The human cerebral cortex is distinguished by its large size and abundant gyrification, or folding, yet the evolutionary mechanisms driving cortical size and structure are unknown. While genes essential for cortical developmental expansion have been identified from the genetics of human primary microcephaly (“small head”, associated with reduced brain size and intellectual disability)1, studies of these genes in mice, whose smooth cortex is one thousand times smaller than that of humans, have provided limited insight. Mutations of abnormal spindle-like microcephaly-associated (ASPM), the most common recessive microcephaly gene, reduce cortical volume by ≥50% in humans2–4, but have little effect in mice5–9, likely reflecting evolutionarily divergent functions of ASPM10,11. We used genome editing to create a germline knockout (KO) of Aspm in the ferret (Mustela putorius furo), a species with a larger, gyrified cortex and greater neural progenitor cell (NPC) diversity12–14 than mice, and closer Aspm protein sequence homology to human. Aspm KO ferrets exhibit severe microcephaly (25–40% decreases in brain weight), reflecting reduced cortical surface area without significant change in cortical thickness, as in human patients3,4, suggesting loss of “cortical units”. The mutant ferret fetal cortex displays a massive premature displacement of ventricular radial glial cells (VRG) to the outer subventricular zone (OSVZ), where many resemble outer radial glia (ORG), an NPC subtype essentially absent in mice and implicated in cerebral cortical expansion in primates12–16. These data suggest an evolutionary mechanism whereby Aspm regulates cortical expansion by controlling the affinity of VRG for the ventricular surface, thus modulating the ratio of VRG, the most undifferentiated cell type, to ORG, a more differentiated progenitor.

Diabetes is a common comorbidity in cystic fibrosis (CF) that worsens prognosis. The lack of an animal model for CF-related diabetes (CFRD) has made it difficult to dissect how the onset of pancreatic pathology influences the emergence of CFRD. We evaluated the structure and function of the neonatal CF endocrine pancreas using a new CFTR-knockout ferret model. Although CF kits are born with only mild exocrine pancreas disease, progressive exocrine and endocrine pancreatic loss during the first months of life was associated with pancreatic inflammation, spontaneous hyperglycemia, and glucose intolerance. Interestingly, prior to major exocrine pancreas disease, CF kits demonstrated significant abnormalities in blood glucose and insulin regulation, including diminished first-phase and accentuated peak insulin secretion in response to glucose, elevated peak glucose levels following glucose challenge, and variably elevated insulin and C-peptide levels in the nonfasted state. Although there was no difference in lobular insulin and glucagon expression between genotypes at birth, significant alterations in the frequencies of small and large islets were observed. Newborn cultured CF islets demonstrated dysregulated glucose-dependent insulin secretion in comparison to controls, suggesting intrinsic abnormalities in CF islets. These findings demonstrate that early abnormalities exist in the regulation of insulin secretion by the CF endocrine pancreas. IntroductionCystic fibrosis (CF) is caused by defects in the CF transmembrane conductance regulator (CFTR) chloride channel. Cystic fibrosisrelated diabetes (CFRD) is a common complication of CF and affects 20%-25% of adolescents and 40%-50% of individuals over 30 years of age (1,2). CFRD is associated with worsening clinical status, including reduced pulmonary function, increased frequency of pulmonary exacerbations, and a decline in nutritional status (3-7). Furthermore, CFRD leads to increased mortality compared with CF patients without diabetes (4,8). Thus, early diagnosis and treatment are vital to improving clinical outcome of CFRD patients.While the pathophysiology of CFRD is multifactorial, delayed insulin secretion appears to be a key hallmark of disease progression (9-12), and the health of CF patients is improved by insulin therapy prior to and following diagnosis of overt diabetes (13,14). Partial insulin deficiency occurs in part due to islet loss associated with exocrine pancreas disease (15-18). However, CF pancreata at CFRD autopsy demonstrate that remaining islets contain roughly half the number of insulin-positive cells found in non-CF controls (17,18), and this degree of β cell loss is thought to be insufficient to explain diabetes (19). Thus, insulin deficiency in CFRD is relative and not absolute. All stages of CFRD are characterized by abnormalities in circulating insulin levels (10,12,20,21). Impaired first-phase insulin (IFPI) responses are common in CFRD patients, but also occur in approximately 50% of CF children with normal glucose tolerance (9). Cu...

Chronic bacterial lung infections in cystic fibrosis (CF) are caused by defects in the CF transmembrane conductance regulator chloride channel. Previously, we described that newborn CF transmembrane conductance regulator-knockout ferrets rapidly develop lung infections within the first week of life. Here, we report a more slowly progressing lung bacterial colonization phenotype observed in juvenile to adult CF ferrets reared on a layered antibiotic regimen. Even on antibiotics, CF ferrets were still very susceptible to bacterial lung infection. The severity of lung histopathology ranged from mild to severe, and variably included mucus obstruction of the airways and submucosal glands, air trapping, atelectasis, bronchopneumonia, and interstitial pneumonia. In all CF lungs, significant numbers of bacteria were detected and impaired tracheal mucociliary clearance was observed. Although Streptococcus, Staphylococcus, and Enterococcus were observed most frequently in the lungs of CF animals, each animal displayed a predominant bacterial species that accounted for over 50% of the culturable bacteria, with no one bacterial taxon predominating in all animals. Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry fingerprinting was used to quantify lung bacteria in 10 CF animals and demonstrated Streptococcus, Staphylococcus, Enterococcus, or Escherichia as the most abundant genera. Interestingly, there was significant overlap in the types of bacteria observed in the lung and intestine of a given CF animal, including bacterial taxa unique to the lung and gut of each CF animal analyzed. These findings demonstrate that CF ferrets develop lung disease during the juvenile and adult stages that is similar to patients with CF, and suggest that enteric bacterial flora may seed the lung of CF ferrets.

Although β-cell dysfunction in cystic fibrosis (CF) leads to diabetes, the mechanism by which the cystic fibrosis transmembrane conductance regulator (CFTR) channel influences islet insulin secretion remains debated. We investigated the CFTR-dependent islet-autonomous mechanisms affecting insulin secretion by using islets isolated from CFTR knockout ferrets. Total insulin content was lower in CF as compared with wild-type (WT) islets. Furthermore, glucose-stimulated insulin secretion (GSIS) was impaired in perifused neonatal CF islets, with reduced first, second, and amplifying phase secretion. Interestingly, CF islets compensated for reduced insulin content under static low-glucose conditions by secreting a larger fraction of islet insulin than WT islets, probably because of elevated SLC2A1 transcripts, increased basal inhibition of adenosine triphosphate-sensitive potassium channels (K-ATP), and elevated basal intracellular Ca2+. Interleukin (IL)-6 secretion by CF islets was higher relative to WT, and IL-6 treatment of WT ferret islets produced a CF-like phenotype with reduced islet insulin content and elevated percentage insulin secretion in low glucose. CF islets exhibited altered expression of INS, CELA3B, and several β-cell maturation and proliferation genes. Pharmacologic inhibition of CFTR reduced GSIS by WT ferret and human islets but similarly reduced insulin secretion and intracellular Ca2+ in CFTR knockout ferret islets, indicating that the mechanism of action is not through CFTR. Single-molecule fluorescent in situ hybridization, on isolated ferret and human islets and ferret pancreas, demonstrated that CFTR RNA colocalized within KRT7+ ductal cells but not endocrine cells. These results suggest that CFTR affects β-cell function via a paracrine mechanism involving proinflammatory factors secreted from islet-associated exocrine-derived cell types.

AimTo evaluate the efficacy and safety of mealtime or post‐meal fast‐acting insulin aspart (faster aspart) vs mealtime insulin aspart (IAsp), both in combination with insulin degludec, in participants with type 1 diabetes (T1D).MethodsThis multicentre, treat‐to‐target trial (Clinical trial registry: NCT02500706, http://clinicaltrials.gov) randomized participants to double‐blind mealtime faster aspart (n = 342) or IAsp (n = 342) or open‐label post‐meal faster aspart (n = 341). The primary endpoint was change from baseline in HbA1c 26 weeks post randomization. All available information, regardless of treatment discontinuation, was used for evaluation of the effect.ResultsNon‐inferiority for the change from baseline in HbA1c was confirmed for mealtime and post‐meal faster aspart vs IAsp (estimated treatment difference [ETD]: 95%CI, −0.02% [−0.11; 0.07] and 0.10% [0.004; 0.19], respectively). Mealtime faster aspart was superior to IAsp for 1‐hour PPG increment using a meal test (ETD, −0.90 mmol/L [−1.36; –0.45]; P < 0.001). Self‐monitored 1‐hour PPG increment favoured faster aspart at breakfast (ETD, −0.58 mmol/L [−0.99; −0.17]; P = 0.006) and across all meals (−0.48 mmol/L [−0.74; −0.21]; P < 0.001). Safety profiles and overall rate of severe or blood glucose‐confirmed hypoglycaemia were similar between treatments, but significantly less hypoglycaemia was seen 3 to 4 hours after meals with mealtime faster aspart.ConclusionMealtime and post‐meal faster aspart in conjunction with insulin degludec provided effective glycaemic control compared with IAsp, with no increased safety risk. Mealtime faster aspart provided PPG control superior to that of IAsp.