Hylocereus undatus flower extract suppresses OVA-induced allergic asthma in BALb/c mice by reducing airway inflammation and modulating gut microbiota.

Asthma is a chronic allergic respiratory disease with limited treatment options. Emerging findings indicate an important interaction between the gut microbiota and the lungs, and that the development of asthma causes changes in the gut environment. Hylocereus undatus flower (HUF) is a traditional Chinese medicine used in the treatment of pulmonary and intestinal diseases. Our previous studies have demonstrated significant anti-asthmatic and anti-inflammatory activity, but the exact mechanism has not been elucidated. In the current study, we validated the potential therapeutic asthma properties of HUF in vivo using an ovalbumin-induced allergic asthma mouse model. We found that HUF treatment significantly reduced the key features of allergic asthma, including an elevated respiratory rate, inflammatory cell accumulation, airway inflammation, and the expression of pro-inflammatory molecules. Histological analysis of mouse lungs showed that HUF attenuated lung inflammatory cell infiltration. Periodic acid-Schiff staining confirmed the reduced mucus secretion in lung mucosa, and Masson's staining confirmed the reduced collagen deposition in the lungs after HUF treatment. Western blot and immunohistochemistry confirmed that HUF increased lung SIRT1 and reduced p38MAPK, NF-κBp65, and caspase-1 proteins. 16 S rDNA sequencing showed that HUF improved the endostasis of the disrupted gut microbiota composition in asthmatic mice. Surprisingly, an inflammatory response was found in the gut of asthmatic mice, along with alterations in inflammation-associated SIRT1 and caspase-1 proteins, and HUF was able to ameliorate these lesions. In conclusion, these findings suggest that HUF may be a new drug candidate for the treatment of allergic asthma.