Epigenetic biomarkers to predict psoriasis disease progression * towards tailored therapy.

Psoriasis is a chronic inflammatory disorder that affects skin and joints. Its
pathogenesis is multifactorial, being determined by a number of genetic risk
factors and environmental influences. The disease process involves defective
skin barrier repair and an attendant deregulation of innate immune responses to
noxious agents, including bacteria and trauma, causing inflammation.
Eventually, the adaptive immune system comes into play and maintains the
inflammatory response through a.o. TNF-alpha and IL12/23 signalling. A subset
of T helper cells, Th17, probably has a pivotal role in the sequence of events
outlined above. However, the entire process likely starts in the epidermal
barrier and its major constituent, the keratinocyte. Psoriasis is a chronic
disease that once it has manifested will show varying activity with spontaneous
remissions and relapses. Psoriasis negatively impacts quality of life and may
be associated with significant comorbidities such as metabolic syndrome that
may be attributable to chronic inflammatory activity. In addition, at least 30%
of patients will develop psoriatic arthritis, which can lead to joint damage
and invalidity. Thus, psoriasis potentially is a severe systemic disorder that
can cause significant morbidity.

In analogy to rheumatoid arthritis, it is likely that early intervention with
disease-modifying drugs (such as biologics) could prevent arthritic damage and
other long-term complications in people with psoriasis. This concept has proven
its worth in the treatment of rheumatoid arthritis, where early intervention
with DMARD (disease-modifying antirheumatic drugs) has significantly reduced
the incidence of invalidity. Among such DMARDS are targeted human and humanized
monoclonal antibodies that suppress TNF alpha and IL12/23 signalling, such as
adalimumab. These have proven to be highly effective in treating psoriasis,
being capable of reducing PASI scores with up to 90%. They are also very
effective against psoriatic arthritis. However, we cannot predict at present
which patients will go on to develop arthritis and other long-term
complications. It is quite possible that there are many patients who should
receive biologics because they will develop complications, but do not get them
now because their apparent disease severity does not seem to warrant it.

Therefore, it is highly desirable to have a set of biomarkers that can predict
disease progression for individual patients. Being able to preselect
individuals who stand to benefit the most from therapy with a biologic would
make it economically feasible to use biologics in order to prevent long-term
complications of psoriasis in such patients. These biomarkers are not yet
available, although considerable effort is being spent on attempts to identify
those (more than 1500 PubMed hits by mid-2013). Current efforts focus on
genetic and (serum) inflammatory markers, but so far with little success.
Certainly, there are no serum or tissue markers available that can indicate the
risk of disease progression.

Here, we propose an innovative approach to prognostic biomarker development,
using a biological phenomenon that has been largely ignored in psoriasis and
other inflammatory skin disorders. We leverage our experience with novel
high-throughput technology that has the potential to deliver relevant
biomarkers in a relatively short time span.

It is well known that psoriasis has a strong hereditary component1, although
environmental influences have a crucial role in triggering disease expression.
It is not known why the disorder persists once it has become manifest. There
are no known genetic or environmental factors that could explain this
phenomenon.

Primary Objective:
To define a top set of genes that most reliably (r >=0.95) distinguish
psoriasis from normal skin. We will define this set from differential
methylation genes to indicate potential biomarkers.

Secondary Objective(s):
Methylome analysis will also give answers to these questions:
1) Is the global methylation pattern in psoriatic skin different from normal
skin in people with psoriasis?
2) Is global methylation of unaffected skin different between people with and
without psoriasis (* can we detect an epigenetic predisposition?)
3) Which gene promoters are differentially methylated between the two major
types of psoriasis and normal skin?
4) Do these genes together with the RNA data point to pathways already known to
be involved in the pathogenesis of psoriasis, and are any novel pathways
suggested that might present therapeutic targets?
5) Does the guttate psoriasis methylome differ from that of plaque psoriasis?

After we have found potential biomarkers, these will then be validated and
developed in a prospective translational trial aimed at obtaining markers that
predict disease progression.

Study design
The proposed study is a nonrandomized non-therapeutic observational clinical
study with taking four biopsies and a blood sample as an intervention at t=0.
While we are only using this patient material ex-vivo in a laboratory, there is
no follow-up planned for the patients/subjects.

Duration
We expect the study to take approximately 18 ± 3 months: 3 months for patient
recruitment, 6-9 months for DNA/RNA analysis and 9 months for data analysis and
marker selection.

Setting
The study will take place at the Maastricht University Medical Centrum + during
2014. Patients are sent to de Department of Dermatology by their general
practitioner or peripheral dermatologist. If patients meet the inclusion
criteria the resident or dermatologist will ask if they will participate in
this psoriasis project. If the subject agrees, the investigator will include
the patient in the study. If there is a partner joining the patient in the
physicians room, the partner will be asked to participate in the study as a
control individual. If there are insufficient partners willing to participate
as a control individual, we will ask partners of patients with psoriasis not
meeting the inclusion criteria.

Justification of study design
For this study we firstly would like to analyse the entire methylome and
transcriptome, to define a set of differentially methylated genes that will
indicate potential biomarkers. Therefore a nonrandomized non-therapeutic
observational clinical study is adequate.

Flow chart
Not applicable

There is very little risk involved in participating in the study. Taking a
biopsy and taking a blood sample are routine techniques that we use extremely
often in clinical practice in normal diagnostics. We will use an anaesthetic
for the skin before taking the biopsy. The lidocaine 1% sometimes gives an
itching of painful feeling for a moment. Taking the biopsies causes no
discomfort because of the anaesthetics. Taking the blood sample with a
venapuncture is hardly painful. The overall burden is minimal.

There are some minor risks involved in taking the biopsies and the blood
sample. These are also mentioned in the information for the subjects.
- After taking a biopsy a small scar may develop. Normally this scar is small
and after a while it will be hardly visible. Some patients tend to develop
excessive scar formation. If a subject is known to have excessive scar
formation, this is an exclusion criterium for this study.
- During biopsy and venepuncture there may be some minimal blood loss. Normally
we will stop it by compression. It is also possible that, after a while, the
venepuncture or biopsy site can start bleeding again. Subjects will receive
information on how to handle this kind of bleeding, which is innocuous.
- Another potential risk is a wound infection. This can be treated relatively
easily. Subjects will receive information on how to recognize a wound infection
and what to do in that case.
- In very rare cases taking the biopsy will damage a superficial cutaneous
nerve. As a result, a small area of the skin will feel numb for some weeks to
months. Usually, feeling will return to the affected area.

Psoriasis negatively impacts quality of life and may be associated with
significant comorbidities such as metabolic syndrome that may be attributable
to chronic inflammatory activity. In addition, at least 30% of patients will
develop psoriatic arthritis, which can lead to joint damage and invalidity3.
This research will contribute to defining biomarkers for these long-term
complications of psoriasis. As written in the introduction, early intervention
could prevent arthritic damage and other long term complications in people with
psoriasis4.

The risks and burden of participating in the study are minimal; the potential
benefits could be very significant.