RESUMO
BACKGROUND & AIMS: Impaired mucosal defense plays an important role in the pathogenesis of Crohn's disease (CD), one of the main subtypes of inflammatory bowel disease (IBD). Deleted in malignant brain tumors 1 (DMBT1) is a secreted scavenger receptor cysteine-rich protein with predominant expression in the intestine and has been proposed to exert possible functions in regenerative processes and pathogen defense. Here, we aimed at analyzing the role of DMBT1 in IBD. METHODS: We studied DMBT1 expression in IBD and normal tissues by quantitative reverse transcription-polymerase chain reaction, immunohistochemistry, and mRNA in situ hybridization. Genetic polymorphisms within DMBT1 were analyzed in an Italian IBD case-control sample. Dmbt1(-/-) mice were generated, characterized, and analyzed for their susceptibility to dextran sulfate sodium-induced colitis. RESULTS: DMBT1 levels correlate with disease activity in inflamed IBD tissues. A highly significant fraction of the patients with IBD displayed up-regulation of DMBT1 specifically in the intestinal epithelial surface cells and Paneth cells. A deletion allele of DMBT1 with a reduced number of scavenger receptor cysteine-rich domain coding exons is associated with an increased risk of CD (P = .00056; odds ratio, 1.75) but not for ulcerative colitis. Dmbt1(-/-) mice display enhanced susceptibility to dextran sulfate sodium-induced colitis and elevated Tnf, Il6, and Nod2 expression levels during inflammation. CONCLUSIONS: DMBT1 may play a role in intestinal mucosal protection and prevention of inflammation. Impaired DMBT1 function may contribute to the pathogenesis of CD.
Assuntos
Doença de Crohn/genética , Doença de Crohn/fisiopatologia , Deleção de Genes , Mucosa Intestinal/fisiopatologia , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Proteínas de Ligação ao Cálcio , Estudos de Casos e Controles , Criança , Doença de Crohn/induzido quimicamente , Proteínas de Ligação a DNA , Sulfato de Dextrana , Suscetibilidade a Doenças , Éxons/genética , Feminino , Humanos , Interleucina-6/metabolismo , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patologia , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Mucinas/genética , Mucinas/fisiologia , Proteína Adaptadora de Sinalização NOD2/metabolismo , RNA Mensageiro/metabolismo , Fatores de Risco , Fator de Necrose Tumoral alfa/metabolismo , Proteínas Supressoras de Tumor , Regulação para Cima/genéticaRESUMO
Two lactoferrampin (LFampin) peptides derived from bovine lactoferrin were compared with respect to their bactericidal activities. LFampin 265-284 killed a set of Gram-positive bacteria that were resistant to LFampin 268-284. The presence of 265Asp-Leu-267Ile did not simply lead to an overall increased potency, since higher concentrations of LFampin 265-284 than LFampin 268-284 were needed to kill the Gram-negative bacteria that were tested. The Asp-Leu-Ile sequence enhances the propensity of LFampin to adopt an alpha-helix, as shown by circular dichroism spectroscopy. These results suggest that the helical conformation of the peptide is an important determinant of the susceptibility of Gram-positive bacteria.
Assuntos
Antibacterianos/metabolismo , Lactoferrina/metabolismo , Lactoglobulinas/metabolismo , Fragmentos de Peptídeos/metabolismo , Peptídeos/metabolismo , Sequência de Aminoácidos , Animais , Bovinos , Dicroísmo Circular , Lactoferrina/química , Lactoglobulinas/química , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Fragmentos de Peptídeos/química , Peptídeos/químicaRESUMO
In order to analyze the clinical potential of two antimicrobial peptides, human lactoferrin 1-11 (hLF1-11) and synthetic histatin analogue Dhvar-5, we measured the killing effect on bacteria, and the potential toxicity on erythrocytes and bone cells. The antimicrobial activity was determined in a killing assay on six strains, including methicillin resistant Staphylococcus Aureus. The effect on human erythrocytes and MC3T3 mouse bone cells was measured with a hemolysis assay and a viability assay, respectively. Both hLF1-11 and Dhvar-5 dose-dependently killed all bacterial strains, starting at concentrations of 6 microg/mL. hLF1-11 had no effect on mammalian cells at concentrations up to 400 microg/mL, but Dhvar-5 induced significant hemolysis (37% at 200 microg/mL) and bone cell death (70% at 400 microg/mL). This indicates that both peptides are able to kill various resistant and non-resistant bacteria, but Dhvar-5 may exert a cytotoxic effect on host cells at higher concentrations.