N-acetyl-beta-D-glucosaminidase (NAG) isoenzymes release from human monocyte-derived macrophages in response to zymosan and human recombinant interferon-gamma

The hidden base of the iceberg: gut peptidoglycome dynamics is foundational to its influence on the host

The intestinal microbiota of humans includes a highly diverse range of bacterial species. All these bacteria possess a cell wall, composed primarily of the macromolecule peptidoglycan. As such, the gut also harbors an abundant and varied peptidoglycome. A remarkable range of host physiological pathways are regulated by peptidoglycan fragments that originate from the gut microbiota and enter the host system. Interactions between the host system and peptidoglycan can influence physiological development and homeostasis, promote health, or contribute to inflammatory disease. Underlying these effects is the interplay between microbiota composition and enzymatic processes that shape the intestinal peptidoglycome, dictating the types of peptidoglycan generated, that subsequently cross the gut barrier. In this review, we highlight and discuss the hidden and emerging functional aspects of the microbiome, i.e. the hidden base of the iceberg, that modulate the composition of gut peptidoglycan, and how these fundamental processes are drivers of physiological outcomes for the host.

Mannose Receptor Mediates the Activation of Chitooligosaccharides on Blunt Snout Bream (Megalobrama amblycephala) Macrophages

Chitooligosaccharide (COS) is an important immune enhancer and has been proven to have a variety of biological activities. Our previous research has established an M1 polarization mode by COS in blunt snout bream (Megalobrama amblycephala) macrophages, but the mechanism of COS activation of blunt snout bream macrophages remains unclear. In this study, we further explored the internalization mechanism and signal transduction pathway of chitooligosaccharide hexamer (COS6) in blunt snout bream macrophages. The results showed that mannose receptor C-type lectin-like domain 4-8 of M. amblycephala (MaMR CTLD4-8) could recognize and bind to COS6 and mediate COS6 into macrophages by both clathrin-dependent and caveolin-dependent pathways. In the inflammatory response of macrophages activated by COS6, the gene expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and nitric oxide synthase 2 (NOS2) was significantly inhibited after MaMR CTLD4-8-specific antibody blockade. However, even if it was blocked, the expression of these inflammation-related genes was still relatively upregulated, which suggested that there are other receptors involved in immune regulation. Further studies indicated that MaMR CTLD4-8 and Toll-like receptor 4 (TLR4) cooperated to regulate the pro-inflammatory response of macrophages caused by COS6. Taken together, these results revealed that mannose receptor (MR) CTLD4-8 is indispensable in the process of recognition, binding, internalization, and immunoregulation of COS in macrophages of blunt snout bream.

Temperature-dependent mucosal permeation kinetics of stigmasterol microspheres: In vivo mice model antioral candidiasis study

Evaluation of mucosal permeation of stigmasterol from the glutaraldehyde cross linked chitosan microspheres at increasing experimental temperatures was performed. The activation energy of permeation, partition, and diffusion were estimated to understand the permeation kinetic with respect to the temperature. The formulation depicting least activation energy possessed the increased permeation thresholds of drug at the site of application. The encapsulation efficacy and mucoadhesive strength were found to be directly proportional to the polymer-emulsifier ratio. Decreased intensity in crystallography directed the molecular dispersion of microencapsulated drug. The depleted enthalpic phase transition in thermogram affirmed the stigmasterol encapsulation. The sphericity and the size of microspheres were determined by scanning electron photo micrograph. The in vivo quantification of oral Candida infection with different statistical approach and histopathological observation of infected tongue of mice on treatment with the stigmasterol encapsulated microspheres showed significant anti oral candidiasis activity by reduction of fungal colony count and recovery of papillae, reorganization of basal cell layer and newly formed papillae during 21-28 days of treatment.

Marine medicinal glycomics

Glycomics is an international initiative aimed to understand the structure and function of the glycans from a given type of cell, tissue, organism, kingdom or even environment, as found under certain conditions. Glycomics is one of the latest areas of intense biological research. Glycans of marine sources are unique in terms of structure and function. They differ considerably from those of terrestrial origin. This review discusses the most known marine glycans of potential therapeutic properties. They are chitin, chitosan, and sulfated polysaccharides named glycosaminoglycans, sulfated fucans, and sulfated galactans. Their medical actions are very broad. When certain structural requirements are found, these glycans can exhibit beneficial effects in inflammation, coagulation, thrombosis, cancer growth/metastasis, and vascular biology. Both structure and therapeutic mechanisms of action of these marine glycans are discussed here in straight context with the current glycomic age through a project suggestively named marine medicinal glycomics.

Chitins and chitosans as immunoadjuvants and non-allergenic drug carriers

Due to the fact that some individuals are allergic to crustaceans, the presumed relationship between allergy and the presence of chitin in crustaceans has been investigated. In vivo, chitin is part of complex structures with other organic and inorganic compounds: in arthropods chitin is covalently linked to proteins and tanned by quinones, in fungi it is covalently linked to glucans, while in bacteria chitin is diversely combined according to Gram(+/-) classification. On the other hand, isolated, purified chitin is a plain polysaccharide that, at the nano level, presents itself as a highly associated structure, recently refined in terms of regularity, nature of bonds, crystallinity degree and unusual colloidal behavior. Chitins and modified chitins exert a number of beneficial actions, i.e., (i) they stimulate macrophages by interacting with receptors on the macrophage surface that mediate the internalization of chitin particles to be degraded by lysozyme and N-acetyl-beta-glucosaminidase (such as Nod-like, Toll-like, lectin, Dectin-1, leukotriene 134 and mannose receptors); (ii) the macrophages produce cytokines and other compounds that confer non-specific host resistance against bacterial and viral infections, and anti-tumor activity; (iii) chitin is a strong Th1 adjuvant that up-regulates Th1 immunity induced by heat-killed Mycobacterium bovis, while down- regulating Th2 immunity induced by mycobacterial protein; (iv) direct intranasal application of chitin microparticles into the lung was also able to significantly down-regulate allergic response to Dermatophagoids pteronyssinus and Aspergillus fumigatus in a murine model of allergy; (v) chitin microparticles had a beneficial effect in preventing and treating histopathologic changes in the airways of asthmatic mice; (vi) authors support the fact that chitin depresses the development of adaptive type 2 allergic responses. Since the expression of chitinases, chitrotriosidase and chitinase-like proteins is greatly amplified during many infections and diseases, the common feature of chitinase-like proteins and chitinase activity in all organisms appears to be the biochemical defense of the host. Unfortunately, conceptual and methodological errors are present in certain recent articles dealing with chitin and allergy, i.e., (1) omitted consideration of mammalian chitinase and/or chitotriosidase secretion, accompanied by inactive chitinase-like proteins, as an ancestral defensive means against invasion, capable to prevent the insurgence of allergy; (2) omitted consideration of the fact that the mammalian organism recognizes more promptly the secreted water soluble chitinase produced by a pathogen, rather than the insoluble and well protected chitin within the pathogen itself; (3) superficial and incomplete reports and investigations on chitin as an allergen, without mentioning the potent allergen from crustacean flesh, tropomyosine; (4) limited perception of the importance of the chemical/biochemical characteristics of the isolated chitin or chitosan for the replication of experiments and optimization of results; and (5) lack of interdisciplinarity. There is quite a large body of knowledge today on the use of chitosans as biomaterials, and more specifically as drug carriers for a variety of applications: the delivery routes being the same as those adopted for the immunological studies. Said articles, that devote attention to the safety and biocompatibility aspects, never reported intolerance or allergy in individuals and animals, even when the quantities of chitosan used in single experiments were quite large. Therefore, it is concluded that crab, shrimp, prawn and lobster chitins, as well as chitosans of all grades, once purified, should not be considered as "crustacean derivatives", because the isolation procedures have removed proteins, fats and other contaminants to such an extent as to allow them to be classified as chemicals regardless of their origin.

Chitosan-based delivery systems for protein therapeutics and antigens

Therapeutic peptides/proteins and protein-based antigens are chemically and structurally labile compounds, which are almost exclusively administered by parenteral injections. Recently, non-invasive mucosal routes have attracted interest for administration of these biotherapeutics. Chitosan-based delivery systems enhance the absorption and/or cellular uptake of peptides/proteins across mucosal sites and have immunoadjuvant properties. Chitosan is a mucoadhesive polysaccharide capable of opening the tight junctions between epithelial cells and it has functional groups for chemical modifications, which has resulted in a large variety of chitosan derivatives with tunable properties for the aimed applications. This review provides an overview of chitosan-based polymers for preparation of both therapeutic peptides/protein and antigen formulations. The physicochemical properties of these carrier systems as well as their applications in protein and antigen delivery through parenteral and mucosal (particularly nasal and pulmonary) administrations are summarized and discussed.

Chitin, chitinases and chitinase-like proteins in allergic inflammation and tissue remodeling

Chitin, the second most abundant polysaccharide in nature after cellulose, consist exoskeleton of lower organisms such as fungi, crustaceans and insects except mammals. Recently, several studies evaluated immunologic effects of chitin in vivo and in vitro and revealed new aspects of chitin regulation of innate and adaptive immune responses. It has been shown that exogenous chitin activates macrophages and other innate immune cells and also modulates adaptive type 2 allergic inflammation. These studies further demonstrate that chitin stimulate macrophages by interacting with different cell surface receptors such as macrophage mannose receptor, toll-like receptor 2 (TLR-2), C-type lectin receptor Dectin-1, and leukotriene B4 receptor (BLT1). On the other hand, a number of chitinase or chitinase-like proteins (C/CLP) are ubiquitously expressed in the airways and intestinal tracts from insects to mammals. In general, these chitinase family proteins confer protective functions to the host against exogenous chitin-containing pathogens. However, substantial body of recent studies also set light on new roles of C/CLP in the development and progression of allergic inflammation and tissue remodeling. In this review, recent findings on the role of chitin and C/CLP in allergic inflammation and tissue remodeling will be highlighted and controversial and unsolved issues in this field of studies will be discussed.

Chitin regulation of immune responses: an old molecule with new roles

Chitin, the second most abundant polysaccharide in nature, is commonly found in lower organisms such as fungi, crustaceans, and insects, but not in mammals. Although the non-specific anti-viral and anti-tumor activities of chitin/chitin derivatives were described two decades ago, the immunological effects of chitin have been only recently been addressed. Recent studies demonstrated that chitin has complex and size-dependent effects on innate and adaptive immune responses including the ability to recruit and activate innate immune cells and induce cytokine and chemokine production via a variety of cell surface receptors including macrophage mannose receptor, toll-like receptor 2 (TLR-2), and Dectin-1. They also demonstrated adjuvant effects of chitin in allergen-induced type 1 or type 2 inflammation and provided insights into the important roles of chitinases and chitinase-like proteins (C/CLP) in pulmonary inflammation. The status of the field and areas of controversy are highlighted.

Chitin-based Embolic Materials in the Renal Artery of Rabbits: Pathologic Evaluation of an Absorbable Particulate Agent

PURPOSE

To prospectively evaluate the tissue reaction to and the embolic effect and absorption of chitin and chitosan microspheres and polyvinyl alcohol (PVA) in the renal artery of rabbits.

MATERIALS AND METHODS

This experiment was performed in accordance with regulations on animal care and experiments. Thirty-six New Zealand white rabbits were divided into four groups according to the materials (PVA, chitin particles, and chitosan particles, and chitosan microspheres; diameter, 150-250 microm) used for embolization of the right renal artery. A rabbit from each group was sacrificed 1 and 3 days and 1, 2, 4, 8, 16, 24, and 32 weeks after embolization. Gross and microscopic pathologic findings were examined with hematoxylin-eosin, Masson trichrome, and Victoria blue staining.

RESULTS

Gross pathologic findings were examined, and swelling of embolized kidneys was observed 1 and 3 days after embolization, whereas shrinkage of the embolized kidneys was consistently seen after 2 weeks, with a hard consistency and nodular surfaces being noted. At histologic analysis, chitosan microspheres filled the lumen more compactly than did other particles. With PVA, a large amount of capillary formations occurred within the embolized arteries, whereas chitin particles and chitosan microspheres showed a lower rate of capillary formation. The shape of all embolic materials remained intact until week 8, at which time the materials gradually decreased in size and number. The chitosan particles and the chitosan microspheres were absorbed around weeks 16 and 24, respectively.

CONCLUSION

Chitosan microspheres have great potential as a new embolic material since they block blood vessels more compactly with a lower rate of capillary formation. This material is biocompatible, and it is absorbed 24 weeks after embolization.

Review of novel particulate antigen delivery systems with special focus on treatment of type I allergy

For the treatment of infectious diseases, cancer and allergy, the directed induction of an appropriate immune response is the ultimate goal. Therefore, with the development of pure, often very small proteins, peptides or DNA by molecular biology techniques, the research for suitable adjuvants or delivery systems became increasingly important. Particle formulations are made of a variety of materials, including lipids, proteins or amino acids, polysaccharides, polyacrylic substances or organic acids. Microparticles serve as vehicles and provide a depot for the entrapped or coupled antigen. The release occurs in a pulsatile or continuous manner, a feature, which is well controllable for many particulate systems. Particles attract antigen presenting cells to the administration site, thereby guaranteeing the efficient presentation of the antigen to the immune system. Importantly, particles also protect the entrapped substance. This is especially necessary after oral application to avoid gastric or tryptic breakdown. In this article, the design and construction of different antigen delivery systems and their immune effects, with special focus on the suitability for allergy treatment, are discussed.

Intranasal application of chitin microparticles down-regulates symptoms of allergic hypersensitivity to Dermatophagoides pteronyssinus and Aspergillus fumigatus in murine models of allergy

BACKGROUND

Previous studies have demonstrated that chitin in the form of microparticles that can be phagocytosed is a potent macrophage stimulator and promotes a Th1 cytokine response and it has been shown that oral administration of chitin microparticles is effective in down-regulating serum IgE and lung eosinophilia in a mouse model of ragweed allergy. To date there have been no studies on the effectivness of directly applying chitin microparticles to the respiratory tract as a treatment for allergic symptoms.

OBJECTIVE

To test the effectivness of chitin microparticles when given intranasally as a treatment for the symptoms of respiratory allergy and allergic asthma and to compare its effectivness in two different mouse models of allergy, namely to Dermatophagoides pteronyssinus and Aspergilhus fumigatus.

RESULTS

The intranasal application of microgram doses of chitin microparticles is an effective treatment for reducing serum IgE and peripheral blood eosinophilia, airway hyper-responsiveness and lung inflammation in both allergy models results in elevation in Th1 cytokines IL-12, IFN-gamma and TNF-alpha and reduction in IL-4 production during allergen challenge.

CONCLUSION

Chitin microparticle suspensions have Th1 immunostimulatory properties and are effective when administered intranasally in mice. The stimulation of the nasal associated lymphoid tissue with chitin microparticles could offer a novel and natural approach to treating allergic disease in humans.

Analytical biochemistry and clinical significance of N-acetyl-beta-D-glucosaminidase and related enzymes

Human N-acetyl-beta-D-glucosaminidase, N-acetyl-alpha-D-glucosaminidase, endo-beta-N-acetylglucosaminidase, hexosaminidase, beta-N-acetylgalactosaminidase and glucocerebrosidase have not been so widely studied as the beta-N-acetylhexosaminidases in bacteria, fungi and arthropods. Their biochemical role has been elucidated, however, and their urinary and plasma determination is being adopted for the early detection of diseases before clinical manifestation, in particular for hypertension, renal injuries and disorders, depression and lysosomal storage diseases. The spectrophotometric determinations of N-acetyl-beta-D-glucosaminidase, most often done with 3-cresolsulphone phthaleinyl N-acetyl-beta-D-glucosaminide, have been recently simplified and adapted to automatic instruments.

Oral administration of chitin down-regulates serum IgE levels and lung eosinophilia in the allergic mouse

Previous studies showed that local macrophages phagocytose nonantigenic chitin particles (1-10 micrometer polymers of N-acetyl-<cmd SC>d<cmd /SC> -glucosamine) through mannose receptors and produce IL-12, IL-18, and TNF-alpha. These cytokines lead to the production of IFN-gamma by NK cells. To determine whether chitin could down-regulate Th2 responses, chitin was given orally (8 mg/day for 3 days before and 13 days during ragweed allergen immunization) in BALB/c and C57BL/6 mice. These ragweed-immunized mice were given ragweed intratracheally on day 11. Three days after the challenge, the immunized mice with saline (controls) showed increases in serum IgE levels and lung eosinophil numbers. The chitin treatment resulted in decreases of these events in both strains. To dissect the inhibitory mechanisms of Th2 responses, spleen cells (4 x 106 cells/ml) isolated from the ragweed-immunized mice (controls) were cultured in the presence of ragweed and/or chitin for 3 days (recall responses). Ragweed alone stimulated the production of IL-4 (0.6 ng/ml), IL-5 (20 U/ml), and IL-10 (3.2 ng/ml), but not IFN-gamma. Ragweed/chitin stimulation resulted in significant decreases of IL-4, IL-5, and IL-10 levels and the production of IFN-gamma (48 U/ml). Moreover, spleen cells isolated from the chitin-treated mice showed ragweed-stimulated IFN-gamma production (15 U/ml) and significantly lower levels of the Th2 cytokines, suggesting that the immune responses were redirected toward a Th1 response. Collectively, these results indicate that chitin-induced innate immune responses down-regulate Th2-facilitated IgE production and lung eosinophilia in the allergic mouse.

Alveolar macrophage priming by intravenous administration of chitin particles, polymers of N-acetyl-D-glucosamine, in mice

Intravenous (i.v.) administration of phagocytosable chitin particles (1 to 10 microm) in C57BL/6 mice and SCID mice primed alveolar macrophages (Mphi) within 3 days to yield up to a 50-fold increase in their oxidative burst when elicited in vitro with phorbol myristate acetate (PMA). C57BL/6 mice pretreated with monoclonal antibodies (MAbs) against mouse gamma interferon (IFN-gamma) or NK1.1 showed a markedly decreased level of alveolar Mphi priming following injection of chitin particles. To confirm IFN-gamma production in vitro, spleen cells isolated from normal C57BL/6 mice and SCID mice were cultured with chitin particles. Significant IFN-gamma production was observed following stimulation with chitin but not with chitosan or latex beads. When spleen cells were treated with anti-NK1.1 MAb, IFN-gamma production was significantly inhibited. Another set of experiments showed that when C57BL/6 mice were pretreated i.v. with a small dose IFN-gamma, a higher level of priming was induced with not only phagocytosable chitin particles but also phagocytosable chitosan and even latex beads. Likewise, the spleen cell cultures preconditioned with IFN-gamma provided an up-regulation of IFN-gamma production by these phagocytosable particles. Taken together, the in vivo and in vitro results suggest that (i) the alveolar Mphi priming mechanism is due, at least in part, to direct activation of Mphi by IFN-gamma, which is produced by NK1.1+ CD4- cells; (ii) IFN-gamma would have an autocrine-like effect on Mphi and make them more responsive to particle priming; and (iii) phagocytosis of particulates, probably by a postmembrane event such as interiorization, appears to be important for the up-regulation of alveolar Mphi priming and IFN-gamma production.

N-acetyl-B-D-glucosaminidase isoenzymes in the diagnosis of poisoning and kidney diseases

Damaged lysosomes from renal tubular cells are, to the greatest degree, the source of activity of NAG in urine. Besides this, the enzyme can appear as a result of degranulation of granulocytes (PMN), active infection of the urinary system as also from serum as a result of glomerular filtration during damage to the glomerular basement membrane. For the purpose of explaining the source of origin of the enzyme in urine, NAG was separated into isoenzymes from the kidneys, granulocytes and serum for comparison with isoenzymes in physiological and pathological urines after ethylene glycol poisoning, and glomerulonephritis, respectively. The separation was made by column ion-exchange chromatography on DEAE-52 cellulose and by electrophoresis in 7% polyacrylamide gel. In addition, the thermostability of isolated isoenzymes was compared.

Lysosomal enzyme activities in liver and sera from guinea pigs fed oil related to the toxic oil syndrome

beta-N-Acetylglucosaminidase and beta-galactosidase activities were determined in serum and liver from guinea pigs fed "toxic oil" (related to cases of TOS) under different experimental conditions. The results obtained were compared with those of guinea pigs fed non "toxic oil" (case-unrelated oil; controls 1) and animals fed no oil (controls 2). In serum, both activities were significantly increased after all treatments with case-related oil as compared with controls 1 and 2. In the liver, beta-galactosidase activity did not show significant differences in any of the treatments when compared with controls 2. However, NAG activity decreased significantly after 7 days of treatment with non-heated oil--either case-related or not--when compared with controls 2; it also decreased significantly after 28 days of treatment with heated case-unrelated oil, both with respect to controls 2 and the animals fed case-related oil. Liver weights tended to increase in the animals fed oil--toxic or not--with respect to those of the livers from untreated animals. Morphologically, a slight vacuolization of the hepatocytes was observed in some of the samples from the treated animals.