and responses to treatment. In this state-of-the-art review, we summarize the biological similarities and differences across the various subclassification schemes among critically ill patients. In addition, we highlight current translational gaps, the need for advanced scientific tools, human-relevant disease models, to gain a comprehensive understanding of the molecular mechanisms underlying critical illness subclasses.

An appraisal of lung computer tomography in very early anti-inflammatory treatment of two different ovine ARDS phenotypes

Mortality and morbidity of Acute Respiratory Distress Syndrome (ARDS) are largely unaltered. A possible new approach to treatment of ARDS is offered by the discovery of inflammatory subphenotypes. In an ovine model of ARDS phenotypes, matching key features of the human subphenotypes, we provide an imaging characterization using computer tomography (CT). Nine animals were randomized into (a) OA (oleic acid, hypoinflammatory; n = 5) and (b) OA-LPS (oleic acid and lipopolysaccharides, hyperinflammatory; n = 4). 48 h after ARDS induction and anti-inflammatory treatment, CT scans were performed at high (H) and then low (L) airway pressure. After CT, the animals were euthanized and lung tissue was collected. OA-LPS showed a higher air fraction and OA a higher tissue fraction, resulting in more normally aerated lungs in OA-LPS in contrast to more non-aerated lung in OA. The change in lung and air volume between H and L was more accentuated in OA-LPS, indicating a higher recruitment potential. Strain was higher in OA, indicating a higher level of lung damage, while the amount of lung edema and histological lung injury were largely comparable. Anti-inflammatory treatment might be beneficial in terms of overall ventilated lung portion and recruitment potential, especially in the OA-LPS group.

Interleukin-41 diminishes cigarette smoke-induced lung inflammation in mice

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and other inflammatory lung illnesses are markedly exacerbated by cigarette smoke (CS). The novel cytokine interleukin (IL)-41 has immunoregulatory effects, but data on its function in lung inflammation caused by CS are limited and inconclusive. Our study aimed to investigate the ability of IL-41 to protect against CS-induced lung inflammation in vivo.

METHODS

In this model, mice were exposed to six cigarettes three times daily for 1 h, with 4-hour intervals between exposures, for 5 consecutive days. Mice received an intraperitoneal dose of IL-41 or a negative control 1 day prior to their initial exposure to CS. On day 6, mice were sacrificed to assess the impact of IL-41 on CS-induced lung inflammation.

RESULTS

We found that IL-41 pre-treatment alleviated pulmonary inflammatory infiltration and lung tissue lesions. IL-41 pre-treatment also limited CS-induced weight loss, and resulted in lower numbers of macrophages in the bronchoalveolar lavage fluid and lower percentages of neutrophils and monocytes in the blood. Furthermore, it promoted the polarization of M2 macrophages rather than M1 macrophages, as determined by immunohistochemistry. Consistent with its effects on M2 polarization, pre-treatment with IL-41 was associated with higher levels of IL-10 in the bronchoalveolar lavage fluid and lung tissues of CS-exposed animals and lower production of tumor necrosis factor-α, IL-6 and IL-1β in the serum and lung tissues.

CONCLUSIONS

These findings suggest that IL-41 could be used therapeutically to treat CS-induced lung inflammatory disorders as it inhibits CS-induced pulmonary inflammation when administered in vivo in mice.