A Novel Laser Vaccine Adjuvant Increases the Motility of Antigen Presenting Cells

Background Development of a potent vaccine adjuvant without introduction of any side effects remains an unmet challenge in the field of the vaccine research. Methodology/Principal Findings We found that laser at a specific setting increased the motility of antigen presenting cells (APCs) and immune responses, with few local or systemic side effects. This laser vaccine adjuvant (LVA) effect was induced by brief illumination of a small area of the skin or muscle with a nondestructive, 532 nm green laser prior to intradermal (i.d.) or intramuscular (i.m.) administration of vaccines at the site of laser illumination. The pre-illumination accelerated the motility of APCs as shown by intravital confocal microscopy, leading to sufficient antigen (Ag)-uptake at the site of vaccine injection and transportation of the Ag-captured APCs to the draining lymph nodes. As a result, the number of Ag+ dendritic cells (DCs) in draining lymph nodes was significantly higher in both the 1° and 2° draining lymph nodes in the presence than in the absence of LVA. Laser-mediated increases in the motility and lymphatic transportation of APCs augmented significantly humoral immune responses directed against a model vaccine ovalbumin (OVA) or influenza vaccine i.d. injected in both primary and booster vaccinations as compared to the vaccine itself. Strikingly, when the laser was delivered by a hair-like diffusing optical fiber into muscle, laser illumination greatly boosted not only humoral but also cell-mediated immune responses provoked by i.m. immunization with OVA relative to OVA alone. Conclusion/Significance The results demonstrate the ability of this safe LVA to augment both humoral and cell-mediated immune responses. In comparison with all current vaccine adjuvants that are either chemical compounds or biological agents, LVA is novel in both its form and mechanism; it is risk-free and has distinct advantages over traditional vaccine adjuvants.National Institutes of Health (U.S.) (grant AI070785)National Institutes of Health (U.S.) (grant RC1 DA028378)Bill & Melinda Gates Foundation (Grand Challenges Explorations grant # 53273)Boston BioCom (Firm) (Sponsored Research agreement grant #2008A25652

Migratory Dermal Dendritic Cells Act as Rapid Sensors of Protozoan Parasites

Dendritic cells (DC), including those of the skin, act as sentinels for intruding microorganisms. In the epidermis, DC (termed Langerhans cells, LC) are sessile and screen their microenvironment through occasional movements of their dendrites. The spatio-temporal orchestration of antigen encounter by dermal DC (DDC) is not known. Since these cells are thought to be instrumental in the initiation of immune responses during infection, we investigated their behavior directly within their natural microenvironment using intravital two-photon microscopy. Surprisingly, we found that, under homeostatic conditions, DDC were highly motile, continuously crawling through the interstitial space in a Gαi protein-coupled receptor–dependent manner. However, within minutes after intradermal delivery of the protozoan parasite Leishmania major, DDC became immobile and incorporated multiple parasites into cytosolic vacuoles. Parasite uptake occurred through the extension of long, highly dynamic pseudopods capable of tracking and engulfing parasites. This was then followed by rapid dendrite retraction towards the cell body. DDC were proficient at discriminating between parasites and inert particles, and parasite uptake was independent of the presence of neutrophils. Together, our study has visualized the dynamics and microenvironmental context of parasite encounter by an innate immune cell subset during the initiation of the immune response. Our results uncover a unique migratory tissue surveillance program of DDC that ensures the rapid detection of pathogens

Setting the stage: host invasion by HIV.

For more than two decades, HIV has infected millions of people worldwide each year through mucosal transmission. Our knowledge of how HIV secures a foothold at both the molecular and cellular levels has been expanded by recent investigations that have applied new technologies and used improved techniques to isolate ex vivo human tissue and generate in vitro cellular models, as well as more relevant in vivo animal challenge systems. Here, we review the current concepts of the immediate events that follow viral exposure at genital mucosal sites where most documented transmissions occur. Furthermore, we discuss the gaps in our knowledge that are relevant to future studies, which will shape strategies for effective HIV prevention

Dual Therapeutic Efficacy of Vinblastine as a Unique Chemotherapeutic Agent Capable of Inducing Dendritic Cell Maturation

Our recent unbiased functional screen of 54 chemotherapeutic drugs unveiled striking heterogeneity in their effects on dendritic cells (DC). Most notably, vinblastine (VBL) was found to induce phenotypic and functional maturation of DCs in vitro. Here, we sought to determine whether VBL exhibits "dual" therapeutic efficacy in living animals by directly killing tumor cells and by boosting host immunity via DC maturation. Local injection of VBL, in a low dose into the skin of C57BL/6 mice induced in situ maturation of epidermal Langerhans cells. When coinjected with a model antigen, ovalbumin (OVA), VBL enhanced OVA-specific cellular and Immoral immune responses. When injected directly into the OVA cDNA-transduced E.G7 tumors, VBL augmented clonal expansion of OVA-reactive CD8 T cells and CTL activities. In B16 melanoma model, intratumor VBL, injection induced apoptosis of melanoma cells, phenotypic maturation of tumor-infiltrating DCs, and significant CTL activities. Although complete clearance was never achieved, growth kinetic of B16 melanoma was markedly reduced in C57BL/6 mice by intratumor VBL injection. Importantly, the same treatment was far less efficacious in immunocompromised severe combined immunodeficient mice, indicating the requirement of intact host immunity. Our results introduce a new concept that VBL may be used to design "immunostimulatory" chemotherapy regimens. [Cancer Res 2009;69(17):6987-94

A comprehensive survey of 3′ animal miRNA modification events and a possible role for 3′ adenylation in modulating miRNA targeting effectiveness

Animal microRNA sequences are subject to 3′ nucleotide addition. Through detailed analysis of deep-sequenced short RNA data sets, we show adenylation and uridylation of miRNA is globally present and conserved across Drosophila and vertebrates. To better understand 3′ adenylation function, we deep-sequenced RNA after knockdown of nucleotidyltransferase enzymes. The PAPD4 nucleotidyltransferase adenylates a wide range of miRNA loci, but adenylation does not appear to affect miRNA stability on a genome-wide scale. Adenine addition appears to reduce effectiveness of miRNA targeting of mRNA transcripts while deep-sequencing of RNA bound to immunoprecipitated Argonaute (AGO) subfamily proteins EIF2C1–EIF2C3 revealed substantial reduction of adenine addition in miRNA associated with EIF2C2 and EIF2C3. Our findings show 3′ addition events are widespread and conserved across animals, PAPD4 is a primary miRNA adenylating enzyme, and suggest a role for 3′ adenine addition in modulating miRNA effectiveness, possibly through interfering with incorporation into the RNA-induced silencing complex (RISC), a regulatory role that would complement the role of miRNA uridylation in blocking DICER1 uptake