Con: β2-adrenergic agonists in ALI/ARDS--not recommended or potentially harmful?

Using the sympathetic system, beta blockers and alpha-2 agonists, to address acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) manifests as an acute inflammatory lung injury characterized by persistent hypoxemia, featuring a swift onset, high mortality, and predominantly supportive care as the current therapeutic approach, while effective treatments remain an area of active investigation. Adrenergic receptors (AR) play a pivotal role as stress hormone receptors, extensively participating in various inflammatory processes by initiating downstream signaling pathways. Advancements in molecular biology and pharmacology continually unveil the physiological significance of distinct AR subtypes. Interventions targeting these subtypes have the potential to induce specific alterations in cellular and organismal functions, presenting a promising avenue as a therapeutic target for managing ARDS. This article elucidates the pathogenesis of ARDS and the basic structure and function of AR. It also explores the relationship between AR and ARDS from the perspective of different AR subtypes, aiming to provide new insights for the improvement of ARDS.

Can the anti-inflammatory activities of β2-agonists be harnessed in the clinical setting?

Beta2-adrenoreceptor agonists (β2-agonists) are primarily bronchodilators, targeting airway smooth muscle and providing critical symptomatic relief in conditions such as bronchial asthma and chronic obstructive pulmonary disease. These agents also possess broad-spectrum, secondary, anti-inflammatory properties. These are mediated largely, though not exclusively, via interactions with adenylyl cyclase-coupled β2-adrenoreceptors on a range of immune and inflammatory cells involved in the immunopathogenesis of acute and chronic inflammatory disorders of the airways. The clinical relevance of the anti-inflammatory actions of β2-agonists, although often effective in the experimental setting, remains contentious. The primary objectives of the current review are: firstly, to assess the mechanisms, both molecular and cell-associated, that may limit the anti-inflammatory efficacy of β2-agonists; secondly, to evaluate pharmacological strategies, several of which are recent and innovative, that may overcome these limitations. These are preceded by a consideration of the various types of β2-agonists, their clinical applications, and spectrum of anti-inflammatory activities, particularly those involving adenosine 3',5'-cyclic adenosine monophosphate-activated protein kinase-mediated clearance of cytosolic calcium, and altered gene expression in immune and inflammatory cells.

Polyethyleneimine and DNA nanoparticles-based gene therapy for acute lung injury

Acute lung injury (ALI) is a devastating clinical syndrome causing a substantial mortality, but to date without any effective pharmacological management in clinic. Here, we tested whether nanoparticles based on polyethylenimine (PEI) and DNA could be a potential treatment. In mouse model of ALI induced by lipopolysaccharide (LPS) (10mg/kg), intravenous injection of PEI/DNA mediated a rapid (in 6h) and short-lived transgene expression in lung, with alveolar epithelial cells as major targets. When β2-Adrenergic Receptor (β2AR) was applied as therapeutic gene, PEI/β2AR treatment significantly attenuated the severity of ALI, including alveolar fluid clearance, lung water content, histopathology, bronchioalveolar lavage cellularity, protein concentration, and inflammatory cytokines in mice with pre-existing ALI. In high-dose LPS (40 mg/kg)-induced ALI, post-injury treatment of PEI/β2AR significantly improved the 5-day survival of mice from 28% to 64%. These data suggest that PEI/DNA nanoparticles could be an effective agent in future clinical application for ALI treatment.

FROM THE CLINICAL EDITOR

In this novel study, PEI/DNA nanoparticles are presented as an effective agent for the treatment of the devastating and currently untreatable syndrome of acute lung injury, using a rodent model system.

Current knowledge of acute lung injury and acute respiratory distress syndrome

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) continues to be a major cause of mortality in adult and pediatric critical care medicine. This article discusses the pulmonary sequelae associated with ALI and ARDS, the support of ARDS with mechanical ventilation, available adjunctive therapies, and experimental therapies currently being tested. It is hoped that further understanding of the fundamental biology, improved identification of the patient's inflammatory state, and application of therapies directed at multiple sites of action may ultimately prove beneficial for patients suffering from ALI/ARDS.