BackgroundHylocereus undatus flower (HUF), the dried flower of H. undatus (Haw.) Britton and Rose, was first recorded in the Lingnan Record of Medicinal Herbs and is now listed in the Dictionary of Traditional Chinese Medicines. As an established traditional remedy, HUF is primarily used to treat various pulmonary conditions, including pneumonia, asthma, and tuberculosis. Acute lung injury (ALI) represents a critical and common pathological manifestation underlying severe respiratory disorders. However, the potential protective effects of HUF against ALI, and the specific mechanisms involved, remain unelucidated.PurposeTo systematically evaluate the protective effects of HUF extract on ALI and the pharmacological mechanisms involved.MethodsUsing a lipopolysaccharide-induced mouse model of ALI, we investigated the effects of HUF on the intestinal microbiota of ALI mice via microbial sequencing, metabolomics sequencing, and fecal microbiota transplantation (FMT). We explored the targets and signaling pathways of HUF intervention using transcriptomics and network pharmacology methods and then validated our results using immunological experiments and polymerase chain reaction analysis (PCR).ResultsHUF reduced lung indices and wet-dry ratios associated with pulmonary edema, alleviated inflammatory responses, and mitigated the severity of pulmonary pathological damage. HUF also increased the expression of intestinal tight junction protein (ZO-1), modulated the structure and relative abundance of the gut microbiota, and elevated the levels of certain short-chain fatty acids (SCFAs). FMT experiments confirmed that the HUF-mediated remodeling of the microbiota played a significant role in alleviating ALI. Transcriptomics and network pharmacology analyses suggested that the mechanism underling the interventional effect of HUF on ALI is related to inflammatory pathways. Immunological and PCR experiments further confirmed an association with the P38 mitogen-activated protein kinase (MAPK) pathway.ConclusionHUF is associated with attenuation of ALI, correlating with modulation of the gut-lung axis and the inflammatory pathways, and HUF may be a candidate for the treatment of ALI.