Definition of Drosophila hemocyte subsets by cell-type specific antigens.

We analyzed the heterogeneity of Drosophila hemocytes on the basis of the expression of cell-type specific antigens. The antigens characterize distinct subsets which partially overlap with those defined by morphological criteria. On the basis of the expression or the lack of expression of blood cell antigens the following hemocyte populations have been defined: crystal cells, plasmatocytes, lamellocytes and precursor cells. The expression of the antigens and thus the different cell types are developmentally regulated. The hemocytes are arranged in four main compartments: the circulating blood cells, the sessile tissue, the lymph glands and the posterior hematopoietic tissue. Each hemocyte compartment has a specific and characteristic composition of the various cell types. The described markers represent the first successful attempt to define hemocyte lineages by immunological markers in Drosophila and help to define morphologically, functionally, spatially and developmentally distinct subsets of hemocytes

Transcriptomic analysis of Ascaris suum larvae during their hepatopulmonary migration

Common roundworms are important intestinal nematodes of man (Ascaris lumbricoides) and pig (Ascaris suum). During the first stages of the infection, the larvae of these parasites undergo a hepatopulmonary migration. This migration is likely to require tightly regulated transcriptional changes in the parasite. We explored this aspect in Ascaris suum by characterizing the transcription profiles of infective L3s from eggs, liver- and lung-L3s and intestinal L4s by next generation sequencing approach. When the most abundant transcripts per life stage were investigated, results showed that in the egg-L3s, transcripts associated with the regulation of translation and transcription, mainly ribosomal proteins, were most abundant. From the liver-L3s onwards, high transcription levels were seen for cuticle collagens, indicating the growth of the larvae during their migration. Interestingly, the type of highly expressed cuticle collagens in the intestinal L4s differed with those present in the liver- and lung-L3s. Apart from collagens, potentially important molecules for host-parasite interaction like C-type lectin-4 and Mucin-5 were in the top 5 of most abundant transcripts in the lung-L3. Unfortunately, a great number of transcripts that are specific for certain larval stages did not show any homology to other proteins within the NCBI database, suggesting that many biologically interesting molecules from this parasite are still to be investigated

Potential dietary feed additives with antibacterial effects and their impact on performance of weaned piglets : a meta-analysis

This meta-analysis evaluated the use of potential dietary feed additives (pDFA) with antibacterial effects and their impact on the perfomance of weaned piglets. Twenty-three peer-reviewed in vivo studies, comprising 50 trials, were identified between January 2010 and January 2017. The pDFA in these studies could be grouped in 5 classes: antimicrobial peptides, chitosan, lysozyme, medium chain fatty acids/triglycerides and plant extracts. Mixed-effect meta-analyses with type of pDFA as fixed effect were performed for the growth parameters 'average daily gain' (ADG) and 'feed conversion ratio' (FCR), which are the two most important and used economic performance parameters for farmers. For each class of pDFA, results of the meta-analysis showed significantly higher average daily gain in the group with pDFA compared to the negative control group, while no significant difference with the positive control group was observed. Furthermore, a positive effect on FCR was found, i.e. significantly less feed was needed to gain 1 kg of body weight in the group with pDFA compared to the negative control group. No significant differences with positive control groups were observed for each class of pDFA, except for plant extracts, where the FCR was also significantly reduced in the treatment group. These results suggest that pDFA could reduce the use of antimicrobials without significant negative effects on performance indicators

Structure-activity relationships of the antimicrobial peptide arasin 1 - and mode of action studies of the N terminal, proline-rich region

Arasin 1 is a 37 amino acid long proline-rich antimicrobial peptide isolated from the spider crab, Hyas araneus. In this work the active region of arasin 1 was identified through structure-activity studies using different peptide fragments derived from the arasin 1 sequence. The pharmacophore was found to be located in the proline/arginine-rich NH2 terminus of the peptide and the fragment arasin 1(1–23) was almost equally active to the full length peptide. Arasin 1 and its active fragment arasin 1(1–23) were shown to be non-toxic to human red blood cells and arasin 1(1–23) was able to bind chitin, a component of fungal cell walls and the crustacean shell. The mode of action of the fully active N-terminal arasin 1(1–23) was explored through killing kinetic and membrane permeabilization studies. At the minimal inhibitory concentration (MIC), arasin 1(1–23) was not bactericidal and had no membrane disruptive effect. In contrast, at concentrations of 5×MIC and above it was bactericidal and interfered with membrane integrity. We conclude that arasin 1(1–23) has a different mode of action than lytic peptides, like cecropin P1. Thus, we suggest a dual mode of action for arasin 1(1–23) involving membrane disruption at peptide concentrations above MIC, and an alternative mechanism of action, possibly involving intracellular targets, at MIC

Protein kinase C-dependent signaling controls the midgut epithelial barrier to malaria parasite infection in anopheline mosquitoes.

Anopheline mosquitoes are the primary vectors of parasites in the genus Plasmodium, the causative agents of malaria. Malaria parasites undergo a series of complex transformations upon ingestion by the mosquito host. During this process, the physical barrier of the midgut epithelium, along with innate immune defenses, functionally restrict parasite development. Although these defenses have been studied for some time, the regulatory factors that control them are poorly understood. The protein kinase C (PKC) gene family consists of serine/threonine kinases that serve as central signaling molecules and regulators of a broad spectrum of cellular processes including epithelial barrier function and immunity. Indeed, PKCs are highly conserved, ranging from 7 isoforms in Drosophila to 16 isoforms in mammals, yet none have been identified in mosquitoes. Despite conservation of the PKC gene family and their potential as targets for transmission-blocking strategies for malaria, no direct connections between PKCs, the mosquito immune response or epithelial barrier integrity are known. Here, we identify and characterize six PKC gene family members--PKCδ, PKCε, PKCζ, PKD, PKN, and an indeterminate conventional PKC--in Anopheles gambiae and Anopheles stephensi. Sequence and phylogenetic analyses of the anopheline PKCs support most subfamily assignments. All six PKCs are expressed in the midgut epithelia of A. gambiae and A. stephensi post-blood feeding, indicating availability for signaling in a tissue that is critical for malaria parasite development. Although inhibition of PKC enzymatic activity decreased NF-κB-regulated anti-microbial peptide expression in mosquito cells in vitro, PKC inhibition had no effect on expression of a panel of immune genes in the midgut epithelium in vivo. PKC inhibition did, however, significantly increase midgut barrier integrity and decrease development of P. falciparum oocysts in A. stephensi, suggesting that PKC-dependent signaling is a negative regulator of epithelial barrier function and a potential new target for transmission-blocking strategies

The Drosophila Inhibitor of Apoptosis (IAP) DIAP2 Is Dispensable for Cell Survival, Required for the Innate Immune Response to Gram-negative Bacterial Infection, and Can Be Negatively Regulated by the Reaper/Hid/Grim Family of IAP-binding Apoptosis Inducers

Many inhibitor of apoptosis (IAP) family proteins inhibit apoptosis. IAPs contain N-terminal baculovirus IAP repeat domains and a C-terminal RING ubiquitin ligase domain. Drosophila IAP DIAP1 is essential for the survival of many cells, protecting them from apoptosis by inhibiting active caspases. Apoptosis initiates when proteins such as Reaper, Hid, and Grim bind a surface groove in DIAP1 baculovirus IAP repeat domains via an N-terminal IAP-binding motif. This evolutionarily conserved interaction disrupts DIAP1-caspase interactions, unleashing apoptosis-inducing caspase activity. A second Drosophila IAP, DIAP2, also binds Rpr and Hid and inhibits apoptosis in multiple contexts when overexpressed. However, due to a lack of mutants, little is known about the normal functions of DIAP2. We report the generation of diap2 null mutants. These flies are viable and show no defects in developmental or stress-induced apoptosis. Instead, DIAP2 is required for the innate immune response to Gram-negative bacterial infection. DIAP2 promotes cytoplasmic cleavage and nuclear translocation of the NF-{kappa}B homolog Relish, and this requires the DIAP2 RING domain. Increasing the genetic dose of diap2 results in an increased immune response, whereas expression of Rpr or Hid results in down-regulation of DIAP2 protein levels. Together these observations suggest that DIAP2 can regulate immune signaling in a dose-dependent manner, and this can be regulated by IBM-containing proteins. Therefore, diap2 may identify a point of convergence between apoptosis and immune signaling pathways

A putative helical cytokine functioning in innate immune signalling in Drosophila melanogaster

In invertebrates and vertebrates, innate immunity is considered the first line of defense mechanism against non-self material. In vertebrates,cytokines play a critical role in innate immune signalling. To date, however, the existence of genes encoding for invertebrate helical cytokines hasbeen anticipated, but never demonstrated. Here, we report the first structural and functional evidence of a gene encoding for a putative helicalcytokine in Drosophila melanogaster. Functional experiments demonstrate that its expression, as well as that of the antimicrobial factors defensinand cecropin A1, is significantly increased after immune stimulation. These observations suggest the involvement of helical cytokines in the innateimmune response of invertebrates

Лекарственные средства, основанные на молекулярных структурах антимикробных пептидов, и терапевтические возможности при лечении инфекционных заболеваний респираторного тракта (часть 2)

На даний час у лікарській практиці вже продемонстрована ефективність застосування антимікробних пептидів у лікуванні місцевого інфекційного процесу, наприклад дериватів кателіцидину (оміганану), дефензиноміметика (брилацидину), α-спірального магаїніну (пексиганану), синтетичного протимікробного пептидоміметика (літиксару). Однак препарати цієї групи, які, можливо, будуть рекомендовані для лікування пневмоній, знаходяться на ранніх стадіях дослідження. Створення нових антимікробних пептидів із високим терапевтичним індексом (співвідношення бактерицидності і токсичності) та вирішення питання доставки їх в осередок ураження легені у хворих з інфекційними захворюваннями, у тому числі і респіраторного тракту, дозволить досягти ерадикації бактерій з мультимедикаментозною резистентністю. Даний напрямок дасть змогу відкрити постантибіотичну еру в широкій практичній діяльності терапевтів, педіатрів, хірургів та лікарів інтенсивної терапії. В настоящее время во врачебной практике продемонстрирована эффективность применения антимикробных пептидов при лечении местного инфекционного процесса, например дериватов кателицидина (омиганана), дефензиномиметика (брилацидина), α-спирального магаинина (пексиганана), синтетического противомикробного пептидомиметика (литиксара). Однако препараты данной группы, которые, возможно, будут рекомендованы для лечения пневмоний, находятся на ранних стадиях исследования. Создание новых антимикробных пептидов с высоким терапевтическим индексом (соотношения бактерицидности и токсичности) и решение вопроса доставки их в очаг поражения легкого позволит достичь эрадикации бактерий с мультилекарственной резистентностью у больных с инфекционными заболеваниями, в том числе и респираторного тракта. Данное направление позволит открыть постантибиотическую эру в широкой практической деятельности педиатров, интенсивистов, терапевтов и хирургов. Currently in medical practice, the effectiveness of the use of antimicrobial peptides, such as derivatives of cathelicidin (omiganan), defensin mimetic (brilacidin), α-helical magainin (pexiganan), synthetic antimicrobial peptide mimetic (lithixar), has been demonstrated in the treatment of the local infectious process. However, the drugs of this group, which may be recommended for the treatment of pneumonia, are in the early stages of studies. Creation of new antimicrobial peptides with a high therapeutic index (bactericidal activity and toxicity ratio) and solution of the problem of their delivery to the lesion focus in the lung will allow the eradication of bacteria with multi-drug resistance in patients with infectious diseases, including the infections of the respiratory tract. This approach will open the post-antibiotic era in the wide practical activities of pediatricians, intensive care specialists, therapeutists and surgeons