Antimicrobial Peptide against Mycobacterium Tuberculosis That Activates Autophagy Is an Effective Treatment for Tuberculosis

Coastal natural products: a review applied to antimycobacterial activity

Despite the many advances in drug research, natural products are still being explored as a promising source for discovering new bioactive compounds to treat global diseases such as tuberculosis. However, there is a lack of studies and information about coastal natural products, which thrive in the transitional environment between two different ecosystems and produce unique secondary metabolites. Mangroves, estuaries, and mudflats make up areas for coastal species and have shown promising results in antituberculosis research, some of them are present in hotspot areas. This review focuses on research conducted in coastal environments and explores the reasons why these natural products tend to outperform non-coastal ones against the causative agent of tuberculosis, Mycobacterium tuberculosis.

Antimicrobial Peptides as Immunomodulators and Antimycobacterial Agents to Combat Mycobacterium tuberculosis: a Critical Review

Tuberculosis (TB) is a devastating disease foisting a significantly high morbidity, prepotent in low- and middle-income developing countries. Evolution of drug resistance among Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, has made the TB treatment more complicated. The protracted nature of present TB treatment, persistent and tolerant Mtb populations, interaction with antiretroviral therapy and existing toxicity concerned with conventional anti-TB drugs are the four major challenges inflicted with emergence of drug-resistant mycobacterial strains, and the standard medications are unable to combat these strains. These factors emphasize an exigency to develop new drugs to overcome these barriers in current TB therapy. With this regard, antimycobacterial peptides derived from various sources such as human cells, bacterial sources, mycobacteriophages, fungal, plant and animal sources could be considered as antituberculosis leads as most of these peptides are associated with dual advantages of having both bactericidal activity towards Mtb as well as immuno-regulatory property. Some of the peptides possess the additional advantage of interacting synergistically with antituberculosis medications too, thereby increasing their efficiency, underscoring the vigour of antimicrobial peptides (AMPs) as best possible alternative therapeutic candidates or adjuvants in TB treatment. Albeit the beneficiary features of these peptides, few obstacles allied with them like cytotoxicity and proteolytic degradation are matter of concerns too. In this review, we have focused on structural hallmarks, targeting mechanisms and specific structural aspects contributing to antimycobacterial activity and discovered natural and synthetic antimycobacterial peptides along with their sources, anti-TB, immuno-regulatory properties, merits and demerits and possible delivery methods of AMPs.

Rifampicin drug resistance and host immunity in tuberculosis: more than meets the eye

Tuberculosis (TB) is the leading cause of death due to an infectious agent, with more than 1.5 million deaths attributed to TB annually worldwide. The global dissemination of drug resistance across Mycobacterium tuberculosis (Mtb) strains, causative of TB, resulted in an estimated 450 000 cases of drug-resistant (DR) TB in 2021. Dysregulated immune responses have been observed in patients with multidrug resistant (MDR) TB, but the effects of drug resistance acquisition and impact on host immunity remain obscure. In this review, we compile studies that span aspects of altered host-pathogen interactions and highlight research that explores how drug resistance and immunity might intersect. Understanding the immune processes differentially induced during DR TB would aid the development of rational therapeutics and vaccines for patients with MDR TB.

The Use of Particulate Systems for Tuberculosis Prophylaxis and Treatment: Opportunities and Challenges

The use of particles to develop vaccines and treatments for a wide variety of diseases has increased, and their success has been demonstrated in preclinical investigations. Accurately targeting cells and minimizing doses and adverse side effects, while inducing an adequate biological response, are important advantages that particulate systems offer. The most used particulate systems are liposomes and their derivatives, immunostimulatory complexes, virus-like particles, and organic or inorganic nano- and microparticles. Most of these systems have been proven using therapeutic or prophylactic approaches to control tuberculosis, one of the most important infectious diseases worldwide. This article reviews the progress and current state of the use of particles for the administration of TB vaccines and treatments in vitro and in vivo, with a special emphasis on polymeric particles. In addition, we discuss the challenges and benefits of using these particulate systems to provide researchers with an overview of the most promising strategies in current preclinical trials, offering a perspective on their progress to clinical trials.

Antimicrobial peptides as drugs with double response against Mycobacterium tuberculosis coinfections in lung cancer

Tuberculosis and lung cancer are, in many cases, correlated diseases that can be confused because they have similar symptoms. Many meta-analyses have proven that there is a greater chance of developing lung cancer in patients who have active pulmonary tuberculosis. It is, therefore, important to monitor the patient for a long time after recovery and search for combined therapies that can treat both diseases, as well as face the great problem of drug resistance. Peptides are molecules derived from the breakdown of proteins, and the membranolytic class is already being studied. It has been proposed that these molecules destabilize cellular homeostasis, performing a dual antimicrobial and anticancer function and offering several possibilities of adaptation for adequate delivery and action. In this review, we focus on two important reason for the use of multifunctional peptides or peptides, namely the double activity and no harmful effects on humans. We review some of the main antimicrobial and anti-inflammatory bioactive peptides and highlight four that have anti-tuberculosis and anti-cancer activity, which may contribute to obtaining drugs with this dual functionality.

Mycobacterium tuberculosis cell-wall and antimicrobial peptides: a mission impossible?

Mycobacterium tuberculosis (Mtb) is one of the most important infectious agents worldwide and causes more than 1.5 million deaths annually. To make matters worse, the drug resistance among Mtb strains has risen substantially in the last few decades. Nowadays, it is not uncommon to find patients infected with Mtb strains that are virtually resistant to all antibiotics, which has led to the urgent search for new molecules and therapies. Over previous decades, several studies have demonstrated the efficiency of antimicrobial peptides to eliminate even multidrug-resistant bacteria, making them outstanding candidates to counterattack this growing health problem. Nevertheless, the complexity of the Mtb cell wall makes us wonder whether antimicrobial peptides can effectively kill this persistent Mycobacterium. In the present review, we explore the complexity of the Mtb cell wall and analyze the effectiveness of antimicrobial peptides to eliminate the bacilli.

ApoE Mimetic Peptide COG1410 Exhibits Strong Additive Interaction with Antibiotics Against Mycobacterium smegmatis

Background

Drug-resistant tuberculosis (TB) is an emerging threat to public health worldwide. Antimicrobial peptide (AMP) is a promising solution to solve the antimicrobial resistance crisis. The apolipoprotein E mimetic peptide COG1410 has been confirmed to simultaneously have neuroprotective, anti-inflammatory, and antibacterial activity. However, whether it is effective to inhibit growth of mycobacteria has not been investigated yet.

Methods

The peptide COG1410 was synthesized with conventional solid-phase peptide synthesis and qualified by HPLC and mass spectrometry. Micro-dilution method was used to determine the minimal inhibitory concentration. A time-kill assay was used to determine the bactericidal dynamics of antimicrobial peptide and relative antibiotics. Static biofilm formation was conducted in 24-well plate and the biofilm was separated from planktonic cells and collected. The mechanism of action of COG1410 was explored by TEM observation and ATP leak assay. The localization of COG1410 was observed by confocal laser scan microscopy. The drug-drug interaction was determined by a checkerboard assay.

Results

COG1410 was a potent bactericidal agent against M. smegmatis in vitro and within the macrophages with MIC 16 μg/mL, but invalid against M. abscess and M. tuberculosis. A time-kill assay showed that COG1410 killed M. smegmatis as potent as clarithromycin, but faster than LL-37, another short synthetic cationic peptide. 1× MIC COG1410 almost reduced 90% biofilm formation of M. smegmatis. Additionally, COG1410 was able to penetrate the cell membrane of macrophage and inhibit intracellular M. smegmatis growth. TEM observation and ATP leak assay found that COG1410 disrupted cell membrane and caused release of cell contents. Confocal fluorescence microscopy showed that FITC-COG1410 aggregated around cell membrane instead of entering the cytoplasm. Although COG1410 had relative high cytotoxicity, it exhibited strong additive interaction with regular anti-TB antibiotics, which reduced the working concentration of COG1410 and expanding safety window. After 30 passages, there was no induced drug resistance for COG1410.

Conclusion

COG1410 was a novel and potent AMP against M. smegmatis by disrupting the integrity of cell membrane.

Embedded-AMP: A Multi-Thread Computational Method for the Systematic Identification of Antimicrobial Peptides Embedded in Proteome Sequences

Antimicrobial peptides (AMPs) have gained the attention of the research community for being an alternative to conventional antimicrobials to fight antibiotic resistance and for displaying other pharmacologically relevant activities, such as cell penetration, autophagy induction, immunomodulation, among others. The identification of AMPs had been accomplished by combining computational and experimental approaches and have been mostly restricted to self-contained peptides despite accumulated evidence indicating AMPs may be found embedded within proteins, the functions of which are not necessarily associated with antimicrobials. To address this limitation, we propose a machine-learning (ML)-based pipeline to identify AMPs that are embedded in proteomes. Our method performs an in-silico digestion of every protein in the proteome to generate unique k-mers of different lengths, computes a set of molecular descriptors for each k-mer, and performs an antimicrobial activity prediction. To show the efficiency of the method we used the shrimp proteome, and the pipeline analyzed all k-mers between 10 and 60 amino acids in length to predict all AMPs in less than 20 min. As an application example we predicted AMPs in different rodents (common cuy, common rat, and naked mole rat) with different reported longevities and found a relation between species longevity and the number of predicted AMPs. The analysis shows as the longevity of the species is higher, the number of predicted AMPs is also higher. The pipeline is available as a web service.

In Vitro Antimycobacterial Activity of Human Lactoferrin-Derived Peptide, D-hLF 1-11, against Susceptible and Drug-Resistant Mycobacterium tuberculosis and Its Synergistic Effect with Rifampicin

Tuberculosis is a highly contagious disease caused by the Mycobacterium tuberculosis complex (MTBC). Although TB is treatable, multidrug-resistant, extensively drug-resistant, and totally drug-resistant forms of M. tuberculosis have become a new life-threatening concern. New anti-TB drugs that are capable of curing these drug-resistant strains are urgently needed. The purpose of this study is to determine the antimycobacterial activity of D-enantiomer human lactoferricin 1-11 (D-hLF 1-11) against mycobacteria in vitro using a 3-(4,5-dimethylthiazol-2-yl)-2,5-dephenyltetrazolium bromide colorimetric assay, resazurin microplate assay, and microscopic observation drug susceptibility assay. Three previously described antimicrobial peptides, protegrin-1, AK 15-6, and melittin, with potent anti-TB activity, were included in this study. The findings suggest that D-hLF 1-11 can inhibit the growth of M. tuberculosis with a minimum inhibitory concentration of 100−200 µg/mL in susceptible, isoniazid (INH)-monoresistant, rifampicin (RF)-monoresistant, and MDR strains. The peptide can also inhibit some nontuberculous mycobacteria and other MTBC in similar concentrations. The antibiofilm activity of D-hLF 1-11 against the biofilm-forming M. abscessus was determined by crystal violet staining, and no significant difference is observed between the treated and untreated biofilm control. The checkerboard assay was subsequently carried out with M. tuberculosis H37Rv and the results indicate that D-hLF 1-11 displays an additive effect when combined with INH and a synergistic effect when combined with RF, with fractional inhibitory concentration indices of 0.730 and 0.312, respectively. The red blood cell hemolytic assay was initially applied for the toxicity determination of D-hLF 1-11, and negligible hemolysis (<1%) was observed, despite a concentration of up to 4 mg/mL being evaluated. Overall, D-hLF 1-11 has potential as a novel antimycobacterial agent for the future treatment of drug-sensitive and drug-resistant M. tuberculosis infections.

Taming the Devil: Antimicrobial Peptides for Safer TB Therapeutics

Tuberculosis (TB) is a highly contagious infection with extensive mortality and morbidity. The rise of TB-superbugs (drug-resistant strains) with the increase of their resistance to conventional antibiotics has prompted a further search for new anti-mycobacterial agents. It is difficult to breach the barriers around TB bacteria, including mycolic cell wall, granuloma, biofilm and mucus, by conventional antibiotics in a short span of time. Hence, there is an essential need for molecules with an unconventional mode of action and structure that can efficiently break the barriers around mycobacterium. Antimicrobial peptides (AMP) are essential components of innate immunity having cationic and amphipathic characteristics. Lines of evidence show that AMPs have good myco-bactericidal and antibiofilm activity against normal as well as antibiotic-resistant TB bacteria. These peptides have shown direct killing of bacteria by membrane lysis and indirect killing by activation of innate immune response in host cells by interacting with the component of the bacterial membrane and intracellular targets through diverse mechanisms. Despite a good anti-mycobacterial activity, some undesirable characteristics are also associated with AMP, including hemolysis, cytotoxicity, susceptibility to proteolysis and poor pharmacokinetic profile, and hence only a few clinical studies have been conducted with these biomolecules. The design of new combinatorial therapies, including AMPs and particulate drug delivery systems, could be new potential alternatives to conventional antibiotics to fight MDR- and XDRTB. This review outlined the array of AMP roles in TB therapy, possible mechanisms of actions, activities, and current advances in pragmatic strategies to improve challenges accompanying the delivery of AMP for tuberculosis therapeutics.

Role of Antimicrobial Peptides in Treatment and Prevention of Mycobacterium Tuberculosis: A Review

Tuberculosis (TB) is one of the leading cause of death worldwide, and the world is fighting with this global health emergency from the past 25 year. The current clinical interventions for the management of TB face a number of inherent challenges which includes low patient compliance due to the long therapy regimen, and emerging antimicrobial resistance. Therefore, there is an unmet need of new anti-TB therapeutic agent with enhanced safety profile, which can reduce the duration of therapy, enhanced bioavailability and efficacy against drug resistant forms of TB. Bacteriocins or anti microbial peptides (AMPs) occurring in microbes, human beings and other life forms have been investigated as host defense peptides. Structurally AMPs are short and ionized and play crucial role in innate immunity of host. Some AMPs can kill microbial infections directly while others function indirectly by altering the host defense mechanisms. Amidst rising issue of antibiotic resistance, AMPs are being tested in clinical research as potential antibiotics and novel therapeutics to fight against infections and non-infectious diseases. Studies have also highlighted the ability of AMPs to act against the bacteria spreading tuberculosis. The present review provides information on antimicrobial peptides, highlights their biological role, classification and mode of action in treatment and prevention of tuberculosis. It further mentions the prospects and challenges of developing peptides for their therapeutic applications against mycobacterium tuberculosis.

Antimicrobial Peptides as an Alternative for the Eradication of Bacterial Biofilms of Multi-Drug Resistant Bacteria

Bacterial resistance is an emergency public health problem worldwide, compounded by the ability of bacteria to form biofilms, mainly in seriously ill hospitalized patients. The World Health Organization has published a list of priority bacteria that should be studied and, in turn, has encouraged the development of new drugs. Herein, we explain the importance of studying new molecules such as antimicrobial peptides (AMPs) with potential against multi-drug resistant (MDR) and extensively drug-resistant (XDR) bacteria and focus on the inhibition of biofilm formation. This review describes the main causes of antimicrobial resistance and biofilm formation, as well as the main and potential AMP applications against these bacteria. Our results suggest that the new biomacromolecules to be discovered and studied should focus on this group of dangerous and highly infectious bacteria. Alternative molecules such as AMPs could contribute to eradicating biofilm proliferation by MDR/XDR bacteria; this is a challenging undertaking with promising prospects.

Challenge in the Discovery of New Drugs: Antimicrobial Peptides against WHO-List of Critical and High-Priority Bacteria

Bacterial resistance has intensified in recent years due to the uncontrolled use of conventional drugs, and new bacterial strains with multiple resistance have been reported. This problem may be solved by using antimicrobial peptides (AMPs), which fulfill their bactericidal activity without developing much bacterial resistance. The rapid interaction between AMPs and the bacterial cell membrane means that the bacteria cannot easily develop resistance mechanisms. In addition, various drugs for clinical use have lost their effect as a conventional treatment; however, the synergistic effect of AMPs with these drugs would help to reactivate and enhance antimicrobial activity. Their efficiency against multi-resistant and extensively resistant bacteria has positioned them as promising molecules to replace or improve conventional drugs. In this review, we examined the importance of antimicrobial peptides and their successful activity against critical and high-priority bacteria published in the WHO list.

Antimicrobial Peptides as Potential Anti-Tubercular Leads: A Concise Review

Despite being considered a public health emergency for the last 25 years, tuberculosis (TB) is still one of the deadliest infectious diseases, responsible for over a million deaths every year. The length and toxicity of available treatments and the increasing emergence of multidrug-resistant strains of Mycobacterium tuberculosis renders standard regimens increasingly inefficient and emphasizes the urgency to develop new approaches that are not only cost- and time-effective but also less toxic. Antimicrobial peptides (AMP) are small cationic and amphipathic molecules that play a vital role in the host immune system by acting as a first barrier against invading pathogens. The broad spectrum of properties that peptides possess make them one of the best possible alternatives for a new “post-antibiotic” era. In this context, research into AMP as potential anti-tubercular agents has been driven by the increasing danger revolving around the emergence of extremely-resistant strains, the innate resistance that mycobacteria possess and the low compliance of patients towards the toxic anti-TB treatments. In this review, we will focus on AMP from various sources, such as animal, non-animal and synthetic, with reported inhibitory activity towards Mycobacterium tuberculosis.