SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Faria,A.M.C.; Ficker,S.M.; Speziali,E.; Menezes,J.S.; Stransky,B.; Verdolin,B.A.; Lahmann,W.M.; Rodrigues,V.S.; Vaz,N.M..

In the present review we address oral tolerance as an important biological phenomenon and discuss how it is affected by aging. Other factors such as frequency of feeding and previous digestion of the antigen also seem to influence the establishment of oral tolerance. We also analyze immunoglobulin isotypes of specific antibodies formed by tolerant and immunized animals of different ages submitted to different conditions of oral antigen administration. Isotypic patterns were studied as a parameter for assessing the pathways of B and T cell interactions leading to antibody production

Effects of strain and age on ear wound healing and regeneration in mice

Palavras-chave: Oral tolerance; Aging; Isotypes; Gut; Mucosa.

Ano: 1998

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000100005

Costa,R.A.; Ruiz-de-Souza,V.; Azevedo Jr.,G.M.; Vaz,N.M.; Carvalho,C.R..

Round holes in the ears of MRL mice tend to close with characteristics of regeneration believed to be absent in other mouse strains (e.g., C57BL/6). We evaluated the kinetics and the histopathology of ear wound closure in young (8 weeks old) C57BL/6 and BALB/c mice. We also used middle-aged (40 weeks old) C57BL/6 mice to evaluate the influence of aging on this process. A circular through-and-through hole was made in the ear, photographs were taken at different times after injury and wound area was measured with digital analysis software. The percentages of closed area measured on day 100 were: 23.57 ± 8.66% for young BALB/c mice, 56.47 ± 7.39% for young C57BL/6 mice, and 75.31 ± 23.65% for middle-aged C57BL/6 mice. Mice were sacrificed on days 1, 3, 5, 25,...

Ethanol-induced colitis prevents oral tolerance induction in mice

Palavras-chave: Wound healing; Regeneration; Scar; Aging; C57BL/6 mice; BALB/c mice.

Ano: 2009

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2009001200004

Andrade,M.C.; Vaz,N.M.; Faria,A.M.C..

The gut mucosa is a major site of contact with antigens from food and microbiota. Usually, these daily contacts with natural antigens do not result in inflammatory reactions; instead they result in a state of systemic hyporesponsiveness named oral tolerance. Inflammatory bowel diseases (IBD) are associated with the breakdown of the immunoregulatory mechanisms that maintain oral tolerance. Several animal models of IBD/colitis are available. In mice, these include targeted disruptions of the genes encoding cytokines, T cell subsets or signaling proteins. Colitis can also be induced by intrarectal administration of chemical substances such as 2,4,6-trinitrobenzene sulfonic acid in 50% ethanol. We report here a novel model of colitis induced by intrarectal...

Evolution and conservation of immunological activity

Palavras-chave: Ethanol; Colitis; Oral tolerance; Cytokines.

Ano: 2003

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003000900013

Vaz,N.M..

Paraphrasing what Gregory Bateson says on evolution, we might say that: "Immunology has long been badly taught. In particular, students - and even professional immunologists - acquire theories of immunological activity without any deep understanding of what problems these theories attempt to solve."

Immunoglobulin production is impaired in protein-deprived mice and can be restored by dietary protein supplementation

Palavras-chave: Theory; Immune system; Evolution; Conservation; Bateson; Maturana.

Ano: 2006

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2006001200002

Amaral,J.F.; Foschetti,D.A.; Assis,F.A.; Menezes,J.S.; Vaz,N.M.; Faria,A.M.C..

Most contacts with food protein and microbiota antigens occur at the level of the gut mucosa. In animal models where this natural stimulation is absent, such as germ-free and antigen-free mice, the gut-associated lymphoid tissue (GALT) and systemic immunological activities are underdeveloped. We have shown that food proteins play a critical role in the full development of the immune system. C57BL/6 mice weaned to a diet in which intact proteins are replaced by equivalent amounts of amino acids (Aa diet) have a poorly developed GALT as well as low levels of serum immunoglobulins (total Ig, IgG, and IgA, but not IgM). In the present study, we evaluated whether the introduction of a protein-containing diet in 10 adult Aa-fed C57BL/6 mice could restore their...

Indirect effects of oral tolerance to ovalbumin interfere with the immune responses triggered by Schistosoma mansoni eggs

Palavras-chave: Food proteins; Immunoglobulins; Maturation; Mucosa.

Ano: 2006

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2006001200009

Carvalho,C.R.; Lenzi,H.L.; Correa-Oliveira,R.; Vaz,N.M..

The objective of the present study was to investigate whether the injection of a tolerated protein (indirect effects) affects the formation of granulomas around Schistosoma mansoni eggs trapped in the lungs after intravenous (iv) injection into normal (noninfected) C57BL/6 mice (6 animals per group). To induce oral tolerance to chicken egg ovalbumin a 1/5 dilution of egg white in water was offered ad libitum in a drinking bottle for 3 days. Control mice received water. After 7 days, control and experimental animals were injected iv with 2,000 S. mansoni eggs through a tail vein. In some mice of both groups the iv injection of eggs was immediately followed by intraperitoneal (ip) immunization with 10 µg of dinitrophenylated conjugates of ovalbumin (DNP-Ova)...

Interruption of recently induced immune responses by oral administration of antigen

Palavras-chave: Oral tolerance; Ovalbumin; Granuloma; Schistosoma mansoni.

Ano: 2002

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2002001000012

Conde,A.A.; Stransky,B.; Faria,A.M.C.; Vaz,N.M..

Interest in oral tolerance has been renewed in the last few years as a possibility of intervention in human autoimmune diseases. An obstacle in this direction is that, although easily induced in animals virgin of contact with the antigen, oral tolerance becomes hard to induce in previously immunized animals. The present results show that there is an early period after primary immunization in which prolonged oral exposure to the antigen may arrest ongoing immune responses. Beyond this period, oral exposures to the antigen become ineffective and may actually boost immune responses. The end of the susceptible period coincides with the emergence of free specific antibodies in serum. However, the previous administration of purified anti-ovalbumin antibodies (40...

Oral tolerance induction with altered forms of ovalbumin

Palavras-chave: Suppression; Antibody response; Oral tolerance; Ovalbumin.

Ano: 1998

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000300008

Stransky,B.; Faria,A.M.C.; Vaz,N.M..

As a T cell-dependent phenomenon, oral tolerance is not expected to depend necessarily on native configuration of antigens. We investigated the induction of oral tolerance with modified ovalbumin (Ova). Oral administration of heat-denatured (HD-Ova) and cyanogen bromide-degraded ovalbumin was less effective than native Ova in inducing oral tolerance in B6D2F1 mice. HD-Ova was effective in suppressing delayed-type hypersensitivity (DTH) reactions but did not suppress specific antibody formation. Injection of Ova directly into the stomach, but not into the ileum or cecum, suppressed subsequent immunization to DTH reactions. Gavage with protease inhibitors (aprotinin or ovomucoid) before gavage with Ova was ineffective in blocking tolerance induction....

Stabilization of serum antibody responses triggered by initial mucosal contact with the antigen independently of oral tolerance induction

Palavras-chave: Antigen; Digestion; Oral tolerance; Mouse; Ovalbumin.

Ano: 1998

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000300009

Verdolin,B.A.; Ficker,S.M.; Faria,A.M.C.; Vaz,N.M.; Carvalho,C.R..

Initial contacts with a T-dependent antigen by mucosal routes may result in oral tolerance, defined as the inhibition of specific antibody formation after subsequent parenteral immunizations with the same antigen. We describe here an additional and permanent consequence of these initial contacts, namely, the blockade of secondary-type responsiveness to subsequent parenteral contacts with the antigen. When repeatedly boosted ip with small doses (3 µg) of ovalbumin (OVA) (or lysozyme), primed B6D2F1 mice showed progressively higher antibody responses. In contrast, mice primed after a single oral exposure to the antigen, although repeatedly boosted, maintained their secondary antibody titers on a level which was inversely proportional to the dose of antigen...

The conservative physiology of the immune system

Palavras-chave: Oral tolerance; Mucosal immunity; Stability; Memory.

Ano: 2001

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2001000200008

Vaz,N.M.; Faria,A.M.C. de; Verdolin,B.A.; Silva Neto,A.F.; Menezes,J.S.; Carvalho,C.R..

Current immunological opinion disdains the necessity to define global interconnections between lymphocytes and regards natural autoantibodies and autoreactive T cells as intrinsically pathogenic. Immunological theories address the recognition of foreignness by independent clones of lymphocytes, not the relations among lymphocytes or between lymphocytes and the organism. However, although extremely variable in cellular/molecular composition, the immune system preserves as invariant a set of essential relations among its components and constantly enacts contacts with the organism of which it is a component. These invariant relations are reflected, for example, in the life-long stability of profiles of reactivity of immunoglobulins formed by normal organisms...