Marcello Allegretti

Repertaxin, a novel inhibitor of rat CXCR2 function, inhibits inflammatory responses that follow intestinal ischaemia and reperfusion injury

Neutrophils are thought to play a major role in the mediation of reperfusion injury. CXC chemokines are known inducers of neutrophil recruitment. Here, we assessed the effects of Repertaxin, a novel low molecular weight inhibitor of human CXCL8 receptor activation, on the local, remote and systemic injuries following intestinal ischaemia and reperfusion (I/R) in the rat. Pre‐incubation of rat neutrophils with Repertaxin (10−11–10−6M) inhibited the chemotaxis of neutrophils induced by human CXCL8 or rat CINC‐1, but not that induced by fMLP, PAF or LTB4, in a concentration‐dependent manner. Repertaxin also prevented CXCL8‐induced calcium influx but not CXCL8 binding to purified rat neutrophils. In a model of mild I/R injury (30 min of ischaemia and 30 min of reperfusion), Repertaxin dose‐dependently (3–30 mg kg−1) inhibited the increase in vascular permeability and neutrophil influx. Maximal inhibition occurred at 30 mg kg−1. Following severe I/R injury (120 min of ischaemia and 120 min of reperfusion), Repertaxin (30 mg kg−1) markedly prevented neutrophil influx, the increase in vascular permeability both in the intestine and the lungs. Moreover, there was prevention of haemorrhage in the intestine of reperfused animals. Repertaxin effectively suppressed the increase in tissue (intestine and lungs) and serum concentrations of TNF‐α and the reperfusion‐associated lethality. For comparison, we also evaluated the effects of an anti‐CINC‐1 antibody in the model of severe I/R injury. Overall, the antibody effectively prevented tissue injury, systemic inflammation and lethality. However, the effects of the antibody were in general of lower magnitude than those of Repertaxin. In conclusion, CINC‐1 and possibly other CXC chemokines, acting on CXCR2, have an important role during I/R injury. Thus, drugs, such as Repertaxin, developed to block the function of the CXCR2 receptor may be effective at preventing reperfusion injury in relevant clinical situations.

Targeting C5a: Recent Advances in Drug Discovery

Activation of complement via the innate and adaptive immune system is vital to the bodys defences in fighting infections. Unregulated complement activation is likely to play a crucial role in the pathogenesis of several diseases including psoriasis, adult (acute) respiratory distress syndrome (ARDS), bullous pemphigoid (BP), rheumatoid arthritis (RA) and ischemia-reperfusion (I/R) injury. The 74 amino acid peptide C5a is released after complement activation at sites of inflammation and is a potent chemoattractant for neutrophils, basophils, eosinophils, leukocytes, monocytes and macrophages. Recombinant proteins and humanized anti-C5 antibodies have been recently developed for blocking specific proteins of the complement system bringing renewed attention towards complement inhibition. Pharmacological studies have been highlighting the complement fragment C5a as an interesting target for the management of complement mediated diseases. Specific inhibition of C5a biological activity could gain therapeutic benefit without affecting the protective immune response. In the last few years several peptide and non-peptide antagonists of C5a have been discovered and tested in relevant pharmacological models; the availability of orally active compounds is rapidly helping to delineate the precise role of C5a in immunoinflammatory disorders. Moreover, mutagenesis data for the C5a/C5a receptor (C5aR) couple make C5aR a valuable model for mechanistic studies of peptidergic G-protein coupled receptors (GPCRs). The aim of this review is to outline the recent advances in C5a inhibition, especially highlighting the value of a multidisciplinary integrated approach in drug discovery.

Blockade of the chemokine receptor CXCR2 ameliorates adjuvant-induced arthritis in rats

Chemokine receptors CXCR1 and CXCR2 may mediate influx of neutrophils in models of acute and chronic inflammation. The potential benefits of oral administration of a CXCR1/2 inhibitor, DF 2162, in adjuvant‐induced polyarthritis (AIA) were investigated.

One-pot, new stereoselective synthesis of endo-tropanamine

Abstract A palladium-catalysed reduction of ketones to primary amines by reaction with ammonium formate in aqueous methanol is described. The proposed method provides a one-pot synthesis of 3- endo -tropanamine in high yields and stereoselectivity.

Targeting the minor pocket of C5aR for the rational design of an oral allosteric inhibitor for inflammatory and neuropathic pain relief

Significance Persistent pain in inflammatory and neuropathic conditions is often refractory to conventional analgesic therapy, with most patients suffering with unrelieved pain and serious treatment-related side effects. There is still a tremendous need to identify novel therapeutics for pain control with innovative biological mechanisms and minimal side effects. In this paper we challenge the hypothesis that a conserved structural motif across the G protein-coupled receptor family plays a regulatory role in the negative modulation of receptor activation and use a multidisciplinary approach to the rational drug design and characterization of a novel potent allosteric inhibitor of the C5a anaphylatoxin receptor (C5aR), thus providing a new promising avenue for the improvement of pharmacotherapy of chronic pain. Chronic pain resulting from inflammatory and neuropathic disorders causes considerable economic and social burden. Pharmacological therapies currently available for certain types of pain are only partially effective and may cause severe adverse side effects. The C5a anaphylatoxin acting on its cognate G protein-coupled receptor (GPCR), C5aR, is a potent pronociceptive mediator in several models of inflammatory and neuropathic pain. Although there has long been interest in the identification of C5aR inhibitors, their development has been complicated, as for many peptidomimetic drugs, mostly by poor drug-like properties. Herein, we report the de novo design of a potent and selective C5aR noncompetitive allosteric inhibitor, DF2593A, guided by the hypothesis that an allosteric site, the “minor pocket,” previously characterized in CXC chemokine receptors-1 and -2, is functionally conserved in the GPCR class. In vitro, DF2593A potently inhibited C5a-induced migration of human and rodent neutrophils. In vivo, oral administration of DF2593A effectively reduced mechanical hyperalgesia in several models of acute and chronic inflammatory and neuropathic pain, without any apparent side effects. Mechanical hyperalgesia after spared nerve injury was also reduced in C5aR−/− mice compared with WT mice. Furthermore, treatment of C5aR−/− mice with DF2593A did not produce any further antinociceptive effect compared with C5aR−/− mice treated with vehicle. The successful medicinal chemistry strategy confirms that a conserved minor pocket is amenable for the rational design of selective inhibitors and the pharmacological results support that the allosteric blockade of the C5aR represents a highly promising therapeutic approach to control chronic inflammatory and neuropathic pain.

DF2755A, a novel non-competitive allosteric inhibitor of CXCR1/2, reduces inflammatory and post-operative pain

The activation of CXCR1/2 has been implicated in the genesis of inflammatory and postoperative pain. Here, we investigated a novel orally acting allosteric inhibitor of CXCR1/2 (DF2755A) and evaluated its antinociceptive effect in several models of inflammatory and post-operatory pain. DF2755A was tested in vitro for efficacy in the chemotaxis assay, selectivity and toxicity. In vivo, C57Bl/6 mice were treated orally with DF2755A and the following experiments were performed: pharmacokinetic profile; inflammatory hyperalgesia models using electronic pressure meter test; neutrophil migration assay assessed by myeloperoxidase assay. DF2755A selectively inhibited neutrophil chemotaxis induced by CXCR1/2 ligands without effect on CXCL8 binding to neutrophils. A single mutation of the allosteric site at CXCR1 abrogated the inhibitory effect of DF2755A on CXCL8-induced chemotaxis. DF2755A given orally was well absorbed (88.2%), and it was able to reduce, in a dose (3-30mg/kg)-dependent manner, inflammatory hyperalgesia induced by carrageenan, LPS and CXCL1/KC as well as neutrophil recruitment and IL-1β production. In addition, DF2755A was able to reduce post-incisional nociception. Therapeutic treatment with DF2755A reduced CFA-induced inflammatory hyperalgesia even when injected intrathecally. The present results indicate that DF2755A is a novel selective allosteric inhibitor of CXCR1/2 with a favorable oral pharmacokinetic profile. Furthermore, the results might suggest that DF2755A might be a candidate of a novel therapeutic option to control inflammatory and post-operative pain.

DFL23448, A Novel Transient Receptor Potential Melastin 8–Selective Ion Channel Antagonist, Modifies Bladder Function and Reduces Bladder Overactivity in Awake Rats

The transient receptor potential melastin 8 ion channel (TRPM8) is implicated in bladder sensing but limited information on TRPM8 antagonists in bladder overactivity is available. This study characterizes a new TRPM8-selective antagonist (DFL23448 [5-(2-ethyl-2H-tetrazol-5-yl)-2-(3-fluorophenyl)-1,3-thiazol-4-ol]) and evaluates it in cold-induced behavioral tests and tests on bladder function and experimental bladder overactivity in vivo in rats. DFL23448 displayed IC50 values of 10 and 21 nM in hTRPM8 human embryonic kidney 293 cells activated by Cooling Agent 10 or cold, but it had limited activity (IC50 > 10 μM) at transient receptor potential vanilloids TRPV1, TRPA1, or TRPV4 or at various G protein–coupled receptors. In rats, DFL23448 administered intravenously or orally had a half-life of 37 minutes or 4.9 hours, respectively. DLF23448 (10 mg/kg i.v.) reduced icilin-induced “wet dog–like” shakes in rats. Intravesical DFL23448 (10 mg/l), but not vehicle, increased micturition intervals, micturition volume, and bladder capacity. During bladder overactivity by intravesical prostaglandin E2 (PGE2), vehicle controls exhibited reductions in micturition intervals, micturition volumes, and bladder capacity by 37%–39%, whereas the same parameters only decreased by 12%–15% (P < 0.05–0.01 versus vehicle) in DFL23448-treated rats. In vehicle-treated rats, but not in DFL23448-treated rats, intravesical PGE2 increased bladder pressures. Intravenous DFL23448 at 10 mg/kg, but not 1 mg/kg DFL23448 or vehicle, increased micturition intervals, micturition volumes, and bladder capacity. During bladder overactivity by intravesical PGE2, micturition intervals, micturition volumes, and bladder capacity decreased in vehicle– and 1 mg/kg DFL23448–treated rats, but not in 10 mg/kg DFL23448–treated rats. Bladder pressures increased less in rats treated with DFL23448 10 mg/kg than in vehicle– or 1 mg/kg DFL23448–treated rats. DFL23448 (10 mg/kg i.v.), but not vehicle, prevented cold stress–induced bladder overactivity. Our results support a role for bladder TRPM8-mediated signals in experimental bladder overactivity.

Antinociceptive effect of two novel transient receptor potential melastatin 8 antagonists in acute and chronic pain models in rat

Transient receptor potential (TRP) channels are a superfamily of non‐selective cation permeable channels involved in peripheral sensory signalling. Animal studies have shown that several TRPs are important players in pain modulation. Among them, the TRP melastatin 8 (TRPM8) has elicited more interest for its controversial role in nociception. This channel, expressed by a subpopulation of sensory neurons in dorsal root ganglia (DRG) and trigeminal ganglia (TG), is activated by cold temperatures and cooling agents. In experimental neuropathic pain models, an up‐regulation of this receptor in DRG and TG has been observed, suggesting a key role for TRPM8 in the development and maintenance of pain. Consistent with this hypothesis, TRPM8 knockout mice are less responsive to pain stimuli.

Set up and optimization of a fermentation protocol for the production of a human antibody fragment (Fab') express in E. coli. Pre-pilot and cGMP pilot scale studies

can be the ther-apeutic of choice for solid tumors due to shorter circulat-ing half life and a higher tumor penetration, bothcharacteristics well suited in a radio immunotherapy(RIT) approach.Ovarian cancer is the leading cause of death among gyne-cological tumors. Standard first line therapy consists ofsurgery followed by chemotherapy cycles. About 90% ofpatients relapse with a 5-year survival rate of 5–20% [1].So far, second line chemotherapy after clinical relapse hasshown limited efficacy. With the advancement of therecombinant biotechnology, a novel approach based onhuman monoclonal antibody immunotherapy has beganto be investigated. The alfa folate receptor ( αFR), which isa 38000 Dalton anchored membrane protein, is overexpressed in more than 90% of ovarian carcinoma cells,and in 60% of other gynecological carcinomas [2]. In con-trast to normal epithelial cells, ovarian carcinoma cellsexpress this receptor on their external surface making itaccessible for binding to monoclonal antibodies.The basic concept of our project is to produce a fullhuman F(ab)