Direct Airway Instillation of Neutrophils Overcomes Chemotactic Deficits Induced by Injury.

BACKGROUND: Trauma induces neutrophil migration toward injury sites, both initiating wound healing and protecting against local bacterial infection. We have previously shown that mitochondrial formyl peptides (mtFPs) released by injured tissues act as chemoattractants by ligating neutrophil (PMN) formyl peptide receptor 1 (FPR1). But this process can also internalize multiple neutrophil chemoattractant receptors and thus might limit neutrophil migration to the lung in response to bacteria. Our objective was to better understand susceptibility to pneumonia after injury and thus find ways to reverse it. METHODS AND RESULTS: We modeled the alveolar chemotactic environment in pulmonary infections by incubating Staphylococcus aureus or Escherichia coli with peripheral blood mononuclear cells. Survey of the chemotactic mediators in the resultant conditioned media (CM) showed multiple potent chemoattractants. Pretreating PMN with mtFPs to mimic injury potently reduced net migration toward CM and this net effect was mostly reversed by an FPR1 antagonist. Using an established mouse model of injury-dependent lung infection, we then showed simple instillation of exogenous unstimulated human neutrophils into the airway resulted in bacterial clearance from the lung. CONCLUSION: Injury-derived mtFPs suppress global PMN localization into complex chemotactic environments like infected alveoli. Transplantation of naive exogenous human neutrophils into the airway circumvents that pathologic process and prevents development of post-traumatic pneumonia without injury noted to the recipients.

Formyl Peptide Receptor-1 Blockade Prevents Receptor Regulation by Mitochondrial Danger-Associated Molecular Patterns and Preserves Neutrophil Function After Trauma.

OBJECTIVES: Trauma predisposes to systemic sterile inflammation (systemic inflammatory response syndrome) as well as infection, but the mechanisms linking injury to infection are poorly understood. Mitochondrial debris contains formyl peptides. These bind formyl peptide receptor-1, trafficking neutrophils to wounds, initiating systemic inflammatory response syndrome, and wound healing. Bacterial formyl peptides, however, also attract neutrophils via formyl peptide receptor-1. Thus, mitochondrial formyl peptides might suppress neutrophils antimicrobial function. Also, formyl peptide receptor-1 blockade used to mitigate systemic inflammatory response syndrome might predispose to sepsis. We examined how mitochondrial formyl peptides impact neutrophils functions contributing to antimicrobial responses and how formyl peptide receptor-1 antagonists affect those functions. DESIGN: Prospective study of human and murine neutrophils and clinical cohort analysis. SETTING: University research laboratory and level 1 trauma center. PATIENTS: Trauma patients, volunteer controls. ANIMAL SUBJECTS: C57Bl/6, formyl peptide receptor-1, and formyl peptide receptor-2 knockout mice. INTERVENTIONS: Human and murine neutrophils functions were activated with autologous mitochondrial debris, mitochondrial formyl peptides, or bacterial formyl peptides followed by chemokines or leukotrienes. The experiments were repeated using formyl peptide receptor-1 antagonist cyclosporin H, "designer" human formyl peptide receptor-1 antagonists (POL7178 and POL7200), or anti-formyl peptide receptor-1 antibodies. Mouse injury/lung infection model was used to evaluate effect of formyl peptide receptor-1 inhibition. MEASUREMENTS AND MAIN RESULTS: Human neutrophils cytosolic calcium, chemotaxis, reactive oxygen species production, and phagocytosis were studied before and after exposure to mitochondrial debris, mitochondrial formyl peptides, and bacterial formyl peptides. Mitochondrial formyl peptide and bacterial formyl peptides had similar effects on neutrophils. Responses to chemokines and leukotrienes were suppressed by prior exposure to formyl peptides. POL7200 and POL7178 were specific antagonists of human formyl peptide receptor-1 and more effective than cyclosporin H or anti-formyl peptide receptor-1 antibodies. Formyl peptides inhibited mouse neutrophils responses to chemokines only if formyl peptide receptor-1 was present. Formyl peptide receptor-1 blockade did not inhibit neutrophils bacterial phagocytosis or reactive oxygen species production. Cyclosporin H increased bacterial clearance in lungs after injury. CONCLUSIONS: Formyl peptides both activate and desensitize neutrophils. Formyl peptide receptor-1 blockade prevents desensitization, potentially both diminishing systemic inflammatory response syndrome and protecting the host against secondary infection after tissue trauma or primary infection.

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.

POL7085 or anti-CCL28 treatment inhibits development of post-paramyxoviral airway disease.

INTRODUCTION: Asthma is major health burden throughout the world, and there are no therapies that have been shown to be able to prevent the development of disease. A severe respiratory paramyxoviral infection early in life has been demonstrated to greatly increase the risk of developing asthma. We have a mouse model of a severe respiratory paramyxoviral infection (Sendai virus, SeV) that mimics human disease, and requires early expression of the cytokine CCL28 to drive the development of post-viral airway disease. The known receptors for CCL28 are CCR3 and CCR10. However, it is not known if blockade of these receptors will prevent the development of post-viral airway disease. The objective of this study was to determine if treatment with a protein epitope mimetic antagonist of CCR10, POL7085, will provide sufficient protection against the development of post-viral airway disease. METHODS: C57BL6 mice were inoculated with SeV or UV inactivated SeV. From day 3-19 post inoculation (PI), mice were subcutaneously administered daily POL7085 or saline, or every other day anti-CCL28 mAb. On days 8, 10, and 12 PI bronchoalveolar cytokines, serum IgE, and lung cellular constituents were measured. At day 21 PI airway hyper-reactivity to methacholine and mucous cell metaplasia was measured. RESULTS: Treatment with either anti-CCL28 or POL7085 significantly reduced development of airway hyper-reactivity and mucous cell metaplasia following SeV infection. The prevention of post-viral airway disease was associated with early reductions in innate immune cells, but did not appear to be due to a reduction in IL-13 or IgE. CONCLUSIONS: Blockade of CCL28 or CCR10 during an acute severe respiratory paramyxoviral infection is sufficient to prevent the development of post-viral airway disease. However, the mechanism of action is unclear and requires further exploration.

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).

POL5551, a novel and potent CXCR4 antagonist, enhances sensitivity to chemotherapy in pediatric ALL.

The importance of the cell surface receptor CXCR4 and the chemokine stromal cell-derived factor-1 (SDF-1/CXCL12) is well-established in normal and malignant hematopoiesis. The Protein Epitope Mimetic POL5551 is a novel and potent antagonist of CXCR4. POL5551 efficiently mobilizes hematopoietic stem and progenitor cells, but its effects in acute lymphoblastic leukemia (ALL) have not been reported. Here, we demonstrate that POL5551 is a potent antagonist of CXCR4 in pre-B and T cell ALL cell lines and pediatric ALL primary samples. POL5551 has activity at nanomolar concentrations in decreasing CXCR4 antibody binding, blocking SDF-1α-mediated phosphorylation of ERK1/2, inhibiting SDF-1α-induced chemotaxis, and reversing stromal-mediated protection from chemotherapy. POL5551 is significantly more effective at inhibiting CXCR4 antibody binding than the FDA-approved CXCR4 inhibitor plerixafor in ALL cell lines and primary samples. We also show that treatment with POL5551 in vitro and cytarabine +/- POL5551 in vivo modulates surface expression of adhesion molecules, findings that may guide the optimal clinical use of POL5551. Finally, we demonstrate that POL5551 increases sensitivity to cytarabine in a xenograft model of a high-risk pediatric ALL, infant MLL-rearranged (MLL-R) ALL. Therefore, disruption of the CXCR4/SDF-1 axis with POL5551 may improve outcomes in children with high-risk ALL.

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.

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.

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 translational challenge in the development of new and effective therapies for endometriosis: a review of confidence from published preclinical efficacy studies.

BACKGROUND: Endometriosis is a benign gynaecological condition that presents symptoms of chronic pelvic pain and the ectopic growth of endometrial lesions at sites on the peritoneum. Few new approaches to the management of the disease symptoms and progression have emerged in decades. The cornerstone of developing new therapies is the confidence and translational value placed in the preclinical models used to assess efficacy of emerging approaches. METHODS: We systematically reviewed preclinical efficacy data from rodent and non-human primates, evaluating the effects of an investigational agent or target reported in PubMed between 2000 and 2010. We evaluated the reports for which model and end-points had been used to determine efficacy, whether there was evidence of independent replication, whether techniques had been incorporated into the experimental design to eliminate potential bias and whether there was a confirmation of drug exposure or target engagement in the study. RESULTS: We identified 94 publications that met our criteria for review. Efficacy studies were conducted in a wider range of different models with no clear consensus on which model or end-point has the most translational value. The large majority of studies either did not report what measures were incorporated into the design to address potential bias or account for it or did not confirm whether the specified target was engaged. CONCLUSIONS: Greater scrutiny of the preclinical efficacy models, end-points and experimental designs is needed if the desire of translating novel treatment approaches is to be realized for women with endometriosis.

Anti-inflammatory modulation of chronic airway inflammation in the murine house dust mite model.

Asthma affects 300 million people worldwide and continues to be a major cause of morbidity and mortality. Disease relevant animal models of asthma are required for benchmarking of novel therapeutic mechanisms in comparison to established clinical approaches. We demonstrate that chronic exposure of mice to house dust mite (HDM) extract results in allergic airway inflammation, that can be significantly attenuated by therapeutic intervention with phosphodiesterase 4 inhibition and corticosteroid treatment. Female BALB/c mice were administered intranasally with HDM (Dermatophagoides pteronyssinus) extract daily for five weeks, and therapeutic intervention with anti-inflammatory treatment (dexamethasone 1 mg/kg subcutaneous once daily, prednisolone 10mg/kg orally twice daily, fluticasone 3, 10 and 30 microg intranasally twice daily, roflumilast 10 mg/kg orally twice daily and intranasally 10 and 30 microg twice daily) was initiated after three weeks of exposure. Chronic HDM extract exposure resulted in significant airway inflammation, demonstrated by bronchoalveolar lavage cell infiltration and lung tissue inflammatory gene expression by TaqMan low density array. Chronic steroid treatment significantly inhibited these parameters. In addition, roflumilast caused a significant reduction in airway inflammatory cell infiltration. We have demonstrated that chronic HDM-induced allergic inflammation can be significantly ameliorated by steroid treatment, and that phosphodiesterase 4 inhibition modulates inflammatory cell infiltration. Therefore, the murine HDM model may be a useful tool for evaluating new targets for the treatment of asthma.