Changes in the Expression and Distribution of Claudins, Increased Epithelial Apoptosis, and a Mannan-Binding Lectin-Associated Immune Response Lead to Barrier Dysfunction in Dextran Sodium Sulfate-Induced Rat Colitis

BACKGROUND/AIMS: This animal study aimed to define the underlying cellular mechanisms of intestinal barrier dysfunction. METHODS: Rats were fed 4% with dextran sodium sulfate (DSS) to induce experimental colitis. We analyzed the sugars in 24-hour urine output by high pressure liquid chromatography. The expression of claudins, mannan-binding lectin (MBL), and MBL-associated serine proteases 2 (MASP-2) were detected in the colonic mucosa by immunohistochemistry; and apoptotic cells in the colonic epithelium were detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method assay. RESULTS: The lactulose and sucralose excretion levels in the urine of rats with DSS-induced colitis were significantly higher than those in the control rats. Mannitol excretion was lower and lactulose/mannitol ratios and sucralose/mannitol ratios were significantly increased compared with those in the control group (p<0.05). Compared with the controls, the expression of sealing claudins (claudin 3, claudin 5, and claudin 8) was significantly decreased, but that of claudin 1 was increased. The expression of pore-forming claudin 2 was upregulated and claudin 7 was downregulated in DSS-induced colitis. The epithelial apoptotic ratio was 2.8%+/-1.2% in controls and was significantly increased to 7.2%+/-1.2% in DSS-induced colitis. The expression of MBL and MASP-2 in the intestinal mucosa showed intense staining in controls, whereas there was weak staining in the rats with colitis. CONCLUSIONS: There was increased intestinal permeability in DSS-induced colitis. Changes in the expression and distribution of claudins, increased epithelial apoptosis, and the MASP-2-induced immune response impaired the intestinal epithelium and contributed to high intestinal permeability.

The Role of Barrier Dysfunction and Change of Claudin Expression in Inflammatory Bowel Disease

No abstract available.

Associação da capacidade de ligação e níveis séricos da Lectina de Ligação à Manose (MBL) à gravidade da cardiomiopatia chagásica crônica / Association of binding capacity and serum levels of mannose-binding lectin (MBL) with the severity of chronic Chagas cardiomyopathy

A doença de Chagas (DC) é uma infecção causada pelo Trypanosoma cruzi, é considerada endêmica na América Latina, afetando cerca de 15 milhões de indivíduos. Estima-se que cerca de 30 por cento das pessoas infectadas desenvolvem cardiomiopatia chagásica crônica, entre 5 à 30 anos após a infecção aguda. Com o objetivo de diferenciar portadores de DC com a evolução potencial para formas clínicas crônicas graves, pesquisadores tentam estabelecer marcadores biológicos de prognóstico da evolução da doença por meio de marcadores imunológicos. Lectina de Ligação a Manose (MBL) é uma molécula de reconhecimento de que a imunidade inata que desempenha um papel fundamental na defesa do hospedeiro, mediando a fagocitose e a destruição dos agentes patogénicos mediada pelo complemento. Existem vários estudos que enfatizam a relevância da MBL em diferentes doenças infecciosas, inflamatórias e auto-imunes. A deficiência de MBL pode implicar na susceptibilidade bacteriana, fúngica, por protozoários e infecções virais. Nosso objetivo foi investigar a associação dos níveis séricos e atividade de ligação da MBL com cardiomiopatia chagásica crônica, através da formação de um índice, que inferiu as moléculas ligantes. Para isso, foi feita uma avaliação, através de ELISA, dos níveis séricos e da capacidade de ligação da MBL, para formação desse índice de relação (Mbi), em pacientes crônicos assintomáticos e cardíacos da doença de Chagas. O estudo incluiu 77 pacientes portadores DC indeterminados (n = 19), cardíaco grave (n = 29) e cardíaco leve (n = 29)...

High levels of serum mannose-binding lectin are associated with the severity of clinical signs of leptospirosis

The clinical heterogeneity observed in leptospirosis may be associated with host factors or bacteria virulence. Human serum mannose-binding lectin (MBL) recognizes many pathogens, and low levels of this lectin are associated with susceptibility to infection. MBL is also implicated in the modulation of the inflammatory process. We determined the levels of serum MBL during leptospirosis infection. A double-antibody sandwich ELISA was used to detect the immunoreactive serum MBL. The ELISA plates were coated with monoclonal antibody to MBL and bound MBL or recombinant human MBL were detected by rabbit anti-human MBL serum. HRPO-conjugated goat anti-rabbit antibody was used for detection of the reaction. Two groups of patients seen at referral hospitals in Recife, PE, Brazil, were divided according to the year of infection, 2001 (N = 61) or 2002 (N = 57) and compared in terms of disease severity and levels of serum MBL. A group of healthy volunteers (N = 97) matched by age, gender, and ethnic background was used as control. Patients infected in 2001 had more severe outcomes than those infected in 2002, including jaundice, hemorrhage, respiratory alteration, and renal complication (P = 0.0009; chi-square test). The frequency of patients producing serum MBL >1000 ng/mL was higher in the 2001 group than in the 2002 and control groups (P < 0.01), suggesting an association of MBL level with disease severity. The involvement of MBL and genetic variation of the MBL2 gene should be further evaluated to establish the role of this lectin in the pathogenesis of leptospirosis.

Avaliação do gene estrutural da proteína de ligação à lectina (MBL) e sua relação com a transmissão materno-fetal do HIV / Mannan-binding lecting (MBL) and its correlation with maternal-to-child HIV transmission

Avaliou-se a expressão do gene mbl2 em 79 crianças e suas mães HIV positivas com o objetivo de avaliar a sua influência na transmissão vertical. Os pacientes divididos em dois grupos: crianças HIV positivas e suas mães (n=18) e crianças HIV negativas e suas mães (n=61) foram avaliados pelo CH50 e AP50 (ensaios hemolíticos), dosagem e avaliação funcional da MBL, ativação da cascata terminal do complemento (ELISA) e o gene mbl2 (PCR). Os resultados não mostraram diferença significante entre os níveis séricos, atividade funcional e o gene da MBL entre os grupos, excluindo a sua influência sobre a transmissão materno-fetal do HIV. Apoio: FAPESP e DAAD / It was evaluated the mbl2 gene expression in 79 children and their HIV positive mothers with the aim to evaluate its influence on mother-to-child HIV. The patients were divided in two groups: HIV positive children and their mothers (n=18) and HIV negative children and their mothers (n=61) were evaluated by CH50 and AP50 (hemolytic assays); levels and functional MBL and terminal complement cascade (ELISA) and mbl2 gene (PCR). The results didn’t show significant difference amons serum levels, functional activities and MBL gene between the groups, excluding the influence in the mother-to child HIV transmission...