Airborne particulate matter and the lung-brain axis: unraveling the neuroinflammatory cascade from alveolar irritation to microglial activation.
Level 5 - mechanism / opinion, no new human data
Narrative review of mechanistic literature without systematic methodology or primary human data
PubMed 41840695 · doi:10.1186/s12974-026-03770-x
What was done
This narrative review synthesizes literature regarding the "lung-brain axis" to describe how exposure to airborne particulate matter (PM2.5 and diesel exhaust) leads to central nervous system pathology. The authors review proposed mechanisms of neurotoxicity, including direct particle translocation (via the olfactory route and disrupted blood-brain barrier) and indirect systemic "spill-over" (alveolar macrophage activation, circulating cytokines such as IL-1β, TNF-α, and IL-6, extracellular vesicles, vagus nerve signaling, and lung-derived exosomal microRNAs).
What was found
The abstract provides a qualitative mechanistic summary and reports no quantitative data, effect estimates, or pooled study numbers. It identifies key signaling pathways connecting alveolar irritation to microglial activation and neuroinflammation, emphasizing the role of systemic inflammatory mediators and neural sensing mechanisms.
Why it matters
Clarifying the signaling conduits between pulmonary irritation and neuroinflammation helps identify potential molecular targets and supports interventions directed at lung inflammation to mitigate the neurological harms of air pollution.
Limits
The review relies on narrative synthesis rather than a systematic methodology or meta-analysis. The abstract contains no primary experimental data, clinical outcomes, or quantitative risk metrics, reflecting primarily mechanistic and preclinical models.
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