Neurological disorders after severe pneumonia are associated with translocation of endogenous bacteria from the lung to the brain

Neurological disorders are a common feature in patients who recover from severe acute pneumonia. However, the underlying mechanisms remain poorly understood. Here, we show that the neurological syndromes after severe acute pneumonia are partly attributed to the translocation of endogenous bacteria from the lung to the brain during pneumonia. Using principal components analysis, similarities were found between the brain's flora species and those of the lungs, indicating that the bacteria detected in the brain may originate from the lungs. We also observed impairment of both the lung-blood and brain-blood barriers, allowing endogenous lung bacteria to invade the brain during pneumonia. An elevated microglia and astrocyte activation signature via bacterial infection-related pathways was observed, indicating a bacterial-induced disruption of brain homeostasis. Collectively, we identify endogenous lung bacteria that play a role in altering brain homeostasis, which provides insight into the mechanism of neurological syndromes after severe pneumonia.

Automated summary

The neurological syndromes after severe acute pneumonia are partly caused by the translocation of endogenous bacteria from the lung to the brain during pneumonia. The study found similarities in the bacterial species between the brain and lungs, indicating that the bacteria in the brain may originate from the lungs. The impairment of lung-blood and brain-blood barriers allows endogenous lung bacteria to invade the brain, leading to bacterial-induced disruption of brain homeostasis.