High levels of circulating triiodothyronine induce plasma cell differentiation.

The effects of hyperthyroidism on B-cell physiology are still poorly known. In this study, we evaluated the influence of high-circulating levels of 3,5,3'-triiodothyronine (T3) on bone marrow, blood, and spleen B-cell subsets, more specifically on B-cell differentiation into plasma cells, in C57BL/6 mice receiving daily injections of T3 for 14 days. As analyzed by flow cytometry, T3-treated mice exhibited increased frequencies of pre-B and immature B-cells and decreased percentages of mature B-cells in the bone marrow, accompanied by an increased frequency of blood B-cells, splenic newly formed B-cells, and total CD19(+)B-cells. T3 administration also promoted an increase in the size and cellularity of the spleen as well as in the white pulp areas of the organ, as evidenced by histological analyses. In addition, a decreased frequency of splenic B220(+) cells correlating with an increased percentage of CD138(+) plasma cells was observed in the spleen and bone marrow of T3-treated mice. Using enzyme-linked immunospot assay, an increased number of splenic immunoglobulin-secreting B-cells from T3-treated mice was detected ex vivo. Similar results were observed in mice immunized with hen egg lysozyme and aluminum adjuvant alone or together with treatment with T3. In conclusion, we provide evidence that high-circulating levels of T3 stimulate plasma cytogenesis favoring an increase in plasma cells in the bone marrow, a long-lived plasma cell survival niche. These findings indicate that a stimulatory effect on plasma cell differentiation could occur in untreated patients with Graves' disease.

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

Food allergy is an adverse reaction that occurs in susceptible people when they eat sensitizing foods and is one of the causes of Inflammatory Bowel Disease (IBD). The effort to understand the induction process of these diseases is important as IBD is increasing worldwide, including in Brazil. The aim of this study was to develop an experimental antigen specific inflammatory process of the gut of mice and rats, using peanut seeds. Animals were immunized with peanut protein extract before their exposure to the in natura peanut seeds. Results showed that systemic immunization with peanut protein extracts rendered significantly higher antibody titers than control groups and that immunized animals submitted to a challenge diet containing peanuts presented time dependent alterations of the gut similar to celiac disease. In conclusion, results suggested that this experimental model was a convenient tool to study the evolution of alterations in chronic antigen specific gut inflammatory process.

A alergia alimentar consiste em uma reação adversa que ocorre em pessoas susceptíveis quando ingerem alimentos sensibilizantes, sendo uma das causas das Doenças Inflamatórias Intestinais (IBD). O objetivo deste estudo foi desenvolver um protocolo experimental de indução de um processo inflamatório intestinal antígeno-específico em camundongos e ratos. Foi escolhida para a indução deste processo a semente de amendoim. Os animais foram imunizados com o extrato protéico previamente à exposição com a semente in natura. Nossos resultados mostram que a imunização sistêmica com extratos protéicos de amendoim ocasiona títulos significativamente maiores de anticorpos quando comparado ao grupo controle e que os animais imunizados submetidos ao desafio com a dieta contendo exclusivamente amendoim apresentam alterações intestinais tempo-dependente similares àquelas observadas na doença celíaca. Os resultados obtidos sugerem que este modelo experimental constitui uma ferramenta conveniente para avaliar as alterações no processo inflamatório intestinal crônico antígeno-específico