500NL project

Several factors have been demonstrated to date to have a crucial effect on the
susceptibility and outcome of infections and (auto)inflammatory diseases: (1)
the genetic make-up of the individual, (2) the colonizing microorganisms on its
skin and mucosae, and (3) variations in the immune responses.

(1) The knowledge about DNA polymorphisms has become a valuable parameter for
assessing risks to develop many important human diseases. Recently, we (and
others) have demonstrated that polymorphisms in immunity-related genes lead to
differences in susceptibility to fungal diseases (1), bacterial infections such
as Borrelia or Bacteroides (2, 3), arthritis (4), or autoimmune disorders such
as inflammatory bowel disease of Crohn*s disease (5, 6).

(2) Next to differences in DNA patterns, it could also be demonstrated that the
presence of certain microorganisms in the gut (e.g. probiotic bacteria) are
able to influence the cytokine production and possible the clinical outcome (7,
8). All vertebrates display complex communities of microorganisms on body
surfaces, called the microbiome or microbiota. However, most of these microbes
are not cultivable and therefore 16S sequence analysis has proven to give
crucial information regarding the complexity of microbial communities on the
skin and mucosae (9). The knowledge about the variation in the human gut will
be increased in a second project called the Human Microbiome project (10). A
search on PubMed indicates the exponential growth of this discipline (0 in 1999
against 865 articles in 2011). The microbiome was demonstrated to give valuable
information about the origin, lifestyle, development of immune responses,
infections, metabolic and autoimmune diseases (11). Next to microbial patterns
in the gut, urine and skin samples were also described to give valuable
information in health and disease (12, 13). It could be demonstrated that the
microbial components present in the human body can be related to immune
responses or autoinflammatory disorders (14, 15). Therefore, it is plausible to
link the differences in microbial status and illnesses (16).

(3) Next to the presence or absence of certain groups of microbes in disease,
the phenotype and function of circulating cells might also differ between
health and disease. In HIV/AIDS patients is the best example described, a
typical mark of this disease is decreased CD4+ T cell circulation. Next to
HIV/AIDS, CD4+ T cells were also described to differ in certain stages of
tuberculosis (17), arthritis (18) and Crohn*s disease (19). Next to T cells,
other cell types, such as dendritic cells, may also change their phenotypic
characteristics during disease (20).
The capacity of immune cells to produce cytokines and chemokines has proven to
be highly important in health and disease. Differences in cytokine production
were linked to several diseases, including Lyme disease (2), Crohn*s disease
(6), but also fungal infections with for example candida (21). Individuals with
altered cytokine responses were reported to be highly susceptible for the
development of disease.

Despite the research that has linked each of these processes to the
susceptibility to disease, practically nothing is known how they influence each
other and how does this interaction relate to the various diseases. In other
words, it is not known whether genetic polymorphisms influence the composition
of the microbiome, how these two factors together modify the immune response of
the host, and what are the consequences for the susceptibility to infections or
(auto)inflammatory disorders. This is the aim of the recently awarded
ERC-Consolidator Grant (nr.310372) to M.G. Netea, that stays at the core of
this study.

Therefore, we will assess by systems biology and pathway analysis the
interaction between the DNA polymorphisms on the one hand, the microbiome of
the skin, intestinal tract and vagina, and the immune responses in a large
group of healthy individuals. After assessing the interaction of these factors
in healthy controls, we will assess whether this balance is distorted in
certain patients groups with infections or (auto)inflammatory disorders.

The aim of the study is to test the hypothesis that susceptibility to and
severity of certain infectious and inflammatory diseases can be explained by
the interaction between the genome, microbiome and immunological responses:
i.e. presence of polymorphisms, differences in microbial composition,
differences in phenotypes and/or of circulating cells (altered cytokine
production).

Specific research questions are:
1. Do genetic variations influence the immune responses and subsequently the
susceptibility or severity of disease?
2. Is there a difference in the composition of the microbiome between healthy
and patient groups?
3. Is the colonization with certain classes of microorganisms influenced by
genetic polymorphisms of the host?
4. What is the phenotype and function of the circulating cells in patients and
controls, and is that influenced by the gene polymorphisms on the one hand, and
microbiome on the other hand?

The study comprises a case-control study. The duration of the study is 3 years
and will be performed in the Radboud University Nijmegen Medical Centre
(RUNMC), in collaboration with Harvard School of Medicine and UMC Groningen.
Patients will be recruited from the RUNMC.

Burden:
- For patients and controls: collection of venous blood, if possible during
regular blood sampling. This comprises a maximum of 1 heparin tube à 10 ml, 1
PaxGene tube a 8 mL, 1 citrate tube a 3 mL and 6 EDTA tubes à 10 ml and 1 serum
tube à 5 ml.
- For controls: the same as for patients, but blood sampling for the purpose of
this study only will be necessary in all cases.

Risks:
- No risks other than local hematoma are related to venous puncture.

Benefit:
There will be no benefits for the subjects enrolled in this study.