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Bioaerosol-Induced Hypersensitivity Diseases
Published in Harriet A. Burge, Bioaerosols, 2020
Cory E. Cookingham, William R. Solomon
Circumstances of antigen exposure: adjuvants. Antigen exposure, whether as aerosol or by other routes, rarely occurs in the absence of other (nonantigenic) agents; among these is a group of substances known as adjuvants. An adjuvant is a substance that encourages and/or augments an immune response. Examples of naturally occurring adjuvants include endotoxin (lipopolysaccha-ride present in cell walls of Gram negative bacteria) (see Chapter 4) and complex substances derived from members of the order Actinomycetales (Mycobacterium, Thermoactinomyces, etc.). As endotoxin is ubiquitous in the environment, all natural exposures to antigen aerosols probably include endotoxin to some degree. The role of endotoxin in the development of specific hypersensitivity diseases, however, has not been extensively explored. The adjuvant activity derived from mycobacteria is commonly used to stimulate immune responses in animal models of disease. In addition, similar materials derived from actinomycetes may modulate the immune responses to vegetable dusts implicated in hypersensitivity pneumonitis (e.g., in farmer’s lung disease).
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Published in Joseph C. Salamone, Polymeric Materials Encyclopedia, 2020
A tyrosine-derived polyiminocarbonate has been considered for “single step” immunization procedures.30 Many vaccines require the use of an adjuvant to reach adequate level of antibodies. Since L-tyrosine is known for its adjuvant properties,31 the use of a degradable tyrosinederived polyiminocarbonate as an antigen delivery device appeared promising.30 A model device, releasing bovine serum albumine (BSA), was tested in mice. Upon degradation of the polyiminocarbonate, the release of BSA in the presence of the tyrosine containing polymer (or its degradation products) resulted in an anti-BSA antibody titer that was comparable to the titer observed when BSA was administered repeatedly in complete Freund’s adjuvant. This system effectively took advantage of the rapid degradation characteristics of tyrosine-derived polyiminocarbonates.
Formulation Development of Prophylactic and Therapeutic Vaccines
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Adjuvants are used in majority of the licensed vaccines to elicit broader and potent immune response against the vaccine antigen(s). The adjuvanted vaccines are presented in one of two specific categories: either the antigen and adjuvants are co-formulated and presented together, or the antigen and adjuvant are presented separately and mixed prior to administration. Future vaccines, which are under clinical development, also fall under these categories. Therefore, assessment of the antigen–adjuvant interaction and their stability becomes crucial. Pre-formulation development studies and extensive characterization of the antigen during the early phases of development outline the buffer and excipient condition in which the antigen is compatible to be formulated with the chosen adjuvant, either in a co-formulated state or in isolation (for “bedside” mixing in clinic). Under situations where the vaccine antigen and adjuvant are co-formulated, apart from characterizing the vaccine antigen(s) and adjuvants separately and understanding the key quality attributes responsible for vaccine stability and potency, analysis of antigen–adjuvant interactions in the co-formulated drug product is important for both vaccine safety and efficacy and overall stability. Since the immunogenicity of the vaccine antigen depends on doses of both the vaccine antigen and the adjuvant, their characterization as a formulated drug product is key.
A novel method to prepare lipid vesicles as carrier of hydrophilic bioactive substances
Published in Journal of Dispersion Science and Technology, 2020
In 1965, Bangham and his colleagues first discovered that phospholipids could spontaneously form a multi-layered vesicle in water and they are known as liposomes.[1] Liposomes are microspheres of a similar bio-film consisting of lipid-like, and are a closed vesicle structure formed by self-assembly of amphiphilic molecules in water. They have been used to transport bioactive substances through the blood stream or through the skin, leading to the widespread use of liposomes in drug delivery and cosmetics.[2–5] Liposomes also can be used as carrier to encapsulate a variety of vaccines and introduce them effectively into cells. They have many advantages as vaccine adjuvants, including prolonging the residence time of the antigen in the body, reducing the side effects, enhancing the immune effect and so on.[6–7] Liposomes have been used as intelligent drug carriers such as temperature-controlled release of drugs,[8] photochemical response release,[9] magnetic response release[10] and so on. In the field of nanocarriers, many researchers have shown great interest in vesicles with similar structures to liposomes, such as quatsomes,[11] niosomes,[12] and so on.[13–15]
Preparation and characterization of polyoxyethylene dehydrated mannitol mono oleate as hydrophilic emulsifier potentially used in w/o/w type adjuvants
Published in Journal of Dispersion Science and Technology, 2021
Mengmeng Zhou, Yantao Li, Xiaoqi Chen, Haijun Zhou, Shulan Yang, Xiongwei Qu
The control of livestock infectious diseases is largely dependent on the use and application of efficient vaccines. Adjuvants are particularly important as they improve vaccine immunogenicity and efficacy. For this reason, many researchers focus on the study of adjuvants in order to promote vaccine immunogenicity.[32] W/o/w emulsions have several potential applications: their use as drug delivery systems appears to be the most promising. In this study, a w/o/w type adjuvant was successfully prepared using PDMMO as a hydrophilic emulsifier. The structure of the hydrophilic emulsifier was confirmed by FT-IR and 1H-NMR spectra. The ideal amount of emulsifier and its stability for w/o/w emulsions were also investigated. PDMMO is a nonionic surfactant and is combined with ethylene oxide as its hydrophilic group. The hydrophilic group is composed of an ether bond and hydroxyl group, but the hydrophilicity is limited because there is only one -OH near the end of the molecule. Hydrophilicity increases with the number of ethylene oxides added. Thus, the stability performance of a w/o/w emulsion varies with changes in the number of ethylene oxides (n) on the molecules of PDMMO. Based on stability testing, the PDMMO that contained 9.0 ethylene oxides was chosen as the hydrophilic emulsifier. Several parameters, including conductivity, viscosity, particle size and distribution, optical microscopic imaging and immunogenicity in vivo, were tested. Electrical conductivity and optical microscopy confirmed that the structure of the emulsions was w/o/w type. Particle size and distribution are important parameters that influence vaccine stability. PDMMO and MMO (at a mass ratio of 4.5 to 1) were used as hydrophilic emulsifiers and lipophilic emulsifiers, respectively. Both are nonionic emulsifiers and exhibit abilities of reducing interfacial tension and improving emulsion stability. The primary emulsification mechanism is that surfactants form interfacial films with large interfacial viscosities and specific thicknesses on the interface between the dispersed phase and medium, which ensures that the droplets of the two dispersed phases cannot be in direct contact.