Cutaneous dendritic cells

[Fibrous papules of the face: a retrospective anatomoclinical study of 283 cases]

BACKGROUND

Fibrous papules of the face are frequent benign lesions seen in the nasal and perinasal region. Their clinical aspect is indistinct and the histological signs are sometimes mild or possibly misleading in the case of atypical forms. We carried out a retrospective study of 283 fibrous papules diagnosed at our histology laboratory. The goal of this study was to characterize this type of frequent but occasionally unrecognized lesion.

PATIENTS AND METHODS

We performed a retrospective study of fibrous papules of the face diagnosed in the dermatopathology laboratory of our dermatology centre between January 2002 and December 2011. The study concerned the clinical information noted in the examination request and the morphological abnormalities seen at optical microscopy. An immunohistological study of factor XIIIa was performed in selected cases.

RESULTS

The fibrous papules of the face came from 129 men and 154 women aged between 18 and 90 years (mean: 46 years). Two hundred and thirty-seven (83.7%) lesions were taken from the nasal region and none were taken from anywhere other than the face. The clinically mentioned diagnoses varied. A diagnosis of fibrous papule of the face was stated in 42% of cases, and the main differential diagnoses were nevus (stated in 34% of cases) and basal cell carcinoma (stated in 14% of cases). The fibrous papules were classic in 85.5% of cases. We observed 6 variants of fibrous papule: hypercellular, inflammatory, pleomorphic, pigmented, clear-cell and granular-cell types. Immunohistochemistry of factor XIIIa was positive in all cases except clear-cell fibrous papules.

DISCUSSION

This study shows that despite their frequency, these lesions often go unrecognized, since the hypothesis of a fibrous papule of the face was mentioned in fewer than 50% of cases at the time of biopsy. Diagnosis is often made by the histopathologist, who may be misled by some rare types. The principal differential diagnoses are nevus and basal cell carcinoma, thus warranting methodical histological analysis of all pieces.

Candida skin test reagent as a novel adjuvant for a human papillomavirus peptide-based therapeutic vaccine

A vaccine adjuvant that can effectively promote cell-mediated immunity is currently not available. Because of the ability of a Candida skin test reagent injection to induce common wart regression, our group is using it as a novel adjuvant in a clinical trial of a peptide-based human papillomavirus therapeutic vaccine. The goal of this current study was to investigate the mechanisms of how Candida enhances the vaccine immune responses. Maturation effects on Langerhans cells, capacity to proliferate T-cells, expression of cytokines and pattern recognition receptors by Langerhans cells, and ability to induce Th1, Th2, and Th17 responses were investigated in healthy subjects. The vaccine, human papillomavirus peptides with Candida, demonstrated partial maturation effects on Langerhans cells indicated by significantly up-regulated CD40 (p=0.00007) and CD80 (p<0.00001) levels, and showed T-cell proliferative capacity (p<0.00001) when presented by Langerhans cells in vitro. Interestingly, the maturation effects were due to the peptides while Candida was responsible for the T-cell proliferation. The cytokine profile (IL-1β, IL-6, IL-8, IL-10, IL-12p40, IL-23Ap19, IFN-γ and TNF-α) of Langerhans cells treated with the vaccine or Candida alone showed that IL-12p40 mRNA was most frequently induced, and IL-12p70 protein was detected in the supernatants. The presence of pattern recognition receptors known to associate with Candida albicans (DC-SIGN, dectin-1, dectin-2, galectin-3, mincle, mannose receptor, Toll-like receptors-1, 2, 4, 6 and 9) were demonstrated in all subjects. On the other hand, the induction of Th1 response demonstrated by IFN-γ secretion by CD4 cells stimulated with the vaccine or Candida pulsed Langerhans cells was demonstrated only in one subject. In summary, the Langerhans cell maturation effects of the vaccine were due to the peptides while the T-cell proliferative capacity was derived from Candida, and the most frequently induced cytokine was IL-12.

Human dendritic cells subsets as targets and vectors for therapy

The skin immune system includes a complex network of dendritic cells (DCs). In addition to generating cellular and humoral immunity against pathogens, skin DCs are involved in tolerogenic mechanisms that maintain immune homeostasis and in pathogenic chronic inflammation in which immune responses are unrestrained. Harnessing DC function by directly targeting DC-derived molecules or by selectively modulating DC subsets is a novel strategy for ameliorating inflammatory diseases. In this short review, we discuss recent advances in understanding the functional specialization of skin DCs and the potential implication for future DC-based therapeutic strategies.

Long-term CD4(+) and CD8(+) T-cell responses induced in HIV-uninfected volunteers following intradermal or intramuscular administration of an HIV-lipopeptide vaccine (ANRS VAC16)

BACKGROUND

We have shown that the intradermal (ID) administration of an HIV-1 lipopeptide candidate vaccine (LIPO-4) is well tolerated in healthy volunteers, with one fifth the IM dose delivered by this route inducing HIV-1-specific CD8(+) T-cell responses of a magnitude and quality similar to those achieved by IM administration. In this long-term follow-up, we aimed to investigate the sustainability and epitopic breadth of the immune responses induced.

METHODS

In a prospective multicentre trial, 68 healthy volunteers were randomised to receive, at weeks 0, 4 and 12, either a 0.5 ml IM (500 μg of each lipopeptide; 35 volunteers) dose or a 0.1 ml ID (100 μg of each lipopeptide; 33 volunteers) dose of the LIPO-4 vaccine, in the deltoid region of the non-dominant arm. All 68 volunteers received the first two vaccinations, and 44 volunteers in the ID group and 22 in the IM group received the third. We describe here the long-term CD8(+) and CD4(+) T-cell immune responses, up to 48 weeks after the first immunisation.

RESULTS

Response frequency was highest at week 14 for CD4(+) T cells, at 85% (28/33) for the IM group and 61% (20/33) for the ID group (p=0.027), and at week 48 for CD8(+) T cells, at 36% (12/33) for the ID group and 31% (11/35) for the IM group (p=0.67). Response rates tended to be lower for volunteers receiving the third vaccination boost, whether IM or ID. Finally, we also observed a striking change in the specificity of the CD8(+) T-cell responses induced shortly (2 weeks) or several months (48 weeks) after LIPO-4 vaccination.

CONCLUSION

Lipopeptide vaccines elicited sustainable CD4(+) and CD8(+) T-cell responses, following IM or ID administration. CD8(+) T-cell responses had shifted and expanded to different epitopes after one year of follow-up. These results should facilitate the design of the next generation of prime-boost trials with repeated doses of lipopeptide vaccines.

DNA vaccines targeting human papillomavirus-associated diseases: progresses in animal and clinical studies

Human papillomavirus (HPV) infection is a major cause of cervical cancer and its precancerous diseases. Cervical cancer is the second deadliest cancer killer among women worldwide. Moreover, HPV is also known to be a causative agent of oral, pharyngeal, anal and genital cancer. Recent application of HPV structural protein (L1)-targeted prophylactic vaccines (Gardasil® and Cervarix®) is expected to reduce the incidence of HPV infection and cervical cancer, and possibly other HPV-associated cancers. However, the benefit of the prophylactic vaccines for treating HPV-infected patients is unlikely, underscoring the importance of developing therapeutic vaccines against HPV infection. In this regard, numerous types of therapeutic vaccine approaches targeting the HPV regulatory proteins, E6 and E7, have been tested for their efficacy in animals and clinically. In this communication, we review HPV vaccine types, in particular DNA vaccines, their designs and delivery by electroporation and their immunologic and antitumor efficacy in animals and humans, along with the basics of HPV and its pathogenesis.

Immunogenicity and safety of Intanza(®)/IDflu(®) intradermal influenza vaccine in South Korean adults: a multicenter, randomized trial

Intanza(®)/IDflu(®) (Sanofi Pasteur, Lyon, France) is an intradermal inactivated trivalent influenza vaccine developed as an alternative to intramuscular influenza vaccine. The objective of this study was to confirm the immunogenicity and safety of Intanza/IDflu in South Korean adults. In a phase IV multicenter trial, South Korean adults 18-59 y old (n = 120) and ≥ 60 y old (n = 120) were randomized 1:1 to receive a single dose of Intanza/IDflu (9 µg for 18-59 y, 15 µg for ≥ 60 y) or trivalent intramuscular vaccine (Vaxigrip(®) 15 µg, Sanofi Pasteur, Lyon, France). Blood was collected on pre-vaccination (day 0) and on day 21. Hemagglutination inhibition titers, seroprotection rates and seroconversion rates were determined on day 21. Geometric mean titers, seroprotection and seroconversion rates were similar between the intradermal and intramuscular vaccines in both age groups for all three vaccine strains (A/H1N1, A/H3N2 and B). Both vaccines met Committee for Medicinal Products for Human Use criteria for all three strains. Solicited systemic reactions of the intradermal groups were generally mild, transient, and similar to those of the intramuscular groups. Solicited injection site reactions were more frequent in the intradermal groups but were mostly mild, transient, and consisted mainly of pain, erythema, and pruritus. No treatment-related serious adverse events or other safety concerns were reported. These results confirm that Intanza/IDflu is an effective and well-tolerated alternative to IM influenza vaccination. (Clinicaltrials.gov NCT ID: NCT01215669).

Human CD1c+ dendritic cells drive the differentiation of CD103+ CD8+ mucosal effector T cells via the cytokine TGF-β

In comparison to murine dendritic cells (DCs), less is known about the function of human DCs in tissues. Here, we analyzed, by using lung tissues from humans and humanized mice, the role of human CD1c(+) and CD141(+) DCs in determining the type of CD8(+) T cell immunity generated to live-attenuated influenza virus (LAIV) vaccine. We found that both lung DC subsets acquired influenza antigens in vivo and expanded specific cytotoxic CD8(+) T cells in vitro. However, lung-tissue-resident CD1c(+) DCs, but not CD141(+) DCs, were able to drive CD103 expression on CD8(+) T cells and promoted CD8(+) T cell accumulation in lung epithelia in vitro and in vivo. CD1c(+) DCs induction of CD103 expression was dependent on membrane-bound cytokine TGF-β1. Thus, CD1c(+) and CD141(+) DCs generate CD8(+) T cells with different properties, and CD1c(+) DCs specialize in the regulation of mucosal CD8(+) T cells.

Understanding dendritic cells and their role in cutaneous carcinoma and cancer immunotherapy

Dendritic cells (DC) represent a diverse group of professional antigen-presenting cells that serve to link the innate and adaptive immune systems. Their capacity to initiate a robust and antigen-specific immune response has made them the ideal candidates for cancer immunotherapies. To date, the clinical impact of DC immunotherapy has been limited, which may, in part, be explained by the complex nature of DC biology. Multiple distinct subsets of DCs have been identified in the skin, where they can be broadly subcategorized into epidermal Langerhans cells (LC), myeloid-derived dermal dendritic cells (mDC) and plasmacytoid dendritic cells (pDC). Each subset is functionally unique and may activate alternate branches of the immune system. This may be relevant for the treatment of squamous cell carcinoma, where we have shown that the tumor microenvironment may preferentially suppress the activity of mDCs, while LCs remain potent stimulators of immunity. Here, we provide an in depth analysis of DC biology, with a particular focus on skin DCs and their role in cutaneous carcinoma. We further explore the current approaches to DC immunotherapy and provide evidence for the targeting of LCs as a promising new strategy in the treatment of skin cancer.

Intradermally-administered influenza virus vaccine is safe and immunogenic in healthy adults 18-64 years of age

BACKGROUND

To increase vaccine acceptance, intradermal (ID) influenza vaccine (Fluzone(®) Intradermal, Sanofi Pasteur Inc.) may be an attractive alternative to intramuscular (IM) vaccination due to smaller needle and volume injected.

METHODS

A multicenter, randomized (2:1 ID vs IM vaccines) study, blinded for ID vaccine lots, was conducted among 4292 adults 18-64 years of age enrolled in October 2008. Three lots of investigational trivalent influenza vaccine containing 9μg hemagglutinin (HA) per strain in 0.1mL administered ID with a 30 gauge, 1.5mm long needle were compared to standard dose vaccine (0.5mL containing 15μg HA/strain) given IM.

RESULTS

The post-vaccination antibody geometric mean titers (GMT) for the ID vaccine were similar to the IM vaccine (H1N1: 193.2 vs. 178.3, H3N2: 246.7 vs. 230.7, and B: 102.5 vs. 126.9). Non-inferiority was met for the ID vaccine compared to IM vaccine as assessed by antibody GMT ratios (IM/ID) for all three virus strains (H1N1: 0.92, H3N2: 0.94, and B: 1.24). Seroconversion rates were non-inferior for H1N1 and H3N2, but not for B (ID vs. IM: H1N1: 61.2% vs. 60.5%, H3N2: 75.3% vs. 74.8%, and B: 46.2% vs. 54.2%). Seroprotection (HAI titer ≥1:40) rates were similar between groups (ID vs. IM, H1N1: 91.1% vs. 91.7%, H3N2: 90.7% vs. 91.4%, and B: 87.4% vs. 89.3%). Local injection site reactions overall were more common with ID than IM vaccine (ID vs. IM: 89.2% vs. 60.2%), but were usually grade 1 or 2 and transient. The frequencies of local injection site pain and systemic reactions were similar between vaccine groups, except more myalgia with IM vaccine.

CONCLUSIONS

The ID vaccine elicited immune responses comparable to IM vaccine except for the seroconversion rate to B virus. With the exception of pain, local injection site reactions were more common with the ID vaccine, but well-tolerated and of short duration.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00772109.

Transcutaneous vaccines--current and emerging strategies

INTRODUCTION

Vaccination, which is the major fundamental prophylaxis against illness and death from infectious disease, has greatly contributed to the global improvement of human health. However, the disadvantages of conventional injection systems hamper the delivery of vaccination technologies to developing countries. The imminent practice of easy-to-use vaccination methods is expected to overcome certain issues associated with injectable vaccinations. One innovative method is the transcutaneous immunization (TCI) system.

AREAS COVERED

Two major strategies for TCI are discussed in this review. One is to promote antigen permeation of the skin barrier by patch systems or nanoparticles. The other is the delivery of antigens into the skin by electroporation and microneedles in order to physically overcome the skin barrier. Moreover, adjuvant development for TCI is discussed.

EXPERT OPINION

Many different approaches have been developed for TCI, which have the potential to be effective, easy-to-use and painless methods of vaccination. However, in practical terms, the guidelines concerning the manufacturing processes and clinical trial evaluation of the procedures have not kept pace with the development of these novel formulations. The accumulation of information regarding skin characteristics and the properties of TCI devices will help refine TCI system development guidelines and thus lead to the improvement of transcutaneous vaccination.

Intradermal application of vitamin D3 increases migration of CD14+ dermal dendritic cells and promotes the development of Foxp3+ regulatory T cells

The active form of vitamin D3 (VitD) is a potent immunosuppressive drug. Its effects are mediated in part through dendritic cells (DCs) that promote the development of regulatory T cells (Tregs). However, it remains elusive how VitD would influence the different human skin DC subsets, e.g., CD1a(+)/langerin(+) Langerhans cells, CD14(+) DDCs and CD1a(+) DDCs upon administration through the skin route in their natural environment. We addressed this issue by intradermal (ID) administration of VitD in a human skin explant system that closely resembles physiological conditions. ID injection of VitD selectively enhanced the migration of CD14(+) DDCs, a subset known for the induction of tolerance. Moreover, ID injection of VitD repressed the LPS-induced T cell stimulatory capacity of migrating DCs. These migrating DCs collectively induced T cells with suppressive activity and abolished IFN-γ productivity. Those induced T cells were characterized by the expression of Foxp3. Thus, we report the novel finding that ID injection of VitD not only modifies skin DC migration, but also programs these DCs in their natural milieu to promote the development of Foxp3(+) Tregs.

Differential capacity of human skin dendritic cells to polarize CD4+ T cells into IL-17, IL-21 and IL-22 producing cells

Accumulating evidence suggests a contribution of T cell-derived IL-17, IL-21 and IL-22 cytokines in skin immune homeostasis as well as inflammatory disorders. Here, we analyzed whether the cytokine-producing T lymphocytes could be induced by the different subsets of human skin dendritic cells (DCs), i.e., epidermal Langerhans cells (LCs), dermal CD1c(+)CD14(-) and CD14(+) DCs (DDCs). DCs were purified following a 2-day migration from separated epidermal and dermal sheets and co-cultured with allogeneic T cells before cytokine secretion was explored. Results showed that no skin DCs could induce substantial IL-17 production by naïve CD4(+) or CD8(+)T lymphocytes whereas all of them could induce IL-17 production by memory T cells. In contrast, LCs and CD1c(+)CD14(-)DDCs were able to differentiate naïve CD4(+)T lymphocytes into IL-22 and IL-21-secreting cells, LCs being the most efficient in this process. Intracellular cytokine staining showed that the majority of IL-21 or IL-22 secreting CD4(+)T lymphocytes did not co-synthesized IFN-γ, IL-4 or IL-17. IL-21 and IL-22 production were dependent on the B7/CD28 co-stimulatory pathway and ICOS-L expression on skin LCs significantly reduced IL-21 level. Finally, we found that TGF-β strongly down-regulates both IL-21 and IL-22 secretion by allogeneic CD4(+) T cells. These results add new knowledge on the functional specialization of human skin DCs and might suggest new targets in the treatment of inflammatory skin disorders.

Dendritic cells and vaccine design for sexually-transmitted diseases

Dendritic cells (DCs) are major antigen presenting cells (APCs) that can initiate and control host immune responses toward either immunity or tolerance. These features of DCs, as immune orchestrators, are well characterized by their tissue localizations as well as by their subset-dependent functional specialties and plasticity. Thus, the level of protective immunity to invading microbial pathogens can be dependent on the subsets of DCs taking up microbial antigens and their functional plasticity in response to microbial products, host cellular components and the cytokine milieu in the microenvironment. Vaccines are the most efficient and cost-effective preventive medicine against infectious diseases. However, major challenges still remain for the diseases caused by sexually-transmitted pathogens, including HIV, HPV, HSV and Chlamydia. We surmise that the establishment of protective immunity in the female genital mucosa, the major entry and transfer site of these pathogens, will bring significant benefit for the protection against sexually-transmitted diseases. Recent progresses made in DC biology suggest that vaccines designed to target proper DC subsets may permit us to establish protective immunity in the female genital mucosa against sexually-transmitted pathogens.

Skin penetration and cellular uptake of amorphous silica nanoparticles with variable size, surface functionalization, and colloidal stability

In this study, the skin penetration and cellular uptake of amorphous silica particles with positive and negative surface charge and sizes ranging from 291 ± 9 to 42 ± 3 nm were investigated. Dynamic light scattering measurements and statistical analyses of transmission electron microscopy images were used to estimate the degree of particle aggregation, which was a key aspect to understanding the results of the in vitro cellular uptake experiments. Despite partial particle aggregation occurring after transfer in physiological media, particles were taken up by skin cells in a size-dependent manner. Functionalization of the particle surface with positively charged groups enhanced the in vitro cellular uptake. However, this positive effect was contrasted by the tendency of particles to form aggregates, leading to lower internalization ratios especially by primary skin cells. After topical application of nanoparticles on human skin explants with partially disrupted stratum corneum, only the 42 ± 3 nm particles were found to be associated with epidermal cells and especially dendritic cells, independent of their surface functionalization. Considering the wide use of nanomaterials in industries and the increasing interest for applications in pharmaceutics and cosmetics versus the large number of individuals with local or spread impairment of the skin barrier, e.g., patients with atopic dermatitis and chronic eczema, a careful dissection of nanoparticle-skin surface interactions is of high relevance to assess possible risks and potentials of intended and unintended particle exposure.

Transepidermal elimination in cutaneous leishmaniasis: a multiregional study

BACKGROUND

Transepidermal elimination has been documented in a myriad of infectious diseases; however, its occurrence in cutaneous leishmaniasis has not been evaluated.

METHODS

Skin biopsies (n = 212) with cutaneous leishmaniasis in Lebanon (n = 46), Syria (n = 53), Saudi Arabia (n = 45) and Pakistan (n = 68) were evaluated. Clinical data collected included age, gender, eruption type (papule, nodule, verrucous or scar), duration and anatomic location. Histopathologically, multiple parameters were recorded including Ridley's parasitic index and pattern, transepidermal elimination, interface changes, ulceration and necrosis. Transepidermal elimination was defined as the presence of amastigotes in the epidermis in all layers, limited to the basal layer or present in a perforating plug. All cases were confirmed by polymerase chain reaction (PCR) analysis followed by restriction fragment length polymorphism analysis for molecular subspeciation.

RESULTS

Leishmania tropica was identified in 88.2% and Leishmania major in 11.8% of all cases. Transepidermal elimination was observed in 28.3% of cases (29 perforating plug, 19 all layers and 12 basal layer) with a significant prevalence of L. major in this group (35 vs. 2%, p < 0.001). Cases with transepidermal elimination were associated with interface changes and higher parasitic index (p < 0.001) but not with an increased ulceration rate (p > 0.05). Multivariate analysis showed that transepidermal elimination was independently predicted by L. major [OR (95% confidence interval) = 80 (9-712); p < 0.001], parasitic index [OR = 3.4 (2.1-5.3); p < 0.001], interface changes [OR = 6.24 (2.2-17.8); p < 0.001] and necrosis [OR = 0.2 (0.1-0.8);p = 0.026].

CONCLUSIONS

We report the largest multiregional cutaneous leishmaniasis series with a 28.3% documented transepidermal elimination incidence of which 48% were perforating plug; a significant prevalence of L. major was also identified in the transepidermal elimination group. The association of transepidermal elimination with interface changes and a higher parasitic index, without an increased ulceration rate, may reflect a unique biologic alteration in the epidermis, serving to facilitate the extrusion of the parasites through the skin.

CD34-derived dendritic cells transfected ex vivo with HIV-Gag mRNA induce polyfunctional T-cell responses in nonhuman primates

The pivotal role of DCs in initiating immune responses led to their use as vaccine vectors. However, the relationship between DC subsets involved in antigen presentation and the type of elicited immune responses underlined the need for the characterization of the DCs generated in vitro. The phenotypes of tissue-derived APCs from a cynomolgus macaque model for human vaccine development were compared with ex vivo-derived DCs. Monocyte/macrophages predominated in bone marrow (BM) and blood. Myeloid DCs (mDCs) were present in all tested tissues and were more highly represented than plasmacytoid DCs (pDCs). As in human skin, Langerhans cells (LCs) resided exclusively in the macaque epidermis, expressing CD11c, high levels of CD1a and langerin (CD207). Most DC subsets were endowed with tissue-specific combinations of PRRs. DCs generated from CD34(+) BM cells (CD34-DCs) were heterogeneous in phenotype. CD34-DCs shared properties (differentiation and PRR) of dermal and epidermal DCs. After injection into macaques, CD34-DCs expressing HIV-Gag induced Gag-specific CD4(+) and CD8(+) T cells producing IFN-γ, TNF-α, MIP-1β, or IL-2. In high responding animals, the numbers of polyfunctional CD8(+) T cells increased with the number of booster injections. This DC-based vaccine strategy elicited immune responses relevant to the DC subsets generated in vitro.

Monocytes differentiation upon treatment with a peptide corresponding to the C-terminus of activated T cell-expressed Tirc7 protein

Atp6v0a3 gene encodes for two alternative products, Tirc7 and a3 proteins, which are differentially expressed in activated T cells and resorbing osteoclasts, respectively. Tirc7 plays a central role in T cell activation, while a3 protein is critical for osteoclast-mediated bone matrix resorption. Based on the large body of evidences documenting the relationships between T cells and osteoclasts, we hypothesized that the extracellular C-terminus of Tirc7 protein could directly interact with osteoclast precursor cells. To address this issue, we performed the molecular cloning of a mouse Atp6v0a3 cDNA segment encoding the last 40 amino acids of Tirc7 protein, and we used this peptide as a ligand added to mouse osteoclast precursor cells. We evidenced that Tirc7-Cter peptide induced the differentiation of RAW264.7 cells into osteoclast-like cells, stimulated an autocrine/paracrine regulatory loop potentially involved in osteoclastic differentiation control, and strongly up-regulated F4/80 protein expression within multinucleated osteoclast-like cells. Using a mouse bone marrow-derived CD11b(+) cell line, or total bone marrow primary cells, we observed that similarly to Rankl, Tirc7-Cter peptide induced the formation of TRACP-positive large multinucleated cells. At last, using mouse primary monocytes purified from total bone marrow, we determined that Tirc7-Cter peptide induced the appearance of small multinucleated cells (3-4 nuclei), devoid of resorbing activity, and which displayed modulations of dendritic cell marker genes expression. In conclusion, we report for the first time on biological effects mediated by a peptide corresponding to the C-terminus of Tirc7 protein, which interfere with monocytic differentiation pathways.

Transcutaneous vaccination via laser microporation

Driven by constantly increasing knowledge about skin immunology, vaccine delivery via the cutaneous route has recently gained renewed interest. Considering its richness in immunocompetent cells, targeting antigens to the skin is considered to be more effective than intramuscular or subcutaneous injections. However, circumvention of the superficial layer of the skin, the stratum corneum, represents the major challenge for cutaneous immunization. An optimal delivery method has to be effective and reliable, but also highly adaptable to specific demands, should avoid the use of hypodermic needles and the requirement of specially trained healthcare workers. The P.L.E.A.S.E.® (Precise Laser Epidermal System) device employed in this study for creation of aqueous micropores in the skin fulfills these prerequisites by combining the precision of its laser scanning technology with the flexibility to vary the number, density and the depth of the micropores in a user-friendly manner. We investigated the potential of transcutaneous immunization via laser-generated micropores for induction of specific immune responses and compared the outcomes to conventional subcutaneous injection. By targeting different layers of the skin we were able to bias polarization of T cells, which could be modulated by addition of adjuvants. The P.L.E.A.S.E.® device represents a highly effective and versatile platform for transcutaneous vaccination.

Intradermally administered TLR4 agonist GLA-SE enhances the capacity of human skin DCs to activate T cells and promotes emigration of Langerhans cells

The natural TLR4 agonist lipopolysaccharide (LPS) has notable adjuvant activity. However, it is not useful as a vaccine adjuvant due to its toxicity. Glucopyranosyl lipid A (GLA) is a synthetic derivative of the lipid A tail of LPS with limited cytotoxicity, but strong potential to induce immune responses in mice, guinea pigs, non-human primates, and humans. In this study we determined how this synthetic TLR4 agonist affects the function of different subsets of human skin dendritic cells (DCs). The effect of GLA in an aqueous formulation (GLA-AF) or in an oil-in-water emulsion (GLA-SE) was compared to that of LPS and TLR3 agonist poly(I:C) using a human skin explant model with intradermal injections for the administration of the agonists. Intradermal injection of GLA-SE or LPS, but not GLA-AF, enhanced the emigration of CD1a(high)/langerin(+) Langerhans cells (LCs), but not dermal DCs (DDCs). LCs and CD14(-) DDCs exhibited an enhanced mature phenotype following intradermal administration of either of the two GLA formulations tested, similar to DCs that emigrated from LPS-injected skin. However, only injection of GLA-SE resulted in a significant increase in the production of the wide range of cytokines that is observed with LPS. Moreover, DCs that emigrated from GLA-SE-injected skin induced stronger CD4(+) T-cell activation, as indicated by a more pronounced T-cell proliferation, than DCs from skin injected with GLA-AF or LPS. Altogether, our data show that GLA-SE has a notable potency to stimulate the function of skin DCs, indicating that GLA-SE may be a good candidate as adjuvant for vaccines administered via the intradermal route.

Microneedle-mediated vaccine delivery: harnessing cutaneous immunobiology to improve efficacy

INTRODUCTION

Breaching the skin's stratum corneum barrier raises the possibility of the administration of vaccines, gene vectors, antibodies and even nanoparticles, all of which have at least their initial effect on populations of skin cells.

AREAS COVERED

Intradermal vaccine delivery holds enormous potential for improved therapeutic outcomes for patients, particularly those in the developing world. Various vaccine-delivery strategies have been employed, which are discussed in this review. The importance of cutaneous immunobiology on the effect produced by microneedle-mediated intradermal vaccination is also discussed.

EXPERT OPINION

Microneedle-mediated vaccines hold enormous potential for patient benefit. However, in order for microneedle vaccine strategies to fulfill their potential, the proportion of an immune response that is due to the local action of delivered vaccines on skin antigen-presenting cells, and what is due to a systemic effect from vaccines reaching the systemic circulation, must be determined. Moreover, industry will need to invest significantly in new equipment and instrumentation in order to mass-produce microneedle vaccines consistently. Finally, microneedles will need to demonstrate consistent dose delivery across patient groups and match this to reliable immune responses before they will replace tried-and-tested needle-and-syringe-based approaches.

Cancer immunotherapy via dendritic cells

Cancer immunotherapy attempts to harness the power and specificity of the immune system to treat tumours. The molecular identification of human cancer-specific antigens has allowed the development of antigen-specific immunotherapy. In one approach, autologous antigen-specific T cells are expanded ex vivo and then re-infused into patients. Another approach is through vaccination; that is, the provision of an antigen together with an adjuvant to elicit therapeutic T cells in vivo. Owing to their properties, dendritic cells (DCs) are often called 'nature's adjuvants' and thus have become the natural agents for antigen delivery. After four decades of research, it is now clear that DCs are at the centre of the immune system owing to their ability to control both immune tolerance and immunity. Thus, DCs are an essential target in efforts to generate therapeutic immunity against cancer.

Dendritic cells in the pathogenesis and treatment of human diseases: a Janus Bifrons?

Dendritic cells (DCs) represent the bridging cell compartment between a variety of nonself antigens (i.e., microbial, cancer and vaccine antigens) and adaptive immunity, orchestrating the quality and potency of downstream immune responses. Because of the central role of DCs in the generation and regulation of immunity, the modulation of DC function in order to shape immune responses is gaining momentum. In this respect, recent advances in understanding DC biology, as well as the required molecular signals for induction of T-cell immunity, have spurred many experimental strategies to use DCs for therapeutic immunological approaches for infections and cancer. However, when DCs lose control over such 'protective' responses - by alterations in their number, phenotype and/or function - undesired effects leading to allergy and autoimmune clinical manifestations may occur. Novel therapeutic approaches have been designed and currently evaluated in order to address DCs and silence these immunopathological processes. In this article we present recent concepts of DC biology and some medical implications in view of therapeutic opportunities.

Ionizing radiation: the good, the bad, and the ugly

Skin changes caused by ionizing radiation have been scientifically documented since 1902. Ionizing radiation is a widely accepted form of treatment for various types of cancer. Despite the technological advances, radiation skin injury remains a significant problem. This injury, often referred to as radiation dermatitis, occurs in about 95% of patients receiving radiation therapy for cancer, and ranges in severity from mild erythema to moist desquamation and ulceration. Ionizing radiation is not only a concern for cancer patients, but also a public health concern because of the potential for and reality of a nuclear and/or radiological event. Recently, the United States has increased efforts to develop medical countermeasures to protect against radiation toxicities from acts of bioterrorism, as well as cancer treatment. Management of radiation dermatitis would improve the therapeutic benefit of radiation therapy for cancer and potentially the mortality expected in any "dirty bomb" attack. Currently, there is no effective treatment to prevent or mitigate radiation skin injury. This review summarizes "the good, the bad, and the ugly" of current and evolving knowledge regarding mechanisms of and treatments for radiation skin injury.

Innate immunity in allergic disease

The innate immune system consists of multiple cell types that express germline-encoded pattern recognition receptors that recognize pathogen-associated molecular patterns (PAMPs) or danger-associated molecular patterns (DAMPs). Allergens are frequently found in forms and mixtures that contain PAMPs and DAMPs. The innate immune system is interposed between the external environment and the internal acquired immune system. It is also an integral part of the airways, gut, and skin. These tissues face continuous exposure to allergens, PAMPs, and DAMPs. Interaction of allergens with the innate immune system normally results in immune tolerance but, in the case of allergic disease, this interaction induces recurring and/or chronic inflammation as well as the loss of immunologic tolerance. Upon activation by allergens, the innate immune response commits the acquired immune response to a variety of outcomes mediated by distinct T-cell subsets, such as T-helper 2, regulatory T, or T-helper 17 cells. New studies highlighted in this review underscore the close relationship between allergens, the innate immune system, and the acquired immune system that promotes homeostasis versus allergic disease.

The tug-of-war between dendritic cells and human chronic viruses

The human immune system is under constant challenge from many viruses, some of which the body is successfully able to clear. Other viruses have evolved to escape the host immune responses and thus persist, leading to the development of chronic diseases. Dendritic cells are professional antigen-presenting cells that play a major role in both innate and adaptive immunity against different pathogens. This review focuses on the interaction of different chronic viruses with dendritic cells and the viruses' ability to exploit this critical cell type to their advantage so as to establish persistence within the host.

Probiotics for photoprotection

Specific strains of probiotic, have been identified as beneficial to influence the composition and/or metabolic activity of the endogenous microbiota and some of these strains have been also shown to inhibit the growth of a wide range of enteropathogens. The first aim of using probiotics has been to improve the composition of the intestinal microbiota from a potentially harmful composition towards a composition that would be beneficial to the host.Beyond their capacity to influence positively the composition of the intestinal microbiota, several lines of evidence suggest that some probiotic bacteria can modulate the immune system both at the local and systemic levels thereby improving immune defense mechanisms and/or downregulate immune disorders such as allergies or intestinal inflammation.Skin reflects the general health status and aging. Different human trials widely suggest that probiotic supplementation might be useful in the management of atopic dermatitis. Based on these properties it appears that, beyond the gut, probiotics might exert their benefits at the skin level.In a randomized double blind placebo-controlled clinical trial, we investigated whether the probiotic bacteria Lactobacillus johnsonii NCC 533 (La1) could modulate the cutaneous immune homeostasis altered by solar-simulated UV exposure in humans. After, UV exposure to twice 1.5 MED, we demonstrated that La1 intake facilitated an earlier recovery of Epidermal cells allostimulatory function. Thus, this clinical data strengthen the assumption that certain probiotics can contribute to modulate skin immune system leading to the preservation of the skin homeostasis. Altogether the data affords the possibility of designing new strategies based on a nutritional approach for the prevention of UV-induced damaging effects.

Immune suppression in head and neck cancers: a review

Head and neck squamous cell carcinomas (HNSCCs) are the sixth most common cancer in the world. Despite significant advances in the treatment modalities involving surgery, radiotherapy, and concomitant chemoradiotherapy, the 5-year survival rate remained below 50% for the past 30 years. The worse prognosis of these cancers must certainly be link to the fact that HNSCCs strongly influence the host immune system. We present a critical review of our understanding of the HNSCC escape to the antitumor immune response such as a downregulation of HLA class I and/or components of APM. Antitumor responses of HNSCC patients are compromised in the presence of functional defects or apoptosis of T-cells, both circulating and tumor-infiltrating. Langerhans cells are increased in the first steps of the carcinogenesis but decreased in invasive carcinomas. The accumulation of macrophages in the peritumoral areas seems to play a protumoral role by secreting VEGF and stimulating the neoangiogenesis.

Microneedle vaccination with stabilized recombinant influenza virus hemagglutinin induces improved protective immunity

The emergence of the swine-origin 2009 influenza pandemic illustrates the need for improved vaccine production and delivery strategies. Skin-based immunization represents an attractive alternative to traditional hypodermic needle vaccination routes. Microneedles (MNs) can deliver vaccine to the epidermis and dermis, which are rich in antigen-presenting cells (APC) such as Langerhans cells and dermal dendritic cells. Previous studies using coated or dissolvable microneedles emphasized the use of inactivated influenza virus or virus-like particles as skin-based vaccines. However, most currently available influenza vaccines consist of solubilized viral protein antigens. Here we test the hypothesis that a recombinant subunit influenza vaccine can be delivered to the skin by coated microneedles and can induce protective immunity. We found that mice vaccinated via MN delivery with a stabilized recombinant trimeric soluble hemagglutinin (sHA) derived from A/Aichi/2/68 (H3) virus had significantly higher immune responses than did mice vaccinated with unmodified sHA. These mice were fully protected against a lethal challenge with influenza virus. Analysis of postchallenge lung titers showed that MN-immunized mice had completely cleared the virus from their lungs, in contrast to mice given the same vaccine by a standard subcutaneous route. In addition, we observed a higher ratio of antigen-specific Th1 cells in trimeric sHA-vaccinated mice and a greater mucosal antibody response. Our data therefore demonstrate the improved efficacy of a skin-based recombinant subunit influenza vaccine and emphasize the advantage of this route of vaccination for a protein subunit vaccine.

Targeting human dendritic cell subsets for improved vaccines

Dendritic cells (DCs) were discovered in 1973 by Ralph Steinman as a previously undefined cell type in the mouse spleen and are now recognized as a group of related cell populations that induce and regulate adaptive immune responses. Studies of the past decade show that, both in mice and humans, DCs are composed of subsets that differ in their localization, phenotype, and functions. These progresses in our understanding of DC biology provide a new framework for improving human health. In this review, we discuss human DC subsets in the context of their medical applications, with a particular focus on DC targeting.

Insight into the immunobiology of human skin and functional specialization of skin dendritic cell subsets to innovate intradermal vaccination design

Dendritic cells (DC) are the key initiators and regulators of any immune response which determine the outcome of CD4(+) and CD8(+) T-cell responses. Multiple distinct DC subsets can be distinguished by location, phenotype, and function in the homeostatic and inflamed human skin. The function of steady-state cutaneous DCs or recruited inflammatory DCs is influenced by the surrounding cellular and extracellular skin microenvironment. The skin is an attractive site for vaccination given the extended local network of DCs and the easy access to the skin-draining lymph nodes to generate effector T cells and immunoglobulin-producing B cells for long-term protective immunity. In the context of intradermal vaccination we describe in this review the skin-associated immune system, the characteristics of the different skin DC subsets, the mechanism of antigen uptake and presentation, and how the properties of DCs can be manipulated. This knowledge is critical for the development of intradermal vaccine strategies and supports the concept of intradermal vaccination as a superior route to the conventional intramuscular or subcutaneous methods.

HIV-1 replication in Langerhans and interstitial dendritic cells is inhibited by neutralizing and Fc-mediated inhibitory antibodies

Langerhans cells (LCs) and interstitial dendritic cells (IDCs) may be among the first human immunodeficiency virus type 1 (HIV-1) targets after sexual transmission. We generated cells of these types by differentiation of purified CD34(+) cord blood cells. After in vitro infection with R5-tropic strains, we obtained similar percentages of infected cells for both dendritic cell (DC) subsets. Moreover, LC infection was not increased by blockage of langerin by antilangerin. These results indicate that, under our experimental conditions, there was no evidence of any preference of HIV replication in LCs versus IDCs. The inhibitory activity of HIV-1-specific IgAs and IgGs against HIV-1 replication in LCs and IDCs was analyzed. We found that neutralizing antibodies inhibit HIV-1 infection of both DC subsets. Interestingly, HIV-1 was inhibited more efficiently by the IgGs than the corresponding IgA, due to an Fcγ receptor-dependent mechanism. Moreover, nonneutralizing inhibitory IgGs were able to inhibit infection of both LCs and IDCs. These results underline the importance of HIV-1 inhibition by the binding of the Fc part of IgGs to Fcγ receptors and suggest that the induction of neutralizing and nonneutralizing inhibitory IgGs in addition to neutralizing IgAs at mucosal sites may contribute to protection against sexual transmission of HIV-1.

Designing vaccines based on biology of human dendritic cell subsets

The effective vaccines developed against a variety of infectious agents, including polio, measles, and hepatitis B, represent major achievements in medicine. These vaccines, usually composed of microbial antigens, are often associated with an adjuvant that activates dendritic cells (DCs). Many infectious diseases are still in need of an effective vaccine including HIV, malaria, hepatitis C, and tuberculosis. In some cases, the induction of cellular rather than humoral responses may be more important because the goal is to control and eliminate the existing infection rather than to prevent it. Our increased understanding of the mechanisms of antigen presentation, particularly with the description of DC subsets with distinct functions, as well as their plasticity in responding to extrinsic signals, represent opportunities to develop novel vaccines. In addition, we foresee that this increased knowledge will permit us to design vaccines that will reprogram the immune system to intervene therapeutically in cancer, allergy, and autoimmunity.

Differential gene expression analysis identifies murine Cacnb3 as strongly upregulated in distinct dendritic cell populations upon stimulation

Langerhans cells (LCs) represent the dendritic cell (DC) population in the epidermis. Among the set of genes induced in primary mouse LCs in response to stimulation, both isoforms of the voltage-dependent Ca²(+) channel (VDCC) regulatory subunit Cacnb3 as well as the DC maturation marker Fscn1 were upregulated most strongly. Comparable results were obtained for a recently described myeloid DC line (SP37A3). Other antigen presenting cell populations, namely, bone marrow-derived DCs, macrophages and primary B cells, showed no stimulation-associated upregulation of Cacnb3 expression. Pharmacological inhibition of Ca²(+) channel activity during the stimulation of SP37A3 cells enhanced their T cell stimulatory capacity, while selective inhibition of L-type VDCC had no effect. Both Cacnb3 isoforms, similar to Fscn1, required JNK and p38 kinase activity for stimulation-associated upregulation, and this process was inhibited by ERK and PI(3)K. The putative promoter region of Cacnb3 isoform 2, which we found to be less ubiquitously expressed than Cacnb3 isoform 1, exerted reporter activity in LC-like cell lines. Our findings suggest that Cacnb3 exerts its function in distinct activated DC populations. Further analysis of the regulatory region(s) facilitating stimulation-induced upregulation of Cacnb3 expression in these DC subsets will help to gain better insight into DC subset specific gene regulation.

Simian virus 40 inhibits differentiation and maturation of rhesus macaque DC-SIGN(+) dendritic cells

Dendritic cells (DC) are the initiators and modulators of the immune responses. Some species of pathogenic microorganisms have developed immune evasion strategies by controlling antigen presentation function of DC. Simian virus 40 (SV40) is a DNA tumor virus of rhesus monkey origin. It can induce cell transformation and tumorigenesis in many vertebrate species, but often causes no visible effects and persists as a latent infection in rhesus monkeys under natural conditions. To investigate the interaction between SV40 and rhesus monkey DC, rhesus monkey peripheral blood monocyte-derived DC were induced using recombinant human Interleukin-4 (rhIL-4) and infective SV40, the phenotype and function of DC-specific intracellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN)(+) DC were analyzed by flow cytometry (FCM) and mixed lymphocyte reaction (MLR). Results showed that SV40 can down-regulate the expression of CD83 and CD86 on DC and impair DC-induced activation of T cell proliferation. These findings suggest that SV40 might also cause immune suppression by influencing differentiation and maturation of DC.

Dose sparing enabled by skin immunization with influenza virus-like particle vaccine using microneedles

To address the limitations of conventional influenza vaccine manufacturing and delivery, this study investigated administration of virus-like particle (VLP) influenza vaccine using a microneedle patch. The goal was to determine if skin immunization with influenza VLP vaccine using microneedles enables dose sparing. We found that low-dose influenza (A/PR/8/34 H1N1) VLP vaccination using microneedles was more immunogenic than low-dose intramuscular (IM) vaccination and similarly immunogenic as high-dose IM vaccination in a mouse model. With a 1μg dose of vaccine, both routes showed similar immune responses and protective efficacy, with microneedle vaccination being more effective in inducing recall antibody responses in lungs and antibody secreting cells in bone marrow. With a low dose of vaccine (0.3μg), microneedle vaccination induced significantly superior protective immunity, which included binding and functional antibodies as well as complete protection against a high dose lethal infection with A/PR/8/34 virus, whereas IM immunization provided only partial (40%) protection. Therefore, this study demonstrates that microneedle vaccination in the skin confers more effective protective immunity at a lower dose, thus providing vaccine dose-sparing effects.

Herpes simplex virus infects skin gamma delta T cells before Langerhans cells and impedes migration of infected Langerhans cells by inducing apoptosis and blocking E-cadherin downregulation

The role individual skin dendritic cell (DC) subsets play in the immune response to HSV remains unclear. We investigated the effect of HSV on DC virus uptake, viability, and migration after cutaneous infection in vitro and in vivo. HSV increased the emigration of skin DCs from whole skin explants over 3 d postinfection (p.i.) compared with mock controls, but the kinetics of emigration was influenced by the skin DC subset. Uninfected (bystander) Langerhans cells (LCs) were the major emigrant DC subset at 24 h p.i., but thereafter, large increases in infected CD103(+)langerin(+) dermal DC (dDC) and uninfected langerin(-) dDC emigration were also observed. LC infection was confirmed by the presence of HSV glycoprotein D (gD) and was associated with impaired migration from cultured skin. Langerin(+) dDC also expressed HSV gD, but infection did not impede migration. We then followed the virus in live MacGreen mice in which LCs express GFP using a fluorescent HSV-1 strain by time-lapse confocal microscopy. We observed a sequential infection of epidermal cells, first in keratinocytes and epidermal gammadelta T cells at 6 h p.i., followed by the occurrence of HSVgD(+) LCs at 24 h p.i. HSV induced CCR7 upregulation on all langerin(+) DC, including infected LCs, and increased production of skin TNF-alpha and IL-1beta. However, a large proportion of infected LCs that remained within the skin was apoptotic and failed to downregulate E-cadherin compared with bystander LCs or mock controls. Thus, HSV infection of LCs is preceded by infection of gammadelta T cells and delays migration.

Harnessing human dendritic cell subsets for medicine

Immunity results from a complex interplay between the antigen-non-specific innate immune system and the antigen-specific adaptive immune system. The cells and molecules of the innate system employ non-clonal recognition receptors including lectins, Toll-like receptors, NOD-like receptors, and helicases. B and T lymphocytes of the adaptive immune system employ clonal receptors recognizing antigens or their derived peptides in a highly specific manner. An essential link between innate and adaptive immunity is provided by dendritic cells (DCs). DCs can induce such contrasting states as immunity and tolerance. The recent years have brought a wealth of information on the biology of DCs revealing the complexity of this cell system. Indeed, DC plasticity and subsets are prominent determinants of the type and quality of elicited immune responses. In this article, we summarize our recent studies aimed at a better understanding of the DC system to unravel the pathophysiology of human diseases and design novel human vaccines.

Origin and functional heterogeneity of non-lymphoid tissue dendritic cells in mice

Dendritic cells (DCs) have been extensively studied in mice lymphoid organs, but less is known about the origin and the mechanisms that regulate DC development and function in non-lymphoid tissues. Here, we discuss recent evidence establishing the contribution of the DC-restricted lineage to the non-lymphoid tissue DC pool and discuss the mechanisms that control the homeostasis of non-lymphoid tissue DCs. We also review recent results underlining the functional specialization of tissue DCs and discuss the potential implications of these findings in tissue immunity and in the development of novel vaccine strategies.

Langerin-expressing dendritic cells in gut-associated lymphoid tissues

Dendritic cells (DCs) are key regulators of the immune system. They act as professional antigen-presenting cells and are capable of activating naive T cells and stimulating the growth and differentiation of B cells. According to their molecular expression, DCs can be divided into several subsets with different functions. We focus on DC subsets expressing langerin, a C-type lectin. Langerin expression is predominant in skin DCs, but langerin-expressing DCs also exist in mucosal tissue and can be induced by immunization and sometimes by nutrient deficiency. Topical transcutaneous immunization induces langerin(+)CD8 alpha(-) DCs in mesenteric lymph nodes (MLNs), which mediate the production of antigen-specific immunoglobulin A antibody in the intestine. Yet, in one recent study, langerin(+) DCs were generated in gut-associated lymphoid tissue and contributed to the suppressive intestinal immune environment in the absence of retinoic acid. In this review, we focus on the phenotypic and functional characteristics of langerin(+) DCs in the mucosal tissues, especially MLNs.

Impact of varicella-zoster virus on dendritic cell subsets in human skin during natural infection

Varicella-zoster virus (VZV) causes varicella and herpes zoster, diseases characterized by distinct cutaneous rashes. Dendritic cells (DC) are essential for inducing antiviral immune responses; however, the contribution of DC subsets to immune control during natural cutaneous VZV infection has not been investigated. Immunostaining showed that compared to normal skin, the proportion of cells expressing DC-SIGN (a dermal DC marker) or DC-LAMP and CD83 (mature DC markers) were not significantly altered in infected skin. In contrast, the frequency of Langerhans cells was significantly decreased in VZV-infected skin, whereas there was an influx of plasmacytoid DC, a potent secretor of type I interferon (IFN). Langerhans cells and plasmacytoid DC in infected skin were closely associated with VZV antigen-positive cells, and some Langerhans cells and plasmacytoid DC were VZV antigen positive. To extend these in vivo observations, both plasmacytoid DC (PDC) isolated from human blood and Langerhans cells derived from MUTZ-3 cells were shown to be permissive to VZV infection. In VZV-infected PDC cultures, significant induction of alpha IFN (IFN-alpha) did not occur, indicating the VZV inhibits the capacity of PDC to induce expression of this host defense cytokine. This study defines changes in the response of DC which occur during cutaneous VZV infection and implicates infection of DC subtypes in VZV pathogenesis.

Transcutaneous immunization studies in mice using diphtheria toxoid-loaded vesicle formulations and a microneedle array

Purpose

To determine the immunogenicity of diphtheria toxoid (DT) formulated in two types of vesicles following transcutaneous immunization (TCI) of mice onto microneedle array-treated skin.

Methods

DT-containing cationic liposomes or anionic surfactant-based vesicles were prepared by extrusion and sonication. The physicochemical properties were characterized in terms of size, ζ-potential, vesicle elasticity and antigen association. TCI was performed by applying formulations onto intact or microneedle array-pretreated mice skin, using cholera toxin as an adjuvant. Subcutaneous and intradermal immunizations were as control. Immune responses were evaluated by IgG and neutralizing antibody titers, and the immune-stimulatory properties were assessed using cultured dendritic cells.

Results

Stable DT-containing cationic liposomes (∼150 nm) and anionic vesicles (∼100 nm) were obtained. Incorporation of Span 80 increased liposome elasticity. About 90% and 77% DT was associated with liposomes and vesicles, respectively. TCI of all formulations resulted in substantial antibody titers only if microneedle pretreatment was applied. Co-administration of cholera toxin further augmented the immune responses of TCI. However, vesicle formulations didn’t enhance the immunogenicity on either intact or microneedle-treated skin and showed low stimulatory activity on dendritic cells.

Conclusions

Microneedle pretreatment and cholera toxin, but not antigen association to vesicles, enhances the immunogenicity of topically applied DT.