The immune cytokine tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has received significant attention as a cancer therapeutic due to its ability to selectively trigger cancer cell apoptosis without causing toxicity in vivo. While TRAIL has demonstrated significant promise in preclinical studies in mice as a cancer therapeutic, challenges including poor circulation half-life, inefficient delivery to target sites, and TRAIL resistance have hindered clinical translation. Recent advances in drug delivery, materials science, and nanotechnology are now being exploited to develop next-generation nanoparticle platforms to overcome barriers to TRAIL therapeutic delivery. Here, we review the design and implementation of nanoparticles to enhance TRAIL-based cancer therapy. The platforms we discuss are diverse in their approaches to the delivery problem and provide valuable insight into guiding the design of future nanoparticle-based TRAIL cancer therapeutics to potentially enable future translation into the clinic.

Neutrophils are the most abundant circulating leukocyte and the first point of contact between many drug delivery formulations and human cells. Despite their prevalence and implication in a range of immune functions, little is known about how human neutrophils respond to synthetic particulates. Here, we describe how ex vivo human neutrophils respond to particles which vary in both size (5 nm to 2 μm) and chemistry (lipids, poly(styrene), poly(lactic-co-glycolic acid), and gold). In particular, we show that (i) particle uptake is rapid, typically plateauing within 15 min; (ii) for a given particle chemistry, neutrophils preferentially take up larger particles at the nanoscale, up to 200 nm in size; (iii) uptake of nanoscale poly(styrene) and liposomal particles at concentrations of up to 5 μg/mL does not enhance apoptosis, activation, or cell death; (iv) particle-laden neutrophils retain the ability to degranulate normally in response to chemical stimulation; and (v) ingested particles reside in intracellular compartments that are retained during activation and degranulation. Aside from the implications for design of intravenously delivered particulate formulations in general, we expect these observations to be of particular use for targeting nanoparticles to circulating neutrophils, their clearance site (bone marrow), or distal sites of active inflammation.

The Global Vaccine Action Plan 2011–2020 (GVAP) aims to extend the full benefit of vaccination against vaccine-preventable diseases to all individuals. More than halfway through the Decade of Vaccines, countries classified as Middle-Income by the World Bank struggle to achieve several GVAP targets. Countries transitioning from Gavi, the Vaccine Alliance, represent a key sub-group of Middle Income Countries.Through a review of available literature on the subject, this study documents the lack of comparative analyses on immunization system performance in countries transitioning from Gavi support. Despite increased emphasis on the importance of programmatic sustainability beyond financing through the Gavi 2016–2020 Strategy and availability of data, existing literature has predominantly documented challenges related to domestic financing of immunization.This study complements a review of current literature with an analysis of country assessments conducted by immunization partners since 2011, in an effort to document programmatic challenges related to decision-making for immunization policy, delivery of services, and access to affordable and timely supply in Gavi transitioning countries.In light of the findings, we suggest continued systematic compilation of country performance data beyond financing to inform policy-making, in particular for: (i) development of a more nuanced theory of change towards sustainable immunization programmes and (ii) measurement of progress and key areas for attention and investment.

Maintaining and limiting T cell responses to constant antigen stimulation is critical to control pathogens and maintain self-tolerance, respectively. Antigen recognition by T cell receptors (TCRs) induces signalling that activates T cells to produce cytokines and also leads to the downregulation of surface TCRs. In other systems, receptor downregulation can induce perfect adaptation to constant stimulation by a mechanism known as statedependent inactivation that requires complete downregulation of the receptor or the ligand. However, this is not the case for the TCR, and therefore, precisely how TCR downregulation maintains or limits T cell responses is controversial. Here, we observed that in vitro expanded primary human T cells exhibit perfect adaptation in cytokine production to constant antigen stimulation across a 100,000-fold variation in affinity with partial TCR downregulation. By directly fitting a mechanistic model to the data, we show that TCR downregulation produces imperfect adaptation, but when coupled to a switch produces perfect adaptation in cytokine production. A prediction of the model is that pMHC-induced TCR signalling continues after adaptation and this is confirmed by showing that, while costimulation cannot prevent adaptation, CD28 and 4-1BB signalling reactivated adapted T cells to produce cytokines in a pMHC-dependent manner. We show that adaptation also applied to 1st generation chimeric antigen receptor (CAR)-T cells but is partially avoided in 2nd generation CARs. These findings highlight that even partial TCR downregulation can limit T cell responses by producing perfect adaptation rendering T cells dependent on costimulation for sustained responses.Introduction 1 T cell activation is critical to initiate and maintain adaptive immunity. It proceeds by the recognition of peptide 2 major-histocompatibility complex (pMHC) antigens by T cells using their T cell receptors (TCRs). TCR/pMHC 3 binding induces signalling pathways that can activate T cells to directly kill cancerous or infected cells and to se-4 crete a range of cytokines (1). When T cells are confronted with persistent or constant pMHC antigens, maintaining 5 responses to foreign or altered-self pMHC (in chronic infections and cancers (2)) can be just as important as lim-6 iting responses to self pMHC (e.g. adaptive tolerance (3)). Like other surface receptors, the TCR is downregulated 7 from the surface of T cells upon recognition of pMHC ligands (4). Precisely how TCR downregulation controls T 8 cell responses to constant pMHC antigen stimulation remains controversial. 9In other cellular systems, receptor downregulation can induce biological adaptation to constant ligand stimulation 10 (5). Adaptation is defined by the ability of a system to display transient responses that return to baseline when 11 presented with constant input stimulation. The process is known as perfect (or near-perfect) when the baselines 12 before and after stimulation are similar and is imperfect otherwise. Systematic network searches have identified...

Maintaining and limiting T cell responses to constant antigen stimulation is critical to control pathogens and maintain self-tolerance, respectively. Antigen recognition by T cell receptors (TCRs) induces signalling that activates T cells to produce cytokines and also leads to the downregulation of surface TCRs. In other systems, receptor downregulation can induce perfect adaptation to constant stimulation by a mechanism known as statedependent inactivation that requires complete downregulation of the receptor or the ligand. However, this is not the case for the TCR, and therefore, precisely how TCR downregulation maintains or limits T cell responses is controversial. Here, we observed that in vitro expanded primary human T cells exhibit perfect adaptation in cytokine production to constant antigen stimulation across a 100,000-fold variation in affinity with partial TCR downregulation. By directly fitting a mechanistic model to the data, we show that TCR downregulation produces imperfect adaptation, but when coupled to a switch produces perfect adaptation in cytokine production. A prediction of the model is that pMHC-induced TCR signalling continues after adaptation and this is confirmed by showing that, while costimulation cannot prevent adaptation, CD28 and 4-1BB signalling reactivated adapted T cells to produce cytokines in a pMHC-dependent manner. We show that adaptation also applied to 1st generation chimeric antigen receptor (CAR)-T cells but is partially avoided in 2nd generation CARs. These findings highlight that perfect adaptation limits T cell responses rendering them dependent on costimulation for sustained responses.