Recombinant expression, purification and PEGylation of Paneth cell peptide (cryptdin-2) with value added attributes against Staphylococcus aureus

Revolutionizing orthopedic healthcare: a systematic review unveiling recombinant antimicrobial peptides

The increasing demand for orthopedic surgeries, including joint replacements, is driven by an aging population and improved diagnosis of joint conditions. Orthopedic surgeries carry a risk of infection, especially in patients with comorbidities. The rise of antibiotic resistance exacerbates this issue, necessitating alternatives like in vitro bioengineered antimicrobial peptides (AMPs), offering broad-spectrum activity and multiple action mechanisms. This review aimed to assess the prevalence of antimicrobial potential and the yield after purification among recombinant AMP families. The antimicrobial potential was evaluated using the Minimum Inhibitory Concentration (MIC) values against the most common bacteria involved in clinical infections. This systematic review adhered to PRISMA guidelines, focusing on in vitro studies of recombinant AMPs. The search strategy was run on PubMed, Scopus and Embase up to 30th March 2023. The Population, Exposure and Outcome model was used to extract the data from studies and ToxRTool for the risk of bias analysis. This review included studies providing peptide production yield data and MIC values against pathogenic bacteria. Non-English texts, reviews, conference abstracts, books, studies focusing solely on chemical synthesis, those reporting incomplete data sets, using non-standard MIC assessment methods, or presenting MIC values as ranges rather than precise concentrations, were excluded. From 370 publications, 34 studies on AMPs were analyzed. These covered 46 AMPs across 18 families, with Defensins and Hepcidins being most common. Yields varied from 0.5 to 2,700 mg/L. AMPs were tested against 23 bacterial genera, with MIC values ranging from 0.125 to >1,152 μg/mL. Arenicins showed the highest antimicrobial activity, particularly against common orthopedic infection pathogens. However, AMP production yields varied and some AMPs demonstrated limited effectiveness against certain bacterial strains. This systematic review emphasizes the critical role of bioengineered AMPs to cope infections and antibiotic resistance. It meticulously evaluates recombinant AMPs, focusing on their antimicrobial efficacy and production yields. The review highlights that, despite the variability in AMP yields and effectiveness, Arenicins and Defensins are promising candidates for future research and clinical applications in treating antibiotic-resistant orthopedic infections. This study contributes significantly to the understanding of AMPs in healthcare, underscoring their potential in addressing the growing challenge of antibiotic resistance. Systematic review registration:https://osf.io/2uq4c/.

Antimicrobial Peptide-Poly(ethylene glycol) Conjugates: Connecting Molecular Architecture, Solution Properties, and Functional Performance

Antimicrobial peptides (AMPs) are promising alternatives to conventional antibiotics for treating infections caused by drug-resistant bacteria; yet, many peptides are limited by toxicity to eukaryotic cells and instability in biological environments. Conjugation to linear polymers that reduce cytotoxicity and improve stability, however, often decreases antimicrobial activity. In this work, we combine the biocompatibility advantages of poly(ethylene glycol) (PEG) with the efficacy merits of nonlinear polymer architectures that accommodate multiple AMPs per molecule. By conjugating a chemokine-derived AMP, stapled Ac-P9, to linear and star-shaped PEG with various arm numbers and lengths, we investigated the role of molecular architecture in solution properties (i.e., ζ-potential, size, and morphology) and performance (i.e., antimicrobial activity, hemolysis, and protease resistance). Linear, 4-arm, and 8-arm conjugates with 2-2.5 kDa PEG arms were found to form nanoscale structures in solution with lower ζ-potentials relative to the unconjugated AMP, suggesting that the polymer partially shields the cationic AMP. Reducing the length of the PEG arms of the 8-arm conjugate to 1.25 kDa appeared to better reveal the peptide, seen by the increased ζ-potential, and promote assembly into particles with a larger size and defined spherical morphology. The antimicrobial effects exerted by the short 8-arm conjugate rivaled that of the unconjugated peptide, and the AMP constituents of the short 8-arm conjugate were protected from proteolytic degradation. All other conjugates examined also imparted a degree of protease resistance, but exhibited some reduced level of antimicrobial activity as compared to the AMP alone. None of the conjugates caused significant cytotoxic effects, which bodes well for their future potential to treat infections. While enhancing proteolytic stability often comes with the cost of lower antimicrobial activity, we have found that presenting AMPs at high density on a neutral nonlinear polymer strikes a favorable balance, exhibiting both enhanced stability and high antimicrobial activity.

Fundamental Uses of Peptides as a New Model in Both Treatment and Diagnosis

An amino acid short chain is known as a peptide. Peptide bonds are the connections that hold the amino acids of a peptide together in a particular order. Characteristically, the shorter length of peptides helps to identify them from proteins. Different ways are used to classify peptides, including chain length, source of peptides, or their biological functions. The fact that peptides serve several purposes suggests that there is a foundation for improvement in peptide production and structure to enhance action. In addition, many patents on peptides for therapeutic and diagnostic approaches have been obtained. This review aims to give an overview of peptides used recently in treatment and diagnosis.

A systematical review on antimicrobial peptides and their food applications

Food safety issues are a major concern in food processing and packaging industries. Food spoilage is caused by microbial contamination, where antimicrobial peptides (APs) provide solutions by eliminating microorganisms. APs such as nisin have been successfully and commonly used in food processing and preservation. Here, we discuss all aspects of the functionalization of APs in food applications. We briefly review the natural sources of APs and their native functions. Recombinant expression of APs in microorganisms and their yields are described. The molecular mechanisms of AP antibacterial action are explained, and this knowledge can further benefit the design of functional APs. We highlight current utilities and challenges for the application of APs in the food industry, and address rational methods for AP design that may overcome current limitations.

C-Terminal PEGylation Improves SAAP-148 Peptide's Immunomodulatory Activities

Synthetic antibacterial and anti-biofilm peptide (SAAP)-148 was developed to combat bacterial infections not effectively treatable with current antibiotics. SAAP-148 is highly effective against antimicrobial-resistant bacteria without inducing resistance; however, challenges for further development of SAAP-148 include its cytotoxicity and short circulation half-life. To circumvent these drawbacks, a library of SAAP-148 linked to polyethylene glycol (PEG) groups of various lengths was synthesized and screened for in vitro antibacterial activity and hemolytic activity. Results indicated that PEGylated SAAP-148 variants combine antibacterial activities with reduced hemolysis compared to SAAP-148. Interestingly, proinflammatory immunomodulatory activities of SAAP-148 were enhanced upon C-terminal PEGylation, with SAAP-148-PEG27 showing the most effect. SAAP-148-PEG27 enhanced SAAP-148's capacity to chemoattract human neutrophils and was able to more efficiently (re)direct M-CSF-induced monocyte-macrophage differentiation toward type 1 macrophages as opposed to SAAP-148. Furthermore, dendritic cells with a stronger mature expression profile were produced if monocytes were exposed to SAAP-148-PEG27 during monocyte-immature dendritic cell differentiation in comparison to SAAP-148. Parameters that influenced the immunomodulatory activities of the peptide-PEG conjugate include (i) the length of the PEG group, (ii) the position of PEG conjugation, and (iii) the peptide sequence. Together, these results indicate that SAAP-148-PEG27 is highly effective in redirecting monocyte-macrophage differentiation toward a proinflammatory phenotype and promoting monocyte-mature dendritic cell development. Therefore, SAAP-148-PEG27 may be a promising agent to modulate inadequate immune responses in case of tumors and chronically infected wounds.

Going Beyond Host Defence Peptides: Horizons of Chemically Engineered Peptides for Multidrug-Resistant Bacteria

Multidrug-resistant (MDR) bacteria are considered a health threat worldwide, and this problem is set to increase over the decades. The ESKAPE, a group of six pathogens including Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp. is the major source of concern due to their high death incidence and nosocomial acquired infection. Host defence peptides (HDPs) are a class of ribosomally synthesised peptides that have shown promising results in combating MDR, including the ESKAPE group, in- and outside bacterial biofilms. However, their poor pharmacokinetics in physiological mediums may impede HDPs from becoming viable clinical candidates. To circumvent this problem, chemical engineering of HDPs has been seen as an emergent approach to not only improve their pharmacokinetics but also their efficacy against pathogens. In this review, we explore several chemical modifications of HDPs that have shown promising results, especially against ESKAPE pathogens, and provide an overview of the current findings with respect to each modification.

The future of recombinant host defense peptides

The antimicrobial resistance crisis calls for the discovery and production of new antimicrobials. Host defense peptides (HDPs) are small proteins with potent antibacterial and immunomodulatory activities that are attractive for translational applications, with several already under clinical trials. Traditionally, antimicrobial peptides have been produced by chemical synthesis, which is expensive and requires the use of toxic reagents, hindering the large-scale development of HDPs. Alternatively, HDPs can be produced recombinantly to overcome these limitations. Their antimicrobial nature, however, can make them toxic to the hosts of recombinant production. In this review we explore the different strategies that are used to fine-tune their activities, bioengineer them, and optimize the recombinant production of HDPs in various cell factories.

Strategies employed in the design of antimicrobial peptides with enhanced proteolytic stability

Due to the alarming developing rate of multidrug-resistant bacterial pathogens, the development and modification of antimicrobial peptides (AMPs) are unprecedentedly active. Despite the fact that considerable efforts have been expended on the discovery and design strategies of AMPs, the clinical translation of peptide antibiotics remains inadequate. A large number of articles and reviews credited the limited success of AMPs to their poor stability in the biological environment, particularly their poor proteolytic stability. In the past forty years, various design strategies have been used to improve the proteolytic stability of AMPs, such as sequence modification, cyclization, peptidomimetics, and nanotechnology. Herein, we focus our discussion on the progress made in improving the proteolytic stability of AMPs and the principle, successes, and limitations of various anti-proteolytic design strategies. It is of prospective significance to extend current insights into the degradation-related inactivation of AMPs and also alleviate/overcome the problem.

Host Defense Peptides: Dual Antimicrobial and Immunomodulatory Action

The rapid rise of multidrug-resistant (MDR) bacteria has once again caused bacterial infections to become a global health concern. Antimicrobial peptides (AMPs), also known as host defense peptides (HDPs), offer a viable solution to these pathogens due to their diverse mechanisms of actions, which include direct killing as well as immunomodulatory properties (e.g., anti-inflammatory activity). HDPs may hence provide a more robust treatment of bacterial infections. In this review, the advent of and the mechanisms that lead to antibiotic resistance will be described. HDP mechanisms of antibacterial and immunomodulatory action will be presented, with specific examples of how the HDP aurein 2.2 and a few of its derivatives, namely peptide 73 and cG4L73, function. Finally, resistance that may arise from a broader use of HDPs in a clinical setting and methods to improve biocompatibility will be briefly discussed.

Molecular engineering of antimicrobial peptide (AMP)-polymer conjugates

As antimicrobial resistance becomes an increasing threat, bringing significant economic and health burdens, innovative antimicrobial treatments are urgently needed. While antimicrobial peptides (AMPs) are promising therapeutics, exhibiting high activity against resistant bacterial strains, limited stability and toxicity to mammalian cells has hindered clinical development. Attaching AMPs to polymers provides opportunities to present AMPs in a way that maximizes bacterial killing while enhancing compatibility with mammalian cells, stability, and solubility. Conjugation of an AMP to a linear hydrophilic polymer yields the desired improvements in stability, mammalian cell compatibility, and solubility, yet often markedly reduces bactericidal effects. Non-linear polymer architectures and supramolecular assemblies that accommodate multiple AMPs per polymer chain afford AMP-polymer conjugates that strike a superior balance of antimicrobial activity, mammalian cell compatibility, stability, and solubility. Therefore, we review the design criteria, building blocks, and synthetic strategies for engineering AMP-polymer conjugates, emphasizing the connection between molecular architecture and antimicrobial performance to inspire and enable further innovation to advance this emerging class of biomaterials.

The effect of structural modification of antimicrobial peptides on their antimicrobial activity, hemolytic activity, and plasma stability

In this article, a series of modifications were made on an antimicrobial peptide F_2,5,12 W, including altering the amino acid sequence, introducing cysteine and other typical amino acids, developing peptide dimers via disulfide bonds, and conjugating with mPEG, in order to enhance the antimicrobial activity, plasma stability, and reduce the hemolytic activity of peptides. The results showed that mPEG conjugation could significantly improve the plasma stability and reduce the hemolytic activity of peptides, while the antimicrobial activity decreased meanwhile. However, altering the sequence of the peptide without changing its amino acid composition had little impact on its antimicrobial activity and plasma stability. The introduction of cysteine enhanced the plasma stability of peptides conspicuously, but at the same time, the increased hydrophobicity of peptides increased their hemolysis. The antimicrobial mechanism and cytotoxicity of the peptides with relatively high antimicrobial activity were also studied. In general, this study provided some ideas for the rational design and structure optimization of antimicrobial peptides.

Cyanobacteria and Eukaryotic Microalgae as Emerging Sources of Antibacterial Peptides

Cyanobacteria and microalgae are oxygen-producing photosynthetic unicellular organisms encompassing a great diversity of species, which are able to grow under all types of extreme environments and exposed to a wide variety of predators and microbial pathogens. The antibacterial compounds described for these organisms include alkaloids, fatty acids, indoles, macrolides, peptides, phenols, pigments and terpenes, among others. This review presents an overview of antibacterial peptides isolated from cyanobacteria and microalgae, as well as their synergism and mechanisms of action described so far. Antibacterial cyanopeptides belong to different orders, but mainly from Oscillatoriales and Nostocales. Cyanopeptides have different structures but are mainly cyclic peptides. This vast peptide repertoire includes ribosomal and abundant non-ribosomal peptides, evaluated by standard conventional methodologies against pathogenic Gram-negative and Gram-positive bacteria. The antibacterial activity described for microalgal peptides is considerably scarcer, and limited to protein hydrolysates from two Chlorella species, and few peptides from Tetraselmis suecica. Despite the promising applications of antibacterial peptides and the importance of searching for new natural sources of antibiotics, limitations still persist for their pharmaceutical applications.

Preparation, Characterization and Pharmacokinetic Study of N-Terminal PEGylated D-Form Antimicrobial Peptide OM19r-8

Recently, new cationic antibacterial peptide OM19R has been designed with low minimum inhibitory concentration (MIC) values against some gram-negative bacteria, such as Escherichia coli, Salmonella, and Shigella. However, this hybrid peptide, like most antibacterial peptides, has low enzyme stability and short half-life, which, in turn, increases the drug's cost. In this study, an antibacterial peptide (OM19r-8) was obtained containing some D-Arg amino acids. The new preparations were carried out through the replacement of l-Arginine by d-Arginine and the addition of PEG chains. Firstly, eight OM19r series of antibacterial peptides were obtained by designing D-Arg. Then, a polyethylene glycol-modified product mPEG₅-butyrALD-OM19r-8 (mPEG₅-OM19r-8) was isolated and purified by reverse-phase high-performance liquid chromatography (RT-HPLC). The enzyme stability test showed that the resistance of antibacterial peptide OM19r-8 to protease degradation increased by 4-32-fold. Moreover, the Time-kill studies showed that the germicidal kinetics curves of mPEG₅-OM19r-8 and OM19r-8 to Escherichia coli had a similar trend, thus suggesting that PEG modification has an acceptable effect on the activity of the original peptide. Furthermore, the elimination of half-life (28.09 ± 2.81min) of mPEG₅-OM19r-8, and the area under the drug concentration-time curve (2686.48 ± 651.36min∗ug/ml) was significantly prolonged. The current study demonstrates an example that optimizes the AMP by utilizing L-to-D amino acid replacement and including PEG chains. These results provide useful data for the clinical application of the mPEG₅-OM19r-8.