Phagocytosed Polyhedrin-Cytokine Cocrystal Nanoparticles Provide Sustained Secretion of Bioactive Cytokines from Macrophages

Investigating Internalization of Reporter-Protein-Functionalized Polyhedrin Particles by Brain Immune Cells

Achieving sustained drug delivery to the central nervous system (CNS) is a major challenge for neurological injury and disease, and various delivery vehicles are being developed to achieve this. Self-assembling polyhedrin crystals (POlyhedrin Delivery System; PODS) are being exploited for the delivery of therapeutic protein cargo, with demonstrated efficacy in vivo. However, to establish the utility of PODS for neural applications, their handling by neural immune cells (microglia) must be documented, as these cells process and degrade many biomaterials, often preventing therapeutic efficacy. Here, primary mouse cortical microglia were cultured with a GFP-functionalized PODS for 24 h. Cell counts, cell morphology and Iba1 expression were all unaltered in treated cultures, indicating a lack of acute toxicity or microglial activation. Microglia exhibited internalisation of the PODS, with both cytosolic and perinuclear localisation. No evidence of adverse effects on cellular morphology was observed. Overall, 20-40% of microglia exhibited uptake of the PODS, but extracellular/non-internalised PODS were routinely present after 24 h, suggesting that extracellular drug delivery may persist for at least 24 h.

Immunisation with Transgenic L. tarentolae Expressing Gamma Glutamyl Cysteine Synthetase from Pathogenic Leishmania Species Protected against L. major and L. donovani Infection in a Murine Model

Leishmaniasis is a protozoan disease responsible for significant morbidity and mortality. There is no recommended vaccine to protect against infection. In this study, transgenic Leishmania tarentolae expressing gamma glutamyl cysteine synthetase (γGCS) from three pathogenic species were produced and their ability to protect against infection determined using models of cutaneous and visceral leishmaniasis. The ability of IL-2-producing PODS^® to act as an adjuvant was also determined in L. donovani studies. Two doses of the live vaccine caused a significant reduction in L. major (p < 0.001) and L. donovani (p < 0.05) parasite burdens compared to their respective controls. In contrast, immunisation with wild type L. tarentolae, using the same immunisation protocol, had no effect on parasite burdens compared to infection controls. Joint treatment with IL-2-producing PODS^® enhanced the protective effect of the live vaccine in L. donovani studies. Protection was associated with a Th1 response in L. major and a mixed Th1/Th2 response in L. donovani, based on specific IgG1 and IgG2a antibody and cytokine production from in vitro proliferation assays using antigen-stimulated splenocytes. The results of this study provide further proof that γGCS should be considered a candidate vaccine for leishmaniasis.

Exploiting Nanomedicine for Cancer Polychemotherapy: Recent Advances and Clinical Applications

The most important limitations of chemotherapeutic agents are severe side effects and the development of multi-drug resistance. Recently, the clinical successes achieved with immunotherapy have revolutionized the treatment of several advanced-stage malignancies, but most patients do not respond and many of them develop immune-related adverse events. Loading synergistic combinations of different anti-tumor drugs in nanocarriers may enhance their efficacy and reduce life-threatening toxicities. Thereafter, nanomedicines may synergize with pharmacological, immunological, and physical combined treatments, and should be increasingly integrated in multimodal combination therapy regimens. The goal of this manuscript is to provide better understanding and key considerations for developing new combined nanomedicines and nanotheranostics. We will clarify the potential of combined nanomedicine strategies that are designed to target different steps of the cancer growth as well as its microenvironment and immunity interactions. Moreover, we will describe relevant experiments in animal models and discuss issues raised by translation in the human setting.

Understanding the Phagocytosis of Particles: the Key for Rational Design of Vaccines and Therapeutics

A robust comprehension of phagocytosis is crucial for understanding its importance in innate immunity. A detailed description of the molecular mechanisms that lead to the uptake and clearance of endogenous and exogenous particles has helped elucidate the role of phagocytosis in health and infectious or autoimmune diseases. Furthermore, knowledge about this cellular process is important for the rational design and development of particulate systems for the administration of vaccines or therapeutics. Depending on these specific applications and the required biological responses, particles must be designed to encourage or avoid their phagocytosis and prolong their circulation time. Functionalization with specific polymers or ligands and changes in the size, shape, or surface of particles have important effects on their recognition and internalization by professional and nonprofessional phagocytes and have a major influence on their fate and safety. Here, we review the phagocytosis of particles intended to be used as carrier or delivery systems for vaccines or therapeutics, the cells involved in this process depending on the route of administration, and the strategies employed to obtain the most desirable particles for each application through the manipulation of their physicochemical characteristics. We also offer a view of the challenges and potential opportunities in the field and give some recommendations that we expect will enable the development of improved approaches for the rational design of these systems.