Adenosine-related small molecules show utility of recall antigen assay to screen compounds for off-target effects on memory T cells.

Extracellular adenosine suppresses T cell immunity in the tumor microenvironment and in vitro treatment of memory T cells with adenosine can suppress antigen-mediated memory T cell expansion. We describe utilizing the recall antigen assay platform to screen small molecule drug off-target effects on memory T cell expansion/function using a dosing regimen based on adenosine treatment. As a proof of principle, we show low dose GS-5734, a monophosphoramidate prodrug of an adenosine analog, does not alter memory T cell recall at lower doses whereas toxicity observed at high dose favors antigen-specific memory T cell survival/proliferation over non-specific CD8+ T cells. Conversely, parent nucleoside GS-441524 at high dosage does not result in cellular toxicity and reduces antigen-specific T cell recall in most donors. Despite similar chemical structure, these drugs displayed opposing effects on memory T cell expansion and viability highlighting the sensitivity of this assay setup in screening compounds for off-target effects.

Enhanced Delivery of Plasmid DNA to Skeletal Muscle Cells using a DLC8-Binding Peptide and ASSLNIA-Modified PAMAM Dendrimer.

Skeletal muscle is ideally suited and highly desirable as a target for therapeutic gene delivery because of its abundance, high vascularization, and high levels of protein expression. However, efficient gene delivery to skeletal muscle remains a current challenge. Besides the major obstacle of cell-specific targeting, efficient intracellular trafficking, or the cytosolic transport of DNA to the nucleus, must be demonstrated. To overcome the challenge of cell-specific targeting, herein we develop a generation 5-polyamidoamine dendrimer (G5-PAMAM) functionalized with a skeletal muscle-targeted peptide, ASSLNIA (G5-SMTP). Specifically, to demonstrate the feasibility of our approach, we prepared a complex of our G5-SMTP dendrimer with a plasmid encoding firefly luciferase and investigated its delivery to skeletal muscle cells. Luciferase assays indicated a threefold increase in transfection efficiency of C2C12 murine skeletal muscle cells using G5-SMTP when compared with nontargeting nanocarriers using unmodified G5. To further improve the transfection yield, we employed a cationic dynein light chain 8 protein (DLC8)-binding peptide (DBP) containing an internal sequence known to bind to the DLC8 of the dynein motor protein complex. Complexation of DBP with our targeting nanocarrier, that is, G5-SMTP, and our luciferase plasmid cargo resulted in a functional nanocarrier that showed an additional sixfold increase in transfection efficiency compared with G5-SMTP transfection alone. To our knowledge, this is the first successful use of two different functional nanocarrier components that enable targeted skeletal muscle cell recognition and increased efficiency of intracellular trafficking to synergistically enhance gene delivery to skeletal muscle cells. This strategy of targeting and trafficking can also be universally applied to any cell/tissue type for which a recognition domain exists.

Non-small-cell lung cancer homing peptide-labeled dendrimers selectively transfect lung cancer cells.

AIM: Lung cancer gene therapies require reagents to selectively transfect lung tumors after systemic administration. MATERIALS & METHODS: We created a reagent called NSCLC-NP by attaching a peptide with binding affinity for lung cancer to polyamidoamine dendrimers. The positively charged dendrimers electrostatically bind negatively charged nucleic acids, inhibit endogenous nucleases and transfect cells targeted by the attached peptide. RESULTS: In vitro, NSCLC-NP complexed to DNA plasmids bound and transfected three human lung cancer cell lines producing protein expression of the plasmid's gene. In vivo, systemically administered NSCLC-NP selectively transfected lung cancer cells growing in RAG1KO mice. CONCLUSION: The capability of NSCLC-NP to selectively transfect lung cancer allows its future use as a vehicle to implement human lung cancer gene therapy strategies.

An enhanced bioluminescence-based Annexin V probe for apoptosis detection in vitro and in vivo.

The process of controlled cellular death known as apoptosis has an important central role not only in normal homeostatic maintenance of tissues, but also in numerous diseases such as cancer, neurodegenerative, autoimmune, and cardiovascular diseases. As a result, new technologies with the capability to selectively detect apoptotic cells represent a central focus of research for the study of these conditions. We have developed a new biosensor for the detection of apoptotic cells, incorporating the targeted selectivity for apoptotic cells from Annexin V with the sensitivity of bioluminescence signal generation from a serum-stable mutant of Renilla luciferase (RLuc8). Our data presents a complete characterization of the structural and biochemical properties of this new Annexin-Renilla fusion protein (ArFP) construct, as well as a validation of its ability to detect apoptosis in vitro. Moreover, this work represents the first report of a bioluminescent Annexin V apoptosis sensor utilized in vivo. With this new construct, we examine apoptosis within disease-relevant animal models of surgery-induced ischemia/reperfusion, corneal injury, and retinal cell death as a model of age-related macular degeneration. In each of these experiments, we demonstrate successful application of the ArFP construct for detection and bioluminescence imaging of apoptosis within each disease or treatment model. ArFP represents an important new tool in the continuously growing kit of technologies for apoptosis detection, and our results from both in vitro and in vivo experiments suggest a diverse range of potential clinically relevant applications including cancer therapeutic screening and efficacy analysis, atherosclerosis and cardiovascular disease detection, and the monitoring of any number of other conditions in which apoptosis has a central role.

4PD Functionalized Dendrimers: A Flexible Tool for In Vivo Gene Silencing of Tumor-Educated Myeloid Cells.

Myeloid cells play a key role in tumor progression and metastasis by providing nourishment and immune protection, as well as facilitating cancer invasion and seeding to distal sites. Although advances have been made in understanding the biology of these tumor-educated myeloid cells (TEMCs), their intrinsic plasticity challenges our further understanding of their biology. Indeed, in vitro experiments only mimic the in vivo setting, and current gene-knockout technologies do not allow the simultaneous, temporally controlled, and cell-specific silencing of multiple genes or pathways. In this article, we describe the 4PD nanoplatform, which allows the in vivo preferential transfection and in vivo tracking of TEMCs with the desired RNAs. This platform is based on the conjugation of CD124/IL-4Rα-targeting peptide with G5 PAMAM dendrimers as the loading surface and can convey therapeutic or experimental RNAs of interest. When injected i.v. in mice bearing CT26 colon carcinoma or B16 melanoma, the 4PD nanoparticles predominantly accumulate at the tumor site, transfecting intratumoral myeloid cells. The use of 4PD to deliver a combination of STAT3- and C/EBPß-specific short hairpin RNA or miR-142-3p confirmed the importance of these genes and microRNAs in TEMC biology and indicates that silencing of both genes is necessary to increase the efficacy of immune interventions. Thus, the 4PD nanoparticle can rapidly and cost effectively modulate and assess the in vivo function of microRNAs and mRNAs in TEMCs.

Red-Shifted Aequorin Variants Incorporating Non-Canonical Amino Acids: Applications in In Vivo Imaging.

The increased importance of in vivo diagnostics has posed new demands for imaging technologies. In that regard, there is a need for imaging molecules capable of expanding the applications of current state-of-the-art imaging in vivo diagnostics. To that end, there is a desire for new reporter molecules capable of providing strong signals, are non-toxic, and can be tailored to diagnose or monitor the progression of a number of diseases. Aequorin is a non-toxic photoprotein that can be used as a sensitive marker for bioluminescence in vivo imaging. The sensitivity of aequorin is due to the fact that bioluminescence is a rare phenomenon in nature and, therefore, it does not suffer from autofluorescence, which contributes to background emission. Emission of bioluminescence in the blue-region of the spectrum by aequorin only occurs when calcium, and its luciferin coelenterazine, are bound to the protein and trigger a biochemical reaction that results in light generation. It is this reaction that endows aequorin with unique characteristics, making it ideally suited for a number of applications in bioanalysis and imaging. Herein we report the site-specific incorporation of non-canonical or non-natural amino acids and several coelenterazine analogues, resulting in a catalog of 72 cysteine-free, aequorin variants which expand the potential applications of these photoproteins by providing several red-shifted mutants better suited to use in vivo. In vivo studies in mouse models using the transparent tissue of the eye confirmed the activity of the aequorin variants incorporating L-4-iodophehylalanine and L-4-methoxyphenylalanine after injection into the eye and topical addition of coelenterazine. The signal also remained localized within the eye. This is the first time that aequorin variants incorporating non-canonical amino acids have shown to be active in vivo and useful as reporters in bioluminescence imaging.

Directing and Potentiating Stem Cell-Mediated Angiogenesis and Tissue Repair by Cell Surface E-Selectin Coating.

Stem cell therapy has emerged as a promising approach for treatment of a number of diseases, including delayed and non-healing wounds. However, targeted systemic delivery of therapeutic cells to the dysfunctional tissues remains one formidable challenge. Herein, we present a targeted nanocarrier-mediated cell delivery method by coating the surface of the cell to be delivered with dendrimer nanocarriers modified with adhesion molecules. Infused nanocarrier-coated cells reach to destination via recognition and association with the counterpart adhesion molecules highly or selectively expressed on the activated endothelium in diseased tissues. Once anchored on the activated endothelium, nanocarriers-coated transporting cells undergo transendothelial migration, extravasation and homing to the targeted tissues to execute their therapeutic role. We now demonstrate feasibility, efficacy and safety of our targeted nanocarrier for delivery of bone marrow cells (BMC) to cutaneous wound tissues and grafted corneas and its advantages over conventional BMC transplantation in mouse models for wound healing and neovascularization. This versatile platform is suited for targeted systemic delivery of virtually any type of therapeutic cell.

Anti-GBM disease and ANCA during dengue infection.

Anti-glomerular basement membrane (GBM) disease is a severe inflammatory renal disorder due to pathogenic autoantibodies directed mainly against the α3 chain of type IV collagen. In ~1/4 of patients with anti-GBM disease, antineutrophil cytoplasmic antibodies (ANCA) predominantly with myeloperoxidase (MPO) specificity can be detected. Although the inciting stimuli leading to the development of an immune response against the type IV collagen and neutrophils are unknown, evidence indicates that both genetic and environmental factors play a role. Of note, molecular mimicry between self-antigens and nonself-antigens such as antigenic determinants of microorganisms has been implicated in the pathogenesis of anti-GBM disease and ANCA-associated vasculitis. A mosquito-borne viral illness highly prevalent in the tropics and subtropics, dengue can be complicated by acute renal failure, proteinuria, hematuria and glomerulonephritis. We present a 66-year-old woman who was diagnosed with dengue infection and rapidly progressive glomerulonephritis during an outbreak of dengue in Honduras in the summer of 2013. Renal biopsy revealed severe crescentic glomerulonephritis. Immunofluorescence examination demonstrated strong linear IgG deposition along glomerular capillary walls. Serologic tests demonstrated antibodies against GBM, MPO and platelet glycoproteins. The patient was diagnosed with anti-GBM disease associated with p-ANCA with MPO specificity. Despite heavy immunosuppression and plasmapheresis, IgG titers against dengue virus continued to rise confirming the diagnosis of acute dengue infection. We present the first reported case of anti-GBM disease associated with p-ANCA with MPO specificity during dengue infection. This report calls for a heightened awareness of autoimmunity leading to crescentic glomerulonephritis in patients with dengue infection.

A targeted and adjuvanted nanocarrier lowers the effective dose of liposomal amphotericin B and enhances adaptive immunity in murine cutaneous leishmaniasis.

BACKGROUND: Amphotericin B (AmB), the most effective drug against leishmaniasis, has serious toxicity. As Leishmania species are obligate intracellular parasites of antigen presenting cells (APC), an immunopotentiating APC-specific AmB nanocarrier would be ideally suited to reduce the drug dosage and regimen requirements in leishmaniasis treatment. Here, we report a nanocarrier that results in effective treatment shortening of cutaneous leishmaniasis in a mouse model, while also enhancing L. major specific T-cell immune responses in the infected host. METHODS: We used a Pan-DR-binding epitope (PADRE)-derivatized-dendrimer (PDD), complexed with liposomal amphotericin B (LAmB) in an L. major mouse model and analyzed the therapeutic efficacy of low-dose PDD/LAmB vs full dose LAmB. RESULTS: PDD was shown to escort LAmB to APCs in vivo, enhanced the drug efficacy by 83% and drug APC targeting by 10-fold and significantly reduced parasite burden and toxicity. Fortuitously, the PDD immunopotentiating effect significantly enhanced parasite-specific T-cell responses in immunocompetent infected mice. CONCLUSIONS: PDD reduced the effective dose and toxicity of LAmB and resulted in elicitation of strong parasite specific T-cell responses. A reduced effective therapeutic dose was achieved by selective LAmB delivery to APC, bypassing bystander cells, reducing toxicity and inducing antiparasite immunity.

Peptide-conjugated PAMAM dendrimer as a universal DNA vaccine platform to target antigen-presenting cells.

DNA-based vaccines hold promise to outperform conventional antigen-based vaccines by virtue of many unique features. However, DNA vaccines have thus far fallen short of expectations, due in part to poor targeting of professional antigen-presenting cells (APC) and low immunogenicity. In this study, we describe a new platform for effective and selective delivery of DNA to APCs in vivo that offers intrinsic immune-enhancing characteristics. This platform is based on conjugation of fifth generation polyamidoamine (G5-PAMAM) dendrimers, a DNA-loading surface, with MHC class II-targeting peptides that can selectively deliver these dendrimers to APCs under conditions that enhance their immune stimulatory potency. DNA conjugated with this platform efficiently transfected murine and human APCs in vitro. Subcutaneous administration of DNA-peptide-dendrimer complexes in vivo preferentially transfected dendritic cells (DC) in the draining lymph nodes, promoted generation of high affinity T cells, and elicited rejection of established tumors. Taken together, our findings show how PAMAM dendrimer complexes can be used for high transfection efficiency and effective targeting of APCs in vivo, conferring properties essential to generate effective DNA vaccines.