Novel ortho ester-based, pH-sensitive cationic lipid for gene deliveryin vitroandin vivo

pH-Sensitive Liposomes with Embedded 3-(isobutylamino)cholan-24-oic Acid: What Is the Possible Mechanism of Fast Cargo Release?

pH-sensitive liposomes have great potential for biomedical applications, in particular as nanocontainers for the delivery of biologically active compounds to specific areas of the human body. In this article, we discuss the possible mechanism of fast cargo release from a new type of pH-sensitive liposomes with embedded ampholytic molecular switch (AMS, 3-(isobutylamino)cholan-24-oic acid) with carboxylic anionic groups and isobutylamino cationic ones attached to the opposite ends of the steroid core. AMS-containing liposomes demonstrated the rapid release of the encapsulated substance when altering the pH of an outer solution, but the exact mechanism of the switch action has not yet been accurately determined. Here, we report on the details of fast cargo release based on the data obtained using ATR-FTIR spectroscopy as well as atomistic molecular modeling. The findings of this study are relevant to the potential application of AMS-containing pH-sensitive liposomes for drug delivery.

A critical overview of current progress for COVID-19: development of vaccines, antiviral drugs, and therapeutic antibodies

The novel coronavirus disease (COVID-19) pandemic remains a global public health crisis, presenting a broad range of challenges. To help address some of the main problems, the scientific community has designed vaccines, diagnostic tools and therapeutics for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The rapid pace of technology development, especially with regard to vaccines, represents a stunning and historic scientific achievement. Nevertheless, many challenges remain to be overcome, such as improving vaccine and drug treatment efficacies for emergent mutant strains of SARS-CoV-2. Outbreaks of more infectious variants continue to diminish the utility of available vaccines and drugs. Thus, the effectiveness of vaccines and drugs against the most current variants is a primary consideration in the continual analyses of clinical data that supports updated regulatory decisions. The first two vaccines granted Emergency Use Authorizations (EUAs), BNT162b2 and mRNA-1273, still show more than 60% protection efficacy against the most widespread current SARS-CoV-2 variant, Omicron. This variant carries more than 30 mutations in the spike protein, which has largely abrogated the neutralizing effects of therapeutic antibodies. Fortunately, some neutralizing antibodies and antiviral COVID-19 drugs treatments have shown continued clinical benefits. In this review, we provide a framework for understanding the ongoing development efforts for different types of vaccines and therapeutics, including small molecule and antibody drugs. The ripple effects of newly emergent variants, including updates to vaccines and drug repurposing efforts, are summarized. In addition, we summarize the clinical trials supporting the development and distribution of vaccines, small molecule drugs, and therapeutic antibodies with broad-spectrum activity against SARS-CoV-2 strains.

Hemiacetal-linked pH-sensitive PEG-lipids for non-viral gene delivery

Cationic lipid–DNA complexes containing a novel hemiacetal PEG-lipid for endosomal escape were characterized in terms of pH-response, stability, and biological activity.

Nanoplatforms for Targeted Stimuli-Responsive Drug Delivery: A Review of Platform Materials and Stimuli-Responsive Release and Targeting Mechanisms

To achieve the promise of stimuli-responsive drug delivery systems for the treatment of cancer, they should (1) avoid premature clearance; (2) accumulate in tumors and undergo endocytosis by cancer cells; and (3) exhibit appropriate stimuli-responsive release of the payload. It is challenging to address all of these requirements simultaneously. However, the numerous proof-of-concept studies addressing one or more of these requirements reported every year have dramatically expanded the toolbox available for the design of drug delivery systems. This review highlights recent advances in the targeting and stimuli-responsiveness of drug delivery systems. It begins with a discussion of nanocarrier types and an overview of the factors influencing nanocarrier biodistribution. On-demand release strategies and their application to each type of nanocarrier are reviewed, including both endogenous and exogenous stimuli. Recent developments in stimuli-responsive targeting strategies are also discussed. The remaining challenges and prospective solutions in the field are discussed throughout the review, which is intended to assist researchers in overcoming interdisciplinary knowledge barriers and increase the speed of development. This review presents a nanocarrier-based drug delivery systems toolbox that enables the application of techniques across platforms and inspires researchers with interdisciplinary information to boost the development of multifunctional therapeutic nanoplatforms for cancer therapy.

Understanding In Vivo Fate of Nucleic Acid and Gene Medicines for the Rational Design of Drugs

Nucleic acid and genetic medicines are increasingly being developed, owing to their potential to treat a variety of intractable diseases. A comprehensive understanding of the in vivo fate of these agents is vital for the rational design, discovery, and fast and straightforward development of the drugs. In case of intravascular administration of nucleic acids and genetic medicines, interaction with blood components, especially plasma proteins, is unavoidable. However, on the flip side, such interaction can be utilized wisely to manipulate the pharmacokinetics of the agents. In other words, plasma protein binding can help in suppressing the elimination of nucleic acids from the blood stream and deliver naked oligonucleotides and gene carriers into target cells. To control the distribution of these agents in the body, the ligand conjugation method is widely applied. It is also important to understand intracellular localization. In this context, endocytosis pathway, endosomal escape, and nuclear transport should be considered and discussed. Encapsulated nucleic acids and genes must be dissociated from the carriers to exert their activity. In this review, we summarize the in vivo fate of nucleic acid and gene medicines and provide guidelines for the rational design of drugs.

Cationic lipids for gene delivery: many players, one goal

Lipid-based carriers represent the most widely used alternative to viral vectors for gene expression and gene silencing purposes. This class of non-viral vectors is particularly attractive for their ease of synthesis and chemical modifications to endow them with desirable properties. Despite combinatorial approaches have led to the generation of a large number of cationic lipids displaying different supramolecular structures and improved behavior, additional effort is needed towards the development of more and more effective cationic lipids for transfection purposes. With this review, we seek to highlight the great progress made in the design of each and every constituent domain of cationic lipids, that is, the chemical structure of the headgroup, linker and hydrophobic moieties, and on the specific effect on the assembly with nucleic acids. Since the complexity of such systems is known to affect their performances, the role of formulation, stability and phase behavior on the transfection efficiency of such assemblies will be thoroughly discussed. Our objective is to provide a conceptual framework for the development of ever more performing lipid gene delivery vectors.

Strategies for altering lipid self-assembly to trigger liposome cargo release

While liposomes have proven to be effective drug delivery nanocarriers, their therapeutic attributes could be improved through the development of clinically viable triggered release strategies in which encapsulated drug contents could be selectively released at the sites of diseased cells. As such, a significant amount of research has been reported involving the development of stimuli-responsive liposomes and a broad range of strategies have been explored for driving content release. These have included the introduction of trigger groups at either the lipid headgroup or within the acyl chains that alter lipid self-assembly properties of known lipids as well as the rational design of lipid analogs programed to undergo conformational changes induced by events such as binding interactions. This review article describes advances in the design of stimuli-responsive liposome strategies with an eye towards emerging trends in the field.

Histone deacetylase 11 inhibits interleukin 10 in B cells of subjects with allergic rhinitis

BACKGROUND

The interleukin (IL)-10 expression in B cells plays an important role in immune tolerance. The regulation of IL-10 expression in B cells is not fully understood yet. Tumor necrosis factor (TNF) is increased in allergic rhinitis (AR) patients. This study tests a hypothesis that TNF enhances histone deacetylase (HDAC)11 expression to inhibit the expression of IL-10 in B cells of AR patients.

METHODS

Peripheral B cells were collected from healthy persons and patients with AR. The B cells were analyzed by immune assay and molecular biological approaches for the expression of IL-10.

RESULTS

The expression of HDAC11 was higher in B cells of patients with AR than that in healthy persons. The expression of IL-10 in B cells was lower in AR patients than that in healthy subjects. The levels of HDAC11 in B cells were negatively correlated with the levels of IL-10. Exposure of B cells to TNF in the culture inhibited the expression of IL-10, in which HDAC11 played a critical role in the interference with the Il10 gene transcription. Inhibition of HDAC11 restored the IL-10 expression in B cells from AR patients and attenuated the experimental AR.

CONCLUSION

TNF can suppress the expression of IL-10 in B cells via enhancing the expression of HDAC11. Inhibition of HDAC11 restores the IL-10 expression in B cells of AR subjects. HDAC11 may be a novel target for the treatment of AR.

Calcium-Responsive Liposomes via a Synthetic Lipid Switch

Liposomal drug delivery would benefit from enhanced control over content release. Here, we report a novel avenue for triggering release driven by chemical composition using liposomes sensitized to calcium-a target chosen due to its key roles in biology and disease. To demonstrate this principle, we synthesized calcium-responsive lipid switch 1, designed to undergo conformational changes upon calcium binding. The conformational change perturbs membrane integrity, thereby promoting cargo release. This was shown through fluorescence-based release assays via dose-dependent response depending on the percentage of 1 in liposomes, with minimal background leakage in controls. DLS experiments indicated dramatic changes in particle size upon treatment of liposomes containing 1 with calcium. In a comparison of ten naturally occurring metal cations, calcium provided the greatest release. Finally, STEM images showed significant changes in liposome morphology upon treatment of liposomes containing 1 with calcium. These results showcase lipid switches driven by molecular recognition principles as an exciting avenue for controlling membrane properties.

Protease-activated receptor-2 suppresses interleukin (IL)-10 expression in B cells via upregulating Bcl2L12 in patients with allergic rhinitis

BACKGROUND AND AIMS

The function of interleukin (IL)-10-producing B cells (B10 cell) is compromised in patients with allergic diseases. Protease-activated receptor (PAR)-2 has immunoregulatory functions. This study aimed to elucidate the role of PAR2 in the suppression of IL-10 expression in peripheral B cells.

METHODS

Peripheral blood B cells were collected from patients with allergic rhinitis (AR). A correlation between the expression of Bcl2-like protein 12 (Bcl2L12) and IL-10 in the B cells was analyzed. An AR mouse model was developed.

RESULTS

We observed that the expression of IL-10 was lower in the peripheral B cells from patients with airway allergy. A negative correlation was identified between the expression of IL-10 and PAR2 in B cells. Activation of PAR2 of B cells increased the expression of Bcl2L12 and suppression of LPS-induced IL-10 expression, which were inhibited by knocking down the Bcl2L12 gene. Treating B cells from AR patients with Bcl2L12-shRNA-carrying liposomes reversed the capability of IL-10 expression and the immunosuppressive function. Administration of Bcl2L12 shRNA-carrying liposomes attenuated experimental AR in mice.

CONCLUSIONS

Activation of PAR2 inhibits the expression of IL-10 in B cells, which can be reversed by treating B cells with Bcl2L12 shRNA-carrying liposomes. The data suggest that regulation of Bcl2L12 may be a novel approach in the treatment for AR.

Fliposomes: trans-2-aminocyclohexanol-based amphiphiles as pH-sensitive conformational switches of liposome membrane - a structure-activity relationship study

Recently developed lipids with the trans-2-aminocyclohexanol (TACH) moiety represent unique pH-sensitive conformational switches ("flipids") that can trigger the membrane of liposome-based drug delivery systems at lowered pH as seen in many pathological scenarios. A library of flipids with various TACH-based headgroups and hydrocarbon tails were designed, prepared, and characterized to systematically elucidate the relationship between their chemical structures and their ability to form and to trigger liposomes. Liposomes (fliposomes) consisting of a flipid, POPC and PEG-ceramide were stable at 4°C, pH 7.4 for up to several months and yet released the encapsulated fluorophore in seconds upon acidification. The colloidal properties and encapsulation efficiencies of the fliposomes depended on the structure features of the flipids such as the polarity of the headgroups and the shape and fluidity of the lipid tails. The pH-triggered release also depended on the flipid structure, where shorter linear tails yielded more efficient release. The release of fliposomes was enhanced at different narrow pH ranges, depending on the basicity of the flipid headgroup, which can be estimated either by calculated pKa or by acid/base titration of the flipids while its conformation is monitored by ¹H NMR. The structure-activity relationship of the flipids supports "lipid tail conformational shortening" as the mechanism to disrupt lipid membranes and would provide great flexibility in the design of pH-sensitive drug delivery systems.

Engineering liposomal nanoparticles for targeted gene therapy

Recent mechanistic studies have attempted to deepen our understanding of the process by which liposome-mediated delivery of genetic material occurs. Understanding the interactions between lipid nanoparticles and cells is still largely elusive. Liposome-mediated delivery of genetic material faces systemic obstacles alongside entry into the cell, endosomal escape, lysosomal degradation and nuclear uptake. Rational design approaches for targeted delivery have been developed to reduce off-target effects and enhance transfection. These strategies, which have included the modification of lipid nanoparticles with target-specific ligands to enhance intracellular uptake, have shown significant promise at the proof-of-concept stage. Control of physical and chemical specifications of liposome composition, which includes lipid-to-DNA charge, size, presence of ester bonds, chain length and nature of ligand complexation, is integral to the performance of targeted liposomes as genetic delivery agents. Clinical advances are expected to rely on such systems in the therapeutic application of liposome nanoparticle-based gene therapy. Here, we discuss the latest breakthroughs in the development of targeted liposome-based agents for the delivery of genetic material, paying particular attention to new ligand and cationic lipid design as well as recent in vivo advances.

Capacious and programmable multi-liposomal carriers

Spherical polycationic brushes (SPBs) were synthesized by grafting polycationic chains onto 100 nm polystyrene particles. These particles were exposed to unilamellar egg-lecithin (EL) liposomes with a mean diameter of 40 nm that had been rendered anionic via the presence of 10 molar% of phosphatidylserine (PS(1-)). The liposomes also contained 30 mole% of a morpholinocyclohexanol-based lipid (MOCH) that undergoes a conformational flip when the pH is decreased from 7.0 to 5.0. Mixtures of SPBs and liposomes at pH 7 gave an electrostatically-driven complex possessing, on average, about 40 liposomes for each SPB particle. It was found that the bound liposomes rapidly release much of their contents when the pH is reduced from 7.0 to 5.0 owing mostly to a MOCH conformational change that creates defects in the bilayer membrane. The drop in pH does not, however, induce a separation of the liposomes from the SPBs. Around 50-60% of the liposome contents escape before, it is reasoned, lateral and transmembrane motion of the membrane components heals the defects and prevents further release. Remarkably, the liposomes complexed with SPB release their cargo much faster than the identical but non-complexed liposomes.