Nature of bacterial colonization influences transcription of mucin genes in mice during the first week of life

Abstract

BackgroundPostnatal regulation of the small intestinal mucus layer is potentially important in the development of adult gut functionality. We hypothesized that the nature of bacterial colonization affects mucus gene regulation in early life.We thus analyzed the influence of the presence of a conventional microbiota as well as two selected monocolonizing bacterial strains on the transcription of murine genes involved in mucus layer development during the first week of life.Mouse pups (N = 8/group) from differently colonized dams: Germ-free (GF), conventional specific pathogen free (SPF), monocolonized with either Lactobacillus acidophilus NCFM (Lb) or Escherichia coli Nissle (Ec) were analyzed by qPCR on isolated ileal tissue sections from postnatal days 1 and 6 (PND1, PND6) after birth with respect to: (i) transcription of specific genes involved in mucus production (Muc1-4, Tff3) and (ii) amounts of 16S rRNA of Lactobacillus and E. coli. Quantification of 16S rRNA genes was performed to obtain a measure for amounts of colonized bacteria.ResultsWe found a microbiota-independent transcriptional increase of all five mucus genes from PND1 to PND6. Furthermore, the relative level of transcription of certain mucus genes on PND1 was increased by the presence of bacteria. This was observed for Tff3 in the SPF, Ec, and Lb groups; for Muc2 in SPF; and for Muc3 and Muc4 in Ec and Lb, respectively.Detection of bacterial 16S rRNA genes levels above the qPCR detection level occurred only on PND6 and only for some of the colonized animals. On PND6, we found significantly lower levels of Muc1, Muc2 and Muc4 gene transcription for Lb animals with detectable Lactobacillus levels as compared to animals with Lactobacillus levels below the detection limit.ConclusionsIn summary, our data show that development of the expression of genes encoding secreted (Muc2/Tff3) and membrane-bound (Muc1/Muc3/Muc4) mucus regulatory proteins, respectively, is distinct and that the onset of this development may be accelerated by specific groups of bacteria present or absent at the mucosal site.

Milk Fat Globule Membrane Supplementation in Formula Modulates the Neonatal Gut Microbiome and Normalizes Intestinal Development

“…Rapid changes in the development of the various IEC subtypes have been documented during early intestinal development in several animal models78282930. Therefore, we next examined the impact of MFGM supplemented formula on the development of IECs.…”

“…GC numbers have also been found to significantly increase within the intestinal epithelium during postnatal development78. We assessed GCs by immunostaining for Muc2, and measuring Muc2 fluorescence intensity relative to DAPI (nuclear stain).…”

“…Using rodent and avian models, several groups have explored postnatal intestinal development from birth to one year of age, revealing major changes in epithelial architecture along the GI tract45678. Within the small intestine, crypt depths and villus lengths significantly increase during the first month, and the number of crypts within the large intestine doubles4.…”

“…Within the small intestine, crypt depths and villus lengths significantly increase during the first month, and the number of crypts within the large intestine doubles4. Others have reported increases in innervation of submucosal ganglia5, changes in localization of epithelial tight junction (TJ) proteins6, and significant increases in goblet cell (GC) numbers and mucins78 during the neonatal period. Proper intestinal development facilitates the overall development of the neonate, but is also important in providing appropriate defense against noxious stimuli.…”

Gut biogeography of the bacterial microbiota

“…Not surprisingly, genetic manipulation of enteric mucus production in mice changes microbial community composition 54,65 . In turn, gut bacteria affect transcription of mucin-encoding genes in mice 66 . Overall, development of a healthy mucosa is a collaborative, bi-directional event between the host and the gut microbiota, creating an environment that allows the specific members to establish persistent colonization via utilization of host-derived glycans.…”