Zein-based nanoparticles for the oral delivery of insulin.

The aim of this work was to evaluate oral nanocarriers, prepared from zein nanoparticles coated with a poly(anhydride)-thiamine conjugate (GT), for the delivery of insulin. Nanoparticles displayed a size of 250 nm with a negative surface charge, and an insulin loading of 80 µg/mg. Under simulated gastric conditions, GT-coated nanoparticles released a significantly lower amount of insulin than bare ones; whereas in simulated intestinal conditions, both types of nanoparticles displayed a similar behavior. The effect of insulin on the lipid metabolism of C. elegans under high glucose conditions, characterized by a reduction of the fat content, was also investigated. The effect was significantly higher for the nanoencapsulated forms of insulin than for the free protein (p < 0.001). This effect was two times higher for GT-coated nanoparticles than for bare ones. In rats, the hypoglycemic effect and the pharmacokinetic profile of insulin-loaded nanoparticles orally administered (50 IU/kg) were evaluated. The glycemia of animals slowly decreased reaching a minimum 6-10-h post-administration, with a maximum decrease of about 60%. The pharmacological availability of nanoencapsulated insulin was 13.5%. In serum, nanoparticles provided a maximum of insulin 4-h post-administration, and its relative oral bioavailability was 5.2% (compared with a sc formulation of insulin). Graphical abstract.

Nanoparticles from Gantrez® AN-poly(ethylene glycol) conjugates as carriers for oral delivery of docetaxel.

The oral delivery of docetaxel (DTX) is challenging due to a low bioavailability, related to an important pre-systemic metabolism. With the aim of improving the bioavailability of this cytotoxic agent, nanoparticles from conjugates based on the copolymer of methyl vinyl ether and maleic anhydride (poly(anhydride)) and two different types of PEG, PEG2000 (PEG2) or methoxyPEG2000 (mPEG2), were evaluated. Nanoparticles, with a DTX loading close to 10%, were prepared by desolvation and stabilized with calcium, before purification and lyophilization. For the pharmacokinetic study, nanoparticles were orally administered to mice at a single dose of 30 mg/kg. The plasma levels of DTX were high, prolonged in time and, importantly, quantified within the therapeutic window. The relative oral bioavailability was calculated to be up to 56% when DTX was loaded in nanoparticles from poly(anhydride)-mPEG2000 conjugate (DTX-NP-mPEG2). Finally, a comparative toxicity study between equitoxic doses of free iv DTX and oral DTX-NP-mPEG2 was conducted in mice. Animals orally treated with DTX-loaded nanoparticles displayed less severe signs of hypersensitivity reactions, peripheral neurotoxicity, myelosuppression and hepatotoxicity than free iv docetaxel. In summary, poly(anhydride)-PEG conjugate nanoparticles appears to be adequate carries for the oral delivery of docetaxel.

Modulation of the fate of zein nanoparticles by their coating with a Gantrez® AN-thiamine polymer conjugate.

The aim of this work was to evaluate the mucus-permeating properties of nanocarriers using zein nanoparticles (NPZ) coated with a Gantrez® AN-thiamine conjugate (GT). NPZ were coated by incubation at different GT-to-zein ratios: 2.5% coating with GT (GT-NPZ1), 5% (GT-NPZ2) and 10% (GT-NPZ3). During the process, the GT conjugate formed a polymer layer around the surface of zein nanoparticles. For GT-NPZ2, the thickness of this corona was estimated between 15 and 20 nm. These nanocarriers displayed a more negative zeta potential than uncoated NPZ. The diffusivity of nanoparticles was evaluated in pig intestinal mucus by multiple particle tracking analysis. GT-NPZ2 displayed a 28-fold higher diffusion coefficient within the mucus layer than NPZ particles. These results align with in vivo biodistribution studies in which NPZ displayed a localisation restricted to the mucus layer, whereas GT-NPZ2 were capable of reaching the intestinal epithelium. The gastro-intestinal transit of mucoadhesive (NPZ) and mucus-permeating nanoparticles (GT-NPZ2) was also found to be different. Thus, mucoadhesive nanoparticles displayed a significant accumulation in the stomach of animals, whereas mucus-penetrating nanoparticles appeared to exit the stomach more rapidly to access the small intestine of animals.

Mannosylated Nanoparticles for Oral Immunotherapy in a Murine Model of Peanut Allergy.

Peanut allergy is one of the most prevalent and severe of food allergies with no available cure. The aim of this work was to evaluate the potential of an oral immunotherapy based on the use of a roasted peanut extract encapsulated in nanoparticles with immunoadjuvant properties. For this, a polymer conjugate formed by the covalent binding of mannosamine to the copolymer of methyl vinyl ether and maleic anhydride was first synthetized and characterized. Then, the conjugate was used to prepare nanoparticles with an important capability to diffuse through the mucus layer and reach, in a large extent, the intestinal epithelium, including Peyer's patches. Their immunotherapeutic potential was evaluated in a model of presensitized CD1 mice to peanut. After completing therapy, mice underwent an intraperitoneal challenge with peanut extract. Nanoparticle-treatment was associated with both less serious anaphylaxis symptoms and higher survival rates than control, confirming the protective effect of this formulation against the challenge.

The effect of thiamine-coating nanoparticles on their biodistribution and fate following oral administration.

Thiamine-coated nanoparticles were prepared by two different preparative methods and evaluated to compare their mucus-penetrating properties and fate in vivo. The first method of preparation consisted of surface modification of freshly poly(anhydride) nanoparticles (NP) by simple incubation with thiamine (T-NPA). The second procedure focused on the preparation and characterization of a new polymeric conjugate between the poly(anhydride) backbone and thiamine prior the nanoparticle formation (T-NPB). The resulting nanoparticles displayed comparable sizes (about 200 nm) and slightly negative surface charges. For T-NPA, the amount of thiamine associated to the surface of the nanoparticles was 15 µg/mg. For in vivo studies, nanoparticles were labelled with either 99mTc or Lumogen® Red. T-NPA and T-NPB moved faster from the stomach to the small intestine than naked nanoparticles. Two hours post-administration, for T-NPA and T-NPB, >30% of the given dose was found in close contact with the intestinal mucosa, compared with a 13.5% for NP. Interestingly, both types of thiamine-coated nanoparticles showed a greater ability to cross the mucus layer and interact with the surface of the intestinal epithelium than NP, which remained adhered in the mucus layer. Four hours post-administration, around 35% of T-NPA and T-NPB were localized in the ileum of animals. Overall, both preparative processes yielded thiamine decorated carriers with similar physico-chemical and biodistribution properties, increasing the versatility of these nanocarriers as oral delivery systems for a number of biologically active compounds.

New pharmaceutical approaches for the treatment of food allergies.

INTRODUCTION: Allergic diseases constitute one of the most common causes of chronic illness in developed countries. The main mechanism determining allergy is an imbalance between Th1 and Th2 response towards Th2. AREAS COVERED: This review describes the mechanisms underlying the natural tolerance to food components and the development of an allergic response in sensitized individuals. Furthermore, therapeutic approaches proposed to manage these abnormal immunologic responses food are also presented and discussed. EXPERT OPINION: In the past, management of food allergies has consisted of the education of patients to avoid the ingestion of the culprit food and to initiate the therapy (e.g. self-injectable epinephrine) in case of accidental ingestion. In recent years, sublingual/oral immunotherapies based on the continuous administration of small amounts of the allergen have been developed. However, the long periods of time needed to obtain significant desensitization and the generation of adverse effects, limit their use. In order to solve these drawbacks, strategies to induce tolerance are being studied, such as the use of either adjuvant immunotherapy in order to facilitate the reversion of the Th2 response towards Th1 or the use of monoclonal antibodies to block the main immunogenic elements.

Evaluation of nanoparticles as oral vehicles for immunotherapy against experimental peanut allergy.

The aim of this work was to evaluate the potential application of an original oral immunotherapy, based on the use of nanoparticles, against an experimentally induced peanut allergy. In this context, a roasted peanut extract, containing the main allergenic proteins, were encapsulated into poly(anhydride) nanoparticles. The resulting peanut-loaded nanoparticles (PE-NP) displayed a mean size of about 150nm and a significantly lower surface hydrophobicity than empty nanoparticles (NP). This low hydrophobicity correlated well with a higher in vitro diffusion in pig intestinal mucus than NP and an important in vivo capability to reach the intestinal epithelium and Peyer's patches. The immunotherapeutic capability of PE-NP was evaluated in a model of pre-sensitized CDI mice to peanut. After completing therapy of three doses of peanut extract, either free or encapsulated into nanoparticles, mice underwent an intraperitoneal challenge. Anaphylaxis was evaluated by means of assessment of symptom scores and mouse mast cell protease-1 levels (mMCPT-1). PE-NP treatment was associated with significant lower levels of mMCPT-1, and a significant survival rate after challenge, confirming the protective effect of this formulation against the challenge. In summary, this nanoparticle-based formulation might be a valuable strategy for peanut-specific immunotherapy.

Mimicking microbial strategies for the design of mucus-permeating nanoparticles for oral immunization.

Dealing with mucosal delivery systems means dealing with mucus. The name mucosa comes from mucus, a dense fluid enriched in glycoproteins, such as mucin, which main function is to protect the delicate mucosal epithelium. Mucus provides a barrier against physiological chemical and physical aggressors (i.e., host secreted digestive products such as bile acids and enzymes, food particles) but also against the potentially noxious microbiota and their products. Intestinal mucosa covers 400m(2) in the human host, and, as a consequence, is the major portal of entry of the majority of known pathogens. But, in turn, some microorganisms have evolved many different approaches to circumvent this barrier, a direct consequence of natural co-evolution. The understanding of these mechanisms (known as virulence factors) used to interact and/or disrupt mucosal barriers should instruct us to a rational design of nanoparticulate delivery systems intended for oral vaccination and immunotherapy. This review deals with this mimetic approach to obtain nanocarriers capable to reach the epithelial cells after oral delivery and, in parallel, induce strong and long-lasting immune and protective responses.

In vivo study of the mucus-permeating properties of PEG-coated nanoparticles following oral administration.

The aim of this work was to investigate the mucus-permeating properties of poly(ethyleneglycol)-coated nanoparticles prepared from the copolymer of methyl vinyl ether and maleic anhydride (Gantrez® AN) after oral administration in rats. Nanoparticles were "decorated" with PEGs of different molecular masses (PEG2000, PEG6000 and PEG10000) at a PEG-to-polymer ratio of 0.125. All the PEG-coated nanoparticles displayed a mean size of ∼150 nm, slightly negative ζ values and a "brush" conformation as determined from the calculation of the PEG density. For in vivo studies, nanoparticles were labelled with either (99m)Tc or fluorescent tags. Naked nanoparticles displayed a higher ability to interact with the mucosa of the stomach than with the small intestine. However, these interactions were restricted to the mucus layer covering the epithelial surface, as visualised by fluorescence microscopy. On the contrary, PEG-coated nanoparticles moved rapidly to the intestine, as determined by imaging, and, then, were capable to develop important interactions with the mucosa, reaching the surface of the epithelium. These mucus permeating properties were more intense for nanoparticles coated with PEG2000 or PEG6000 than with PEG10000. However, the capability of nanocarriers to develop adhesive interactions within the mucosa decreased when prepared at excessive PEG densities.