Production Of Antimicrobial Peptides Research Articles

Production, characterization, and application of phage-derived PK34 recombinant anti-microbial peptide.

PK34 is a D29 mycobacteriophage-derived anti-microbial peptide (AMP) with anti-Mycobacterium tuberculosis activity. It is expected to become an auxiliary drug for the treatment of M. tuberculosis infection, or as a template for the development of anti-M. tuberculosis drugs. The focus of this paper is to obtain recombinant PK34 by a novel method of prokaryotic expression and purification by affinity chromatography. The minimum inhibitory concentration (MIC) of recombinant PK34 was better than that of synthetic PK34 as measured by the microplate-based Alamar Blue assay (MABA). In order to further compare the different anti-bacterial effects of PK34 obtained by the two methods on M. tuberculosis, the bacterial changes after drug incubation were observed at the microscopic level by transmission electron microscopy (TEM). In order to apply PK34 to clinical treatment earlier in the future, this paper tested the maximum non-toxic concentration of recombinant PK34 to the two most studied immune cells, RAW264.7 and THP-1, through cytotoxicity experiments. The maximum non-toxic concentration was the same as the MIC of recombinant PK34 to M. tuberculosis H37Rv, and both were 12.5μg/mL. The monoclonal antibodies against PK34 and their hybridoma cell lines were prepared using recombinant PK34 as the antigen. Next, we obtained the gene sequence of the monoclonal antibody, which was prepared for the basic research of PK34 in M. tuberculosis treatment. In addition, the possible molecular docking mode between PK34 and trehalose-6,6-dimycolate (TDM) was predicted by AI simulation. To sum up, this paper provides a new idea for the birth of more new AMPs of the same type as PK34 in the future. KEY POINTS: • Design and prepare a novel recombinant PK34 anti-microbial peptide. • Recombinant PK34 has higher purity and anti-bacterial activity than synthetic PK34. • The monoclonal antibody against recombinant PK34 was prepared and sequenced.

Metabolites enhance innate resistance to human Mycobacterium tuberculosis infection.

To determine the mechanisms that mediate resistance to Mycobacterium tuberculosis (M. tuberculosis) infection in household contacts (HHCs) of patients with tuberculosis (TB), we followed 452 latent TB infection-negative (LTBI-) HHCs for 2 years. Those who remained LTBI- throughout the study were identified as nonconverters. At baseline, nonconverters had a higher percentage of CD14+ and CD3-CD56+CD27+CCR7+ memory-like natural killer (NK) cells. Using a whole-transcriptome and metabolomic approach, we identified deoxycorticosterone acetate as a metabolite with elevated concentrations in the plasma of nonconverters, and further studies showed that this metabolite enhanced glycolytic ATP flux in macrophages and restricted M. tuberculosis growth by enhancing antimicrobial peptide production through the expression of the surface receptor sialic acid binding Ig-like lectin-14. Another metabolite, 4-hydroxypyridine, from the plasma of nonconverters significantly enhanced the expansion of memory-like NK cells. Our findings demonstrate that increased levels of specific metabolites can regulate innate resistance against M. tuberculosis infection in HHCs of patients with TB who never develop LTBI or active TB.

Antifungal Activity of Avocado Seed Recombinant GASA/Snakin PaSn.

The avocado fruit (Persea americana) has become a significant fruit in the human diet for its nutritional properties. However, the seed is a source of bioactive molecules and has been poorly utilized. Previously, we reported that the PaSn gene is expressed in the avocado seeds, a cysteine-rich antimicrobial peptide (GASA/Snakin), and demonstrated its antibacterial activity. In this work, we report the recombinant production of PaSn in the Escherichia coli system and evaluate its antifungal activity against plant and human pathogen fungi. The recombinant peptide showed antifungal activity at 200 μg/mL against phytopathogens Colletotrichum gloeosporioides and Fusarium oxysporum and human pathogens Candida albicans and C. glabrata. Our results demonstrate the usefulness of a prokaryotic expression system for avocado antimicrobial peptide production. In conclusion, the snakin PaSn could be helpful in the control of postharvest avocado and other fruits' fungal diseases and human fungal pathogens.

Ornithine decarboxylase supports ILC3 responses in infectious and autoimmune colitis through positive regulation of IL-22 transcription

Group 3 innate lymphoid cells (ILC3s) are RORγT+ lymphocytes that are predominately enriched in mucosal tissues and produce IL-22 and IL-17A. They are the innate counterparts of Th17 cells. While Th17 lymphocytes utilize unique metabolic pathways in their differentiation program, it is unknown whether ILC3s make similar metabolic adaptations. We employed single-cell RNA sequencing and metabolomic profiling of intestinal ILC subsets to identify an enrichment of polyamine biosynthesis in ILC3s, converging on the rate-limiting enzyme ornithine decarboxylase (ODC1). In vitro and invivo studies demonstrated that exogenous supplementation with the polyamine putrescine or its biosynthetic substrate, ornithine, enhanced ILC3 production of IL-22. Conditional deletion of ODC1 in ILC3s impaired mouse antibacterial defense against Citrobacter rodentium infection, which was associated with a decrease in anti-microbial peptide production by the intestinal epithelium. Furthermore, in a model of anti-CD40 colitis, deficiency of ODC1 in ILC3s markedly reduced the production of IL-22 and severity of inflammatory colitis. We conclude that ILC3-intrinsic polyamine biosynthesis facilitates efficient defense against enteric pathogens as well as exacerbates autoimmune colitis, thus representing an attractive target to modulate ILC3 function in intestinal disease.

Extracellular production of Ulp1403-621 in leaky E. coli and its application in antimicrobial peptide production.

Small ubiquitin-like modifier (SUMO) tag is widely used to promote soluble expression of exogenous proteins, which can then be cleaved by ubiquitin-like protease 1 (Ulp1) to obtain interested protein. But the application of Ulp1 in large-scale recombinant protein production is limited by complicated purification procedures and high cost. In this study, we describe an efficient and simple method of extracellular production of Ulp1403-621 using a leaky Escherichia coli BL21(DE3), engineered by deleting the peptidoglycan-associated outer membrane lipoprotein (pal) gene. Ulp1403-621 was successfully leaked into extracellular supernatant by the BL21(DE3)-Δpal strain after IPTG induction. The addition of 1% glycine increased the extracellular production of Ulp1403-621 approximately fourfold. Moreover, extracellular Ulp1403-621 without purification had high activities for cleaving SUMO fusion proteins, and antimicrobial peptide pBD2 obtained after cleavage can inhibit the growth of Staphylococcus aureus. The specific activity of extracellular Ulp1403-621 containing 1mM EDTA and 8mM DTT reached 2.0 × 106 U/L. Another commonly used protease, human rhinovirus 3C protease, was also successfully secreted by leaky E. coli strains. In conclusion, extracellular production of tool enzymes is an attractive way for producing large-scale active recombinant proteins at a lower cost for pharmaceutical, industrial, and biotechnological applications. KEY POINTS: • First report of extracellular production of Ulp1403-621 in leaky Escherichia coli BL21(DE3) strain. • One percent glycine addition into cultivation medium increased the extracellular production of Ulp1403-621 approximately fourfold. • The specific activity of extracellular Ulp1403-621 produced in this study reached 2.0 × 106 U/L.

Ayurvedic formulations Guduchi and Madhuyashti triggers JNK signaling mediated immune response and adversely affects Huntington phenotype

BackgroundHuntington’s disease manifests due to abnormal CAG trinucleotide expansion, in the first exon of the Huntingtin gene and disease progression involves genetic, immune, and environmental components. The pathogenesis is characterized by the formation of Inclusion Bodies, disruption of neuronal circuitry, cellular machinery, and apoptosis, resulting in gradual and progressive loss of neuronal cells, ultimately leading to nervous system dysfunction. Thus, the present study was conducted to assess the effect of two Ayurvedic formulations, Guduchi and Madhuyashti, on Huntington’s phenotype, using Drosophila as a model system.MethodThe Huntington phenotype was ectopically induced in the Drosophila eye using the UAS-GAL4 binary system and the effect of the two Ayurvedic formulations were assessed by feeding the progenies on them. Degeneration was observed microscopically and Real Time-PCR was done to assay the alterations in the different transcripts of the innate immune pathways and JNK signaling pathway. Immunostaining was performed to assay different gene expression patterns.ResultThe present study shows that Guduchi and Madhuyashti, endowed with immunomodulatory and intellect promoting properties, aggravates polyQ mediated neurodegeneration. We provide evidence that these formulations enhance JNK signaling by activating the MAP 3 K, dTAK1, which regulates the expression of Drosophila homologue for JNK. Sustained, rather than a transient expression of JNK leads to excessive production of Anti-Microbial Peptides without involving the canonical transcription factors of the Toll or IMD pathways, NF-κB. Enhanced JNK expression also increases caspase levels, with a concomitant reduction in cell proliferation, which may further contribute to increased degeneration.ConclusionThis is a report linking the functional relevance of Guduchi and Madhuyashti with molecular pathways, which can be important for understanding their use in therapeutic applications and holds promise for mechanistic insight into the mammalian counterpart.

S100 Proteins as Novel Therapeutic Targets in Psoriasis and Other Autoimmune Diseases

Psoriasis is one of the most common inflammatory skin diseases affecting about 1–3% of the population. One of the characteristic abnormalities in psoriasis is the excessive production of antimicrobial peptides and proteins, which play an essential role in the pathogenesis of the disease. Antimicrobial peptides and proteins can be expressed differently in normal and diseased skin, reflecting their usefulness as diagnostic biomarkers. Moreover, due to their very important functions in innate immunity, members of host defense peptides and proteins are currently considered to be promising new therapeutic targets for many inflammatory diseases. Koebnerisin (S100A15) belongs to an S100 family of antimicrobial proteins, which constitute the multigenetic group of calcium-binding proteins involved in ion-dependent cellular functions and regulation of immune mechanisms. S100A15 was first discovered to be overexpressed in ‘koebnerized’ psoriatic skin, indicating its involvement in the disease phenotype and the same promising potential as a new therapeutic target. This review describes the involvement of antimicrobial peptides and proteins in inflammatory diseases’ development and therapy. The discussion focuses on S100 proteins, especially koebnerisin, which may be involved in the underlying mechanism of the Köebner phenomenon in psoriasis, as well as other immune-mediated inflammatory diseases described in the last decade.

Enteropathy endoscopic findings in small intestine in patients with severe COVID-19

Background and aim: Small intestine study is a challenge in the field of clinical research. However, capsule endoscopy is a safe and minimally invasive alternative. During the COVID-19 pandemic, this endoscopic procedure acquires added value. Although SARS-CoV-2 has mainly respiratory manifestations, gastrointestinal symptoms are observed in 30% of cases. ACE-2 used by SARS-CoV-2 to infect cells is highly expressed in the brush border of enterocytes. This enzyme transports essential amino acids in the small intestine and regulates intestinal inflammation through antimicrobial peptides production. Here we describe the endoscopic changes in the mucosa of the small intestine secondary to severe SARS-CoV-2 infection in patients with and without gastrointestinal symptoms. Methods: We performed a prospective and observational study in hospitalized patients with severe COVID-19 disease. Capsule endoscopy and detection of SARS-CoV-2 RNA in feces were performed in each participant. Each capsule was reviewed separately by two trained endoscopists. Results: Twenty individuals were enrolled. Diarrhea was observed in 78% of participants. In 45% of capsule endoscopy studies, changes characterized by shortening of villi, atrophy or denuded areas accompanied by red spots or patches, hyperemia or edema were found. Individuals showing these changes in the intestinal mucosa were positive for SARS-CoV-2 in stool. Conclusions: Here we provide evidence of macroscopic changes along the small intestine in COVID-19 patients. We proposed the term of COVID-19 enteropathy to denote involvement of the mucosa and in the villi of the small intestine in SARS-CoV-2 infected individuals. Longitudinal follow-up will be valuable for a better understanding of COVID-19 enteropathy.

An odorant binding protein is involved in counteracting detection-avoidance and Toll-pathway innate immunity

IntroductionOdorant-binding proteins (OBPs) are a class of small molecular weight soluble proteins that exist as expanded gene families in all insects, acting as ligand carriers mediating olfaction and other physiological processes. During fungal infection, a subset of insect OBPs were shown to be differentially expressed. ObjectivesWe tested whether the altered expression of insect OBPs during pathogenic infection plays a role in behavioral or immune interactions between insect hosts and their pathogens. MethodsA wide range of techniques including RNAi-directed knockdown, heterologous protein expression, electrophysiological/behavioral analyses, transcriptomics, gut microbiome analyses, coupled with tandem mass spectrometry ion monitoring, were used to characterize the function of a locust OBP in host behavioral and immune responses. ResultsThe entomopathogenic fungus Metarhizium anisopliae produces the volatile compound phenylethyl alcohol (PEA) that causes behavioral avoidance in locusts. This is mediated by the locust odorant binding protein 11 (LmOBP11). Expression of LmOBP11 is induced by M. anisopliae infection and PEA treatment. LmOBP11 participates in insect detection of the fungal-produced PEA and avoidance of PEA-contaminated food, but the upregulation of LmOBP11 upon M. anisopliae infection negatively affects the insect immune responses to ultimately benefit successful mycosis by the pathogen. RNAi knockdown of LmOBP11 increases the production of antimicrobial peptides and enhances locust resistance to M. anisopliae infection, while reducing host antennal electrophysiological responses to PEA and locust avoidance of PEA treated food. Also, transcriptomic and gut microbiome analyses reveal microbiome dysbiosis and changes in host genes involved in behavior and immunity. These results are consistent with the elevated expression of LmOBP11 leading to enhanced volatile detection and suppression of immune responses. ConclusionThese findings suggest a crosstalk between olfaction and immunity, indicating manipulation of host OBPs as a novel target exploited by fungal pathogens to alter immune activation and thus promote the successful infection of the host.

Bacillus subtilis programs the differentiation of intestinal secretory lineages to inhibit Salmonella infection.

The role of intestinal microbiota on fate determination of intestinal epithelial cells has not been extensively examined. In this study, we explore the effect of Bacillus subtilis on programmed intestinal epithelial differentiation. We find that B.subtilis stimulates the differentiation of intestinal secretory cells. Moreover, B.subtilis inhibits the Notch pathway to reduce the expression of hairy and enhancer of split 1, thereby shifting intestinal stem cell differentiation toward a secretory cell fate. Moreover, we demonstrate that the programming effect of B.subtilis on intestinal differentiation is Toll-like receptor 2 pathway dependent. B.subtilis is associated with increased numbers of Paneth and goblet cells in the intestine. This results in the production of antimicrobial peptides to protect the intestinal mucosal barrier against Salmonella typhimurium. This study demonstrates that B.subtilis contributes to the differentiation of secretory cells by affecting Notch pathway signaling to maintain the intestinal barrier.

Recombinant antimicrobial peptide production

Chemie Ingenieur TechnikVolume 94, Issue 9 p. 1258-1258 Poster Recombinant antimicrobial peptide production L. Michel, Corresponding Author L. Michel lisa.michel@haw-hamburg.de University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanyCorrespondence: L. Michel (lisa.michel@haw-hamburg.de), University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanySearch for more papers by this authorA. Thoma, A. Thoma University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanySearch for more papers by this authorM. J. Saeidi, M. J. Saeidi University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanySearch for more papers by this authorG. Cornelissen, G. Cornelissen University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanySearch for more papers by this author L. Michel, Corresponding Author L. Michel lisa.michel@haw-hamburg.de University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanyCorrespondence: L. Michel (lisa.michel@haw-hamburg.de), University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanySearch for more papers by this authorA. Thoma, A. Thoma University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanySearch for more papers by this authorM. J. Saeidi, M. J. Saeidi University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanySearch for more papers by this authorG. Cornelissen, G. Cornelissen University of Applied Sciences, Biotechnology, Ulmenliet 20, 21033 Hamburg, GermanySearch for more papers by this author First published: 25 August 2022 https://doi.org/10.1002/cite.202255045AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume94, Issue9Special Issue: (Bio)Process Engineering – a Key to Sustainable Development: ProcessNet and DECHEMA-BioTechNet Jahrestagungen 2022 together with 13th ESBES SymposiumSeptember 2022Pages 1258-1258 RelatedInformation

Maximizing Recovery of Paenibacillin, a Bacterially Produced Lantibiotic, Using Continuous Foam Separation from Bioreactors.

Industrial production of paenibacillin, and similar rare antimicrobial peptides, is hampered by low productivity of the producing microorganisms and lack of efficient methods to recover these peptides from fermentor or bioreactor end products. Preliminary data showed that paenibacillin was preferentially partitioned in foam accumulated during growth of the producer, Paenibacillus polymyxa, in aerated liquid media. This research was initiated to improve the production and recovery of paenibacillin in bioreactors by maximizing partitioning of this antimicrobial agent in the collected foam. This was completed through harvesting foam continuously during paenibacillin production, using modified bioreactor, and optimizing bioreaction conditions through response surface methodology (RSM). During initial screening, the following factors were tested using 400 mL inoculated media in 2 L bioreactors: medium (tryptic soy broth, TSB, with or without added yeast extract), airflow (0 or 0.8 L/min; LPM), stir speed (300 or 500 revolution/min; RPM), incubation temperature (30 or 36 °C), and incubation time (16 or 24 h). Results showed that airflow, time, and stir speed had significant effects (p < 0.05) on paenibacillin recovery in the collected collapsed foam (foamate). These factors were varied together to follow the path of steepest assent to maximize paenibacillin concentration. Once the local maximum was found, RSM was completed with a central composite design to fine-tune the bioreaction parameters. The optimization experiments proved that the significant parameters and their optimal conditions for paenibacillin concentration in the foam were: incubation at 30 °C for 23 h with airflow of 0.95 LPM, and agitation speed of 450 RPM. These conditions increased paenibacillin concentration, predicted by RSM, from 16 µg/mL in bioreaction without foam collection to 743 µg/mL collected in foamate. The optimized conditions also almost doubled the yield of paenibacillin measured in the foam collected from a bioreaction run (12,674 µg/400 mL bioreaction) when compared to that obtained from a run without foam collection (6400 µg/400 mL bioreaction). Results of this study could improve the feasibility of commercial production and downstream processing of paenibacillin and similar novel antimicrobial peptides. Availability of such peptides will eventually help in protecting perishable products against pathogenic and spoilage bacteria.

756 Skin wounding alters the gut microbiome by inducing antimicrobial peptide and mucin production from intestinal epithelia

Intestinal and skin microflora can influence several systemic health behaviors. In this study, we hypothesized that skin and gut tissue microbiota are linked, and that skin health can control the gut microbiota. To test this, we compared intestinal responses in control mice to co-housed littermates with full-thickness incisions on back skin or K14Cre-targeted expression of HYAL-1 in the epidermis. The latter mice represent a skin-specific model of the hyaluronidase activity produced by wounding but without a systemic inflammatory or stress response.

Antiviral Effect of hBD-3 and LL-37 during Human Primary Keratinocyte Infection with West Nile Virus.

West Nile virus (WNV) is an emerging flavivirus transmitted through mosquito bites and responsible for a wide range of clinical manifestations. Following their inoculation within the skin, flaviviruses replicate in keratinocytes of the epidermis, inducing an innate immune response including the production of antimicrobial peptides (AMPs). Among them, the cathelicidin LL-37 and the human beta-defensin (hBD)-3 are known for their antimicrobial and immunomodulatory properties. We assessed their role during WNV infection of human primary keratinocytes. LL-37 reduced the viral load in the supernatant of infected keratinocytes and of the titer of a viral inoculum incubated in the presence of the peptide, suggesting a direct antiviral effect of this AMP. Conversely, WNV replication was not inhibited by hBD-3. The two peptides then demonstrated immunomodulatory properties whether in the context of keratinocyte stimulation by poly(I:C) or infection by WNV, but not alone. This study demonstrates the immunostimulatory properties of these two skin AMPs at the initial site of WNV replication and the ability of LL-37 to directly inactivate West Nile viral infectious particles. The results provide new information on the multiple functions of these two peptides and underline the potential of AMPs as new antiviral strategies in the fight against flaviviral infections.

Advances in the use of plants as potential biofactories in the production of antimicrobial peptides

AbstractPlants subjected to phytopathogens can synthesize peptides with antimicrobial properties. In the last few decades, there has been an impressive increase in the prospection of antimicrobial peptides (AMPs) due to continuous demand for the development and manufacture of new antibiotics. In this setting, plants have attracted scientific and pharmaceutical interest and are considered promising AMPs biofactories. However, it is a great challenge to explore the diversity of actions needed to obtain a pharmaceutical product with AMPs derived from plants on a large scale. This review presents the last 5 years main findings on plants used as AMPs biofactories. Published works in this period were reviewed, and perspectives are presented on recombinant AMPs for drug production that appear in a plant‐based system, as well as products available on the market.

Redclaw crayfish (Cherax quadricarinatus) responds to Vibrio parahaemolyticus infection by activating toll and immune deficiency signaling pathways and transcription of associated immune response genes

In invertebrates, several genes controlled by the Toll and immunodeficiency (IMD) signaling cascade are altered during microbial infection. However, little is known about the expression patterns of innate immune response genes in red-clawed crayfish (Cherax quadricarinatus). In the present study, the transcription of five genes was assessed in C. quadricarinatus challenged with Vibrio parahaemolyticus (V. parahaemolyticus). The expression of Relish, Toll-like receptor (TLR), tumor necrosis factor receptor-related factor 6 (TRAF6), Akirin, and IMD in different tissues and at different time points after infection were assessed. In addition, the Relish gene was amplified, the protein conformation of the Relish gene was predicted, and gene expression changes associated with antimicrobial peptide production in C. quadricarinatus were analyzed using RNA interference (RNAi). During V. parahaemolyticus infection, the transcripts of the above five genes were significantly increased in the hepatopancreas of C. quadricarinatus (P < 0.05). In contrast, TLR was significantly downregulated in muscle tissue at the initial stage of infection (P < 0.05); TRAF6 and IMD were significantly down-regulated throughout infection (P < 0.05); Akirin transcripts had the lowest abundance at 24 h post-infection; Relish, IMD and Akirin genes were significantly up-regulated in gill tissue at the early stage of infection (P < 0.05); only TRAF6 was significantly up-regulated at 6, 24 and 48 h after infection. The Relish gene of C. quadricarinatus is closely related to the Exopalaemon carinicauda. When the Relish gene was knocked down by RNAi, the V. parahaemolyticus challenge showed that the mortality rate of the RANi group was significantly higher than that of the NC group; pathological sections showed that the hepatopancreatic tissue damage was the most severe 12 h after the interference; and the interference significantly inhibited IRF4, NF-κB, ALF, laccase, SOD1, and lectin genes. Therefore, it can be hypothesized that the Toll and IMD pathways are activated in C. quadricarinatus in response to bacterial infection and that genes associated with these pathways are differentially transcribed in different tissues. This study provides insights into the Toll and IMD signaling pathways and the spatiotemporal expression of key genes regulating bacterial infection resistance in C. quadricarinatus.

RGD-Labeled Hemocytes With High Migration Activity Display a Potential Immunomodulatory Role in the Pacific Oyster Crassostrea gigas.

Immunocyte migration to infection sites is important for host cellular defense, but the main types of migrating hemocytes and their mechanisms against pathogen invasions are unclear in invertebrates. In the present study, a population of hemocytes in the Pacific oyster Crassostrea gigas labeled with a fluorescein isothiocyanate (FITC)-conjugated Arg-Gly-Asp (RGD)-containing peptide was sorted. RGD+ hemocytes were characterized by a smaller cell size and cytoplasmic-nucleo ratio, fewer cytoplasmic granules, and higher levels of myeloperoxidase, reactive oxygen species, and intracellular free calcium concentration. RGD+ hemocytes exhibited a high level of migration activity, which was further induced after V. splendidus infection. Transcriptome analysis revealed that RGD+ hemocytes highly expressed a series of migration-related genes, which together with migration-promoting genes were significantly upregulated after V. splendidus infection. The neuroendocrine system was also proven to regulate the migration activity of RGD+ hemocytes, especially with the excitatory neuroendocrine factor dopamine, which promoted migration activity as confirmed by receptor blocking assays. Meanwhile, RGD+ hemocytes could highly express immunomodulatory factor interleukin (IL)-17s and their receptor genes, which was positively related to the production of antimicrobial peptides in whole hemocytes after V. splendidus infection. Collectively, this study identified a specific hemocyte population, i.e., RGD+ hemocytes, that shows high migration activity in response to pathogen infection and exerts a potential immunomodulatory role by highly expressing IL-17s that might enhance the hemocytes’ antimicrobial peptide production in oysters.

IL-17 and IL-17-producing cells in protection versus pathology.

IL-17 cytokine family members have diverse biological functions, promoting protective immunity against many pathogens but also driving inflammatory pathology during infection and autoimmunity. IL-17A and IL-17F are produced by CD4+ and CD8+ T cells, γδ T cells, and various innate immune cell populations in response to IL-1β and IL-23, and they mediate protective immunity against fungi and bacteria by promoting neutrophil recruitment, antimicrobial peptide production and enhanced barrier function. IL-17-driven inflammation is normally controlled by regulatory T cells and the anti-inflammatory cytokines IL-10, TGFβ and IL-35. However, if dysregulated, IL-17 responses can promote immunopathology in the context of infection or autoimmunity. Moreover, IL-17 has been implicated in the pathogenesis of many other disorders with an inflammatory basis, including cardiovascular and neurological diseases. Consequently, the IL-17 pathway is now a key drug target in many autoimmune and chronic inflammatory disorders; therapeutic monoclonal antibodies targeting IL-17A, both IL-17A and IL-17F, the IL-17 receptor, or IL-23 are highly effective in some of these diseases. However, new approaches are needed to specifically regulate IL-17-mediated immunopathology in chronic inflammation and autoimmunity without compromising protective immunity to infection.

Streptococcus M utans-Specific Antimicrobial Peptide C16G2-Mediated Caries Prevention: A Review.

Oral biofilms are a group of healthy synergistic organisms, that on interplay with the immune system undergo transition and colonize the pathogenic bacteria, leading to various diseases like dental caries, gingivitis, periodontitis and a few systemic conditions. Dental caries being the most common disease of the oral cavity, comprise a heterogeneous group of bacteria that can cause imbalance in the biofilm. Caries prevention has been in research for decades, where antibiotics, chemical biocides and fluoride-antimicrobial approaches have not been adequate for this multifactorial disease. In recent years, the major focus of caries prevention has been shifted to plaque-biofilm modification as an ecological approach that would prevent bacterial colonization. Saliva produces various natural antimicrobial peptides that can regulate biofilm modification. Synthetic production of antimicrobial peptides concentrates on selective elimination and a targeted approach towards cariogenic pathogens, precisely Streptococcus mutans (S. mutans). A search in Medline/PubMed, EBSCO and ScienceDirect databases on C16G2, antimicrobial peptides (AMPs) and S. mutans, using MeSH (Medical Subject Heading) terms was performed and papers published until 2020 were included for further evaluation. A total of eight articles written in English with available full texts were selected based on the search strategy. They included four publications on AMPs against S. mutans and another four articles on AMPs in caries prevention. This review focuses on C16G2 antimicrobial peptide and its potential to modify biofilm and inhibit the targeted bacteria causing dental caries.

Current Status of Immune Deficiency Pathway in Tenebrio molitor Innate Immunity.

Yellow mealworm (Tenebrio molitor) is a highly beneficial beetle that serves as an excellent source of edible protein as well as a practical study model. Therefore, studying its immune system is important. Like in other insects, the innate immune response effected through antimicrobial peptides production provides the most critical defense armory in T. molitor. Immune deficiency (Imd) signaling is one of the major pathways involved in the humoral innate immune response in this beetle. However, the nature of the molecules involved in the signaling cascade of the Imd pathway, from recognition to the production of final effectors, and their mechanism of action are yet to be elucidated in T. molitor model. In this review, we present a general overview of the current literature available on the Imd signaling pathway and its identified interaction partners in T. molitor.