Gene expression and in silico analysis of snakehead murrel interleukin 8 and antimicrobial activity of C-terminal derived peptide WS12

Gonorrhea caused due to antimicrobial-resistant bacteria Neisseria gonorrhoeae treated using probiotic peptide

Neisseria gonorrhea is a sexually transmitted disease from gonorrhea that lacks treatment; despite the urgency, the absence of adequate drugs, lack of human correlates of protection, and inadequate animal models of infection have delayed progress toward the prevention of gonococcal infection. Lactobacillus crispatus is a lactic acid bacterium typically found in the human vaginal microbiota. Peptides from L. crispatus have shown a potential therapeutic option for targetting N. gonorrhea. Bioinformatics analysis is important for speeding up drug target acquisition, screening refinement, and evaluating adverse effects and drug resistance prediction. Therefore, this study identified an antimicrobial peptide from the bacteriocin immunity protein (BIP) of L. crispatus using the bioinformatics tool and Collection of Antimicrobial Peptide (CAMPR3). Based on the AMP score and highest ADMET properties, the peptide SM20 was chosen for docking analysis. SM20 was docked against multiple proteins from the genome of the AMR bacterium N. gonorrhea using an online tool; protein-peptide interactions were established and visualized using the PyMol visualizing tool. Molecular docking was carried out using the CABSdock tool, and multiple conformations were obtained against the membrane proteins of N. gonorrhoea. The peptide SM20 exhibited higher docking scores and ADMET properties. Therefore, SM20 could be further encapsulated with cellulose; it can be applied topically to the genital tract to target N. gonorrhea infection. The controlled release of the antimicrobial peptide from the gel can provide sustained delivery of the treatment, increasing its efficacy and reducing the risk of resistance development.

Identification, Expression and Antimicrobial Functional Analysis of Interleukin-8 (IL-8) in Response to Streptococcus iniae and Flavobacterium covae in Asian Seabass (Lates calcarifer Bloch, 1790)

In this research, the proinflammatory cytokine interleukin-8 (IL-8) was shown to play a key role in inflammatory responses in fish. This study involved the cloning of the gene that encodes IL-8 in Asian seabass (Lates calcarifer) as well as analyses of its expression and function in this fish. The expression levels of LcIL-8 indicated that it was broadly expressed in most analyzed tissues, with the most predominant expression in the whole blood 6 to 24 h after infection with S. iniae at concentrations of 105 colony-forming units (CFU)/fish (p < 0.05). After fish were immersed in F. covae, the LcIL-8 transcript was upregulated in the gills, liver and intestine, and the highest expression level was observed in the gills. However, LcIL-8 was downregulated in all the tested tissues at 48 and 96 h after infection with the two pathogenic strains, indicating that Lc-IL8 has a short half-life during the early immune responses to pathogens. Moreover, the MIC of the rLcIL-8 protein against S. iniae was 10.42 ± 3.61 µg/mL. Furthermore, functional analyses clearly demonstrated that 10 and 100 µg of the rLcIL-8 protein efficiently enhanced the phagocytic activity of Asian seabass phagocytes in vitro (p < 0.05). Additionally, in vivo injection of S. iniae following the rLcIL-8 protein indicated that 50 and 100 µg of rLc-IL-8 were highly effective in protecting fish from this pathogen (p < 0.001). The obtained results demonstrate that rLcIL-8 possesses a biological function in the defense against bacterial infections in Asian seabass.

CC and CXC chemokines in turbot (Scophthalmus maximus L.): Identification, evolutionary analyses, and expression profiling after Aeromonas salmonicida infection

Chemokines are a superfamily of structurally related cytokines, which exert essential roles in guiding cell migration in development, homeostasis, and immunity. CC and CXC chemokines are the two major subfamilies in teleost species. In this study, a total of seventeen CC and CXC chemokines, with inclusion of twelve CC and five CXC chemokines, were systematically identified from the turbot genome, making turbot the teleost harboring the least number of CC and CXC chemokines among all teleost species ever reported. Phylogeny, synteny, and genomic organization analyses were performed to annotate these genes, and multiple chemokine genes were identified in the turbot genome, due to the tandem duplications (CCL19 and CCL20), the whole genome duplications (CCL20, CCL25, and CXCL12), and the teleost-specific members (CCL34-36, CCL44, and CXCL18). In addition, chemokines were ubiquitously expressed in nine examined healthy tissues, with high expression levels observed in liver, gill, and spleen. Moreover, most chemokines were significantly differentially expressed in gill and spleen after Aeromonas salmonicida infection, and exhibited tissue-specific and time-dependent manner. Finally, protein-protein interaction network (PPI) analysis indicated that turbot chemokines interacted with a few immune-related genes such as interleukins, cathepsins, stats, and TLRs. These results should be valuable for comparative immunological studies and provide insights for further functional characterization of chemokines in teleost.

A hepatic antimicrobial peptide, hepcidin from Indian major carp, Catla catla: molecular identification and functional characterization

Background

Increase of antibiotic resistance in pathogenic microbes necessitated novel molecules for curing infection. Antimicrobial peptides (AMPs) are the gene-encoded evolutionarily conserved small molecules with therapeutic value. AMPs are considered as an alternative drug for conventional antibiotics. Hepcidin, the cysteine-rich antimicrobial peptide, is an important component in innate immune response. In this study, we identified and characterized hepcidin gene from the fish, Catla catla (Indian major carp) and termed it as Cc-Hep.

Results

Open reading frame of Cc-Hep consists of 261 base pair that encodes 87 amino acids. Cc-Hep is synthesized as a prepropeptide consisting of 24 amino acid signal peptide, 36 amino acid propeptide, and 26 amino acid mature peptide. Sequence analysis revealed that Cc-Hep shared sequence similarity with hepcidin from Sorsogona tuberculata. Phylogenetic analysis indicated that Cc-Hep was grouped with HAMP2 family. Structure analysis of mature Cc-Hep identified two antiparallel beta sheets stabilized by four disulphide bonds and a random coil. The mature peptide region of Cc-Hep has a charge of + 2, isoelectric value 8.23 and molecular weight 2.73 kDa.

Conclusion

Functional characterization predicted antibacterial, antioxidant, and anticancer potential of Cc-Hep, which can be explored in aquaculture or human health care.

Immunodetection of rainbow trout IL-8 cleaved-peptide: Tissue bioavailability and potential antibacterial activity in a bacterial infection context

Chemokines such as IL-8 are part of an important group of proinflammatory response molecules, as well as cell recruitment. However, it has been described in both higher vertebrates and fish that IL-8 has an additional functional role by acting as an antimicrobial effector, either directly or by cleavage of a peptide derived from its C-terminal end. Nevertheless, it is still unknown whether this fragment is released in the context of infection by bacterial pathogens and if it could be immunodetected in tissues of infected salmonids. Therefore, the objective of this research was to demonstrate that the C-terminal end of IL-8 from Oncorhynchus mykiss is cleaved, retaining its antibacterial properties, and that is detectable in tissues of infected rainbow trout. SDS-PAGE and mass spectrometry demonstrated the cleavage of a fragment of about 2 kDa when the recombinant IL-8 was subjected to acidic conditions. By chemical synthesis, it was possible to synthesize this fragment called omIL-8α_80-97 peptide, which has antibacterial activity against Gram-negative and Gram-positive bacteria at concentrations over 10 μM. Besides, by fluorescence microscopy, it was possible to locate the omIL-8α_80-97 peptide both on the cell surface and in the cytoplasm of the bacteria, as well as inside the monocyte/macrophage-like cell. Finally, by indirect ELISA, Western blot, and mass spectrometry, the presence of the fragment derived from the C-terminal end of IL-8 was detected in the spleen of trout infected with Piscirickettsia salmonis. The results reported in this work present the first evidence about the immunodetection of an antibacterial, and probably cell-penetrating peptide cleaved from the C-terminal end of IL-8 in monocyte/macrophage-like cell and tissue of infected rainbow trout.

Innate immune function of serine/threonine-protein kinase from Macrobrachium rosenbergii in response to host-pathogen interactions

The occurrences of multiple drug-resistant strains have been relentlessly increasing in recent years. The aquaculture industry has encountered major disease outbreaks and crucially affected by this situation. The usage of non-specific chemicals and antibiotics expedites the stimulation of resistant strains. Triggering the natural defense mechanism would provide an effective and safest way of protecting the host system. Hence, we have investigated the innate immune function of serine/threonine-protein kinase (STPK) in Macrobrachium rosenbergii (Mr). The in-silico protein analysis resulted in the identification of cationic antimicrobial peptide, MrSL-19, with interesting properties from STPK of M. rosenbergii. Antimicrobial assay, FACS and SEM analysis demonstrated that the peptide potentially inhibits Staphylococcus aureus by interacting with its membrane. The toxic study on MrSL-19 demonstrated that the peptide is not toxic against HEK293 cells as well as human erythrocytes. This investigation showed the significant innate immune property of an efficient cationic antimicrobial peptide, MrSL-19 of STPK from M. rosenbergii.

Peroxiredoxin of Arthrospira platensis derived short molecule YT12 influences antioxidant and anticancer activity

This study demonstrates both the antioxidant and anticancer potential of the novel short molecule YT12 derived from peroxiredoxin (Prx) of spirulina, Arthrospira platensis (Ap). ApPrx showed significant reduction in reactive oxygen species (ROS) against hydrogen peroxide (H₂ O₂ ) stress. The complementary DNA sequence of ApPrx contained 706 nucleotides and its coding region possessed 546 nucleotides between position 115 and 660. Real-time quantitative reverse transcription polymerase chain reaction analysis confirmed the messenger RNA expression of ApPrx due to H₂ O₂ exposure in spirulina cells at regular intervals, in which the highest expression was noticed on Day 20. Cytotoxicity assay was performed using human peripheral blood mononuclear cells, and revealed that at 10 μM, the YT12 did not exhibit any notable toxicity. Furthermore, ROS scavenging activity of YT12 was performed using DCF-DA assay, in which YT12 scavenged a significant amount of ROS at 25 μM in H₂ O₂ -treated blood leukocytes. The intracellular ROS in human colon adenocarcinoma cells (HT-29) was regulated by oxidative stress, where the YT12 scavenges ROS in HT-29 cells at 12.5 μM. Findings show that YT12 peptide has anticancer activity, when treated against HT-29 cells. Through the MTT assay, YT12 showed vital cytotoxicity against HT-29 cells. These finding suggested that YT12 is a potent antioxidant molecule which defends ROS against oxidative stress and plays a role in redox balance.

Characterization and Antimicrobial Activity of the Teleost Chemokine CXCL20b

Fish are a potential source of diverse organic compounds with a broad spectrum of biological activities. Many fish-derived antimicrobial peptides and proteins are key components of the fish innate immune system. They are also potential candidates for development of new antimicrobial agents. CXCL20b is a grass carp (Ctenopharyngodon idella) CXC chemokine strongly transcribed at the early stage of bacterial infections, for which the immune role had not been reported to date. In the present study, we found that CXCL20b is a cationic amphipathic protein that displays potent antimicrobial activity against both Gram-positive and Gram-negative bacteria. The results of DiOC₂(3) and atomic force microscopy (AFM) assays indicated that CXCL20b could induce bacterial membrane depolarization and disruption in a short time. By performing further structure-activity studies, we found that the antimicrobial activity of CXCL20b was mainly relative to the N-terminal random coil region. The central part of this cytokine representing β-sheet region was insoluble in water and the C-terminal α-helical region did not show an antimicrobial effect. The results presented in this article support the poorly understood function of CXCL20b, which fulfills an important role in bony fish antimicrobial immunity.

Biophysical approaches for exploring lipopeptide-lipid interactions

In recent years, lipopeptides (LPs) have attracted a lot of attention in the pharmaceutical industry due to their broad-spectrum of antimicrobial activity against a variety of pathogens and their unique mode of action. This class of compounds has enormous potential for application as an alternative to conventional antibiotics and for pest control. Understanding how LPs work from a structural and biophysical standpoint through investigating their interaction with cell membranes is crucial for the rational design of these biomolecules. Various analytical techniques have been developed for studying intramolecular interactions with high resolution. However, these tools have been barely exploited in lipopeptide-lipid interactions studies. These biophysical approaches would give precise insight on these interactions. Here, we reviewed these state-of-the-art analytical techniques. Knowledge at this level is indispensable for understanding LPs activity and particularly their potential specificity, which is relevant information for safe application. Additionally, the principle of each analytical technique is presented and the information acquired is discussed. The key challenges, such as the selection of the membrane model are also been briefly reviewed.

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A brief overview of topics to understand the generalities of lipopeptide (LP) science.

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Main analytical techniques used to reveal the interaction and the distorting effect of LP on artificial membranes.

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Guidelines for selecting of the most adequate membrane models for the given analytical technique.

Sub-lethal effect of synthetic pyrethroid pesticide on metabolic enzymes and protein profile of non-target Zebra fish, Danio rerio

Extensive application of pesticide in agricultural field affects the enzymatic activity of non-target animals, including fishes. In this study, the impact of sublethal concentration of fenvalerate on marker enzymes of freshwater Zebra fish was evaluated. Pesticide-induced stress can specifically affect non target fishes, through elevated level of reactive oxygen species which is responsible for biochemical, cell metabolism and physiological activities. The oxidative stress mediated by fenvalerate at sub lethal concentrations after 28 days of exposure of Zebra fish. Following 28 days of exposure of pesticide, catalase, superoxide dismutase, aspartate amino transferases, alanine amino transferase, alkaline phosphatase and acid phosphatase were assessed. Results revealed reduction of superoxide dismutase activity after 28 days of exposure in sub lethal concentration of fenvalerate in liver and gills. In liver, catalase activity was found to be less in fenvalerate exposed fish than control fish. In liver, increase of 75.75% aspartate amino transferase and 38% increase in alanine amino transferase in gills. SGPT activity was relatively higher than SGOT suggests more contribution of phyruvalate than oxaloacetate formation. Fenvalerate induced changes in acid phosphatase and alkaline phosphatase activity in the liver and gills of Zebra fish after four weeks of exposure. Fenvalerate induced expression of various stress proteins in gill, liver, followed by muscle. Some proteins lost its intensity due to fenvalerate toxicity. Result revealed that enzyme assays and SDS-PAGE analysis for protein subunits determination is relevant tool to monitor stress in freshwater ecosystem. The findings suggest that in monitoring fenvalerate toxicity programme, enzyme activities can be potent diagnostic tool for fenvalerate induced toxicity.

CK11, a Teleost Chemokine with a Potent Antimicrobial Activity

CK11 is a rainbow trout (Oncorhynchus mykiss) CC chemokine phylogenetically related to both mammalian CCL27 and CCL28 chemokines, strongly transcribed in skin and gills in homeostasis, for which an immune role had not been reported to date. In the current study, we have demonstrated that CK11 is not chemotactic for unstimulated leukocyte populations from central immune organs or mucosal tissues but instead exerts a potent antimicrobial activity against a wide range of rainbow trout pathogens. Our results show that CK11 strongly inhibits the growth of different rainbow trout Gram-positive and Gram-negative bacteria, namely Lactococcus garvieae, Aeromonas salmonicida subsp. salmonicida, and Yersinia ruckeri and a parasitic ciliate Ichthyophthirius multifiliis Similarly to mammalian chemokines and antimicrobial peptides, CK11 exerted its antimicrobial activity, rapidly inducing membrane permeability in the target pathogens. Further transcriptional studies confirmed the regulation of CK11 transcription in response to exposure to some of these pathogens in specific conditions. Altogether, our studies related to phylogenetic relations, tissue distribution, and biological activity point to CK11 as a potential common ancestor of mammalian CCL27 and CCL28. To our knowledge, this study constitutes the first report of a fish chemokine with antimicrobial activity, thus establishing a novel role for teleost chemokines in antimicrobial immunity that supports an evolutionary relationship between chemokines and antimicrobial peptides.

A mini review on immune role of chemokines and its receptors in snakehead murrel Channa striatus

Chemokines are ubiquitous cytokine molecules involved in migration of cells during inflammation and normal physiological processes. Though the study on chemokines in mammalian species like humans have been extensively studied, characterization of chemokines in teleost fishes is still in the early stage. The present review provides an overview of chemokines and its receptors in a teleost fish, Channa striatus. C. striatus is an air breathing freshwater carnivore, which has enormous economic importance. This species is affected by an oomycete fungus, Aphanomyces invadans and a Gram negative bacteria Aeromonas hydrophila is known to cause secondary infection. These pathogens impose immune changes in the host organism, which in turn mounts several immune responses. Of these, the role of cytokines in the immune response is immense, due to their involvement in several activities of inflammation such as cell trafficking to the site of inflammation and antigen presentation. Given that importance, chemokines in fishes do have significant role in the immunological and other physiological functions of the organism, hence there is a need to understand the characteristics, activities and performace of these small molecules in details.