The mycotoxin deoxynivalenol promotes uptake ofSalmonellaTyphimurium in porcine macrophages, associated with ERK1/2 induced cytoskeleton reorganization

Abstract

-Both the mycotoxin deoxynivalenol (DON) and Salmonella Typhimurium are major issues in swine production. This study aimed at examining the interaction between DON and Salmonella Typhimurium at the level of the porcine innate immune system, represented by macrophages. First, we assessed the direct cytotoxic effect of DON on porcine macrophages. Incubation with 0.25 lg/mL of DON or higher resulted in a significant cytotoxic effect after 24 h of incubation. Secondly, the direct toxic effect of DON on the growth and on the expression of Salmonella pathogenicity island 1 (SPI-1) and SPI-2 virulence genes of Salmonella Typhimurium was determined. At low non-cytotoxic concentrations, as can be found in the serum of pigs, DON did not have any effect on either growth or virulence gene expression of Salmonella Typhimurium. However, when the invasion and intracellular survival of Salmonella Typhimurium in macrophages preexposed to 0.025 lg/mL of DON was examined, DON significantly promoted the uptake of Salmonella Typhimurium into macrophages. The enhanced uptake coincided with marked F-actin reorganization of the cells, which was due to the activation of extracellular signal-regulated protein kinase 1/2 (ERK1/2). These results suggest that low but relevant concentrations of DON modulate the innate immune system and could thus increase the susceptibility of pigs to infections with Salmonella Typhimurium.deoxynivalenol / Salmonella Typhimurium / pig / macrophage / cytoskeleton

The Mycotoxin Deoxynivalenol Potentiates Intestinal Inflammation by Salmonella Typhimurium in Porcine Ileal Loops

“…The enhanced susceptibility of intestinal epithelial cells to Salmonella invasion and translocation is in accordance with our previous findings that concentrations of DON as low as 0.025 µg/mL enhance the uptake of Salmonella Typhimurium in porcine macrophages associated with ERK1/2 induced cytoskeletal reorganization [51]. Results of our present and previous studies thus indicate that DON may influence both the intestinal and systemic phase of a Salmonella Typhimurium infection, leading to increased host susceptibility to this pathogen.…”

T-2 toxin induced Salmonella Typhimurium intoxication results in decreased Salmonella numbers in the cecum contents of pigs, despite marked effects on Salmonella-host cell interactions

“…In vitro treatment of the host cells with T-2 toxin rendered them more susceptible to invasion, in a SPI-1 independent manner, and increased the transepithelial passage of the bacterium (Figures 4 and 6). This is in accordance with Vandenbroucke et al who showed that DON promotes the invasion and translocation of Salmonella Typhimurium over porcine host cells, by a mechanism that is not SPI-1 dependent [24,59]. The results obtained by Maresca et al also confirm our results since they pointed out that DON concentrations that do not compromise the barrier function, significantly increase the passage of non-invasive Escherichia coli bacteria through Caco-2 inserts [58].…”

“…These cytoskeletal changes are important for the uptake and the cytoplasmic transport of the bacterium, as well as for the establishment and the stability of the bacterial replicative niche, also called Salmonella containing vacuole (SCV) [59]. By the use of iTRAQ analysis, we demonstrated that 5 ng/mL T-2 toxin induces alterations in the expression of proteins that are involved in the cytoskeleton formation of differentiated IPEC-J2 cells.…”

“…Furthermore, T-2 toxin causes an increased expression of thymosin beta-10, an actin-sequestering protein involved in cytoskeleton organization and biogenesis [63], of cysteine and glycine-rich protein 1 isoform 1, a regulator for actin filament bundling [64] and of profilin, an actin-binding protein that can sequester G-actin or actively participate in filament growth [65]. According to Vandenbroucke et al, low concentrations of DON can modulate the cytoskeleton of macrophages resulting in an enhanced uptake of Salmonella Typhimurium in porcine macrophages [59]. The observed changes in protein expression are not sufficient to induce morphological changes, as assessed with TEM (Figure 7).…”

Persistence of Yersinia ruckeri in trout macrophages

“…The cytotoxic effect of Y. ruckeri on rainbow trout head kidney macrophages was assessed using a staining with ethidium bromide monoazide (EMA, SigmaeAldrich) and Hoechst (Invitrogen, Paisley, Scotland) as described previously [26]. EMA binds to nucleic acid in cells with damaged membranes and was used for the detection of non-viable cells, which can be either late apoptotic or necrotic.…”