Bilirubin nanoparticles modulate Treg/Th17 cells and functional metabolism of gut microbiota to inhibit lung adenocarcinoma.

Abstract

The level of serum bilirubin is associated with the incidence of lung cancer in both smokers and non-smokers, but the specific mechanism is unknown. Bilirubin nanoparticles (BRNPs) were synthesized to explore the effects on Treg/Th17 immunity and gut microbiota in Lewis Lung Carcinoma (LLC) mice, to provide insights for the treatment of lung adenocarcinoma. 10 μg/mL BRNPs promoted apoptosis of A549, NCI-H1299 and LLC cells. BRNPs inhibited lung adenocarcinoma formation in smoking and non-smoking LLC mice. In vivo and in vitro co-culture system proved that BRNPs promoted apoptosis of LLC cells and Treg cell differentiation, and inhibited the cigarette smoke extract (CSE)-induced anti-apoptosis effect and Th17 cell differentiation. In non-smoking LLC mice, Clostridium_sp and Alistipes_inops may be the pathogenic strains for inflammatory infiltration, while Staphylococcus, bile acid, alanine, and glucose metabolism may serve as the therapeutic target in BRNPs group. Fecal supernatant from NPs mice could promote Th17 differentiation and anti-apoptotic effect of LLC cells, while blocking the in vitro pro-apoptotic effect of BRNPs. Helicobacter_rodentium, Streptococcus_salivarius and Bifidobacterium_bifidum and metabolism (lipopolysaccharide and linoleic acid, as well as TCA circulation) may be the potential target for BRNPs+smoke treatment. Fecal supernatant from NPs + smoke mice promoted the CSE-induced Th17 differentiation and the anti-apoptotic effect of LLC cells, but this effect was blocked after the BRNPs intervention. Thus, BRNPs promoted Treg/Th17 cell immunity to inhibit tumor development in both smoking and non-smoking LLC mice through gut microbiota. In addition, BRNPs' therapeutic effect in smoking LLC mice may be related to Helicobacter_rodentium, Streptococcus_salivarius and Bifidobacterium_bifidum.