CNR - Institute of Neuroscience CNR
Institute of Neuroscience
 

Project

Mechanisms of inflammation

Inflammation, a complex reaction due to the activation of the immune system, is aimed to defend the host against foreign invaders and to heal injured self-tissues. When this reaction is excessive, it may be noxious to the host due to a cascade of deleterious events.

Two main stimuli of inflammation, bacteria and cerebral ischemia, are studied in our group.

A first line of research is aimed at defining the physiopathological factors involved in sepsis and studying the role of inflammatory cytokines, oxidative stress and of different immune cell populations (neutrophils, macrophages and Kupffer cells) and their pharmacological modulation. These studies employ the experimental models of endotoxin and cecal ligation and puncture (CLP) (Fig. 1).

 

A second line of research studies the inflammatory mediators and molecular mechanisms of the damage induced by cerebral ischemia, which is among the leading causes of mortality and disability. We have developed two models of focal ischemia (with or without reperfusion) of the middle cerebral artery (MCA), the vessel most commonly affected in stroke syndromes. These models of permanent and transient ischemia in rodents are highly useful approximations of ischemic hemispheral infarction in humans. The model of permanent ischemia produces a fairly predictable cortical lesion (Fig. 2A) while the model of transient ischemia produces cortical and subcortical infarction (Fig. 2B). This model has the main advantage of being more similar to the clinical condition because both the initial ischemia and the secondary reperfusion are critical factors in the final histopathologic and clinical outcome and may yield more clinically relevant information on pathophysiology, neurochemistry and drug efficacy.

 

The model of permanent ischemia has been used to study the short- and long-term neuroprotective and anti-inflammatory effects of systemically administered erythropoietin (EPO), a glycoprotein with a central role in erythropoiesis. Different portions of EPO have been identified to interact with the classical receptor and chemical or mutational modifications of some amino acid residues in some regions of EPO have abolished its binding to the receptor and, therefore, these modified EPO were not erythropoietic but retained potent neuroprotective properties. Consequently we have characterized two distinct receptors of EPO: the EPO receptor homodimer, which is important for hemato-poiesis, and an heterocomplex composed of the EPO receptor and the β common receptor which is involved in tissue- and neuroprotection. At last we have found that the neuroprotective actrivities of EPO can be mimicked by small, nonerythropoieic peptides that simulate a portion of EPO's three-dimensional structure. The relevance of this animal model of cerebral ischemia for human disease is supported by a recent clinical trial which found significant improvement in outcome of stroke patients given EPO intravenously within 8h of the onset of symptoms.

Both models of ischemia have also been used to study the neuroprotective effects of a new inhibitor for the receptors of the inflammatory chemokine interleukin-8 (IL-8), which is implicated in the recruitment of polymorphonuclear neutrophils (PMN). This drug is more effective against transient than permanent ischemia, which is consistent with the hypothesis that PMN are mediators mainly in the reperfusion injury.
However the neuroprotective effect, especially on neurological deficits, in permanent ischemia suggests that additional mechanisms may be involved. Preliminary data with IL-8-receptor KO mice suggest that IL-8 by itself is involved in the damage of permanent cerebral ischemia.
The model of permanent ischemia is currently used to study the mechanisms of the neuroprotective effects of another chemokine, fractalkine.

Publications

  • Brines M, Patel NS, Villa P, Brines C, Mennini T, De Paola M, Erbayraktar Z, Erbayraktar S, Sepodes B, Thiemermann C, Ghezzi P, Yamin M, Hand CC, Xie QW, Coleman T, Cerami A (2008) Nonerythropoietic, tissue-protective peptides derived from the tertiary structure of erythropoietin. Proc. Natl. Acad. Sci. U.S.A. 105:10925-30.
  • Villa P, van Beek J, Larsen AK, Gerwien J, Christensen S, Cerami A, Brines M, Leist M, Ghezzi P, Torup L (2007) Reduced functional deficits, neuroinflammation, and secondary tissue damage after treatment of stroke by nonerythropoietic erythropoietin derivatives. J. Cereb. Blood Flow Metab. 27:552-63.
  • Garau A, Bertini R, Colotta F, Casilli F, Bigini P, Cagnotto A, Mennini T, Ghezzi P, Villa P (2005) Neuroprotection with the CXCL8 inhibitor repertaxin in transient brain ischemia. Cytokine 30:125-31.
  • Leist M, Ghezzi P, Grasso G, Bianchi R, Villa P, Fratelli M, Savino C, Bianchi M, Nielsen J, Gerwien J, Kallunki P, Larsen AK, Helboe L, Christensen S, Pedersen LO, Nielsen M, Torup L, Sager T, Sfacteria A, Erbayraktar S, Erbayraktar Z, Gokmen N, Yilmaz O, Cerami-Hand C, Xie QW, Coleman T, Cerami A, Brines M (2004) Derivatives of erythropoietin that are tissue protective but not erythropoietic. Science 305:239-42.
  • Villa P, Bigini P, Mennini T, Agnello D, Laragione T, Cagnotto A, Viviani B, Marinovich M, Cerami A, Coleman TR, Brines M, Ghezzi P (2003) Erythropoietin selectively attenuates cytokine production and inflammation in cerebral ischemia by targeting neuronal apoptosis. J. Exp. Med. 198:971-5.

Collaborations

  • L. Torup, Lundbeck, Valby-Copenhagen, Denmark.
  • R. Bertini, Dompè, L'Aquila.
  • M. Brines, The Kenneth S. Warren Institute, Ossining, NY, USA.
  • A. Valerio, Department of Biomedical Sciences and Biotechnologies, University of Brescia, Brescia.
  • C. Limatola, Department of Human Physiology and Pharmacology, University of Rome "La Sapienza", Rome.

 

PI photo

Pia Villa

Contact information

email  E-mail

email  +39 02 3901 4492

Participating staff
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