Introduction T spiralis infection leads to a T cell-dependent enteropathy characterised by villus atrophy, crypt hyperplasia and an increase in Paneth and goblet cells. Paneth cells express a number of antimicrobial peptides and proteins. Our aim was to investigate changes in the expression of cationic antimicrobial peptides and proteins that are normally expressed by Paneth cells.
Methods Small intestinal epithelial cells were isolated from control mice and those infected with T spiralis. Concentrated cell extracts (in acetic acid) were studied by acid urea-polyacrylamide gel electrophoresis (AU-PAGE) and Western blot analysis. Samples with similar protein concentrations were used to assess antimicrobial activity against Escherichia coli, after 5 h of incubation at 37°C, using the following equation: antimicrobial activity = [(OD620 of control solution−OD620 of sample)/OD620 of control solution] ×100.
Results The establishment of infection with the nematode was confirmed by the presence of worms in the small intestinal lumen, changes in mucosal architecture and increase in Paneth and goblet cell numbers. In contrast to controls, AU-PAGE analysis of Paneth cell-containing small intestinal epithelial cell extracts from T spiralis-infected mice showed two prominent bands. AU-PAGE-Western blot and amino acid sequence analyses identified one of these bands to be secretory phospholipase A2. Sequences for cryptdins were detected in the second prominent band. Acid extracts of epithelial cells isolated from T spiralis-infected mice showed significantly greater antimicrobial activity, compared to those from control mice [mean 54.7 (SEM 8.7)% vs 7.3 (3.5)%; p=0.001].
Conclusion Following T spiralis infection, there was an increase in small intestinal epithelial expression of secretory phospholipase A2 and cryptdins. Enhanced production of these Paneth cell-derived peptides is likely to mediate greater antimicrobial activity against luminal bacteria in T spiralis-infected small intestine.
Competing interests None declared.
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