Spermicidal efficacy of VRP, a synthetic cationic antimicrobial peptide, inducing apoptosis and membrane disruption

Role of intracranial bone marrow mesenchymal stem cells in stroke recovery: A focus on post-stroke inflammation and mitochondrial transfer

Stem cell therapy has become a hot research topic in the medical field in recent years, with enormous potential for treating a variety of diseases. In particular, bone marrow mesenchymal stem cells (BMSCs) have wide-ranging applications in the treatment of ischemic stroke, autoimmune diseases, tissue repair, and difficult-to-treat diseases. BMSCs can differentiate into multiple cell types and exhibit strong immunomodulatory properties. Although BMSCs can regulate the inflammatory response activated after stroke, the mechanism by which BMSCs regulate inflammation remains unclear and requires further study. Recently, stem cell therapy has emerged as a potentially effective approach for enhancing the recovery process following an ischemic stroke. For example, by regulating post-stroke inflammation and by transferring mitochondria to exert therapeutic effects. Therefore, this article reviews the therapeutic effects of intracranial BMSCs in regulating post-stroke inflammation and mitochondrial transfer in the treatment of stroke, providing a basis for further research.

Antimicrobial peptides: features, applications and the potential use against covid-19

BACKGROUND

Antimicrobial peptides (AMPs) are a diverse class of molecules that represent a vital part of innate immunity. AMPs are evolutionarily conserved molecules that exhibit structural and functional diversity. They provide a possible solution to the antibiotic-resistance crisis.

MAIN TEXT

These small cationic peptides can target bacteria, fungi, and viruses, as well as cancer cells. Their unique action mechanisms, rare antibiotic-resistant variants, broad-spectrum activity, low toxicity, and high specificity encourage pharmaceutical industries to conduct clinical trials to develop them as therapeutic drugs. The rapid development of computer-assisted strategies accelerated the identification of AMPs. The Antimicrobial Peptide Database (APD) so far contains 3324 AMPs from different sources. In addition to their applications in different fields, some AMPs demonstrated the potential to combat COVID-19, and hinder viral infectivity in diverse ways.

CONCLUSIONS

This review provides a brief history of AMPs and their features, including classification, evolution, sources and mechanisms of action, biosynthesis pathway, and identification techniques. Furthermore, their different applications, challenges to clinical applications, and their potential use against COVID-19 are presented.

Antitumor Effects of Scorpion Peptide Smp43 through Mitochondrial Dysfunction and Membrane Disruption on Hepatocellular Carcinoma

Smp43, a cationic antimicrobial peptide identified from the venom gland of the Egyptian scorpion Scorpio maurus palmatus, shows cytotoxicity toward hepatoma cell line HepG2 by membrane disruption. However, its underlying detailed mechanisms still remain to be further clarified. In the present study, we evaluated the cellular internalization of Smp43 and explored its effects on cell viability, cell cycle, apoptosis, autophagy, necrosis, and factor expression related to these cellular processes in human HepG2. Smp43 was found to suppress the growth of HepG2, Huh7, and human primary hepatocellular carcinoma cells while showing low toxicity to normal LO2 cells. Furthermore, Smp43 could interact with the cell membrane and be internalized into HepG2 cells via endocytosis and pore formation, which caused a ROS production increase, mitochondrial membrane potential decline, cytoskeleton disorganization, dysregulation of cyclin expression, mitochondrial apoptotic pathway activation, and alteration of MAPK as well as PI3K/Akt/mTOR signaling pathways. Finally, Smp43 showed effective antitumor protection in the HepG2 xenograft mice model. Overall, these findings indicate that Smp43 significantly exerts antitumor effects via induction of apoptosis, autophagy, necrosis, and cell cycle arrest due to its induction of mitochondrial dysfunction and membrane disruption. This discovery will extend the antitumor mechanisms of antimicrobial peptides and contribute to the development of antitumor agents against hepatocellular carcinoma.

A review emphasizing on utility of heptad repeat sequence as a tool to design pharmacologically safe peptide-based antibiotics

Extensive usage of antibiotics has created an unprecedented scenario of the rapid emergence of many drug-resistant bacteria, which has become an alarming public health concern around the globe. Search for better alternatives that are as efficacious as antibiotics led to the discovery of antimicrobial peptides (AMPs). These small cationic amphiphilic peptides have emerged as a promising option as antimicrobial agents, owing to their multifaceted implications against varied pathogens. Recent years have witnessed tremendous growth in research on AMPs resulting in them being tested in clinical trials of which six got approved for topical application. The relatively less successful outcome has been attributed to the poor cell selectivity shown by most of the naturally occurring AMPs. This drawback needs to be circumvented by identifying strategies to design safe and effective peptides. In the present review, we have emphasized the importance of heptad repeat sequence (leucine and/or phenylalanine zipper motif) as a tool that has shown great promise in remodeling the toxic AMPs to safe antimicrobial agents.

Small Molecule Interferences in Resazurin and MTT-Based Metabolic Assays in the Absence of Cells

In vitro assays (such as resazurin and MTT) provide an opportunity to determine the cytotoxicity of novel therapeutics before moving forward with expensive and resource-intensive in vivo studies. A concern with using these assays, however, is the production of false responses in the presence of particular chemical functionalities. To better understand this phenomenon, 19 small molecules at 6 concentrations (1 μM-100 mM) were tested in the presence of resazurin and MTT reagents to highlight potential interfering species. Through the use of absorbance measurements (using well-plate assays and UV-vis spectroscopy) with parallel MS analysis, we have shown that significant conversion of the assay reagents readily occurs in the presence of many tested interfering species without the need for any cellular activity. The most attributable sources of interference seem to arise from the presence of thiol and carboxylic acid moieties. Interestingly, the detectable interferences were more prevalent and larger in the presence of MTT (19 species with some deviations >3000%) compared to resazurin (16 species with largest deviation of ∼150%). Additionally, those deviations in the presence of resazurin were only substantial at high concentrations, while MTT showed deviations across the tested concentrations. This comprehensive study gives insight into chemical functional groups (thiols, amines, amides, carboxylic acids) that may interfere with resazurin and MTT assays in the absence of metabolic activity and indicates that proper control studies must be performed to obtain accurate data from these in vitro assays.

Localization of MIF-II on mammalian spermatozoa: A study revealing its structure, function and motility inhibitory pathway

Motility of spermatozoa is a crucial factor for determining semen quality. Here we report motility inhibitory factor (MIF-II) from goat epididymal plasma, revealing its structure, function, localization and motility inhibitory pathway. Structural characterization with MALDI revealed novelty of this protein while circular dichroism data confirmed its alpha helical nature. Higher dilutions of MIF-II antibody increased cauda sperm motility and induced immature/immotile caput sperm motility as tested microscopically. Higher number of sperm cells and lower dilutions of antibody induced agglutination in cauda sperm showing surface localization. Indirect immuno-fluorescence showed MIF-II localization throughout the caput sperm surface which relocated more towards acrosomal region with maturation. ELISA assay revealed gradual increase and decrease in concentration of MIF-II in epididymal plasma and plasma membrane respectively from caput to cauda. Signaling cascade that leads to sperm motility inhibition elevates nitric oxide levels through cAMP dependent pathway. MIF-II treatment doesn't alter sperm surface morphology. Expression pattern of MIF-II during epididymal maturation goes hand-in-hand with gaining motility potential as well as dormancy of spermatozoa before ejaculation. Both MIF-II and its antibody inhibit fertilization in-vitro thus expected to open new gateway for future male infertility and contraceptive development research.

A CCR5 antagonist-based HIV entry inhibitor exhibited potent spermicidal activity: Potential application for contraception and prevention of HIV sexual transmission

B07 is a small-molecule CCR5 antagonist-based HIV-1 entry inhibitor that is being developed as an anti-HIV microbicide for preventing sexual transmission of HIV. Here we evaluated its spermicidal and contraceptive potential, including sperm motility, plasma membrane integrity, and contraceptive efficacy tested in rabbits. We found that B07 inhibited sperm motility and movement patterns in a concentration- and time-dependent manner. Within 30 min, B07 induced sperm immobilization with the minimum 100% effective concentration and median effective concentration of 640.0 and 64.4 μg/mL, respectively. The hypo-osmotic swelling test showed that plasma membranes of B07-treated sperms exhibited slight disruption, as verified by electron micrographs. In both B07 gel and N-9 gel groups, not a single implantation site or embryo was observed based on the contraceptive efficacy test in rabbits, indicating that B07 could effectively block the potential of sperm to reach and/or fertilize oocytes. The safety profile of B07 in vivo was evaluated by use of an optimized rabbit vaginal irritation test. While the pathological scores of the N-9 gel group was 14.67 ± 1.21, those of the blank control and B07 gel groups were 2.17 ± 0.76 and 4.00 ± 0.89, respectively, which were within the clinically acceptable range (<8). The proportion of inflammatory cells and CD45⁺ cells in the cervicovaginal lavages of the B07 gel group showed no significant change compared to those of the control group. Therefore, our results confirmed that B07 exhibited significant spermicidal and contraceptive effects, suggesting its potential for development as a microbicidal spermicide for contraception and prevention of HIV sexual transmission.

A novel epididymal quiescence factor inhibits sperm motility by modulating NOS activity and intracellular NO-cGMP pathway

Mature and potentially motile spermatozoa stored in cauda epididymis in an inactive state for approximately 30 days; however, during ejaculation they regain motility. To understand the actual molecular mechanism of the sperm quiescence during caudal stay, a proteinaceous quiescence factor (QF) has been purified from caprine epididymal plasma to apparent homogeneity. In the present study complete purification, detailed characterization as well as mechanistic pathway of QF has been described. QF is purified to 215-fold with 45% activity recovery. It is a 59 kDa monomeric protein with isoelectric point 5.8 and optimally active at pH 7.5. Circular dichroism spectroscopy and atomic force microscopy study confirm its α-helical secondary structure and globular tertiary conformation. QF is a thermo-stable protein as higher temperature does not alter its helical structure. N-terminal amino acid sequencing and MALDI analysis of QF did not find 100% similarity with any available protein of the database, proved its novelty. QF at 2 μM dose inhibits sperm progressive forward motility within 10 min. This motility inhibitory activity of QF is mediated by reducing NOS enzyme activity and subsequently decreasing the intracellular NO and cGMP concentration. It does not modulate intracellular Ca⁺⁺ and cAMP concentration. QF has no adverse effect on DNA integrity and morphology of spermatozoa. Motility inhibitory action of QF is reversible. Thus, the role of QF in maintaining energy saving quiescence state of mature cauda spermatozoa and its reactive nitrogen species reducing activity may lead to a new direction for storage of spermatozoa and idiopathic male infertility.