Oncolysate-loaded Escherichia coli bacterial ghosts enhance the stimulatory capacity of human dendritic cells.

The natural adjuvant properties of bacterial ghosts (BGs) lie within the presence of intact pathogen-associated molecular patterns on their surface. BGs can improve the direct delivery, natural processing and presentation of target antigens within dendritic cells (DCs). Moreover, sensitization of human DCs by cancer cell lysate (oncolysate)-loaded BGs in the presence of IFN-α and GM-CSF enhanced DC maturation as indicated by an increased expression of maturation markers and co-stimulatory molecules, higher production of IL-12p70 and stimulation of significantly increased proliferation of both autologous CD4+ and CD8+ T cells compared to DCs matured in the presence of purified lipopolysaccharide. The induced T cells efficiently recognized oncolysate-derived tumor-associated antigens expressed by cancer cells used for the production of oncolysate. Our optimized one-step simultaneous antigen delivery and DC maturation-inducing method emerges as a promising tool for the development and implementation of next-generation cellular cancer immunotherapies.

Long circulating liposomal platform utilizing hydrophilic polymer-based surface modification: preparation, characterisation, and biological evaluation.

Liposomes are one of the most important drug delivery vectors, nowadays used in clinics. In general, polyethylene glycol (PEG) is used to ensure the stealth properties of the liposomes. Here, we have employed hydrophilic, biocompatible and highly non-fouling N-(2-hydroxypropyl) methacrylamide (HPMA)-based copolymers containing hydrophobic cholesterol anchors for the surface modification of liposomes, which were prepared by the method of lipid film hydration and extrusion through 100 nm polycarbonate filters. Efficient surface modification of liposomes was confirmed by transmission electron microscopy, atomic force microscopy, and gradient ultracentrifugation. The ability of long-term circulation in the vascular bed was demonstrated in rabbits after i.v. application of fluorescently labelled liposomes. Compared to PEGylated liposomes, HPMA-based copolymer-modified liposomes did not induce specific antibody formation and did not activate murine and human complement. Compared with PEGylated liposomes, HPMA-based copolymer-modified liposomes showed a better long-circulating effect after repeated administration. HPMA-based copolymer-modified liposomes thus represent suitable new candidates for a generation of safer and improved liposomal drug delivery platforms.

Overexpression of CD44v8-10 in Colon Polyps-A Possible Key to Early Diagnosis.

Background and aims: The majority of colorectal cancers arise from detectable adenomatous or serrated lesions. Here we demonstrate how deregulated alternative splicing of CD44 gene in diseased colon mucosa results in downregulation of standard isoform of CD44 gene (CD44s) and upregulation of variant isoform CD44v8-10. Our aim is to show that upregulation of CD44v8-10 isoform is a possible marker of precancerous lesion in human colon. Methods: We analysed pairs of fresh biopsy specimen of large intestine in a cohort of 50 patients. We studied and compared alternative splicing profile of CD44 gene in colon polyps and adjoined healthy colon mucosa. We performed end-point and qRT PCR, western blotting, IHC staining and flow cytometry analyses. Results: We detected more than five-fold overexpression of CD44v8-10 isoform and almost twenty-fold downregulation of standard isoform CD44s in colon polyps compared to adjoined healthy tissue with p = 0.018 and p < 0.001 in a cohort of 50 patients. Our results also show that aberrant splicing of CD44 occurs in both biologically distinct subtypes of colorectal adenoma possibly in ESRP-1 specific manner. Conclusion: 92% of the colon polyp positive patients overexpressed CD44v8-10 isoform in their colon polyps while only 36% of them had positive fecal occult blood test which is currently a standard non-invasive screening technique. Impact: We believe that our results are important for further steps leading to application of CD44v8-10 isoform as a biomarker of colorectal precancerosis in non-invasive detection. Early detection of colon precancerosis means successful prevention of colorectal carcinoma.

Carbon-Based Nanomaterials Increase Reactivity of Primary Monocytes towards Various Bacteria and Modulate Their Differentiation into Macrophages.

The evaluation of carbon-based nanomaterials' (C-BNMs') interactions with the immune system, notably their ability to cause inflammation, is a critical step in C-BNM health risk assessment. Particular attention should be given to those C-BNMs that do not cause direct cytotoxicity or inflammation on their own. However, the intracellular presence of these non-biodegradable nanomaterials could dysregulate additional cell functions. This is even more crucial in the case of phagocytes, which are the main mediators of defensive inflammation towards pathogens. Hence, our study was focused on multi-walled carbon nanotubes (MWCNTs) and two different types of graphene platelets (GPs) and whether their intracellular presence modulates a proinflammatory response from human primary monocytes towards common pathogens. Firstly, we confirmed that all tested C-BNMs caused neither direct cytotoxicity nor the release of tumour necrosis factor α (TNF-α), interleukin (IL)-6 or IL-10. However, such pre-exposed monocytes showed increased responsiveness to additional bacterial stimuli. In response to several types of bacteria, monocytes pre-treated with GP1 produced a significantly higher quantity of TNF-α, IL-6 and IL-10. Monocytes pre-treated with MWCNTs produced increased levels of IL-10. All the tested C-BNMs enhanced monocyte phagocytosis and accelerated their differentiation towards macrophages. This study confirms the immunomodulatory potential of C-BNMs.

Myomedin scaffold variants targeted to 10E8 HIV-1 broadly neutralizing antibody mimic gp41 epitope and elicit HIV-1 virus-neutralizing sera in mice.

One of the proposed strategies for the development of a more efficient HIV-1 vaccine is based on the identification of proteins binding to a paratope of chosen broadly neutralizing antibody (bNAb) that will mimic cognate HIV-1 Env (glyco)protein epitope and could be used as potent immunogens for induction of protective virus-neutralizing antibodies in the immunized individuals. To verify this "non-cognate ligand" concept, we developed a highly complex combinatorial library designed on a scaffold of human myomesin-1 protein domain and selected proteins called Myomedins specifically binding to variable regions of HIV-1 broadly neutralizing antibody 10E8. Immunization of mice with these Myomedin variants elicited the production of HIV-1 Env-specific antibodies. Hyperimmune sera bound to Env pseudotyped viruses and weakly/moderately neutralized 54% of tested clade A, B, C, and AE pseudotyped viruses variants in vitro. These results demonstrate that Myomedin variants have the potential to mimic Env epitopes and could be used as potential HIV-1 vaccine components.

Gadolinium labelled nanoliposomes as the platform for MRI theranostics: in vitro safety study in liver cells and macrophages.

Gadolinium (Gd)-based contrast agents are extensively used for magnetic resonance imaging (MRI). Liposomes are potential nanocarrier-based biocompatible platforms for development of new generations of MRI diagnostics. Liposomes with Gd-complexes (Gd-lip) co-encapsulated with thrombolytic agents can serve both for imaging and treatment of various pathological states including stroke. In this study, we evaluated nanosafety of Gd-lip containing PE-DTPA chelating Gd+3 prepared by lipid film hydration method. We detected no cytotoxicity of Gd-lip in human liver cells including cancer HepG2, progenitor (non-differentiated) HepaRG, and differentiated HepaRG cells. Furthermore, no potential side effects of Gd-lip were found using a complex system including general biomarkers of toxicity, such as induction of early response genes, oxidative, heat shock and endoplasmic reticulum stress, DNA damage responses, induction of xenobiotic metabolizing enzymes, and changes in sphingolipid metabolism in differentiated HepaRG. Moreover, Gd-lip did not show pro-inflammatory effects, as assessed in an assay based on activation of inflammasome NLRP3 in a model of human macrophages, and release of eicosanoids from HepaRG cells. In conclusion, this in vitro study indicates potential in vivo safety of Gd-lip with respect to hepatotoxicity and immunopathology caused by inflammation.

Proinflammatory Effect of Carbon-Based Nanomaterials: In Vitro Study on Stimulation of Inflammasome NLRP3 via Destabilisation of Lysosomes.

Carbon-based nanomaterials (C-BNM) have recently attracted an increased attention as the materials with potential applications in industry and medicine. Bioresistance and proinflammatory potential of C-BNM is the main obstacle for their medicinal application which was documented in vivo and in vitro. However, there are still limited data especially on graphene derivatives such as graphene platelets (GP). In this work, we compared multi-walled carbon nanotubes (MWCNT) and two different types of pristine GP in their potential to activate inflammasome NLRP3 (The nod-like receptor family pyrin domain containing 3) in vitro. Our study is focused on exposure of THP-1/THP1-null cells and peripheral blood monocytes to C-BNM as representative models of canonical and alternative pathways, respectively. Although all nanomaterials were extensively accumulated in the cytoplasm, increasing doses of all C-BNM did not lead to cell death. We observed direct activation of NLRP3 via destabilization of lysosomes and release of cathepsin B into cytoplasm only in the case of MWCNTs. Direct activation of NLRP3 by both GP was statistically insignificant but could be induced by synergic action with muramyl dipeptide (MDP), as a representative molecule of the family of pathogen-associated molecular patterns (PAMPs). This study demonstrates a possible proinflammatory potential of GP and MWCNT acting through NLRP3 activation.

N-Oxy lipid-based click chemistry for orthogonal coupling of mannan onto nanoliposomes prepared by microfluidic mixing: Synthesis of lipids, characterisation of mannan-coated nanoliposomes and in vitro stimulation of dendritic cells.

New synthetic aminooxy lipid was designed and synthesized as a building block for the formulation of functionalised nanoliposomes (presenting onto the outer surface of aminooxy groups) by microfluidic mixing. Orthogonal binding of cellular mannan (Candida glabrata (CCY 26-20-1) onto the outer surface of functionalised nanoliposomes was modified by orthogonal binding of reducing termini of mannans to oxime lipids via a click chemistry reaction based on aminooxy coupling (oxime ligation). The aminooxy lipid was proved as a suitable active component for preparation of functionalised nanoliposomes by the microfluidic mixing method performed with the instrument NanoAssemblr™. This "on-chip technology" can be easily scaled-up. The structure of mannan-liposomes was visualized by transmission and scanning electron microscopy, including immunogold staining of recombinant mannan receptor bound onto mannosylated-liposomes. The observed structures are in a good correlation with data obtained by DLS, NTA, and TPRS methods. In vitro experiments on human and mouse dendritic cells demonstrate selective internalisation of fluorochrome-labelled mannan-liposomes and their ability to stimulate DC comparable to lipopolysaccharide. We describe a potentially new drug delivery platform for mannan receptor-targeted antimicrobial drugs as well as for immunotherapeutics. Furthermore, the platform based on mannans bound orthogonally onto the surface of nanoliposomes represents a self-adjuvanted carrier for construction of liposome-based recombinant vaccines for both systemic and mucosal routes of administration.

Multi-layered nanofibrous mucoadhesive films for buccal and sublingual administration of drug-delivery and vaccination nanoparticles - important step towards effective mucosal vaccines.

Nanofibre-based mucoadhesive films were invented for oromucosal administration of nanocarriers used for delivery of drugs and vaccines. The mucoadhesive film consists of an electrospun nanofibrous reservoir layer, a mucoadhesive film layer and a protective backing layer. The mucoadhesive layer is responsible for tight adhesion of the whole system to the oral mucosa after application. The electrospun nanofibrous reservoir layer is intended to act as a reservoir for polymeric and lipid-based nanoparticles, liposomes, virosomes, virus-like particles, dendrimers and the like, plus macromolecular drugs, antigens and/or allergens. The extremely large surface area of nanofibrous reservoir layers allows high levels of nanoparticle loading. Nanoparticles can either be reversibly adsorbed to the surface of nanofibres or they can be deposited in the pores between the nanofibres. After mucosal application, nanofibrous reservoir layers are intended to promote prolonged release of nanoparticles into the submucosal tissue. Reversible adsorption of model nanoparticles as well as sufficient mucoadhesive properties were demonstrated. This novel system appears appropriate for the use in oral mucosa, especially for sublingual and buccal tissues. To prove this concept, trans-/intramucosal and lymph-node delivery of PLGA-PEG nanoparticles was demonstrated in a porcine model. This system can mainly be used for sublingual immunization and the development of "printed vaccine technology".

Nonpyrogenic Molecular Adjuvants Based on norAbu-Muramyldipeptide and norAbu-Glucosaminyl Muramyldipeptide: Synthesis, Molecular Mechanisms of Action, and Biological Activities in Vitro and in Vivo.

Fatty acyl analogues of muramyldipeptide (MDP) (abbreviated N-L18 norAbuGMDP, N-B30 norAbuGMDP, norAbuMDP-Lys(L18), norAbuMDP-Lys(B30), norAbuGMDP-Lys(L18), norAbuGMDP-Lys(B30), B30 norAbuMDP, L18 norAbuMDP) are designed and synthesized comprising the normuramyl-l-α-aminobutanoyl (norAbu) structural moiety. All new analogues show depressed pyrogenicity in both free (micellar) state and in liposomal formulations when tested in rabbits in vivo (sc and iv application). New analogues are also shown to be selective activators of NOD2 and NLRP3 (inflammasome) in vitro but not NOD1. Potencies of NOD2 and NLRP3 stimulation are found comparable with free MDP and other positive controls. Analogues are also demonstrated to be effective in stimulating cellular proliferation when the sera from mice are injected sc with individual liposome-loaded analogues, causing proliferation of bone marrow-derived GM-progenitors cells. Importantly, vaccination nanoparticles prepared from metallochelation liposomes, His-tagged antigen rOspA from Borrelia burgdorferi, and lipophilic analogue norAbuMDP-Lys(B30) as adjuvant, are shown to provoke OspA-specific antibody responses with a strong Th1-bias (dominance of IgG2a response). In contrast, the adjuvant effects of Alum or parent MDP show a strong Th2-bias (dominance of IgG1 response).

Antiviral activities of 2,6-diaminopurine-based acyclic nucleoside phosphonates against herpesviruses: In vitro study results with pseudorabies virus (PrV, SuHV-1).

Pseudorabies virus (PrV), a causative agent of Aujeszky's disease, is deadly to most mammals with the exception of higher primates and men. This disease causes serious economic loses among farm animals, especially pigs, yet many European countries are today claimed to be Aujeszky's disease free because of the discovery of an efficient vaccination for pigs. In reality, the virus is still present in wild boar. Current vaccines are neither suitable for dogs nor are there anti-PrV drugs approved for veterinary use. Therefore, the disease still represents a high threat, particularly for expensive hunting dogs that can come into close contact with infected boars. Here we report on the anti-PrV activities of a series of synthetic diaminopurine-based acyclic nucleoside phosphonate (DAP-ANP) analogues. Initially, all synthetic DAP-ANPs under investigation are shown to exhibit minimal cytotoxicity by MTT and XTT tests (1-100µM range). Thereafter in vitro infection models are established using PrV virus SuHV-1, optimized on PK-15 and RK-13 cell lines. Out of the six DAP-ANP analogues tested, analogue VI functionalized with a cyclopropyl group on the 6-amino position of the purine ring proves the most effective antiviral DAP-ANP analogue against PrV infection, aided by sufficient hydrophobic character to enhance bioavailability to its cellular target viral DNA-polymerase. Four other DAP-ANP analogues with functional groups introduced to the C2'position are shown ineffective against PrV infection, even with favourable hydrophobic properties. Cidofovir(®), a drug approved against various herpesvirus infections, is found to exert only low activity against PrV in these same in vitro models.

Liposomal nanocarriers for plasminogen activators.

Several plasminogen activators (PAs) have been found effective in treating different thromboembolic diseases. However, administration of conventional thrombolytic therapy is limited by a low efficacy of present formulations of PAs. Conventional treatments using these therapeutic proteins are associated with several limitations including rapid inactivation and clearance, short half-life, bleeding complications or non-specific tissue targeting. Liposome-based formulations of PAs such as streptokinase, tissue-plasminogen activator and urokinase have been developed to improve the therapeutic efficacy of these proteins. Resulting liposomal formulations were found to preserve the original activity of PAs, promote their selective delivery and improve thrombus targeting. Therapeutic potential of these liposome-based PAs has been demonstrated successfully in various pre-clinical models in vivo. Reductions in unwanted side effects (e.g., hemorrhage or immunogenicity) as well as enhancements of efficacy and safety were achieved in comparison to currently existing treatment options based on conventional formulations of PAs. This review summarizes present achievements in: (i) preparation of liposome-based formulations of various PAs, (ii) development of PEGylated and targeted liposomal PAs, (iii) physico-chemical characterization of these developed systems, and (iv) testing of their thrombolytic efficacy. We also look to the future and the imminent arrival of theranostic liposomal formulations to move this field forward.

The Position of His-Tag in Recombinant OspC and Application of Various Adjuvants Affects the Intensity and Quality of Specific Antibody Response after Immunization of Experimental Mice.

Lyme disease, Borrelia burgdorferi-caused infection, if not recognized and appropriately treated by antibiotics, may lead to chronic complications, thus stressing the need for protective vaccine development. The immune protection is mediated by phagocytic cells and by Borrelia-specific complement-activating antibodies, associated with the Th1 immune response. Surface antigen OspC is involved in Borrelia spreading through the host body. Previously we reported that recombinant histidine tagged (His-tag) OspC (rOspC) could be attached onto liposome surfaces by metallochelation. Here we report that levels of OspC-specific antibodies vary substantially depending upon whether rOspC possesses an N' or C' terminal His-tag. This is the case in mice immunized: (a) with rOspC proteoliposomes containing adjuvants MPLA or non-pyrogenic MDP analogue MT06; (b) with free rOspC and Montanide PET GEL A; (c) with free rOspC and alum; or (d) with adjuvant-free rOspC. Stronger responses are noted with all N'-terminal His-tag rOspC formulations. OspC-specific Th1-type antibodies predominate post-immunization with rOspC proteoliposomes formulated with MPLA or MT06 adjuvants. Further analyses confirmed that the structural features of soluble N' and C' terminal His-tag rOspC and respective rOspC proteoliposomes are similar including their thermal stabilities at physiological temperatures. On the other hand, a change in the position of the rOspC His-tag from N' to C' terminal appears to affect substantially the immunogenicity of rOspC arguably due to steric hindrance of OspC epitopes by the C' terminal His-tag itself and not due to differences in overall conformations induced by changes in the His-tag position in rOspC variants.

Liposomal delivery systems for anti-cancer analogues of vitamin E.

Pro-apoptotic analogues of vitamin E (VE) exert selective anti-cancer effect on various animal cancer models. Neither suitable formulation of α-tocopheryl succinate (α-TOS), representative semi-synthetic VE analogue ester, nor suitable formulations of the other VE analogues for clinical application have been reported yet. The major factor limiting the use of VE analogues is their low solubility in aqueous solvents. Due to the hydrophobic character of VE analogues, liposomes are predetermined as suitable delivery system. Liposomal formulation prevents undesirable side effects of the drug, enhances the drug biocompatibility, and improves the drug therapeutic index. Liposomal formulations of VE analogues especially of α-TOS and α-tocopheryl ether linked acetic acid (α-TEA) have been developed. The anti-cancer effect of these liposomal VE analogues has been successfully demonstrated in pre-clinical models in vivo. Present achievements in: (i) preparation of liposomal formulations of VE analogues, (ii) physico-chemical characterization of these developed systems and (iii) testing of their biological activity such as induction of apoptosis and evaluation of anti-cancer effect are discussed in this review.

Antiviral effect of HPMPC (Cidofovir®), entrapped in cationic liposomes: in vitro study on MDBK cell and BHV-1 virus.

We designed and synthesised a series of new cationic lipids based on spermine linked to various hydrophobic anchors. These lipids could be potentially useful for the preparation of stable cationic liposomes intended for the construction of drug targeting systems applicable in the field of anticancer/antiviral therapy, vaccine carriers, and vectors for the gene therapy. Low in vitro toxicity was found for these compounds, especially for LD1, in several cell lines. The delivery of both a fluorescence marker (calcein) and antiviral drugs into cells has been achieved owing to a large extent of internalization of cationic liposomes (labelled by Lyssamine-Rhodamine PE or fluorescein-PE) as demonstrated by fluorescent microscopy and quantified by flow cytometry. The bovine herpes virus type 1 (BHV-1) virus infection in vitro model using MDBK cells was employed to study the effect of the established antiviral drug HPMPC (Cidofovir®) developed by Prof. A. Holý. Inhibition of BHV-1 virus replication was studied by quantitative RT-PCR and confirmed by both Hoffman modulation contrast microscopy and transmission electron microscopy. We found that in vitro antiviral activity of HPMPC was significantly improved by formulation in cationic liposomes, which decreased the viral replication by about 2 orders of magnitude.

Enhancement of immune response towards non-lipidized Borrelia burgdorferi recombinant OspC antigen by binding onto the surface of metallochelating nanoliposomes with entrapped lipophilic derivatives of norAbuMDP.

Lyme disease caused by spirochete Borrelia burgdorferi sensu lato, is a tick-born illness. If the infection is not eliminated by the host immune system and/or antibiotics, it may further disseminate and cause severe chronic complications. The immune response to Borrelia is mediated by phagocytic cells and by Borrelia-specific complement-activating antibodies associated with Th1 cell activation. A new experimental vaccine was constructed using non-lipidized form of recombinant B. burgdorferi s.s. OspC protein was anchored by metallochelating bond onto the surface of nanoliposomes containing novel nonpyrogenic lipophilized norAbuMDP analogues denoted MT05 and MT06. After i.d. immunization, the experimental vaccines surpassed Alum with respect to OspC-specific titers of IgG2a, IgG2b isotypes when MT06 was used and IgG3, IgM isotypes when MT05 was used. Both adjuvants exerted a high adjuvant effect comparable or better than MDP and proved themselves as nonpyrogenic.

Metallochelating liposomes with associated lipophilised norAbuMDP as biocompatible platform for construction of vaccines with recombinant His-tagged antigens: preparation, structural study and immune response towards rHsp90.

Hsp90-CA is present in cell wall of Candida pseudohyphae or hyphae-typical pathogenic morphotype for both systemic and mucosal Candida infections. Heat shock protein from Candida albicans (hsp90-CA) is an important target for protective antibodies during disseminated candidiasis of experimental mice and human. His-tagged protein rHsp90 was prepared and used as the antigen for preparation of experimental recombinant liposomal vaccine. Nickel-chelating liposomes (the size around 100nm, PDI≤0.1) were prepared from the mixture of egg phosphatidyl choline and nickel-chelating lipid DOGS-NTA-Ni (molar ratio 95:5%) by hydration of lipid film and extrusion methods. New non-pyrogenic hydrophobised derivative of MDP (C18-O-6-norAbuMDP) was incorporated into liposomes as adjuvans. rHsp90 was attached onto the surface of metallochelating liposomes by metallochelating bond and the structure of these proteoliposomes was studied by dynamic light scattering, AF microscopy, TEM and GPC. The liposomes with surface-exposed C18-O-6-norAbuMDP were well recognised and phagocyted by human dendritic cells in vitro. In vivo the immune response towards this experimental vaccine applied in mice (i.d.) demonstrated both TH1 and TH2 response comparable to FCA, but without any side effects. Metallochelating liposomes with lipophilic derivatives of muramyl dipeptide represent a new biocompatible platform for construction of experimental recombinant vaccines and drug-targeting systems.

Liposomes with high encapsulation capacity for paclitaxel: Preparation, characterisation and in vivo anticancer effect.

Paclitaxel (PTX) is approved for the treatment of ovarian and breast cancer. The commercially available preparation of PTX, Cremophor EL(R) is associated with hypersensitivity reactions in spite of a suitable premedication. In general, the developed liposomal PTX formulations are troubled with low PTX encapsulation capacity (maximal content, 3 mol%) and accompanied by PTX crystallisation. The application of "pocket-forming" lipids significantly increased the encapsulation capacity of PTX in the liposomes up to 10 mol%. Stable lyophilised preparation of PTX (7 mol%) encapsulated in the liposomes composed of SOPC/POPG/MOPC (molar ratio, 60:20:20) doped with 5 mol% vitamin E had the size distribution of 180-190 nm (PDI, 0.1) with zeta-potential of -31 mV. Sucrose was found to be a suitable cryoprotectant at the lipid:sugar molar ratios of 1:5-1:10. This liposomal formulation did not show any evidence of toxicity in C57BL/6 mice treated with the highest doses of PTX (100 mg/kg administered as a single dose and 150 mg/kg as a cumulative dose applied in three equivalent doses in 48-h intervals). A dose-dependent anticancer effect was found in both hollow fibre implants and syngenic B16F10 melanoma mouse tumour models.