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Host Defense and Parasite Evasion
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Tsetse flies such as Glossina morsitans that serve as vectors of African trypanosomes harbor a number of different specialized obligatory bacterial symbionts, some that can play a protective role. One such symbiont, Wigglesworthia glossinidia (Figure 4.11), provides vitamins that are otherwise not available in the exclusively blood-derived diet of tsetse flies. In addition, if flies are denied access to W. glossinidia during their larval development, they will be both sterile and immunocompromised. They are vulnerable to infections with Escherichia coli and exhibit reduced expression of genes that encode antimicrobial peptides (cecropin and attacin), other hemocyte-derived proteins (thioester-containing proteins 2 and 4 and prophenoloxidase) and signal-mediating molecules. Furthermore, they have reduced hemocyte populations, and they become more susceptible to trypanosome infections. This evidence indicates that W. glossinidia must be present if the tsetse immune system is to develop properly. Studies of the human microbiome (the collection of microorganisms that normally reside in or on the body) reveal a similar trend: full immune maturation depends on the presence and stimulation provided by human microbial symbionts.
Designed Antimicrobial Peptides: A New Horizon
Published in Heather A.E. Benson, Michael S. Roberts, Vânia Rodrigues Leite-Silva, Kenneth A. Walters, Cosmetic Formulation, 2019
Kathryn W. Woodburn, Chia-Ming Chiang, Jesse Jaynes, L. Edward Clemens
To aid in development of an effective topical microbicide against Trichomonas vaginalis, a cecropin peptide, D2A21, was formulated in a hydrophilic gel containing 0.5% or 2% D2A21. A 0.5% or 2% w/v D2A21 peptide solution was prepared in normal saline and 3.25% w/v hydroxyethylcellulose polymer (Lushbaugh et al., 2000). The gel was stored at 2–8°C until used. Estrogenized mice pre-treated with L. rhamnosus were pre-medicated with intravaginal placebo gel, 0.5% or 2% D2A21 gel, prior to T. vaginalis challenge. It was found that 2% D2A21 gel was more efficacious (10% infected) than placebo gel (53% infected) in preventing vaginal T. vaginalis infections in mice. The 0.5% D2A21 gel was not significantly different from placebo in preventing T. vaginalis infection.
Host Defense and Parasite Evasion
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2015
Eric S. Loker, Bruce V. Hofkin
Another example of a collaborative, mutualistic arrangement to achieve infection of an invertebrate host is provided by entomopathogenic nema-todes such as Steinernema and Heterorhabditis (see also Box 7.2). Infective Steinernema larvae actively search for, find, and infect insect hosts. Once in the insect, they release from special areas of their intestine mutualistic bacteria (Xenorhabdus) that then proliferate rapidly in the host insect’s hemocoel, producing a number of factors that damage the host’s hemocytes. The bacteria also inhibit expression of host-produced antimicrobial peptides, such as cecropin, and inhibit prophenoloxidase and thus melanization. Furthermore, the bacteria produce antimicrobial factors that prevent the growth of opportunistic bacteria and release enzymes that degrade molecules produced by the host insect, providing a nutrient soup that favors growth of their associated nematodes. Consequently, both Xenorhabdus and Steinernema proliferate in the host, which is soon killed. Eventually thousands of larval nematodes leave the host insect, each carrying an inoculum of these specialized bacteria to facilitate infection of a hapless new host. Because of their efficiency in killing insects, entomopathogenic nematodes have been used widely as biological control agents.
Antimicrobial peptides: a promising strategy for lung cancer drug discovery?
Published in Expert Opinion on Drug Discovery, 2020
Farshid Zandsalimi, Sam Talaei, Mehdi Noormohammad Ahari, Shahin Aghamiri, Pourya Raee, Soheil Roshanzamiri, Fatemeh Yarian, Mojgan Bandehpour, Zeinab Zohrab Zadeh
The antitumor activity of host AMPs has been established by several studies, but because of poor cytotoxic activity, they cannot be directly used as antitumor agents. The anticancer efficacy of candidate ACPs can be improved depending on their mechanism. For instance, cyclotides exert their killing activity by targeting phosphatidylethanolamine phospholipids. Thus, novel analogs could be developed to enhance the membrane-binding specificities and selectivity to tumor cells by altering their amino acid compositions. Tian et al. [106] revealed that mutagenesis on particular AMPs can be useful for the induction of anticancer features. They substituted Glu16 of cathelicidin-BF (BF-30) with a Lys residue. The resulting peptide (Cbf-K16) exhibited a selective inhibitory effect on the proliferation of H460 human non-small cell lung cancer cells. The team postulated that Cbf-K16 made membrane rupture. The positive charge of Cbf-K16 also facilitates the binding of this antimicrobial peptide to genomic DNA and blocking gene expression. In another study, Huang et al. [107] used an engineered form of cecropin B (CB1a) on lung cancerous cells, in vivo and in vitro model. Their observations indicated that CB1a can disrupt adherence of tumor cells and significantly reduce their viability by inducing cell surface damages. Along with high toxicity to cancer cells, CB1a had less effect on the healthy cell when compared to docetaxel as a conventional drug in lung cancer therapy.
Metal Nanoparticles in Infection and Immunity
Published in Immunological Investigations, 2020
Antimicrobial peptides have been discovered in a wide variety of animals, such as the magainins in frog skin (Zasloff 1987), and cecropins in the hemolymph of moths (Moore et al. 1996). Closely related peptides with antimicrobial effects have subsequently found in many organisms, including horseshoe crabs, other insects, and mammals. For example, cecropin P1 is expressed in Paneth cells in intestinal crypts of the human intestine (Boman et al. 1993; Lee et al. 1989). Antimicrobial peptides are also synthesized by bacteria, such as Polymyxin B, and its derivative colistin, produced by Bacillus polymyxus. In a similar manner to their interactions with nitric oxide, metals can potentiate the antimicrobial effect of cationic peptides, as shown in Figure 2b,c. These effects can often be observed with metal salts as well as with metal nanoparticles. Figure 2b shows a cecropia moth, a large North American moth with vivid eye spots on the wings, and from which the antimicrobial peptide cecropin was first isolated.
Strategies for recombinant production of antimicrobial peptides with pharmacological potential
Published in Expert Review of Clinical Pharmacology, 2020
Kamila Botelho Sampaio de Oliveira, Michel Lopes Leite, Gisele Regina Rodrigues, Harry Morales Duque, Rosiane Andrade da Costa, Victor Albuquerque Cunha, Lorena Sousa de Loiola Costa, Nicolau Brito da Cunha, Octavio Luiz Franco, Simoni Campos Dias
In addition to self-cleavage, AMPs can also be removed from fusion protein by using specific reagents such as cyanogen bromide (CNBr) or formic acid [30,241]. CNBr cleavage is a strategy that allows the peptide to be released from fusion protein by cutting the C-terminal of methionine residues [323]. Some AMPs, such as magainin2 [206] or ecAMP1 [324] and others, have this amino acid residue as part of their structural component (see AMPs database [325]). Recombinant cecropin A, for instance, decreased its antimicrobial activity when compared with its natural counterpart because of an alteration at the C-terminal before cleavage with CNBr [326]. Otherwise, the formic acid cut between (D↓P) amino acids, leading to the release of peptides at low costs [327]. Cecropin CM-4 [282] or lactoferricin/AMP-HP [328] were recovered using formic acid. However, this cleavage system adds an amino acid to any extremity of AMPs treated.