Helicobacter bilis Infection Alters Mucosal Bacteria and Modulates Colitis Development in Defined Microbiota Mice

Abstract

Background Helicobacter bilis infection of C3H/HeN mice harboring the altered Schaedler flora (ASF) triggers progressive immune responsiveness and the development of colitis. We sought to investigate temporal alterations in community structure of a defined (ASF-colonized) microbiota in normal and inflamed murine intestines, and to correlate microbiota changes to histopathologic lesions. Methods The colonic mucosal microbiota of healthy mice and ASF mice colonized with H. bilis for 3, 6, or 12 weeks was investigated by fluorescence in situ hybridization (FISH) targeting the 16S rRNA genes of total bacteria, group-specific organisms, and individual ASF bacterial species. Microbial profiling of ASF and H. bilis abundance was performed on cecal contents. Results H. bilis colonized mice developed colitis associated with temporal changes in composition and spatial distribution of the mucosal microbiota. The number of total bacteria, ASF519, and helicobacter-positive bacteria were increased (P<0.05) while ASF360/361-positive bacteria were decreased (P<0.05) versus controls. Adherent biofilms in colitic mice were most often (P<0.05) composed of total bacteria, ASF457, and H. bilis. Total numbers of ASF519 and H. bilis bacteria were positively correlated (P=0.03, r=0.39 and P<0.0001, r=0.73) and total numbers of ASF360/361 bacteria were negatively correlated (P=0.003, r=−0.53) to histopathologic score. Differences in cecal abundance of ASF members were not observed. Conclusions Altered community structure with murine colitis is characterized by distinct ASF bacteria that interact with the colonic mucosa, either by formation of an isolating interlaced layer, by attachment, or by invasion, and this interaction is differentially expressed over time.

A real-time PCR assay for accurate quantification of the individual members of the Altered Schaedler Flora microbiota in gnotobiotic mice

“…Upon colonization, each species likely occupies different niches of the mouse GI tract and contributes to immune maturation, colonization resistance and host physiology (Orcutt et al, 1987). In addition, this model GI microbial community offers a unique opportunity to assess the specific contribution of individual bacterial species during states of homeostasis and disease (Atherly et al, 2016; Brugiroux et al, 2016; Endt et al, 2010; Ge et al, 2006; Rooks et al, 2017). However, a robust molecular quantification method for this community is needed, especially considering that cultivating some ASF members can be cumbersome.…”

“…Stehr et al, 2009, found P. goldsteinii (ASF 519) to be one of the most abundant community members in outbred CD-1 mice. More recently, other laboratories have reported P. goldsteinii (ASF 519) as the most relatively abundant ASF community member in BALB/cByJ (Rooks et al, 2017) and C3H/HeN mice (Atherly et al, 2016) following colonization with either E. coli LF82 or Helicobacter bilis , respectively. The most abundant taxa in our healthy C3H/HeN and C57BL/6 mice fed normal chow was L. murinus (ASF 361), yet others have found its abundance in cecal contents to vary from low to intermediate levels in a variety of mouse lines (Alexander et al, 2006; Sarma-Rupavtarm et al, 2004; Stehr et al, 2009).…”

“…The Altered Schaedler Flora (ASF) microbiota is one example of a defined community that offers the opportunity to study and dissect host-and-microbe relationships at a mechanistic level (Wymore et al, 2015). Moreover, it permits the addition of other specific organisms such as pathogens (Brugiroux et al, 2016, Endt et al, 2010) or pathobionts (Atherly et al, 2016, Ge et al, 2006, Rooks et al, 2017), thereby allowing for the measurement of individual member contributions to host functions such as immune system maturation (i.e., development of regulatory CD4 + T cells) and the onset of intestinal inflammation (Geuking et al, 2011, Liu et al, 2011; Wymore et al, 2015). Although the ASF community is limited in its metabolic capabilities and phylogenetic representation as compared to a conventional gut microbiota (Brugiroux et al, 2016; Dewhirst et al, 1999), the ASF community is resilient, and its members are long-term colonizers (Stehr et al, 2009) despite varying in abundance across different anatomical sites and host genotypes (Alexander et al, 2006; Sarma-Rupavtarm et al 2004).…”

Utilizing Whole Fusobacterium Genomes To Identify, Correct, and Characterize Potential Virulence Protein Families

“…Of the protein families characterized in this study, the most frequent and extensively enriched are MORN2 (membrane ontology and recognition nexus type 2) domaincontaining proteins that can have 1 to 27 repeats of this ϳ20-amino-acid domain. This expansion of MORN2 domain proteins is highly specific to Fusobacterium (24), with the exception of multiple genes found in Helicobacter bilis, which is involved in colitis and hepatitis, as well as infectious abortions in sheep (35,36). No known function has been assigned to the MORN2 domain-containing proteins; however, most contain signal sequences allowing for export into the periplasmic space and potential further export to the outer membrane or secretion into the extracellular environment.…”

Other Helicobacters, gastric and gut microbiota

“…Schaedler flora (ASF) induced the development of colitis associated with temporal changes in composition and spatial distribution of the mucosal microbiota. Adherent biofilms in colitic mice were composed of total bacteria, ASF457, and H. bilis in the majority of samples 39. Various mouse models were implemented to investigate NHPH infection.…”