Small-Angle X-ray Scattering Unveils the Internal Structure of Lipid Nanoparticles

Lipid nanoparticles own a remarkable potential in nanomedicine, only partially disclosed. While the clinical use of liposomes and cationic lipid-nucleic acid complexes is well-established, liquid lipid nanoparticles (nanoemulsions), solid lipid nanoparticles, and nanostructured lipid carriers have even greater potential. However, they face obstacles in being used in clinics due to a lack of understanding about the molecular mechanisms controlling their drug loading and release, interactions with the biological environment (such as the protein corona), and shelf-life stability. To create effective drug delivery carriers and successfully translate bench research to clinical settings, it is crucial to have a thorough understanding of the internal structure of lipid nanoparticles. Through synchrotron small-angle X-ray scattering experiments, we determined the spatial distribution and internal structure of the nanoparticles' lipid, surfactant, and the water in them. The nanoparticles themselves have a barrel-like shape that consists of coplanar lipid platelets (specifically cetyl palmitate) that are partially covered by polysorbate 80 surfactant and retain a small amount of hydration water. Although the platelet structure was expected, the presence of surfactant molecules forming sticky patches between adjacent platelets challenges the classical core-shell model used to describe solid lipid nanoparticles. Additionally, the surfactant partially covers the water-nanoparticle interface, allowing certain lipid regions to come into direct contact with surrounding water. These structural features play a significant role in drug loading and release, biological fluid interaction, and nanoparticle stability, making these findings valuable for the rational design of lipid-based nanoparticles.Comment: 22 pages, 11 figure

Pulmonary Interstitial Matrix and Lung Fluid Balance From Normal to the Acutely Injured Lung

This review analyses the mechanisms by which lung fluid balance is strictly controlled in the air-blood barrier (ABB). Relatively large trans-endothelial and trans-epithelial Starling pressure gradients result in a minimal flow across the ABB thanks to low microvascular permeability aided by the macromolecular structure of the interstitial matrix. These edema safety factors are lost when the integrity of the interstitial matrix is damaged. The result is that small Starling pressure gradients, acting on a progressively expanding alveolar barrier with high permeability, generate a high transvascular flow that causes alveolar flooding in minutes. We modeled the trans-endothelial and trans-epithelial Starling pressure gradients under control conditions, as well as under increasing alveolar pressure (Palv) conditions of up to 25 cmH2O. We referred to the wet-to-dry weight (W/D) ratio, a specific index of lung water balance, to be correlated with the functional state of the interstitial structure. W/D averages ∼5 in control and might increase by up to ∼9 in severe edema, corresponding to ∼70% loss in the integrity of the native matrix. Factors buffering edemagenic conditions include: (i) an interstitial capacity for fluid accumulation located in the thick portion of ABB, (ii) the increase in interstitial pressure due to water binding by hyaluronan (the “safety factor” opposing the filtration gradient), and (iii) increased lymphatic flow. Inflammatory factors causing lung tissue damage include those of bacterial/viral and those of sterile nature. Production of reactive oxygen species (ROS) during hypoxia or hyperoxia, or excessive parenchymal stress/strain [lung overdistension caused by patient self-induced lung injury (P-SILI)] can all cause excessive inflammation. We discuss the heterogeneity of intrapulmonary distribution of W/D ratios. A W/D ∼6.5 has been identified as being critical for the transition to severe edema formation. Increasing Palv for W/D > 6.5, both trans-endothelial and trans-epithelial gradients favor filtration leading to alveolar flooding. Neither CT scan nor ultrasound can identify this initial level of lung fluid balance perturbation. A suggestion is put forward to identify a non-invasive tool to detect the earliest stages of perturbation of lung fluid balance before the condition becomes life-threatening

Precision medicine: a new era for inner ear diseases

The inner ear is the organ responsible for hearing and balance. Inner ear dysfunction can be the result of infection, trauma, ototoxic drugs, genetic mutation or predisposition. Often, like for Ménière disease, the cause is unknown. Due to the complex access to the inner ear as a fluid-filled cavity within the temporal bone of the skull, effective diagnosis of inner ear pathologies and targeted drug delivery pose significant challenges. Samples of inner ear fluids can only be collected during surgery because the available procedures damage the tiny and fragile structures of the inner ear. Concerning drug administration, the final dose, kinetics, and targets cannot be controlled. Overcoming these limitations is crucial for successful inner ear precision medicine. Recently, notable advancements in microneedle technologies offer the potential for safe sampling of inner ear fluids and local treatment. Ultrasharp microneedles can reach the inner ear fluids with minimal damage to the organ, collect μl amounts of perilymph, and deliver therapeutic agents in loco. This review highlights the potential of ultrasharp microneedles, combined with nano vectors and gene therapy, to effectively treat inner ear diseases of different etiology on an individual basis. Though further research is necessary to translate these innovative approaches into clinical practice, these technologies may represent a true breakthrough in the clinical approach to inner ear diseases, ushering in a new era of personalized medicine

Airborne Particulate Matter and SARS-CoV-2 Partnership: Virus Hitchhiking, Stabilization and Immune Cell Targeting—A Hypothesis

It is widely assumed that the spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in humans occurs through close contact with an infected person, short-range transmission through respirable droplets from an infected individuals' cough or sneeze, and aerosolized airborne droplets in long-range (over a few meters) transmission (1). Large respirable droplets (>5 μm) rapidly settle out of the air, whereas virus-laden small droplets (200 signatories, has further stressed the importance of inhalation exposure to viruses in respirable droplets at short to medium distances (up to several meters) (2). In contrast to the inhalation mode of viral transmission through airborne respirable droplets, here we speculate an additional role for settled and airborne particulate matter (PM) not only in viral transmission through inhalation and ingestion, but also in promoting immunity through antigen delivery, adjuvanticity and trained immunity

Milan PM1 Induces Adverse Effects on Mice Lungs and Cardiovascular System

Recent studies have suggested a link between inhaled particulate matter (PM) exposure and increased mortality and morbidity associated with cardiorespiratory diseases. Since the response to PM1 has not yet been deeply investigated, its impact on mice lungs and cardiovascular system is here examined. A repeated exposure to Milan PM1 was performed on BALB/c mice. The bronchoalveolar lavage fluid (BALf) and the lung parenchyma were screened for markers of inflammation (cell counts, tumor necrosis factor-α (TNF-α); macrophage inflammatory protein-2 (MIP-2); heme oxygenase-1 (HO-1); nuclear factor kappa-light-chain-enhancer of activated B cells p50 subunit (NFκB-p50); inducible nitric oxide synthetase (iNOS); endothelial-selectin (E-selectin)), cytotoxicity (lactate dehydrogenase (LDH); alkaline phosphatase (ALP); heat shock protein 70 (Hsp70); caspase-8-p18), and a putative pro-carcinogenic marker (cytochrome 1B1 (Cyp1B1)). Heart tissue was tested for HO-1, caspase-8-p18, NFκB-p50, iNOS, E-selectin, and myeloperoxidase (MPO); plasma was screened for markers of platelet activation and clot formation (soluble platelet-selectin (sP-selectin); fibrinogen; plasminogen activator inhibitor 1 (PAI-1)). PM1 triggers inflammation and cytotoxicity in lungs. A similar cytotoxic effect was observed on heart tissues, while plasma analyses suggest blood-endothelium interface activation. These data highlight the importance of lung inflammation in mediating adverse cardiovascular events following increase in ambient PM1 levels, providing evidences of a positive correlation between PM1 exposure and cardiovascular morbidity

Na+-activated K+ current contributes to postexcitatory hyperpolarization in neocortical intrinsically bursting neurons

The ionic mechanisms underlying the termination of action-potential (AP) bursts and postburst afterhyperpolarization (AHP) in intrinsically bursting (IB) neocortical neurons were investigated by performing intracellular recordings in thin slices of rat sensorimotor cortex. The blockade of Ca(2+)-activated K(+) currents enhanced postburst depolarizing afterpotentials, but had inconsistent and minor effects on the amplitude and duration of AHPs. On the contrary, experimental conditions resulting in reduction of voltage-dependent Na(+) entry into the cells caused a significant decrease of AHP amplitude. Slice perfusion with a modified artificial cerebrospinal fluid in which LiCl (40 mM) partially replaced NaCl had negligible effects on the properties of individual APs, whereas it consistently increased burst length and led to an approximately 30% reduction in the amplitude of AHPs following individual bursts or short trains of stimulus-induced APs. Experiments performed by partially replacing Na(+) ions with choline revealed a comparable reduction in AHP amplitude associated with an inhibition of bursting activity. Moreover, in voltage-clamp experiments carried out in both in situ and acutely isolated neurons, partial substitution of extracellular NaCl with LiCl significantly and reversibly reduced the amplitude of K(+) currents evoked by depolarizing stimuli above-threshold for Na(+)-current activation. The above effect of Na(+)-to-Li(+) substitution was not seen when voltage-gated Na(+) currents were blocked with TTX, indicating the presence of a specific K(+)-current component activated by voltage-dependent Na(+) (but not Li(+)) influx. The above findings suggest that a Na(+)-activated K(+) current recruited by the Na(+) entry secondary to burst discharge significantly contributes to AHP generation and the maintenance of rhythmic burst recurrence during sustained depolarizations in neocortical IB neurons