Chronic inflammation is a common feature of Cystic Fibrosis (CF) patients and is mainly caused by bacterial infections. However, new evidences suggest that constitutive inflammation is present in CF patients even in the absence of bacterial infection, due to CFTR dysfunctions. In a previous project (FFC#22/2017) researchers used CF zebrafish embryos, which recapitulate the chronic inflammation of CF human patients, and demonstrated that injection of bacteriophages (phages) not only efficiently counteract bacterial infection, but also show anti-inflammatory effects in the absence of bacteria. The rationale of this project is to validate the anti-inflammatory effects of phage therapy. To this aim, the CF zebrafish model will be treated with the previously used phages. The expected results are to show that phages might act as immuno-modulators. The CF zebrafish also in regard of inflammation is a cheap and easy-of-use model also in regard of inflammation and may to speed-up the translational potential.