The Effect of T-2 Toxin on the Acute Phase Reaction in Mice

In vivo effects of T-2 mycotoxin on synthesis of proteins and DNA in rat tissues

Rats were given an ip injection of T-2 mycotoxin (T-2), the T-2 metabolite, T-2 tetraol (tetraol), or cycloheximide. Serum, liver, heart, kidney, spleen, muscle, and intestine were collected at 3, 6, and 9 hr postinjection after a 2-hr pulse at each time with [14C]leucine and [3H]thymidine. Protein and DNA synthesis levels in rats were determined by dual-label counting of the acid-precipitable fraction of tissue homogenates. Rats given a lethal dose of T-2, tetraol, or cycloheximide died between 14 and 20 hr. Maximum inhibition of protein synthesis at the earliest time period was observed in additional rats given the same lethal dose of the three treatments and continued for the duration of the study (9 hr). With sublethal doses of T-2 or tetraol, the same early decrease in protein synthesis was observed but, in most of the tissues, recovery was seen with time. In the T-2-treated rats. DNA synthesis in the six tissues studied was also suppressed, although to a lesser degree. With sublethal doses, complete recovery of DNA synthesis took place in four of the six tissues by 9 hr after toxin exposure. The appearance of newly translated serum proteins did not occur in the animals treated with T-2 mycotoxin or cycloheximide, as evidenced by total and PCA-soluble serum levels of labeled leucine. An increase in tissue-pool levels of free leucine and thymidine in response to T-2 mycotoxin was also noted. T-2 mycotoxin, its metabolite, T-2 tetraol, and cycloheximide cause a rapid inhibition of protein and DNA synthesis in all tissue types studied. These results are compared with the responses seen in in vitro studies.

Impaired murine resistance to Salmonella typhimurium following oral exposure to the trichothecene T-2 toxin

On orally exposing Salmonella-resistant C3H/HeN mice to the trichothecene T-2 toxin (1 mg/kg body weight), challenging with Salmonella typhimurium, and continuing to dose with T-2 toxin on alternate days for 3 wk, the LD50 for the organism decreased by five orders of magnitude, in comparison with control mice not treated with T-2 toxin. In the absence of S. typhimurium, T-2 toxin did not cause lethal effects when administered at this level. Increased mortality in response to S. typhimurium challenge was dependent on T-2 toxin dose in the range 0 to 1 mg/kg for this regimen. The toxin did not significantly affect intestinal infection but did increase splenic counts in mice challenged with a range of S. typhimurium doses and also accelerated body-weight loss in infected animals. Mice challenged with the organism exhibited similar mortality when T-2 toxin treatment was begun 1 day prior to infection or at 5 or 9 days after infection. A time-related decrease in mortality, relative to that found for the standardized co-challenge described above, was observed when T-2 toxin administration was begun at 9, 13 or 23 days after infection. The results indicated that, depending on the challenge dose of the organism, both early and late phase acquired immune response to S. typhimurium could be impaired by T-2 toxin. Markedly enhanced susceptibility to gram-negative bacterial infection is another manifestation of trichothecene toxicity and may be an important aetiological factor in animal health problems that are associated with these mycotoxins.

T-2 toxin effects on the serum amyloid P-component (SAP) response of Listeria monocytogenes- and Salmonella typhimurium-infected mice

T-2 mycotoxin, given to mice 4 days prior to an intraperitoneal inoculation with Listeria monocytogenes EGD, increases the acute phase response as determined by measurements of serum amyloid protein-P (SAP), and decreases the severity of the infection. Conversely, when T-2 toxin is given simultaneously with L. monocytogenes the mice become more susceptible to the infection, and the SAP levels attained are diminished relative to the non-toxin-treated Listeria-infected controls. T-2 toxin given 4 days prior to intraperitoneal inoculation with Salmonella typhimurium had no effect on either the resultant infection or SAP levels. These results indicate that T-2 toxin modulates the acute phase response to infection, and are consistent with an in vivo role for SAP as a nonspecific host resistance factor.