Translational research to study the effect and mechanism of microbiota in paediatric immune-mediated diseases.

According to the hygiene hypothesis, the increase in immune-mediated diseases
(IMD) during the last decades may be due to decreased contact with (parts of)
microbiota in early life. This contact may be necessary for a normal and
balanced development of the immune system. Therefore, along these lines, immune
mediated diseases may be prevented or treated by the administration of (parts
of ) microbes. Recently we have selected three probiotics species by in vitro
exposing peripheral blood mononuclear cells (PBMC*s) to several microbiota that
had been shown in previous research to be able to pass the stomach and to
adhere to intestinal epithelium. Subsequently, we administered this particular
combination of microbiota to pregnant allergic women during the last 6 weeks of
pregnancy and to their high-risk offspring during the first 12 months of life.
This resulted in a lower prevalence of eczema at the age of 3 months (OR 0.3,
95%CI=0.2-0.9). These preliminary results made us continue research in this
field. Next to allergies, Juvenile Chronic Arthritis (JCA), Diabetes Mellitus
type I (IDDM), Atopic Dermatitis (AD) and Crohn*s disease (=CD; together with
Ulcerative Colitis representing Inflammatory Bowel Disease=IBD) are all
prevalent diseases, mediated by the immune system. In this project we will
select probiotic species by in vitro exposing PBMC*s of children with the
diseases mentioned, to several microbiota and measure the production of
cytokines by PBMC's as well as determining the phenotype of PBMC's. PBMC*s will
subsequently be exposed to the selected bacteria in a trans-well system with
human gut epithelial cells to confirm the data. PBMC's will be added to the
basolateral compartment, while probiotics are added apically of the cell line
Caco-2.

In vitro selection of microbiota that can be used in a subsequent trial with
children with IMD. The selection will be made based on the cytokine profile and
immune cell characterization after co-culture of PBMC*s with bacteria.
Influence of human gut epithelial cells will be studied in a trans-well system.

In vitro study with PBMC's isolated from blood obtained from children with IMD.

Risks and burden for subjects are considered minimal. Subjects will be invited
for the subsequent interventional study with selected probiotic bacteria if
they wish. Blood will be withdrawn simultaneous with routine withdrawal as much
as possible.