Pathologic Changes in Mice Induced by Subtilase Cytotoxin, a Potent NewEscherichia coliAB₅Toxin That Targets the Endoplasmic Reticulum

Abstract

Subtilase cytotoxin (SubAB) is the prototype of a recently discovered AB(5) cytotoxin family produced by certain strains of Shiga toxigenic Escherichia coli (STEC). The catalytic A subunit is a highly specific subtilase-like serine protease that cleaves the endoplasmic reticulum chaperone BiP. The toxin is lethal for mice, but the pathology it induces is poorly understood. Here, we show that intraperitoneal injection of SubAB causes microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment in mice--characteristics typical of Shiga toxin-induced hemolytic uremic syndrome. SubAB caused extensive microvascular thrombosis and other histologic damage in the brain, kidneys, and liver, as well as dramatic splenic atrophy. Peripheral blood leukocyte levels were increased at 24 h; there was also significant neutrophil infiltration in the liver, kidneys, and spleen and toxin-induced apoptosis at these sites. These findings raise the possibility that SubAB directly contributes to pathology in humans infected with strains of STEC that produce both Shiga toxin and SubAB.

Decreased ER-associated degradation of α-TCR induced by Grp78 depletion with the SubAB cytotoxin

“…The first population represents the cells which succumbed to the initial insult, while the latter population likely represent the cells which have successfully mounted UPR and survived. Our results contrast with the effects of SubAB on experimental mice, where evidence of increased apoptosis was detected in different organs 24 and 48 h following intraperitoneal SubAB injection (Wang et al, 2007).…”

“…Since SubAB is cytotoxic to Vero cells (Morinaga et al, 2007;Paton et al, 2004;Paton et al, 2006) and leads to increased apoptosis in many organs following intraperitoneal injection in mice (Wang et al, 2007), we therefore explored whether SubAB induces apoptotic features in human cells. In HeLa cells, SubAB induced activation of procaspase 3 as evidenced by cleavage of PARP and detection of trace amounts of cleaved caspase 3.…”

“…HUS is the most common cause of acute renal failure in infants and young children, and is a substantial cause of acute mortality and chronic morbidity, in particular in underdeveloped countries with poor sanitary conditions and inappropriate hospital care (Siegler and Oakes, 2005). Injection of purified SubAB into experimental mice induced their demise after development of symptoms resembling HUS pathology, raising the possibility that SubAB contributes to HUS pathogenesis in humans (Wang et al, 2007). A preexisiting infection with human CMV, which induces ER stress, was shown to prevent the cytotoxic effects of SubAB in human fibroblasts (Buchkovich et al, 2008).…”

“…SubB also directs internalization of the toxin and retrograde trafficking to the ER in a clathrin-dependent fashion (Chong et al, 2007). HUS is a life-threatening complication of STEC infection characterized by microangipathic hemolytic anemia, thrombocytopenia and renal failure, which can be reproduced in experimental mice by injection of purified SubAB (Wang et al, 2007). The A subunit of SubAB specifically cleaves BiP depleting cellular stores of this ER chaperone within 20-30 min upon addition to cell culture, an activity which is completely abolished by the Ser272Ala mutation of the A subunit (Paton et al, 2006).…”

Bioengineered bugs expressing oligosaccharide receptor mimics: Toxin-binding probiotics for treatment and prevention of enteric infections

“…20 Expression of the GM2 mimic required introduction of the Neisseria β1-4galactosyltransferase gene lgtE, as well as an α2-3sialyltransferase (cstII), and a β1-4N-acetylgalactosaminyltransferase gene (cgtA) from Campylobacter jejuni NCTC11168, along with the UDP-GalNAc-4-epimerase gene (gne) from E. coli O113 on two separate plasmids. 24 Although SubAB is highly lethal when injected into mice, causing massive thrombotic microangiopathy and multiple organ damage, 20,25 its contribution to human disease is unproven. However, a combination of the Gb 3 and GM2 mimic probiotics is likely to be effective against STEC strains that produce both Stx and SubAB.…”