Prolonged Plasma Exposure of the Kv1.3-Inhibitory Peptide HsTX1[R14A] by Subcutaneous Administration of a Poly(Lactic-co-Glycolic Acid) (PLGA) Microsphere Formulation

Activation of PTEN/P13K/AKT Signaling Pathway by miRNA-124-3p-Loaded Nanoparticles to Regulate Oxidative Stress Attenuates Cardiomyocyte Regulation and Myocardial Injury

As a common cardiovascular disease, acute myocardial infarction seriously affects the health and life of patients. miRNAs play an important role in acute myocardial infarction. Based on miRNA obtained from the previous sequencing, this study investigated whether miRNA (miR)-124-3p-loaded nanoparticles (NPs) affect the phenotype of the acute myocardial infarction (AMI) rat. Nano-miR-124-3p decreased the myocardial infarction area, improved the myocardial tissue structure, and increased the degree of fibrosis. Nano-miR-124-3p decreased apoptosis and the expression of cleaved caspase 3, indicating its role in protecting and repairing the myocardium. To further verify the action mechanism of miRNA, a potential target gene of miR-124-3p, PTEN was identified by STARBASE and further confirmed using double luciferase assays. Following cotransfection of nano-miR-124-3p and PTEN, the areas of tissue structure damage, myocardial infarction, and fibrosis were substantially elevated. The expression of cleaved caspase 3 and the apoptosis rate in the nano-miR-124-3p and PTEN cotransfection group was also significantly increased. Bioinformatics analysis revealed that miRNA-124-3 may regulate oxidative stress injury by targeting PTEN. Taken together, miR-124-3p could protect and repair myocardial tissues through targeting PTEN.

In Vitro Cell Behavior and Antibiotic Activity under Sustained Release of Doxycycline-Loaded Poly(lactic-co-glycolic acid) Microspheres

The state-of-the-art sustained drug delivery systems are related to features to improve pharmacological transport through a controlled ratio between drug release and the desired therapeutic effect. Microspheres of biodegradable polymers, such as poly(lactic-co-glycolic acid) (PLGA), play an important role in these approaches, directing the release in a specific region of interest. In this way, the encapsulation of doxycycline (DOX) as a microbial agent turns the PLGA microspheres into a potential device for the treatment of topic oral diseases. Thus, this work aimed to produce DOX-loaded PLGA microspheres and see how they interfered with mesenchymal stem cell viability and in the sustained release in antimicrobial assays. Scanning electron microscopy showed the spherical microstructured pattern, revealing assorted sized distribution, with major diameters ranging 1–3 µm. The encapsulation efficiency presented a mean of 80% in both methods to obtain the microspheres (sonication and magnetic rotation). The DOX release test revealed a gradual and continuous profile of 30–40% between 120 and 168 h. Mesenchymal stem cells cultured in PLGA with or without DOX at several concentrations revealed no effect on the cell metabolic activity. Striking morphology changes were observed by confocal microscopy after 1 to 3 days under culture. The live/dead assay indicated that when microsphere densities were increased (from 10 to 100 µg/mL) cultured cells presented an internalized pattern of microspheres in both groups of PLGA containing DOX or not, while slight cell death signals were identified nearby microsphere clusters. Microbiological assays performed by the agar diffusion test pointed out that an inhibition zone was identified in Staphylococcus aureus (S. aureus) cultures at earlier times of DOX release. Despite the well-known use of PLGA as a drug delivery vehicle, when synthesized with DOX, it presents both characteristics of the desired treatment to prevent healthy tissue damage while avoiding bacterial growth in a microenvironment with anatomical features, such as grooves, projections, and other tough conditions that favor the development of oral diseases.

Blockade of Microglial Kv1.3 Potassium Channels by the Peptide HsTX1[R14A] Attenuates Lipopolysaccharide-mediated Neuroinflammation

The expression of voltage-gated potassium Kv1.3 channels is increased in activated microglia, with non-selective blockade reported to attenuate microglial-mediated neuroinflammation. In this study, we evaluated the impact of a potent and selective peptidic blocker of Kv1.3 channels, HsTX1[R14A], on microglial-mediated neuroinflammation in vitro and in vivo. Treatment with both 0.1 and 1 µg/mL lipopolysaccharide (LPS) significantly (p < 0.05) increased Kv1.3 abundance on the surface of BV-2 microglia in association with increased levels of mRNA for tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6). The increased transcription of TNF-α and IL-6 was significantly attenuated (by 24.9 and 20.2%, respectively) by HsTX1[R14A] (100 nM). The concomitant increase in TNF-α and IL-6 release from BV-2 microglia was significantly attenuated by HsTX1[R14A] by 10.7 and 12.6%, respectively. In LPS-treated primary mouse microglia, the levels of TNF-α and nitric oxide were also attenuated by HsTX1[R14A] (26.1 and 20.4%, respectively). In an LPS-induced mouse model of neuroinflammation, both an immediate and delayed subcutaneous dose of HsTX1[R14A] (2 mg/kg) significantly reduced plasma and brain levels of the pro-inflammatory mediators TNF-α, IL-1β and IL-6, with no impact on the anti-inflammatory IL-10. These results demonstrate that HsTX1[R14A] is a promising therapeutic candidate for the treatment of diseases with a neuroinflammatory component.

The Kv1.3 K+ channel in the immune system and its "precision pharmacology" using peptide toxins

Since the discovery of the Kv1.3 voltage-gated K⁺ channel in human T cells in 1984, ion channels are considered crucial elements of the signal transduction machinery in the immune system. Our knowledge about Kv1.3 and its inhibitors is outstanding, motivated by their potential application in autoimmune diseases mediated by Kv1.3 overexpressing effector memory T cells (e.g., Multiple Sclerosis). High affinity Kv1.3 inhibitors are either small organic molecules (e.g., Pap-1) or peptides isolated from venomous animals. To date, the highest affinity Kv1.3 inhibitors with the best Kv1.3 selectivity are the engineered analogues of the sea anemone peptide ShK (e.g., ShK-186), the engineered scorpion toxin HsTx1[R14A] and the natural scorpion toxin Vm24. These peptides inhibit Kv1.3 in picomolar concentrations and are several thousand-fold selective for Kv1.3 over other biologically critical ion channels. Despite the significant progress in the field of Kv1.3 molecular pharmacology several progressive questions remain to be elucidated and discussed here. These include the conjugation of the peptides to carriers to increase the residency time of the peptides in the circulation (e.g., PEGylation and engineering the peptides into antibodies), use of rational drug design to create novel peptide inhibitors and understanding the potential off-target effects of Kv1.3 inhibition.

PLGA-based biodegradable microspheres in drug delivery: recent advances in research and application

Biodegradable microspheres have been widely used in the field of medicine due to their ability to deliver drug molecules of various properties through multiple pathways and their advantages of low dose and low side effects. Poly (lactic-co-glycolic acid) copolymer (PLGA) is one of the most widely used biodegradable material currently and has good biocompatibility. In application, PLGA with a specific monomer ratio (lactic acid and glycolic acid) can be selected according to the properties of drug molecules and the requirements of the drug release rate. PLGA-based biodegradable microspheres have been studied in the field of drug delivery, including the delivery of various anticancer drugs, protein or peptide drugs, bacterial or viral DNA, etc. This review describes the basic knowledge and current situation of PLGA biodegradable microspheres and discusses the selection of PLGA polymer materials. Then, the preparation methods of PLGA microspheres are introduced, including emulsification, microfluidic technology, electrospray, and spray drying. Finally, this review summarizes the application of PLGA microspheres in drug delivery and the treatment of pulmonary and ocular-related diseases.