Vibrational dynamics of confined supercooled water

The quest for a possible liquid-liquid coexistence line in supercooled water below its homogeneous nucleation temperature is faced by confining water within a porous silica substrate (MCM-41). This system is investigated by synchrotron radiation infrared spectroscopy, exploring both the intramolecular and the intermolecular vibrational dynamics, in the temperature range from ambient down to ∼120 K, along several isobaric paths between 0.7 kbar and 3.0 kbar. Upon lowering the temperature, the OH-stretching band shows that the intramolecular vibrational dynamics continuously evolves from predominantly liquidlike to predominantly icelike. An abrupt change in the line shape of the intermolecular vibrational band between 220 K and 240 K, depending on the pressure, is the signature of nucleation of ice within the MCM-41 pores. These findings do not support the presence of two liquid phases and provide evidence for the coexistence of liquid water and ice in water confined in MCM-41.

Therapeutic efficacy of anti-MMP9 antibody in combination with nab-paclitaxel-based chemotherapy in pre-clinical models of pancreatic cancer

Matrix metalloproteinase 9 (MMP9) is involved in the proteolysis of extracellular proteins and plays a critical role in pancreatic ductal adenocarcinoma (PDAC) progression, invasion and metastasis. The therapeutic potential of an anti‐MMP9 antibody (αMMP9) was evaluated in combination with nab‐paclitaxel (NPT)‐based standard cytotoxic therapy in pre‐clinical models of PDAC. Tumour progression and survival studies were performed in NOD/SCID mice. The mechanistic evaluation involved RNA‐Seq, Luminex, IHC and Immunoblot analyses of tumour samples. Median animal survival compared to controls was significantly increased after 2‐week therapy with NPT (59%), Gem (29%) and NPT+Gem (76%). Addition of αMMP9 antibody exhibited further extension in survival: NPT+αMMP9 (76%), Gem+αMMP9 (47%) and NPT+Gem+αMMP9 (94%). Six‐week maintenance therapy revealed that median animal survival was significantly increased after NPT+Gem (186%) and further improved by the addition of αMMP9 antibody (218%). Qualitative assessment of mice exhibited that αMMP9 therapy led to a reduction in jaundice, bloody ascites and metastatic burden. Anti‐MMP9 antibody increased the levels of tumour‐associated IL‐28 (1.5‐fold) and decreased stromal markers (collagen I, αSMA) and the EMT marker vimentin. Subcutaneous tumours revealed low but detectable levels of MMP9 in all therapy groups but no difference in MMP9 expression. Anti‐MMP9 antibody monotherapy resulted in more gene expression changes in the mouse stroma compared to the human tumour compartment. These findings suggest that anti‐MMP9 antibody can exert specific stroma‐directed effects that could be exploited in combination with currently used cytotoxics to improve clinical PDAC therapy.

Ice crystallization observed in highly supercooled confined water

We investigate the state of water confined in the cylindrical pores of MCM-41 type mesoporous silica, with pore diameters of 2.8 nm and 4.5 nm, over the temperature range 160–290 K by combining small angle neutron scattering and wide angle diffraction.

Abstract 4822: Anti-MMP9 antibody in combination with standard cytotoxic therapy in preclinical models of pancreatic cancer

BACKGROUND: Matrix metalloproteinase 9 (MMP9) is involved in the proteolysis of extracellular proteins and is reported to play a key role in development, invasion and metastasis of many cancers including pancreatic ductal adenocarcinoma (PDAC). Andecaliximab is a potent and highly selective monoclonal antibody inhibitor of MMP9 that has shown antitumor activity in combination with chemotherapy in gastric cancer. The therapeutic potential of targeted MMP9 inhibition in combination with cytotoxic therapy in preclinical models of PDAC was evaluated through the use of an αMMP9 antibody.

METHODS: Animal survival and qualitative analysis were performed in the peritoneal dissemination model in mice using 7.5x105 AsPC-1 cells. Tumor growth study was performed in subcutaneous xenografts in mice using 7.5x105 AsPC-1 cells. The mechanistic evaluation involved RNASeq, Luminex, IHC and Immunoblot analysis in tumor samples.

RESULTS: Median animal survival compared to controls (17 days) was increased after 2-week therapy with NPT (27 days, a 59% increase), Gem (22 days, +29%) and NPT+Gem (30 days, +76%). Addition of αMMP9 antibody increased survival as follows: NPT+MMP9 (30 days, +76%), Gem+MMP9 (25 days, +47%) and NPT+Gem+MMP9 (33 days, +94%). Evaluation of efficacy of maintenance therapy (6-weeks) revealed that median animal survival (controls: 22 days) was increased after NPT+Gem therapy (63 days, +186%) and further improved by addition of αMMP9 antibody (70 days, +218%). Qualitative assessment of mice after 2-week therapy revealed that αMMP9 therapy led to reduction in jaundice, bloody ascites and metastatic burden, both alone and in combination with NPT+Gem. Tumor lysates demonstrated changes in several proteins in chemotherapy groups including IP-10, MDC, PAI-1, GM-CSF, MIP-1b and IL-12b. αMMP9 therapy increased IL-28 (1.5 fold, p = 0.016). IHC analysis revealed decreased tumor microvessel density based on endomucin staining in αMMP9 therapy groups (59.9%, p<0.0001). Immunoblot analysis showed decreased vimentin expression in αMMP9 therapy groups (42.5%, p =0.03). In tumor growth study, NPT+Gem significantly decreased tumor growth (72%, p=0.0005) compared to controls. αMMP9 therapy caused a non-significant decrease in tumor growth (17%, p=0.24). Tumor tissues revealed low, but detectable levels of MMP9 mRNA in all therapy groups but no difference in MMP9 expression. αMMP9 monotherapy resulted in more gene expression changes in the mouse stromal than the human tumor compartment compared to other treatments. However, NPT+Gem+MMP9 combination therapy resulted in greater numbers of changes in gene expression compared to the other treatments in the tumor compartment.

CONCLUSION: These findings suggest that MMP9 inhibition can augment the effects of standard cytotoxic therapy and support the potential of this combination therapeutic strategy for clinical PDAC therapy.

Citation Format: Niranjan Awasthi, Amanda Mikels-Vigdal, Erin Stefanutti, Margaret A. Schwarz, Sheena Monahan, Victoria Smith, Roderich E. Schwarz. Anti-MMP9 antibody in combination with standard cytotoxic therapy in preclinical models of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4822.

Abstract 653: Inhibition of MMP9 improves anti-tumor immunity by changing the tumor microenvironment to promote T cell trafficking and activation

Background: Matrix metalloproteinase 9 (MMP9) acts via diverse mechanisms to promote tumor growth, invasion, and metastasis. It activates growth factors and signaling pathways, promotes angiogenesis, and impedes anti-tumor immune responses. We developed a monoclonal antibody that inhibits mouse MMP9 (AB0046) and assessed its mechanism of action in immunocompetent mouse tumor models and in vitro assays.

Methods: We examined MMP9 expression in a variety of human tumor tissues via immunohistochemistry. Human monocytes were differentiated in vitro and protein expression was assessed via enzyme-linked immunosorbent assay. Primary tumor growth in orthotopic, syngeneic tumor models was examined following anti-MMP9 antibody treatment. RNA sequencing, immunohistochemical and flow cytometry analyses were performed on tumor tissues to assess gene expression, stromal remodeling and macrophage polarization in response to AB0046 treatment.

Results: MMP9 levels are elevated in human tumors compared to healthy tissues. The protein is expressed predominantly in stromal cells, including macrophages and neutrophils, with more occasional heterogeneous expression in tumor epithelia. Differentiation of human monocyte-derived macrophages in vitro revealed that M2 polarization is associated with increased expression of MMP9 and Th2 markers CCL18 and TGFβ. Anti-MMP9 treatment in three independent mouse tumor models (HC11-NeuT, CT26, Lewis lung carcinoma (LLC)) resulted in decreased primary tumor growth (p=0.001 and p=0.018 for HC11-NeuT and CT26 respectively) and increased animal survival (p=0.024 for LLC). Gene expression profiling of tumors from the various models demonstrated that inhibition of MMP9 resulted in elevated expression of genes associated with immune cell activation pathways (Hallmark Interferon Gamma Response, p<0.05, FDR<0.001). Additional analysis in the HC11-NeuT model revealed a significant decrease in M2 macrophages in the tumor microenvironment (p < 0.05) with AB0046 treatment, as well as reductions in tumor-associated fibrillar collagen as assessed by Picrosirius red staining.

Conclusions: These analyses show that MMP9 is expressed in a variety of human tumors. Our data suggest that inhibition of MMP9 promotes anti-tumor immunity and enhances a Th1 immune response. GS-5745, a humanized anti-MMP9 inhibitory antibody, is being evaluated in gastric cancer in phase 3 and 2 studies with chemotherapy and nivolumab, respectively (NCT02545504, NCT02864381).

Citation Format: Vladi Juric, Amanda Mikels-Vigdal, Chris O'Sullivan, Andrew Greenstein, Erin Stefanutti, Vivian Barry-Hamilton, Igor Mikaelian, Ted Sullivan, Erik Huntzicker, Jeremiah Degenhardt, Peng Yue, Victoria Smith. Inhibition of MMP9 improves anti-tumor immunity by changing the tumor microenvironment to promote T cell trafficking and activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 653. doi:10.1158/1538-7445.AM2017-653

Cationic liposomes formulated with DMPC and a gemini surfactant traverse the cell membrane without causing a significant bio-damage

Cationic liposomes have been intensively studied both in basic and applied research because of their promising potential as non-viral molecular vehicles. This work was aimed to gain more information on the interactions between the plasmamembrane and liposomes formed by a natural phospholipid and a cationic surfactant of the gemini family. The present work was conducted with the synergistic use of diverse experimental approaches: electro-rotation measurements, atomic force microscopy, ζ-potential measurements, laser scanning confocal microscopy and biomolecular/cellular techniques. Electro-rotation measurements pointed out that the interaction of cationic liposomes with the cell membrane alters significantly its dielectric and geometric parameters. This alteration, being accompanied by significant changes of the membrane surface roughness as measured by atomic force microscopy, suggests that the interaction with the liposomes causes locally substantial modifications to the structure and morphology of the cell membrane. However, the results of electrophoretic mobility (ζ-potential) experiments show that upon the interaction the electric charge exposed on the cell surface does not vary significantly, pointing out that the simple adhesion on the cell surface of the cationic liposomes or their fusion with the membrane is to be ruled out. As a matter of fact, confocal microscopy images directly demonstrated the penetration of the liposomes inside the cell and their diffusion within the cytoplasm. Electro-rotation experiments performed in the presence of endocytosis inhibitors suggest that the internalization is mediated by, at least, one specific pathway. Noteworthy, the liposome uptake by the cell does not cause a significant biological damage.

Epoxy resin/carbon black composites below the percolation threshold

A set of epoxy resin composites filled with 0.25-2.0 wt.% of commercially available ENSACO carbon black (CB) of high and low surface area (CBH and CBL respectively) has been produced. The results of broadband dielectric spectroscopy of manufactured CB/epoxy below the percolation threshold in broad temperature (200 K to 450 K) and frequency (20 Hz to 1 MHz) ranges are reported. The dielectric properties of composites below the percolation threshold are mostly determined by alpha relaxation in pure polymer matrix. The glass transition temperature for CB/epoxy decreases in comparison with neat epoxy resin due to the extra free volume at the polymer-filler interface. At room temperature, the dielectric permittivity is higher for epoxy loaded with CBH additives. In contrast, at high temperature, the electrical conductivity was found to be higher for composites with CBL embedded. The established influence of the CB surface area on the broadband dielectric characteristics can be exploited for the production of effective low-cost antistatic paints and coatings working at different temperatures.