Orchestrating antigen delivery and presentation efficiency in lymph node by nanoparticle shape for immune response

Activating humoral and cellular immunity in lymph nodes (LNs) of nanoparticle-based vaccines is critical to controlling tumors. However, how the physical properties of nanovaccine carriers orchestrate antigen capture, lymphatic delivery, antigen presentation and immune response in LNs is largely unclear. Here, we manufactured gold nanoparticles (AuNPs) with the same size but different shapes (cages, rods, and stars), and loaded tumor antigen as nanovaccines to explore their disparate characters on above four areas. Results revealed that star-shaped AuNPs captured and retained more repetitive antigen epitopes. On lymphatic delivery, both rods and star-shaped nanovaccines mainly drain into the LN follicles region while cage-shaped showed stronger paracortex retention. A surprising finding is that the star-shaped nanovaccines elicited potent humoral immunity, which is mediated by CD4+ T helper cell and follicle B cell cooperation significantly preventing tumor growth in the prophylactic study. Interestingly, cage-shaped nanovaccines preferentially presented peptide-MHC I complexes to evoke robust CD8+ T cell immunity and showed the strongest therapeutic efficacy when combined with the PD-1 checkpoint inhibitor in established tumor study. These results highlight the importance of nanoparticle shape on antigen delivery and presentation for immune response in LNs, and our findings support the notion that different design strategies are required for prophylactic and therapeutic vaccines.

Surface-modified nanoparticles of docetaxel for chemotherapy of lung cancer: An intravenous to oral switch

Despite being potent, the marketed formulations of Docetaxel (DX) are associated with numerous side effects and are meant for intravenous administration. Advanced pharmaceutical nanotechnology has a significant potential to facilitate the 'intravenous (i.v) to oral switch'. The present research work deals with the development of an orally administrable, folate-receptor-targeted Nanostructured lipid carriers (NLCs) of DX (FA-DX-NLCs) for facilitating oral chemotherapy of lung cancer while overcoming the bioavailability and toxicity issues. The nanoformulation prepared to employ high-pressure homogenization and lyophilization, was evaluated and statistically analyzed for various in-vitro and in-vivo formulation characteristics. The lyophilized nanoparticles were observed to be spherical with a particle size of 183.4 ± 2.13 (D90), Pdi of 0.358 ± 0.03, % EE of 82.41 ± 2.44, % DL of 4.41 ± 0.54 and a zeta potential of -3.3 ± 0.7 mv. The increased oral in-vivo bioavailability of DX was evident from the plasma-concentration area under the time curve (AUC_0-t), which was ∼ 27-fold greater for FA-DX-NLCs as compared to DX suspension. The orally administered FA-DX-NLCs exhibited excellent antitumor efficacy in a pre-clinical model of lung carcinoma. Tumor staging, histopathology, and immunostaining of the tumors suggested greater anti-proliferative, apoptotic, anti-metastatic, and anti-angiogenic potential as compared to DX-suspension. The pre-clinical toxicity studies affirmed the excellent safety and bio-compatibility of FA-DX-NLCs. The research work presents immense translational potential for switching the DX-based chemotherapy for lung cancer from 'hospital to home.'

Hybrid Lymphatic Drug Delivery Vehicles as a New Avenue for Targeted Therapy: Lymphatic Trafficking, Applications, Challenges, and Future Horizons

Lymphatic drug targeting is an effective approach for targeting immunomodulators, and chemotherapeutic drugs at a specific organ or cellular location. The cellular, paracellular, and dendritic cell trafficking machinery are involved in the lymphatic transport of therapeutic agents. The engineering of triggered and hybrid lymphatic drug delivery systems (LDDS) is a promising strategy to fight cancer metastasis and microbial pandemics. Hybrid lymphatic drug delivery systems can be tailored and developed by grafting the conventional LDDS with biological agents. Thus, hybrid LDDS could collect the benefits of conventional and biological delivery systems. Moreover, the fabrication of triggered LDDS increases drug accumulation in the lymphatic system in the response to an internal stimulus such as pH, and redox status or external such as magnetic field, temperature, and light. Stimuli-responsive LDD systems prevent premature release of payload and mediate selective drug biodistribution. This improves therapeutic impact and reduces the systemic side effect of anticancer, immunomodulatory, and antimicrobial therapeutics. This review highlights the challenges and future horizons of nanoscaled-triggered LDDS and their influence on the lymphatic trafficking of therapeutic molecules.

Dawn of lipid nanoparticles in lymph node targeting: Potential in cancer immunotherapy

It is generally known that the lymph nodes (LNs) are important tissues in cancer immunotherapy. Therefore, delivering immune functional compounds to LNs is a useful strategy for enhancing cancer immunotherapy. Lipid-based nanocarriers have been widely used as delivery systems that target LNs, but lipid nanoparticle (LNP) technology has recently attracted increased interest. High levels of nucleic acids can be efficiently loaded in LNPs, they can be used to actively deliver nucleic acids into the cytoplasm, and they can be produced on an industrial scale. The use of microfluidic devices has been particularly valuable for producing small-sized LNPs, thus paving the way for successful LN targeting. In the review, we focus on the potential of LNP technology for targeting LNs.

Bile acid transporter-mediated oral drug delivery

Bile acids are synthesized in the liver, stored in the gallbladder, and secreted into the duodenum at meals. Apical sodium-dependent bile acid transporter (ASBT), an ileal Na⁺-dependent transporter, plays the leading role of bile acid absorption into enterocytes, where bile acids are delivered to basolateral side by ileal bile acid binding protein (IBABP) and then released by organic solute transporter OSTα/β. The absorbed bile acids are delivered to the liver via portal vein. In this process called "enterohepatic recycling", only 5% of the bile acid pool (~3 g in human) is excreted in feces, indicating the large recycling capacity and high transport efficacy of ASBT-mediated absorption. Therefore, bile acid transporter-mediated oral drug delivery has been regarded as a feasible and potential strategy to improve the oral bioavailability. This review introduces the key factors in enterohepatic recycling, especially the mechanism of bile acid uptake by ASBT, and the development of bile acid-based oral drug delivery for ASBT-targeting, including bile acid-based prodrugs, bile acid/drug electrostatic complexation and bile acid-containing nanocarriers. Furthermore, the specific transport pathways of bile acid in enterocytes are described and the recent finding of lymphatic delivery of bile acid-containing nanocarriers is discussed.

Nanotopography-based lymphatic delivery for improved anti-tumor responses to checkpoint blockade immunotherapy

Rationale: Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is a co-inhibitory checkpoint receptor that is expressed by naïve T-cells in lymph nodes (LNs) to inhibit activation against “self” antigens (Ags). In cancer, anti-CTLA-4 blocks inhibitory action, enabling robust activation of T-cells against tumor Ags presented in tumor draining LNs (TDLNs). However, anti-CTLA-4 is administered intravenously with limited exposure within TDLNs and immune related adverse events (irAEs) are associated with over-stimulation of the immune system.

Methods: Herein, we first deliver anti-CTLA-4 in an orthotopic mammary carcinoma murine model using a nanotopographical microneedle-array device to compare its anti-tumor response to that from systemic administration. Additionally, to demonstrate the feasibility of lymphatic delivery in humans using the device, we use near-infrared fluorescence imaging to image delivery of ICG to LNs.

Results: Our data show that lymphatic infusion results in more effective tumor growth inhibition, arrest of metastases, increased tumor infiltrating lymphocytes and complete responses when compared to conventional systemic administration. In clinical studies, we demonstrate for the first time that nanotopographic infusion can deliver ICG through the lymphatics directly to the axilla and inguinal LNs of healthy human volunteers.

Conclusion: Taken together, these results suggest that regional delivery using a nanotopography-based microneedle array could revolutionize checkpoint blockade immunotherapy by reducing systemic drug exposure and maximizing drug delivery to TDLNs where tumor Ags present. Future work is needed to determine whether lymphatic delivery of anti-CTLA-4 can alleviate irAEs that occur with systemic dosing.

Soft- and hard-lipid nanoparticles: a novel approach to lymphatic drug delivery

With the current advance in nanotechnology, the development has accelerated of a number of nanoparticle-type drugs such as nano-emulsions, lipid emulsions, liposomes, and cell therapeutics. With these developments, attempts are being made to apply these new drugs to healing many intractable diseases related to antibody production, autoimmune disorders, cancer, and organ transplantation in both clinical and nonclinical trials. Drug delivery to the lymphatic system is indispensable for treating these diseases, but the core technologies related to the in vivo distribution characteristics and lymphatic delivery evaluation of these particle-type drugs have not yet been established. Additionally, the core technologies for setting up the pharmacotherapeutic aspects such as their usage and dosages in the development of new drugs do not meet the needs of the market. Therefore, it is necessary to consider dividing these particle-type drugs into soft-lipid nanoparticles that can change size in the process of body distribution and hard-lipid nanoparticles whose surfaces are hardened and whose sizes do not easily change in vivo; these soft- and hard-lipid nanoparticles likely possess different biodistribution characteristics including delivery to the lymphatic system. In this review, we summarize the different types, advantages, limitations, possible remedies, and body distribution characteristics of soft- and hard-lipid nanoparticles based on their administration routes. We also emphasize that it will be necessary to fully understand the differences in distribution between these soft- and hard-lipid nanoparticle-type drugs and to establish pharmacokinetic models for their more ideal lymphatic delivery.

Pharmacokinetics and biodistribution of squalene-containing emulsion adjuvant following intramuscular injection of H5N1 influenza vaccine in mice

Squalene is a component of oil-in-water emulsion adjuvants developed for potential use in some influenza vaccines. The biodistribution of the squalene-containing emulsion adjuvant (AddaVax™) alone and as part of complete H5N1 vaccine was quantified in mechanistically and toxicologically relevant target tissues up to 336 h (14 days) following injection into quadriceps muscle. At 1 h, about 55% of the intramuscularly injected dose of squalene was detected in the local quadriceps muscles and this decreased to 26% at 48 h. Twenty-four hours after the injection, approximately 5%, 1%, and 0.6% of the injected dose was detected in inguinal fat, draining lymph nodes, and sciatic nerve, respectively. The peak concentration for kidney, brain, spinal cord, bone marrow, and spleen was each less than 1% of the injected dose, and H5N1 antigen did not significantly alter the biodistribution of squalene to these tissues. The area-under-blood-concentration curve (AUC) and peak blood concentration (Cmax) of squalene were slightly higher (20-25%) in the presence of H5N1 antigen. A population pharmacokinetic model-based statistical analysis identified body weight and H5N1 antigen as covariates influencing the clearance of squalene. The results contribute to the body of knowledge informing benefit-risk analyses of squalene-containing emulsion vaccine adjuvants.

Pharmacokinetic aspects and in vitro-in vivo correlation potential for lipid-based formulations

Lipid-based formulations have been an attractive choice among novel drug delivery systems for enhancing the solubility and bioavailability of poorly soluble drugs due to their ability to keep the drug in solubilized state in the gastrointestinal tract. These formulations offer multiple advantages such as reduction in food effect and inter-individual variability, ease of preparation, and the possibility of manufacturing using common excipients available in the market. Despite these advantages, very few products are available in the present market, perhaps due to limited knowledge in the in vitro tests (for prediction of in vivo fate) and lack of understanding of the mechanisms behind pharmacokinetic and biopharmaceutical aspects of lipid formulations after oral administration. The current review aims to provide a detailed understanding of the in vivo processing steps involved after oral administration of lipid formulations, their pharmacokinetic aspects and in vitro in vivo correlation (IVIVC) perspectives. Various pharmacokinetic and biopharmaceutical aspects such as formulation dispersion and lipid digestion, bioavailability enhancement mechanisms, impact of excipients on efflux transporters, and lymphatic transport are discussed with examples. In addition, various IVIVC approaches towards predicting in vivo data from in vitro dispersion/precipitation, in vitro lipolysis and ex vivo permeation studies are also discussed in detail with help of case studies.