Biological Activity of Desulfovibrio desulfuricans Lipopolysaccharides Evaluated via Interleukin-8 Secretion by Caco-2 Cells

Background: Although Desulfovibrio desulfuricans species, besides existing in the natural environment, is also found in the human digestive tract, no information is currently available on its role in the intestinal ecosystem and its activity in regard to the intestinal mucosa. Bacterial products (lipopolysaccharides, LPSs) are generally known for their ability to trigger inflammatory response by stimulating cytokine expression, such as interleukin-8 (IL-8). Methods: Colonic Caco-2 cells were exposed to LPSs isolated from the soil type and intestinal wild strains of D. desulfuricans bacteria. The amount of IL-8 secreted was measured by ELISA. The effects of sodium butyrate and cell preincubation with sodium butyrate on the IL-8 secretion in response to LPSs were also analysed. Results: LPSs from D. desulfuricans down-regulated IL-8 secretion by the cells. Incubation of these cells with butyrate alone resulted in a dose-dependent stimulation of IL-8 release. Butyrate also modulated IL-8 secretion by cells stimulated with LPSs. Conclusions: Our findings suggest the lack of inflammatory response of intestinal mucosa in the presence of LPSs of D. desulfuricans. This response can be conditioned by the natural bacterial product, butyrate, which exerts a stimulatory effect on the IL-8 secretion and modulates its release in response to LPSs.