Preliminary studies for the establishment of a model of CFTR-deficient piglets
Résumé
Introduction.– Cystic fibrosis (CF) is a life-shortening disease caused by mutations in the Cystic Fibrosis Trans membrane conductance Regulator (CFTR) gene. The lack of an animal model with lung abnormalities similar to those typically found in human CF has hindered studies of pathogenesis, treatment and prevention of infection in this disease. We aim to establish in Tours a CF pig model with a mutant CFTR that was engineered by our collaborator E. Wolf (Gene Center, LMU, Munich, Germany). Methods.– Pigs with mutant CFTR are bred in Tours, France. One difficulty with this CF pig model is a 100% prevalence of meconium ileus leading to death in the first days of birth. We therefore organized a multidisciplinary team at Tours (Inserm-INRA-CHU of Tours) and produced animals by mating CFTR+/- male and female pigs. Newborn CF piglets were anesthetized for surgical procedure after the diagnosis of CFTR-/- was confirmed by PCR. Prior to surgery, an attempt to diagnose the intestinal obstruction by abdominal ultrasonography and computerized tomography (CT) scan was made. Results.– Eleven CFTR-/- piglets (1.2 ± 0.2 kg) were born from Nov 2012 to Apr 2013. Nine of them were anesthetized for exploratory laparotomy; the two others were stillborn or euthanized (moribund). The mean birth-to-surgery time was 12.9 ± 2.8 h and included the time for PCR analysis. All CFTR-/- piglets developed meconium ileus, with distended intestine proximal to the obstruction and had poorly developed colon (microcolon). Four piglets had non-viable lesions (intestinal perforation). Ileostomies (intestinal by-pass) were performed for the setting-up of the anesthesia and surgical procedures, but the piglets were eventually euthanized. Finally, five piglets were waking up with an ileostomy. In addition to post-operative care, maternal-milk bottle-feeding has been started six hours after the surgery, with feces passing through the ileostomy. They survived one to three days. We failed to identify the meconium ileus by ultrasonography, but succeed by CT scan. A wide variety of tissues/fluids were collected from these animals to begin a tissue/secretion samples bank for future studies. Conclusions.– The cause of death of the CFTR KO piglets is not currently known, and we are still improving the post-operative cares. As the incidence of meconium ileus is of 100% in CFTR-/- animals, the diagnosis could be done faster by CT scan (and confirmed later by the PCR). By reducing the birth-to-surgery time, we hope to improve the survival. The tissues that we have collected provide an original opportunity to investigate initiating mechanisms of disease, with CF and non-CF comparisons, but without confounders.