beta-glucans in promoting health: Prevention against mutation and cancer

The polysaccharides beta-glucans occur as a principal component of the cellular walls. Some microorganisms, such as yeast and mushrooms, and also cereals such as oats and barley, are of economic interest because they contain large amounts of beta-glucans. These substances stimulate the immune system, modulating humoral and cellular immunity, and thereby have beneficial effect in fighting infections (bacterial, viral, fungal and parasitic). beta-Glucans also exhibit hypocholesterolemic and anticoagulant properties. Recently, they have been demonstrated to be anti-cytotoxic, antimutagenic and anti-tumorogenic, making them promising candidate as pharmacological promoters of health. (C) 2008 Elsevier B.V. All rights reserved.

Immunodominant Antigens of Leishmania chagasi Associated with Protection against Human Visceral Leishmaniasis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Autonomic control of cardiorespiratory interactions in fish, amphibians and reptiles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Natural antibodies in paracoccidioidomycosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Demonstration of antibody and cellular immune response to brain extract in West and Lennox-Gastaut syndromes

Investigamos a resposta imunológica celular e humoral frente a extrato salino de tecido cerebral em 9 pacientes com síndrome de Lennox-Gastaut, 15 pacientes com síndrome de West e 20 crianças normais. A técnica de imunodifusão dupla em gel de agar (Ouchterlony) evidenciou em todos os pacientes, altos níveis de um anticorpo precipitante contra o extrato salino de tecido cerebral. O teste de inibição de migração de leucócitos com o mesmo antígeno mostrou-se positivo na maioria dos pacientes. O possível papel destas respostas autoimmunes na patogenia das sindromes de West e Lennox-Gastaut é discutido.

Immunological disturbance in West and Lennox-Gastaut syndromes

Investigamos a imunidade humoral e celular em 18 pacientes com sindrome de West, 12 com sindrome de Lennox-Gastaut e 19 controles. Os exames realizados foram os seguintes: percentagem de linfócitos Ô e  no sangue periférico, niveis séricos de IgG, IgA e IgM, sensibilização cutânea com o DNCB, PHA intra dérmica, teste de inibição de migração de leucócitos e transformação blástica de linfócitos em presença de PHA. Detectamos deficiência de imunidade celular em 28 crianças, (18 com sindrome de West e 10 com sindrome de Lennox-Gastaut) e baixos níveis de imunoglobulinas em apenas 6. A depressão imunitária mostrou-se mais intensa nas crianças que apresentam sindrome de West.

Imunoglobulinas e C3 no granuloma paracoccidióidico

Utilizou-se o modelo experimental de paracoccidioidomicose, em camundongos, induzida pela inoculação endovenosa de suspensão de formas cerebriformes do P. brasiliensis (cepa Bt2; 1x10(6) formas viáveis/animal), para avaliar, após 2, 4, 8, 16 e 20 semanas: 1. A presença de imunoglobulinas e C3 nos granulomas pulmonares, por imunofluorescência direta; 2. A resposta imune humoral (imunodifusão) e celular (teste do coxim plantar), e 3. A histopatologia das lesões. Os camundongos apresentaram resposta imunocelular positiva desde a 2a. semana, com depressão transitória na 16a. semana, e anticorpos desde a 4a. semana, com pico na 16a. semana. Os granulomas pulmonares foram epitelióides, com numerosos fungos e microabscesses; a extensão das lesões foi progressiva até a 16a. semana, com regressão discreta na 20a. semana. Desde a 2a. semana, houve deposição de IgG e C3 na parede dos fungos no interior dos granulomas e a presença de células IgG positivas no halo linfomononuclear periférico; estes achados foram máximos entre a 4a. e 16a. semanas. Não se detectou depósito de IgG e C3 no interstício dos granulomas. IgG e C3 parecem exercer papel precoce e importante na defesa do hospedeiro contra o P. brasiliensis, contribuindo possivelmente para a destruição dos fungos e bloqueando a difusão de antígenos para fora dos granulomas.

Evaluation of different immunization protocols with P. brasiliensis antigens in Guinea pigs

O objetivo deste trabalho foi desenvolver protocolo eficiente e reprodutível de imunização em cobaias com antígenos de P. brasiliensis, visando a obtenção de modelo experimental para futuros estudos de mecanismos de proteção imunológica. Testaram-se três diferentes antígenos (particulado, solúvel e composto) e seis protocolos nos quais foram avaliadas as influências dos seguintes fatores: presença ou ausência de adjuvante completo de Freund, número de doses imunizantes e intervalo de tempo entre a última dose imunizante e o desafio. A eficiência do protocolo de imunização foi estudada pela avaliação da resposta imune celular e humoral anti-P. brasiliensis, utilizando teste cutâneo e teste de inibição da migração do macrófago, e imunodifusão, respectivamente. Observou-se que: 1. Três doses imunizantes de antígeno induziram melhor resposta do que duas doses; 2. Maior resposta imune foi conseguida com a utilização de adjuvante completo de Freund; 3. Animais desafiados depois de longo tempo (6 semanas) da última dose imunizante mostraram melhor resposta imune anti-P. brasiliensis; 4. Os antígenos solúvel e composto foram igualmente eficientes induzindo maior resposta imune humoral e celular anti-P. brasiliensis enquanto que o antígeno particulado provocou menor reatividade

Natural killer cell activity in experimental paracoccidioidomycosis of the Syrian hamster

Com o objetivo de avaliar a atividade de células natural killer na paracoccidioidomicose experimental do hamster, 80 hamsters foram infectados por via intratesticular com Paracoccidioides brasiliensis e sacrificados após 24h, 48h, 96h, 1, 2, 4, 8 e 11 semanas de infecção. Como controle foram avaliados 40 hamsters normais, não infectados. Os animais foram submetidos ao estudo da atividade citotóxica de células NK pela técnica de single-cell assay e da resposta imune humoral pelas técnicas de imunodifusão dupla e Elisa. A produção do fator inibidor da migração de macrófagos em presença de Phytohemaglutinina e antígeno de P. brasiliensis e a histopatologia das lesões foram estudadas após 1,4, 8e 11 semanas de infecção. Os animais infectados, quando comparados aos controles, apresentaram níveis de atividade NK significativamente elevados durante as 4 primeiras semanas de infecção, havendo diminuição dessa atividade a partir da 8ª semana. Foi observada correlação inversa entre atividade NK e níveis de anticorpos específicos e, associação entre diminuição da atividade NK, depressão de resposta imune celular e aumento da extensão das lesões histopatológicas. Os resultados sugerem que após ativação inicial, as células NK são incapazes de controlar a disseminação do fungo pelos tecidos. A depressão da atividade NK na fase tardia da infecção parece estar relacionada com os distúrbios imunorregulatórios associados à paracoccidioidomicose.

Effect of Bacillus of Calmette-Guérin, Avridine and Propionlbacterium acnes as immunomodulators on rabies in mice

Avaliou-se a resposta imune celular e humoral de camundongos inoculados com vírus rábico de rua e submetidos aos imunomoduladores Onco-BCG, avridina e Propionibacterium acnes. Os animais submetidos ao tratamento com P.acnes apresentaram um maior percentual de sobrevivência quando comparados aos dos demais tratamentos. Foram observados menores níveis de IFN-g nos animais infectados, sugerindo imunossupressão viral. O teste do Coxim Plantar não foi eficaz para a detecção da resposta de hipersensibilidade retardada na metodologia utilizada, contrariamente ao MIF. A sobrevivência dos animais não apresentou correlação com os níveis de anticorpos soroneutralizantes, concentração de IFN-g e resposta ao MIF.

EXPERIMENTAL PARACOCCIDIOIDOMYCOSIS OF HAMSTER INOCULATED IN THE CHEEK POUCH

We compared the granuloma morphology and immune response of hamsters inoculated with Paracoccidioides brasiliensis (Pb) into the cheek pouch, which lacks lymphatic drainage, and into the footpad, which is rich in lymphatics. Our objective was to better understand the modulation of Pb granuloma in an immunocompetent animal inoculated in an immunologically privileged site. The humoral immune response (ELISA) and cell mediated immunity (footpad test) became positive on days 7 and 14, respectively in animals inoculated into footpad and on days 35 and 60 in animals inoculated into the pouch. Typical epithelioid granulomas were observed at both sites on day 14. The number of fungi gradually decreased from the beginning of the experiment in footpad lesions, but only after day 35 in pouch granulomas, when cell mediated immunity was detectable. The results indicate that typical epithelioid paracoccidioidomycotic granulomas may develop in the absence of a detectable immune response; however, they are incapable of controlling fungal reproduction. Lack of lymphatic drainage delays the appearance of a detectable immune response, but with time fungi escape from the pouch, elicit an immune response and reach other organs. Our results further indicate the importance of the lymphatics in the pathogenesis of paracoccidioidomycosis.

PATHOGENICITY AND IMMUNOGENICITY OF PARACOCCIDIOIDES-BRASILIENSIS ISOLATES IN THE HUMAN-DISEASE AND IN AN EXPERIMENTAL MURINE MODEL

The pathogenicity and immunogenicity of six recently isolated Paracoccidioides brasiliensis samples derived from patients presenting distinct and well defined clinical forms of paracoccidioidomycosis (PCM) were compared as to their virulence, tropism to different organs and ability to induce specific cellular and humoral immune response in susceptible (B10.A) inbred mice. Isolates Pb44 and Pb47 were obtained from acute cases, Pb50 from a chronic severe form, Pb45 from a chronic moderate case and both Pb56 and Pb57 from chronic mild forms of PCM. Pathogenicity and tropism of each fungal sample were evaluated by LD50% estimation, examination of gross lesions on various organs at 2, 4, 12 and 16 weeks post-infection, and by colony-forming unit (CFU) counts in the lungs at week 16 post-infection of mice. Fungal tropism in human PCM and in B10.A mice was always dissociated. A well defined relationship between virulence of the fungal sample and the clinical findings of the correspondent patient was not evident, although a tendency to higher LD50% and less intense paracoccidioidic lesions was observed in mice infected with Pb56 and Pb57. The specific DTH response patterns varied according to the infectant sample, but positive DTH reactions at the beginning of the infection and a tendency to anergy or low DTH responses at week 12 and/or week 16 post-infection were always observed. A correspondence between the DTH response in humans and in mice was noticeable only when the isolates from the most benign cases (Pb56 and Pb57) were considered. The specific antibody patterns in mice and in the correspondent patients were also not analogous. Collectively, these results indicate that an association between the fungal pathogenicity and immunogenicity in the human disease and in susceptible mice was discernible only when isolates obtained from very mild cases (Pb56 and Pb57) were considered.

The immune system of insects and the control of some parasitary human diseases

Parasitic diseases in humans, transmitted by insects, affect about 500 million people living mainly in countries of low economic power, the control of these diseases is difficult to carry out, mainly die to social and political problems, enhanced bg the capacity of these organisms to develop resistance to insecticides used to for their destruction.Some recent advances in the area of insect immunology have open the possibility for abetter epidemiological control of these diseases.The immune system of these insects, as well as that of other organisms, have the ability to recognize the infecting parasites and liberate a series of reactions which stop the infection. These reactions involve the circulating cells (hemocytes) against the parasite. These cells have the ability of phagocytize and liberate the production of various humoral factors, neutralizing the infection.Some promising results, obtained by the study of the immune system of malaria-transmitting insects, the sleeping disease, and dengue, are an example of this new sanitary strategy.

Study of pulmonary experimental paracoccidioidomycosis by analysis of bronchoalveolar lavage cells: Resistant vs. susceptible mice

Adult Swiss (susceptible) and BALB/c (non-susceptible) mice were inoculated by the intravenous route with 1 x 10(6) yeast cells of Paracoccidioides brasiliensis, strain 18. Immunologic parameters, histopathology and features of the bronchoalveolar lavage (BAL) were evaluated at week 2, 4, 8 and 16 post-infection. The pulmonary infection was progressive in Swiss mice and regressive in BALB/c mice. The numbers of total cells, lymphocytes and polymorphonuclear neutrophils increased in BAL, as well as the percentages of giant cells, and CD4 and CD8 positive cells. The ultrastructural study of BAL cells revealed a predominance of macrophages and a frequency of 13.2% of type II pneumocytes. As the infection progressed, the number of fungal cells and spreading macrophages, as well as the stimulated release of H2O2 by macrophages, increased. The animals exhibited an exacerbation of the humoral immune response and a depression of cellular immunity during the infection. There was a good correlation between the intensity and the pattern of the pulmonary histopathology and the cellular findings in the BAL. The present model reproduces some anatomoclinical patterns of the human disease and shows that BAL may be a useful tool in monitoring the pulmonary infection caused by P. brasiliensis.

DETECTION OF CELLULAR-IMMUNITY WITH THE SOLUBLE-ANTIGEN OF THE FUNGUS SPOROTHRIX-SCHENCKII IN THE SYSTEMIC FORM OF THE DISEASE

Sporothrix schenckii is the etiologic agent of sporotrichosis, a mycosis of world-wide distribution more commonly occurring in tropical regions. The immunological mechanisms involved in the prevention and control of sporotrichosis are not fully understood but apparently include both the humoral and cellular responses. In the present investigation, cellular immunity was evaluated by in vivo and in vitro tests in mice infected with yeast-like forms of S. schenckii. The disease developed systemically and cellular immunity was evaluated for a period of 10 weeks. The soluble antigen utilized in the tests was prepared from yeast form of the fungus through the sonication (20 min: 10 sonications at 50 W at 2-min intervals). Delayed hypersensitivity and lymphocyte transformation tests showed that the cellular immune response was depressed between the 4th and 6th week of infection when the animals were challenged with the soluble fungal antigen. This depression frequently indicates worsening of the disease, with greater involvement of the host. This is a promising field of research for a better understanding of the pathogeny of this mycosis.