Sylvia Maria Nicolau Campos

The serum D-xylose test as a useful tool to identify malabsorption in rats with antigen specific gut inflammatory reaction

The inappropriate immune response to foods, such as peanut, wheat and milk may be the basis in the pathogenesis of enteropathies like coeliac and Crohn disease, which present small intestinal malabsorption. A number of recent studies have utilized d‐xylose absorption as an investigative tool to study small intestinal function in a variety of clinical settings. Thus, the aim of this experimental study was to evaluate the intestinal absorption of d‐xylose in an antigen‐specific gut inflammatory reaction rat model. Animals of the experimental group were inoculated with peanut protein extract before their exposure to a challenge diet containing exclusively peanut seeds to induce the gut inflammatory reaction caused by peanut allergy. Our results show that systemic inoculation with peanut protein extract renders significantly higher antibody titres (5.085 ± 0.126 units) (P < 0.0001) than control rats (0.905 ± 0.053 units) and that the antibody titres correlate positively to an inflammatory alteration of the gut morphology (P < 0.0001). Animals pertaining to the experimental group showed an intestinal absorption of d‐xylose lower than control rats (P < 0.0001). We also observed that d‐xylose absorption correlates negatively with IgG titres and positively with morphometric parameters (Pearson correlation). In conclusion, the use of serum d‐xylose test was useful to identify the presence of small intestinal malabsorption in our antigen specific gut inflammatory reaction rat model.

Diet selection in immunologically manipulated mice

Diet selection is a complex problem that animals in wildlife have to deal with daily. In their natural environment, these animals meet a great variety of foods some of which they are able and prepared to eat, yet, not all of it is eaten. In addition to the biological factors, some of which we shall discuss deeper in this paper, an important factor in food preference is social contact. Alterations in the physiology of mammals can have profound effects on the choice or preference for certain foods. On the other hand the decline of taste and smell perception in the elderly, the degree of food restriction, the sensorial properties of foods (such as presentation, taste, and smell) can be considered factors that influence feeding behavior leading to aversion. Many species, including man, learn to associate nausea with taste, and as a consequence avoid its specific intake, which has been shown to be persistent. Conditioned taste aversion is a form of associative learning in which animals display an aversion to the taste of a food that has previously been paired with illness. Our group has investigated the pattern of ingestion of foods that are frequently eaten by mice in wildlife and are potentially allergenic to humans in order to study the immunological consequences to these foods such as oral tolerance and inflammatory processes of the gut. We have chosen two seeds, peanuts (Arachis hypogea) and cashew nuts (Anacardium occidentale), as our source of antigens as the first is considered to be one of the most potent food allergens and for the second there seems to be very little allergy in the human setting. We used male and female, normal, adult CBA/J, A/J, C57BL/6 and Balb/c mice 2-3 months old and hybrid (C57Bl/6xBalb/c) F1, (Balb/cxC57Bl/6) F1), (C57Bl/6xDBA2) F1 mice. Food preference appeared to be strain-specific. Animals tolerized to a determined seed, then immunized with its protein extract and re-exposed to the seed in natura alter their feeding pattern. We suggest that diet selection, a multi-factorial event, is influenced by genetic factors such as the MHC and the immunological status of the animal.

Evaluation of the acute toxicity of dolabelladienotriol, a potential antiviral from the brown alga Dictyota pfaffii, in BALB/c mice

Dolabelladienotriol is a product extracted from the brown marine alga Dictyota pfaffii from Brazil that has been shown to have antiviral activity and low cytotoxicity. Our studies have evaluated the acute toxicity of dolabelladienotriol in BALB/c mice for ten days after administration of a single dose. Among the parameters considered were behavior, weight, biochemical and histological analyses of blood samples taken at three different times (Bs.0, Bs.1 and Bs.2) and optical microscopic examination of organs like liver, kidney, stomach and small intestine. Mice deaths were not observed at any dose during the ten day period. There were some changes in the biochemical analysis results for urea nitrogen (BUN) and alanine aminotransferase (ALT), but the changes were not significantly different from the reference levels of the animals before administration of the substance. Histological analyses of tissues were very similar for all animals. The alterations in liver and kidney tissues did not affect the animals´ behavior at any concentration, not even at 50 mg/kg, where the most significant changes in tissues were seen. This study indicates that dolabelladienotriol has low toxicity in administered dose range.

Food allergy/hypersensitivity: antigenicity or timing?

Mechanisms involved in the induction of oral tolerance (OT) or systemic immunization through the oral rout are still poorly understood. In our previous studies, we have shown that when normal mice eat peanuts they become tolerant, with no gut alterations. Conversely, if immunized with peanut proteins prior to a challenge diet (CD) containing peanuts they develop chronic inflammation of the gut. Our aim is to evaluate the consequences of the introduction of a novel protein in the diet of animals presenting antigen-specific gut inflammation. Adult, female C57BL/6J mice were divided in control (C) and experimental (E) groups. C1-C3 received peanut protein immunization, animals of the control groups C4 were sham immunized, and control group C5 received ovalbumin (OVA) immunization. The experimental group was immunized with peanut protein extract. Before initial exposure to a 30-day peanut containing CD, the experimental group was divided into 5 groups (E1-E5). OVA feeding began 7 days prior CD (E1) on day 0 (E2), 7 (E3), 14 (E4) and 21 (E5) during CD. Our results show that oral exposure to a novel protein (OVA) in the absence of gut inflammation (E1) leads to low levels of systemic antibody (Ab) titers, comparable to tolerant animals. Conversely, as off initial induction of inflammation, groups submitted to OVA (OT) protocol develop increasingly higher systemic Ab titers similar to animals of the immune control group. In conclusion, our protocol indicates that timing is more important than the antigenicity when a novel protein is offered, in the diet.

Induction of an antigen specific gut inflammatory reaction in mice and rats: a model for human Inflammatory Bowel Disease

A alergia alimentar consiste em uma reacao adversa que ocorre em pessoas susceptiveis quando ingerem alimentos sensibilizantes, sendo uma das causas das Doencas Inflamatorias Intestinais (IBD). O objetivo deste estudo foi desenvolver um protocolo experimental de inducao de um processo inflamatorio intestinal antigeno-especifico em camundongos e ratos. Foi escolhida para a inducao deste processo a semente de amendoim. Os animais foram imunizados com o extrato proteico previamente a exposicao com a semente in natura. Nossos resultados mostram que a imunizacao sistemica com extratos proteicos de amendoim ocasiona titulos significativamente maiores de anticorpos quando comparado ao grupo controle e que os animais imunizados submetidos ao desafio com a dieta contendo exclusivamente amendoim apresentam alteracoes intestinais tempo-dependente similares aquelas observadas na doenca celiaca. Os resultados obtidos sugerem que este modelo experimental constitui uma ferramenta conveniente para avaliar as alteracoes no processo inflamatorio intestinal cronico antigeno-especifico

Maternal immunomodulation of the offspring's immunological system

The mothers and the offsprings immunological system are closely related thus one can influence the other. This hypothesis drove our aim to study the impact of the mothers immunological status over the immunological response of their offspring. For this, female mice tolerant or allergic to peanuts were exposed or not to a challenge diet containing peanuts during the gestation-lactation period (TEP/AEP; TNEP/ANEP, respectively). After weaning the offspring was submitted to the peanut allergy or peanut tolerization protocol and then challenged with a peanut diet. Our results showed that when the offspring is submitted to the allergy induction protocol, they behave differently depending on their mothers immunological status. Offspring born to TEP mothers produced the lowest antibody titters while those born to AEP mothers produced the highest antibody titters compared to mice born to TNEP and ANEP. On the other hand when the offspring was submitted to the tolerization protocol all groups presented low antibody titers with no significant difference between groups, independent of the mothers immunological status and/or contact with peanuts during the gestation-lactation period. The analysis of the histological profile of the offspring correlates well to the serological response. In other words, offspring born to TEP mothers and submitted to the allergy induction protocol presented a normal histological profile, while the offspring born to AEP mothers produced the worst gut inflammation. These results indicate that mothers, exposed to the antigen (by the oral route) during gestation, actively influence the immune response of their offspring. This work sheds some light on the importance of the immunomodulation induced by dietary antigens during gestation and their influence on the immunological response of their offspring. However, more work is needed to elucidate the molecular and cellular components of this regulatory phenomenon.

Comparison between digital and optical microscopy: Analysis in a mouse gut inflammation model

Virtual microscopy is currently widely used for various purposes, such as teaching, archiving, collaborations and research. Although the cost of this technique has reduced, it continues to be expensive for the majority of laboratories in developing countries. The Graduate Program in Pathology at the Federal Fluminense University (Niterói, Brazil) has acquired equipment for virtual microscopy. However, this novel method faced prejudice, as students and technicians were skeptical about its reliability. Thus, the aim of the current study was to evaluate whether virtual microscopy is a reliable method of analysis for our research. Thus, a mouse gut inflammation model developed by our research group was used in the present study. Analysis was performed using optical microscopy and digital imaging using the APERIO scanning system and the ImageScope® software. Intestinal epithelial cells (IECs), intra epithelial leucocytes (IEL), and villi number and area were evaluated. No significant differences were observed in villi number, IEC and IEL; however, the villi area was significantly smaller when measured using the computer. Thus, the present study indicates that virtual microscopy is a trustworthy method for research purposes.

Enlarged colitogenic T cell population paradoxically supports colitis prevention through the B-lymphocyte-dependent peripheral generation of CD4 + Foxp3 + Treg cells

Intestinal inflammation can be induced by the reconstitution of T/B cell-deficient mice with low numbers of CD4+ T lymphocytes depleted of CD25+Foxp3+ regulatory T cells (Treg). Using RAG-knockout mice as recipients of either splenocytes exclusively depleted of CD25+ cells or FACS-purified CD4+CD25−Foxp3− T cells, we found that the augmentation of potentially colitogenic naïve T cell numbers in the inoculum was unexpectedly beneficial for the suppression of colon disease and maintenance of immune homeostasis. Protection against T cell-mediated colitis correlated with a significant increment in the frequency of peripherally-induced CD4+CD25+Foxp3+ T (pTreg) cells, especially in the mesenteric lymph nodes, an effect that required the presence of B cells and CD4+CD25−Foxp3+ cells in physiological proportions. Our findings support a model whereby the interplay between B lymphocytes and a diversified naïve T cell repertoire is critical for the generation of CD4+CD25+Foxp3+ pTreg cells and colitis suppression.

Avaliação da interferência da tolerância oral na rejeição do transplante de coração alogênico avascular na orelha de camundongo

OBJECTIVE: Although the development of surgical techniques and the discovery of immune-suppressors permitted heart transplantation to be accepted as a widespread treatment for terminally ill patients, rejection, complications due to these drugs and the chronic vasculopathies continue to be majority problems. The search for alternatives to supplant these impediments by performing avascular allogeneic heart transplants from newborn BALB/C mice (24h old) to the subcutaneous tissue of the ears of adult male C57BI/6J and C3H/HEJ mice to evaluate the interference of systemic oral tolerance on the rejection mechanisms are our main goal. METHOD: Adult, male C57BI/6 e C3H/HEJ were divided in two groups. The tolerant group received peanuts ad libitum for one week in the diet while the immune group continued to eat mouse chow. Both groups were immunized sc with 100mg of peanut extract. The transplanted newborn BALB/C hearts were deposited of into the subcutaneous tissue of the ears of tolerant and immune mice in the presence or not of concomitant immunization to peanut protein. RESULTS: We demonstrated that feeding proteins induces systemic tolerance since animals of both strains that ate the seeds before being immunized had lower systemic antibodies than immune animals. Tolerant C3H/HEJ mice with concomitant administration of the tolerogenic antigen presented a more preserved transplanted heart than all other groups. CONCLUSION: Although not homegeneously, the immunoregulatory mecanisms of oral tolerance modified the rejection process of alogenic avascular heart transplant to the ear of adult mice. As these mecanisms are not yet well understood more work needs to be done in this field.

A histomorphometric classification system for normal and inflamed mouse duodenum-Quali-quantitative approach

Gut‐associated intestinal lymphoid tissue, the largest secondary lymphoid organ in the human body, constantly samples antigens from the gut lumen, presenting as a default response the activation of TCD4+FOXP3+ regulatory T cells that secrete a profile of anti‐inflammatory cytokines maintaining gut homeostasis denominated from an immunological perspective as mucosal tolerance. However, when antigens are sampled in an inflammatory setting, the immune response may either be protective, in the case of harmful pathogens, or cause further inflammatory reactions as in food allergy, inflammatory bowel diseases, coeliac disease or food protein‐induced enterocolitis syndrome. Therefore, there is a need for accurate and consistent experimental models. However, a drawback in comparing these models is the lack of a classification system similar to that which is already used for humans. Thus, the aim of this work was to propose a classification system of the small intestinal histomorphology in experimental mice. To do this we used a mouse antigen‐specific gut inflammation model developed by our research group. Duodenum sections stained with haematoxylin‐eosin and Alcian blue were scanned using the APERIO scanning system and analysed with the ImageScope® software. The evaluated parameters were villus area, villus height and width, enterocyte count, mononuclear intra‐epithelial leucocyte and goblet cell counts, and architectural and cellular ratios. Food‐sensitized animals challenged with a diet containing the corresponding food allergen presented, as for humans, time‐dependent shortened and widened villi accompanied by leucocyte infiltrate and loss of goblet cells. With these data, we were able to establish a classification system for experimental intestinal inflammation in mice thus permitting better comparisons among and between experiments than has been possible previously.