Plant Phenolics and Lectins as Vaccine Adjuvants

Abstract

Background: The immune system is responsible for providing protection to the body against foreign substances. The immune system divides into two types of immune responses to study its mechanisms of protection: 1) Innate and 2) Adaptive. The innate immune response represents the first protective barrier of the organism that also works as a regulator of the adaptive immune response, if evaded the mechanisms of the innate immune response by the foreign substance the adaptive immune response takes action with the consequent antigen neutralization or elimination. The adaptive immune response objective is developing a specific humoral response that consists in the production of soluble proteins known as antibodies capable of specifically recognizing the foreign agent; such protective mechanism is induced artificially through an immunization or vaccination. Unfortunately, the immunogenicity of the antigens is an intrinsic characteristic of the same antigen dependent on several factors. Conclusion: Vaccine adjuvants are chemical substances of very varied structure that seek to improve the immunogenicity of antigens. The main four types of adjuvants under investigation are the following: 1) Oil emulsions with an antigen in solution, 2) Pattern recognition receptors activating molecules, 3) Inflammatory stimulatory molecules or activators of the inflammasome complex, and 4) Cytokines. However, this paper addresses the biological plausibility of two phytochemical compounds as vaccine adjuvants: 5) Lectins, and 6) Plant phenolics whose characteristics, mechanisms of action and disadvantages are addressed. Finally, the immunological usefulness of these molecules is discussed through immunological data to estimate effects of plant phenolics and lectins as vaccine adjuvants, and current studies that have implanted these molecules as vaccine adjuvants, demonstrating the results of this immunization.

Plant Phenolics as Pathogen-Carrier Immunogenicity Modulator Haptens

“…Therefore, it is possible for the adaptive immune response to develop a specific humoral response. This consists of the production of soluble proteins (antibodies) capable of specifically recognizing the foreign agent with the consequent neutralization or elimination thereof [ 2 ]. Even though, these antibodies when produced in high quantities might lead to pathogenesis such as hypersensitivity.…”

“…Plant metabolites classify in two types: 1) Primary metabolites: As carbohydrates, lipids, proteins and nucleic acids, essential molecules for the proper cellular function; and, 2) Secondary metabolites: All those compounds that are dispensable for the proper cellular function; however, these secondary metabolites provide advantages for survival in the environment. For example, they may have insecticidal properties against pests or attract pollinating insects [ 2 ].…”

“…Another group of compounds classifies as stilbenes because in their structure it is possible to find a similarity to stilbene. And so on as shown in Table 2 [ 2 ].…”

“…The innate immune response represents the first protective barrier of the organism that also functions as a regulator of the adaptive immune response. If the mechanisms of the innate immune response fail, the adaptive immune response takes action whose objectives are to develop a specific humoral response that consists of the production of soluble proteins known as antibodies capable of specifically recognizing the foreign agent with the consequent neutralization or elimination thereof [ 2 ]. An immunization scheme consisting of the programmed administration of a substance called antigen, can induce a protective mechanism with the objective of developing an adaptive immune response against the antigen.…”

“…Furthermore, depending on the type of antigen used, there are advantages and disadvantages such as a risk of pathogenicity, low or high immunogenicity, or a response against epitopes without relevance [ 6 ]. It is therefore necessary to develop specific immunization schemes for different antigens, as well as to consider the simultaneous supply of adjuvants to reinforce or inhibit the immune response against the antigen [ 2 ]. Thus, this paper addresses the biological plausibility of antigen conjugates to inhibit pathogenesis, for instance, pathogen infection or hypersensitivity by means of said conjugates that forms to immunogen or toleragen.…”