phosphorus-radioisotopes and Crohn-Disease

The cause of Crohn's disease (CD) remains poorly understood. Counterintuitively, these patients possess an impaired acute inflammatory response, which could result in delayed clearance of bacteria penetrating the lining of the bowel and predispose to granuloma formation and chronicity. We tested this hypothesis in human subjects by monitoring responses to killed Escherichia coli injected subcutaneously into the forearm. Accumulation of (111)In-labeled neutrophils at these sites and clearance of (32)P-labeled bacteria from them were markedly impaired in CD. Locally increased blood flow and bacterial clearance were dependent on the numbers of bacteria injected. Secretion of proinflammatory cytokines by CD macrophages was grossly impaired in response to E. coli or specific Toll-like receptor agonists. Despite normal levels and stability of cytokine messenger RNA, intracellular levels of tumor necrosis factor (TNF) were abnormally low in CD macrophages. Coupled with reduced secretion, these findings indicate accelerated intracellular breakdown. Differential transcription profiles identified disease-specific genes, notably including those encoding proteins involved in vesicle trafficking. Intracellular destruction of TNF was decreased by inhibitors of lysosomal function. Together, our findings suggest that in CD macrophages, an abnormal proportion of cytokines are routed to lysosomes and degraded rather than being released through the normal secretory pathway.

Topics: Adult; Aged; Crohn Disease; Cytokines; Escherichia coli; Female; Gene Expression Profiling; Humans; Indium Radioisotopes; Linear Models; Macrophages; Male; Middle Aged; Neutrophils; Oligonucleotide Array Sequence Analysis; Phosphorus Radioisotopes; RNA, Messenger; Tumor Necrosis Factor-alpha

Topics: Crohn Disease; Female; Humans; Magnetic Resonance Imaging; Middle Aged; Osteoarthropathy, Secondary Hypertrophic; Phosphorus Radioisotopes

The methods of immunoselection and electrophoretic analysis of [32P]-labelled nucleic acids have been applied to the problem of defining Crohn's disease (CD) specific antigen associated DNA or RNA, with the intention of identifying a presumptive aetiological microbial agent. Mesenteric lymph node derived cells from CD and control gastrointestinal disease cases were cultured in vitro with [32P] orthophosphate after mitogenic stimulation with phytohaemaglutinin and pokeweed mitogen. Total cell lysates were immunoprecipitated with CD and control serum IgG fractions and immune complexes recovered with pansorbin. Antigen associated [32P]-labelled nucleic acids were phenol/chloroform extracted and analysed by electrophoresis on polyacrylamide and agarose gels. No immunoprecipitated nucleic acid specific to CD tissues could be detected and no differences in antigen recognition between CD and control serum IgG were observed. No evidence was obtained for nucleic acid containing antigens either of the autoimmune type or of possible viral or microbial origin in CD mesenteric lymph nodes.

Topics: Antigen-Antibody Reactions; Antigens; Crohn Disease; DNA; Electrophoresis, Agar Gel; Electrophoresis, Polyacrylamide Gel; Humans; Immunoglobulin G; Lymph Nodes; Mesentery; Phosphorus Radioisotopes; RNA