Cystic fibrosis is one of the most frequent serious genetic diseases in France (7000 patients). It is the consequence of mutations in the CFTR gene, encoding a protein involved in the hydro-electrolytic balance of secretions. Beyond the well-known lung damage in these patients, intestinal inflammation is present in the majority of patients.~While advances in the management of cystic fibrosis are increasing patient life expectancy, other issues are emerging, including the impact of this chronic intestinal inflammation on the nutritional status and high risk of digestive cancers (Maisonneuve, 2013; Garg and Ooi, 2017; Yamada, 2018).~Currently, no management is proposed to treat this intestinal inflammation. The use of laxatives to fluidize digestive secretions and restore a digestive ecosystem close to the healthy subject could constitute a new therapeutic approach to this intestinal inflammation, as previously shown in the mouse model of cystic fibrosis (De Lisle, 2007). However, to date, to the investigator's knowledge, no studies have evaluated the effect of laxative treatment on intestinal inflammation of cystic fibrosis in humans.~This study is a bi-centric, non-comparative, prospective study for a phase II trial according to a Fleming scheme.~Study participants will take a 3-month laxative treatment with polyethylene glycol for 3 months. In addition to the inclusion visit, a follow-up visit will take place at 3 months and 3 intermediate telephone calls will be made to ensure efficacy, tolerance and compliance.
The main objective of the study is to evaluate the effectiveness of polyethylene glycol treatment on intestinal inflammation in children with cystic fibrosis. In this test, a method adapted from the Fleming one-step scheme will be used. The success rate is measured by the proportion of patients with fecal calprotectin levels < 250 µg/g at 3 months after treatment initiation.