Cystic Fibrosis: Using ferrets as a Disease Model.

Cystic Fibrosis:

Using ferrets as a Disease Model

Ferret Models

Terms and Abbreviations

CF = Cystic Fibrosis SCNT = Somatic Cell Nuclear Transfer MI = Meconium Ileus LFT = Liver Function Test ALT = Alanine Aminotransferase UDCA = Ursodeoxycholic Acid FABPi = Fatty acid binding promoter

Background

CF affects: 1 in 3,500 newborns each year

People of mixed European descent

Caused by a defective CFTR gene Codes for epithelial chloride channel

Background CF affects many tissues:

Lung Liver Pancreas Male Reproductive Tract Intestines Gall Bladder Sweat Gland

Why ferrets?

2 reasons:

Their lung anatomy and cell biology are similar to humans

They reproduce fast

Methodology

Knockout gene was engineered HA-tagged cDNA of CFTR gene

Used the FABPi promoter

Results

9 clones heterozygous for CFTR were bred

Expected 1:2:1 ratio to create ferret models with CF, or kits

Results

At 24 hours, CF kits were indestinguishable from littermates

At 36 hours, they failed to thrive

Euthanized at 48 hours

Results: MI Variable Penetrance MI affects the intestine

It is a blockage Can cause perforations in intestine

Frequency ranged for 50-100% in offspring of 9 heterzygous male parents Was statistically linked to the parents

used in breeding (P< 0.047)

Results: Male RT

Nearly all males with CF suffered from infertility

Vas Deferens becomes absent throughout development Unilateral degeneration detected as

early as 2 yrs old

Results: Male RT

Results: Pancreas All glands exhibited legions

Ferrets were consistant with those in newborn humans with CF

Significantly less severe than those seen on the Pig model

Histopathology of gall bladder and liver indistinguishable from non CF littermates

Results: Lungs Those infants that escaped MI did

not escape Lung complications

25% of neonatal deaths were not found out for those who passed MI

Evidence found of pneumonia and aspiration

Results: Lungs

ALT levels were elevated

Bilirubin Elevated

Cholesterol levels reduced Suggests potential liver disease No histo legions on liver, but elevated

LFTs

Results: Liver Elevated LFTs is unclear Bile acid malabsorption by intestine

Changes circulation and composition of bile acids

Cholesterol levels low due to defective fatty acid absorption in the gut

Oral doses of UDCA showed normalization of LFTs and ALT levels

Results: Nutrition Due to bad bile acids, lipids become

hard to digest in CF patients.

Due to impaired pancreas activity, HCO3- is not secreted into gut which lowers pH

To counteract, oral proton pump is given to try and normalize gut pH

Conclusions

There are many models out there

Each one may be best suited to a specific symptom of CF

Still doing research on ferrets for lungs Initial reasoning for using them is sound

References 1.) Disease phenotype of a ferret CFTR-knockout model of cystic

fibrosis Published in Volume 120, Issue 9 (September 1, 2010)J Clin Invest. 2010;120(9):3149–3160. doi:10.1172/JCI43052. Copyright © 2010, American Society for Clinical Investigation

2.) Riordan JR, et al. Identification of the cystic fibrosis gene: cloning and characterization of complementary DNA. Science. 1989;245(4922):1066–

1073. 3.) Egan ME. How useful are cystic fibrosis mouse models? Drug Discov

Today Dis Models. 2009;6(2):35–41.

4.) Rogers CS, et al. Disruption of the CFTR gene produces a model of cystic fibrosis in newborn pigs. Science. 2008;321(5897):1837–1841.

All 3 Models

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