Leishmania braziliensis enhances monocyte responses to promote anti-tumor activity

Innate immune cells can undergo long-term functional reprogramming after certain infections, a process called trained immunity (TI). Here, we focus on antigens of Leishmania braziliensis, which induced anti-tumor effects via trained immunity in human monocytes. We reveal that monocytes exposed to promastigote antigens of L. braziliensis develop an enhanced response to subsequent exposure to Toll-like receptor (TLR)2 or TLR4 ligands. Mechanistically, the induction of TI in monocytes by L. braziliensis is mediated by multiple pattern recognition receptors, changes in metabolism, and increased deposition of H3K4me3 at the promoter regions of immune genes. The administration of L. braziliensis exerts potent anti-tumor capabilities by delaying tumor growth and prolonging survival of mice with non-Hodgkin lymphoma. Our work reveals mechanisms of TI induced by L. braziliensis in vitro and identifies its potential for cancer immunotherapy.

Synthesis of a unique mannose α-1-phosphate side chain moiety found in Candida auris cell wall mannan

Candida auris is an emerging fungal pathogen that has become a world-wide public health threat. While there have been numerous studies into the nature, composition and structure of the cell wall of Candida albicans and other Candida species, much less is known about the C. auris cell wall. We have shown that C. auris cell wall mannan contains a unique phosphomannan structure which distinguishes C. auris mannan from the mannans found in other fungal species. Specifically, C. auris exhibits two unique acid-labile mannose α-1-phosphate (Manα1PO4) sidechains that are absent in other fungal mannans and fungal pathogens. This unique mannan structural feature presents an opportunity for the development of vaccines, therapeutics, diagnostic tools and/or research reagents that target C. auris. Herein, we describe the successful synthesis and structural characterization of a Manα1PO4-containing disaccharide moiety that mimics the phosphomannan found in C. auris. Additionally, we present evidence that the synthetic Manα1PO4 glycomimetic is specifically recognized and bound by cell surface pattern recognition receptors, i.e. rhDectin-2, rhMannose receptor and rhMincle, that are known to play important roles in the innate immune response to C. auris as well as other fungal pathogens. The synthesis of the Manα1PO4 glycomimetic may represent an important starting point in the development of vaccines, therapeutics, diagnostics and research reagents which target a number of C. auris clinical strains. In addition, these data provide new insights and understanding into the structural biology of this unique fungal pathogen.

An adjuvant strategy enabled by modulation of the physical properties of microbial ligands expands antigen immunogenicity

Activation of the innate immune system via pattern recognition receptors (PRRs) is key to generate lasting adaptive immunity. PRRs detect unique chemical patterns associated with invading microorganisms, but whether and how the physical properties of PRR ligands influence the development of the immune response remains unknown. Through the study of fungal mannans, we show that the physical form of PRR ligands dictates the immune response. Soluble mannans are immunosilent in the periphery but elicit a potent pro-inflammatory response in the draining lymph node (dLN). By modulating the physical form of mannans, we developed a formulation that targets both the periphery and the dLN. When combined with viral glycoprotein antigens, this mannan formulation broadens epitope recognition, elicits potent antigen-specific neutralizing antibodies, and confers protection against viral infections of the lung. Thus, the physical properties of microbial ligands determine the outcome of the immune response and can be harnessed for vaccine development.

Isolation, Physicochemical Characterization, Labeling, and Biological Evaluation of Mannans and Glucans

The cell wall contains mannans and glucans that are recognized by the host immune system. In this chapter, we will describe the methods to isolate mannans and glucans from the C. albicans cell wall. In addition, we describe how to determine purity, molecular size, and structure of the mannans and glucans. We also detail how to prepare the carbohydrates for in vitro, ex vivo, or in vivo use by describing endotoxin removal (depyrogenation), derivatization, and labeling and evaluation of bioactivity.

An adjuvant strategy enabled by modulation of the physical properties of fungal mannans elicits pan-coronavirus reactive anti-SARS-CoV-2 Spike antibodies

Activation of the innate immune system via pattern recognition receptors (PRRs) is key to generate long-lasting adaptive immunity. While it is known that PRRs detect unique chemical patterns associated with invading microorganism, if and how the physical properties of PRR ligands influence development of the immune response is largely overlooked. Through the study of fungal mannans we present data that put the physical form of PRR ligands at the center of the process that determines the outcome of the immune response. Soluble mannans are immunosilent in the periphery but elicit a potent pro-inflammatory response in the draining lymph node (dLN). By modulating the physical form of mannans, we developed a formulation that targets both periphery and dLN. When combined with SARS-CoV-2 Spike, this formulation elicits neutralizing anti-SARS-CoV-2 antibodies that cross-react with pathogenic coronaviruses. Thus, the physical properties of fungal ligands can be harnessed for rational adjuvant design and vaccine development.

Immunoregulatory Activity of the Natural Product Laminarin Varies Widely as a Result of Its Physical Properties

Ligation of Dectin-1 by fungal glucans elicits a Th17 response that is necessary for clearing many fungal pathogens. Laminarin is a (1→3, 1→6)-β-glucan that is widely reported to be a Dectin-1 antagonist, however, there are reports that laminarin is also a Dectin-1 agonist. To address this controversy, we assessed the physical properties, structure, purity, Dectin-1 binding, and biological activity of five different laminarin preparations from three different commercial sources. The proton nuclear magnetic resonance analysis indicated that all of the preparations contained laminarin although their molecular mass varied considerably (4400-34,400 Da). Two of the laminarins contained substantial quantities of very low m.w. compounds, some of which were not laminarin. These low m.w. moieties could be significantly reduced by extensive dialysis. All of the laminarin preparations were bound by recombinant human Dectin-1 and mouse Dectin-1, but the affinity varied considerably, and binding affinity did not correlate with Dectin-1 agonism, antagonism, or potency. In both human and mouse cells, two laminarins were Dectin-1 antagonists and two were Dectin-1 agonists. The remaining laminarin was a Dectin-1 antagonist, but when the low m.w. moieties were removed, it became an agonist. We were able to identify a laminarin that is a Dectin-1 agonist and a laminarin that is Dectin-1 antagonist, both of which are relatively pure preparations. These laminarins may be useful in elucidating the structure and activity relationships of glucan/Dectin-1 interactions. Our data demonstrate that laminarin can be either a Dectin-1 antagonist or agonist, depending on the physicochemical properties, purity, and structure of the laminarin preparation employed.

Novel structural features in Candida albicans hyphal glucan provide a basis for differential innate immune recognition of hyphae versus yeast

The innate immune system differentially recognizes Candida albicans yeast and hyphae. It is not clear how the innate immune system effectively discriminates between yeast and hyphal forms of C. albicans. Glucans are major components of the fungal cell wall and key fungal pathogen-associated molecular patterns. C. albicans yeast glucan has been characterized; however, little is known about glucan structure in C. albicans hyphae. Using an extraction procedure that minimizes degradation of the native structure, we extracted glucans from C. albicans hyphal cell walls. (1)H NMR data analysis revealed that, when compared with reference (1→3,1→6) β-linked glucans and C. albicans yeast glucan, hyphal glucan has a unique cyclical or "closed chain" structure that is not found in yeast glucan. GC/MS analyses showed a high abundance of 3- and 6-linked glucose units when compared with yeast β-glucan. In addition to the expected (1→3), (1→6), and 3,6 linkages, we also identified a 2,3 linkage that has not been reported previously in C. albicans. Hyphal glucan induced robust immune responses in human peripheral blood mononuclear cells and macrophages via a Dectin-1-dependent mechanism. In contrast, C. albicans yeast glucan was a much less potent stimulus. We also demonstrated the capacity of C. albicans hyphal glucan, but not yeast glucan, to induce IL-1β processing and secretion. This finding provides important evidence for understanding the immune discrimination between colonization and invasion at the mucosal level. When taken together, these data provide a structural basis for differential innate immune recognition of C. albicans yeast versus hyphae.

New insights into the structure of (1→3,1→6)-β-D-glucan side chains in the Candida glabrata cell wall

β-Glucan is a (1→3)-β-linked glucose polymer with (1→6)-β-linked side chains and a major component of fungal cell walls. β-Glucans provide structural integrity to the fungal cell wall. The nature of the (1-6)-β-linked side chain structure of fungal (1→3,1→6)-β-D-glucans has been very difficult to elucidate. Herein, we report the first detailed structural characterization of the (1→6)-β-linked side chains of Candida glabrata using high-field NMR. The (1→6)-β-linked side chains have an average length of 4 to 5 repeat units spaced every 21 repeat units along the (1→3)-linked polymer backbone. Computer modeling suggests that the side chains have a bent curve structure that allows for a flexible interconnection with parallel (1→3)-β-D-glucan polymers, and/or as a point of attachment for proteins. Based on these observations we propose new approaches to how (1→6)-β-linked side chains interconnect with neighboring glucan polymers in a manner that maximizes fungal cell wall strength, while also allowing for flexibility, or plasticity.

Synthesis of the beta-1,3-glucan, laminarahexaose: NMR and conformational studies

The synthesis of laminarahexaose is described. NMR studies of several of the intermediates leading to the beta-1,3-glucan show anomalously small coupling constants for some of the C-1 hydrogens. An X-ray structure for the protected hexasaccharide shows that the small coupling constants are due to some of the glucopyranose rings adopting a twist-boat conformation. The X-ray studies also explain other unexpected NMR observations.

Differential high-affinity interaction of dectin-1 with natural or synthetic glucans is dependent upon primary structure and is influenced by polymer chain length and side-chain branching

Glucans are structurally diverse fungal biopolymers that stimulate innate immunity and are fungal pathogen-associated molecular patterns. Dectin-1 is a C-type lectin-like pattern recognition receptor that binds glucans and induces innate immune responses to fungal pathogens. We examined the effect of glucan structure on recognition and binding by murine recombinant Dectin-1 with a library of natural product and synthetic (1-->3)-beta/(1-->6)-beta-glucans as well as nonglucan polymers. Dectin-1 is highly specific for glucans with a pure (1-->3)-beta-linked backbone structure. Although Dectin-1 is highly specific for (1-->3)-beta-d-glucans, it does not recognize all glucans equally. Dectin-1 differentially interacted with (1-->3)-beta-d-glucans over a very wide range of binding affinities (2.6 mM-2.2 pM). One of the most striking observations that emerged from this study was the remarkable high-affinity interaction of Dectin-1 with certain glucans (2.2 pM). These data also demonstrated that synthetic glucan ligands interact with Dectin-1 and that binding affinity increased in synthetic glucans containing a single glucose side-chain branch. We also observed differential recognition of glucans derived from saprophytes and pathogens. We found that glucan derived from a saprophytic yeast was recognized with higher affinity than glucan derived from the pathogen Candida albicans. Structural analysis demonstrated that glucan backbone chain length and (1-->6)-beta side-chain branching strongly influenced Dectin-1 binding affinity. These data demonstrate: 1) the specificity of Dectin-1 for glucans; 2) that Dectin-1 differentiates between glucan ligands based on structural determinants; and 3) that Dectin-1 can recognize and interact with both natural product and synthetic glucan ligands.

Oral delivery and gastrointestinal absorption of soluble glucans stimulate increased resistance to infectious challenge

Glucans are immunomodulatory carbohydrates found in the cell walls of fungi and certain bacteria. We examined the pharmacokinetics of three water-soluble glucans (glucan phosphate, laminarin, and scleroglucan) after oral administration of 1 mg/kg doses in rats. Maximum plasma concentrations for glucan phosphate occurred at 4 h. In contrast, laminarin and scleroglucan showed two plasma peaks between 0.5 and 12 h. At 24 h, 27 +/- 3% of the glucan phosphate and 20 +/- 7% of the laminarin remained in the serum. Scleroglucan was rapidly absorbed and eliminated. The liver did not significantly contribute to the clearance of plasma glucan. Biological effects were further studied in mice. Following oral administration of 1 mg, glucans were bound and internalized by intestinal epithelial cells and gut-associated lymphoid tissue (GALT) cells. Internalization of glucan by intestinal epithelial cells was not Dectin-dependent. GALT expression of Dectin-1 and toll-like receptor (TLR) 2, but not TLR4, increased following oral administration of glucan. Oral glucan increased systemic levels of interleukin (IL)-12 (151 +/- 15%) in mice. Oral glucan administration also increased survival in mice challenged with Staphylococcus aureus or Candida albicans. These data demonstrate that orally administered water-soluble glucans translocate from the gastrointestinal (GI) tract into the systemic circulation. The glucans are bound by GI epithelial and GALT cells, and they modulate the expression of pattern recognition receptors in the GALT, increase IL-12 expression, and induce protection against infectious challenge.

4-Acetoxy-2,2-dimethylbutanoate: a useful carbohydrate protecting group for the selective formation of β-(1→3)-d-glucans

The use of 4-acetoxy-2,2-dimethylbutanoyl protecting group for the C2-hydroxyl allows the selective formation of β-glycosides without producing α-glycosides. This very bulky protecting group can be removed under mild conditions.

Pharmacokinetics of fungal (1–3)-β-d-glucans following intravenous administration in rats

Glucans are microbial cell wall carbohydrates that are shed into the circulation of patients with infections. Glucans are immunomodulatory and have structures that are influenced by bacterial or fungal species and growth conditions. We developed a method to covalently label carbohydrates with a fluorophore on the reducing terminus, and used the method to study the pharmacokinetics following intravenous administration of three highly purified and characterized glucans (glucan phosphate, laminarin and scleroglucan) that varied according to molecular size, branching frequency and solution conformation. Elimination half-life was longer (3.8+/-0.8 vs. 2.6+/-0.2 and 3.1+/-0.6 h) and volume of distribution lower (350+/-88 ml/kg vs. 540+/-146 and 612+/-154 ml/kg) for glucan phosphate than for laminarin and scleroglucan. Clearance was lower for glucan phosphate (42+/-6 ml/kg h) than for laminarin (103+/-17 ml/kg h) and scleroglucan (117+/-19 ml/kg h). Since plasma levels at steady state are inversely related to clearance, these differences suggest that pharmacokinetics could favor higher blood levels of glucans with certain physicochemical properties.

Novel Monoclonal Antibodies with Specificity for Chelated Uranium(VI): Isolation and Binding Properties

A derivative of 1,10-phenanthroline that binds to UO(2)(2+) with nanomolar affinity was found to be a very effective immunogen for the generation of antibodies directed toward chelated complexes of hexavalent uranium. This study describes the synthesis of 5-isothiocyanato-1,10-phenanthroline-2,9-dicarboxylic acid and its use in the generation and functional characterization of a group of monoclonal antibodies that recognize the most soluble and toxic form of uranium, the hexavalent uranyl ion (UO(2)(2+)). Three different monoclonal antibodies (8A11, 10A3, and 12F6) that recognize the 1:1 complex between UO(2)(2+) and 2,9-dicarboxy-1,10-phenanthroline (DCP) were produced by the injection of BALB/c mice with DCP-UO(2)(2+) covalently coupled to a carrier protein. Equilibrium dissociation constants for the binding of DCP-UO(2)(2+) to antibodies 8A11, 10A3, and 12F6 were 5.5, 2.4, and 0.9 nM, respectively. All three antibodies bound the metal-free DCP with roughly 1000-fold lower affinity. The second-order rate constants for the bimolecular association of each antibody with soluble DCP-UO(2)(2+) were in the range of 1 to 2 x 10(7) M(-1) s(-1). Binding studies conducted with structurally related chelators and 21 metal ions demonstrated that each of these three antibodies was highly specific for the soluble DCP-UO(2)(2+) complex. Detailed equilibrium binding studies conducted with three other derivatives of DCP, either complexed with UO(2)(2+) or metal-free, suggested that the antigen binding sites on the three antibodies have significant functional and structural similarities. Biomolecules that bind specifically to uranium will be at the heart of any new biotechnology developed to monitor and control uranium contamination. The three antibodies described herein possess sufficient affinity and specificity to support the development of immunoassays for hexavalent uranium in environmental and clinical samples.

Human monocyte scavenger receptors are pattern recognition receptors for (1-->3)-beta-D-glucans

Glucans are cell wall constituents of fungi and bacteria that bind to pattern recognition receptors and modulate innate immunity, in part, by macrophage activation. We used surface plasmon resonance to examine the binding of glucans, differing in fine structure and charge density, to scavenger receptors on membranes isolated from human monocyte U937 cells. Experiments were performed at 25 degrees C using a biosensor surface with immobilized acetylated low density lipoprotein (AcLDL). Inhibition of the binding by polyinosinic acid, but not polycytidylic acid, confirmed the interaction of scavenger receptors. Competition studies showed that there are at least two AcLDL binding sites on human U937 cells. Glucan phosphate interacts with all sites, and the CM-glucans and laminarin interact with a subset of sites. Polymer charge has a dramatic effect on the affinity of glucans with macrophage scavenger receptors. However, it is also clear that human monocyte scavenger receptors recognize the basic glucan structure independent of charge.

Normal human fibroblasts express pattern recognition receptors for fungal (1-->3)-beta-D-glucans

Fungal cell wall glucans nonspecifically stimulate various aspects of innate immunity. Glucans are thought to mediate their effects via interaction with membrane receptors on macrophages, neutrophils, and NK cells. There have been no reports of glucan receptors on nonimmune cells. We investigated the binding of a water-soluble glucan in primary cultures of normal human dermal fibroblasts (NHDF). Membranes from NHDF exhibited saturable binding with an apparent dissociation constant (K(D)) of 8.9 +/- 1.9 microg of protein per ml and a maximum binding of 100 +/- 8 resonance units. Competition studies demonstrated the presence of at least two glucan binding sites on NHDF. Glucan phosphate competed for all binding sites, with a K(D) of 5.6 microM (95% confidence interval [CI], 3.0 to 11 microM), while laminarin competed for 69% +/- 6% of binding sites, with a K(D) of 3.7 microM (95% CI, 1.9 to 7.3 microM). Glucan (1 microg/ml) stimulated fibroblast NF-kappaB nuclear binding activity and interleukin 6 (IL-6) gene expression in a time-dependent manner. NF-kappaB was activated at 4, 8, and 12 h, while IL-6 mRNA levels were increased by 48% at 8 h. This is the first report of pattern recognition receptors for glucan on human fibroblasts and the first demonstration of glucan binding sites on cells other than leukocytes. It also provides the first evidence that glucans can directly modulate the functional activity of NHDF. These results provide new insights into the mechanisms by which the host recognizes and responds to fungal (1-->3)-beta-D-glucans and suggests that the response to glucans may not be confined to cells of the immune system.

Glucans exhibit weak antioxidant activity, but stimulate macrophage free radical activity

Polymeric carbohydrates have been reported to modulate inflammatory responses in vitro and in vivo. Previous reports suggest that certain carbohydrate polymers, such as (1-->3)-beta-D-glucans, may possess free radical scavenging activity. If glucans are free radical scavengers then it might explain, in part, the ability of these ligands to modulate inflammatory responses. The present study examined the free radical scavenging activity of a variety of carbohydrate polymers and the effect of the polymers on free radical levels in a murine macrophage cell line. All of the carbohydrates exhibited concentration dependent antioxidant effects (EC(50) range = 807 to 43 microg/ml). However, the antioxidant activity for the carbohydrates was modest in comparison with PDTC (EC(50) = 0.13 microg/ml) and the carbohydrate concentration required for antioxidant activity was high (x EC(50) = 283 microg/ml). The antioxidant ability of the polymers was greater (p < .05) than their monosaccharide constituents, i.e., dextrose EC(50) = 807 vs. glucan sulfate EC(50) = 43 microg/ml. Coincubation of glucans with murine J774a.1 cells increased free radical levels when compared to controls. Therefore, the weak free radical scavenging activity of glucan polymers cannot explain their modulatory effect on inflammatory responses in tissue culture and/or disease models of inflammation.

The influence of glucan polymer structure and solution conformation on binding to (1-->3)-beta-D-glucan receptors in a human monocyte-like cell line

Glucans are (1-3)-beta-D-linked polymers of glucose that are produced as fungal cell wall constituents and are also released into the extracellular milieu. Glucans modulate immune function via macrophage participation. The first step in macrophage activation by (1-3)-beta-D-glucans is thought to be the binding of the polymer to specific macrophage receptors. We examined the binding/uptake of a variety of water soluble (1-3)-beta-D-glucans and control polymers with different physicochemical properties to investigate the relationship between polymer structure and receptor binding in the CR3- human promonocytic cell line, U937. We observed that the U937 receptors were specific for (1-->3)-beta-D-glucan binding, since mannan, dextran, or barley glucan did not bind. Scleroglucan exhibited the highest binding affinity with an IC(50)of 23 nM, three orders of magnitude greater than the other (1-->3)-beta-D-glucan polymers examined. The rank order competitive binding affinities for the glucan polymers were scleroglucan>>>schizophyllan > laminarin > glucan phosphate > glucan sulfate. Scleroglucan also exhibited a triple helical solution structure (nu = 1.82, beta = 0.8). There were two different binding/uptake sites on U937 cells. Glucan phosphate and schizophyllan interacted nonselectively with the two sites. Scleroglucan and glucan sulfate interacted preferentially with one site, while laminarin interacted preferentially with the other site. These data indicate that U937 cells have at least two non-CR3 receptor(s) which specifically interact with (1-->3)-beta-D-glucans and that the triple helical solution conformation, molecular weight and charge of the glucan polymer may be important determinants in receptor ligand interaction.

Receptor binding and internalization of a water-soluble (1--&gt;3)-beta-D-glucan biologic response modifier in two monocyte/macrophage cell lines

Glucan phosphate, a water-soluble, chemically defined (1--&gt;3)-beta-D-glucan biologic response modifier, has been reported to exert antisepsis activity and accelerate wound healing. In this study we describe the specific binding of glucan phosphate to human and murine monocyte/macrophage cell lines, U937 and J774A.1, respectively. At 37 degrees C, equilibrium binding was rapidly achieved, i.e., within 1 min. In U937 cells, binding occurred with an affinity (Kd) of 37 microM and a Bmax of 65 x 106 binding sites/cell at 37 degrees C. In J774A.1 cells, glucan phosphate bound with an affinity (Kd) of 24 microM and a Bmax of 53 x 106 binding sites/cell at 37 degrees C. In both cases there was insignificant nonspecific binding. We further demonstrated that bound glucan phosphate cannot be displaced by a 50-fold excess of unlabeled ligand, suggesting internalization of glucan phosphate. Transmission electron microscopy showed significantly increased cytoplasmic vacuolization and significantly decreased mitotic activity in glucan phosphate-treated U937 cells compared with that in untreated cells. Pullulan, a random coil alpha-(1--&gt;4)-(1--&gt;6)-linked glucose polymer that served as a control, did not compete for the same binding site as glucan phosphate in either cell line, indicating the specificity of the binding site for (1--&gt;3)-beta-D-glucans. We conclude that water-soluble pharmaceutical grade (1--&gt;3)-beta-D-glucan phosphate specifically binds to and is internalized by U937 and J774A.1 cells.

Receptor binding and internalization of a water-soluble (1-->3)-beta-D-glucan biologic response modifier in two monocyte/macrophage cell lines

Glucan phosphate, a water-soluble, chemically defined (1-->3)-beta-D-glucan biologic response modifier, has been reported to exert antisepsis activity and accelerate wound healing. In this study we describe the specific binding of glucan phosphate to human and murine monocyte/macrophage cell lines, U937 and J774A.1, respectively. At 37 degrees C, equilibrium binding was rapidly achieved, i.e., within 1 min. In U937 cells, binding occurred with an affinity (Kd) of 37 microM and a Bmax of 65 x 106 binding sites/cell at 37 degrees C. In J774A.1 cells, glucan phosphate bound with an affinity (Kd) of 24 microM and a Bmax of 53 x 106 binding sites/cell at 37 degrees C. In both cases there was insignificant nonspecific binding. We further demonstrated that bound glucan phosphate cannot be displaced by a 50-fold excess of unlabeled ligand, suggesting internalization of glucan phosphate. Transmission electron microscopy showed significantly increased cytoplasmic vacuolization and significantly decreased mitotic activity in glucan phosphate-treated U937 cells compared with that in untreated cells. Pullulan, a random coil alpha-(1-->4)-(1-->6)-linked glucose polymer that served as a control, did not compete for the same binding site as glucan phosphate in either cell line, indicating the specificity of the binding site for (1-->3)-beta-D-glucans. We conclude that water-soluble pharmaceutical grade (1-->3)-beta-D-glucan phosphate specifically binds to and is internalized by U937 and J774A.1 cells.

Isolation of a previously unidentified polysaccharide (MAR-10) from Hyssop officinalis that exhibits strong activity against human immunodeficiency virus type 1

A polysaccharide (MAR-10) was isolated from the aqueous extract of the plant Hyssop officinalis and examined for its activity against HIV-1 (SF strain) in HUT78 T cell line and primary cultures of peripheral blood mononuclear cells. MAR-10, in a concentration-dependent manner, inhibited HIV-1 replication as demonstrated by the inhibition of HIV-1 p24 antigen and syncytia formation. Furthermore, MAR-10 had no significant direct toxicity or effect on lymphocyte functions or CD4+ and CD8+ T cell counts. In addition, MAR-10 has broad spectrum anti-glycosidase activity. Our study demonstrates that MAR-10 contains strong anti-HIV-1 activity that may be useful in the treatment of patients with HIV-1 infection.

Development of a water-soluble, sulfated (1-->3)-beta-D-glucan biological response modifier derived from Saccharomyces cerevisiae

This report describes a method for the solubilization of micro-particulate (1-->3)-beta-D-glucan. Insoluble glucan is dissolved in methyl sulfoxide and urea (8 M) and partially sulfated at 100 degrees. The resulting water-soluble product is called glucan sulfate. The conversion rate is 98%, and the preparation is endotoxin free as determined by the Limulus lysate procedure. Glucan sulfate is composed of 34.06% C, 6.15% H, 50.30% O, 5.69% S and 3.23% N, and has a repeating unit empirical formula of (C6H10O5)8.3 SO3NH4+.4 H2O, suggesting that, on the average, a sulfate group is substituted on every third glucose subunit along the polymer. Molecular weight averages, polydispersity, and intrinsic viscosity were determined by aqueous high-performance size-exclusion chromatography (HPSEC). Two polymer peaks were resolved. Peak 1 (Mw = 1.25 x 10(6) g/mol) represents < 1% of the total polymer mass. Peak 2 (Mw = 1.45 x 10(4) g/mol) comprises > 99% of polymers. 13C NMR spectroscopy confirmed the beta-(1-->3) interchain linkage. In solution, glucan sulfate polymers self-associate in a triple helix. Glucan sulfate stimulates murine bone marrow proliferation following intravenous administration. The ability to prepare a immunologically active, water-soluble (1-->3)-beta-D-glucan preparation will greatly enhance the clinical utility of this class of compounds.

Development, physicochemical characterization and preclinical efficacy evaluation of a water soluble glucan sulfate derived from Saccharomyces cerevisiae

This report describes the development, characterization and preclinical efficacy evaluation of water soluble glucan sulfate. Glucan sulfate was derived from insoluble beta-1,3-D-glucan isolated from Saccharomyces cerevisiae. The proposed repeating unit empirical formula of glucan sulfate is [(C6H10O5)5.3H2SO4]n. Two polymer peaks were resolved by aqueous high-performance size exclusion chromatography (HPSEC) with on-line multi-angle laser light scattering (MALLS) photometry and differential viscometry. Peak 1 (MW = 1219697 Da) represents approximately 1% of the total polymers, while peak 2 (MW = 8884 Da) accounts for approximately 99% of polymers. 13C-NMR spectroscopy suggests that glucan sulfate polymer strands may be partially cross-linked. Glucan sulfate (250 mg/kg, i.v.) increased (P less than 0.01) macrophage vascular clearance of 131I-reticuloendothelial emulsion by 42% (P less than 0.01) and in vitro bone marrow proliferation by 46% (P less than 0.05). Glucan sulfate (250 mg/kg, i.v.) increased (P less than 0.05) median survival time of C57B1/6J mice with syngeneic melanoma B16 or sarcoma M5076. In addition, glucan sulfate immunoprophylaxis increased resistance of mice to challenge with Escherichia coli, Candida albicans or Mouse Hepatitis Virus strain A-59. We concluded that: (1) insoluble beta-1,3-D-glucan can be converted to a water soluble sulfated form; (2) glucan sulfate activates macrophages and stimulates bone marrow; (3) glucan sulfate exerts antitumor therapeutic activity, and (4) glucan sulfate immunoprophylaxis will modify the course of experimental infectious disease.

A method for the solubilization of a (1----3)-beta-D-glucan isolated from Saccharomyces cerevisiae

This report describes a method for the solubilization of a micro-particulate beta-D-glucan. Insoluble glucan is dissolved in methyl sulfoxide and urea (8M) and partially phosphorylated at 100 degrees. The resulting water-soluble product is called glucan phosphate. The conversion rate is 70%, and the preparation is endotoxin free as determined by the Limulus lysate procedure. Glucan phosphate is composed of 34.66% C, 6.29% H, 42.83% O, and 2.23% P and has a repeating-unit empirical formula of (C6H10O5)7.PO3H2, indicating a phosphate group substitution on every seventh glucose subunit. Molecular-weight averages, polydispersity, and intrinsic viscosity were determined by aqueous high-performance size-exclusion chromatography (s.e.c.) with on-line, multi-angle laser light scattering (m.a.l.l.s.) photometry and differential viscometry (d.v.). Two polymer peaks were resolved. Peak 1 (Mw = 3.57 x 10(6) daltons), represents approximately 2% of the total polymers, while peak 2 (Mw = 1.10 x 10(5) daltons) comprises approximately 98% of polymers. 13C- and 31P-n.m.r. spectroscopy confirmed the beta-1,3 interchain linkage and the presence of a phosphate group. In solution, glucan phosphate polymers self-associate in a triple-helical arrangement. The ability to prepare a immunologically active, non-toxic, water-soluble beta-D-glucan preparation will greatly enhance the clinical utility of this class of compounds.

Isolation, physicochemical characterization and preclinical efficacy evaluation of soluble scleroglucan

Herein we describe the isolation, physicochemical characterization and preclinical evaluation of a water-soluble biologic response modifier extracted from Sclerotium glucanicum. Alkaline extraction of insoluble S. glucanicum exopolymers produced a soluble scleroglucan composed of a triple-helical beta-1,3-linked glucopyranose backbone with single beta-1,6-linked glucopyranosyl branches every third subunit. Scleroglucan has a weight average molecular mass of 1.56 x 10(6) Da, a weight average root mean square distance from the center of gravity of the molecule to its farthest elements of 51.8 nm, a polydispersity (weight-average molecular mass/number average molecular mass) of 1.83 and intrinsic viscosity of 3.081 dl/g. Scleroglucan (250 mg/kg, intravenously) stimulated in vivo murine macrophage phagocytic activity (66%, P less than .001) and increased in vitro macrophage tumor cytotoxicity against syngeneic tumor targets by 124% (P less than .05). Scleroglucan enhanced (P less than .001) murine bone marrow proliferation in a biphasic manner by up to 328%. Scleroglucan therapy increased survival of mice challenged with syngeneic lymphoma, melanoma or adenocarcinoma. AKR/J mice bearing syngeneic lymphoma (1 x 10(3) cells, intraperitoneally) demonstrated increased (P less than .001) long-term survival (100% vs. 0%, greater than 64 days). C57Bl/6J mice bearing syngeneic melanoma B16 (5 x 10(5) cells, subcutaneously) demonstrated increased long-term survival (64% vs. 0%, P less than .05). C57Bl/6J mice bearing syngeneic adenocarcinoma BW10232 (1 x 10(5) cells, subcutaneously) demonstrated increased (P less than .05) median survival time. In addition, scleroglucan prophylaxis increased resistance of mice to challenge with Staphylococcus aureus, Candida albicans and mouse hepatitis virus A-59. Scleroglucan did not induce toxicity or hepatomegaly. We conclude that: 1) a branched, water-soluble beta-1,3-linked scleroglucan biologic response modifier can be extracted from S. glucanicum; 2) scleroglucan will stimulate immunity, modify experimental neoplastic disease and increase resistance to microbial challenge; and 3) scleroglucan shows promise as an immunopotentiating drug.

External ocular inflammatory effects of lipoxygenase enzyme products

We systematically observed the effects of lipoxygenase enzyme products (5-, 8-, 9-, 12-, and 15-HETE and leukotrienes (LT) C4, D4, and B4) on the external ocular inflammatory process in rabbits. Our results, using 1 and 10 micrograms enzymatic preparations topically applied to the conjunctiva, were consistent with the potent chemotactic activity of 12-HETE and LTB4. Modulation of the inflammatory process can be accomplished better, as a result of our findings, by inhibition of both the lipoxygenase and cyclooxygenase pathways.

Inhibition of soybean lipoxygenase by SKF 525-A and metyrapone

To determine whether agents which inhibit cytochrome P-450 enzymes also inhibit lipoxygenase, the effects of metyrapone and SKF 525-A were assessed on soybean lipoxygenase using a spectrophotometric technique which allows for measurement of both the rate and magnitude of product formation. Both SKF 525-A and metyrapone inhibited the rate of product formation and the final amount of product formed in 5 min incubations SKF 525-A was 5 to 5 times more potent than metyrapone, with the IC50 for SKF 525-A 40 microM and for metyrapone between 150 and 200 microM as determined by the total product formation in 5 minutes. Analysis of the reduced product by HPLC confirmed that the substances monitored were those generated by the 15-lipoxygenase enzyme.

Reversible inhibitors of beta-glucosidase

A variety of reversible inhibitors of sweet almond beta-glucosidase were examined. These included simple sugars and sugar derivatives, amines and phenols. With respect to the sugar inhibitors and, indeed, the various glycoside substrates, the enzyme has what can be considered a "relaxed specificity". No single substituent on glucose, for example, is essential for binding. Replacement of a hydroxyl group with an anionic substituent reduces the affinity while substitution with a cationic (amine) substituent enhances the affinity. Amines, in general, are good inhibitors, binding more tightly than the corresponding alcohols: pKiRNH3+ = 0.645pKiROH + 1.77 (n = 9, r = 0.97). The affinity of a series of 10 primary amines was found to be strongly influenced by substituent hydrophobicity: pKi = 0.52 pi + 1.32 (r = 0.95). The major binding determinant of the glycoside substrates is the aglycon moiety. Thus, the Ki values of phenols are similar in magnitude to the Ks values of the corresponding aryl beta-glucoside. The pH dependence for the inhibition by various phenols indicates that it is the un-ionized phenol which binds to the enzyme when an enzymic group of pKa = 6.8 (+/- 0.1) is protonated. The affinity of the phenol inhibitor is dependent on its basicity with a Brønsted coefficient for binding of beta = -0.26 (n = 14, r = 0.98). The pH dependence of the binding of two particularly potent beta-glucosidase inhibitors was also examined. 1-Deoxynojirimycin (1,5-dideoxy-1,5-imino-D-glucitol) has a pH-corrected Ki = 6.5 microM, and D-glucono-1,5-lactam has a pH-corrected Ki = 29 microM.(ABSTRACT TRUNCATED AT 250 WORDS)

Optically Active Amines. Part XIII. Circular Dichroism of the N-Salicylidene Derivatives of Alkylamines

Comparison of the c.d. spectra of (S)-(+)-N-salicylidene-α-phenylethylamine with those of (S)-(+)-N-salicylidene-sec-butylamine and (R)-(−)-N-salicylidene-2,2-dimethyl-3-aminobutane confirms the conclusion that the strong rotational strength shown by N-salicylidene-α- and β-phenylalkylamines is due to an interaction of the π-electron System of the phenyl group and the salicylidenimino chromophore. The sign of the Cotton effects near 255 and 315 nm shown by the N-salicylidenes of alkylamines and cycloalkylamines, when these are conformationally defined, can be correlated with their absolute configurations using a planar sector rule, similar to that used for the interpretation of the c.d. and o.r.d. spectra of N-salicylidene-α- and β-phenylalkylamines.