Soluble beta-glucan polysaccharide binding to the lectin site of neutrophil or natural killer cell complement receptor type 3 (CD11b/CD18) generates a primed state of the receptor capable of mediating cytotoxicity of iC3b-opsonized target cells

Catch me if you can: phagocytosis and killing avoidance by Cryptococcus neoformans

After inhalation of infectious particles, Cryptococcus neoformans resides in the alveolar spaces, where it can survive and replicate in the extracellular environment. This yeast has developed different mechanisms to avoid internalization by phagocytic cells, the main one being a polysaccharide capsule around the cell body, which inhibits the uptake of the yeast by macrophages. In addition, capsule-independent mechanisms have also been described, such as the production of antiphagocytic proteins. Despite these mechanisms, phagocytosis can occur in the presence of opsonins, and once C. neoformans is internalized, multiple outcomes are possible, including pathogen killing or intracellular replication and escape from macrophages. For this reason, C. neoformans is considered a facultative intracellular pathogen. As alveolar macrophages are the first component of the host immune system to confront C. neoformans, the outcome of this interaction could determine the degree of infection, producing either a severe disseminated disease or a latency state. In this review, we will tackle the complexity of the interaction between C. neoformans and macrophages, including the phagocytic avoidance mechanisms and all the possible outcomes that have been described for this interaction. Finally, we will discuss the consequences of the different outcomes for the type of infection produced in the host.

Effect of AndoSan™ on expression of adhesion molecules and production of reactive oxygen species in human monocytes and granulocytes in vivo

BACKGROUND

Oral intake (60 ml daily) over 12 days in eight healthy volunteers of an immunostimulatory extract based on the medicinal mushroom Agaricus blazei Murill (AbM (AndoSan™)), reduced the monocyte and granulocyte release of mainly proinflammatory cytokines in vivo, suggesting an anti-inflammatory effect. In this foremost in vivo study, the aim was to examine the effect of such AndoSan™ consumption on the expression of adhesion molecules CD11b, CD11c and CD62L and production of reactive oxygen species (ROS) in leukocytes.

METHODOLOGY/PRINCIPAL FINDINGS

As shown by flow cytometry, there was a significant increase of CD62L expression on monocytes and granulocytes from before (day 0) compared with 12 days after daily AndoSan™ consumption. However, only minor alterations and no clear trend in the expression of CD11b and CD11c were detected. Intracellular ROS (mainly superoxide ion) were significantly reduced in these cells from days 0 to 12.

CONCLUSIONS/SIGNIFICANCE

These results support that oral intake of AndoSan™ exhibits an anti-inflammatory effect in humans in vivo.

Fungal antioxidant pathways promote survival against neutrophils during infection

Filamentous fungi are a common cause of blindness and visual impairment worldwide. Using both murine model systems and in vitro human neutrophils, we found that NADPH oxidase produced by neutrophils was essential to control the growth of Aspergillus and Fusarium fungi in the cornea. We demonstrated that neutrophil oxidant production and antifungal activity are dependent on CD18, but not on the β-glucan receptor dectin-1. We used mutant A. fumigatus strains to show that the reactive oxygen species-sensing transcription factor Yap1, superoxide dismutases, and the Yap1-regulated thioredoxin antioxidant pathway are each required for protection against neutrophil-mediated oxidation of hyphae as well as optimal survival of fungal hyphae in vivo. We also demonstrated that thioredoxin inhibition using the anticancer drug PX-12 increased the sensitivity of fungal hyphae to both H2O2- and neutrophil-mediated killing in vitro. Additionally, topical application of PX-12 significantly enhanced neutrophil-mediated fungal killing in infected mouse corneas. Cumulatively, our data reveal critical host oxidative and fungal anti-oxidative mediators that regulate hyphal survival during infection. Further, these findings also indicate that targeting fungal anti-oxidative defenses via PX-12 may represent an efficacious strategy for treating fungal infections.

The β-glucan receptor Dectin-1 activates the integrin Mac-1 in neutrophils via Vav protein signaling to promote Candida albicans clearance

Resistance to fungal infections is attributed to engagement of host pattern-recognition receptors, notably the β-glucan receptor Dectin-1 and the integrin Mac-1, which induce phagocytosis and antifungal immunity. However, the mechanisms by which these receptors coordinate fungal clearance are unknown. We show that upon ligand binding, Dectin-1 activates Mac-1 to also recognize fungal components, and this stepwise process is critical for neutrophil cytotoxic responses. Both Mac-1 activation and Dectin-1- and Mac-1-induced neutrophil effector functions require Vav1 and Vav3, exchange factors for RhoGTPases. Mac-1- or Vav1,3-deficient mice have increased susceptibility to systemic candidiasis that is not due to impaired neutrophil recruitment but defective intracellular killing of C. albicans yeast forms, and Mac-1 or Vav1,3 reconstitution in hematopoietic cells restores resistance. Our results demonstrate that antifungal immunity depends on Dectin-1-induced activation of Mac-1 functions that is coordinated by Vav proteins, a pathway that may localize cytotoxic responses of circulating neutrophils to infected tissues.

Agaricus subrufescens: A review

Medicinal mushrooms have currently become a hot issue due to their various therapeutic properties. Of these, Agaricus subrufescens, also known as the "almond mushroom", has long been valued by many societies (i.e., Brazil, China, France, and USA). Since its discovery in 1893, this mushroom has been cultivated throughout the world, especially in Brazil where several strains of A. subrufescens have been developed and used as health food and alternative medicine. This article presents up-to-date information on this mushroom including its taxonomy and health promoting benefits. Medicinal properties of A. subrufescens are emphasized in several studies which are reviewed here. In addition, safety issues concerning the use of this fungus will be discussed.

Synthesis of curdlan-graft-poly(ethylene glycol) and formulation of doxorubicin-loaded core–shell nanoparticles

A new core–shell nanoparticle containing the chemotherapeutic drug doxorubicin was formulated via amphiphilic graft copolymer self-assembly using curdlan- graft-poly(ethylene glycol) (curdlan -g-PEG). The graft copolymer was synthesized through the dicyclohexylcarbodiimide ester linkage of carboxylated PEG to the hydroxyl groups of the curdlan backbone. The nanoparticles were 109.9 nm in size and encapsulated doxorubicin in high yield (4%–5% wt/wt). The nanoparticles also controlled the release of doxorubicin over 24 h with a release profile that followed a Fickian diffusion model. The biocompatibility of curdlan- g-PEG was confirmed by hemolysis assay. This is the first nanoparticle formulated using the hydrophobicity of curdlan for concealing the immunomodulatory potential of curdlan within the core.

Mac-1 negative NK cells constitute the predominant subset in the livers of mice transvenously injected with tumor cells

We evaluated age-related differences in hepatic natural killer (NK) cell phenotypes in juvenile (2-week-old) and adult (8-week-old) C57BL/6(B6) mice, and determined NK cell cytotoxicity and apoptosis in tumor inoculated mice. Juvenile mice had a preponderance of Mac-1(-) NK cells that exhibited significantly higher cytotoxicity levels. The Mac-1(-) NK cell population was the predominant subset in the liver of mice inoculated with the CMT-93 mouse rectum carcinoma cell line, which paralleled a dramatic decrease in the numbers of Mac-1(+) NK cells. The decrease in Mac-1(+) NK cells was driven by an apoptotic pathway.

Activation of peripheral-blood granulocytes is strongly correlated with patient outcome after immunotherapy with anti-GD2 monoclonal antibody and granulocyte-macrophage colony-stimulating factor

PURPOSE

Adjuvant therapy using anti-GD2 monoclonal antibody and granulocyte-macrophage colony-stimulating factor (GM-CSF) has shown treatment success for patients with high-risk neuroblastoma (NB). Although there is ample evidence on how the antibody targets NB, in vivo contribution by GM-CSF remains unclear. This report investigates granulocyte activation and its correlation with treatment outcome.

PATIENTS AND METHODS

Patients enrolled onto NCT00072358 received multiple treatment cycles, each consisting of anti-GD2 antibody 3F8 plus subcutaneous (SC) GM-CSF. Peripheral-blood (PB) samples from 151 patients were collected on day 0 and day 4 of cycle 1. PB from a subgroup of 35 patients had intravenous (IV) instead of SC GM-CSF during cycle 4. Samples were analyzed by flow cytometry for CD11a, CD63, CD87, and CD11b and its activation epitope CBRM1/5.

RESULTS

Comparing cycle 1 day 4 PB samples with day 0 PB samples, five of five activation marker-positive granulocytes were significantly higher. The change in frequency and mean fluorescence intensity of CBRM1/5-positive granulocytes correlated with progression-free survival (PFS; P = .024 and P = .008, respectively). A multivariable analysis identified increasing CBRM1/5-positive granulocytes and missing killer immunoglobulin-like receptor ligand as positive independent prognostic factors for PFS, whereas second-line cyclophosphamide-based therapy before protocol entry negatively influenced outcome. Thirty-five patients who received SC GM-CSF at cycle 1 and IV GM-CSF at cycle 4 had significantly less CBRM1/5 activation after IV GM-CSF. In contrast, 63 patients who received SC GM-CSF at both cycles had comparable CBRM1/5 activation.

CONCLUSION

GM-CSF-induced granulocyte activation in vivo is associated with improved patient outcome. This activation was more apparent when GM-CSF was given by the SC route instead of IV route.

Lectin site ligation of CR3 induces conformational changes and signaling

Neutrophils provide an innate immune response to tissues infected with fungal pathogens such as Candida albicans. This response is tightly regulated in part through the interaction of integrins with extracellular matrix ligands that are distributed within infected tissues. The β(2) integrin, CR3 (CD11b/CD18), is unique among integrins in containing a lectin-like domain that binds the fungal pathogen-associated molecular pattern β-glucan and serves as the dominant receptor for recognition of fungal pathogens by human granulocytes. β-Glucan, when isolated in soluble form, has been shown to be a safe and effective immune potentiator when administered therapeutically. Currently a pharmaceutical grade preparation of β-glucan is in several clinical trials with an anti-cancer indication. CR3 binding of extracellular matrix, carbohydrate, or both ligands simultaneously differentially regulates neutrophil function through a mechanism not clearly understood. Using FRET reporters, we interrogated the effects of soluble β-glucan on intracellular and extracellular CR3 structure. Although the canonical CR3 ligand fibrinogen induced full activation, β-glucan alone or in conjunction with fibrinogen stabilized an intermediate conformation with moderate headpiece extension and full cytoplasmic tail separation. A set of phosphopeptides differentially regulated by β-glucan in a CR3-dependent manner were identified using functional proteomics and found to be enriched for signaling molecules and proteins involved in transcriptional regulation, mRNA processing, and alternative splicing. These data confirm that CR3 is a signaling pattern recognition receptor for β-glucan and represent the first direct evidence of soluble β-glucan binding and affecting a signaling-competent intermediate CR3 conformation on living cells.

Engineered Fc variant antibodies with enhanced ability to recruit complement and mediate effector functions

Engineering the antibody Fc region to enhance the cytotoxic activity of therapeutic antibodies is currently an active area of investigation. The contribution of complement to the mechanism of action of some antibodies that target cancers and pathogens makes a compelling case for its optimization. Here we describe the generation of a series of Fc variants with enhanced ability to recruit complement. Variants enhanced the cytotoxic potency of an anti-CD20 antibody up to 23-fold against tumor cells in CDC assays, and demonstrated a correlated increase in C1q binding affinity. Complement-enhancing substitutions combined additively, and in one case synergistically, with substitutions previously engineered for improved binding to Fc gamma receptors. The engineered combinations provided a range of effector function activities, including simultaneously enhanced CDC, ADCC, and phagocytosis. Variants were also effective at boosting the effector function of antibodies targeting the antigens CD40 and CD19, in the former case enhancing CDC over 600-fold, and in the latter case imparting complement-mediated activity onto an IgG1 antibody that was otherwise incapable of it. This work expands the toolkit of modifications for generating monoclonal antibodies with improved therapeutic potential and enables the exploration of optimized synergy between Fc gamma receptors and complement pathways for the destruction of tumors and infectious pathogens.

Pharmacological, structural, and drug delivery properties and applications of 1,3-β-glucans

1,3-β-Glucans are a class of natural polysaccharides with unique pharmacological properties and the ability to form single- and triple-helical structures that can be formed into resilient gels with the application of heat and humidity. The pharmacological capabilities of 1,3-β-glucans include the impartation of tumor inhibition, resistance to infectious disease, and improvements in wound healing. Curdlan is a linear 1,3-β-glucan that has been used extensively to study the nature of these helical structures and gels, and Curdlan sulfates have found ongoing application in the inhibition of HIV infection. 1,3-β-Glucan gels have been used in food science as stabilizers and encapsulating agents, in nanoscience as scaffolds to build nanofibers and nanowires, and in drug delivery to form nanoparticles and create helical micelles encapsulating polynucleotides. 1,3-β-Glucans are beginning to have enormous significance due to their dual nature as structure-forming agents and pharmacological substances, and research is especially focused on the application of these polymers in animal nutrition and drug delivery.

Molecular basis for the interaction of low density lipoprotein receptor-related protein 1 (LRP1) with integrin alphaMbeta2: identification of binding sites within alphaMbeta2 for LRP1

The LDL receptor-related protein 1 (LRP1) is a large endocytic receptor that controls macrophage migration in part by interacting with β(2) integrin receptors. However, the molecular mechanism underlying LRP1 integrin recognition is poorly understood. Here, we report that LRP1 specifically recognizes α(M)β(2) but not its homologous receptor α(L)β(2). The interaction between these two cellular receptors in macrophages is significantly enhanced upon α(M)β(2) activation by LPS and is mediated by multiple regions in both LRP1 and α(M)β(2). Specifically, we find that both the heavy and light chains of LRP1 are involved in α(M)β(2) binding. Within the heavy chain, the binding is mediated primarily via the second and fourth ligand binding repeats. For α(M)β(2), we find that the α(M)-I domain represents a major LRP1 recognition site. Indeed, substitution of the I domain of the α(L)β(2) receptor with that of α(M) confers the α(L)β(2) receptor with the ability to interact with LRP1. Furthermore, we show that residues (160)EQLKKSKTL(170) within the α(M)-I domain represent a major LRP1 recognition site. Given that perturbation of this specific sequence leads to altered adhesive activity of α(M)β(2), our finding suggests that binding of LRP1 to α(M)β(2) could alter integrin function. Indeed, we further demonstrate that the soluble form of LRP1 (sLRP1) inhibits α(M)β(2)-mediated adhesion of cells to fibrinogen. These studies suggest that sLRP1 may attenuate inflammation by modulating integrin function.

Differential pathways regulating innate and adaptive antitumor immune responses by particulate and soluble yeast-derived β-glucans

β-glucans have been reported to function as a potent adjuvant to stimulate innate and adaptive immune responses. However, β-glucans from different sources are differential in their structure, conformation, and thus biologic activity. Different preparations of β-glucans, soluble versus particulate, further complicate their mechanism of action. Here we show that yeast-derived particulate β-glucan activated dendritic cells (DCs) and macrophages via a C-type lectin receptor dectin-1 pathway. Activated DCs by particulate β-glucan promoted Th1 and cytotoxic T-lymphocyte priming and differentiation in vitro. Treatment of orally administered yeast-derived particulate β-glucan elicited potent antitumor immune responses and drastically down-regulated immunosuppressive cells, leading to the delayed tumor progression. Deficiency of the dectin-1 receptor completely abrogated particulate β-glucan-mediated antitumor effects. In contrast, yeast-derived soluble β-glucan bound to DCs and macrophages independent of the dectin-1 receptor and did not activate DCs. Soluble β-glucan alone had no therapeutic effect but significantly augmented antitumor monoclonal antibody-mediated therapeutic efficacy via a complement activation pathway but independent of dectin-1 receptor. These findings reveal the importance of different preparations of β-glucans in the adjuvant therapy and allow for the rational design of immunotherapeutic protocols usable in clinical trials.

Effect of an extract based on the medicinal mushroom Agaricus blazei Murill on expression of cytokines and calprotectin in patients with ulcerative colitis and Crohn's disease

An immunomodulatory extract (AndoSan™) based on the medicinal mushroom Agaricus blazei Murill (AbM) has shown to reduce blood cytokine levels in healthy volunteers after 12 days' ingestion, pointing to an anti-inflammatory effect. The aim was to study whether AndoSan™ had similar effects on cytokines in patients with ulcerative colitis (UC) and Crohn's disease (CD). Calprotectin, a marker for inflammatory bowel disease (IBD), was also measured. Patients with CD (n = 11) and with UC (n = 10) consumed 60 ml/day of AndoSan™. Patient blood plasma was harvested before and after 6 h LPS (1 ng/ml) stimulation ex vivo. Plasma and faecal calprotectin levels were analysed using ELISA and 17 cytokines [IL-2, IFN-γ, IL-12 (Th1), IL-4, IL-5, IL-13 (Th2), IL-7, IL-17, IL-1β, IL-6, TNF-α, IL-8, MIP-1β, MCP-1, G-CSF, GM-CSF and IL-10] by multiplex assay. After 12 days' ingestion of AndoSan™, baseline plasma cytokine levels in UC was reduced for MCP-1 (40%) and in LPS-stimulated blood for MIP-1β (78%), IL-6 (44%), IL-1β (41%), IL-8 (30%), G-CSF (29%), MCP-1 (18%) and GM-CSF (17%). There were corresponding reductions in CD: IL-2 (100%), IL-17 (55%) and IL-8 (29%) and for IL-1β (35%), MIP-1β (30%), MCP-1 (22%), IL-8 (18%), IL-17 (17%) and G-CSF (14%), respectively. Baseline concentrations for the 17 cytokines in the UC and CD patient groups were largely similar. Faecal calprotectin was reduced in the UC group. Ingestion of an AbM-based medicinal mushroom by patients with IBD resulted in interesting anti-inflammatory effects as demonstrated by declined levels of pathogenic cytokines in blood and calprotectin in faeces.

Regulation of innate immune response to Candida albicans infections by αMβ2-Pra1p interaction

Candida albicans is a common opportunistic fungal pathogen and is the leading cause of invasive fungal diseases in immunocompromised individuals. The induction of cell-mediated immunity to C. albicans is one of the main tasks of cells of the innate immune system, and in vitro evidence suggests that integrin α(M)β₂ (CR3, Mac-1, and CD11b/CD18) is the principal leukocyte receptor involved in recognition of the fungus. Using α(M)β₂-KO mice and mutated strains of C. albicans in two models of murine candidiasis, we demonstrate that neutrophils derived from mice deficient in α(M)β₂ have a reduced ability to kill C. albicans and that the deficient mice themselves exhibit increased susceptibility to fungal infection. Disruption of the PRA1 gene of C. albicans, the primary ligand for α(M)β₂, protects the fungus against leukocyte killing in vitro and in vivo, impedes the innate immune response to the infection, and increases fungal virulence and organ invasion in vivo. Thus, recognition of pH-regulated antigen 1 protein (Pra1p) by α(M)β₂ plays a pivotal role in determining fungal virulence and host response and protection against C. albicans infection.

An open-label dosing study to evaluate the safety and effects of a dietary plant-derived polysaccharide supplement on the N-glycosylation status of serum glycoproteins in healthy subjects

BACKGROUND

The functional role of dietary carbohydrates in nutrition is one of the most complex and at times controversial areas in nutritional science. In-vitro and in-vivo studies suggest that certain dietary saccharide biopolymers can have bifidogenic and or immunomodulatory effects, and that some could represent preferential substrates or precursors that can impact cellular glycosylation.

OBJECTIVE

Examine the impact of oral ingestion of a standardized dietary plant-derived polydisperse polysaccharide supplement (Advanced Ambrotose powder (AA)) on the N-glycosylation status of serum glycoproteins in a cohort of healthy individuals.

DESIGN

An open-label study was carried out. This study was in two phases: pilot study (n=6 individuals) to assess safety and dose, and a larger study (n=12) to evaluate specific glycosylation changes. Serum N-glycosylation profiles, using mass spectrometry, were monitored at weekly intervals, for 7 weeks, to evaluate baseline levels and normal fluctuations. The individuals were then monitored for a further 7 weeks, during which time increasing doses of AA were ingested (1.3-5.2 g/day).

RESULTS

No adverse events were encountered. AA supplementation resulted in distinct changes in the relative intensities of seven biantennary N-glycans (P<0.001), and a significant overall shift towards increased sialylation. Regression analysis revealed a dose-dependent decrease in mono- and di-galactosylated structures (coefficient -0.130 decrease/week: P=0.02 and -0.690: P=0.005), and a concomitant increase in disialylated glycans ( × 1.083: P<0.05).

CONCLUSIONS

Supplementation with the dietary plant-derived polysaccharides in AA resulted in significant changes in serum protein N-glycosylation in healthy individuals. How this occurs and whether it has biological significance remains to be evaluated.

Effect of oat bran on time to exhaustion, glycogen content and serum cytokine profile following exhaustive exercise

The aim of this study was to evaluate the effect of oat bran supplementation on time to exhaustion, glycogen stores and cytokines in rats submitted to training. The animals were divided into 3 groups: sedentary control group (C), an exercise group that received a control chow (EX) and an exercise group that received a chow supplemented with oat bran (EX-O). Exercised groups were submitted to an eight weeks swimming training protocol. In the last training session, the animals performed exercise to exhaustion, (e.g. incapable to continue the exercise). After the euthanasia of the animals, blood, muscle and hepatic tissue were collected. Plasma cytokines and corticosterone were evaluated. Glycogen concentrations was measured in the soleus and gastrocnemius muscles, and liver. Glycogen synthetase-α gene expression was evaluated in the soleus muscle. Statistical analysis was performed using a factorial ANOVA. Time to exhaustion of the EX-O group was 20% higher (515 ± 3 minutes) when compared with EX group (425 ± 3 minutes) (p = 0.034). For hepatic glycogen, the EX-O group had a 67% higher concentrations when compared with EX (p = 0.022). In the soleus muscle, EX-O group presented a 59.4% higher glycogen concentrations when compared with EX group (p = 0.021). TNF-α was decreased, IL-6, IL-10 and corticosterone increased after exercise, and EX-O presented lower levels of IL-6, IL-10 and corticosterone levels in comparison with EX group. It was concluded that the chow rich in oat bran increase muscle and hepatic glycogen concentrations. The higher glycogen storage may improve endurance performance during training and competitions, and a lower post-exercise inflammatory response can accelerate recovery.

Lentinan: hematopoietic, immunological, and efficacy studies in a syngeneic model of acute myeloid leukemia

Lentinan, a beta-glucan nutritional supplement isolated from the shitake mushroom (Lentula edodes), is a biological response modifier with immunostimulatory properties. Concomitantly, the role of beta-glucans as chemoimmunotherapeutic in a number of solid cancers has been widely documented. We investigated the effects of nutritional grade lentinan upon BN rats and in a preclinical syngeneic model of acute myeloid leukemia. BN rats supplemented daily with lentinan exhibited weight gains, increased white blood cells, monocytes, and circulating cytotoxic T-cells; and had a reduction in anti-inflammatory cytokines IL-4, IL-10, and additionally IL-6. Lentinan treatment of BN rats with BNML leukemia resulted in improved cage-side health and reduced cachexia in the terminal stage of this aggressive disease. Combination of lentinan with standards of care in acute myeloid leukemia, idarubicin, and cytarabine increased average survival compared with monotherapy and reduced cachexia. These results indicate that nutritional supplementation of cancer patients with lentinan should be further investigated.

Potentiating effect of beta-glucans on photodynamic therapy of implanted cancer cells in mice

Photodynamic therapy (PDT) combines a drug or photosensitizer with a specific type of light to kill cancer cells. The cellular damage induced by PDT leads to activation of the DNA damage repair, which is an important factor for modulating tumor sensitivity to this treatment. beta-Glucans are natural polysaccharides that bind complement receptor 3 on the effector cells, thereby activating them to kill tumor cells during PDT. The hypothesis of the present study was that adjuvant therapy with beta-glucans would increase the efficacy of PDT. C57BL/6 female mice were subcutaneously implanted with Lewis lung carcinoma cells. Ten days after implantation, the mice were administered intravenously sodium porfimer (10 mg/kg) 24 h prior to laser irradiation, with or without oral administration of beta-glucan (400 microg/d/mouse, 5 days) from either barley, baker's yeast, or marine brown algae that contains the storage glucan, laminarin. Tumor volume and necrotic area in excised tumors were measured. The expression of proliferating cell nuclear antigen (PCNA) was determined as an indicator of the activity of the DNA damage repair system. PDT in combination with each beta-glucan significantly reduced tumor growth (P < 0.05, n = 10) and expression of PCNA (P < 0.001, n = 9), and increased necrosis in tumor tissues (P < 0.001, n = 9). Furthermore, each structurally different <beta-glucan exerted similar potentiating effects on PDT. The present findings show that beta-glucans enhance the tumor response to PDT, resulting in pronounced necrosis of PDT-treated tumors and suppression of the DNA damage repair system.

Double diastereoselection explains limitations in synthesizing mannose-containing beta-(1,3)-glucans

It is known that 3-O-glycosylation of glucosidic acceptors bearing acyl groups in the 4 and 6 positions instead of a 4,6-O-benzylidene ring mainly affords alpha-glycosides. Described here is an unexpected stereochemical outcome for elongation at glucose O-3 of a beta-d-Glcp-(1-->3)-alpha-d-Manp disaccharide using peracetylated ethyl thioglucoside as a donor. This unexpected reaction was correlated with match-mismatch effects, as shown by efficient coupling of the same acceptor by a donor of l-configuration.

iC3b-opsonized apoptotic cells mediate a distinct anti-inflammatory response and transcriptional NF-kappaB-dependent blockade

In recent years, it has become apparent that the removal of apoptotic cells by macrophages and DC is not only noninflammatory, but also immune-inhibitory, in most although not all circumstances. Complement may be involved in the uptake of apoptotic cells via direct binding of bridging factors in some physiological circumstances, by opsonization and engagement of the complement receptors. In the current study, we use a complement-dependent system of apoptotic cell clearance by human-derived macrophages and DC. Using a luciferase reporter gene and measuring immune response to non-opsonic zymosan, we show that iC3b-apoptotic cells induce NF-kappaB inhibition in response to zymosan and LPS at the nuclear translocation, transcriptional and post-transcriptional levels, leading to profound inhibition of proinflammatory cytokines. In addition, interaction with iC3b-opsonized apoptotic cells is characterized by macrophage secretion of IL-10 and lack of TGF-beta secretion. In conclusion, in cells with iC3b receptors, opsonized apoptotic cells mediate a distinct anti-inflammatory response and transcriptional NF-kappaB-dependent blockage.

An LFA-1 (alphaLbeta2) small-molecule antagonist reduces inflammation and joint destruction in murine models of arthritis

LFA-1 appears to play a central role in normal immune responses to foreign Ags. In autoimmune or inflammatory diseases, there is increased expression of LFA-1 and/or its counterligand, ICAM-1. Others have demonstrated that the targeted disruption of LFA-1:ICAM interactions, either by gene deletion or Ab treatment in mice, results in reduced leukocyte trafficking, inflammatory responses, and inhibition of inflammatory arthritis in the K/BxN serum transfer model. However, there has been little success in finding a small-molecule LFA-1 antagonist that can similarly impact rodent models of arthritis. In this paper, we present the first reported example of an LFA-1 small-molecule antagonist, BMS-587101, that is efficacious in preclinical disease models. In vitro, BMS-587101 inhibited LFA-1-mediated adhesion of T cells to endothelial cells, T cell proliferation, and Th1 cytokine production. Because BMS-587101 exhibits in vitro potency, cross-reactivity, and oral bioavailability in rodents, we evaluated the impact of oral administration of this compound in two different models of arthritis: Ab-induced arthritis and collagen-induced arthritis. Significant impact of BMS-587101 on clinical score in both models was observed, with inhibition comparable or better than anti-mouse LFA-1 Ab. In addition, BMS-587101 significantly reduced cytokine mRNA levels in the joints of Ab-induced arthritis animals as compared with those receiving vehicle alone. In paws taken from the collagen-induced arthritis study, the bones of vehicle-treated mice had extensive inflammation and bone destruction, whereas treatment with BMS-587101 resulted in marked protection. These findings support the potential use of an LFA-1 small-molecule antagonist in rheumatoid arthritis, with the capacity for disease modification.

Anti-GD2 Strategy in the Treatment of Neuroblastoma

The prognosis for advanced neuroblastoma remains poor with high risk of recurrence after consolidation. Therapies based on monoclonal antibodies that specifically target disialoganglioside GD2 on tumor cells are improving treatment results for high-risk neuroblastoma. This article reviews the use of anti-GD2 antibodies either as monotherapy or as part of a larger and more complex treatment approach for advanced neuroblastoma. We review how anti-GD2 antibodies can be combined with other treatments or strategies to enhance their clinical effects. Tumor resistance and other problems that decrease the efficacy of anti-GD2 antibodies are discussed. Future developments in the area of anti-GD2 immunotherapies for neuroblastoma are also addressed.

An extract based on the medicinal mushroom Agaricus blazei Murill stimulates monocyte-derived dendritic cells to cytokine and chemokine production in vitro

The edible mushroom Agaricus blazei Murill (AbM), which has been used in traditional medicine against a range of diseases and possess immunomodulating properties, probably due to its high content of beta-glucans. Others and we have demonstrated stimulatory effects of extracts of this mushroom on different immune cells. Dendritic cells are major directors of immune function. We wanted to examine the effect of AbM stimulation on signal substance release from monocyte-derived dendritic cells (MDDC). After 6d incubation with IL-4 and GM-CSF, the cells were true MDDC. Then the cells were further incubated with up to 10% of the AbM-based extract, AndoSan, LPS (0.5 microg/ml) or PBS control. We found that the AbM extract promoted dose-dependent increased levels of IL-8, G-CSF, TNFalpha, IL-1beta, IL-6 and MIP-1beta, in that order. The synthesis of IL-2, IL-8 and IFNgamma were similar for the AbM extract and LPS. However, AndoSan induced a 10- to 2-fold higher production than did LPS of G-CSF, TNFalpha and IL-1beta, respectively. AbM did not induce increased synthesis of Th2 or anti-inflammatory cytokines or the Th1 cytokine IL-12. We conclude that stimulation of MDDC with an AbM-based extract resulted in increased production of proinflammatory, chemotactic and some Th1-type cytokines in vitro.

Understanding gene expression patterns in immune-mediated disorders

Gene expression profiling of peripheral blood cells can provide dynamic information regarding the host response to immune-mediated disorders. AlloMap molecular expression testing from XDx monitors the expression of 20 genes in peripheral blood mononuclear cells (PBMC) to discriminate cardiac allograft recipients of 15 years or greater who are at low risk for acute cellular rejection (ACR). The AlloMap test classifier is based on the expression level of 11 genes, encoding proteins with diverse functions, which are differentially expressed in stable patients with moderate to severe ACR compared to patients without ACR. The nine other test genes are used for normalizing gene expression levels and assuring sample quality. In this work we review the development processes leading to the selection of the 11 informative genes and the derivation of the AlloMap test classifier, and discuss the relationship of peripheral blood gene expression with diverse pathways associated with ACR, including T-cell priming, platelet activation, systemic responses to allograft inflammation, and the overall state of immunosuppression.

Beta-glucan-indomethacin combination produces no lethal effects

BACKGROUND

The most important quality of beta-glucans and the reason why so much attention has been devoted to them are their physiological effects. They are typical biological response modifiers with pronounced immunomodulating activity. However, some questions about possible side effects remain.

AIM

Several papers reported the lethal side effects of non-steroidal anti-inflammatory drugs in glucan-treated mice, probably due to the peritonitis by enteric bacteria. However, these results were never independently confirmed. The purpose of this study is to evaluate these claims using several different types of glucans.

METHODS

Effects of combined treatment with four different types of glucans and indomethacin were measured by evaluation of phagocytosis of HEMA particles by peripheral blood leukocytes and production of IL-6 in mouse serum. In addition, the level of blood glucose, colon length and survival after 30 days of treatment was measured.

RESULTS

Our finding showed that simultaneous treatment with glucan and indomethacin caused a small decrease of phagocytic activity and IL-2 production. Two other tested parameters-blood glucose levels and colon length-that had been found to be significantly affected by this treatment, were virtually unchanged. In the final, yet most important part of the study, we found absolutely no mortality, regardless of the type of glucan or the routes of glucan administration.

CONCLUSION

No adverse negative effects due to simultaneous treatment with glucan and non-steroidal anti-inflammatory drug dose was found, despite testing two different routes of glucan administration and four different types of glucan.

Soluble glucomannan isolated from Candida utilis primes blood phagocytes

It is well documented that the polysaccharide glucomannan (GM), an abundant constituent of the fungal cell wall, in the form of particulate induces strong activation of phagocytes, however, the effects of soluble GM are not known. Activation of phagocyte anti-microbial mechanisms is a crucial part of the innate host defense against invading pathogens. However, under uncontrolled inflammatory conditions they contribute to damage of surrounding tissues. Thus, to prevent these deleterious effects, the activation of phagocytes is a tightly regulated process. Therefore, in this study we analyzed the effect of soluble GM on some neutrophil functions such as reactive oxygen species production, degranulation, and receptor mobilization at the plasma membrane. Soluble GM at the tested concentrations did not stimulate oxidative burst of phagocytes directly but significantly potentiated oxidative burst in response to opsonized zymosan particles. GM induced significant phosphorylation of p47phox subunit of NADPH oxidase on Ser345. This priming effect of GM was accompanied by time and concentration dependent degranulation characterized by increased surface expression of receptors stored in neutrophil granules (CD10, CD11b, CD14, CD35, and CD66b). Degranulation was further confirmed by increase of elastase activity in media. Thus, it could be suggested that soluble GM induces priming of phagocytes connected with their degranulation, the increase of surface receptor expression, and potentiation of oxidative burst response to opsonized particles through the activation of NADPH oxidase.

Benefits of oat β-glucan and sucrose feedings on infection and macrophage antiviral resistance following exercise stress

Oat β-glucan can counteract the exercise-induced increased risk for upper respiratory tract infection (URTI) in mice, which is at least partly mediated by its effects on lung macrophages. Substantial evidence in humans indicates that carbohydrate-containing sports drinks can offset the decreased immune function associated with stressful exercise. However, no studies in animals or humans have directly examined their effects on URTI using a controlled virus-challenge model. We examined the effects of sucrose feedings alone and in combination with oat β-glucan on susceptibility to infection and on macrophage antiviral resistance in mice following stressful exercise. These effects were also examined in rested, nonimmunocompromised control mice. Mice were assigned to one of four groups: H2O (water), sucrose (S), oat β-glucan (OβG), and sucrose + oat β-glucan (S+OβG). OβG and S treatments consisted of a solution of 50% OβG and 6% sucrose, respectively, and were administered in drinking water for 10 consecutive days. Exercise consisted of a treadmill run to fatigue performed on three consecutive days. Mice were then intranasally inoculated with a standardized dose of herpes simplex virus 1 (HSV-1) and monitored for morbidity and mortality for 21 days. Additional mice were used to determine macrophage antiviral resistance. In the exercise experiment, S, OβG, and S+OβG all reduced morbidity ( P < 0.05), while only S+OβG reduced mortality ( P < 0.05). Macrophage antiviral resistance was also increased in S, OβG, and S+OβG treatments ( P < 0.05). In resting controls, S and S+OβG reduced morbidity and mortality ( P < 0.05) and showed a trend toward increased macrophage antiviral resistance. There was no significant additive effect of S and OβG in either control or exercised animals. These data extend our previous work on the benefits of oat β-glucan to show that sucrose feedings have similar effects on susceptibility to respiratory infection and macrophage antiviral resistance in both resting controls and following exercise stress.

Orally administered glucans from the edible mushroom Pleurotus pulmonarius reduce acute inflammation in dextran sulfate sodium-induced experimental colitis

Polysaccharides are one of the most potent mushroom-derived substances exhibiting anti-inflammatory and immunomodulatory properties. The aims of the present study were to determine whether orally administered glucans from the edible mushroom Pleurotus pulmonarius could attenuate or prevent the development of experimental colitis in mice. Colonic inflammation was induced in mice by treatment with 3.5 % dextran sulfate sodium (DSS) for 18 d. Before or after DSS administration, mice were given hot water solubles (HWS) or mycelium extract (ME) (2 or 20 mg per mouse) daily in their food. Colonic damage was macroscopically and histologically evaluated. Inflammation was assessed by changes in colon length, TNF-alpha levels released by colonic samples in organ culture and myeloperoxidase (MPO) activity. mRNA levels of pro-inflammatory (IL-1beta) and anti-inflammatory (IL-10) cytokines in colonic samples were determined by quantitative real-time RT-PCR. P. pulmonarius glucans attenuated and prevented the development of symptoms associated with DSS-induced colitis. High doses of HWS and ME blocked colon shortening, suppressed MPO activity and improved macroscopic score in all treatment groups. In addition, histological damage from colitis was reduced by HWS and ME at all doses. The tissue levels of TNF-alpha protein were significantly decreased and correlated with degree of inflammation and macroscopic score. All treatments significantly attenuated the increased DSS-mediated expression levels of IL-1beta. We conclude that the different glucan preparations (HWS or ME) harvested from P. pulmonarius when orally administered to DSS-treated mice attenuate the development of colonic inflammation, suggesting putative clinical utility for these extracts in the treatment of colitis.

Intracellular life of Coxiella burnetii in macrophages

Coxiella burnetii, the agent of Q fever, is an obligate intracellular bacterium that is considered a potential biological weapon of category B. C. burnetii survives within myeloid cells by subverting receptor-mediated phagocytosis and preventing phagosome maturation. The intracellular fate of C. burnetii also depends on the functional state of myeloid cells. This review describes the mechanisms used by C. burnetii to circumvent uptake and trafficking events, and the role of cytokines on C. burnetii survival in myeloid cells.

Effect of an extract based on the medicinal mushroom Agaricus blazei murill on release of cytokines, chemokines and leukocyte growth factors in human blood ex vivo and in vivo

An immunostimulatory extract based on the medicinal mushroom Agaricus blazei Murill (AbM) has been shown to stimulate mononuclear phagocytes in vitro to produce pro-inflammatory cytokines, and to protect against lethal peritonitis in mice. The present aim was to study the effect of AbM on release of several cytokines in human whole blood both after stimulation ex vivo and in vivo after oral intake over several days in healthy volunteers. The 17 signal substances examined were; T helper 1 (Th1) cytokines [interleukin (IL)-2, interferon (IFN)-gamma and IL-12], T helper 2 cytokines (IL-4, IL-5 and IL-13), pleiotropic (IL-7, IL-17), pro-inflammatory [IL-1beta, IL-6, tumour necrosis factor (TNF)-alpha (mainly produced by Th1 cells)]--and anti-inflammatory (IL-10) cytokines, chemokines [IL-8, macrophage inhibitory protein (MIP)-1beta and monocyte chemoattractant protein (MCP)-1] and leukocyte growth factors [granulocyte colony-stimulating factor (G-CSF), granulocyte/macrophage colony stimulating factor]. After stimulation of whole blood ex vivo with 0.5-5.0% of a mushroom extract, AndoSan mainly containing AbM, there was a dose-dependent increase in all the cytokines studied, ranging from two to 399-fold (TNF-alpha). However, in vivo in the eight volunteers who completed the daily intake (60 ml) of this AbM extract for 12 days, a significant reduction was observed in levels of IL-1beta (97%), TNF-alpha (84%), IL-17 (50%) and IL-2 (46%). Although not significant, there was a trend towards reduced levels for IL-8, IFN-gamma and G-CSF, whilst those of the remaining nine cytokines tested, were unaltered. The discrepant results on cytokine release ex vivo and in vivo may partly be explained by the antioxidant activity of AbM in vivo and limited absorption of its large, complex and bioactive beta-glucans across the intestinal mucosa to the reticuloendothelial system and blood.

Beta-glucans, history, and the present: immunomodulatory aspects and mechanisms of action

The present paper represents a comprehensive up-to-date review of beta -glucans, their chemical and biological properties, and their role in immunological reactions. beta -D-Glucans belong to a group of physiologically active compounds called biological response modifiers and represent highly conserved structural components of cell walls in yeast, fungi, or seaweed. Despite almost 150 years of research, the exact mechanisms of their action remain unclear. The present review starts with the history of glucans. Next, attention is focused on sources and structure, comparing the effects of physicochemical properties, and sources on biological effects. As glucans belong to natural products useful in preventing various diseases, they have been highly sought after throughout human history. Based on extensive recent research, this paper explains the various mechanisms of effects and the ways glucans mediate their effects on defense reactions against infections. Despite the fact that predominately pharmacological effects of glucans are positive, their unfavorable and potentially toxic side effects were not overlooked. In addition, attention was focused on the future research, possible alternatives such as synthetic oligosaccharides, and on clinical applications.

Activation of human neutrophil Mac-1 by anion substitution

Substituting the medium chloride with glucuronate or glutamate causes a rapid, 10 to 30-fold, increase in the binding of the monoclonal antibody, CBRM1/5, which recognizes the high-affinity conformation of the Mac-1 integrin. This change is reflected in functional adhesion assays that show increased adhesion to ICAM-1 coated beads. Blocking antibodies indicate that the increased adhesion is almost entirely due to Mac-1. The inhibitor NPPB (100 microM) reduces Cl(-) efflux into low Cl(-) medium by 75%, and blocks increased CBRM1/5 binding after stimulation with fMLP or TNF-alpha, but has no effect on the anion substitution induced increase in CBRM1/5 binding or adhesion to immobilized ICAM-1. Thus, changes in external anion composition, not internal chloride or increases in Cl(-) efflux, are responsible for Mac-1 activation. This effect is substantial. The percentage of Mac-1 in the high affinity state approaches 100% in glutamate and 50% in glucuronate, a far greater response than what is observed after stimulation with fMLP.

Combined yeast-derived beta-glucan with anti-tumor monoclonal antibody for cancer immunotherapy

Beta-glucan is an immuno-stimulating agent that has been used to treat cancer and infectious disease for many years with varying and unpredictable efficacy. Recent studies have unraveled the action mode of yeast-derived beta-glucan in combination with anti-tumor monoclonal antibodies (mAbs) in cancer therapy. It has demonstrated that particulate or large molecular weight soluble beta-glucans are ingested and processed by macrophages. These macrophages secrete the active moiety that primes neutrophil complement receptor 3 (CR3) to kill iC3b-opsonized tumor cells. In vitro and in vivo data demonstrate that successful combination therapy requires complement activation and deposition on tumors and CR3 expression on granulocytes. Pre-clinical animal studies have demonstrated the efficacy of combined beta-glucan with anti-tumor mAb therapy in terms of tumor regression and long-term survival. Clinical trials are underway using anti-epidermal growth factor receptor mAb (cetuximab) in combination with beta-glucan for metastatic colorectal cancer. This review provides a brief overview of this combination therapy in cancer and describes in detail the beta-glucan composition and structure, mechanism of action, and preclinical studies in human carcinoma xenograft models. It is proposed that the addition of beta-glucan will further improve the therapeutic efficacy of anti-tumor mAbs in cancer patients.

Complement receptor of the Ig superfamily enhances complement-mediated phagocytosis in a subpopulation of tissue resident macrophages

An important function of the complement cascade is to coat self and foreign particles with C3-proteins that serve as ligands for phagocytic receptors. Although tissue resident macrophages play an important role in complement-mediated clearance, the receptors coordinating this process have not been well characterized. In the present study, we identified a subpopulation of resident peritoneal macrophages characterized by high expression of complement receptor of the Ig superfamily (CRIg), a recently discovered complement C3 receptor. Macrophages expressing CRIg showed significantly increased binding and subsequent internalization of complement-opsonized particles compared with CRIg negative macrophages. CRIg internalized monovalent ligands and was able to bind complement-opsonized targets in the absence of Ca(2+) and Mg(2+), which differs from the beta(2)-integrin CR3 that requires divalent cations and polyvalent ligands for activation of the receptor. Although CRIg dominated in immediate binding of complement-coated particles, CRIg and CR3 contributed independently to subsequent particle phagocytosis. CRIg thus identifies a subset of tissue resident macrophages capable of increased phagocytosis of complement C3-coated particles, a function critical for immune clearance.

Efeitos da suplementação de fibras solúveis sobre as células do sistema imune após exercício exaustivo em ratos treinados

A intensidade, volume, modalidade de exercício, assim como o nível de aptidão e fatores nutricionais podem alterar a reposta imunológica. O objetivo deste estudo foi avaliar o efeito da suplementação crônica de farelo de aveia (fonte de fibras solúveis) sobre as células do sistema imunológico em ratos treinados, frente a um teste de exaustão. Foram utilizados ratos Wistar, ± dois meses, peso ± 200g, divididos em três grupos (n = 9, cada um): 1) controle sedentário (C); 2) treinado oito semanas submetido ao teste de exaustão (EX); e 3) treinado oito semanas submetido ao teste de exaustão com suplementação de 30% de farelo de aveia (EXA). O treinamento consistiu de 60 minutos de natação diários, cinco dias por semana durante oito semanas. As análises realizadas foram: contagem total de leucócitos, linfócitos dos linfonodos mesentéricos, macrófagos peritoneais e capacidade fagocitária de macrófagos peritoneais. Aplicou-se o teste estatístico ANOVA two way, seguido do post hoc de Tukey com p < 0,05. O grupo EX apresentou leucocitose quando comparado com o controle, o que não ocorreu no grupo EXA, porém, na comparação entre os grupos exercitados EXA, mostrou menor leucocitose em relação a EX. Não houve alteração significativa nos linfócitos teciduais em nenhum dos grupos exercitados. Tanto o número de macrófagos peritoneais como a capacidade fagocitária desta célula foram maiores nos grupos exercitados. Porém, no grupo suplementado a capacidade fagocitária foi maior em relação ao grupo exaustão sem farelo de aveia. A suplementação de fibras solúveis demonstrou resultados benéficos com relação às alterações imunológicas induzidas pelo exercício extenuante, além de aumentar a capacidade fagocitária de macrófagos peritoniais em ratos treinados durante oito semanas submetidos ao teste de exaustão.

Role of very long fatty acid-containing glycosphingolipids in membrane organization and cell signaling: the model of lactosylceramide in neutrophils

Glycosphingolipids are highly enriched in specialized membrane microdomains ("lipid rafts", caveolar domains and glycosynapses), and they participate to the process of transduction of information across the membrane. Lactosylceramide (LacCer) is specifically coupled with the Src family kinase Lyn in plasma membrane microdomains of human neutrophils. Ligand binding to LacCer activates Lyn, resulting in neutrophil functions, such as superoxide generation and migration. The beta-Gal-(1-4)-beta-Glc disaccharide structure of LacCer is necessary, but it is not sufficient for LacCer-mediated Lyn activation. For this function, the presence of a LacCer molecular species with ceramide containing a very long fatty acid chain is also required. In this manuscript, we discuss the importance of interdigitation within the membrane, promoted by the presence of glycosphingolipid species with very long fatty acyl chains as determinants for membrane organization, instrumental to the signaling process.