title: Mouse background strain profoundly influences Paneth cell function and intestinal microbial composition.
abstract: BACKGROUND
  Increasing evidence supports the central role of Paneth cells in maintaining intestinal host-microbial homeostasis. However, the direct impact of host genotype on Paneth cell function remains unclear. Here, we characterize key differences in Paneth cell function and intestinal microbial composition in two widely utilized, genetically distinct mouse strains (C57BL/6 and 129/SvEv). In doing so, we demonstrate critical influences of host genotype on Paneth cell activity and the enteric microbiota.
  
  
  RESULTS
  Paneth cell numbers were determined by flow cytometry. Antimicrobial peptide (AMP) expression was evaluated using quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR), acid urea-polyacrylamide gel electrophoresis, and mass spectrometry. Effects of mouse background on microbial composition were assessed by reciprocal colonization of germ-free mice from both background strains, followed by compositional analysis of resultant gut bacterial communities using terminal restriction fragment length polymorphism analysis and 16 S qPCR. Our results revealed that 129/SvEv mice possessed fewer Paneth cells and a divergent AMP profile relative to C57BL/6 counterparts. Novel 129/SvEv á-defensin peptides were identified, including Defa2/18v, Defa11, Defa16, and Defa18. Host genotype profoundly affected the global profile of the intestinal microbiota, while both source and host factors were found to influence specific bacterial groups. Interestingly, ileal α-defensins from 129/SvEv mice displayed attenuated antimicrobial activity against pro-inflammatory E. coli strains, a bacterial species found to be expanded in these animals.
  
  
  CONCLUSIONS
  This work establishes the important impact of host genotype on Paneth cell function and the composition of the intestinal microbiota. It further identifies specific AMP and microbial alterations in two commonly used inbred mouse strains that have varying susceptibilities to a variety of disorders, ranging from obesity to intestinal inflammation. This will be critical for future studies utilizing these murine backgrounds to study the effects of Paneth cells and the intestinal microbiota on host health and disease.
authors.affiliation: Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, North Carolina, United States of America. agulati@med.unc.edu
authors.forename: Ajay S
authors.initials: AS
authors.lastname: Gulati
authors.forename: Michael T
authors.initials: MT
authors.lastname: Shanahan
authors.forename: Janelle C
authors.initials: JC
authors.lastname: Arthur
authors.forename: Emily
authors.initials: E
authors.lastname: Grossniklaus
authors.forename: Richard J
authors.initials: RJ
authors.lastname: von Furstenberg
authors.forename: Lieselotte
authors.initials: L
authors.lastname: Kreuk
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Henning
authors.forename: Christian
authors.initials: C
authors.lastname: Jobin
authors.forename: R Balfour
authors.initials: RB
authors.lastname: Sartor
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry; D004847:Epithelial Cells / Q000166:cytology; D004926:Escherichia coli / Q000378:metabolism; D005434:Flow Cytometry / Q000379:methods; D005753:Gastric Mucosa / Q000378:metabolism; D005838:Genotype; D007150:Immunohistochemistry / Q000379:methods; D007422:Intestines / Q000382:microbiology*; D013058:Mass Spectrometry / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D019879:Paneth Cells / Q000166:cytology*; D012150:Polymorphism, Restriction Fragment Length; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction; D013270:Stomach / Q000382:microbiology; D023084:alpha-Defensins / Q000378:metabolism
chemical_list: D023181:Antimicrobial Cationic Peptides; D023084:alpha-Defensins