Biophysical characterization of the recombinant chitinase chi18-5 with potential biotechnological interest.

Chitinase chi18-5 is an enzyme able to hydrolyze chitin and chitosan producing chitooligosaccharides (COS) of potential technological interest. chi18-5 is produced naturally by the fungus Trichoderma atroviride. It belongs to the glycosyl hydrolase (GH) family 18 of the Carbohydrate Active Enzyme (CAZy) database and it has 83% identity compared to the well-characterized chi42 of Trichoderma harzianum. Several efforts have been made to characterize the biochemical activity of the enzyme and its structure. Here, we studied the biophysical properties of recombinant chi18-5. In order to gain insight into its structure and stability, we studied thermal denaturation by Circular Dichroism (CD), Intrinsic Fluorescence (FL), and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FT-IR) at several pH between 3 and 8. We observed that the conformation of chi18-5 changes near its pI, and the transitions as a function of the temperature involved an increment in ß-sheet secondary structure at the expenses of ⍺-helix. We also performed amide hydrogen exchange dynamics in selected conditions. At pH ≤ 6, the proportion of fast exchanging residues are larger than at pH ≥ 6. Our results suggest that at pH below pI, chi18-5 is in a less compact structure which may have influence in the interaction with substrate and enzyme activity. KEY POINTS: • Characterization of enzyme behavior is critical for their wide applications • We produced and characterized biophysically a chitinase as a function of pH • The pH of optimum activity correlates with a less compact structure of chi18-5.

Dissolution properties, solid-state transformation and polymorphic crystallization: progesterone case study.

Progesterone is a natural steroid hormone and a poor soluble drug which presents two polymorphs (forms 1 and 2). Different methods to obtain form 2 were tested and a complete solid-state characterization of both polymorphs (forms 1 and 2) was conducted. X-ray powder diffraction, hot stage microscopy, Fourier transform infrared, dispersive Raman, (13)C solid-state nuclear magnetic resonance spectroscopy, thermal analysis, scanning electron microscopy techniques and intrinsic dissolution rates (IDR) were applied to investigate physical-chemical and dissolution properties of these two polymorphs. Form 2 was obtained from diluted solutions and from melting after cooling at room temperature. Form 1 was obtained from concentrated solutions and, a mixture of both polymorphs was crystallized from intermediate solutions. The crystal habit was not a distinctive characteristic of each polymorph. The effect of mechanical stress was evaluated in the metastable polymorph (form 2). We observed that grinding form 2 produced seeds of form 1 that induced the transformation of form 2 into form 1 at high temperature. The polymorphic quantification from XRD patterns of ground samples were carried out by the Rietveld method. After grinding and at room temperature conditions (∼25 °C), it was observed the transformation of 17% of form 2 into form 1 in 10 days.

Limitations of Limulus amebocyte lysate test for endotoxin control in raw materials for liposomal nanoformulations.

Aim: To evaluate the applicability of Limulus amebocyte lysate (LAL) assay for endotoxin determination in lipid compounding liposomal nanoformulations.Materials & methods: Spiked cholesterol, hydrogenated soy phosphatidylcholine and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG 2000) samples with endotoxins, simulating contaminated samples or in-process contamination were analyzed by chromogenic LAL assay.Results: Recovery of spiked endotoxins was achieved from DSPE-PEG 2000 suspended in water, whereas recovery was not achieved from spiked cholesterol and hydrogenated soy phosphatidylcholine suspended in methanol, and from multilamellar vesicles. Conclusion: Endotoxins, when in contact with organic solvents, no longer react in the LAL assay as they do in aqueous media. This indicates limitations of the LAL assay for endotoxin control in raw materials for liposomal nanoformulations.

[Box: see text].

Role of chitosan in intestinal integrity: TLR4 and IFNAR signaling in the induction of E-cadherin and CD103 in mice.

Chitin and its derivative chitosan (Q) are abundant structural elements in nature. Q has modulatory and anti-inflammatory effects and also regulates the expression of adhesion molecules. The interaction between cells expressing the αEß7 integrin and E-cadherin facilitates tolerogenic signal transmission and localization of lymphocytes at the frontline for interaction with luminal antigens. In this study we evaluated the ability of orally administered Q to stimulate E-cadherin and CD103 expression in vitro and in vivo. Our findings show that Q promoted epithelial cell migration, accelerated wound healing and increased E-cadherin expression in IEC-18 cells and isolated intestinal epithelial cells (IECs) after Q feeding. The upregulation of E-cadherin was dependent on TLR4 and IFNAR signaling, triggering CD103 expression in lymphocytes. Q reinforced the E-cadherin-αEß7 axis, crucial for intestinal barrier integrity and contributed to the localization of lymphocytes on the epithelium.

Quantitative analysis and evaluation of solid-state stability of mebendazole Forms A and C suspensions by powder X-ray diffraction using the Rietveld method.

Mebendazole (MBZ) is a broad-spectrum active pharmaceutical ingredient (API) indicated for treating parasitosis, and it has three solid-state forms, A, B, and C. These solid forms exhibit significant differences in dissolution properties, which cause considerable changes in the therapeutic effect. When at least 30 % of Form A is present in the formulation, it has a similar effect to the placebo. The aim of this study was to develop a reliable quantitative method for MBZ (Forms A and C) suspensions that allowed to study the solid-state stability and the kinetics of the solid-state transformation of MBZ suspensions under the recommended pharmaceutical industry conditions. One method was developed to carry out the drying process and the other one to quantify Forms A and C of MBZ suspensions; both were evaluated. For the stability study, samples were prepared with different starting reference concentrations of Form A and stored from 1 to 24 months under long-term stability conditions (30 ± 2 °C and 75 ± 5 % RH) and from 1 to 6 months under accelerated stability conditions (40 ± 2 °C and 75 ± 5 % RH). Data collection was performed by powder X-ray diffraction (PXRD). The Rietveld method (RM) and Topas's program were used to solid form quantification. Avrami's equation was used to determine the kinetic parameters. The results showed that the combination of the drying process and solid form quantification developed method for suspension was a very accurate methodology for solid-state stability studies. Furthermore, in long-term and accelerated solid-state conditions, suspension with an initial value of 1 % of Form A were sufficient to cause a solid-state transformation (Form C to A) greater than 30 % in the first and second months, with a complete transformation in nine and six months respectively. These results demonstrate that suspensions show complete solid-state transformation (Form C to A) in a shorter time than the product's shelf life (∼2 years). In this work, a reliable methodology was developed to quantify MBZ (Forms A and C) suspensions. This methodology could be used to control the different solid forms for MBZ and other APIs to avoid solid-state transformation problems.

Chitosan can improve antimicrobial treatment independently of bacterial lifestyle, biofilm biomass intensity and antibiotic resistance pattern in non-aureus staphylococci (NAS) isolated from bovine clinical mastitis.

Bovine mastitis is the most frequent and costly disease that affects dairy cattle. Non-aureus staphylococci (NAS) are currently one of the main pathogens associated with difficult-to-treat intramammary infections. Biofilm is an important virulence factor that can protect bacteria against antimicrobial treatment and prevent their recognition by the host's immune system. Previously, we found that chronic mastitis isolates which were refractory to antibiotic therapy developed strong biofilm biomass. Now, we evaluated the influence of biofilm biomass intensity on the antibiotic resistance pattern in strong and weak biofilm-forming NAS isolates from clinical mastitis. We also assessed the effect of cloxacillin (Clx) and chitosan (Ch), either alone or in combination, on NAS isolates with different lifestyles and abilities to form biofilm. The antibiotic resistance pattern was not the same in strong and weak biofilm producers, and there was a significant association (p ≤ 0.01) between biofilm biomass intensity and antibiotic resistance. Bacterial viability assays showed that a similar antibiotic concentration was effective at killing both groups when they grew planktonically. In contrast, within biofilm the concentrations needed to eliminate strong producers were 16 to 128 times those needed for weak producers, and more than 1,000 times those required for planktonic cultures. Moreover, Ch alone or combined with Clx had significant antimicrobial activity, and represented an improvement over the activity of the antibiotic on its own, independently of the bacterial lifestyle, the biofilm biomass intensity or the antibiotic resistance pattern. In conclusion, the degree of protection conferred by biofilm against antibiotics appears to be associated with the intensity of its biomass, but treatment with Ch might be able to help counteract it. These findings suggest that bacterial biomass should be considered when designing new antimicrobial therapies aimed at reducing antibiotic concentrations while improving cure rates.

Chitosan and cloxacillin combination improve antibiotic efficacy against different lifestyle of coagulase-negative Staphylococcus isolates from chronic bovine mastitis.

Bovine mastitis affects the health of dairy cows and the profitability of herds worldwide. Coagulase-negative staphylococci (CNS) are the most frequently isolated pathogens in bovine intramammary infection. Based on the wide range of antimicrobial, mucoadhesive and immunostimulant properties demonstrated by chitosan, we have evaluated therapy efficiency of chitosan incorporation to cloxacillin antibiotic as well as its effect against different bacterial lifestyles of seven CNS isolates from chronic intramammary infections. The therapeutic effects of combinations were evaluated on planktonic cultures, bacterial biofilms and intracellular growth in mammary epithelial cells. We found that biofilms and intracellular growth forms offered a strong protection against antibiotic therapy. On the other hand, we found that chitosan addition to cloxacillin efficiently reduced the antibiotic concentration necessary for bacterial killing in different lifestyle. Remarkably, the combined treatment was not only able to inhibit bacterial biofilm establishment and increase preformed biofilm eradication, but it also reduced intracellular bacterial viability while it increased IL-6 secretion by infected epithelial cells. These findings provide a new approach to prophylactic drying therapy that could help to improve conventional antimicrobial treatment against different forms of bacterial growth in an efficient, safer and greener manner reducing multiresistant bacteria generation and spread.

Characterization of the inhibition of enveloped virus infectivity by the cationic acrylate polymer eudragit E100.

The antiviral effects of the cationic acrylate polymer E100 on a panel of lipid-enveloped viruses and the interactions involved are studied. The treatment of several common viruses with E100 induced a dose-dependent inhibition of the infectivity of viruses below the detection limit of the assays employed. Similarly, the treatment of human sera infected with HIV or HCV reduced virus RNA plasma levels to undetectable values. This implies that Eudragit E100 can interact with enveloped viruses, even in the presence of proteins, through a mechanism that is not reversed by titration of the positively charged groups of the polymer, opening the possibility to remove viral particles with the polymer as it is eliminated.

Formulation, Quality Control and Safety Issues of Nanocarriers Used for Cancer Treatment.

Cancer is becoming a leading cause of death in the last years. Although we have seen great advances, most human cancers remain incurable because many patients either do not respond or relapse to treatment. Several lines of research are disclosing new therapeutic targets which lead to new active drugs. However, there are still unsolved problems related to stabilization of the pharmaceutical ingredient in aqueous and biological media, pharmacokinetic and pharmacodynamic profiles and cellular uptake to name just a few. In this context, nanotechnology with the emerging tools of nanoengineering offers many possibilities to guide the design of new products with improved safety and efficacy. The presence of several reacting groups and the sensitivity of their properties to small changes in composition make nanocarriers tunable not only to modify their stability in a particular environment but also to respond to changes in biological situations in the right place and time frame. This review summarizes the main preparation methods and formulation strategies of nano and microcarriers designed for drug delivery applications for cancer treatment and will attempt to give a glimpse on how their structure, shape, physico-chemical properties and chemical composition may affect their overall stability and interactions with biological systems. We will also cover aspects of nanoengineering that are opening new opportunities for the development of more effective nanomedicines, emphasizing on the challenges that have to be kept in mind when dealing with biological activities of nanocarriers that depend not only on their chemical composition but also on those of the structures formed by them and by their interactions with biological systems. From this, a very important issue that emerges is that nanocarriers frequently display an intrinsic bioactivity (i.e.: immunomodulatory). Therefore, it should be stressed that nanocarriers cannot be considered as inert, biocompatible excipients. Furthermore, their biological activity will mostly depend on the physical and chemical properties of the structures of the nanoparticles that are presented to living systems. As an approach to the rational design of new pharmaceutical products, nanoengineering is providing new tools for the precise control of the properties of nanocarriers for cancer treatment.

Local and systemic activity of the polysaccharide chitosan at lymphoid tissues after oral administration.

Chitosan is a cationic polysaccharide derived from the partial deacetylation of chitin, which exhibits particular properties: interacts with negatively charged sites on the cell surface; changes the permeability of intestinal epithelium, enhancing the uptake of peptides and proteins; and activates leukocytes. Antigens coadministered or encapsulated with the polysaccharide show improved mucosal and systemic humoral immune responses, although the mechanism is poorly understood. Herein, we characterized in Peyer's patches mesenteric lymph nodes and spleen molecular events triggered after oral administration of chitosan in the absence of protein antigen. Sixteen hours after feeding, we studied the uptake and distribution of the polysaccharide, the phenotype of recruited antigen-presenting cells (APC), the induction of cytokines such as tumor necrosis factor alpha, interleukin (IL)-12, IL-4, IL-10, and transforming growth factor-beta (TGF-beta), and the activation of T lymphocytes. We show here that the uptake of chitosan at inductive mucosal sites involves CD11b/c+ APC and that chitosan feeding increases the percentage of OX62+ dendritic cells, which up-regulate the major histocompatibility complex class II antigens without changing the expression of costimulatory CD80 or CD86 molecules. The polysaccharide elicits the release of IL-10 as well as the expression of IL-4 and TGF-beta in mucosa, and in spleen, the activation of CD3+ T cells occurs. Our results demonstrate that chitosan acts by enhancing the T helper cell type 2 (Th2)/Th3 microenvironment in the mucosa. A single dose of this polysaccharide exhibits local and systemic effects, and its activity could be relevant in the maintenance of the intestinal homeostasis.

Thermodynamic and Kinetic Aspects Involved in the Development of Nanocarriers and Drug Delivery Systems Based on Cationic Biopolymers.

During the last years we have seen an increasing number of reports describing new properties and potential applications of cationic polymers and derived nanostructures. This review gives a summary of their applications in drug delivery, the preparation methods for nano and microstructures and will attempt to give a glimpse on how their structure, chemical composition and properties may be affected or modulated as to make them suitable for an intended application as drug delivery nanocarriers. The compositional complexity with the existence of several reacting groups makes cationic nanostructures critically sensitive to the contribution of thermodynamic and kinetic parameters in the determination of the type and stability of a particular structure and its ability to respond to changes in environmental conditions in the right time frame. Curiously, and contrarily to what could be expected, despite the fact that cationic polymers can form strong electrostatic interactions the contribution of the entropic component has been often found to be very important for their association with negatively charged supramolecular structures. Some general considerations indicate that when considering a complex multimolecular system like a nanocarrier containing an active ingredient it is frequently possible to find conditions under which enthalpic and entropic contributions are compensated leading to stable structures with a marginal thermodynamic stability (free energy change close to zero) which make them able to respond relatively fast to changes in the environmental conditions and therefore suitable for the design of smart drug delivery systems. Like with other nanocarriers, it should always be kept in mind that the properties of cationic nanocarriers will depend not only on their chemical composition but also on the properties of the structures formed by them.

Aggregation of casein micelles by interactions with chitosans: a study by Monte Carlo simulations.

Recently, it was found that the addition of chitosan, a cationic polymer, to whole or skim milk produces the destabilization and coagulation of casein micelles which takes place without modifications in the milk pH or in the stability of most of the whey proteins. In the present work, Monte Carlo simulations are employed to show that the phase separation of casein micelles induced by chitosan can be explained by a depletion mechanism, where an effective attraction between the casein micelles is induced by the presence of chitosan molecules. This interaction is described on the basis of Vrij's model, where the depletion of polymer from the gap between neighboring casein micelles originates an effective attractive interaction that leads to a phase transition. This model, that considers volume restriction effects, accounts for several qualitative and even quantitative aspects of the experimental data for the coagulation of casein through chitosan addition.

Reversible precipitation of casein micelles with a cationic hydroxyethylcellulose.

The cationic hydroxyethylcellulose Polyquaternium 10 (PQ10) was found to produce a dose-dependent destabilization of casein micelles from whole or skim milk without affecting the stability of most of the whey proteins. The anionic phosphate residues on caseins were not determinant in the observed interaction since the destabilization was also observed with dephosphorylated caseins to the same extent. However, the precipitation process was completely inhibited by rising NaCl concentration, indicating an important role of electrostatic interactions. Furthermore, the addition of 150 mM NaCl solubilized preformed PQ10-casein complexes, rendering a stable casein suspension without a disruption of the internal micellar structure as determined by dynamic light scattering. This casein preparation was found to contain most of the Ca2+ and only 10% of the lactose originally present in milk and remained as a stable suspension for at least 4 months at 4 degrees C. The final concentration of PQ10 determined both the size of the casein-polymer aggregates and the amount of milkfat that coprecipitates. The presence of PQ10 in the aggregates did not inhibit the activity of rennet or gastrointestinal proteases and lipases, nor did it affect the growth of several fermentative bacteria. The cationic cellulose PQ10 may cause a reversible electrostatic precipitation of casein micelles without disrupting their internal structure. The reversibility of the interaction described opens the possibility of using this cationic polysaccharide to concentrate and resuspend casein micelles from whole or skim milk in the production of new fiber-enriched lactose-reduced calcium-caseinate dairy products.

Amphipathic and membrane-destabilizing properties of the cationic acrylate polymer Eudragit E100.

The cationic acrylate polymer Eudragit E100 (E100) produces a biphasic effect on the stability of casein micelles disrupting their internal structure. These results suggested that this polymer could have some amphipathic character. Therefore, in this study the polymer was characterized with respect to its interaction with different amphipathic systems (bile-acid micelles, lipoproteins and liposomes), cell membranes (red blood cells) and virus membranes (Herpes simplex type 2 virus). As with caseins, a biphasic effect was observed with bile acids with a precipitation phase at low polymer/bile acid ratio and a solubilization phase when the polymer concentration was increased. Upon interaction with human plasma, an important reduction in cholesterol and triglycerides was observed upon remotion of E100 by a rise in pH to 8.5 and centrifugation. In agreement with this finding, an important reduction in plasma lipoproteins was observed upon its treatment with E100 and further remotion by pH rise and centrifugation. However, the amount of the major protein components of human plasma and the activity of several enzymes and antibodies were not affected by their treatment with E100. The membrane-destabilizing properties of E100 were confirmed by its lytic activity on liposomes and red blood cells and by an important antiviral effect of E100 on Herpes simplex virus type 2. Altogether, these results show that, despite its water solubility and cationic character, E100 displays a significative amphipathic and membrane-destabilizing character with potential biotechnological applications. [diagram in text].

Biochemical characterization of the interactions between doxorubicin and lipidic GM1 micelles with or without paclitaxel loading.

Doxorubicin (Dox) is an anthracycline anticancer drug with high water solubility, whose use is limited primarily due to significant side effects. In this study it is shown that Dox interacts with monosialoglycosphingolipid (GM1) ganglioside micelles primarily through hydrophobic interactions independent of pH and ionic strength. In addition, Dox can be incorporated even into GM1 micelles already containing highly hydrophobic paclitaxel (Ptx). However, it was not possible to incorporate Ptx into Dox-containing GM1 micelles, suggesting that Dox could be occupying a more external position in the micelles. This result is in agreement with a higher hydrolysis of Dox than of Ptx when micelles were incubated at alkaline pH. The loading of Dox into GM1 micelles was observed over a broad range of temperature (4°C-55°C). Furthermore, Dox-loaded micelles were stable in aqueous solutions exhibiting no aggregation or precipitation for up to 2 months when kept at 4°C-25°C and even after freeze-thawing cycles. Upon exposure to blood components, Dox-containing micelles were observed to interact with human serum albumin. However, the amount of human serum albumin that ended up being associated to the micelles was inversely related to the amount of Dox, suggesting that both could share their binding sites. In vitro studies on Hep2 cells showed that the cellular uptake and cytotoxic activity of Dox and Ptx from the micellar complexes were similar to those of the free form of these drugs, even when the micelle was covered with albumin. These results support the idea of the existence of different nano-domains in a single micelle and the fact that this micellar model could be used as a platform for loading and delivering hydrophobic and hydrophilic active pharmaceutical ingredients.

Biochemical characterization of GM1 micelles-Amphotericin B interaction.

In this work a thorough characterization of the GM1 micelle-Amphotericin B (AmB) interaction was performed. The micelle formation as well as the drug loading occurs spontaneously, although influenced by the physicochemical conditions, pH and temperature. The chromatographic profile of GM1-AmB complexes at different molar ratios shows the existence of two populations. The differential absorbance of GM1, monomeric and aggregate AmB, allowed us to discriminate the presence of all of them in both fractions. Thus, we noted that at higher proportion of AmB in the complex, increases the larger population which is composed mainly of aggregated AmB. The physical behavior of these micelles shows that both GM1- AmB complexes were stable in solution for at least 30 days. However upon freeze-thawing or lyophilization-solubilization cycles, only the smallest population, enriched in monomeric AmB, showed a complete solubilization. In vitro, GM1-AmB micelles were significantly less toxic on cultured cells than other commercial micellar formulations as Fungizone, but had a similar behavior to liposomal formulations as Ambisome. Regarding the antifungal activity of the new formulation, it was very similar to that of other formulations. The characterization of these GM1-AmB complexes is discussed as a potential new formulation able to improve the antifungal therapeutic efficiency of AmB.

Interaction of a cationic acrylate polymer with caseins: biphasic effect of Eudragit E100 on the stability of casein micelles.

When whole or skim milk was incubated with the cationic acrylate polymer Eudragit E100, a biphasic effect on the stability of casein micelles was observed. A precipitation phase was observed at low polymer/casein ratios. Strikingly, a solubilization phase of the aggregates was observed when the ratios of polymer/casein were increased. Purified alpha(s)-, beta-, and kappa-caseins or dephosphorylated caseins were equally precipitated and resolubilized by the cationic polymer, indicating no special selectivity for a particular protein or phosphate residue for these events. An increase in the size of the aggregates as the optimum precipitating amount of Eudragit E100 was reached suggests a crossbridging of the micelles by the polymer. The inhibition of the precipitation phase by high ionic strength indicates that electrostatic interactions play a critical role in complex formation. Furthermore, a dramatic reduction in size of the protein colloidal particles upon solubilization of the aggregates was observed by dynamic light scattering, indicating a dissociation of the micellar structure. Taken together, the results indicate that at low concentration Eudragit E100 may act as a precipitant of casein micelles, mainly by ionic interaction and at high concentration as an amphipathic agent, solubilizing casein micelles with a disruption of their internal structure.

Eudragit E100 surface activity and lipid interactions.

Eudragit E100 (E100) is a cationic methacrylate polymer that interacts with viral and cell membranes. We studied the effect of pH, ionic strength and the presence of lipid monolayers on the surface activity of the polymer. E100 forms stable monolayers at the air-water interface, either by spreading or when added into the subphase. This behavior is highly influenced by the pH and saline concentration of the subphase. At pH 5 or higher, the adsorption of the polymer to the air-water interface begins immediately after its injection into the subphase, while at pH below 5 E100 remains in the subphase with a particularly slow adsorption to the interface. In addition, low ionic strength (10 mM) in the subphase results in a fast adsorption of the polymer to the interface, even at pH under 5. On the other hand, in the presence of non-ionic (cholesterol) or anionic (monosialoganglioside) lipid monolayers, E100 shows a fast adsorption to the interface, [comma] reaching surface pressures of 25 and 36 mN m(-1), respectively. However, E100 barely interacts with monolayers of a zwitterionic lipid (hydrogenated soy lecithin) with a cut-off pressure of 11 mN m(-1). The interaction of E100 with GM1 micelles in the subphase reduces its surface activity. Altogether these results show that E100 can effectively penetrate into model membranes and that its amphipathic character is largely dependent on the chemical composition of the aqueous environment and the lipid composition of the membrane.

Self-assembled micelles of monosialogangliosides as nanodelivery vehicles for taxanes.

We demonstrate herein that taxanes (paclitaxel (Ptx) and docetaxel (Dtx)) can be spontaneously loaded into ganglioside nanomicelles. The efficiency of gangliosides to solubilize taxanes was highly dependent on their self-aggregating structure. Thus, GM3 that forms unilamellar vesicles was less efficient to solubilize taxanes than gangliosides that form micelles (i.e. GM1 and GM2). Sialic acid cyclization of GM1 by acid treatment led to an important reduction in its capacity to solubilize taxanes, as also did the replacement of the fatty acid of ceramide by a dicholoracetyl group. Water solubility of paclitaxel (Ptx) is less than 1 µg mL⁻¹ and increased up to 6.3mg.mL⁻¹ upon its association with GM1 micelles. The incorporation of Ptx in GM1 reached an optimum at GM1/Ptx 20/1 molar ratio when performed at room temperature. An increase in the solubilization capacity of GM1 micelles was observed upon dehydration of their polar head group by pre-treatment at 55 °C. Loading of Ptx into the micelle induced a structural reorganization that led to an important protection of Ptx reducing its hydrolysis at alkaline pH. Diffusion of either GM1 or Ptx was restricted upon mixed-micelle formation indicating that they are kinetically more stable than pure ganglioside micelles. X-ray powder diffraction of lyophilized GM1 micelles with Ptx showed a change in their internal structure from a crystalline state to completely amorphous. Taxane-ganglioside mixed micelles were stable in solution for at least 4months and also upon freeze-thawing or lyophilization-solubilization cycles. Upon mixing with human blood constituents, GM1/Ptx micelles did not induce hemolysis or platelet aggregation and were spontaneously covered with human serum albumin (HSA), which could aid in the delivery of micellar content to tumors. In vitro antimitotic activity of GM1/Ptx mixed micelles was qualitatively equivalent to that of free drug in DMSO solution.

Helminth antigens enable CpG-activated dendritic cells to inhibit the symptoms of collagen-induced arthritis through Foxp3+ regulatory T cells.

Dendritic cells (DC) have the potential to control the outcome of autoimmunity by modulating the immune response. In this study, we tested the ability of Fasciola hepatica total extract (TE) to induce tolerogenic properties in CpG-ODN (CpG) maturated DC, to then evaluate the therapeutic potential of these cells to diminish the inflammatory response in collagen induced arthritis (CIA). DBA/1J mice were injected with TE plus CpG treated DC (T/C-DC) pulsed with bovine collagen II (CII) between two immunizations with CII and clinical scores CIA were determined. The levels of CII-specific IgG2 and IgG1 in sera, the histological analyses in the joints, the cytokine profile in the draining lymph node (DLN) cells and in the joints, and the number, and functionality of CD4+CD25+Foxp3+ T cells (Treg) were evaluated. Vaccination of mice with CII pulsed T/C-DC diminished the severity and incidence of CIA symptoms and the production of the inflammatory cytokine, while induced the production of anti-inflammatory cytokines. The therapeutic effect was mediated by Treg cells, since the adoptive transfer of CD4+CD25+ T cells, inhibited the inflammatory symptoms in CIA. The in vitro blockage of TGF-ß in cultures of DLN cells plus CII pulsed T/C-DC inhibited the expansion of Treg cells. Vaccination with CII pulsed T/C-DC seems to be a very efficient approach to diminish exacerbated immune response in CIA, by inducing the development of Treg cells, and it is therefore an interesting candidate for a cell-based therapy for rheumatoid arthritis (RA).