A rabbit model of toxic shock syndrome that uses a constant, subcutaneous infusion of toxic shock syndrome toxin 1

Abstract

We have developed a rabbit model of toxic shock syndrome that uses a subcutaneous infusion pump to administer toxic shock syndrome toxin 1 (TSST-1). A dose of 150 ,ug, infused at a constant rate over a period of 7 days, resulted in a characteristic illness highlighted by fever, conjunctival hyperemia, cachexia, and lethargy. The illness was uniformly fatal, with a mean interval until death of 3.2 ± 0.4 days. Serial determinations of serum chemistries confirmed the multisystem nature of this illness. Rabbits developed profound hypocalcemia, with levels falling from 15.5 ± 0.2 to 7.6 ± 0.4 mg/dl under the influence of TSST-1. Blood urea nitrogen and creatinine rose dramatically, in the setting of oliguria or anuria. Serum glutamicpyruvic transaminase was the most reliable indicator of hepatic dysfunction, with the mean rising from 48 U/liter before administration of TSST-1 to 546 U/liter among rabbits surviving 2 days of the infusion. Creatine phosphokinase also rose dramatically in 10 of 16 rabbits. Rabbits demonstrated relative neutrophilia and lymphopenia as well as an increase in the partial thromboplastin time. Histopathologic examination demonstrated disease of multiple organs, particularly the liver, spleen, and lymph nodes, all of which demonstrated inflammation, thrombosis, hemorrhage, and erythrophagocytosis. The concurrent administration of prednisolone with TSST-1 prevented death in four of four rabbits and greatly lessened the morbidity. Rabbits were not protected from morbidity or mortality by the concurrent administration of polymyxin B. We believe that a constant, subcutaneous infusion of TSST-1 in rabbits provides a reproducible model for studying the pathogenesis of TSS.

Analysis of the early response to TSST-1 reveals Vβ-unrestricted extravasation, compartmentalization of the response, and unresponsiveness but not anergy to TSST-1

“…Serum calcium declined, whereas blood urea nitrogen, serum creatinine, and serum glutamic pyruvic transaminase were highly elevated after application of TSST-1. At necropsy, most rabbits had mottled, congested livers, dark red cervical, thoracic, and mesenteric lymph nodes, dark, congested thymuses and spleens, and mottled, congested lungs [9]. The histological changes seen in tissues of rabbits infected with TSST-1-negative S. aureus, engineered by phage-transfer to express the TSST-1 gene and thus, produce the toxin, were remarkably similar to those described in tissues from human patients with TSS [11,13].…”

“…For the study of tissue-specific cytokine expression, animal models are mandatory. It is well documented that humans and rabbits are much more susceptible to the effects of sAg as compared with mice [7][8][9].…”

Activation of mouse liver natural killer cells and NK1.1+T cells by bacterial superantigen-primed Kupffer cells

“…17 Histological examinations revealed both in humans and mammals that superantigens induce severe inflammation in the kidney (tubular necrosis) and lung (congestion and hemorrhage). [2][3][4] The liver was also infiltrated by lymphocytes, and many centrilobular necroses were seen, thus resulting a marked elevation of the plasma aspartate transaminase levels. 3 Several studies have reported bacterial superantigens to stimulate certain V␤ T cells in both mice and humans.…”

“…Bacterial superantigens induce toxic shock syndrome and sometimes cause multiple organ failure. [1][2][3][4] Bacterial superantigens are known to bind major histocompatibility complex (MHC) class II molecules of monocytes/macrophages and B cells and broadly activate certain V␤ T cells through their T-cell receptors (TCR) based on the type of bacterial superantigen. 1,5 Superantigen-activated macrophages produce several proinflammatory cytokines and activate T cells to produce interferon gamma (IFN-␥) and interleukin-2 (IL-2), and these immunological events are believed to be involved in the toxic shock syndrome.…”

“…Thirty-three percent Percoll solution is critical because activated liver MNC have a lower density than resting liver MNC, and a usual 40% Percoll solution will lose activated liver MNC. The pellet was resuspended in red blood cell-lysis solution (140 mmol/L NH 4 Cl, 1 mmol/L ethylenediaminetetraacetic acid, 100 mmol/L Tris [pH 7.3]), then was washed twice in 10% fetal bovine serum (FBS)-RPMI 1640 medium. The number of liver MNC yield was 3 to 4 ϫ 10 6 per mouse.…”