The role of intestinal bifidobacteria on immune system development in young rats.
OBJECTIVE
The effects of intestinal bifidobacteria on the development of immunity in early life were explored.


METHODS
Neonatal SD rats born and housed under strict barrier systems were fed from birth with sufficient antibiotics (bifidobacteria minimisation group) or supplemented daily with 1x10(10) colony-forming units of live Bifidobacterium longum (bifidobacteria supplementation group). Relevant indices of immune development were determined at one, three and six weeks old.


RESULTS
Compared to the control group, minimisation of the intestinal bifidobacteria delayed maturation of dendritic cells in Peyer's Patches and the development of T cells in the thymus, increased IL-4 secretion in the plasma, down-regulated IL-12, IL-10 mRNA and the interferon-gamma/IL-4 mRNA ratio in intestinal mucosa, decreased interferon-gamma mRNA in cultured peripheral blood mononuclear cells (PBMCs), and reduced immunoglobulin-M production in cultured PBMCs. Conversely, supplementation with bifidobacteria promoted dendritic cell maturation in Peyer's Patches, up-regulated IL-12, IL-10, interferon-gamma mRNA and the interferon-gamma/IL-4 ratio in intestinal mucosa, increased interferon-gamma gene expression in cultured PBMCs, and raised immunoglobulin-M secretion in cultured PBMCs.


CONCLUSIONS
Intestinal bifidobacteria could promote the maturation of dendritic cells and its expression of IL-12 locally in the gut, influence the development of T cells in the thymus, favour the development of T-helper cell type 1 response by increasing the local and systemic expression of interferon-gamma and ensure the intestinal regulatory T cell response by promoting the local expression of IL-10. In addition, they enhance antibody synthesis by PBMCs, thereby affecting the development of both the gut and systemic immunity in early life.
Dong
Ping
P
Children's Hospital, Pediatrics Department of Shanghai Medical College, Fudan University, Shanghai, PR China.
Yang
Yi
Y
Wang
Wei-ping
WP
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001644:Bifidobacterium / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D007107:Immune System / Q000254:growth & development* / Q000382:microbiology*; D007375:Interleukin-1 / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology; D007422:Intestines / Q000276:immunology / Q000382:microbiology*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000382:microbiology; D008213:Lymphocyte Activation / Q000276:immunology; D010581:Peyer's Patches / Q000276:immunology / Q000382:microbiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology / Q000382:microbiology; D013950:Thymus Gland / Q000276:immunology / Q000382:microbiology
D007375:Interleukin-1; D015847:Interleukin-4