2. 2 | GENOMICS GENOMICS | 3
The challenge: to find the perfect
in vitro safety assessment
All over the world, safety-concerned pro-
fessionals in regulatory organizations are
asking the same question: Are we ready to
trust current methods for assessment of
sensitizers? Can they really replace tradi-
tional animal testing?
We know that sensitizers exercise their
harmful effects by triggering a multitude of
intricate mechanisms in the exposed tissues.
At the same time, we want the testing pro-
cedures to be simple, cost-effective, reliable
and conclusive. The technical challenge is to
understand a very complex case by using a
straightforward assay.
Enter genomics!
By using biomarker signatures, genomics
combines the straightforwardness of in vitro
testing with the biological intricacy of in vivo
models. It represents a big step towards a
future scenario where the use of lab animals
is an exception for safety testing purposes.
How do we reach the
predictivity we actually
need?
Is it really rational
still to handle lab
animals in 2016?
The assays we use
deliver results alright
– but are they relevant?
SIMPLICITY
INFORMATIONAL CONTENT
In vivo
Genomics
In vitro
MANY IN VITRO TESTS FOR
SENSITIZERS ON THE MARKET
ARE FAIRLY SIMPLE TO PER-
FORM, BUT THEY ARE OFTEN
NOT CONCLUSIVE ENOUGH TO
GIVE REASSURING RESULTS.
GENOMICS-BASED MODELS, ON
THE OTHER HAND, OFFER A
RELIABLE ALTERNATIVE TO
ANIMAL TESTING.
FINDING THE BALANCE
3. 4 | GENOMICS GENOMICS | 5
Building scientific models
which are closer to reality
Traditionally, science has taught and applied
the principle of reductionism. Researchers
have studied one detail at a time, eliminating
all complicating factors.
In modern life science, a holistic way of
thinking has emerged with the advent of
new, advanced methodologies. By using spe-
cial technology, researchers can study intri-
cate systems, where innumerable concerted
actions take place at each moment.
One such methodology is genomics, where
literally thousands of genes (DNA) and their
messengers (mRNA) can be studied simulta-
neously (see fact box on page 12).
This has changed the perspective of the
whole research field which has gone from
reductionism to holism. This systematic
approach makes it possible to design safety
assessment models which are reassuringly
close to reality.
REDUCTIONISM
• Focuses on one detail at a time
• Studies one causal chain at a time
• Tries to eliminate effects from the
context
A simple model
AN IN VITRO MODEL,
WHERE FEW POINTS
ARE MEASURED, GIVES
NON-CONCLUSIVE
RESULTS.
Genomics
BY MEASURING A LARGE
NUMBER OF PARAMETERS,
THIS MODEL MIMICS
REALITY AND GIVES
CONCLUSIVE RESULTS.
Reality
HOLISM
• Focuses on the whole
• Interested in the concerted effect of
many details
• Studies how details are influenced by
the context
4. 6 | GENOMICS GENOMICS | 7
An intricate response to
foreign substances
When the tissues of a living organism are
exposed to a harmful agent, a number of
biological processes are set in motion. The
interior of the affected cells can be compared
to a city which is hit by a natural disaster—
sirens sound in the street, fire fighters are
alerted, vehicles hurry along the streets …
The guardians of the skin are dendritic cells.
When exposed to a sensitizer they will react
like the alarmed city and trigger an intricate
response where different types of proteins
are produced. The functions of these proteins
are described below. (Read more about the
immune system on page 13.)
CELLULAR RESPONSES
Recognition of foreign substances
Activation of immunological self-
defence mechanisms of the host
Cellular stress responses
Communication with other cells
of the immune system
BLOOD VESSEL
DERMIS
EPIDERMIS
THE DENDRITIC CELLS ARE PRESENT IN TISSUES THAT ARE IN CONTACT
WITH THE EXTERNAL ENVIRONMENT, E.G. IN THE DERMIS LAYER OF THE
SKIN. ITS BRANCHED STRUCTURE HELPS IT CATCH FOREIGN SUBSTANCES
WHICH PENETRATE THE OUTER LAYER OF THE SKIN, THE EPIDERMIS.
THE RECOGNITION OF
FOREIGN SUBSTANCES LEADS
TO ACTIVATION OF VARIOUS
MECHANISMS IN DENDRITIC
CELLS, LEADING TO CHANGES
IN CELL FUNCTION AND
APPEARANCE. THESE CHANGES
ARE ALL CONTROLLED BY
GENE REGULATION, WHICH
COULD BE MONITORED BY
E.G. GENOMIC TECHNIQUES.
5. 8 | GENOMICS GENOMICS | 9
The GARD method
mimicsthe immune system
GARD is a state-of-the-art assay. It predicts
the ability of chemical compounds to induce
skin sensitization. GARD uses a genomic
biomarker signature to predict the sensi-
tizing ability of chemical compounds. These
biomarkers represent the various activated
mechanisms in dendritic cells in response
to foreign substances. This is why GARD
exhibits the highest predictive performance
of assays currently on the market.
Cultivated dendritic cells are exposed to a
test substance. The genomic transcripts
from the cell—the mRNA—are collected.
SENSITIZER
NON-SENSITIZER
GARD utilizes tailor-made software based on
advanced algorithms to transform the data
to clear and conclusive results. The collected
data are analyzed with statistical prediction
models in easy-to-use application-based
software.
The mRNA is identified and measured by
automated equipment, by the use of reporter
probes.
6. 10 | GENOMICS GENOMICS | 11
The key to GARDs superior predictive perfor-
mance lies in the way data are analyzed. By
utilizing advanced machine learning tech-
niques, we are able to turn a vast collection
of raw data—originating from the measure-
ments of hundreds of genomic biomark-
ers—into a single answer: Sensitizer or
Non-Sensitizer.
While the raw data are very complex, GARD
generates decision values that are easily
interpreted. A decision value greater than
zero indicates a sensitizer (here illustrated
in red), while decision values smaller than
zero indicate a non-sensitizer. These clas-
sifications are directly related to the level of
activation induced in the dendritic cell when
challenged by a test substance.
Advanced computer calculations give
conclusive and clear results
7. 12 | GENOMICS GENOMICS | 13
Q&A GENOMICS
What is the relation between DNA and
mRNA and proteins?
Life on Earth is based upon the organized
activity of proteins. The chemical structure
of these proteins is described by the DNA.
In multi-cellular organisms, the DNA is
stored in the cell nucleus, whereas the
production of proteins takes place outside
the nucleus. The information is transferred
from the nucleus to the protein-building
machinery in the form of mRNA, messen-
ger RNA. It may be compared to a factory
where the master blueprints are stored in
the office and the staff make copies which
they use at their work-stations.
Hence, if a molecular biologist wants to
study which proteins are produced in a cell
at a certain time, he or she can choose to
study mRNA instead. This is what is being
done in the GARD technique, described in
this brochure.
What is “omics”?
In the early nineties, an international net-
work of scientists started a project with the
goal to map the human genome, the HUGO
project. This huge endeavor gave a big boost
to the technical development of methods
which speeded up the lab work, and it now
makes it possible to study a large number of
things in parallel in living cells.
As the study of the genome is called ge-
nomics, an entire family of related -omics
areas were established in this way: tran-
scriptomics (mRNA), proteomics (proteins),
metabolomics (products of the metabo-
lism) et cetera.
Q&A IMMUNOLOGY
What is a dendritic cell?
The dendritic cell (from the Greek word
déndron, meaning ‘tree’) is a type of white
blood cell (leukocyte). It serves as a sen-
tinel which catches antigens, i.e. foreign
substances that have entered the body.
Once activated, it will migrate to local
lymph nodes where it alerts and interacts
with other white blood cells of the immune
system, primarily T cells.
What is a T cell?
The human immune system—protecting us
against microbes and foreign substances—
is an extremely complicated functional net-
work of cells, proteins and other signaling
factors. In short, it consists of a basic, uni-
versal defence which we are born with and
a customized defence against things that
we encounter during our lifespan. The T
cell (named so because they mature in the
thymus) is a type of white blood cell which
plays a central role in this so called adap-
tive immune system. It carries our “immu-
nological memories” and makes it possible
to develop immunity against diseases we
have previously encountered.
What is sensitization?
Chemical hypersensitivity (also called
chemical allergy) is a disease state induced
by the human immune system in response
to chemical sensitizers and is initiated by
a process termed sensitization. Chemicals
that are frequently reported to induce
chemical sensitization include metal ions,
fragrances and cosmetic additives and
dyes. Sensitizers are typically small mole-
cule chemicals which are able to penetrate
the skin, where they activate dendritic cells
and initiate an immune reaction. Sensi-
tization occurs when the T cells learn to
recognize a specific sensitizer. Following
subsequent exposure, the primed T cells
—which have now established an immuno-
logical memory—react rapidly to induce a
state of inflammation. This in turn leads to
the disease-associated symptoms, such as
itching, blistering and tissue damage.Transcription
Translation
DNA
mRNA
Protein
8. 14 | GENOMICS GENOMICS | 15
One more thing:
mice are not men
The golden standard of sensitization
assays—animal tests on mice.
The future of sensitization assays
—GARD.
Predictive performance
9. 16 | GENOMICS
Immunotoxicological
assays, based
on genomics
SenzaGen is a Swedish in vitro test lab company, spe-
cializing in genomics-based methodology for immu-
notoxicological assays. Our proprietary lead product,
GARD, utilizes genomic biomarker signatures of hun-
dreds of genes relevant for hazard prediction. Doing
so, it predicts and classifies chemical sensitizers with
a state-of-the-art predictive performance. This bro-
chure explains some of the basic concepts which form
the scientific foundation for GARD.
SenzaGen was formed in 2010 as a spinoff from the
research being performed at the Department of
Immunotechnology at the Faculty of Engineering,
Lund University. The company is based at Medicon
Village in Lund, Sweden.
GARD—Genomic Allergen Rapid Detection
SENZAGEN AB
MEDICON VILLAGE
SCHEELEVÄGEN 2
223 81 LUND
SWEDEN
SENZAGEN INC
1260 LAKE BLVD
SUITE 209
DAVIS
CA 95616
USA
WWW.SENZAGEN.COM
