Abstract
Background and purpose: Mutations in the CFTR chloride channel result in
intestinal o-structive episodes in cystic fibrosis (CF) patients and in
CF animal models. This study explores the possibility of reducing the
frequency of obstructive episodes in the
Cftr-/- mice by the oral application of a gut
selective NHE3 inhibitor tenapanor and searches for the underlying
mechanisms involved. Experimental approach: Sex and age-matched
Cftr+/+ and Cftr-/-
mice were orally gavaged twice daily with 30mgkg-1
tenapanor or vehicle for a period of 21 days. Body weight and stool
water content was assessed daily and gastrointestinal transit time (GTT)
once weekly. The mice were sacrificed when an intestinal obstruction was
suspected or after 21 days, and stool and tissues were collected for
further analysis. Key results: 21 day tenapanor application resulted in
a significant increase in stool water content, stool alkalinity, and a
significant decrease in GTT in Cftr+/+ and
Cftr-/- mice. Tenapanor significantly reduced
obstructive episodes to 8% compared to 46% in vehicle treated
Cftr-/- mice and prevented mucosal
inflammation. A decrease in cryptal hyperproliferation, mucus
accumulation and mucosal mast cell number was also observed in tenapanor
compared to vehicle treated unobstructed
Cftr-/- mice. Conclusion and implications: Oral
tenapanor application prevented obstructive episodes in CFTR deficient
mice and was safe in Cftr+/+ and
Cftr-/- mice. These results suggest that
tenapanor may be a safe and affordable adjunctive therapy in cystic
fibrosis patients to alleviate constipation and prevent recurrent DIOS.