Candidacidal activities of human lactoferrin peptides derived from the N terminus

Functionalization of Alginate Hydrogels with a Multifunctional Peptide Supports Mesenchymal Stem Cell Adhesion and Reduces Bacterial Colonization

Hydrogels with cell adhesive moieties stand out as promising materials to enhance tissue healing and regeneration. Nonetheless, bacterial infections of the implants represent an unmet major concern. In the present work, we developed an alginate hydrogel modified with a multifunctional peptide containing the RGD cell adhesive motif in combination with an antibacterial peptide derived from the 1-11 region of lactoferrin (LF). The RGD-LF branched peptide was successfully anchored to the alginate backbone by carbodiimide chemistry, as demonstrated by 1H NMR and fluorescence measurements. The functionalized hydrogel presented desirable physicochemical properties (porosity, swelling and rheological behavior) to develop biomaterials for tissue engineering. The viability of mesenchymal stem cells (MSCs) on the peptide-functionalized hydrogels was excellent, with values higher than 85 % at day 1, and higher than 95 % after 14 days in culture. Moreover, the biological characterization demonstrated the ability of the hydrogels to significantly enhance ALP activity of MSCs as well as to decrease bacterial colonization of both Gram-positive and Gram-negative models. Such results prove the potential of the functionalized hydrogels as novel biomaterials for tissue engineering, simultaneously displaying cell adhesive activity and the capacity to prevent bacterial contamination, a dual bioactivity commonly not found for these types of hydrogels.

Lactoferrin as a potential therapeutic for the treatment of Candida-associated denture stomatitis

BACKGROUND

The use of prostheses in the oral cavity creates favorable conditions for Candida colonization, which may subsequently lead to Candida-associated denture stomatitis (CADS). Due to its many contributing factors and frequent relapses, CADS is difficult to manage. Given the rise in drug resistance among fungal species, it is critical to develop new therapeutic approaches, reduce the required dosage of medications, and minimize the toxicity and side effects of therapy.

HIGHLIGHT

Salivary lactoferrin, a multifunctional glycoprotein, is thought to be the first line of defense against microbial invasion of mucosal surfaces.

CONCLUSION

Current research emphasizes the capability of lactoferrin and its derivatives to eliminate a broad spectrum of Candida species. It may be an appealing option for use in monotherapy or in combination with common medications for oral stomatitis treatment. This review provides an overview of the current understanding of lactoferrin's anti-fungal effects in oral candidiasis.

Vaginal microbiota: Potential targets for vulvovaginal candidiasis infection

Vulvovaginal candidiasis (VVC) is the second most common cause of vaginal infection globally after bacterial vaginosis (BV) and associated with adverse reproductive and obstetric outcomes, including preterm delivery, sexually transmitted infections and pelvic inflammatory disease. Although effective control of VVC is achievable with the use of traditional treatment strategies (i.e., antifungals), the possibility of drug intolerance, treatment failure and recurrence, as well as the appearance of antifungal-resistant Candida species remain critical challenges. Therefore, alternative therapeutic strategies against VVC are urgently required. In recent years, an improved understanding of the dysbiotic vaginal microbiota (VMB) during VVC has prompted the consideration of administering -biotics to restore the balance of the VMB within the context of VVC prevention and treatment. Here, we aim to summarize the current evidence of the anti-Candida effects of probiotics, postbiotics and synbiotics and their potential use as an alternative/complementary therapy against VVC. Additionally, this review discusses advantages and challenges associated with the application of -biotics in VVC to provide guidance for their later use. We also review new developments in VVC therapy, i.e., vaginal microbiota transplantation (VMT) as an emerging live biotherapeutic therapy against VVC and discuss existing shortcomings associated with this nascent field, expecting to stimulate further investigations for introduction of new therapies against VVC.

Screening sensibility and antifungal activity after topical application of a synthetic lactoferrin-derived antimicrobial peptide

OBJECTIVE

Onychomycosis is the most common disease of the nails and constitutes about half of all nail abnormalities. Onychomycosis is usually caused by dermatophytes and incomparably less frequently by yeast-like fungi and non-dermatophyte molds. Current treatment options for onychomycosis are ineffective.

METHODS

This study evaluated the performance of a commercial and CE-registered product containing antimicrobial peptide hLF1-11 in vitro for treating toenail onychomycosis. In a case-control setting, nail samples from 59 volunteers were obtained before and after treatment by a pedicurist and investigated for the presence of fungi by culturing, barcode sequencing, and MALDI-TOF-MS.

RESULTS

Of 89 samples, T. rubrum (19%) and C. parapsilosis (17%) were cultured. In total, 47 samples (53%) were positive for culture. MALDI-TOF-MS could identify 28, but 19 remained unidentified; those species were not included in the commercial MALDI-TOF reference database library. A positive effect of treatment by the hLF1-11 product on 41 volunteers (1 placebo, 18 low doses, 22 high doses) was observed. No adverse effects of the peptide were observed or reported by the pedicurist or any of the participants.

CONCLUSIONS

This study showed a positive therapeutic effect of a commercial product containing hLF1-11 in the case of 88.9% of the patients with onychomycosis. The present formulation of hLF1-11 into PBS is stable enough to permit storage at room temperature for at least two years.

Combining the Peptide RWQWRWQWR and an Ethanolic Extract of Bidens pilosa Enhances the Activity against Sensitive and Resistant Candida albicans and C. auris Strains

The antifungal activity of palindromic peptide RWQWRWQWR and its derivatives was evaluated against clinical isolates of Candida albicans and C. auris. Also, Bidens pilosa ethanolic extracts of leaves and stem were evaluated. Furthermore, combinations of peptide, extract, and/or fluconazole (FLC) were evaluated. The cytotoxicity of peptides and extracts in erythrocytes and fibroblasts was determined. The original palindromic peptide, some derivative peptides, and the ethanolic extract of leaves of B. pilosa exhibited the highest activity in some of the strains evaluated. Synergy was obtained between the peptide and the FLC against C. auris 435. The combination of the extract and the original palindromic peptide against C. albicans SC5314, C. auris 435, and C. auris 537 decreased the minimal inhibitory concentrations (MICs) by a factor of between 4 and 16. These mixtures induced changes in cell morphology, such as deformations on the cell surface. The results suggest that the combination of RWQWRWQWR and B. pilosa extract is an alternative for enhancing antifungal activity and decreasing cytotoxicity and costs and should be considered to be a promising strategy for treating diseases caused by Candida spp.

Candida parapsilosis sensu stricto Antifungal Resistance Mechanisms and Associated Epidemiology

Fungal diseases cause millions of deaths per year worldwide. Antifungal resistance has become a matter of great concern in public health. In recent years rates of non-albicans species have risen dramatically. Candida parapsilosis is now reported to be the second most frequent species causing candidemia in several countries in Europe, Latin America, South Africa and Asia. Rates of acquired azole resistance are reaching a worrisome threshold from multiple reports as in vitro susceptibility testing is now starting also to explore tolerance and heteroresistance to antifungal compounds. With this review, the authors seek to evaluate known antifungal resistance mechanisms and their worldwide distribution in Candida species infections with a specific focus on C. parapsilosis.

Sensitization of KPC and NDM Klebsiella pneumoniae To Rifampicin by the Human Lactoferrin-Derived Peptide hLF1-11

A synergistic effect of non-bactericidal concentrations of the human lactoferrin (hLF)-derived peptide hLF1-11 and rifampicin against multidrug-resistant KPC (Klebsiella pneumoniae carbapenemase)-producing K. pneumoniae has been previously shown. The present study focuses on the mechanism(s) underlying this synergistic effect. The contribution of hLF1-11 and rifampicin to the synergistic effect was evaluated by killing assays with KPC K. pneumoniae cells incubated with hLF1-11 and, after washing, with rifampicin, or vice versa. Cell membrane permeability and polarization upon exposure to hLF1-11 and/or rifampicin were evaluated by ethidium bromide (EtBr) and DiBAC₄(3) (bis-1,3-dibutylbarbituric acid trimethine oxonol) permeability, respectively. The effect of carbonyl cyanide m-chlorophenyl hydrazone (CCCP), an uncoupler of oxidative phosphorylation, was also evaluated. KPC K. pneumoniae cells were effectively killed after prior exposure to rifampicin for 30 to 60 min followed by treatment with hLF1-11, while no antibacterial activity was observed when cells were incubated with hLF1-11 first and then with rifampicin. EtBr accumulation increased upon exposure to hLF1-11 or the combination of hLF1-11 and rifampicin, but not upon exposure to rifampicin alone. Moreover, hLF1-11 induced a dose-dependent membrane depolarization. As expected, the antibacterial activity of hLF1-11 alone or combined with rifampicin was significantly reduced in the presence of CCCP. Furthermore, hLF1-11 and rifampicin were synergistic also against a colistin-resistant NDM (New Delhi metallo-β-lactamase)-producing K. pneumoniae strain. The results suggest that rifampicin was accumulated by KPC cells during the 30-to-60-min incubation and that the addition of hLF1-11 sensitized bacterial cells to rifampicin by inducing a transient loss of membrane potential and increased cell membrane permeability, thus facilitating the entrance and retention of rifampicin into the cytoplasm. IMPORTANCE The present study describes a synergistic effect between rifampicin, an impermeable hydrophobic antibiotic with an intracellular target, and an hLF1-11, an antimicrobial peptide derived from human lactoferrin, against multidrug-resistant Klebsiella pneumoniae. Carbapenem-resistant K. pneumoniae has recently caused an outbreak in Tuscany, Italy, thus pressing the need for the development of new treatment options. The mechanisms underlying such a synergistic effect have been studied. The results suggest that the synergistic effect was due to the transient loss of membrane potential induced by hLF1-11 and the subsequent increase in cell membrane permeability which allowed rifampicin to enter the bacterial cell. Therefore, it is likely that a sub-inhibitory concentration of hLF1-11 can efficiently permeabilize K. pneumoniae cells to rifampicin, allowing the antibiotic to reach its intracellular target. These results encourage further exploration of possible applications of this synergistic combination in the treatment of K. pneumoniae infections.

Quantifying the Antifungal Activity of Peptides Against Candida albicans

Traditional methods for performing antifungal susceptibility testing for Candida albicans are time-consuming and lack quantitative results. For example, a common approach relies on plating cells treated with different concentrations of antifungal molecules on agar plates and then counting the colonies to determine the relationship between molecule concentration and growth inhibition. This method requires many plates and substantial time to count the colonies. Another common approach eliminates the plates and counting of colonies by visually inspecting cultures treated with antifungal agents to identify the minimum concentration required to inhibit growth; however, visual inspection produces only qualitative results, and information on growth at subinhibitory concentrations is lost. This protocol describes a method for measuring the susceptibility of C. albicans to antifungal peptides. By relying on optical density measurements of cultures, the method reduces the time and materials needed to obtain quantitative results on culture growth at different peptide concentrations. The incubation of the fungus with peptides is performed in a 96-well plate using an appropriate buffer, with controls representing no growth inhibition and complete growth inhibition. Following the incubation with the peptide, the resulting cell suspensions are diluted to reduce peptide activity and then grown overnight. After overnight growth, the optical density of each well is measured and compared to the positive and negative controls to calculate the resulting growth inhibition at each peptide concentration. The results using this assay are comparable to the results using the traditional method of plating the cultures on agar plates, but this protocol reduces plastic waste and the time spent on counting colonies. Although the applications of this protocol have focused on antifungal peptides, the method will also be applicable to testing other molecules with known or suspected antifungal activity.

Synergistic Activity of the Human Lactoferricin-Derived Peptide hLF1-11 in Combination with Caspofungin against Candida Species

Candida species are the main fungal opportunistic pathogens causing systemic infections that are often associated with drug resistance and biofilm production on medical devices. The pressing need for new antifungal agents led to an increased interest in the use of combination therapies. The present study was aimed at investigating potential synergistic activity of the human lactoferrin-derived hLF1-11 peptide with caspofungin against caspofungin-resistant or -susceptible C. albicans, C. parapsilosis, and C. glabrata strains. Synergism was evaluated by the checkerboard assay, measuring cellular metabolic activity against Candida planktonic and sessile cells. A fractional inhibitory concentration (FIC) index of ≤0.5 was interpreted as synergy. Synergism was evaluated by killing assays on planktonic cells. A cell viability assay was performed with biofilm formation inhibition and preformed biofilm. Synergy for killing and viability assays was defined as a ≥2-log-CFU/mL reduction in comparison with the most active constituent. hLF1-11 and caspofungin exerted (i) synergistic effects against planktonic cells of all the tested strains, yielding drastic caspofungin MIC reduction, (ii) synergistic effects on the inhibition of biofilm formation against biofilm producer strains, yielding caspofungin BIC reduction, and (iii) synergistic effects on preformed biofilm assessed by measuring metabolic activity (FIC range, 0.28 to 0.37) against biofilm-producing strains and by cell viability assay in C. albicans SC5314. The synergistic effect observed between caspofungin and hLF1-11 against Candida spp. is of potential clinical relevance, representing a promising novel approach to target caspofungin-resistant Candida species infections. Further studies elucidating the mechanisms of action of such a synergistic effect are needed. IMPORTANCE The present study describes a synergistic effect between a conventional antifungal drug, caspofungin, and a synthetic peptide derived from human lactoferrin, hLF1-11, against Candida species. These yeasts are able to cause severe systemic fungal infections in immunocompromised hosts. In addition, they can form biofilms in medical implanted devices. Recently, caspofungin-resistant Candida strains have emerged, thus highlighting the need to develop different therapeutic strategies. In in vitro studies, this drug combination is able to restore sensitivity to caspofungin in caspofungin-resistant strains of Candida species, both in free-living cells and in cells organized in biofilms. This synergism could represent a promising novel approach to target infections caused by caspofungin-resistant Candida species.

Disruption of Iron Homeostasis and Mitochondrial Metabolism Are Promising Targets to Inhibit Candida auris

Fungal infections are a global threat, but treatments are limited due to a paucity in antifungal drug targets and the emergence of drug-resistant fungi such as Candida auris. Metabolic adaptations enable microbial growth in nutrient-scarce host niches, and they further control immune responses to pathogens, thereby offering opportunities for therapeutic targeting. Because it is a relatively new pathogen, little is known about the metabolic requirements for C. auris growth and its adaptations to counter host defenses. Here, we establish that triggering metabolic dysfunction is a promising strategy against C. auris. Treatment with pyrvinium pamoate (PP) induced metabolic reprogramming and mitochondrial dysfunction evident in disrupted mitochondrial morphology and reduced tricarboxylic acid (TCA) cycle enzyme activity. PP also induced changes consistent with disrupted iron homeostasis. Nutrient supplementation experiments support the proposition that PP-induced metabolic dysfunction is driven by disrupted iron homeostasis, which compromises carbon and lipid metabolism and mitochondria. PP inhibited C. auris replication in macrophages, which is a relevant host niche for this yeast pathogen. We propose that PP causes a multipronged metabolic hit to C. auris: it restricts the micronutrient iron to potentiate nutritional immunity imposed by immune cells, and it further causes metabolic dysfunction that compromises the utilization of macronutrients, thereby curbing the metabolic plasticity needed for growth in host environments. Our study offers a new avenue for therapeutic development against drug-resistant C. auris, shows how complex metabolic dysfunction can be caused by a single compound triggering antifungal inhibition, and provides insights into the metabolic needs of C. auris in immune cell environments. IMPORTANCE Over the last decade, Candida auris has emerged as a human pathogen around the world causing life-threatening infections with wide-spread antifungal drug resistance, including pandrug resistance in some cases. In this study, we addressed the mechanism of action of the antiparasitic drug pyrvinium pamoate against C. auris and show how metabolism could be inhibited to curb C. auris proliferation. We show that pyrvinium pamoate triggers sweeping metabolic and mitochondrial changes and disrupts iron homeostasis. PP-induced metabolic dysfunction compromises the utilization of both micro- and macronutrients by C. auris and reduces its growth in vitro and in immune phagocytes. Our findings provide insights into the metabolic requirements for C. auris growth and define the mechanisms of action of pyrvinium pamoate against C. auris, demonstrating how this compound works by inhibiting the metabolic flexibility of the pathogen. As such, our study characterizes credible avenues for new antifungal approaches against C. auris.

In vitro activity of the antimicrobial peptides h-Lf1-11, MSI-78, LL-37, fengycin 2B, and magainin-2 against clinically important bacteria

We investigated the antibacterial activity of the antimicrobial peptides h-Lf1-11, MSI-78, LL-37, fengycin 2B, and magainin-2. The minimum inhibitory concentration (MIC) was determined by microdilution technique according to CLSI (M07-A9, 2012) against Escherichia coli, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, carbapenem-resistant Klebsiella pneumoniae, and Acinetobacter baumannii. The MSI-78 showed potent bactericidal activity with MIC range of 1.25-40 mg/L against all bacterial strains. The h-Lf1-11, magainin-2, and LL-37 exhibited moderate activity (MIC range of 40-160, 80-160, and 40-160 mg/L, respectively) while the fengycin 2B did not show significant activity against all bacterial strains tested. These results revealed that MSI-78, h-Lf1-11, magainin-2, and LL-37 have great potential as antibacterial agents and their activity deserves to be more explored in further studies for the treatment of antibiotic-resistant bacteria.

In vitro activity of lactoferricin solution against Malassezia pachydermatis from otitis externa in dogs and cats

BACKGROUND

Malassezia pachydermatis is a commensal organism of the skin, yet it may induce dermatitis and/or otitis. Lactoferricin (Lfcin) is an antimicrobial peptide obtained by the pepsin-mediated digestion of lactoferrin, a multifunctional innate-defence milk protein. The antibacterial activity of Lfcin is thought to cause alteration of bacterial membrane permeability, thus inducing cell death.

OBJECTIVES

The aim of this study was to evaluate in vitro antifungal activity of different dilutions of Lfcin solution against M. pachydermatis strains isolated from ears of dogs and cats with otitis externa.

METHODS AND MATERIALS

Fifty clinical Malassezia isolates from 40 dogs and 10 cats were tested. A dilution method in microtitre plates was used starting with a 20% Lfcin water solution. The different dilutions were 2:1 (13.3%), 1:1 (10%), 1:2 (6.7%), 1:5 (3.3%) and 1:10 (1.8%). Results were expressed as the value at which the growth of 50% (minimal fungicidal concentration MFC₅₀ ) and 90% (MFC₉₀ ) of yeast cells was inhibited.

RESULTS

All strains showed susceptibility to 20% Lfcin solution (100%). With 1:5 and 1:10 dilutions corresponding to 3.3% and 1.8% Lfcin solutions, all strains showed resistance. The MFC₅₀ and MFC₉₀ values were observed at 13.3% and 20% Lfcin solutions.

CONCLUSIONS AND CLINICAL RELEVANCE

The results indicated that Lfcin solution exhibits the antimicrobial activity specific to antimicrobial peptides. In particular, the 20% solution can be effective in killing M. pachydermatis isolated strains. Some susceptibilities also are evident at lower concentrations of ≤6.7% for four strains.

Activity of MSI-78, h-Lf1-11 and cecropin B antimicrobial peptides alone and in combination with voriconazole and amphotericin B against clinical isolates of Fusarium solani

Fusarium infections have been associated with high mortality rates due to the lack of definition of an ideal treatment strategy. Antimicrobial peptides (AMPs) have potential antifungal activity. Therefore, investigating the in vitro activity of these molecules alone and in association with conventional antifungals against clinical isolates of Fusarium was the aim of this study. Fusarium solani (n=10) strains were tested against the AMPs, MSI-78, h-Lf1-11 and cecropin B in accordance with CLSI protocol. Further, a checkerboard assay for its combination with amphotericin B or voriconazole, was carried out. MSI-78, h-Lf1-11 and cecropin B exhibited antifungal activity against F. solani strains tested with MICs ranging from 20 to 320mg/L. Satisfactory percentage of synergism was demonstrated for all evaluated combinations, ranging from 70 to 100%. The use of AMPs combined with amphotericin B and voriconazole antifungals has great synergistic potential and deserve to be evaluated in murine models of fusariosis.

Host Defense Peptides as Templates for Antifungal Drug Development

Current treatment for invasive fungal diseases is limited to three classes of antifungal drugs: azoles, polyenes, and echinocandins. The most recently introduced antifungal class, the echinocandins, was first approved nearly 30 years ago. The limited antifungal drug portfolio is rapidly losing its clinical utility due to the inexorable rise in the incidence of invasive fungal infections and the emergence of multidrug resistant (MDR) fungal pathogens. New antifungal therapeutic agents and novel approaches are desperately needed. Here, we detail attempts to exploit the antifungal and immunoregulatory properties of host defense peptides (HDPs) in the design and evaluation of new antifungal therapeutics and discuss historical limitations and recent advances in this quest.

Harnessing biomolecules for bioinspired dental biomaterials

Dental clinicians have relied for centuries on traditional dental materials (polymers, ceramics, metals, and composites) to restore oral health and function to patients. Clinical outcomes for many crucial dental therapies remain poor despite many decades of intense research on these materials. Recent attention has been paid to biomolecules as a chassis for engineered preventive, restorative, and regenerative approaches in dentistry. Indeed, biomolecules represent a uniquely versatile and precise tool to enable the design and development of bioinspired multifunctional dental materials to spur advancements in dentistry. In this review, we survey the range of biomolecules that have been used across dental biomaterials. Our particular focus is on the key biological activity imparted by each biomolecule toward prevention of dental and oral diseases as well as restoration of oral health. Additional emphasis is placed on the structure-function relationships between biomolecules and their biological activity, the unique challenges of each clinical condition, limitations of conventional therapies, and the advantages of each class of biomolecule for said challenge. Biomaterials for bone regeneration are not reviewed as numerous existing reviews on the topic have been recently published. We conclude our narrative review with an outlook on the future of biomolecules in dental biomaterials and potential avenues of innovation for biomaterial-based patient oral care.

Innate Inspiration: Antifungal Peptides and Other Immunotherapeutics From the Host Immune Response

The purpose of this review is to describe antifungal therapeutic candidates in preclinical and clinical development derived from, or directly influenced by, the immune system, with a specific focus on antimicrobial peptides (AMP). Although the focus of this review is AMP with direct antimicrobial effects on fungi, we will also discuss compounds with direct antifungal activity, including monoclonal antibodies (mAb), as well as immunomodulatory molecules that can enhance the immune response to fungal infection, including immunomodulatory AMP, vaccines, checkpoint inhibitors, interferon and colony stimulating factors as well as immune cell therapies. The focus of this manuscript will be a non-exhaustive review of antifungal compounds in preclinical and clinical development that are based on the principles of immunology and the authors acknowledge the incredible amount of in vitro and in vivo work that has been conducted to develop such therapeutic candidates.

Salivary proteome of a Neotropical primate: potential roles in host defense and oral food perception

BACKGROUND

Saliva contains a very complex mixture of proteins for defense against microbiological pathogens and for oral food perception. Howler monkeys are Neotropical primates that can consume a mostly leaf diet. They are well known to thrive in highly disturbed habitats where they may cope with a diversity of dietary challenges and infection risks. We aimed to describe the salivary proteome of howlers to contribute to better understanding of their physiology.

METHODS

We analyzed the salivary proteins of wild black howler monkeys (Alouatta pigra), by SDS-PAGE-1-D and Nano LC-MS/MS and categorized them by their function involved in host defense and oral food perception.

RESULTS

Our proteomic analysis identified 156 proteins in howler saliva including a number of host defense peptides that are the first line of defense in mammals, such as defensin, cathelicidin, dermcidin, and lactotransferrin, and proteins with anti-bacterial, anti-fungal, and anti-viral capacity, such as IgA, IgG, IgM, BPI, salivary heat shock 70 kDa protein, beta-2-microbulin, and protein S-100. We also identified key proteins necessary for taste perception, including salivary carbonic anhydrase VI, cystatin D, IgA, and fatty acid-binding protein. Proteins to detect astringent foods were identifying, including four members of cystatins (A, B, C and D), lactoperoxidase, and histidine-rich proteins. No chitinase and amylase were identified as would be expected because howlers do not eat insects and little starch. These findings provide basic information to future studies in oral biology, ingestive physiology, and physiological ecology of mammals and non-human primates.

NMR Assisted Antimicrobial Peptide Designing: Structure Based Modifications and Functional Correlation of a Designed Peptide VG16KRKP

Antimicrobial Peptides (AMPs), within their realm incorporate a diverse group of structurally and functionally varied peptides, playing crucial roles in innate immunity. Over the last few decades, the field of AMP has seen a huge upsurge, mainly owing to the generation of the so-called drug resistant 'superbugs' as well as limitations associated with the existing antimicrobial agents. Due to their resilient biological properties, AMPs can very well form the sustainable alternative for nextgeneration therapeutic agents. Certain drawbacks associated with existing AMPs are, however, issues of major concern, circumventing which are imperative. These limitations mainly include proteolytic cleavage and hence poor stability inside the biological systems, reduced activity due to inadequate interaction with the microbial membrane, and ineffectiveness because of inappropriate delivery among others. In this context, the application of naturally occurring AMPs as an efficient prototype for generating various synthetic and designed counterparts has evolved as a new avenue in peptide-based therapy. Such designing approaches help to overcome the drawbacks of the parent AMPs while retaining the inherent activity. In this review, we summarize some of the basic NMR structure based approaches and techniques which aid in improving the activity of AMPs, using the example of a 16-residue dengue virus fusion protein derived peptide, VG16KRKP. Using first principle based designing technique and high resolution NMR-based structure characterization we validate different types of modifications of VG16KRKP, highlighting key motifs, which optimize its activity. The approaches and designing techniques presented can support our peers in their drug development work.

Development and Characterization of a Novel Peptide-Loaded Antimicrobial Ocular Insert

Infectious ocular keratitis is the leading cause of blindness worldwide. Bacterial resistance to classical pharmacological treatments raised the interest of researchers towards antimicrobial peptide (AMP)-based therapy. hLF 1-11, a synthetic antimicrobial peptide derived from the N-terminus of human lactoferrin, proved effective against different bacteria and yeast but, like all proteinaceous materials, it is unstable from chemical, physical, and biological points of view. In this study, new freeze-dried solid matrices containing mucoadhesive polymers were prepared and characterized in terms of rheology, hydration time, bioadhesion, drug content, and in vitro release. The formulation HPMC/T2/HA/hLF 1-11_fd was selected for the delivery of hLF 1-11, since it showed good drug recovery and no chemical degradation up to at least 6 months (long-term stability). Furthermore, the HPMC/T2/HA/hLF 1-11_fd matrix allowed for the release of the drug in a simulated physiological environment, linked to an optimal hydration time, and the peptide antimicrobial activity was preserved for up to 15 months of storage, a very promising result considering the chemical liability of proteinaceous material. For its properties, the freeze-dried matrix developed in this study could be a good platform for the delivery of antimicrobial peptides in the precorneal area to treat infectious phenomena of the ocular surface.

Milk Peptides Survive In Vivo Gastrointestinal Digestion and Are Excreted in the Stool of Infants

BACKGROUND

Human milk peptides released by gastrointestinal proteases have been identified with bioactivities that can benefit the infant but must first reach their respective sites of activity. Peptides in the stool either survived to or were released inside the intestinal tract, and thus had the opportunity to exert bioactivity there. However, it is unknown whether any milk peptides, bioactive or not, can survive in the stool of infants.

OBJECTIVE

The aim of this study was primarily to identify milk peptides in infant stool samples and secondarily test the hypotheses that the milk peptide profiles of stools are different between preterm infants at different days of life and between preterm and term infants.

METHODS

Infant stool samples were collected from 16 preterm infants (<34 weeks gestational age) at 8 or 9 and 21 or 22 days of life (DOL), and from 10 term infants (>34 weeks gestational age) at 8 or 9 DOL. Milk peptides were isolated from the stool samples and identified using tandem MS. The peptide counts and abundances were compared between infant groups.

RESULTS

In total, 118 exclusively milk-derived peptides from the caseins and α-lactalbumin were present in the stool samples, including some peptides with known or potential bioactivity. The remaining 8014 identified peptides could be derived either from milk or endogenous proteins. Although many individual milk peptides were significantly different between preterm infants at 8/9 and 21/22 DOL and between preterm and term infants, total peptide abundance and count were similar for all 3 groups.

CONCLUSIONS

This is the first study to confirm the survival of milk peptides in the stool of infants. Some of the peptides had potential bioactivities that could influence infant gut development. These results are important to understand the physiological relevance of human milk peptides to the infant.

Protocol for the Lactoferrin Infant Feeding Trial (LIFT): a randomised trial of adding lactoferrin to the feeds of very-low birthweight babies prior to hospital discharge

INTRODUCTION

Very-low birthweight (VLBW, <1500 g) infants comprise about 1%-1.4% of all births in high-income countries. Every year, about 3000 VLBW babies in Australia and New Zealand receive intensive care. Many die or else survive with severe brain injury, retinopathy, late-onset sepsis or necrotising enterocolitis (NEC), each of which carries substantial risk of disability.

METHODS AND ANALYSIS

This trial tests whether adding bovine lactoferrin (bLF) to feeds in VLBW infants improves (1) survival to hospital discharge free from brain injury, late-onset sepsis, NEC and treated retinopathy of prematurity (primary composite end point); (2) each component of the primary composite end point and (3) time to reach full enteral feeds, number of blood transfusions, chronic lung disease and length of hospital stay. It includes a cost-effectiveness analysis of bLF in improving survival free from major morbidity, and evaluates the effect of bLF on survival and developmental outcomes at 24 to 36 months corrected gestational age.This is a multicentre, two-arm, randomised trial comparing the treatment group receiving bLF added to breast milk or formula milk daily (up to 250 mg/kg/day bLF) versus the control group receiving no bLF supplementation. The intervention is administered until 34 completed weeks corrected gestation or for 2 weeks, whichever is longer, or until discharge home, if earlier. The target sample size of 1500 participants yields 85% power, at the two-sided 5% level significance, to detect a difference in proportions meeting the primary outcome assuming the true probability is 74% in controls and 80.5% in the bLF group.

ETHICS AND DISSEMINATION

This protocol was approved by Northern Sydney Local Human Research Ethics Committee in January 2017 (Version 2.0, Reference 1003-118M) and other relevant ethics committees. The findings of the trial will be disseminated through peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

ACTRN12611000247976; Pre-results.

Sequential and Structural Aspects of Antifungal Peptides from Animals, Bacteria and Fungi Based on Bioinformatics Tools

Emerging drug resistance varieties and hyper-virulent strains of microorganisms have compelled the scientific fraternity to develop more potent and less harmful therapeutics. Antimicrobial peptides could be one of such therapeutics. This review is an attempt to explore antifungal peptides naturally produced by prokaryotes as well as eukaryotes. They are components of innate immune system providing first line of defence against microbial attacks, especially in eukaryotes. The present article concentrates on types, structures, sources and mode of action of gene-encoded antifungal peptides such as mammalian defensins, protegrins, tritrpticins, histatins, lactoferricins, antifungal peptides derived from birds, amphibians, insects, fungi, bacteria and their synthetic analogues such as pexiganan, omiganan, echinocandins and Novexatin. In silico drug designing, a major revolution in the area of therapeutics, facilitates drug development by exploiting different bioinformatics tools. With this view, bioinformatics tools were used to visualize the structural details of antifungal peptides and to predict their level of similarity. Current practices and recent developments in this area have also been discussed briefly.

Nanotherapeutics: An insight into healthcare and multi-dimensional applications in medical sector of the modern world

In recent years nanotechnology has revolutionized the healthcare strategies and envisioned to have a tremendous impact to offer better health facilities. In this context, medical nanotechnology involves design, fabrication, regulation, and application of therapeutic drugs and devices having a size in nano-range (1-100 nm). Owing to the revolutionary implications in drug delivery and gene therapy, nanotherapeutics has gained increasing research interest in the current medical sector of the modern world. The areas which anticipate benefits from nano-based drug delivery systems are cancer, diabetes, infectious diseases, neurodegenerative diseases, blood disorders and orthopedic problems. The development of nanotherapeutics with multi-functionalities has considerable potential to fill the lacunae existing in the present therapeutic domain. Nanomedicines in the field of cancer management have enhanced permeability and retention of drugs thereby effectively targeting the affected tissues. Polymeric conjugates of asparaginase, polymeric micelles of paclitaxel have been recmended for various types of cancer treatment .The advancement of nano therapeutics and diagnostics can provide the improved effectiveness of the drug with less or no toxicity concerns. Similarly, diagnostic imaging is having potential future applications with newer imaging elements at nano level. The newly emerging field of nanorobotics can provide new directions in the field of healthcare. In this article, an attempt has been made to highlight the novel nanotherapeutic potentialities of polymeric nanoparticles, nanoemulsion, solid lipid nanoparticle, nanostructured lipid carriers, dendrimers, nanocapsules and nanosponges based approaches. The useful applications of these nano-medicines in the field of cancer, nutrition, and health have been discussed in details. Regulatory and safety concerns along with the commercial status of nanosystems have also been presented. In summary, a successful translation of emerging nanotherapeutics into commercial products may lead to an expansion of biomedical science. Towards the end of the review, future perspectives of this important field have been introduced briefly.

The N-Terminus of Human Lactoferrin Displays Anti-biofilm Activity on Candida parapsilosis in Lumen Catheters

Candida parapsilosis is a major cause of hospital-acquired infection, often related to parenteral nutrition administered via catheters and hand colonization of health care workers, and its peculiar biofilm formation ability on plastic surfaces. The mortality rate of 30% points to the pressing need for new antifungal drugs. The present study aimed at analyzing the inhibitory activity of the N-terminal lactoferrin-derived peptide, further referred to as hLF 1-11, against biofilms produced by clinical isolates of C. parapsilosis characterized for their biofilm forming ability and fluconazole susceptibility. hLF 1-11 anti-biofilm activity was assessed in terms of reduction of biofilm biomass, metabolic activity, and observation of sessile cell morphology on polystyrene microtiter plates and using an in vitro model of catheter-associated C. parapsilosis biofilm production. Moreover, fluctuation in transcription levels of genes related to cell adhesion, hyphal development and extracellular matrix production upon peptide exposure were evaluated by quantitative real time RT-PCR. The results revealed that hLF 1-11 exhibits an inhibitory effect on biofilm formation by all the C. parapsilosis isolates tested, in a dose-dependent manner, regardless of their fluconazole susceptibility. In addition, hLF 1-11 induced a statistically significant dose-dependent reduction of preformed-biofilm cellular density and metabolic activity at high peptide concentrations only. Interestingly, when assessed in a catheter lumen, hLF 1-11 was able to induce a 2-log reduction of sessile cell viability at both the peptide concentrations used in RPMI diluted in NaPB. A more pronounced anti-biofilm effect was observed (3.5-log reduction) when a 10% glucose solution was used as experimental condition on both early and preformed C. parapsilosis biofilm. Quantitative real time RT-PCR experiments confirmed that hLF 1-11 down-regulates key biofilm related genes. The overall findings suggest hLF 1-11 as a promising candidate for the prevention of C. parapsilosis biofilm formation and to treatment of mature catheter-related C. parapsilosis biofilm formation.

Synergistic activity of synthetic N-terminal peptide of human lactoferrin in combination with various antibiotics against carbapenem-resistant Klebsiella pneumoniae strains

The spread of multi-drug resistant (MDR) Klebsiella pneumoniae strains producing carbapenemases points to a pressing need for new antibacterial agents. To this end, the in-vitro antibacterial activity of a synthetic N-terminal peptide of human lactoferrin, further referred to as hLF1-11, was evaluated against K. pneumoniae strains harboring different carbapenemase genes (i.e. OXA-48, KPC-2, KPC-3, VIM-1), with different susceptibility to colistin and other antibiotics, alone or in combination with conventional antibiotics (gentamicin, tigecycline, rifampicin, clindamycin, and clarithromycin). An antimicrobial peptide susceptibility assay was used to assess the bactericidal activity of hLF1-11 against the different K. pneumoniae strains tested. The synergistic activity was evaluated by a checkerboard titration method, and the fractional inhibitory concentration (FIC) index was calculated for the various combinations. hLF1-11 was more efficient in killing a K. pneumoniae strain susceptible to most antimicrobials (including colistin) than a colistin-susceptible strain and a colistin-resistant MDR K. pneumoniae strain. In addition, hLF1-11 exhibited a synergistic effect with the tested antibiotics against MDR K. pneumoniae strains. The results of this study indicate that resistance to hLF1-11 and colistin are not strictly associated, and suggest an hLF1-11-induced sensitizing effect of K. pneumoniae to antibiotics, especially to hydrophobic antibiotics, which are normally not effective on Gram-negative bacteria. Altogether, these data indicate that hLF1-11 in combination with antibiotics is a promising candidate to treat infections caused by MDR-K. pneumoniae strains.

Antifungal plant defensins: increased insight in their mode of action as a basis for their use to combat fungal infections

Plant defensins are small, cationic peptides with a highly conserved 3D structure. They have been studied extensively in the past decades. Various biological activities have been attributed to plant defensins, such as anti-insect and antimicrobial activities, but they are also known to affect ion channels and display antitumor activity. This review focuses on the structure, biological activity and antifungal mode of action of some well-characterized plant defensins, with particular attention to their fungal membrane target(s), their induced cell death mechanisms as well as their antibiofilm activity. As plant defensins are, in general, not toxic to human cells, show in vivo efficacy and have low frequencies of resistance occurrence, they are of particular interest in the fight against fungal infections.

The Antifungal Activity of Lactoferrin and Its Derived Peptides: Mechanisms of Action and Synergy with Drugs against Fungal Pathogens

Lactoferrin is a multifunctional iron-binding glycoprotein belonging to the transferrin family. It is found abundantly in milk and is present as a major protein in human exocrine secretions where it plays a role in the innate immune response. Various antifungal functions of lactoferrin have been reported including a wide spectrum of activity across yeasts and molds and synergy with other antifungal drugs in combination therapy, and various modes of action have been proposed. Bioactive peptides derived from lactoferrin can also exhibit strong antifungal activity, with some surpassing the potency of the whole protein. This paper reviews current knowledge of the spectrum of activity, proposed mechanisms of action, and capacity for synergy of lactoferrin and its peptides, including the three most studied derivatives: lactoferricin, lactoferrampin, and Lf(1-11), as well as some lactoferrin-derived variants and modified peptides.

Endogenous Pulmonary Antibiotics

The human lung produces a variety of peptides and proteins which have intrinsic antimicrobial activity. In general these molecules have broad spectra of antimicrobial activity, kill micro-organisms rapidly, and evade resistance generated by pathogens. In recent years it has become increasingly apparent that the antimicrobial peptides (AMPs) simultaneously possess immunomodulatory functions, suggesting complex roles for these molecules in regulating the clearance of, and immune response to, invading pathogens. These collective properties have stimulated considerable interest in the potential clinical application of endogenous AMPs.

This article outlines the biology of AMPs, their pattern of expression in the lung, and their functions, with reference to both antimicrobial and immunomodulatory activity. We then consider the biological importance of AMPs, before concentrating on the potential to use AMPs to therapeutic effect. The principles discussed in the article apply to innate immune defence throughout the body, but particular emphasis is placed on AMPs in the lung and the potential application to pulmonary infection.

Anticancer activities of bovine and human lactoferricin-derived peptides

Lactoferrin (LF) is a mammalian host defense glycoprotein with diverse biological activities. Peptides derived from the cationic region of LF possess cytotoxic activity against cancer cells in vitro and in vivo. Bovine lactoferricin (LFcinB), a peptide derived from bovine LF (bLF), exhibits broad-spectrum anticancer activity, while a similar peptide derived from human LF (hLF) is not as active. In this work, several peptides derived from the N-terminal regions of bLF and hLF were studied for their anticancer activities against leukemia and breast-cancer cells, as well as normal peripheral blood mononuclear cells. The cyclized LFcinB-CLICK peptide, which possesses a stable triazole linkage, showed improved anticancer activity, while short peptides hLF11 and bLF10 were not cytotoxic to cancer cells. Interestingly, hLF11 can act as a cell-penetrating peptide; when combined with the antimicrobial core sequence of LFcinB (RRWQWR) through either a Pro or Gly-Gly linker, toxicity to Jurkat cells increased. Together, our work extends the library of LF-derived peptides tested for anticancer activity, and identified new chimeric peptides with high cytotoxicity towards cancerous cells. Additionally, these results support the notion that short cell-penetrating peptides and antimicrobial peptides can be combined to create new adducts with increased potency.

Functional gold nanoparticle-based antibacterial agents for nosocomial and antibiotic-resistant bacteria

AIM

Medical treatments for bacterial-infections have become challenging because of the emergence of antibiotic-resistant bacterial strains. Thus, new therapeutics and antibiotics must be developed.

MATERIALS & METHODS

Arginine and tryptophan can target negatively-charged bacteria and penetrate bacterial cell membrane, respectively. Synthetic-peptides containing arginine, tryptophan and cysteine termini, in other words, (DVFLG)2REEW4C and (DVFLG)2REEW2C, as starting materials were mixed with aqueous tetrachloroauric acid to generate peptide-immobilized gold nanoparticles (i.e., [DVFLG]2REEW4C-AuNPs and [DVFLG]2REEW2C-AuNPs) through one-pot reactions.

RESULTS & DISCUSSION

The peptide immobilized AuNPs exhibit targeting capacity and antibacterial activity. Furthermore, (DVFLG)2REEW4C-AuNPs immobilized with a higher number of tryptophan molecules possess more effective antibacterial capacity than (DVFLG)2REEW2C-AuNPs. Nevertheless, they are not harmful for animal cells. The feasibility of using the peptide-AuNPs to inhibit the cell growth of bacterium-infected macrophages was demonstrated.

CONCLUSION

These results suggested that the proposed antibacterial AuNPs are effective antibacterial agents for Staphylococci, Enterococci and antibiotic-resistant bacterial strains. [Formula: see text].

Antimicrobial Activity of Lactoferrin-Related Peptides and Applications in Human and Veterinary Medicine

Antimicrobial peptides (AMPs) represent a vast array of molecules produced by virtually all living organisms as natural barriers against infection. Among AMP sources, an interesting class regards the food-derived bioactive agents. The whey protein lactoferrin (Lf) is an iron-binding glycoprotein that plays a significant role in the innate immune system, and is considered as an important host defense molecule. In search for novel antimicrobial agents, Lf offers a new source with potential pharmaceutical applications. The Lf-derived peptides Lf(1-11), lactoferricin (Lfcin) and lactoferrampin exhibit interesting and more potent antimicrobial actions than intact protein. Particularly, Lfcin has demonstrated strong antibacterial, anti-fungal and antiparasitic activity with promising applications both in human and veterinary diseases (from ocular infections to osteo-articular, gastrointestinal and dermatological diseases).

Isolation, characterization and mechanism of action of an antimicrobial peptide from Lecythis pisonis seeds with inhibitory activity against Candida albicans

Antimicrobial peptides (AMPs) are produced by a range of organisms as a first line of defense against invaders or competitors. Owing to their broad antimicrobial activity, AMPs have attracted attention as a potential source of chemotherapeutic drugs. The increasing prevalence of infections caused by Candida species as opportunistic pathogens in immunocompromised patients requires new drugs. Lecythis pisonis is a Lecythydaceae tree that grows in Brazil. The AMPs produced by this tree have not been described previously. We describe the isolation of 12 fractions enriched in peptides from L. pisonis seeds. Of the 12 fractions, at 10 μg/ml, the F4 fraction had the strongest growth inhibitory effect (53.7%) in Candida albicans, in addition to a loss of viability of 94.9%. The F4 fraction was separated into seven sub-fractions by reversed-phase chromatography. The F4.7' fraction had the strongest activity at 10 μg/ml, inhibiting C. albicans growth by 38.5% and a 69.3% loss of viability. The peptide in F4.7' was sequenced and was found to be similar to plant defensins. For this reason, the peptide was named L. pisonis defensin 1 (Lp-Def1). The mechanism of action that is responsible for C. albicans inhibition by Lp-Def1 includes a slight increase of reactive oxygen species induction and a significant loss of mitochondrial function. The results described here support the future development of plant defensins, specifically Lp-Def1, as new therapeutic substances against fungi, especially C. albicans.

A study of effects of peptide fragments of bovine and human lactoferrins on activities of three key HIV-1 enzymes

The intent of this study was to examine human and bovine lactoferrin fragments including lactoferrin (1-11), lactoferricin and lactoferrampin, all of which did not demonstrate hemolytic activity toward rabbit erythrocytes at 1 mM concentration, for possible inhibitory effects on the activities of HIV-1 reverse transcriptase, protease and integrase. The data showed that human lactoferricin was the most potent in inhibiting HIV-1 reverse transcriptase (IC50 =2 μM). Bovine lactoferricin (IC50 = 10 μM) and bovine lactoferrampin (IC50 = 150 μM) were less potent. Human lactoferrampin and human and bovine lactoferrin (1-11) at 1 mM concentration did not exhibit any inhibitory effect on HIV-1 reverse transcriptase. All peptides showed only a slight inhibitory effect (from slightly below 2% to 6% inhibition) on HIV-1 protease. Human lactoferrampin and bovine lactoferrampin showed obvious inhibitory effect on HIV-1 integrase at 37 μM and 18.5 μM, respectively. The HIV-1 integrase inhibitory activity of human lactoferrampin and bovine lactoferrampin was dose-dependent. The other peptides were devoid of HIV-1 integrase inhibitory activity. Thus, it is concluded that some lactoferrin fragments exert an inhibitory action on HIV-1 reverse transcriptase and HIV-1 integrase.

Characterization of hLF1-11 immobilization onto chitosan ultrathin films, and its effects on antimicrobial activity

hLF1-11 (GRRRRSVQWCA) is an antimicrobial peptide (AMP) with high activity against methicillin-resistant Staphylococcus aureus (MRSA), the most prevalent species in implant-associated infection. In this work, the effect of the surface immobilization on hLF1-11 antimicrobial activity was studied. Immobilization was performed onto chitosan thin films as a model for an implant coating due to its reported osteogenic and antibacterial properties. Chitosan thin films were produced by spin-coating on gold surfaces. hLF1-11 was immobilized onto these films by its C-terminal cysteine in an orientation that exposes the antimicrobial activity-related arginine-rich portion of the peptide. Two levels of exposure (with and without a polyethylene glycol (PEG) spacer) were analyzed. Covalent immobilization was further compared with the AMP physical adsorption onto chitosan films. Surfaces were characterized using ellipsometry, contact angle measurements, atomic force microscopy, infrared and X-ray photoelectron spectroscopies and using a fluorimetric assay for hLF1-11 quantification. Surface antimicrobial activity was assessed through surface adhesion and viability assays using an MRSA (S. aureus ATCC 33591). The incorporation of hLF1-11 increased significantly bacterial adhesion to chitosan films. However, the presence of hLF1-11, namely when immobilized through a PEG spacer, decreased the viability of adherent bacteria with regard to the control surface. These results demonstrated that hLF1-11 after covalent immobilization by its cysteine can maintain activity, particularly if a spacer is applied. However, further studies, exploring the opposite orientation or the same C-terminal orientation, but non-cysteine related, can help to clarify the potential of the hLF1-11 immobilization strategy.

Interplay between Candida albicans and the antimicrobial peptide armory

Antimicrobial peptides (AMPs) are key elements of innate immunity, which can directly kill multiple bacterial, viral, and fungal pathogens. The medically important fungus Candida albicans colonizes different host niches as part of the normal human microbiota. Proliferation of C. albicans is regulated through a complex balance of host immune defense mechanisms and fungal responses. Expression of AMPs against pathogenic fungi is differentially regulated and initiated by interactions of a variety of fungal pathogen-associated molecular patterns (PAMPs) with pattern recognition receptors (PRRs) on human cells. Inflammatory signaling and other environmental stimuli are also essential to control fungal proliferation and to prevent parasitism. To persist in the host, C. albicans has developed a three-phase AMP evasion strategy, including secretion of peptide effectors, AMP efflux pumps, and regulation of signaling pathways. These mechanisms prevent C. albicans from the antifungal activity of the major AMP classes, including cathelicidins, histatins, and defensins leading to a basal resistance. This minireview summarizes human AMP attack and C. albicans resistance mechanisms and current developments in the use of AMPs as antifungal agents.

Preparation and antimicrobial action of three tryptic digested functional molecules of bovine lactoferrin

Lactoferrin is an 80 kDa bilobal, iron binding glycoprotein which is primarily antimicrobial in nature. The hydrolysis of lactoferrin by various proteases in the gut produces several functional fragments of lactoferrin which have varying molecular sizes and properties. Here, bovine lactoferrin has been hydrolyzed by trypsin, the major enzyme present in the gut, to produce three functional molecules of sizes approximately 21 kDa, 38 kDa and 45 kDa. The molecules have been purified using ion exchange and gel filtration chromatography and identified using N-terminal sequencing, which reveals that while the 21 kDa molecule corresponds to the N2 domain (21LF), the 38 kDa represents the whole C-lobe (38LF) and the 45 kDa is a portion of N1 domain of N-lobe attached to the C-lobe (45LF). The iron binding and release properties of 21LF, 38LF and 45LF have been studied and compared. The sequence and structure analysis of the portions of the excision sites of LF from various species have been done. The antibacterial properties of these three molecules against bacterial strains, Streptococcus pyogenes, Escherichia coli, Yersinia enterocolitica and Listeria monocytogenes were investigated. The antifungal action of the molecules was also evaluated against Candida albicans. This is the first report on the antimicrobial actions of the trypsin cleaved functional molecules of lactoferrin from any species.

Lactoferrin and the newborn: current perspectives

Neonatal sepsis and necrotizing enterocolitis (NEC) are associated with significant mortality and morbidity. Inflammation secondary to sepsis and NEC increases morbidity, especially those related to the lung, brain and eye. Therapeutic strategies that target inflammation and decrease the emergence of antibiotic resistance are urgently needed. Lactoferrin (Lf) is a multifunctional protein that modulates inflammation, cell growth and differentiation and has broad antimicrobial activity. Studies evaluating the efficacy and safety of Lf in the prevention of neonatal sepsis and NEC are currently in progress, and one completed study shows significant promise. In this article, the functions of this multifunctional molecule and current clinical evidence for its use in the newborn are reviewed. Lf prophylaxis and therapy may have a significant impact in improving clinical outcomes of vulnerable preterm neonates.

Properties and mechanisms of action of naturally occurring antifungal peptides

Antimicrobial peptides are a vital component of the innate immune system of all eukaryotic organisms and many of these peptides have potent antifungal activity. They have potential application in the control of fungal pathogens that are a serious threat to both human health and food security. Development of antifungal peptides as therapeutics requires an understanding of their mechanism of action on fungal cells. To date, most research on antimicrobial peptides has focused on their activity against bacteria. Several antimicrobial peptides specifically target fungal cells and are not active against bacteria. Others with broader specificity often have different mechanisms of action against bacteria and fungi. This review focuses on the mechanism of action of naturally occurring antifungal peptides from a diverse range of sources including plants, mammals, amphibians, insects, crabs, spiders, and fungi. While antimicrobial peptides were originally proposed to act via membrane permeabilization, the mechanism of antifungal activity for these peptides is generally more complex and often involves entry of the peptide into the cell.

Enhanced efficacy of synergistic combinations of antimicrobial peptides with caspofungin versus Candida albicans in insect and murine models of systemic infection

The objective of this study was to determine whether combinations of antimicrobial peptides (AMPs) with caspofungin display enhanced antifungal activity versus Candida albicans in vitro and in vivo. Three conventional AMPs that satisfied criteria favouring their potential development as novel antifungals were selected for investigation. Colistin sulphate was also included as a cyclic peptide antibiotic used in the clinic. Minimum inhibitory concentrations (MICs) were determined for each antifungal agent and checkerboard assays were used to determine fractional inhibitory concentration index (FICI) values for dual combinations of AMPs or colistin with caspofungin. Viability assays were performed for the same combinations in order to investigate fungicidal interactions. Synergistic antifungal combinations were then tested for efficacy in vivo and compared to monotherapies in wax moth larva and murine models of systemic C. albicans infection. In combination with caspofungin, each of the AMPs [hMUC7-12, DsS3(1-16), hLF(1-11)] and colistin were synergistic and candidacidal in vitro. The treatment of infected wax moth larvae with combinations of caspofungin with hMUC7-12, DsS3(1-16) or colistin resulted in significant enhancements in survival compared to treatment with monotherapies. Notably, the treatment of C. albicans-infected mice with a combination of caspofungin and DsS3(1-16) resulted in the enhancement of survival compared to groups treated with just the individual agents. This study demonstrates that combination therapies containing caspofungin and AMPs or colistin merit further development as potential novel treatments for C. albicans infections.

Molecular biology of lactoferrin and its role in modulating immunity and viral pathogenesis

Lactoferrin (Lf), also known as lactotransferrin, is a globular glycoprotein belonging to the transferrin family that is widely expressed in several fluids such as milk, tears, gastric fluid and saliva. Apart from its ability to bind and regulate iron levels in body secretions, Lf possesses antimicrobial activity and is specifically a component of the innate immune system. The antibacterial activity of Lf occurs by depriving the environment of iron essential for bacterial growth. In the case of antiviral activity, Lf may act as a competitor for the cell membrane receptors commonly used by viruses to enter cells. This review summarizes the roles of Lf under normal physiology, with a special emphasis on viruses. The authors also discuss in great detail the interactions between Lf and Kaposi’s sarcoma-associated herpesvirus, as well as possible future directions of research that may progress toward designing modern-day therapeutics to counter viral infections.

Antimicrobial lactoferrin peptides: the hidden players in the protective function of a multifunctional protein

Lactoferrin is a multifunctional, iron-binding glycoprotein which displays a wide array of modes of action to execute its primary antimicrobial function. It contains various antimicrobial peptides which are released upon its hydrolysis by proteases. These peptides display a similarity with the antimicrobial cationic peptides found in nature. In the current scenario of increasing resistance to antibiotics, there is a need for the discovery of novel antimicrobial drugs. In this context, the structural and functional perspectives on some of the antimicrobial peptides found in N-lobe of lactoferrin have been reviewed. This paper provides the comparison of lactoferrin peptides with other antimicrobial peptides found in nature as well as interspecies comparison of the structural properties of these peptides within the native lactoferrin.

Chemical genomic screening of a Saccharomyces cerevisiae genomewide mutant collection reveals genes required for defense against four antimicrobial peptides derived from proteins found in human saliva

To compare the effects of four antimicrobial peptides (MUC7 12-mer, histatin 12-mer, cathelicidin KR20, and a peptide containing lactoferricin amino acids 1 to 11) on the yeast Saccharomyces cerevisiae, we employed a genomewide fitness screen of combined collections of mutants with homozygous deletions of nonessential genes and heterozygous deletions of essential genes. When an arbitrary fitness score cutoffs of 1 (indicating a fitness defect, or hypersensitivity) and -1 (indicating a fitness gain, or resistance) was used, 425 of the 5,902 mutants tested exhibited altered fitness when treated with at least one peptide. Functional analysis of the 425 strains revealed enrichment among the identified deletions in gene groups associated with the Gene Ontology (GO) terms "ribosomal subunit," "ribosome biogenesis," "protein glycosylation," "vacuolar transport," "Golgi vesicle transport," "negative regulation of transcription," and others. Fitness profiles of all four tested peptides were highly similar, particularly among mutant strains exhibiting the greatest fitness defects. The latter group included deletions in several genes involved in induction of the RIM101 signaling pathway, including several components of the ESCRT sorting machinery. The RIM101 signaling regulates response of yeasts to alkaline and neutral pH and high salts, and our data indicate that this pathway also plays a prominent role in regulating protective measures against all four tested peptides. In summary, the results of the chemical genomic screens of S. cerevisiae mutant collection suggest that the four antimicrobial peptides, despite their differences in structure and physical properties, share many interactions with S. cerevisiae cells and consequently a high degree of similarity between their modes of action.