Induction of Mycobacterium Tuberculosis Lipid-Specific T Cell Responses by Pulmonary Delivery of Mycolic Acid-Loaded Polymeric Micellar Nanocarriers

Mycolic acid (MA), a major lipid component of Mycobacterium tuberculosis (Mtb) cell wall, can be presented by the non-polymorphic antigen presenting molecule CD1b to T cells isolated from Mtb-infected individuals. These MA-specific CD1b-restricted T cells are cytotoxic, produce Th1 cytokines, and form memory populations, suggesting that MA can be explored as a potential subunit vaccine candidate for TB. However, the controlled elicitation of MA-specific T cell responses has been challenging due to difficulties in the targeted delivery of lipid antigens and a lack of suitable animal models. In this study, we generated MA-loaded micellar nanocarriers (MA-Mc) comprised of self-assembled poly(ethylene glycol)-bl-poly(propylene sulfide; PEG-PPS) copolymers conjugated to an acid sensitive fluorophore to enhance intracellular delivery of MA to phagocytic immune cells. Using humanized CD1 transgenic (hCD1Tg) mice, we found these nanobiomaterials to be endocytosed by bone marrow-derived dendritic cells (DCs) and localized to lysosomal compartments. Additionally, MA-Mc demonstrated superior efficacy over free MA in activating MA-specific TCR transgenic (DN1) T cells in vitro. Following intranasal immunization, MA-Mc were primarily taken up by alveolar macrophages and DCs in the lung and induced activation and proliferation of adoptively transferred DN1 T cells. Furthermore, intranasal immunization with MA-Mc induced MA-specific T cell responses in the lungs of hCD1Tg mice. Collectively, our data demonstrates that pulmonary delivery of MA via PEG-PPS micelles to DCs can elicit potent CD1b-restricted T cell responses both in vitro and in vivo and MA-Mc could be explored as subunit vaccines against Mtb infection

Toll-like receptor 8 agonist nanoparticles mimic immunomodulating effects of the live BCG vaccine and enhance neonatal innate and adaptive immune responses

Background: Newborns display distinct immune responses, leaving them vulnerable to infections and impairing immunization. Targeting newborn dendritic cells (DCs), which integrate vaccine signals into adaptive immune responses, might enable development of age-specific vaccine formulations to overcome suboptimal immunization. Objective: Small-molecule imidazoquinoline Toll-like receptor (TLR) 8 agonists robustly activate newborn DCs but can result in reactogenicity when delivered in soluble form. We used rational engineering and age- and species-specific modeling to construct and characterize polymer nanocarriers encapsulating a TLR8 agonist, allowing direct intracellular release after selective uptake by DCs. Methods: Chemically similar but morphologically distinct nanocarriers comprised of amphiphilic block copolymers were engineered for targeted uptake by murine DCs in vivo, and a range of TLR8 agonist–encapsulating polymersome formulations were then synthesized. Novel 96-well in vitro assays using neonatal human monocyte-derived DCs and humanized TLR8 mouse bone marrow–derived DCs enabled benchmarking of the TLR8 agonist–encapsulating polymersome formulations against conventional adjuvants and licensed vaccines, including live attenuated BCG vaccine. Immunogenicity of the TLR8 agonist adjuvanted antigen 85B (Ag85B)/peptide 25–loaded BCG-mimicking nanoparticle formulation was evaluated in vivo by using humanized TLR8 neonatal mice. Results: Although alum-adjuvanted vaccines induced modest costimulatory molecule expression, limited TH-polarizing cytokine production, and significant cell death, BCG induced a robust adult-like maturation profile of neonatal DCs. Remarkably, TLR8 agonist polymersomes induced not only newborn DC maturation profiles similar to those induced by BCG but also stronger IL-12p70 production. On subcutaneous injection to neonatal mice, the TLR8 agonist–adjuvanted Ag85B peptide 25 formulation was comparable with BCG in inducing Ag85B-specific CD4+ T-cell numbers. Conclusion: TLR8 agonist–encapsulating polymersomes hold substantial potential for early-life immunization against intracellular pathogens. Overall, our study represents a novel approach for rational design of early-life vaccines

Sutureless versus conventional bioprostheses for aortic valve replacement in severe symptomatic aortic valve stenosis

International audienceObjective: Sutureless aortic valves are a novel option for aortic valve replacement. We sought to demonstrate noninferiority of sutureless versus standard bioprostheses in severe symptomatic aortic stenosis.Methods: The Perceval Sutureless Implant Versus Standard-Aortic Valve Replacement is a prospective, randomized, adaptive, open-label trial. Patients were randomized (March 2016 to September 2018) to aortic valve replacement with a sutureless or stented valve using conventional or minimally invasive approach. Primary outcome was freedom from major adverse cerebral and cardiovascular events (composite of all-cause death, myocardial infarction, stroke, or valve reintervention) at 1 year.Results: At 47 centers (12 countries), 910 patients were randomized to sutureless (n = 453) or conventional stented (n = 457) valves; mean ages were 75.4 ± 5.6 and 75.0 ± 6.1 years, and 50.1% and 44.9% were female, respectively. Mean ± standard deviation Society of Thoracic Surgeons scores were 2.4 ± 1.7 and 2.1 ± 1.3, and a ministernotomy approach was used in 50.4% and 47.3%, respectively. Concomitant procedures were performed with similar rates in both groups. Noninferiority was demonstrated for major adverse cerebral and cardiovascular events at 1 year, whereas aortic valve hemodynamics improved equally in both groups. Use of sutureless valves significantly reduced surgical times (mean extracorporeal circulation times: 71.0 ± 34.1 minutes vs 87.8 ± 33.9 minutes; mean crossclamp times: 48.5 ± 24.7 vs 65.2 ± 23.6; both P < .0001), but resulted in a higher rate of pacemaker implantation (11.1% vs 3.6% at 1 year). Incidences of perivalvular and central leak were similar.Conclusions: Sutureless valves were noninferior to stented valves with respect to major adverse cerebral and cardiovascular events at 1 year in patients undergoing aortic valve replacement (alone or with coronary artery bypass grafting). This suggests that sutureless valves should be considered as part of a comprehensive valve program