Abstract
BackgroundIncreasing 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.Methodology and Principal FindingsPaneth 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 and SignificanceThis 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.
Highlights
Paneth cells are highly specialized secretory cells of the intestinal epithelium, located at the base of the crypts of Lieberkuhn in the small intestine
This work establishes the important impact of host genotype on Paneth cell function and the composition of the intestinal microbiota
Repeat analyses (n = 3) revealed B6 mice had 0.8360.32% Lyz+ epithelial cells versus 0.2360.09% in 129 mice (,4-fold difference, P,.04). This was consistent with ileal mRNA expression of Lyz shown in Figure 1C, which demonstrated that specific pathogen-free (SPF) B6 mice expressed,3-fold more Lyz transcript than 129 mice (P,.0001)
Summary
Paneth cells are highly specialized secretory cells of the intestinal epithelium, located at the base of the crypts of Lieberkuhn in the small intestine. Their distinctive morphology is characterized by large secretory granules that contain a diverse array of proteins that support intestinal homeostasis. These homeostatic functions range from maintenance of the intestinal stem cell niche [1] to establishment of the antimicrobial barrier of the intestinal mucosa [2]. 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). We demonstrate critical influences of host genotype on Paneth cell activity and the enteric microbiota
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