download report - Istituto Pasteur

P a r t i c i p a n t s :
Sergio Fucile, Francesca Grassi, Eleonora Palma, Davide
Ragozzino, professors; Flavia Trettel, researcher; Myriam
Catalano, Clotilde Lauro, post-doc fellows; Raffaela
Cipriani, Fabrizia Sobrero, PhD students; Giuseppina
Chece, technician.
C o l l a b o r a t i o n s :
Istituto Mario Negri, Milano (Dr. Pietro Ghezzi, Dr. Pia Villa);
Dipartimento di Fisiologia e Farmacologia, Sapienza-Università di
Roma (Dr. Letizia Antonilli, Dr. Valentina Brusadin);
Karolinska Institute, Stockholm, Sweden (Dr. Bertil Fredholm);
Università di Roma Tor Vergata (Dr. Angelo Spinedi).
Report of activity
Chemokines and their receptors play important roles
in the CNS both under physiological and pathological
conditions. The main aim of our research project
is to investigate the physiopathological activities of
chemokines as modulators of neuronal and glial
functions, identifying the molecular pathways
involved. In the last two years, we have been mainly
involved in the study of the neuromodulatory activity
of two chemokines: fractalkine/CX3CL1 and
IL8/CXCL8.
Neuroprotective activity of CX3CL1
The activities of CX3CL1 as neuroprotective substance
has been deeply investigated in vitro in neurotoxicity
models. Several evidences indicate that
chemokines have both neurotrophic and neuroprotective
activities and their production could also represent
a defensive response toward toxic insults: the
trophic and neuroprotective action of chemokines
has been demonstrated in different neuronal systems,
like hippocampal (Meucci et al., 1998; Araujo and
Cotman, 1993), cortical (Bruno et al., 2000) and cerebellar
granule cultures (Limatola et al., 2000a), as
well as in oligodendrocytes precursors (Robinson et
Principal investigator: Cristina Limatola
Professor of Physiology
Dipartimento di Fisiologia e Farmacologia
Tel: (+39) 06 49690243; Fax: (+39) 06 49910851
cristina.limatola@uniroma1.it
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Molecular recognition in biomolecules - AREA 4
Molecular and functional approaches to investigate the
physiopathological role of the chemokines and their receptors
in the central nervous system
al., 1998). The chemokine RANTES specifically protects
cortical neurons from Aβ-induced toxicity
(Bruno et al., 2000), while IL8/CXCL8 protects cerebellar
granule neurons from apoptosis (Limatola et
al., 2000). CX3CL1 is a unique chemokine belonging
to the CX 3 C subfamily, that is present both as soluble
and membrane anchored forms (Baggiolini et al.,
1998). Recent evidence indicates that this chemokine
mediates microglial-neuron communications; in particular,
neuron-derived fractalkine regulates
microglial activation, affecting microglial survival
(Streit et al., 2001).
We have recently reported that CX 3 CL1 strongly
reduces neuronal hippocampal cell death induced by
glutamate (excitotoxicity), and that its neuroprotective
effects are maintained even if the chemokine is
administrated up to 8 hours after the excitotoxic
insult (Limatola et al., 2005). Since there is a large
debate in literature concerning the kind of cells that
express the specific CX 3 CL1 receptor CX3CR1, we
were interested in understanding if CX3CR1 activation
responsible of the neuroprotective effect was of
neuronal or glial origin. At this aim we used mice
engineerized to express the fluorescent protein GFP
in place and under the promoter of the CX3CR1
gene (CX3CR1 GFP/GFP mice) and used hippocampal
neurons obtained from these mice in experiments
of excitotoxic death to analyse the neuroprotective
properties of the medium conditioned by CX3CL1stimulated
wild type microglial cells. In these experiments
we demonstrated that CX3CL1 induce the
release of neurotrophic factor(s) from microglial
cells and identified adenosine as a putative neurotrophic
factor, by HPLC analysis (Lauro et al.,
2007). Since adenosine can activate four different
GPCRs, using subtype-specific receptor antagonists,
we identified adenosine receptor type 1 (AR1) as the
one involved in CX3CL1-mediated neuroprotection.
The involvement of AR1 has been also confirmed
using mice that do not express AR1 (AR1-/-, kindly
provided by Dr. Bertil Fredholm, Stockolm). We are