Tiziana Borsello talks with
ScienceWatch.com and answers a few questions about
this month's Fast Moving Front in the field of
Neurosciences & Behavior. The author has also sent
along images of their work.
Article: A peptide inhibitor of c-Jun N-terminal
kinase protects against excitotoxicity and cerebral
T;Clarke, PGH;Hirt, L;Vercelli, A;Repici,
M;Schorderet, DF;Bogousslavsky, J;Bonny, C
Journal: NATURE MED, 9 (9): 1180-1186 SEP 2003
Addresses: Univ Lausanne, Inst Biol Cellulaire &
Morphol, Rue Bugnon 9, CH-1005 Lausanne, Switzerland.
Univ Lausanne, Inst Biol Cellulaire & Morphol, CH-1005
Dept Anat Pharmacol & Forens Med, I-10126 Turin,
(addresses have been truncated)
Why do you think your paper is highly
We believe that this paper is of general interest in the field of
neuroscience since it illustrates the death of neurons during stroke and a
possible way to prevent death. This is a hot field. Stroke is one of the
leading causes of death and long-term disability and despite intensive
research efforts there are currently no effective treatments.
We believe that the results presented in this paper open new frontiers
against ischemia. In fact, the neuroprotectant used in this work, D-JNKI1,
prevents the activation of the JNK enzyme, involved in death signalling
pathways, and powerfully protects against stroke in experimental models.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
Yes, we proved for the first time that it is possible to prevent the death
of neurons after stroke by using a new methodology.
The discovery: By preventing JNK action it is possible to avoid neuronal
death after stroke. The compound used, D-JNKI1, prevented 90% of the lesion
(generated by the ischemia) in the brain. More importantly, targeting the
JNK cascade in a very specific way (see methodology), provides a promising
therapeutic approach for ischemia. This is because the injection of the
neuroprotectant within 6-12 hours after the brain injury still resulted in
a powerful protection and we still obtained a reduction of the infarcted
zone of 50-90%. This is considered a useful temporal window for treating
human patients after ischemia.
The methodology: We described the possibility of targeting protein
complexes and enzymes involved in intracellular death signalling pathways
by means of cell permeable peptide (CPP). The CPP represents a novel,
versatile, and extremely powerful way of blocking the propagation of
intracellular processes, with an unprecedented specificity allowing for
reduction of side effects.
Would you summarize the significance of your paper
in layman's terms?
Despite a considerable worldwide research effort, current therapies for
stroke are of limited efficacy. In cerebral ischemic stroke, which is the
most common kind, the occlusion of a blood vessel inside the skull deprives
brain tissue of oxygen and nutrients, leading to the death of many neurons.
The brain insult (stroke) triggers biochemical intracellular cascades
activation (chains of reactions) inside neurons that ultimately kill them.
This sequence of events has been studied for almost 20 years, and
scientists were quick to develop drugs to prevent it, by studying different
neuroprotective agents. All these studies raised hopes for a clinical
breakthrough, because when given to rats and mice at the time of
brain-artery occlusion, the neuroprotective agents prevented much of the
brain damage. But, when used in the incidence of human stroke, they were a
dismal failure, partly because they protected the brain only when given at
the time of ischemia or within the next 2-3 hours, whereas few stroke
patients reach the hospital that quickly.
Our results, as published in this paper, offer new hope for stroke
treatment. We showed for the first time that a novel drug can strongly
protect the brains of adult mice and baby rats even when given 6-12 hours
after the ischemia. Such late treatment had always been a theoretical
possibility, because most of the neuronal death occurs relatively late
(within 6-24 hours) after ischemia. This is the first drug to actually
achieve such a strong protection during such late administration.
These studies really offer a possible basis for stroke therapy. In fact,
Xigen S.A., a Swiss biopharmaceutical company that concentrates on research
and development of novel peptide therapeutics, is now developing the
clinical trial of this compound in Lausanne, Switzerland.
How did you become involved in this research and
were there any particular problems encountered along the way?
Neuronal death plays a critical role in most of the important neural
pathologies, including stroke, epilepsy, Parkinson's disease, Alzheimer's
disease, and multiple sclerosis. This is why an understanding of the
mechanisms of neuronal death is our main challenge. To identify some death
pathways is in fact very important and to achieve neuroprotection is one of
the primary interests for the neuroscientist. An understanding of the
control mechanisms of neuronal death allows the development of new tools to
prevent it. In 2000, I was studying neuronal death in vitro. The
overall goal of my studies was to establish the molecular details of signal
transduction pathways that are initiated by environmental stress (in this
case: excitotoxicity in vitro) and lead to the regulation of the
neuronal death machinery.
In particular, I was studying the JNK cascade role in neuronal death and I
was aware of the inhibitor peptide D-JNKI1 because I was working near Dr.
Christophe Bonny's lab and he designed this inhibitor for preventing the
cell death of pancreatic cells in the field of diabetes research. He agreed
to work with me and we began our collaboration.
I was the first to utilize the peptide in the central nervous system, and
to characterize its distribution inside cells and its neuroprotective
functions in neurons. I first tested D-JNKI1 in the in vitro model
to prevent neuronal death and, since it worked so well, I immediately
decided to move to in vivo models. I finished two collaborations
in order to verify if the powerful neuroprotection found in vitro
was also maintained in vivo model, which it was.
We had many difficulties due to the long-term of these studies and also due
to the intrinsic difficulties you find while working with other
laboratories. But we succeeded and discovered the powerful neuroprotective
capabilities of this compound. We understood the enormous implications this
would have in acute diseases and in fact, our study is still going on in
this field, but now we are also focusing on the possibility of its
application in different brain insult models and in chronic diseases (my
ongoing studies at the Mario Negri Institute in Milano, Italy). In the
meantime, other authors discovered many different paradigms in which
D-JNKI1 protects against neuronal death in the central nervous system.
Seeing the wide range of applications for our discovery is for us the
Where do you see your research leading in the
The research of my laboratory is heading in three main directions.
First, in our view, the most significant challenge in this area is
developing CPPs to treat chronic diseases. We are performing the first CPP
treatment in a chronic in vivo model of neurodegenerative disease
and we've now received very encouraging results. However, we still have
plenty of additional work to do in this direction.
Secondly, we are now looking for new important key modulators of neuronal
death pathways, with the aim of determining if they can be targeted for
therapeutic intervention. This is because neurons may decide to die in many
different ways and clearly distinct pathways are involved in their death
Third, this is a methodology improvement. One of the limitations of the
CPPs methodology is the poor control of the delivery, in fact these CPP
compounds diffuse over all the tissues in the body. We are currently at
work on having a spatio-temporal control of CPP delivery: this will reduce
possible side effects and will enhance the efficacy.
Do you foresee any social or political
implications for your research?
The costs of stroke are enormous. In Europe and the USA, 2-6% of all health
care costs—on average 0.27% of the GDP—are spent on direct
stroke care, inclusive of the costs of hospital and nursing home care, the
services of physicians and other medical professionals, drugs, appliances,
and rehabilitation. (See: Evers S, et al., "International
Comparison of Stroke Cost Studies," Stroke 35:1209-15, 2004.)
Indirect costs, defined as production losses, further increase the burden
of the disease. In Europe, direct costs are in the range of 3,000-16,000
euros per patient during the first year, whereas the lifetime direct cost
may reach 30,000 euros. Taken together, direct and indirect costs may be as
high as 20,000-26,000 euros per patient in the first year. In Europe, 22
billion euros are spent on stroke annually (See: Truelsen T, et
al., "Cost of stroke in Europe," Eur. J. Neuro. 12, Suppl
The growing number of subjects with stroke is likely to increasingly burden
health and social systems in the future. The situation may be worsened by
the estimated decrease in the European population, shifting the dependency
ratio, with fewer young people supporting an increasing proportion of
elderly people. In addition to stroke, the overall health impact of chronic
neurodegenerative diseases is certainly more than merely obvious.
Tiziana Borsello, Ph.D.
Neuronal Death and Neuroprotection Unit
Istituto Di Ricerche Farmacologiche
Keywords: cerebral ischemic stroke, neurons, ischemia, neuronal death,
D-JNKI1, JNK enzyme, cell permeable peptide (CPP), costs of stroke, euros
per patient, chronic neurodegenerative diseases.