Lung microbiota: a new hope for treating acute respiratory distress syndrome?

Abstract

The lung microbiota, present in healthy individuals, undergoes alterations in different diseases and is closely linked to changes in both systemic and alveolar immunity. These interactions play a crucial role in the onset and progression of numerous diseases. Acute respiratory distress syndrome (ARDS), one of the most severe conditions encountered in intensive care units (ICU), is characterized by high incidence and mortality rates. The pathophysiology of ARDS involves complex mechanisms, including the activation and dysregulation of overlapping pathways related to injury, inflammation, and coagulation, both locally in the lungs and systemically. Notably, alterations in the microbiota may contribute to the pathogenesis of ARDS. Emerging evidence suggests that changes in the lung microbiota are associated with ARDS development, often marked by increased bacterial burden, reduced microbial diversity, and shifts in microbiota composition. In this review, we focus on the regulatory roles of the lung microbiota in ARDS and their therapeutic potential.

Keywords: ARDS; corona virus disease 2019 (COVID-19); lung microbiota; metabolic products; prognosis.

FIGURE 1

Potential therapeutic targets and promising drugs for attenuating ALI/ARDS by modulating lung microbiota. Gut-associated bacteria, bacteria that are enriched in the gut, such as Bacteroides spp.; Responders to early corticosteroid therapy, patients who showed a significant improvement in their PaO₂/FiO₂ ratio after receiving corticosteroid treatment. Arterial blood gas measurements were obtained upon ICU admission, prior to the initial administration of corticosteroids, and repeated 24 hours later, following (or prior to) corticosteroid treatment. The difference in PaO₂/FiO₂ between these two time points, referred to as ΔPaO₂/FiO₂, was calculated. Patients with a ΔPaO₂/FiO₂ ≥ 150 mmHg were categorized as responders, while those with a ΔPaO₂/FiO₂ < 150 mmHg were classified as non-responders.