Bombyx mori Cecropin D could trigger cancer cell apoptosis by interacting with mitochondrial cardiolipin

An updated proteomic analysis of Drosophila haemolymph after bacterial infection

Using an in-depth Mass Spectrometry-based proteomics approach, we provide a comprehensive characterization of the hemolymphatic proteome of adult flies upon bacterial infection. We detected and quantified changes in abundance of several known immune regulators and effectors, including multiple antimicrobial peptides, peptidoglycan-binding proteins and serine proteases. Comparison to previously published transcriptomic analyses reveals a partial overlap with our dataset, indicating that many proteins released into the haemolymph upon infection may not be regulated at the transcript level. Among them, we identify a set of muscle-derived proteins released into the haemolymph upon infection. Finally, our analysis reveals that infection induces major changes in the abundance of proteins associated with mitochondrial respiration. This study uncovers a large number of previously undescribed proteins potentially involved in the immune response.

Cathelicidin-BF: A Potent Antimicrobial Peptide Leveraging Charge and Phospholipid Recruitment against Multidrug-Resistant Clinical Bacterial Isolates

Cathelicidin-BF (CatBF) is a LL-37 homologous antimicrobial peptide (AMP) isolated from Bungarus fasciatus with an exceptional portfolio of antimicrobial, antiviral, antifungal, and anticancer activities. Contrary to many AMPs, it showed a good pharmacological profile with a half-life of at least 1 h in serum and efficacy against bacterial infections in mice. To evaluate its potential against resistant nosocomial infections, we assessed its activity against 81 clinically relevant resistant bacterial isolates. CatBF exhibited minimum inhibitory concentrations (MICs) as low as 0.5 μM against carbapenem-resistant Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli. Its wide-ranging activity, unaffected by resistance mechanisms or Gram phenotype, prompted us to investigate its molecular mode of action. NMR spectroscopy, paramagnetic probes, and molecular dynamics (MD) simulations were employed to define its structure, penetration depth, and orientation in various membrane models, including micelles, bicelles, oriented bilayers, and vesicles. We found that CatBF's potent activity relies on its strong charge, allowing membrane neutralization at low peptide/lipid ratios and selective recruitment of charged phospholipids. At higher concentrations, a change in peptide orientation reveals membrane invagination and the formation of transient pores possibly leading to bacterial death. Our findings highlight the potential of CatBF as a model for developing resistance-independent agents to combat multidrug-resistant (MDR) bacterial infections.

The Mechanisms and Implications of Cardiolipin in the Regulation of Cell Death

Cardiolipin (CL), an exclusive phospholipid, is predominantly found within the confines of the inner mitochondrial membrane, playing an indispensable role in the sustenance of mitochondrial operations and the regulation of cellular energy metabolism. The influence of CL on the pathways of cell death has garnered significant interest in recent scholarly discourse. This review delves into the multifaceted roles of CL across various modes of cell demise, encompassing apoptosis, autophagy, pyroptosis, ferroptosis, necrosis, and necroptosis. The discussion extends to the examination of CL's implications in a clinical context, particularly concerning cardiovascular maladies, neurological degeneration, and oncological conditions. Through an integrative analysis of contemporary research findings, the aim is to elucidate the intricate dynamics of CL's involvement in cell death phenomena. While acknowledging the inherent limitations and the hurdles faced by current research endeavors, the therapeutic potential of CL as a modulator of cell death pathways is nonetheless encouraging. Forthcoming investigations must surmount these obstacles, thereby uncovering the nuanced mechanisms and impacts of CL in the realm of cell death and associated pathologies, potentially paving the way for innovative clinical intervention strategies.

Biological Activity of Peptide Fraction Derived from Hermetia illucens L. (Diptera: Stratiomyidae) Larvae Haemolymph on Gastric Cancer Cells

Gastric cancer (GC) is one of the leading causes of cancer-related mortality worldwide, characterised by poor prognosis and limited responsiveness to chemotherapy. There is a need for new and more effective anticancer agents. Antimicrobial peptides (AMPs) represent a promising class of biomolecules for this purpose. Naturally occurring in the innate immune system, these peptides can also exert cytotoxic effects against cancer cells, earning them the designation of "anticancer peptides" (ACPs). They have the potential to be a viable support for current chemotherapy schedules due to their selectivity against cancer cells and minor propensity to induce chemoresistance in cells. Insects are an excellent source of AMPs. Among them, due to its ability to thrive in hostile and microorganism-rich environments, we isolated a peptide fraction from Hermetia illucens L. (Diptera: Stratiomyidae) haemolymph to evaluate a possible anticancer activity. We tested Peptide Fractions (PFs) against AGS and KATO III gastric cancer cell lines. Data obtained indicated that PFs, especially those resulting from Escherichia coli and Micrococcus flavus infection (to boost immune response), were able to inhibit tumour cell growth by inducing apoptosis or cell cycle arrest in a cell line-specific manner. These results support further investigation into the use of antimicrobial peptides produced from insects as possible anticancer agents.

Revisiting edible insects as sources of therapeutics and drug delivery systems for cancer therapy

Cancer has been medicine's most formidable foe for long, and the rising incidence of the disease globally has made effective cancer therapy a significant challenge. Drug discovery is targeted at identifying efficacious compounds with minimal side effects and developments in nanotechnology and immunotherapy have shown promise in the fight against this complicated illness. Since ancient times, insects and insect-derived products have played a significant role in traditional medicine across several communities worldwide. The aim of this study was to inspect the traditional use of edible insects in various cultures and to explore their modern use in cancer therapy. Edible insects are sources of nutrients and a variety of beneficial substances with anticancer and immunomodulatory potential. Recently, insect derived bioactive-components have also been used as nanoparticles either in combination with chemotherapeutics or as a nano-cargo for the enhanced delivery of chemotherapeutic drugs due to their high biocompatibility, low bio-toxicity, and their antioxidant and anticancer effects. The crude extracts of different edible insects and their active components such as sericin, cecropin, solenopsin, melittin, antimicrobial peptides and fibroin produce anti-cancer and immunomodulatory effects by various mechanisms which have been discussed in this review.

Application Value of Antimicrobial Peptides in Gastrointestinal Tumors

Gastrointestinal cancer is a common clinical malignant tumor disease that seriously endangers human health and lacks effective treatment methods. As part of the innate immune defense of many organisms, antimicrobial peptides not only have broad-spectrum antibacterial activity but also can specifically kill tumor cells. The positive charge of antimicrobial peptides under neutral conditions determines their high selectivity to tumor cells. In addition, antimicrobial peptides also have unique anticancer mechanisms, such as inducing apoptosis, autophagy, cell cycle arrest, membrane destruction, and inhibition of metastasis, which highlights the low drug resistance and high specificity of antimicrobial peptides. In this review, we summarize the related studies on antimicrobial peptides in the treatment of digestive tract tumors, mainly oral cancer, esophageal cancer, gastric cancer, liver cancer, pancreatic cancer, and colorectal cancer. This paper describes the therapeutic advantages of antimicrobial peptides due to their unique anticancer mechanisms. The length, net charge, and secondary structure of antimicrobial peptides can be modified by design or modification to further enhance their anticancer effects. In summary, as an emerging cancer treatment drug, antimicrobial peptides need to be further studied to realize their application in gastrointestinal cancer diseases.

Characterization of the Antimicrobial Activities of Trichoplusia ni Cecropin A as a High-Potency Therapeutic against Colistin-Resistant Escherichia coli

The spread of colistin-resistant bacteria is a serious threat to public health. As an alternative to traditional antibiotics, antimicrobial peptides (AMPs) show promise against multidrug resistance. In this study, we investigated the activity of the insect AMP Tricoplusia ni cecropin A (T. ni cecropin) against colistin-resistant bacteria. T. ni cecropin exhibited significant antibacterial and antibiofilm activities against colistin-resistant Escherichia coli (ColREC) with low cytotoxicity against mammalian cells in vitro. Results of permeabilization of the ColREC outer membrane as monitored through 1-N-phenylnaphthylamine uptake, scanning electron microscopy, lipopolysaccharide (LPS) neutralization, and LPS-binding interaction revealed that T. ni cecropin manifested antibacterial activity by targeting the outer membrane of E. coli with strong interaction with LPS. T. ni cecropin specifically targeted toll-like receptor 4 (TLR4) and showed anti-inflammatory activities with a significant reduction of inflammatory cytokines in macrophages stimulated with either LPS or ColREC via blockade of TLR4-mediated inflammatory signaling. Moreover, T. ni cecropin exhibited anti-septic effects in an LPS-induced endotoxemia mouse model, confirming its LPS-neutralizing activity, immunosuppressive effect, and recovery of organ damage in vivo. These findings demonstrate that T. ni cecropin exerts strong antimicrobial activities against ColREC and could serve as a foundation for the development of AMP therapeutics.

Unraveling the Role of Antimicrobial Peptides in Insects

Antimicrobial peptides (AMPs) are short, mainly positively charged, amphipathic molecules. AMPs are important effectors of the immune response in insects with a broad spectrum of antibacterial, antifungal, and antiparasitic activity. In addition to these well-known roles, AMPs exhibit many other, often unobvious, functions in the host. They support insects in the elimination of viral infections. AMPs participate in the regulation of brain-controlled processes, e.g., sleep and non-associative learning. By influencing neuronal health, communication, and activity, they can affect the functioning of the insect nervous system. Expansion of the AMP repertoire and loss of their specificity is connected with the aging process and lifespan of insects. Moreover, AMPs take part in maintaining gut homeostasis, regulating the number of endosymbionts as well as reducing the number of foreign microbiota. In turn, the presence of AMPs in insect venom prevents the spread of infection in social insects, where the prey may be a source of pathogens.

The Mechanism of Action of SAAP-148 Antimicrobial Peptide as Studied with NMR and Molecular Dynamics Simulations

Background: SAAP-148 is an antimicrobial peptide derived from LL-37. It exhibits excellent activity against drug-resistant bacteria and biofilms while resisting degradation in physiological conditions. Despite its optimal pharmacological properties, its mechanism of action at the molecular level has not been explored. Methods: The structural properties of SAAP-148 and its interaction with phospholipid membranes mimicking mammalian and bacterial cells were studied using liquid and solid-state NMR spectroscopy as well as molecular dynamics simulations. Results: SAAP-148 is partially structured in solution and stabilizes its helical conformation when interacting with DPC micelles. The orientation of the helix within the micelles was defined by paramagnetic relaxation enhancements and found similar to that obtained using solid-state NMR, where the tilt and pitch angles were determined based on 15N chemical shift in oriented models of bacterial membranes (POPE/POPG). Molecular dynamic simulations revealed that SAAP-148 approaches the bacterial membrane by forming salt bridges between lysine and arginine residues and lipid phosphate groups while interacting minimally with mammalian models containing POPC and cholesterol. Conclusions: SAAP-148 stabilizes its helical fold onto bacterial-like membranes, placing its helix axis almost perpendicular to the surface normal, thus probably acting by a carpet-like mechanism on the bacterial membrane rather than forming well-defined pores.