Protective effect of acidic mannan fraction of bakers' yeast on experimental candidiasis in mice

The Diverse Roles of Monocytes in Cryptococcosis

Monocytes are considered to play a central role in the pathogenesis of Cryptococcus neoformans infection. Monocytes and monocyte-derived macrophages and dendritic cells are key components for the control of infection, but paradoxically they can also contribute to detrimental host responses and may even support fungal proliferation and dissemination. Simultaneously, the C. neoformans polysaccharide capsule can impair the functions of monocytes. Although monocytes are often seen as simple precursor cells, they also function as independent immune effector cells. In this review, we summarize these monocyte-specific functions during cryptococcal infection and the influence of C. neoformans on monocyte responses. We also cover the most recent findings on the functional and phenotypic heterogeneity of monocytes and discuss how new advanced technologies provide a platform to address outstanding questions in the field.

Fungal mediated innate immune memory, what have we learned?

The binary classification of mammalian immune memory is now obsolete. Innate immune cells carry memory characteristics. The overall capacity of innate immune cells to remember and alter their responses is referred as innate immune memory and the induction of a non-specific memory resulting in an enhanced immune status is termed "trained immunity". Historically, trained immunity was first described as triggered by the human fungal pathogen Candida albicans. Since, numerous studies have accumulated and deciphered the main characteristics of trained immunity mediated by fungi and fungal components. This review aims at presenting the newly described aspect of memory in innate immunity with an emphasis on the historically fungal mediated one, covering the known molecular mechanisms associated with training. In addition, the review uncovers the numerous non-specific effect that β-glucans trigger in the context of infectious diseases and septicaemia, inflammatory diseases and cancer.

Comparison of pathogenicity of various Candida albicans and C. stellatoidea strains

In order to clarify the pathogenicity and the pathogenic factors of various Candida species strains, three strains, NIH A-207 and J-1012 (serotype A), and NIH B-792 (serotype B) of Candida albicans and two strains, ATCC 20408 (karyotype II) and ATCC 36232 (karyotype I) of C. stellatoidea, a synonym for C. albicans, were tested for their lethality to mice, adherence to Hela cells, hydrophobicity, and cell growth under acidic conditions, pH 2.0-5.9. The pathogenicity for mice of all the strains was observed in the order NIH B-792, ATCC 36232, J-1012, NIH A-207, and ATCC 20408. The pathogenicity for mice by all the strains used was well correlated with adherence to the Hela cells, the hydrophobicity, and the cell growth under the acidic condition, pH 2.0. These results emphasize that these specific properties of the C. albicans and C. stellatoidea strains play an important role in the pathogenesis of candidosis.

Role of polymorphonuclear leukocytes in the resistance of tumor-bearing mice against Candida albicans infection

Tumor-bearing mice showed a significant resistance against Candida albicans intravenous infection. Longer survival was observed in groups of mice inoculated with fungal cells 2-3 weeks after tumor transplantation with allogeneic sarcoma 180, syngeneic methylcholanthrene-induced Meth A fibrosarcoma, and MM 46 mammary carcinoma than in non-tumor-bearing mice inoculated only with fungal cells. This effect was not observed when the mice were infected only 1 week after tumor transplantation. A significant decrease in the number of C. albicans cells in the kidneys was observed in mice inoculated with fungal cells 2-3 weeks after tumor transplantation. In the tumor-bearing mice treated with cyclophosphamide (CY), a remarkable decrease in both the number of peripheral blood polymorphonuclear leukocytes (PMNs) and the defense against challenge with C. albicans cells was observed, as compared with the CY-untreated groups (normal and tumor-bearing mice). A marked increase in the calcium concentration in serum and number, candidacidal activity, active oxygen level, and myeloperoxidase activity of PMNs was observed in the 2-3-week tumor-bearing mice. From these results, it is suggested that PMNs, which accumulated in the 2-3-week tumor-bearing mice, play an important role in the protection from C. albicans infection by increasing the number and the types of killing factors.

Comparative study of protective effects of chitin, chitosan, and N-acetyl chitohexaose against Pseudomonas aeruginosa and Listeria monocytogenes infections in mice

We conducted a comparative study of the protective effects of chitin, chitosan, and N-acetyl chitohexaose (NACOS-6) against mice infected intravenously or intraperitoneally with Pseudomonas aeruginosa and Listeria monocytogenes. Mice pretreated with chitin, chitosan, and NACOS-6 showed resistance to intraperitoneal infections by both microbes. Only mice pretreated with chitin and chitosan showed resistance to intravenous infections by both microbes. The number, active oxygen generation, and myeloperoxidase activity of peritoneal exudate cells (PEC) in the chitin, chitosan, and NACOS-6-treated mice were greater than those of the untreated mice. Also, these PEC factors from mice pretreated with chitin and chitosan were greater than those from the NACOS-6-treated mice.

Production of interleukin-1 activity of Kupffer cells from mice treated with the acidic mannan fraction of baker's yeast

We investigated the production of interleukin-1 (IL-1) activity by Kupffer cells (KC) from mice treated with a neutral mannan fraction (WNM) or an acidic mannan fraction (WAM025) from baker's yeast (Saccharomyces cerevisiae) in vivo and in vitro. The mice administered WAM025 showed an increase in the number of KC and the IL-1 production compared with mice administered WNM. In an in vitro stimulation assay using KC from a normal mouse, it was also found that WAM025 displayed an increase in IL-1 production. Diisopropyl fluorophosphate completely inhibited the production of IL-1 by KC from the mice administered WAM025.

Hemoglobin is utilized by Candida albicans in the hyphal form but not yeast form

Hyphal cells of Candida albicans bound to human hemoglobin, but not the yeast cells. The amount of hemoglobin receptor was significantly higher on the hyphal cells than on the yeast cells. Only the hyphal cells of C. albicans used hemoglobin as a source of iron. The hemolytic factor was detected in the culture supernatant of the hyphal cell of C. albicans.

Effect of N-acetylchitohexaose against Candida albicans infection of tumor-bearing mice

A water-soluble oligosaccharide, N-acetylchitohexaose (NACOS-6), was able to enhance the protective effect against Candida albicans infection in mice during the early phase of tumor-bearing. A significant decrease in the number of C. albicans cells in the kidneys of NACOS-6-treated tumor-bearing mice was observed 8 days after the fungal infection, or 15 days after the tumor transplantation. The candidacidal activity of polymorphonuclear leukocytes from NACOS-6-treated tumor-bearing mice did not differ from that of NACOS-6-untreated tumor-bearing mice. On the other hand, the candidacidal activities of both macrophages and T lymphocytes increased following administration of NACOS-6 in the early phase of tumor-bearing. The culture supernatant of T lymphocytes from NACOS-6-treated tumor-bearing mice also potentiated the candidacidal activity of casein-induced macrophages. An enhancement of natural killer cell activity of splenic lymphocytes obtained from NACOS-6-treated tumor-bearing mice was also observed.

Antimetastatic and growth-inhibitory effects of N-acetylchitohexaose in mice bearing Lewis lung carcinoma

N-Acetylchitohexaose, a water-soluble oligosaccharide was found to display a significant antimetastatic effect against Lewis lung carcinoma (LLC) transplanted into C57BL/6 mice, giving rise to a 40-50% inhibition ratio of pulmonary metastasis when administered intravenously (1 mg/kg) on day 6 after the tumor implantation (5 x 10(5) cells/mouse). It was also revealed that this hexaose had a significant growth-inhibitory effect against the local tumor of the same carcinoma (a 20-30% inhibition ratio), showing an enhancing effect on concomitant immunity in local tumor-resected mice. This oligosaccharide was also shown to enhance the tumoricidal effect of splenic T lymphocytes against LLC and P-815 mastocytoma cells and to increase the natural killer activity of splenic T lymphocytes, assayed with YAC-1 cells as the target.

In vitro activity of mannan sulfate, a novel sulfated polysaccharide, against human immunodeficiency virus type 1 and other enveloped viruses

Mannan sulfate, a novel sulfated polysaccharide, was prepared and investigated for its activity against human immunodeficiency virus type 1 (HIV-1) in vitro. Mannan sulfate completely inhibited HIV-1-induced cell destruction and viral antigen expression in HIV-1-infected Molt-4 (clone 8) cells at a concentration of 4 micrograms/ml. The 50% antiviral effective doses obtained with mannan sulfate in Molt-4 (clone 8) cells and in MT-4 cells were 1.5 and 9.3 micrograms/ml, respectively. No toxicity for Molt-4 (clone 8) cells or MT-4 cells was observed at a concentration of 4,000 and 2,500 micrograms/ml, respectively. Mannan sulfate was also inhibitory to other enveloped viruses, i.e. herpes simplex virus types 1 and 2, vaccinia virus and vesicular stomatitis virus. These results suggest that mannan sulfate may be useful for the chemotherapy of various viral infections, including those causing and associated with AIDS.

Candida cell wall mannan: a polysaccharide with diverse immunologic properties

It is clear that mannan has the potential to influence multiple biologic functions in vivo and in vitro, including both mannan-specific and mannan-nonspecific activities. Based on in vitro studies, various mechanisms have been proposed for the regulatory activities observed, ranging from interference with normal PMNL and monocyte function to the induction of T suppressor cells. It may well be, in fact, that different mechanisms function at different levels depending upon the specific phenomenon being influenced. Approaches to determining the mechanisms involved in these regulatory phenomena, however, have been complicated by the fact that many studies were performed with mannan extracted in the laboratory by traditional methods and used as such without further purification. Most laboratory-acquired mannans appear to be heterogeneous mixtures containing polymers of differing size and charge. When such mixtures have been separated on the basis of size or charge, it has been shown that biologic function can be correlated with individual fractions, and that a single bulk preparation of mannan can contain components with opposing biologic activities. Resolution of the specific mechanisms involved in the regulatory phenomena described, therefore, will not be complete until homogeneous preparations of mannan are employed to investigate the mechanisms.