Protein Corona Formation on Lipid Nanoparticles Negatively Affects the NLRP3 Inflammasome Activation

More than a delivery system: the evolving role of lipid-based nanoparticles

Lipid-based nanoparticles, including liposomes and lipid nanoparticles (LNPs), make up an important class of drug delivery systems. Their modularity enables encapsulation of a wide range of therapeutic cargoes, their ease of functionalization allows for incorporation of targeting motifs and anti-fouling coatings, and their scalability facilitates rapid translation to the clinic. While the discovery and early understanding of lipid-based nanoparticles is heavily rooted in biology, formulation development has largely focused on materials properties, such as how liposome and lipid nanoparticle composition can be altered to maximize drug loading, stability and circulation. To achieve targeted delivery and enable improved accumulation of therapeutics at target tissues or disease sites, emphasis is typically placed on the use of external modifications, such as peptide, protein, and polymer motifs. However, these approaches can increase the complexity of the nanocarrier and complicate scale up. In this review, we focus on how our understanding of lipid structure and function in biological contexts can be used to design intrinsically functional and targeted nanocarriers. We highlight formulation-based strategies, such as the incorporation of bioactive lipids, that have been used to modulate liposome and lipid nanoparticle properties and improve their functionality while retaining simple nanocarrier designs. We also highlight classes of naturally occurring lipids, their functions, and how they have been incorporated into lipid-based nanoparticles. We will additionally position these approaches into the historical context of both liposome and LNP development.

Protein corona formation on supramolecular polymer nanoparticles causes differential endosomal sorting resulting in an attenuated NLRP3 inflammasome activation

Upon introduction into biological environments, nanoparticles undergo the spontaneous formation of a dynamic protein corona, which continually evolves and significantly modifies their physicochemical properties and interactions with biological systems. This evolving protein corona can critically impact the nanoparticles' endocytic pathways and targeting efficiency, potentially altering their functional characteristics and obscuring their intended therapeutic effects. Despite considerable focus on the characterization of corona proteins and their impact on nanoparticle uptake, the intracellular processes and their effects on immunogenicity are not yet thoroughly understood. Supramolecular polymer nanoparticles (SNPs) with a highly hydrophobic core are recognized for triggering NLRP3 inflammasome activation, a key component of the innate immune system. Here, it is reported that the protein corona formation on SNPs exerts an inhibitory effect on the activation pathway of NLRP3 inflammasome. The protein corona impairs the intrinsic capacity of SNPs to induce lysosomal membrane rupture, thereby diminishing the cellular stress signals necessary for the formation of the NLRP3 inflammasome complex. Furthermore, the cells transport SNPs with an attached protein corona to recycling endosomes, where they are sorted and prepared for exocytosis. Conversely, nascent SNPs are primarily confined to late endosomes and lysosomes, leading to lysosomal rupture and inflammasome activation. This differential routing reflects the significant impact of the protein corona on the cellular handling and subsequent biological activity of nanoparticles. In summary, this study elucidates the fundamental role of the protein corona in shaping the intracellular disposition of nanoparticles, with implications for modulating their interactions with the immune system.

Intracellular processing of DNA-lipid nanoparticles: A quantitative assessment by image segmentation

Carriers for efficient delivery of nucleic acids, such as lipid nanoparticles (LNPs), have gained much attention for gene therapy applications. Intracellular processing of such nanocarriers is a complex mechanism comprising cellular internalization by endocytosis pathways, endosomal release into the cytosol, lysosomal degradation, and recycling. The endosomal escape rates of current formulations are considered low, and methods to reliably quantify endocytic events are not readily available. To address this shortcoming and to support the optimization of LNP formulations, the current study presents an automated live-cell imaging-based analysis method. Engineered HuH7 hepatic cell lines overexpressing fluorescent Galectin and Rab reporters together with lysosomal co-staining enabled qualitative and quantitative tracking of DNA-loaded LNPs. The use of two fluorescently labeled DNA-LNP formulations containing either SM-102 or ALC-0315 ionizable lipids revealed significant differences in endosomal escape rates and intracellular processing. Upon treatment, only subpopulations of the HuH7 target cells could be activated with respect to escape or recycling. Recycling inhibitors were therefore used to promote endosomal escape. These findings provide valuable insights into the timing and regulation of endocytic events, which will be instrumental to optimize therapeutic LNP formulations.

Impact of ionizable groups in star polymer nanoparticles on NLRP3 inflammasome activation

The advent of cancer nanovaccines (N.V.s) has transformed immunotherapy by using nanoparticles as biologic delivery vehicles or vaccine adjuvants. However, challenges remain due to nanoparticle-immune cell interactions. Investigating nanoparticle (N.P.) physicochemical effects on the innate immune system is crucial for safe biomaterials design. The NLRP3 inflammasome, a key innate immunity component, is implicated in many inflammatory disorders. Various nanoparticle-associated molecular patterns (NAMPs) trigger NLRP3 activation, but the combined effect of these NAMPs in a single N.P. platform is not well understood. Star polymer nanocarriers were chosen to study the impact of combined hydrophobic and ionizable groups on NLRP3 activation. Star polymers offer stable self-assembly, high drug/gene encapsulation, and enhanced cellular internalization. We designed 4-arm star random copolymers with constant hydrophobic moiety and varied ionizable groups to evaluate their NLRP3 activation in macrophages. The study revealed differences in cytokine release and cell death linked to ionizable groups, providing insights for selecting safe, immunomodulatory biomaterials.

Muco-Penetrating Lipid Nanoparticles Having a Liquid Core for Enhanced Intranasal mRNA Delivery

Intranasal delivery of mRNA vaccines offers promising opportunities to combat airborne viruses like SARS-CoV-2 by provoking mucosal immunity, which not only defends against respiratory infection but also prevents contagious transmission. However, the development of nasal mRNA vaccines has been hampered by the lack of effective means to overcome the mucus barrier. Herein, ionizable lipid-incorporated liquid lipid nanoparticles (iLLNs) capable of delivering mRNA cargo across airway mucosa are designed. Adjusting the ratios of ionizable and cationic lipids allows fine-tuning of the pKa of iLLNs to the range of nasal mucosal pH (5.5-6.5), thus facilitating mucus penetration via the formation of near-neutral, PEGylated muco-inert surfaces. When nasally administered to mice, the top candidate iLLN-2/mRNA complexes enable about 60-fold greater reporter gene expression in the nasal cavity, compared to the benchmark mRNA-lipid nanoparticles (ALC-LNP) having the same lipid composition as that of BNT162b2 vaccine. Moreover, a prime-boost intranasal immunization of iLLN-2/mRNA complexes elicits a greater magnitude of SARS-CoV-2 spike-specific mucosal IgA and IgG response than ALC-LNP, without triggering any noticeable inflammatory reactions. Taken together, these results provide useful insights for the design of nasally deliverable mRNA formulations for prophylactic applications.

Frit-inlet asymmetric flow field-flow fractionation for the analysis of lipid nanoparticle-protein interactions

Research into nanoparticle interactions with biomolecules has become increasingly important in nanomedicine. While lipid nanoparticles (LNPs) are widely used as drug delivery systems, there remains a gap in understanding their fate in circulation, which is crucial for selecting appropriate lipids during formulation development. This study is the first to use Asymmetric Flow Field Flow Fractionation (AF4) to compare two types of LNPs: MC3-LNPs and SM-102-LNPs, and their interactions with a model protein, bovine serum albumin (BSA). AF4 offers high-resolution separation, with the ability to simultaneously perform multiparametric inline analysis with multiple detectors. In this study, the impact of LNP size, morphology and PDI on BSA corona formation were examined using inline multiangle light scattering (MALS) and dynamic light scattering (DLS). AF4 separation revealed two subpopulations for MC3-LNPs, while SM102-LNPs exhibited a single population. Analysis of shape factor indicated a shape factor of 0.783 for SM-102-BSA and 0.741 and 0.795 (peak 1 and 2) for MC3-BSA, confirming interaction between LNPs and BSA. Both LNPs exhibited LNP-BSA induced aggregation. Overall, this study demonstrates the effectiveness of AF4, particularly when hyphenated with multidetector systems, for simultaneously separating LNPs from complex biological media and studying LNP-protein interactions.

Shear-Stress Initiates Signal Two of NLRP3 Inflammasome Activation in LPS-Primed Macrophages through Piezo1

The innate immune system is tightly regulated by a complex network of chemical signals triggered by pathogens, cellular damage, and environmental stimuli. While it is well-established that changes in the extracellular environment can significantly influence the immune response to pathogens and damage-associated molecules, there remains a limited understanding of how changes in environmental stimuli specifically impact the activation of the NLRP3 inflammasome, a key component of innate immunity. Here, we demonstrated how shear stress can act as Signal 2 in the NLRP3 inflammasome activation pathway by treating LPS-primed immortalized bone marrow-derived macrophages (iBMDMs) with several physiologically relevant magnitudes of shear stress to induce inflammasome activation. We demonstrated that magnitudes of shear stress within 1.0 to 50 dyn/cm2 were able to induce ASC speck formation, while 50 dyn/cm2 was sufficient to induce significant calcium signaling, gasdermin-D cleavage, caspase-1 activity, and IL-1β secretion, all hallmarks of inflammasome activation. Utilizing NLRP3 and caspase-1 knockout iBMDMs, we demonstrated that the NLRP3 inflammasome was primarily activated as a result of shear stress exposure. Quantitative polymerase chain reaction (qPCR), ELISA, and a small molecule inhibitor study aided us in demonstrating that expression of Piezo1, NLRP3, gasdermin-D, IL-1β, and CCL2 secretion were all upregulated in iBMDMs treated with shear stress. This study provides a foundation for further understanding the interconnected pathogenesis of chronic inflammatory diseases and the ability of shear stress to play a role in their progression.

Protein corona formed on lipid nanoparticles compromises delivery efficiency of mRNA cargo

Lipid nanoparticles (LNPs) are the most clinically advanced nonviral RNA-delivery vehicles, though challenges remain in fully understanding how LNPs interact with biological systems. In vivo , proteins form an associated corona on LNPs that redefines their physicochemical properties and influences delivery outcomes. Despite its importance, the LNP protein corona is challenging to study owing to the technical difficulty of selectively recovering soft nanoparticles from biological samples. Herein, we developed a quantitative, label-free mass spectrometry-based proteomics approach to characterize the protein corona on LNPs. Critically, this protein corona isolation workflow avoids artifacts introduced by the presence of endogenous nanoparticles in human biofluids. We applied continuous density gradient ultracentrifugation for protein-LNP complex isolation, with mass spectrometry for protein identification normalized to protein composition in the biofluid alone. With this approach, we quantify proteins consistently enriched in the LNP corona including vitronectin, C-reactive protein, and alpha-2-macroglobulin. We explore the impact of these corona proteins on cell uptake and mRNA expression in HepG2 human liver cells, and find that, surprisingly, increased levels of cell uptake do not correlate with increased mRNA expression in part likely due to protein corona-induced lysosomal trafficking of LNPs. Our results underscore the need to consider the protein corona in the design of LNP-based therapeutics.

Abstract Figure

An investigation of the effect of the protein corona on the cellular uptake of nanoliposomes under flow conditions using quartz crystal microgravimetry with dissipation

When nanoparticle delivery systems are immersed in biological fluids, a complex assembly of proteins forms on their surface, creating a protein corona. The protein corona alters the physicochemical properties, toxicity, biodistribution, cellular uptake, and immune response of the nanoparticles, and consequently, their therapeutic efficacy. Currently, there is a lack of in vitro methods to assess the effects of the protein corona on nanoparticle uptake under dynamic flow and assess their binding kinetics in real-time. Here, we introduce quartz crystal microbalance with dissipation (QCM-D) as an in vitro technique, capable of incorporating dynamic flow, to study the effect of the protein corona on the binding of nanoliposome (NLP) formulations to cell surfaces as a first step in their cellular uptake. The interactions of four NLP formulations (low PEGylated, high PEGylated, negatively charged and positively charged NLPs) with A375 melanoma and THP1 cell lines were assessed by QCM-D, before and after the formation of a protein corona. Through real-time recording of the frequency and dissipation shifts (Δf and ΔD, respectively), the QCM-D results provided strong evidence of the role of the protein corona in the cellular interaction of these NLP formulations, with a variation in their adsorption kinetics depending on their initial composition. NLP's attachment to the cell surface was the lowest for PEGylated NLPs (<5%), while the positively charged NLPs showed the highest cellular attachment (≈100%), regardless of the presence of the protein corona or cell type. The effect of the protein corona was more pronounced for the negatively charged NLPs, where a significant reduction in the NLP attachment was observed. To complement the QCM-D data on the NLP attachment and to determine whether the NLP attachment leads to cellular uptake, confocal microscopy and flow cytometry were used to confirm NLP uptake by A375 and THP1 cells. Proteomic analysis revealed a differential composition of the protein corona on the various NLPs with possible implications for their sequestration and cellular uptake. Collectively, the findings suggest that QCM-D can be an important tool to study the binding of NLP formulations or other nanoparticles with cell membranes under dynamic flow, which very often differs from nanoparticle uptake under static conditions.

Dendritic cell activation by iron oxide nanoparticles depends on the extracellular environment

Nanoparticles can exert immune modulating effects in a host depending on composition, mode of administration, and type of disease. Although the specific mechanisms of nanoparticle-induced immune responses remain unclear, their uptake by macrophages and other phagocytic innate immune cells is considered to be a key event. Our objective here was to ascertain if nanoparticle-mediated activation of dendritic cells (DCs) occurs in vitro or in vivo when exposed to hydroxyethyl starch-coated iron oxide nanoparticles. For the present studies, our choice of nanoparticles, animal model, and experimental design is motivated by our previously published observations that systemic exposure can induce antitumor adaptive immune responses in mouse models of metastatic breast cancer. Here, we began by assessing the potential toxicity of systemic exposure to commercially available starch-coated Bionized Nanoferrite® nanoparticles (BP) by measuring body weight, complete blood count, and enzyme parameters in healthy FVB/NJ mice after repeated BP dosing. We observed no evidence of toxicity at doses up to 25 mg Fe per mouse, five-fold higher than those used in subsequent in vivo experiments. We then measured the expression of surface maturation markers (CD86, MHC II) in DCs incubated with BP in vitro. Although DCs cultured with BP revealed high levels of nanoparticle uptake, neither JAWSII dendritic cells nor bone marrow derived dendritic cells (BMDCs) showed significant changes in marker expression to indicate stimulation of maturation and effector function. To assess whether BP interactions in vivo produced different effects, we analyzed CD80, CD86, and MHC II expression of DCs recovered from the livers, spleens, bone marrows, and lymph nodes of mice injected once with BP (5 mg Fe). Interestingly, only DCs in spleens and bone marrow cells responded to BP exposure. DCs recovered from other organs showed no evidence of increased activation. These findings highlight complex interactions between living systems and nanoparticles, and their potential to mediate context-specific and selective activation of innate immune cells. Our study also emphasizes that results obtained from in vitro experiments must be interpreted with caution, as they may not faithfully represent responses in living systems.

Delivery Aspects for Implementing siRNA Therapeutics for Blood Diseases

Hematological disorders result in significant health consequences, and traditional therapies frequently entail adverse reactions without addressing the root cause. A potential solution for hematological disorders characterized by gain-of-function mutations lies in the emergence of small interfering RNA (siRNA) molecules as a therapeutic option. siRNAs are a class of RNA molecules composed of double-stranded RNAs that can degrade specific mRNAs, thereby inhibiting the synthesis of underlying disease proteins. Therapeutic interventions utilizing siRNA can be tailored to selectively target genes implicated in diverse hematological disorders, including sickle cell anemia, β-thalassemia, and malignancies such as lymphoma, myeloma, and leukemia. The development of efficient siRNA silencers necessitates meticulous contemplation of variables such as the RNA backbone, stability, and specificity. Transportation of siRNA to specific cells poses a significant hurdle, prompting investigations of diverse delivery approaches, including chemically modified forms of siRNA and nanoparticle formulations with various biocompatible carriers. This review delves into the crucial role of siRNA technology in targeting and treating hematological malignancies and disorders. It sheds light on the latest research, development, and clinical trials, detailing how various pharmaceutical approaches leverage siRNA against blood disorders, mainly concentrating on cancers. It outlines the preferred molecular targets and physiological barriers to delivery while emphasizing the growing potential of various therapeutic delivery methods. The need for further research is articulated in the context of overcoming the shortcomings of siRNA in order to enrich discussions around siRNA's role in managing blood disorders and aiding the scientific community in advancing more targeted and effective treatments.

Distinct Inflammatory Programs Underlie the Intramuscular Lipid Nanoparticle Response

Developments in mRNA/lipid nanoparticle (LNP) technology have advanced the fields of vaccinology and gene therapy, raising questions about immunogenicity. While some mRNA/LNPs generate an adjuvant-like environment in muscle tissue, other mRNA/LNPs are distinct in their capacity for multiple rounds of therapeutic delivery. We evaluate the adjuvancy of components of mRNA/LNPs by phenotyping cellular infiltrate at injection sites, tracking uptake by immune cells, and assessing the inflammatory state. Delivery of 9 common, but chemically distinct, LNPs to muscle revealed two classes of inflammatory gene expression programs: inflammatory (Class A) and noninflammatory (Class B). We find that intramuscular injection with Class A, but not Class B, empty LNPs (eLNPs) induce robust neutrophil infiltration into muscle within 2 h and a diverse myeloid population within 24 h. Single-cell RNA sequencing revealed SM-102-mediated expression of inflammatory chemokines by myeloid infiltrates within muscle 1 day after injection. Surprisingly, we found direct transfection of muscle infiltrating myeloid cells and splenocytes 24 h after intramuscular mRNA/LNP administration. Transfected myeloid cells within the muscle exhibit an activated phenotype 24 h after injection. Similarly, directly transfected splenic lymphocytes and dendritic cells (DCs) are differentially activated by Class A or Class B containing mRNA/LNP. Within the splenic DC compartment, type II conventional DCs (cDC2s) are directly transfected and activated by Class A mRNA/LNP. Together, we show that mRNA and LNPs work synergistically to provide the necessary innate immune stimuli required for effective vaccination. Importantly, this work provides a design framework for vaccines and therapeutics alike.

Study of Hard Protein Corona on Lipid Surface of Composite Nanoconstruction

The composition of the protein corona covering any nanoparticle (NP) when it enters a biological fluid determines the parameters of the NP's interaction with the body. To "control" these parameters, it is important to know the composition of the protein corona, the determination of which is a complex task associated with the two-layer organization of the corona (hard and soft coronas). In a previous publication, we reported obtaining lipid-coated NPs with a full protein corona, isolating them, and proving the presence of the corona on the surface of the NPs. This work reports on the preparation, isolation, and purification of lipid-coated NPs bearing a hard corona. The protein corona composition was determined by using the LC-MS/MS method. Thirty-seven serum proteins were identified with a high degree of reliability. The hard corona contained various apolipoproteins, including apolipoprotein E, which can potentially affect the penetration of NPs into the cell.

Effects of excipients on the interactions of self-emulsifying drug delivery systems with human blood plasma and plasma membranes

Due to its versatility in formulation and manufacturing, self-emulsifying drug delivery systems (SEDDS) can be used to design parenteral formulations. Therefore, it is necessary to understand the effects of excipients on the behavior of SEDDS formulations upon parenteral administration, particularly their interactions with blood plasma and cell membranes. In this study, we prepared three neutrally charged SEDDS formulations composed of medium-chain triglycerides as the oil phase, polyoxyl-35 castor oil (EL35) and polyethylene glycol (15)-hydroxystearate (HS15) as the nonionic surfactants, medium-chain mono- and diglycerides as the co-surfactant, and propylene glycol as the co-solvent. The cationic surfactant, didodecyldimethylammonium bromide (DDA), and the anionic surfactant, sodium deoxycholate (DEO), were added to the neutral SEDDS preconcentrates to obtain cationic and anionic SEDDS, respectively. SEDDS were incubated with human blood plasma and recovered by size exclusion chromatography. Data showed that SEDDS emulsion droplets can bind plasma protein to different extents depending on their surface charge and surfactant used. At pH 7.4, the least protein binding was observed with anionic SEDDS. Positive charges increased protein binding. SEDDS stabilized by HS15 can adsorb more plasma protein and induce more plasma membrane disruption activity than SEDDS stabilized by EL35. These effects were more pronounced with the HS15 + DDA combination. The addition of DDA and DEO to SEDDS increased plasma membrane disruption (PMD) activities, and DDA (1% w/w) was more active than DEO (2% w/w). PMD activities of SEDDS were concentration-dependent and vanished at appropriate dilution ratios.

Sprayable inflammasome-inhibiting lipid nanorods in a polymeric scaffold for psoriasis therapy

Localized delivery of inflammasome inhibitors in phagocytic macrophages could be promising for psoriasis treatment. The present work demonstrates the development of non-spherical lipid nanoparticles, mimicking pathogen-like shapes, consisting of an anti-inflammatory inflammasome inhibiting lipid (pyridoxine dipalmitate) as a trojan horse. The nanorods inhibit inflammasome by 3.8- and 4.5-fold compared with nanoellipses and nanospheres, respectively. Nanorods reduce apoptosis-associated speck-like protein and lysosomal rupture, restrain calcium influx, and mitochondrial reactive oxygen species. Dual inflammasome inhibitor (NLRP3/AIM-2-IN-3) loaded nanorods cause synergistic inhibition by 21.5- and 59-folds compared with nanorods and free drug, respectively alongside caspase-1 inhibition. The NLRP3/AIM-2-IN-3 nanorod when transformed into a polymeric scaffold, simultaneously and effectively inhibits RNA levels of NLRP3, AIM2, caspase-1, chemokine ligand-2, gasdermin-D, interleukin-1β, toll-like receptor 7/ 8, and IL-17A by 6.4-, 1.6-, 2.0-, 13.0-, 4.2-, 24.4-, 4.3-, and 1.82-fold, respectively in psoriatic skin in comparison to Imiquimod positive control group in an in-vivo psoriasis-like mice model.

Endocytosis: the match point of nanoparticle-based cancer therapy

Nanomedicine has inspired a ground-breaking strategy for cancer therapy. By intelligently assembling diverse moieties to form nanoparticles, numerous functionalities such as controlled release, synergistic efficiency, and in situ killing can be achieved. The emerging nanoparticles have been designed with elevated targeting efficiency as targeting cancer cells is the primary requirement for nanoparticles. However, effective targeting does not guarantee therapeutic effects as endocytosis is a prerequisite for nanoparticles to exert effects. The recent decade has witnessed the rapid development of endocytosis-oriented nanoparticles, and this review subtly analyzes, categorizes, and exemplifies these nanoparticles according to their biological internalization patterns, and the correlation between the endocytosis mechanism and the property of nanoparticles is bridged. Based on the interdisciplinary vision, the present challenges and future perspectives of nanoparticle design for successful endocytosis are discussed, highlighting the potential strategies for the future development of endocytosis-oriented nanoparticles, thus facilitating the endocytosis-oriented strategy from bench to bedside. The undeniable fact is that endocytosis-oriented nanoparticles will definitely bring new blood to the next generation of advanced cancer therapies.

The menace of severe adverse events and deaths associated with viral gene therapy and its potential solution

Over the past decade, in vivo gene replacement therapy has significantly advanced, resulting in market approval of numerous therapeutics predominantly relying on adeno-associated viral vectors (AAV). While viral vectors have undeniably addressed several critical healthcare challenges, their clinical application has unveiled a range of limitations and safety concerns. This review highlights the emerging challenges in the field of gene therapy. At first, we discuss both the role of biological barriers in viral gene therapy with a focus on AAVs, and review current landscape of in vivo human gene therapy. We delineate advantages and disadvantages of AAVs as gene delivery vehicles, mostly from the safety perspective (hepatotoxicity, cardiotoxicity, neurotoxicity, inflammatory responses etc.), and outline the mechanisms of adverse events in response to AAV. Contribution of every aspect of AAV vectors (genomic structure, capsid proteins) and host responses to injected AAV is considered and substantiated by basic, translational and clinical studies. The updated evaluation of recent AAV clinical trials and current medical experience clearly shows the risks of AAVs that sometimes overshadow the hopes for curing a hereditary disease. At last, a set of established and new molecular and nanotechnology tools and approaches are provided as potential solutions for mitigating or eliminating side effects. The increasing number of severe adverse reactions and, sadly deaths, demands decisive actions to resolve the issue of immune responses and extremely high doses of viral vectors used for gene therapy. In response to these challenges, various strategies are under development, including approaches aimed at augmenting characteristics of viral vectors and others focused on creating secure and efficacious non-viral vectors. This comprehensive review offers an overarching perspective on the present state of gene therapy utilizing both viral and non-viral vectors.

Mechanisms and Delivery of tRNA Therapeutics

Transfer ribonucleic acid (tRNA) therapeutics will provide personalized and mutation specific medicines to treat human genetic diseases for which no cures currently exist. The tRNAs are a family of adaptor molecules that interpret the nucleic acid sequences in our genes into the amino acid sequences of proteins that dictate cell function. Humans encode more than 600 tRNA genes. Interestingly, even healthy individuals contain some mutant tRNAs that make mistakes. Missense suppressor tRNAs insert the wrong amino acid in proteins, and nonsense suppressor tRNAs read through premature stop signals to generate full length proteins. Mutations that underlie many human diseases, including neurodegenerative diseases, cancers, and diverse rare genetic disorders, result from missense or nonsense mutations. Thus, specific tRNA variants can be strategically deployed as therapeutic agents to correct genetic defects. We review the mechanisms of tRNA therapeutic activity, the nature of the therapeutic window for nonsense and missense suppression as well as wild-type tRNA supplementation. We discuss the challenges and promises of delivering tRNAs as synthetic RNAs or as gene therapies. Together, tRNA medicines will provide novel treatments for common and rare genetic diseases in humans.

Looking back, moving forward: protein corona of lipid nanoparticles

Lipid nanoparticles (LNPs) are commonly employed for drug delivery owing to their considerable drug-loading capacity, low toxicity, and excellent biocompatibility. Nevertheless, the formation of protein corona (PC) on their surfaces significantly influences the drug's in vivo fate (such as absorption, distribution, metabolism, and elimination) upon administration. PC denotes the phenomenon wherein one or multiple strata of proteins adhere to the external interface of nanoparticles (NPs) or microparticles within the biological milieu, encompassing ex vivo fluids (e.g., serum-containing culture media) and in vivo fluids (such as blood and tissue fluids). Hence, it is essential to claim the PC formation behaviors and mechanisms on the surface of LNPs. This overview provided a comprehensive examination of crucial aspects related to such issues, encompassing time evolution, controllability, and their subsequent impacts on LNPs. Classical studies of PC generation on the surface of LNPs were additionally integrated, and its decisive role in shaping the in vivo fate of LNPs was explored. The mechanisms underlying PC formation, including the adsorption theory and alteration theory, were introduced to delve into the formation process. Subsequently, the existing experimental outcomes were synthesized to offer insights into the research and application facets of PC, and it was concluded that the manipulation of PC held substantial promise in the realm of targeted delivery.

Impact of physicochemical properties on biological effects of lipid nanoparticles: Are they completely safe

Lipid nanoparticles (LNPs) are promising materials and human-use approved excipients, with manifold applications in biomedicine. Researchers have tended to focus on improving the pharmacological efficiency and organ targeting of LNPs, while paid relatively less attention to the negative aspects created by their specific physicochemical properties. Here, we discuss the impacts of LNPs' physicochemical properties (size, surface hydrophobicity, surface charge, surface modification and lipid composition) on the adsorption-transportation-distribution-clearance processes and bio-nano interactions. In addition, since there is a lack of review emphasizing on toxicological profiles of LNPs, this review outlined immunogenicity, inflammation, hemolytic toxicity, cytotoxicity and genotoxicity induced by LNPs and the underlying mechanisms, with the aim to understand the properties that underlie the biological effects of these materials. This provides a basic strategy that increased efficacy of medical application with minimized side-effects can be achieved by modulating the physicochemical properties of LNPs. Therefore, addressing the effects of physicochemical properties on toxicity induced by LNPs is critical for understanding their environmental and health risks and will help clear the way for LNPs-based drugs to eventually fulfill their promise as a highly effective therapeutic agents for diverse diseases in clinic.

Quantitative analysis of mRNA-lipid nanoparticle stability in human plasma and serum by size-exclusion chromatography coupled with dual-angle light scattering

Understanding the stability of mRNA loaded lipid nanoparticles (mRNA-LNPs) is imperative for their clinical development. Herein, we propose the use of size-exclusion chromatography coupled with dual-angle light scattering (SEC-MALS) as a new approach to assessing mRNA-LNP stability in pure human serum and plasma. By applying a dual-column configuration to attenuate interference from plasma components, SEC-MALS was able to elucidate the degradation kinetics and physical property changes of mRNA-LNPs, which have not been observed accurately by conventional dynamic light scattering techniques. Interestingly, both serum and plasma had significantly different impacts on the molecular weight and radius of gyration of mRNA-LNPs, suggesting the involvement of clotting factors in desorption of lipids from mRNA-LNPs. We also discovered that a trace impurity (~1 %) in ALC-0315, identified as its O-tert-butyloxycarbonyl-protected form, greatly diminished mRNA-LNP stability in serum. These results demonstrated the potential utility of SEC-MALS for optimization and quality control of LNP formulations.

NLRP3 Inflammasome Inhibitors for Antiepileptogenic Drug Discovery and Development

Epilepsy is one of the most prevalent and serious brain disorders and affects over 70 million people globally. Antiseizure medications (ASMs) relieve symptoms and prevent the occurrence of future seizures in epileptic patients but have a limited effect on epileptogenesis. Addressing the multifaceted nature of epileptogenesis and its association with the Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-mediated neuroinflammation requires a comprehensive understanding of the underlying mechanisms of these medications for the development of targeted therapeutic strategies beyond conventional antiseizure treatments. Several types of NLRP3 inhibitors have been developed and their effect has been validated both in in vitro and in vivo models of epileptogenesis. In this review, we discuss the advances in understanding the regulatory mechanisms of NLRP3 activation as well as progress made, and challenges faced in the development of NLRP3 inhibitors for the treatment of epilepsy.

Nanoparticle-mediated co-delivery of inflammasome inhibitors provides protection against sepsis

The NLRP3 inflammasome, a multiprotein complex responsible for triggering the release of pro-inflammatory cytokines, plays a crucial role in inducing the inflammatory response associated with sepsis. While small molecule inhibitors of the NLRP3 inflammasome have been investigated for sepsis management, delivering NLRP3 inhibitors has been accompanied by several challenges, primarily related to the drug formulation, delivery route, stability, and toxicity. Many existing inflammasome inhibitors either show higher liver toxicity or require a high dosage to efficiently impede the inflammasome complex assembly. Moreover, the potential synergistic effects of combining multiple inflammasome inhibitors in sepsis therapy remain largely unexplored. Therefore, a rational approach is essential for presenting the potential administration of NLRP3 small molecule inhibitors to inhibit NLRP3 inflammasome activation effectively. In this context, we present a lipid nanoparticle-based dual-drug delivery system loaded with MCC 950 and disulfiram, demonstrating markedly higher efficiency compared to an equivalent amount of free-drug combinations and individual drug nanoparticles in vitro. This combination therapy substantially improved the in vivo survival rate of mice for LPS-induced septic peritonitis. Additionally, the synergistic approach illustrated a significant reduction in the expression of active caspase-1 as well as IL-1β inhibition integral components in the NLRP3 pathway. This study underscores the importance of integrating combination therapies facilitated by nanoparticle delivery to address the limitations of small molecule inflammasome inhibitors.

Flow-Induced Shear Stress Primes NLRP3 Inflammasome Activation in Macrophages via Piezo1

The NLRP3 inflammasome is a crucial component of the innate immune system, playing a pivotal role in initiating and regulating the body's inflammatory response to various pathogens and cellular damage. Environmental stimuli, such as temperature, pH level, and nutrient availability, can influence the behavior and functions of innate immune cells, including immune cell activity, proliferation, and cytokine production. However, there is limited understanding regarding how mechanical forces, like shear stress, govern the intrinsic inflammatory reaction, particularly the activation of the NLRP3 inflammasome, and how shear stress impacts NLRP3 inflammasome activation through its capacity to induce alterations in gene expression and cytokine secretion. Here, we investigated how shear stress can act as a priming signal in NLRP3 inflammasome activation by exposing immortalized bone marrow-derived macrophages (iBMDMs) to numerous physiologically relevant magnitudes of shear stress before chemically inducing inflammasome activation. We demonstrated that shear stress of large magnitudes was able to prime iBMDMs more effectively for inflammasome activation compared to lower shear stress magnitudes, as quantified by the percentage of cells where ASC-CFP specks formed and IL-1β secretion, the hallmarks of inflammasome activation. Testing this in NLRP3 and caspase-1 knockout iBMDMs showed that the NLRP3 inflammasome was primarily primed for activation due to shear stress exposure. Quantitative polymerase chain reaction (qPCR) and a small-molecule inhibitor study mechanistically determined that shear stress regulates the NLRP3 inflammasome by upregulating Piezo1, IKKβ, and NLRP3. These findings offer insights into the mechanistic relationship among physiological shear stresses, inflammasome activation, and their impact on the progression of inflammatory diseases and their interconnected pathogenesis.