Insights into anti-pathogenic activities of mannose lectins

Targeted nanotherapeutics for the treatment of Helicobacter pylori infection

Helicobacter pylori infection is involved in gastric diseases such as peptic ulcer and adenocarcinoma. Approved antibiotherapies still fail in 10 to 40% of the infected patients and, in this scenario, targeted nanotherapeutics emerged as powerful allies for H. pylori eradication. Nano/microparticles conjugated with H. pylori binding molecules were developed to eliminate H. pylori by either (i) blocking essential mechanisms of infection, such as adhesion to gastric mucosa or (ii) binding and killing H. pylori through the release of drugs within the bacteria or at the site of infection. Glycan antigens (as Lewis B and sialyl-Lewis X), pectins, lectins, phosphatidylethanolamine and epithelial cell membranes were conjugated with nano/microparticles to successfully block H. pylori adhesion. Urea-coated nanoparticles were used to improve drug delivery inside bacteria through H. pylori UreI channel. Moreover, nanoparticles coated with antibodies against H. pylori and loaded with sono/photosensitizers, were promising for their application as targeted sono/photodynamic therapies. Further, non-specific H. pylori nano/microparticles, but only active in the acidic gastric environment, coated with binders to bacterial membrane, extracellular polymeric substances or to high temperature requirement A protease, were evaluated. In this review, an overview of the existing nanotherapeutics targeting H. pylori will be given and their rational, potential to counteract infection, as well as level of development will be presented and discussed.

Vicia ervilia lectin (VEA) has an antibiofilm effect on both Gram-positive and Gram-negative pathogenic bacteria

Bacterial growing resistance to antibiotics poses a critical threat to global health. This study investigates, for the first time, the antibiofilm properties of Vicia ervilia agglutinin (VEA) from six different V. ervilia accessions against pathogenic bacteria, and the yeast Candida albicans. In the absence of antimicrobial properties, purified VEA significantly inhibited biofilm formation, both in Gram-positive and Gram-negative bacteria, but not in C. albicans. With an inhibitory concentration ranging from 100 to 500 µg/ml, the VEA antibiofilm activity was more relevant against the Gram-positive bacteria Streptococcus aureus and Staphylococcus epidermidis, whose biofilm was reduced up to 50% by VEA purified from accessions #5 and #36. VEA antibiofilm variability between accessions was observed, likely due to co-purified small molecules rather than differences in VEA protein sequences. In conclusion, VEA seed extracts from the accessions with the highest antibiofilm activity could represent a valid approach for the development of an effective antibiofilm agent.

Genome-wide identification and analysis of monocot-specific chimeric jacalins (MCJ) genes in Maize (Zea mays L.)

BACKGROUND

The monocot chimeric jacalins (MCJ) proteins, which contain a jacalin-related lectin (JRL) domain and a dirigent domain (DIR), are specific to Poaceae. MCJ gene family is reported to play an important role in growth, development and stress response. However, their roles in maize have not been thoroughly investigated.

RESULTS

In this study, eight MCJ genes in the maize genome (designated as ZmMCJs) were identified, which displayed unequal distribution across four chromosomes. Phylogenetic relationships between the ZmMCJs were evident through the identification of highly conserved motifs and gene structures. Analysis of transcriptome data revealed distinct expression patterns among the ZmMCJ genes, leading to their classification into four different modules, which were subsequently validated using RT-qPCR. Protein structures of the same module are found to be relatively similar. Subcellular localization experiments indicated that the ZmMCJs are mainly located on the cell membrane. Additionally, hemagglutination and inhibition experiments show that only part of the ZmMCJs protein has lectin activity, which is mediated by the JRL structure, and belongs to the mannose-binding type. The cis-acting elements in the promoter region of ZmMCJ genes predicted their involvement response to phytohormones, such as abscisic acid and jasmonic acid. This suggests that ZmMCJ genes may play a significant role in both biotic and abiotic stress responses.

CONCLUSIONS

Overall, this study adds new insights into our understanding of the gene-protein architecture, evolutionary characteristics, expression profiles, and potential functions of MCJ genes in maize.

Biosensor Characterization from Cratylia mollis Seed Lectin (Cramoll)-MOF and Specific Carbohydrate Interactions in an Electrochemical Model

Biosensors are small devices known for their selectivity, high specificity and sensitivity to the respective analyte, at low concentrations. We developed an electrochemical biosensor using the crystalline polymer MOF-[Cu3 (BTC)2 (H2 O)2 ]n to characterize Cratylia mollis seed lectin (Cramoll) and its interaction with free carbohydrate (glucose) and carbohydrates on the surface of rabbit erythrocytes. The electrochemical potentials presented by the exponential curves that vary from 96 to 142 mV in relation to concentrations of 10 to 20 mM of glucose are decisive for the use of the system containing gold electrode/MOF/Cramoll for the characterization of biological models due to its high sensitivity. As well as the kinetic behavior presented in the cyclic voltammograms, with a cathodic current response of 0.000 3 A for a glucose concentration of 15 mM. These results were due to the high specificity of Cramoll under these conditions, promoting stability of surface charges at the Cramoll/electrode interface. This phenomenon facilitates the monitoring of the interaction with free glucose present in the electrolyte medium by potentiometric and amperometric methods and with carbohydrates present on the surface of rabbit erythrocytes through the potentiometric method. Through scanning electron microscopy (SEM) it was possible to observe Cramoll immobilized on the MOF surface, proving the specificity of the ligand (glucose-lectin) through the morphological lectin changes in this process. This electrochemical model, Cramoll/MOF biosensor, is effective for evaluating free lectin/carbohydrate or in the erythrocyte membrane.

Fc-MBL-modified Fe3O4 magnetic bead enrichment and fixation in Gram stain for rapid detection of low-concentration bacteria

Functional bacterial enrichment magnetic beads (Fe₃O₄@SiO₂@Fc-MBL) and Gram staining were combined for the fast diagnosis of infecting bacteria in meningitis. Fe₃O₄@SiO₂@Fc-MBL has excellent microbial binding ability and can be used for bacterial enrichment from cerebrospinal fluid (CSF). The enriched bacteria are recognized by Gram stain at very low concentrations (10 CFU·mL^-1). The feasibility of this method was verified by five common bacteria in meningitis infection (Gram-positive: Staphylococcus epidermidis, Staphylococcus haemolyticus, and Staphylococcus capitis; Gram-negative: Klebsiella pneumoniae and Escherichia coli). The extraction efficiency of Fc-MBL-modified Fe₃O₄ magnetic beads was approximately 90% in artificial CSF for the selected bacteria, with the exception of E. coli (~ 60%). The bacteria were successfully recognized by Gram staining and microscopic observation. Fe₃O₄@SiO₂@Fc-MBL acts by capturing and fixing the bacteria in a magnetic field throughout the experiment. Compared with traditional CSF Gram staining, this new method avoids interference by inflammatory cells and red blood cells during microscopic examination. Furthermore, the sensitivity of this method is much better than the centrifugation smear method. The whole process can be accomplished within 30 min. This novel method may have potential as a clinical tool for analysis of bacteria in the CSF.

Association of Mannose-Binding Lectin 2 Gene Polymorphism with Tuberculosis Based on Mycobacterium tuberculosis Lineages

Purpose

Polymorphisms in MBL2 may contribute to the susceptibility to tuberculosis. The aim of the present study was to determine the associations of the polymorphisms of five loci (rs1800450, rs1800451, rs7096206, rs7095891, and rs11003125) in the MBL2 gene with susceptibility to tuberculosis and specific lineages of Mycobacterium tuberculosis causing tuberculosis in the Uyghur population of Xinjiang, China.

Methods

From January 2019 to January 2020, we enrolled 170 Uyghur tuberculosis patients as the case group and 147 Uyghur staff with no clinical symptoms as the control group from four designated tuberculosis hospitals in southern Xinjiang, China. The polymorphisms of five loci in MBL2 of human were detected by sequencing. Whole-genome sequencing was applied in 68 M. tuberculosis isolates from the case group and the data were used to perform genealogy analysis.

Results

The distributions of allele and genotype frequencies of five loci in MBL2 varied little between the case and control groups and varied little among the groups, including those infected with different lineages of M. tuberculosis and the control (except those of rs11003125), the P values were all >0.05. The distribution of alleles of rs11003125 was statistically different between patients infected with lineages 3 and 4 M. tuberculosis (χ²=7.037, P=0.008). The C allele and CC genotype of rs11003125 were found to be protective factors against lineage 4 infection when compared to lineage 3 (ORs were 0.190 and 0.158, respectively; 95% confidence intervals were 0.053~0.690 and 0.025~0.999, respectively).

Conclusion

Our results suggested that human’s susceptibility to tuberculosis is affected both by the host genetic polymorphisms and the lineage of the M. tuberculosis that people were exposed to. However, due to the limitation of the sample size in the present study, larger sample size and more rigorous design should be guaranteed in future studies.

Mannose-binding lectin conjugated to quantum dots as fluorescent nanotools for carbohydrate tracing

Quantum dots (QDs) have stood out as nanotools for glycobiology due to their photostability and ability to be combined with lectins. Mannose-binding lectin (MBL) is involved in the innate immune system and plays important roles in the activation of the complement cascade, opsonization, and elimination of apoptotic and microbial cells. Herein, adsorption and covalent coupling strategies were evaluated to conjugate QDs to a recombinant human MBL (rhMBL). The most efficient nanoprobe was selected by evaluating the conjugate ability to labelCandida albicansyeasts by flow cytometry. The QDs-rhMBL conjugate obtained by adsorption at pH 6.0 was the most efficient, labelingca.100% of cells with the highest median fluorescence intensity. The conjugation was also supported by Fourier transform infrared spectroscopy, zeta potential, and size analyses.C. albicanslabeling was calcium-dependent; 12% and <1% of cells were labeled in buffers without calcium and containing EDTA, respectively. The conjugate promoted specific labeling (based on cluster effect) since, after inhibition with mannan, there was a reduction of 80% in cell labeling, which did not occur with methyl-α-D-mannopyranoside monosaccharide. Conjugates maintained colloidal stability, bright fluorescence, and biological activity for at least 8 months. Therefore, QDs-rhMBL conjugates are promising nanotools to elucidate the roles of MBL in biological processes.

Pattern recognition receptors in health and diseases

Pattern recognition receptors (PRRs) are a class of receptors that can directly recognize the specific molecular structures on the surface of pathogens, apoptotic host cells, and damaged senescent cells. PRRs bridge nonspecific immunity and specific immunity. Through the recognition and binding of ligands, PRRs can produce nonspecific anti-infection, antitumor, and other immunoprotective effects. Most PRRs in the innate immune system of vertebrates can be classified into the following five types based on protein domain homology: Toll-like receptors (TLRs), nucleotide oligomerization domain (NOD)-like receptors (NLRs), retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), C-type lectin receptors (CLRs), and absent in melanoma-2 (AIM2)-like receptors (ALRs). PRRs are basically composed of ligand recognition domains, intermediate domains, and effector domains. PRRs recognize and bind their respective ligands and recruit adaptor molecules with the same structure through their effector domains, initiating downstream signaling pathways to exert effects. In recent years, the increased researches on the recognition and binding of PRRs and their ligands have greatly promoted the understanding of different PRRs signaling pathways and provided ideas for the treatment of immune-related diseases and even tumors. This review describes in detail the history, the structural characteristics, ligand recognition mechanism, the signaling pathway, the related disease, new drugs in clinical trials and clinical therapy of different types of PRRs, and discusses the significance of the research on pattern recognition mechanism for the treatment of PRR-related diseases.

Activity of Mannose-Binding Lectin on Bacterial-Infected Chickens-A Review

Simple Summary

In the quest to combat bacterial-related diseases in chickens, different methods, of which some are less economical and less effective on the long-term, have been adapted. However, chickens possess mannose-binding lectin (MBL) which could be vital in managing pathogenic bacteria in chickens. MBL is one of the soluble proteins secreted by the chicken’s innate immune system which can be activated when chickens are exposed to chicken-related diseases. This review explains how mannose-binding lectin activation can help in fighting bacterial pathogens in chickens. This knowledge is believed to reduce incessant use of antibiotics and to assist in developing a profitable breeding program with less or no adverse effect on the chicken, human and the environment.

Abstract

In recent years, diseases caused by pathogenic bacteria have profoundly impacted chicken production by causing economic loss in chicken products and by-product revenues. MBL (mannose-binding lectin) is part of the innate immune system (IIS), which is the host’s first line defense against pathogens. The IIS functions centrally by identifying pathogen-specific microorganism-associated molecular patterns (MAMPs) with the help of pattern recognition receptors (PRRs). Studies have classified mannose-binding lectin (MBL) as one of the PRR molecules which belong to the C-type lectin family. The protective role of MBL lies in its ability to activate the complement system via the lectin pathway and there seems to be a direct link between the chicken’s health status and the MBL concentration in the serum. Several methods have been used to detect the presence, the level and the structure of MBL in chickens such as Enzyme-linked immunosorbent assay (ELISA), Polymerase Chain Reaction (PCR) among others. The concentration of MBL in the chicken ranges from 0.4 to 35 µg/mL and can be at peak levels at three to nine days at entry of pathogens. The variations observed are known to depend on the bacterial strains, breed and age of the chicken and possibly the feed manipulation strategies. However, when chicken MBL (cMBL) becomes deficient, it can result in malfunctioning of the innate immune system, which can predispose chickens to diseases. This article aimed to discuss the importance and components of mannose-binding lectin (MBL) in chickens, its mode of actions, and the different methods used to detect MBL. Therefore, more studies are recommended to explore the causes for low and high cMBL production in chicken breeds and the possible effect of feed manipulation strategies in enhancing cMBL production.

A SNaPshot Assay for Determination of the Mannose-Binding Lectin Gene Variants and an Algorithm for Calculation of Haplogenotype Combinations

Mannose-binding lectin (MBL) deficiency caused by the variability in the MBL2 gene is responsible for the susceptibility to and severity of various infectious and autoimmune diseases. A combination of six single nucleotide polymorphisms (SNPs) has a major impact on MBL levels in circulation. The aim of this study is to design and validate a sensitive and economical method for determining MBL2 haplogenotypes. The SNaPshot assay is designed and optimized to genotype six SNPs (rs1800451, rs1800450, rs5030737, rs7095891, rs7096206, rs11003125) and is validated by comparing results with Sanger sequencing. Additionally, an algorithm for online calculation of haplogenotype combinations from the determined genotypes is developed. Three hundred and twenty-eight DNA samples from healthy individuals from the Czech population are genotyped. Minor allele frequencies (MAFs) in the Czech population are in accordance with those present in the European population. The SNaPshot assay for MBL2 genotyping is a high-throughput, cost-effective technique that can be used in further genetic-association studies or in clinical practice. Moreover, a freely available online application for the calculation of haplogenotypes from SNPs is developed within the scope of this project.

Xenophagy in innate immunity: A battle between host and pathogen

Autophagy is a fundamental bulk intracellular degradation and recycling process that directly eliminates intracellular microorganisms through "xenophagy" in various types of cells, especially in macrophages. Meanwhile, bacteria have evolved strategies and cellular self-defense mechanisms to prevent autophagosomal degradation and even attack the immune system of host. The lack of knowledge about the roles of autophagy in innate immunity severely limits our understanding of host defensive system and the development of farmed industry consisting of aquaculture. Increasing evidence in recent decades has shown the importance of autophagy. This review focuses on the triggering of xenophagy, targeting of invading pathogens to autophagosomes and elimination in the autophagolysosomes during pathogen infection. How the pathogen can escape from the xenophagy pathway was also discussed. Overall, we aim to reduce diseases and improve industrial production in aquaculture by providing theoretical and technical guidance on xenophagy.