Immunomodulatory action of jacalin from Artocarpus integrifolia and mannoprotein from Saccharomyces uvarum on the humoral immunity of laying hens / Avaliação da ação imunomoduladora do Jacalin de Artocarpus integrifolia e mannoprotein de Saccharomyces uvarum na imunidade humoral das galinhas poedeiras

ABSTRACT: Advances in the fields of glycobiology and immunology have provided many insights into the role of carbohydrate-protein interactions in the immune system. Jacalin of Artocarpus integrifolia (JCA) and structural mannoprotein of Saccharomyces uvarum (MPS) are molecules with immunomodulatory properties. JCA is an IgA human lectin binding molecule that causes the mitogenic stimulation of immune cells, production of cytokines, chemotaxis, and activation of leukocytes. Studies on the immunomodulatory properties of JCA and MPS in mammals and fish suggest that they have an action on antibody production. The aim of this study was to investigate the possible action of JCA and MPS on the production of specific antibodies in laying hens. For this, laying hens were inoculated with an intra abdominal injection of sheep red blood cells (SRBC) with either JCA (0.075 µg, 0.75 µg, and 7.5 µg) or MPS (20 µg and 100 µg). Levels of anti-SRBC antibodies of the IgY, IgM, and IgA classes were evaluated by ELISA. Results showed that JCA and MPS have immunomodulatory effects on levels of anti-SRBC IgM, IgA, and IgY. An immunostimulatory effect of JCA was observed in primary immune response on anti-SRBC IgY, while an inhibitory effect of JCA and MPS was observed in secondary immune response on the production of IgM and IgA anti-SRBC. These results suggested that MPS and JCA have immunomodulatory effects on antibody production and could be used in future studies on humoral immune response in poultry.

RESUMO: Avanços nos campos glicobiologia e imunologia forneceram muitas informações sobre o papel das interações da proteína-carboidrato na modulação do sistema imunológico. A jacalina extraída de Artocarpus integrifolia (JCA) e a manoproteína da parede celular de Saccharomyces uvarum (MPS) são moléculas com propriedades imunomoduladoras. JCA é uma lectina com afinidade pela IgA humana e tem ação mitogênica sobre células do sistema imunológico estimulando a produção de citocinas, a quimiotaxia e a ativação de leucócitos. Estudos sobre as propriedades imunomoduladoras de JCA e MPS em mamíferos e peixes sugerem que essas moléculas podem ter um efeito sobre a produção de anticorpos. O objetivo deste estudo foi investigar a ação da JCA e MPS sobre a produção de anticorpos específicos em galinhas poedeiras. Para isso, galinhas poedeiras foram inoculadas por via intra-abdominal com eritrócitos de carneiro (SRBC) em associação com o JCA (0,075 µg, 0,75 µg, e 7,5 µg) ou MPS (20 µg e 100 µg). Os níveis de anticorpos anti-SRBC das classes IgY, IgM, e IgA foram avaliados por ELISA. Os resultados mostraram que a JCA e a MPS têm um efeito imunomodulador sobre a produção IgY, IgM, ou IgA anti-SRBC. Um efeito imunoestimulador da JCA foi observado sobre a produção de anticorpos IgY na resposta imune primária, enquanto um efeito imuno inibitório da JCA e da MPS sobre a produção de IgM e IgA anti-SRBC na resposta imune secundária. Estes resultados sugerem que o MPS e JCA tem efeito modulador sobre a produção de anticorpos e podem ser utilizados em estudos futuros sobre a imunidade humoral em aves comerciais.

Concanavalin A enhances phagocytosis and killing of Candida albicans by mice peritoneal neutrophils and macrophages.

In this study we tested the hypothesis that after administration of a single intraperitoneal dose of concanavalin A (Con-A) to mice, the proportion of neutrophils and macrophages in the peritoneal exudate and their phagocytic and candidacidal activities should change with time. The number of neutrophils in the peritoneal exudate was greatly increased 6 h after administration of Con-A, and those cells were able to kill both intracellular and extracellular yeast and germ tube forms of Candida albicans. Addition of catalase to the culture medium reduced the killing of C. albicans, suggesting that the candidacidal activity depended on the myeloperoxidase system. The survival of mice pretreated with Con-A and submitted to an inoculum of C. albicans 6 h afterwards was twice higher than that of controls, which suggests that neutrophils were able to clear the experimental infection. One day after the treatment, the population of neutrophils in the exudate was about 45%, but after 2 days it was reduced to only 5% and the candidacidal activity was also reduced. After 4 days the exudate contained over 95% of macrophages, the candidacidal activity reached a maximum, and the phagocytosis mediated by both complement receptors and mannose receptors was increased. Uptake of FITC-mannose-BSA by macrophages was maximal on about the 4th day and was inhibited by mannan, suggesting that treatment with Con-A increased the activity of mannose receptors. These results support the hypothesis that activation of cellular immunity by Con-A occurred in two phases, one dominated by neutrophils, and the other by macrophages expressing increased activity of mannose receptors.

Artin M enhances TNF-α production and phagocytosis of Candida albicans mediated by dectin-1 and mannose receptors.

The activities of dectin-1 and mannose receptors on phagocytosis of Candida albicans and the production of TNF-α by macrophages from mice pretreated for 3 days with extract of Artocarpus intergrifolia seeds (jack extract), Artin M or jacalin were studied. Macrophages from these mice were coincubated with C. albicans CR15 (yeast), in the presence of mannose (50mM) plus mannan (100 µg) or laminarin (1mg). Phagocytosis was significantly enhanced to 52% in macrophages from mice pretreated intraperitoneally for 3 days with jack extract (500 µg/250 µl PBS). Reduction in phagocytosis from 52% to 34% (P<0.05) occurred in the presence of mannose receptor inhibitors and from 52% to 16% (P<0.01) in the presence of dectin-1 inhibitor laminarin, whereas only 20% of control macrophages phagocytosed blastoconidia. Similar results were verified for pretreatment of mice with Artin M (2.5 µg/250 µl PBS), but not for jacalin (25 µg/250 µl PBS). Macrophages from mice pretreated 3 days previously with jack extract or Artin M and then coincubated for 2h with C. albicans presented a significant increase in TNF-α production, correlating with significantly less transition of yeast to filamentous forms compared to pretreatment with jacalin. These results suggest that Artin M, but not jacalin present in jack extract significantly increased TNF-α production and the activity of mannose and dectin-1 receptors.

Protective effect of Artin M from extract of Artocarpus integrifolia seeds by Th1 and Th17 immune response on the course of infection by Candida albicans.

The immunoregulatory effect of Artin M and jacalin from extract of Artocarpus integrifolia seeds (jack extract) against infection with Candida albicans was investigated. Swiss mice received jack extract containing 500 µg protein/ml PBS intraperitoneally (i.p.) or PBS alone and after 72 h were infected i.p. with C. albicans CR15 (10(7)) and sacrificed after 30 min, 2, 6, 24, and 72 h. ELISA analysis revealed that in jack extract-treated mice IFN-γ was predominantly produced versus IL-10 in control mice. These results suggest that jack extract induced a protective immune response, since C. albicans clearance was complete at 72 h postinfection. Jack extract presents two lectins (Artin M and jacalin) with distinct biological properties. Artin M was able to induce IL-12 production by macrophages. Also, Artin M in different concentrations, associated with jacalin or in jack extract induced both IFN-γ and IL-17 production. As a consequence, phagocytic and candidacidal activity increased significantly. Alanine aminotransferase activity (ALT) was used as parameter for damage of the liver. The activity of ALT correlated with inoculum size that increased significantly in control group, however, mice pretreated with jack extract 3 days before infection presented normal ALT. Mice pretreated with jack extract that received a lethal inoculum of Candida presented 90% survival versus 20% among controls or mice pretreated with jacalin. Thus, the results suggest that Artin M by itself, associated with jacalin or present in jack extract is able to induce protective Th1 and Th17 immune responses against Candida albicans infection.

Increased tumour necrosis factor-alpha production, higher mannose receptor activity and ability to kill Candida by concanavalin-A-activated macrophages.

In a previous study, our group verified that mice pretreated with concanavalin-A (Con-A) produced more tumour necrosis factor (TNF)-alpha and presented greater Candida clearance from the peritoneal cavity, liver and spleen, which yielded a higher survival rate than control animals. In this work, the hypothesis that macrophages were of crucial importance in overcoming the infection was tested. Thus, peritoneal macrophages from mice pretreated for 3 days with Con-A or phosphate-buffered saline (PBS) were coincubated with CR1, CR15 and 577 isolates of Candida albicans for 0.5, 1 and 2 h. The ability of Con-activated macrophages to produce TNF-alpha, ingest via mannose receptors and kill all the isolates was significantly greater compared with PBS-treated macrophages, and activated macrophages exhibited a lower incidence of apoptosis, verified by binding to annexin V-fluorescein isothiocyanate. The transition of yeast cells to filamentous forms during coincubation for 2 h with control macrophages was about 73-80%, whereas in the presence of Con-A-activated macrophages, it was 35-40%. Our results suggest that a greater clearance of C. albicans infection through treatment with Con-A is probably due to the activation of macrophages, which produce more TNF-alpha, express more mannose receptors and are better endowed to kill ingested C. albicans.

Polysaccharide-rich fraction of Agaricus brasiliensis enhances the candidacidal activity of murine macrophages.

A polysaccharide-rich fraction (ATF) of medicinal mushroom Agaricus brasiliensis was evaluated on the candidacidal activity, H2O2 and nitric oxide (NO) production, and expression of mannose receptors by murine peritoneal macrophages. Mice received three intraperitoneal (i.p.) injections of ATF and after 48 h their peritoneal resident macrophages were assayed against Candida albicans yeast forms. The treatment increased fungicidal activity and it was associated with higher levels of H2O2, whereas NO production was not affected. We also found that the treatment enhances mannose receptor expression by peritoneal macrophages, which are involved in the attachment and phagocytosis of non-opsonized microorganisms. Treatment of animals with ATF was able to enhance the clearance of C. albicans during the first 6 h after the experimental i.p. infection. Our results suggest that this extract can increase host resistance against some infectious agents through the stimulation of microbicidal activity of macrophages.

Polysaccharide-rich fraction of Agaricus brasiliensis enhances the candidacidal activity of murine macrophages

A polysaccharide-rich fraction (ATF) of medicinal mushroom Agaricus brasiliensis was evaluated on the candidacidal activity, H2O2 and nitric oxide (NO) production, and expression of mannose receptors by murine peritoneal macrophages. Mice received three intraperitoneal (i.p.) injections of ATF and after 48 h their peritoneal resident macrophages were assayed against Candida albicans yeast forms. The treatment increased fungicidal activity and it was associated with higher levels of H2O2, whereas NO production was not affected. We also found that the treatment enhances mannose receptor expression by peritoneal macrophages, which are involved in the attachment and phagocytosis of non-opsonized microorganisms. Treatment of animals with ATF was able to enhance the clearance of C. albicans during the first 6 h after the experimental i.p. infection. Our results suggest that this extract can increase host resistance against some infectious agents through the stimulation of microbicidal activity of macrophages.