Inhibition of C5aR1 as a promising approach to treat taxane-induced neuropathy.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of several antitumor agents resulting in progressive and often irreversible damage of peripheral nerves. In addition to their known anticancer effects, taxanes, including paclitaxel, can also induce peripheral neuropathy by activating microglia and astrocytes, which release pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin 1-beta (IL-1ß), and chemokine (C-C motif) ligand 2 (CCL-2). All these events contribute to the maintenance of neuropathic or inflammatory response. Complement component 5a (C5a)/C5a receptor 1 (C5aR1) signaling was very recently shown to play a crucial role in paclitaxel-induced peripheral neuropathy. Our recent findings highlighted that taxanes have the previously unreported property of binding and activating C5aR1, and that C5aR1 inhibition by DF3966A is effective in preventing paclitaxel-induced peripheral neuropathy (PIPN) in animal models. Here, we investigated if C5aR1 inhibition maintains efficacy in reducing PIPN in a therapeutic setting. Furthermore, we characterized the role of C5aR1 activation by paclitaxel and the CIPN-associated activation of nod-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome. Our results clearly show that administration of the C5aR1 inhibitor strongly reduced cold and mechanical allodynia in mice when given both during the onset of PIPN and when neuropathy is well established. C5aR1 activation by paclitaxel was found to be a key event in the induction of inflammatory factors in spinal cord, such as TNF-α, ionized calcium-binding adapter molecule 1 (Iba-1), and glial fibrillary acidic protein (GFAP). In addition, C5aR1 inhibition significantly mitigated paclitaxel-induced inflammation and inflammasome activation by reducing IL-1ß and NLRP3 expression at both sciatic and dorsal root ganglia level, confirming the involvement of inflammasome in PIPN. Moreover, paclitaxel-induced upregulation of C5aR1 was significantly reduced by DF3966A treatment in central nervous system. Lastly, the antinociceptive effect of C5aR1 inhibition was confirmed in an in vitro model of sensory neurons in which we focused on receptor channels usually activated upon neuropathy. In conclusion, C5aR1 inhibition is proposed as a therapeutic option with the potential to exert long-term protective effect on PIPN-associated neuropathic pain and inflammation.

Conformational Change in the Mechanism of Inclusion of Ketoprofen in ß-Cyclodextrin: NMR Spectroscopy, Ab Initio Calculations, Molecular Dynamics Simulations, and Photoreactivity.

Inclusion of drugs in cyclodextrins (CDs) is a recognized tool for modifying several properties such as solubility, stability, bioavailability, and so on. The photoreactive behavior of the ß-CD/ketoprofen (KP) complex upon UV exposure showed a significant increase in photodecarboxylation, whereas the secondary degradation products by hydroxylation of the benzophenone moiety were inhibited. The results may account for an improvement of KP photophysical properties upon inclusion, thus better fostering its topical use. To correlate the structural details of the inclusion with these results, an NMR spectroscopic study of KP upon inclusion in ß-CD was performed. Effects of the magnetically anisotropic centers of KP, changing their orientations upon inclusion and giving chemical shift variations, were specifically correlated with the results of the molecular dynamic simulations and ab initio calculations. In the large variety of papers focusing on the structural analysis of ß-CD complexes, this work represents one of the few examples in which a detailed analysis of these simultaneous upfield-downfield NMR shifts of the same aromatic molecule upon inclusion is reported. Interestingly, the results demonstrate that the observed upfield and downfield shifts upon inclusion are not related to any direct magnetic role of ß-CD. The conformational change of KP upon the inclusion process consists of a slight reduction in the angle between the two phenyl rings and in a remarkable reduction in the mobility of the carboxyl group, the latter being one of the main contributions to the NMR resonance shifts. These structural details help in understanding the features of the inclusion complex and, eventually, the driving force for its formation.

Receptor binding mode and pharmacological characterization of a potent and selective dual CXCR1/CXCR2 non-competitive allosteric inhibitor.

BACKGROUND AND PURPOSE: DF 2156A is a new dual inhibitor of IL-8 receptors CXCR1 and CXCR2 with an optimal pharmacokinetic profile. We characterized its binding mode, molecular mechanism of action and selectivity, and evaluated its therapeutic potential. EXPERIMENTAL APPROACH: The binding mode, molecular mechanism of action and selectivity were investigated using chemotaxis of L1.2 transfectants and human leucocytes, in addition to radioligand and [(35) S]-GTPγS binding approaches. The therapeutic potential of DF 2156A was evaluated in acute (liver ischaemia and reperfusion) and chronic (sponge-induced angiogenesis) experimental models of inflammation. KEY RESULTS: A network of polar interactions stabilized by a direct ionic bond between DF 2156A and Lys(99) on CXCR1 and the non-conserved residue Asp(293) on CXCR2 are the key determinants of DF 2156A binding. DF 2156A acted as a non-competitive allosteric inhibitor blocking the signal transduction leading to chemotaxis without altering the binding affinity of natural ligands. DF 2156A effectively and selectively inhibited CXCR1/CXCR2-mediated chemotaxis of L1.2 transfectants and leucocytes. In a murine model of sponge-induced angiogenesis, DF 2156A reduced leucocyte influx, TNF-α production and neovessel formation. In vitro, DF 2156A prevented proliferation, migration and capillary-like organization of HUVECs in response to human IL-8. In a rat model of liver ischaemia and reperfusion (I/R) injury, DF 2156A decreased PMN and monocyte-macrophage infiltration and associated hepatocellular injury. CONCLUSION AND IMPLICATIONS: DF 2156A is a non-competitive allosteric inhibitor of both IL-8 receptors CXCR1 and CXCR2. It prevented experimental angiogenesis and hepatic I/R injury in vivo and, therefore, has therapeutic potential for acute and chronic inflammatory diseases.

Therapeutic inhibition of CXCR2 by Reparixin attenuates acute lung injury in mice.

BACKGROUND AND PURPOSE: Acute lung injury (ALI) remains a major challenge in critical care medicine. Both neutrophils and chemokines have been proposed as key components in the development of ALI. The main chemokine receptor on neutrophils is CXCR2, which regulates neutrophil recruitment and vascular permeability, but no small molecule CXCR2 inhibitor has been demonstrated to be effective in ALI or animal models of ALI. To investigate the functional relevance of the CXCR2 inhibitor Reparixin in vivo, we determined its effects in two models of ALI, induced by either lipopolysaccharide (LPS) inhalation or acid instillation. EXPERIMENTAL APPROACH: In two ALI models in mice, we measured vascular permeability by Evans blue and evaluated neutrophil recruitment into the lung vasculature, interstitium and airspace by flow cytometry. KEY RESULTS: Pharmacological inhibition of CXCR2 by Reparixin reduced CXCL1-induced leukocyte arrest in the microcirculation of the cremaster muscle, but did not influence arrest in response to leukotriene B4 (LTB4) demonstrating specificity. Reparixin (15 microg g(-1)) reduced neutrophil recruitment in the lung by approximately 50% in a model of LPS-induced ALI. A higher dose did not provide additional reduction of neutrophil recruitment. This dose also reduced accumulation of neutrophils in the interstitial compartment and vascular permeability in LPS-induced ALI. Furthermore, both prophylactic and therapeutic application of Reparixin improved gas exchange, and reduced neutrophil recruitment and vascular permeability in a clinically relevant model of acid-induced ALI. CONCLUSIONS AND IMPLICATIONS: Reparixin, a non-competitive allosteric CXCR2 inhibitor attenuates ALI by reducing neutrophil recruitment and vascular permeability.

Treatment with DF 2162, a non-competitive allosteric inhibitor of CXCR1/2, diminishes neutrophil influx and inflammatory hypernociception in mice.

BACKGROUND AND PURPOSE: Neutrophil migration into tissues is involved in the genesis of inflammatory pain. Here, we addressed the hypothesis that the effect of CXC chemokines on CXCR1/2 is important to induce neutrophil migration and inflammatory hypernociception. EXPERIMENTAL APPROACH: Mice were treated with a non-competitive allosteric inhibitor of CXCR1/2, DF 2162, and neutrophil influx and inflammatory hypernociception were assessed by myeloperoxidase assay and electronic pressure meter test, respectively, in various models of inflammation. KEY RESULTS: DF 2162 inhibited neutrophil chemotaxis induced by CXCR1/2 ligands but had no effect on CXCL8 binding to neutrophils. A single mutation of the allosteric site at CXCR1 abrogated the inhibitory effect of DF 2162 on CXCL-8-induced chemotaxis. Treatment with DF 2162 prevented influx of neutrophils and inflammatory hypernociception induced by CXCL1 in a dose-dependent manner. The compound inhibited neutrophil influx and inflammatory hypernociception induced by carrageenan, lipopolysaccharide and zymosan, but not hypernociception induced by dopamine and PGE(2). DF 2162 had a synergistic effect with indomethacin or the absence of TNFR1 to abrogate carrageenan-induced hypernociception. Treatment with DF 2162 diminished neutrophil influx, oedema formation, disease score and hypernociception in collagen-induced arthritis. CONCLUSIONS AND IMPLICATIONS: CXCR1/2 mediates neutrophil migration and is involved in the cascade of events leading to inflammatory hypernociception. In addition to modifying fundamental pathological processes, non-competitive allosteric inhibitors of CXCR1/2 may have the additional benefit of providing partial relief for pain and, hence, may be a valid therapeutic target for further studies aimed at the development of new drugs for the treatment of rheumatoid arthritis.

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

BACKGROUND AND PURPOSE: 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. EXPERIMENTAL APPROACH: A model of AIA in rats was used to compare the therapeutic effects of the treatment with DF2162, anti-TNF or anti-CINC-1 antibodies on joint inflammation and local production of cytokines and chemokines. KEY RESULTS: DF2162 prevented chemotaxis of rat and human neutrophils induced by chemokines acting on CXCR1/2. DF2162 was orally bioavailable and metabolized to two major metabolites. Only metabolite 1 retained CXCR1/2 blocking activity. Treatment with DF2162 (15 mg kg(-1), twice daily) or metabolite 1, but not metabolite 2, starting on day 10 after arthritis induction diminished histological score, the increase in paw volume, neutrophil influx and local production of TNF, IL-1beta, CCL2 and CCL5. The effects of DF2162 were similar to those of anti-TNF, and more effective than those of anti-CINC-1, antibodies. DF2162 prevented disease progression even when started 13 days after arthritis induction. CONCLUSIONS AND IMPLICATIONS: DF 2162, a novel orally-active non-competitive allosteric inhibitor of CXCR1 and CXCR2, significantly ameliorates AIA in rats, an effect quantitatively and qualitatively similar to those of anti-TNF antibody treatment. These findings highlight the contribution of CXCR2 in the pathophysiology of AIA and suggest that blockade of CXCR1/2 may be a valid therapeutic target for further studies aiming at the development of new drugs for treatment of rheumatoid arthritis.

Targeting C5a: recent advances in drug discovery.

Activation of complement via the innate and adaptive immune system is vital to the body's 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.

R- and S-isomers of nonsteroidal anti-inflammatory drugs differentially regulate cytokine production.

2-arylpropionic acids, a well known class of non-steroidal anti-inflammatory drugs (NSAIDs), exist as a racemic mixture of their enantiomeric forms, with S-isomers primarily responsible for inhibition of prostaglandin (PG) production and of inflammatory events. In this study we show that S-isomers are also responsible for the paradoxical up-regulation of tumor necrosis factor (TNF) induced by ketoprofen, flurbiprofen and ibuprofen in murine peritoneal macrophages stimulated by bacterial endotoxin (LPS). This effect is in close correlation with cyclooxygenase inhibitory capacity of S-isomers and, from Northern blot analysis, seems to be mediated by the up-regulation of TNF mRNA. In addition, up-regulation of TNF production by S-isomers is associated with inhibition of interleukin-10 (IL-10) production. Conversely, we have observed that S-enantiomers reduce IL-6 production at a concentration 100 times higher than that able to inhibit cyclooxygenase activity. The unwanted pro-inflammatory effects of S-isomers through TNF and IL-10 production could therefore hinder their analgesic effect, that is, at least in part, related to IL-6 inhibition. In addition, TNF amplification by S-isomers could be correlated to the clinical evidence of their gastric toxicity. On the other hand, R-isomers did not affect TNF and IL-10 production even at cyclooxygenase-blocking concentration, while they reduced IL-6 production to the same levels as S-isomers. It is concluded that the regulation of cytokine production by S-isomers of 2-arylpropionic acids could partially mask their therapeutic effects and could be correlated to the clinical evidence of their higher gastric toxicity. On the other hand, IL-6 inhibition without the unwanted effects on TNF and IL-10 production shown by R-isomers could be correlated to the analgesic effect reported for R-2-arylpropionic acids.

Synthesis, inhibitory activity towards human leukocyte elastase and molecular modelling studies of 1-carbamoyl-4-methyleneaminoxyazetidinones.

Some monocyclic beta-lactam derivatives of type 3 (MAOAs) in which the leaving group (LG) on the C(4) is a methyleneaminoxy moiety, were synthesised and tested in vitro and in vivo for their inhibitory activity towards human leukocyte elastase (HLE). Some compounds showed an appreciable in vitro inhibitory activity against this enzyme. Effects on the anti-HLE activity due to the nature of the substituents R and R(1) present on their LG were observed and rationalised by means of molecular modelling techniques. The results of in vivo pharmacological tests indicated that MAOAs, while showing an inhibitory activity on the haemorrhage induced by HLE, did not exhibit any effects due to the R and R(1) substituents.

[Methods and applications in the control of hypersensitivity in exposed occupational populations]. / Metodi ed applicazioni nel controllo di reazioni da ipersensibilità in popolazioni di lavoratori esposti.

The aim of this work is to present a clinical questionnaire for epidemiological studies in occupational allergology. We have evaluated and tested the items of such a questionnaire, finding a good sensitivity and specificity in terms of identification of symptoms and a clinical approach to the patient. The questionnaire was blind tested by two specialists and their results were found to be concordant. We realized that such a questionnaire is an easy instrument to use for medical personnel, reproducible and reliable. It can be applied in well orientated studies of occupational medicine as a first step in the investigation of work-related symptoms and in monitoring the workplace.

Tartronates: a new generation of drugs affecting bone metabolism.

In the search for a new class of bone-sparing agents for treating osteopenic disorders, we hypothesized that tartronic acid derivatives, sharing the chemical characteristics both of bisphosphonates and of Gla residues contained in matrix proteins such as osteocalcin, could positively affect bone metabolism. A series of tartronates was therefore tested for their ability to affect bone metabolism. In vitro resorption tests were performed examining pit formation by freshly isolated rat and rabbit osteoclasts plated onto bone slices and exposed to the drugs for 48 h. Tartronates bearing a linear side-chain (DF 1222 and DF 1363A) were the most effective in inhibiting pit excavation in the pM-nM range. Tartronates did not affect osteoclast viability, number, adhesion, or tartrate resistant acid phosphatase activity. Transient cell retraction was observed in osteoclasts plated onto glass and exposed to DF 1222. The maximal effect was seen in cells treated for 4 h at a concentration of 1 pM. DF 1222 accelerated mineralization in cultures of periosteal cells without affecting other osteoblast-like functions. This product was therefore tested in vivo in ovariectomized mice. Bone mass in femur was evaluated, by ash gravimetry, 21 days after ovariectomy. Unfortunately, DF 1222, the most active of tartronates in vitro, was inactive in this test because of its high hydrophilicity and the subsequent too short residence time. On the contrary, its tetrahydropyranyl ether derivative, DF 1363A, endowed with a significantly higher lipophilicity, showed a dose-dependent bone-sparing effect when administered subcutaneously at 10, 30, and 100 mg/kg/die, thus confirming the activity seen in in vitro tests. Because of their feasible parallel effect on both bone resorption and formation, tartronate derivatives may be tested to candidate this class of products for clinical studies.

[The dexamethasone test and the choice of treatment and drug in depression]. / Il test al desametazone e la scelta del trattamento e del farmaco nella depressione.

A large body of literature data have indicated that the dexamethasone suppression test (DST) may be useful in diagnosing depression. It has been also hypothesized that depressed patients showing an abnormal response to dexamethasone administration ("DST-non suppressors") are responsive to the treatment with psychopharmacological agents whereas the "DST-suppressors" subjects are often "placebo-responders". Moreover, on the basis of considerations concerning the inhibitory role of noradrenaline in the control of both the activity of the hypothalamic-pituitary-adrenal axis and mood, it has been claimed that the "DST-non suppressors" subjects respond to the treatment with antidepressant drugs potentiating the noradrenergic activity at level of the central nervous system. The present review of the main data on the topic leads to conclude that the DST may be useful in selecting the most appropriate treatment for depressed patients; the test, however, does not make it possible to choose the antidepressant drug on the basis of its neurochemical profile.

[The Italian experience in the control of rabies. I. Procedural methods]. / L'esperienza italiana nel controllo della rabbia. I. Lavoro operativo.

Oral vaccination of foxes associated with their control has been shown to be a rapid and safe method to extinguish enzootic foci of sylvatic rabies and to prevent the entry and spreading of this zoonosis in free zones of Italy. Domestic animals vaccination with live modified vaccines in zones with sylvatic rabies has proved to be highly effective in limiting the cases, recorded only in non-vaccinated animals.