Retinoic acid-loaded liposomes induce human mucosal CD103+ dendritic cells that inhibit Th17 cells and drive regulatory T-cell development in vitro.

The active vitamin A metabolite, all-trans-retinoic acid (RA), primes precursor dendritic cells (DCs) into a mucosal phenotype with tolerogenic properties characterized by the expression of integrin CD103. CD103+ DCs can counteract pathogenic Th1 and Th17 in inflammatory bowel disease (IBD) or celiac disease (CD). Tolerogenic manipulation of DCs using nanoparticles carrying tolerogenic adjuvants and disease-specific antigens is a valuable treatment strategy to induce antigen-specific mucosal tolerance in vivo. Here, we investigated the effects of RA-loaded liposomes on human DC phenotype and function, including DC-driven T-cell development, both during the generation of monocyte-derived DCs (moDCs) as well as by priming immature moDCs. RA liposomes drove CD103+ DC differentiation as well as ALDH1A2 expression in DCs. Neutrophil-dependent Th17 cell development was reduced by RA-liposome-differentiated and RA-liposome-primed DCs. Moreover, RA liposome treatment shifted T-cell development toward a Th2 cell profile. Importantly, RA liposomes induced the development of IL-10-producing and FoxP3+ regulatory T cells (Tregs) of various Treg subsets, including ICOS+ Tregs, that were potent inhibitors of bystander memory T-cell proliferation. Taken together, RA-loaded liposomes could be a novel treatment avenue for IBD or CD patients.

Resident Memory T Cells in the Atherosclerotic Lesion Associate With Reduced Macrophage Content and Increased Lesion Stability.

BACKGROUND: Tissue resident memory T (TRM) cells are a T-cell subset that resides at the site of prior antigen recognition to protect the body against reoccurring encounters. Besides their protective function, TRM cells have also been implicated in inflammatory disorders. TRM cells are characterized by the expression of CD69 and transcription factors Hobit (homolog of Blimp-1 [B lymphocyte-induced maturation protein 1] in T cells) and Blimp-1. As the majority of T cells in the arterial intima expresses CD69, TRM cells may contribute to the pathogenesis of atherosclerosis as well. Here, we aimed to assess the presence and potential role of TRM cells in atherosclerosis. METHODS: To identify TRM cells in human atherosclerotic lesions, a single-cell RNA-sequencing data set was interrogated, and T-cell phenotypes were compared with that of integrated predefined TRM cells. The presence and phenotype of TRM in atherosclerotic lesions was corroborated using a mouse model that enabled tracking of Hobit-expressing TRM cells. To explore the function of TRM cells during atherogenesis, RAG1-/- (recombination activating gene 1 deficient) LDLr-/- (low-density lipoprotein receptor knockout) mice received a bone marrow transplant from HobitKO/CREBlimp-1flox/flox mice, which exhibit abrogated TRM cell formation, whereafter the mice were fed a Western-type diet for 10 weeks. RESULTS: Human atherosclerotic lesions contained T cells that exhibited a TRM cell-associated gene signature. Moreover, a fraction of these T cells clustered together with predefined TRM cells upon integration. The presence of Hobit-expressing TRM cells in the atherosclerotic lesion was confirmed in mice. These lesion-derived TRM cells were characterized by the expression of CD69 and CD49α. Moreover, we demonstrated that this small T-cell subset significantly affects lesion composition, by reducing the amount of intralesional macrophages and increasing collagen content. CONCLUSIONS: TRM cells, characterized by the expression of CD69 and CD49α, constitute a minor population in atherosclerotic lesions and are associated with increased lesion stability in a Hobit and Blimp-1 knockout mouse model.

Virus-Associated CD8+ T-Cells Are Not Activated Through Antigen-Mediated Interaction Inside Atherosclerotic Lesions.

INTRODUCTION: Viral infections have been associated with the progression of atherosclerosis and CD8+ T-cells directed against common viruses, such as influenza, Epstein-Barr virus, and cytomegalovirus, have been detected inside human atherosclerotic lesions. These virus-specific CD8+ T-cells have been hypothesized to contribute to the development of atherosclerosis; however, whether they affect disease progression directly remains unclear. In this study, we aimed to characterize the activation status of virus-specific CD8+ T-cells in the atherosclerotic lesion. METHODS: The presence, clonality, tissue enrichment, and phenotype of virus-associated CD8+ T-cells in atherosclerotic lesions were assessed by exploiting bulk T-cell receptor-ß sequencing and single-cell T-cell receptor (α and ß) sequencing datasets on human endarterectomy samples and patient-matched blood samples. To investigate if virus-specific CD8+ T-cells can be activated through T-cell receptor stimulation in the atherosclerotic lesion, the immunopeptidome of human plaques was determined. RESULTS: Virus-associated CD8+ T-cells accumulated more in the atherosclerotic lesion (mean=2.0%), compared with patient-matched blood samples (mean=1.4%; P=0.05), and were more clonally expanded and tissue enriched in the atherosclerotic lesion in comparison with nonassociated CD8+ T-cells from the lesion. Single-cell T-cell receptor sequencing and flow cytometry revealed that these virus-associated CD8+ T-cells were phenotypically highly similar to other CD8+ T-cells in the lesion and that both exhibited a more activated phenotype compared with circulating T-cells. Interestingly, virus-associated CD8+ T-cells are unlikely to be activated through antigen-specific interactions in the atherosclerotic lesion, as no virus-derived peptides were detected on HLA-I in the lesion. CONCLUSIONS: This study suggests that virus-specific CD8+ T-cells are tissue enriched in atherosclerotic lesions; however, their potential contribution to inflammation may involve antigen-independent mechanisms.

Immunoproteasomal Inhibition With ONX-0914 Attenuates Atherosclerosis and Reduces White Adipose Tissue Mass and Metabolic Syndrome in Mice.

BACKGROUND: Atherosclerosis is the major underlying pathology of cardiovascular disease and is driven by dyslipidemia and inflammation. Inhibition of the immunoproteasome, a proteasome variant that is predominantly expressed by immune cells and plays an important role in antigen presentation, has been shown to have immunosuppressive effects. METHODS: We assessed the effect of ONX-0914, an inhibitor of the immunoproteasomal catalytic subunits LMP7 (proteasome subunit ß5i/large multifunctional peptidase 7) and LMP2 (proteasome subunit ß1i/large multifunctional peptidase 2), on atherosclerosis and metabolism in LDLr-/- and APOE*3-Leiden.CETP mice. RESULTS: ONX-0914 treatment significantly reduced atherosclerosis, reduced dendritic cell and macrophage levels and their activation, as well as the levels of antigen-experienced T cells during early plaque formation, and Th1 cells in advanced atherosclerosis in young and aged mice in various immune compartments. Additionally, ONX-0914 treatment led to a strong reduction in white adipose tissue mass and adipocyte progenitors, which coincided with neutrophil and macrophage accumulation in white adipose tissue. ONX-0914 reduced intestinal triglyceride uptake and gastric emptying, likely contributing to the reduction in white adipose tissue mass, as ONX-0914 did not increase energy expenditure or reduce total food intake. Concomitant with the reduction in white adipose tissue mass upon ONX-0914 treatment, we observed improvements in markers of metabolic syndrome, including lowered plasma triglyceride levels, insulin levels, and fasting blood glucose. CONCLUSIONS: We propose that immunoproteasomal inhibition reduces 3 major causes underlying cardiovascular disease, dyslipidemia, metabolic syndrome, and inflammation and is a new target in drug development for atherosclerosis treatment.

Noncovalent Conjugation of OVA323 to ELP Micelles Increases Immune Response.

Subunit vaccines would benefit from a safe particle-based adjuvant. Elastin-like polypeptide (ELP)-based micelles are interesting candidate adjuvants due to their well-defined size and easy modification with protein-based cargo. Coiled coils can facilitate noncovalent modifications, while potentially enhancing antigen delivery through interaction with cell membranes. ELP micelles comprise ELP diblock copolymers that self-assemble above a critical micelle temperature. In this study, an amphiphilic ELP was conjugated to peptide "K", which forms a heterodimeric coiled-coil complex with peptide "E". Self-assembled "covalent" micelles containing ELP-OVA323 (i.e., model antigen OVA323 conjugated to ELP), "coiled-coil" micelles containing ELP-K/E-OVA323 and "hybrid" micelles containing ELP-K and ELP-OVA323 were shown to be monodisperse and spherical. Dendritic cells (DCs) were exposed to all micelle compositions, and T-cell proliferation was investigated. The presence of ELP-K enhanced micelle uptake and subsequent DC maturation, resulting in enhanced CD4+ T-cell proliferation, which makes ELPs with coiled coil-associated antigens a promising vaccine platform.

Intradermal Vaccination with PLGA Nanoparticles via Dissolving Microneedles and Classical Injection Needles.

PURPOSE: A dissolving microneedle array (dMNA) is a vaccine delivery device with several advantages over conventional needles. By incorporating particulate adjuvants in the form of poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) into the dMNA, the immune response against the antigen might be enhanced. This study aimed to prepare PLGA-NP-loaded dMNA and to compare T-cell responses induced by either intradermally injected aqueous-PLGA-NP formulation or PLGA-NP-loaded dMNA in mice. METHODS: PLGA NPs were prepared with microfluidics, and their physicochemical characteristics with regard to encapsulation efficiencies of ovalbumin (OVA) and CpG oligonucleotide (CpG), zeta potentials, polydispersity indexes, and sizes were analysed. PLGA NPs incorporated dMNA was produced with three different dMNA formulations by using the centrifugation method, and the integrity of PLGA NPs in dMNAs was evaluated. The immunogenicity was evaluated in mice by comparing the T-cell responses induced by dMNA and aqueous formulations containing ovalbumin and CpG (OVA/CpG) with and without PLGA NP. RESULTS: Prepared PLGA NPs had a size of around 100 nm. The dMNA formulations affected the particle integrity, and the dMNA with poly(vinyl alcohol) (PVA) showed almost no aggregation of PLGA NPs. The PLGA:PVA weight ratio of 1:9 resulted in 100% of penetration efficiency and the fastest dissolution in ex-vivo human skin (< 30 min). The aqueous formulation with soluble OVA/CpG and the aqueous-PLGA-NP formulation with OVA/CpG induced the highest CD4 + T-cell responses in blood and spleen cells. CONCLUSIONS: PLGA NPs incorporated dMNA was successfully fabricated and the aqueous formulation containing PLGA NPs induce superior CD4+ and CD8+ T-cell responses.

Modulation of immune responses using adjuvants to facilitate therapeutic vaccination.

Therapeutic vaccination offers great promise as an intervention for a diversity of infectious and non-infectious conditions. Given that most chronic health conditions are thought to have an immune component, vaccination can at least in principle be proposed as a therapeutic strategy. Understanding the nature of protective immunity is of vital importance, and the progress made in recent years in defining the nature of pathological and protective immunity for a range of diseases has provided an impetus to devise strategies to promote such responses in a targeted manner. However, in many cases, limited progress has been made in clinical adoption of such approaches. This in part results from a lack of safe and effective vaccine adjuvants that can be used to promote protective immunity and/or reduce deleterious immune responses. Although somewhat simplistic, it is possible to divide therapeutic vaccine approaches into those targeting conditions where antibody responses can mediate protection and those where the principal focus is the promotion of effector and memory cellular immunity or the reduction of damaging cellular immune responses as in the case of autoimmune diseases. Clearly, in all cases of antigen-specific immunotherapy, the identification of protective antigens is a vital first step. There are many challenges to developing therapeutic vaccines beyond those associated with prophylactic diseases including the ongoing immune responses in patients, patient heterogeneity, and diversity in the type and stage of disease. If reproducible biomarkers can be defined, these could allow earlier diagnosis and intervention and likely increase therapeutic vaccine efficacy. Current immunomodulatory approaches related to adoptive cell transfers or passive antibody therapy are showing great promise, but these are outside the scope of this review which will focus on the potential for adjuvanted therapeutic active vaccination strategies.

Tuning the Cross-Linking Density and Cross-Linker in Core Cross-Linked Polymeric Micelles and Its Effects on the Particle Stability in Human Blood Plasma and Mice.

Core cross-linked polymeric micelles (CCPMs) are designed to improve the therapeutic profile of hydrophobic drugs, reduce or completely avoid protein corona formation, and offer prolonged circulation times, a prerequisite for passive or active targeting. In this study, we tuned the CCPM stability by using bifunctional or trifunctional cross-linkers and varying the cross-linkable polymer block length. For CCPMs, amphiphilic thiol-reactive polypept(o)ides of polysarcosine-block-poly(S-ethylsulfonyl-l-cysteine) [pSar-b-pCys(SO2Et)] were employed. While the pCys(SO2Et) chain lengths varied from Xn = 17 to 30, bivalent (derivatives of dihydrolipoic acid) and trivalent (sarcosine/cysteine pentapeptide) cross-linkers have been applied. Asymmetrical flow field-flow fraction (AF4) displayed the absence of aggregates in human plasma, yet for non-cross-linked PM and CCPMs cross-linked with dihydrolipoic acid at [pCys(SO2Et)]17, increasing the cross-linking density or the pCys(SO2Et) chain lengths led to stable CCPMs. Interestingly, circulation time and biodistribution in mice of non-cross-linked and bivalently cross-linked CCPMs are comparable, while the trivalent peptide cross-linkers enhance the circulation half-life from 11 to 19 h.

Lung airway-surveilling CXCR3(hi) memory CD8(+) T cells are critical for protection against influenza A virus.

Inducing memory CD8(+) T cells specific for conserved antigens from influenza A virus (IAV) is a potential strategy for broadly protective vaccines. Here we show that memory CD8(+) T cells in the airways played an important role in early control of IAV. Expression of the chemokine receptor CXCR3 was critical for memory CD8(+) T cells to populate the airways during the steady state and vaccination approaches were designed to favor the establishment of memory CD8(+) T cells in the airways. Specifically, we found that interleukin-12 (IL-12) signaling shortly after immunization limited CXCR3 expression on memory CD8(+) T cells. Neutralization of IL-12 or adjuvants that did not induce high amounts of IL-12 enhanced CXCR3 expression, sustained airway localization of memory CD8(+) T cells, and resulted in superior protection against IAV.

Microanatomy of the Human Atherosclerotic Plaque by Single-Cell Transcriptomics.

RATIONALE: Atherosclerotic lesions are known for their cellular heterogeneity, yet the molecular complexity within the cells of human plaques has not been fully assessed. OBJECTIVE: Using single-cell transcriptomics and chromatin accessibility, we gained a better understanding of the pathophysiology underlying human atherosclerosis. METHODS AND RESULTS: We performed single-cell RNA and single-cell ATAC sequencing on human carotid atherosclerotic plaques to define the cells at play and determine their transcriptomic and epigenomic characteristics. We identified 14 distinct cell populations including endothelial cells, smooth muscle cells, mast cells, B cells, myeloid cells, and T cells and identified multiple cellular activation states and suggested cellular interconversions. Within the endothelial cell population, we defined subsets with angiogenic capacity plus clear signs of endothelial to mesenchymal transition. CD4+ and CD8+ T cells showed activation-based subclasses, each with a gradual decline from a cytotoxic to a more quiescent phenotype. Myeloid cells included 2 populations of proinflammatory macrophages showing IL (interleukin) 1B or TNF (tumor necrosis factor) expression as well as a foam cell-like population expressing TREM2 (triggering receptor expressed on myeloid cells 2) and displaying a fibrosis-promoting phenotype. ATACseq data identified specific transcription factors associated with the myeloid subpopulation and T cell cytokine profiles underlying mutual activation between both cell types. Finally, cardiovascular disease susceptibility genes identified using public genome-wide association studies data were particularly enriched in lesional macrophages, endothelial, and smooth muscle cells. CONCLUSIONS: This study provides a transcriptome-based cellular landscape of human atherosclerotic plaques and highlights cellular plasticity and intercellular communication at the site of disease. This detailed definition of cell communities at play in atherosclerosis will facilitate cell-based mapping of novel interventional targets with direct functional relevance for the treatment of human disease.

Protective role for the N-terminal domain of α-dystroglycan in Influenza A virus proliferation.

α-Dystroglycan (α-DG) is a highly glycosylated basement membrane receptor that is cleaved by the proprotein convertase furin, which releases its N-terminal domain (α-DGN). Before cleavage, α-DGN interacts with the glycosyltransferase LARGE1 and initiates functional O-glycosylation of the mucin-like domain of α-DG. Notably, α-DGN has been detected in a wide variety of human bodily fluids, but the physiological significance of secreted α-DGN remains unknown. Here, we show that mice lacking α-DGN exhibit significantly higher viral titers in the lungs after Influenza A virus (IAV) infection (strain A/Puerto Rico/8/1934 H1N1), suggesting an inability to control virus load. Consistent with this, overexpression of α-DGN before infection or intranasal treatment with recombinant α-DGN prior and during infection, significantly reduced IAV titers in the lungs of wild-type mice. Hemagglutination inhibition assays using recombinant α-DGN showed in vitro neutralization of IAV. Collectively, our results support a protective role for α-DGN in IAV proliferation.

Hypercholesterolemia Induces a Mast Cell-CD4+ T Cell Interaction in Atherosclerosis.

Mast cells (MCs) are potent innate immune cells that aggravate atherosclerosis through the release of proinflammatory mediators inside atherosclerotic plaques. Similarly, CD4+ T cells are constituents of the adaptive immune response and accumulate within the plaques following lipid-specific activation by APCs. Recently it has been proposed that these two cell types can interact in a direct manner. However, no indication of such an interaction has been investigated in the context of atherosclerosis. In our study, we aimed to examine whether MCs can act as APCs in atherosclerosis, thereby modulating CD4+ T cell responses. We observed that MCs increased their MHC class II expression under hyperlipidemic conditions both in vivo and in vitro. Furthermore, we showed that MCs can present Ags in vivo via MHC class II molecules. Serum from high-fat diet-fed mice also enhanced the expression of the costimulatory molecule CD86 on cultured MCs, whereas OVA peptide-loaded MCs increased OT-II CD4+ T cell proliferation in vitro. The aortic CD4+ and TH1 cell content of atherosclerotic mice that lack MCs was reduced as compared with their wild-type counterparts. Importantly, we identified MCs that express HLA-DR in advanced human atheromata, indicating that these cells are capable of Ag presentation within human atherosclerotic plaques. Therefore, in this artice, we show that MCs may directly modulate adaptive immunity by acting as APCs in atherosclerosis.

Smchd1 haploinsufficiency exacerbates the phenotype of a transgenic FSHD1 mouse model.

In humans, a copy of the DUX4 retrogene is located in each unit of the D4Z4 macrosatellite repeat that normally comprises 8-100 units. The D4Z4 repeat has heterochromatic features and does not express DUX4 in somatic cells. Individuals with facioscapulohumeral muscular dystrophy (FSHD) have a partial failure of somatic DUX4 repression resulting in the presence of DUX4 protein in sporadic muscle nuclei. Somatic DUX4 derepression is caused by contraction of the D4Z4 repeat to 1-10 units (FSHD1) or by heterozygous mutations in genes responsible for maintaining the D4Z4 chromatin structure in a repressive state (FSHD2). One of the FSHD2 genes is the structural maintenance of chromosomes hinge domain 1 (SMCHD1) gene. SMCHD1 mutations have also been identified in FSHD1; patients carrying a contracted D4Z4 repeat and a SMCHD1 mutation are more severely affected than relatives with only a contracted repeat or a SMCHD1 mutation. To evaluate the modifier role of SMCHD1, we crossbred mice carrying a contracted D4Z4 repeat (D4Z4-2.5 mice) with mice that are haploinsufficient for Smchd1 (Smchd1MommeD1 mice). D4Z4-2.5/Smchd1MommeD1 mice presented with a significantly reduced body weight and developed skin lesions. The same skin lesions, albeit in a milder form, were also observed in D4Z4-2.5 mice, suggesting that reduced Smchd1 levels aggravate disease in the D4Z4-2.5 mouse model. Our study emphasizes the evolutionary conservation of the SMCHD1-dependent epigenetic regulation of the D4Z4 repeat array and further suggests that the D4Z4-2.5/Smchd1MommeD1 mouse model may be used to unravel the function of DUX4 in non-muscle tissues like the skin.

Deficiency of the T cell regulator Casitas B-cell lymphoma-B aggravates atherosclerosis by inducing CD8+ T cell-mediated macrophage death.

Aims: The E3-ligase CBL-B (Casitas B-cell lymphoma-B) is an important negative regulator of T cell activation that is also expressed in macrophages. T cells and macrophages mediate atherosclerosis, but their regulation in this disease remains largely unknown; thus, we studied the function of CBL-B in atherogenesis. Methods and results: The expression of CBL-B in human atherosclerotic plaques was lower in advanced lesions compared with initial lesions and correlated inversely with necrotic core area. Twenty weeks old Cblb-/-Apoe-/- mice showed a significant increase in plaque area in the aortic arch, where initial plaques were present. In the aortic root, a site containing advanced plaques, lesion area rose by 40%, accompanied by a dramatic change in plaque phenotype. Plaques contained fewer macrophages due to increased apoptosis, larger necrotic cores, and more CD8+ T cells. Cblb-/-Apoe-/- macrophages exhibited enhanced migration and increased cytokine production and lipid uptake. Casitas B-cell lymphoma-B deficiency increased CD8+ T cell numbers, which were protected against apoptosis and regulatory T cell-mediated suppression. IFNγ and granzyme B production was enhanced in Cblb-/-Apoe-/- CD8+ T cells, which provoked macrophage killing. Depletion of CD8+ T cells in Cblb-/-Apoe-/- bone marrow chimeras rescued the phenotype, indicating that CBL-B controls atherosclerosis mainly through its function in CD8+ T cells. Conclusion: Casitas B-cell lymphoma-B expression in human plaques decreases during the progression of atherosclerosis. As an important regulator of immune responses in experimental atherosclerosis, CBL-B hampers macrophage recruitment and activation during initial atherosclerosis and limits CD8+ T cell activation and CD8+ T cell-mediated macrophage death in advanced atherosclerosis, thereby preventing the progression towards high-risk plaques.

The many faces of CD8+ T cells in atherosclerosis.

PURPOSE OF REVIEW: Atherosclerosis and the clinical consequence of cardiovascular disease remain the leading cause of death worldwide. Both an increase in cholesterol levels, as well as immune responses drive the pathogenesis of this disease. Although much is known about the role of many immune cell subsets in atherogenesis, research into the role of CD8 T cells is limited. RECENT FINDINGS: Both atheroprotective and atherogenic functions of CD8 T cells have been reported. On the one hand, the inflammatory cytokines produced by CD8 T cells exacerbate inflammatory responses, and the cytotoxic activity of these cells toward lesion-stabilizing cells such as endothelial cells drives the progression and instability of atherosclerotic lesions. On the other hand, cytotoxic activity toward antigen presenting cells and the presence of regulatory CD8 T-cell subsets dampen immunity and can limit atherosclerosis. SUMMARY: Here we review the different roles of CD8 T cells in atherosclerosis and discuss possible treatment strategies targeting these cells to reduce atherosclerotic lesion burden.

NLRP3 Inflammasome Inhibition by MCC950 Reduces Atherosclerotic Lesion Development in Apolipoprotein E-Deficient Mice-Brief Report.

OBJECTIVE: Inflammasomes are multiprotein complexes, and their activation has been associated with cardiovascular disease. Inflammasome activation leads to secretion of caspase-1 by innate immune cells, resulting in the activation of interleukin-1ß. Recently, a potent and selective inhibitor of the NLRP3 inflammasome, MCC950, was described. In this study, we investigated the effect of MCC950 on atherosclerotic lesion development in apoE-/- mice. APPROACH AND RESULTS: First, we determined the efficacy of MCC950 in vitro. Bone marrow-derived macrophages and dendritic cells were stimulated with lipopolysaccharide and cholesterol crystals resulting in high levels of interleukin-1ß release, which was inhibited by MCC950. In vivo MCC950 treatment reduced lipopolysaccharide-induced interleukin-1ß secretion, without affecting the tumor necrosis factor-α response. Subsequently, atherosclerotic plaques were induced in Western-type diet fed apoE-/- mice by semiconstrictive perivascular collar placement at the carotid arteries, after which the mice received MCC950 (10 mg/kg) or vehicle control 3× per week intraperitoneally for 4 weeks. After euthanize, atherosclerotic plaque size and volume were quantified in hematoxylin-eosin-stained 10-µm cryosections throughout the artery. MCC950 treatment significantly reduced the development of atherosclerotic lesions as determined by maximal stenosis, average plaque size, and plaque volume. Although the amount of collagen and the necrotic core size were not affected, the number of macrophages in the plaque was significantly reduced on treatment. In addition, VCAM-1 (vascular cell adhesion molecule 1) and ICAM-1 (intercellular adhesion molecule 1) mRNA expression was significantly reduced in the carotids of MCC950-treated mice. CONCLUSIONS: These findings show that specific inhibition of the NLRP3 inflammasome using MCC950 can be a promising therapeutic approach to inhibit atherosclerotic lesion development.

Mesoporous Silica Nanoparticle-Coated Microneedle Arrays for Intradermal Antigen Delivery.

PURPOSE: To develop a new intradermal antigen delivery system by coating microneedle arrays with lipid bilayer-coated, antigen-loaded mesoporous silica nanoparticles (LB-MSN-OVA). METHODS: Synthesis of MSNs with 10-nm pores was performed and the nanoparticles were loaded with the model antigen ovalbumin (OVA), and coated with a lipid bilayer (LB-MSN-OVA). The uptake of LB-MSN-OVA by bone marrow-derived dendritic cells (BDMCs) was studied by flow cytometry. The designed LB-MSN-OVA were coated onto pH-sensitive pyridine-modified microneedle arrays and the delivery of LB-MSN-OVA into ex vivo human skin was studied. RESULTS: The synthesized MSNs demonstrated efficient loading of OVA with a maximum loading capacity of about 34% and the lipid bilayer enhanced the colloidal stability of the MSNs. Uptake of OVA loaded in LB-MSN-OVA by BMDCs was higher than that of free OVA, suggesting effective targeting of LB-MSN-OVA to antigen-presenting cells. Microneedles were readily coated with LB-MSN-OVA at pH 5.8, yielding 1.5 µg of encapsulated OVA per microneedle array. Finally, as a result of the pyridine modification, LB-MSN-OVA were effectively released from the microneedles upon piercing the skin. CONCLUSION: Microneedle arrays coated with LB-MSN-OVA were successfully developed and shown to be suitable for intradermal delivery of the encapsulated protein antigen.

Cutting edge: rapid boosting of cross-reactive memory CD8 T cells broadens the protective capacity of the Flumist vaccine.

Memory CD8 T cells recognizing conserved proteins from influenza A virus (IAV), such as nucleoprotein, have the potential to provide protection in individuals who lack the proper neutralizing Abs. In this study, we show that the most potent CD8 T cell-inducing influenza vaccine on the market (Flumist) does not induce sufficient numbers of cross-reactive CD8 T cells to provide substantial protection against lethal nonhomologous IAV challenge. However, Flumist-primed CD8 T cells rapidly acquire memory characteristics and can respond to short-interval boosting to greatly enlarge the IAV-specific memory pool, which is sufficient to protect mice from nonhomologous IAV challenge. Thus, a current vaccine strategy, Flumist, may serve as a priming platform for the rapid induction of large numbers of memory CD8 T cells with the capacity for broad protection against influenza.

Biological recognition and cellular trafficking of targeted RNA-lipid nanoparticles.

Lipid nanoparticles (LNPs) have unlocked the potential of ribonucleic acid (RNA) therapeutics and vaccines. Production and large-scale manufacturing methods for RNA-LNPs have been established and rapidly accelerate. Despite this, basic research on LNPs is still required, due to their high assembly complexity and fairly new development, including research on lipid organization, transfection optimization, and in vivo behavior. Understanding fundamental aspects of LNPs that is, how lipid composition and physicochemical properties affect their biodistribution, cell recognition, and transfection, could propel their clinical development and facilitate overcoming current challenges. Herein, we review recent developments in the field of LNP technology and summarize the main findings focusing on nano-bio interactions.