Most drugs used to treat viral disease target a virus-coded product. They inhibit a single virus or virus family, and the pathogen can readily evolve resistance. Host-targeted antivirals can overcome ...these limitations. The broad-spectrum activity achieved by host targeting can be especially useful in combating emerging viruses and for treatment of diseases caused by multiple viral pathogens, such as opportunistic agents in immunosuppressed patients. We have developed a family of compounds that modulate sirtuin 2, an NAD+-dependent deacylase, and now report the properties of a member of that family, FLS-359. Biochemical and x-ray structural studies show that the drug binds to sirtuin 2 and allosterically inhibits its deacetylase activity. FLS-359 inhibits the growth of RNA and DNA viruses, including members of the coronavirus, orthomyxovirus, flavivirus, hepadnavirus, and herpesvirus families. FLS-359 acts at multiple levels to antagonize cytomegalovirus replication in fibroblasts, causing modest reductions in viral RNAs and DNA, together with a much greater reduction in infectious progeny, and it exhibits antiviral activity in humanized mouse models of infection. Our results highlight the potential of sirtuin 2 inhibitors as broad-spectrum antivirals and set the stage for further understanding of how host epigenetic mechanisms impact the growth and spread of viral pathogens.
Targeted monoclonal antibody therapy is an important strategy in cancer therapeutics. Among the most promising characteristics of therapeutic targets are those that modulate the growth and survival ...of malignant neoplasms and their sensitivity to anticancer therapies. The insulin-like growth factor-I receptor (IGF-IR) is overexpressed in many types of solid and hematopoietic malignancies, and has been implicated as a principal cause of heightened proliferative and survival signaling. IGF-IR has also been shown to confer resistance to cytotoxic, hormonal, and targeted therapies, suggesting that therapeutics targeting IGF-IR may be effective against a broad range of malignancies. IMC-A12 (ImClone Systems Incorporated), a fully human monoclonal IgG1 antibody that binds with high affinity to the IGF-IR, inhibits ligand-dependent receptor activation and downstream signaling. IMC-A12 also mediates robust internalization and degradation of the IGF-IR. In human tumor xenograft models, IGF-IR blockade by IMC-A12 results in rapid and profound growth inhibition of cancers of the breast, lung, colon, and pancreas, and many other neoplasms. Although promising single-agent activity has been observed, the most impressive effects of targeting the IGF-IR with IMC-A12 have been noted when this agent was combined with cytotoxic agents or other targeted therapeutics. The results with IMC-A12 to date suggest that it may be an effective therapeutic in a diverse array of oncologic indications.
Due to a long running research bias toward the breeding season, there are major gaps in knowledge on the basic nonbreeding ecology of many species, preventing a full‐annual cycle focus in ecology and ...conservation. Exacerbating this problem is the fact that many species are extremely difficult to detect outside of breeding. Here, we demonstrate a partial solution to this problem by using archival GPS tags to examine the overwintering ecology of a migratory nocturnal bird, the eastern whip‐poor‐will (Antrostomus vociferous). We deployed tags on 21 individuals and were able to recover 11 (52%) one year later. Tags collected high precision (approx. 10 m) points throughout the nonbreeding period. With continuous time movement models, we used these data to estimate overwintering home ranges. All individuals exhibited at least one bounded home range during this phase of the annual cycle, three of eleven had two wintering locations, and home range area ranged from 0.50 to 10.85 ha. All overwintering home ranges contained closed‐canopy forest land cover (42%–100%), and no other land cover type represented >40% of any home range. We found some evidence, with caveats, that total edge within the landscape surrounding the home range was negatively related to home range area. The prevalence of contiguous closed‐canopy forest cover in overwintering home ranges contrasts with apparent breeding habitat preferences, which includes clear‐cuts and other, more open, habitats. This study is the first to reveal key aspects of overwintering space use in this species by using archival GPS to overcome both logistical and methodological limitations. Expanded use of such technology is critical to gathering basic ecological and distributional data, necessary for achieving a more complete understanding of full‐annual cycles of animal populations.
By using archival GPS, for the first time we have been able to map home ranges and quantify land cover for a nightjar (Family Caprimulgidae) during the nonbreeding season. We found contrasting patterns of habitat use with the breeding season and high variability in home range area. This is critical natural history information for understanding the full‐annual cycle of this guild.
Migratory birds spend most of their journeys at stopover sites where they rest and refuel. Many migrants are in steep decline, and understanding their behavior within and among migrations is crucial ...for developing effective conservation strategies across the full annual cycle. One of the most rapidly declining songbirds in North America is the Rusty Blackbird (Euphagus carolinus; 85–95% decline over the past 50 yr), and stopover ecology is a major gap in our knowledge of its annual cycle. We utilized an automated telemetry array in western Lake Erie and the Motus Wildlife Tracking System to track landscape-scale movements, stopover duration, departure behavior, and between-season site fidelity in this species. We found that stopover duration during both fall and spring was nearly 1 mo (mean = 25.5 days)—exceptionally long for a passerine. During spring, birds in both poor condition and high degree of molt had longer stopovers, post-departure flights were relatively long for a songbird, and tailwinds predicted departure in both seasons. Many individuals made landscape-scale (10–35 km) relocations during stopover. Site fidelity was high for a passerine, in terms of both route and stopover site. Taken together, these behaviors describe a migration strategy that largely matches the staging behavior of shorebirds. Lastly, we found that Rusty Blackbirds migrate directly across Lake Erie and migrate primarily at night, which might expose them to mortality from offshore wind development. Collectively, our results indicate that high-quality stopover habitat may be critically important to Rusty Blackbird populations. More broadly, our results highlight the need to expand the scale of stopover studies, and to further explore all aspects of species' annual cycles to understand potential limiting factors on populations.
Purpose
Chemotherapy-induced neutropenia (CIN) increases the risk of infections and mortality in cancer patients. G-CSF therapies are approved for the treatment of CIN, but non-G-CSF therapies are ...needed to increase efficacy and minimize side effects. Plinabulin is an inhibitor of tubulin polymerization that ameliorates CIN caused in patients by the microtubule stabilizer docetaxel. The present study evaluates the potential of plinabulin to reduce neutropenia induced by chemotherapies of different classes in a manner not dependent on increasing G-CSF.
Methods
The anti-CIN benefits of plinabulin were tested in rodents co-treated with docetaxel, cyclophosphamide or doxorubicin. Effects on G-CSF levels were evaluated in tissues by immunoassay. Flow cytometry was utilized to test treatment effects on femur bone marrow cell counts from immunocompetent mice-bearing orthotopic 4T1 breast cancer tumors.
Results
Plinabulin alleviated neutropenia induced by microtubule stabilizing, DNA cross-linking and DNA intercalating chemotherapies, yet did not affect bone marrow or blood G-CSF levels. The number of lineage
−
/Sca1
+
/c-Kit
+
(LSK) hematopoietic stem/progenitor cells (HSPC) in murine bone marrow collected 2 days after treatment was not affected by docetaxel monotherapy despite increased plasma G-CSF in this group. LSK cell number was, however, increased when plinabulin was combined with docetaxel, without affecting G-CSF.
Conclusions
Results support the clinical testing of plinabulin as a non-G-CSF-based treatment for CIN associated with chemotherapies of different mechanisms. Results also support HSPC as a focal point for future mechanism-of-action work aimed at understanding the ability of plinabulin to reduce this serious side effect of cytotoxic therapy in cancer patients.
Parathyroid hormone (PTH) affects the skeleton by acting on osteocytes (Ots) in bone through yet unclear mechanisms. We report that matrix metalloproteinase 14 (MMP14) expression/activity are ...increased in bones from mice with genetic constitutive activation (ca) of the PTH receptor 1 (PTH1R) in Ots (caPTH1ROt) and in bones from mice exposed to elevated PTH levels but not in mice lacking conditional knockout (cKO) the PTH1R in Ots (cKOPTH1ROt). Furthermore, PTH upregulates MMP14 in human bone cultures and in Ot‐enriched bones from floxed control mice but not from cKOPTH1ROt mice. MMP14 activity increases soluble receptor activator of NF‐κB ligand production, which in turn, stimulates osteoclast differentiation and resorption. Pharmacologic inhibition of MMP14 activity reduced the high bone remodeling exhibited by caPTH1ROt mice or induced by chronic PTH elevation and decreased bone resorption but allowed full stimulation of bone formation induced by PTH injections, thereby potentiating bone gain. Thus, MMP14 is a new member of the intricate gene network activated in Ots by PTH1R signaling that can be targeted to adjust the skeletal responses to PTH in favor of bone preservation.—Delgado‐Calle, J., Hancock, B., Likine, E. F., Sato, A. Y., McAndrews, K., Sanudo, C., Bruzzaniti, A., Riancho, J. A., Tonra, J. R., Bellido, T. MMP14 is a novel target of PTH signaling in osteocytes that controls resorption by regulating soluble RANKL production. FASEB J. 32, 2878–2890 (2018). www.fasebj.org
Vascular endothelial growth factor receptor 3 (VEGFR-3) binds VEGF-C and VEGF-D and is essential for the development of the lymphatic vasculature. Experimental tumors that overexpress VEGFR-3 ligands ...induce lymphatic vessel sprouting and enlargement and show enhanced metastasis to regional lymph nodes and beyond, whereas a soluble form of VEGFR-3 that blocks receptor signaling inhibits these changes and metastasis. Because VEGFR-3 is also essential for the early blood vessel development in embryos and is up-regulated in tumor angiogenesis, we wanted to determine if an antibody targeting the receptor that interferes with VEGFR-3 ligand binding can inhibit primary tumor growth. Our results show that antibody interference with VEGFR-3 function can inhibit the growth of several human tumor xenografts in immunocompromised mice. Immunohistochemical analysis showed that the blood vessel density of anti-VEGFR-3-treated tumors was significantly decreased and hypoxic and necrotic tumor tissue was increased when compared with tumors treated with control antibody, indicating that blocking of the VEGFR-3 pathway inhibits angiogenesis in these tumors. As expected, the anti-VEGFR-3-treated tumors also lacked lymphatic vessels. These results suggest that the VEGFR-3 pathway contributes to tumor angiogenesis and that effective inhibition of tumor progression may require the inhibition of multiple angiogenic targets.
Reprogramming tumor infiltrating myeloid cells to elicit pro-inflammatory responses is an exciting therapeutic maneouver to improve anti-tumor responses. We recently demonstrated that a distinct ...microtubule-targeting drug, plinabulin-a clinical-stage novel agent-modulates dendritic cell maturation and enhances anti-tumor immunity. Here, we investigated the effects of plinabulin on macrophage polarization
and
. Plinabulin monotherapy induced significant tumor growth inhibition in mice bearing subcutaneous MC38 colon cancer. Importantly, the regressing tumors were characterized by an increase in M1-like/M2-like tumor-associated macrophages (TAM) ratio. The efficacy of plinabulin remained unaltered in T cell-deficient Rag2
mice, suggesting an important role of macrophages in driving the drug's anti-tumor effect. Exposure of murine and healthy human macrophages to plinabulin induced polarization toward the M1 phenotype, including increased expression of co-stimulatory molecules CD80, CD86 and pro-inflammatory cytokines IL-1β, IL-6, and IL-12. M2-associated immunosuppressive cytokines IL-10 and IL-4 were reduced. This pro-inflammatory M1-like skewing of TAMs in response to plinabulin was dependent on the JNK pathway. Functionally, plinabulin-polarized human M1 macrophages directly killed HuT 78 tumor cells
. Importantly, plinabulin induced a functional M1-like polarization of tumor infiltrating macrophages in murine tumors as well as in tumor samples from ovarian cancer patients, by preferentially triggering M1 proliferation. Our study uncovers a novel immunomodulatory effect of plinabulin in directly triggering M1 polarization and proliferation as well as promoting TAM anti-tumoral effector functions.
Vascular endothelial growth factor receptor-1 (VEGFR-1) plays important roles in promotion of tumor growth by mediating cellular functions in tumor vascular endothelium and cancer cells. Blockade of ...VEGFR-1 activation has been shown to inhibit pathologic angiogenesis and tumor growth, implicating VEGFR-1 as a potential therapeutic target for the treatment of cancer. We have thus developed a VEGFR-1 antagonist human monoclonal antibody designated as IMC-18F1 and evaluated its antitumor activity in preclinical experimental models to show the therapeutic potential of the antibody for cancer treatment in clinic.
Human IgG transgenic mice were used for generation of anti-VEGFR-1 antibodies. Anti-VEGFR-1-specific blocking antibodies were identified using solid-phase binding and blocking assays. Inhibitory antitumor cell activity of IMC-18F1 was assessed in cell-based kinase and growth assays. Pharmacokinetic/pharmacodynamic studies were done to determine the association of antibody blood level with antitumor efficacy of the antibody in vivo. Antitumor efficacy of the anti-VEGFR-1 antibodies as monotherapy and in combination with cytotoxic agents was evaluated in human breast cancer xenograft models.
A fully human neutralizing antibody, IMC-18F1, was shown to be a high-affinity (KD=54 pmol) inhibitor of VEGFR-1 ligand binding (VEGF-A, VEGF-B, and placental growth factor). IMC-18F1 inhibited ligand-induced intracellular activation of VEGFR-1 and mitogen-activated protein kinase signaling and prevented ligand-stimulated in vitro growth of breast cancer cells. In vivo, IMC-18F1 suppressed the growth of human breast tumor xenografts in association with reduced mitogen-activated protein kinase and Akt activation, reduced tumor cell proliferation, and increased tumor cell apoptosis. Pharmacokinetic/pharmacodynamic studies established a plasma elimination half-life of 5 days for IMC-18F1 and a steady-state trough plasma therapeutic threshold of 88 microg/mL. Importantly, inhibition of mouse and human VEGFR-1 with MF1 and IMC-18F1, respectively, enhanced the antitumor efficacy of cytotoxic agents commonly used to treat breast cancer.
Based on preclinical validation studies, IMC-18F1 anti-VEGFR-1 has potential to provide clinical benefit to cancer patients.
The inducible costimulatory molecule (ICOS) is expressed on activated T cells and participates in a variety of important immunoregulatory functions. After the induction of experimental allergic ...encephalomyelitis in SJL mice with proteolipid protein (PLP), brain ICOS mRNA and protein were up-regulated on infiltrating CD3+ T cells before disease onset. ICOS blockade during the efferent immune response (9-20 days after immunization) abrogated disease, but blockade during antigen priming (1-10 days after immunization) exacerbated disease. Upon culture with PLP and compared with immunized controls, splenocytes produced either decreased interferon-gamma (IFN-gamma, in efferent blockade) or excessive IFN-gamma (in priming blockade). PLP-specific immunoglobulin G1 was decreased in animals treated with anti-ICOS during antigen priming, but not in other groups.
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