Biocompatible Polymers Modified with d-Octaarginine as an Absorption Enhancer for Nasal Peptide Delivery

Discovery of a selective TRF2 inhibitor FKB04 induced telomere shortening and senescence in liver cancer cells

Telomere repeat binding factor 2 (TRF2), a critical element of the shelterin complex, plays a vital role in the maintenance of genome integrity. TRF2 overexpression is found in a wide range of malignant cancers, whereas its down-regulation could cause cell death. Despite its potential role, the selectively small-molecule inhibitors of TRF2 and its therapeutic effects on liver cancer remain largely unknown. Our clinical data combined with bioinformatic analysis demonstrated that TRF2 is overexpressed in liver cancer and that high expression is associated with poor prognosis. Flavokavain B derivative FKB04 potently inhibited TRF2 expression in liver cancer cells while having limited effects on the other five shelterin subunits. Moreover, FKB04 treatment induced telomere shortening and increased the amounts of telomere-free ends, leading to the destruction of T-loop structure. Consequently, FKB04 promoted liver cancer cell senescence without modulating apoptosis levels. In corroboration with these findings, FKB04 inhibited tumor cell growth by promoting telomeric TRF2 deficiency-induced telomere shortening in a mouse xenograft tumor model, with no obvious side effects. These results demonstrate that TRF2 is a potential therapeutic target for liver cancer and suggest that FKB04 may be a selective small-molecule inhibitor of TRF2, showing promise in the treatment of liver cancer.

A comprehensive review of advanced nasal delivery: Specially insulin and calcitonin

Peptide drugs through nasal mucous membrane, such as insulin and calcitonin have been widely used in the medical field. There are always two sides to a coin. One side, intranasal drug delivery can imitate the secretion pattern in human body, having advantages of physiological structure and convenient use. Another side, the low permeability of nasal mucosa, protease environment and clearance effect of nasal cilia hinder the intranasal absorption of peptide drugs. Researchers have taken multiple means to achieve faster therapeutic concentration, lower management dose, and fewer side effects for better nasal preparations. To improve the peptide drugs absorption, various strategies had been explored via the nasal mucosa route. In this paper, we reviewed the achievements of 18 peptide drugs in the past decade about the perspectives of the efficacy, mechanism of enhancing intranasal absorption and safety. The most studies were insulin and calcitonin. As a result, absorption enhancers, nanoparticles (NPs) and bio-adhesive system are the most widely used. Among them, chitosan (CS), cell penetrating peptides (CPPs), tight junction modulators (TJMs), soft NPs and gel/hydrogel are the most promising strategies. Moreover, two or three strategies can be combined to prepare drug vectors. In addition, spray freeze dried (SFD), self-emulsifying nano-system (SEN), and intelligent glucose reaction drug delivery system are new research directions in the future.

Mucosal absorption of antibody drugs enhanced by cell-penetrating peptides anchored to a platform of polysaccharides

Our previous studies demonstrated that L-octaarginine grafted onto hyaluronic acid via a tetraglycine spacer significantly enhanced intranasal absorption of protein drugs with a molecular weight (Mw) of 22 kDa or less. The present study focused on its potential as an absorption enhancer for antibody drugs with a larger Mw and the enhancement mechanism. When ranibizumab (48 kDa) alone was intranasally administered in mice, its absolute bioavailability was 0.67% on average. The mean bioavailability elevated to 6.2% under coadministration with tetraglycine-L-octaarginine-linked hyaluronic acid. A similar result was observed under substitution of ranibizumab with certolizumab pegol (91 kDa), although bioavailability itself decreased with the Mw increase, irrespective of coadministration with the hyaluronic acid derivative. Rat experiments also revealed that coadministration with the polysaccharide derivative resulted in significant enhancement of intranasal absorption of trastuzumab (148 kDa). In vitro studies using gene-knocked down cells indicated that syndecan-4-induced macropinocytosis played a crucial role on acceleration of antibody uptake into epithelial cells on the nasal mucosa, irrespective of their Mw. It appeared that neither clathrin heavy chain nor caveolin-1 involved in cellular uptake of antibodies. Tetraglycine-L-octaarginine-linked hyaluronic acid was concluded to be a promising delivery tool that possessed universal absorption-enhancing abilities independent to Mw of biologics.

Current Understanding of Sodium N-(8-[2-Hydroxylbenzoyl] Amino) Caprylate (SNAC) as an Absorption Enhancer: The Oral Semaglutide Experience

Oral administration of peptide therapeutics faces challenges because of the distinct environment of the gastrointestinal tract. An oral formulation of semaglutide, a glucagon-like peptide 1 receptor agonist, was approved by the U.S. Food and Drug Administration in 2019 as a peptide therapy for the treatment of type 2 diabetes. Oral semaglutide uses sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC) technology to enhance the absorption of semaglutide in the stomach and protect it from degradation by gastric enzymes. This article presents a summary of studies investigating SNAC technology as an absorption enhancer for a number of molecules and, in particular, explores how SNAC, once coformulated with oral semaglutide, facilitates increased absorption and bioavailability. Practical advice and dispensing information for pharmacists is also provided.

Performance of Cell-Penetrating Peptides Anchored to Polysaccharide Platforms Applied via Various Mucosal Routes as an Absorption Enhancer

We have been investigating the potential of cell-penetrating peptides anchored to polymeric platforms as a novel absorption enhancer which delivers biologics into systemic circulation via mucosal routes. Our previous mouse experiments demonstrated that hyaluronic acid modified with l-octaarginine, a typical cell-penetrating peptide, via a tetraglycine spacer significantly enhanced the mucosal absorption of protein drugs applied into the nasal cavities, irrespective of the molecular weights (M_w) of the drugs. The present study evaluated the performance of tetraglycine-l-octaarginine-linked hyaluronic acid applied via various mucosal routes. Somatropin (M_w: ca. 22.1 kDa) was moderately absorbed from the lung mucosa, and the mean absolute bioavailability (BA) reached 19% under enhancer-free conditions; nevertheless, its BA under intranasal administration was approximately 1% or less. Its BA significantly elevated to 46% on average through intrapulmonary coadministration with tetraglycine-l-octaarginine-linked hyaluronic acid. When the administration site was replaced with the oral cavities, an extreme reduction in somatropin absorption was observed with a mean BA of 0.056% under enhancer-free conditions. Intraoral coadministration with tetraglycine-l-octaarginine-linked hyaluronic acid resulted in a 6.3-fold elevation of somatropin absorption with statistical significance. A similar enhancement was observed under intrarectal administration with a further reduction in BA. On the other hand, the hyaluronic acid derivative did not exhibit the absorption-enhancing ability under intragastric administration, probably due to the lack of stabilization effects against enzyme-susceptible biologics. The results indicated that the intrapulmonary route was suitable for maximizing the mucosal absorption of biologics, and that there was a likelihood of the intraoral route with user convenience. When somatropin was substituted with fluorescein isothiocyanate-conjugated dextran with an average M_w range of 4-70 kDa, similar phenomena were observed under intrapulmonary and intranasal administration. BA decreased with an increase in the M_w of dextran; however, the ratio of BA under enhancer-present conditions to that under enhancer-free conditions was consistently around 3, indicating that the performance of the hyaluronic acid derivative was M_w-independent, irrespective of the administration route.

Biomimetic graphene-supported ultrafine platinum nanowires for colorimetric and electrochemical detection of hydrogen peroxide

The detection of hydrogen peroxide (H₂O₂) is of great significance in environmental monitoring, enzymatic reactions, and disease diagnosis. Here we present the peptide-mediated biomimetic synthesis of ultrafine platinum nanowires (PtNWs) on graphene oxide (GO) nanosheets for the formation of functional hybrids, which show high potential for the fabrication of colorimetric and electrochemical sensors for the detection of H₂O₂ with high performance. A multifunctional peptide with the sequence KIIIIKYWYAF was designed to create peptide nanofibers (PNFs) via a controllable self-assembly process, which serves as a bridge between GO nanosheets and PtNWs to form PtNWs-PNFs/GO hybrids. On this basis, a dual-mode sensor platform for both colorimetric and electrochemical sensing of H₂O₂ was fabricated successfully. The obtained results indicate that the synthesized PtNWs-PNFs/GO hybrids could catalyze the decomposition of H₂O₂ to generate ˙OH radicals with a significant current response, and the ˙OH radicals are capable of overoxidizing 3,3',5,5',-tetramethylbenzidine (TMB), producing a blue-colored species with a distinct color change for colorimetric sensing. In addition, due to its high catalytic activity, the fabricated PtNWs-PNFs/GO hybrid-based electrochemical sensor exhibits a wider linear detection range of 0.05 μM-15 mM and a low detection limit of 0.0206 μM, which can be applied to detect H₂O₂ with high selectivity and sensitivity. Our study provides a green and environmentally friendly synthetic strategy for the preparation of biomimetic materials from PtNWs, and the fabricated colorimetric/electrochemical dual-mode H₂O₂ sensor platform will have a great impact in bioanalysis, environmental monitoring, and biomedicine.

Mechanism on antigen delivery under mucosal vaccination using cell-penetrating peptides immobilized at multiple points on polymeric platforms

We have developed an aggregate of D-octaarginine immobilized at multiple points on a co-polymer of N-vinylacetamide and acrylic acid. Previous studies revealed that immunoglobulin G and A were induced when mice were inoculated with influenza virus antigens under coadministration with the D-octaarginine-immobilized polymers as a mucosal vaccine adjuvant. Infection experiments demonstrated that mice vaccinated with a mixture of inactivated influenza viruses and the polymers were protected from infection with mouse-adapted infectious viruses. In the present study, we investigated the mechanism on antigen delivery under mucosal vaccination using the polymers. Two-hour retention of fluorescein-labeled ovalbumin (F-OVA) on the nasal mucosa was observed when applied with the polymers; nevertheless F-OVA was eliminated less than 10 min under polymer-free conditions. F-OVA mixed with the polymers was vigorously taken up into murine dendritic cells. Electrophoresis and dynamic light scattering analysis indicated that OVA interacted with the polymers. The uptake of F-OVA was hardly ever inhibited by the addition of an excess amount of intact OVA. The results suggested that viral antigens were accumulated on the mucosa and delivered into dendritic cells under basolateral membranes via dendrites extending to the mucosal surface and/or subsequent to their permeation through epithelial cells, when they were coadministered with D-octaarginine-immobilized polymers.

Nanotechnologies for the delivery of biologicals: Historical perspective and current landscape

Biological macromolecule-based therapeutics irrupted in the pharmaceutical scene generating a great hope due to their outstanding specificity and potency. However, given their susceptibility to degradation and limited capacity to overcome biological barriers new delivery technologies had to be developed for them to reach their targets. This review aims at analyzing the historical seminal advances that shaped the development of the protein/peptide delivery field, along with the emerging technologies on the lead of the current landscape. Particularly, focus is made on technologies with a potential for transmucosal systemic delivery of protein/peptide drugs, followed by approaches for the delivery of antigens as new vaccination strategies, and formulations of biological drugs in oncology, with special emphasis on mAbs. Finally, a discussion of the key challenges the field is facing, along with an overview of prospective advances are provided.

Nasal absorption enhancement of protein drugs independent to their chemical properties in the presence of hyaluronic acid modified with tetraglycine-L-octaarginine

Our previous mouse studies demonstrated that mean bioavailability of exendin-4, which is an injectable glucagon-like peptide-1 (GLP-1) analogue whose molecular weight (Mw) and isoelectric point (pI) are ca. 4.2 kDa and 4.5, respectively, administered nasally with poly(N-vinylacetamide-co-acrylic acid) (PNVA-co-AA) bearing D-octaarginine, which is a typical cell-penetrating peptide, was 20% relative to subcutaneous administration even though it was less than 1% when exendin-4 alone was given nasally. The studies also revealed that the absorption-enhancing ability of D-octaarginine-linked PNVA-co-AA for exendin-4 was statistically equivalent to that of sodium salcaprozate (SNAC), which is an absorption enhancer formulated in tablets of semaglutide approved recently as an orally available GLP-1 analogue. From a perspective of clinical application of our technology, we have separately developed hyaluronic acid modified with L-octaarginine via a tetraglycine spacer which would be degraded in biological conditions. The present study revealed that tetraglycine-L-octaarginine-linked hyaluronic acid enhanced nasal absorption of exendin-4 in mice, as did D-octaarginine-linked PNVA-co-AA. There was no significant difference in absorption-enhancing abilities between the hyaluronic acid derivative and SNAC when octreotide (Mw: ca. 1.0 kDa, pI: 8.3) and lixisenatide (Mw: ca. 4.9 kDa, pI: 9.5) were used as a model protein drug. On the other hand, SNAC did not significantly enhance nasal absorption of somatropin (Mw: ca. 22.1 kDa, pI: 5.3) when compared with absorption enhancer-free conditions. Substitution of SNAC with tetraglycine-L-octaarginine-linked hyaluronic acid resulted in a 5-fold increase in absolute bioavailability of somatropin with statistical significance. It appeared that pI hardly ever influenced absorption-enhancing abilities of both enhancers. Results indicated that our polysaccharide derivative would be a promising absorption enhancer which delivers biologics applied on the nasal mucosa into systemic circulation and was of greater advantage than SNAC for enhancing nasal absorption of protein drugs with a larger Mw.

Biodegradable Hyaluronic Acid Modified with Tetraglycine-l-octaarginine as a Safe Adjuvant for Mucosal Vaccination

We have been investigating the potential use of polymers modified with cell-penetrating peptides as an adjuvant for mucosal vaccination and have already developed nondegradable poly( N-vinylacetamide- co-acrylic acid) (PNVA- co-AA) with which d-octaarginine, a typical cell-penetrating peptide, was grafted. Our previous murine infection experiments demonstrated that immunoglobulin G (IgG) and immunoglobulin A (IgA) were induced in systemic circulation and secreted on nasal mucosa, respectively, through 4-time nasal inoculations with a mixture of influenza viral antigens and d-octaarginine-linked PNVA- co-AA at 7-day intervals, and that immunized mice were perfectly protected from homologous virus infection. In the present study, we designed novel biodegradable polymers bearing cell-penetrating peptides from a perspective of clinical application. Hyaluronic acid whose glucuronic acid was modified with tetraglycine-l-octaarginine at a monosaccharide unit ratio of 30% was successfully developed. The hyaluronic acid derivative exhibited adjuvant activities identical to PNVA- co-AA bearing either d-octaarginine or tetraglycine-d-octaarginine under the above-mentioned inoculation schedule. We further found that there was no difference in humoral immunity between the 4-time inoculations at 7-day intervals and the 2-time inoculations at 28-day intervals. Intranasal IgA induced through the latter schedule with a smaller number of inoculations, which is clinically practical, exhibited cross-reactivity beyond the subtype of viral strains. In vitro toxicity studies demonstrated that the hyaluronic acid derivative was much less toxic than the corresponding PNVA- co-AA derivatives, and that both the polymers and their metabolites did not exhibit genotoxicity. Our results suggested that tetraglycine-l-octaarginine-linked hyaluronic acid would be a clinically valuable and safe adjuvant for mucosal vaccination.