Polymeric lamellar substrate particles for intranasal vaccination

The incorporation of cationic property and immunopotentiator in poly (lactic acid) microparticles promoted the immune response against chronic hepatitis B

Biodegradable microparticles (MPs) as vaccine adjuvants have sparked the passion of researchers in recent decades. However, it is still a huge challenge to develop an efficient vaccine delivery system to reverse chronic hepatitis B (CHB). Herein, we integrated a physiochemical merit and an immunopotentiator property in poly (lactic acid) (PLA) MPs and verified the therapeutic effect on CHB model mice. We prepared uniform MPs with insertion of cationic lipid didodecyldimethylammonium bromide (DDAB), which endowed a physiochemical merit for MPs. Such a DDAB-PLA (DP) group raised the recruitment of immune cells to the injection site along with the secretion of chemokines and pro-inflammatory cytokines, promoting the activation of antigen-presenting cells (APCs). Further combination of stimulator of interferon genes (STING) agonist 5,6-dimethylxanthenone-4-acetic acid (DMXAA) (DP-D) elevated 5.8-fold higher interferon regulatory factor 7 (IRF-7) expression compared to that for DP group. The DP group showed preferred lysosome escape advantage, which was in line with the DMXAA release behavior and the intracellular target of DMXAA. In addition, DP-D vaccine augmented the IFN-γ secreting splenocytes and motivated Th1-biased antibodies in a more efficient way than that for the DP group. In the CHB model, the MPs based vaccines achieved 50% HBsAg seroconversion rate, and HBcAg in the liver also got a reduction. DP-D produced higher amount of memory T/B cells to confer protection in a sustained manner. Present work thus provided a promising strategy, via integrating a fine-tuned physiochemical property and an immunopotentiator virtue in the MPs, which synergistically reinforced both humoral and cellular immune responses against CHB.

Nanocarriers: a versatile approach for mucosal vaccine delivery

Infectious agents generally use mucosal surfaces as entry port to the body thereby necessitating the need of development of mucosal vaccine as vaccination is important for disease avoidance and suppression. Vaccination through mucosal route is a promising strategy to elicit efficient immune response as parentally administered vaccines induce poor mucosal immunity in general. Safety, economy and stability are highly desired with vaccines and this can be achieved with use of delivery cargos. This review focuses on challenges related with mucosal vaccines and use of nanocarriers as suitable cargos to cater the antigen effectively to the desired site. The review also includes different factors which are to be considered regarding the performance of the nanocarriers and clinical status of these systems.

Sufficiency of a single administration of filarial antigens adsorbed on polymeric lamellar substrate particles of poly (L-lactide) for immunization

A majority of antigens require repeated administration to ensure development of adequate humoral and cell mediated immune response. To minimize the number of administrations required, we investigated the utility of biodegradable polymeric lamellar substrate particles of poly (l-lactide) (PLSP) as adjuvant for filarial antigen preparations. PLSP was prepared and characterized and Brugia malayi adult worm extract (BmA) and its SDS-PAGE resolved 54-68 kDa fraction F6 were adsorbed on to PLSP. Swiss mice received a single injection of PLSP-F6, PLSP-BmA, FCA-F6, FCA-BmA and two doses of the plain antigens. Specific IgG, IgG1, IgG2a, IgG2b and IgE levels in serum, IFN-γ, TNF-α and nitric oxide (NO) release from cells of the immunized animals in response to antigen challenge were studied. The average size of PLSP particles was <10 μm and its % antigen adsorption efficacy was 60.4, 55.2 and 61.6 for BSA, BmA and F6, respectively. Single injection of PLSP-F6 or PLSP-BmA produced better immune responses compared to one injection of FCA-F6/BmA or two injections of plain F6 or BmA. Moreover, PLSP-F6 produced much better response than PLSP-BmA. These data demonstrate for the first time that PLSP is a superior immunoadjuvant for enhancing the immune response to filarial BmA and F6 molecules and obviates the need for multiple immunization injections.

Single shot tetanus vaccine manufactured by a supercritical fluid encapsulation technology

Single shot vaccines of tetanus toxoid (TT) were manufactured using the NanoMix process - a low temperature solvent free encapsulation technology using supercritical fluids. The formulations were injected into mice, and compared to multiple injections of a commercially available alum adsorbed TT vaccine. After 5 months the antibody titres were found to be similar for both the alum adsorbed and microparticle formulations, demonstrating for the first time the potential of formulating antigens in PLA microparticles using the supercritical fluid (NanoMix) technique to produce single shot vaccines. The results are likely to be due to the maintenance of toxoid bioactivity and some degree of sustained release of the encapsulated antigens, resulting in repeated stimulation of antigen presenting cells eliminating the need for multiple immunisations. This demonstrates the potential of this supercritical fluid processing technique to reduce the need for booster doses in a vaccine regimen.

Nasal vaccine innovation

The current vaccine market is gaining momentum in the development of alternative administration routes namely intranasal, oral, topical, pulmonary, vaginal, and rectal; the nasal route offers the most promising opportunity for vaccine administration. It can enhance convenience, safety, elicit both local and systemic immune responses; thus potentially provide protection from pathogens at the site of entry. Nasal vaccine innovation comes with both opportunities and challenges. The innovative strategies used by industry and researchers to overcome the hurdles are discussed in this article: these include live-attenuated vaccines, adjuvants, mucoadhesives, particulate delivery systems, virus-like particles, vaccine manufacture, challenges of regulatory authorities, and the nasal vaccine impact on market potential. Critical issues for effective nasal vaccination are the antigen-retention period that enables its interaction with the lymphatic system and choice of an adjuvant that is nontoxic and induces the required immune response. Co-adjuvanting by means of a mucoadhesive technology addresses some of these issues. ChiSys(®), a natural bioadhesive with proven intranasal safety profile, has already demonstrated efficacy for several nasally delivered vaccines including norovirus. With the looming threat of a pandemic, alternatives such as intranasal vaccination will ultimately facilitate greater public compliance and rapid mass global vaccination.

Amorphous phase-segregated copoly(ether)esterurethane thermoset networks with oligo(propylene glycol) and oligo[(rac-lactide)-co-glycolide] segments: synthesis and characterization

Completely amorphous copoly(ether)ester networks based on oligo(propylene glycol) and oligo[(rac-dilactide)-co-glycolide] segments were synthesized by crosslinking star-shaped hydroxyl-telechelic cooligomers using an aliphatic low-molecular weight diisocyanate. Two different network architectures were applied exhibiting differences in the phase-separation behavior. For networks from oligo(propylene glycol)-block-oligo[(rac-lactide)-co-glycolide] triols (G(3)OPG-bl-OLG) only one glass transition was obtained. However, networks from a mixture of oligo(propylene glycol) triols (G(3)OPG) and oligo[(rac-lactide)-co-glycolide] tetrols (P(4)OLG) with a ratio of components in a certain range show two glass transition temperatures (T (g)) being attributed to two segregated amorphous phases. In this way a wide spectrum of mechanical properties can be realized and adjusted to the requirements of a specific application.

Administration of Optimum Sustained-Insulin Release PLGA Microcapsules to Spontaneous Diabetes-Prone BB/WorTky Rats

To show the possibility of sustained-release insulin formulation composed of PLGA, the optimum one was administered to BioBreeding rat, a model of spontaneous type I diabetes mellitus (IDDM). Every 2 weeks subcutaneous administration made their blood glucose level depend on the insulin release and food intake. However, all of them kept alive with little change or rather a little gain in body weight. Furthermore, some of pregnant rats with intermittent treatment bore fetuses, although additional insulin therapy seemed necessary. Therefore, the formulation could become a new tool as a provider of basal insulin for IDDM patients.

A new intranasal influenza vaccine based on a novel polycationic lipid—ceramide carbamoyl-spermine (CCS)

Although most pathogens use the mucosal routes for invasion, the majority of currently available vaccines are administered parenterally. Injectable vaccines induce good systemic immunity but often unsatisfactory mucosal immunity. A non-injectable mucosal vaccine, which can be self-administered intranasally, may provide both effective systemic and mucosal immunity and can be used for vaccination of large populations within a short period of time in case of a sudden epidemic. Here, we report on a new intranasal (i.n.) influenza vaccine, based on a novel polycationic sphingolipid, N-palmitoyl D-erythro-sphingosyl carbamoyl-spermine (ceramide carbamoyl-spermine = CCS), having combined carrier and adjuvant activities, which elicits, in mice, strong systemic (serum) and local (lung and nasal) humoral and cellular responses, and provides protective immunity. In a comparative study, we show that both unmodified commercial vaccine and vaccine formulated with neutral or anionic liposomes were poorly immunogenic upon i.n. administration. Of five vaccine formulations based on well-established monocationic lipids in the form of unsized liposomes, three (DC-Chol, DDAB, and DSTAP-based) resulted in low serum and local responses, while two others (DMTAP and DOTAP-based vaccines) induced both systemic and local vigorous Th1+Th2 immune responses. However, only the vaccine formulated with CCS was equivalent or superior to the commercial vaccine co-administered with cholera toxin as an adjuvant. Furthermore, the CCS-based influenza vaccine was highly efficacious following a single or a repeated (x2) i.n. or a single i.m. administration, without an added adjuvant, in both young (2 months) and old (18 months) mice. It elicited high titers of strain cross-reactive hemagglutination inhibition (HI) antibodies, and the high antibody titers and protective immunity persisted for at least 9 months. No systemic adverse effects, and only a mild local inflammatory response, were observed in mice and rabbits vaccinated i.n. with the CCS vaccine formulation. A similar approach may prove efficacious for i.n. vaccination against other pathogens.

Recent advances for the treatment of cocaine abuse: central nervous system immunopharmacotherapy

Cocaine addiction continues to be a major health and societal problem in spite of governmental efforts devoted toward educating the public of the dangers of illicit drug use. A variety of pharmacotherapies and psychosocial programs have been proposed in an effort to provide a method for alleviation of the physical and psychological symptoms of cocaine abuse. Unfortunately, these methods have been met with limited success, illustrating a critical need for new effective approaches for the treatment of cocaine addiction. Recently an alternative cocaine abuse treatment strategy was proposed using intranasal administration of an engineered filamentous bacteriophage displaying cocaine-sequestering antibodies on its surface. These phage particles are an effective vector for CNS penetration and are capable of binding cocaine, thereby blocking its behavioral effects in a rodent model. The convergence of phage display and immunopharmacotherapy has allowed for an investigation of the efficacy of protein-based therapeutics acting within the CNS on the effects of cocaine in animal models and has uncovered a new tool in the battle against cocaine addiction.

The immunogenicity-enhancing effect of emulsion vaccine adjuvants is independent of the dispersion type and antigen release rate--a revisit of the role of the hydrophile-lipophile balance (HLB) value

Effective antigen delivery is one of the most important issues in vaccine development. It has been suggested that adjuvant action results from a depot effect by prolonging the duration of the interaction between antigen and cells, and thus is related to the antigen-releasing properties of emulsion adjuvants. The objective of this study was to investigate the effect of the dispersion properties of emulsion-type vaccine adjuvants on the immune response with the aim of optimizing vaccine adjuvant formulation. Emulsion-type adjuvants with various dispersion properties of either the oil-in-water or water-in-oil type were prepared using emulsifiers with various hydrophilic-hydrophobic balance (HLB) values. The physicochemical properties of the emulsions, including the conductivity and viscosity, and antigen release rates were then determined. Cell death induced by the vaccine adjuvants was examined in EL4 cells by Annexin V/propidium iodide (PI) staining and flow cytometric analysis. Mice were immunized with or without the adjuvants and the immunogenicity-enhancing effect of the adjuvants determined by measuring antibody production using an enzyme linked immunosorbent assay. The conductivity, viscosity, and antigen release rates varied widely among emulsions containing emulsifiers with different HLB values. However, the magnitude of the antigen-specific antibody response was similar in most emulsions adjuvants containing Spans or Tweens. L121-adjuvant, the control adjuvant inducing the strongest apoptosis in vitro, was shown to stimulate the highest antibody response in vivo. The results obtained in this study indicate that the immunogenicity-enhancing effect of emulsion adjuvants is independent of the dispersion type and the antigen release rate of the vaccine delivery system.

A novel insulin formulation can keep providing steady levels of insulin for much longer periods in-vivo

We have recently succeeded in preparing insulin-loaded microcapsules that release the insulin in a strictly controlled manner with little initial rapid release in-vitro or in-vivo. We show here the superiority of the best formulation prepared with co-poly(D,L-lactic/glycolic) acids (PLGA) (mean MW 5800, L/G ratio 50:50) with a main diameter of 15 approximately 30 microm in-vivo. When 3.2 % insulin-loaded PLGA microcapsules were subcutaneously given as a single dose to streptozotocin-induced hyperglycaemic rats (250 U kg(-1)), plasma insulin levels gradually increased and constant levels (30.3-94.1 microU mL(-1)) were sustained. Rats receiving the formulation once a week showed not only steady plasma insulin levels, but also gained weight at a similar speed to normal rats. Meanwhile, daily treatment with Humulin U (25 U kg(-1)) caused a transient high insulin level (2723.9 microU mL(-1) at 1 h) in plasma, but the body weight of the rats was little changed. A pharmacological study in female Cynomolgus monkeys also revealed that the microcapsular formulation provided a flat release of insulin for longer periods and showed no immunogenic activity. In the near future, therefore, this insulin formulation could become very beneficial as a provider of basal insulin levels for insulin-dependent diabetic patients.

Can nonliving nasal vaccines be made to work?

Nasal vaccines consisting of nonliving particulate formulations can induce immune responses of importance for protection against infection. The most promising results have been obtained with vaccines against influenza, pertussis and group B meningococcal disease. So far, however, the results do not challenge the standing of corresponding injectable vaccines, although results of experiments in animals do indicate that effective nonliving nasal vaccines may soon be developed. This will depend on refined immunization schedules to benefit from immunological memory and on formulations to make the vaccines more accessible to the immune system by way of mucosal adjuvants or immune modulators.