Roles of Antioxidants in Immunity
The immune system is the name given to the sum of the processes that protect the whole organism against diseases, recognize and destroy pathogens and tumor cells. The immune system scans every foreign substance that enters or comes into contact with the body and distinguishes it from the healthy body cells and tissues of the living body and provides defense against harmful substances. The immune system should also detect and respond to abnormal cells and molecules that occur at certain intervals in the body and prevent the development of diseases (Calder 2013). The immune system is very delicate to the balance of oxidants and antioxidants, and a small change in this balance can cause undesirable results. Many of the immune cell functions are dependent on ROS, and ROS increase cytotoxic activity in phagocytes and exhibit microbicidal action, so it is important for immunity. Also, they provide, for example, control of signal transmission of gene expression, the integrity and function of membrane lipids, cellular proteins, and nucleic acids in immune system cells. Without sufficient amounts of antioxidants, ROS produced by phagocytic immune cells can be harmful to the cells themselves and cause oxidative stress. Compared to other somatic cells, there are higher amounts of antioxidants in the immune system and antioxidants have an important place in the continuation of the immune system (Amir Aslani and Ghobadi 2016).
Therapeutic Use of Bioactive Peptide Properties
Food-borne bioactive peptides have health benefits. They are successfully used in the treatment of many diseases. Bioactive peptides are more bioavailable and less allergic than other peptides. Peptides have multiple benefits on biological functions such as blood pressure, metabolic risk factors (coagulation, obesity, lipoprotein metabolism, peroxidation), immunity, hypertension, cardiovascular disease, inflammation, intestinal and neurological functions, diabetes, microbial infections, dental health, and mineral metabolism (Bougie and Bouhallab 2015; Priya 2019). The use of bioactive peptides using nanoparticle and microparticle systems can increase the advantages of bioactive peptides and achieve therapeutic effects (McClements 2018). As a therapeutic agent, bioactive proteins have many uses. Lately, there has been an expansion in the utilization of natural products, such as plants for enormous scope in the production of significant proteins, including, vaccines, antibodies, industrial proteins, and different pharmaceuticals (Daniell et al. 2009; Marauyama et al. 2014). The use of plants offers numerous points of advantages compared to mammalian culture cells due to their low prices and safety. In addition, past examinations have exhibited the potential ability of plants to create complex proteins, for example, secretory antibodies, comprising of four distinctive polypeptide chains that are covalently connected by disulfide bonds (Orzaez, Granell, and Blazquez 2009; Marauyama et al. 2014). This increases the availability of the proteins obtained from these creatures as vaccine production and gives us ideas about producing vaccines against diseases. The peptides produced from the natural compounds described in this chapter have high antioxidant properties and the use of these antioxidant peptides will provide many benefits. In addition, these bioactive peptides do not only have antioxidant roles, they have many benefits, and it is believed that these bioactive peptide sequences may be used in the vaccine production and steps described in other chapters of this book.
Can Bioactive Peptides Be Used as Vaccine Agents?
Peptide vaccines, which are also mentioned in other chapters of this book, are known to have great advantages. These vaccines are generally shown in many preclinical and clinical studies, with low cost, easy stability, relative safety, and easy synthesis. In addition, these peptide vaccines can be used in almost all diseases ranging from many virus infections to Alzheimer’s disease and even allergies (Yang and Kim 2015). It is a matter of curiosity whether antioxidant natural peptides can be used in vaccine structure in addition to the vaccines created with synthetic peptides; studies on this subject argue that successful results can be obtained. First of all, the peptides that will be used to deal with conditions such as nanoparticle production in vaccine studies using peptides must have certain properties. In this respect, the choice of peptides with antioxidant properties can change the effectiveness of the molecule to be produced (Spicer et al. 2018). For example, in a study with GV1001 16-amino-acid peptide, the antioxidant properties of the peptide draw attention (Park et al. 2016). In addition, there are opinions that oral vaccines exist in the studies and that these vaccines obtained with plants can be both cheap and healthy. In particular, studies with amyloid peptide and studies in Alzheimer’s disease are indicative of this condition (Yoshida et al. 2011; Yoshida et al. 2019). It can be said that plant-induced antigens used in the production of oral vaccines have fewer side effects than vaccines administered by injection. In addition to the immunological safety benefit, plant- derived vaccines are thought to be safer and cheaper than those produced from animal cells or microbes. In addition, a vaccine produced from animal cells or microbes requires improvement during the manufacturing process because animal cells may contain viruses, microbes, endotoxins, and prions that can infect humans. However, plant-based vaccines can be administered directly to humans, and therefore a plant- borne vaccine can be produced relatively cheaply. This study highlights the oral vaccines but suggests that plant-based vaccines can be advantageous (Yoshida et al. 2019). In addition, it is thought that nanoparticle vaccines with plant protein can be used for viruses and can be a good protector (Santoni, Zampieri, and Avesani 2020). The use of VP6-ferritin nanoparticle vaccine obtained from milk protein in rotavirus is thought to induce mucosal and humoral immunogenicity and may reduce the side effects of this disease in infants, and is a promising candidate for this disease (Li et al. 2019). In another study, it is thought that an extremely potent seafood antimicrobial peptide epinecidin-1 with anticancer and immunomodulatory activities is promising for treatment (Neshani et al. 2019).
It raises the question that peptides with antioxidant properties can be obtained naturally and may be more safe and effective for humans. However, there are not many studies in this area, so experimental studies are required to test its accuracy. In the study, oral vaccination was made using plants and its advantages were explained.