RICERCA ITALIANA     

ANTAGONISTS OF Bv8-PROKINETICIN RECEPTORS: MOLECULAR MODELS FOR THE DEVELOPMENT OF NEW ANALGESIC, ANTI-INFLAMMATORY, IMMUNOMODULATOR DRUGS

Università degli Studi di Roma "La Sapienza"

Abstract

We will synthesize a new family of non-peptide prokineticin receptor (PKR) antagonists to extend our knowledge on the functional role of prokineticins and their receptors in nociception, inflammation and immunity and provide molecular models for the development of new drugs that targeting the PK system can have a role in the therapeutic control of pathological states characterized by pain and strong immune components such as chronic inflammatory and autoimmune diseases.
Synthesized antagonists will be derivatives of triazine and pyrimidine scaffolds and endowed with high affinity, selectivity and antagonist potency at PKRs. These molecules together with the peptide antagonist [Ala 24]Bv8 will be used in the following experimental approaches:
1. To evaluate the functional role of endogenous prokineticin system in acute nociception and in animal models of chronic pain.
2. To define the role of PK system in the brain descending control of pain sensation.
3. To elucidate the functional role of PKRs expressed by immune cells.
4. To study anti-hyperalgesic and anti-inflammatory activities of PKR antagonists in mice and rats bearing inflammatory and neuropathic lesions.
5. To study the immunomodulatory activity of PKR antagonists in animal immuno responses and models of experimental autoimmune diseases.
According to the approaches 1 and 4 , the role of each PKR in nociception in absence of compensatory activities by endogenous opioid >>>

Principal Investigator

Lucia Negri Università degli Studi di ROMA "La Sapienza"

Research Objectives

Prokineticins and their receptors, PK-R1 and PK-R2, represent a recently identified endogenous protein system involved in nociception, inflammation and autoimmunity. Prokineticin and their receptors hint at novel strategies for analgesic, antiinflammatory and immunomodulator drug development.
The proposed program will investigate the antinociceptive, anti-inflammatory and immunomodulator properties of antagonists of the prokineticin receptors PKR-1 and PKR-2.
The final objectives of this project are
1. To synthesize new compounds containing triazine- and pirimidine- derived scaffolds that preliminary studies indicated to be valuable models for the development of non-peptide PKR antagonists.
2. To evaluate receptor affinity and selectivity and PKR antagonist properties of the synthesized non-peptide compounds in comparison with the previously described peptide antagonist [24Ala]Bv8.
3. To localize PKR receptor proteins by in situ binding of labelled PKR antagonists in dorsal root ganglia, central nervous system, bone marrow, lymphoid organs, blood cells and inflammatory immune cells.
4. To use the synthesized PKR antagonists to elucidate the role of endogenous prokineticins and prokineticin receptors in the central and peripheral modulation of pain sensation, in immune responses and in cytokine production by glial cells and infiltrating and resident immune cells.
5. To evaluate the analgesic, anti-inflammatory and >>>

First Results

Project results will extend our knowledge on the functional role of prokineticins and their receptors in nociception, inflammation and immunity and provide molecular models of prokineticin receptor antagonists for the development of new drugs that targeting the PK system can have a role in the therapeutic control of pathological states characterized by pain and strong immune components such as chronic inflammatory and autoimmune diseases.
Although available data on the functional role of PKRs and PK2 in pain sensation are robust, they all concern with impaired nociceptive responses in mice lacking PK-R1 or PK-R2 or PK2 genes. There are many limitations to extrapolate these results to intact animals. Embryonic deletion of a gene may lead to compensatory expression of other genes during embryonic and post-natal life. There are many examples of functional deficiencies observed in receptor-ko mice that are not replicated in intact mice by quenching the receptor activity with a receptor antagonist. Additionally, knockout of both PKR genes in the same mouse is not yet available and, therefore, it is difficult to evaluate PK receptor participation to many nociceptive responses. Finally, owing to many CNS and peripheral defects in PK-R2-KO mice, the nociceptive role of PK-R2 receptor could not be clearly defined by gene deletion.
Another broad limitation to extrapolate the results obtained in PKR-KO mice to chronic pain syndromes is that available data on PKR-KO are >>>

Timescale

24 months

National and international background

Many serious inflammatory and immune diseases are often associated with unrelieved pain. Despite major advances in the understanding of the molecular mechanisms involved in these painful chronic diseases and considerable investment in pharmaceutical research and development in this field, there are few innovative drugs, all of which have safety issues. The multiple mediators of pain and inflammation are products of injury-induced gene expression that lead to plastic changes in the nervous system and immune responses. Valuable targets for drug development may be found among molecules over-expressed in pain-related inflammatory diseases and endowed with the ability of reproducing nociceptive sensitization and modulating immune responses in experimental animals. Recently we have identified novel molecular entities which can lower pain threshold and modulate immune responses in laboratory animals and are over-expressed in inflammatory diseases and tumors (Negri et al., 2007). These molecules are small proteins named Bv8-prokineticins (PKs) that activate G-protein linked PKR receptors (PK-R1 and PK-R2) in the central nervous system, dorsal root ganglia and in cells participating to immuno and inflammatory responses.
PKs are small secreted proteins (8-11 kD) (Mollay et al., 1999; Wechselberger, et al., 1999; LeCouter et al. 2001; Li et al., 2001 ) that lower the nociceptor threshold to a broad spectrum of physical and chemical noxious stimuli (Negri et al. 2002). In primary >>>