Antimicrobial peptides in animals and their role in host defences (original) (raw)

Antimicrobial Peptides in Farm Animals: An Updated Review on Its Diversity, Function, Modes of Action and Therapeutic Prospects

Veterinary Sciences

Antimicrobial peptides (AMPs) are the arsenals of the innate host defense system, exhibiting evolutionarily conserved characteristics that are present in practically all forms of life. Recent years have witnessed the emergence of antibiotic-resistant bacteria compounded with a slow discovery rate for new antibiotics that have necessitated scientific efforts to search for alternatives to antibiotics. Research on the identification of AMPs has generated very encouraging evidence that they curb infectious pathologies and are also useful as novel biologics to function as immunotherapeutic agents. Being innate, they exhibit the least cytotoxicity to the host and exerts a wide spectrum of biological activity including low resistance among microbes and increased wound healing actions. Notably, in veterinary science, the constant practice of massive doses of antibiotics with inappropriate withdrawal programs led to a high risk of livestock-associated antimicrobial resistance. Therefore, the...

Antimicrobial Peptides in Farm animals: An updated review on its diversity, function, mode of action and therapeutic prospects

2020

Antimicrobial peptides (AMPs) are the arsenals of the innate host defense system exhibiting the ancient evolutionarily conserved characteristics that is present in practically all forms of life. Recent years have witnessed emergence of antibiotic resistant bacteria compounded with a slow discovery rate for new antibiotics that has necessitated scientific efforts to search for alternatives to antibiotics. Research on the identification of AMPs has generated very encouraging evidences that they curb infectious pathologies and are also useful as novel biologics to function as immunotherapeutic agents. Being innate, they exhibit least toxicity to the host and exert wide spectrum of biological activity including low resistance among microbes, and increased wound healing actions. Notably, in veterinary science, the constant practice of massive doses of antibiotics with inappropriate withdrawal programs led to the high risk of livestock-associated antimicrobial resistance. Therefore, the world faces tremendous pressure for designing and devising strategies to mitigate the use of antibiotics in animals and keep it safe for the posterity. In this review, we illustrate the diversity of farm animals specific AMPs, their biochemical foundations, mode of action and prospective application in clinics. Subsequently, we present the data for their systematic classification by the major and minor groups, antipathogenic action, and allied bioactivities in the host. Finally, we address the limitations to their clinical implementation and envision areas for further advancement.

Animal antimicrobial peptides: An overview

Biopolymers, 1998

Antibiotic peptides are a key component of the innate immune systems of most multicellular organisms. Despite broad divergences in sequence and taxonomy, most antibiotic peptides share a common mechanism of action, i.e., membrane permeabilization of the pathogen. This review provides a general introduction to the subject, with emphasis on aspects such as structural types, post-translational modifications, mode of action or mechanisms of resistance. Some of these questions are treated in depth in other reviews in this issue. The review also discusses the role of antimicrobial peptides in nature, including several pathological conditions, as well as recent accounts of their application at the preclinical level.

Peptides and proteins with antimicrobial activity

Indian Journal of Pharmacology, 2008

The increase of microbial resistance to antibiotics has led to a continuing search for newer and more effective drugs. Antimicrobial peptides are generally found in animals, plants, and microorganisms and are of great interest to medicine, pharmacology, and the food industry. These peptides are capable of inhibiting pathogenic microorganisms. They can attack parasites, while causing little or no harm to the host cells. The defensins are peptides found in granules in the polymorphonuclear neutrophils (PMNs) and are responsible for the defense of the organism. Several animal defensins, like dermaseptin, antileukoprotease, protegrin, and others, have had their activities and efficacy tested and been shown to be effective against bacteria, fungi, and protists; there are also specific defensins from invertebrates, e.g., drosomycin and heliomicin; from plants, e.g., the types A and B; and the bacteriocins, e.g., acrocin, marcescin, etc. The aim of the present work was to compile a comprehensive bibliographic review of the diverse potentially antimicrobial peptides in an effort to systematize the current knowledge on these substances as a contribution for further researches. The currently available bibliography does not give a holistic approach on this subject. The present work intends to show that the mechanism of defense represented by defensins is promising from the perspective of its application in the treatment of infectious diseases in human, animals and plants.

Cathelicidins: family of antimicrobial peptides. A review

Molecular Biology Reports, 2012

Cathelicidins are small, cationic, antimicrobial peptides found in humans and other species, including farm animals (cattle, horses, pigs, sheep, goats, chickens, rabbits and in some species of fish). These proteolytically activated peptides are part of the innate immune system of many vertebrates. These peptides show a broad spectrum of antimicrobial activity against bacteria, enveloped viruses and fungi. Apart from exerting direct antimicrobial effects, cathelicidins can also trigger specific defense responses in the host. Their roles in various pathophysiological conditions have been studied in mice and humans, but there are limited information about their expression sites and activities in livestock. The aim of the present review is to summarize current information about these antimicrobial peptides in farm animals, highlighting peptide expression sites, activities, and future applications for human and veterinary medicine.

Antimicrobial peptides of buffalo and their role in host defenses

Antimicrobial peptides (AMPs) are highly conserved components of the innate immune system found among all classes of life. Buffalo (Bubalus bubalis), an important livestock for milk and meat production, is known to have a better resistance to many diseases as compared to cattle. They are found to express many AMPs such as defensins, cathelicidins, and hepcidin which play an important role in neutralizing the invading pathogens. Buffalo AMPs exhibit broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria. Similar to its natural form, synthetic analogs of buffalo AMPs are also antimicrobial against bacteria and even fungus making them a good target for the development of therapeutic antimicrobials. In addition to its antimicrobial effect, AMPs have been demonstrated to have a number of immunomodulatory functions, and their genes are responsive to infections. Further, induction of their gene expression by external factors may help in preventing infectious diseases. This review briefly discusses the AMPs of buffalo identified to date and their possible role in innate immunity.

β-Defensin Antibiotic Peptides in the Innate Immunity of the Buffalo: In Vivo and In Vitro Studies

Alternatives to Laboratory Animals

β-Defensin antimicrobial peptides are multifunctional biomolecules, which are a major component of the oxygen-independent microbicidal system of buffalo polymorphonuclear (PMN) cells. They have great potential for use as proteomic biomarkers of host cell responses in the presence of microbial agents. On purifying these peptides by RP-HPLC, four defensin peptides were revealed. The results from testing against Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes, Candida albicans, Rinderpest Virus (RPV) and Newcastle Disease Virus (NDV), showed that the peptides possessed antimicrobial and antiviral activities. Minimum inhibitory concentration (MIC) values varied according to the peptide amounts and the exposure time. Furthermore, an increase in the levels of these cationic antimicrobial peptides was apparent in milk obtained from natural cases of mastitis, as compared to the levels in normal milk. MALDI-TOF-based amino acid sequencing confirmed the expression of two β-defensins (LAP and BNBD-2) in mastitis milk. A comparison of peptide sequences revealed that buffalo LAP and BNBD-2 share 98.6% and 100% sequence identity, respectively, with those of cattle. In vitro, Bovine Viral Diarrhoea Virus (BVDV) infection was shown to induce the expression of the β-defensin gene, as evidenced by the PCR amplification of cDNA with specific primers. The determination of the enhanced expression of β-defensin peptides in mastitis milk and in PMN cells, can be considered as an advanced approach to the assessment of cellular and molecular responses to cell injury. It is hoped that in vitro studies on phagocytes such as PMN cells and other cell lines, will eventually replace the use of animals in elucidating the roles of these cytokines in response to microbe-derived cell damage. It will also be possible to use defensins as biomarkers to correlate failure in host cell defence systems with peptide heterogeneity.

Potential Role of Synthetic Antimicrobial Peptides in Animal Health to Combat Growing Concerns of Antibiotic Resistance - A Review.

Antibiotic resistance and particularly multidrug resistant (MDR) pathogens are of increasing concern. WHO (World Health Organization) wrote in April, 2014 that “this serious threat is no longer a prediction for the future, it is happening right now in every region of the world and has the potential to affect everyone, of any age, in any country.” Antimicrobial peptides (AMPs) are a class of naturally occurring compounds found in plants and animals and have been isolated from living organisms ranging from single-celled microorganisms, to plants, to livestock species, and to humans. Over 1200 such naturally occurring AMP compounds have been isolated and identified. These compounds are found and produced by many different tissues, and generally form part of the first line of defenses in organism immune systems. Additional research indicates that AMPs are also involved with promoting wound repair, the reduction of inflammations, possibly through the release of prostaglandins, and some are part of the neutrophils and their defense mechanisms against pathogens. The phagocytic action by neutrophils in fighting infectious agents is a series of biological events which includes AMPs as a cofactor in fighting infections and in wound repair, with multiple types of AMPs involved. Early attempts at synthesizing AMPs were unsuccessful due to the expense and the relatively short half-life of the generated AMPs. Recently, synthetic AMPs of a more simplistic nature have been produced using several different positively charged amino acid side chains in their formulations, each amino acid attached to a cholic acid backbone that are inexpensive to manufacture, stable, and better tolerated by the organism. These synthetic AMPs show a range of activities and specificities for bacteria, viruses, fungi and parasites and the many derivations of these synthetic AMPs are referred to as Ceragenins or cationic selective antimicrobials (CSAs).