Blood-brain Barrier Translocation Research Articles

Regulation of neuroinflammation in Alzheimer's disease via nanoparticle-loaded phytocompounds with anti-inflammatory and autophagy-inducing properties.

Alzheimer's disease (AD) is characterized by neuroinflammation linked to amyloid β (Aβ) aggregation and phosphorylated tau (τ) protein in neurofibrillary tangles (NFTs). Key elements in Aβ production and NFT assembly, like γ-secretase and p38 mitogen-activated protein kinase (p38MAPK), contribute to neuroinflammation. In addition, impaired proteosomal and autophagic pathways increase Aβ and τ aggregation, leading to neuronal damage. Conventional neuroinflammation drugs have limitations due to unidirectional therapeutic approaches and challenges in crossing the Blood-Brain Barrier (BBB). Clinical trials for non-steroidal anti-inflammatory drugs (NSAIDs) and other therapeutics remain uncertain. Novel strategies addressing the complex pathogenesis and BBB translocation are needed to effectively tackle AD-related neuroinflammation. The current scenario demands for a much-sophisticated theranostic measures which could be achieved via customized engineering and designing of novel nanotherapeutics. As, these therapeutics functions as a double edge sword, having the efficiency of unambiguous targeting, multiple drug delivery and ability to cross BBB proficiently. Inclusion criteria involve selecting recent, English-language studies from the past decade (2013-2023) that explore the regulation of neuroinflammation in neuroinflammation, Alzheimer's disease, amyloid β, tau protein, nanoparticles, autophagy, and phytocompounds. Various study types, including clinical trials, experiments, and reviews, were considered. Exclusion criteria comprised non-relevant publication types, studies unrelated to Alzheimer's disease or phytocompounds, those with methodological flaws, duplicates, and studies with inaccessible data. In this study, polymeric nanoparticles loaded with specific phytocompounds and coated with an antibody targeting the transferrin receptor (anti-TfR) present on BBB. Thereafter, the engineered nanoparticles with the ability to efficiently traverse the BBB and interact with target molecules within the brain, could induce autophagy, a cellular process crucial for neuronal health, and exhibit potent anti-inflammatory effects. Henceforth, the proposed combination of desired phytocompounds, polymeric nanoparticles, and anti-TfR coating presents a promising approach for targeted drug delivery to the brain, with potential implications in neuroinflammatory conditions such as Alzheimer's disease.

Oral delivery of brain-targeted miltefosine-loaded alginate nanoparticles functionalized with polysorbate 80 for the treatment of cryptococcal meningitis.

To develop alginate nanoparticles functionalized with polysorbate 80 (P80) as miltefosine carriers for brain targeting in the oral treatment of cryptococcal meningitis. Miltefosine-loaded alginate nanoparticles functionalized or not with P80 were produced by an emulsification/external gelation method and the physicochemical characteristics were determined. The haemolytic activity and cytotoxic and antifungal effects of nanoparticles were assessed in an in vitro model of the blood-brain barrier (BBB). A murine model of disseminated cryptococcosis was used for testing the efficacy of oral treatment with the nanoparticles. In addition, serum biomarkers were measured for toxicity evaluation and the nanoparticle biodistribution was analysed. P80-functionalized nanoparticles had a mean size of ∼300 nm, a polydispersity index of ∼0.4 and zeta potential around -50 mV, and they promoted a sustained drug release. Both nanoparticles were effective in decreasing the infection process across the BBB model and reduced drug cytotoxicity and haemolysis. In in vivo cryptococcosis, the oral treatment with two doses of P80 nanoparticles reduced the fungal burden in the brain and lungs, while the non-functionalized nanoparticles reduced fungal amount only in the lungs, and the free miltefosine was not effective. In addition, the P80-functionalization improved the nanoparticle distribution in several organs, especially in the brain. Finally, treatment with nanoparticles did not cause any toxicity in animals. These results support the potential use of P80-functionalized alginate nanoparticles as miltefosine carriers for non-toxic and effective alternative oral treatment, enabling BBB translocation and reduction of fungal infection in the brain.

Penetrating the Blood-Brain Barrier with New Peptide-Porphyrin Conjugates Having anti-HIV Activity.

Passing through the blood-brain barrier (BBB) to treat neurological conditions is one of the main hurdles in modern medicine. Many drugs with promising in vitro profiles become ineffective in vivo due to BBB restrictive permeability. In particular, this includes drugs such as antiviral porphyrins, with the ability to fight brain-resident viruses causing diseases such as HIV-associated neurocognitive disorders (HAND). In the last two decades, BBB shuttles, particularly peptide-based ones, have shown promise in carrying various payloads across the BBB. Thus, peptide–drug conjugates (PDCs) formed by covalent attachment of a BBB peptide shuttle and an antiviral drug may become key therapeutic tools in treating neurological disorders of viral origin. In this study, we have used various approaches (guanidinium, phosphonium, and carbodiimide-based couplings) for on-resin synthesis of new peptide–porphyrin conjugates (PPCs) with BBB-crossing and potential antiviral activity. After careful fine-tuning of the synthetic chemistry, DIC/oxyma has emerged as a preferred method, by which 14 different PPCs have been made and satisfactorily characterized. The PPCs are prepared by coupling a porphyrin carboxyl group to an amino group (either N-terminal or a Lys side chain) of the peptide shuttle and show effective in vitro BBB translocation ability, low cytotoxicity toward mouse brain endothelial cells, and low hemolytic activity. Three of the PPCs, MP-P5, P4-MP, and P4-L-MP, effectively inhibiting HIV infectivity in vitro, stand out as most promising. Their efficacy against other brain-targeting viruses (Dengue, Zika, and SARS-CoV-2) is currently under evaluation, with preliminary results confirming that PPCs are a promising strategy to treat viral brain infections.

To What Extent Do Fluorophores Bias the Biological Activity of Peptides? A Practical Approach Using Membrane-Active Peptides as Models.

The characterization of biologically active peptides relies heavily on the study of their efficacy, toxicity, mechanism of action, cellular uptake, or intracellular location, using both in vitro and in vivo studies. These studies frequently depend on the use of fluorescence-based techniques. Since most peptides are not intrinsically fluorescent, they are conjugated to a fluorophore. The conjugation may interfere with peptide properties, thus biasing the results. The selection of the most suitable fluorophore is highly relevant. Here, a comprehensive study with blood–brain barrier (BBB) peptide shuttles (PepH3 and PepNeg) and antimicrobial peptides (AMPs) (vCPP2319 and Ctn[15-34]), tested as anticancer peptides (ACPs), having different fluorophores, namely 5(6)-carboxyfluorescein (CF), rhodamine B (RhB), quasar 570 (Q570), or tide fluor 3 (TF3) attached is presented. The goal is the evaluation of the impact of the selected fluorophores on peptide performance, applying routinely used techniques to assess cytotoxicity/toxicity, secondary structure, BBB translocation, and cellular internalization. Our results show that some fluorophores significantly modulate peptide activity when compared with unlabeled peptides, being more noticeable in hydrophobic and charged fluorophores. This study highlights the need for a careful experimental design for fluorescently labeled molecules, such as peptides.

Lipid Nanoformulations in the Treatment of Neuropsychiatric Diseases: An Approach to Overcome the Blood Brain Barrier.

Neuropsychiatric diseases primarily characterized by dementia stand third in the global list of diseases causing disability. The poor water solubility, erratic oral absorption, low bioavailability, poor intestinal absorption, and the impeding action of the blood-brain barrier (BBB) are the major factors limiting the therapeutic feasibility of the antipsychotics. Only a small percentage of antipsychotics reaches the therapeutic target site, which warrants administration of high doses, consequently leading to unwanted side-effects. Hence the main struggle for the effective treatment of neuropsychiatric diseases occurs "at the gates" of the brain, which can be mitigated with the use of a nanotechnology-based platform. The goal of this review is to undertake a comprehensive study about the role of lipid nanoformulations in facilitating the delivery of antipsychotics across BBB along with the available in vitro and in vivo evidence. Lipid nanoformulations have attained great popularity for the delivery of therapeutics into the brain. Their nanosize helps in overcoming the biological barriers, thereby providing easy BBB translocation of the drugs. Besides, they offer numerous advantages like controlled and targeted drug release, minimizing drug efflux, long storage stability, augmented bioavailability, and reduced adverse drug effects to attain an optimal therapeutic drug concentration in the brain. Moreover, employing alternative routes of administration has also shown promising results. Thus, it can be concluded that the lipid nanoformulations bear immense potential in overcoming the challenges associated with the treatment of neuropsychiatric disorders. However, the area warrants further clinical studies to ensure their commercialization, which could revolutionize the treatment of neuropsychiatric diseases in the coming decades.

DPepH3, an Improved Peptide Shuttle for Receptor-independent Transport Across the Blood-Brain Barrier.

The use of peptides as drug carriers across the blood-brain barrier (BBB) has increased significantly during the last decades. PepH3, a seven residue sequence (AGILKRW) derived from the α-helical domain of the dengue virus type-2 capsid protein, translocates across the BBB with very low toxicity. Somehow predictably from its size and sequence, PepH3 is degraded in serum relatively fast. Among strategies to increase peptide half-life (t1/2), the use of the enantiomer (wholly made of D-amino acid residues) can be quite successful if the peptide interacts with a target in non-stereospecific fashion. The goal of this work was the development of a more proteolytic-resistant peptide, while keeping the translocation properties. The serum stability, cytotoxicity, in vitro BBB translocation, and internalization mechanism of DPepH3 was assessed and compared to the native peptide. DPepH3 demonstrates a much longer t1/2 compared to PepH3. We also confirm that BBB translocation is receptor-independent, which fully validates the enantiomer strategy chosen. In fact, we demonstrate that internalization occurs trough macropinocytosis. In addition, the enantiomer demonstrates to be non-cytotoxic towards endothelial cells as PepH3. DPepH3 shows excellent translocation and internalization properties, safety, and improved stability. Taken together, our results place DPepH3 at the forefront of the second generation of BBB shuttles.

Antibodies for the Treatment of Brain Metastases, a Dream or a Reality?

The incidence of brain metastases (BM) in cancer patients is increasing. After diagnosis, overall survival (OS) is poor, elicited by the lack of an effective treatment. Monoclonal antibody (mAb)-based therapy has achieved remarkable success in treating both hematologic and non-central-nervous system (CNS) tumors due to their inherent targeting specificity. However, the use of mAbs in the treatment of CNS tumors is restricted by the blood–brain barrier (BBB) that hinders the delivery of either small-molecules drugs (sMDs) or therapeutic proteins (TPs). To overcome this limitation, active research is focused on the development of strategies to deliver TPs and increase their concentration in the brain. Yet, their molecular weight and hydrophilic nature turn this task into a challenge. The use of BBB peptide shuttles is an elegant strategy. They explore either receptor-mediated transcytosis (RMT) or adsorptive-mediated transcytosis (AMT) to cross the BBB. The latter is preferable since it avoids enzymatic degradation, receptor saturation, and competition with natural receptor substrates, which reduces adverse events. Therefore, the combination of mAbs properties (e.g., selectivity and long half-life) with BBB peptide shuttles (e.g., BBB translocation and delivery into the brain) turns the therapeutic conjugate in a valid approach to safely overcome the BBB and efficiently eliminate metastatic brain cells.

Protein-functionalized nanoparticles derived from end-functional polymers and polymer prodrugs for crossing the blood-brain barrier

Nanoparticles may provide a viable way for neuroprotective drugs to cross the blood–brain barrier (BBB), which limits the passage of most drugs from the peripheral circulation to the brain. Heterotelechelic polymer prodrugs comprising a neuroprotective model drug (adenosine) and a maleimide functionality were synthesized by the “drug-initiated” approach and subsequent nitroxide exchange reaction. Nanoparticles were obtained by nanoprecipitation and exhibited high colloidal stability with diameters in the 162–185 nm range and narrow size distributions. Nanoparticles were then covalently surface-conjugated to different proteins (albumin, α2-macroglobulin and fetuin A) to test their capability of enhancing BBB translocation. Their performances in terms of endothelial permeability and cellular uptake in an in vitro BBB model were compared to that of similar nanoparticles with surface-adsorbed proteins, functionalized or not with the drug. It was shown that bare NPs (i.e., NPs not surface-functionalized with proteins) without the drug exhibited significant permeability and cellular uptake, which were further enhanced by NP surface functionalization with α2-macroglobulin. However, the presence of the drug at the polymer chain-end prevented efficient passage of all types of NPs through the BBB model, likely due to adecrease in the hydrophobicity of the nanoparticle surface and alteration of the protein binding/coupling, respectively. These results established a new and facile synthetic approach for the surface-functionalization of polymer nanoparticles for brain delivery purposes.

An insight into the ligand–receptor interactions involved in the translocation of pathogens across blood–brain barrier

Traversal of pathogen across the blood-brain barrier (BBB) is an essential step for central nervous system (CNS) invasion. Pathogen traversal can occur paracellularly, transcellularly, and/or in infected phagocytes (Trojan horse mechanism). To trigger the translocation processes, mainly through paracellular and transcellular ways, interactions between protein molecules of pathogen and BBB are inevitable. Simply, it takes two to tango: both host receptors and pathogen ligands. Underlying molecular basis of BBB translocation of various pathogens has been revealed in the last decade, and a plethora of experimental data on protein-protein interactions has been created. This review compiles these data and should give insights into the ligand-receptor interactions that occur during BBB translocation. Further, it sheds light on cell signaling events triggered in response to ligand-receptor interaction. Understanding of the molecular principles of pathogen-host interactions that are involved in traversal of the BBB should contribute to develop new vaccine and drug strategies to prevent CNS infections.

OspA-CD40 dyad: ligand-receptor interaction in the translocation of neuroinvasive Borrelia across the blood-brain barrier

Lyme borreliosis is the most widespread vector-borne disease in temperate zones of Europe and North America. Although the infection is treatable, the symptoms are often overlooked resulting in infection of the neuronal system. In this work we uncover the underlying molecular mechanism of borrelial translocation across the blood-brain barrier (BBB). We demonstrate that neuroinvasive strain of Borrelia readily crosses monolayer of brain-microvascular endothelial cells (BMECs) in vitro and BBB in vivo. Using protein-protein interaction assays we found that CD40 of BMECs and OspA of Borrelia are the primary molecules in transient tethering of Borrelia to endothelium. OspA of neuroinvasive Borrelia, but not of non-neuroinvasive strain, binds CD40. Furthermore, only the neuroinvasive Borrelia and its recombinant OspA activated CD40-dependent pathway in BMECs and induced expression of integrins essential for stationary adhesion. Demonstration of the CD40-ligand interactions may provide a new possible perspective on molecular mechanisms of borrelial BBB translocation process.