Inhibition of interleukin-10 signaling in lung dendritic cells by toll-like receptor 4 ligands.

The homeostatic microenvironment in lung is immunosuppressive and interleukin-10 (IL-10) helps maintain this microenvironment. Despite constitutive production of IL-10 in normal lung, macrophages (MØs) and dentritic cells (DCs) remain capable of responding to microorganisms, suggesting that these innate immune cells have a mechanism to override the immunosuppressive effects of IL-10. Prior studies by the authors revealed that Toll-like receptor (TLR) ligands inhibit IL-10 receptor signaling in alveolar macrophages (AMØs), thereby obviating the immunosuppressive activity of IL-10. This report compares the immunologic phenotypes of AMØs and lung DCs and their ability to respond to IL-10 following exposure to microbial stimuli. IL-10 was constitutively produced by normal lung epithelium and exposure to lipopolysaccharide (LPS) in vivo increased the expression of IL-10 during the first 24 hours. AMØs constitutively produced IL-10 mRNA, whereas both AMØs and LDCs constitutively expressed IL-12 mRNA. AMØs and LDCs, as well as bone marrow-derived MØs and DCs, had reduced capacity to activate STAT3 in response to IL-10 if pretreated with LPS. Inhibition was not associated with decreased expression of IL-10 receptor (IL-10R) and was dependent on the MyD88 signaling pathway. These results demonstrate a common underlying regulatory mechanism in both DCs and MØs by which microbial stimuli can override the immunosuppressive effect of constitutive IL-10 production in the lung.

18F-Labeled Carboplatin Derivative for PET Imaging of Platinum Drug Distribution.

Increasing evidence indicates that reduced intracellular drug accumulation is the parameter most consistently associated with platinum drug resistance, emphasizing the need to directly measure the intratumor drug concentration. In the era of precision medicine and with the advent of powerful imaging and proteomics technologies, there is an opportunity to better understand drug resistance by exploiting these techniques to provide new knowledge on drug-target interactions. Here, we contribute to this endeavor by reporting on the development of an 18F-labeled carboplatin derivative (18F-FCP) that has the potential to image drug uptake and retention, including intratumoral distribution, by PET. Methods: Fluorinated carboplatin (19F-FCP) was synthesized using 19F-labeled 2-(5-fluoro-pentyl)-2-methyl malonic acid (19F-FPMA) as the labeling agent to coordinate with the cisplatin-aqua complex. It was then used to treat cell lines and compared with cisplatin and carboplatin at different concentrations. Manual radiosynthesis and characterization of 18F-FCP were performed using 18F-FPMA for coordination with the cisplatin-aqua complex. Automated radiosynthesis of 18F-FCP was optimized on the basis of manual synthesis procedures. The stability of 18F-FCP was verified using high-performance liquid chromatography. 18F-FCP was evaluated using ex vivo biodistribution and in vivo PET imaging in non-tumor-bearing animals as well as in KB-3-1 and COLO-205 tumor xenograft-bearing nude mice. Results: In vitro cytotoxicity studies demonstrated that 19F-FCP has an antitumor activity profile similar to that of the parent drug carboplatin. In vivo plasma and urine stability analysis showed intact 18F-FCP at 24 h after injection. PET imaging and biodistribution studies showed fast clearance from blood and major accumulation in the kidneys, indicating substantial renal clearance of 18F-FCP. Using 18F-FCP PET, we could image and identify the intratumor drug profile. Conclusion: Our results demonstrated that 19F-FCP, like carboplatin, retains antitumor activity in various cell lines. 18F-FCP could be a useful imaging tool for measuring the intratumor drug distribution. This strategy of using a new therapeutic carboplatin derivative to quantify and track platinum drugs in tumors using PET has the potential to translate into a clinically useful imaging tool for individual patients.

Highly stable intrinsically radiolabeled indium-111 quantum dots with multidentate zwitterionic surface coating: dual modality tool for biological imaging.

Here we describe a novel strategy to incorporate indium-111 into near infrared (NIR) emitting Cu-In-Se quantum dots (CIS-QDs) to synthesize intrinsically radiolabeled QDs (rQDs), as a quantitative tool for in vivo SPECT/fluorescence imaging. Multidentate zwitterionic polymer ligands were used to functionalize and improve the stability of CIS-rQDs and reduce nonspecific binding with plasma proteins/cell membrane. CIS-rQDs were taken up by colorectal adenocarcinoma (COLO-205) and human epidermoid carcinoma (KB-3-1) cells at low uptake rate (∼0.4%, 2 × 105 QDs per cell at 24 h) and reduced nonspecific interaction of zwitterionic CIS-rQDs with cells was observed by fluorescence microscopy. The cytotoxicity of CIS-rQDs was reduced due to the low toxic inorganic composition of QDs and multidentate zwitterionic surface coating. In 5 out of 6 nude mice bearing either COLO-205 or KB-3-1 tumor, both SPECT and fluorescence imaging demonstrated passive localization of CIS-rQDs in the tumor as early as 6 h post-injection. In these mice the passive accumulation of CIS-rQDs in the tumor, due to leaky vasculature, ranged from ∼0.3% ID per g to ∼4.6% ID per g at 48 h post-injection (from region of interest analysis of SPECT imaging). This intrinsic radio-labeling strategy provides a nanoparticle platform which incorporates imaging and potentially therapeutic radionuclides with retention of fluorescence intensity. It also provides complimentary quantitative data capabilities for both in vivo SPECT imaging and radiotracer ex vivo analysis.

Near-infrared imaging of adoptive immune cell therapy in breast cancer model using cell membrane labeling.

The overall objective of this study is to non-invasively image and assess tumor targeting and retention of directly labeled T-lymphocytes following their adoptive transfer in mice. T-lymphocytes obtained from draining lymph nodes of 4T1 (murine breast cancer cell) sensitized BALB/C mice were activated in-vitro with Bryostatin/Ionomycin for 18 hours, and were grown in the presence of Interleukin-2 for 6 days. T-lymphocytes were then directly labeled with 1,1-dioctadecyltetramethyl indotricarbocyanine Iodide (DiR), a lipophilic near infrared fluorescent dye that labels the cell membrane. Assays for viability, proliferation, and function of labeled T-lymphocytes showed that they were unaffected by DiR labeling. The DiR labeled cells were injected via tail vein in mice bearing 4T1 tumors in the flank. In some cases labeled 4T1 specific T-lymphocytes were injected a week before 4T1 tumor cell implantation. Multi-spectral in vivo fluorescence imaging was done to subtract the autofluorescence and isolate the near infrared signal carried by the T-lymphocytes. In recipient mice with established 4T1 tumors, labeled 4T1 specific T-lymphocytes showed marked tumor retention, which peaked 6 days post infusion and persisted at the tumor site for up to 3 weeks. When 4T1 tumor cells were implanted 1-week post-infusion of labeled T-lymphocytes, T-lymphocytes responded to the immunologic challenge and accumulated at the site of 4T1 cell implantation within two hours and the signal persisted for 2 more weeks. Tumor accumulation of labeled 4T1 specific T-lymphocytes was absent in mice bearing Meth A sarcoma tumors. When lysate of 4T1 specific labeled T-lymphocytes was injected into 4T1 tumor bearing mice the near infrared signal was not detected at the tumor site. In conclusion, our validated results confirm that the near infrared signal detected at the tumor site represents the DiR labeled 4T1 specific viable T-lymphocytes and their response to immunologic challenge can be imaged in vivo.

Functionalization of quantum dots with multidentate zwitterionic ligands: impact on cellular interactions and cytotoxicity.

Surface functionalization of nanoparticles is an important determinant of their interactions with biological compartments at the nano-bio interface. In this paper, a series of multidentate zwitterionic polymeric ligands were synthesized and used to functionalize the surface of quantum dots (QDs). The structure of polymer ligands was designed by changing the molar ratio of reactants and precursors used in the reaction. A three-component micro-emulsion method was developed to improve the efficiency of ligand exchange and avoid cross-linking reactions. Highly stable, compact and biocompatible zwitterionic QDs with different surface charge densities were obtained after ligand exchange. Variation of the surface charge density of QDs was verified by zeta potential measurements. The interaction of zwitterionic QDs with different cancer and normal cell lines (KB 3-1, COLO 205 and HEK 293) was surface charge density dependent. From cell viability studies, it was shown that higher surface charge density resulted in lower cytotoxicity of zwitterionic QDs when incubated with both cancer and normal cell lines. Furthermore, the feasibility of conjugating functionalized QDs (coated with amine zwitterionic polymer ligands) with a biomolecule was demonstrated. This was exemplified by the conjugation of amine zwitterionic QDs with a cRGD peptide, which showed improved interaction of cRGD-QDs with ανß3 integrin receptors expressed on U87MG glioblastoma tumor cells. Engineering the surface charge density and functionalization of nanoparticles, by multidentate zwitterionic ligands, provides a strategy to tune the surface properties of QDs, which impacts their cytotoxicity and cellular interaction at the nano-bio interface.

Intrinsically radiolabeled multifunctional cerium oxide nanoparticles for in vivo studies.

Cerium oxide nanoparticles (CONPs) have demonstrated protection properties against oxidation in various cells and tissues. The mechanism of this, however, is poorly understood. Monitoring the interaction of CONPs with biological compartments 'in situ' is crucial to understand their biochemical and physiological properties in vivo. In this paper, a multifunctional nanoparticle platform was obtained through an intrinsic radiolabeling strategy and extrinsic surface functionalization to combine dual imaging components (Single Photon Emission Computed Tomography/Optical Imaging, SPECT/OI) in one nanoparticle. The cell viability, cell uptake and overall in vivo biodistribution of CONPs were also manipulated through surface functionalization. The intrinsic radiolabeling strategy is demonstrated by incorporating radionuclides (141Ce, 111In or 65Zn) into CONPs and a radiolabeled CONP (rCONP) was coated with biocompatible polymers including Dextran T10 (DT10), poly(acrylic acid) (PAA), or functionalized DT10 (DT10-NH2, DT10-PEG and DT10-sulfobetaine). Fluorescent CONPs were obtained through conjugation of fluorescein isothiocyanate (FITC) with DT10-NH2 rCONP and used for cell imaging. The DT10 and DT10-NH2 rCONP did not show decreased viability up to 120 µg mL-1 whilst the PAA rCONP showed decreased viability beyond 40 µg mL-1. Variations in blood circulation and renal/hepatic clearance of rCONPs were demonstrated and were dependent on surface coating and the hydrodynamic size of nanoparticles. The ex vivo biodistribution results were reflected in SPECT imaging of 141Ce-rCONPs, showing accumulation in the liver and spleen of a living mouse over a one week period. The intrinsic radiolabeling and extrinsic surface modifications together determine the biophysical properties of CONPs and their potential applications for in vivo studies and biomedical imaging.

Inhibition of IL-10 receptor function in alveolar macrophages by Toll-like receptor agonists.

Despite an immunosuppressive lung environment, alveolar macrophages (AM) retain the capacity to respond to microorganisms. This report demonstrates that IL-10, constitutively produced by normal alveolar epithelium, stimulates signal transduction through the IL-10R on AM and that IL-10R function can be inhibited by stimulation of Toll-like receptor (TLR) on AM. IL-10 mRNA and protein were constitutively expressed in normal alveolar epithelium of mice, and IL-10R were constitutively expressed on normal murine AM. Stimulation of AM through TLR2, TLR4, or TLR9 was sufficient to inhibit IL-10R signal transduction, including phosphorylation and nuclear translocation of STAT3 transcription factor. Inhibition of IL-10R function by TLRs was not associated with a decrease in IL-10R expression, but did require expression of the myeloid differentiation factor 88 adaptor protein. Continuous exposure of macrophages to IL-10 caused sustained expression of the chemokine receptors CCR1 and CCR5. However, the addition of TLR ligands inhibited IL-10-induced expression of CCR1 and CCR5. Finally, exposure of macrophages to TLR ligands blocked the ability of IL-10 to inhibit the induction of TNF-alpha by C2-ceramide. These findings demonstrate a novel regulatory mechanism that may allow AM to overcome inhibitory effects of constitutive IL-10 in the lungs that may permit a more effective response to pulmonary infections.