Mucoadhesive-to-penetrating controllable peptosomes-in-microspheres co-loaded with anti-miR-31 oligonucleotide and Curcumin for targeted colorectal cancer therapy.

Background: Accumulating evidences indicate that nanomedicines greatly decrease the side effects and enhance the efficacy of colorectal cancer (CRC) treatment. In particular, the use of rectal delivery of nanomedicines, with advantages such as fast therapeutic effects and a diminishing hepatic first-pass effect, is currently emerging. Method: We established a CRC targeted delivery system, in which α-lactalbumin peptosomes (PSs) co-loaded with a microRNA (miR)-31 inhibitor (miR-31i) and curcumin (Cur) were encapsuslated in thiolated TEMPO oxidized Konjac glucomannan (sOKGM) microspheres, referred as sOKGM-PS-miR-31i/Cur. The CRC targeting capability, drug release profiles, mucoadhesive-to-penetrating properties and therapeutic efficacy of sOKGM-PS-miR-31i/Cur delivery system were evaluated in colorectal cancer cells and azoxymethane-dextran sodium (AOM-DSS) induced tumor models. Results: sOKGM-PS-miR-31i/Cur delivery system were stable in the harsh gastrointestinal environment after rectal or oral administration; and were also mucoadhesive due to disulfide bond interactions with the colonic mucus layer, resulting in an enhanced drug retention and local bioavailability in the colon. Concomitantly, the released PS-miR-31i/Cur PSs from the microsphere was mucus-penetrating, efficiently passing through the colonic mucus layer, and allowed Cur and miR-31i specifically target to colon tumor cells with the guide of CD133 targeting peptides. Consequently, rectal delivery of sOKGM-PS-miR-31i/Cur microspheres suppressed tumor growth in an azoxymethane-dextran sodium sulfate (AOM-DSS)-induced tumor model. Conclusion: sOKGM-PS-miR-31i/Cur microspheres are effective rectal delivery system with combined advantages of mucoadhesive and mucus-penetrating properties, representing a potent and viable therapeutic approach for CRC.

The in vitro displacement of adsorbed model antigens from aluminium-containing adjuvants by interstitial proteins.

Vaccines prepared by adsorbing an antigen onto an aluminium-containing adjuvant are usually administered by intramuscular or subcutaneous injection. The vaccine then comes in contact with interstitial fluid which contains proteins. In vitro displacement studies were performed to determine whether antigens, which are adsorbed to aluminium-containing adjuvants, can be displaced by interstitial proteins. It was found that when previously adsorbed model antigens such as lysozyme or myoglobin were exposed to interstitial proteins such as albumin or fibrinogen that extensive displacement occurred. A factorial study of the displacement of myoglobin from aluminium hydroxide adjuvant by albumin was performed. The displacement occurred rapidly with the majority of the displacement occurring in less than 15 min. Whether the concentration of the adsorbed myoglobin was above or below the adsorptive capacity of the aluminium hydroxide adjuvant affected the amount which could be displaced. Less myoglobin was displaced when the concentration was below the adsorptive capacity. The age of the model vaccine (1, 2 or 7 days) prior to exposure to the interstitial protein did not influence the amount of myoglobin that was displaced. The affinity of model antigens and interstitial proteins for aluminium hydroxide or aluminium phosphate adjuvant was characterized by the adsorption coefficient in the Langmuir equation. In every case studied, the protein having the larger adsorption coefficient was able to displace the protein with the smaller adsorption coefficient.

[Bioavailability of amino acids from several industrially-prepared protein-containing products]. / Bioverfügbarkeit von Aminosäuren aus einigen industriell gefertigten proteinhaltigen Produkten.

To evaluate the bioavailability of amino acids from proteins and protein-containing products, the area under the postprandial plasma-concentration-time-curve of the amino acids after oral administration needs to be calculated. Therefore, basic values depending on circadian plasma concentration rhythms have to be subtracted from measured values after loading. To determine the relative bioavailability of two tested samples, e.g., a protein-containing product before and after processing or two technologically different preparations of the same protein, it is sufficient to compare their absorption-curves, both corrected by the basic values. For that purpose the mean value-curves corresponding to the group of subjects are used, because the individual courses show considerable differences, in particular due to discontinuous gastric emptying. Enzymatic hydrolysis of a lactalbumin reduces the quantitative bioavailability of the amino acids by 12%. Concerning products used in nutrition of patients and babies, the availability from ready-to-drink liquid products is about 7-10% better than that out of the same dry products in powdered form. Compared with sterilization, ultrahigh heat treatment of milk protein products improves the availability slightly, by about 1%. Processing of dried green peas destined for use in convenience food increases the protein availability by 20%.

The importance of alpha-lactalbumin in infant nutrition.

The ideal "humanization" of milk substitutes should include the creation of an amino acid pattern closely resembling that of human milk. Because the mixture of proteins in human milk is particularly rich in tryptophan and cysteine and low in methionine, this pattern is difficult to achieve with commercially available proteins. Even whey-predominant formulas only approximate human milk. Human milk has a high concentration of whey protein (70% of total protein). Of this, alpha-lactalbumin, a component of the lactase synthetase complex, accounts for 41% of the whey and 28% of the total protein. Only 3% of the protein in bovine milk is alpha-lactalbumin. Human and bovine alpha-lactalbumin share a 72% amino acid sequence homology. Both proteins contain (wt/wt) 6% tryptophan and 5% cysteine but only 0.9% methionine. Thus the differences in the amino acid compositions of bovine and human milks are largely attributable to differences in their alpha-lactalbumin contents. Commercial availability of bovine alpha-lactalbumin would allow the construction of infant formulas with amino acid compositions that are very close to that of human milk. alpha-Lactalbumin would also be a valuable constituent of diets for patients whose protein intake must be restricted.