Inflammatory Mechanisms in Acute Lung Injury

Acute lung injury arises when a complex network of inflammatory events disrupts the delicate alveolar-capillary barrier, leading to capillary leak, pulmonary oedema and hypoxaemia. The initial insult—whether infectious, chemical or mechanical—triggers endothelial and epithelial cell activation, with release of pro-inflammatory cytokines such as tumour necrosis factor-α and interleukin-1β. Neutrophils and monocyte-derived macrophages are recruited via chemokine gradients and adhere to the injured endothelium through up-regulated adhesion molecules. Within these immune cells, metabolic reprogramming shifts energy production towards glycolysis, fuelling assembly of inflammasomes such as NLRP3 and AIM2 and driving maturation of IL-1β and IL-18. Pyroptotic cell death amplifies tissue damage, while excessive reactive oxygen species exacerbate capillary permeability and oxidise proteins and lipids. Counter-regulatory pathways, including Nrf2-mediated antioxidative responses and anti-inflammatory macrophage polarisation, often prove insufficient to resolve injury. Persistent inflammation culminates in diffuse alveolar damage, impaired gas exchange and progression to acute respiratory distress syndrome. Understanding the interplay between cell death programmes, metabolic signals and barrier integrity is essential to develop targeted therapies that restore pulmonary homeostasis and reduce the high mortality associated with severe lung injury.

Research from Nature Portfolio

Recent studies have defined a pivotal role for metabolic enzymes in inflammasome activation. One seminal work demonstrated that PKM2-mediated glycolysis in macrophages promotes phosphorylation of EIF2AK2, driving activation of both NLRP3 and AIM2 inflammasomes and subsequent release of IL-1β, IL-18 and HMGB1; pharmacological inhibition of the PKM2–EIF2AK2 axis conferred protection against lethal endotoxaemia and sepsis in murine models. Another key investigation revealed that activation of the purinergic P2X7 receptor in monocytes induces mitochondrial dysfunction, which in turn impairs NLRP3 inflammasome assembly via stabilisation of HIF-1α. In patients with sepsis, profound P2X7-driven mitochondrial failure correlated with reduced inflammasome responses and higher mortality, offering a mechanistic link between hyperinflammation and subsequent immune paralysis.

Inflammatory Mechanisms in Acute Lung Injury publication trend

The graph below shows the total number of articles in inflammatory mechanisms in acute lung injury across all publications each year (not limited to Nature Index journals).

Technical terms

Inflammasome: multiprotein complex that activates inflammatory caspases and promotes cytokine maturation.

Pyroptosis: pro-inflammatory form of programmed cell death mediated by gasdermin pore formation.

Reactive oxygen species (ROS): chemically reactive molecules derived from oxygen that can drive tissue injury and inflammation.

Macrophage polarisation: functional differentiation of macrophages into pro-inflammatory (M1) or anti-inflammatory (M2) states.

Immunometabolism: interplay between cellular metabolic pathways and immune cell function.

References

1. Chemical Evolution and Biological Evaluation of Natural Products for Efficient Therapy of Acute Lung Injury. Advanced Science (2023).
2. NIR triggered polydopamine coated cerium dioxide nanozyme for ameliorating acute lung injury via enhanced ROS scavenging. Journal of Nanobiotechnology (2024).
3. PKM2-dependent glycolysis promotes NLRP3 and AIM2 inflammasome activation. Nature Communications (2016).
4. P2X7 receptor induces mitochondrial failure in monocytes and compromises NLRP3 inflammasome activation during sepsis. Nature Communications (2019).