Bergström Anders, Kristensen Matilde B, Bahl Martin I, Metzdorff Stine B, Fink Lisbeth N, Frøkiaer Hanne, Licht Tine R
Gut Ecology Group, Department of Food Microbiology, National Food Institute, Technical University of Denmark, Søborg, Denmark.
BMC Res Notes. 2012 Aug 2;5:402. doi: 10.1186/1756-0500-5-402.
Postnatal 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.
We 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.
In 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.
小肠黏液层的产后调节在成年肠道功能发育中可能具有重要意义。我们推测细菌定植的性质会影响生命早期的黏液基因调控。因此，我们分析了常规微生物群以及两种选定的单一定植细菌菌株对出生后第一周小鼠黏液层发育相关基因转录的影响。对来自不同定植状态母鼠的幼鼠（每组N = 8只）进行分析：无菌（GF）、常规无特定病原体（SPF）、单一定植嗜酸乳杆菌NCFM（Lb）或大肠杆菌Nissle（Ec），在出生后第1天和第6天（PND1、PND6）从分离的回肠组织切片通过qPCR分析：（i）参与黏液产生的特定基因（Muc1 - 4、Tff3）的转录，以及（ii）嗜酸乳杆菌和大肠杆菌的16S rRNA量。对16S rRNA基因进行定量以获得定植细菌量的测量值。
我们发现从PND1到PND6，所有五个黏液基因的转录增加与微生物群无关。此外，细菌的存在增加了PND1时某些黏液基因的相对转录水平。在SPF、Ec和Lb组中观察到Tff3的这种情况；在SPF组中观察到Muc2的这种情况；在Ec和Lb组中分别观察到Muc3和Muc4的这种情况。仅在PND6时且仅对一些定植动物检测到细菌16S rRNA基因水平高于qPCR检测水平。在PND6时，与嗜酸乳杆菌水平低于检测限的动物相比，嗜酸乳杆菌水平可检测的Lb动物中Muc1、Muc2和Muc4基因转录水平显著降低。
总之，我们的数据表明，分别编码分泌型（Muc2/Tff）和膜结合型（Muc1/Muc3/Muc4）黏液调节蛋白的基因表达的发育是不同的，并且这种发育的起始可能会因黏膜部位存在或不存在的特定细菌群而加速。
