C-X-C Motif Chemokine Receptor 4 Blockade Promotes Tissue Repair After Myocardial Infarction by Enhancing Regulatory T Cell Mobilization and Immune-Regulatory Function.

BACKGROUND: Acute myocardial infarction (MI) elicits an inflammatory response that drives tissue repair and adverse cardiac remodeling. Inflammatory cell trafficking after MI is controlled by C-X-C motif chemokine ligand 12 (CXCL12) and its receptor, C-X-C motif chemokine receptor 4 (CXCR4). CXCR4 antagonists mobilize inflammatory cells and promote infarct repair, but the cellular mechanisms are unclear. METHODS: We investigated the therapeutic potential and mode of action of the peptidic macrocycle CXCR4 antagonist POL5551 in mice with reperfused MI. We applied cell depletion and adoptive transfer strategies using lymphocyte-deficient Rag1 knockout mice; DEREG mice, which express a diphtheria toxin receptor-enhanced green fluorescent protein fusion protein under the control of the promoter/enhancer region of the regulatory T (Treg) cell-restricted Foxp3 transcription factor; and dendritic cell-depleted CD11c-Cre iDTR mice. Translational potential was explored in a porcine model of reperfused MI using serial contrast-enhanced magnetic resonance imaging. RESULTS: Intraperitoneal POL5551 injections in wild-type mice (8 mg/kg at 2, 4, 6, and 8 days) enhanced angiogenesis in the infarct border zone, reduced scar size, and attenuated left ventricular remodeling and contractile dysfunction at 28 days. Treatment effects were absent in splenectomized wild-type mice, Rag1 knockout mice, and Treg cell-depleted DEREG mice. Conversely, treatment effects could be transferred into infarcted splenectomized wild-type mice by transplanting splenic Treg cells from POL5551-treated infarcted DEREG mice. Instructive cues provided by infarct-primed dendritic cells were required for POL5551 treatment effects. POL5551 injections mobilized Treg cells into the peripheral blood, followed by enhanced Treg cell accumulation in the infarcted region. Neutrophils, monocytes, and lymphocytes displayed similar mobilization kinetics, but their cardiac recruitment was not affected. POL5551, however, attenuated inflammatory gene expression in monocytes and macrophages in the infarcted region via Treg cells. Intravenous infusion of the clinical-stage POL5551 analogue POL6326 (3 mg/kg at 4, 6, 8, and 10 days) decreased infarct volume and improved left ventricular ejection fraction in pigs. CONCLUSIONS: These data confirm CXCR4 blockade as a promising treatment strategy after MI. We identify dendritic cell-primed splenic Treg cells as the central arbiters of these therapeutic effects and thereby delineate a pharmacological strategy to promote infarct repair by augmenting Treg cell function in vivo.

Multifaceted C-X-C Chemokine Receptor 4 (CXCR4) Inhibition Interferes with Anti-Vascular Endothelial Growth Factor Therapy-Induced Glioma Dissemination.

Resistance to antiangiogenic therapy in glioblastoma (GBM) patients may involve hypoxia-induced expression of C-X-C motif chemokine receptor 4 (CXCR4) on invading tumor cells, macrophage/microglial cells (MGCs), and glioma stem cells (GSCs). We determined whether antagonizing CXCR4 with POL5551 disrupts anti-vascular endothelial growth factor (VEGF) therapy-induced glioma growth and dissemination. Mice bearing orthotopic CT-2A or GL261 gliomas received POL5551 and/or anti-VEGF antibody B20-4.1.1. Brain tissue was analyzed for tumor volume, invasiveness, hypoxia, vascular density, proliferation, apoptosis, GSCs, and MGCs. Glioma cells were evaluated for CXCR4 expression and polymorphism and POL5551's effects on CXCR4 ligand binding, cell viability, and migration. No CXCR4 mutations were identified. POL5551 inhibited CXCR4 binding to its ligand, stromal cell-derived factor-1α, and reduced hypoxia- and stromal cell-derived factor-1α-mediated migration dose-dependently but minimally affected cell viability. In vivo, B20-4.1.1 increased hypoxic foci and invasiveness, as seen in GBM patients receiving anti-VEGF therapy. Combination of POL5551 and B20-4.1.1 reduced both glioma invasiveness by 16% to 39% and vascular density compared to B20-4.1.1 alone in both glioma models. Reduced populations of GSCs and MGCs were also seen in CT-2A tumors. POL5551 concentrations, evaluated by mass spectrometry, were higher in tumors than in neighboring brain tissues, likely accounting for the results. Inhibition of CXCR4-regulated tumoral, stem cell, and immune mechanisms by adjunctive CXCR4 antagonists may help overcome antiangiogenic therapy resistance, benefiting GBM patients.

Mobilization of hematopoietic stem cells with the novel CXCR4 antagonist POL6326 (balixafortide) in healthy volunteers-results of a dose escalation trial.

BACKGROUND: Certain disadvantages of the standard hematopoietic stem and progenitor cell (HSPC) mobilizing agent G-CSF fuel the quest for alternatives. We herein report results of a Phase I dose escalation trial comparing mobilization with a peptidic CXCR4 antagonist POL6326 (balixafortide) vs. G-CSF. METHODS: Healthy male volunteer donors with a documented average mobilization response to G-CSF received, following ≥6 weeks wash-out, a 1-2 h infusion of 500-2500 µg/kg of balixafortide. Safety, tolerability, pharmacokinetics and pharmacodynamics were assessed. RESULTS: Balixafortide was well tolerated and rated favorably over G-CSF by subjects. At all doses tested balixafortide mobilized HSPC. In the dose range between 1500 and 2500 µg/kg mobilization was similar, reaching 38.2 ± 2.8 CD34 + cells/µL (mean ± SEM). Balixafortide caused mixed leukocytosis in the mid-20 K/µL range. B-lymphocytosis was more pronounced, whereas neutrophilia and monocytosis were markedly less accentuated with balixafortide compared to G-CSF. At the 24 h time point, leukocytes had largely normalized. CONCLUSIONS: Balixafortide is safe, well tolerated, and induces efficient mobilization of HSPCs in healthy male volunteers. Based on experience with current apheresis technology, the observed mobilization at doses ≥1500 µg/kg of balixafortide is predicted to yield in a single apheresis a standard dose of 4× 10E6 CD34+ cells/kg from most individuals donating for an approximately weight-matched recipient. Exploration of alternative dosing regimens may provide even higher mobilization responses. Trial Registration European Medicines Agency (EudraCT-Nr. 2011-003316-23) and clinicaltrials.gov (NCT01841476).

Efficacy of the Novel Antibiotic POL7001 in Preclinical Models of Pseudomonas aeruginosa Pneumonia.

The clinical development of antibiotics with a new mode of action combined with efficient pulmonary drug delivery is a priority against untreatable Pseudomonas aeruginosa lung infections. POL7001 is a macrocycle antibiotic belonging to the novel class of protein epitope mimetic (PEM) molecules with selective and potent activity against P. aeruginosa We investigated ventilator-associated pneumonia (VAP) and cystic fibrosis (CF) as indications of the clinical potential of POL7001 to treat P. aeruginosa pulmonary infections. MICs of POL7001 and comparators were measured for reference and clinical P. aeruginosa strains. The therapeutic efficacy of POL7001 given by pulmonary administration was evaluated in murine models of P. aeruginosa acute and chronic pneumonia. POL7001 showed potent in vitro activity against a large panel of P. aeruginosa isolates from CF patients, including multidrug-resistant (MDR) isolates with adaptive phenotypes such as mucoid or hypermutable phenotypes. The efficacy of POL7001 was demonstrated in both wild-type and CF mice. In addition to a reduced bacterial burden in the lung, POL7001-treated mice showed progressive body weight recovery and reduced levels of inflammatory markers, indicating an improvement in general condition. Pharmacokinetic studies indicated that POL7001 reached significant concentrations in the lung after pulmonary administration, with low systemic exposure. These results support the further evaluation of POL7001 as a novel therapeutic agent for the treatment of P. aeruginosa pulmonary infections.

CXCR7-dependent angiogenic mononuclear cell trafficking regulates tumor progression in multiple myeloma.

The CXCR4/stromal cell-derived factor-1 (SDF-1) axis is essential for cell trafficking and has been shown to regulate tumor progression and metastasis in many tumors including multiple myeloma (MM). A second chemokine receptor for SDF-1, CXCR7 was discovered recently and found on activated endothelial cells. We examined the role of CXCR7 in angiogenic mononuclear cells (AMCs) trafficking in MM. Our data demonstrate that AMCs are circulating in patients with MM and in vivo studies show that they specifically home to areas of MM tumor growth. CXCR7 expression is important for regulating trafficking and homing of AMCs into areas of MM tumor growth and neoangiogenesis. We demonstrate that the CXCR7 inhibitor, POL6926, abrogated trafficking of AMCs to areas of MM tumor progression leading to a significant inhibition of tumor progression. These effects were through regulation of endothelial cells and not through a direct tumor effect, indicating that targeting a bone marrow microenvironmental cell can lead to a delay in MM tumor progression. In conclusion, our studies demonstrate that CXCR7 may play an important role in the regulation of tumor progression in MM through an indirect effect on the recruitment of AMCs to areas of MM tumor growth in the bone marrow niche.

Protective effect of a Protein Epitope Mimetic CCR10 antagonist, POL7085, in a model of allergic eosinophilic airway inflammation.

BACKGROUND: Potential involvement of the CCR10/CCL28 axis was recently reported in murine models of allergic asthma. If confirmed, blockade of the CCR10 receptor would represent an alternative to current asthma therapies. We evaluated the effect of a novel Protein Epitope Mimetic CCR10 antagonist, POL7085, in a murine model of allergic eosinophilic airway inflammation. METHODS: Mice were sensitized and challenged to ovalbumin. POL7085, a CCR10 antagonist (7.5 and 15 mg/kg), dexamethasone (1 mg/kg) or vehicle were administered intranasally once daily 1h before each allergen challenge. On day 21, airway hyperresponsiveness, bronchoalveolar lavage inflammatory cells and Th2 cytokines, and lung tissue mucus and collagen were measured. RESULTS: Allergen challenge induced airway hyperresponsiveness in vehicle-treated animals as measured by whole body barometric plethysmography, and eosinophilia in bronchoalveolar lavage. POL7085 dose-dependently and significantly decreased airway hyperresponsiveness (34 ± 16 %) and eosinophil numbers in bronchoalveolar lavage (66 ± 6 %). In addition, the highest dose of POL7085 used significantly inhibited lung IL-4 (85 ± 4 %), IL-5 (87 ± 2 %) and IL-13 (190 ± 19 %) levels, and lung collagen (43 ± 11 %). CONCLUSIONS: The Protein Epitope Mimetic CCR10 antagonist, POL7085, significantly and dose-dependently decreased allergen-induced airway hyperresponsiveness and airway inflammation after once daily local treatment. Our data give strong support for further investigations with CCR10 antagonists in asthmatic disease.

ScRALF3, a secreted RALF-like peptide involved in cell-cell communication between the sporophyte and the female gametophyte in a solanaceous species.

Small peptides have been shown to regulate numerous aspects of plant development through cell-cell communication. These signaling events are particularly important during reproduction, regulating gamete development and embryogenesis. Rapid alkalinization factor (RALF)-like genes, a large gene family that encodes secreted peptides, have specific or ubiquitous expression patterns. Previously, five RALF-like genes with potential involvement during reproduction were isolated from Solanum chacoense. Here, we show that ScRALF3 is an important peptide regulator of female gametophyte development. Its expression, which is auxin-inducible, is strictly regulated before and after fertilization. Down-regulation of ScRALF3 expression by RNA interference leads to the production of smaller fruits that produce fewer seeds, due to improper development of the embryo sacs. Defects include loss of embryo sac nuclei polarization, as well as an increase in asynchronous division, accounting for cellular dysfunctions and premature embryo sac development arrest during megagametogenesis. ScRALF3 is expressed in the sporophytic tissue surrounding the embryo sac, the integument and the nucellus, as revealed by in situ hybridization and GUS staining. As expected for a secreted peptide, fluorescence from an ScRALF3-GFP fusion construct is detected throughout the secretory pathway. Therefore, the ScRALF3 secreted peptide may be directly involved in the regulation of multiple aspects of cell-cell communication between the female gametophyte and its surrounding sporophytic tissue during ovule development.

Effectiveness of Geriatric Assessment-Driven Interventions on Survival and Functional and Nutritional Status in Older Patients with Head and Neck Cancer: A Randomized Controlled Trial (EGeSOR).

This study assesses the efficacy of Geriatric Assessment (GA)-driven interventions and follow-up on six-month mortality, functional, and nutritional status in older patients with head and neck cancer (HNC). HNC patients aged 65 years or over were included between November 2013 and September 2018 by 15 Ear, Nose, and Throat (ENT) and maxillofacial surgery departments at 13 centers in France. The study was of an open-label, multicenter, randomized, controlled, and parallel-group design, with independent outcome assessments. The patients were randomized 1:1 to benefit from GA-driven interventions and follow-up versus standard of care. The interventions consisted in a pre-therapeutic GA, a standardized geriatric intervention, and follow-up, tailored to the cancer-treatment plan for 24 months. The primary outcome was a composite criterion including six-month mortality, functional impairment (fall in the Activities of Daily Living (ADL) score ≥2), and weight loss ≥10%. Among the patients included (n = 499), 475 were randomized to the experimental (n = 238) or control arm (n = 237). The median age was 75.3 years [70.4-81.9]; 69.5% were men, and the principal tumor site was oral cavity (43.9%). There were no statistically significant differences regarding the primary endpoint (n = 98 events; 41.0% in the experimental arm versus 90 (38.0%); p = 0.53), or for each criterion (i.e., death (31 (13%) versus 27 (11.4%); p = 0.48), weight loss of ≥10% (69 (29%) versus 65 (27.4%); p = 0.73) and fall in ADL score ≥2 (9 (3.8%) versus 13 (5.5%); p = 0.35)). In older patients with HNC, GA-driven interventions and follow-up failed to improve six-month overall survival, functional, and nutritional status.

Cell-cell communication and signalling pathways within the ovule: from its inception to fertilization.

Cell-cell communication pervades every aspect of the life of a plant. It is particularly crucial for the development of the gametes and their subtle interaction leading to double fertilization. The ovule is composed of a funiculus, one or two integuments, and a gametophyte surrounded by nucellus tissue. Proper ovule and embryo sac development are critical to reproductive success. To allow fertilization, the correct relative positioning and differentiation of the embryo sac cells are essential. Integument development is also intimately linked with the normal development of the female gametophyte; the sporophyte and gametophyte are not fully independent tissues. Inside the gametophyte, numerous signs of cell-cell communication take place throughout development, including cell fate patterning, fertilization and the early stages of embryogenesis. This review highlights the current evidence of cell-cell communication and signalling elements based on structural and physiological observations as well as the description and characterization of mutants in structurally specific genes. By combining data from different species, models of cell-cell interactions have been built, particularly for the establishment of the germline, for the progression through megagametogenesis and for double fertilization.

The discovery of AZD9164, a novel muscarinic M3 antagonist.

The optimization of a new series of muscarinic M(3) antagonists is described, leading to the identification of AZD9164 which was progressed into the clinic for evaluation of its potential as a treatment for COPD.

Personalised anti-inflammatory therapy for bronchiectasis and cystic fibrosis: selecting patients for controlled trials of neutrophil elastase inhibition.

BACKGROUND: Neutrophil elastase (NE) has been linked to lung neutrophil dysfunction in bronchiectasis and cystic fibrosis (CF), making NE inhibition a potential therapeutic target. NE inhibitor trials have given mixed result perhaps because not all patients have elevated airway NE activity. METHODS: We tested whether a single baseline sputum NE measurement or a combination of clinical parameters could enrich patient populations with elevated NE activity for "personalised medicine". Intra- and interindividual variations of total and active NE levels in induced sputum from patients with CF or bronchiectasis were monitored over 14 days. Patients with established CF and bronchiectasis (n=5 per group) were recruited. NE was measured using three different methods: one total and two active NE assays. Subsequently, we analysed the association between clinical parameters and NE from a large bronchiectasis cohort study (n=381). RESULTS: All three assays showed a high degree of day-to-day variability (0-233% over 14 days). There were strong correlations found between all assays (p<0.0001). Despite high day-to-day variability, patients could be stratified into "high" or "low" groups based on moderate cut-off levels. In the bronchiectasis cohort study, factors most associated with high sputum NE levels were: Pseudomonas aeruginosa infection (ß-estimate 11.5, 95% CI -6.0-29.0), sputum colour (ß-estimate 10.4, 95% CI 4.3-16.6), Medical Research Council dyspnoea score (ß-estimate 6.4, 95% CI 1.4-11.4) and exacerbation history (ß-estimate 3.4, 95% CI 1.4-5.3). Collectively, P. aeruginosa infection, sputum colour and exacerbation frequency provided the greatest specificity for "high" NE (98.7%, 95% CI 7.0-99.6%). CONCLUSION: These results show that patients with bronchiectasis and CF can be effectively divided into "high" or "low" groups, based on sputum NE assays or clinical inclusion criteria.

Protein epitope mimetic macrocycles as biopharmaceuticals.

Fully synthetic medium-sized macrocyclic peptides mimicking the key ß-hairpin and α-helical protein epitopes relevant in many protein-protein interactions have emerged as a novel class of drugs with the potential to fill an important gap between small molecules and proteins. Conformationally stabilized macrocyclic scaffolds represent ideal templates for medicinal chemists to incorporate bioactive peptide and protein pharmacophores in order to generate novel drugs to treat diseases with high unmet medical need. This review describes recent approaches to design and generate large libraries of such macrocycles, for hit identification, and for their efficient optimization. Finally, this review describes some of the most advanced protein epitope mimetic (PEM) macrocycles in clinical development.

CXCR4 Protein Epitope Mimetic Antagonist POL5551 Disrupts Metastasis and Enhances Chemotherapy Effect in Triple-Negative Breast Cancer.

The SDF-1 receptor CXCR4 has been associated with early metastasis and poorer prognosis in breast cancers, especially the most aggressive triple-negative subtype. In line with previous reports, we found that tumoral CXCR4 expression in patients with locally advanced breast cancer was associated with increased metastases and rapid tumor progression. Moreover, high CXCR4 expression identified a group of bone marrow-disseminated tumor cells (DTC)-negative patients at high risk for metastasis and death. The protein epitope mimetic (PEM) POL5551, a novel CXCR4 antagonist, inhibited binding of SDF-1 to CXCR4, had no direct effects on tumor cell viability, but reduced migration of breast cancer cells in vitro. In two orthotopic models of triple-negative breast cancer, POL5551 had little inhibitory effect on primary tumor growth, but significantly reduced distant metastasis. When combined with eribulin, a chemotherapeutic microtubule inhibitor, POL5551 additively reduced metastasis and prolonged survival in mice after resection of the primary tumor compared with single-agent eribulin. Hypothesizing that POL5551 may mobilize tumor cells from their microenvironment and sensitize them to chemotherapy, we used a "chemotherapy framing" dosing strategy. When administered shortly before and after eribulin treatment, three doses of POL5551 with eribulin reduced bone and liver tumor burden more effectively than chemotherapy alone. These data suggest that sequenced administration of CXCR4 antagonists with cytotoxic chemotherapy synergize to reduce distant metastases.

Beneficial effect of trimebutine and N-monodesmethyl trimebutine on trinitrobenzene sulfonic acid-induced colitis in rats.

The use of local anesthetics, such as lidocaine, has been proposed in the treatment of distal ulcerative colitis. Trimebutine maleate (TMB) displays a local anesthetic activity higher than that of lidocaine in rabbit corneal reflex. TMB and nor-TMB its main metabolite in human show similar affinity to that of bupivacaine toward sodium channel labeled by [3H]batrachotoxin and block sodium currents in sensory neurons from rat dorsal root ganglia. The aim of this study was to evaluate the effects of TMB and nor-TMB in comparison to lidocaine and bupivacaine in a rat model of acute colonic inflammation induced by trinitrobenzene sulfonic acid (TNBS). A single intracolonic instillation of TNBS (50 mg/kg dissolved in ethanol 30%) led to early plasma extravasation then macroscopic damage (hyperemia and necrosis), increased colonic weight and tissular MPO, a marker of neutrophilic infiltration. Local administration of TMB at dose of 3 to 60 mg/kg, 30 min before, 24 and 48 h after colitis induction, significantly reduced the severity of colitis. Nor-TMB (1, 3, 10, 30 mg/kg) as well as lidocaine (1, 3, 10 mg/kg) dose-dependently reduced colitis while bupivacaine at 10 mg/kg did not affect it significantly. In contrast systemic administration of TMB, nor-TMB and lidocaine at 10 mg/kg had no significant effect. Furthermore, local administration of TMB (30 mg/kg) and lidocaine (10 mg/kg) significantly reduced plasmatic extravasation. In conclusion, intracolonic treatment with TMB and nor-TMB improved acute experimental TNBS-induced colitis in rat and these effects could be explained by their local anesthetic activity.

Combined VEGF and CXCR4 antagonism targets the GBM stem cell population and synergistically improves survival in an intracranial mouse model of glioblastoma.

Glioblastoma recurrence involves the persistence of a subpopulation of cells with enhanced tumor-initiating capacity (TIC) that reside within the perivascular space, or niche (PVN). Anti-angiogenic therapies may prevent the formation of new PVN but have not prevented recurrence in clinical trials, suggesting they cannot abrogate TIC activity. We hypothesized that combining anti-angiogenic therapy with blockade of PVN function would have superior anti-tumor activity. We tested this hypothesis in an established intracranial xenograft model of GBM using a monoclonal antibody specific for murine and human VEGF (mcr84) and a Protein Epitope Mimetic (PEM) CXCR4 antagonist, POL5551. When doses of POL5551 were increased to overcome an mcr84-induced improvement in vascular barrier function, combinatorial therapy significantly inhibited intracranial tumor growth and improved survival. Anti-tumor activity was associated with significant changes in tumor cell proliferation and apoptosis, and a reduction in the numbers of perivascular cells expressing the TIC marker nestin. A direct effect on TICs was demonstrated for POL5551, but not mcr84, in three primary patient-derived GBM isolates. These findings indicate that targeting the structure and function of the PVN has superior anti-tumor effect and provide a strong rationale for clinical evaluation of POL5551 and Avastin in patients with GBM.

The CXCR4 antagonist POL5551 is equally effective as sirolimus in reducing neointima formation without impairing re-endothelialisation.

Impaired endothelial recovery after the implantation of drug-eluting stents is a major concern because of the increased risk for late stent thrombosis. The disruption of the chemokine axis CXCL12/CXCR4 inhibits neointima formation by blocking the recruitment of smooth muscle progenitor cells. To directly compare a CXCR4-targeting treatment strategy with drugs that are currently used for stent coating, we studied the effects of the CXCR4 antagonist POL5551 and the drug sirolimus on neointima formation. Apolipoprotein E-deficient mice were treated with POL5551 or sirolimus continuously for 28 days after a carotid wire injury. POL5551 inhibited neointima formation by 63% (for a dosage of 2 mg/kg/day) and by 70% (for a dosage of 20 mg/kg/day). In comparison, sirolimus reduced the neointimal area by 69%. In contrast to treatment with POL5551 during the first three days after injury, injection of POL5551 (20 mg/kg) once per day for 28 days diminished neointimal hyperplasia by 53%. An analysis of the cellular composition of the neointima showed a reduction in the relative smooth muscle cell (SMC) and macrophage content in mice that had been treated with a high dose of POL5551. In contrast, the diminished SMC content after sirolimus treatment was associated with a neointimal enrichment of macrophages. Furthermore, endothelial recovery was impaired by sirolimus, but not by POL5551. Therefore, the inhibition of CXCR4 by POL5551 is equally effective in preventing neointima formation as sirolimus, but POL5551 might be more beneficial because treatment with it results in a more stable lesion phenotype and because it does not impair re-endothelialisation.

Chemokine receptors as targets for cancer therapy.

Chemokines and their receptors play critical roles in leukocyte trafficking during inflammatory processes. Although the role of chemokine receptors (CKRs) in cancer biology is a relatively new field of study, a growing body of data suggest that a number of CKRs, including CXCR4, CCR4, CCR7, and CCR10, may play diverse of roles in cancer growth, cancer metastasis, cancer angiogenesis, or the composition of the cancer microenvironment. Preclinical models of cancer indicate that cancer antagonists, most notably those for CXCR4, can block cancer growth either directly or by altering the cancer stroma. Highthroughput screening methods to identify effective CKR antagonists have been developed, but specificity, potency, and drug-delivery of validated candidate compounds remain issues that result in the clinical failure of many initially promising candidates. The recent approval of a CCR5 receptor antagonist in HIV suggests that safe, effective small molecular antagonists for other CKRs may not be far away. There is still a clear need to extend our understanding of the signalling pathways by which CKRs facilitate cancer processes. Because of the role of CKRs in cancer cell survival, the combination of CKR antagonists with traditional chemotoxic agents or with immunotherapy is an alluring strategy since this increases the specificity of treatment to the cancer and potentially limits additional systemic side effects.

Characterization of five RALF-like genes from Solanum chacoense provides support for a developmental role in plants.

Five RALF (rapid alkalinization factor)-like genes, named ScRALF1 to 5, were isolated from fertilized ovule and ovary cDNA libraries of Solanum chacoense. They showed high sequence similarities with the RALF protein sequence from Nicotiana tabacum, and exhibited the characteristic architecture of RALF polypeptides. All ScRALFs were moderately to highly expressed at some stage of fruit maturation. ScRALF1 and ScRALF3 were predominantly expressed in ovaries and larger fruits, while ScRALF2, ScRALF4, and ScRALF5 were also expressed in other tissues, indicating that while some RALFs may be involved in fruit maturation, others could be involved in other developmental processes. Wounding or treatment of plants with growth regulators involved in plant defense responses had no significant impact on the mRNA level of any of these genes. These results suggest and support previous data showing that RALF peptides are more likely to act as a small peptide involved in plant development than in defense responses.

Cutting edge: chemoattractant receptor-homologous molecule expressed on Th2 cells plays a restricting role on IL-5 production and eosinophil recruitment.

PGs play key regulatory roles in inflammation and immunity. PGD2, released from mast cells and Th2 cells during allergic responses, has recently been shown to target a novel receptor, chemoattractant receptor-homologous molecule expressed TH2 cells (CRTH2), in addition to the classic PGD (DP) receptor. CRTH2 is expressed on Th2 cells and eosinophils and mediates chemotaxis of these cells to PGD2. Thus, CRTH2 is thought to be a key receptor mediating eosinophil and Th2 cell recruitment during allergic responses. To examine the role of CRTH2 in this context in vivo, we generated CRTH2 knockout mice. Surprisingly, in an allergic inflammatory model of asthma, CRTH2 knockout mice showed enhanced eosinophil recruitment into the lung compared with wild-type littermate mice. This is consistent with our observation that CRTH2 knockout cells produce significantly higher amounts of IL-5 and IL-3 in vitro. These results suggest a nonredundant role of CRTH2 in restricting eosinophilia and allergic response in vivo.

Discovery of thiadiazoles as a novel structural class of potent and selective PDE7 inhibitors. Part 2: metabolism-directed optimization studies towards orally bioavailable derivatives.

The synthesis and optimization of pharmacokinetic parameters of structurally novel small PDE7 inhibitors is discussed.