INVESTIGADORES
DE MORENO Maria Alejandra
congresos y reuniones científicas
Título:
Activation of the innate immunity by probiotic bacterium and a fermented milk containing this microorganism
Autor/es:
C. MALDONADO GALDEANO; A. DE MORENO DE LEBLANC; C. DOGI; S. CHAVES; E. CARMUEGA; R. WEILL; G. PERDIGON
Lugar:
Valencia, España
Reunión:
Workshop; 1st International Immunonutrition Workshop; 2007
Resumen:
Improvement of the immune status of the host is one of the beneficial properties attributed to
probiotics. Previous results have shown that the effect induced by a probiotic strain Lactobacillus
casei CRL 431 is through innate immunity.
The present work investigated the behaviour of another probiotic bacterium Lactobacillus
casei DN 114001 in relation to the interaction between the epithelial and immune cells, using mice
as the experimental model. Using electron microscopy and fluorescent bacteria it was demonstrated
that this bacterium interacts with the intestinal epithelial cells and the small fragments of the
bacterium can internalize and make contact with the immune cells (macrophages and dendritic
cells) present in Peyer patches and in the lamina propria of the small and large intestine. These
antigenic particles remain in the gut for 72 h, similar to other particulate antigens.
A subsequent study investigated the effect of the inclusion of this probiotic bacterium in
fermented milk on the mucosal innate immune system of the gut in BALBc mice. The fermented
milk was administered to the mice for five consecutive days, which was previously determined to
be the optimal dose to stimulate the immune response. At the end of the administration period the
animals were killed and the small and large intestine was removed for the determination of: (a) the
number of IgA- and cytokine (IL-10, interferon _ (IFN-g), TNF_)-producing cells in histological
slices of both intestines; (b) the expression in the lamina propria of the small intestine of the
different receptors present in the immune cells involved in the innate immunity, e.g. mannose
receptor CD206 present in macrophages or on the dendritic cell surface (this receptor participates
mainly in the internalization process and in antigen clearance); (c) Toll-like receptor 4 (TLR4),
which is involved in the adhesion and pro-inflammatory signals induced by pathogenic bacteria, as
a measure of possible adverse effects. Increases were found in the number of IgA-, TNF_- and
IFNg-producing cells in both intestines. The anti-inflammatory cytokine IL-10 also showed a
significant increase in relation to the control (without fermented milk). This increase may have been
induced to down regulate the mucosal response. The receptor CD206 was slightly increased, but
TLR4 was unchanged. These results showed that innate immunity is involved in the gut mucosal
immune activation observed, and led to an investigation of the effect of the consumption of this
fermented milk in early period of the life, when the maturation of the innate immune cells occurs.
After weaning, newborn mice received the fermented milk until the adulthood (45 d of age). The
number of cells positive for maturation markers, such as F4/80+ cells (macrophages) and 33D1+
cells (dendritic cells) were determined in the small intestine. The expression of these markers
increased in treated animals compared with the control group (newborn mice not receiving
fermented milk).
These results demonstrate that the probiotic bacterium or its fragments interact with
epithelial and phagocytic immune cells associated with the gut. This observation is reflected in the
results obtained with the fermented milk, which show an increase in the number of CD206 receptors
and activation of the immune cells associated with the gut, with an increase in cytokine- and IgA+-
producing cells.
The results for the specific markers of maturation of the macrophages and dendritic cells in
adult mice (45 d of age) that received the fermented milk after weaning are in agreement with those
of previous studies.
It has been demonstrated that fermented milk containing the probiotic strain L. casei DN
114001 can modulated the gut immune response mainly through the innate immune system by
increasing the receptors related to maturation of the macrophages and dendritic cells associated with
the gut, by activating these cells and by increasing the number of IgA+ B-cells.