Chitin and chitinase: Role in pathogenicity, allergenicity and health

Easy-to-use imaging-cytometry assay to analyze chitin patterns in yeasts

BACKGROUND & AIM

Pathogenic fungi are a major threat to public health, and fungal infections are becoming increasingly common and treatment resistant. Chitin, a component of the fungal cell wall, modifies host immunity and contributes to antifungal resistance. Moreover, chitin content is regulated by chitin synthases and chitinases. However, the specific roles and mechanisms remain unclear. In this study, we developed a cytometric imaging assay to quantify chitin content and identify the distribution of chitin in the yeast cell wall.

METHODS

The Candida albicans SC5314 and Nakaseomyces glabratus (ex. C. glabrata) ATCC2001 reference strains, as well as 106 clinical isolates, were used. Chitin content, distribution, and morphological parameters were analysed in 12 yeast species. Moreover, machine learning statistical software was used to evaluate the ability of the cytometric imaging assay to predict yeast species using the values obtained for these parameters.

RESULTS

Our imaging-cytometry assay was repeatable, reproducible, and sensitive to variations in chitin content in C. albicans mutants or after antifungal stimulation. The evaluated parameters classified the yeast species into the correct clade with an accuracy of 85 %.

CONCLUSION

Our findings demonstrate that this easy-to-use assay is an effective tool for the exploration of chitin content in yeast species.

The great potential of polysaccharides from natural resources in the treatment of asthma: A review

Despite significant progress in diagnosis and treatment, asthma remains a serious public health challenge. The conventional therapeutic drugs for asthma often have side effects and unsatisfactory clinical efficacy. Therefore, it is very urgent to develop new drugs to overcome the shortcomings of conventional drugs. Natural polysaccharides provide enormous resources for the development of drugs or health products, and they are receiving a lot of attention from scientists around the world due to their safety, effective anti-inflammatory and immune regulatory properties. Increasing evidence shows that polysaccharides have favorable biological activities in the respiratory disease, including asthma. This review provides an overview of primary literature on the recent advances of polysaccharides from natural resources in the treatment of asthma. The mechanisms and practicability of polysaccharides, including polysaccharides from plants, fungus, bacteria, alga, animals and others are reviewed. Finally, the further research of polysaccharides in the treatment of asthma are discussed. This review can provide a basis for further study of polysaccharides in the treatment of asthma and provides guidance for the development and clinical application of novel asthma treatment drugs.

Activity of a Recombinant Chitinase of the Atta sexdens Ant on Different Forms of Chitin and Its Fungicidal Effect against Lasiodiplodia theobromae

This study evaluates the activity of a recombinant chitinase from the leaf-cutting ant Atta sexdens (AsChtII-C4B1) against colloidal and solid α- and β-chitin substrates. 1H NMR analyses of the reaction media showed the formation of N-acetylglucosamine (GlcNAc) as the hydrolysis product. Viscometry analyses revealed a reduction in the viscosity of chitin solutions, indicating that the enzyme decreases their molecular masses. Both solid state 13C NMR and XRD analyses showed minor differences in chitin crystallinity pre- and post-reaction, indicative of partial hydrolysis under the studied conditions, resulting in the formation of GlcNAc and a reduction in molecular mass. However, the enzyme was unable to completely degrade the chitin samples, as they retained most of their solid-state structure. It was also observed that the enzyme acts progressively and with a greater activity on α-chitin than on β-chitin. AsChtII-C4B1 significantly changed the hyphae of the phytopathogenic fungus Lasiodiplodia theobromae, hindering its growth in both solid and liquid media and reducing its dry biomass by approximately 61%. The results demonstrate that AsChtII-C4B1 could be applied as an agent for the bioproduction of chitin derivatives and as a potential antifungal agent.

Engineering the Relatively Conserved Residues in Active Site Architecture of Thermophilic Chitinase SsChi18A Enhanced Catalytic Activity

Chitinase plays a vital role in the efficient biotransformation of the chitin substrate. This study aimed to modify and elucidate the contribution of the relatively conserved residues in the active site architecture of a thermophilic chitinase SsChi18A from Streptomyces sp. F-3 in processive catalysis. The enzymatic activity on colloidal chitin increased to 151%, 135%, and 129% in variants Y286W, E287A, and K186A compared with the wild type (WT). Also, the apparent processive parameter G2/G1 was lower in the variants compared to the WT, indicating the essential role of Tyr-286, Glu-287, and Lys-186 in processive catalysis. Additionally, the enzymatic activity on the crystalline chitin of F48W and double mutants F48W/Y209F and F48W/Y286W increased by 35%, 16%, and 36% compared with that for WT. Molecular dynamics simulations revealed that the driving force of processive catalysis might be related to the changes in interaction energy. This study provided a rational design strategy targeting relatively conserved residues to enhance the catalytic activity of GH18 processive chitinases.

Location-based prediction model for Crohn's disease regarding a novel serological marker, anti-chitinase 3-like 1 autoantibodies

BACKGROUND

Defective neutrophil regulation in inflammatory bowel disease (IBD) is thought to play an important role in the onset or manifestation of IBD, as it could lead to damage of the intestinal mucosal barrier by the infiltration of neutrophils in the inflamed mucosa and the accumulation of pathogens. Like neutrophils in the context of innate immune responses, immunoglobulin A (IgA) as an acquired immune response partakes in the defense of the intestinal epithelium. Under normal conditions, IgA contributes to the elimination of microbes, but in connection with the loss of tolerance to chitinase 3-like 1 (CHI3L1) in IBD, IgA could participate in CHI3L1-mediated improved adhesion and invasion of potentially pathogenic microorganisms. The tolerance brake to CHI3L1 and the occurrence of IgA autoantibodies to this particular target, the exact role and underlying mechanisms of CHI3L1 in the pathogenesis of IBD are still unclear.

AIM

To determine the predictive potential of Ig subtypes of a novel serological marker, anti-CHI3L1 autoantibodies (aCHI3L1) in determining the disease phenotype, therapeutic strategy and long-term disease course in a prospective referral cohort of adult IBD patients.

METHODS

Sera of 257 Crohn's disease (CD) and 180 ulcerative colitis (UC) patients from a tertiary IBD referral center of Hungary (Division of Gastroenterology, Department of Internal Medicine, Faculty of Medicine, University of Debrecen) were assayed for IgG, IgA, and secretory IgA (sIgA) type aCHI3L1 by enzyme-linked immunosorbent assay using recombinant CHI3L1, along with 86 healthy controls (HCONT).

RESULTS

The IgA type was more prevalent in CD than in UC (29.2% vs 11.1%) or HCONT (2.83%; P < 0.0001 for both). However, sIgA subtype aCHI3L1 positivity was higher in both CD and UC patients than in HCONT (39.3% and 32.8% vs 4.65%, respectively; P < 0.0001). The presence of both IgA and sIgA aCHI3L1 antibodies was associated with colonic involvement (P < 0.0001 and P = 0.038, respectively) in patients with CD. Complicated disease behavior at sample procurement was associated with aCHI3L1 sIgA positivity (57.1% vs 36.0%, P = 0.009). IgA type aCH3L1 was more prevalent in patients with frequent relapse during the disease course in the CD group (46.9% vs 25.7%, P = 0.005). In a group of patients with concomitant presence of pure inflammatory luminal disease and colon involvement at the time of diagnosis, positivity for IgA or sIgA type aCH3L1 predicted faster progression towards a complicated disease course in time-dependent models. This association disappeared after merging subgroups of different disease locations.

CONCLUSION

CHI3L1 is a novel neutrophil autoantigenic target in IBD. The consideration of antibody classes along with location-based prediction may transform the future of serology in IBD.

Widespread occurrence of chitinase-encoding genes suggests the Endozoicomonadaceae family as a key player in chitin processing in the marine benthos

Chitin is the most abundant natural polymer in the oceans, where it is primarily recycled by chitin-degrading microorganisms. Endozoicomonadaceae (Oceanospirillales) bacteria are prominent symbionts of sessile marine animals, particularly corals, and presumably contribute to nutrient cycling in their hosts. To reveal the chitinolytic potential of this iconic, animal-dwelling bacterial family, we examined 42 publicly available genomes of cultured and uncultured Endozoicomonadaceae strains for the presence of chitinase-encoding genes. Thirty-two of 42 Endozoicomonadaceae genomes harbored endo-chitinase- (EC 3.2.1.14), 25 had exo-chitinase- (EC 3.2.1.52) and 23 polysaccharide deacetylase-encoding genes. Chitinases were present in cultured and uncultured Endozoicomonadaceae lineages associated with diverse marine animals, including the three formally described genera Endozoicomonas, Paraendozoicomonas and Kistimonas, the new genus Candidatus Gorgonimonas, and other, yet unclassified, groups of the family. Most endo-chitinases belonged to the glycoside hydrolase family GH18 but five GH19 endo-chitinases were also present. Many endo-chitinases harbored an active site and a signal peptide domain, indicating the enzymes are likely functional and exported to the extracellular environment where endo-chitinases usually act. Phylogenetic analysis revealed clade-specific diversification of endo-chitinases across the family. The presence of multiple, distinct endo-chitinases on the genomes of several Endozoicomonadaceae species hints at functional variation to secure effective chitin processing in diverse micro-niches and changing environmental conditions. We demonstrate that endo-chitinases and other genes involved in chitin degradation are widespread in the Endozoicomonadaceae family and posit that these symbionts play important roles in chitin turnover in filter- and suspension-feeding animals and in benthic, marine ecosystems at large.

From gut to skin: exploring the potential of natural products targeting microorganisms for atopic dermatitis treatment

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease. Recent studies have revealed that interactions between pathogenic microorganisms, which have a tendency to parasitize the skin of AD patients, play a significant role in the progression of the disease. Furthermore, specific species of commensal bacteria in the human intestinal tract can have a profound impact on the immune system by promoting inflammation and pruritogenesis in AD, while also regulating adaptive immunity. Natural products (NPs) have emerged as promising agents for the treatment of various diseases. Consequently, there is growing interest in utilizing natural products as a novel therapeutic approach for managing AD, with a focus on modulating both skin and gut microbiota. In this review, we discuss the mechanisms and interplay between the skin and gut microbiota in relation to AD. Additionally, we provide a comprehensive overview of recent clinical and fundamental research on NPs targeting the skin and gut microbiota for AD treatment. We anticipate that our work will contribute to the future development of NPs and facilitate research on microbial mechanisms, based on the efficacy of NPs in treating AD.

Expression and possible functions of a horizontally transferred glycosyl hydrolase gene, GH6-1, in Ciona embryogenesis

BACKGROUND

The Tunicata or Urochordata is the only animal group with the ability to synthesize cellulose directly and cellulose is a component of the tunic that covers the entire tunicate body. The genome of Ciona intestinalis type A contains a cellulose synthase gene, CesA, that it acquired via an ancient, horizontal gene transfer. CesA is expressed in embryonic epidermal cells and functions in cellulose production. Ciona CesA is composed of both a glycosyltransferase domain, GT2, and a glycosyl hydrolase domain, GH6, which shows a mutation at a key position and seems functionless. Interestingly, the Ciona genome contains a glycosyl hydrolase gene, GH6-1, in which the GH6 domain seems intact. This suggests expression and possible functions of GH6-1 during Ciona embryogenesis. Is GH6-1 expressed during embryogenesis? If so, in what tissues is the gene expressed? Does GH6-1 serve a function? If so, what is it? Answers to these questions may advance our understanding of evolution of this unique animal group.

RESULTS

Quantitative reverse transcription PCR and in situ hybridization revealed that GH6-1 is expressed in epidermis of tailbud embryos and in early swimming larvae, a pattern similar to that of CesA. Expression is downregulated at later stages and becomes undetectable in metamorphosed juveniles. The GH6-1 expression level is higher in the anterior-trunk region and caudal-tip regions of late embryos. Single-cell RNA sequencing analysis of the late tailbud stage showed that cells of three clusters with epidermal identity express GH6-1, and that some of them co-express CesA. TALEN-mediated genome editing was used to generate GH6-1 knockout Ciona larvae. Around half of TALEN-electroporated larvae showed abnormal development of adhesive papillae and altered distribution of surface cellulose. In addition, three-fourths of TALEN-electroporated animals failed to complete larval metamorphosis.

CONCLUSIONS

This study showed that tunicate GH6-1, a gene that originated by horizontal gene transfer of a prokaryote gene, is recruited into the ascidian genome, and that it is expressed and functions in epidermal cells of ascidian embryos. Although further research is required, this observation demonstrates that both CesA and GH6-1 are involved in tunicate cellulose metabolism, impacting tunicate morphology and ecology.

Chitosan Nanoparticles-Based Cancer Drug Delivery: Application and Challenges

Chitin is the second most abundant biopolymer consisting of N-acetylglucosamine units and is primarily derived from the shells of marine crustaceans and the cell walls of organisms (such as bacteria, fungi, and algae). Being a biopolymer, its materialistic properties, such as biodegradability, and biocompatibility, make it a suitable choice for biomedical applications. Similarly, its deacetylated derivative, chitosan, exhibits similar biocompatibility and biodegradability properties, making it a suitable support material for biomedical applications. Furthermore, it has intrinsic material properties such as antioxidant, antibacterial, and antitumor. Population studies have projected nearly 12 million cancer patients across the globe, where most will be suffering from solid tumors. One of the shortcomings of potent anticancer drugs is finding a suitable cellular delivery material or system. Therefore, identifying new drug carriers to achieve effective anticancer therapy is becoming essential. This paper focuses on the strategies implemented using chitin and chitosan biopolymers in drug delivery for cancer treatment.

Particulate matter10-induced airway inflammation and fibrosis can be regulated by chitinase-1 suppression

BACKGROUND

Particulate matter₁₀ (PM₁₀) can induce airway inflammation and fibrosis. Recently, chitinase-1 has been shown to play key roles in inflammation and fibrosis. We aimed to investigate the effects of chitinase-1 inhibitor in PM₁₀-treated murine mice models.

METHODS

In female BALB/c mice, PM₁₀ was intranasally administered six times over 3 weeks, and ovalbumin (OVA) was intraperitoneally injected and then intranasally administered. Chitinase-1 inhibitor (CPX) 6 times over 3 weeks or dexamethasone 3 times in the last week were intraperitoneally administered. Two days after the last challenges, mice were euthanized. Messenger RNA sequencing using lung homogenates was conducted to evaluate signaling pathways.

RESULTS

PM₁₀ and/or OVA-induced airway inflammation and fibrosis murine models were established. CPX and dexamethasone ameliorated PM₁₀ or PM₁₀/OVA-induced airway hyper-responsiveness, airway inflammation, and fibrosis. CPX and dexamethasone also reduced levels of various inflammatory markers in lung homogenates. PM₁₀ and OVA also induced changes in mRNA expression across an extreme range of genes. CPX and dexamethasone decreased levels of mRNA expression especially associated with inflammation and immune regulation. They also significantly regulated asthma and asthma-related pathways, including the JACK-STAT signaling pathway.

CONCLUSIONS

Chitinase-1 suppression by CPX can regulate PM₁₀- and OVA-induced and aggravated airway inflammation and fibrosis via an asthma-related signaling pathway.

Modulation of defense genes and phenolic compounds in wild blueberry in response to Botrytis cinerea under field conditions

Botrytis blight is an important disease of wild blueberry [(Vaccinium angustifolium (Va) and V. myrtilloides (Vm))] with variable symptoms in the field due to differences in susceptibility among blueberry phenotypes. Representative blueberry plants of varying phenotypes were inoculated with spores of B. cinerea. The relative expression of pathogenesis-related genes (PR3, PR4), flavonoid biosynthesis genes, and estimation of the concentration of ten phenolic compounds between uninoculated and inoculated samples at different time points were analyzed. Representative plants of six phenotypes (brown stem Va, green stem Va, Va f. nigrum, tall, medium, and short stems of Vm) were collected and studied using qRT-PCR. The expression of targeted genes indicated a response of inoculated plants to B. cinerea at either 12, 24, 48 or 96 h post inoculation (hpi). The maximum expression of PR3 occurred at 24 hpi in all the phenotypes except Va f. nigrum and tall stem Vm. Maximum expression of both PR genes occurred at 12 hpi in Va f. nigrum. Chalcone synthase, flavonol synthase and anthocyanin synthase were suppressed at 12 hpi followed by an upregulation at 24 hpi. The expression of flavonoid pathway genes was phenotype-specific with their regulation patterns showing temporal differences among the phenotypes. Phenolic compound accumulation was temporally regulated at different post-inoculation time points. M-coumaric acid and kaempferol-3-glucoside are the compounds that were increased with B. cinerea inoculation. Results from this study suggest that the expression of PR and flavonoid genes, and the accumulation of phenolic compounds associated with B. cinerea infection could be phenotype specific. This study may provide a starting point for understanding and determining the mechanisms governing the wild blueberry-B. cinerea pathosystem.

Inflammatory checkpoints in amyotrophic lateral sclerosis: From biomarkers to therapeutic targets

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive motor neuron damage. Due to the complexity of the ALS, so far the etiology and underlying pathogenesis of sporadic ALS are not completely understood. Recently, many studies have emphasized the role of inflammatory networks, which are comprised of various inflammatory molecules and proteins in the pathogenesis of ALS. Inflammatory molecules and proteins may be used as independent predictors of patient survival and might be used in patient stratification and in evaluating the therapeutic response in clinical trials. This review article describes the latest advances in various inflammatory markers in ALS and its animal models. In particular, this review discusses the role of inflammatory molecule markers in the pathogenesis of the disease and their relationship with clinical parameters. We also highlight the advantages and disadvantages of applying inflammatory markers in clinical manifestations, animal studies, and drug clinical trials. Further, we summarize the potential application of some inflammatory biomarkers as new therapeutic targets and therapeutic strategies, which would perhaps expand the therapeutic interventions for ALS.

Anaphylaxis induced by intra-articular injection of chitosan: A case report and literature review

Generally, we consider chitosan being a safe, nontoxic natural polymer with wide clinical applications. However, allergic reactions caused by chitosan have been reported on rare occasions. We report here a case of allergy and perform a literature review.

Zooplankton act as cruise ships promoting the survival and pathogenicity of pathogenic bacteria

Bacteria in general interact with zooplankton in aquatic ecosystems. These zooplankton-bacterial interactions help to shape the bacterial community by regulating bacterial abundances. Such interactions are even more significant and crucially in need of investigation in the case of pathogenic bacteria, which cause severe diseases in humans and animals. Among the many associations between a host metazoan and pathogenic bacteria, zooplankton provide nutrition and protection from stressful conditions, promote the horizontal transfer of virulence genes, and act as a mode of pathogen transport. These interactions allow the pathogen to survive and proliferate in aquatic environments and to endure water treatment processes, thereby creating a potential risk to human health. This review highlights current knowledge on the contributions of zooplankton to the survival and pathogenicity of pathogenic bacteria. We also discuss the need to consider these interactions as a risk factor in water treatment processes.

Crystal structure of ChbG from Klebsiella pneumoniae reveals the molecular basis of diacetylchitobiose deacetylation

The chitobiose (chb) operon is involved in the synthesis of chitooligosaccharide and is comprised of a BCARFG gene cluster. ChbG encodes a chitooligosaccharide deacetylase (CDA) which catalyzes the removal of one acetyl group from N,N’-diacetylchitobiose. It is considered a novel type of CDA due to its lack of sequence homology. Although there are various structural studies of CDAs linked to the kinetic properties of the enzyme, the structural information of ChbG is unavailable. In this study, the crystal structure of ChbG from Klebsiella pneumoniae is provided. The molecular basis of deacetylation of diacetylchitobiose by ChbG is determined based on structural analysis, mutagenesis, biophysical analysis, and in silico docking of the substrate, diacetylchitobiose. This study contributes towards a deeper understanding of chitin and chitosan biology, as well as provides a platform to engineer CDA biocatalysts.

Structural and functional characterization of Klebsiella pneumonia ChbG (which lacks sequence homology) reveals the mechanism of chitooligosaccharide processing by ChbG.

Engineered Hemostatic Biomaterials for Sealing Wounds

Hemostatic biomaterials show great promise in wound control for the treatment of uncontrolled bleeding associated with damaged tissues, traumatic wounds, and surgical incisions. A surge of interest has been directed at boosting hemostatic properties of bioactive materials via mechanisms triggering the coagulation cascade. A wide variety of biocompatible and biodegradable materials has been applied to the design of hemostatic platforms for rapid blood coagulation. Recent trends in the design of hemostatic agents emphasize chemical conjugation of charged moieties to biomacromolecules, physical incorporation of blood-coagulating agents in biomaterials systems, and superabsorbing materials in either dry (foams) or wet (hydrogel) states. In addition, tough bioadhesives are emerging for efficient and physical sealing of incisions. In this Review, we highlight the biomacromolecular design approaches adopted to develop hemostatic bioactive materials. We discuss the mechanistic pathways of hemostasis along with the current standard experimental procedures for characterization of the hemostasis efficacy. Finally, we discuss the potential for clinical translation of hemostatic technologies, future trends, and research opportunities for the development of next-generation surgical materials with hemostatic properties for wound management.

Longitudinal and Comparative Measures of Serum Chitotriosidase and YKL-40 in Patients With Idiopathic Pulmonary Fibrosis

Background

Although chitin is absent in humans, chitinases are present in healthy subjects and show dysregulated expression in a variety of diseases resulting from abnormal tissue injury and repair responses. It was shown that chitotriosidase (chitinase 1/CHIT1) and structurally-related chitinase 3-like 1 protein (CHI3L1/YKL-40) play important roles in the pathobiology of idiopathic pulmonary fibrosis (IPF), however little is known about their longitudinal serum levels and relationship to clinical measures in IPF.

Methods

The present study is the first to evaluate serial measurements of serum CHIT1 activity and YKL-40 concentrations in patients with IPF starting antifibrotic treatment and followed up for 24 months. In addition, baseline serum CHIT1 and YKL-40 were compared between patients with IPF and control subjects, and possible CHIT1 and YKL-40 relationships to longitudinal clinical assessments in IPF were explored.

Results

Baseline serum CHIT1 activity and YKL-40 concentrations were significantly elevated in patients with IPF compared to control subjects and showed similar discriminatory ability in distinguishing IPF from controls. No significant differences between the median serum CHIT1 activity and YKL-40 concentration measured over a study follow-up were noted. We found significantly elevated baseline serum CHIT1 activity in the progressors compared with the stables in the first year, while significantly increased baseline serum CHIT1 activity was noted in the stables compared to the progressors in the second year. Additionally, we observed a significant negative correlation between a change in serum YKL-40 concentration and a change in forced vital capacity (FVC) % predicted (% pred.) in the stables subgroup, whereas, a change in serum CHIT1 activity correlated negatively with a change in FVC% pred. in the progressors subgroup.

Conclusions

This explorative study findings add further evidence that CHIT1 and YKL-40 are upregulated in patients with IPF, and suggest that longitudinally stable serum CHIT1 activity and YKL-40 concentration levels may potentially be associated with the antifibrotic treatment response. In addition, our findings are supporting the possible role of CHIT1 and YKL-40 as candidate diagnostic and prognostic biomarkers in IPF. Further research is needed to validate present study findings.

Transcriptome analysis of genes associated with autolysis of Coprinus comatus

Coprinus comatus, widely known as "Jituigu", is an important commodity and food in China. The yield of C. comatus, however, is substantially reduced by the autolysis of the fruiting bodies after harvest. To gain insight into the molecular mechanism underlying this autolysis, we divided the growth of C. comatus fruiting bodies into four stages: infant stage (I), mature stage (M), discolored stage (D), and autolysis stage (A). We then subjected these stages to de novo transcriptomic analysis using high-throughput Illumina sequencing. A total of 12,946 unigenes were annotated and analyzed with the Gene Ontology (GO), Clusters of Orthologous Groups of proteins (COG), and Kyoto Encyclopedia of Genes and Genomes (KEGG). We analyzed the differentially expressed genes (DEGs) between stages I and M, M and D, and D and A. Because the changes from M to D are thought to be related to autolysis, we focused on the DEGs between these two stages. We found that the pathways related to metabolic activity began to vary in the transition from M to D, including pathways named as autophagy-yeast, peroxisome, and starch and sucrose metabolism. This study also speculates the possible process of the autolysis of Coprinus comatus. In addition, 20 genes of interest were analyzed by quantitative real-time PCR to verify their expression profiles at the four developmental stages. This study, which is the first to describe the transcriptome of C. comatus, provides a foundation for future studies concerning the molecular basis of the autolysis of its fruiting bodies.

Occupational exposure to gasoline in gasoline station male attendants promotes M1 polarization in macrophages

Several studies have reported the toxicological implications of exposure to petroleum hydrocarbon fumes in animal models. There is little documentation on the effect of such exposure on oxidative stress levels and immune response. To our knowledge, no documentation of M1 polarization in macrophages in gasoline station male attendants. Therefore, this study aimed to evaluate the harmful effects of gasoline vapors in 62 male attendants (16-70 years) compared to 29 age- and sex-matched-unexposed controls. The attendants were recruited from Damietta governorate gasoline stations. Gasoline exposure induced a significant increase in tumor necrosis factor-α (TNF-α) level (p < 0.05) as well as a slight but non-significant increase in the activity of acidic mammalian chitinase (AMCase) (p > 0.05). Further TNF-α/AMCase ratio was significantly increased (p < 0.01) in sera of the attendants when compared to those of the healthy controls. Also, the total leucocytic and lymphocytic counts were significantly increased (p < 0.01 and p < 0.001, respectively). On contrary, neutrophils to lymphocytes ratio (NLR) and platelets to lymphocytes ratio (PLR) were significantly decreased (p < 0.05 and p < 0.001, respectively). In addition, significant reduction in hemoglobin (Hb) concentration, plasma glutathione reduced form (GSH), and catalase, as well as superoxide dismutase (SOD) activities in red blood cells were observed in the exposed attendants. As a result, malondialdehyde (MDA), nitric oxide (NO) levels, and NO/AMCase ratio were significantly increased (p < 0.05). In conclusion, this study inferred that prolonged gasoline exposure can mediate immune activation, especially M1 macrophages polarization, possibly via oxidative stress-mediated mechanism.

Current Perspectives on Chitinolytic Enzymes and Their Agro-Industrial Applications

Chitinases are a large and diversified category of enzymes that break down chitin, the world's second most prevalent polymer after cellulose. GH18 is the most studied family of chitinases, even though chitinolytic enzymes come from a variety of glycosyl hydrolase (GH) families. Most of the distinct GH families, as well as the unique structural and catalytic features of various chitinolytic enzymes, have been thoroughly explored to demonstrate their use in the development of tailor-made chitinases by protein engineering. Although chitin-degrading enzymes may be found in plants and other organisms, such as arthropods, mollusks, protozoans, and nematodes, microbial chitinases are a promising and sustainable option for industrial production. Despite this, the inducible nature, low titer, high production expenses, and susceptibility to severe environments are barriers to upscaling microbial chitinase production. The goal of this study is to address all of the elements that influence microbial fermentation for chitinase production, as well as the purifying procedures for attaining high-quality yield and purity.

Key considerations on the development of biodegradable biomaterials for clinical translation of medical devices: With cartilage repair products as an example

With the interdisciplinary convergence of biology, medicine and materials science, both research and clinical translation of biomaterials are progressing at a rapid pace. However, there is still a huge gap between applied basic research on biomaterials and their translational products - medical devices, where two significantly different perspectives and mindsets often work independently and non-synergistically, which in turn significantly increases financial costs and research effort. Although this gap is well-known and often criticized in the biopharmaceutical industry, it is gradually widening. In this article, we critically examine the developmental pipeline of biodegradable biomaterials and biomaterial-based medical device products. Then based on clinical needs, market analysis, and relevant regulations, some ideas are proposed to integrate the two different mindsets to guide applied basic research and translation of biomaterial-based products, from the material and technical perspectives. Cartilage repair substitutes are discussed here as an example. Hopefully, this will lay a strong foundation for biomaterial research and clinical translation, while reducing the amount of extra research effort and funding required due to the dissonance between innovative basic research and commercialization pipeline.

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To elucidate the chain of medical devices development and basic research process.

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To propose rationales of biomaterial research with mindset of clinical translation.

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To elaborate with established medical devices for cartilage repairs as examples.

RNAi for chitin synthase 1 rather than 2 causes growth delay and molting defect in Henosepilachna vigintioctopunctata

Chitin synthase (CHS) plays a critical role in chitin synthesis and excretion. In most insects, CHSs have been segregated into 1 and 2 classes. CHS1 is responsible for chitin production in the ectodermally-derived epidermal cells. CHS2 is dedicated to chitin biosynthesis in the midgut peritrophic matrix (PM). Henosepilachna vigintioctopunctata is a serious pest of Solanaceae and Cucurbitaceae plants. In this study, we identified HvCHS1 and HvCHS2. We found that HvCHS1 was abundantly transcribed in the larval tracheae and epidermis, whereas HvCHS2 was mainly expressed in the guts. Escherichia coli HT115 expressed double stranded RNAs targeting HvCHS1 and HvCHS2 (dsCHS1 and dsCHS2) were used to immerse potato foliage and the treated leaves were provided to the newly-molted fourth- and third-instar larvae. Ingestion of dsCHS1 by the fourth-instar larvae significantly diminished the target mRNA level and had slight influence on the expression of HvCHS2. In contrast, consumption of dsCHS2 significantly lowered the target mRNA level but triggered the transcription of HvCHS1. Knockdown of HvCHS1, rather than HvCHS2, arrested larval development and impaired larva-pupa-adult transition. A large proportion of HvCHS1 hypomorphs became stunting prepupae, deformed pupae or misshapen adults. Moreover, knockdown of HvCHS1 damaged gut integrity, decreased cuticle thickness, and delayed the formation of newly-generated cuticle layer during ecdysis. Furthermore, depletion of HvCHS1 inhibited the development of trachea system and thinned tracheal taenidia. Ingestion of dsCHS1 at the third-instar stage caused similar but severe negative effects. Our results demonstrated that HvCHS1 is responsible for chitin biosynthesis during ecdysis. Moreover, HvCHS1 is a potential amenable target gene and young larvae are more susceptible to dsRNA.

Comparative molecular evolution of chitinases in ascomycota with emphasis on mycoparasitism lifestyle

Chitinases are involved in multiple aspects of fungal life cycle, such as cell wall remodelling, chitin degradation and mycoparasitism lifestyle. To improve our knowledge of the chitinase molecular evolution of Ascomycota, the gene family of 72 representatives of this phylum was identified and subjected to phylogenetic, evolution trajectory and selective pressure analyses. Phylogenetic analysis showed that the chitinase gene family size and enzyme types varied significantly, along with species evolution, especially for groups B and C. In addition, two new subgroups, C3 and C4, are recognized in group C chitinases. Random birth and death testing indicated that gene expansion and contraction occurred in most of the taxa, particularly for species in the order Hypocreales (class Sordariomycetes). From an enzyme function point of view, we speculate that group A chitinases are mainly involved in species growth and development, while the expansion of genes in group B chitinases is related to fungal mycoparasitic and entomopathogenic abilities, and, to a certain extent, the expansion of genes in group C chitinases seems to be correlated with the host range broadening of some plant-pathogenic fungi in Sordariomycetes. Further selection pressure testing revealed that chitinases and the related amino acid sites were under positive selection in the evolutionary history, especially at the nodes sharing common ancestors and the terminal branches of Hypocreales. These results give a reasonable explanation for the size and function differences of chitinase genes among ascomycetes, and provide a scientific basis for understanding the evolutionary trajectories of chitinases, particularly that towards a mycoparasitic lifestyle.

Update on pollen-food allergy syndrome

INTRODUCTION

Allergies affect 20-30% of the population and respiratory allergies are mostly due to pollen grains from anemophilous plants. One to 5% of people suffer from food allergies and clinicians report increasing numbers of pollen-food allergy syndrome (PFAS), such that the symptoms have broadened from respiratory to gastrointestinal, and even to anaphylactic shock in the presence of cofactors. Thirty to 60% of food allergies are associated with pollen allergy while the percentage of pollen allergies associated to food allergy varies according to local environment and dietary habits.

AREAS COVERED

Articles published in peer-reviewed journals, covered by PubMed databank, clinical data are discussed including symptoms, diagnosis, and management. A chapter emphasizes the role of six well-known allergen families involved in PFAS: PR10 proteins, profilins, lipid transfer proteins, thaumatin-like proteins, isoflavone reductases, and β-1,3 glucanases. The relevance in PFAS of three supplementary allergen families is presented: oleosins, polygalacturonases, and gibberellin-regulated proteins. To support the discussion a few original relevant results were added.

EXPERT OPINION

Both allergenic sources, pollen and food, are submitted to the same stressful environmental changes resulting in an increase of pathogenesis-related proteins in which numerous allergens are found. This might be responsible for the potential increase of PFAS.

Engineering a carbohydrate binding module to enhance chitinase catalytic efficiency on insoluble chitinous substrate

Development of a high-performance chitinase for efficient biotransformation of insoluble chitinous substrate would be highly valuable in industry. In this study, the chitin-binding domains (ChBDs) of chitinase SaChiA4 were successfully modified to improve the enzymatic activity. The engineered substitution variant R-SaChiA4, which had the exogenous ChBD of chitinase ChiA1 from Bacillus circulans WL-12 (ChBD_ChiA1) substituted for its original ChBD_ChiA4, increased its activity by nearly 54% (28.0 U/mg) towards chitin powder, and by 49% towards colloidal chitin, compared with the wild-type. The substrate-binding assay demonstrated that the ChBD could enhance the capacity of enzymatic hydrolysis by promoting substrate affinity, and molecular dynamics simulations indicated that this could be due to hydrophobic interactions in different substrate binding modes. This work advances the understanding of the role of the ChBD, and provides a step towards the achievement of industrial-scale hydrolysis and utilization of insoluble chitin.

Functional metagenomics reveals differential chitin degradation and utilization features across free-living and host-associated marine microbiomes

BACKGROUND

Chitin ranks as the most abundant polysaccharide in the oceans yet knowledge of shifts in structure and diversity of chitin-degrading communities across marine niches is scarce. Here, we integrate cultivation-dependent and -independent approaches to shed light on the chitin processing potential within the microbiomes of marine sponges, octocorals, sediments, and seawater.

RESULTS

We found that cultivatable host-associated bacteria in the genera Aquimarina, Enterovibrio, Microbulbifer, Pseudoalteromonas, Shewanella, and Vibrio were able to degrade colloidal chitin in vitro. Congruent with enzymatic activity bioassays, genome-wide inspection of cultivated symbionts revealed that Vibrio and Aquimarina species, particularly, possess several endo- and exo-chitinase-encoding genes underlying their ability to cleave the large chitin polymer into oligomers and dimers. Conversely, Alphaproteobacteria species were found to specialize in the utilization of the chitin monomer N-acetylglucosamine more often. Phylogenetic assessments uncovered a high degree of within-genome diversification of multiple, full-length endo-chitinase genes for Aquimarina and Vibrio strains, suggestive of a versatile chitin catabolism aptitude. We then analyzed the abundance distributions of chitin metabolism-related genes across 30 Illumina-sequenced microbial metagenomes and found that the endosymbiotic consortium of Spongia officinalis is enriched in polysaccharide deacetylases, suggesting the ability of the marine sponge microbiome to convert chitin into its deacetylated-and biotechnologically versatile-form chitosan. Instead, the abundance of endo-chitinase and chitin-binding protein-encoding genes in healthy octocorals leveled up with those from the surrounding environment but was found to be depleted in necrotic octocoral tissue. Using cultivation-independent, taxonomic assignments of endo-chitinase encoding genes, we unveiled previously unsuspected richness and divergent structures of chitinolytic communities across host-associated and free-living biotopes, revealing putative roles for uncultivated Gammaproteobacteria and Chloroflexi symbionts in chitin processing within sessile marine invertebrates.

CONCLUSIONS

Our findings suggest that differential chitin degradation pathways, utilization, and turnover dictate the processing of chitin across marine micro-niches and support the hypothesis that inter-species cross-feeding could facilitate the co-existence of chitin utilizers within marine invertebrate microbiomes. We further identified chitin metabolism functions which may serve as indicators of microbiome integrity/dysbiosis in corals and reveal putative novel chitinolytic enzymes in the genus Aquimarina that may find applications in the blue biotechnology sector. Video abstract.

Genome-wide identification of chitinase genes in Thalassiosira pseudonana and analysis of their expression under abiotic stresses

BACKGROUND

The nitrogen-containing polysaccharide chitin is the second most abundant biopolymer on earth and is found in the cell walls of diatoms, where it serves as a scaffold for biosilica deposition. Diatom chitin is an important source of carbon and nitrogen in the marine environment, but surprisingly little is known about basic chitinase metabolism in diatoms.

RESULTS

Here, we identify and fully characterize 24 chitinase genes from the model centric diatom Thalassiosira pseudonana. We demonstrate that their expression is broadly upregulated under abiotic stresses, despite the fact that chitinase activity itself remains unchanged, and we discuss several explanations for this result. We also examine the potential transcriptional complexity of the intron-rich T. pseudonana chitinase genes and provide evidence for two separate tandem duplication events during their evolution.

CONCLUSIONS

Given the many applications of chitin and chitin derivatives in suture production, wound healing, drug delivery, and other processes, new insight into diatom chitin metabolism has both theoretical and practical value.

Chitinases and chitinase-like proteins as biomarkers in neurologic disorders

Chitinases are hydrolytic enzymes widely distributed in nature. Despite their physiologic and pathophysiologic roles are not well understood, chitinases are emerging as biomarkers in a broad range of neurologic disorders, where in many cases, protein levels measured in the CSF have been shown to correlate with disease activity and progression. In this review, we will summarize the structural features of human chitinases and chitinase-like proteins and their potential physiologic and pathologic functions in the CNS. We will also review existing evidence for the role of chitinases and chitinase-like proteins as diagnostic and prognostic biomarkers in inflammatory, neurodegenerative diseases, and psychiatric disorders. Finally, we will comment on future perspectives of chitinase studies in neurologic conditions.

Insect Allergens on the Dining Table

Edible insects are important sources of nutrition, particularly in Africa, Asia, and Latin America. Recently, edible insects have gained considerable interest as a possible solution to global exhaustion of the food supply with population growth. However, little attention has been given to the adverse reactions caused by insect consumption. Here, we provide an overview of the food allergens in edible insects and offer insights for further studies. Most of the edible insect allergens identified to date are highly cross-reactive invertebrate pan-allergens such as tropomyosin and arginine kinase. Allergic reactions to these allergens may be cross-reactions resulting from sensitization to shellfish and/or house dust mites. No unique insect allergen specifically eliciting a food allergy has been described. Many of the edible insect allergens described thus far have counterpart allergens in cockroaches, which are an important cause of respiratory allergies, but it is questionable whether inhalant allergens can cause food allergies. Greater effort is needed to characterize the allergens that are unique to edible insects so that safe edible insects can be developed. The changes in insect proteins upon food processing or cooking should also be examined to enhance our understanding of edible insect food allergies.

Intestinal Population in Host with Metabolic Syndrome during Administration of Chitosan and Its Derivatives

Chitosan and its derivatives can alleviate metabolic syndrome by different regulation mechanisms, phosphorylation of AMPK (AMP-activated kinase) and Akt (also known as protein kinase B), suppression of PPAR-γ (peroxisome proliferator-activated receptor-γ) and SREBP-1c (sterol regulatory element–binding proteins), and translocation of GLUT4 (glucose transporter-4), and also the downregulation of fatty-acid-transport proteins, fatty-acid-binding proteins, fatty acid synthetase (FAS), acetyl-CoA carboxylase (acetyl coenzyme A carboxylase), and HMG-CoA reductase (hydroxy methylglutaryl coenzyme A reductase). The improved microbial profiles in the gastrointestinal tract were positively correlated with the improved glucose and lipid profiles in hosts with metabolic syndrome. Hence, this review will summarize the current literature illustrating positive correlations between the alleviated conditions in metabolic syndrome hosts and the normalized gut microbiota in hosts with metabolic syndrome after treatment with chitosan and its derivatives, implying that the possibility of chitosan and its derivatives to serve as therapeutic application will be consolidated. Chitosan has been shown to modulate cardiometabolic symptoms (e.g., lipid and glycemic levels, blood pressure) as well as gut microbiota. However, the literature that summarizes the relationship between such metabolic modulation of chitosan and prebiotic-like effects is limited. This review will discuss the connection among their structures, biological properties, and prebiotic effects for the treatment of metabolic syndrome. Our hope is that future researchers will consider the prebiotic effects as significant contributors to the mitigation of metabolic syndrome.

Chitinases: Therapeutic Scaffolds for Allergy and Inflammation

Background: Chitinases are the evolutionary conserved glycosidic enzymes that are characterized by their ability to cleave the naturally abundant polysaccharide chitin. The potential role of chitinases has been identified in the manifestation of various allergies and inflammatory diseases. In recent years, chitinases inhibitors are emerging as an alluring area of interest for the researchers and scientists and there is a dire need for the development of potential and safe chitinase antagonists for the prophylaxis and treatment of several diseases.

Objective: The present review expedites the role of chitinases and their inhibitors in inflammation and related disorders.

Methods: At first, an exhaustive survey of literature and various patents available related to chitinases were carried out. Useful information on chitinases and their inhibitor was gathered from the authentic scientific databases namely SCOPUS, EMBASE, PUBMED, GOOGLE SCHOLAR, MEDLINE, EMBASE, EBSCO, WEB OF SCIENCE, etc. This information was further analyzed and compiled up to prepare the framework of the review article. The search strategy was conducted by using queries with key terms “ chitin”, “chitinase”, “chitotrisidase”, “acidic mammalian chitinase”, “chitinase inhibitors”, “asthma” and “chitinases associated inflammatory disorders”, etc. The patents were searched using the key terms “chitinases and uses thereof”, “chitinase inhibitors”, “chitin-chitinase associated pathological disorders” etc. from www.google.com/patents, www.freepatentsonline.com, and www.scopus.com.

Results: The present review provides a vision for apprehending human chitinases and their participation in several diseases. The patents available also signify the extended role and effectiveness of chitinase inhibitors in the prevention and treatment of various diseases viz. asthma, acute and chronic inflammatory diseases, autoimmune diseases, dental diseases, neurologic diseases, metabolic diseases, liver diseases, polycystic ovary syndrome, endometriosis, and cancer. In this regard, extensive pre-clinical and clinical investigations are required to develop some novel, potent and selective drug molecules for the treatment of various inflammatory diseases, allergies and cancers in the foreseeable future.

Conclusion: In conclusion, chitinases can be used as potential biomarkers in prognosis and diagnosis of several inflammatory diseases and allergies and the design of novel chitinase inhibitors may act as key and rational scaffolds in designing some novel therapeutic agents in the treatment of variety of inflammatory diseases.

Molecularly Distinct NLRP3 Inducers Mediate Diverse Ratios of Interleukin-1β and Interleukin-18 from Human Monocytes

Inflammasomes cleave and activate interleukin- (IL-) 1β and IL-18 which have both shared and unique biological functions. IL-1β is an important mediator of the acute phase response to infections and tissue damage, whereas IL-18 takes part in activation and tailoring of the adaptive immune response. While IL-1β has served as the prototypic indicator of inflammasome activation, few studies have compared the potential differences in IL-1β and IL-18 production during inflammasome activation. Since these cytokines partake in different immune pathways, the involvement of inflammasome activity in different conditions needs to be described beyond IL-1β production alone. To address a potential heterogeneity in inflammasome functionality, ATP, chitosan, or silica oxide (SiO₂) were used to induce NLRP3 inflammasome activation in THP-1 cells and the subsequent outcomes were quantified. Despite using doses of the inflammasome inducers yielding similar release of IL-1β, SiO₂-stimulated cells showed a lower concentration of released IL-18 compared to ATP and chitosan. Hence, the cells stimulated with SiO₂ responded with a distinctly different IL-18 : IL-1β ratio. The difference in the IL-18 : IL-1β ratio for SiO₂ was constant over different doses. While all downstream responses were strictly dependent on a functional NLRP3 inflammasome, the differences did not depend on the level of gene expression, caspase-1 activity, or pyroptosis. We suggest that the NLRP3 inflammasome response should be considered a dynamic process, which can be described by taking the ratio between IL-1β and IL-18 into account and moving away from an on/off perspective of inflammasome activation.

Cloning, characterization, and functional analysis of chitinase-like protein 1 in the shell of Pinctada fucata

Biomineralization, especially shell formation, is a sophisticated process regulated by various matrix proteins. Pinctada fucata chitinase-like protein 1 (Pf-Clp1), which belongs to the GH18 family, was discovered by our group using in-depth proteomic analysis. However, its function is still unclear. In this study, we first obtained the full-length cDNA sequence of Pf-Clp1 by RACE. Real-time polymerase chain reaction results revealed that Pf-Clp1 was highly expressed in the important biomineralization tissues, the mantle edge and the mantle pallial. We expressed and purified recombinant protein rPf-Clp1 in vitro to investigate the function of Pf-Clp1 on CaCO3 crystallization. Scanning electron microscopy imaging and Raman spectroscopy revealed that rPf-Clp1 was able to affect the morphologies of calcite crystal in vitro. Shell notching experiments suggested that Pf-Clp1 might function as a negative regulator during shell formation in vivo. Knockdown of Pf-Clp1 by RNAi led to the overgrowth of aragonite tablets, further confirming its potential negative regulation on biomineralization, especially in the nacreous layer. Our work revealed the potential function of molluscan Clp in shell biomineralization for the first time and unveiled some new understandings toward the molecular mechanism of shell formation.

Evolutionary analysis and protein family classification of chitin deacetylases in Cryptococcus neoformans

Cryptococcus neoformans is an opportunistic fungal pathogen causing cryptococcal meningoencephalitis. Interestingly, the cell wall of C. neoformans contains chitosan, which is critical for its virulence and persistence in the mammalian host. C. neoformans (H99) has three chitin deacetylases (CDAs), which convert chitin to chitosan. Herein, the classification of the chitin-related protein (CRP) family focused on cryptococcal CDAs was analyzed by phylogenetics, evolutionary pressure (d_N/d_S), and 3D modeling. A phylogenetic tree of 110 CRPs revealed that they can be divided into two clades, CRP I and II with bootstrap values (> 99%). CRP I clade comprises five groups (Groups 1-5) with a total of 20 genes, while CRP II clade comprises sixteen groups (Groups 6-21) with a total of 90 genes. CRP I comprises only fungal CDAs, including all three C. neoformans CDAs, whereas CRP II comprises diverse CDAs from fungi, bacteria, and amoeba, along with other carbohydrate esterase 4 family proteins. All CDAs have the signal peptide, except those from group 11. Notably, CDAs with the putative O-gycosylation site possess either the glycosylphosphatidylinositol (GPI)-anchor motif for CRP I or the chitin-binding domain (CBD) for CRP II, respectively. This evolutionary conservation strongly indicates that the O-glycosylation modification and the presence of either the GPI-anchor motif or the chitin-binding domain is important for fungal CDAs to function efficiently at the cell surface. This study reveals that C. neoformans CDAs carrying GPI anchors have evolved divergently from fungal and bacterial CDAs, providing new insights into evolution and classification of CRP family.

Development of a Chitosan-Vaseline Gauze Dressing with Wound-Healing Properties in Murine Models

Wound dressings are always needed after skin injury; however, most of the dressings still leave room for improvement. Here, we would like to develop an effective dressing with the ability to improve wound healing. A chitosan-Vaseline gauze (CVG) dressing was developed by coating the chitosan mixture and Vaseline on sterile gauze with subsequent drying. Infrared spectroscopy and electron microscopy were used to investigate the miscibility and structure of the dressing. The cytotoxicity and antibacterial nature were evaluated in vitro. The studies of water retention rate, wound healing, and tissue compatibility were carried out over a period of 14 days on full-thickness skin wounds of male Sprague-Dawley rats. It was observed that the CVG dressing demonstrated functional structure by miscibility, non-cytotoxicity, and good antibacterial effects against both Gram-positive and Gram-negative bacteria. The water retention rate incresased up to 25% after applying CVG for 3 hours. Besides, CVG treatment increased angiogenesis and improved microvascular density in wounds. The wounds treated with CVG showed size deduction with new collagen aggregations similar to those in the normal dermis. All the aforementioned results suggest that CVG dressing could be a promising candidate for wound treatment.

Partial purification and characterization of chitinase produced by Bacillus licheniformis B307

The optimal conditions required for chitinase production from Bacillus licheniformis B307 strain, obtained from Syrian soil, were studied. Optimization experiments were carried out under submerged fermentation conditions, and colloidal chitin was the source of carbon. Luria broth medium supplied with 0.5% colloidal chitin was the optimum medium for chitinase production. The maximum chitinase yield was obtained at 30 °C, pH6, incubation time 14 days, and 150 rpm. The optimum chitinase activity was achieved at 60 °C and pH6. The chitinase activity with unmodified medium was 1.9 U/mL which then enhanced about eight folds to reach 14.2 U/mL under optimized submerged fermentation conditions. An extracellular chitinase of Bacillus licheniformis B307 was partially purified using ammonium sulfate precipitation followed by concentration with various sizes of concentrator tubes. The chitinase was partially purified 8.24 fold and specific enzyme activity increased 2.08 fold (2 U/mg). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of partial purified chitinase exhibited a molecular weight (M_r) near to 36 and 42kDa. These results make it possible to invest in this strain to produce chitinase to be used as antifungal, food additives and other applications.

Chitotriosidase: a marker and modulator of lung disease

Chitotriosidase (CHIT1) is a highly conserved and regulated chitinase secreted by activated macrophages; it is a member of the 18-glycosylase family (GH18). CHIT1 is the most prominent chitinase in humans, can cleave chitin and participates in the body's immune response and is associated with inflammation, infection, tissue damage and remodelling processes. Recently, CHIT1 has been reported to be involved in the molecular pathogenesis of pulmonary fibrosis, bronchial asthma, COPD and pulmonary infections, shedding new light on the role of these proteins in lung pathophysiology. The potential roles of CHIT1 in lung diseases are reviewed in this article.

This is the first review of chitotriosidase in lung diseasehttp://bit.ly/2LpZUQI

Chitinases and Chitinase-Like Proteins in Obstructive Lung Diseases - Current Concepts and Potential Applications

Chitinases, enzymes that cleave chitin’s chain to low molecular weight chitooligomers, are widely distributed in nature. Mammalian chitinases belong to the 18-glycosyl-hydrolase family and can be divided into two groups: true chitinases with enzymatic activity (AMCase and chitotriosidase) and chitinase-like proteins (CLPs) molecules which can bind to chitin or chitooligosaccharides but lack enzymatic activity (eg, YKL-40). Chitinases are thought to be part of an innate immunity against chitin-containing parasites and fungal infections. Both groups of these hydrolases are lately evaluated also as chemical mediators or biomarkers involved in airway inflammation and fibrosis. The aim of this article is to present the current knowledge on the potential role of human chitinases and CLPs in the pathogenesis, diagnosis, and course of obstructive lung diseases. We also assessed the potential role of chitinase and CLPs inhibitors as therapeutic targets in chronic obstructive pulmonary disease and asthma.

Comparative transcriptomic analyses of powdery mildew resistant and susceptible cultivated cucumber (Cucumis sativus L.) varieties to identify the genes involved in the resistance to Sphaerotheca fuliginea infection

Background

Cucumber (Cucumis sativus L.) is a widely cultivated vegetable crop, and its yield and quality are greatly affected by various pathogen infections. Sphaerotheca fuliginea is a pathogen that causes powdery mildew (PM) disease in cucumber. However, the genes involved in the resistance to PM in cucumber are largely unknown.

Methods

In our study, a cucumber PM resistant cultivated variety “BK2” and a susceptible cultivated variety “H136” were used to screen and identify differential expressed genes (DEGs) under the S. fuliginea infection.

Results

There were only 97 DEGs between BK2 and H136 under the control condition, suggesting a similarity in the basal gene expression between the resistant and susceptible cultivated varieties. A large number of hormone signaling-related DEGs (9.2% of all DEGs) between resistant and susceptible varieties were identified, suggesting an involvement of hormone signaling pathways in the resistance to PM. In our study, the defense-related DEGs belonging to Class I were only induced in susceptible cultivated variety and the defense-related DEGs belonging to Class II were only induced in resistant cultivated variety. The peroxidase, NBS, glucanase and chitinase genes that were grouped into Class I and II might contribute to production of the resistance to PM in resistant cultivated variety. Furthermore, several members of Pathogen Response-2 family, such as glucanases and chitinases, were identified as DEGs, suggesting that cucumber might enhance the resistance to PM by accelerating the degradation of the pathogen cell walls. Our data allowed us to identify and analyze more potential genes related to PM resistance.

Identification and Functional Analysis of Two Chitin Synthase Genes in the Common Cutworm, Spodoptera litura

Chitin is one the main components of the insect cuticle, and chitin synthase (CHS) is an important enzyme required for chitin formation. CHS has been characterized in various insect species, but the structure and biochemical properties in Spodoptera litura have not been determined. In this study, we identified two CHS genes, SlCHS1 and SlCHS2, which encode proteins with 1565 and 1520 amino acid residues, respectively. Transcriptional analysis suggested that SlCHS1 has a high expression level in the integument whereas SlCHS2 showed the highest expression level in the midgut. During S. litura growth and development, SlCHS1 and SlCHS2 were both predominantly expressed in the fourth-instar larval stage. In addition, the expression of SlCHS1 and SlCHS2 could be induced by 20-hydroxyecdysone (20E). Silencing of SlCHS1 by RNA interference significantly inhibited the pupation and molting of S. litura larvae (RNAi), while knockdown of SlCHS2 had no significant effects on the S. litura phenotype. These results may provide a new molecular target for control of S. litura.

Natural products with preservative properties for enhancing the microbiological safety and extending the shelf-life of seafood: A review

Seafood is highly perishable, presenting a rapid loss of its quality soon after capture. Temperature is the critical parameter that impacts on seafood shelf-life reduction, allowing the growth of foodborne pathogens and spoilage microorganisms. In recent years, the search by additional methods of preserving seafood has increased, able to ensure quality and safety. Several natural preservatives have highlighted and gained considerable attention from the scientific community, consumers, industry, and health sectors as a method with broad action antimicrobial and generally economical. Natural preservatives, from different sources, have been widely studied, such as chitosan from animal sources, essential oils, and plant extracts from a plant source, lactic acid bacteria, and bacteriocins from microbiological sources and organic acid from different sources, all with great potential for use in seafood systems. This review focuses on the natural preservatives studied in seafood matrices, their forms of application, concentrations usually employed, their mechanisms of action, factors that interfere in their use and the synergistic effect of the interactions among the natural preservatives, with a focus for maintenance of quality and ensure of food safety.

Possible Role of Chitin-Like Proteins in the Etiology of Alzheimer's Disease

Chitin is a β-linked straight chain carbohydrate matrix monopolymer prominent in invertebrates, from fungi to arthropods. Surprisingly, chitin is now documented in vertebrates, including humans, a component of vertebrate physiology that has been neglected until now. Chitin levels are elevated in Alzheimer's disease (AD) patients, not only in the central nervous system but also in the cerebrospinal fluid and plasma. Elevated levels of chitin lectin have been reported in patients with AD. Chitinase activity varies widely in the human population. Chitin levels can increase in individuals with intrinsically low chitinase activity. Elevated amounts of chitin can reflect accumulation of the small chitin fragments that remain wherever rapid hyaluronan synthesis occurs. Another source of chitin may be from remote fungal infections. Chitin can be toxic for neurons, and its accumulation may lead to the development of AD. We present new suggestions for animal models and treatment modalities that could prove useful in future research endeavors. An unexpected connection with Gaucher's disease patients and their heterozygote relatives is also identified. These chitin-related mechanisms are novel approaches to AD whose etiology until now has defied explication.

Starch-binding domains as CBM families-history, occurrence, structure, function and evolution

The term "starch-binding domain" (SBD) has been applied to a domain within an amylolytic enzyme that gave the enzyme the ability to bind onto raw, i.e. thermally untreated, granular starch. An SBD is a special case of a carbohydrate-binding domain, which in general, is a structurally and functionally independent protein module exhibiting no enzymatic activity but possessing potential to target the catalytic domain to the carbohydrate substrate to accommodate it and process it at the active site. As so-called families, SBDs together with other carbohydrate-binding modules (CBMs) have become an integral part of the CAZy database (http://www.cazy.org/). The first two well-described SBDs, i.e. the C-terminal Aspergillus-type and the N-terminal Rhizopus-type have been assigned the families CBM20 and CBM21, respectively. Currently, among the 85 established CBM families in CAZy, fifteen can be considered as families having SBD functional characteristics: CBM20, 21, 25, 26, 34, 41, 45, 48, 53, 58, 68, 69, 74, 82 and 83. All known SBDs, with the exception of the extra long CBM74, were recognized as a module consisting of approximately 100 residues, adopting a β-sandwich fold and possessing at least one carbohydrate-binding site. The present review aims to deliver and describe: (i) the SBD identification in different amylolytic and related enzymes (e.g., CAZy GH families) as well as in other relevant enzymes and proteins (e.g., laforin, the β-subunit of AMPK, and others); (ii) information on the position in the polypeptide chain and the number of SBD copies and their CBM family affiliation (if appropriate); (iii) structure/function studies of SBDs with a special focus on solved tertiary structures, in particular, as complexes with α-glucan ligands; and (iv) the evolutionary relationships of SBDs in a tree common to all SBD CBM families (except for the extra long CBM74). Finally, some special cases and novel potential SBDs are also introduced.

Safety evaluation of the food enzyme chitinase from Streptomyces violaceoruber (strain pChi)

The food enzyme, a chitinase (EC 3.2.1.14), is produced with the genetically modified Streptomyces violaceoruber strain pChi by Nagase. No information was provided regarding the presence of antimicrobial resistance genes in the production strain, other than that used in the genetic modification. The chitinase is intended to be used in baking processes. Based on the maximum use levels recommended, dietary exposure to the food enzyme-total organic solids (TOS) was estimated on the basis of individual data from the EFSA Comprehensive European Food Consumption Database. The exposure estimate is up to 0.829 mg TOS/kg body weight per day in European populations. Genotoxicity tests did not raise a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-days oral toxicity study in rats. The Panel identified a no observed adverse effect level at the highest dose tested of 791 mg TOS/kg body weight, which, compared with the dietary exposure, results in margin of exposure of at least 1,171. Similarity of the amino acid sequence to those of known allergens was searched and no matches were found. The Panel considered that there are no indications for food allergic reactions to this chitinase. Based on the data provided and the derived margin of exposure, the Panel concluded that the food enzyme chitinase produced with the genetically modified S. violaceoruber strain pChi does not give rise to safety concerns arising from the toxicological studies and the production process under the intended conditions of use. The CEP Panel was unable to conclude on the absence of viable cells and DNA from the genetically modified production strain in the food enzyme, for which uncertainty remains on the possible presence of gene(s) conferring antimicrobial resistance.

Comparative proteomic analysis provides insights into the complex responses to Pseudoperonospora cubensis infection of cucumber (Cucumis sativus L.)

Cucumber (Cucumis sativus L.) is an important crop distributed in many countries. Downy mildew (DM) caused by the obligate oomycete Pseudoperonospora cubensis is especially destructive in cucumber production. So far, few studies on the changes in proteomes during the P. cubensis infection have been performed. In the present study, the proteomes of DM-resistant variety ‘ZJ’ and DM-susceptible variety ‘SDG’ under the P. cubensis infection were investigated. In total, 6400 peptides were identified, 5629 of which were quantified. KEGG analysis showed that a number of metabolic pathways were significantly altered under P. cubensis infection, such as terpenoid backbone biosynthesis, and selenocompound metabolism in ZJ, and starch and sucrose metabolism in SDG. For terpenoid backbone synthesis, 1-deoxy-D-xylulose-5-phosphate synthase, 1-deoxy-D-xylulose 5-phosphate reductoisomerase, 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase, 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase, and geranylgeranyl pyrophosphate synthase were significantly accumulated in ZJ rather than in SDG, suggesting that pathogen-induced terpenoids accumulation might play an important role in the resistance against P. cubensis infection. Furthermore, a number of pathogenesis-related proteins, such as endochitinases, peroxidases, PR proteins and heat shock proteins were identified as DAPs, suggesting that DM resistance was controlled by a complex network. Our data allowed us to identify and screen more potential proteins related to the DM resistance.

Immune-enhancing effects of anionic macromolecules extracted from Codium fragile on cyclophosphamide-treated mice

Immune-regulation and homeostasis are critical in cancer therapy and immunomodulatory biomaterials have been used to decrease side effects of immunosuppressant drugs. Anionic macromolecules (CFAMs) were isolated from the seaweed Codium fragile, and its immune-enhancing biological activities were examined in CY-induced immunosuppressed mice. CFAMs improved the splenic lymphocyte proliferation, NK cell activity, and spleen index. The expression of immune-associated genes was highly upregulated in splenic lymphocytes, and gene expression was differently regulated according to mitogens such as T-cell (Con A) and B-cell (LPS) mitogens. Additionally, CFAMs boosted the proliferation, NO production, and phagocytosis of peritoneal macrophages. CFAMs also considerably stimulated immune-associated gene expression in peritoneal macrophages. Moreover, our results showed CFAMs mediated its immune-enhancing effects via the MAPK pathway. These suggested CFAMs can be used as a potent immunomodulatory material under immune-suppressive condition. Furthermore, CFAMs may also be used as a bio-functional and pharmaceutical material for improving human health and immunity.

Danger-Associated Molecular Patterns (DAMPs): the Derivatives and Triggers of Inflammation

PURPOSE OF REVIEW

Allergen is an umbrella term for irritants of diverse origin. Along with other offenders such as pathogens, mutagens, xenobiotics, and pollutants, allergens can be grouped as inflammatory agents. Danger-associated molecular patterns (DAMPs) are altered metabolism products of necrotic or stressed cells, which are deemed as alarm signals by the innate immune system. Like inflammation, DAMPs play a role in correcting the altered physiological state, but in excess, they can be lethal due to their signal transduction roles. In a vicious loop, inflammatory agents are DAMP generators and DAMPs create a pro-inflammatory state. Only a handful of DAMPs such as uric acid, mtDNA, extracellular ATP, HSPs, amyloid β, S100, HMGB1, and ECM proteins have been studied till now. A large number of DAMPs are still obscure, in need to be unveiled. The identification and functional characterization of those DAMPs in inflammation pathways can be insightful.

RECENT FINDINGS

As inflammation and immune activation have been implicated in almost all pathologies, studies on them have been intensified in recent times. Consequently, the pathologic mechanisms of various DAMPs have emerged. Following PRR ligation, the activation of inflammasome, MAPK, and NF-kB is some of the common pathways. The limited number of recognized DAMPs are only a fraction of the vast array of other DAMPs. In fact, any misplaced or abnormal level of metabolite can be a DAMP. Sophisticated analysis studies can reveal the full profile of the DAMPs. Lowering the level of DAMPs is useful therapeutic intervention but certainly not as effective as avoiding the DAMP generators, i.e., the inflammatory agents. So, rather than mitigating DAMPs, efforts should be focused on the elimination of inflammatory agents.

Cathepsins: Proteases that are vital for survival but can also be fatal

The state of enzymes in the human body determines the normal physiology or pathology, so all the six classes of enzymes are crucial. Proteases, the hydrolases, can be of several types based on the nucleophilic amino acid or the metal cofactor needed for their activity. Cathepsins are proteases with serine, cysteine, or aspartic acid residues as the nucleophiles, which are vital for digestion, coagulation, immune response, adipogenesis, hormone liberation, peptide synthesis, among a litany of other functions. But inflammatory state radically affects their normal roles. Released from the lysosomes, they degrade extracellular matrix proteins such as collagen and elastin, mediating parasite infection, autoimmune diseases, tumor metastasis, cardiovascular issues, and neural degeneration, among other health hazards. Over the years, the different types and isoforms of cathepsin, their optimal pH and functions have been studied, yet much information is still elusive. By taming and harnessing cathepsins, by inhibitors and judicious lifestyle, a gamut of malignancies can be resolved. This review discusses these aspects, which can be of clinical relevance.