Expression and Localization of Paneth Cells and Their α-Defensins in the Small Intestine of Adult Mouse

Abstract

Paneth cells contribute to intestinal innate immunity by sensing bacteria and secreting α-defensin. In Institute of Cancer Research (ICR) mice, α-defensin termed cryptdin (Crp) in Paneth cells consists of six major isoforms, Crp1 to 6. Despite accumulating evidences that α-defensin functions in controlling the intestinal microbiota, topographical localization of Paneth cells in the small intestine in relation to functions of α-defensin remains to be determined. In this study, we examined the expression level of messenger RNA (mRNA) encoding six Crp-isoforms and Crp immunoreactivities using singly isolated crypts together with bactericidal activities of Paneth cell secretions from isolated crypts of duodenum, jejunum, and ileum. Here we showed that levels of Crp mRNAs in the single crypt ranged from 5 x 10 3 to 1 x 10 6 copies per 5 ng RNA. For each Crp isoform, the expression level in ileum was 4 to 50 times higher than that in duodenum and jejunum. Furthermore, immunohistochemical analysis of isolated crypts revealed that the average number of Paneth cell per crypt in the small intestine increased from proximal to distal, three to seven-fold, respectively. Both Crp1 and 4 expressed greater in ileal Paneth cells than those in duodenum or jejunum. Bactericidal activities in secretions of ileal Paneth cell exposed to bacteria were significantly higher than those of duodenum or jejunum. In germ-free mice, Crp expression in each site of the small intestine was attenuated and bactericidal activities released by ileal Paneth cells were decreased compared to those in conventional mice. Taken together, Paneth cells and their α-defensin in adult mouse appeared to be regulated topographically in innate immunity to control intestinal integrity.

Effect of dietary zinc supplementation on the gastrointestinal microbiota and host gene expression in theShank3B−/−mouse model of autism spectrum disorder

“…Alpha defensins are antimicrobial peptides active against a wide range of microorganisms [96]. Consistent with their known prevalence in the small intestine [97, 98], we documented higher expression of alpha defensin genes in the ileum compared with colon samples. Expression of several alpha defensins was higher in the Shank3B −/− KO mice compared to the wild-type mice, especially those on the supplemented zinc diet.…”

Effect of Dietary Zinc Supplementation on the Gastrointestinal Microbiota and Host Gene Expression in the Shank3B-/- Mouse Model of Autism Spectrum Disorder

“…Consistent with their known prevalence in the small intestine [97,98], we documented higher expression of alpha defensin genes in the ileum compared with colon samples. Expression of several alpha defensins was higher in the Shank3B -/-KO mice compared to the wild-type mice, especially those on the supplemented zinc diet.…”

Decrease of α-defensin impairs intestinal metabolite homeostasis via dysbiosis in mouse chronic social defeat stress model

“…Given the results that Crp4 administration rescued the dysbiosis and the impaired intestinal metabolites due to CSDS loading, it is suggested that Crp4 administration improved host microenvironment for Paneth cells and resulted in the increase of Crp1 secretion. This speculation is supported by evidence on the intestinal ecosystem, including that the intestinal commensal microbiota positively affects Paneth cell development and function, i.e., Crp secretions by comparing the germ-free and the conventional mice 12 , 48 , 49 .…”

“…α-Defensin, an antimicrobial peptide, produced and secreted by Paneth cells in the crypt of the small intestine is responsible, in part, for innate enteric immunity 9 – 12 and plays a critical role in both elimination and symbiosis in the intestine by killing pathogens while eliciting less bactericidal activities against commensal bacteria 13 . It has been reported that the absence of active α-defensin alters the composition of small intestinal microbiota in mice 14 , and oral administration of α-defensin rescues severe dysbiosis of graft-versus-host disease (GVHD) model mice 15 , indicating that α-defensin plays an important role in maintaining homeostasis of the intestinal microbiota.…”