Effects of the excretory/secretory products of six nematode species, parasites of the digestive tract, on the proliferation of HT29-D4 and HGT-1 cell lines.

The excretory/secretory (ES) products of the nematode parasite Trichostrongylus colubriformis have been found to increase the in vitro proliferation of the epithelial cell line HT29-D4. To assess the specificity of this effect, ES products from other trichostrongyle species were tested on colonic (HT29-D4) and gastric (HGT-1) tumour cell lines. Adult worms of six different nematode species, parasites of the stomach or the small intestine of ruminants, were incubated in vitro in Dulbecco's Modified Eagle's Medium for 24 h. The conditioned media were then added at different concentrations to the culture medium of the two cell lines. A stimulation of the HT29-D4 cell growth occurred with the ES products of two parasite species of the small intestine, at the concentrations of 0.1 microgram protein/ml (Trichostrongylus vitrinus) and 1.0-5.0 micrograms/ml (Cooperia curticei). Inversely, a decrease in cell number was observed with the ES products of another intestinal species, Nematodirus battus at concentrations of 1.0-5.0 micrograms/ml. With the ES products of the abomasal nematodes, a proliferation of HT29-D4 cells was obtained at 0.25-5.0 micrograms/ml with ES products of Teladorsagia circumcincta but no significant effect was observed for Haemonchus contortus. On the tumoral gastric cell line HGT-1, the ES products from the 6 nematode species gave a similar stimulative effect. These in vitro results suggest that nematode parasite species secrete or excrete component(s) which could affect the epithelial regeneration of the host digestive tract.