Unique Gene Expression Signatures in the Intestinal Mucosa and Organoids Derived from Germ-Free and Monoassociated Mice.

Lucie Janeckova,Jiri Svec,Jolana Tureckova,Jitka Stancikova,Katerina Galuskova,Monika Stastna,Eva Sloncova,Helena Tlaskalova-Hogenova,Michal Kolar,Vladimir Korinek,Tomas Hudcovic,Hynek Strnad,Nikol Baloghova,Klara Kostovcikova

doi:10.3390/ijms20071581

Abstract

Commensal microbiota contribute to gut homeostasis by inducing transcription of mucosal genes. Analysis of the impact of various microbiota on intestinal tissue provides an important insight into the function of this organ. We used cDNA microarrays to determine the gene expression signature of mucosa isolated from the small intestine and colon of germ-free (GF) mice and animals monoassociated with two E. coli strains. The results were compared to the expression data obtained in conventionally reared (CR) mice. In addition, we analyzed gene expression in colon organoids derived from CR, GF, and monoassociated animals. The analysis revealed that the complete absence of intestinal microbiota mainly affected the mucosal immune system, which was not restored upon monoassociation. The most important expression changes observed in the colon mucosa indicated alterations in adipose tissue and lipid metabolism. In the comparison of differentially expressed genes in the mucosa or organoids obtained from GF and CR mice, only six genes were common for both types of samples. The results show that the increased expression of the angiopoietin-like 4 (Angptl4) gene encoding a secreted regulator of lipid metabolism indicates the GF status.

Highlights

Mammalian gut is a complex organ consisting of cells and tissues intrinsic for the organism, and in addition, containing vast amounts of bacteria
The tissues were obtained from GF and conventionally reared (CR) mice and mice monoassociated with the E. coli O6K13 or Nissle 1917 strain, further referred to as ‘N’ and ‘O’ mice, respectively
Since the expression level of these genes was mainly reduced in GF mice, this confirmed the previously published results that gut microbiota are indispensable for the establishment and maintenance of the mucosal immune system [28,29]

Summary

Introduction

Mammalian gut is a complex organ consisting of cells and tissues intrinsic for the organism, and in addition, containing vast amounts of bacteria. The microbial population in the gut, so-called microbiome, outnumbers the amount of cells present in the human body (reviewed in Reference [1]). Gut colonization by microbiota is crucial for development and function of the intestinal immune system (reviewed in Reference [2]). In case the colonization occurs at a later age, the immune response to various stimuli is decreased and never recovers the levels observed in animals kept in standard conditions [3]. Commensal microbiota contribute to gut homeostasis by inducing region-dependent mucosal transcription [4]. The composition of microbial populations is influenced during a lifetime by the host’s diet, antibiotics usage, and genetic background of the host (reviewed in Reference [5]). A single gene polymorphism may impact the bacterial population diversity in the intestine [6]

Methods

Results

Conclusion