Aureobasidium-derived soluble branched (1,3-1,6) beta-glucan (Sophy beta-glucan) enhances natural killer activity in Leishmania amazonensis-infected mice

Investigating Therapeutic Potential of Beta-Glucan on Experimental Toxoplasmosis in Immunocompetent and Immunocompromised Mice: In Silico and in Vivo Studies

There is a need to find efficient treatment for toxoplasmosis, a global disease with a public health concern, as the used therapeutics have limited effectiveness. Beta-glucan (β-glucan), a natural polysaccharide, has anti-inflammatory, immunomodulatory, and anti-infective activities against bacteria, viruses, and parasites. We aimed to investigate the therapeutic efficacy of β-glucan on toxoplasmosis using an in silico study and an in vivo mice model. The β-glucan drug-likeness characteristics were evaluated by molecular docking simulations, Lipinski's RO5 filter analysis, and the computational quantitative structural-activity relationships/absorption, distribution, metabolism, excretion, and toxicity predictive characteristics compared to spiramycin, an anti-toxoplasmosis drug. Sixty albino mice were divided into two divisions, immunocompetent and immunosuppressed. Each division contained five groups; healthy, diseased, spiramycin-treated, β-glucan-treated, and both β-glucan and spiramycin-treated groups. Parasitological, histopathological examinations, and immunological analysis were detected. β-glucan docked complexes demonstrated H-bonding and hydrophobic interactions towards their promising anti-toxoplasmosis targets compared to the spiramycin. The treated mice revealed a statistically significant reduction (p < 0.001) in the parasite burden. Regarding immunocompetent and immunosuppressed division, the group that was treated with both β-glucan and spiramycin, demonstrated the greatest outcomes, with 71% and 66% efficacy, respectively. It is concluded that β-glucan shows promising potential as an anti-toxoplasmosis candidate by potentiating the spiramycin effect and modulating the immunological response.

Botryosphaeran, [(1 → 3)(1 → 6)-β-D-glucan], induces apoptosis-like death in promastigotes of Leishmania amazonensis, and exerts a leishmanicidal effect on infected macrophages by activating NF-kB and producing pro-inflammatory molecules

Leishmaniasis is an infectious-parasitic disease caused by the protozoan Leishmania spp. The available treatments are based upon expensive drugs bearing adverse side-effects. The search for new therapeutic alternatives that present a more effective action without causing adverse effects to the patient is therefore important. The objective of this study was to evaluate the in vitro effect of botryosphaeran, a (1 → 3)(1 → 6)-β-D-glucan, on the promastigote and intracellular amastigote forms of Leishmania amazonensis. The direct activity of botryosphaeran on promastigote forms was evaluated in vitro and inhibited proliferation, the IC50 7 μg/mL in 48 h was calculated. After 48 h treatment, botryosphaeran induced nitric oxide production (NO), caused mitochondrial membrane hyperpolarization, increased reactive oxygen species (ROS), and accumulation of lipid vesicles in promastigotes, resulting in apoptosis, necrosis and autophagy, and was accompanied by morphological and ultrastructural changes. The range of concentrations used did not alter the viability of peritoneal macrophages from BALB/c mice and erythrocytes of sheep. Botryosphaeran was able to reduce the number of infected macrophages and the number of amastigotes per macrophage at 12.5 μg/mL (50.75% ± 6.48), 25 μg/mL (55.66% ± 3.93) and 50 μg/mL (72.9% ± 6.98), and IC50 9.3 μg/mL (±0.66) for intracellular amastigotes forms. The leishmanicidal effect was due to activation of NF-κB and promoted an increase in pro-inflammatory cytokines (TNF-α and IL-6), iNOS and microbial-derived ROS and NO, in addition to decreasing the levels of SOD. Based upon the data obtained, we infer that botryosphaeran exerted an active leishmanicidal and immunomodulatory effect, acting on promastigotes through autophagic, apoptotic and necrosis processes, and in the intracellular amastigote form, through the action of ROS and NO.

β‑glucan vaccine adjuvant approach for cancer treatment through immune enhancement (B‑VACCIEN) in specific immunocompromised populations (Review)

The incidence of cancer, which is the second leading cause of mortality globally, continues to increase, although continued efforts are being made to identify effective treatments with fewer side‑effects. Previous studies have reported that chronic microinflammation, which occurs in diseases, including diabetes, along with weakened immune systems, may ultimately lead to cancer development. Chemotherapy, radiotherapy and surgery are the mainstream approaches to treatment; however, they all lead to immune system weakness, which in turn increases the metastatic spread. The aim of the present review was to provide evidence of a biological response modifier β‑glucan [β‑glucan vaccine adjuvant approach to treating cancer via immune enhancement (B‑VACCIEN)] and its beneficial effects, including vaccine‑adjuvant potential, balancing metabolic parameters (including blood glucose and lipid levels), increasing peripheral blood cell cytotoxicity against cancer and alleviating chemotherapy side effects in animal models. This suggests its value as a potential strategy to provide long‑term prophylaxis in immunocompromised individuals or genetically prone to cancer.

β-glucans: wide-spectrum immune-balancing food-supplement-based enteric (β-WIFE) vaccine adjuvant approach to COVID-19

Conventional vaccines to combat COVID-19 through different approaches are at various stages of development. The complexity of COVID-19 such as the potential mutations of the virus leading to antigenic drift and the uncertainty on the duration of the immunity induced by the vaccine have hampered the efforts to control the COVID-19 pandemic. Thus, we suggest an alternative interim treatment strategy based on biological response modifier glucans such as the Aureobasidium pullulans AFO-202-derived β-glucan, which has been reported to induce trained immunity, akin to that induced by the Bacille Calmette-Guérin vaccine, by epigenetic modifications at the central level in the bone marrow. These β-glucans act as pathogen-associated molecular patterns, activating mucosal immunity by binding with specific pathogen recognition receptors such as dectin-1 and inducing both the adaptive and innate immunity by reaching distant lymphoid organs. β-Glucans have also been used as immune adjuvants for vaccines such as the influenza vaccine. Therefore, until a conventional vaccine is widely available, an orally consumable vaccine adjuvant that acts like biosimilars, termed as the wide-spectrum immune-balancing food-supplement-based enteric (β-WIFE) vaccine adjuvant approach, with well-reported safety is worth in-depth investigation and can be considered for a clinical trial.

COVID-19 and Possible Pharmacological Preventive Options

The dreadful fear of the coronavirus disease 2019 (COVID-19), which is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with the deadly consequences, requires rapid development of pharmacological cures. The objective of this review is to speculate about possible pharmacological options, already available today to prevent or treat the COVID-19 in the early stage of its outbreak. A literature search across PubMed and internet was conducted. A number of studies dealing with COVID-19 were identified. The data elucidated that increased pro-inflammatory and decreased anti-inflammatory cytokines in combination with hypoxia, thromboembolism and pneumonia are involved in the pathogenesis of SARS-CoV-2 infection. Although many drugs has been tested in monotherapy regimen with varying outcome or without desirable effect, there is still hope for better results by simultaneously targeting the virus itself and its symptoms. Theoretically, a mixture of at least two available antiviral drugs in combination with other anti-pathogenic and immune system-enhancing drugs or combination of antiviral drugs with convalescent plasma seems likely to have much better effect than the monotherapy regimen of either of these drugs.

Coagulopathy associated with COVID-19 - Perspectives & Preventive strategies using a biological response modifier Glucan

Direct endothelial injury by viruses and dysregulation of clotting mechanisms due to cytokine storm are the major precipitating factors of mortality in COVID-19; both are attributed to a fundamental dysregulation of the immune system. While immune dysregulation can be attributed to several factors, the risk of associated thrombogenic disruption varies across individuals. This variation depends on several factors, such as comorbidities, including diabetes, hypertension, and cardiovascular diseases. When considering ethnic variations, the vulnerability of Caucasians, African Americans and Hispanics needs to be addressed before arriving at strategies to handle thromboembolic complications, which have been identified in recent reports as the leading causes of mortality in COVID-19. Although evaluation of D-dimer and prothrombin during admission is considered to predict prognosis and mortality, there are no preventive or prophylactic strategies before hospital admission. Herein, we present our perspectives on the effect of regular supplementation with the biological response modifier beta glucan based on its relevance to immune modulation. This effect is of paramount importance in decreasing the development of severe COVID-19 and reducing mortality against the background of coagulopathy, especially in vulnerable populations.

Role of Immune Dysregulation in Increased Mortality Among a Specific Subset of COVID-19 Patients and Immune-Enhancement Strategies for Combatting Through Nutritional Supplements

Background: The COVID-19 pandemic has been causing varying severities of illness. Some are asymptomatic and some develop severe disease leading to mortality across ages. This contrast triggered us explore the causes, with the background that a vaccine for effective immunization or a drug to tackle COVID-19 is not too close to reality. We have discussed strategies to combat COVID-19 through immune enhancement, using simple measures including nutritional supplements. Discussion: A literature search on mortality-related comorbid conditions was performed. For those conditions, we analyzed the pro-inflammatory cytokines, which could cause the draining of the immune reservoir. We also analyzed the immune markers necessary for the defense mechanism/immune surveillance against COVID-19, especially through simple means including immune enhancing nutritional supplement consumption, and we suggest strategies to combat COVID-19. Major comorbid conditions associated with increased mortality include cardiovascular disease (CVD), diabetes, being immunocompromised by cancer, and severe kidney disease with a senile immune system. Consumption of Aureobasidium pullulans strain (AFO-202) beta 1,3-1,6 glucan supported enhanced IL-8, sFAS macrophage activity, and NK cells' cytotoxicity, which are major defense mechanisms against viral infection. Conclusion: People with co-morbid conditions who are more prone to COVID-19-related deaths due to immune dysregulation are likely to benefit from consuming nutritional supplements that enhance the immune system. We recommend clinical studies to validate AFO-202 beta glucan in COVID-19 patients to prove its efficacy in overcoming a hyper-inflammation status, thus reducing the mortality, until a definite vaccine is made available.

The preventable efficacy of β-glucan against leptospirosis

Leptospirosis, caused by pathogenic Leptospira species, has emerged as an important neglected zoonotic disease. Few studies have reported the preventable effects of immunoregulators, except for antibiotics, against leptospirosis. Generally, immunostimulatory agents are considered effective for enhancing innate immune responses. Many studies have found that beta-glucan (β-glucan) could be a potent and valuable immunostimulant for improving immune responses and controlling diseases. In this study, we investigated the preventable role of β-glucan against Leptospira infection in hamsters. First, β-glucan was administered 24 h prior to, during and after infection. The results showed that β-glucan increased the survival rate to 100%, alleviated tissue injury, and decreased leptospire loads in target organs. Additionally, we found using quantitative real-time PCR that application of β-glucan significantly enhanced the expression of Toll-like receptor (TLR) 2, interleukin (IL)-1β and iNOS at 2 dpi (days post infection) and reduced the increase of TLR2, IL-1β and iNOS induced by Leptospira at 5 dpi. Furthermore, to induce memory immunity, β-glucan was administered 5 days prior to infection. β-Glucan also significantly increased the survival rates and ameliorated pathological damage to organs. Moreover, we demonstrated that β-glucan-trained macrophages exhibited elevated expression of proinflammatory cytokines (IL-1β and IL-6) in vitro, indicating that β-glucan induces an enhanced inflammatory response against Leptospira infection. These results indicate that administration of β-glucan and other immunostimulants could be potential valuable options for the control of Leptospira infection.

β-Glucan and Parasites

Immunosuppression caused by parasitic infections represents the foremost way by which the parasites overcome or escape the host’s immune response. Glucan is a well-established natural immunomodulator with the ability to significantly improve immune system, from innate immunity to both branches of specific immunity. Our review is focused on the possible role of glucan’s action in antiparasite therapies and vaccine strategies. We concluded that the established action of glucan opens a new window in treatment and protection against parasitic infections.

Modulation of inflammation response to murine cutaneous Leishmaniasis by homeopathic medicines: Antimonium crudum 30cH

Background: Leishmaniasis is a zoonotic disease caused by protozoan parasites of the mononuclear phagocytic system. The modulation activity of these cells can interfere in the host/parasite relationship and influences the prognosis.

Methods: We evaluated the effects of the homeopathic preparation Antimonium crudum 30cH on experimental infection induced by Leishmania (L.) amazonensis. Male Balb/c mice were inoculated with 2 × 106 Leishmania (L.) amazonensis promastigotes into the footpad and, after 48 h (acute phase) or 60 days (chronic phase), cell population of lymphocytes and phagocytes present in the peritoneal washing fluid and spleen were analyzed by flow cytometry and histopathology, with histometry of the subcutaneous primary lesion, local lymph node and spleen. Immunohistochemistry was performed to quantify CD3 (T lymphocyte), CD45RA (B lymphocyte) and CD11b (phagocytes) positive cells.

Results: In treated mice, during the acute phase, there was significant increase of the macroscopic lesion, associated to inflammatory edema, as well increase in the number of free amastigotes and B lymphocytes inside the lesion. Increase of B lymphocytes (predominantly B-2 cells) was also seen in the local lymph node, spleen and peritoneum. In the chronic phase, the inflammatory process in the infection focus was reduced, with reduced phagocyte migration and peritoneal increase of B-1a cells (precursors of B-2 immunoglobulin producers cells) and T CD8+ cells.

Conclusion: The treatment of mice with Antimonium crudum 30cH induced a predominantly B cell pattern of immune response in Leishmania (L.) amazonensis experimental infection, alongside the increase of free amastigote forms number in the infection site. The clinical significance of this study is discussed, further studies are suggested.

Effect of the Medicinal Agaricus blazei Murill-Based Mushroom Extract, AndoSanTM, on Symptoms, Fatigue and Quality of Life in Patients with Crohn's Disease in a Randomized Single-Blinded Placebo Controlled Study

Background

Ingestion of AndoSan^TM, based on the mushroom Agaricus blazei Murill, has previously shown an anti-inflammatory effect through reduction of pro-inflammatory cytokines in healthy individuals and patients with Crohn’s disease (CD). In this randomized single-blinded placebo-controlled study we examined whether intake of AndoSan^TM also resulted in clinical effects.

Methods and Findings

50 patients with symptomatic CD were randomized for oral daily consumption of AndoSan^TM or placebo for a 21-day experimental period, in this per-protocol study. Patients reported validated scores for symptoms, fatigue and health related quality of life (HRQoL) at days 0, 14 and 21. Fecal calprotectin and general blood parameters were also analyzed. In the AndoSan^TM group (n = 25) symptoms improved from baseline (day 0) to days 14 and 21, with respective mean scores (95% CI) of 5.52 (4.64–6.40), 4.48 (3.69–5.27) and 4.08 (3.22–4.94) (p<0,001). We found significant improvements in symptom score for both genders in the AndoSan^TM group, and no significant changes in the placebo (n = 25) group. There were however no significant differences between the groups (p = 0.106), although a marginal effect in symptom score for men (p = 0.054). There were comparable improvements in physical, mental and total fatigue for both groups. HRQoL versus baseline were at day 21 improved for bodily pain and vitality in the AndoSan^TM group and for vitality and social functioning in the placebo group. No crucial changes in general blood samples and fecal calprotectin were detected.

Conclusions

The results from this single-blinded randomized clinical trial shows significant improvement on symptoms, for both genders, in the AndoSan^TM group, but no significant differences between the study groups. The results on fatigue, HRQoL, fecal calprotectin and blood samples were quite similar compared with placebo. The patients did not report any harms or unintended effects of AndoSan^TM. CD patients with mild to moderate symptoms may have beneficiary effects of AndoSan^TM as a safe supplement in addition to conventional medication.

Trial Registration

ClinicalTrials.gov NCT01496053

Effect of Immune-Enhancing Enteral Nutrition Enriched with or without Beta-Glucan on Immunomodulation in Critically Ill Patients

We investigated whether high-protein enteral nutrition with immune-modulating nutrients (IMHP) enriched with β-glucan stimulates immune function in critically ill patients. In a randomized double-blind placebo-controlled study, 30 patients consumed one of three types of enteral nutrition: a control or IMHP with and without β-glucan. The IMHP with β-glucan group showed increases in natural killer (NK) cell activities relative to the baseline, and greater increases were observed in NK cell activities relative to the control group after adjusting for age and gender. The IMHP groups with and without β-glucan had greater increases in serum prealbumin and decreases in high-sensitivity C-reactive protein (hs-CRP) than the control group. The control group had a greater decrease in peripheral blood mononuclear cell (PBMC) interleukin (IL)-12 production than the IMHP with and without β-glucan groups. In all patients, the change (Δ) in hs-CRP was correlated with Δ prealbumin and Δ PBMC IL-12, which were correlated with ΔNK cell activity and Δ prealbumin. This study showed beneficial effects of a combination treatment of β-glucan and IMHP on NK cell activity. Additionally, strong correlations among changes in NK cell activity, PBMC IL-12, and hs-CRP suggested that β-glucan could be an attractive candidate for stimulating protective immunity without enhanced inflammation (ClinicalTrials.gov: NCT02569203).

Oral administration of the Aureobasidium pullulans-derived β-glucan effectively prevents the development of high fat diet-induced fatty liver in mice

Aureobasidium pullulans-derived β-glucan (AP-PG) consisting of a β-(1,3)-linked glucose main chain and β-(1,6)-linked glucose branches is taken as a supplement to improve health. This study demonstrates that oral administration of AP-PG is effective to prevent the development of high-fat diet (HFD)-induced fatty liver in mice. Here, C57BL/6N mice were fed with a normal diet or HFD, and AP-PG diluted in drinking water was administered orally. After 16 weeks, the serological analysis showed that HFD-induced high blood cholesterol and triglyceride levels were reduced by the oral administration of AP-PG. Further, HFD induced-fatty liver was significantly reduced by the oral administration of AP-PG. The triglyceride accumulation in the liver was also significantly reduced in mice administered AP-PG. Liver injury as indicated by an increase in serum alanine aminotransferase (ALT) in the HFD-fed mice was significantly reduced in the mice administered AP-PG orally, and the gene expression of cholesterol 7 alpha-hydroxylase (CYP7A1) which is known to be involved in cholesterol degradation in the liver was significantly increased in the AP-PG administered mice. These results suggest the possibility that the oral administration of AP-PG is effective to prevent the development of non-alcoholic fatty liver disease (NAFLD).

Stimulation of macrophages with the β-glucan produced by aureobasidium pullulans promotes the secretion of tumor necrosis factor-related apoptosis inducing ligand (TRAIL)

A β-glucan produced by Aureobasidium pullulans (AP-PG) is consisting of a β-(1,3)-linked main chain with β-(1,6)-linked glucose side residues. Various β-glucans consisting of β-(1,3)-linked main chain including AP-PG are believed to exhibit anti-tumor activities, and actually, anti-tumor activities of AP-PG in mice have been demonstrated. In this study, we demonstrate that stimulation with AP-PG induces TRAIL expression in mouse and human macrophage-like cell lines. TRAIL is known to be a cytokine which specifically induces apoptosis in transformed cells, but not in untransformed cells. The expression of TRAIL mRNA after stimulation with AP-PG was increased in RAW264.7 cells, Mono Mac 6 cells, and macrophage-differentiated THP-1 cells. The mRNA expression of TNF-α and FasL is only weakly increased after stimulation with AP-PG. The induction activity of TRAIL by curdlan, a bacterial β-glucan, was very similar to that by AP-PG in RAW264.7 cells, but weaker in macrophage-differentiated THP-1 cells. Activation of caspases was found in HeLa cells after treatment with the supernatant of cultured medium from AP-PG-stimulated Mono Mac 6 cells, and was inhibited by the anti-TRAIL neutralizing antibody. These findings suggest that the stimulation with AP-PG effectively induces TRAIL in macrophages, and that it may be related to apoptosis induction of tumor cells.

Fermentation of non-sterilized fish biomass with a mixed culture of film-forming yeasts and lactobacilli and its effect on innate and adaptive immunity in mice

Non-sterilized fish waste containing fish bones was fermented using combined starter cultures of film-forming yeast (Candida ethanolica) and lactic acid bacteria (LAB; Lactobacillus casei and Lactobacillus rhamnosus) in order to obtain a liquefied fermented broth without spoiling. During the entire fermentation, the number of LAB cells was maintained at a high level (6 × 10(8)-5 × 10(7) cells/ml). Although the number of general bacteria was 10(6)cell/ml after adding non-sterilized fish biomass, its growth was suppressed to be 1-3 × 10(4) cells/ml. The entire biomass had completely liquefied and the fermented broth contained all 20 α-amino acids composed of protein and also various kinds of minerals in abundance. The weight of mice group fed the fermented broth content feed (sample feed) for 31 days significantly increased compared with that fed no broth feed (control feed) (21.37 g vs 20.76 g (p < 0.05). No abnormal behavior and appearance were observed. All internal organs (the heart, the liver, the lung, the intestines, and the spleen) of both groups were confirmed to be normal by visual observation. In peripheral blood, the percentages of NK cells and CD8+ T cells of the mice in the sample feed group increased significantly relative to those in the control feed group (NK cells: 19% vs 11%, CD8+ T cells: 9% vs 5%, p < 0.05). In the spleen, the percentage of NK cells in the sample feed group also increased significantly compared to that in the control feed group (p < 0.05). The fermented fish biomass is expected to be effective for innate and adaptive immunity and thus fit for animal feed.

β-Glucan derived from Aureobasidium pullulans is effective for the prevention of influenza in mice

β-(1→3)-D-glucans with β-(1→6)-glycosidic linked branches produced by mushrooms, yeast and fungi are known to be an immune activation agent, and are used in anti-cancer drugs or health-promoting foods. In this report, we demonstrate that oral administration of Aureobasidium pullulans-cultured fluid (AP-CF) enriched with the β-(1→3),(1→6)-D-glucan exhibits efficacy to protect mice infected with a lethal titer of the A/Puerto Rico/8/34 (PR8; H1N1) strain of influenza virus. The survival rate of the mice significantly increased by AP-CF administration after sublethal infection of PR8 virus. The virus titer in the mouse lung homogenates was significantly decreased by AP-CF administration. No significant difference in the mRNA expression of inflammatory cytokines, and in the population of lymphocytes was observed in the lungs of mice administered with AP-CF. Interestingly, expression level for the mRNA of virus sensors, RIG-I (retinoic acid-inducible gene-I) and MDA5 (melanoma differentiation-associated protein 5) strongly increased at 5 hours after the stimulation of A. pullulans-produced purified β-(1→3),(1→6)-D-glucan (AP-BG) in murine macrophage-derived RAW264.7 cells. Furthermore, the replication of PR8 virus was significantly repressed by pre-treatment of AP-BG. These findings suggest the increased expression of virus sensors is effective for the prevention of influenza by the inhibition of viral replication with the administration of AP-CF.

A small scale study on the effects of oral administration of the β-glucan produced by Aureobasidium pullulans on milk quality and cytokine expressions of Holstein cows, and on bacterial flora in the intestines of Japanese black calves

BACKGROUND

The β-(1 → 3),(1 → 6)-D-glucan extracellularly produced by Aureobasidium pullulans exhibits immunomodulatory activity, and is used for health supplements. To examine the effects of oral administration of the β-(1 → 3),(1 → 6)-D-glucan to domestic animals, a small scale study was conducted using Holstein cows and newborn Japanese Black calves.

FINDINGS

Holstein cows of which somatic cell count was less than 3 x 10⁵/ml were orally administered with or without the β-(1 → 3),(1 → 6)-D-glucan-enriched A. pullulans cultured fluid (AP-CF) for 3 months, and the properties of milk and serum cytokine expression were monitored. Somatic cell counts were not significantly changed by oral administration of AP-CF, whereas the concentration of solid non fat in the milk tended to increase in the AP-CF administered cows. The results of cytokine expression analysis in the serum using ELISA indicate that the expressions of tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 in all cows which were orally administered with AP-CF became slightly lower than that of control cows after the two-month treatment. On the other hand, IL-8 expression tended to indicate a moderately higher level in all treated cows after the three-month administration of AP-CF in comparison with that of the control cows. Peripartum Japanese Black beef cows and their newborn calves were orally administered with AP-CF, and bacterial flora in the intestines of the calves were analyzed by T-RFLP (terminal restriction fragment length polymorphism). The results suggest that bacterial flora are tendentiously changed by oral administration of AP-CF.

CONCLUSIONS

Our data indicated the possibility that oral administration of the β-(1 → 3),(1 → 6)-D- glucan produced by A. pullulans affects cytokine expressions in the serum of Holstein cows, and influences bacterial flora in the intestines of Japanese Black calves. The findings may be helpful for further study on the efficacies of oral administration of β-(1 → 3),(1 → 6)-D-glucans on domestic animals.

Natural killer cells in experimental and human leishmaniasis

Infections with parasites of the genus Leishmania lead to a rapid, but transient activation of natural killer (NK) cells. In mice activation of NK cells requires a toll-like-receptor 9-dependent stimulation of dendritic cells (DC) which is followed by the production of IL-12. Although NK cells appear to be non-essential for the ultimate control of cutaneous and visceral leishmaniasis (VL) and can exhibit immunosuppressive functions, they form an important source of interferon (IFN)-γ, which elicits antileishmanial activity in macrophages and helps to pave a protective T helper cell response. In contrast, the cytotoxic activity of NK cells is dispensable, because Leishmania-infected myeloid cells are largely resistant to NK-mediated lysis. In human cutaneous and VL, the functional importance of NK cells is suggested by reports that demonstrate (1) a direct activation or inhibition of NK cells by Leishmania promastigotes, (2) the suppression of NK cell numbers or activity during chronic, non-healing infections, and (3) the recovery of NK cell activity following treatment. This review aims to provide an integrated view on the migration, activation, inhibition, function, and therapeutic modulation of NK cells in experimental and human leishmaniasis.

Effects of Sophy β-glucan on growth performance, carcass traits, meat composition, and immunological responses of Peking ducks

The response of Peking ducks to supplements of Sophy β-glucan was studied. A total of 160 healthy 1-d-old mixed-sex ducklings were randomly allocated to 3 groups: Sophy β-glucan (n = 80), bacitracin zinc (n = 40), and control (n = 40), which received the same antibiotics-deficient diet supplemented with 1% β-glucan, 5% bacitracin zinc, or nothing, respectively. During 2 mo of the study, growth performance, carcass composition, and meat quality of Peking ducks were evaluated. Additionally, a separate immunological study was conducted with a total of 105 healthy male Peking ducks in 7 groups (n = 15) and immunized with different doses of β-glucan (0, 0.5, 2.5, 12.5, and 62.5 μg/duck) and BSA (200 μg/duck). Blood was taken for detection of anti-BSA-IgG antibody and peripheral blood mononuclear cells proliferation assays. Groups subjected to different dietary treatments showed almost no differences in growth performance and slaughter traits except breast muscle percentage and intestinal length. These 2 indicators were significantly higher in the bacitracin zinc group than in the control and β-glucan groups (P < 0.05). Similarly, chemical compositions, fatty acids, and amino acids of breast muscle were not significantly influenced by the diet. Ducks immunized with Sophy β-glucan did not have enhanced level of anti-BSA-IgG antibodies but had significant peripheral blood mononuclear cells proliferation compared with unchallenged ducks (P < 0.01). With an increase in the glucan concentration, the proliferative responses approximately linearly increased. These findings indicate that 1% Sophy glucan did not improve duck growth performance, carcass composition, and meat quality significantly under the conditions of the present experiment and mainly had regulatory or enhancing properties on poultry nonspecific cellular immunity.